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ifis publishing ifis academic publishing company not-for-profit organisation operating sciences regulations food health based reading ifis produces online bibliographic databases fsta resource company offered since 1969 along escalex launched 2017 fsta food science technology abstracts includes 1.4 million scientific non-predatory records trusted sources related disciplines surrounding food beverages ifis also produces association wiley blackwell dictionary food science technology second edition not-for-profit charitable organisation ifis offers access researchers developing countries research4life programmes hinari agora escalex created collaboration molecular connections launched april 2017 allows search retrieval food beverage food law information various geographies across globe originally known international food information service ifis established 1968 collaboration four organisations company originally based lane end house shinfield though recently moved granary bridge farm arborfield fsta bibliographic abstracting indexing database scientific technological information relating food beverages nutrition contains 1.3 million indexed records full-text links available covering 5,475 active historical journals books trade publications reviews conference proceedings reports patents standards database updated weekly records indexed ifis thesaurus containing 12,346 food science keywords curated structured hierarchies resource used researchers industry practitioners students contains information sources 29 languages sourced publishers 60 countries coverage includes major commodities food beverage industry related applied pure sciences pet foods food psychology food economics food safety fsta accessed ebscohost ovid proquest dialog stn web science
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Databases
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music kit music kit software package next computer system first developed david a. jaffe julius o. smith supported motorola 56001 dsp included next computer motherboard also first architecture unify music-n midi paradigms thus combined generality former interactivity performance capabilities latter music kit integrated sound kit first demonstrated 1988 davies symphony hall 1.0 release shipped 1989 next computer included objective-c library creating music sound applications score language included expression evaluation midi sound dsp drivers several command-line utilities simple score-playing application called scoreplayer music kit integrated variety music applications including finale creation station also used video games even document processors 2.0 release next computer included additional bundled applications including ensemble fractal-based improvisation tool developed michael mcnabb others involved next music kit project included douglas fulton documentation demos doug keislar third-party support greg kellogg drivers lee boynton drivers sound kit dana massie development addition consultants brought early included andy moorer dsp software architecture roger dannenberg data structures john strawn dsp software 1992 next 3.0 release music kit un-bundled next software released copyrighted open source package stanford center computer research music acoustics ccrma julius o. smith professor stanford university hired david a. jaffe consultant continue develop music kit among additions time support airel quintprocessor five-dsp board nextcube support audio directly via dsp56001 serial port brought back next cube support nextstep use dsp processing using turtle beach dsp56001 card set eight motorola evaluation boards combined chassis prototype frankenstein platform used sondius program stanford office technology licensing develop physical models musical instruments addition jaffe hired third party add midi time code support music kit sondius group later spun independent company staccato systems inc. funding yamaha stanford university staccato systems inc. acquired analog devices 2000 recent ports music kit done leigh smith stephen brandon
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Operating systems
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socket 479 socket 479 mpga479m cpu socket intel pentium celeron mobile processors normally used laptops also used tualatin-m pentium iii processors official naming intel µfcpga µpga479m exist multiple electrically incompatible mechanically compatible processor families available pga packages using socket variants thereof even intel cpu specifications seem clear enough distinction instead use package/socket designations pga478 ppga478 1 sockets perhaps adding yet confusion pga-based cpus also available bga precisely µbga even µfcbga package 479 contacts balls populated cpu variants intel cpu specifications use designations bga479 pbga479 h-pbga479 however pointed designations denote rather cpu package socket bga variants use intended directly soldered mainboard e.g embedded system non-bga counterparts cpus use one mentioned sockets socket 479 socket 479 479 pin holes pentium processors pga package 479 pins plug zero insertion force socket 478 pins electrically connected b2 reserved depopulated micro-fcpga package although electrically mechanically similar socket 478 one pin less making impossible use pentium processor 478 board reason manufacturers like asus made drop-in boards e.g ct-479 allow use socket 479 processors chipsets employ socket pentium intel 855gm/gme/pm intel 915gm/gms/pm intel 855gme chipset supports pentium cpu intel 855gm chipset officially support 90 nm 2mb l2 cache dothan core models even though works works 400fsb 3rd party/user able overclock fsb 855gm/gme/pm support 533fsb dothan core difference 855gm chipset graphics core runs 200 mhz 855gme runs 250 mhz 2006 intel released successor socket 479 revised pinout core processor called socket m. socket placement one pin changed pentium version socket 479 socket processors physically fit socket 479 electrically incompatible versions socket479 except using ati north bridge rc415md socket supports 667 mt/s fsb intel 945pm/945gm chipsets
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Computer architecture
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database index database index data structure improves speed data retrieval operations database table cost additional writes storage space maintain index data structure indexes used quickly locate data without search every row database table every time database table accessed indexes created using one columns database table providing basis rapid random lookups efficient access ordered records index copy selected columns data table searched efficiently also includes low-level disk block address direct link complete row data copied databases extend power indexing letting developers create indexes functions expressions example index could created upper last_name would store upper-case versions codice_1 field index another option sometimes supported use partial indices index entries created records satisfy conditional expression aspect flexibility permit indexing user-defined functions well expressions formed assortment built-in functions database software includes indexing technology enables sub-linear time lookup improve performance linear search inefficient large databases suppose database contains n data items one must retrieved based value one fields simple implementation retrieves examines item according test one matching item stop finds single item multiple matches must test everything means number operations worst case n linear time since databases may contain many objects since lookup common operation often desirable improve performance index data structure improves performance lookup many different used purpose complex design trade-offs involving lookup performance index size index-update performance many index designs exhibit logarithmic log n lookup performance applications possible achieve flat 1 performance indexes used police database constraints unique exclusion primary key foreign key index may declared unique creates implicit constraint underlying table database systems usually implicitly create index set columns declared primary key capable using already-existing index police constraint many database systems require referencing referenced sets columns foreign key constraint indexed thus improving performance inserts updates deletes tables participating constraint database systems support exclusion constraint ensures newly inserted updated record certain predicate holds record used implement unique constraint equality predicate complex constraints like ensuring overlapping time ranges intersecting geometry objects would stored table index supporting fast searching records satisfying predicate required police constraint data present arbitrary order logical ordering specified index data rows may spread throughout table regardless value indexed column expression non-clustered index tree contains index keys sorted order leaf level index containing pointer record page row number data page page-organized engines row offset file-organized engines non-clustered index one non-clustered index database table clustering alters data block certain distinct order match index resulting row data stored order therefore one clustered index created given database table clustered indices greatly increase overall speed retrieval usually data accessed sequentially reverse order clustered index range items selected since physical records sort order disk next row item sequence immediately last one fewer data block reads required primary feature clustered index therefore ordering physical data rows accordance index blocks point databases separate data index blocks separate files others put two completely different data blocks within physical file multiple databases multiple tables joined referred cluster confused clustered index described records tables sharing value cluster key shall stored together nearby data blocks may improve joins tables cluster key since matching records stored together less i/o required locate cluster configuration defines data layout tables parts cluster cluster keyed b-tree index hash table data block table record stored defined value cluster key order index definition defines columns important possible retrieve set row identifiers using first indexed column however possible efficient databases retrieve set row identifiers using second greater indexed column example imagine phone book organized city first last name first name given city easily extract list phone numbers city however phone book would tedious find phone numbers given last name would look within city section entries last name databases others ’ use index phone book example composite index created columns codice_2 search giving exact values three fields search time minimal—but provide values codice_3 codice_4 search uses codice_3 field retrieve matched records sequential lookup checks matching codice_4 improve performance one must ensure index created order search columns indexes useful many applications come limitations consider following sql statement codice_7 process statement without index database software must look last_name column every row table known full table scan index database simply follows b-tree data structure smith entry found much less computationally expensive full table scan consider sql statement codice_8 query would yield email address every customer whose email address ends wikipedia.org even email_address column indexed database must perform full index scan index built assumption words go left right wildcard beginning search-term database software unable use underlying b-tree data structure words where-clause sargable problem solved addition another index created codice_9 sql query like codice_10 puts wild-card right-most part query gro.aidepikiw index reverse email_address satisfy wildcard characters used sides search word wikipedia.org index available field used rather sequential search performed takes n time bitmap index special kind indexing stores bulk data bit arrays bitmaps answers queries performing bitwise logical operations bitmaps commonly used indexes b+ trees efficient values index repeat repeat small number times contrast bitmap index designed cases values variable repeat frequently example sex field customer database usually contains three distinct values male female unknown recorded variables bitmap index significant performance advantage commonly used trees dense index databases file pairs keys pointers every record data file every key file associated particular pointer record sorted data file clustered indices duplicate keys dense index points first record key sparse index databases file pairs keys pointers every block data file every key file associated particular pointer block sorted data file clustered indices duplicate keys sparse index points lowest search key block reverse-key index reverses key value entering index e.g. value 24538 becomes 83542 index reversing key value particularly useful indexing data sequence numbers new key values monotonically increase primary index contains key fields table pointer non-key fields table primary index created automatically table created database create file must specify two things primary index 1 name primary index 2 primary index specification used index field neither ordering fields key fields assurance file organized key field primary key field one index entry every tuple data file dense index contains value indexed attribute pointer block/record indices implemented using variety data structures popular indices include balanced trees b+ trees hashes microsoft sql server leaf node clustered index corresponds actual data simply pointer data resides elsewhere case non-clustered index relation single clustered index many unclustered indices index typically accessed concurrently several transactions processes thus needs concurrency control principle indexes utilize common database concurrency control methods specialized concurrency control methods indexes exist applied conjunction common methods substantial performance gain cases index used quickly locate data record required data read words index used locate data records table return data covering index special case index contains required data field answer required data consider following table fields omitted find name id 13 index id useful record must still read get name however index id name contains required data field eliminates need look record covering indexes specific table queries join/ access across multiple tables may potentially consider covering indexes one tables covering index dramatically speed data retrieval may large due additional keys slow data insertion update reduce index size systems allow including non-key fields index non-key fields part index ordering included leaf level allowing covering index less overall index size standard defines create indexes iso sql standard cover physical aspects indexes one physical parts database conception among others like storage tablespace filegroups rdbms vendors give create index syntax specific options depend software capabilities
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Databases
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openbugs openbugs software application bayesian analysis complex statistical models using markov chain monte carlo mcmc methods openbugs open source variant winbugs bayesian inference using gibbs sampling runs microsoft windows linux well inside r statistical package versions v3.0.7 onwards designed least efficient reliable winbugs range test applications addition different licence greater range operating systems fundamental difference openbugs winbugs way expert system selects updating algorithm use class full conditional distribution node winbugs defines one algorithm possible class limit number algorithms openbugs use allowing greater flexibility extensibility user select updater used node compilation differences detailed openbugs website source code openbugs written component pascal programming language dependent component pascal libraries provided oberon microsystems part blackbox component framework development tools available open source binaries current version openbugs available microsoft windows previous version linux also run wine linux installation problems development usage questions discussed openbugs bulletin board attempts port openbugs java gardens point component pascal given favor new portable implementation called jags bugs language language specifies model code parsed openbugs creates executable compiled code generates sample posterior distribution run openbugs designed run together s-plus bugs language similar programming language openbugs works well together r r2openbugs brugs packages provides interoperability r modules help analyses
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Programming language topics
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code-division multiple access code-division multiple access cdma channel access method used various radio communication technologies cdma example multiple access several transmitters send information simultaneously single communication channel allows several users share band frequencies see bandwidth permit without undue interference users cdma employs spread spectrum technology special coding scheme transmitter assigned code cdma used access method many mobile phone standards is-95 also called cdmaone 3g evolution cdma2000 often simply referred cdma umts 3g standard used gsm carriers also uses wideband cdma w-cdma well td-cdma td-scdma radio technologies technology code-division multiple access channels long known soviet union ussr first work devoted subject published 1935 dmitry ageev shown use linear methods three types signal separation frequency time compensatory technology cdma used 1957 young military radio engineer leonid kupriyanovich moscow made experimental model wearable automatic mobile phone called lk-1 base station lk-1 weight 3 kg 20–30 km operating distance 20–30 hours battery life base station described author could serve several customers 1958 kupriyanovich made new experimental pocket model mobile phone phone weighed 0.5 kg serve customers kupriyanovich proposed device called correlator 1958 ussr also started development altai national civil mobile phone service cars based soviet mrt-1327 standard phone system weighed placed trunk vehicles high-ranking officials used standard handset passenger compartment main developers altai system vniis voronezh science research institute communications gspi state specialized project institute 1963 service started moscow 1970 altai service used 30 ussr cities cdma spread-spectrum multiple-access technique spread-spectrum technique spreads bandwidth data uniformly transmitted power spreading code pseudo-random code narrow ambiguity function unlike narrow pulse codes cdma locally generated code runs much higher rate data transmitted data transmission combined bitwise xor exclusive faster code figure shows spread-spectrum signal generated data signal pulse duration formula_1 symbol period xored code signal pulse duration formula_2 chip period note bandwidth proportional formula_3 formula_4 bit time therefore bandwidth data signal formula_5 bandwidth spread spectrum signal formula_6 since formula_2 much smaller formula_1 bandwidth spread-spectrum signal much larger bandwidth original signal ratio formula_9 called spreading factor processing gain determines certain extent upper limit total number users supported simultaneously base station user cdma system uses different code modulate signal choosing codes used modulate signal important performance cdma systems best performance occurs good separation signal desired user signals users separation signals made correlating received signal locally generated code desired user signal matches desired user code correlation function high system extract signal desired user code nothing common signal correlation close zero possible thus eliminating signal referred cross-correlation code correlated signal time offset zero correlation close zero possible referred auto-correlation used reject multi-path interference analogy problem multiple access room channel people wish talk simultaneously avoid confusion people could take turns speaking time division speak different pitches frequency division speak different languages code division cdma analogous last example people speaking language understand languages perceived noise rejected similarly radio cdma group users given shared code many codes occupy channel users associated particular code communicate general cdma belongs two basic categories synchronous orthogonal codes asynchronous pseudorandom codes digital modulation method analogous used simple radio transceivers analog case low-frequency data signal time-multiplied high-frequency pure sine-wave carrier transmitted effectively frequency convolution wiener–khinchin theorem two signals resulting carrier narrow sidebands digital case sinusoidal carrier replaced walsh functions binary square waves form complete orthonormal set data signal also binary time multiplication achieved simple xor function usually gilbert cell mixer circuitry synchronous cdma exploits mathematical properties orthogonality vectors representing data strings example binary string 1011 represented vector 1 0 1 1 vectors multiplied taking dot product summing products respective components example u b v c dot product u·v ac bd dot product zero two vectors said orthogonal properties dot product aid understanding w-cdma works vectors b orthogonal formula_10 user synchronous cdma uses code orthogonal others codes modulate signal example 4 mutually orthogonal digital signals shown figure orthogonal codes cross-correlation equal zero words interfere case is-95 64-bit walsh codes used encode signal separate different users since 64 walsh codes orthogonal signals channelized 64 orthogonal signals following example demonstrates user signal encoded decoded start set vectors mutually orthogonal although mutual orthogonality condition vectors usually constructed ease decoding example columns rows walsh matrices example orthogonal functions shown adjacent picture vectors assigned individual users called code chip code chipping code interest brevity rest example uses codes v two bits user associated different code say v. 1 bit represented transmitting positive code v 0 bit represented negative code −v example v v v 1 −1 data user wishes transmit 1 0 1 1 transmitted symbols would purposes article call constructed vector transmitted vector sender different unique vector v chosen set construction method transmitted vector identical due physical properties interference two signals point phase add give twice amplitude signal phase subtract give signal difference amplitudes digitally behaviour modelled addition transmission vectors component component sender0 code 1 −1 data 1 0 1 1 sender1 code 1 1 data 0 0 1 1 senders transmit simultaneously table describes coding steps signal0 signal1 transmitted time air add produce raw signal raw signal called interference pattern receiver extracts intelligible signal known sender combining sender code interference pattern following table explains works shows signals interfere one another decoding values greater 0 interpreted 1 values less zero interpreted 0 example decoding data0 2 −2 2 2 receiver interprets 1 0 1 1 values exactly 0 means sender transmit data following example assume signal0 1 −1 −1 1 1 −1 1 −1 transmitted alone following table shows decode receiver receiver attempts decode signal using sender1 code data zeros therefore cross-correlation equal zero clear sender1 transmit data mobile-to-base links precisely coordinated particularly due mobility handsets different approach required since mathematically possible create signature sequences orthogonal arbitrarily random starting points make full use code space unique pseudo-random pseudo-noise pn sequences used asynchronous cdma systems pn code binary sequence appears random reproduced deterministic manner intended receivers pn codes used encode decode user signal asynchronous cdma manner orthogonal codes synchronous cdma shown example pn sequences statistically uncorrelated sum large number pn sequences results multiple access interference mai approximated gaussian noise process following central limit theorem statistics gold codes example pn suitable purpose low correlation codes users received power level variance e.g. noise power mai increases direct proportion number users words unlike synchronous cdma signals users appear noise signal interest interfere slightly desired signal proportion number users forms cdma use spread-spectrum process gain allow receivers partially discriminate unwanted signals signals encoded specified pn sequence code received signals different codes code different timing offset appear wideband noise reduced process gain since user generates mai controlling signal strength important issue cdma transmitters cdm synchronous cdma tdma fdma receiver theory completely reject arbitrarily strong signals using different codes time slots frequency channels due orthogonality systems true asynchronous cdma rejection unwanted signals partial unwanted signals much stronger desired signal overwhelm leads general requirement asynchronous cdma system approximately match various signal power levels seen receiver cdma cellular base station uses fast closed-loop power-control scheme tightly control mobile transmit power theory cdma tdma fdma exactly spectral efficiency practice challenges – power control case cdma timing case tdma frequency generation/filtering case fdma tdma systems must carefully synchronize transmission times users ensure received correct time slot cause interference since perfectly controlled mobile environment time slot must guard time reduces probability users interfere decreases spectral efficiency similarly fdma systems must use guard band adjacent channels due unpredictable doppler shift signal spectrum user mobility guard bands reduce probability adjacent channels interfere decrease utilization spectrum asynchronous cdma offers key advantage flexible allocation resources i.e allocation pn codes active users case cdm synchronous cdma tdma fdma number simultaneous orthogonal codes time slots frequency slots respectively fixed hence capacity terms number simultaneous users limited fixed number orthogonal codes time slots frequency bands allocated cdm tdma fdma systems remain underutilized due bursty nature telephony packetized data transmissions strict limit number users supported asynchronous cdma system practical limit governed desired bit error probability since sir signal-to-interference ratio varies inversely number users bursty traffic environment like mobile telephony advantage afforded asynchronous cdma performance bit error rate allowed fluctuate randomly average value determined number users times percentage utilization suppose 2 n users talk half time 2 n users accommodated average bit error probability n users talk time key difference bit error probability n users talking time constant whereas random quantity mean 2 n users talking half time words asynchronous cdma ideally suited mobile network large numbers transmitters generate relatively small amount traffic irregular intervals cdm synchronous cdma tdma fdma systems recover underutilized resources inherent bursty traffic due fixed number orthogonal codes time slots frequency channels assigned individual transmitters instance n time slots tdma system 2 n users talk half time half time n users needing use n time slots furthermore would require significant overhead continually allocate deallocate orthogonal-code time-slot frequency-channel resources comparison asynchronous cdma transmitters simply send something say go air n't keeping pn signature sequence long connected system modulation schemes try minimize bandwidth signal since bandwidth limited resource however spread-spectrum techniques use transmission bandwidth several orders magnitude greater minimum required signal bandwidth one initial reasons military applications including guidance communication systems systems designed using spread spectrum security resistance jamming asynchronous cdma level privacy built signal spread using pseudo-random code code makes spread-spectrum signals appear random noise-like properties receiver demodulate transmission without knowledge pseudo-random sequence used encode data cdma also resistant jamming jamming signal finite amount power available jam signal jammer either spread energy entire bandwidth signal jam part entire signal cdma also effectively reject narrow-band interference since narrow-band interference affects small portion spread-spectrum signal easily removed notch filtering without much loss information convolution encoding interleaving used assist recovering lost data cdma signals also resistant multipath fading since spread-spectrum signal occupies large bandwidth small portion undergo fading due multipath given time like narrow-band interference result small loss data overcome another reason cdma resistant multipath interference delayed versions transmitted pseudo-random codes poor correlation original pseudo-random code thus appear another user ignored receiver words long multipath channel induces least one chip delay multipath signals arrive receiver shifted time least one chip intended signal correlation properties pseudo-random codes slight delay causes multipath appear uncorrelated intended signal thus ignored cdma devices use rake receiver exploits multipath delay components improve performance system rake receiver combines information several correlators one tuned different path delay producing stronger version signal simple receiver single correlation tuned path delay strongest signal frequency reuse ability reuse radio channel frequency cell sites within cellular system fdma tdma systems frequency planning important consideration frequencies used different cells must planned carefully ensure signals different cells interfere cdma system frequency used every cell channelization done using pseudo-random codes reusing frequency every cell eliminates need frequency planning cdma system however planning different pseudo-random sequences must done ensure received signal one cell correlate signal nearby cell since adjacent cells use frequencies cdma systems ability perform soft hand-offs soft hand-offs allow mobile telephone communicate simultaneously two cells best signal quality selected hand-off complete different hard hand-offs utilized cellular systems hard-hand-off situation mobile telephone approaches hand-off signal strength may vary abruptly contrast cdma systems use soft hand-off undetectable provides reliable higher-quality signal recent study novel collaborative multi-user transmission detection scheme called collaborative cdma investigated uplink exploits differences users fading channel signatures increase user capacity well beyond spreading length mai-limited environment authors show possible achieve increase low complexity high bit error rate performance flat fading channels major research challenge overloaded cdma systems approach instead using one sequence per user conventional cdma authors group small number users share spreading sequence enable group spreading despreading operations new collaborative multi-user receiver consists two stages group multi-user detection mud stage suppress mai groups low-complexity maximum-likelihood detection stage recover jointly co-spread users data using minimal euclidean-distance measure users channel-gain coefficients note research area going 2004 prof. li ping introduced new concept enhanced cdma version known interleave division multiple access idma scheme uses orthogonal interleaved means user separation place signature sequence used cdma system many researchers introduced various orthogonal interleaving mechanisms including tree based interleaved suggested prof. manoj kumar shukla harcourt butler technical university
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Internet protocols
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80legs 80legs web crawling service allows users create run web crawls software service platform 80legs created computational crawling company houston tx company launched private beta 80legs april 2009 publicly launched service demofall 09 conference time public launch 80legs offered customized web crawling scraping services since added subscription plans product offerings 80legs built top distributed grid computing network grid consists approximately 50,000 individual computers distributed across world uses bandwidth monitoring technology prevent bandwidth cap overages 80legs criticised numerous site owners technology effectively acting distributed denial service attack obeying robots.txt average webmaster aware existence 80legs blocking access crawler done already late server ddosed guilty party detected time-consuming in-depth analysis logfiles rulesets modsecurity like one atomicorp block access webserver 80legs order prevent ddos webknight also blocks 80legs default distributed crawler impossible block crawler ip best way found block 80legs useragent 008 wrecksite blocks 80legs default
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Web technology
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theatre europe theatre europe turn-based strategy video game developed published personal software services first released united kingdom commodore 64 zx spectrum amstrad cpc atari 8-bit home computers 1985 later released france ere informatique 1986 released united states datasoft later year also ported tatung einstein home computer 1989 exclusively united kingdom fifth instalment strategic wargames series game set fictional war europe nato warsaw pact sides use nuclear chemical weapons main objective game fight conventional battles continental europe whilst trying avoid worldwide nuclear holocaust throughout game various capital cities civilian populations destroyed nuclear weapons game end either side forced surrender entire population europe perishes order request nuclear strike player required call dedicated telephone number led automated message announcing authorisation code development developers obtained extensive information statistics military strength ministry defence soviet embassy london theatre europe gained national controversy upon release receiving criticism campaign nuclear disarmament cnd sun newspaper high street retail chains refused sell game upon release despite controversy game received critical acclaim reviewers praise directed accuracy playability value money best strategy game award 1985 golden joystick awards nominated game year title game turn-based strategy revolves around fictional conflict powers nato allies warsaw pact player choice choosing either nato warsaw pact collectively referred soviet forces demo computer versus computer option game plays game takes place period 30 in-game days one day equal one round three types difficulty level one unless provoked enemy use nuclear weapons whilst levels two three enable enemy use nuclear chemical attacks prevent player winning game main feature game focused map europe western russia displays accurate terrain mountain ranges major cities borders military forces belonging side game also features arcade sequence involves shooting enemy units order secure combat bonuses gameplay mode however ignored changing game settings arcade sequences turned player notified choose battle map depending area chosen illustration battle commencing countryside city presented various forms military equipment including aeroplanes helicopters tanks player must shoot destroy enemy units using cursor similar style missile command outcome arcade sequence affect game performing poorly result severe losses throughout round combat resolved player must move assemble forces continental europe known movement phase two special units exclusively available warsaw pact 1st airborne army flown directly behind enemy lines 1st amphibious army move sea tactical attack point units moved cursor one may moved time units moved within round attack phase begin amount friendly units may attack opposing army however unit dispatched battle stopped current attack phase concludes attacking phase separate screen displaying combat information enemy numbers casualties displayed screen detailing attacking phase turned settings battle instead decided warrants air superiority armaments battle sequences player opportunity rebuild units allocating quantity armament supplies air support issued friendly unit map rebuilding ground units game move onto air phase consists commanding aircraft aeroplanes bombers limited number reserve air units several options allocating air forces include counter air strikes reconnaissance enemy movement interdiction assault breakers deep strikes counter air strikes involve attacks enemy air bases whereas interdiction involves aircraft sent behind enemy lines order attack supply movement networks interdiction aircraft discovered enemy territory chance side respond retaliatory nuclear strike remaining three aircraft options attack single unit strike enemy territory attack railways order disable enemy reinforcements respectively game allows player request chemical nuclear tactical strikes enemy chemical attack automatically targeted enemy capital city conclude readout announcing outcome attack civilian casualties order launch strategic nuclear attack player given 30 seconds call dedicated 1-800 telephone number obtain special authorisation code automated answerphone message authorisation code 'midnight sun authorisation code received player given three separate options proceed standby mode postpone nuclear launch whereas strategic launch involve one nuclear warhead targeting city third option known fire-plan issue full-scale nuclear strike across europe may result nuclear holocaust end game personal software services founded coventry west midlands gary mays richard cockayne 1981 company known creating games revolved around historic battles conflicts battle britain bismarck falklands '82 company partnership french video game developer ere informatique published localised versions products united kingdom 1986 cockayne took decision alter products release 16-bit consoles found smaller 8-bit consoles zx spectrum lacked processing power larger strategy games decision falsely interpreted pulling spectrum market video game journalist phillipa irving following years successful sales throughout mid-1980s personal software services experienced financial difficulties cockayne admitted retrospective interview took eye ball company acquired mirrorsoft february 1987 later dispossessed company due strains debt interview computer magazine richard cockayne stated theatre europe received heavy criticism campaign nuclear disarmament cnd sun newspaper respectively cnd accused developers bad taste despite cockayne claiming organisation never looked product development game cockayne mays obtained figures statistics various military strength ministry defence soviet embassy london cockayne asserted statistics developers gained realistically plausible stating would let horrifying results speak game game designer alan steel stated testing alarmed discover computer played warsaw pact always conventional war overwhelmingly forcing nato either surrender begin nuclear war steel adjusted game give nato chance win theatre europe first released united kingdom commodore 64 zx spectrum amstrad cpc atari 8-bit home computers 1985 re-released france united states consoles 1986 due lobbying cnd high street outlets boots john menzies refused sell game stores former finding morally offensive game received critical acclaim upon release gwyn hughes sinclair defended accuracy morality game stating bad taste game well researched program thought would give player insight nature modern war philippa irving crash similarly stated theatre europe offered usual run-of-the-mill war game heralded simplistic nature adding novice gamers would get ease john gilbert sinclair user added scepticism developer intention making something serious opposed titles however praised game brilliant chilling simulation reviewer writing zx computing similarly stated game superbly chilling extremely well-presented reviewer computer video games criticised inferior graphics zx spectrum stating bit flawed comparison commodore 64 version mark reed computer gamer noted game attracted media attention despite objective game discouraging use nuclear weapons reed praised presentation gameplay also stating use joystick keyboard excellent reviewer zzap 64 heralded presentation value money stating overall special indeed reviewer also gave praise sound suggesting game featured one best pieces micro music ever antic stated atari 8-bit version execution uneven magazine reported arcade portion quickly becomes nuisance nato could defeat warsaw pact lack balance flaws exist commodore 64 version peter connor advanced computer entertainment said theatre europe gift regards value money level playability 1994 survey wargames computer gaming world gave title two-plus stars five stating rendered obsolete history game play game best strategy game award 1985 golden joystick awards also nominated game year title
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Computer architecture
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trustworthy computing term trustworthy computing twc applied computing systems inherently secure available reliable particularly associated microsoft initiative name launched 2002 1995 restrictions commercial traffic internet may 26 1995 bill gates sent internet tidal wave memorandum microsoft executives assigning ... internet highest level importance ... microsoft windows 95 released without web browser microsoft yet developed one success web caught surprise mid 1995 testing web server august 24 1995 launched major online service msn national research council recognized rise internet simultaneously increased societal reliance computer systems increasing vulnerability systems failure produced important report 1999 trust cyberspace report reviews cost un-trustworthy systems identifies actions required improvement bill gates launched microsoft trustworthy computing initiative january 15 2002 memo referencing internal whitepaper microsoft cto senior vice president craig mundie move reportedly prompted fact ... fire larger customers–government agencies financial companies others–about security problems windows issues brought front center series self-replicating worms embarrassing attacks code red nimda klez four areas identified initiative ’ key areas security privacy reliability business integrity despite initial scepticism 10-year anniversary generally accepted ... made positive impact industry ... ..
