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common criteria evaluation validation scheme common criteria evaluation validation scheme ccevs united states government program administered national information assurance partnership niap evaluate security functionality information technology conformance common criteria international standard new standard uses protection profiles common criteria standards certify product change happened 2009 change implemented bring credibility back cc brand stated goal making change ensure achievable repeatable testable evaluations ccevs program partnership u.s. government industry assist consumers scheme intended serve many communities interest diverse roles responsibilities community includes product developers product vendors value-added resellers systems integrators security researchers acquisition/procurement authorities consumers products auditors accreditors individuals deciding fitness operation products within respective organizations close cooperation government industry paramount success scheme realization objectives validation body ultimate responsibility operation ccevs accordance niap policies procedures appropriate interpret amend policies procedures nist nsa responsible providing sufficient resources niap validation body may carry responsibilities however 2009 niap reached vendors labs academia customers help evaluation products therefore diminishing reliance nsa validation body led director deputy director selected nist nsa management personnel include validators technical experts various technology areas validation body ensures appropriate mechanisms place protect interests parties within ccevs participating process security evaluation disputes brought forth participating party i.e sponsor evaluation product protection profile developer cctl concerning operation ccevs associated activities shall referred validation body resolution product certified listed pp compliant niap product compliant list pcl
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Computer security
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supra-entity supra-entity conceptual element derived entity-relationship e-r technique information system modeling similar entity defined higher level encompassing individual entity occurrences parts groups groups parts parts groups concepts supra-entity supra-relationship supra-attribute created published gonzález muller work “ business entity-relationship model innovation entrepreneurship management ” applied first time work conceptually model key elements interrelationships “ business ” reality supra-entities supra-relationships supra-attributes objective covering diversity situations perspectives existing reality integrated representation higher level individual occurrences multiple parts groups entities relationships according different criteria structures properties attributes association supra-entities level partition grouping supra-entity formed individual entities multiple structures entity parts multiple structures entity groups multiple structures groups entity parts parts entity groups associated closed squared structure shown attached diagram representation multiple structures parts groups groups parts parts entity groups form supra-entity done strips connecting different elements instead usual line symbol used single structure entity-relationship models example supra-entity products business sector shown next diagram addition application modeling development databases information systems supra-entities supra-relationships allow redefinition concept innovation degrees types clarity amplitude facilitates generation ideas innovation capacity general business innovation defined supra-entity domain scope consists creation generation introduction new occurrences supra-entity elements good results success first invention major innovation improved minor incremental innovation including new occurrences replicate similar previous ones example apply definition innovation supra-entity products obtain product innovations consist creation generation introduction market new element occurrences supra-entity products good results success first invention major innovation improved minor incremental innovation including new occurrences replicate similar previous ones business innovation traditionally identified introduction marketing new improved products processes market innovation necessarily require technological innovate identifying new needs new customer segments new ways getting product customer new forms agreements contracting new environments etc summary possible innovate different supra-entities supra-relationships constitute business entity-relationship model achieving different types innovations increasing innovation capacity business
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Databases
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ibm db2 family db2 family data management products including database servers developed ibm support relational model recent years products extended support object-relational features non-relational structures like json xml brand name styled db2 creation 1983 2017 historically unlike database vendors ibm produced platform-specific db2 product major operating systems however 1990s ibm changed track produced db2 mostly-common product designed mostly common code base l-u-w linux-unix-windows db2 z db2 different result use different drivers db2 traces roots back beginning 1970s edgar f. codd researcher working ibm described theory relational databases june 1970 published model data manipulation 1974 ibm san jose research center developed relational dbms system r implement codd concepts key development system r project sql apply relational model codd needed relational-database language named dsl/alpha time ibm n't believe potential codd ideas leaving implementation group programmers codd supervision violated several fundamentals codd relational model result structured english query language sequel ibm released first relational-database product wanted commercial-quality sublanguage well overhauled sequel renamed basically-new language structured query language sql ibm bought metaphor computer systems utilize gui interface encapsulating sql platform already use since mid 80 parallel development sql ibm also developed query example qbe first graphical query language ibm first commercial relational-database product sql/ds released dos/vse vm/cms operating systems 1981 1976 ibm released query example vm platform table-oriented front-end produced linear-syntax language drove transactions relational database later qmf feature db2 produced real sql brought qbe look feel db2 name db2 ibm database 2 first given database management system dbms 1983 ibm released db2 mvs mainframe platform years db2 full-function dbms exclusively available ibm mainframes later ibm brought db2 platforms including os/2 unix ms windows servers linux including linux z systems pdas process occurred 1990s inspiration mainframe version db2 architecture came part ibm ims hierarchical database dedicated database-manipulation language ibm dl/i db2 also embedded i5/os operating system ibm system iseries formerly as/400 versions available z/vse z/vm earlier version code would become db2 luw linux unix windows part extended edition component os/2 called database manager ibm extended functionality database manager number times including addition distributed database functionality means distributed relational database architecture drda allowed shared access database remote location lan note drda based objects protocols defined distributed data management architecture ddm eventually ibm took decision completely rewrite software new version database manager called db2/2 db2/6000 respectively versions db2 different code bases followed '/ naming convention became db2/400 as/400 db2/vse dos/vse environment db2/vm vm operating system ibm lawyers stopped handy naming convention used decided products needed called product platform example db2 os/390 next iteration mainframe server-based products named db2 universal database db2 udb mid-1990s ibm released clustered db2 implementation called db2 parallel edition initially ran aix edition allowed scalability providing shared-nothing architecture single large database partitioned across multiple db2 servers communicate high-speed interconnect db2 edition eventually ported linux unix windows luw platforms renamed db2 extended enterprise edition eee ibm refers product database partitioning feature dpf bundles flagship db2 enterprise product informix corporation acquired illustra made database engine object-sql dbms introducing universal server oracle ibm followed suit changing database engines capable object-relational extensions 2001 ibm bought informix software following years incorporated informix technology db2 product suite db2 technically considered object-sql dbms mid-2006 ibm announced viper codename db2 9 distributed platforms z/os db2 9 z/os announced early 2007 ibm claimed new db2 first relational database store xml natively enhancements include oltp-related improvements distributed platforms business intelligence/data warehousing-related improvements z/os self-tuning self-managing features additional 64-bit exploitation especially virtual storage z/os stored procedure performance enhancements z/os continued convergence sql vocabularies z/os distributed platforms october 2007 ibm announced viper 2 codename db2 9.5 distributed platforms three key themes release simplified management business critical reliability agile xml development june 2009 ibm announced cobra codename db2 9.7 luw db2 9.7 added data compression database indexes temporary tables large objects db2 9.7 also supported native xml data hash partitioning database partitioning range partitioning table partitioning multi-dimensional clustering native xml features allows users directly work xml data warehouse environments db2 9.7 also added several features make easier oracle database users work db2 include support commonly used sql syntax pl/sql syntax scripting syntax data types oracle database db2 9.7 also enhanced concurrency model exhibit behavior familiar users oracle database microsoft sql server october 2009 ibm introduced second major release year announced db2 purescale db2 purescale database cluster solution non-mainframe platforms suitable online transaction processing oltp workloads ibm based design db2 purescale parallel sysplex implementation db2 data sharing mainframe db2 purescale provides fault-tolerant architecture shared-disk storage db2 purescale system grow 128 database servers provides continuous availability automatic load balancing 2009 announced db2 engine mysql allows users system platform natively access db2 ibm operating system formerly called as/400 users platforms access files mysql interface system predecessors as/400 system/38 db2 tightly integrated operating system comes part operating system provides journaling triggers features early 2012 ibm announced next version db2 db2 10.1 code name galileo linux unix windows db2 10.1 contained number new data management capabilities including row column access control enables ‘ fine-grained ’ control database multi-temperature data management moves data cost effective storage based hot cold frequently data accessed data ibm also introduced ‘ adaptive compression ’ capability db2 10.1 new approach compressing data tables june 2013 ibm released db2 10.5 code name kepler 12 april 2016 ibm announced db2 luw 11.1 june 2016 released mid-2017 ibm re-branded db2 dashdb product offerings amended names db2 db2 z/os mainframe available traditional product packaging value unit edition allows customers instead pay one-time charge db2 also powers ibm infosphere warehouse offers data warehouse capabilities infosphere warehouse available z/os includes several bi features etl data mining olap acceleration in-line analytics db2 10.5 linux unix windows contains functionality tools offered prior generation db2 infosphere warehouse linux unix windows ibm provides three cloud services db2 db2 administered either command-line gui command-line interface requires knowledge product easily scripted automated gui multi-platform java client contains variety wizards suitable novice users db2 supports sql xquery db2 native implementation xml data storage xml data stored xml relational data clob data faster access using xquery db2 apis rexx pl/i cobol rpg fortran c++ c delphi .net cli java python perl php ruby many programming languages db2 also supports integration eclipse visual studio integrated development environments purequery ibm data access platform focused applications access data purequery supports java .net purequery provides access data databases in-memory java objects via tools apis runtime environment delivered ibm data studio developer ibm data studio purequery runtime important feature db2 computer programs error handling sql communications area sqlca structure used exclusively within db2 program return error information application program every sql statement executed primary singularly useful error diagnostic held field sqlcode within sqlca block sql return code values later versions db2 added functionality complexity execution sql multiple errors warnings could returned execution sql statement may example initiated database trigger sql statements instead original sqlca error information retrieved successive executions get diagnostics statement see sql return codes comprehensive list common sqlcodes
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Databases
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quadrature-division multiple access quadrature-division multiple access qdma radio protocol term combines two standard terms telecommunications cdma qpsk qdma used local area networks usually wireless short-range wimax cdma qdma especially suitable modern communications example transmission short messages sms mms communication motion cars trains etc establishment unplanned links traditional tdma fdma require lot overhead set link parameter new user detect user left allocation free allocated another cdma qdma new user simply allocated new code ready go may impose slight load spectrum system devised absorb controlled measure collisions continue operations high level quality service
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Internet protocols
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svi-738 spectravideo svi-738 x'press msx1 compatible home computer manufactured spectravideo 1985 although compatible msx 1.0 standard incorporates several extensions standard 80-column display serial rs-232 built-in 3.5 floppy drive many hardware-compatible msx 2.0 standard system whole leading referred msx 1.5 computer along sony hb-101 canon v-8 casio mx-10 hitachi mb-h1 portable computer based msx standard hence title x'press came packaged carrying bag addition manuals booklets software cp/m 2.2 msx-dos 1.0 disk containing special demonstration program featuring astronaut flying screen demonstrating computer graphic capabilitites listing facts computer rom ram sizes along disk drive integrated serial port stood use graphics chip specified msx-2 standard although use 16 kb vram allowed add 80 column mode together bugs first model design konami scc-sound based cartridges work bad sound among reasons msx 1.5 moniker ran microsoft disk basic 1.0 rom turned disk non-autoexecutable disk inserted computer marketed mainly europe australasia middle east poland marketed centralna składnica harcerska price 590 000 polish złotys average salary two months time msx computer marketed poland equipped several schools version svi-738 sold altered keyboard rom order provide polish-specific characters could also found schools finland spain initially distributed indescomp creation spanish subsidiary united kingdom sold £399.95 svi-738 also sold united states
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Computer architecture
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apple a12 apple a12 bionic 64-bit arm-based system chip soc designed apple inc first appeared iphone xs xs max xr 2019 versions ipad air ipad mini two high-performance cores claimed 15 faster 50 energy-efficient apple a11 four high-efficiency cores claimed use 50 less power energy-efficient cores a11 a12 features apple-designed 64-bit armv8.3-a six-core cpu two high-performance cores running 2.49 ghz called vortex four energy-efficient cores called tempest vortex cores 7-wide decode out-of-order superscalar design tempest cores 3-wide decode out-of-order superscalar design like mistral cores tempest cores based apple swift cores apple a6 a12 also integrates apple-designed four-core graphics processing unit gpu 50 faster graphics performance a11 a12 includes dedicated neural network hardware apple calls next-generation neural engine neural network hardware eight cores perform 5 trillion 8-bit operations per second unlike a11 neural engine third party apps access a12 neural engine a12 manufactured tsmc using 7 nm finfet process first ship consumer product contains 6.9 billion transistors die size a12 83.27 mm 5 smaller a11 manufactured package package pop together 4 gib lpddr4x memory iphone xs xs max 3 gb lpddr4x memory iphone xr ipad air 2019 ipad mini 2019 armv8.3 instruction set supports brings significant security improvement form pointer authentication mitigates exploitation techniques involving memory corruption jump-oriented-programming return-oriented-programming
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Computer architecture
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ideapad tablets ideapad tablets lenovo brand consumer-oriented tablet computers designed home use entertainment opposed business-focused thinkpad tablet series devices sold certain countries china india new zealand sold lepad brand similar lephone series smartphones ideapad-branded tablets produced android windows operating systems ideapad brand gradually phased recent years replaced general tab brand android devices miix brand windows devices exception several distinctive hardware lines yoga series yoga tablet 2 pro 13-inch tablet built-in projector 9,600 mah battery lenovo claims last 15 hours continuous use display resolution 2,560 pixels 1,440 pixels 32 gigabytes built-in storage come standard expanded 64 gigabytes microsd card yoga tablet 2 pro like previous yoga tablets thin body thick cylindrical base thick base designed make holding device portrait mode comfortable device projector mounted projector resolution 854 pixels 480 pixels sound provided stereo speakers subwoofer but-in base lenovo a10 tablet 10.1-inch tablet computer runs android lenovo ideatab lynx released united states december 2012 lynx tablet sold 599 accutype keyboard base priced 149 lynx 11.6-inch tablet lynx without dock 11.85 inches 7.4 inches 0.37 inches weighs 1.41 pounds approximately weight thickness third generation apple ipad keyboard dock weighs 1.45 pounds total 2.86 pounds lynx runs full-version windows 8 opposed windows rt lynx uses 1.8 ghz dual-core clovertrail intel atom z2760 processor 2gb memory either 32gb 64gb emmc flash storage 11.6-inch in-plane switching display resolution 1,366 x 768 resolution supports five-point capacitive multitouch micro-usb micro-hdmi ports microsd card slot lynx table keyboard dock two standard usb 2.0 ports lynx also bluetooth 4.0 802.11b/g/n wi-fi networking stereo speakers dual microphones 2-megapixel front-facing webcam review lynx cnet wrote real question lynx stand one answer might weight despite 11.6-inch screen tablet felt shockingly light held lenovo launch event although lenovo says 1.44 pounds lynx tablet portion closer feel kindle ipad larger display either keyboard dock takes away lynx airiness course although two least feel solidly linked use together latch secure n't worry accidentally dislodging screen also happy responsiveness lynx touchscreen although n't get chance really challenge five minute hands-on ideapad k2 ideapad k2010 1920x1200 pixel 10.1-inch ips panel tablet tegra 3 running 1.7 ghz possibly overclocked 2gb ram fingerprint scanner keyboard dock known lepad k2 lepad k2010 china ideapad k2 meant high-end gamers business users lenovo displayed tablet new product showcase india ideatab a1 1024x600 7-inch display tablet android 2.3 4.0 ideatab s2109 1024 x 768 pixels 4:3 aspect ratio 9.7-inch ips display omap 4430 soc dual core arm cortex a9 1 ghz sgx540 powervr gpu 1gb ram 3 versions 8 16 32 gb included storage capacity android 4.0 ideatab s2110 10.1-inch ips display tablet using qualcomm 1.5 ghz soc 1gb ram android 4.0 three tablets announced lenovo ideapad tablet line 2011 ideapad k1 a1 p1 ideapad k1 tablet announced july 2011 ideapad k1 tablet offered following specifications 30 free apps pre-loaded ideapad including angry birds hd kindle android documents go norton mobile security review gizmodo appreciated value ideapad k1 represented offer 32gb tablet 499 reviewer described tablet one attractive gizmodo reviewed “ matte chrome-colored side back trim deep red back panel ” ideapad k1 tablet featured interface improvements compared android 3.1 tablets gizmodo indicated battery life average android tablets 8 hours 3 minutes despite continuous web surfing wi-fi ideapad k1 summarized laptop magazine offering “ strong mix style performance uniquely compelling enhancements android 3.1 ui ” ideapad a1 tablet announced september 2011 pcworld review indicated a1 would first 7-inch tablet prices 200 less reviewer stated low price achieved reduction storage capacity functionality basic unit offered 2gb internal storage variants storage would made available a1 contained micro sd card slot allowed expansion 32gb a1 tablet powered single-core 1 ghz cortex a8 processor suggested reviewer single-core cpu may reason honeycomb board may explain lenovo achieve aggressive price feature indicated notable tablet price capacitive touch screen contrast resistive touch screen found value tablets display also offered higher-than average resolution 1024x600 pixels 170 pixels per inch ppi ppi value made display sharper even apple ipad 2 offered 132 ppi 9.7-inch screen fact a1 included android 2.3 gingerbread opposed android 3.2 honeycomb indicated point concern reviewer said companies incorporate android 2.2 2.3 achieved making significant customizations on-board apps well interface time announcement lenovo provided information customizations made ideapad a1 tablet 0.47 inches thin weighed 0.88 lbs a1 offered four different colors white black pink light blue feature a1 announced lenovo inclusion magnesium alloy roll cage protected internal components bumpers another key feature a1 gps require data connection used ideapad p1 tablet different ideapad k1 thinkpad tablets featured windows 7 operating system instead android 3.1 additionally unlike k1 thinkpad tablets p1 tablet included intel atom processor opposed nvidia tegra processor lenovo ideapad p1 windows tablet also preloaded adobe flash player 10.3 lenovo app shop microsoft security essentials lenovo app manager switch entertainment productivity apps like send email games watch online movies specifications ideapad p1 follows
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Operating systems
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versive versive machine learning startup based seattle washington us founded 2012 stephen purpura chris metcalfe company sells on-premises software cloud services professional service solutions help businesses automate human expertise september 2014 versive raised 42 million total investment company changed name context relevant versive 2017 october 2018 versive acquired esentire versive developed platform ingests data determines important creates problem-specific solution deployed continually learning proprietary high-performance machine learning technology accelerates deployment machine learning solutions problem-specific applications provide out-of-the-box experience reduces workload users building complicated models deployment options include public private clouds traditional servers hadoop clusters scale-out in-memory technology allows smart caching small huge datasets using computers parallelize efforts needed versive software applied various industries including finance information gathered technology aims help clients predict activity based observed trends technology used help security teams detect advanced cyber threats best emerging security product interop may 2017 useful calculating prices risks high speed system also detect fraud quickly versive launched 1.3 million seed funding madrona venture group seattle-based angel investor geoff entress initial investors included mike mcsherry cliff kushler mark illing swype/nuance startup received additional 1.5 million funding madrona november 2012 july 2013 versive raised total 7 million round series funding round included previous investors madrona entress well vulcan capital bloomberg beta may june september 2014 versive raised additional 35 million total investment three chunks goldman sachs bank america merrill lynch bloomberg beta new york life formation 8 madrona work-bench seattle angel investors versive partnered good harbor security risk management company founded richard a. clarke counterterrorism expert former cyber-security adviser bush administration clarke sits versive advisory board company helps versive repair security breaches ensure security compliance among services may 2014 versive named databeat innovation showdown april 2014 versive nominated pacific northwest startup year geekwire november 2013 versive selected geekwire collaboration museum history industry mohai bezos center innovation one seattle 10 recognizes promising young start-up companies within seattle region context relevant along nine companies recognized geekwire gala 4 december 2013 also unveiled sketch business concept giant-sized cocktail napkins
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Distributed computing architecture
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recordset recordset data structure consists group database records either come base table result query table concept common number platforms notably microsoft data access objects dao activex data objects ado recordset object contains fields collection properties collection time recordset object refers single record within set current record
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Databases
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computer security institute computer security institute csi professional membership organization serving practitioners information network computer-enabled physical security level system administrator chief information security officer founded 1974 csi used conduct two conferences per year — annual computer security conference exhibition csi sx internet entrepreneur jimmy wales keynote speaker csi ’ annual conference held november 6–8 2006 orlando florida csi perhaps best known annual csi/fbi computer crime security survey began conduct 1996 collaboration san francisco federal bureau investigation computer intrusion squad researchers robert h. smith school business university maryland fbi disappeared title study 2006 2007 reports 15th annual survey turned last released 2011 available general public information week csi staff including richard power testified expert witnesses united states senate committee hearings 2011 csi absorbed ubm although mention appears ubm wikipedia page september 2014 original csi website returns 404 file found error snapshots website found wayback time machine
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Computer security
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relational calculus relational calculus consists two calculi tuple relational calculus domain relational calculus part relational model databases provide declarative way specify database queries contrast relational algebra also part relational model provides procedural way specifying queries relational algebra might suggest steps retrieve phone numbers names book stores supply sample book relational calculus would formulate descriptive declarative way relational algebra relational calculus essentially logically equivalent algebraic expression equivalent expression calculus vice versa result known codd theorem
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Databases
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genesi genesi international group technology consulting companies united states mexico germany widely known designing manufacturing arm architecture power isa computing devices genesi group consists genesi usa inc. genesi americas llc genesi europe ug red efika bplan gmbh affiliated non-profit organization power2people genesi official linaro partner software development team instrumental moving linux arm architecture towards wider adoption hard-float application binary interface incompatible existing applications provides enormous performance gains many use cases main products genesi arm-based computers designed inexpensive quiet highly energy efficient custom open firmware compliant firmware products run multitude operating systems genesi designed maintains powerdeveloper online platform genesi products arm products manufacturers via powerdeveloper projects programs hundreds systems provided powerdeveloper community far thereby supporting open source development many countries linux distributions directly benefited programs include limited crux debian raspbian fedora gentoo opensuse ubuntu genesi funded development morphos operating system shifted focus towards linux 2004 however genesi remains main supporter operating system continues actively support user developer communities via morphzone social platform features discussion forums digital library software repository bounty system
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Computer architecture