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Computer security
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ecomstation ecomstation ecs pc operating system based os/2 published serenity systems mensys bv currently owned developed xeu.com includes several additions accompanying software present ibm version system ecomstation 32-bit operating system runs exclusively x86 processor architecture real virtualized still used version 1 ecomstation released 2001 based around integrated os/2 version 4.5 client convenience package os/2 warp version 4 released ibm 2000 latter made available holders existing os/2 support contracts included following new features among others compared final retail version os/2 1996 os/2 warp version 4 ecomstation provided retail channel end users obtain updates addition beginning bundled number additional features enhancements including limited ibm began wind os/2 development serenity partners began take slack combination in-house contract community/open source development efforts terms keeping operating system usable current hardware results many efforts included version 2 ecomstation among others became clear ibm would release new retail version os/2 warp client operating system version 4 1996 users began consider alternatives ibm released final version server edition ibm os/2 warp server e-business wseb internally called version 4.5 ibm also continued updating client merged parts server proposed bob st. john serenity systems oem company could create client using existing os/2 client ibm enhancements adding improvements needed serenity ibm business partner done similar thing os/2-based vertical applications like serenity managed client rapid deployment os based workspace on-demand ecomstation server managed server based wseb os/2 software vendor stardock made proposal ibm 1999 followed company april 29 2000 serenity conjunction kim cheung touchvoice systems created discussion group purpose discussing os/2 community interest new managed client ebusiness using components wseb called ecomstation replace one based wod idea brought also create new non-remote boot client — effect oem version os/2 client although serenity initial response suggestion thick client negative response positive enough community ibm get things moving months later first ecs preview shipped notwithstanding cheung fairly simple initial concept community input actively solicited beginning feature requests quickly began coming final ga release ecomstation 1.0 us english released july 2001 significantly different original preview many respects obviously ibm os/2 install routine longer used instead rapid-deployment system based cheung wisemanager product utilized install operating system components addition number enhancements os/2 user interface integrated including revamped desktop layout entirely new icons customizable graphic effects number windowing components redesigned system dialogs enhanced user-extensible system shutdown ecomstation 1.0 built 2000 release ibm convenience package os/2 warp version 4 commonly referred mcp mcp1 additionally several commercial applications bundled operating system package notably lotus smartsuite os/2 ibm desktop on-call english edition released efforts turned making language editions called national language versions nlvs available however first non-english nlv targeted german released end 2001 due large part greater-than-anticipated effort localizing redesigned installer new materials ultimately non-english nlvs released ecomstation 1.0 languages would become available ecomstation 1.1 1.2. ecomstation 1.1 included several major new features compared version 1.0 largest change operating system installed package wide-ranging functional enhancements desktop environment workplace shell based open source xworkplace project netlabs.org included desktop folder enhancements status bars improved sorting options new virtual desktop feature customizable desktop toolbar support programmable widgets expanded configuration options various enhancements built-in support pppoe pptp internet connections also provided addition completely new install process designed bootable code installation cd rewritten improve compatibility modern bioses pre-boot menu introduced allowed user select various drivers kernel options use booting cd graphical installer ecomstation 1.0 replaced new streamlined interface ecomstation 1.1 based 2001 release ibm convenience package 2 os/2 warp version 4 also known mcp2 subsequent ibm service updates integrated version serenity systems separated base operating system product major commercial applications bundled ecomstation 1.0 base ecomstation 1.1 product sold title ecomstation entry applications including lotus smartsuite 1.7 hoblink x11 server packaged separately ecomstation application pack multi-processor support included ecomstation entry due additional license fees required ibm time instead smp package available ecomstation retailers paid extra release ecomstation 1.1 ecomstation server edition also made available based os/2 warp server e-business product besides english also german russian nlvs released ecomstation 1.1 principal new feature ecomstation 1.2 advertised revamped desktop multimedia support updated versions various bundled components ibm non-ibm also included ecomstation 1.2 released english german dutch nlvs serenity systems announced intention provide media refresh incorporating number fixes updates made available release ecomstation 1.2 released version 1.2r initially 12 november 2005 subsequently withdrawn re-released due last-minute bug fix 17 november 2005 principal new feature ecomstation 1.2r support installation athlon 64 systems previously possible awkward work-arounds ecomstation 1.2r released english german italian nlvs additionally beta release traditional chinese nlv made available via download registered customers ecomstation 2.0 longer-than-usual development cycle first beta released 21 december 2005 first self-styled release candidate announced 18 june 2007 final ga release available may 2010 biggest change ecomstation 2.0 addition acpi support represented first major update core operating system developed specifically ecomstation ibm benefits acpi included support modern hardware including advanced power-management features well support irqs 15 addition new acpi driver allowed access os/2 symmetric multi-processing support obviating need ibm proprietary smp-enablement driver consequently starting ecomstation 2.0 smp support included base product additional cost major feature introduced version 2.0 enhanced version journaled file system allowed operating system booted directly jfs-formatted partitions previous versions jfs usable non-bootable data partitions installing operating system onto jfs allowed significant performance improvement due much larger cache sizes supported jfs well reduced chkdsk times event non-clean shutdown ecomstation pricing model revamped significantly version 2.0 standard consumer version home student edition edition lower recommended retail price previous versions ecomstation however one customer limited five purchases business edition targeted commercial customers limit number purchases business edition also came telephone support whereas home student edition customers limited e-mail online assistance software-wise two products identical license terms differed noted editions ecomstation 2.0 included openoffice.org office suite provided separate cd application pack available previous versions discontinued ecomstation 2.0 available english release language versions deferred version 2.1 current version ecomstation 2.1 released year version 2.0 may 2011 version 2.1 two significant new features first support ahci disk controllers via newly developed device driver second replacement old ibm boot manager open-source air-boot software require primary partition therefore easier install disks pre-existing operating systems ecomstation 2.1 also updates included applications notably mozilla firefox minor improvements installer version 2.1 much former branding serenity systems removed released product replaced mensys bv ecomstation 2.1 currently available english german nlvs preview release japanese nlv also available certain customers nlvs including dutch italian reportedly development beta versions ecomstation 2.2 released 2013. ecomstation currently developed xeu.com various third party companies individuals although os/2 longer sold ibm ecomstation developed sold long remains profitable according serenity xeu.com important development ecomstation keeps adding value stakeholders involved recent major release version 2 released warpstock europe held 14–16 may 2010 updated version 2.1 followed year later may 2011 date last edition taken installation cds official release dates may different release dates refer us english editions unless otherwise noted ecomstation also complemented several open source applications included installer following open-source packages available ecomstation actively maintained see unix ports os/2 ecs netlabs ported packages also server edition based ibm os/2 warp server e-business minimum hardware requirements system running ecomstation 1.0 2.0 rc listed ecomstation number limitations relative operating systems currently available
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Computer architecture
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socket f+ socket f+ also socket fr2 internally cpu socket amd server processors starting 45 nm generation k10 cpu family successor socket f. main difference two sockets supported hypertransport version socket f supports hypertransport 2.0 1.0 ghz speed socket f+ supports hypertransport 3.0 2.6 ghz speed backwards compatible version 1.0 2.0
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Computer architecture
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information networking institute information networking institute ini established carnegie mellon 1989 nation ’ first research education center devoted information networking integral department college engineering collaboration school computer science tepper school business heinz college ini ’ professional graduate degree programs represent fusion technologies economics policies secure communication networks systems services ini also partners research outreach entities extend educational training programs broad audience people using information networking part daily lives ini educational partner carnegie mellon cylab university-wide multidisciplinary research center involving 50 faculty 100 graduate students work ini cylab carnegie mellon university designated national security agency department homeland security national center academic excellence information assurance/cyber defense education cae-ia/cd national center academic excellence information assurance/cyber defense research cae-r also designated nsa u.s. cyber command national center academic excellence cyber operations cae-cyber ops designations ini cylab participate ini teaching faculty drawn ini also ongoing partnership university hyogo graduate school applied informatics faculty involved teaching advising ini programs conducting research aspects information networking information security affiliated research centers ini graduated 1,400 alumni currently occupy positions variety sectors across industry government academia
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Computer security
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zend studio zend studio commercial proprietary integrated development environment ide php developed zend technologies based php development tools pdt plugin eclipse platform pdt project led zend zend studio tightly integrated zend server zend pre-integrated tested php application stack integration enables developers quickly set complete php environment speed root cause analysis problems detected testing production environment zend studio also integrated zend framework example provides mvc view easy code navigation integration zend_tool automated code generation along zend server 2013 zend studio deployed 40,000 companies
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Programming language topics
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fast automatic restoration fast automatic restoration fastar automated fast response system developed deployed american telephone telegraph 1992 centralized restoration digital transport network fastar automatically reroutes circuits spare protection capacity fiber-optic cable failure detected hence increasing service availability reducing impact outages network similar operation real-time restoration rtr developed deployed mci used mci network minimize effects fiber cut recovery technique used computer networks telecommunication networks mesh optical networks backup path alternate path affected traffic takes failure condition backup channel computed real time occurrence failure technique broadly classified two centralized restoration distributed restoration technique utilizes central controller access complete up-to-date accurate information network available resources resources utilized physical topology network service demands etc failure detected part network failure detection identification notification scheme central controller calculates new re-route path around failure based information database current state network new route backup path calculated central controller sends commands affected digital cross-connects make appropriate reconfigurations switching elements order implement new path fastar rtr restoration systems examples systems utilize restoration technique restoration technique central controller used hence up-to-date database state network needed scheme nodes network utilize local controllers local information particular node connected neighboring nodes available spare capacity links used connect neighbors state switching elements failure occurs part network local controllers handle computation re-routing affected traffic example approach technique utilized self-healing networks shn transport networks gradually developed digital cross connect system dcs -based mesh networks sonet ring networks optical mesh networks years recovery architecture used therein recovery architectures used different transport networks dcs-based mesh networks restoration ds3 facilities add-drop multiplexer adm -based ring protection sonet ring networks finally optical cross connect oxc -based mixed protection restoration optical mesh networks first restoration architecture used 1980s dcs-based mesh restoration ds3 facilities architecture utilized centralized restoration technique every restoration event coordinated network operation center noc restoration architecture path-based failure dependent utilized fault occurs fault detection isolation architecture capacity-efficient due use stub release slow failure recovery time time takes reestablish traffic continuity failure rerouting signals diverse facilities order minutes architecture implemented 1990s introduction sonet/sdh networks employed distributed protection technique utilizes either path-based upsr span-based blsr protection recovery path precomputed occurrence failure adm-based ring protection capacity-inefficient unlike dcs-based mesh restoration faster recovery time 50 ms recovery architecture used protection optical mesh networks introduced early 2000s protection architecture recovery time tens hundreds milliseconds significant improvement recovery time supported dcs-based mesh restoration unlike dcs-based mesh restoration recovery path predetermined pre-provisioned architecture also capacity efficiency seen preceding mesh restoration architecture dcs-based fastar uses dcs-based mesh restoration architecture architecture consists nodal equipment central control equipment data communication network interconnecting nodes central controller figure right explains architecture fastar different building blocks interact central processor called restoration provisioning integrated design rapid located noc responsible receiving analyzing alarm reports generated event fiber failure also handles alternate backup route computation re-routing affected traffic primary path already computed backup path path assurance tests enables roll-back traffic original path failure repaired rapid maintains up-to-date information state network available spare capacity central access display system cads provides craft interface rapid related restoration management systems traffic maintenance administration system tmas enables rapid perform control protection switch lock-out process protection channels used restoration sending commands line terminating equipment lte restoration network controllers rncs located central office co fiber optic network alarms generated affected digital access cross-connect system dacss lte sent rnc aged find alarm result transient correlated finally sent rapid via data communication network lte either ft series g digital transmission system add drop multiplexer adm reports fiber failure ltes rnc also provides rapid immediate access backup channels re-routing traffic path assurance tests restoration test equipment rte provides rapid means perform continuity tests used path assurance dacs responsible reporting fiber failures node failures occur within office rnc addition dacs enables automatic restoration providing central processor access remotely perform cross-connects ds-3 level data communication network used connect nodal equipments central controller achieve needed availability network full redundancy used form two totally diverse terrestrial satellite-based networks event major restoration process one networks support communication burden absence fastar operates ds-3 level restore individual smaller demands fastar restores 90 95 percent affected ds-3 demand within two three minutes fiber-optic cut occurs output dacs equipment input another rnc collects alarms affected ltes rnc ages alarms sends rapid rapid determines amount spare capacity available failure identifies ds-3 demands affected finds restoration route affected traffic sequential order priority sends command appropriate dacss implement re-route thus establishing restoration figure right route exists node node q via nodes c f k l. event fiber-optic cable failure nodes f k lte ft series g adm two offices detects sends alarm reports failure respective rncs rncs age alarm send reports rapid located noc rapid initiates time window ensure related alarms generated rncs affected nodes rnc office whose traffic utilizes f k failed fiber optic cable window times rapid performs route computation establish new backup path traffic node node q creates new route c f g j k l. route computation also done sequentially order priority traffic two nodes network utilize failed fiber-optic cable backup path traffic going nodes f k computed rapid ensures continuity connectivity along established back-up paths sending command rncs located q turn use test signal generated respective rte check continuity link connectivity backup path verified traffic nodes q transferred backup path commanding dacs iiis make appropriate cross connections rapid performs service verification test verify service transfer successful test returns positive result service transfer successful else service transfer unsuccessful needs repeated service traffic transfer process performed traffic going affected fiber optic cable f–k fastar restores much affected traffic demand available protection capacity allow shared risk link groups srlgs refer situations links connect two distinct nodes offices network share common conduit configuration links group shared risk one link fails links group may fail majority networks use today utilize srlgs times access building across bridge single conduit restore traffic link two offices nodes share srlg links event conduit cut least one two offices must fastar-ompliant cut srlg1 would restorable using fastar fastar implemented either office b b c yet fastar-compliant given failure srlg2 ds-3 traffic link 3 would restored fastar via newly re-computed backup path ds-3 traffic link 2 would restored fastar implemented either office b c. restore three links event failure srlgs fastar implemented offices c. failure srlg1 would cause fastar automatically re-route traffic link 1 3 via two re-computed backup paths also another time failure srlg2 detected reported rapid traffic link 2 3 re-routed new backup path fastar network management used integrate analyze different data alarms supplied various system elements make fastar architecture centralized display troubleshoot isolate problems fault management analysis corrective action taken fastar network management cuts across three tiers
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Distributed computing architecture
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evasi0n evasi0n stylized evasi0n jailbreak program ios 6.0 6.1.2 ios 7.0 7.0.6 evasi0n7 known portable code base minimal use arbitrary code execution seven million copies evasi0n downloaded presumably installed first four days release released 4 february 2013 four six exploits used patched apple 18 march 2013 release ios 6.1.3 meant end original version evasi0n 22 december 2013 evad3rs released new version evasi0n supports ios 7.x known evasi0n7 one major exploit used jailbreak patched apple 4th beta ios 7.1 two beta 5 final release ios 7.1 fixed exploits used evasi0n7 evasi0n jailbreak specifically breaches modern security features address space layout randomization kernel space version launchd hard-coded list exclusive services serve device stability well vendor lock-in ios evasi0n reads fixed data vectors locate random address kernel space utilizes codice_1 file launchd processes regardless list exclusive services
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Computer security
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mac box set mac box set software package made apple inc. including latest version os x mac os x iwork ilife mac box set updated twice original release first release introduced shipped date ilife iwork '09 january 9 2009 included retail discs mac os x 10.5.6 leopard ilife '09 iwork '09 commonly called mac box set '09 next release started shipping shortly mac os x snow leopard introduced thing changed release mac os x version 10.6.3 snow leopard shipped ilife '11 introduced ilife version updated everything else stayed versions mac box set
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Operating systems
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portopia serial murder case often translated portopia serial murder case english adventure game designed yuji horii published enix first released nec pc-6001 june 1983 since ported personal computers nintendo famicom mobile phone services game player must resolve murder mystery searching clues exploring different areas interacting characters solving item-based puzzles game features first-person graphics nonlinear gameplay open world conversations non-player characters branching dialogue choices suspect interrogations nonlinear storytelling plot twists famicom version also features command menu system point-and-click interface 3d dungeon maze upon release portopia serial murder case well received japan became influential title helped define visual novel genre portopia serial murder case follows first-person perspective narrative various events described still pictures text messages player interacts game using verb-noun parser requires typing precise commands keyboard finding exact words type considered part riddles must solved sound effects present game lacks music save function features conversation system branching dialogue choices story develops entering commands receiving answers player sidekick non-player characters game features nonlinear gameplay allowing multiple different ways achieve objectives includes travelling different areas open world making choices determine dialogues order events well alternative endings depending player identifies culprit however one characters true culprit others red herrings player closes case wrong culprit player face criticism police chief need re-open case game includes phone could used manually dial number needed contact several non-player characters game also features inventory system requiring examination collection items could used evidence later game keyboard famicom version replaces verb-noun parser menu list fourteen set commands selectable gamepad similar command selection menu system introduced yuji horii murder mystery adventure game released 1984 pc famicom releases portopia one commands menu allowed player use point-and-click interface using d-pad move cursor screen order look clues hotspots famicom version portopia also features branching menu selections includes using pointer magnifying glass investigate objects needed find hidden clues fist hammer hit anything anyone could used carry beatings suspect interrogations additional sequences also added notably underground dungeon maze style similar role-playing video games although story game fictional set real japanese cities mainly kobe addition sequences kyoto sumoto president successful bank company found dead secretary inside locked room mansion signs seem indicate kouzou stabbed however police sends detective investigate detective charge case unnamed unseen silent protagonist essentially embodies player simply referred works assistant named nicknamed one actually speaks executes player commands characters include among others daughter man named kouzou nephew heir stripper game conceived yuji horii around 1981 27 years old shortly bought first computer learned program modifying games time read pc magazine article computer game genre united states text adventures horii noticed lack games japanese market decided create adventure game horii also cited manga authors tetsuya chiba mitsuru adachi katsuhiro otomo influences game developed using basic programming language horii wanted expand adventure game genre ideas one concept create program story would develop entering command receiving answer idea game progresses conversations human computer started get ambitious thought could make computer converse enough data entered attempting create artificial intelligence language algorithm however realized n't possible computers time created dialogue computer beforehand player could type words computer would reply back reaction another concept contrast linear stories adventure games time idea branching non-linear storytelling main scenario take 20 game ’ content remaining 80 response various actions player however due pc memory limitations able create several short branching scenarios still found interesting one long linear scenario also conceived graphical format picture on-screen representing happening command menu system select action later became standard format japanese adventure games following 1983 release game ported various japanese personal computers famicom port released 1985 first adventure game released platform famicom version also first collaboration yuuji horii koichi nakamura chunsoft dragon quest famicom version programmed nakamura 19 years old time version portopia changed interface adopting command menu system horii created 1984 adventure game due frustration text-based entry admitting never able get far adventure games horii created command menu system hokkaido later used famicom version portopia horii also noted famicom versions portopia hokkaido wanted make appealing mature audience beyond famicom typical younger audience also playing wizardry time inspiring include 3d dungeon maze famicom version portopia game never released western world largely due mature content involving themes murder suicide fraud bankruptcy interrogation beatings drug dealings strip club lack western release prompted rom hacking group dvd translations develop unofficial translation famicom version first mobile phone version game branded part trilogy along mobile versions hokkaido rensa satsujin okhotsk ni kiyu karuizawa yūkai annai released 2003 ezweb yahoo keitai services features list set commands similar famicom version also improved graphics free-moving cursor save function games trilogy retitled re-released 2005 2006 services second portopia version possesses content first mobile one addition updated graphics background music bonus function obtained completing game hint option nullifies ending bonus used frequently famicom version game sold 700,000 copies game well received japan allowing multiple ways achieve objectives well-told storyline surprising twist ending japanese press described game without game technically way lose according square enix first real detective adventure game game along super mario bros. inspired hideo kojima creator metal gear series enter video game industry praised portopia mystery drama humor 3d dungeons providing proper background explanation behind murderer motives expanding potential video games kojima considers one three influential games played influence evident games including metal gear series snatcher pc-6001 version portopia serial murder case included hidden secret portopia also one first video games ever played nintendo eiji aonuma went become director legend zelda series starting ocarina time portopia influence also evident horii later work including seminal role-playing game dragon quest used storytelling techniques menu interface portopia john szczepaniak retro gamer considers one influential games responsible defining visual novel genre comparing role super mario bros. tetris street fighter defining respective genres platform game puzzle game fighting game respectively 2003 portopia serial murder case ranked 19th poll determine thirty best famicom games poll conducted tokyo metropolitan museum photography part level x exhibition english-language webzine retrogaming times monthly compared game later-released shadowgate player must examine collect objects find true purpose later recommended portopia fans slower paced games require players think puzzles john szczepaniak praised pacing quality writing considers gameplay plot sophisticated time noted contains elements found number later titles including déjà vu snatcher nine hours nine persons nine doors 1up also noted portopia similar icom simulations déjà vu released several years later nintendo successful series adventure games also inspired portopia usgamer compared later police quest adventure games csi television series well classic sherlock holmes novels according official xbox magazine portopia features point-and-click murder mystery plot open world suspect interrogations nonlinear gameplay dialogue choices alternate endings standard 2015 way ahead time 1983 comparing l.a. noire peter tieryas gave portopia positive retrospective review stating influence undeniable tragic back story strange vicissitudes characters face uncanny freedom investigate haunting uncovering killer makes special
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Computer architecture
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cross-site request forgery cross-site request forgery also known one-click attack session riding abbreviated csrf sometimes pronounced sea-surf xsrf type malicious exploit website unauthorized commands transmitted user web application trusts many ways malicious website transmit commands specially-crafted image tags hidden forms javascript xmlhttprequests example work without user interaction even knowledge unlike cross-site scripting xss exploits trust user particular site csrf exploits trust site user browser csrf vulnerabilities known cases exploited since 2001 carried user ip address website logs might evidence csrf exploits under-reported least publicly 2007 well-documented examples new attacks web-enabled devices carried 2018 including attempts change dns settings routers router manufacturers hurriedly released firmware updates improve protection advised users change router settings reduce risk details released citing obvious security reasons attackers find reproducible link executes specific action target page victim logged embed link page control trick victim opening attack carrier link may placed location victim likely visit logged target site example discussion forum sent html email body attachment real csrf vulnerability utorrent cve-2008-6586 exploited fact web console accessible localhost:8080 allowed critical actions executed using simple get request attacks launched placing malicious automatic-action html image elements forums email spam browsers visiting pages would open automatically without much user action people running vulnerable utorrent version time opening pages susceptible attack csrf attacks using image tags often made internet forums users allowed post images javascript example using bbcode accessing attack link local utorrent application localhost:8080 browser would also always automatically send existing cookies domain general property web browsers enables csrf attacks exploit targeted vulnerabilities execute hostile actions long user logged target website example local utorrent web interface time attack cross-site request forgery confused deputy attack web browser csrf commonly following characteristics risk web applications perform actions based input trusted authenticated users without requiring user authorize specific action user authenticated cookie saved user web browser could unknowingly send http request site trusts user thereby causes unwanted action utorrent example described attack facilitated fact utorrent web interface used get request critical state-changing operations change credentials download file etc explicitly discourages assumption many existing csrf prevention mechanisms web frameworks cover get requests rather apply protection http methods intended state-changing attacker may forge request log victim target website using attacker credentials known login csrf login csrf makes various novel attacks possible instance attacker later log site legitimate credentials view private information like activity history saved account attack demonstrated google yahoo depending type http request methods vary susceptibility csrf attacks due differences handling web browsers therefore protective measures attack depend method http request additionally typically described static type attack csrf also dynamically constructed part payload cross-site scripting attack demonstrated samy worm constructed fly session information leaked via offsite content sent target malicious url csrf tokens could also sent client attacker due session fixation vulnerabilities guessed via brute-force attack rendered malicious page generates thousands failed requests attack class dynamic csrf using per-client payload session-specific forgery described 2009 nathan hamiel shawn moyer blackhat briefings though taxonomy yet gain wider adoption new vector composing dynamic csrf attacks presented oren ofer local owasp chapter meeting january 2012 – ajax hammer – dynamic csrf severity metrics issued csrf vulnerabilities result remote code execution root privileges well vulnerability compromise root certificate completely undermine public key infrastructure several things happen cross-site request forgery succeed attack blind attacker see target website sends back victim response forged requests unless exploit cross-site scripting bug target website similarly attacker target links submit forms come initial forged request subsequent links forms similarly predictable multiple targets simulated including multiple images page using javascript introduce delay clicks given constraints attacker might difficulty finding logged-in victims attackable form submissions hand attack attempts easy mount invisible victims application designers less familiar prepared csrf attacks say password cracking dictionary attacks csrf prevention techniques work embedding additional authentication data requests allows web application detect requests unauthorized locations synchronizer token pattern stp technique token secret unique value request embedded web application html forms verified server side token may generated method ensures unpredictability uniqueness e.g using hash chain random seed attacker thus unable place correct token requests authenticate example stp set django html form stp compatible relies html introduces complexity server side due burden associated checking validity token request token unique unpredictable also enforces proper sequence events e.g screen 1 2 3 raises usability problem e.g user opens multiple tabs relaxed using per session csrf token instead per request csrf token web applications use javascript majority operations may use anti-csrf technique relies same-origin policy security technique based assumption javascript running within origin able read cookie value javascript running rogue file email able read copy custom header even though csrf-token cookie automatically sent rogue request server still expecting valid x-csrf-token header csrf token unique unpredictable may generated randomly may derived session token using hmac csrf token cookie must httponly flag intended read javascript design technique implemented many modern frameworks django angularjs token remains constant whole user session works well ajax applications enforce sequence events web application protection provided technique thwarted target website disables same-origin policy using one following techniques similarly cookie-to-header approach without involving javascript site set csrf token cookie also insert hidden field html form sent client form submitted site check cookie token matches form token same-origin policy prevents attacker reading setting cookies target domain put valid token crafted form advantage technique synchronizer pattern token need stored server browser extensions requestpolicy mozilla firefox umatrix firefox google chrome/chromium prevent csrf providing default-deny policy cross-site requests however significantly interfere normal operation many websites csfire extension also firefox mitigate impact csrf less impact normal browsing removing authentication information cross-site requests noscript extension firefox mitigates csrf threats distinguishing trusted untrusted sites removing authentication payloads post requests sent untrusted sites trusted ones application boundary enforcer module noscript also blocks requests sent internet pages local sites e.g localhost preventing csrf attacks local services utorrent routers self destructing cookies extension firefox directly protect csrf reduce attack window deleting cookies soon longer associated open tab various techniques used proposed csrf prevention historically cross-site scripting xss vulnerabilities even applications running domain allow attackers bypass essentially csrf preventions
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Computer security
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semantic interoperability community practice semantic interoperability community practice sicop group people seek make semantic web operational respective settings achieving semantic interoperability semantic data integration sicop seeks enable semantic interoperability specifically operationalizing relevant technologies approaches online conversation meetings tutorials conferences pilot projects activities aimed developing disseminating best practices individuals making community practice various settings however sicop claims neither formal implied endorsement organization
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Computer architecture
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domain assurance council domain assurance council dac trade association started summer 2006 paul hoffman john levine members dac divided categories include
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Computer security
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bélády anomaly computer storage bélády anomaly phenomenon increasing number page frames results increase number page faults certain memory access patterns phenomenon commonly experienced using first-in first-out fifo page replacement algorithm fifo page fault may may increase page frames increase optimal stack-based algorithms like lru page frames increase page fault decreases lászló bélády demonstrated 1969 common computer memory management information loaded specific-sized chunks chunk referred page main memory hold limited number pages time requires frame page load page fault occurs page found might need loaded disk memory page fault occurs frames use one must cleared make room new page simple algorithm fifo whichever page frames longest one cleared bélády anomaly demonstrated believed increase number page frames would always result number fewer page faults bélády nelson shedler constructed reference strings fifo page replacement algorithm produced nearly twice many page faults larger memory smaller one formulated conjecture 2 general bound 2010 fornai iványi showed anomaly fact unbounded one construct reference string arbitrary page fault ratio
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Operating systems
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signalr signalr software library microsoft asp.net allows server code send asynchronous notifications client-side web applications library includes server-side client-side javascript components asp.net signalr library asp.net developers add real-time web functionality applications real-time web functionality ability server-side code push content connected clients happens real-time signalr takes advantage several transports automatically selecting best available transport given client server best available transport signalr takes advantage websocket html5 api enables bi-directional communication browser server signalr use websockets covers available gracefully fall back techniques technologies n't application code remains signalr also provides simple high-level api server-to-client rpc call javascript functions client browser server-side .net code asp.net application well adding useful hooks connection management connect/disconnect events grouping connections authorization
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Operating systems
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manaba manaba cloud-based collaborative learning system developed internet service provider asahi net inc. manaba developed 2007 collaboration two private universities japan initially designed connect students teachers enable students accumulate learning evidence elevate learning outcomes mutual review known intuitive interface meaningful design focused learning outcomes flexibility scalability cloud application manaba adopted approximately 200 educational institutions globally december 31 2013 manaba provides spaces teachers conduct surveys tests collect assignments enable group projects facilitate online discussions students also review work develop debates course materials manaba provides individual space student accumulate learning evidence time share others reflect back previous work instructors assess learning outcomes looking students ’ portfolios collectively manaba creates spaces groups engage community discussions various topics name “ manaba ” comes two japanese words manabu 学 ba 場 manabu means learning ba activity place events occur
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Distributed computing architecture
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rtx operating system rtx line real-time operating system rtos extensions firm intervalzero software extension abstraction layer converts microsoft windows operating system rtos first windows real-time solution market rtx real-time software extensions windows combines familiar user experience microsoft windows rich gui extant drivers software ... direct control embedded hardware providing hard real-time determinism symmetric multiprocessing smp abilities rtx extensions followed windows architecture since windows nt 3.5 generally rtx supports 32-bit windows rtx64 supports 64-bit windows 2015 rtx2016 supports 32-bits rtx64 3.0 supports 64-bits systems used different markets industrial automation testbed simulation digital audio digital video aerospace military medical devices electrical grid electricity generation uses
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Operating systems
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os 2200 os 2200 operating system unisys clearpath dorado family mainframe systems operating system kernel os 2200 lineal descendant exec 8 univac 1108 documentation information current past unisys systems found unisys public support website see unisys 2200 series system architecture description machine architecture relationship os 2200 operating system earlier 1100 systems going back 1101 1951 1108 first 1100 series computer designed efficient support multiprogramming multiprocessing along new hardware came operating system exec 8 executive system 1108 univac 1108 computer announced 1964 delivered late 1965 first 1108 computers used exec exec ii developed univac 1107 however univac planned offer symmetric multiprocessor versions 1108 4 processors earlier operating systems really basic monitor programs n't designed even though supported limited multiprogramming univac 1110 introduced 1972 operating system name changed os 1100 reflect support wider range systems name os 1100 retained 1988 introduction sperry 2200 series follow 1100 series name changed os 2200 since time 2200 series became unisys clearpath ix series unisys clearpath dorado series operating system retained os 2200 name company name product names also changed time engineering research associates era saint paul acquired remington rand corporation remington rand also acquired eckert–mauchly computer corporation philadelphia building univac computer two combined univac division remington rand direction william norris william norris one founders era later left remington rand start control data corporation univac division remington rand corporation became univac division sperry rand corporation remington rand merged sperry corporation 1970s sperry rand began corporate identity program changed name sperry corporation division names begin sperry computer systems division became sperry univac later division names dropped everything simply became sperry operating system kernel still referred exec unisys customer personnel however unisys began releasing suites products tested together system base releases later called clearpath os 2200 release n term os 2200 changed refer entire suite products system release others bis released asynchronously dorado hardware platforms 1986 burroughs sperry corporations merged become unisys long time 2200 series clients say stands univac still supplier major mainframe product lines companies continued development including mcp operating system burroughs os 2200 sperry 2016 unisys made virtual microsoft windows version os2200 available cost educational leisure purposes exec 8 sometimes referred exec viii univac operating system developed univac 1108 1964 combined best features earlier operating systems exec exec ii used univac 1107 exec 8 one first commercially successful multiprocessing operating systems supported simultaneous mixed workloads comprising batch time-sharing real-time one file system flat naming structure across many drums spindles also supported well-received transaction processing system previous systems real-mode systems hardware support protection separation programs operating system support multiprogramming previous systems limited running one user job concurrently multiple supporting functions known well-behaved card reader printer card punch spoolers exec 8 operating system designed beginning multiprogramming multiprocessing operating system 1108 designed four cpus memory mass storage primary system constraints 1100 series envisioned targeting general market extreme real time processing primary requirement specifications exec 8 drawn december 1964 preliminary programmers reference manual user guide work began may 1965 exec 8 began real time operating system early use mostly general scientific engineering work also used message switching process control simulation missile firing control designed run systems often 128k words 576 k bytes—less maximum memory size ibm pc xt focused real time batch processing earliest release levels work 128kw increasing functionality later releases made untenable since n't leave enough space programs useful size maximum memory capacity 1108 256kw 1,148 kb efficient use memory important constraint since core memory expensive part system mass storage consisted 6-foot long rotating drums held 256kw fh-432 2mw fh-1782 highest capacity mass storage fastrand drum held 22 mw 99 mb file fragmentation dealt process called file save generally done per day night involved rolling files tape reinitializing drum file system reading files back severe memory constraints real time use keeping single copy code loaded core requirement since 1108 designed multitasking system fully reentrant thread safe reentrant module accessed program data single memory base address different instance run data switching execution contexts could done single instruction merely setting different base address single register system used fine-grained locking protect shared data structures executive compilers utilities even sophisticated user applications might multiple copies running concurrently written code could shared required loading one copy memory saving space time took load code another reason separate code data different load entities memory implemented two independent banks separate physical cabinets called ibank dbank instruction data access path cpu could read banks simultaneously loading executable code one memory bank data run time many programs could almost halved reentrant code thread safe execute self-modifying code allowed programs modifying executable code runtime still acceptable programming technique time 1100-series computers users encouraged performance hit security benefits touted highly valued hacking 1100-series applications would provide benefit anyone hackers malevolent exec 8 primarily batch processing system gave applications called tasks fine control cpu scheduling priority threads called activities processor switching preemptive higher priority threads gaining control processor currently running lowest priority thread program except realtime systems even lowest priority tasks got processor time multiprogramming multiprocessing operating system fully symmetric processor management test-and-set instruction built hardware allowed efficient fine-grained locking within os within multi-threaded applications exec 8 work organized jobs called runs scheduled based priority need lockable resources uniservo tape drives fastrand drum files control language syntax uses symbol univac called master space control statement recognition symbol immediately followed command program name comma option switches space character remainder statement differed particular commands command compile fortran program would look like options sourcefile objectfile input data application could read file generally card images immediately follow command run stream lines sentinel command end assumed input data forgetting insert led compiler interpreting subsequent commands program data reason preferable process data files rather inputting run stream 1968 work began adding time-sharing capability exec 8 delivered level 23 executive 1969 time sharing called demand mode capabilities batch real time processes everything could done batch could done ascii terminal demand mode job stream i/o attached terminal handler rather card image input spool output files run control language used years later specific time sharing commands added control statements could issued asynchronously immediate processing even neither executive running program expecting data commands could entered terminal began could performed without stopping work progress terminal called transparent commands first statements kill current program redirect terminal output file eventually almost control statements allowed immediate batch demand runs terminate fin statement demand user terminates session run active exec automatically terminates run without requiring fin transaction processing capability developed late 1960s joint project united airlines later refined another joint project air canada capability fully integrated operating system 1972 became basis much future growth 1100 series early users controlled communication lines directly within real time programs part development transaction processing included communication message system managed communication lines presented messages exec 8 scheduled transactions moved low level communication physical line management protocols applications cms 1100 application cms 1100 ran real time multi-threaded program privilege acquiring control communication lines submitting transaction messages scheduling led notions exec 8 applications nature needed carefully controlled ensure could cause integrity issues security certainly concern early days system reliability integrity much larger issues system still primarily batch transaction processing little chance anyone could install unauthorized code system cms 1100 later added capability interface demand terminals well transaction terminals terminals could used early terminal drivers could removed exec cms 1100 later replaced combination cpcomm clearpath enterprise servers communications platform silas system interface legacy application systems intel-based dorado server models lower level communications moved firmware upper levels handled silas cpcommos clearpath enterprise servers communications platform open systems exec contains code system allowed run highest privilege levels mechanisms code promoted privilege levels exec responsible managing system hardware scheduling managing work communicating operators administrators release 16.0 exec level 49r2 49.70.5 internal system levels use three-part number 21.92.42 first widely used production system although earlier releases used production number sites first number part major level indicates new version exec previous updates integrated new base version infrequent process occurs intervals years second number part indicates versions updates major level often occurs several times per week decision made freeze feature content prepare release third part comes play indicates versions pre-release level fixes minor feature updates applied concurrently preparing level release updates mainline continue engineers integrate changes preparation future release many years official release level full three-part number later releases named simply 44r1 44r2 49r2 although three-part number still used internally exec heart real time multi-threaded batch processing system everything built around model exec largely structured real time program functions performed services windows daemons linux unix implemented either activities within exec batch programs always running background time-sharing known demand mode transaction processing implemented special cases batch one result restrictions time-sharing user transaction program lots warnings writers transaction programs happy performance example call tape mount permitted largest unit work run taken factory production run terminology generally equates job session systems run defined run stream run stream sequence control statements represent steps taken may include file handling program execution branches control batch run typically stored file scheduled start command within another run operator time sharing run initiated logging time-sharing terminal inputting run command often run statement second control statement often add program execution generated automatically based user profile security authorizations validated based authenticated user-id information supplied run control statement transactions special case ’ actually control statements internal data structures run created enables exec associate security accounting debugging etc mechanisms transaction programs generally security profile cached memory time transaction user authenticated copied user session data transaction run state transaction scheduled transaction instance essentially run accounting logging error handling encapsulated run mechanism batch jobs runs characterized runstream job control language statements stored file batch job always contains run statement first record file statement gives run name runid defines priorities defines maximum number sups standard units processing job expected use job started job start control statement operator via st keyin system may configured automatically issue start statements number jobs boots jobs serve purpose performing initialization recovery background functions fields run statement may overridden corresponding fields start statement except start executed privileged user userid security state always taken run start two priority fields run statement one used specify backlog priority 26 backlog priority levels – z exec configured maximum number open batch runs level reached jobs selected backlog queues priority order within priority selection usually fifo however exec pre-scans job control statements first program execution looking file names reel numbers job would immediately stall resources needs available may bypassed start jobs priority level second priority level defines execution processor resource group general higher execution group priorities typically get processor time os 2200 job control language support full programmability allow dynamic additions sequences control language add control statement file added may created job immediately preceding adding add control statements may also submitted within running program via api additional programmability available indirectly use symbolic stream generator ssg ssg programming language manipulating creating text files input parameters system information used heavily configuration management make processing functions text images need created programmatically resulting output add ed run thus providing indirectly programmable runstream operator commands available change backlog execution priorities runs operator commands available api suitably privileged users automated controlled remote administrator deadline special case batch deadline run looks like batch run except deadline time specified run start control statement deadline time used conjunction maximum sups time estimate control statement deadline job runs normal batch priorities unless appears could miss deadline time mismatch time deadline remaining sups higher priority deadline ’ totally shut transactions effect real time effectively shut processing system necessary achieve goal os 2200 time-sharing sessions called demand demand runs use control language batch runs additions known immediate control statements immediate control statements use sentinel indicates executed immediately even program running used create assign files important ones allow demand user error terminate running program even send signal transactions execute runs without stored submitted control statements instead message received session defined transaction session scanned determine transaction queue placed normally determined first characters message user-written scanners may added communication manager capable handling 250,000 active sessions takes incoming transaction messages passes message queuing software handle unlimited number queued messages using message queuing architecture call made transaction interface package tip apis operating system queue transaction appropriate queuing point queuing point identifies priority concurrency level work associated transaction program executed transaction program scheduling tree allows client establish relative usage groups transaction programs concurrency limits avoid one type work dominating system exclusion work avoid creating commitment resources 4094 nodes may created tree priority 0 63 concurrency level 1 2047 specified transaction program highest priority transaction selected scheduling except limited concurrency policies effect node higher nodes real time another type run rather set priority levels activity may request real time typically used long running batch programs like os 2200 communications manager cpcomm restricted 36 real time priority levels available api applications use user account must privilege use real time priorities site control applications use priority levels real time priorities totally dominate lower priorities quite possible misbehaved real time program tie one processors real time priority applies individual activity thread program may real time non-real time threads executing time run started getting access processor controls rate progress heart exec dispatcher manages processors exec supports 4095 dispatching priorities although sites define small subset two highest priorities ’ switchable recognition certain types processing must allowed continue processor started voluntarily give control interrupt lockout occurs interrupt arrives special cases exec code prevents interrupts order change data interrupt handler may also access interlock used interrupt post processing routines either need run physical processor simply interrupted dispatcher i/o completions i/o initiation examples locks used priorities spin locks way set someone else another processor design requires set short instruction sequences high exec priority used operator command handler functions may run even real time program control expected use short amounts time need time queue work processed low exec activity real time activities unlimited processor quantum run without switching unless interrupted higher priority real time activity high exec activity real time activities given control available processor running something lower priority interrupts sent processors necessary ensure immediate availability real time used customers fly missiles run simulators functions require immediate response transaction priorities may handled two ways defined site may sort lower priority real time priority matters quantum size essentially infinite appropriate short-lived transactions airline reservations one loops due programming error exec terminate reaches small configured maximum time form allows exec vary priority within range optimize system resource usage approach gives higher priority shorter time slices programs i/o limited progressively lower priorities longer time slices computing exec dynamically adjusts priorities based behavior programs often behave ways different times approach appropriate longer running transactions like database queries airline fare quotes batch demand always use dynamically adjusted priorities programs i/o limited conversation time-sharing user get higher priorities short time slices compute-oriented programs get lower priorities longer time slices exec two additional mechanisms optimizing dispatching one affinity-based dispatching possible exec run activity processor last time get greatest advantage residual cache contents n't possible tries keep activity nearest processor standpoint cache memory access times second fairness policy mechanism site define relative percentage resources allocated transactions demand batch within transactions batch priority groupings indicate percentage group time allocated priority ensures transactions dominate system batch work gets done within various priority groupings ensures progress assured group unless group percentage zero fairness algorithms come play processors busy os 2200 systems often run processors near 100 utilized os 2200 supports several models system performance management customers may purchase certain fixed performance level exec monitor processor usage ensure performance exceed level customers also purchase additional performance either temporarily permanently full capacity system workload increases emergency requires recently system added metered usage capability mode full power system always available customer although may administratively limit usage accumulated month reported usage submitted unisys billing depending specific contract terms client may receive bill excess usage contracted baseline month statement showing total contracted usage decremented first form like cell phone bill potential charging excess minutes latter like buying pre-paid phone card os 2200 hierarchical file system operating systems rather structured naming convention notion container files called program files files os 2200 simply containers may addressed either word offset file sector 28-word unit offset file 28 words historical unit early mass storage device fastrand drum could hold 64 units per physical track nonetheless fortunate historical accident four 28-word units 112 words occupy 504 bytes today mass storage devices using 512-byte physical records os 2200 clients almost adopted multiple 112 words physical record size database page size i/o processors automatically adjust 504 512 byte mapping adding 8 bytes zeros writes stripping reads physical record os 2200 handles applications use sizes multiples 112 words indivisibly reading containing physical records writing back unchanged changed portions data chaining special locking functions guarantee indivisibility even device errors across multiple systems cluster file formats internal data structures described data structures programming reference manual ever since exec-8 file names taken form qualifier*filename f-cycle e.g. personnel*employees +1 qualifier filename simply twelve-character strings used create whatever naming structure client desires f-cycle number 0 999 allows multiple generations file may referenced relative numbers +1 next new cycle -1 previous cycle +0 current cycle leaving cycle defaults current cycle batch production runs create new generations files use approach numbers wrap around 999 32 consecutive relative cycle numbers may exist one time creating +1 deletes -31 file may used program file program file contains elements generally act files element naming qualifier*filename f-cycle .element/version e-cycle e.g. personnel*programs.taxcalc/2008 element version twelve-character names used way user desires e-cycle similar f-cycle represents generation number without restriction 32 concurrent cycles limit 256k cycles however e-cycle applies text elements line text element marked cycle numbers inserted deleted elements also type sub-type commonly used types text object default type suitable options select appropriate type text elements also sub-types typically represent programming language e.g. asm c cob default element name object file text file created object element may executed main program linked object elements including main program linking may static dynamic main program may executed without pre-linking provided required sub-programs program file system libraries otherwise known rules may included program file direct dynamic linker search unfulfilled references linker may also used statically link multiple object modules together form new object module containing instructions data information original object modules omnibus elements may used data applications may serve hold structured information applications system utilities assumed structure omnibus element compatibility earlier basic mode programming models relocatable absolute element types relocatable elements output basic mode compilers may combined basic mode static linker map – collector form absolute element executable os 2200 implements fully virtual file system files may allocated anywhere across mass storage devices mass storage treated large space pool similar way virtual memory managed contiguous space allocated possible mass storage treated set pages 8kb size file placed many areas different devices required dynamic expansion files attempts allocate space adjacent previous allocation find space wherever available fact files need even present mass storage used exec file backup system fully integrated file backups made tape reel number recorded file directory space gets short mass storage files simply marked unloaded current backup copy space available use enough space ca n't found way backup started reference unloaded file queued file copied back mass storage whole system automatic generally transparent users general exec provide access methods files simply containers access methods provided language run time systems database manager one exception fixed-block access method provided high-volume transaction processing much less overhead database manager participate locking clustering recovery mechanisms clients want explicit control location files use removable pack concept one time truly represented physically removable disk packs operating system would automatically generate pack mount requests operators needed today still used place files usually database files transaction files one disk volumes files may still span multiple disk volumes list volume names given file created files volume groups still backed subject automatic virtual space management os 2200 also provides full implementation common internet file system cifs cifs implements smb protocol used microsoft servers unix/linux samba software cifs clearpath os 2200 file server file client cifs-compliant systems includes desktop pcs running windows cifs supports smb message signing maintain os 2200 security cifs clearpath os 2200 provides two levels protection first os 2200 files visible network declared shares cifs command specific privilege exists control may declare share second level control access still protected os 2200 security clients accessing os 2200 via cifs either automatically identified via ntlm kerberos presented query os 2200 user id password cifs allows os 2200 files presented hierarchical view typically qualifier appear highest level tree followed filename element name version addition files may stored os 2200 servers using full windows filename format windows applications see os 2200 another file server os 2200 applications apis available read write files existing cifs-compliant servers windows file servers network text files automatically converted os 2200 internal formats binary files must understood application program cifsut utility running os 2200 exchange encrypted compressed files software winzip concept subsystems protected subsystems central design os 2200 subsystem analogous .dll windows code data may shared among programs running system os 2200 subsystem set banks reside separate part address space directly accessed user program instead hardware os provide gate may target call instruction see unisys 2200 series system architecture information database managers run time libraries messaging system many system functions implemented subsystems subsystems usually consisting pure code run time libraries may direct target call instruction without requiring gate subsystems run user program protection environment subsystems database managers consist code data privileged code may called via gate subsystems may also access control lists associated control may call importantly gate controls specific entry points visible protection environment subsystem run often user-specific parameter provides additional secure information caller os 2200 security system designed protect data unauthorized access modification exposure includes implementation dod orange book b1 level specification os 2200 first obtained successful b1 evaluation september 1989 evaluation maintained 1994 point os 2200 developers continued follow development documentation practices required b1 evaluation central b1 system concepts users objects users identities clearance levels compartments privileges objects require certain combinations various types access objects os 2200 consist files protected subsystems devices tape reels security profile user session includes user identity clearance level 0-63 compartment set set allowed privileges os 2200 implements mandatory access control mac discretionary access control dac based bell-la padula model confidentiality read write biba integrity model read write run read execute file run executing clearance level must greater equal clearance level file file clearance level must 0 within clearance level range run addition run executing compartment set must contain file compartment set os 2200 combines bell-la padula biba model requirements run executing clearance level compartment set must exactly match file permit writing file deleting dac associates access control list object list identifies users user groups access defines type access user group allowed read write execute delete full set b1 controls restrictive environments system administrators configure servers choosing controls apply set security levels fundamental security security level 3 serves starting point every os 2200 system one user designated security officer systems configured fundamental security security officer allowed perform certain tasks systems configured higher levels security trusted users may allowed perform tasks os 2200 provides fine-grained security mechanism based principle least privilege principle demands minimum privilege granted necessary perform task required thus os 2200 concept super user role assumed user rather uses large set specific privileges may granted separately user privilege associated specific authority systems configured security level 1 higher levels user creates object object owner default object private creating user may also public controlled access control list owner security officer may create access control list object system configured fundamental security files owners instead created private account project public access controlled read write keys users log system identify optionally select clearance level compartment set use session os 2200 offers flexible authentication system multiple authentication mechanisms supported concurrently client- third party-written authentication software may also used standard authentication capabilities include last two permit use biometrics smart cards authentication mechanism supported technologies os 2200 provides encryption data rest cipher api software subsystem encrypts decrypts caller data cipher api also supports use hardware accelerator card bulk data encryption cmos-based dorado servers cpcomm provides ssl/tls encryption data transit intel-based dorado servers ssl tls provided openssl included dorado firmware dorado servers support tls levels 1.0 1.2 well sslv3 ssl disabled default vulnerabilities protocol cpcomm cipher api use encryption services cryptolib fips-certified software encryption module aes triple des algorithms among algorithms implemented cryptolib os 2200 also supports encrypting tape drives provide encryption archive data os 2200 systems may clustered achieve greater performance availability single system 4 systems may combined cluster sharing databases files via shared disks hardware device xpc-l provides coordination among systems providing high-speed lock manager database file access clustered environment allows system local files databases application groups along shared files one shared application groups local files databases accessed single system shared files databases must disks simultaneously accessible systems cluster xpc-l provides communication path among systems coordination actions also provides fast lock engine connection xpc-l via special i/o processor operates extremely low latencies lock manager xpc-l provides functions required file database locks includes deadlock detection ability free locks failed applications xpc-l implemented two physical servers create fully redundant configuration maintenance including loading new versions xpc-l firmware may performed one servers continues run failures including physical damage one server stop cluster information kept servers os 2200 operations built around active operators one consoles console terminal window part reserved fixed display frequently updated summary information activity system rest console used scrolling display events message issued requires operator response given number 0 9 remains display answered tape mount messages scroll messages repeated every two minutes tape mounted operations sentinel used os 2200 operations os 2200 consoles simply windows within operations sentinel display may many display pcs desired remote operation typical operations sentinel supports number clearpath windows linux unix systems auto-action message database released product database allows operations sentinel recognize messages scripts may written automatically respond messages require response hide unwanted messages translate languages create events etc full dark room operation used clients operations sentinel displays remote locations monitoring system creating alerts certain events occur administration os 2200 systems performed using wide variety tools specialized particular area system example tool used administering transaction environment allows new transaction programs installed specifies necessary information changes queuing structure priorities concurrency levels tools specific security officer allow creation users changing allowed privileges changing system security settings etc tools graphical interface although provide batch stored file interface actions specified control stream allows scripting administrative interfaces either local sites maybe based time day events remote sites unique privileges required administrative area application groups logical construct consisting instance universal data system uds instance message queue subsystem set transactions application group audit trail os 2200 supports maximum 16 application groups system notion application group corresponds often called application set programs data represent larger unit connected processing example application group might represent airline system another application group might represent corporate finance system application groups might represent instances application data models bank branches important thing application group environment sessions recovery etc application groups may started stopped recovered independently application groups accounting scheduling rules transactions multiple application groups may share priorities interleaved priorities permits site control relative priorities transactions across entire system unisys history newsletter contains articles unisys history computers addition unisys history newsletters links sites historical archives unisys charles babbage institute university minnesota hagley museum library delaware charles babbage institute holds archives era early remington rand archives saint paul mn burroughs archives hagley museum library holds bulk sperry archives
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Operating systems
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machttp machttp webserver designed run classic mac os versions 7.x 9.x written software developer chuck shotton originally shareware dates 1993 available source code form sourceforge.net perl artistic license current version 2.6.1 still used older macintosh hardware later commercialized webstar sold originally starnine later bought quarterdeck software program runs mac os x classic environment ported run natively mac os x though attempt apparently underway 2003 functionally replaced apache web server machttp supports common gateway interface standard generating dynamic content well apple events scriptability
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Web technology
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unix file types standard unix file types regular directory symbolic link fifo special block special character special socket defined posix different os-specific implementations allow types posix requires e.g solaris doors file type identified codice_1 command displays type first character file system permissions field regular files unix impose provide internal file structure therefore structure interpretation entirely dependent software using however codice_2 command used determine type data contain take example one line codice_1 output posix specifies format output long format codice_4 option particular first field first space dubbed file mode string first character describes file type rest string indicates file permissions therefore example mode string codice_5 file type codice_6 directory permissions codice_7 internally codice_8 obtains codice_9 structure associated file transforms codice_10 field human-readable format note codice_10 actually bit field two parts file type stored within codice_12 mask tested macros like codice_13 codice_14 value mask codice_12 get file type flags gnu coreutils version codice_8 uses call codice_17 glibc function exposed gnulib library get mode string freebsd uses simpler approach allows smaller number file types regular files show codice_1 hyphen-minus codice_19 mode field common special file directory layout directory file defined filesystem used several filesystems available unix native non-native one directory file layout directory marked codice_6 first letter mode field output codice_21 codice_9 e.g symbolic link reference another file special file stored textual representation referenced file path means destination may relative path may exist symbolic link marked codice_23 lower case codice_24 first letter mode string e.g one strengths unix always inter-process communication among facilities provided os pipes connect output one process input another fine processes exist parent process space started user circumstances communicating processes must use fifos referred named pipes one circumstance occurs processes must executed different user names permissions named pipes special files exist anywhere file system created command codice_25 codice_26 named pipe marked codice_27 first letter mode string e.g socket special file used inter-process communication enables communication two processes addition sending data processes send file descriptors across unix domain socket connection using codice_28 codice_29 system calls unlike named pipes allow unidirectional data flow sockets fully duplex-capable socket marked codice_30 first letter mode string e.g unix almost things handled files location file system even hardware devices like hard drives great exception network devices turn file system handled separately device files used apply access rights devices direct operations files appropriate device drivers unix makes distinction character devices block devices distinction roughly follows although example disk partitions may character devices provide un-buffered random access blocks partition block devices provide buffered random access blocks partition character device marked codice_31 first letter mode string likewise block device marked codice_32 e.g door special file inter-process communication client server currently implemented solaris door marked codice_33 upper case first letter mode string e.g
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Computer file systems
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zero instruction set computer computer science zero instruction set computer zisc refers computer architecture based solely pattern matching absence micro- instructions classical sense chips known thought comparable neural networks marketed number synapses neurons acronym zisc alludes reduced instruction set computer risc zisc hardware implementation kohonen networks artificial neural networks allowing massively parallel processing simple data 0 1 hardware implementation invented guy paillet developed cooperation ibm chip factory essonnes france commercialized ibm zisc architecture alleviates memory bottleneck blending pattern memory pattern learning recognition logic massively parallel computing solves allotting neuron memory allowing simultaneous problem-solving results settled disputing according techcrunch software emulations types chips currently used image recognition many large tech companies facebook google applied miscellaneous pattern detection tasks text results said produced microseconds even chips released 2007 junko yoshida ee times compared neuromem chip machine machine capable able predict crimes scanning people faces person interest tv series describing heart big data foreshadow ing real-life escalation era massive data collection
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Computer architecture
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swig simplified wrapper interface generator swig open-source software tool used connect computer programs libraries written c c++ scripting languages lua perl php python r ruby tcl languages like c java javascript go modula-3 ocaml octave scilab scheme output also form xml lisp s-expressions aim allow calling native functions written c c++ programming languages passing complex data types functions keeping memory inappropriately freed inheriting object classes across languages etc programmer writes interface file containing list c/c++ functions made visible interpreter swig compile interface file generate code regular c/c++ target programming language swig generate conversion code functions simple arguments conversion code complex types arguments must written programmer swig tool creates source code provides glue c/c++ target language depending language glue comes two forms swig used calling interpreted functions native code must done programmer manually swig wraps simple c declarations creating interface closely matches way declarations would used c program example consider following interface file file two functions global variable two constants swig creates extension module declarations accessible scripting language functions variables constants respectively python two main reasons embed scripting engine existing c/c++ program several reasons create dynamic libraries loaded extant interpreters including swig written c c++ publicly available since february 1996 initial author main developer david m. beazley developed swig working graduate student los alamos national laboratory university utah faculty university chicago development currently supported active group volunteers led william fulton swig released gnu general public license swig successful participant google summer code 2008 2009 2012 2008 swig got four slots haoyu bai spent summers swig python 3.0 backend jan jezabek worked support generating com wrappers cheryl foil spent time comment 'translator swig maciej drwal worked c backend 2009 swig participated google summer code time four students participated baozeng ding worked scilab module matevz jekovec spent time c++0x features ashish sharma spent summer objective-c module miklos vajna spent time php directors 2012 swig participated google summer code time four five students successfully completed project leif middelschulte worked c target language module swati sharma enhanced objective-c module neha narang added new module javascript dmitry kabak worked source code documentation doxygen comments python similar functionality offered sip boost boost.python library
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Programming language topics
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kristen nygaard kristen nygaard 27 august 1926 – 10 august 2002 norwegian computer scientist programming language pioneer politician internationally nygaard acknowledged co-inventor object-oriented programming programming language simula ole-johan dahl 1960s nygaard dahl received 2001 a. m. turing award contribution computer science nygaard born oslo received master degree mathematics university oslo 1956 thesis abstract probability theory entitled theoretical aspects monte carlo methods nygaard worked full-time norwegian defense research establishment 1948 1960 computing programming 1948–1954 operational research 1952–1960 1957 1960 head first operations research groups norwegian defense establishment cofounder first chairman norwegian operational research society 1959–1964 1960 hired norwegian computing center ncc responsible building ncc research institute 1960s becoming director research 1962 together ole-johan dahl developed simula 1961–1965 simula-67 first object-oriented programming languages introducing core concepts object-oriented programming languages objects classes inheritance virtual quantities multi-threaded quasi-parallel program execution 2004 aito established annual prize name ole-johan dahl kristen nygaard honor pioneering work object-orientation aito dahl-nygaard prize awarded annually two individuals made significant technical contributions field object-orientation work spirit pioneer conceptual and/or implementation work dahl nygaard shaped present view object-oriented programming prize presented year ecoop conference prize consists two awards given senior junior professional conducted research norwegian trade unions planning control data processing evaluated light objectives organised labour 1971–1973 working together olav terje bergo research development work included social impact computer technology general system description language delta 1973–1975 working erik holbaek-hanssen petter haandlykken nygaard professor aarhus denmark 1975–1976 became professor emeritus oslo part-time 1977 full-time 1984–1996 work aarhus oslo included research education system development social impact computer technology became foundation scandinavian school system development closely linked field participatory design beginning 1976 engaged development since 1986 implementation general object-oriented programming language beta together bent bruun kristensen ole lehrmann madsen birger moeller-pedersen language available wide range computers nygaard first half 1980s chairman steering committee scandinavian research program sydpol system development profession oriented languages coordinating research supporting working groups system development language research artificial intelligence also 1980s chairman steering committee cost-13 european common market commission -financed research project extensions profession-oriented languages necessary artificial intelligence information technology becoming part professional work nygaard research 1995-1999 related distributed systems leader general object-oriented distributed systems goods three-year norwegian research council-supported project starting 1997 aiming enriching object-oriented languages system development methods new basic concepts make possible describe relation layered and/or distributed programs computer hardware people carrying programs goods team also included haakon bryhni dag sjøberg ole smørdal nygaard final research interests studies introductory teaching programming creation process-oriented conceptual platform informatics subjects developed new research project called cool comprehensive object-oriented learning together number international test sites giving lectures courses subjects norway elsewhere november 1999 became chair advisory committee broadband communication norwegian department municipal regional affairs held part-time position simula research laboratory 2001 research institute opened june 1990 received honorary doctorate lund university sweden june 1991 became first individual given honorary doctorate aalborg university denmark became member norwegian academy sciences october 1990 computer professionals social responsibility awarded norbert wiener award social professional responsibility 1999 became together dahl first receive rosing prize new prize awarded norwegian data association exceptional professional achievements june 2000 awarded honorary fellowship originating object technology concepts object management group international organization standardization within object-orientation november 2001 dahl awarded ieee john von neumann medal institute electrical electronics engineers introduction concepts underlying object-oriented programming design implementation simula 67 february 2002 given together ole-johan dahl 2001 a. m. turing award association computing machinery acm citation ideas fundamental emergence object oriented programming design programming languages simula simula 67 august 2000 made commander royal norwegian order st. olav king norway 1984 1985 nygaard chairman informatics committee university oslo active design university plan developing research education computing communication facilities faculties university first chairman environment protection committee norwegian association protection nature 10 years 1970s norwegian representative oecd activities information technology member research committee norwegian federation trade unions cooperated unions number countries several years engaged running experimental social institution trying new ways creating humane living conditions socially outcast alcoholics nygaard active norwegian politics mid late 1960s member national executive committee norwegian liberal party chair party strategy committee minor ballot candidate 1949 parliamentary election intense political fight 1972 referendum whether norway become member european common market later european union worked coordinator many youth organisations worked membership 1971 2001 nygaard member labour party member committees research policies party november 1988 became chair information committee norway eec august 1990 reorganized nei til ef organization disseminating information norway relation common market coordinating efforts keep norway outside european union membership norway literally eu 1993 eec ratified maastricht treaty became european union organization changed name reflect nei til ef became largest political organization norway 145,000 members 1994 population 4 million nygaard worked anne enger lahnstein leader anti-eu centre party campaign referendum november 28 1994 nei til eu succeeded 52.2 electorate voted voter participation highest ever norway history 88.8 strategy campaign insisted nygaard something well i.e scandinavian welfare state nygaard considered threatened maastricht agreement resigned chair 1995 later chair organization strategy committee member council 1996 1997 nygaard coordinator efforts establish european anti-maastricht movement team cooperative network national organizations opposing economic monetary union european union emu maastricht treaty european countries within outside eu team successfully started march 3 1997 kristen nygaard married johanna nygaard 1951 johanna nygaard worked norwegian agency aid developing countries specialized number years recruiting giving administrative support specialists working east africa johanna kristen nygaard three children seven grandchildren nygaard died heart attack 2002