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leonard h. tower jr. leonard len h. tower jr. born june 17 1949 free software activist one founding board members free software foundation contributed initial releases gcc gnu diff left free software foundation 1997 tower born june 17 1949 astoria queens new york city u.s 1971 tower received sb biology massachusetts institute technology time business manager tech student newspaper fsf first full-time paid employee tower mostly performed administrative tasks including managing mailing lists newsgroups requests information 1986 tower assisted richard stallman stallman initial plan base c compiler gnu project pastel compiler stallman obtained lawrence livermore lab tower worked rewriting existing code pastel variation pascal c stallman worked building new c front end stallman dropped plan discovered livermore compiler required much memory concluding would write new compiler scratch new compiler known gcc none pastel compiler used managed adapt use c front end written stallman released new gnu c compiler march 22 1987 acknowledging others contributions including tower wrote parts parser rtl generator rtl definitions vax machine description based ideas contributed jack davidson christopher fraser along mike haertel david hayes stallman tower also one initial co-authors gnu diff file comparison utility based published algorithm eugene myers late 1980s early 1990s tower spoke usenix conferences representative fsf tower early member league programming freedom 1991 tower one organization two active speakers along richard stallman
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Operating systems
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gervase markham programmer gervase markham 21 june 1978 – 27 july 2018 british software engineer mozilla foundation lead developer bugzilla started contributing mozilla project 1999 became youngest paid employee mozilla.org age 23 graduated oxford university markham named paternal grandfather canon gervase markham 1910–2007 squire vicar morland near penrith related 16th-century poet writer gervase markham according times obituary elder gervase markham descendant william markham archbishop york 1710–1807 2006 google-o'reilly open source award best community activist also presented fosdem conference several years mozilla foundation activities bugzilla markham born-again christian undergoing treatment metastatic adenoid cystic carcinoma wrote relationship saw died 27 july 2018 long battle cancer
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Computer security
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cint cint command line c/c++ interpreter included object oriented data analysis package root although intended use faculties root cint also used standalone addition another program requires interpreter cint interpreted version c/c++ much way beanshell interpreted version java addition language interpreter offers certain bash-like shell features history tab-completion accomplish latter relies heavily reflection support built root user classes follow interfaces may also take advantage features language interpreted cint actually something hybrid c c++ covering 95 ansi c 85 c++ syntax however bit forgiving either language example operator codice_1 replaced codice_2 optional warning addition statements command line need end semi-colon although necessary statements macros cern switched cling c++ interpreter cint distributed standalone author cint latest home page
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Programming language topics
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wireguard wireguard free open-source software application communication protocol implements virtual private network vpn techniques create secure point-to-point connections routed bridged configurations run module inside linux kernel aims better performance ipsec openvpn tunneling protocols wireguard aims provide vpn simple highly effective review arstechnica observed popular vpn technologies openvpn ipsec often complex set disconnect easily absence configuration take substantial time negotiate reconnections may use outdated ciphers relatively massive code 400,000 600,000 lines code two examples given makes harder find bugs wireguard design seeks reduce issues making tunnel secure easier manage default using versioning cryptography packages focuses ciphers believed among secure current encryption methods also codebase around 4000 lines 1 either openvpn ipsec making security audits easier ars technica reported testing stable tunnels easy create wireguard compared alternatives commented would hard go back long reconnection delays compared wireguard nonsense instant reconnections wireguard utilizes curve25519 key exchange chacha20 encryption poly1305 data authentication siphash hashtable keys blake2s hashing supports layer 3 ipv4 ipv6 encapsulate v4-in-v6 vice versa written jason a. donenfeld published second version gnu general public license gpl may 2019 researchers inria published machine-checked proof protocol produced using cryptoverif proof assistant two early adopters wireguard vpn service providers mullvad azirevpn wireguard received donations mullvad private internet access nlnet foundation december 18 2018 protonmail protonvpn advocated continued research development wireguard technology indicating intent raise financial support oregon senator ron wyden recommended national institute standards technology nist evaluate wireguard replacement existing technologies like ipsec openvpn implementations wireguard protocol include
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Computer security
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sunway processor sunway shenwei chinese series computer microprocessors developed jiāngnán computing lab wuxi china uses reduced instruction set computing risc architecture details still sparse sunway series microprocessors developed mainly use military people republic china expressed online forums original microarchitecture believed inspired dec alpha sw-3 thought especially based alpha 21164 jack dongarra states follow-on sw26010 shenwei-64 instruction set related dec alpha instruction set n't say new instruction set three prior generations names although precise details instruction set unknown
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Computer architecture
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computer cooling computer cooling required remove waste heat produced computer components keep components within permissible operating temperature limits components susceptible temporary malfunction permanent failure overheated include integrated circuits central processing units cpus chipset graphics cards hard disk drives components often designed generate little heat possible computers operating systems may designed reduce power consumption consequent heating according workload heat may still produced removed without attention cooling use heatsinks cooled airflow reduces temperature rise produced given amount heat attention patterns airflow prevent development hotspots computer fans widely used along heatsink fans reduce temperature actively exhausting hot air also exotic cooling techniques liquid cooling modern day processors designed cut reduce voltage clock speed internal temperature processor exceeds specified limit cooling may designed reduce ambient temperature within case computer exhausting hot air cool single component small area spot cooling components commonly individually cooled include cpu graphics processing unit gpu northbridge integrated circuits e.g. cpu gpu main generators heat modern computers heat generation reduced efficient design selection operating parameters voltage frequency ultimately acceptable performance often achieved managing significant heat generation operation temperature computer components rise heat transferred surroundings equal heat produced component thermal equilibrium reached reliable operation temperature must never exceed specified maximum permissible value unique component semiconductors instantaneous junction temperature rather component case heatsink ambient temperature critical cooling changed high temperatures significantly reduce life span cause permanent damage components heat output components sometimes exceed computer cooling capacity manufacturers often take additional precautions ensure temperatures remain within safe limits computer thermal sensors integrated cpu motherboard chipset gpu shut high temperatures detected prevent permanent damage although may completely guarantee long-term safe operation overheating component reaches point may throttled temperatures fall safe point using dynamic frequency scaling technology throttling reduces operating frequency voltage integrated circuit disables non-essential features chip reduce heat output often cost slightly significantly reduced performance desktop notebook computers throttling often controlled bios level throttling also commonly used manage temperatures smartphones tablets components packed tightly together little active cooling additional heat transferred hand user electronic computers became larger complex cooling active components became critical factor reliable operation early vacuum-tube computers relatively large cabinets could rely natural forced air circulation cooling however solid state devices packed much densely lower allowable operating temperatures starting 1965 ibm manufacturers mainframe computers sponsored intensive research physics cooling densely packed integrated circuits many air liquid cooling systems devised investigated using methods natural forced convection direct air impingement direct liquid immersion forced convection pool boiling falling films flow boiling liquid jet impingement mathematical analysis used predict temperature rises components possible cooling system geometry ibm developed three generations thermal conduction module tcm used water-cooled cold plate direct thermal contact integrated circuit packages package thermally conductive pin pressed onto helium gas surrounded chips heat conducting pins design could remove 27 watts chip 2000 watts per module maintaining chip package temperatures around systems using tcms 3081 family 1980 es/3090 1984 models es/9000 1990 ibm 3081 processor tcms allowed 2700 watts single printed circuit board maintaining chip temperature thermal conduction modules using water cooling also used mainframe systems manufactured companies including mitsubishi fujitsu cray-1 supercomputer designed 1976 distinctive cooling system machine height diameter consumed 115 kilowatts comparable average power consumption dozen western homes medium-sized car integrated circuits used machine fastest available time using emitter-coupled logic however speed accompanied high power consumption compared later cmos devices heat removal critical refrigerant circulated piping embedded vertical cooling bars twelve columnar sections machine 1662 printed circuit modules machine copper core clamped cooling bar system designed maintain cases integrated circuits refrigerant circulating final heat rejection water-cooled condenser piping heat exchangers pumps cooling system arranged upholstered bench seat around outside base computer 20 percent machine weight operation refrigerant later cray-2 densely packed modules seymour cray trouble effectively cooling machine using metal conduction technique mechanical refrigeration switched 'liquid immersion cooling method involved filling chassis cray-2 liquid called fluorinert fluorinert name implies inert liquid interfere operation electronic components components came operating temperature heat would dissipate fluorinert pumped machine chilled water heat exchanger performance per watt modern systems greatly improved many computations carried given power consumption possible integrated circuits 1980s 1990s recent supercomputer projects blue gene rely air cooling reduces cost complexity size systems compared liquid cooling fans used natural convection insufficient remove heat fans may fitted computer case attached cpus gpus chipset psu hard drives cards plugged expansion slot common fan sizes include 40 60 80 92 120 140 mm 200 230 250 300 mm fans sometimes used high-performance personal computers computer certain resistance air flowing chassis components sum smaller impediments air flow inlet outlet openings air filters internal chassis electronic components fans simple air pumps provide pressure air inlet side relative output side pressure difference moves air chassis air flowing areas lower pressure fans generally two published specifications free air flow maximum differential pressure free air flow amount air fan move zero back-pressure maximum differential pressure amount pressure fan generate completely blocked two extremes series corresponding measurements flow versus pressure usually presented graph fan model unique curve like dashed curves adjacent illustration fans installed parallel series combination parallel installation would fans mounted side side series installation would second fan line another fan inlet fan exhaust fan simplify discussion assumed fans model parallel fans provide double free air flow additional driving pressure series installation hand double available static pressure increase free air flow rate adjacent illustration shows single fan versus two fans parallel maximum pressure water doubled flow rate note air flow changes square root pressure thus doubling pressure increase flow 1.41 times twice might assumed another way looking pressure must go factor four double flow rate determine flow rate chassis chassis impedance curve measured imposing arbitrary pressure inlet chassis measuring flow chassis requires fairly sophisticated equipment chassis impedance curve represented solid red black lines adjacent curve determined actual flow chassis generated particular fan configuration graphically shown chassis impedance curve crosses fan curve slope chassis impedance curve square root function doubling flow rate required four times differential pressure particular example adding second fan provided marginal improvement flow configurations approximately shown plot second fan series would provide slightly better performance parallel installation equation required airflow chassis formula_1 simple conservative rule thumb cooling flow requirements discounting effects heat loss chassis walls laminar versus turbulent flow accounting constants specific heat density sea level formula_2 formula_3 example typical chassis 500 watts load maximum internal temperature environment i.e difference formula_4 would actual flow chassis free air rating fan dual piezo cooling jet patented ge uses vibrations pump air device initial device three millimeters thick consists two nickel discs connected either side sliver piezoelectric ceramics alternating current passed ceramic component causes expand contract 150 times per second nickel discs act like bellows contracted edges discs pushed together suck hot air expanding brings nickel discs together expelling air high velocity device bearings require motor thinner consumes less energy typical fans jet move amount air cooling fan twice size consuming half much electricity lower cost passive heat-sink cooling involves attaching block machined extruded metal part needs cooling thermal adhesive may used commonly personal-computer cpu clamp holds heat sink directly chip thermal grease thermal pad spread block fins ridges increase surface area heat conductivity metal much better air radiates heat better component protecting usually integrated circuit cpu fan-cooled aluminium heat sinks originally norm desktop computers nowadays many heat sinks feature copper base-plates entirely made copper dust buildup metal fins heat sink gradually reduces efficiency countered gas duster blowing away dust along unwanted excess material passive heat sinks commonly found older cpus parts get hot chipset low-power computers usually heat sink attached integrated heat spreader ihs essentially large flat plate attached cpu conduction paste layered dissipates spreads heat locally unlike heat sink spreader meant redistribute heat remove addition ihs protects fragile cpu passive cooling involves fan noise convection forces move air heatsink another growing trend due increasing heat density computer gpu fpga asics immerse entire computer select components thermally electrically conductive liquid although rarely used cooling personal computers liquid immersion routine method cooling large power distribution components transformers also becoming popular data centers personal computers cooled manner may require either fans pumps may cooled exclusively passive heat exchange computer hardware enclosure placed heat exchanger i.e heater core radiator might still needed though piping also needs placed correctly coolant used must sufficiently low electrical conductivity interfere normal operation computer liquid somewhat electrically conductive may cause electrical shorts components traces permanently damage reasons preferred liquid insulator dielectric conduct electricity wide variety liquids exist purpose including transformer oils synthetic single-phase dielectric coolants engineered fluids electrocool l 2-phase coolants 3m fluorinert non-purpose oils including cooking motor silicone oils successfully used cooling personal computers fluids used immersion cooling especially hydrocarbon based materials mineral oils cooking oils organic esters may degrade common materials used computers rubbers pvc thermal greases therefore critical review material compatibility fluids prior use mineral oil particular found negative effects pvc rubber-based wire insulation thermal pastes used transfer heat heat sinks processors graphic cards reported dissolve liquids however negligible impact cooling unless components removed operated air evaporation especially 2-phase coolants pose problem liquid may require either regularly refilled sealed inside computer enclosure powerful computers many features required less powerful computers ones fewer features used via epia motherboard cpu typically dissipates approximately 25 watts heat whereas capable pentium 4 motherboard cpu typically dissipates around 140 watts computers powered direct current external power supply brick generate heat inside computer case replacement cathode ray tube crt displays efficient thin-screen liquid crystal display lcd ones early twenty-first century reduces power consumption significantly component may fitted good thermal contact heatsink passive device large thermal capacity large surface area relative volume heatsinks usually made metal high thermal conductivity aluminium copper incorporate fins increase surface area heat relatively small component transferred larger heatsink equilibrium temperature component plus heatsink much lower component alone would heat carried away heatsink convective fan-forced airflow fan cooling often used cool processors graphics cards consume significant amounts electrical energy computer typical heat-generating component may manufactured flat surface block metal corresponding flat surface finned construction sometimes attached fan clamped component fill poorly conducting air gaps due imperfectly flat smooth surfaces thin layer thermal grease thermal pad thermal adhesive may placed component heatsink heat removed heat-sink convection extent radiation possibly conduction heat-sink thermal contact say metal case inexpensive fan-cooled aluminium heat sinks often used standard desktop computers heat-sinks copper base-plates made copper better thermal characteristics aluminium copper heat-sink effective aluminium unit size relevant regard high-power-consumption components used high-performance computers passive heat sinks commonly found older cpus parts dissipate much power chipset computers low-power processors equipment silent operation critical fan noise unacceptable usually heat-sink clamped integrated heat spreader ihs flat metal plate size cpu package part cpu assembly spreads heat locally thin layer thermal compound placed compensate surface imperfections spreader primary purpose redistribute heat heat-sink fins improve efficiency several brands ddr2 ddr3 ddr4 upcoming ddr5 dram memory modules fitted finned heatsink clipped onto top edge module technique used video cards use finned passive heatsink gpu dust tends build crevices finned heatsinks particularly high airflow produced fans keeps air away hot component reducing cooling effectiveness however removing dust restores effectiveness peltier junctions generally around 10-15 efficient ideal refrigerator carnot cycle compared 40–60 achieved conventional compression cycle systems reverse rankine systems using compression/expansion due lower efficiency thermoelectric cooling generally used environments solid state nature moving parts low maintenance compact size orientation insensitivity outweighs pure efficiency modern tecs use several stacked units composed dozens hundreds thermocouples laid next allows substantial amount heat transfer combination bismuth tellurium commonly used thermocouples active heat pumps consume power tecs produce temperatures ambient impossible passive heatsinks radiator-cooled liquid cooling heatpipe hsfs however pumping heat peltier module typically consume electric power heat amount pumped liquid cooling highly effective method removing excess heat common heat transfer fluid desktop pcs distilled water advantages water cooling air cooling include water higher specific heat capacity thermal conductivity principle used typical active liquid cooling system computers identical used automobile internal combustion engine water circulated water pump waterblock mounted cpu sometimes additional components gpu northbridge heat exchanger typically radiator radiator usually cooled additionally means fan besides fan could possibly also cooled means peltier cooler although peltier elements commonly placed directly top hardware cooled coolant used conduct heat away hot side peltier element coolant reservoir often also connected system besides active liquid cooling systems passive liquid cooling systems also sometimes used systems often discard fan water pump hence theoretically increasing reliability system and/or making quieter active systems downsides systems however much less efficient discarding heat thus also need much coolant -and thus much bigger coolant reservoir- giving time coolant cool liquids allow transfer heat parts cooled air making liquid cooling suitable overclocking high performance computer applications compared air cooling liquid cooling also influenced less ambient temperature liquid cooling comparatively low noise-level compares favorably active cooling become quite noisy disadvantages liquid cooling include complexity potential coolant leak leaked water importantly additives added water damage electronic components comes contact need test repair leaks makes complex less reliable installations notably first major foray field liquid-cooled personal computers general use high-end versions apple power mac g5 ultimately doomed propensity coolant leaks. ref name= powermac g5 coolant leaks/repairs /ref air-cooled heat sink generally much simpler build install maintain water cooling solution although cpu-specific water cooling kits also found may easy install air cooler limited cpus however liquid cooling gpu cards also possible originally limited mainframe computers liquid cooling become practice largely associated overclocking form either manufactured kits form do-it-yourself setups assembled individually gathered parts past years seen increase popularity liquid cooling pre-assembled moderate high performance desktop computers sealed closed-loop systems incorporating small pre-filled radiator fan waterblock simplify installation maintenance water cooling slight cost cooling effectiveness relative larger complex setups liquid cooling typically combined air cooling using liquid cooling hottest components cpus gpus retaining simpler cheaper air cooling less demanding components ibm aquasar system uses hot water cooling achieve energy efficiency water used heat buildings well since 2011 effectiveness water cooling prompted series all-in-one aio water cooling solutions aio solutions result much simpler install unit units reviewed positively review sites heat pipe hollow tube containing heat transfer liquid liquid absorbs heat evaporates one end pipe vapor travels cooler end tube condenses giving latent heat liquid returns hot end tube gravity capillary action repeats cycle heat pipes much higher effective thermal conductivity solid materials use computers heat sink cpu attached larger radiator heat sink heat sinks hollow attachment creating one large heat pipe transfers heat cpu radiator cooled using conventional method method expensive usually used space tight small form-factor pcs laptops fan noise tolerated audio production efficiency method cooling many desktop cpus gpus well high end chipsets use heat pipes addition active fan-based cooling remain within safe operating temperatures cooling technology development kronos thorn micro technologies employs device called ionic wind pump also known electrostatic fluid accelerator basic operating principle ionic wind pump corona discharge electrical discharge near charged conductor caused ionization surrounding air corona discharge cooler developed kronos works following manner high electric field created tip cathode placed one side cpu high energy potential causes oxygen nitrogen molecules air become ionized positively charged create corona halo charged particles placing grounded anode opposite end cpu causes charged ions corona accelerate towards anode colliding neutral air molecules way collisions momentum transferred ionized gas neutral air molecules resulting movement gas towards anode advantages corona-based cooler lack moving parts thereby eliminating certain reliability issues operating near-zero noise level moderate energy consumption soft cooling practice utilizing software take advantage cpu power saving technologies minimize energy use done using halt instructions turn put standby state cpu subparts n't used underclocking cpu resulting lower total speeds useful overclocking cpu improve user experience rather increase raw processing power since prevent need noisier cooling contrary term suggests form cooling reducing heat creation undervolting practice running cpu component voltages device specifications undervolted component draws less power thus produces less heat ability varies manufacturer product line even different production runs product well components system processors often specified use voltages higher strictly necessary tolerance ensures processor higher chance performing correctly sub-optimal conditions lower-quality motherboard low power supply voltages certain limit processor function correctly although undervolting far typically lead permanent hardware damage unlike overvolting undervolting used quiet systems less cooling needed reduction heat production allowing noisy fans omitted also used battery charge life must maximized conventional cooling techniques attach cooling component outside computer chip package attaching technique always exhibit thermal resistance reducing effectiveness heat efficiently quickly removed directly cooling local hot spots chip within package locations power dissipation 300 w/cm typical cpu less 100 w/cm occur although future systems expected exceed 1000 w/cm form local cooling essential developing high power density chips ideology led investigation integrating cooling elements computer chip currently two techniques micro-channel heat sinks jet impingement cooling micro-channel heat sinks channels fabricated silicon chip cpu coolant pumped channels designed large surface area results large heat transfers heat dissipation 3000 w/cm reported technique heat dissipation increased two-phase flow cooling applied unfortunately system requires large pressure drops due small channels heat flux lower dielectric coolants used electronic cooling another local chip cooling technique jet impingement cooling technique coolant flown small orifice form jet jet directed toward surface cpu chip effectively remove large heat fluxes heat dissipation 1000 w/cm reported system operated lower pressure comparison micro-channel method heat transfer increased using two-phase flow cooling integrating return flow channels hybrid micro-channel heat sinks jet impingement cooling phase-change cooling extremely effective way cool processor vapor compression phase-change cooler unit usually sits underneath pc tube leading processor inside unit compressor type air conditioner compressor compresses gas mixture gases comes evaporator cpu cooler discussed hot high pressure vapor pushed condenser heat dissipation device condenses hot gas liquid typically subcooled exit condenser liquid fed expansion device restriction system cause drop pressure vaporize fluid cause reach pressure boil desired temperature expansion device used simple capillary tube elaborate thermal expansion valve liquid evaporates changing phase absorbing heat processor draws extra energy environment accommodate change see latent heat evaporation produce temperatures reaching around liquid flow evaporator boiling cooling cpu turning vapor low pressure end evaporator gas flows compressor cycle begins way processor cooled temperatures ranging depending load wattage processor refrigeration system see refrigeration gas mixture used type system suffers number issues cost weight size vibration maintenance cost electricity noise need specialized computer tower mainly one must concerned dew point proper insulation sub-ambient surfaces must done pipes sweat dripping water sensitive electronics alternately new breed cooling system developed inserting pump thermosiphon loop adds another degree flexibility design engineer heat effectively transported away heat source either reclaimed dissipated ambient junction temperature tuned adjusting system pressure higher pressure equals higher fluid saturation temperatures allows smaller condensers smaller fans and/or effective dissipation heat high ambient temperature environment systems essence next generation fluid cooling paradigm approximately 10 times efficient single phase water since system uses dielectric heat transport medium leaks cause catastrophic failure electric system type cooling seen extreme way cool components since units relatively expensive compared average desktop also generate significant amount noise since essentially refrigerators however compressor choice air cooling system main determinant allowing flexibility noise reduction based parts chosen liquid nitrogen boils far freezing point water valuable extreme coolant short overclocking sessions typical installation liquid nitrogen cooling copper aluminum pipe mounted top processor graphics card system heavily insulated condensation liquid nitrogen poured pipe resulting temperatures well evaporation devices ranging cut heat sinks pipes attached custom milled copper containers used hold nitrogen well prevent large temperature changes however nitrogen evaporates refilled realm personal computers method cooling seldom used contexts overclocking trial-runs record-setting attempts cpu usually expire within relatively short period time due temperature stress caused changes internal temperature although liquid nitrogen non-flammable condense oxygen directly air mixtures liquid oxygen flammable materials dangerously explosive liquid nitrogen cooling generally used processor benchmarking due fact continuous usage may cause permanent damage one parts computer handled careless way even harm user liquid helium colder liquid nitrogen also used cooling liquid helium boils temperatures ranging measured heatsink however liquid helium expensive difficult store use liquid nitrogen also extremely low temperatures cause integrated circuits stop functioning silicon-based semiconductors example freeze around cooling improved several techniques may involve additional expense effort techniques often used particular run parts computer cpu gpu higher voltages frequencies specified manufacturer overclocking increases heat generation installation higher performance non-stock cooling may also considered modding many overclockers simply buy efficient often expensive fan heat sink combinations others resort exotic ways computer cooling liquid cooling peltier effect heatpumps heat pipe phase change cooling also related practices positive impact reducing system temperatures often called thermal interface material tim e.g intel perfectly flat surfaces contact give optimal cooling perfect flatness absence microscopic air gaps practically possible particularly mass-produced equipment thin skim thermal compound much thermally conductive air though much less metal improve thermal contact cooling filling air gaps small amount compound sufficient fill gaps used best temperature reduction obtained much debate merits compounds overclockers often consider compounds superior others main consideration use minimal amount thermal compound required even surfaces thermal conductivity compound typically 1/3 1/400 metal though much better air conductivity heatsink compound ranges 0.5 80w/mk see articles aluminium 200 air 0.02 heat-conductive pads also used often fitted manufacturers heatsinks less effective properly applied thermal compound simpler apply fixed heatsink omitted users unaware importance good thermal contact replaced thick ineffective layer compound unlike techniques discussed use thermal compound padding almost universal dissipating significant amounts heat mass-produced cpu heat spreaders heatsink bases never perfectly flat smooth surfaces placed best contact possible air gaps reduce heat conduction easily mitigated use thermal compound best possible results surfaces must flat possible achieved laborious process known lapping reduce cpu temperature typically older pcs use flat ribbon cables connect storage drives ide scsi large flat cables greatly impede airflow causing drag turbulence overclockers modders often replace rounded cables conductive wires bunched together tightly reduce surface area theoretically parallel strands conductors ribbon cable serve reduce crosstalk signal carrying conductors inducing signals nearby conductors empirical evidence rounding cables reducing performance may length cable short enough effect crosstalk negligible problems usually arise cable electromagnetically protected length considerable frequent occurrence older network cables computer cables cable tied chassis cables increase airflow less problem new computers use serial ata much narrower cable colder cooling medium air effective cooling cooling air temperature improved guidelines fewer fans strategically placed improve airflow internally within pc thus lower overall internal case temperature relation ambient conditions use larger fans also improves efficiency lowers amount waste heat along amount noise generated fans operation little agreement effectiveness different fan placement configurations little way systematic testing done rectangular pc atx case fan front fan rear one top found suitable configuration however amd somewhat outdated system cooling guidelines notes front cooling fan seem essential fact extreme situations testing showed fans recirculating hot air rather introducing cool air may fans side panels could similar detrimental effect—possibly disrupting normal air flow case however unconfirmed probably varies configuration desktop computers typically use one fans cooling almost desktop power supplies least one built-in fan power supplies never draw heated air within case results higher psu operating temperatures decrease psu energy efficiency reliability overall ability provide steady supply power computer internal components reason modern atx cases exceptions found ultra-low-budget cases feature power supply mount bottom dedicated psu air intake often filter beneath mounting location allowing psu draw cool air beneath case manufacturers recommend bringing cool fresh air bottom front case exhausting warm air top rear fans fitted force air case effectively removed pressure inside becomes higher outside referred positive airflow opposite case called negative airflow worth noting positive internal pressure prevents dust accumulating case air intakes equipped dust filters case negative internal pressure suffer higher rate dust accumulation even intakes filtered negative pressure draw dust available opening case air flow inside typical desktop case usually strong enough passive cpu heatsink desktop heat sinks active including one even multiple directly attached fans blowers server cooling fans 1 u enclosures usually located middle enclosure hard drives front passive cpu heat sinks rear larger higher enclosures also exhaust fans approximately 4u may active heat sinks power supplies generally rear-facing exhaust fans data centers typically contain many racks thin horizontally mounted 1u servers air drawn front rack exhausted rear data centers typically contain large numbers computers power-dissipating devices risk equipment overheating extensive hvac systems used prevent often raised floor used area floor may used large plenum cooled air power cabling another way accommodating large numbers systems small space use blade chassis oriented vertically rather horizontally facilitate convection air heated hot components tends rise creating natural air flow along boards stack effect cooling manufacturers take advantage effect laptops present difficult mechanical airflow design power dissipation cooling challenge constraints specific laptops include device whole light possible form factor built around standard keyboard layout users close noise must kept minimum case exterior temperature must kept low enough used lap cooling generally uses forced air cooling heat pipes use metal chassis case passive heat sink also common solutions reduce heat include using lower power-consumption arm intel atom processors mobile devices usually discrete cooling systems mobile cpu gpu chips designed maximum power efficiency due constraints device battery higher performance devices may include heat spreader aids transferring heat external case phone tablet
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Computer architecture
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research language computation research language computation quarterly peer-reviewed academic journal covering research computational linguistics natural language processing established 2003 ceased publication december 2010 journal published springer science+business media journal abstracted indexed
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Computational linguistics
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anti-spam techniques users people tend much less bothered spam slipping filters mail box false negatives desired e-mail ham blocked false positives trying balance false negatives missed spams vs false positives rejecting good e-mail critical successful anti-spam system servers able block spam tools individual users help control balance number techniques individuals use restrict availability e-mail addresses reducing preventing attractiveness spam sharing email address among limited group correspondents one way limit spam method relies discretion members group disclosing email addresses outside group circumvents trust relationship group reason forwarding messages recipients n't know one another avoided absolutely necessary forward messages recipients n't know one another good practice list recipient names bcc instead practice avoids scenario unscrupulous recipients might compile list email addresses spamming purposes practice also reduces risk address distributed computers affected email address harvesting malware however privacy email address lost divulgence likely regained posting anonymously fake name address one way avoid e-mail address harvesting users ensure fake address valid users want receive legitimate email regarding posts web sites alter addresses humans figure spammers instance joe example.com might post joenos pam.invalid.example.com address munging however cause legitimate replies lost user valid address truly invalid otherwise someone server still get spam ways use transparent address munging avoid allowing users see actual address obfuscate automated email harvesters methods displaying part e-mail address web page image text logo shrunken normal size using in-line css jumbled text order characters restored using css spammers often regard responses messages—even responses like n't spam —as confirmation email address valid likewise many spam messages contain web links addresses user directed follow removed spammer mailing list several cases spam-fighters tested links confirming lead recipient address removal—if anything lead spam removal request filing complaint may get address list washed lower complaints spammer stay active acquire new accounts and/or internet provider sender addresses often forged spam messages including using recipient address forged sender address responding spam may result failed deliveries may reach innocent e-mail users whose addresses abused usenet widely considered even important avoid responding spam many isps software seek destroy duplicate messages someone may see spam respond cancelled server effect reposting spam since duplicate reposted copy last longer replying may also cause poster falsely linked part spam message contact forms allow users send email filling forms web browser web server takes form data forwarding email address users never see email address forms however sometimes inconvenient users able use preferred e-mail client risk entering faulty reply address typically notified delivery problems contact forms drawback require website supports server side scripts finally software used run contact forms badly designed become spam tool right additionally spammers begun send spam using contact form many modern mail programs incorporate web browser functionality display html urls images easily expose user offensive images spam addition spam written html contain web bugs allows spammers see e-mail address valid message caught spam filters javascript programs used direct user web browser advertised page make spam message difficult close delete spam messages contained attacks upon security vulnerabilities html renderer using holes install spyware computer viruses borne mechanisms mail clients automatically download display html images attachments fewer risks clients configured display default email user may sometimes need give address site without complete assurance site owner use sending spam one way mitigate risk provide disposable email address—a temporary address user disable abandon forwards email real account number services provide disposable address forwarding addresses manually disabled expire given time interval expire certain number messages forwarded disposable email addresses used users track whether site owner disclosed address capability resulted legal jeopardy sites disclose confidential addresses without permission systems use ham passwords ask unrecognised senders include email password demonstrates email message ham spam message typically email address ham password would described web page ham password would included subject line email address ham passwords often combined filtering systems counter risk filtering system accidentally identify ham message spam message plus addressing technique appends password username part email address tracking spammer isp reporting offense lead spammer service terminated criminal prosecution unfortunately difficult track spammer—and online tools assist always accurate occasionally spammers employ netblocks case abuse contact netblock spammer confirm address examples online tools spamcop network abuse clearinghouse provide automated semi-automated means report spam isps spam-fighters regard inaccurate compared expert email system however email users experts free tool called complainterator may used reporting spam complainterator send automatically generated complaint registrar spamming domain registrar name servers historically reporting spam way seriously abated spam since spammers simply move operation another url isp network ip addresses consumers may also forward unwanted deceptive commercial email email address spam uce.gov maintained us federal trade commission ftc database collected used prosecute perpetrators scam deceptive advertising alternative contacting isps contact registrar domain name used spam e-mail registrars icann-accredited administrative organizations obliged uphold certain rules regulations resources necessary dealing abuse complaints advocate responding aggressively spam—in words spamming spammer basic idea make spamming less attractive spammer increasing spammer overhead several ways reach spammer besides caveats mentioned may lead retaliations spammer variety techniques e-mail senders use try make sure send spam failure control amount spam sent judged e-mail receivers often cause even legitimate email blocked sender put dnsbls since spammer accounts frequently disabled due violations abuse policies constantly trying create new accounts due damage done isp reputation source spam many isps web email providers use captchas new accounts verify real human registering account automated spamming system also verify credit cards stolen accepting new customers check spamhaus project rokso list background checks one difficulty implementing opt-in mailing lists many means gathering user email addresses remain susceptible forgery instance company puts web form allow users subscribe mailing list products malicious person enter people email addresses — harass make company appear spamming anti-spammers company sends e-mail forgery victims spamming albeit inadvertently prevent abuse maps anti-spam organizations encourage mailing lists use confirmed opt-in also known verified opt-in double opt-in whenever email address presented subscription list list software send confirmation message address confirmation message contains advertising content construed spam — address added live mail list unless recipient responds confirmation message see also spamhaus mailing lists vs. spam lists page modern mailing list management programs gnu mailman listserv majordomo qmail ezmlm support confirmed opt-in default e-mail senders type anti-spam checks e-mail coming users customers done e-mail coming rest internet sort bounce message anti-virus warning gets sent forged email address result backscatter problems sending challenges forged e-mail addresses greatly reduced creating new message contains challenge instead challenge placed bounce message receiving mail system gives rejection-code smtp session receiving mail system rejects e-mail way sending system actually creates bounce message result bounce message almost always sent real sender format language sender usually recognize firewalls routers programmed allow smtp traffic tcp port 25 machines network supposed run mail transfer agents send e-mail practice somewhat controversial isps block home users especially isps allow blocking turned upon request e-mail still sent computers designated smart hosts via port 25 smart hosts via e-mail submission port 587 network address translation used intercept port 25 smtp traffic direct mail server enforces rate limiting egress spam filtering commonly done hotels cause e-mail privacy problems well making impossible use starttls smtp-auth port 587 submission port n't used machines suddenly start sending lots e-mail may well become zombie computers limiting rate e-mail sent around typical computer question legitimate e-mail still sent large spam runs slowed manual investigation done monitoring spam reports places spamcop aol feedback loop network abuse clearinghouse domain abuse mailbox etc. isps often learn problems seriously damage isp reputation mail servers blacklisted malicious software human spam senders often use forged addresses sending spam messages control may enforced smtp servers ensure senders use correct email address field outgoing messages email users database user record e-mail address smtp server must check email address field outgoing message address belongs user credentials supplied smtp authentication field forged smtp error returned email client e.g email address trying send isps webmail providers either acceptable use policy aup terms service tos agreement discourages spammers using system allows spammer terminated quickly violations increasingly anti-spam efforts led co-ordination law enforcement researchers major consumer financial service companies internet service providers monitoring tracking e-mail spam identity theft phishing activities gathering evidence criminal cases appropriate legislation enforcement significant impact spamming activity penalty provisions australian spam act 2003 dropped australia ranking list spam-relaying countries email spam tenth twenty-eighth legislation provides mandates bulk emailers must follow makes compliant spam easier identify filter analysis sites spamvertised given piece spam often leads questionable registrations internet domain names since registrars required maintain trustworthy whois databases digging registration details complaining proper locations often results site shutdowns uncoordinated activity may effective given today volume spam rate criminal organizations register new domains however coordinated effort implemented adequate infrastructure obtain good results since spamming facilitated fact large volumes email inexpensive send one proposed set solutions would require senders pay cost order send email making prohibitively expensive spammers anti-spam activist daniel balsam attempts make spamming less profitable bringing lawsuits spammers number proposals sideband protocols assist smtp operation anti-spam research group asrg internet research task force irtf working number email authentication proposals providing simple source authentication flexible lightweight scalable recent internet engineering task force ietf activities include marid 2004 leading two approved ietf experiments 2005 domainkeys identified mail 2006 dmarc stands domain-based message authentication reporting conformance standardizes email receivers perform email authentication using well-known sender policy framework spf dkim mechanisms channel email new proposal sending email attempts distribute anti-spam activities forcing verification probably using bounce messages back-scatter n't occur first email sent new contacts smtp proxies allow combating spam real time combining sender behavior controls providing legitimate users immediate feedback eliminating need quarantine statistical bayesian filtering set requires administrative maintenance per se instead users mark messages spam nonspam filtering software learns judgements thus statistical filter reflect software author administrator biases content rather user biases example biochemist researching viagra wo n't messages containing word viagra automatically flagged spam viagra show often legitimate messages still spam emails containing word viagra get filtered content rest spam messages differs significantly content legitimate messages statistical filter also respond quickly changes spam content without administrative intervention long users consistently designate false negative messages spam received email statistical filters also look message headers thereby considering content also peculiarities transport mechanism email typical statistical filtering uses single words calculations decide message classified spam powerful calculation made using groups two words taken together random noise words used successfully fool filter software programs implement statistical filtering include bogofilter dspam spambayes assp e-mail programs mozilla mozilla thunderbird mailwasher later revisions spamassassin another interesting project crm114 hashes phrases bayesian classification phrases also free mail filter popfile sorts mail many categories user wants family friends co-worker spam whatever bayesian filtering spam subject several research conferences including
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Computer security
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whoscall whoscall caller id number management mobile application developed gogolook division korean company naver corporation app identifies incoming call call comes allowing users identify important calls filter unwanted callers also includes number management features number keyword blocks offline database whoscall relies networks local partners internet searches user community generated content identify numbers platform available across android windows phone ios platforms name whoscall derives calling available 31 countries including taiwan korea hong kong japan thailand brazil conception app arose weekly gathering three founders later became gogolook moment took time day jobs work various app ideas weekends free time gathering one founders received telephone call promptly asked others quick search incoming unknown number online hoping search result either forum business page prepare call choose ignore got wondering app feasible first version app launched august 2010 still one several apps part-timers moment got slow start eventually gained traction propelled limelight google ’ ceo eric schmidt visit taiwan mentioned app whoscall name “ app called whoscall tells strange numbers ’ fast growing ... taiwan. ” 2013 whoscall selected google play ’ best apps 2013 8 countries across asia time received initial funding trinity investment corporation angel investors end year whoscall buyout korea internet service company nhn株式會社 nt 529 million dollars whoscall ios version launched december 2014 2015 whoscall official website completely updated provide search services number searching time whoscall officially launched beta test whoscall card also released whoscall featured whoscall dialer shortcuts end 2015 whoscall announced upgrade three major functions whoscall card mobile directory whoscall featured soon became user personal call manager 2016 whoscall fully upgraded whoscall card ios version introduces instant caller identification new blocking features end 2016 whoscall global downloads exceeded 50 million identifying billions times month july 18 2017 whoscall signed mou korean financial management association company launched online shopping reporting system fraud october whoscall released playbook advanced searching feature providing caller identification also store information far whoscall 60 million users around world specializing ai r whoscall showcard released beta v4.3 allows users customize outgoing call screens users edit personal business names along descriptions business address business hours photos shown shown showcard info shown outgoing calls rings screen receiving end call ends receiver call end dialogue may also choose view information regarding number whoscall featured several prominent international media including techcrunch techinasia e27 highly regarded overwhelming positive reviews holds average 4.4 star ratings google play store 2013 google play taiwan awarded whoscall 2013 innovation awards year whoscall awarded google play ’ best apps year taiwan hong kong singapore philippines malaysia indonesia vietnam thailand 2015 whoscall 2015 app store featured next year whoscall became 2016 google play featured awarded popular app google store 2017 whoscall chosen google successful case study event google i/o 2017 november 2011 google ’ ceo eric schmidt visit taiwan mentioned app whoscall name “ app called whoscall tells strange numbers ’ fast growing ... taiwan. ” may 20 2014 president taiwan ying-jeou address nation marking 6th year office mentions gogolook name refers example creativity potential youth taiwan april 2014 growing concerns regarding whoscall privacy issues prompting public figures take press cases public records including home telephone numbers addresses showing incoming calling screens gogolook swiftly came statement never collected stored personal information servers let alone make publicly available soon discovered personal information said public figures leaked government servers poor security made available search engines gogolook sources information whoscall promptly lauded call screen telemarketers also reliable reminder possible dissemination personal information
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Computer security
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heartbeat network computer clusters heartbeat network private network shared nodes cluster accessible outside cluster used cluster nodes order monitor node status communicate messages necessary maintaining operation cluster heartbeat method uses fifo nature signals sent across network making sure messages received system ensures events properly ordered communications protocol every node sends back message given interval say delta effect confirming alive heartbeat messages viewed control messages help determine network includes delayed messages receiver node called sync maintains ordered list received messages message timestamp later given marked time received every node system determines messages received since fifo property ensures messages ordered general difficult select delta optimal applications delta small requires much overhead large results performance degradation everything waits next heartbeat signal
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Distributed computing architecture
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blade software blade block drive-by download exploits computer program developed phillip porras vinod yegneswaran sri international long lu wenke lee georgia institute technology blade funded grants national science foundation united states army research laboratory office naval research program designed prevent drive-by download malware attacks
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Computer security