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Programming language topics
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sitekey sitekey web-based security system provides one type mutual authentication end-users websites primary purpose deter phishing sitekey deployed several large financial institutions 2006 including bank america vanguard group bank america vanguard group discontinued use 2015 product owned rsa data security 2006 acquired original maker passmark security sitekey uses following challenge-response technique user phishing site different web site domain legitimate domain user browser refuse send state token step 2 phishing site owner either need skip displaying correct security image prompt user security question obtained legitimate domain pass answers theory could cause user become suspicious since user might surprised re-prompted security questions even used legitimate domain browser recently however practice evidence users generally fail notice anomalies harvard study found sitekey 97 ineffective practice real people n't notice n't care sitekey missing according results also requires users keep track authentication information someone associated n different websites use sitekey must remember n different 4-tuples information site username phrase password may 2015 bank america announced sitekey would discontinued users end year would allow users log username password one step july 2015 vanguard also discontinued use sitekey website
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Web technology
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anthony zboralski anthony zboralski french hacker artist internet entrepreneur anthony zboralski born martigues france attended parmiter school 1989 1990. 1994 zboralski social engineered fbi connect internet set teleconferences hackers period four months zboralski posed legal attaché paris thomas baker costing fbi 250,000 dollars zboralski part group hackers called w00w00 2011 2013 zboralski worked managing consultant ioactive 2014 zboralski co-founded belua systems limited surfez couvert tv show co-written antoine rivière zboralski zboralski offered practical recommendations protect life 2.0 began airing game one 2013 co-produced flair production mtv networks france
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Computer security
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common gateway interface computing common gateway interface cgi offers standard protocol web servers execute programs execute like console applications also called command-line interface programs running server generates web pages dynamically programs known cgi scripts simply cgis specifics script executed server determined server common case cgi script executes time request made generates html brief http post request client send html form data cgi program via standard input data url paths http header data presented process environment variables 1993 national center supercomputing applications ncsa team wrote specification calling command line executables www-talk mailing list web server developers adopted standard web servers ever since work group chaired ken coar started november 1997 get ncsa definition cgi formally defined work resulted rfc 3875 specified cgi version 1.1 specifically mentioned rfc following contributors historically cgi scripts often written using c language rfc 3875 common gateway interface cgi partially defines cgi using c saying environment variables accessed c library routine getenv variable environ name cgi comes early days web users wanted connect databases web servers cgi program executed server provided common gateway web server database web server runs http server software responds requests web browsers generally http server directory folder designated document collection — files sent web browsers connected server example web server domain name codice_1 document collection stored codice_2 local file system web server respond request codice_3 sending browser pre-written file codice_4 pages constructed fly server software may defer requests separate programs relay results requesting client usually web browser displays page end user early days web programs usually small written scripting language hence known scripts programs usually require additional information specified request instance wikipedia implemented script one thing script would need know whether user logged logged name content top wikipedia page depends information http provides ways browsers pass information web server e.g part url server software must pass information script somehow conversely upon returning script must provide information required http response request http status request document content available document type e.g html pdf plain text et cetera initially different server software would use different ways exchange information scripts result n't possible write scripts would work unmodified different server software even though information exchanged therefore decided establish standard way exchanging information cgi common gateway interface defines common way server software interface scripts webpage generating programs invoked server software operate according cgi standard known cgi scripts standard quickly adopted still supported well-known server software apache iis extension node.js-based servers early use cgi scripts process forms beginning html html forms typically action attribute button designated submit button submit button pushed uri specified action attribute would sent server data form sent query string action specifies cgi script cgi script would executed produces html page web server allows owner configure urls shall handled cgi scripts usually done marking new directory within document collection containing cgi scripts — name often codice_5 example codice_6 could designated cgi directory web server web browser requests url points file within cgi directory e.g. codice_7 instead simply sending file codice_8 web browser http server runs specified script passes output script web browser anything script sends standard output passed web client instead shown on-screen terminal window remarked cgi standard defines additional information passed request passed script instance slash additional directory name appended url immediately name script example codice_9 path stored codice_10 environment variable script called parameters sent script via http get request question mark appended url followed param=value pairs example codice_11 parameters stored codice_12 environment variable script called parameters sent script via http post request passed script standard input script read environment variables data standard input adapt web browser request following perl program shows environment variables passed web server web browser issues request environment variables codice_13 64-bit windows 7 web server running cygwin returns following information variables defined cgi standard codice_10 codice_12 ones starting codice_16 pass information along http request environment seen web browser firefox running windows 7 pc web server apache running system emulates unix cgi script named codice_17 program could generate content write standard output web server transmit browser following environment variables passed cgi programs program returns result web server form standard output beginning header blank line header encoded way http header must include mime type document returned headers supplemented web server generally forwarded response back user simple cgi program written python 3 along html handles simple addition problem doctype html html /html import cgi import cgitb cgitb.enable input_data cgi.fieldstorage print 'content-type text/html html following print leave blank line print h1 addition results /h1 try except print p 0 1 2 /p '.format num1 num2 num1 num2 python 3 cgi gets inputs html adds two numbers together web server supports cgi configured interpret url serves reference cgi script common convention codice_42 directory base directory tree treat executable files within directory security cgi scripts another popular convention use filename extensions instance cgi scripts consistently given extension codice_43 web server configured interpret files cgi scripts convenient required many prepackaged scripts opens server attack remote user upload executable code proper extension case http put posts user-submitted data provided program via standard input web server creates subset environment variables passed adds details pertinent http environment cgi often used process inputs information user produce appropriate output example cgi program one implementing wiki user agent requests name entry web server executes cgi cgi program retrieves source entry page one exists transforms html prints result web server receives input cgi transmits user agent edit page link clicked cgi populates html codice_44 editing control page contents saves back server user submits form calling command generally means invocation newly created process server starting process consume much time memory actual work generating output especially program still needs interpreted compiled command called often resulting workload quickly overwhelm server overhead involved process creation reduced techniques fastcgi prefork interpreter processes running application code entirely within web server using extension modules mod_perl mod_php another way reduce overhead use precompiled cgi programs e.g writing languages c c++ rather interpreted compiled-on-the-fly languages perl php implementing page generating software custom webserver module alternative approaches include optimal configuration web application depends application-specific details amount traffic complexity transaction tradeoffs need analyzed determine best implementation given task time budget web frameworks offer alternative using cgi scripts interact user agents
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Web technology
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intelliquip intelliquip llc develops browser-based software also known intelligent front-end basic function company software automate front-end sales process complex equipment software specialized fluid handling equipment industry compatible pumps compressors valves blowers turboexpanders heat exchangers actuators filters seals couplings motors variable-frequency drives intelliquip browser-based software incorporates concept software service saas means deploy subscription-based hosted service users access via internet without need install software user computer saas platform intelliquip ’ intelligent front-end allows clients deploy selection configuration solutions equipment directly internal sales force sales channels company licensed fpx llc patented core configurator engine use software intelliquip also member hydraulic institute largest association pump industry manufacturers north america part hydraulic institute electronic data exchange committee participate project fiatech adopt aex cfixml schemas implement intelliquip software initiative developing standards automate information exchange design procurement delivery installation operation maintenance engineered equipment
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Distributed computing architecture
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duplicati duplicati backup client securely stores encrypted incremental compressed remote backups local files cloud storage services remote file servers duplicati supports various online backup services like onedrive amazon s3 backblaze rackspace cloud files tahoe lafs google drive also servers support ssh/sftp webdav ftp duplicati uses standard components rdiff zip aescrypt gnupg allows users recover backup files even duplicati available released terms gnu lesser general public license lgpl duplicati free software duplicati written mostly c implemented completely within clr enables cross-platform runs well 32-bit 64-bit versions windows macos linux using either .net framework mono duplicati graphical user interface wizard-style interface command-line version use headless environments interfaces use core thus set features capabilities command-line version similar duplicity interface duplicati unique features usually found commercial systems remote verification backup files disk snapshots backup open files disk snapshots performed vss windows lvm linux original duplicati project started june 2008 intended produce graphical user interface duplicity program included port duplicity code use windows dropped september 2008 work clean re-implementation began re-implementation includes sub-programs found duplicity rdiff ftp etc initial version duplicati saw initial release june 2009 2012 work duplicati 2 started complete rewrite includes new storage engine allows efficient incremental continuous backups new user interface web-based makes possible install duplicati 2 headless systems like servers nas also responsive easily used mobile devices even though duplicati 2 still beta already 20,000 active installations duplicati gui command-line interface call common component called main serves binding point operations supported currently encryption compression storage component considered subcomponent loaded runtime making possible third-party developer inject subcomponent duplicati without access source need modify duplicati license type also flexible enough allow redistribution duplicati closed-source storage provider duplicati designed independent provider possible means storage medium supports common commands get/put/list/delete work duplicati duplicity model duplicati based relies heavily components system librdiff tcftp others since duplicati intended cross-platform unlikely components available platforms duplicati re-implements components instead notably duplicati features rdiff aescrypt implementation work system supports clr runtime duplicati gui duplicati 1.x intended used single machine display attached however also possible install duplicati windows service linux daemon set duplicati system tray starting duplicati service limitation addressed duplicati 2 web interface used headless systems duplicati 1.x extremely slow file listings browsing file tree restores take long time since duplicati produces incremental backups corrupt missing incremental volume render following incremental backups next full backup useless duplicati 2 regularly tests backup detect corrupted files early duplicati 1.x stores file modification date metadata like permissions attributes addressed duplicati 2
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Computer security
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stemming linguistic morphology information retrieval stemming process reducing inflected sometimes derived words word stem base root form—generally written word form stem need identical morphological root word usually sufficient related words map stem even stem valid root algorithms stemming studied computer science since 1960s many search engines treat words stem synonyms kind query expansion process called conflation computer program subroutine stems word may called stemming program stemming algorithm stemmer stemmer english operating stem cat identify strings cats catlike catty stemming algorithm might also reduce words fishing fished fisher stem fish stem need word example porter algorithm reduces argue argued argues arguing argus stem argu first published stemmer written julie beth lovins 1968 paper remarkable early date great influence later work area paper refers three earlier major attempts stemming algorithms professor john w. tukey princeton university algorithm developed harvard university michael lesk direction professor gerard salton third algorithm developed james l. dolby r consultants los altos california later stemmer written martin porter published july 1980 issue journal program stemmer widely used became de facto standard algorithm used english stemming dr. porter received tony kent strix award 2000 work stemming information retrieval many implementations porter stemming algorithm written freely distributed however many implementations contained subtle flaws result stemmers match potential eliminate source error martin porter released official free software mostly bsd-licensed implementation algorithm around year 2000 extended work next years building snowball framework writing stemming algorithms implemented improved english stemmer together stemmers several languages paice-husk stemmer developed chris paice lancaster university late 1980s iterative stemmer features externally stored set stemming rules standard set rules provides 'strong stemmer may specify removal replacement ending replacement technique avoids need separate stage process recode provide partial matching paice also developed direct measurement comparing stemmers based counting over-stemming under-stemming errors several types stemming algorithms differ respect performance accuracy certain stemming obstacles overcome simple stemmer looks inflected form lookup table advantages approach simple fast easily handles exceptions disadvantages inflected forms must explicitly listed table new unfamiliar words handled even perfectly regular e.g cats cat table may large languages simple morphology like english table sizes modest highly inflected languages like turkish may hundreds potential inflected forms root lookup approach may use preliminary part-of-speech tagging avoid overstemming lookup table used stemmer generally produced semi-automatically example word run inverted algorithm might automatically generate forms running runs runned runly last two forms valid constructions unlikely.. suffix stripping algorithms rely lookup table consists inflected forms root form relations instead typically smaller list rules stored provides path algorithm given input word form find root form examples rules include suffix stripping approaches enjoy benefit much simpler maintain brute force algorithms assuming maintainer sufficiently knowledgeable challenges linguistics morphology encoding suffix stripping rules suffix stripping algorithms sometimes regarded crude given poor performance dealing exceptional relations like 'ran 'run solutions produced suffix stripping algorithms limited lexical categories well known suffixes exceptions however problem parts speech well formulated set rules lemmatisation attempts improve upon challenge prefix stripping may also implemented course languages use prefixing suffixing suffix stripping algorithms may differ results variety reasons one reason whether algorithm constrains whether output word must real word given language approaches require word actually exist language lexicon set words language alternatively suffix stripping approaches maintain database large list known morphological word roots exist real words approaches check list existence term prior making decision typically term exist alternate action taken alternate action may involve several criteria non-existence output term may serve cause algorithm try alternate suffix stripping rules case two suffix stripping rules apply input term creates ambiguity rule apply algorithm may assign human hand stochastically priority one rule another algorithm may reject one rule application results non-existent term whereas overlapping rule example given english term friendlies algorithm may identify ies suffix apply appropriate rule achieve result friendl friendl likely found lexicon therefore rule rejected one improvement upon basic suffix stripping use suffix substitution similar stripping rule substitution rule replaces suffix alternate suffix example could exist rule replaces ies affects algorithm varies algorithm design illustrate algorithm may identify ies suffix stripping rule well suffix substitution rule apply since stripping rule results non-existent term lexicon substitution rule substitution rule applied instead example friendlies becomes friendly instead friendl diving details common technique apply rules cyclical fashion recursively computer scientists would say applying suffix substitution rule example scenario second pass made identify matching rules term friendly ly stripping rule likely identified accepted summary friendlies becomes via substitution friendly becomes via stripping friend example also helps illustrate difference rule-based approach brute force approach brute force approach algorithm would search friendlies set hundreds thousands inflected word forms ideally find corresponding root form friend rule-based approach three rules mentioned would applied succession converge solution chances brute force approach would slower lookup algorithms direct access solution rule-based try several options combinations choose result seems best complex approach problem determining stem word lemmatisation process involves first determining part speech word applying different normalization rules part speech part speech first detected prior attempting find root since languages stemming rules change depending word part speech approach highly conditional upon obtaining correct lexical category part speech overlap normalization rules certain categories identifying wrong category unable produce right category limits added benefit approach suffix stripping algorithms basic idea stemmer able grasp information word stemmed apply accurate normalization rules unlike suffix stripping rules also modify stem stochastic algorithms involve using probability identify root form word stochastic algorithms trained learn table root form inflected form relations develop probabilistic model model typically expressed form complex linguistic rules similar nature suffix stripping lemmatisation stemming performed inputting inflected form trained model model produce root form according internal ruleset similar suffix stripping lemmatisation except decisions involved applying appropriate rule whether stem word return word whether apply two different rules sequentially applied grounds output word highest probability correct say smallest probability incorrect typically measured lemmatisation algorithms stochastic given word may belong multiple parts speech probability assigned possible part may take account surrounding words called context context-free grammars take account additional information either case assigning probabilities possible part speech likely part speech chosen appropriate normalization rules applied input word produce normalized root form stemming techniques use n-gram context word choose correct stem word hybrid approaches use two approaches described unison simple example suffix tree algorithm first consults lookup table using brute force however instead trying store entire set relations words given language lookup table kept small used store minute amount frequent exceptions like ran run word exception list apply suffix stripping lemmatisation output result linguistics term affix refers either prefix suffix addition dealing suffixes several approaches also attempt remove common prefixes example given word indefinitely identify leading prefix removed many approaches mentioned earlier apply go name affix stripping study affix stemming several european languages found algorithms use stem database example set documents contain stem words stems mentioned necessarily valid words rather common sub-strings brows browse browsing order stem word algorithm tries match stems database applying various constraints relative length candidate stem within word example short prefix stem words would considered stem word beside .. much early academic work area focused english language significant use porter stemmer algorithm many languages investigated hebrew arabic still considered difficult research languages stemming english stemmers fairly trivial occasional problems dries third-person singular present form verb dry axes plural axe well axis stemmers become harder design morphology orthography character encoding target language becomes complex example italian stemmer complex english one greater number verb inflections russian one complex noun declensions hebrew one even complex due nonconcatenative morphology writing system without vowels requirement prefix stripping hebrew stems two three four characters multilingual stemming applies morphological rules two languages simultaneously instead rules single language interpreting search query commercial systems using multilingual stemming exist two error measurements stemming algorithms overstemming understemming overstemming error two separate inflected words stemmed root been—a false positive understemming error two separate inflected words stemmed root not—a false negative stemming algorithms attempt minimize type error although reducing one type lead increasing example widely used porter stemmer stems universal university universe univers case overstemming though three words etymologically related modern meanings widely different domains treating synonyms search engine likely reduce relevance search results example understemming porter stemmer alumnus → alumnu alumni → alumni alumna alumnae → alumna english word keeps latin morphology near-synonyms conflated stemming used approximate method grouping words similar basic meaning together example text mentioning daffodils probably closely related text mentioning daffodil without cases words morphological stem idiomatic meanings closely related user searching marketing satisfied documents mentioning markets marketing stemmers common elements query systems web search engines effectiveness stemming english query systems soon found rather limited however led early information retrieval researchers deem stemming irrelevant general alternative approach based searching n-grams rather stems may used instead also stemmers may provide greater benefits languages english stemming used determine domain vocabularies domain analysis many commercial companies using stemming since least 1980s produced algorithmic lexical stemmers many languages snowball stemmers compared commercial lexical stemmers varying results google search adopted word stemming 2003 previously search fish would returned fishing software search algorithms vary use word stemming programs simply search substrings obviously find fish fishing searching fishes find occurrences word fish
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Computational linguistics
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claasen law claasen logarithmic law usefulness named technologist theo a. c. m. claasen introduced idea 1999 cto philips semiconductors law also expressed system parameters e.g ram cpu speed disk capacity need increase multiple create noticeable impact performance case ram law 256mb unit practically useful 128mb unit though base unit doubled would require 16384mb 128 × 128mb unit ram truly double performance law modern car e.g ford mondeo substantially useful getting occupants b older car e.g ford model order achieve linear improvement usefulness time necessary exponential increase technology time moore law delivers exponential increase technology claasen law combined moore law implies linear improvement usefulness time
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Computer architecture
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baikal cpu baikal cpu line mips arm-based microprocessors developed fabless design firm baikal electronics spin-off russian supercomputer company t-platforms judging information available online sources baikal electronics selected different approach compared russian microprocessor initiatives elbrus-2sm elbrus-8s mcst multiclet line chips design baikal electronics based existing commercial ip cores imagination technologies arm holdings compared innovative approach multiclet elbrus cpu history dating back elbrus supercomputers soviet union march 2015 synopsys inc. announced baikal electronics selected synopsys solutions accelerate design verification advanced system chips may 2015 baikal electronics imagination technologies announced first commercial baikal microprocessor based mips warrior p5600 called baikal-t1 first samples new cpu available starting june 2015 baikal-t1 mainly targets applications networking industrial automation features hardware support virtualization high performance 128-bit simd engine march 2016 announced imagination technologies blog desktop pc called tavolga terminal also known meadowsweet terminal pc available order t-platforms computer based baikal-t1 cpu sm750 graphics processing unit debian linux operating system
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Computer architecture
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reach authorisation procedure authorisation procedure one regulatory tools european regulation ec reach n°1907/2006 aiming ban use substances high concern svhc included annex xiv reach substitute technically economically feasible alternatives process concerns manufacturers importers downstream users substances representatives foreign manufacturers also apply authorisation authorisation today impacts many industries including aerospace electronics automotive energy paint industries moreover defence applications de facto exempted authorisation process member states must decide case case basis whether company benefit procedure outlined article 2.3 reach reach regulation relies four main procedures registration evaluation restriction authorisation chemical substances eu member states european chemicals agency request european commission submit propositions identify substances high concern based criteria laid article 57 reach work supported expert groups echa eu member states based various criteria screening methodologies order identify relevant svhcs annex xiv last step prioritisation process lists svhcs exhibit particularly high risk human health environment based inherent properties quantities uses order forbid use eu market recommendations include svhcs annex xiv made echa debated relevant stakeholders member states companies ngos etc. final decision inclusion substance annex xiv taken european commission listed annex xiv reach regulation substance therefore assigned “ sunset date ” use banned unless authorisation granted definite period time today 2015/05/26 161 substances listed candidate list 31 substances listed annex xiv candidate list usually updated every 6 months annex xiv updated every 12 18 months authorisation procedure complex concerns manufacturers importers downstream users representatives substances banning use takes effect sunset date date use substance possible companies granted authorisation submitted dossier latest application date latter indeed benefit transitional period pending eu commission final decision exception made downstream users case upstream stakeholder within supply chain granted authorisation substance use point view supply chain substance matters instance subcontractors authorised importers covered annex xiv substance use supplied via supply chain authorisation application made granted finally downstream users need apply authorisation nevertheless obligation notify use echa art 66 reach check compliance risk management measures concerned companies thus invited take measures soon substance use enters candidate list enquiring impacted actors strategies authorisation applications made one several specific uses article 3 reach thus defines “ use ” “ processing formulation consumption storage keeping treatment filling containers transfer one container another mixing production article use ” framework authorisation dossier description use applied specify market supply chain processes type articles concerned use applied consistent enough cover exposure scenario also analysis alternatives use applied mistaken identified use corresponds reach registration process identified use focuses process consider performances markets questions exceptions exist application authorisation required production article may require authorisation point finished articles require authorisation put market even though still contain substance subject authorisation consequently articles requiring use annex xiv substance still produced outside eu imported particular case future restrictions procedure could however limit placing market articles risk remains art 58.6 reach review period duration eu commission authorises use substance sunset date following durations considered review periods end review period application authorisation reassessed evaluate progress made terms research development substitution applications extend review period made latest 18 months expiry date european commission may also reduce duration new circumstances appear terms risks impacts court european union qualified rule appeals applications authorisation member states turn responsible controlling decision implementation application authorisation afa made three main parts chemical safety report csr analysis alternatives aoa socio-economic analysis sea goal dossier demonstrate alternative substance immediately available risks controlled social economic advantages use substance outweigh risks human health environment dossier usually takes 6 18 months preparation echa guidelines available assist drafting application authorisation filed latest application date lad set 18 months sunset date lad enables benefit transitional period pending european commission decision afa made one several substances case grouping need demonstrated basis annex xi reach one several uses applied one several companies latter case called joint application requires appointing main applicant contact point echa two submission routes planned reach regulation adequate control route goal chemical safety report prove threshold values respected socio-economic route goal chemical safety report demonstrate risks reduced minimum chemical safety report contains aoa aims demonstrate alternative appropriate i.e technically economically feasible less risky available analysis alternatives therefore presents substance alternative solutions contains socio-economic analysis compulsory document socio-economic route also complete application justified adequate control route aims demonstrate advantages use substance outweigh risks human health environment purpose applicants must compare two scenarios ‘ use scenario ’ continued use substance one hand ‘ non-use scenario ’ cease use substance hand discuss impacts contains dossiers submitted submission windows february may august november echa strongly advise follow windows plenary sessions two committees rac seac organised march june september december year submitting plenary sessions submission windows therefore helps efficient assessment application applications deemed received business rules check successfully passed provided echa fees paid time examination dossier carried risk assessment committee rac socio-economic analysis committee seac opens public consultation alternatives 8 weeks companies ngos interested party possibility comment possibly challenge alternatives proposed applicant consultation followed additional discussions two committees order clarify application process called trialogue stakeholders invited participate duration examination varies according complexity clarity dossier committees however obligation deliver first opinion dossier 10 months submission latest dossier committee opinion sent commission whole process take 2 years may 4 2015 28 applications authorisation filed total 56 uses dossier requires implementing specific strategy define uses analysis industrial processes associated risks alternatives socio-economic impacts banning substance committees expect dossier contain precise description industrial process operational conditions representative dossier well risk management measures implemented applicant main issue application authorisation process duration review period granted therefore critical bring necessary precisions dossiers justify requested review period duration justification weak argumentation generic may induce granting shorter-than-requested review period beyond simple drafting application authorisation dossier whole process implies expertise deep analysis company activity multiple aspects analysis therefore requires extensive collection information also possibly contacts customers strengthen analysis alternatives public consultation one core mechanisms authorisation process stakeholders ’ competing companies universities laboratories ngos member states etc involvement consultation process growing last years reach 400 comments single dossier influence comments particular concerning alternatives makes major step authorisation process order streamline process templates comments instructions available echa website consulting costs application authorisation estimated echa amounts average around 230,000 eur single use
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Computer security
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iphone 4 iphone 4 smartphone designed marketed apple inc fourth generation iphone succeeding 3gs preceding 4s following number notable leaks iphone 4 first unveiled june 7 2010 apple worldwide developers conference san francisco released june 24 2010 united states united kingdom france germany japan iphone 4 introduced new hardware design iphone family apple ceo steve jobs touted thinnest smartphone world time consisted stainless steel frame doubles antenna internal components situated aluminosilicate glass iphone 4 also introduced apple new high-resolution retina display pixel density 326 pixels per inch maintaining physical size aspect ratio precursors iphone 4 also introduced apple a4 system-on-chip along ios 4—which notably introduced multitasking functionality apple new facetime video chat service iphone 4 also first iphone include front-facing camera first released version cdma networks ending period exclusive carrier iphone products united states iphone 4 received generally positive reception critics praising revamped design powerful hardware comparison previous models market success 600,000 pre-orders within 24 hours release iphone 4 plagued highly publicized reports abnormalities new antenna design caused device lose cellular signal held certain way human contact phone outer edge would cause significant decrease signal strength iphone 4 spent longest time apple flagship iphone model fifteen months although succeeding 4s announced october 2011 4 continued sold midrange model september 2012 thereafter entry-level offering apple lineup september 2013 announcement iphone 5s/iphone 5c iphone 4 longest lifespan iphone ever produced spanning close four years available developing countries early 2015 official unveiling iphone 4 june 7 2010 two prototypes brought attention media breaching apple normally secretive development process many speculations regarding technical specifications proved accurate january 27 2010 gadget website engadget received leaked images unreleased ipad unbeknownst editors readers images contained two unreleased iphone 4s n't subsequent gizmodo release aware complete contents images april 19 2010 gadget website gizmodo reported purchased iphone prototype 5000 furthermore conducted product teardown device prototype reported lost apple employee gray powell redwood city california shortly gizmodo published detailed information prototype apple legal associates formally requested phone returned apple gizmodo responded intent cooperate april 23 officers rapid enforcement allied computer team react task force california httap program raided home jason chen gizmodo editor responsible reviewing prototype seizing computers hard drives electronic frontier foundation criticized raid violating journalist source protection laws forbid seizure journalist computers well suspicion apple used influence member steering committee charged direction oversight california react task force push police action way would normally conducted type incident apple already received iphone prototype raid returned gizmodo district attorney stated investigation suspended discontinued searching gizmodo editor belongings determine whether shield laws applicable cautioned charges issued point pictures video second prototype published vietnamese website taoviet may 12 2010 almost identical first used a4 chip manufactured apple website purchased prototype 4,000 digitimes reported screen resolution new phone 960-by-640 confirmed apple iphone 4 official announcement iphone 4 available pre-order june 15 2010 customers attempting pre-order iphone 4 reported problems pre-order process us uk online apple stores crashed due surge traffic issue reported softbank apple exclusive partners united states japan respectively suspended advance sales iphone 4 demand threatened exceed supply retail stores also unable complete pre-order transactions due servers crashing apple partner carriers received 600,000 pre-orders iphone 4 first 24 hours largest number pre-orders apple received single day device point engadget reported 20:30 utc iphone 4 pre-order suppliers sold 1.7 million iphone 4s sold first three days availability iphone 4 also released orange tunisia available eight cities launch july 30 2010 iphone 4 made available sale australia new zealand 15 countries free bumper cases south korea released kt september 10 israel released september 24 cellcom pelephone orange launched thailand september 23 ais dtac true move malaysia september 26 kuala lumpur nationwide september 27 according website maxis iphone 4 released south africa september 22 vodacom mtn networks limited quantities iphone 4 launched vietnam september 30 vinaphone viettel first 3 major cities hanoi ho chi minh city da nang country end october iphone 4 launched india may 27 2011 aircel airtel january 11 2011 verizon wireless announced media event reached agreement apple would begin selling cdma iphone 4 united states ending apple exclusivity agreement verizon iphone went sale february 10 pre orders began february 3 verizon iphone includes 'personal hotspot feature allows user use iphone wireless hotspot five devices connecting one time february 3 2011 presale iphone 4 broke verizon first day sales records single device june 24 2010 apple issued statement white iphone 4 models proving challenging manufacture expected initially pushed release date back second half july lot speculation surrounding delay white iphone 4 among popular rumors concerning phone internal camera adversely affected light leaking due semi-translucent glass white paint sources report problem relates apple inability match white color front face plate home button april 27 2011 apple announced would releasing white iphone 4 model april 28 2011 gsm cdma release white iphone 4 carried april 28 apple official unveiling iphone 4s october 4 2011 announced sprint would begin carrying reconfigured cdma iphone 4 iphone 4s us october 14 september 2013 release iphone 5s iphone 5c apple stopped selling iphone 4 stores well website replaced 8 gb iphone 4s display iphone 4 manufactured lg exclusive contract apple features led backlit tft lcd capacitive touchscreen pixel density 326 pixels per inch ppi diagonally measured 960×640 display pixel 78 micrometers width display contrast ratio 800:1 screen marketed apple retina display based assertion display approximately 300 ppi distance one eye 57 arcseconds per pixel maximum amount detail human retina perceive iphone expected used distance 12 inches eyes higher resolution would allegedly effect image apparent quality maximum potential human eye already met claim disputed raymond soneira president displaymate technologies said interview wired magazine claims jobs something exaggeration reasonably close perfect display steve pushed little far soneira stated resolution human retina higher claimed apple working 477 ppi eyes 36 arcseconds per pixel however phil plait author bad astronomy whose career includes collaboration nasa regarding camera hubble space telescope responded criticism stating better 20/20 eyesight one foot away iphone 4 pixels resolved picture look pixellated average eyesight picture look fine iphone 4 features additional front-facing vga camera backside-illuminated 5 megapixel rear-facing camera 3.85 mm f/2.8 lens led flash rear-facing camera capable recording hd video 720p 30 frames per second cameras make use tap focus feature part ios 4 photo video recording rear-facing camera 5× digital zoom contrast steve jobs announcement wwdc 2010 recent federal communications commission documentation shown iphone 4 contains penta-band 3g umts antenna quad-band 3g umts radio advertised apple according fcc documentation filed apple radio inside iphone 4 supports 800 850 900 1,900 2,100 mhz 800 mhz frequency commonly used japanese mobile phones advertised supported apple however 800 mhz band subset 850 mhz band probably explains device advertised quad-band chip-sets manufactured skyworks solutions infineon gsm version apple mobile products time iphone 4 also used 30 pin dock connector external data port iphone 4 first generation iphone second microphone used noise cancellation located top unit near headphone jack main microphone bottom left iphone 4 introduces gyroscopic sensor detects 3-axis angular acceleration around x z axes enabling precise calculation yaw pitch roll gyroscope complements accelerometer sensor present since original iphone detects device acceleration shake vibration shock fall detecting linear acceleration along one three axes x z combined data accelerometer gyroscope provides detailed precise information device 6-axis movement space 3 axes gyroscope combined 3 axes accelerometer enable device recognize approximately far fast direction moved space iphone 4 powered apple a4 chip designed intrinsity like prior iphone models manufactured samsung system-on-a-chip composed arm cortex-a8 cpu integrated powervr sgx535 gpu apple a4 also used ipad clocked rated speed 1 ghz clock speed iphone 4 disclosed prior models iphone underclocked cpu typically extends battery life lowers heat dissipation iphone 4 512 mb dram additional dram supports increased performance multi-tasking iphone 4 uses micro-sim card iphone 4 devices running gsm network positioned ejectable tray located right side device cdma network however phone connects network using esn prior models used regular mini-sim cards depending operator micro-sim cards may available networks globally technical workaround possible trim mini-sim card knife scissors fits micro-sim tray prior models data stored flash memory 8 16 32 gb sim unlike prior generations storage capacity printed back unit iphone 4 features redesigned structure designed jony ive design would later reused adapted iphone 4s 5 5s se notably bulges back panel well band front back gone replaced flattened surfaces redesign reflects utilitarianism uniformity existing apple products ipad imac overall dimensions iphone 4 reduced predecessor high wide deep compared iphone 3gs high wide deep making iphone 4 24 thinner predecessor iphone 3gs steve jobs claimed thinnest smartphone planet reduced size device primarily due externally placed antenna iphone 4 structured around stainless steel frame wraps around edge phone acting primary structure device iphone 4 antennas metal band features two slits gsm version phone one lower left one top fake slit along lower right cosmetically mirror one lower left divide band two antenna sections left section band serves bluetooth wi-fi gps antenna right lower sections band act antenna gsm umts connectivity cdma version phone four slits metal band two top left right two bottom divides metal band four different segments like gsm version phone serves different antennas connectivity top portion band divided top left right slits connecting cdma network left portion metal band bluetooth wi-fi gps like gsm version right side antenna serves cosmetically mirror left side also create similar look gsm version phone internal components situated two panels aluminosilicate glass described apple chemically strengthened 20 times stiffer 30 times harder plastic theoretically allowing scratch resistant durable prior models fall 2010 pentalobe screws started replace philips screws used post-repair units us production units japan iphone 4 shipped ios 4 newest version apple ios mobile operating system time ios 4 introduced multitasking system allowing apps remain suspended memory perform certain operations background allowing users switch apps using on-screen menu also introduced facetime allows users perform video calls iphone ipad ipod touch os x users iphone 4 supports ios 7 released september 2013 due relatively aged hardware iphone 4 certain features available newer iphone models available device ios 7 include siri 3d maps turn-by-turn navigation airdrop airplay mirroring live camera filters panorama mode certain visual effects introduced ios 7 blurring translucent interface elements parallax effect home screen live wallpapers still subject limitations ios 7.1 bring slight performance improvements operating system iphone 4. ios 7 specifically ios 7.1.2 last version ios support iphone 4 unlike iphone 4s iphone 4 receive ios 8 update due performance issues iphone 4 bumper ring rubber plastic surrounds edge iphone 4 purpose protecting phone inner part rubber external band made plastic bumper wraps around edges device protecting edges lesser extent screen bumper cover front rear phone though slightly raise iphone whatever surface sitting additionally plastic band houses metallic buttons volume controls sleep/wake button six holes bumper enable access mute switch dock connector headphone jack speaker microphones apple updated bumper wider volume switch hole release iphone 4 cdma network updated bumper also compatible iphone 4s next generation iphone identical exterior design measurements iphone 4 cdma pre-release reception generally positive announcement included information covered gizmodo fox news commented seeing action far informative staring gizmodo photos busted test unit rhodri marsden independent said aside introduction face-to-face video calling staggering feature set instead focusing device powerful predecessor speedier easier use make previously laborious tasks seem like cinch cnet reacted announcement explaining believes imovie ios exciting part year wwdc keynote article noted iphone 4 unlike current cameras record hd content edit device labeling true mobile editing suite reviews iphone 4 generally favorable walt mossberg wall street journal called device best device class engadget named best smartphone market june 2010 cnet gave iphone 4 rating 8.6 10 one highest ratings given smartphone techradar gave device 4.5/5 stars consumer reports said signal problem reason rate recommended model although tests ranked highest among smart phones joshua topolsky engadget described device industrial design detailed sophisticated predecessor users reported yellow discoloration screen disappeared several days attributed glass lamination glue used time dry fully unit reached consumers due speed manufacturing another issue reported users within days iphone 4 release calls proximity sensor insensitive facial contact touchscreen end calls mute calls dial numbers users reported particularly low-light conditions photos taken iphone 4 sometimes contained blue green splotches issues white balance also discovered particularly using flash shortly iphone 4 launched consumers reported signal strength phone reduced touching lower left edge phone bridging one two locations separates two antennas resulting dropped calls areas lower signal reception response apple issued statement advising customers avoid gripping phone lower left corner making receiving call consequence problem reported july 2 2010 several iphone 4 users planning suing apple fraud concealment negligence intentional misrepresentation defective design legal challenge started law firm set website recruit disenchanted iphone 4 buyers lawsuit apple later day apple issued another statement stating discovered cause dramatic drop bars apple explained formula used calculate number bars display wrong apple promised correct issue release software update within weeks would address mistake present since original iphone new york times commented failure detect longstanding problem earlier astonishing consumer reports initially stated iphone 4 signal issues unique may serious continued mention signal loss problem faced entire smartphone industry problem apple made formal apology next day magazine altered stance encountering instances dropped calls magazine rejected apple explanation conducting tests controlled environment comparing results prior generations iphone sarcastically pointed using piece tape cover lower left antenna gap one way fix problem recommended consumers want iphone works well without masking-tape fix purchase iphone 3gs instead magazine also tested iphone 4 wearing bumper frame-like cover sold apple prevents direct contact antenna reporting resolve problem cnn repeated consumer reports statement small amount duct tape proven effective fix iphone 4 dropped call issue july 16 2010 press conference steve jobs announced apple would provide iphone 4 owners free case help solve antenna issue refund users already purchased bumper free case offer would valid september 30 2010 apple would re-evaluate situation get free case owners able apply via app installed phone found app store july 22 2010 september 30 2010 jobs also announced apple could produce enough bumpers owners phone would source supply offer range cases additionally jobs cited figures applecare showed 0.55 percent iphone 4 users complained company issue number phones returned apple 1.7 percent – 4.3 percentage points less number iphone 3gs models returned first month phone launch consumer reports noted solution permanent though good first step however jobs specify time line fixing problem offering free bumper temporary solution pc world decided remove iphone 4 top 10 cell phones chart reassign pending rating despite negative media attention regarding antenna issues 72 iphone 4 users say satisfied iphone 4 according august 2010 survey changewave research iphone 4 model continued sold unchanged september 2013 2011 two iphone 4 units equipped special application taken international space station aboard space shuttle sts-135 mission devices used various experiments utilizing sensors special app
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Operating systems
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windows imaging component windows imaging component wic component object model based imaging codec framework introduced windows vista later available windows xp service pack 3 working processing digital images image metadata allows applications supporting framework automatically get support installed codecs graphics file formats similar directshow acm/vcm extended using image codecs support third-party graphics formats system-wide basis additionally windows presentation foundation applications also automatically support installed image codecs codecs raw image formats used high-end professional digital cameras also supported manner wic enables application developers perform image processing operations image format single set common apis without requiring prior knowledge specific image formats writing codec wic developers get system-wide support graphics file format applications use wic .net 3.x wpf windows imaging component provides extensible architecture image codecs pixel formats metadata automatic run-time discovery new formats supports reading writing arbitrary metadata image files ability preserve unrecognized metadata editing working images preserves high bit depth image data 32 bits per channel throughout revamped high dynamic range image processing pipeline built windows vista windows imaging component supports windows color system icc v4-compliant color management technology windows vista default windows vista ships jpeg tiff gif png bmp hd photo encoders decoders ico decoder additionally 2009 camera manufacturers 3rd-parties released wic codecs proprietary raw image formats enabling mac-like raw image support windows 7 vista july 2011 extended significantly microsoft providing separate codec pack current digital cameras progressive graphics file pgf viewer distributed wic codec wic supports exchangeable image file exif png textual metadata image file directory ifd iptc information interchange model iptc extensible metadata platform xmp formats addition wic includes extensible framework support third-party metadata implementations metadata format support per codec example native jpeg codec supports xmp native gif png codecs wic available windows xp service pack 2 stand-alone downloadable program built windows xp service pack 3 also available part .net framework 3.0 discontinued powertoy windows xp microsoft known photo info allows viewing editing image metadata windows explorer also uses wic starting windows vista windows explorer windows photo gallery based wic thus view organize images format wic codec installed office 2010 later versions core office apps word excel powerpoint outlook import image file formats supported wic starting windows 7 windows media center available windows 7 home premium wic-enabled also gdi+ graphic library built wic although gdi+ load 3rd-party external codecs windows 7 wic stack underwent major overhaul free-threaded built-in external codecs shipping windows free-threaded also requirement new codecs targeting windows 7 microsoft expression design import export capabilities entirely based wic expression media phase one media pro service pack 1 later also supports additional raw camera formats hd photo jpeg xr using wic 2018 third-party imaging applications image editors image organizers image viewers utilize wic fastpictureviewer simple standalone third-party image viewer supports standard image formats along hd photo raw camera formats nrw nef cr2 dng using wic experimental wic import plug-in adobe photoshop also found fastpictureviewer website another wic import plug-in gimp found gimp-forum.net
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Operating systems
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sleuth kit sleuth kit tsk library collection unix- windows-based utilities facilitate forensic analysis computer systems written maintained primarily digital investigator brian carrier sleuth kit capable parsing ntfs fat/exfat ufs 1/2 ext2 ext3 ext4 hfs iso 9660 yaffs2 file systems either separately within disk images stored raw dd expert witness aff formats sleuth kit used examine microsoft windows apple macintosh osx many linux unix computers sleuth kit used sleuth kit free open-source suite provides large number specialized command-line based utilities based coroner toolkit official successor platform tools included sleuth kit include
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Computer security
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mirror driver mirror driver display driver virtual device mirrors drawing operations one additional physical display devices video mirroring active time system draws primary video device location inside mirrored area copy draw operation executed mirrored video device real-time windows mirror drivers first introduced 1998 windows 2000 display driver model renamed later xpdm 2006 windows vista microsoft introduced new windows display driver model older drivers still supported vista since older model encompass support features first introduced vista newer features would necessarily disabled older driver active consequence mirror driver designed older model active windows remote assistance windows live mesh use vista disabled desktop window manager windows aero similar situation existed transition windows 7 windows 8 beginning ddk targeted windows 8 mirror drivers fulfill exacting specifications must support specific set functions windows installations come two mirror drivers preinstalled mnmdd used netmeeting rdpdd chained dd used terminal server/remotedesktop services third-party mirror drivers included screen readers jaws window-eyes freedombox monitoring software lanschool remote desktop software timbuktu logmein ultravnc tightvnc radmin remotepc
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Operating systems
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sap cloud platform sap cloud platform platform service developed sap se creating new applications extending existing applications secure cloud computing environment managed sap sap cloud platform integrates data business processes sap cloud platform open platform-as-a-service includes in-memory sap hana database management system connects premises cloud-based systems running sap third-party software relies open standards like java javascript node.js cloud foundry integration options sap cloud platform promoted build extend business applications rapid innovation cycles sap apple inc. partnered develop mobile applications ios using cloud-based software development kits sdks sap cloud platform sap cloud platform based open source technology developed supported partnership suse company also partnership cloud foundry beta offering sap cloud platform enables customers test give feedback functionalities coming cloud foundry initially unveiled sap netweaver cloud belonging sap hana cloud portfolio october 16 2012 cloud platform reintroduced new name sap hana cloud platform may 13 2013 foundation sap cloud products including sap businessobjects cloud adoption sap hana cloud platform increased steadily since platform launch 2012 sap claiming 4000 customers 500 partners adopting sap hana cloud platform february 27 2017 sap hana cloud platform renamed sap cloud platform mobile world congress sap cloud platform contains many services better overview assigned several categories following list contains categories defined sap applications available sap hana app center extend integrate applications customize existing applications extend mobile footprint mobile-first apps sap cloud platform organizations better engage customers empower employees developers build applications running cloud still access data premises clouds sap cloud platform developer edition offers users easy free way explore sap cloud platform capabilities addition 1gb shared sap hana sap cloud platform provides users
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Distributed computing architecture
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anti-replay anti-replay sub-protocol ipsec part internet engineering task force ietf main goal anti-replay avoid hackers injecting making changes packets travel source destination anti-replay protocol uses unidirectional security association order establish secure connection two nodes network secure connection established anti-replay protocol uses packet sequence numbers defeat replay attacks follows source sends message adds sequence number packet sequence number starts 0 incremented 1 subsequent packet destination maintains 'sliding window record sequence numbers validated received packets rejects packets sequence number lower lowest sliding window i.e old already appears sliding window i.e duplicates/replays accepted packets validated update sliding window displacing lowest sequence number window already full see also replay attack
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Internet protocols
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nemesis 3 eve destruction four distinct classes vixen chosen first one resembles original vic viper second one twisted version vic viper featuring new photon missile third one like metalion nemesis 2 featuring napalm missile extended fire blaster fourth one like sabel tiger salamander featuring 2-way missile approach ripple laser four classes may choose classic shield force field takes less hits expire protects direction also possible choose behavior option original shadow movement fixed rolling like option warrior nemesis 2 game retains several new weapons introduced nemesis 2 like laser fire blaster vector laser well salamander weapons like meteor laser screw laser game nemesis series visibly keeps track number speed boosts order upgrade ship weapons secret spots must found like secret stages nemesis 2 predictions salamander
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Computer architecture
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persistent programming language programming languages natively seamlessly allow objects continue existing program closed called persistent programming languages jade one language persistent programming language programming language extended constructs handle persistent data distinguished embedded sql least two ways persistent programming language embedded sql using embedded sql programmer responsible writing explicit code fetch data memory store data back database persistent programming language programmer manipulate persistent data without write code explicitly drawbacks persistent programming languages include
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Programming language topics
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nlx motherboard form factor nlx new low profile extended form factor proposed intel developed jointly ibm dec vendors low profile low cost mass-marketed retail pcs release 1.2 finalized march 1997 release 1.8 finalized april 1999 nlx similar overall design lpx including riser card low-profile slimline case modernized updated allow support latest technologies keeping costs fixing main problems lpx specified motherboards size officially nlx form factor designed use atx power supplies featured soft power function however nlx cases instead used smaller sfx form factor proprietary form factors 20-pin connector many slimline systems formerly designed fit lpx form factor modified fit nlx nlx true standard unlike lpx making interchangeability components easier older form factor ibm gateway nec produced fair number nlx computers late 1990s primarily socket 370 pentium ii-iii celeron nlx never enjoyed widespread acceptance lpx importantly one largest pc manufacturers dell decided using nlx created proprietary motherboards use slimline systems although many computers motherboards still available secondhand new production essentially ceased slimline small form factor market nlx superseded micro-atx flexatx mini-itx form factors
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Computer architecture
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business process execution language web services business process execution language ws-bpel commonly known bpel business process execution language oasis standard executable language specifying actions within business processes web services processes bpel export import information using web service interfaces exclusively one describe web-service interactions two ways executable business processes abstract business processes ws-bpel aims model behavior processes via language specification executable abstract business processes extends web services interaction model enables support business transactions also defines interoperable integration model facilitate expansion automated process integration within businesses development came notion programming large programming small required different types languages serialized xml aims enable programming large concepts programming large programming small distinguish two aspects writing type long-running asynchronous processes one typically sees business processes origins ws-bpel go back web services flow language wsfl xlang 2001 ibm microsoft defined fairly similar programming large languages wsfl web services flow language xlang respectively microsoft even went ahead created scripting variant called xlang/s would later serve basis orchestrations services inside biztalk server specifically documented language proprietary fully documented advent popularity bpml growing success bpmi.org open bpms movement led jboss intalio inc. ibm microsoft decided combine languages new language bpel4ws april 2003 bea systems ibm microsoft sap siebel systems submitted bpel4ws 1.1 oasis standardization via web services bpel technical committee although bpel4ws appeared 1.0 1.1 version oasis ws-bpel technical committee voted 14 september 2004 name spec ws-bpel 2.0 change name aligned bpel web service standard naming conventions start ws- similar ws-security took account significant enhancements made bpel4ws 1.1 ws-bpel 2.0 discussing specific version moniker bpel commonly used june 2007 active endpoints adobe systems bea ibm oracle sap published bpel4people ws-humantask specifications describe human interaction bpel processes implemented ten original design goals associated bpel bpel orchestration language choreography language primary difference orchestration choreography executability control orchestration specifies executable process involves message exchanges systems message exchange sequences controlled orchestration designer choreography specifies protocol peer-to-peer interactions defining e.g. legal sequences messages exchanged purpose guaranteeing interoperability protocol directly executable allows many different realizations processes comply choreography realized writing orchestration e.g. form bpel process peer involved orchestration choreography distinctions based analogies orchestration refers central control conductor behavior distributed system orchestra consisting many players choreography refers distributed system dancing team operates according rules choreography without centralized control bpel focus modern business processes plus histories wsfl xlang led bpel adopt web services external communication mechanism thus bpel messaging facilities depend use web services description language wsdl 1.1 describe outgoing incoming messages addition providing facilities enable sending receiving messages bpel programming language also supports standard graphical notation ws-bpel oasis technical committee decided scope vendors invented notations notations take advantage fact constructs bpel block-structured e.g. sequence pick scope etcetera feature enables direct visual representation bpel process descriptions form structograms style reminiscent nassi–shneiderman diagram others proposed use substantially different business process modeling language namely business process model notation bpmn graphical front-end capture bpel process descriptions illustration feasibility approach bpmn specification includes informal partial mapping bpmn bpel 1.1 detailed mapping bpmn bpel implemented number tools including open-source tool known bpmn2bpel however development tools exposed fundamental differences bpmn bpel make difficult cases impossible generate human-readable bpel code bpmn models even difficult problem bpmn-to-bpel round-trip engineering generating bpel code bpmn diagrams maintaining original bpmn model generated bpel code synchronized sense modification one propagated bpel control structures 'if-then-elseif-else 'while well variable manipulation facilities depend use 'programming small languages provide logic bpel implementations must support xpath 1.0 default language design bpel envisages extensibility systems builders use languages well bpelj effort related jsr 207 may enable java function 'programming small language within bpel despite wide acceptance web services distributed business applications absence human interactions significant gap many real-world business processes fill gap bpel4people extended bpel orchestration web services alone orchestration role-based human activities well within context business process bpel4people extending bpel additional independent syntax semantic ws-humantask specification introduces definition human tasks notifications including properties behavior set operations used manipulate human tasks coordination protocol introduced order control autonomy life cycle service-enabled human tasks interoperable manner bpel4people specification introduces ws-bpel extension address human interactions ws-bpel first-class citizen defines new type basic activity uses human tasks implementation allows specifying tasks local process use tasks defined outside process definition extension based ws-humantask specification version 2.0 introduced changes new features
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Web technology
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iphone 1st generation iphone colloquially known iphone 2g iphone 1 2008 differentiate later models first smartphone designed marketed apple inc. years rumors speculation officially announced january 9 2007 later released united states june 29 2007 featured quad-band gsm cellular connectivity gprs edge support data transfer development iphone dated back 2005 former apple ceo steve jobs conceived idea design expanded upon next 2 years complete secrecy announced q1 2007 although several aspects iphone considered obsolete current standards device seen archetype current cell phones eliminating physical hardware buttons stylus favor touch-based user interface successor iphone 3g announced june 2008 2005 apple ceo steve jobs conceived idea using touchscreen interact computer way could directly type onto display instead requiring stylus common existing technology time decided device would require triple layered capacitive multi-touch touch screen new advanced technology time helped removing physical keyboard mouse tablet computer jobs recruited group apple engineers investigate idea side project jobs reviewed prototype user interface saw potential developing concept mobile phone whole effort called project purple 2 began 2005 apple created device secretive unprecedented collaboration cingular wireless mobility development cost collaboration estimated 150 million thirty-month period apple rejected design committee approach yielded motorola rokr e1 largely unsuccessful collaboration motorola instead cingular wireless gave apple liberty develop iphone hardware software in-house original iphone introduced steve jobs january 9 2007 keynote address macworld conference expo held moscone west san francisco california address jobs said day looking forward two half years today apple going reinvent phone jobs introduced iphone combination three devices widescreen ipod touch controls revolutionary mobile phone breakthrough internet communicator six weeks iphone released plastic screen replaced glass one jobs upset screen prototype carrying pocket scratched keys quick switch led bidding process manufacturing contractor foxconn opened new wing shenzhen factory complex specifically bid february 2007 lg electronics accused apple copying lg prada phone similar hardware functionality announced several weeks iphone iphone released united states june 29 2007 price 499 4 gb model 599 8 gb model requiring 2-year contract thousands people reported waited outside apple retail stores days device launch many stores reported stock shortages within hour availability avoid repeating problems playstation 3 launch caused burglaries even shooting off-duty police officers hired guard stores overnight later made available united kingdom france germany portugal republic ireland austria november 2007 six ten americans surveyed said knew iphone coming release iphone main competitors consumer business markets considered lg prada lg viewty samsung ultra smart f700 nokia n95 nokia e61i palm treo 750 palm centro htc touch sony ericsson w960 blackberry ipod touch touchscreen device media internet abilities interface iphone without ability connect cellular network phone functions internet access released september 5 2007 time apple significantly dropped price 8 gb model 599 399 still requiring 2-year contract discontinuing 4 gb model apple sold one millionth iphone five days later 74 days release receiving hundreds emails ... upset price drop apple gave store credit early adopters 16 gb model released february 5 2008 499 original launch price 4 gb model apple released sdk march 6 2008 allowing developers create apps would available starting iphone os version 2.0 free upgrade iphone users june 9 apple announced iphone 3g began shipping july 11 original iphone discontinued july 15 total sales volume came 6,124,000 units release iphone marketed running os x name operating system revealed iphone os release iphone sdk original iphone supported three major versions operating system discontinued iphone os 1 2 3 however full iphone os 3 feature set supported last update original iphone received iphone os 3.1.3 original operating system original iphone iphone os 1 marketed os x included visual voicemail multi-touch gestures html email safari web browser threaded text messaging youtube however many features like mms apps copy paste supported release leading hackers jailbreaking phones add features official software updates slowly added features iphone os 2 released july 11 2008 time release iphone 3g introduced third-party applications microsoft exchange support push e-mail enhancements iphone os 3 released june 17 2009 introduced copy paste functionality spotlight search home screen new features youtube app iphone os 3 available original iphone well iphone 3g however features iphone os 3 supported original iphone iphone os 3.1.3 last version iphone os ios released original iphone four writers given review models original iphone david pogue new york times walt mossberg wall street journal steven levy newsweek ed baig usa today new york times wall street journal published positive cautious reviews iphone primary criticisms relatively slow speed 2.5g edge network phone inability connect using 3g services wall street journal technology columnist walt mossberg concluded despite flaws feature omissions iphone balance beautiful breakthrough handheld computer time magazine named invention year 2007 mobile gazette reported whilst iphone many impressive points equally many bad ones noting lack 3g mms third-party applications weak camera without autofocus flash
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Operating systems
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komdiv-32 komdiv-32 family 32-bit microprocessors developed manufactured scientific research institute system development niisi russian academy sciences manufacturing plant niisi located dubna grounds kurchatov institute komdiv-32 processors intended primarily spacecraft applications many radiation hardened rad-hard microprocessors compatible mips r3000 integrated mips r3010 compatible floating-point unit
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Computer architecture
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online sas online sas also known online.net french cloud computing web hosting company founded xavier niel 1999 100 subsidiary iliad group company provides physical dedicated servers cloud computing architectures dedibox scaleway brands domain registration services bookmyname brand colocation services datacenters brand iliad datacenter company second player france gb/s internet traffic 1999 online started activities web hosting domain name registration services august 2002 domain name registrar bookmyname bought iliad concurrent ldcom may 2006 rental dedicated servers dedibox brand launched december 2008 iliad bought alice adsl also took construction operation datacenters launched 1999 isdnet bought cable wireless january 2000 acquired tiscali france june 2003 finally renamed iliad datacenter april 2010 online merges dedibox another subsidiary iliad bringing together different hosting activities single brand 2012 company opened third datacenter 11800 m² vitry-sur-seine 11 months construction works site received first tier-iii certification france uptime institute january 2014 since 2012 company publishes real time pue datacenters pue.online.net effort transparency 2013 online launched labs.online.net preview infrastructure service offer based dedicated hardware without virtualization based arm cpus hardware made factory near laval france april 2015 service left beta status renamed scaleway popularity platform grows online added servers x86_64 based cpus march 2016 online owns operates several data centers located île-de-france region past company operated also since august 2013 network online as12876 online s.a.s independent one free case allowed company move away closed interconnection policy internet service provider early 2015 company announced exceeded gb/s immediate internet traffic may 2016 online shows total gb/s capacity links weathermap present following internet exchange points france-ix equinix-ix ams-ix et neutral internet exchange
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Distributed computing architecture
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curry programming language curry experimental functional logic programming language based haskell language merges elements functional logic programming including constraint programming integration nearly superset haskell lacking support mostly overloading using type classes implementations provide anyway language extension münster curry compiler functional program set functions defined equations rules functional computation consists replacing subexpressions equal regards function definitions subexpressions replacements reductions possible value normal form obtained instance consider function double defined expression “ ” replaced latter replaced interpret operator “ ” defined infinite set equations e.g. etc similar way one evaluate nested expressions subexpressions replaced quoted also another order evaluation replace arguments operators right left case derivations lead result property known confluence follows fundamental property pure functional languages termed referential transparency value computed result depend order time evaluation due absence side effects simplifies reasoning maintenance pure functional programs many functional languages like haskell curry supports definition algebraic data types enumerating constructors instance type boolean values consists constructors declared follows functions booleans defined pattern matching i.e. providing several equations different argument values principle replacing equals equals still valid provided actual arguments required form e.g complex data structures obtained recursive data types instance list elements type elements arbitrary denoted type variable either empty list “ ” non-empty list “ ” consisting first element list type “ ” usually written finite lists x1x2 ... xn written x1x2 ... xn define operations recursive types inductive definitions pattern matching supports convenient separation different cases instance concatenation operation “ ” polymorphic lists defined follows optional type declaration first line specifies “ ” takes two lists input produces output list list elements unspecified type beyond application various programming tasks operation “ ” also useful specify behavior functions lists instance behavior function last yields last element list specified follows lists xs elements e xs e ∃ysyse xs based specification one define function satisfies specification employing logic programming features similarly logic languages functional logic languages provide search solutions existentially quantified variables contrast pure logic languages support equation solving nested functional expressions equation like yse solved instantiating ys list e value curry one define operation last follows symbol “ ” used equational constraints order provide syntactic distinction defining equations similarly extra variables i.e. variables occurring left-hand side defining equation explicitly declared “ ” order provide opportunities detect bugs caused typos conditional equation form l c r applicable reduction condition c solved contrast purely functional languages conditions evaluated boolean value functional logic languages support solving conditions guessing values unknowns condition narrowing discussed next section used solve kind conditions narrowing mechanism whereby variable bound value selected among alternatives imposed constraints possible value tried order remainder program invoked case determine validity binding narrowing extension logic programming performs similar search actually generate values part search rather limited testing narrowing useful allows function treated relation value computed directions curry examples previous section illustrate noted previous section narrowing thought reduction program term graph often many different ways strategies reduce given term graph antoy et al proved 1990s particular narrowing strategy needed narrowing optimal sense number reductions get normal form corresponding solution minimal among sound complete strategies needed narrowing corresponds lazy strategy contrast sld-resolution strategy prolog rule defining shown expresses fact actual argument must match result narrowing expression curry express property also following concise way haskell allow declaration since pattern left-hand side contains defined function pattern also called functional pattern functional patterns enabled combined functional logic features curry support concise definitions tasks requiring deep pattern matching hierarchical data structures since curry able solve equations containing function calls unknown values execution mechanism based non-deterministic computations similarly logic programming mechanism supports also definition non-deterministic operations i.e. operations delivers one result given input archetype non-deterministic operations predefined infix operation called choice operator returns one arguments operator defined following rules thus evaluation expression returns well computing non-deterministic operations computing free variables narrowing expressive power rules defining show important feature curry rules tried order evaluate operation hence one define operation insert element list indeterminate position operation defined returns permutation given input list due absence side effects functional logic program executed different strategies evaluate expressions curry uses variant needed narrowing strategy combines lazy evaluation non-deterministic search strategies contrast prolog uses backtracking search solutions curry fix particular search strategy hence implementations curry like kics2 user easily select search strategy like depth-first search backtracking breadth-first search iterative deepening parallel search
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Programming language topics
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list former ia-32 compatible processor manufacturers 32-bit intel architecture became dominant computing platform 1980s 1990s multiple companies tried build microprocessors compatible intel instruction set architecture companies successful mainstream computing market far amd market presence computing market couple product generations cyrix successful 386 486 generations products well pentium introduced list former ia-32 compatible microprocessor vendors
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Computer architecture
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commercial operating system cos cos-3xx commercial operating system name used digital equipment corporation family operating systems supported use dibol programming language combining features basic fortran cobol cos also supported rpg report program generator commercial operating system implemented run hardware pdp-8 pdp-11 family cos-310 developed pdp-8 provide operating environment dibol cos-310 system purchased package included desk vt-52 vdt video display tube pair eight inch floppy drives optionally could purchase one 2.5 mb hard drives removable media cos-310 one operating systems available decmate ii unlike tss-8 user 4k virtual machine cos user virtual 32k cos-350 developed support pdp-11 port dibol focus vendors turnkey software packages pre-cos-350 pdp 11/05 single-user batch-oriented implementation released multi-user pdp 11/10-based cos came 4 years later much powerful pdp-11/34 added significant configuration flexibility expansion capability
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Operating systems