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larrabee microarchitecture larrabee codename cancelled gpgpu chip intel developing separately current line integrated graphics accelerators named larrabee state park whatcom county washington near town bellingham chip released 2010 core consumer 3d graphics card plans cancelled due delays disappointing early performance figures project produce gpu retail product directly larrabee research project terminated may 2010 intel mic multiprocessor architecture announced 2010 inherited many design elements larrabee project function graphics processing unit product intended co-processor high performance computing almost decade later june 12 2018 idea intel dedicated gpu revived intel desire create discrete gpu set launch 2020 whether new development connected developments larabee remain uncertain however december 4 2009 intel officially announced first-generation larrabee would released consumer gpu product instead released development platform graphics high-performance computing official reason strategic reset attributed delays hardware software development may 25 2010 technology intel blog announced larrabee would released gpu instead would released product high-performance computing competing nvidia tesla project produce gpu retail product directly larrabee research project terminated may 2010 intel mic multiprocessor architecture announced 2010 inherited many design elements larrabee project function graphics processing unit product intended co-processor high performance computing prototype card named knights ferry production card built 22 nm process named knights corner planned production 2012 later larrabee considered hybrid multi-core cpu gpu similarities coherent cache hierarchy x86 architecture compatibility cpu-like wide simd vector units texture sampling hardware gpu-like gpu larrabee would supported traditional rasterized 3d graphics direct3d opengl games however hybridization cpu gpu features also suitable general purpose gpu gpgpu stream processing tasks example might performed ray tracing physics processing real time games offline scientific research component supercomputer larrabee early presentation drew criticism gpu competitors nvision 08 nvidia employee called intel siggraph paper larrabee marketing puff quoted industry analyst peter glaskowsky speculated larrabee architecture like gpu 2006 june 2009 intel claimed prototypes larrabee par nvidia geforce gtx 285 justin rattner intel cto delivered keynote supercomputing 2009 conference november 17 2009 talk demonstrated overclocked larrabee processor topping one teraflops performance claimed first public demonstration single-chip system exceeding one teraflops pointed early silicon thereby leaving open question eventual performance architecture one fifth available competing graphics boards larrabee cancelled standalone discrete graphics product december 4 2009 larrabee intended differ older discrete gpus geforce 200 series radeon 4000 series three major ways expected make larrabee flexible current gpus allowing differentiation appearance games 3d applications intel siggraph 2008 paper mentioned several rendering features difficult achieve current gpus render target read order-independent transparency irregular shadow mapping real-time raytracing recent gpus ati radeon hd 5xxx nvidia geforce 400 series feature increasingly broad general-purpose computing capabilities via directx11 directcompute opencl well nvidia proprietary cuda technology giving many capabilities larrabee x86 processor cores larrabee differed several ways cores current intel cpus core 2 duo core i7 theoretically larrabee x86 processor cores would able run existing pc software even operating systems different version processor might sit motherboard cpu sockets using quickpath intel never announced plans though larrabee native c/c++ compiler included auto-vectorization many applications able execute correctly recompiled maximum efficiency expected required code optimization using c++ vector intrinsics inline larrabee assembly code however gpgpus software would benefited utilization vector processing unit one tech journalism site claims larrabee graphics capabilities planned integrated cpus based haswell microarchitecture larrabee philosophy using many small simple cores similar ideas behind cell processor commonalities use high-bandwidth ring bus communicate cores however many significant differences implementation expected make programming larrabee simpler intel began integrating line gpus onto motherboards intel gma brand 2004 integrated onto motherboards newer versions released sandy bridge incorporated onto die cpu chips sold separately though low cost power consumption intel gma chips made suitable small laptops less demanding tasks lack 3d graphics processing power compete contemporary nvidia amd/ati gpus share high-end gaming computer market hpc market place popular video game consoles contrast larrabee sold discrete gpu separate motherboards expected perform well enough consideration next generation video game consoles team working larrabee separate intel gma team hardware designed newly formed team intel hillsboro oregon site separate designed nehalem software drivers written newly formed team 3d stack specifically written developers rad game tools including michael abrash intel visual computing institute research basic applied technologies could applied larrabee-based products intel siggraph 2008 paper describes cycle-accurate simulations limitations memory caches texture units included larrabee projected performance graphs show many 1 ghz larrabee cores required maintain 60 frame/s 1600×1200 resolution several popular games roughly 25 cores required gears war antialiasing 25 cores f.e.a.r 4× antialiasing 10 cores 4× antialiasing intel claimed larrabee would likely run faster 1 ghz numbers represent actual cores rather virtual timeslices another graph shows performance games scales nearly linearly number cores 32 cores 48 cores performance drops 90 would expected linear relationship continued june 2007 pc watch article suggested first larrabee chips would feature 32 x86 processor cores come late 2009 fabricated 45 nanometer process chips defective cores due yield issues would sold 24-core version later 2010 larrabee would shrunk 32 nanometer fabrication process enable 48-core version last statement performance calculated theoretically maximum possible performance follows 32 cores × 16 single-precision float simd/core × 2 flop fused multiply-add × 2 ghz 2 tflops theoretically public demonstration larrabee architecture took place intel developer forum san francisco september 22 2009 early port former cpu-based research project shown real-time scene contained ray traced water surface reflected surrounding objects like ship several flying vehicles accurately second demo given sc09 conference portland november 17 2009 keynote intel cto justin rattner larrabee card able achieve 1006 gflops sgemm 4kx4k calculation engineering sample larrabee card procured reviewed linus sebastian video published may 14 2018 unable make card give video output however motherboard displaying post code d6
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Computer architecture
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interactive ruby shell interactive ruby shell irb irb repl programming object-oriented scripting language ruby abbreviation irb comes fact filename extension ruby .rb although interactive ruby files extension .irb program launched command line allows execution ruby commands immediate response experimenting real-time features command history line editing capabilities job control able communicate directly shell script internet interact live server developed keiju ishitsuka syntax example
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Programming language topics
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alien 8 alien 8 action-adventure video game developed published ultimate play game released zx spectrum bbc micro amstrad cpc msx 1985 game spiritual successor best-selling knight lore lauded critics isometric graphics game player takes control robot alien 8 whose job ensure cryogenically frozen passengers board starship remain viable ship voyage game written chris stamper graphics designed tim stamper alien 8 uses image masking technique knight lore allows developers create composite structures stacked images without visual overlay technique copyrighted ultimate filmation game engine spiritual predecessor game rendered isometric projection game critically acclaimed upon release reviewers praised game graphics innovation however minor criticism directed similarities knight lore game presented isometric format set board starship taking role robot alien 8 player must explore large starship order ensure cryogenic life support systems preserving biological crew re-activated core system series geometrically-shaped circuits however circuits removed invading aliens distributed around starship main objective game collect correct circuits return respective locations starship reaches destination circuits variously shaped cubes pyramids domes cylinders spiritual predecessor environment game takes form series isometric flip-screen rooms trace outline large starship total 129 rooms filled various objects moveable platforms static hazards spikes hostile aliens well executing well-timed manoeuvres jumps player able use starship props block defend another feature use remote controlled drones directed alien 8 inaccessible dangerous areas dying planet distant galaxy last creatures known guardians stored libraries records knowledge single starship together cryogenically preserved members race single robot alien 8 tasked keeping occupants vessel alive duration journey ship launched towards new solar system alien 8 performs task thousands years journey however ship nears destination attacked boarded hostile aliens cryogenic life support systems damaged attack alien 8 must restore operational status ship automatic thrusting systems manoeuvre planetary orbit development alien 8 began immediately release knight lore stamper brothers predicted publishers would attempt copy knight lore filmation technology games predecessor stamper brothers developed game monochrome avoid visual overlay attribute clash common processing limitation early 8-bit consoles however amstrad release exclusively displayed dual-colours game critically acclaimed upon release reviewer crash praised graphics presentation stating excellent imaginative pleasing compared predecessor despite regarding slight difference amstrad action similarly praised graphics citing amazing brilliant great colour combinations reviewer amtix stated visuals breathtakingly stunning improves predecessor david kelly popular computing weekly stated game little disappointment due similarities knight lore however asserted graphics superior quality predecessor chris bourne sinclair user stated general quality graphics higher predecessor although used identical system crash praised new additions game particular time limit various collectable items reviewer stated new features compelling exciting differs predecessor reviewer amstrad action similarly praised innovation stating wonderfully original ideas despite criticising similarities knight lore kelly praised game extra puzzles animation enemies heralding brilliant bourne similarly praised 3d animation stating every extension game improved knight lore
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Computer architecture
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mcc interim linux mcc interim linux linux distribution first released february 1992 owen le blanc manchester computing centre mcc part university manchester first linux distribution created computer users unix experts featured menu-driven installer installed kernel set end-user programming tools mcc first made linux available anonymous ftp november 1991 le blanc irritations early experiments linux lack working fdisk would later write one need use multiple ftp repositories acquire essential software library version problems inspired creation distribution le blanc claimed referred distributions interim ... intended final official small harmonious moderately tested conform everyone taste -- release -- provide stable base software added prior first release closest approximation linux distribution h j lu boot-root floppy disk images two 5¼ diskette images containing linux kernel minimum tools required get started minimal tools able boot hard drive required editing master boot record hex editor first release mcc interim linux based linux 0.12 made use theodore ts ramdisk code copy small root image memory freeing floppy drive additional utilities diskettes also stated distributions unofficial experiments describing goals releases indeed attempt ever made distribute wide range software even x386 windowing system soon first release came distributions tamu created individuals texas university martin junius mj softlanding linux system h j lu small base system turn quickly superseded debian slackware oldest surviving distributions 1.0 distribution mcc interim pointed debian five times size mcc quite comprehensive final distribution encouraged users switch debian providing transitional support discussed email dated 23 april 1992 boot utilities disk pair included optional pair disks contained gcc g++ 2.1 kermit shoelace released 14 april 1993 added version 0.95c+ bison flex gdb gprof groff gzip man released 26 april 1993 added version 0.99.p8 emacs info added version 0.99.p8+ elm lp mail progman timezone words
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Operating systems
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zerocoin protocol zerocoin privacy protocol proposed johns hopkins university professor matthew d. green graduate students ian miers christina garman 2013 designed extension bitcoin protocol would improve bitcoin transactions anonymity coin-mixing capabilities natively built protocol zerocoin currently compatible bitcoin due public nature blockchain users may privacy compromised interacting network address problem third-party coin mixing service used obscure trail cryptocurrency transactions may 2013 matthew d. green graduate students ian miers christina garman proposed zerocoin protocol cryptocurrency transactions anonymised without going trusted third-party coin destroyed minted erase history coin spent information available reveal exactly coin spent initially zerocoin protocol planned integrated bitcoin network however proposal accepted bitcoin community thus zerocoin developers decided launch protocol independent cryptocurrency project create standalone cryptocurrency implementing zerocoin protocol named moneta september 2016 zcoin xzc first cryptocurrency implement zerocoin protocol launched poramin insom team january 2018 academic paper partially funded zcoin published replacing proof-of-work system memory intensive merkle tree proof algorithm ensuring equitable mining among ordinary users april 2018 cryptographic flaw found zerocoin protocol allows attacker destroy coins owned honest users create coins thin air steal users coins zcoin cryptocurrency team acknowledging flaw stated high difficulty performing attacks low probability giving economic benefit attacker december 2018 zcoin released academic paper proposing lelantus protocol remove need trusted setup hides origin amount coins transaction using zerocoin protocol transactions use zerocoin feature drawn escrow pool coin transaction history erased emerges transactions verified zero-knowledge proofs mathematical way prove statement true without revealing details question 16 november 2013 matthew d. green announced zerocash protocol provides additional anonymity shielding amount transacted zerocash reduces transaction sizes 98 however significantly computationally expensive taking 3.2gb memory generate recent developments protocol reduced 40mb zerocash utilizes succinct non-interactive zero-knowledge arguments knowledge also known zk-snarks special kind zero-knowledge method proving integrity computations proofs less 300 bytes long verified milliseconds contain additional advantage hiding amount transacted well however unlike zerocoin zerocash requires initial set trusted entity developed matthew d. green assistant professor behind zerocoin protocol zcash first zerocash based cryptocurrency began development 2013 late 2014 poramin insom student masters security informatics johns hopkins university wrote paper implementing zerocoin protocol cryptocurrency matthew green faculty member roger ver tim lee zcoin initial investors poramin also set exchanged named satang convert thai baht zcoin directly 20 february 2017 malicious coding attack zerocoin protocol created 370,000 fake tokens perpetrators sold 400 bitcoins 440,000 zcoin team announced single-symbol error piece code allowed attacker create zerocoin spend transactions without corresponding mint unlike ethereum dao event developers opted destroy coins attempt reverse happened newly generated ones september 2018 zcoin introduced dandelion protocol hides origin ip address sender without using onion router tor virtual private network vpn october 2018 unknown user uploaded banned video zcoin blockchain order avoid thai government censorship november 2018 zcoin conducted world first large-scale party elections thailand democrat party using interplanetary file system ipfs december 2018 zcoin implemented merkle tree proof mining algorithm deters usage application-specific integrated circuit asic mining coins memory intensive miners allows ordinary users use central processing unit cpu graphics card mining enable egalitarianism coin mining 30 july 2019 zcoin formally departed zerocoin protocol adopting new protocol called sigma prevents counterfeit privacy coins inflating coin supply achieved removing feature called trusted setup zerocoin protocol pivx cryptocurrency based zerocoin protocol using proof-of-stake mechanism issue new coins validate transactions one criticism zerocoin added computation time required process would need performed primarily bitcoin miners proofs posted blockchain would also dramatically increase size blockchain nevertheless stated original author proofs could stored outside blockchain since zerocoin denomination bitcoin used mint zerocoin anonymity would compromised zerocoins zerocoins denomination currently minted unspent potential solution problem would allow zerocoins specific set denominations however would increase needed computation time since multiple zerocoins could needed one transaction depending specific implementation zerocoin requires two large prime numbers generate parameter easily factored values must either generated trusted parties rely rsa unfactorable objects avoid requirement trusted party setup however possible zerocash protocol
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Internet protocols
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join dependency area computer science known dependency theory join dependency constraint set legal relations database scheme table formula_1 subject join dependency formula_1 always recreated joining multiple tables subset attributes formula_1 one tables join attributes table formula_1 join dependency called trivial join dependency plays important role fifth normal form also known project-join normal form proven scheme formula_5 decomposed tables formula_6 formula_7 decomposition lossless-join decomposition legal relations formula_5 restricted join dependency formula_5 called formula_10 another way describe join dependency say relationships join dependency independent unlike case functional dependencies sound complete axiomatization join dependencies though axiomatization exist expressive dependency languages full typed dependencies however implication join dependencies decidable let formula_5 relation schema let formula_12 decomposition formula_5 relation formula_14 satisfies join dependency join dependency trivial one formula_17 formula_5 2-ary join dependencies called multivalued dependency historical artifact fact studied general case specifically u set attributes r relation r satisfies formula_19 r satisfies formula_20 given pizza-chain models purchases table customer order-number customer-name pizza-name courier following relations derived since relationships independent join dependency follows order-number customer-name order-number pizza-name order-number courier customer courier however join-dependency like order-number customer-name order-number pizza-name order-number courier customer-name courier order-number customer-name courier order-number pizza-name would valid well makes obvious join dependency enough normalize database scheme
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Databases
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dynamic kernel module support dynamic kernel module support dkms program/framework enables generating linux kernel modules whose sources generally reside outside kernel source tree concept dkms modules automatically rebuilt new kernel installed essential feature dkms automatically recompiles dkms modules new kernel version installed allows drivers devices outside mainline kernel continue working linux kernel upgrade another benefit dkms allows installation new driver existing system running arbitrary kernel version without need manual compilation precompiled packages provided vendor dkms written linux engineering team dell 2003 included many distributions ubuntu debian fedora suse arch dkms free software released terms gnu general public license gpl v2 later dkms supports rpm deb package formats out-of-the-box
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Computer architecture
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iphone 3gs iphone 3gs originally styled iphone 3g smartphone designed marketed apple inc third generation iphone successor iphone 3g introduced june 8 2009 wwdc 2009 took place moscone center san francisco iphone named 3gs stood speed phil schiller mentioned launch keynote improvements include performance 3-megapixel camera higher resolution video ability voice control support 7.2 mbit/s hsdpa downloading remains limited uploading apple implemented hsupa protocol released united states canada six european countries june 19 2009 australia japan june 26 internationally july august 2009 iphone 3gs runs apple ios operating system succeeded apple flagship smartphone 2010 iphone 4 june 24 8gb model released discontinuing 16 32gb models however 3gs continued production september 2012 iphone 5 announced iphone 3gs made available pre-order june 7 2009 released june 19 united states canada 7 european countries june 26 australia united kingdom within first weekend release one million iphone 3gs units sold new features iphone 3gs mainly internal changes regarding speed iphone 3gs speedy 2x faster predecessor though addition upgrades mainly regarding performance various software features also introduced exclusive iphone 3gs video recording voice control digital compass features ios apple mobile operating system user interface ios based concept direct manipulation using multi-touch gestures interface control elements consist sliders switches buttons interaction os includes gestures swipe tap pinch reverse pinch specific definitions within context ios operating system multi-touch interface internal accelerometers used applications respond shaking device one common result undo command rotating vertically one common result switching portrait landscape mode lcd display device designed apple made lg features capacitive touchscreen pixel density 163 pixels per inch ppi 480-by-320 display improvements predecessor screen include 24-bit color emulation 18-bit color display plus dithering color rich display oleophobic coating help reduce fingerprints display capacitive touchscreen designed bare finger multiple fingers multi-touch sensing iphone 3gs features improved 3-megapixel camera manufactured omnivision addition higher pixel count also features auto-focus auto white balance auto macro capable capturing vga video iphone 3gs camera app features slider allows users switch capturing photos recording videos tap-to-focus feature allows users tap area camera image auto-focus 5x digital zoom ios 4 later auto focus auto exposure lock holding area ios 5 later gridlines composition ios 5 later iphone 3gs powered samsung apl0298c05 chip designed manufactured samsung first iphone system-on-a-chip system-on-a-chip composed arm cortex-a8 cpu core underclocked 600 mhz 833 mhz integrated powervr sgx 535 gpu 256 mb package package pop dram twice amount 3g allowing increased performance multi-tasking apple claims iphone 3gs 2x faster predecessor showing demonstrations various apps loading half time predecessor previous models data stored flash memory sim offer options expand storage initially available 16 32 gb though 8 gb model later released apple discontinuing 16 32 gb models forcing needing storage select iphone 4 buy older model 3gs iphone 3gs powered internal 3.7 v 1220 mah rechargeable lithium-ion polymer battery designed retain 80 original capacity 400 full charge discharge cycles battery life indicator percentage also exclusive iphone 3gs apple claims 3gs last ten hours video nine hours web browsing wi-fi twelve hours 2g talk time five 3g 30 hours music 300 hours standby magnetometer also built-in iphone 3gs used measure strength and/or direction magnetic field vicinity device sometimes certain devices radio signals interfere magnetometer requiring users either move away interference re-calibrate moving device figure 8 motion iphone 3gs also features compass app unique time release showing compass points direction magnetic field addition iphone 3g tri-band umts/hsdpa radio quad-band gsm/gprs/edge radio 3gs also adds support 7.2 mbit/s hsdpa allowing faster downlink speeds though upload speeds remain apple implemented hsupa protocol updates include addition built-in nike+ipod sensor eliminates need external sensor allows native nike+ipod support bluetooth server iphone 3gs also slightly improved adding support bluetooth 2.1 specifications voice control introduced exclusive feature iphone 3gs allows controlling phone music features phone voice two ways activate voice control hold home button home screen seconds change effect double-clicking home button activate voice control ios 3.x ios 4 later double clicking home button opens multitasking bar voiceover color inversion text zoom introduced exclusive features iphone 3gs voiceover feature dictates music details system menus text things first introduced third generation ipod shuffle color inversion reverses color scheme black white white black text zoom allows users zoom text screen iphone 3gs retains design 3g glossy plastic back tapered edges metal buttons 3gs reflective silver text reverse side matches silver apple logo replacing 3g grey text unlike predecessor iphone 3gs available white black 16 gb 32 gb although 8 gb model available black reviews iphone 3gs generally mixed favorable walt mossberg wall street journal described device packed new features makes great product even better many users software may enough boost keep buying new model engadget also said additions video recording compass speed bump n't seem compelling us device managed receive numerous favorable reviews cnet gave iphone 3gs 4 5 stars citing battery life improvements speed bump engadget praised performance improvements 8 gb version received favorable reviews mainly comes pre-installed ios 4 jason snell macworld praised iphone 3gs saying device internal changes shines ios 4 update making iphone 3gs worthwhile upgrade compared predecessor although little late compared iphone 4 tipb stated aside hardware specific features like facetime retina display gyroscope support bottom line iphone 3gs users getting software makes iphone 4 great shortly release iphone 3gs users reported overheating device heavy use others reported discoloration device due heat particularly white models discoloration issues largely discounted result iphone covers rubbing back iphone apple responded heat issue reports warning users leaving iphones car hot day leaving direct sunlight extended periods time refraining heavy usage hot/sunny environment also worth pointing temperature specifications iphone operated follows safety standards countries 3gs released release iphone 4 iphone 3gs received update ios 4 release iphone 4s 3gs still offered free contract november 2011 raised price 59 cents explanation 99¢ price available two-year contract united states three-year contract telus rogers bell fido solutions canada departure apple previous trends two phones sold september 9 2009 apple launched updated model iphone 3gs patched segment overflow securerom device allowed loading unsigned llb release iphone 4s apple updated baseband hardware infineon baseband chip toshiba baseband chip week 2 production 2011 removed end-user ability change basebands although new chip uses modem firmware infineon chip updated ipad baseband 06.15.00 still vulnerable at+xapp exploit 3gs received ios 6 making first ios device receive updates four major ios releases although 3gs still supported major features ios 6 supported 3gs generally positive reviews smooth performance ios 5 even claim better performance making still good candidate ios 6 september 12 2012 apple announced would longer selling supporting iphone 3gs device receive ios 7 due hardware limitations february 21 2014 apple issued ios 6.1.6 fix infamous goto fail ssl security bug
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Operating systems
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fhfs file server fhfs ftp http web server package transparently based hfs filezilla fhfs built act all-in-one user-based file hosting website good schools businesses etc whose students/employees need easily transport files fhfs designed specifically account-based storage easily compatible uses using over-top original hfs setup early development started january 2011 beta builds tested october 2011 version 1.0 released 11/3/2011 fhfs started accelerate development filesplat.com well showcase capabilities hfs macros fhfs 2.0 released 10/28/2012 exactly one year first beta 1.0 fhfs loosely based source code www.filesplat.com time created developer filesplat longer uses fhfs fhfs written several different languages including hfs macros xml xhtml css javascript dos php c fhfs recognized developer hfs fhfs 2.0.5 contains roughly 9500 somewhat-compressed lines 412,000 characters original code addition standard features hfs
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Internet protocols
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mb86900 mb86900 microprocessor produced fujitsu implements sparc v7 instruction set architecture developed sun microsystems first implementation sparc introduced 1986 used first sparc-based workstation sun microsystems sun-4 1987 chipset operated 16.67 mhz chipset consisted two chips mb86900 microprocessor mb86910 floating-point unit chip set implemented two 20,000-gate 1.2 µm complementary metal–oxide–semiconductor cmos gate-arrays fabricated fujitsu limited
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Computer architecture
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temporal multithreading temporal multithreading one two main forms multithreading implemented computer processor hardware simultaneous multithreading distinguishing difference two forms maximum number concurrent threads execute given pipeline stage given cycle temporal multithreading number one simultaneous multithreading number greater one authors use term super-threading synonymously many possible variations temporal multithreading classified two sub-forms main processor pipeline may contain multiple threads context switches effectively occurring pipe stages e.g. barrel processor form multithreading expensive coarse-grained forms execution resources span multiple pipe stages may deal multiple threads also contributing cost fact design optimized around concept background thread — concurrent threads implemented hardware might require state read written cycle forms temporal multithreading similar many ways simultaneous multithreading simultaneous process hardware must store complete set states per concurrent thread implemented hardware must also preserve illusion given thread processor resources fairness algorithms must included types multithreading situations prevent one thread dominating processor time and/or resources temporal multithreading advantage simultaneous multithreading causes lower processor heat output however allows one thread executed time