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zombie computing computing zombie computer connected internet compromised hacker computer virus trojan horse program used perform malicious tasks one sort another remote direction botnets zombie computers often used spread e-mail spam launch denial-of-service attacks dos attacks owners zombie computers unaware system used way owner tends unaware computers metaphorically compared fictional zombies coordinated ddos attack multiple botnet machines also resembles zombie horde attack depicted fictional zombie films zombie computers used extensively send e-mail spam 2005 estimated 50–80 spam worldwide sent zombie computers allows spammers avoid detection presumably reduces bandwidth costs since owners zombies pay bandwidth spam also greatly furthers spread trojan horses trojans self-replicating rely movement e-mails spam grow whereas worms spread means similar reasons zombies also used commit click fraud sites displaying pay-per-click advertising others host phishing money mule recruiting websites zombies used conduct distributed denial-of-service ddos attacks term refers orchestrated flooding target websites large numbers computers large number internet users making simultaneous requests website server intended result crashing prevention legitimate users accessing site variant type flooding known distributed degradation-of-service committed pulsing zombies distributed degradation-of-service moderated periodical flooding websites done intent slowing rather crashing victim site effectiveness tactic springs fact intense flooding quickly detected remedied pulsing zombie attacks resulting slow-down website access go unnoticed months even years notable incidents distributed denial- degradation-of-service attacks past include attack upon spews service 2003 one blue frog service 2006 2000 several prominent web sites yahoo ebay etc clogged standstill distributed denial service attack mounted ‘ mafiaboy ’ canadian teenager attack grc.com discussed length perpetrator 13-year-old probably sardis mississippi identified gibson research web site steve gibson disassembled 'bot zombie used attack traced distributor account research describes operation 'bot'-controlling irc channel beginning july 2009 similar botnet capabilities also emerged growing smartphone market examples include july 2009 wild release sexy space text message worm world first botnet capable sms worm targeted symbian operating system nokia smartphones later month researcher charlie miller revealed proof concept text message worm iphone black hat briefings also july united arab emirates consumers targeted etisalat blackberry spyware program 2010s security community divided real world potential mobile botnets august 2009 interview new york times cyber security consultant michael gregg summarized issue way point smart phones desktops '80s
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Computer security
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internet group management protocol internet group management protocol igmp communications protocol used hosts adjacent routers ipv4 networks establish multicast group memberships igmp integral part ip multicast igmp used one-to-many networking applications online streaming video gaming allows efficient use resources supporting types applications igmp used ipv4 networks multicast management ipv6 networks handled multicast listener discovery mld part icmpv6 contrast igmp bare ip encapsulation network designed deliver multicast service using igmp might use basic architecture igmp operates host local multicast router switches featuring igmp snooping derive useful information observing igmp transactions protocol independent multicast pim used local remote multicast routers direct multicast traffic hosts sending multicasts hosts registered igmp receive igmp operates network layer network management protocols like icmp igmp protocol implemented particular host within router host requests membership group local router router listens requests periodically sends subscription queries single router per subnet elected perform querying function multilayer switches include igmp querier capability allow igmp snooping features work absence ip multicast capability larger network igmp vulnerable attacks firewalls commonly allow user disable needed three versions igmp igmpv1 defined igmpv2 defined igmpv3 initially defined updated defines igmpv3 mldv2 igmpv2 improves igmpv1 adding ability host signal desire leave multicast group igmpv3 improves igmpv2 supporting source-specific multicast introduces membership report aggregation versions backwards compatible router supporting igmpv3 support clients running igmpv1 igmpv2 igmpv3 igmpv1 uses query-response model queries sent 224.0.0.1 membership reports sent group multicast address igmpv2 accelerates process leaving group adjusts timeouts leave-group messages sent 224.0.0.2 group-specific query introduced group-specific queries sent group multicast address means routers select igmp querier network introduced igmpv3 introduces source-specific multicast capability membership reports sent 224.0.0.22 several types igmp messages igmp messages carried bare ip packets ip protocol number 2 similar internet control message protocol transport layer used igmp messaging message sent using following ip destination addresses freebsd linux windows operating systems support igmp host side
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Internet protocols
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thunder blade game released standard stand-up arcade cabinet introduced use force feedback joystick vibrates gameplay sit-down unit also available replacing force feedback seat moves tandem joystick versions game later released master system amiga amstrad cpc atari st commodore 64 dos msx turbografx-16 sharp x68000 zx spectrum nintendo 3ds remake released 3d classic japan august 20 2014 north america europe may 14 2015 australia july 2 2015 follow-up super thunder blade released exclusively sega mega drive/genesis game plot setting resembles 1983 film 1984 tv series blue thunder player controls helicopter gunship using chain gun missiles destroy enemy tanks helicopters etc. save home country levels top-down third-person perspective view boss levels top-down view game well received sinclair saying thunder blade probably game took money arcades summer probably one eagerly awaited coin-op conversions game earned golden joystick console award 1988-1989
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Computer architecture
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terranet ab terranet ab company delivers mobile telephony data services via peer-to-peer mobile mesh network handsets light infrastructure headquartered sweden currently led ceo pär-olof johannesson system uses unit within range additional network node allowing voice data transmission via radio frequency rather conventional cell sites terranet concept originally developed way bring mobile coverage under-served geographies populations technology much broader market terranet phone switched begins look phones within effective range finds connects extends radio network actual number dialled handset uses checks see person called within range handsets network call goes detractors questioned terranet lack clear business model though device manufacturers appear interested efforts noted thought leaders voice ip alexander straub truphone identified mesh networks next big thing telecoms terranet ab founded 2004 inventor technology anders carlius serial entrepreneur lund skåne county carlius came background chip manufacturing switchcore also worked web portal operator spray network served first ceo 2010 since inception terranet headquartered lund ideon science park best known home ericsson radio systems carlius says came idea travelling safari east africa wife emma first extensive pilot project carried autumn 2005 farming co-operative botswana trials included agreement indian operator bharat sanchar nigam test 50 handsets late 2012 number pilots south america year development engineer conny said main prerogative miniaturise terranet credit card-sized circuit could installed mobile handset company prestigious red herring magazine award april 2008 carlius received number honours work promoting entrepreneurship sweden including leadership awards 2005 rapidus 2008 jönköping international business school terranet supported private investors july 2013 emerged serial entrepreneur dan olofsson bought 12.5 stake ceo pär-olof johannesson acknowledged oloffson investment means lot company well-known operator heavy industrial background knows industry inside
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Distributed computing architecture
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temporal database temporal database stores data relating time instances offers temporal data types stores information relating past present future time temporal databases could uni-temporal bi-temporal tri-temporal specifically temporal aspects usually include valid time transaction time decision time uni-temporal database one axis time either validity range system time range bi-temporal database two axes time tri-temporal database three axes time approach introduces additional complexities temporal databases contrast current databases confused currently available databases store facts believed true current time temporal databases support managing accessing temporal data providing one following features development sql attendant use real-life applications database users realized added date columns key fields issues arose example table primary key attributes adding date primary key track historical changes lead creation rows intended deletes must also handled differently rows tracked way 1992 issue recognized standard database theory yet resolving issue neither then-newly formalized sql-92 standard richard snodgrass proposed 1992 temporal extensions sql developed temporal database community response proposal committee formed design extensions 1992 edition sql standard ansi x3.135.-1992 iso/iec 9075:1992 extensions known tsql2 developed 1993 committee late 1993 snodgrass presented work group responsible american national standard database language sql ansi technical committee x3h2 known ncits h2 preliminary language specification appeared march 1994 acm sigmod record based responses specification changes made language definitive version tsql2 language specification published september 1994 attempt made incorporate parts tsql2 new sql standard called sql3 parts tsql2 included new substandard sql3 iso/iec 9075-7 called sql/temporal tsql2 approach heavily criticized chris date hugh darwen iso project responsible temporal support canceled near end 2001 december 2011 iso/iec 9075 database language part 2 sql/foundation included clauses table definitions define application-time period tables valid time tables system-versioned tables transaction time tables system-versioned application-time period tables bitemporal tables substantive difference tsql2 proposal adopted sql:2011 hidden columns sql:2011 treatment new data type intervals instead two date timestamp columns bound together using codice_1 declaration another difference replacement controversial prefix statement modifiers tsql2 set temporal predicates features standard related temporal databases automatic time period splitting temporal primary keys temporal referential integrity temporal predicates allen interval algebra time-sliced sequenced queries illustration consider following short biography fictional man john doe store life john doe current non-temporal database use table person name address order simplify name defined primary key person john father officially reported birth april 4 1975 date smallville official inserted following entry database codice_2 note date stored database graduation john moves forgets register new address john entry database changed december 27 1994 finally reports bigtown official updates address database person table contains codice_3 note information john living smallville overwritten longer possible retrieve information database official accessing database december 28 1994 would told john lives bigtown technically database administrator ran query codice_4 december 26 1994 result would codice_5 running query 2 days later would result codice_6 death database would state lived bigtown april 1 2001 coroner deletes john doe entry database running query would return result valid time time fact true real world valid time period may past span current time occur future example record valid time person table two fields added valid-from valid-to specify period person address valid real world april 4 1975 john father registered son birth official inserts new entry database stating john lives smallville april 3 note although data inserted 4th database states information valid since 3rd official yet know john move another place valid-to field set infinity ∞ entry database december 27 1994 john reports new address bigtown living since august 26 1994 new database entry made record fact original entry codice_7 deleted valid-to attribute updated reflect known john stopped living smallville august 26 1994 database contains two entries john doe john dies current entry database updated stating john live bigtown longer database looks like transaction time records time period database entry accepted correct enables queries show state database given time transaction time periods occur past current time transaction time table records never deleted new records inserted existing ones updated setting transaction end time show longer current enable transaction time example two fields added person table transaction-from transaction-to transaction-from time transaction made transaction-to time transaction superseded may infinity yet superseded makes table bitemporal table happens person address stored database incorrect suppose official accidentally entered wrong address date suppose person lied address reason upon discovery error officials update database correct information recorded example 1-jun-1995 3-sep-2000 john doe moved beachy avoid paying beachy exorbitant residence tax never reported authorities later tax investigation discovered 2-feb-2001 fact beachy dates record fact existing entry john living bigtown must split two separate records new record inserted recording residence beachy database would appear follows however leaves record database ever claimed lived bigtown 1-jun-1995 3-sep-2000 might important know auditing reasons use evidence official tax investigation transaction time allows capturing changing knowledge database since entries never directly modified deleted instead entry records entered superseded logically deleted database contents look like database records happened real world also officially recorded different times bitemporal model contains valid transaction time provides historical rollback information historical information e.g john live 1992 provided valid time rollback e.g 1992 database believe john lived provided transaction time answers example questions may database may altered since 1992 causing queries produce different results valid time transaction time single fact example consider temporal database storing data 18th century valid time facts somewhere 1701 1800 transaction time would show facts inserted database example january 21 1998 challenging issue support temporal queries transaction time database evolving schema order achieve perfect archival quality key importance store data schema version first appeared however even simple temporal query rewriting history attribute value would required manually rewritten schema versions potentially hundreds case mediawiki process would particularly taxing users proposed solution provide automatic query rewriting although part sql similar standards approaches minimize complexities schema evolution following implementations provide temporal features relational database management system rdbms non-relational nosql database management systems provide temporal features including following sometimes slowly changing dimension used method
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Databases
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zathura document viewer zathura free plugin-based document viewer plugins available pdf via poppler mupdf postscript djvu epub written lightweight controlled vi-like keybindings zathura customizability makes well-liked many linux users zathura official packages available arch linux debian fedora gentoo openbsd opensuse source mage gnu/linux ubuntu unofficial macos package provided macports zathura named 2005 film development zathura began 12 august 2009 18 september 2009 version 0.0.1 announced arch linux community zathura official arch linux package since april 2010 year end july imported source mage test grimoire official debian package since least 2011 part debian squeeze zathura automatically reloads documents working compiled documents written latex zathura refresh output whenever compilation takes place zathura option enabling inverse search using synctex zathura adjust document best-fit fit width rotate pages view pages side-by-side fullscreen mode pages also recolored black background white foreground zathura search text copy text primary x selection supports bookmarks open encrypted files behavior appearance zathura customized using configuration file zathura ability execute external shell commands opened tabs using
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Programming language topics
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transactional synchronization extensions transactional synchronization extensions tsx-ni extension x86 instruction set architecture isa adds hardware transactional memory support speeding execution multi-threaded software lock elision according different benchmarks tsx provide around 40 faster applications execution specific workloads 4–5 times database transactions per second tps tsx documented intel february 2012 debuted june 2013 selected intel microprocessors based haswell microarchitecture haswell processors 45xx well r-series k-series unlocked multiplier skus support tsx august 2014 intel announced bug tsx implementation current steppings haswell haswell-e haswell-ep early broadwell cpus resulted disabling tsx feature affected cpus via microcode update 2016 side-channel timing attack found abusing way tsx handles transactional faults i.e page faults order break kaslr major operating systems support tsx emulation provided part intel software development emulator also experimental support tsx emulation qemu fork tsx provides two software interfaces designating code regions transactional execution hardware lock elision hle instruction prefix-based interface designed backward compatible processors without tsx support restricted transactional memory rtm new instruction set interface provides greater flexibility programmers tsx enables optimistic execution transactional code regions hardware monitors multiple threads conflicting memory accesses aborting rolling back transactions successfully completed mechanisms provided software detect handle failed transactions words lock elision transactional execution uses memory transactions fast path possible slow fallback path still normal lock hardware lock elision hle adds two new instruction prefixes codice_1 codice_2 two prefixes reuse opcodes existing codice_3 codice_4 prefixes codice_5 codice_6 processors support tsx codice_3 codice_4 prefixes ignored instructions codice_1 codice_2 valid thus enabling backward compatibility codice_1 prefix hint used following instructions explicit codice_12 prefix codice_13 codice_14 codice_15 codice_16 codice_17 codice_18 codice_19 codice_20 codice_21 codice_22 codice_23 codice_24 codice_25 codice_26 codice_27 codice_28 codice_29 codice_30 codice_30 instruction used without codice_12 prefix well codice_2 prefix hint used instructions listed codice_34 codice_35 instructions hle allows optimistic execution critical section eliding write lock lock appears free threads failed transaction results execution restarting codice_1-prefixed instruction treating instruction codice_1 prefix present restricted transactional memory rtm alternative implementation hle gives programmer flexibility specify fallback code path executed transaction successfully executed rtm adds three new instructions codice_38 codice_39 codice_40 codice_38 codice_39 instructions mark start end transactional code region codice_40 instruction explicitly aborts transaction transaction failure redirects processor fallback code path specified codice_38 instruction abort status returned codice_45 register tsx provides new codice_46 instruction returns whether processor executing transactional region intel tsx specification describes transactional memory exposed programmers withholds details actual transactional memory implementation intel specifies developer optimization manuals haswell maintains read-sets write-sets granularity cache line tracking addresses l1 data cache processor intel also states data conflicts detected cache coherence protocol haswell l1 data cache associativity eight means implementation transactional execution writes nine distinct locations mapping cache set abort however due micro-architectural implementations mean fewer accesses set guaranteed never abort additionally cpu configurations hyper-threading technology l1 cache shared two threads core operations sibling logical processor core cause evictions independent research points haswell ’ transactional memory likely deferred update system using per-core caches transactional data register checkpoints words haswell likely use cache-based transactional memory system much less risky implementation choice hand intel skylake later may combine cache-based approach memory ordering buffer mob purpose possibly also providing multi-versioned transactional memory amenable speculative multithreading august 2014 intel announced bug exists tsx implementation haswell haswell-e haswell-ep early broadwell cpus resulted disabling tsx feature affected cpus via microcode update bug fixed f-0 steppings vpro-enabled core m-5y70 broadwell cpu november 2014 bug found reported diploma thesis school electrical computer engineering national technical university athens
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Computer architecture
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novabackup novabackup developed novastor data protection software enables smb users backup recover mission critical data across hybrid physical virtual machines novabackup designed work microsoft windows operating systems offering local online file backups disaster recovery image backups novabackup uses proprietary file format uses .nbd file extension backwards compatible meaning backups older versions novabackup version 8 restored latest version software version 7 8 backups still restored file extensions need updated .nbd multiple novabackup editions available versions built smb users support backups pcs laptops servers including support exchange/sql virtual machines novabackup software includes novacare premium support email/phone-in technical support maintenance upgrades novastor partnered buffalo offering novabackup software included linkstation family consumer nas solutions terastation family business-class nas solutions release change log novabackup starting version 13.0 current novabackup release log
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Computer security
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intel turbo boost intel turbo boost intel trade name feature automatically raises certain processors operating frequency thus performance demanding tasks running turbo-boost-enabled processors core i5 core i7 core i9 xeon series manufactured since 2008 particularly based nehalem sandy bridge later microarchitectures frequency accelerated operating system requests highest performance state processor processor performance states defined advanced configuration power interface acpi specification open standard supported major operating systems additional software drivers required support technology design concept behind turbo boost commonly referred dynamic overclocking workload processor calls faster performance processor clock try increase operating frequency regular increments required meet demand increased clock rate limited processor power current thermal limits number cores currently use maximum frequency active cores frequency increases occur increments 133 mhz nehalem processors 100 mhz sandy bridge ivy bridge haswell skylake processors electrical thermal limits exceeded operating frequency automatically decreases decrements 133 100 mhz processor operating within design limits turbo boost 2.0 introduced 2011 sandy bridge microarchitecture intel turbo boost max 3.0 introduced 2016 broadwell-e microarchitecture intel november 2008 white paper discusses turbo boost technology new feature incorporated nehalem-based processors released month similar feature called intel dynamic acceleration ida available many core 2 based centrino platforms feature receive marketing treatment given turbo boost intel dynamic acceleration dynamically changed core frequency function number active cores operating system instructed one active cores enter c3 sleep state using advanced configuration power interface acpi active core dynamically accelerated higher frequency intel turbo boost technology monitor gui utility could used monitor turbo boost utility reached end-of-life state longer supporting intel processors released q2 2013 longer available
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Computer architecture
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avr32 avr32 32-bit risc microcontroller architecture produced atmel microcontroller architecture designed handful people educated norwegian university science technology including lead designer øyvind strøm cpu architect erik renno atmel norwegian design center instructions executed single-cycle multiply–accumulate unit perform 32-bit × 16-bit 48-bit arithmetic operation two cycles result latency issued per cycle resemble 8-bit avr microcontroller family even though designed atmel norway trondheim debug-tools similar support avr32 dropped linux kernel 4.12 atmel switched mostly variants arm architecture avr32 least two micro-architectures avr32a avr32b differ instruction set architecture register configurations use caches instructions data avr32a cpu cores inexpensive applications provide dedicated hardware registers shadowing register file status return address interrupts saves chip area expense slower interrupt-handling avr32b cpu cores designed fast interrupts dedicated registers hold values interrupts exceptions supervisor calls avr32b cores also support java virtual machine hardware avr32 instruction set 16-bit compact 32-bit extended instructions similar e.g arm several specialized instructions found older armv5 armv6 mips32 several u.s. patents filed avr32 isa design platform like avr 8-bit microcontroller architecture avr32 designed high code density packing much function instructions fast instructions clock cycles atmel used independent benchmark consortium eembc benchmark architecture various compilers consistently outperformed armv5 16-bit thumb code armv5 32-bit arm code much 50 code-size 3× performance atmel says picopower avr32 at32uc3l consumes less 0.48 mw/mhz active mode claimed time used less power 32-bit cpu march 2015 claim new cortex-m0+-based microcontrollers using arm holdings arm architecture instruction set broken ultra-low power performance barriers date avr32 architecture used atmel products 2006 atmel launched avr32a avr32 ap7 core 7-stage pipelined cache-based design platform ap7000 implements avr32b architecture supports simd single instruction multiple data dsp digital signal processing instructions risc instruction-set addition java hardware acceleration includes memory management unit mmu supports operating systems like linux early 2009 rumored ap7200 follow-on processor held back resources going chips 2007 atmel launched second avr32 avr32 uc3 core designed microcontrollers using on-chip flash memory program storage running without mmu memory management unit avr32 uc3 core uses three-stage pipelined harvard architecture specially designed optimize instruction fetches on-chip flash memory avr32 uc3 core implements avr32a architecture shares instruction set architecture isa ap7 sibling differs including optional simd instructions java support shares 220 instructions avr32b isa features atomic bit manipulation control on-chip peripherals general purpose i/os fixed point dsp arithmetic implementations combined compatible set peripheral controllers buses first seen at91sam arm-based platforms peripherals first seen ap7000 high speed usb peripheral controller standalone dma controller appeared later updated arm9 platforms arm cortex-m3 based products avr32 cores include nexus class 2+ based on-chip debug framework build jtag uc3 core announced electronica 2010 munich germany november 10 2010 first 32-bit avr microcontroller optional floating-point unit april 10 2012 atmel announced end life ap7 core devices april 4 2013 devicename ends *au audio version allow execution atmel licensed audio firmware ips devicename ends *s includes aes crypto module series low-power uc3d embeds sleepwalking technology allows peripheral wake device sleep mode
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Computer architecture
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robert mercer robert leroy mercer born july 11 1946 american computer scientist developer early artificial intelligence co-ceo renaissance technologies hedge fund mercer played key role brexit campaign donating data analytics services nigel farage also major funder organizations supporting right-wing political causes united states breitbart news donald trump 2016 campaign president principal benefactor make america number 1 super pac november 2017 mercer announced would step renaissance technologies sell stake breitbart news daughters mercer grew new mexico developed early interest computers 1964 attended national youth science camp west virginia learned program donated ibm computer went get bachelor degree physics mathematics university new mexico working degree job air force weapons laboratory kirtland air force base writing programs though felt produced good work felt optimized later said experience left jaundiced view government-funded research earned ph.d. computer science university illinois urbana–champaign 1972 mercer joined ibm research fall 1972 worked thomas j. watson research center yorktown new york helped develop brown clustering statistical machine translation technique part speech recognition translation research program led frederick jelinek lalit bahl june 2014 mercer received association computational linguistics lifetime achievement award work 1993 mercer joined hedge fund renaissance technologies recruited executive nick patterson founder renaissance james harris simons quantitative analyst preferred hire mathematicians computer scientists physicists rather business school students financial analysts mercer former colleague ibm peter brown became co-ceos renaissance simons retired 2009 renaissance main fund medallion earned 39 per year average 1989 2006 bipartisan senate panel estimated 2014 medallion investors underpaid taxes 6.8 billion decade masking short-term gains long-term returns 2014 renaissance managed 25 billion assets november 2017 mercer announced would stepping position renaissance technologies decision taken hedge fund faced backlash mercer political activism mercer appears director eight bermuda companies paradise papers appear used legally avoid us taxes 2015 washington post called mercer one ten influential billionaires politics since 2006 mercer donated 34.9 million republican political campaigns us mercer given 750,000 club growth 2 million american crossroads 2.5 million freedom partners action fund 2010 financially supported fringe biochemist art robinson unsuccessful efforts unseat peter defazio oregon 4th congressional district 2013-2014 election cycle mercer donated fourth largest amount money among individual donors second among republican donors mercer joined koch brothers ’ conservative political donor network 2010 citizens united v. fec mercer daughter rebekah mercer decided establish political foundation mercer family foundation run rebekah donated variety conservative causes mercer donated heritage foundation cato institute media research center reclaim new york gai 2013 mercer shown data former jimmy carter pollster patrick caddell critical top democrats commissioned research caddell showed voters becoming alienated political parties mainstream candidates mercer main financial backer jackson hole summit conference took place wyoming august 2015 advocate gold standard also supported doctors disaster preparedness fred kelly grant idaho activist encourages legal challenges environmental laws campaign death penalty nebraska funded ads new york critical so-called ground-zero mosque according associates interviewed bloomberg mercer concerned monetary banking systems united states believes danger government meddling mercer major source funds breitbart news gave least 10 million media outlet according newsweek 2015 mercer also gave 400,000 black americans better future conservative think tank led raynard jackson since 2017 mercer donated 87,100 super pac mercer activist campaign united kingdom end membership european union also known brexit andy wigmore communications director leave.eu said mercer donated services data analytics firm cambridge analytica nigel farage head united kingdom independence party ukip firm able advise leave.eu ability harvest data people facebook profiles order target individualized persuasive messages vote brexit reported cambridge analytica also undisclosed links canadian digital firm aggregateiq also played pivotal role domenic cummings voteleave campaign delivered estimated one billion individually curated targeted adverts voters lead brexit referendum contravention established voting rules voteleave leave.eu inform uk electoral commission donation despite fact law demands donations valued £7,500 must reported 2018 electoral commission found voteleave campaign guilty breaking electoral law january 2016 mercer biggest single donor 2016 u.s. presidential race june 2016 ranked 1 donor federal candidates 2016 election cycle donated 2 million john r. bolton super pac 668,000 republican national committee mercer major financial supporter 2016 presidential campaign ted cruz contributing 11 million super pac associated candidate mercer major supporter donald trump 2016 campaign president mercer daughter rebekah helped get steve bannon kellyanne conway senior roles trump campaign rebekah worked conway cruz super-pac keep promise 2016 republican primaries mercer also financed super pac make america number one supported trump campaign nick patterson former colleague mercer said 2017 trump would elected without mercer support mercer said civil rights act 1964 landmark federal statute arising civil rights movement 1960s major mistake 2017 david magerman former renaissance employee alleged lawsuit mercer said african americans economically better civil rights movement white racists longer existed united states racists remaining black racists mercer portrayed actor aden gillett 2019 hbo channel 4 produced drama entitled mercer wife diana lynne dean three daughters jennifer jenji rebekah bekah heather sue rebekah runs mercer family foundation three mercer daughters formerly owned bakery called ruby et violette mercer plays competitive poker owns ho scale model railroad 2009 mercer filed suit raildreams custom model railroad design alleging raildreams overcharged 2 million mercer lives owl nest mansion head harbor new york commissioned series yachts named sea owl recent one 203 feet 62 metres length pirate-themed playroom mercer grandchildren chandelier venetian glass florida mercer built large stable horse riding center acquired one country largest collections machine guns historical firearms including weapon arnold schwarzenegger wielded terminator 2013 mercer sued several members household staff accused docking wages failing pay overtime compensation lawsuit settled according lawyer represented staff members mercer net worth estimated hundreds millions dollars often referred billionaire
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Computational linguistics
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apl programming language apl named book programming language programming language developed 1960s kenneth e. iverson central datatype multidimensional array uses large range special graphic symbols represent functions operators leading concise code important influence development concept modeling spreadsheets functional programming computer math packages also inspired several programming languages mathematical notation manipulating arrays developed kenneth e. iverson starting 1957 harvard university 1960 began work ibm developed notation adin falkoff published book programming language 1962 preface states premise notation used inside ibm short research reports computer systems burroughs b5000 stack mechanism stack machines versus register machines evaluated ibm upcoming computers iverson also used notation draft chapter programming language written book writing fred brooks automatic data processing would published 1963 1979 iverson received turing award work apl early 1962 first attempt use notation describe complete computer system happened falkoff discussed william c. carter work standardize instruction set machines later became ibm system/360 family 1963 herbert hellerman working ibm systems research institute implemented part notation ibm 1620 computer used students special high school course calculating transcendental functions series summation students tested code hellerman lab implementation part notation called personalized array translator pat 1963 falkoff iverson edward h. sussenguth jr. working ibm used notation formal description ibm system/360 series machine architecture functionality resulted paper published ibm systems journal 1964 published team turned attention implementation notation computer system one motivations focus implementation interest john l. lawrence new duties science research associates educational company bought ibm 1964 lawrence asked iverson group help use language tool develop use computers education lawrence m. breed philip s. abrams stanford university joined team ibm research continued prior work implementation programmed fortran iv part notation done ibm 7090 computer running ibsys operating system work finished late 1965 later named ivsys iverson system basis implementation described detail abrams stanford university technical report interpreter iverson notation 1966 academic aspect formally supervised niklaus wirth like hellerman pat system earlier implementation include apl character set used special english reserved words functions operators system later adapted time-sharing system november 1966 reprogrammed ibm system/360 model 50 computer running time sharing mode used internally ibm key development ability use apl effectively wide use cathode ray tube crt terminals development special ibm selectric typewriter interchangeable typing element special apl characters used paper printing terminal workstations using selectric typewriter typing element mechanism ibm 1050 ibm 2741 terminal keycaps could placed normal keys show apl characters would entered typed key struck first time programmer could type see proper apl characters used iverson notation forced use awkward english keyword representations falkoff iverson special apl selectric typing elements 987 988 designed late 1964 although apl computer system available use iverson cited falkoff inspiration idea using ibm selectric typing element apl character set many apl symbols even apl characters selectric typing element still typed over-striking two extant element characters example grade character made delta shift-h sheffer stroke shift-m necessary apl character set much larger 88 characters allowed typing element even letters restricted upper-case capitals first apl interactive login creation apl workspace 1966 larry breed using ibm 1050 terminal ibm mohansic labs near thomas j. watson research center home apl yorktown heights new york ibm chiefly responsible introducing apl marketplace apl first available 1967 ibm 1130 apl\1130 would run little 8k 16-bit words memory used dedicated 1 megabyte hard disk apl gained foothold mainframe timesharing systems late 1960s early 1980s part would support multiple users lower-specification systems dynamic address translation hardware additional improvements performance selected ibm system/370 mainframe systems included apl assist microcode support apl execution included processor firmware distinct implemented entirely higher-level software somewhat later suitably performing hardware finally growing available mid- late-1980s many users migrated applications personal computer environment early ibm apl interpreters ibm 360 ibm 370 hardware implemented multi-user management instead relying host services thus timesharing systems first introduced 1966 apl\360 system multi-user interpreter ability programmatically communicate operating system information setting interpreter system variables done special privileged i-beam functions using monadic dyadic operations 1973 ibm released apl.sv continuation product offered shared variables means access facilities outside apl system operating system files mid-1970s ibm mainframe interpreter even adapted use ibm 5100 desktop computer small crt apl keyboard small computers time offered basic 1980s vsapl program product enjoyed wide use conversational monitor system cms time sharing option tso vspc music/sp cics users 1973-1974 patrick e. hagerty directed implementation university maryland apl interpreter 1100 line sperry univac 1100/2200 series mainframe computers time sperry nothing 1974 student alan stebbens assigned task implementing internal function 1960s 1970s several timesharing firms arose sold apl services using modified versions ibm apl\360 interpreter north america better-known ones i. p. sharp associates scientific time sharing corporation stsc time sharing resources tsr computer company tcc compuserve also entered market 1978 apl interpreter based modified version digital equipment corp carnegie mellon ran dec ki kl 36-bit machines compuserve apl available commercial market consumer information service advent first less expensive mainframes ibm 4300 later personal computer mid-1980s timesharing industry gone sharp apl available i. p. sharp associates first timesharing service 1960s later program product starting around 1979 sharp apl advanced apl implementation many language extensions packages ability put one objects single variable file system nested arrays shared variables apl interpreters available mainframe mini-computer manufacturers also notably burroughs control data corporation cdc data general digital equipment corporation dec harris hewlett-packard hp siemens ag xerox others garth foster syracuse university sponsored regular meetings apl implementers community syracuse minnowbrook conference center blue mountain lake new york later years eugene mcdonnell organized similar meetings asilomar conference grounds near monterey california pajaro dunes near watsonville california sigapl special interest group association computing machinery continues support apl community microcomputers became available mid 1970s onwards basic became dominant programming language nevertheless microcomputers provided apl instead first intel 8008-based mcm/70 released 1974 primarily used education another machine time videobrain family computer released 1977 supplied dialect apl called apl/s commodore superpet introduced 1981 included apl interpreter developed university waterloo 1976 bill gates claimed open letter hobbyists microsoft corporation implementing apl intel 8080 motorola 6800 little incentive make available hobbyists software piracy never released starting early 1980s ibm apl development leadership jim brown implemented new version apl language contained primary enhancement concept nested arrays array contain arrays new language features facilitated integrating nested arrays program workflow ken iverson longer control development apl language left ibm joined i. p. sharp associates one major contributions directing evolution sharp apl accord vision vendors busy developing apl interpreters new hardware notably unix-based microcomputers apl2 almost always standard chosen new apl interpreter developments even today apl vendors users cite apl2 compatibility selling point products apl2 ibm mainframe computers still available ibm cites use problem solving system design prototyping engineering scientific computations expert systems teaching mathematics subjects visualization database access first available cms tso 1984 apl2 workstation edition windows os/2 aix linux solaris followed much later early 1990s various implementations apl aplx dyalog et al. include extensions object-oriented programming support .net framework xml-array conversion primitives graphing operating system interfaces lambda calculus expressions apl formed basis influenced following languages apl criticized praised choice unique non-standard character set learn become ardent adherents suggesting weight behind iverson idea notation used make difference 1960s 1970s terminal devices even display monitors could reproduce apl character set popular ones employed ibm selectric print mechanism used special apl type element one early apl line terminals line-mode operation full screen texas instruments ti model 745 circa 1977 full apl character set featured half full duplex telecommunications modes interacting apl time-sharing service remote mainframe run remote computer job called rje time universal use high-quality graphic displays printing devices unicode support apl character font problem largely eliminated however entering apl characters requires use input method editors keyboard mappings virtual/on-screen apl symbol sets easy-reference printed keyboard cards frustrate beginners accustomed programming languages beginners prior experience programming languages study involving high school students found typing using apl characters hinder students measurable way defense apl use apl requires less coding type keyboard mappings become memorized time also special apl keyboards manufactured use today freely available downloadable fonts operating systems microsoft windows reported productivity gains assume one spend enough time working apl make worthwhile memorize symbols semantics keyboard mappings mention substantial number idioms common tasks unlike traditionally structured programming languages apl code typically structured chains monadic dyadic functions operators acting arrays apl many nonstandard primitives functions operators indicated single symbol combination symbols primitives defined precedence always associate right thus apl read best understood right-to-left early apl implementations circa 1970 programming loop-flow control structures codice_1 codice_2 loops codice_3 constructs