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Computer architecture
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circuit-level gateway circuit-level gateway type firewall circuit-level gateways work session layer osi model shim-layer application layer transport layer tcp/ip stack monitor tcp handshaking packets determine whether requested session legitimate information passed remote computer circuit-level gateway appears originated gateway firewall technology supervises tcp handshaking among packets confirm session genuine firewall traffic cleaned based particular session rules may controlled acknowledged computers circuit-level firewalls conceal details protected network external traffic helpful interdicting access impostors circuit-level firewalls clean entity packets circuit-level gateways relatively inexpensive advantage hiding information private network protect hand filter individual packets
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Internet protocols
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xactly corporation xactly corporation pure-play saas company provides cloud-based enterprise software services offer tools allow sales performance management sales effectiveness sales compensation employee engagement xactly corporation headquartered san jose california company raised 116 million funding since inception 2005 investors include rembrandt venture partners alloy ventures key venture partners bay partners outlook ventures illuminate ventures silicon valley bank wellington financial salesforce.com xactly corp created march 1 2005 founder ceo christopher w. cabrera co-founder managing director satish k. palvai company headquartered san jose california xactly corp acquired centive automated incentive compensation management technology solutions company 2009 july 31 2017 company taken private vista equity partners delisted new york stock exchange
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Distributed computing architecture
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greenbutton greenbutton new zealand-based software firm company specialized moving independent software vendors isvs enterprises cloud computing founded 2006 greenbutton based wellington new zealand additional offices palo alto california seattle greenbutton acquired microsoft 2 may 2014 technologies integrated azure service greenbutton founded intergrid 2006 wellington new zealand provide small scale customers access job processors company helped software vendors use cloud computing offering service called greenbutton july 2010 2011 company renamed greenbutton joined microsoft partner network 2011 greenbutton declared microsoft corp ’ windows azure isv partner year 2011 new zealand partner year award microsoft new zealand may 2011 greenbutton entered alliance microsoft included investment reported us 1 million adding mark canepa board directors greenbutton bizspark partner year software exporter year awards ms new zealand 2011 dave fellows greenbutton solutions architect year award year december 2011 greenbutton opened two offices united states office palo alto california functioned us headquarters second sales office seattle greenbutton finalists new zealand hi-tech awards company total turnover 1.5 million fiscal year 2011-12 greenbutton partnered pixar animation studios microsoft cloud computing platform windows azure rendering service renderman image generating software announced january 2012 service enhances renderman interface specification june 2012 greenbutton announced partnership gns science new zealand american based stillwater group cloud computing seismic processing company promoted software integrated seismic processing amazon web services aws cloud service seismic processing part oil natural gas exploration process requires heavy processing data 2012 greenbutton entered partnership numerix american company develops software risk analysis financial derivatives award 2012 wellington gold awards 2 may 2014 greenbutton announced acquisition microsoft technology integrated microsoft azure greenbutton stopped accepting new customers day acquisition greenbutton operates microsoft azure product line azure batch
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Distributed computing architecture
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avature avature privately held global human capital management software company sells software service company founded dimitri boylan co-founder former ceo hotjobs incorporated dublin ireland operating subsidiaries argentina australia china germany spain united kingdom united states avature platform designed support development strategic hr solutions talent acquisition talent management used 160 countries 24 languages company 650 customers including 110 fortune 500 well several government entities educational institutions 2018 company 600 employees originally founded recruiting outsourcing service provider new york buenos aires 2005 avature provided services large organizations global staffing firms september 2008 company commercially released flagship product avature crm flexible enterprise platform global talent acquisition market leader sourcing recruitment marketing candidate engagement 2012 avature sold recruiting services businesses korn ferry focused efforts development technology subsequent years company ’ product suite expanded include additional talent acquisition solutions applicant tracking campus events recruiting onboarding well talent management solutions including internal mobility performance management contingent workforce management october 2008 human resource executive magazine pointed avature crm top hr product 2010 identified gartner 'cool vendor´ innovations human capital management company also recognized hro today 2012 tektonic award talent management furthermore avature contingent workforce management solution avature cwm named 2018 top hr product human resource executive magazine october 2018 saas report named avature chief financial officer ana laura darino within annual top women leaders saas list
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Distributed computing architecture
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nokia e5-00 nokia e5-00 also called nokia e5 qwerty smartphone runs symbian os v9.3 operating system like phones nokia eseries targeted b2b comes business software applications including quickoffice office document editor released third quarter 2010 comes candybar form factor casing five color options e5-00 similar e72 dram memory e72 also important cost reductions one cost reduction technology lcds screen e5-00 transmissive lcd display e-72 transflective lcd e5 supports 256k display colors important cost reductions removal secondary camera accelerometer digital compass third full focus camera extends depth field without narrowing aperture instead autofocus e5-00 smaller battery 1200 mah e-72 1500 talk-time 8 hours stand time 10 days also features gps integrated assisted runs nokia maps 3.0 ovi maps nokia e5 supports mail exchange ibm lotus notes traveler corporate emails e5 supports hd voice nokia e5-00 features im instant messenger allowing access several chat services communities simultaneously include yahoo messenger google talk skype wechat whatsapp windows live messenger reception e5 generally positive cnet uk praised quality full qwerty keyboard criticized performance 320 x 240 pixel lcd quoting virtually impossible see direct sunlight softpedia contrast stated lcd worked perfectly sunlight softpedia wrote e5-00 all-rounder performs decent areas though also stated camera strong point
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Operating systems
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starling framework starling open source game framework used create 2d games run mobile desktop platforms recreates traditional flash display list architecture top accelerated graphics hardware several commercial games built starling including angry birds friends incredipede starling initiated 2011 adobe shortly introducing stage3d api air flash run-time systems stage3d allows utilizing gpu inside flash player via low-level api starling simplify transition developers providing accompanying high-level api built top stage3d framework seen rapid adoption years utilized many games independent commercial developers part adobe gaming sdk since starling introduction several open source libraries published 3rd party developers depend starling extend functionality
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Programming language topics
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syntax definition formalism syntax definition formalism sdf metasyntax used define context-free grammars formal way describe formal languages express entire range context-free grammars current version sdf3 parser parser generator sdf specifications provided part free asf+sdf meta environment operate using sglr scannerless glr parser sdf parser outputs parse trees case ambiguities parse forests features sdf following example defines simple boolean expression syntax sdf2
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Programming language topics
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apache spamassassin apache spamassassin computer program used e-mail spam filtering uses variety spam-detection techniques including dns-based fuzzy-checksum-based spam detection bayesian filtering external programs blacklists online databases released apache license 2.0 part apache foundation since 2004 program integrated mail server automatically filter mail site also run individual users mailbox integrates several mail programs apache spamassassin highly configurable used system-wide filter still configured support per-user preferences apache spamassassin created justin mason maintained number patches earlier program named filter.plx mark jeftovic turn begun august 1997 mason rewrote jeftovic code scratch uploaded resulting codebase sourceforge april 20 2001 summer 2004 project became apache software foundation project later officially renamed apache spamassassin spamassassin 3.4.2 release first well three years developers say project picked new set developers moving forward apache spamassassin perl-based application mail :spamassassin cpan usually used filter incoming mail one several users run standalone application subprogram another application milter sa-exim exiscan mailscanner mimedefang amavis client spamc communicates daemon spamd client/server embedded mode operation performance benefits certain circumstances may introduce additional security risks typically either variant application set generic mail filter program called directly mail user agent supports whenever new mail arrives mail filter programs procmail made pipe incoming mail apache spamassassin adjustment user .procmailrc file apache spamassassin comes large set rules applied determine whether email spam rules based regular expressions matched body header fields message apache spamassassin also employs number spam-fighting techniques rules called tests spamassassin documentation test score value assigned message matches test criteria scores positive negative positive values indicating spam negative ham non-spam messages message matched tests apache spamassassin combines results global score assigned message higher score higher probability message spam apache spamassassin internal configurable score threshold classify message spam usually message considered spam matches multiple criteria matching single test usually enough reach threshold apache spamassassin considers message spam rewritten default configuration content mail appended mime attachment brief excerpt message body description tests resulted mail classified spam score lower defined settings default information tests passed total score still added email headers used post-processing less severe actions tagging mail suspicious apache spamassassin allows per-user configuration behavior even installed system-wide service configuration read file database configuration users specify individuals whose emails never considered spam change scores certain rules user also define list languages want receive mail apache spamassassin assigns higher score mails appear written another language apache spamassassin based heuristics pattern recognition software exhibits false positives false negatives apache spamassassin also supports methods added reasonably easily writing perl plug-in apache spamassassin apache spamassassin reinforces rules bayesian filtering user administrator feeds examples good ham bad spam filter order learn difference two purpose apache spamassassin provides command-line tool sa-learn instructed learn single mail entire mailbox either ham spam typically user move unrecognized spam separate folder run sa-learn folder non-spam folder spam separately alternatively mail user agent supports sa-learn called individual emails regardless method used perform learning spamassassin bayesian test help score future e-mails based learning improve accuracy apache spamassassin free/open source software licensed apache license 2.0 versions prior 3.0 dual-licensed artistic license gnu general public license codice_1 utility distributed apache spamassassin compiles spamassassin ruleset deterministic finite automaton allows apache spamassassin use processor power efficiently apache spamassassin designed trigger gtube 68-byte string similar antivirus eicar test file string inserted rfc 5322 formatted message passed apache spamassassin engine apache spamassassin trigger weight 1000
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Computer security
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cbl index cbl index ratio number ip addresses given ip subnet subnetwork number cbl composite blocking list listings subnet may used measure clean compromised computers given subnet higher number cleaner subnet cbl index may represented decibels db cidr suffix */xx note spam researchers prefer use percentage ips listed subnet using percentages better suited unclean subnets clean nets significantly less 1 addresses listed cbl dnsbl composite blocking list lists ip addresses compromised virus spam sending infection computer worm computer virus spamware cbl full zone data available publicly via rsync download cbl index reasonably good tool getting estimates subnet outgoing spam reputation treated caution subnets often contain ips radically different purposes assuming ips within subnet represent risk/reputation potentially dangerous cbl index may used estimation overall anti-spam performance isp operator cbl zone dated 2007-07-07t21:03+00:00 166_086 ip addresses listed 83.0.0.0/11 network cbl index net 2_097_152/166_086 12.6 */28.3 11.0 db 2_097_152 number ip addresses */11 network 2** 32-11
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Computer security
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xarchiver xarchiver front-end various command line archiving tools linux bsd operating systems designed independent desktop environment default archiving application xfce lxde uses gtk+2 toolkit provide program interface therefore capable running system gtk+2 support exists large number applications also use toolkit support widespread among linux distributions irrespective specific desktop solution supported formats time version 0.5.2 appropriate installed program 7z arj bzip2 gzip lha lzma lzop rar rpm deb tar zip xarchiver uses direct save protocol xds drag drop file saving program acts front-end various commonly installed libraries dealing supported compression formats xarchiver ca n't create archives whose archiver installed currently xfce master branch xarchiver continued github
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Computer file systems
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minet minet stimulus protocol carries keystroke information telephone set call control server also used carry information set control simple text displays mitel corporation designed 1980s signaling protocol proprietary digital tdm telephone sets later used control mitel ip sets encapsulated within tcp mitel uses alternative functional protocol sip maintain practical life pbx call control software
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Internet protocols
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home directory home directory file system directory multi-user operating system containing files given user system specifics home directory name location defined operating system involved example linux bsd fhs systems use /home/ username windows systems 2000 server 2003 keep home directories folder called documents settings user home directory intended contain user files including text documents music pictures videos etc may also include configuration files preferred settings software used might tailored liking web browser bookmarks favorite desktop wallpaper themes passwords external services accessed via given software etc user install executable software directory available users permission directory home directory organized use sub-directories content user home directory protected file system permissions default accessible authenticated users administrators user granted administrator privileges authority access protected location filesystem including users home directories separating user data system-wide data avoids redundancy makes backups important files relatively simple furthermore trojan horses viruses worms running user name privileges cases able alter files user home directory perhaps files belonging workgroups user part actual system files unix user automatically placed home directory upon login ~user shorthand variable refers user home directory allowing user navigate anywhere else filesystem use unix commands tilde character shorthand command refers particular user home directory unix superuser access directories filesystem hence access home directories users superuser home directory older systems many newer systems located /root linux bsd /var/root mac os x openvms operating system user home directory called root directory equivalent unix/dos/windows/amigaos root directory referred master file directory single-user operating systems simply single directory partition user files individual directory setup per user though users still setup maintain directories inside main working directory manually
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Computer file systems
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take-grant protection model take-grant protection model formal model used field computer security establish disprove safety given computer system follows specific rules shows even though question safety general undecidable specific systems decidable linear time model represents system directed graph vertices either subjects objects edges labeled label indicates rights source edge destination two rights occur every instance model take grant play special role graph rewriting rules describing admissible changes graph total four rules preconditions formula_1 preconditions formula_2 using rules take-grant protection model one reproduce states system change respect distribution rights therefore one show rights leak respect given safety model
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Computer security
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windowproc win32 application programming windowproc window procedure user-defined callback function processes messages sent window function specified application registers window class named anything necessarily windowproc window procedure responsible handling messages sent window function prototype windowproc given hwnd handle window message sent umsg identifies actual message wparam lparam parameters whose meaning depends message application identify message take required action hundreds different messages produced result various events taking place system typically application processes small fraction messages order ensure messages processed windows provides default window procedure called defwindowproc provides default processing messages application process application usually calls defwindowproc end windowproc function whatever messages processed passed default procedure
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Operating systems
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open database license open database license odbl copyleft share alike license agreement intended allow users freely share modify use database maintaining freedom others odbl published open data commons see also open data part open knowledge international foundation odbl created goal allowing users share data freely without worrying problems relating copyright ownership allows users make free use data database without worrying copyright creators add data use databases license establishes rights users database well correct procedure attributing credit credit due data make changes improvements data thus simplifying sharing comparison data users longer need worry repercussions violations copyright law stolen information using open database license openstreetmap osm project completed move creative commons license odbl september 2012 attempt legal security specific license databases rather creative works projects using odbl include opencorporates open food facts paris opendata
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Databases
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anaconda python distribution anaconda free open-source distribution python r programming languages scientific computing data science machine learning applications large-scale data processing predictive analytics etc aims simplify package management deployment package versions managed package management system conda anaconda distribution used 15 million users includes 1500 popular data-science packages suitable windows linux macos anaconda distribution comes 1,500 packages well conda package virtual environment manager also includes gui anaconda navigator graphical alternative command line interface cli big difference conda pip package manager package dependencies managed significant challenge python data science reason conda exists pip installs python package dependencies required whether conflict packages installed previously working installation example google tensorflow suddenly stop working pip install different package needs different version numpy library insidiously everything might still appear work get different results data science unable reproduce results elsewhere n't pip install order conda analyzes current environment everything installed version limitations specify e.g want tensorflow 2.0 figures install compatible dependencies tell want ca n't done pip contrast install thing wanted dependencies even breaks things open source packages individually installed anaconda repository anaconda cloud anaconda.org private repository mirror using codice_1 command anaconda inc compiles builds packages anaconda repository provides binaries windows 32/64 bit linux 64 bit macos 64-bit also install anything pypi conda environment using pip conda knows installed pip installed custom packages made using codice_2 command shared others uploading anaconda cloud pypi repositories default installation anaconda2 includes python 2.7 anaconda3 includes python 3.7 however create new environments include version python packaged conda anaconda navigator desktop graphical user interface gui included anaconda distribution allows users launch applications manage conda packages environments channels without using command-line commands navigator search packages anaconda cloud local anaconda repository install environment run packages update available windows macos linux following applications available default navigator conda open source cross-platform language-agnostic package manager environment management system installs runs updates packages dependencies created python programs package distribute software language e.g. r including multi-language projects conda package environment manager included versions anaconda miniconda anaconda repository anaconda cloud package management service anaconda find access store share public private notebooks environments conda pypi packages cloud hosts useful python packages notebooks environments wide variety applications need log cloud account search public packages download install build new packages using anaconda client command line interface cli manually automatically upload packages cloud
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Operating systems
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rainbow series rainbow series sometimes known rainbow books series computer security standards guidelines published united states government 1980s 1990s originally published u.s. department defense computer security center national computer security center standards describe process evaluation trusted systems cases u.s. government entities well private firms would require formal validation computer technology using process part procurement criteria many standards influenced superseded common criteria books nicknames based color cover example trusted computer system evaluation criteria referred orange book book entitled applied cryptography security expert bruce schneier states ncsc-tg-021 ca n't even begin describe color cover books series hideously colored covers goes describe receive copy saying n't tell sent
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Computer security
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dexter malware dexter computer virus point sale malware infects computers running microsoft windows discovered security firm seculert december 2012 infects pos systems worldwide steals sensitive information credit card debit card information december 2013 researchers discovered stardust major revision dexter compromised 20,000 cards active campaign hitting us merchants one first known botnets target point-of-sale pos terminals used stores restaurants process customers credit debit card payments
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Computer security
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series 30+ series 30+ abbreviated s30+ software platform application user interface used nokia-branded mobile devices platform introduced nokia september 2013 first appearing nokia 108 main nokia feature phone operating system end series 30 series 40 platforms 2014 despite similar name user interface s30+ technically completely different unrelated s30 many s30+ devices support maui runtime environment mre developed mediatek later devices included support j2me applications even models n't support java j2me applications still capable running built-in online applications opera mini browser bing search msn weather skype groupme chat s30+ models also come online shop would allow downloading new apps games platform taken nokia microsoft mobile 2014 hmd global 2016 although devices still selling brand nokia following feature phones use series 30+ platform available single dual sim models maximum accepted video resolution 854×480
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Operating systems
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ibm thinkpad 310 ibm thinkpad 310 notebook computer manufactured 1997 ibm corporation part thinkpad laptop 300 series models shipped windows 95 capable running windows 3.1 later versions windows far recent windows xp provided sufficient ram driver upgrades run properly well several linux variations features hardware varied model three models 310 lineup featured cd-rom standard none featured internal floppy drive bay capable housing floppy drive models feature port back allowed connection external floppy drive could boot models featured intel pentium processor running 166 mhz graphics hardware chips technologies 65550 pci system approximately 1 mb video memory dstn display capable 800x600 resolution models also featured 2 type ii cardbus slots models came either 16mb 32mb edo ram
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Computer architecture
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arpwatch arpwatch computer software tool monitoring address resolution protocol traffic computer network generates log observed pairing ip addresses mac addresses along timestamp pairing appeared network also option sending email administrator pairing changes added network administrators monitor arp activity detect arp spoofing network flip-flops changed new stations address reuse arpwatch developed lawrence berkeley national laboratory network research group open-source software released bsd license
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Computer security
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software lockout multiprocessor computer systems software lockout issue performance degradation due idle wait times spent cpus kernel-level critical sections software lockout major cause scalability degradation multiprocessor system posing limit maximum useful number processors mitigate phenomenon kernel must designed critical sections short possible therefore decomposing data structure smaller substructures multiprocessor systems processor schedules controls therefore supervisor processor kernel data structures globally shared sections code access shared data structures critical sections design choice made improve scaling reliability modularity examples kernel data structure ready list communication channels conflict happens one processor trying access resource memory portion time prevent critical races inconsistency one processor cpu given time allowed access particular data structure memory portion cpus trying access time locked-out waiting idle status three cases distinguished idle wait either necessary convenient convenient idle wait necessary access ready list low level scheduling operation idle wait necessary convenient case critical section synchronization/ipc operations require less time context switch executing another process avoid idle wait idle wait instead convenient case kernel critical section device management present monolithic kernels microkernel instead falls first two cases multiprocessor system conflicts kernel-level conflicts due access kernel level critical sections thus idle wait periods generated major impact performance degradation idle wait time increases average number idle processors thus decreases scalability relative efficiency taking parameters average time interval spent processor kernel level critical sections l time locked state average time interval spent processor tasks outside critical sections e ratio l/e crucial evaluating software lockout typical values l/e range 0.01 0.1 system l/e ratio 0.05 instance 15 cpus expected average 1 cpu always idle 21 cpus 2.8 idle 40 cpus 19 idle 41 cpus 20 idle therefore adding 40 cpus system would useless general l/e value threshold maximum number useful cpus reduce performance degradation software lockout reasonable levels l/e 0.05 0.1 kernel and/or operating system must designed accordingly conceptually valid solution decompose kernel data structure smaller independent substructures shorter elaboration time allows one cpu access original data structure many uniprocessor systems hierarchical protection domains estimated spend 50 time performing supervisor mode operations systems adapted multiprocessing setting lock access supervisor state l/e would easily greater 1 resulting system throughput uniprocessor despite number cpus
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Computer architecture
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installation computer programs installation setup computer program including device drivers plugins act making program ready execution installation refers particular configuration software hardware view making use able computer soft digital copy piece software program needed install different processes installing piece software program process varies program computer programs including operating systems often come installer specialized program responsible whatever needed see installation installation may part larger software deployment process installation typically involves code program copied/generated installation files new files local computer easier access operating system creating necessary directories registering environment variables providing separate program un-installation etc.. code generally copied/generated multiple locations uninstallation usually involves erasing program folder example registry files system code may need modified deleted complete uninstallation computer programs executed simply copying folder stored computer executing programs supplied form unsuitable immediate execution therefore need installation procedure installed program executed without need reinstall execution common operations performed software installations include operations may require charges free charge case payment installation costs means costs connected relevant incurred result installing drivers equipment customers premises installers may attempt trick users installing junkware various forms adware toolbars trialware software partnering companies prevent extra caution exactly asked installed needed installation additional software simply skipped unchecked may require user use custom detailed expert version installation procedure .such malicious conduct necessarily decision software developers company also issue external installers download.com installer cnet mentioned earlier computer programs need installation usual many programs run dos mac os atari tos amigaos computing environments grew complex fixed hard drives replaced floppy disks need tangible installation presented example commodore released installer amiga class modern applications need installation known portable applications may roamed around onto different computers run similarly live operating systems need installation run directly bootable cd dvd usb flash drive loaded network thin clients examples amigaos 4.0 various linux distributions morphos mac os versions 1.0 9.0 see live cd live usb finally web applications run inside web browser need installation windows systems common form installation installation process usually needs user attends make choices accepting declining end-user license agreement eula specifying preferences installation location supplying passwords assisting product activation graphical environments installers offer wizard-based interface common attended installers may ask users help mitigate errors instance disk computer program installed full installer may ask user specify another target path clear enough space disk common misconception unarchivation considered installation action include user choices accepting declining eula installation display messages windows progress silent installation unattended installation see silent installations unattended unattended installations silent reason behind silent installation may convenience subterfuge malware almost always installed silently installation performed without user interaction progress user present one reasons use approach automate installation large number systems unattended installation either require user supply anything received necessary input prior start installation input may form command line switches answer file file contains necessary parameters windows xp linux distributions examples operating systems installed answer file unattended installation assumed user help mitigate errors instance installation medium faulty installer fail installation user fix fault replace medium unattended installers may record errors computer log later review installation performed without using computer monitor connected attended forms headless installation another machine connects target machine instance via local area network takes display output since headless installation need user location target computer unattended headless installers may used install program multiple machines time installation process runs preset time predefined condition transpires opposed installation process starts explicitly user command instance system administrator willing install later version computer program used schedule installation occur program running operating system may automatically install device driver device user connects see plug play malware may also installed automatically example infamous conficker installed user plugged infected device computer clean installation one done absence interfering elements old versions computer program installed leftovers previous installation particular clean installation operating system installation target disk partition erased installation since interfering elements absent clean installation may succeed unclean installation may fail may take significantly longer network installation shortened netinstall installation program shared network resource may done installing minimal system proceeding download packages network may simply copy original media software publishers offer site licenses institutional customers may provide version intended installation network installation program installer computer program installs files applications drivers software onto computer installers specifically made install files contain installers general-purpose work reading contents software package installed differences package management system installer installation computer programs sometimes necessary update installer package manager make possible technique called bootstrapping used common pattern use small executable files update installer starts real installation update small executable called bootstrapper sometimes bootstrapper installs prerequisites software bootstrapping process cross-platform installer builders produce installers run windows macos linux example installanywhere flexera software windows nt family includes installation api associated service called windows installer microsoft provides minimum level tools required create installers using windows installer freely available windows sdk instead focusing api allow developers third parties leverage creating custom installers third party tools may supporting create installers using api speed process examples include installshield flexera software wix outercurve foundation installation authoring tools rely windows installer include wise installation studio wise solutions inc. installer vise mindvision software visual installer samlogic nsis clickteam innosetup installsimple macos includes installer native package manager macos also includes separate software updating application software update supports apple system software included dock 10.6.6 mac app store shares many attributes successful app store ios devices similar app approval process use apple id purchases automatic installation updating although apple preferred delivery method macos previously purchased licenses transferred mac app store downloading automatic updating commercial applications macos may also use third-party installer mac version installer vise mindvision software installermaker stuffit system installer software used set install operating system onto device examples system installers linux ubiquity wubi ubuntu anaconda centos fedora debian-installer debian-based versions linux yast suse-based projects another example found haiku operating system uses utility called haiku installer install onto device booting live cd live usb
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Operating systems
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omniweb omniweb proprietary internet web browser developed marketed omni group exclusively apple macos operating system though longer maintained still available free download omniweb originally developed omni group nextstep platform released lighthouse design march 17 1995 one month development time nextstep evolved openstep mac os x omniweb updated run platforms omniweb also able run microsoft windows yellow box openstep frameworks lighthouse design bought sun microsystems omni group released product version 2.5 onwards version 4.0 onwards omniweb developed solely os x platform omniweb developed using cocoa api allowed take full advantage os x features used quartz render images smooth text use multiple processors available featured interface made use aqua ui features drawers sheets customizable toolbars omniweb originally employed proprietary html layout engine used standard api nstext components however engine slow particularly scrolling fully compatible recent web standards cascading style sheets omniweb version 4.5 omni group adopted apple khtml-based webcore rendering engine created apple safari browser august 11 2004 omni group released version 5.0 omniweb included number new features notable feature unusual implementation tabbed browsing tabs displayed vertically drawer side window including optional thumbnail pictures pages despite certain amount controversy merits tab drawer tab toolbar feature persisted final version september 7 2006 version 5.5 released major new features included use custom version webkit instead webcore universal binary support saving web archive support user-defined style sheets select next link feature ftp folder display ad-blocking improvements updated localizations many small changes bug fixes omniweb omni group flagship app os x web browsers improved—apple eventually bundled safari os x— omni successfully introduced products omnigraffle omnioutliner omniweb importance diminished omniweb price successively lowered first 39.95 february 24 2009 omni group announced omniweb would made available free change previous price 14.95 omni group official website states browser longer active development omniweb popular early 2000s omnigroup experience developing openstep became foundation mac os x gave edge developers apple safari omniweb best support mac os x technologies among competition chiefly mozilla firefox internet explorer mac john siracusa technology journalist critic writing ars technica said finding level functionality proper mac os x application respected developer proven track record like finding perfect 1/10,000th scale replica eiffel tower box crackerjacks tower transforms tiny robot makes lunch
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Internet protocols
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pac-man championship edition game designed tōru iwatani creator original 1980 arcade game pac-man iwatani final game retirement originally released xbox live arcade service xbox 360 later released android ios j2me roku maemo 5 s60 platforms playstation network playstation portable playstation 3 consoles nintendo 3ds part retail game pac-man galaga dimensions part downloadable game compilation pac-man museum xbox 360 playstation 3 steam pc pac-man championship edition received two successors—an indirect follow-up pac-man championship edition dx released 2010 featuring new gameplay elements—and direct sequel pac-man championship edition 2 released playstation 4 xbox one pc 2016 like original pac-man basic game play pac-man championship edition consists entirely navigating pac-man maze eating dots power pellets bonus items fruits keys objects avoiding four ghosts roam maze well pac-man caught ghost player loses life eating power pellet causes ghosts turn blue allowing pac-man eat send back home re-emerge original form however several major differences original counterpart making pac-man c.e faster paced game maze divided two halves eating dots one half causes bonus item appear side eating item causes new maze appear half players also collect additional power pellets increase powered time continue earning maximum points eating ghosts longer player stays alive faster game gets points earned opposed levels game played within certain time limit players attempting get highest score possible game features six modes championship basic five-minute mode two challenge modes affect stage increasing power pellet pickups putting maze darkness three extra modes featuring different mazes game also supports online leader boards game originally released xbox live arcade service june 6 2007 announcement game spurred purchases xbox 360 japan pac-man c.e also available disc titled xbox live arcade compilation bundled xbox 360 arcade console bundle well compilation package namco museum virtual arcade latter however ca n't accessed within nmva must accessed game library ports ios j2me android psp minis released december 10 2009 middle 2009 late 2010 december 1 2010 respectively follow-up pac-man championship edition dx released xbox live arcade november 17 2010 playstation network november 23 2010 original pac-man championship edition ported nintendo 3ds part retail game titled pac-man galaga dimensions 2011 included downloadable game titled pac-man museum 2014 june 5 2007 first pac-man world championship held new york city brought together ten competitors eight countries play new pac-man championship edition prior release xbox live arcade top two scorers robert glashuettner austria carlos daniel borrego romero mexico competed championship single five-minute round borrego named pac-man world champion xbox 360 console specially decorated pac-man artwork signed tōru iwatani participants pac-man championship edition received mostly positive reviews critics reviewers stating gameplay fresh exciting one best 'exclusive pieces downloadable/casual entertainment available nice see classic remade instead simply repackaged jared rea joystiq called first true sequel pac-man since ms pac-man criticisms include lack multiplayer mode apparent relapse patterns original game metacritic aggregator score 83 user average 8.5/10 ios port criticised microtransaction strategy android port criticised poor controls ign criticised pspminis version due absence online leaderboards inferiority sequel
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Operating systems
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congo bongo also known isometric platform arcade game released sega 1983 player takes role red-nosed safari hunter tries catch ape named bongo hunter seeks bongo exact revenge apparent practical joke bongo set fire hunter tent giving literal hot foot game named peter w. gorrie cfo sega time game rom contains message indicating likely coded least part company ikegami tsushinki congo bongo gameplay similar donkey kong frogger levels viewed isometric perspective oblique perspective ports protagonist offensive abilities must move jump avoid enemies obstacles complete level first level player must avoid coconuts thrown bongo climb series cliffs reach time shaking monkeys try throw hunter mountain second player crosses swamp riding backs swimming hippopotamuses dodging snakes scorpions third level requires player cross plain duck holes avoid charging rhinoceroses fourth involves second swamp crossing lily pads fish hippos player completes four levels hunter gives sleeping bongo hot foot retaliation prank bongo played game begins increased difficulty despite commercial failure initially released congo bongo ported nearly every major gaming platform day including sg-1000 msx intellivision colecovision commodore 64 twice first cartridge later disk ibm pc atari 2600 atari 5200 atari 8-bit family texas instruments ti-99/4a sega ports atari 2600 5200 8-bits commodore 64 cartridge version featured two four levels arcade original colecovision release missing level snake lake intellivision port features 4 game original levels ahoy 1984 stated congo bongo commodore 64 vic-20 fraught problems gameplay repetitive frustrating tedious inconsistent times confusing music got nerves stomped plus whole thing derivative 1984 st. game readers named game worst atari program 1983 even worse notorious e.t extra-terrestrial emulated version original arcade release featured unlockable playstation portable version sega genesis collection sega mega drive collection pal regions version also featured sonic ultimate genesis collection sega mega drive ultimate collection pal regions xbox 360 playstation 3 enhanced remake released playstation 2 sega ages label part sega ages 2500 series vol 23 sega memorial selection
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Computer architecture
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wireless identity theft wireless identity theft also known contactless identity theft rfid identity theft form identity theft described act compromising individual ’ personal identifying information using wireless radio frequency mechanics numerous articles written wireless identity theft broadcast television produced several investigations phenomenon according marc rotenberg electronic privacy information center wireless identity theft pretty serious issue contactless wireless card design inherently flawed wireless identity theft relatively new technique gathering individual ’ personal information rf-enabled cards carried person access control credit debit government issued identification cards cards carry radio frequency identification chip responds certain radio frequencies tags come contact radio waves respond slightly altered signal response contain encoded personal identifying information including card holder ’ name address social security number phone number pertinent account employee information upon capturing ‘ harvesting ’ data one able program cards respond identical fashion ‘ cloning ’ many websites dedicated teaching people well supplying necessary equipment software financial industrial complex migrating use magnetic stripes debit credit cards technically require swipe magnetic card swipe reader number transactions per minute increased transactions processed shorter time therefore making arguably shorter lines cashier academic researchers ‘ white-hat ’ hackers analysed documented covert theft rfid credit card information met denials criticisms rfid card-issuing agencies nevertheless public disclosure information could stolen low-cost jerry-rigged detectors used scan cards mailing envelopes studies also even via drive-by data attacks design security features various cards upgraded remove card owners ’ names data additionally number completely unencrypted card designs converted encrypted data systems issues raised 2006 report importance due tens millions cards already issued credit debit card data could stolen via special low cost radio scanners without cards physically touched removed owner ’ pocket purse carry bag among findings 2006 research study vulnerabilities first-generation rfid-enabled credit cards reports white-hat hackers related issue privacy groups individuals also raised big brother concerns threat individuals aggregated information even tracking movements either card issuing agencies third party entities even governments industry observers stated ‘ ... rfid certainly potential invasive consumer technology ever ’ credit card issuing agencies issued denial statements regarding wireless identity theft fraud provided marketing information either directly criticized implied release study results credit card companies contacted new york times investigative report said removing card holder names data transmitted new second generation rfid cards certain official identification documents issued u.s. government u.s passports passport cards also enhanced driver ’ licenses issued states new york washington contain rfid chips purpose assisting policing u.s. border various security issues identified use including ability black hats harvest identifier numbers distance apply blank counterfeit documents cards thus assuming people ’ identifiers various issues potential issues use identified including privacy concerns although rfid identifier number associated document supposed include personal identification information ... numbers evolve time uses evolve time eventually things reveal information initially expect stated tadayoshi kohno assistant professor computer science university washington participated study government issued documents
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Computer security
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finfisher finfisher also known finspy surveillance software marketed lench solutions plc markets spyware law enforcement channels finfisher covertly installed targets computers exploiting security lapses update procedures non-suspect software company criticized human rights organizations selling capabilities repressive non-democratic states known monitoring imprisoning political dissidents egyptian dissidents ransacked offices egypt secret police following overthrow egyptian president hosni mubarak reported discovered contract gamma international €287,000 license run finfisher software 2014 american citizen sued ethiopian government surreptitiously installing finspy onto computer america using wiretap private skype calls monitor entire family ’ every use computer period months lench solutions plc uk-based branch gamma international ltd andover england germany-based branch gamma international gmbh munich gamma international subsidiary gamma group specializing surveillance monitoring including equipment software training services reportedly owned william louthean nelson shell corporation british virgin islands shell corporation signed nominee director order withhold identity ultimate beneficiary nelson common system companies established offshore august 6 2014 finfisher source code pricing support history related data retrieved gamma international internal network made available internet addition spyware finfisher suite offered gamma intelligence community includes monitoring ongoing developments updating solutions techniques complement developed intelligence agencies software suite company calls remote monitoring deployment solutions ability take control target computers capture even encrypted data communications using enhanced remote deployment methods install software target computers intrusion training program offered includes training methods techniques use company-supplied software suite marketed arabic english german french portuguese russian offered worldwide trade shows offering intelligence support system iss training products law enforcement intelligence agencies finfisher malware installed various ways including fake software updates emails fake attachments security flaws popular software sometimes surveillance suite installed target accepts installation fake update commonly used software code install malware also detected emails software designed evade detection antivirus software versions work mobile phones major brands security flaw apple itunes allowed unauthorized third parties use itunes online update procedures install unauthorized programs gamma international offered presentations government security officials security software trade shows described covertly install finfisher spy software suspects computers using itunes update procedures security flaw itunes finfisher reported exploited first described 2008 security software commentator brian krebs apple patch security flaw three years november 2011 apple officials offered explanation flaw took long patch promotional videos used firm trade shows illustrate infect computer surveillance suite released wikileaks december 2011 2014 ethiopian government found installed finspy computer american citizen via fake email attachment appeared microsoft word document finfisher also found engage politically motivated targeting ethiopia instance photos political opposition group used bait infect users technical analysis malware methods infection persistence techniques published code security blog four parts 12 march 2013 reporters without borders named gamma international one five corporate enemies internet “ digital era mercenaries ” selling products used governments violate human rights freedom information finfisher technology used bahrain reporters without borders together privacy international european center constitutional human rights ecchr bahrain centre human rights bahrain watch filed organisation economic co-operation development oecd complaint asking national contact point united kingdom investigate gamma ’ possible involvement bahrain since research shown finfisher technology used australia austria bahrain bangladesh britain brunei bulgaria canada czech republic estonia ethiopia germany hungary india indonesia japan latvia lithuania macedonia malaysia mexico mongolia netherlands nigeria pakistan panama qatar romania serbia singapore south africa turkey turkmenistan united arab emirates united states venezuela vietnam finfisher capable masquerading legitimate programs mozilla firefox april 30 2013 mozilla announced sent gamma cease-and-desist letter trademark infringement gamma created espionage program entitled firefox.exe even provided version number trademark claims appear legitimate firefox software article pc magazine bill marczak member bahrain watch computer science phd student university california berkeley research finfisher said finspy mobile gamma mobile spyware saw respect desktop version finfisher antivirus alone n't enough bypassed antivirus scans article author sara yin analyst pc magazine predicted antivirus providers likely updated signatures detect finspy mobile according announcements eset finfisher finspy detected eset antivirus software win32/belesak.d trojan security vendors claim products block spyware know detect regardless may launched eugene kaspersky head security company kaspersky lab stated detect malware regardless purpose origin two years statement eugene kaspersky 2012 description technique used finfisher evade kaspersky protection published part 2 relevant blog code security
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Computer security