instead used array operations use structured programming constructs often necessary since operation could performed full array one statement example codice_4 function codice_5 replace for-loop iteration ιn applied scalar positive integer yields one-dimensional array vector 1 2 3 ... n. recent implementations apl generally include comprehensive control structures data structure program control flow clearly cleanly separated apl environment called workspace workspace user define programs data i.e. data values exist also outside programs user also manipulate data without define program examples apl interpreter first types six spaces awaiting user input output starts column one user save workspace values programs execution status apl uses set non-ascii symbols extension traditional arithmetic algebraic notation single character names single instruction multiple data simd vector functions one way apl enables compact formulation algorithms data transformation computing conway game life one line code nearly versions apl theoretically possible express computable function one expression one line code unusual character set many programmers use special keyboards apl keytops write apl code although various ways write apl code using ascii characters practice almost never done may thought support iverson thesis notation tool thought modern implementations use standard keyboard layouts special mappings input method editors access non-ascii characters historically apl font distinctive uppercase italic alphabetic characters upright numerals symbols vendors continue display apl character set custom font advocates apl claim examples so-called write-only code badly written almost incomprehensible code almost invariably examples poor programming practice novice mistakes occur language advocates also claim far productive apl conventional computer languages working software implemented far less time far fewer programmers using technology also may claim compact terse apl lends well larger-scale software development complexity number lines code reduced greatly many apl advocates practitioners also view standard programming languages cobol java comparatively tedious apl often found time-to-market important trading systems apl makes clear distinction functions operators functions take arrays variables constants expressions arguments return arrays results operators similar higher-order functions take functions arrays arguments derive related functions example sum function derived applying reduction operator addition function applying reduction operator maximum function returns larger two numbers derives function returns largest group vector numbers j language iverson substituted terms verb function adverb conjunction operator apl also identifies features built language represented symbol fixed combination symbols primitives primitives either functions operators coding apl largely process writing non-primitive functions versions apl operators however primitives considered neither functions operators noticeably assignment words used apl literature meanings differ mathematics generality computer science apl explicit representations functions operators syntax thus providing basis clear explicit statement extended facilities language tools experiment displays hello world 'hello world sample user session youtube design theme apl define default actions cases would produce syntax errors programming languages 'hello world string constant displays display default action expression action specified explicitly e.g assignment function parameter another example theme exponentiation apl written indicates raising 2 power 3 would written languages fortran python many languages use signify multiplication 2*3 apl uses however base specified statement apl languages programming languages one would syntax error apl however assumes missing base natural logarithm constant e 2.71828 ... interpreting suppose array numbers gives average reading right-to-left gives number elements x since dyadic operator term left required well parenthesis since otherwise x would taken summation would element x divided number elements x adds elements x building calculates standard deviation since assignment operator appear within expression would place suitable values av sd naturally one would make expression function repeated use rather retyping time following immediate-mode expression generates typical set pick 6 lottery numbers six pseudo-random integers ranging 1 40 guaranteed non-repeating displays sorted ascending order lot concisely although seems complex new apler combines following apl functions also called primitives glyphs since function left left-most x tell apl result simply outputs display single line separated spaces without needing explicit instruction codice_6 also monadic equivalent called codice_15 simply returns one random integer 1 sole operand right inclusive thus role-playing game program might use expression codice_16 roll twenty-sided die following expression finds prime numbers 1 r. time space calculation complexity formula_1 big notation executed right left means note assumes apl origin 1 i.e. indices start 1 apl set use 0 origin codice_45 codice_46 convenient calculations following expression sorts word list stored matrix x according word length following function life written dyalog apl takes boolean matrix calculates new generation according conway game life demonstrates power apl implement complex algorithm little code also hard follow unless one advanced knowledge apl following example also dyalog first line assigns html code variable codice_47 uses apl expression remove html tags explanation apl used many purposes including financial insurance applications artificial intelligence neural networks robotics argued apl calculation tool programming language symbolic nature array capabilities made popular domain experts data scientists require skills computer programmer apl well suited image manipulation computer animation graphic transformations encoded matrix multiplications one first commercial computer graphics houses digital effects produced apl graphics product named visions used create television commercials animation 1982 film tron latterly stormwind boating simulator uses apl implement core logic interfacing rendering pipeline middleware major part physics engine today apl remains use wide range commercial scientific applications example investment management asset management health care dna profiling hobbyists first implementation apl using recognizable apl symbols apl\360 ran ibm system/360 completed november 1966 though time remained use within ibm 1973 implementors larry breed dick lathwell roger moore awarded grace murray hopper award association computing machinery acm given work design implementation apl\360 setting new standards simplicity efficiency reliability response time interactive systems 1975 ibm 5100 microcomputer offered apl\360 one two built-in rom-based interpreted languages computer complete keyboard display supported special symbols used language significant developments apl\360 included cms/apl made use virtual storage capabilities cms aplsv introduced shared variables system variables system functions subsequently ported ibm system/370 vspc platforms final release 1983 replaced apl2 1968 apl\1130 became first publicly available apl system created ibm ibm 1130 became popular ibm type-iii library software ibm released apl*plus sharp apl versions apl\360 added business-oriented extensions data formatting facilities store apl arrays external files jointly developed two companies employing various members original ibm apl\360 development team two companies i. p. sharp associates ipsa apl\360 services company formed 1964 ian sharp roger moore others stsc time-sharing consulting service company formed 1969 lawrence breed others together two developed apl*plus thereafter continued work together develop apl separately apl*plus sharp apl stsc ported apl*plus many platforms versions made vax 11 pc unix whereas ipsa took different approach arrival personal computer made sharp apl available platform using additional pc-xt/360 hardware 1993 soliton incorporated formed support sharp apl developed sharp apl sax sharp apl unix apl*plus continues apl2000 apl+win 1985 ian sharp dan dyer stsc jointly received kenneth e. iverson award outstanding contribution apl apl2 significant re-implementation apl ibm developed 1971 first released 1984 provides many additions language notable nested non-rectangular array support available mainframe computers running z/os z/vm workstations running aix linux sun solaris microsoft windows entire apl2 products services team awarded iverson award 2007 dyalog apl first released british company dyalog ltd. 1983 available aix linux including raspberry pi macos microsoft windows platforms based apl2 extensions support object-oriented programming functional programming licences free personal/non-commercial use 1995 two development team john scholes peter donnelly awarded iverson award work interpreter gitte christensen morten kromberg joint recipients iverson award 2016 nars2000 open-source apl interpreter written bob smith prominent apl developer implementor stsc 1970s 1980s nars2000 contains advanced features new datatypes runs natively microsoft windows platforms wine aplx cross-platform dialect apl based apl2 several extensions first released british company microapl 2002 although longer development commercial sale available free charge dyalog gnu apl free implementation extended apl specified iso/iec 13751:2001 thus similar apl2 runs gnu/linux windows using cygwin uses unicode internally written jürgen sauermann richard stallman founder gnu project early adopter apl using write text editor high school student summer 1969 apl traditionally interpreted language language characteristics weak variable typing well suited compilation however arrays core data structure provides opportunities performance gains parallelism parallel computing massively parallel applications very-large-scale integration vlsi outset apl regarded high-performance language example noted speed could perform complicated matrix operations operates arrays performs operations like matrix inversion internally nevertheless apl rarely purely interpreted compilation partial compilation techniques used include following apl interpreters support idiom recognition evaluate common idioms single operations example evaluating idiom codice_48 single operation codice_49 boolean vector codice_50 array creation two intermediate arrays avoided weak typing apl means name may reference array datatype function operator general interpreter know advance form must therefore perform analysis syntax checking etc run-time however certain circumstances possible deduce advance type name expected reference generate bytecode executed reduced run-time overhead bytecode also optimised using compilation techniques constant folding common subexpression elimination interpreter execute bytecode present assumptions made met dyalog apl includes support optimised bytecode compilation apl subject research experiment since language first became available first compiler considered burroughs apl-700 released around 1971 order able compile apl language limitations imposed apex research apl compiler written robert bernecky available gnu public license stsc apl compiler hybrid bytecode optimiser compiler enables compilation functions machine code provided sub-functions globals declared interpreter still used runtime library execute functions meet compilation requirements apl standardized american national standards institute ansi working group x3j10 international organization standardization iso international electrotechnical commission iec iso/iec joint technical committee 1 subcommittee 22 working group 3 core apl language specified iso 8485:1989 extended apl language specified iso/iec 13751:2001
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Operating systems
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sqsh sqsh pronounced skwish short sqshell pronounced s-q-shell open-source substitute isql interactive sql client supplied sybase adaptive server enterprise ase relational database management system isql sqsh essentially rudimentary command-line tools issuing transact-sql commands ase server receiving displaying results sqsh supports among others command history aliases piping output external programs sources runs various flavours unix including linux well windows cygwin libraries
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Databases
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line discipline line discipline ldisc layer terminal subsystem unix-like systems terminal subsystem consists three layers upper layer provide character device interface lower hardware driver communicate hardware pseudo terminal middle line discipline implement behavior common terminal devices line discipline glues low level device driver code high level generic interface routines read 2 write 2 ioctl 2 responsible implementing semantics associated device policy separated device driver serial hardware driver used devices require different data handling example standard line discipline processes data receives hardware driver applications writing device according requirements terminal unix-like system input handles special characters interrupt character typically control-c erase kill characters typically backspace delete control-u respectively output replaces lf characters cr/lf sequence serial port could also used dial-up internet connection using serial modem ppp case ppp line discipline would used would accumulate input data serial line ppp input packets delivering networking stack rather character device would transmit packets delivered networking stack serial line unix-like systems use streams implement line disciplines
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Operating systems
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multilingual notation multilingual notation representation lexical resource allows translation two words instance within lmf multilingual notation could presented following diagram english french translation diagram two intermediate senseaxis instances used order represent near match fleuve french river english senseaxis instance bottom linked directly english sense notion exist english complex situation two languages concerned following diagram dealing english italian spanish within context multilingual database comprising two languages usually multilingual notations factorized order save number links terms multilingual notations interlingual nodes shared among language descriptions specific context lexical resource bilingual lexicon term bilingual link usually preferred let us note instead translation rather broad meaning authors prefer equivalence words different notions like dynamic formal equivalences term mainly used context machine translation nlp lexicons term used context translation dictionary concerns mainly hand-held electronic translators
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Computational linguistics
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elbrus-2s+ elbrus-2s+ multi-core microprocessor based elbrus 2000 architecture developed moscow center sparc technologies mcst multiple reports regarding evolution technology purpose import substitution russia raised several ministries july 2014 due economic sanctions response 2014 pro-russian unrest ukraine december 2014 announced mikron start pilot production dual-core variant microprocessor called elbrus-2sm using 90 nanometer cmos manufacturing process zelenograd russia elbrus-4s cpu reported built support intel x86 emulation well native vliw mode perform 23 instructions per clock cycle programs built elbrus 2000 native mode compiler determines different operations shall distributed 23 computing units saving final program means dynamic scheduling needed runtime thus reducing amount work cpu perform every time program executed static scheduling needs performed one time program built advanced algorithms finding optimal distribution work employed south bridge elbrus 2000 chipset connects peripherals bus cpu developed mcst also compatible mcst-r1000 december 2012 kraftway announced deliver elbrus based pc together partner mcst august 2013 kuyan gusev kozlov kaimuldenov kravtsunov mcst published article based experience building deployment debian linux elbrus computer architecture done using hybrid compiler toolchain cross native elbrus-2s+ intel core 2 duo december 2014 implementation opengl 3.3 standard demonstrated running game doom 3 bfg edition elbrus-4s clocked 720 mhz using radeon graphics card 2 gigabytes video memory april 2015 mcst announced two new products based elbrus-4s cpu one 19-inch rack server four cpus 16 cores one personal computer december 2015 first shipment pcs based vliw cpu elbrus-4s made russia
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Computer architecture
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nomadik nomadik family microprocessors multimedia applications stmicroelectronics based arm9 arm architecture designed specifically mobile devices december 12 2002 stmicroelectronics texas instruments jointly announced initiative open mobile application processor interfaces omapi intended used 2.5 3g mobile phones going produced 2003 later merged larger initiative renamed mipi alliance nomadik stmicroelectronics implementation standard nomadik first presented october 7 2003 ceatec show tokyo later year nomadik microprocessor report analysts choice award application processors family aimed 2.5g/3g mobile phones personal digital assistants portable wireless products multimedia capability addition suitable automotive multimedia applications known device using nomadik processor nokia n96 used stn8815 version chip n96 debuted 2008 absence gpu noticed derivative nomadik created specifically navigation systems gps named cartesio sta2062 used products garmin nüvi 205 nüvi 500 derivative used arm926ej-s coupled sta5620 gps rf downconverter added 32-channel hardware gps correlator nomadik family discontinued 2009 development already begun successor soc called stn8500 superseded novathor family st-ericsson renamed u8500 st-nxp wireless division merged st-ericsson joint venture
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Computer architecture
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chipset computer system chipset set electronic components integrated circuit known data flow management system manages data flow processor memory peripherals usually found motherboard chipsets usually designed work specific family microprocessors controls communications processor external devices chipset plays crucial role determining system performance computing term chipset commonly refers set specialized chips computer motherboard expansion card personal computers first chipset ibm pc 1984 neat chipset developed chips technologies intel 80286 cpu home computers game consoles arcade-game hardware 1980s 1990s term chipset used custom audio graphics chips examples include commodore amiga original chip set sega system 16 chipset term chipset often refers specific pair chips motherboard northbridge southbridge northbridge links cpu high-speed devices especially ram graphics controllers southbridge connects lower-speed peripheral buses pci isa many modern chipsets southbridge contains on-chip integrated peripherals ethernet usb audio devices motherboards chipsets often come different manufacturers manufacturers chipsets x86 motherboards include amd broadcom intel nvidia sis via technologies apple computers unix workstations traditionally used custom-designed chipsets server manufacturers also develop custom chipsets products 1980s chips technologies pioneered manufacturing chipsets pc-compatible computers computer systems produced since often share commonly used chipsets even across widely disparate computing specialties example ncr 53c9x low-cost chipset implementing scsi interface storage devices could found unix machines mips magnum embedded devices personal computers traditionally x86 computers processor primary connection rest machine motherboard chipset northbridge northbridge directly responsible communications high-speed devices system memory primary expansion buses pcie agp pci cards common examples conversely system communication back processor connection processor northbridge commonly designated front side bus fsb requests resources directly controlled northbridge offloaded southbridge northbridge intermediary processor southbridge southbridge handled everything else generally lower-speed peripherals board functions largest hard disk storage connectivity usb parallel serial communications connection northbridge southbridge normally pci bus 2003 interaction cpu main memory expansion device graphics card — whether agp pci integrated motherboard — directly controlled northbridge ic behalf processor made processor performance highly dependent system chipset especially northbridge memory performance ability shuttle information back processor 2003 however amd introduction athlon 64-bit series processors changed athlon64 marked introduction integrated memory controller incorporated processor thus allowing processor directly access handle memory negating need traditional northbridge intel followed suit 2008 release core series cpus x58 platform newer processors integration increased primarily inclusion system primary pcie controller integrated graphics directly cpu fewer functions left un-handled processor chipset vendors condensed remaining northbridge southbridge functions single chip intel version platform controller hub pch effectively enhanced southbridge remaining peripherals—as traditional northbridge duties memory controller expansion bus pcie interface even on-board video controller integrated cpu die chipset often contains secondary pcie connections though however platform controller hub also integrated processor package second die mobile variants skylake processors
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Computer architecture
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crunchfish crunchfish swedish technology company malmö develops gesture recognition software mobile phone tablet market crunchfish founded 2010 initial focus create innovations ios android app markets gesture recognition using standard webcam main gesture sensor one core innovations company focusing touchless interaction based camera based gestures 2013 april company selected '2013 red herring top 100 company red herring magazine crunchfish produces gesture sensing software set customized mid-air gesture recognition solutions named a3d™ global mobile device manufacturers app developers crunchfish cooperates smartphone manufacturers enable crunchfish gesture sensing technology partners mobile devices crunchfish developed touchless functions chinese gionee smartphone elife e6 launched china july 2013 india africa august 2013 crunchfish integrates touchless functions e.g smartphones technology portable mobile platform devices gesture recognition technology used mobile phones tablets dtvs equipped front-facing camera typical uses crunchfish touchless technology devices intelligent home smartphones tablets digital tv games home electronics built-in standard camera gesture based functionality adds alternative options standard touch interface user example put tablet front him/her free mid-air gesture hands interacting media player without touching smartphone users answer reject phone calls start slideshows photo gallery use video scrubber etc without touching device device pause video playback users look away screen crunchfish touchless a3d software able detect track objects fingers hand gestures face movements three dimensions based video stream embedded standard camera e.g mobile device
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Distributed computing architecture
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challenge–response spam filtering challenge–response c/r system type spam filter automatically sends reply challenge alleged sender incoming e-mail originally designed 1997 stan weatherby called email verification reply sender asked perform action assure delivery original message would otherwise delivered action perform typically takes relatively little effort great effort perform large numbers effectively filters spammers challenge–response systems need send challenges unknown senders senders previously performed challenging action previously sent e-mail would automatically whitelisted c/r systems attempt provide challenges fulfilled easily legitimate senders non-easily spammers two characteristics differ legitimate senders spammers exploited achieve goal listed examples challenges could used exploit differences nowadays c/r systems used widely enough make spammers bother automatically respond challenges therefore c/r systems generally rely simple challenge would made complicated spammers ever build automated responders c/r systems ideally problems sending challenges forged email addresses reduced challenges sent critics c/r systems raised several issues regarding usefulness email defense number issues relate programs auto-respond e-mail including mailing list managers vacation programs bounce messages mail servers spammers use fake non-existent address sender address field e-mail header also use forged existing sender address valid arbitrary person address without person consent latter would become increasingly common e.g callback verification would become popular detect spam c/r systems challenging message forged sender address would send challenge new message person whose address forged would create e-mail backscatter would effectively shift burden person would received spam person whose address forged addition forged sender decided validate challenge c/r user would receive spam anyway forged sender address would whitelisted though definitely undesirable side-effect issue would non-existent people whose email address used forged address spam happen run c/r system case one c/r users must implement form return address signing bounce address tag validation ensure challenge goes also systems like spf dkim became common forged sender addresses would recognized systems reaching c/r system cases c/r systems tricked becoming spam relays useful part message challenge generally included challenge message spammer knowing sending c/r using system could design message spam payload part message challenge message includes case forged sender actual recipient spam c/r system unwittingly relay disseminating ordinary email address protected c/r system results challenges send mail address c/r critics consider rude give people email address require unless previously whitelisted might always possible answer challenge send mail advocates c/r systems argue benefits far outweigh 'burden incidental challenge probably never final solution spam without laying kind burden e-mail sender reason widespread use c/r systems understood accepted appreciated analogy snail mail sender prepared pay stamp analogy phone calls caller prepared pay outgoing call c/r systems interact badly mailing list software person subscribed mailing list begins use c/r software posters mailing list may confronted challenge messages order confirmations billing statements delivery notices online shopping systems usually sent via automated systems email challenges sent systems lost legitimate mail sent systems may reach c/r system user advocates c/r systems argue though takes extra effort solutions problems exist end-user behind c/r system simple things c/r advocates claim systems lower rate false positives systems automatically filtering unsolicited bulk email critics argue typical users c/r systems still need review challenged mail regularly looking non-bulk mail solicited bulk email sender responded challenge issue particularly notable newsletters transactional messages solicited bulk email senders usually check challenges mail however bulk email question solicited c/r user could expected added whitelist bulk email solicited definition spam filtered c/r system
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Computer security
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safetica technologies safetica technologies european data loss prevention software dlp vendor safetica dlp designed contextual protection data endpoint level blocks erroneous malicious actions might lead sensitive files leaving company safetica also identify wasted costs connected low work productivity ineffective use software licenses wasted print company history goes back 2007 group security professionals led founder jakub mahdal started developing security solutions czech republic 2011 company started using name safetica technologies introduced first version product called safetica dlp soon partnered top-class investor ondřej tomek put 1,000,00 research development got first customers abroad 2013 safetica started distribution markets asia middle east 2015 safetica technologies received 1,500,000 investment product development petr žikeš became new ceo 2016 company partnered global antivirus company eset bundle products antivirus products means safetica distributed throughout global sales network covering 180 countries
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Computer security
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memory barrier memory barrier also known membar memory fence fence instruction type barrier instruction causes central processing unit cpu compiler enforce ordering constraint memory operations issued barrier instruction typically means operations issued prior barrier guaranteed performed operations issued barrier memory barriers necessary modern cpus employ performance optimizations result out-of-order execution reordering memory operations loads stores normally goes unnoticed within single thread execution cause unpredictable behaviour concurrent programs device drivers unless carefully controlled exact nature ordering constraint hardware dependent defined architecture memory ordering model architectures provide multiple barriers enforcing different ordering constraints memory barriers typically used implementing low-level machine code operates memory shared multiple devices code includes synchronization primitives lock-free data structures multiprocessor systems device drivers communicate computer hardware program runs single-cpu machine hardware performs necessary bookkeeping ensure program executes memory operations performed order specified programmer program order memory barriers necessary however memory shared multiple devices cpus multiprocessor system memory-mapped peripherals out-of-order access may affect program behavior example second cpu may see memory changes made first cpu sequence differs program order following two-processor program gives example out-of-order execution affect program behavior initially memory locations codice_1 codice_2 hold value codice_3 program running processor 1 loops value codice_2 zero prints value codice_1 program running processor 2 stores value codice_6 codice_1 stores value codice_8 codice_2 pseudo-code two program fragments shown steps program correspond individual processor instructions processor 1 processor 2 one might expect print statement always print number 42 however processor 2 store operations executed out-of-order possible codice_2 updated codice_1 print statement invoked come loop similarly processor 1 load operations may executed out-of-order possible codice_1 read codice_2 checked print statement might therefore print unexpected value programs neither situations acceptable memory barrier inserted processor 2 assignment codice_2 ensure new value codice_1 visible processors prior change value codice_2 another inserted processor 1 access codice_1 ensure value codice_1 read prior seeing change value codice_2 another example driver performs following sequence processor store operations executed out-of-order hardware module may triggered data ready memory another illustrative example non-trivial one arises actual practice see double-checked locking multithreaded programs usually use synchronization primitives provided high-level programming environment java .net framework application programming interface api posix threads windows api synchronization primitives mutexes semaphores provided synchronize access resources parallel threads execution primitives usually implemented memory barriers required provide expected memory visibility semantics environments explicit use memory barriers generally necessary api programming environment principle high-level memory model defines memory visibility semantics although programmers usually need use memory barriers high level environments important understand memory visibility semantics extent possible understanding necessarily easy achieve memory visibility semantics always consistently specified documented programming language semantics defined different level abstraction machine language opcodes programming environment memory model defined different level abstraction hardware memory model important understand distinction realize always simple mapping low-level hardware memory barrier semantics high-level memory visibility semantics particular programming environment result particular platform implementation posix threads may employ stronger barriers required specification programs take advantage memory visibility implemented rather specified may portable memory barrier instructions address reordering effects hardware level compilers may also reorder instructions part program optimization process although effects parallel program behavior similar cases general necessary take separate measures inhibit compiler reordering optimizations data may shared multiple threads execution note measures usually necessary data protected synchronization primitives discussed prior section c c++ volatile keyword intended allow c c++ programs directly access memory-mapped i/o memory-mapped i/o generally requires reads writes specified source code happen exact order specified omissions omissions reorderings reads writes compiler would break communication program device accessed memory-mapped i/o c c++ compiler may omit reads writes volatile memory locations may reorder read/writes relative actions volatile location variable keyword volatile guarantee memory barrier enforce cache-consistency therefore use volatile alone sufficient use variable inter-thread communication systems processors c c++ standards prior c11 c++11 address multiple threads multiple processors usefulness volatile depends compiler hardware although volatile guarantees volatile reads volatile writes happen exact order specified source code compiler may generate code cpu may re-order execution volatile read write reordered regard non-volatile reads writes thus limiting usefulness inter-thread flag mutex preventing compiler specific compilers like gcc reorder operations around in-line assembly code volatile memory tags like asm volatile memory see examples compiler memory barrier moreover guaranteed volatile reads writes seen order processors cores due caching cache coherence protocol relaxed memory ordering meaning volatile variables alone may even work inter-thread flags mutexes
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Computer architecture
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dual format dual format technique used allow two completely different systems software reside disk term used amiga atari st platform indicate disk could inserted either machine would still boot run secret behind lies special layout first track disk contained amiga atari st bootsector time fooling operating system think track resolved format expected games used technique three produced eclipse software design stone age monster business lethal xcess st/amiga format magazine also used technique coverdisks amiga pc dual-format games also existed like budget version rick dangerous game 3d pool even contained tri-format disk contained amiga atari st pc versions game dual tri-format disks implemented using technology developed rob computing recently dual format come identify software distributed single disk includes windows macintosh versions installation program list dual format floppy disk titles
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Computer architecture
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security parameter index security parameter index spi identification tag added header using ipsec tunneling ip traffic tag helps kernel discern two traffic streams different encryption rules algorithms may use spi per rfc 2401 required part ipsec security association sa enables receiving system select sa received packet processed spi local significance since defined creator sa spi generally viewed opaque bit string however creator sa may interpret bits spi facilitate local processing works like port numbers tcp udp connections means could different sas used provide security one connection sa could therefore act set rules carried encapsulating security payload esp header authentication header ah length 32 bits
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Internet protocols
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cell loss priority cell loss priority clp flag bit atm cell header determines probability cell discarded network becomes congested cells clp 0 insured traffic unlikely dropped cells clp 1 best-effort traffic may discarded congested conditions order free resources handle insured traffic clp used control network traffic policing mechanism policing process determines cells meet predefined restrictions enter atm network restrictions include traffic rates burst sizes agreed upon customer network provider
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Internet protocols
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burroughs b1700 burroughs b1000 series series mainframe computers built burroughs corporation originally introduced 1970s continued software development 1987 series consisted three major generations b1700 b1800 b1900 series machines also known burroughs small systems contrast burroughs large systems b5000 b6000 b7000 b8000 burroughs medium systems b2000 b3000 b4000 much original research b1700 initially codenamed plp proper language processor program language processor done burroughs pasadena plant production b1700s began mid-1970s occurred santa barbara liege belgium plants majority design work done santa barbara b1830 notable exception designed liege b1000 distinguished machines writeable control store allowing machine emulate machine burroughs mcp master control program would schedule particular job run mcp would preload interpreter whatever language required interpreters presented different virtual machines cobol fortran etc notable idea semantic gap ideal expression solution particular programming problem real physical hardware illustrated inefficiency current machine implementations three burroughs architectures represent solving problem building hardware aligned high-level languages so-called language-directed design contemporary term today often called high-level language computer architecture large systems stack machines efficiently executed algol medium systems b2000 3000 b4000 aimed business world executing cobol thus everything done bcd including addressing memory b1000 series perhaps universal solution perspective used idealized virtual machines language actual hardware built enhance capability perhaps obvious examples bit-addressable memory variable size arithmetic logic unit alu ability data register instruction register allowing efficient instruction parsing another feature machine language appearance output alu appear different addressable registers x+y x-y two read-only registers within machine language one concession fact burroughs primarily supplier business thus running cobol availability bcd arithmetic alu internally machines employed 16-bit instructions 24-bit data path bit addressable memory supported mix quite efficiently internally later generation memories stored data 32-bit boundaries capable reading across boundary supplying merged result initial hardware implementations built ctl family originally made fairchild semiconductor introduction b1955 1979 series employed popular readily obtainable ttl logic family b1955 control logic implemented proms muxes b1965 last series implemented pair microcode sequencers stayed lock step majority instructions executed single cycle first cycle decoded fplas using 16 inputs perfect size 16-bit instruction word 48 min-terms successive cycles multi-cycle instruction sourced proms fplas prom outputs wired together fpla would drive output first cycle get tri-stated proms would drive control lines completion instruction i/o system b1000 series consisted 24-bit data path control strobes peripherals cpu would place data data path inform peripheral data present many peripheral adapters fairly simplistic cpu actually drove adapter state machines operations successive accesses later models machines 1800 1900 series could configured either single dual processor tightly coupled machines competed access main memory b1955 b1965 could accommodate four processors memory bus least one would assigned multi-line adapter supplied serial i/o system dual-processor configurations ever actually sold multi-line capable driving multiple 19.2kb rs485 serial lines multi-drop configuration serial i/o polled given terminal would wait addressed grab line send data pending multi-line adapter would dma data main memory linked list format consequently processors n't deal serial i/o interrupt issues taken care fact block mode terminals type supported b1000 series could address maximum 2 megabytes memory days multiple gigabytes sounds fairly limiting commercial installations got hundreds kilobytes storage
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Computer architecture
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file deletion file deletion way removing file computer file system examples reasons deleting files operating systems include commands deleting files rm unix era cp/m dr-dos del/erase ms-dos/pc dos dr-dos microsoft windows etc. file managers also provide convenient way deleting files files may deleted one-by-one whole directory tree may deleted common problem deleting files accidental removal information later proves important one way deal back files regularly erroneously deleted files may found archives another technique often used delete files instantly move temporary directory whose contents deleted recycle bin trash works microsoft windows apple macos well linux distributions employ strategy ms-dos one use undelete command ms-dos deleted files really deleted marked deleted—so could undeleted time disk blocks used eventually taken files data recovery programs work scanning files marked deleted space freed per byte rather per file sometimes cause data recovered incompletely defragging drive may prevent undeletion blocks used deleted file might overwritten since marked empty another precautionary measure mark important files read-only many operating systems warn user trying delete files file system permissions exist users lack necessary permissions able delete files preventing erasure people work critical system files unix-like operating systems order delete file one must usually write permission parent directory file common problem sensitive data deleted files really erased may recovered interested parties file systems remove link data see undelete even overwriting parts disk something else formatting may guarantee sensitive data completely unrecoverable special software available overwrites data modern post-2001 ata drives include secure erase command firmware however high security applications high-security enterprises sometimes require disk drive physically destroyed ensure data recoverable microscopic changes head alignment effects mean even measures guaranteed data encrypted encryption key unavailable crypto-shredding practice 'deleting data deleting overwriting encryption keys
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Computer file systems
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berkeley iram project 1996–2004 research project computer science division university california berkeley berkeley iram project explored computer architecture enabled wide bandwidth memory processor made possible designed integrated circuit chip since envisioned chip would consist primarily random-access memory ram smaller part needed central processing unit cpu research team used term intelligent ram iram describe chip architecture like j–machine project mit primary objective research avoid von neumann bottleneck occurs connection memory cpu relatively narrow memory bus separate integrated circuits strong competitive pressures technology employed component computer system—principally cpu memory offline storage—is typically selected minimize cost needed attain given level performance though microprocessor memory implemented integrated circuits prevailing technology used differs microprocessor technology optimizes speed memory technology optimizes density reason integration memory processor chip part limited static random-access memory sram may implemented using circuit technology optimized logic performance rather denser lower-cost dynamic random-access memory dram microprocessor access off-chip memory costs time power however significantly limiting processor performance reason computer architecture employing hierarchy memory systems developed static memory integrated microprocessor temporary easily accessible storage cache data also retained off-chip dram since on-chip cache memory redundant presence adds cost power purpose iram research project find computing applications better trade-off cost performance could achieved architecture dram integrated on-chip processor thus eliminating need redundant static memory cache—even though technology used optimum dram implementation fair say berkeley iram achieve recognition berkeley risc received iram project nevertheless influential although initial iram proposals focused trade-offs cpu dram iram research came concentrate vector instruction sets publications early advocates incorporation vector processing vector instruction sets microprocessors several commercial microprocessors intel avx subsequently adopted vector processing instruction set extensions