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bbc archives bbc archives collections documenting bbc ’ broadcasting history including copies television radio broadcasts internal documents photographs online content sheet music commercially available music press cuttings artefacts historic equipment original copies collections permanently retained process digitised collections uploaded onto bbc archives website bbc online viewers see archive one largest broadcast archives world 15 million items bbc archives encompass numerous different archives containing different materials produced acquired bbc earliest material dates back 1890 consists 1 million hours playable material addition documents photographs equipment archives contain 15 million items 60 miles shelving spread several sites stock managed using bar code system help locate material shelves also track material lent bbc says budget managing protecting digitising archive accounts small part bbc overall spend bbc engaging ongoing project digitise archived programme material converting recordings made older analogue formats audio tape videotape film electronic formats compatible modern computer systems much audio-visual material originally recorded formats obsolete incompatible modern broadcast equipment due fact machines used reproduce many formats longer manufactured additionally film audio formats slowly disintegrating digitisation also serves digital preservation programme bbc archive website relaunched online 2008 provided newly released historical material regularly since bbc works partnership british film institute bfi national archives partners working using materials 2012 bbc archive development produced book primarily aimed bbc staff titled 'bbc archive collections archive use book describes bbc archive collections offers guidance around items collections reused online 1963 2010 majority television material nationally networked programmes bbc archive housed archive centre windmill road brentford west london television programmes also stored open university milton keynes bbc nations regional libraries around country late 1990s early 2000s material radio side bbc also stored site condition three windmill road buildings deteriorated years suffered occasional flooding incidents eventually archive relocated new centre perivale park perivale three miles north old site new bbc archive centre opened summer 2010 material successfully moved march 2011 material stored thirteen vaults controlled match best climate material inside named different bbc personality depending content contained addition vaults new editing workrooms added material easily transferred formats well viewed restored building also fitted fire suppression systems protect archive event incident centre total loss archive avoided april 2019 bbc archives employs around 200 staff based archive centre perivale bbc television archive contains 1.5 million tape items well 600,000 cans film material archive holds extensive material approximately mid-1970s onwards important recordings broadcaster retained future recordings date less comprehensively preserved process telerecording originally invented 1947 videotape recording gradually introduced late 1950s onwards due expense tapes recording seen production use recordings subsequently wiped telerecordings junked exceptions early years usually occasions great importance coronation queen elizabeth ii addition numerous programmes time broadcast 'live utilised recording procedure production process earliest item collection 1936 today majority programmes kept including news entertainment drama selection long-running programmes quiz shows remaining material television archive offered british film institute prior disposed bbc sound archive contains archived output bbc radio output widespread recordings exist archive mid-1930s recording programmes speeches kept rebroadcast catalyst launch bbc empire service 1932 subsequent rebroadcast speeches political leaders time convenient different time zones prior broadcast recordings seen false listener avoided recordings made frequently disposed efforts marie slocombe founded sound archive 1937 retained recordings prominent figures country archive became officially appointed sounds recording librarian 1941 today bbc radio output recorded re-use approximately 66 output preserved archives programmes involving guests live performances artists kept whereas programmes dj plays commercially available music sampled kept entirely prior material disposed material offered british library sound archive archive consists number different formats including wax cylinders numerous gramophone records made shellac vinyl well numerous recordings tape cd digital audio tape dat difficulty different formats availability machines required play vinyl records archive 16 inches size require large phonograph units play players wax cylinders dats longer production also 700,00 vinyl records 180,000 78 records 400,000 lp record 350,000 cd archive radio digital archive capturing radio programmes broadcast quality wav files since 2008 1.5 million recordings growing daily wax cylinder collection donated british library sound archive based new bbc archive centre perivale along television archive previously based windmill road brentford bbc written archive contains internal written documents communications corporation launch 1922 present day collections shed light behind scenes workings corporation also elaborate difficulties getting television radio programme air case may archive guidelines state access files post-1980 restricted due current nature files general exception rule documents scripts programme broadcast records written archives located bbc written archive centre caversham berkshire near reading centre houses archive four half miles shelving along reading rooms centre different bbc archives centre opens writers academic researchers higher education bbc photographic library responsible approximately 7 million images dating back 1922 created publicity purposes subsequently kept future use addition programme promotion large number images historic events often incorporate daily news bulletins result half photographic library team work specifically images images kept originals archive digitisation utilised specific image required use image sent digital format copies images also used case images damaged notable due vinegar syndrome popular images archive include colin firth pride prejudice michael parkinson interviewing muhammad ali martin bashir interviewing diana princess wales picture delia derbyshire work radiophonic workshop bbc turn millennium bbc launched bbc archive treasure hunt public appeal recover pre-1980s lost bbc radio television productions original material featuring several popular programmes lost due practice wiping copyright issues technological reasons resolution appeal one hundred productions recovered including men ministry something shout man superman doctor dilemma 'm sorry 'll read hancock half hour 'm sorry n't clue ronnie corbett thing addition recording sessions elton john ringo starr paul simon also peter sellers estate collection donated numerous recordings featuring peter sellers bbc together british film institute open university channel 4 teachers tv formed collaboration named creative archive licence group create copyright licence re-release archived material licence trial launched 2005 notable re-release part bbc news archive programmes made bbc natural history unit creative use public artists teachers encouraged use content create works terms licence restrictive compared copyleft licences use creative archive content commercial endorsement campaigning defamatory derogatory purposes forbidden derivative works released licence content used within uk trial ended 2006 following review bbc trust works released licence withdrawn voices archives former bbc project launched partnership bbc four provided free access audio interviews various notable people professions variety political religious social backgrounds website ceased updated june 2005 concept instead adopted bbc radio 4 collection film interviews various programmes bbc heritage collection newest bbc archives holds variety historic broadcast technology art props merchandise collection created personal collections bequeaths former staff members bbc formal policy heritage collection c.2003 collection includes amongst items bbc one noddy globe clock bbc-marconi type microphone early crystal radio made british broadcasting company marconi/emi camera used early bbc television experiments bbc micro computer selection items used create foley addition broadcast technology art also kept namely portraits bbc director generals well props including original tardis doctor children television puppet gordon gopher heritage collection one permanent home majority objects display either around bbc properties loan museums collections notable museum housing collection national science media museum bradford years bbc used various programme catalogue databases keep record programmes archives internal databases include infax fabric publicly accessible databases include bbc genome bbc programmes
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Databases
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windows server 2019 windows server 2019 latest version server operating system microsoft part windows nt family operating systems windows server 2019 announced march 20 2018 first windows insider preview version released day released general availability october 2 2018 october 6 2018 distribution windows version 1809 build 17763 paused microsoft investigated issue user data deleted in-place upgrade affected systems user profile folder e.g documents music pictures moved another location data left original location windows server 2019 based windows version 1809 codebase removed distribution time re-released november 13 2018 software product life cycle server 2019 reset accordance new release date windows server 2019 version 1903 following new features
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Computer architecture
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metal gear 2 solid snake metal gear 2 solid snake overhead action-adventure stealth video game tagline tactical espionage game initially released konami 1990 msx2 computer platform sequel msx2 version original metal gear solid snake designed written series creator hideo kojima learned existence snake revenge sequel nes developed specifically north american european markets solid snake would officially available japan north american european release playstation 2 2006 included full ports msx2 metal gear games additional content also included metal gear solid 3 released playstation 3 xbox 360 playstation vita given stand-alone re-release japan downloadable game mobile phones wii virtual console set 1999 years events original game solid snake must infiltrate heavily defended territory known zanzibar land rescue kidnapped scientist destroy revised metal gear game significantly evolved stealth-based game system predecessor almost every way introduced complex storyline dealing themes nature warfare nuclear proliferation considered one best 8 bit games ever made metal gear 2 builds upon stealth-based gameplay system predecessor original metal gear player objective infiltrate enemy stronghold avoiding detection soldiers cameras infrared sensors surveillance devices biggest change game done enemy abilities instead remaining stationed one screen like first game enemy soldiers patrol different screens across single map moreover guards expanded field vision 45 degrees along ability turn heads left right see diagonally enemy also detect sounds enemy able hear noise made player punch wall gunshots made without suppressor investigate source sound made also detect sounds made player walking certain surfaces means players need careful surfaces walk player discovered enemy counter displayed upper right side screen go enemy lost track player counter reaches zero alert phase go game return normal player given variety new maneuvers tools help remain undetected complete game example player kneel crawl addition walking allowing player avoid making noise certain terrains pick land mines hide tight spaces desks inside air ducts radar 3x3 grid upper right screen shows player current area center grid red dot enemy soldiers white dots allowing player determine ahead however radar disabled game enters alert phase radar also used mine detector equipped determine locations enemy mines launch stinger missiles onto airborne target many weapons equipment first game brought along new items robotic mice used distract enemies camouflaged mat three different types rations special attributes health carrying capacity increased time boss defeated transceiver also greatly revamped first game well conversations context-sensitive rather simply area-oriented transceiver screen displays faces snake radio contact currently communicating player also talk children living fortress gain new information player penalized loss health kills child areas varied previous msx2 game number puzzles must fulfilled complete game luring carrier pigeon specific kind ration chasing female spy ladies lavatory deciphering secret tap codes gain new frequency numbers msx2 version required use either floppy disk game master ii sram memory save player progress passwords used well absence either complexities eliminated later ports due standardization storage devices memory cards internal hard drives save data solid snake formerly retired foxhound agent hero original metal gear returns playable character new mission rescue kidnapped czechoslovak biologist dr. kio marv forces zanzibarland assisted radio support crew consisting roy kyanbel roy campbell later versions new commanding officer mcdonnell miller survival coach drill instructor george kesler george kasler later versions military strategist yozev norden renamed johan jacobsen later revised versions wildlife expert also assisting on-site horry white holly white later versions cia agent posing journalist natasha marcova gustava heffner later versions stb agent dr. marv bodyguard dr. petrovich madnar drago pettrovich madnar newer versions metal gear designer first game captured along dr. marv also appearing game big boss renegade former commander foxhound grey fox gray fox later versions disappeared following events outer heaven incident bosses installment consist black color black ninja later versions experimental drug-enhanced ninja disbanded nasa project revealed kyle schneider original metal gear running man former olympic runner turned terrorist red blaster explosive expert spetsnaz ultra box four horsemen later version assassination squad specializing confined spaces predator jungle evil later versions jungle warfare expert south african reconnaissance command night sight night fright later versions assassin vietnam uses state art stealth suit renders invisible radar human eye major oil crisis seriously affects global economy late 1990s petrol deposits running faster previous estimates efforts adopt alternative energy sources attempts drill oil fails take slack counter problem czech scientist dr. kio marv bio-engineers new species algae oilix could produce petroleum-grade hydrocarbons little expense effort unveils algae world energy conference prague way demonstration united states kidnapped soldiers zanzibarland central asian country established 1997 successful independence war soviet union nato discovers zanzibarland leaders plan hold world hostage controlling supply oil oilix nuclear warheads pillaged old stockpiles marked dismantling light global efforts toward nuclear disarmament foxhound new commander roy campbell brings solid snake retirement sends zanzibarland rescue dr. marv christmas eve 1999 course mission snake teams holly white cia operative posing journalist gustava heffner stb agent dr. marv bodyguard also reunited dr. drago pettrovich madnar metal gear inventor outer heaven claims kidnapped forced work another metal gear project named metal gear zanzibarland well oversee mass-production smaller non-nuclear-equipped metal gear units snake learns dr. madnar big boss snake former superior survived events first game leads zanzibarland snake heffner dr. madnar head toward zanzibarland main prison heffner killed missile fired metal gear dr. madnar recaptured enemy new metal gear pilot revealed gray fox determined finish mission snake fights zanzibarland elite mercenary force manages reach dr. marv cell snake arrives late finds dr. marv corpse oilix data holly later tips actually died dr. madnar torture addition snake learns madnar volunteered services zanzibarland finish work metal gear revenge scientific community shunning events first game snake incapacitates madnar latter attempts attack snake faces gray fox metal gear eventually destroys mech men later fight hand-to-hand minefield snake finishes tries escape snake meets big boss lost equipment weapons disposal snake forced improvise using items find lighter aerosol fashioning makeshift flamethrower snake defeats big boss second time snake holly escape together deliver oilix formula campbell following success nes version metal gear sold million units north america konami began development sequel platform titled snake revenge designed specifically overseas market hideo kojima directed first msx2 game involved either nes versions plans develop sequel time became reacquainted coworker assigned work snake revenge train ride tokyo coworker revealed involvement project encouraged kojima create sequel end train ride kojima already envisioned basic premise game undergoing business trip sales division konami kojima successfully convinced superiors approve development metal gear 2 solid snake msx division msx2 version metal gear 2 released japan july 20 1990 unlike first msx2 game official english localization produced konami already discontinued sales msx games europe although fan translation later produced 1997 msx hobbyist group g international first port metal gear 2 another platform japanese feature phone version released october 1 2004 downloadable app i-mode ezweb yahoo mobile services version features additions original msx2 version easy mode unlockable boss rush mode clearing main game also include adjustments changes notably replacement portraits used conversation sequences portraits msx2 version modeled real life celebrities new portraits instead designed closely resemble metal gear solid illustrator yoji shinkawa character designs later installments changes would also implemented version included playstation 2 expanded edition released japan 2005 included full ports msx2 metal gear games part newly-added content subsistence would later released north america europe 2006 full english localizations msx2 games marking first time metal gear 2 given international release two msx2 games would later included metal gear solid 3 released playstation 3 xbox 360 2011 playstation vita 2012 metal gear 2 also released wii virtual console exclusively japan march 30 2010 like virtual console games metal gear 2 emulated original msx2 hardware rather ported mobile phone version like subsistence hd edition ports although version game patched use revised character portraits rather original ones game music written konami kukeiha club members tsuyoshi sekito masahiro ikariko mutsuhiko izumi yuko kurahashi tomoya tomita kazuhiko uehara yuji takenouchi cartridge msx2 version carried custom sound chip scc previously employed games nemesis 2 snatcher enhanced music sound effects beyond msx basic capabilities arranged music based metal gear 2 solid snake used vr training disc metal gear solid integral released north america metal gear solid vr missions additionally integral features two hidden tunes based metal gear 2 available via secret codec frequency main game one arranged version theme solid snake arrangement zanzibar breeze listenable contacting codec frequency 140.66 certain locations theme solid snake also made appearance nintendo 2008 crossover fighting game super smash bros. brawl initial release metal gear 2 ranked msx magazine top 30 best selling msx games list six months premiering 1 spot october 1990 issue metal gear 2 solid snake would later receive near universal-acclaim retro game reviewers according paul soth gamespy game surpassed predecessor metal gear every way addition praising gameplay also praised game gripping well written storyline rich characterization quality storytelling made mgs compelling concluded players disappointed great gameplay story remains one best 8 bit games ever made game informer critical game however giving 7 10 wrote order reach pivotal moments game story must endure ridiculous situations solid snake ever seen game focus constant backtracking keycard acquisition makes repetitive concluded diehard fans find experience rewarding best way play game bonus disc metal gear solid 3 subsistence game mechanics sequel metal gear solid despite transition 3d remained largely similar 2d predecessor included plot summaries first two msx2 games accessible special mode previous operations retro gamer regarded metal gear 2 close anyone get playing metal gear solid 2d putting game boy color game released decade later 2000 retro gamer also included among top ten msx games jeremy parish 1up.com referred metal gear solid basically high-spec remake metal gear 2 nickolai adkins 1up also noted much scenario plot elements metal gear 2 recycled metal gear solid ranging snake emerging retirement rescue kidnapped non-soldier personnel beginning escape sequence snake accompanied female accomplice/love interest end ign notes metal gear 2 introduced stealth mechanics making noise attract guards crouching crawling ground disarming mines enemies view cones
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Computer architecture
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imessage imessage instant messaging service developed apple inc launched 2011 supported messages application ios 5 later os x mountain lion later imessage announced scott forstall wwdc 2011 keynote june 6 2011 version messages app ios support imessage included ios 5 update october 12 2011 february 16 2012 apple announced new messages app replacing ichat would part os x mountain lion mountain lion released july 25 2012 october 23 2012 apple ceo tim cook announced apple device users sent 300 billion messages using imessage apple delivers average 28,000 messages per second february 2016 eddy cue announced number imessages sent per second grown 200,000 may 2014 lawsuit filed apple issue user switches apple device non-apple device messages delivered imessage would reach destination november 2014 apple addressed problem providing instructions online tool deregister imessage federal court dismissed suit apple favor march 21 2016 group researchers johns hopkins university published report demonstrated attacker possession imessage ciphertexts could potentially decrypt photos videos sent via service researchers published findings vulnerability patched apple may 3 2016 independent open-source project named piemessage announced app developer eric chee consisting code os x communicates imessage connects android client allowing android client send receive messages june 13 2016 apple announced addition apps imessage service accessible via messages apps apps create share content add stickers make payments within imessage conversations without switch standalone apps one could develop standalone imessage apps extension existing ios apps publishers also create standalone stickers apps without writing code according sensor tower march 2017 imessage app store features nearly 5,000 message-enabled apps imessage allows users send texts documents photos videos contact information group messages internet ios macos users imessage alternative sms mms messaging users devices running ios 5 later send sms setting messages cause message sent via sms sender active internet connection receiver internet connection message stored server connection restored imessage accessible messages app iphone ipad ipod touch running ios 5 later mac running os x mountain lion later owners devices register one email addresses apple additionally iphone owners register phone numbers apple provided carrier supported message sent mobile number messages check apple mobile number set imessage message seamlessly transition imessage sms messages user sent communication aligned right replies people left user see imessage user typing message pale gray ellipsis appears text bubble user reply started also possible start conversation one ios device continue another iphones green buttons text bubbles indicate sms-based communication ios devices blue buttons text bubbles indicate imessage communication imessages encrypted tracked using delivery receipts recipient enables read receipts sender able see recipient read message imessage also allows users set chats two people—a group chat launch ios 10 users send messages accompanied range bubble screen effects holding send button force range effects surfaced users select effect sent receiver imessage protocol based apple push notification service apns —a proprietary binary protocol sets keep-alive connection apple servers every connection unique code acts identifier route used send message specific device connection encrypted tls using client-side certificate requested device activation imessage november 12 2012 chetan sharma technology strategy consulting firm published us mobile data market update q3 2012 noting decline text messaging united states suggested decline may attributed americans using alternative free messaging services imessage 2017 google announced would compete imessage messaging service android messaging november 4 2014 electronic frontier foundation eff listed imessage secure messaging scorecard giving score 5 7 points received points communications encrypted transit communications encrypted keys provider n't access end-to-end encryption past communications secure keys stolen forward secrecy security designs well-documented recent independent security audit missed points users verify contacts identities source code open independent review september 2015 matthew green noted imessage display key fingerprints out-of-band verification users unable verify man-in-the-middle attack occurred post also noted imessage uses rsa key exchange means opposed eff scorecard claims imessage feature forward secrecy august 7 2019 researchers project zero presented 6 “ interaction-less ” exploits imessage could used takeover control user ’ device 6 exploits fixed ios 12.4 released july 22 2019 however stil undisclosed exploits patched future update
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Internet protocols
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runa sandvik runa sandvik computer security expert known proponent strong encryption hired new york times senior director information security march 2016 proponent smartphone messaging application signal acquired first computer fifteen years old studied computer science norwegian university science technology 2014 sandvik married michael auger pair made home washington d.c. sandvik early developer tor anonymity network cooperative facility helps individuals obfuscate internet protocol using access internet sandvik technical advisor freedom press foundation serves review board black hat europe sandvik interviewed edward snowden may 2014 february 2015 sandvik documented efforts retrieve information foia reqests.. sandvik husband auger demonstrated smart rifles remote access remotely hacked 13,000 trackingpoint sniper rifle equipped embedded linux computer according wired magazine used according specifications aiming computer enable novice hit remote targets would otherwise require skilled marksman however manufacturers designed aiming computer wifi capabilities shooter could upload video shots sandvik auger found could initiate unix shell command line interpreter use alter parameters aiming computer relies always miss targets found knowledgeable hacker could use shell acquire root access acquiring root access allowed interloper erase aiming computer software— bricking aiming computer sandvik led efforts make new york times tor onion service allowing times employees readers access newspaper site ways impede intrusive government monitoring
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Computer security
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mkstemp computing codice_1 posix function creating temporary file computer file usually ceases exist program opened file closes terminates accepts argument determines location temporary file prefix generated filename codice_1 added single unix specification function codice_3 deprecated latter carried risk temporary file name could created another thread process within time caller obtains temporary filename attempts create codice_1 suffer problem codice_5 following code example usage codice_1 local variable codice_13 modified codice_1 contain path new file unspecified codice_1 sets errno values errno set event failure codice_1 function generates filename according supplied argument template attempts create repeats process file successfully created opens file returns file descriptor caller data buffer passed function template containing new filename file deleted immediately codice_1 call returns prevent processes opening file still used calling process still valid file descriptor older versions codice_1 created file umask 0666 resulting temporary files readable writable users thus presenting security vulnerability mitigated setting umask manually calling codice_1 newer versions function create file umask 600 owner file may read write
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Computer file systems