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Computer architecture
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aiyara cluster aiyara cluster low-powered computer cluster specially designed process big data aiyara cluster model considered specialization beowulf cluster sense aiyara also built commodity hardware inexpensive personal computers system-on-chip computer boards unlike beowulf applications aiyara cluster scoped big data area scientific high-performance computing another important property aiyara cluster low-power must built class processing units produces less heat name aiyara originally referred first arm-based cluster built wichai srisuruk chanwit kaewkasi suranaree university technology name aiyara came thai word literally elephant reflect underneath software stack apache hadoop like beowulf aiyara cluster define particular software stack run atop cluster normally runs variant linux operating system commonly used big data software stacks apache hadoop apache spark report aiyara hardware successfully processed non-trivial amount big data published proceedings icsec 2014 aiyara mk-i second aiyara cluster consists 22 cubieboards first known soc-based arm cluster able process big data successfully using spark hdfs stack aiyara cluster model technical description explaining build aiyara cluster later published chanwit kaewkasi dzone 2014 big data guide results cluster optimization techniques make cluster processing rate boost 0.9 gb/min still preserve low-power consumption reported proceeding ieee tencon 2014
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Distributed computing architecture
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language workbench language workbench tool set tools enables software development language-oriented programming software development paradigm language workbench typically include tools support definition reuse composition domain-specific languages together integrated development environment language workbenches introduced popularized martin fowler 2005 language workbenches usually support
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Programming language topics
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brain test brain test piece malware masquerading android app tested users iq brain test discovered security firm check point available google play app store 15 september 2015 check point described brain test new level sophistication malware brain test uploaded two separate occasions com.zmhitlte.brain com.mile.brain starting august 2015 times google bouncer failed detect malware first removal 24 august 2015 software reintroduced using obfuscation technique tim erin tripwire said bypassing vetting processes apple google keystone mobile malware campaign malware turned include rootkit revelation described cunning first thought malware thought written chinese actor according shaulov check point based use packing/obfuscation tool baidu eleven paths telefonica-owned company found links may pieces malware based id used access umeng internet domains accessed apps shared jpg png images appears app first detected nexus 5 using check point mobile threat prevention system fact system unable remove malware alerted software company researchers unusual threat according check point may necessary re-flash rom device brain test successfully installed reinstaller system directory malware uploaded two forms packing feature present second
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Computer security
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managed security service computing managed security services mss network security services outsourced service provider company providing service managed security service provider mssp roots mssps internet service providers isps mid late 1990 ’ initially isp would sell customers firewall appliance customer premises equipment cpe additional fee would manage customer-owned firewall dial-up connection according recent industry research organizations 74 manage security in-house 82 professionals said either already partnered plan partner managed security service provider businesses turn managed security services providers alleviate pressures face daily related information security targeted malware customer data theft skills shortages resource constraints managed security services mss also considered systematic approach managing organization security needs services may conducted in-house outsourced service provider oversees companies network information system security functions managed security service include round-the-clock monitoring management intrusion detection systems firewalls overseeing patch management upgrades performing security assessments security audits responding emergencies products available number vendors help organize guide procedures involved diverts burden performing chores manually considerable away administrators industry research firm forrester research identified 14 significant vendors global market 2018 23-criteria evaluation managed security service providers mssps -- identifying accenture ibm dell secureworks trustwave verizon deloitte wipro others leaders mssp market newcomers market include number smaller providers used protect homes small business high networth clients early example outsourced off-site mssp service us west nteract internet security security service ’ require customer purchase equipment security equipment installed customers premises service considered mssp offering us west retained ownership firewall equipment firewalls operated internet point presence pop service based check point firewall-1 equipment following year long beta introduction period service generally available early 1997 service also offered managed virtual private networking vpn encryption security launch customized assistance assessment business risks key business requirements security development security policies processes may include comprehensive security architecture assessments design include technology business risks technical risks procedures consulting may also include security product integration on-site mitigation support intrusion occurred including emergency incident response forensic analysis service involves installing upgrading managing firewall virtual private network vpn and/or intrusion detection hardware software electronic mail commonly performing configuration changes behalf customer management includes monitoring maintaining firewall traffic routing rules generating regular traffic management reports customer intrusion detection management either network level individual host level involves providing intrusion alerts customer keeping date new defenses intrusion regularly reporting intrusion attempts activity content filtering services may provided email filtering data traffic filtering clearly managed service product resale major revenue generator many mss providers category provides value-added hardware software variety security-related tasks one service may provided archival customer data day-to-day monitoring interpretation important system events throughout network—including unauthorized behavior malicious hacks denial service dos anomalies trend analysis first step incident response process includes one-time periodic software scans hacking attempts order find vulnerabilities technical logical perimeter generally assess security throughout network accurately reflect personnel-related exposures due disgruntled employees social engineering etc regularly reports given client includes monitoring event logs intrusions change management service identify changes system violate formal security policy example rogue administrator grants much access system short measures compliance technical risk model decision criteria engaging services mssp much form outsourcing cost-effectiveness compared in-house solutions focus upon core competencies need round-the-clock service ease remaining up-to-date important factor specific mss outsourcing network security hands critical control company infrastructure outside party mssp whilst relieving ultimate responsibility errors client mssp still ultimate responsibility security must prepared manage monitor mssp hold accountable services contracted relationship mssp client turnkey one although organization remains responsible defending network information security related business risks working mssp allows organization focus core activities remaining protected network vulnerabilities business risks result information assets upon business depends securely configured managed resulting asset compromise due violations confidentiality availability integrity compliance specific government-defined security requirements achieved using managed security services business model behind managed security services commonplace among large enterprise companies security experts model later adapted fit medium-sized smaller companies smbs organizations 500 employees 100 employee one site value-added reseller var community either specializing managed security offering extension managed service solutions smbs increasingly turning managed security services number reasons chief among specialized complex highly dynamic nature security growing number regulatory requirements obliging businesses secure digital safety integrity personal information financial data held transferred via computer networks whereas larger organizations typically employ specialist department organizations smaller scale distributed location businesses medical dental offices attorneys professional services providers retailers typically employ full-time security specialists although frequently employ staff external consultants organizations many constrained budget limitations address combined issues lack expertise lack time limited financial resources emerging category managed security service provider smb arisen organizations across sectors shifting managed security services traditional in-house security practices trend outsourcing security jobs managed security services vendors picking appreciable pace also helps enterprises focus core business activities strategic approach effective management cost-effectiveness seamless monitoring major drivers fueling demand services increase participation leading companies worldwide end user enterprises gaining confidence outsourcing security services providers category tend offer comprehensive security services delivered remotely managed appliances devices simple install run part background fees normally highly affordable reflect financial constraints charged monthly basis flat rate ensure predictability costs service providers deliver daily weekly monthly exception-based reporting depending client ’ requirements security tuning firewall tuning/ ids tuning/ siem tuning today security become power weapon cyberattacks become highly sophisticated enterprises toil keep par new malware deviant e-mail spoofing fraud gambit among different prominent players managed security service provider observe growing need combat increasingly complicated intended attacks response vendors busy enhancing sophistication solution many cases winning security expert expand portfolio besides increasing regulatory compliance associated protection citizen ’ data worldwide likely stimulate enterprises ensure high data-security level frontrunners engaging managed security services financial services telecom information technology etc maintain competitive edge mss vendors focusing refining product offering technologies deployed clients another crucial factor profitability remains capability lower cost yet generate revenue avoiding deployment additional tools simplifying service creation integration products ensures unprecedented visibility well integration besides mss market would witness tremendous growth regions north america europe asia –pacific latin america middle east africa
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Computer security
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dig dug dig dug programmed shouichi fukatani worked many namco earlier arcade titles designed junior colleagues galaga creator shigeru yokoyama music composed yuriko keino becoming first game worked namco — short jingle made character moved made executives wanted walking sound game described strategic digging game namco large amount strategy used defeat enemies heavily used game marketing upon release dig dug well-received critics addictive gameplay cute characters strategy popular title golden age arcade video games met long series sequels spin-offs several platforms alongside ports home consoles digital storefronts dig dug also included many namco video game compilations number systems characters game appear throughout mr. driller series based dig dug gameplay dig dug maze video game controlling titular character player objective eliminate enemies screen pookas red tomato-like creatures comically large goggles fygars green dragons breathe fire dig dug defeat enemies using bike pump inflate air explode crushing large falling rocks bonus points awarded squashing multiple enemies single rock dropping two rocks stage cause bonus item appear middle screen eaten points enemies defeated dig dug progress next stage enemies travel solid dirt reach player eyes shown inflated enemies pose threat player allowing dig dug pass without harm game play short jingle dig dug moves abruptly stopping becomes idle player takes long clear stage enemies become faster much aggressive indicated short jingle stages indicated number flowers placed top screen later stages feature variations color dirt increasing movement speed enemies dig dug first released japan namco april 19 1982 later released north america europe atari inc. later year game programmed shouichi fukatani worked many company earlier arcade titles died 1985 ran namco galaga arcade system modified shigeichi ishimura described namco strategic digging game amount strategy used defeat enemies heavily used game marketing music composed yuriko keino first video game namco worked — idea music played character moved inspired development team want add walking sound player instead replaced short jingle many developers junior colleagues galaga creator shigeru yokoyama helped supervise project first home conversion dig dug released atari 2600 1983 developed published atari followed versions atari 5200 colecovision atari 8-bit family commodore 64 apple ii japan game ported casio pv-1000 1983 later msx 1984 nintendo family computer 1985 gakken produced handheld lcd tabletop game 1983 replaced dig dug air pump flamethrower accommodate hardware limitations namco released game boy conversion north america 1992 featured all-new game called new dig dug player must collect keys open exit door — version later included 1996 japan-only compilation namco gallery vol 3 also included galaxian tower druaga famista 4 japanese sharp x68000 version developed dempa released 1995 bundled dig dug ii dig dug included several namco video game compilations including namco museum vol 3 1996 namco museum 64 1999 namco museum 50th anniversary 2005 namco museum remix 2007 namco museum essentials 2009 namco museum switch 2017 game released digitally xbox live arcade 2006 featuring support online leaderboards achievements added xbox one backwards compatibility lineup 2016 version japanese wii virtual console released 2009 dig dug also included bonus game pac-man party alongside arcade versions pac-man galaga dig dug critical commercial success upon release praised strategy gameplay character designs sold 22,228 arcade units north america end 1982 grossing us 46.3 million revenue popular title golden age arcade video games american publication blip magazine favorably compared games pac-man defender simple controls fun gameplay allgame called arcade nes classic praising characters gameplay unique premise easily translatable home platforms japanese magazine gamest called one greatest arcade games time 1998 applauding addictiveness breaking traditional dot-eater gameplay used titles pac-man rally-x 2007 retrospective eurogamer praised perfect gameplay strategy saying one memorable legendary videogame releases past 30 years killer list videogames rated six popular coin-op game website electronic fun computers games praised atari 8-bit version retaining entertaining gameplay arcade version simple controls reviewing xbox live arcade digital re-release ign liked presentation leaderboards achievements noting still extremely fun addicting game recommending fans original newcomers gamespot similar response praising xbla version colorful artwork retaining original arcade gameplay eurogamer applauded game addictiveness still holding years release home versions game would receive criticism quality lack exclusive content readers softline magazine ranked dig dug tenth-worst apple ii fourth-worst atari 8-bit video game 1983 subpar quality living consumer expectations eurogamer ign gamespot criticized xbla conversion lack online multiplayer achievements easy unlock eurogamer particular criticizing game controls sometimes unresponsive dig dug met long series sequels several platforms first dig dug ii released 1985 less successful game opted overhead perspective instead digging earth dig dug drills along fault lines sink pieces island ocean 1996 remake game dig dug arrangement released arcades alongside original namco classic collection vol 2 arcade collection added new enemies music power-ups boss fights two-player co-operative play 3d followup titled dig dug deeper published infogrames 2001 windows nintendo ds sequel released 2005 combining elements first two games adding narrative link mr. driller series massively-multiplayer online game dig dug island publicly released 2008 online version dig dug ii game lasted year servers shuttered 2009 two dig dug -themed slot machines produced japanese company oizumi 2003 small lcd monitors featuring animations dig dug characters webcomic adaptation game produced 2012 shiftylook subsidiary bandai namco focused reviving older namco game franchises drawn several different artists lasting nearly 200 issues concluding 2014 following closure shiftylook character dig dug renamed taizo hori play japanese phrase horitai zo meaning want dig would become prominent character namco mr. driller series retconned father susumu hori married baraduke protagonist masuyo tobi would divorce unknown reasons taizo appears playable character namco super wars wonderswan color namco × capcom playstation 2 released japan taizo appears now-defunct web browser game namco high principal titular high school simply known president dig dug pookas would appear several namco video games including sky kid 1985 pac-man world 1999 pro baseball famista ds 2011 2011 super smash bros. nintendo 3ds wii u 2014
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Computer architecture
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southampton basic system southampton basic system sobs dialect basic programming language developed used ict 1900 series computers late 1960s early 1970s implemented minimop operating system university southampton also ran maximop operated teletype terminal though crt terminals could also used common many early implementations basic sobs needed lines line numbers allow user add new lines program desired place also targets codice_1 codice_2 statements codice_3 facility available allow sections code renumbered default increments 10 allow space middle program line numbers numeric values represented internally floating point language relatively statements comparison modern programming languages note particular lack codice_4-like statement codice_5 looping construct available programmers variable names numeric values either single letter single letter followed single numeric digit thus allowing 286 discreet variables total strings supported variable names restriction followed pound codice_6 symbol limited number numeric functions provided took one numeric parameter support strings limited one function codice_7 returned length string parameter sub-strings supported square brackets codice_8 referred sub-string string codice_9 2nd character 3rd character inclusive would print codice_10 syntax also supported left-hand side assignment would print codice_11 support handling arrays data relatively strong codice_12 statements able read entire array codice_13 statements perform useful matrix operations matrix addition matrix subtraction matrix multiplication finding inverse matrix square matrix example output would sobs primitive debugging capabilities limited mostly codice_14 statement codice_15 would cause interpreter print line number executed
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Programming language topics
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nso group nso group technologies israeli technology firm focused cyber intelligence founded 2010 niv carmi omri lavie shalev hulio reportedly employs around 500 people based herzliya near tel aviv annual revenues said around 40 million 2013 150 million 2015 june 2017 company put sale 1 billion francisco partners management founders lavie hulio partnering european private equity fund novalpina capital purchased majority stake nso february 2019 according company nso provides authorized governments technology helps combat terror crime claims software created nso group used targeted attacks human rights activists journalists several countries nso founders said ex-members unit 8200 israeli intelligence corps unit responsible collecting signals intelligence company start-up funding came group investors headed eddy shalev partner venture capital fund genesis partners group invested total 1.8 million dollars 30 stake 2012 government mexico announced signing 20 million contract nso 2015 company reportedly sold surveillance technology government panama contract became subject panamanian anti-corruption investigation following disclosure leak confidential information italian firm hacking team 2014 american private equity firm francisco partners bought company 130 million reported 2015 francisco seeking sell company 1 billion company officially put sale 1 billion june 2017 roughly ten times francisco originally paid 2014 february 14 2019 francisco partners sold 60 majority stake nso back co-founders shalev hulio omri lavie supported purchase novalpina capital hulio lavie invested 100 million novalpina acquiring remaining portion majority stake thus valuing company approximately 1 billion day acquisition novalpina attempted address concerns raised citizen lab letter stating belief nso operates sufficient integrity caution april 2019 nso froze deals saudi arabia scandal alleging nso software role tracking slain journalist jamal khashoggi months death may 2019 exploit whatsapp alleged developed nso whatsapp told financial times broke news attack hallmarks private company known work governments deliver spyware reportedly takes functions mobile phone operating systems nso denied involvement selecting targeting victims explicitly denied creating exploit august 25 2016 citizen lab lookout revealed software known pegasus created nso used target human rights activist ahmed mansoor united arab emirates mansoor informed citizen lab researchers bill marczak john scott-railton iphone 6 targeted august 10 2016 means clickable link sms text message analysis citizen lab lookout discovered link downloaded software exploit three previously unknown unpatched zero-day vulnerabilities ios according analysis software jailbreak iphone malicious url opened form attack known spear phishing software installs collects communications locations targeted iphones including communications sent imessage gmail viber facebook whatsapp telegram skype software also collect wi-fi passwords researchers noticed software code referenced nso group product called pegasus leaked marketing materials pegasus previously come light leak records hacking team indicated software supplied government panama 2015 researchers claim mexican journalist rafael cabrera also targeted software could used israel turkey thailand qatar kenya uzbekistan mozambique morocco yemen hungary saudi arabia nigeria bahrain citizen lab lookout notified apple security team patched flaws within ten days released update ios patch macos released six days later 2017 citizen lab researchers revealed nso exploit links may sent mexican scientists public health campaigners targets supported measures reduce childhood obesity including mexico soda tax july 2017 international team assembled investigate 2014 iguala mass kidnapping publicly complained thought surveilled mexican government claim mexican government used pegasus send messages funeral homes containing links clicked allowed government surreptitiously listen investigators mexican government repeatedly denied unauthorized hacking june 2018 israeli court indicted former employee nso group allegedly stealing copy pegasus attempting sell online 50 million worth cryptocurrency december 2018 new york times investigation concluded pegasus software played role murder jamal khashoggi friend khashoggi claimed filing saudi authorities used israeli-made software spy dissident citizen lab researchers reported october 2018 targeted undercover operatives connected nso citizen lab previously reported use nso software spy inner circle jamal khashoggi murder citizen lab october report revealed nso signature spy software placed iphone saudi dissident omar abdulaziz one khashoggi ’ confidantes months abdulaziz claimed software revealed khashoggi private criticisms saudi royal family abdulaziz claimed played major role kashoggi death ap report incident could find direct evidence connecting operative surveillance citizen lab ’ researchers nso nso denied involvement phone joaquín guzmán known el chapo hacked using nso software 2011 mexican president felipe calderón reportedly called nso thank company role guzmán capture
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Computer security
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casebook pbc casebook pbc us cloud computing public-benefit corporation headquartered new york city incubated annie e. casey foundation company initially developed child welfare solutions since expanded provide saas platform servicing whole human services casebook initially started project annie e. casey foundation leadership kathleen feely vice-president innovation foundation early success private service providers software spun non-profit organization known case commons 2012 indiana department child services first state agency implement casebook mobile web-based solution child welfare caseworkers effort led organization receiving design experience award 2014 code america technology award 2015 2017 organization helped state california child welfare digital services agency learn build ship software year leadership new ceo tristan louis casebook pbc entered national partnership kpmg allowing kpmg leverage casebook platform exclusive solution child welfare vertical rebranded case commons casebook pbc company offers casebook platform set core components used variety human services software developments historical background child welfare space company also offers suite applications put together allow states assemble ccwis-ready child welfare system official company site casebook pbc certified b-corp
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Distributed computing architecture
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query optimization query optimization function many relational database management systems query optimizer attempts determine efficient way execute given query considering possible query plans generally query optimizer accessed directly users queries submitted database server parsed parser passed query optimizer optimization occurs however database engines allow guiding query optimizer hints query request information database simple finding address person ss 123-45-6789 complex like finding average salary employed married men california ages 30 39 earn less wives queries results generated accessing relevant database data manipulating way yields requested information since database structures complex cases especially not-very-simple queries needed data query collected database accessing different ways different data-structures different orders different way typically requires different processing time processing times query may large variance fraction second hours depending way selected purpose query optimization automated process find way process given query minimum time large possible variance time justifies performing query optimization though finding exact optimal way execute query among possibilities typically complex time consuming may costly often practically impossible thus query optimization typically tries approximate optimum comparing several common-sense alternatives provide reasonable time good enough plan typically deviate much best possible result trade-off amount time spent figuring best query plan quality choice optimizer may choose best answer different qualities database management systems different ways balancing two cost-based query optimizers evaluate resource footprint various query plans use basis plan selection assign estimated cost possible query plan choose plan smallest cost costs used estimate runtime cost evaluating query terms number i/o operations required cpu path length amount disk buffer space disk storage service time interconnect usage units parallelism factors determined data dictionary set query plans examined formed examining possible access paths e.g. primary index access secondary index access full file scan various relational table join techniques e.g. merge join hash join product join search space become quite large depending complexity sql query two types optimization consist logical optimization—which generates sequence relational algebra solve query—and physical optimization—which used determine means carrying operation query optimizers represent query plans tree plan nodes plan node encapsulates single operation required execute query nodes arranged tree intermediate results flow bottom tree top node zero child nodes—those nodes whose output fed input parent node example join node two child nodes represent two join operands whereas sort node would single child node input sorted leaves tree nodes produce results scanning disk example performing index scan sequential scan performance query plan determined largely order tables joined example joining 3 tables b c size 10 rows 10,000 rows 1,000,000 rows respectively query plan joins b c first take several orders-of-magnitude time execute one joins c first query optimizers determine join order via dynamic programming algorithm pioneered ibm system r database project algorithm works two stages sort order avoid redundant sort operation later processing query second particular sort order speed subsequent join clusters data particular way sql query modern relational dbms selections joins particular sql queries often nest several layers spj blocks select-project-join means group exists exists operators cases nested sql queries flattened select-project-join query always query plans nested sql queries also chosen using dynamic programming algorithm used join ordering lead enormous escalation query optimization time database management systems use alternative rule-based approach uses query graph model one hardest problems query optimization accurately estimate costs alternative query plans optimizers cost query plans using mathematical model query execution costs relies heavily estimates cardinality number tuples flowing edge query plan cardinality estimation turn depends estimates selection factor predicates query traditionally database systems estimate selectivities fairly detailed statistics distribution values column histograms technique works well estimation selectivities individual predicates however many queries conjunctions predicates query predicates often highly correlated example codice_1 implies codice_2 hard estimate selectivity conjunct general poor cardinality estimates uncaught correlation one main reasons query optimizers pick poor query plans one reason database administrator regularly update database statistics especially major data loads/unloads classical query optimization assumes query plans compared according one single cost metric usually execution time cost query plan calculated without uncertainty assumptions sometimes violated practice multiple extensions classical query optimization studied research literature overcome limitations extended problem variants differ model cost single query plans terms optimization goal classical query optimization associates query plan one scalar cost value parametric query optimization assumes query plan cost depends parameters whose values unknown optimization time parameters instance represent selectivity query predicates fully specified optimization time provided execution time parametric query optimization therefore associates query plan cost function maps multi-dimensional parameter space one-dimensional cost space goal optimization usually generate query plans could optimal possible parameter value combinations yields set relevant query plans run time best plan selected set true parameter values become known advantage parametric query optimization optimization general expensive operation avoided run time often cost metrics addition execution time relevant compare query plans cloud computing scenario instance one compare query plans terms much time take execute also terms much money execution costs context approximate query optimization possible execute query plans randomly selected samples input data order obtain approximate results reduced execution overhead cases alternative query plans must compared terms execution time also terms precision reliability data generate multi-objective query optimization models cost query plan cost vector vector component represents cost according different cost metric classical query optimization considered special case multi-objective query optimization dimension cost space i.e. number cost vector components one different cost metrics might conflict e.g. might one plan minimal execution time different plan minimal monetary execution fees cloud computing scenario therefore goal optimization find query plan minimizes cost metrics must find query plan realizes best compromise different cost metrics best compromise depends user preferences e.g. users might prefer cheaper plan others prefer faster plan cloud scenario goal optimization therefore either find best query plan based specification user preferences provided input optimizer e.g. users define weights different cost metrics express relative importance define hard cost bounds certain metrics generate approximation set pareto-optimal query plans i.e. plans plan better cost according metrics user select preferred cost tradeoff plan set multi-objective parametric query optimization generalizes parametric multi-objective query optimization plans compared according multiple cost metrics plan costs may depend parameters whose values unknown optimization time cost query plan therefore modeled function multi-dimensional parameter space multi-dimensional cost space goal optimization generate set query plans optimal possible combination parameter values user preferences
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Databases
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fdisk computer file systems fdisk command-line utility provides disk partitioning functions available dos dr flexos ibm os/2 microsoft windows operating systems certain ports freebsd netbsd openbsd dragonfly bsd macos compatibility reasons versions windows nt operating system line windows 2000 onwards replaced advanced tool called codice_1 similar utilities exist unix-like systems example bsd disklabel ibm introduced fixed disk setup program version 1.00 march 1983 release ibm pc/xt first pc store data hard disk ibm personal computer dos version 2.0 version 1 could used create one fat12 dos partition delete change active partition display partition data writes master boot record supported four partitions three intended operating systems cp/m-86 xenix expected partitioning utilities support august 1984 pc dos 3.0 added fat16 partitions support larger hard disks efficiently april 1987 pc dos/fdisk 3.30 added support extended partitions could hold 23 logical drives volumes ibm pc dos 7.10 contained utilities command available ms-dos versions 3.2 later support fat16b added compaq ms-dos 3.31 later became available ms-dos/pc dos 4.0 dos programs including program came original windows 95 capable creating fat partitions types fat12 fat16 fat16b derivative ms-dos provided windows 95 windows 98 later windows versions shipping windows 95b later able manipulate fat32 partitions windows 2000 later use logical disk manager feature well unlike programs operating systems programs dos windows 9x/me alter data partition table also overwrite many sectors data partition however create extended partition partition editor must put extended boot records logical drive disk users must sure correct disk/partition chosen using dos/windows partitioning switch undocumented well known repairing master boot record supplied windows 95 report correct size hard disk larger 64 gb updated available microsoft corrects microsoft named replacement 263044usa8 version 4.72.2811.0 signature may 23 2000 original windows 98 program size smaller updated one os/2 shipped two partition table managers version 4.0 text mode fdisk gui-based fdiskpm two identical functionality manipulate fat partitions advanced hpfs partitions os/2 versions 4.5 higher including ecomstation use jfs filesystem well fat hpfs replace logical volume manager lvm dr dos 6.0 flexos include implementation command implementation freedos free software freedos version developed brian e. reifsnyder paragon technology systems pts-dos 2000 pro includes implementation mach operating system written robert baron ported 386bsd julian elischer implementation used freebsd netbsd dragonfly bsd 2019 well early versions openbsd 1995 1997 openbsd 2.2 tobias weingartner re-wrote 1997 openbsd 2.2 subsequently forked apple computer inc 2002 still used basis macos 2019 native partitions bsd systems traditionally use bsd disklabel partitioning supported certain architectures compatibility reasons addition bsd disklabel mandatory linux maximum number partitions fdisk 60 3 primary partitions 1 extended partition 56 logical partitions
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Computer file systems
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symbolic stream generator symbolic stream generator ssg software productivity aid unisys mainframe computers former univac 1100/2200 series ssg used generate run-streams corresponding ibm job control language apply administer symbolic changes program sources form version control many purposes ssg program i.e. job control script called skeleton programming language symstream tool created output streams based interpreting data provided via multiple input sources originally created univac creation operating system os updates later adopted general user community creation complex batch real-time computer processes sources could recursively reference additional sources providing wide flexibility input parsing rules output creation also source files similar levels dynamic input capability interpretation multiple input sources allowed dynamic creation output stream content complex recursive processes could applied create program source code job execution sequences simulated dynamic input virtual consoles general provide scripting capabilities reminiscent unix grep yacc tools
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Programming language topics
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atari panther atari panther cancelled 32-bit video game console atari corporation going successor atari 7800 atari xegs developed ex-sinclair team flare technology previously responsible two cancelled console projects flare one konix multisystem panther planned combination atari st atari transputer workstation blossom video hardware work started 1988 planned release 1991 directly compete super nintendo entertainment system sega genesis atari abandoned project favor 64-bit jaguar team flare convinced create 3d graphics hardware instead system features three chips consisting motorola 68000 running 16 mhz object processor called panther ensoniq sound processor called otis featuring 32 sound channels presumably es5505 panther never manufactured design eclipsed jaguar three games planned panther release games later rewritten atari jaguar upon panther demise
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Computer architecture
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quickcode quickcode formerly scraperwiki web-based platform collaboratively building programs extract analyze public online data wiki-like fashion scraper refers screen scrapers programs extract data websites wiki means user programming experience create edit programs extracting new data analyzing existing datasets main use website providing place programmers journalists collaborate analyzing public data service renamed circa 2016 n't wiki scraping time eponymous parent company renamed 'the sensible code company scrapers created using browser based ide connecting via ssh server running linux programmed using variety programming languages including perl python ruby javascript r. scraperwiki founded 2009 julian todd aidan mcguire initially funded 4ip venture capital arm tv station channel 4 since attracted additional £1 million round funding enterprise ventures francis irving chief executive officer scraperwiki
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Web technology
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amd k12 k12 amd first custom microarchitecture based armv8-a aarch64 instruction set planned release 2017 predecessor a1100 series also armv8-a used arm cortex-a57 cores product still n't released development arm architectures continuing products planned microarchitecture focus high frequency power efficiency target dense server embedded semi-custom market segments
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Computer architecture
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cfdisk cfdisk linux partition editor similar fdisk different user interface curses part util-linux package linux utility programs originally written 1992 current version 2.29 current cfdisk implementation based libfdisk supports master boot record guid partition table bsd disklabel sgi sun disk labels also provides information partitions content invoked without arguments cfdisk attempts read current partition table disk drive present findings
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Computer file systems
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macintosh 512ke macintosh 512k enhanced 512ke introduced april 1986 cheaper alternative top-of-the-line macintosh plus debuted three months previously macintosh 512k 800k disk drive 128k rom used macintosh plus like predecessors little room expansion companies create memory upgrades brought machine 2 mb earliest macintosh model able run system software 6 also earliest used appleshare server bridge mac communicate modern devices originally case identical predecessor except model number listed rear bucket agency approval label used beige-like color well like macintosh plus 1987 512ke adopted standard apple platinum color well case-front design plus without name though keeping original rear bucket later lifespan 512ke discounted offered educational market badged macintosh ed m0001d later m0001ed 512ke shipped original short macintosh keyboard extended macintosh plus keyboard built-in numeric keypad could purchased optionally version 512ke sold outside north america included full keyboard marketed macintosh 512k/800 later larger keyboard would included standard north america well although 512ke includes 128k roms 800k disk drive mac plus 512ke retains port connectors original mac reason 512ke users hard disk option slower floppy-port-based hard disk 20 similar products serial port even though 512ke roms contain scsi manager software enables use faster scsi hard disks roms ones used mac plus scsi port apple point users certain third-party products could added 512ke provide scsi port macintosh 512k could upgraded 512ke purchasing installing apple 299 macintosh plus disk drive kit included following one upgrade made apple replaced logic board rear case accommodate different port configuration macintosh plus providing built-in scsi functionality 4mb ram apple official upgrades costly many third-party manufacturers offered add-on scsi cards well ram upgrades achieve functionality new rom allowed computer run much newer system application software though loaded data ram slightly decreased amount available memory – 1.5k – leaving well 370k available applications june 1986 512ke shipped system 3.2 discontinued apple changed recommended os 512ke system 4.1 system 6.0.8 maximum os 512ke
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Computer architecture
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mapmyuser.com mapmyuser web traffic analysis tool mapmyuser provides realtime web stats visitor geolocation statistics mapmyuser used compute web usage share example
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Web technology
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