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directshow directshow sometimes abbreviated ds dshow codename quartz multimedia framework api produced microsoft software developers perform various operations media files streams replacement microsoft earlier video windows technology based microsoft windows component object model com framework directshow provides common interface media across various programming languages extensible filter-based framework render record media files demand request user developer directshow development tools documentation originally distributed part directx sdk currently distributed part windows sdk formerly known platform sdk microsoft plans completely replace directshow gradually media foundation future windows versions one reason cited microsoft provide much robust support content protection systems see digital rights management microsoft msft becky weiss also confirms 'll notice working media foundation requires work slightly lower level working directshow would still directshow features n't yet media foundation described media foundation article windows vista windows 7 applications use media foundation instead directshow several media related tasks direct predecessor directshow activemovie codenamed quartz originally chartered provide mpeg-1 file playback support windows also intended future replacement media processing frameworks like video windows never designed handle codecs put video frames different order compression process media control interface never fully ported 32-bit environment utilize com quartz team started existing project called clockwork clockwork modular media processing framework semi-independent components worked together process digital media streams previously used several projects including microsoft interactive television mitv project another project named tiger activemovie announced march 1996 released may 1996 bundled beta version internet explorer 3.0 march 1997 microsoft announced activemovie would become part directx 5 suite technologies around july started referring directshow reflecting microsoft efforts time consolidate technologies worked directly hardware common naming scheme directshow became standard component windows operating systems starting windows 98 however available windows 95 installing latest available directx redistributable directx version 8.0 directshow became part mainline distribution directx sdk placed alongside directx apis october 2004 directshow removed main directx distribution relocated directx extras download april 2005 directshow removed entirely directx moved windows sdk starting windows server 2003 sp1 version sdk directx sdk however still required build directshow samples since november 2007 directshow apis part windows sdk includes several new enhancements codecs filter updates enhanced video renderer evr dxva 2.0 directx video acceleration directshow divides complex multimedia task e.g video playback sequence fundamental processing steps known filters filterwhich represents one stage processing datahas input and/or output pins may used connect filter filters generic nature connection mechanism enables filters connected various ways implement different complex functions implement specific complex task developer must first build filter graph creating instances required filters connecting filters together three main types filters rendering process filter graph searches windows registry registered filters builds graph filters based locations provided connects filters together developer request executes i.e. plays pauses etc created graph directshow filter graphs widely used video playback filters implement functions file parsing video audio demultiplexing decompressing rendering well video audio recording editing encoding transcoding network transmission media interactive tasks dvd navigation may also controlled directshow example left right graph contains source filter read mp3 file stream splitter decoder filters parse decode audio rendering filter play raw audio samples filter one pins used connect filter filters every pin functions either output input source data flow one filter another depending filter data either pulled input pin pushed output pin order transfer data filters pin connect one pin agree kind data sending filters built using set c++ classes provided directshow sdk called directshow base classes handle much creation registration connection logic filter filter graph use filters automatically need registered separate directshow registry entry well registered com registration managed directshow base classes however application adds filters manually need registered unfortunately difficult modify graph already running usually easier stop graph create new graph scratch starting directshow 8.0 dynamic graph building dynamic reconnection filter chains introduced help alter graph running however many filter vendors ignore feature making graph modification problematic graph begun processing default directshow includes number filters decoding common media file formats mpeg-1 mp3 windows media audio windows media video midi media containers avi asf wav splitters/demultiplexers multiplexers source sink filters static image filters since associated patented technologies licensed windows license fees required e.g. fraunhofer mp3 codecs mpeg-4 advanced simple profile aac h.264 vorbis containers mov mp4 available 3rd parties incorporating support additional codecs involve paying licensing fees involved codec technology developer patent holder however directshow standard format repertoire easily expanded means variety filters filters enable directshow support virtually container format audio video codec example filters developed ogg vorbis musepack ac3 finally bridge filters simultaneously support multiple formats well functions like stream multiplexing exposing functionality underlying multimedia apis vlc amount work required implement filter graph depends several factors simplest case directshow create filter graph automatically source file url possible developer may able manually create filter graph source file possibly addition custom filter let directshow complete filter graph connecting filters together next level developer must build filter graph scratch manually adding connecting desired filter finally cases essential filter unavailable developer must create custom filter filter graph built unlike main c api quicktime necessary call moviestask loop load media file directshow handles transparent way creates several background threads smoothly play requested file url without much work required programmer also contrast quicktime nothing special required loading url instead local file diskdirectshow filter graph abstracts details programmer although recent developments quicktime including activex control reduced disparity directshow editing services des introduced directx 8.0/windows xp api targeted video editing tasks built top core directshow architecture directshow editing services introduced microsoft windows movie maker includes apis timeline switching services resizing cropping video audio effects well transitions keying automatic frame rate sample rate conversion features used non-linear video editing allowing creation composite media number source audio video streams directshow editing services allow higher-level run-time compositing seeking support graph management still allowing applications access lower-level directshow functions original api c++ directshow editing services accessible microsoft .net compatible language including microsoft visual c microsoft visual basic using third-party code library called directshownet library alternatively entire directshow api including directshow editing services accessed borland delphi 5 6 7 c++ builder 6 later versions minor modifications using third party software library called dspack march 2012 apparently early 2009 microsoft stated directshow editing services api supported may altered unavailable future originally windows 9x directshow used video renderer filter drew images using directdraw 3 could also fall back gdi overlay drawing modes circumstances depending upon visibility video window video card capabilities limited access video window video windows plagued deadlocks caused applications incorrect handling video windows early directshow releases handle playback window hidden applications also reliable way draw caption text graphics top video directshow 6.0 released part directx media introduced overlay mixer renderer designed dvd playback broadcast video streams closed captioning subtitles overlay mixer uses directdraw 5 rendering downstream connection video renderer required window management overlay mixer also supports video port extensions vpe enabling work analog tv tuners overlay capability sending video directly video card via analog link rather via pci bus overlay mixer also supports dxva connections always renders overlay full-screen video tv-out always activated windows xp introduced new filter called video mixing renderer 7 vmr-7 sometimes referred vmr number 7 vmr-7 used directdraw version 7 render video option use gdi drawing main new feature vmr-7 ability mix multiple streams graphics alpha blending allowing applications draw text graphics video support custom effects also featured windowless mode access composited image rendered fixed problems access window handle vmr-7 officially released windows xp directx 9 included vmr-9 version uses direct3d 9 instead directdraw allowing developers transform video images using direct3d pixel shaders available windows platforms part directx 9 redistributable vmr-7 provides windowless mode however unlike overlay mixer vmr-7 support video ports using /3gb boot option may cause vmr-9 fail windows vista windows 7 ship new renderer available media foundation component directshow filter called enhanced video renderer evr evr designed work desktop window manager supports dxva 2.0 available windows vista windows 7 offers better performance better quality according microsoft january 8 2007 microsoft received emmy award streaming media architectures components 58th annual technology engineering emmy awards commanding directshow play file relatively simple task however programming advanced customizations commanding directshow display certain windows messages video window creating custom filters many developers complain difficulties regarded one microsoft complex development libraries/apis developers rarely create directshow filters scratch rather employ directshow base classes base classes often simplify development allowing programmer bypass certain tasks however process may remain relatively complex code found base classes nearly half size entire mfc library result even base classes number com objects directshow contains often overwhelms developers cases directshow api deviates traditional com rules particularly regard parameters used methods overcome difficulties directshow unique com rules developers often turn higher level api uses directshow notably windows media player sdk api provides developer activex control fewer com interfaces deal although directshow capable dynamically building graph render given media type certain instances difficult developers rely functionality need resort manually building filter graphs resulting filter graph variable possible filter graphs change time new filters installed computer directshow also criticized support digital rights management drm however directshow minimal support drm api windows media player sdk significantly reflects microsoft adherence drm codec hell term derived dll hell multiple directshow filters conflict performing task large number companies develop codecs form directshow filters resulting presence several filters decode media type issue exacerbated directshow merit system filter implementations end competing one another registering increasingly elevated priority microsoft ted youmans explained directshow based merit system idea using combination filter ’ merit specific media type/sub type one could reasonably pick right codec every time n't really designed competing merit nuclear arms race tool help troubleshooting codec hell issues usually referenced gspot codec information appliance useful determining codec used render video files avi containers graphedit also help understanding sequence filters directshow using render media file codec hell resolved manually building filter graphs using media player supports ignoring overriding filter merits using filter manager changes filter merits windows registry directshow developer-centric framework api directly offer end-user control encoding content incorporate user interface encoding using installed codecs different formats instead relies developers develop software using api contrast multimedia frameworks quicktime video windows allow end-users perform basic video-related tasks re-encoding using different codec editing files streams convenience offered end-user gui apparent since avi format codecs used video windows still remain use example virtualdub
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Operating systems
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natural language engineering natural language engineering bimonthly peer-reviewed academic journal published cambridge university press covers research software natural language processing aim bridge gap traditional computational linguistics research implementation practical applications potential real-world use original publication theoretical applied aspects computational linguistics journal also contains industry watch emerging trends columns tracking developments field editor-in-chief ruslan mitkov university wolverhampton according journal citation reports journal 2016 impact factor 1.065
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Computational linguistics
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expertization expertization process authentication object usually sort collected individual authority committee authorities expert expert committee examines collectible issues certificate typically including experts apply mark signature item attesting genuineness expertization particularly common valuable philatelic items often forged may unsaleable without
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Computer security
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nokia n93 nokia n93 smartphone nokia part multimedia nseries introduced 25 april 2006 released july 2006 runs symbian os v9.1 s60 3rd edition interface advanced camera phone nokia time release particularly marketed camcorder packed unique swivel design like predecessor nokia n90 n93 improved upon camera capabilities n90 phone 3.2-megapixel camera carl zeiss optics 3x optical zoom first nokia phone well 30 fps 640×480 vga mpeg-4 video recording capability succeeded nokia n93i well coming 2 colors pearl black silver also nokia n93 golf edition preloaded pro session golf software help improve golf skills also edition included memory card preloaded movie mission impossible iii theme although nokia planned release n-gage application n93 alongside n73 n93i never made due memory issues
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Operating systems
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mailwasher mailwasher email filtering software windows detect delete spam user email mail server downloaded user computer mailwasher developed new zealand based company firetrust uses combination user defined filters spam databases bayesian filtering filter works small portion email allows unwanted emails directly deleted user pop3 inbox without downloading email client user computer approach intended prevent downloading spam messages infected malware two versions program free version access single mail account contain bayesian learning filter pro version access multiple accounts additional features
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Computer security
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microsoft edge microsoft edge web browser developed microsoft first released windows 10 xbox one 2015 android ios 2017 macos 2019 edge includes integration cortana extensions hosted microsoft store unlike internet explorer edge support legacy activex bho technologies originally built microsoft edgehtml chakra engines 2019 edge rebuilt chromium-based browser using blink v8 engines part change codenamed anaheim microsoft intends add support windows 7 8 8.1 macos according statcounter edge still lower market share internet explorer market share combined microsoft browsers place second chrome traditional pcs microsoft edge default web browser windows 10 windows 10 mobile xbox one consoles replacing internet explorer 11 internet explorer mobile development release dependent model windows service included windows 10 enterprise long-term servicing branch ltsb builds microsoft initially announced edge would support legacy trident mshtml layout engine backwards compatibility later said due strong feedback edge would use new engine internet explorer would continue provide legacy engine favorites reading list browsing history downloads viewed hub sidebar providing functionality similar internet explorer ’ downloads manager favorites center browser includes integrated adobe flash player internal whitelist allowing flash applets facebook websites load automatically bypassing security controls requiring user activation pdf reader also supports asm.js edge support legacy technologies activex browser helper objects instead uses extension system internet explorer 11 remains available alongside edge windows 10 compatibility remains nearly identical windows 8.1 version use edge engine previously announced edge integrates microsoft online platforms order provide voice control search functionality dynamic information related searches within address bar users make annotations web pages stored shared onedrive ca n't save html pages computers also integrates reading list function provides reading mode strips unnecessary formatting pages improve legibility preliminary support browser extensions added march 2016 build 14291 three extensions initially supported microsoft indicated delay allowing extensions small number due security concerns edgehtml proprietary layout engine developed edge fork trident removed legacy code older versions internet explorer rewritten majority source code support web standards interoperability modern browsers edgehtml written c++ rendering engine first released experimental option internet explorer 11 part windows 10 preview 9926 build edgehtml meant fully compatible webkit layout engine used safari chrome browsers microsoft stated edge–webkit differences bugs ’ interested fixing review engine beta windows 10 build anandtech found substantial benchmark improvements trident particularly javascript engine performance come par google chrome benchmarks focusing performance webgl api found edgehtml perform much better google chrome mozilla firefox edge originally lacked support open media standards webm opus later added edge 14.14291. edge 17 scored 492/555 html5test comparable firefox 59 scored 491/555 lagging behind chrome 66 scored 528/555 chromium-based microsoft edge four channels overall canary dev short developer beta stable microsoft collectively calls canary dev beta channels microsoft edge insider channels december 2014 writing zdnet technology writer mary jo foley reported microsoft developing new web browser codenamed spartan windows 10 said spartan would treated new product separate internet explorer internet explorer 11 retained alongside compatibility early january 2015 verge obtained details surrounding spartan sources close microsoft including reports would replace internet explorer desktop mobile versions windows 10 microsoft officially unveiled spartan windows 10-focused keynote january 21 2015 described separate product internet explorer final name announced spartan first made publicly available default browser windows 10 technical preview build 10049 released march 30 2015 new engine used spartan available windows 10 builds part internet explorer 11 microsoft later announced internet explorer would deprecated windows 10 would use spartan engine april 29 2015 build conference keynote announced spartan would officially known microsoft edge browser logo branding designed maintain continuity branding internet explorer project spartan branding used versions released build 2015 june 25 microsoft released version 19.10149 windows 10 mobile included new brand june 28 version 20.10158 followed desktop versions also including updated branding july 15 microsoft released version 20.10240 final release insiders version rolled consumers july 29 august 12 microsoft started preview program next version microsoft edge released version 20.10512 mobile-users 6 days later followed version 20.10525 desktop users preview received multiple updates november 5 2015 microsoft released version 25.10586 final release edge second public release desktop users november 12 update rolled desktop users xbox one users part new xbox experience update november 18 update windows 10 mobile finally november 19 update also made available part windows server 2016 technical preview 4 november 2017 microsoft released ports edge android ios apps feature integration synchronization desktop version windows 10 pcs due platform restrictions factors ports use layout engine desktop version instead use os-native webkit-based engines april 2018 edge added tab audio muting june 2018 support web authentication specifications added windows insider builds support windows hello external security tokens december 6 2018 microsoft announced intent base edge chromium source code using rendering engine google chrome enhancements developed microsoft also announced versions edge available windows 7 windows 8 macos versions updated frequent basis january 6 2019 microsoft integrated newsguard internet news trustworthiness extension beta version microsoft edge ios android april 8 2019 first chromium-based builds edge windows released public may 20 2019 first chromium-based preview builds edge macos released public marking first time 13 years microsoft browser available mac platform last time microsoft browser available mac platform microsoft internet explorer mac withdrawn january 2006 june 2019 iama post reddit edge developer stated theoretically possible linux version developed future work actually started possibility june 19 2019 microsoft made chromium-powered edge browser available windows 7 windows 8 testing early benchmarks edgehtml engine—included first beta release edge windows 10 build 10049—had drastically better javascript performance trident 7 internet explorer 11 similar performance google chrome 41 mozilla firefox 37 sunspider benchmark edge performed faster browsers benchmarks operated slower google chrome mozilla firefox opera later benchmarks conducted version included 10122 showed significant performance improvement compared ie11 edge back 10049 according microsoft benchmark result iteration edge performed better chrome firefox google octane 2.0 apple jetstream benchmark july 2015 edge scored 377 555 points html5test chrome 44 firefox 42 scored 479 434 respectively internet explorer 11 scored 312 august 2015 microsoft released windows 10 build 10532 insiders included edge 21.10532.0 beta version scored 445 555 points html5test release windows 10 build 14390 insiders july 2016 html5test score browser development version 460 555 points chrome 51 scored 497 firefox 47 scored 456 safari 9.1 scored 370 june 2016 microsoft published benchmark results prove superior power efficiency edge comparison major web browsers opera questioned accuracy provided test results opera came top independent testing pc world confirmed microsoft results however tests conducted linus sebastian contradicted microsoft results instead showing chrome best battery performance august 2015 review windows 10 dan grabham techradar microsoft edge praised performance despite feature-complete state launch andrew cunningham ars technica praised browser tremendously promising much better browser internet explorer ever criticized lack functionality launch thom holwerda osnews criticized edge august 2015 hidden url bar lack user friendliness poor design tab system utterly broken never shipped final release described browser implemented features sort cosmic joke saying infuriating n't even begin describe data august 2015 weeks release showed user uptake edge low 2 overall computer users using new browser among windows 10 users usage peaked 20 dropped 14 august 2015 october 2015 security researcher published report outlining bug edge inprivate mode causing data related visited sites still cached user profile directory theoretically making possible others determine sites visited bug gained mainstream attention early february 2016 fixed cumulative update february 9 microsoft planned switch chromium edge engine faced mixed reception move increase consistency web platform compatibility major browsers reason move attracted criticism reduces diversity overall web browser market increases influence google developer blink layout engine overall browser market microsoft ceding independently-developed browser engine
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Operating systems
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meaningcloud meaningcloud software service product enables users embed text analytics semantic processing application system previously branded textalytics meaningcloud extends concept semantic api cloud-based framework makes integration semantic processing system something close plug-and-play experience meaningcloud available saas mode on-premises advanced apis provide functionality optimized diverse applications ease use addition customization integration capabilities offer fast learning curve short time obtain results meaningcloud brand meaningcloud llc wholly owned subsidiary meaningcloud europe s.l. previously known daedalus daedalus founded 1998 jose c gonzalez colleagues spin-off artificial intelligence research lab technical university madrid
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Computational linguistics
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empire city 1931 also known street fight shooting gallery game originally released arcades 1986 game players taking mafia 1931 new york city gunning mobsters one one versions game released family computer 1987 msx 1988 acclaim advertised release nintendo entertainment system western regions console version remained exclusive japan seibu kaihatsu eventually released follow-up game dead angle game set 1931 new york city player controls young man must avenge family members killed gang shootout period several months targets mobsters culminating mafia boss players move crosshair around screen aim shoot mobsters one time lurk around various areas including street windows arrow appears helps direct players location next mobster onscreen players set amount time find shoot enemy time running speech bubble appears counting last seconds timer timer reaches zero player shot screen pans location enemy defend button available last resort avoid shot players replenish ammo shooting hidden ammunition boxes get bonus points shooting gold bars levels cleared set number mobsters eliminated game final level player one opportunity assassinate mob boss walks front windows building final level completed game loops back beginning famicom version largely player progress restored time famicom version using password system four numbers and/or letters review computer video games said game fast moving lots action called unusual addictive game bound winner
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Computer architecture
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artificial solutions artificial solutions multinational technology company develops technology enable enterprises rapidly build conversational ai systems allow users converse applications electronic devices free-format natural language using speech text touch gesture delivered teneo conversational ai development analytics platform company ’ technology allows business users developers collaborate creating conversational applications 35 languages running os device without need specialist linguistic skills company natural language solutions deployed wide range industries including automotive finance energy entertainment telecoms public sector retail travel company founded 2001 went public 2019 reverse takeover indentive ab artificial solutions listed nazdaq first north stock exchange ticker asai artificial solutions founded stockholm 2001 friends johan åhlund johan gustavsson michael söderström create interactive web assistants using combination artificial intelligence natural language processing though åhlund initially took persuading thought sounded ridiculous talking virtual agent internet company expanded development online customer service optimization products 2005 several offices throughout europe supporting development sales online virtual assistants artificial solutions placed visionary latest gartner magic quadrant crm web customer service applications 2006 artificial solutions acquired kiwilogic german software house creating virtual assistants elbot artificial solutions ’ test-bed explore psychology human-machine communication loebner prize 2008 closest contestant annual competition based turing test reach 30 threshold fooling 25 human judges change management 2010 company started focus basis technology natural language interaction launched teneo platform allows people hold humanlike intelligent conversations applications services running electronic devices 2013 artificial solutions launched indigo mobile personal assistant able operate remember context conversation across different platforms operating systems new round funding announced june 2013 9.4m used support expansion us market february 2014 artificial solutions announced teneo network knowledge patented intelligent framework enables users interact using natural language private shared public ecosystem devices also known internet things lawrence flynn remains ceo chris bushnell cfo
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Computational linguistics
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certified senders alliance certified senders alliance initiated eco german direct marketing association ddv constitutes central whitelist since 2004 csa whitelist positive list email bulk senders isps email-providers participating whitelist solicited email need enter isps spamfilter longer chances false positives legitimate email erroneously tagged spam reduced bulk email senders apply certification whitelist comply admission criteria closed-loop authentication providing masthead revocation unsubscribe functions clear identity sole technological control servers used send emails applicants submit samples services prove csa criteria implemented also pay fee applications reviewed certification committee date 100 providers participate whitelist csa cooperates eco complaints office internet users report breaches csa criteria csa frequently discloses members breached csa criteria excluded whitelist among providers joined csa whitelist aol arcor freenet host europe group microsoft vodafone kabel deutschland pironet united internet companies gmx 1 1 internet web.de well yahoo yandex year csa holds congress csa summit current legal requirements regarding email marketing discussed general data protection regulation well technical challenges trends
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Computer security
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compuserve compuserve compuserve information service also known initialism cis first major commercial online service provider united states described 1994 oldest big three information services others prodigy america online dominated field 1980s remained major influence mid-1990s peak early 1990s cis known online chat system message forums covering variety topics extensive software libraries computer platforms series popular online games notably megawars iii island kesmai also known introduction gif format pictures gif exchange mechanism 1997 17 years h r block acquired cis parent announced desire sell company complex deal worked worldcom acting broker resulting cis sold aol 2015 verizon acquired aol including compuserve division 2017 verizon completed acquisition yahoo compuserve became part verizon newly formed oath inc. subsidiary compuserve founded 1969 compu-serv network inc. columbus ohio subsidiary golden united life insurance focus business customers though golden united founder harry gard sr. son-in-law jeffrey wilkins widely miscredited first president compuserve first president john r. goltz wilkins replaced goltz ceo within first year operation goltz wilkins graduate students electrical engineering university arizona early recruits university included sandy trevor inventor compuserve cb simulator chat system doug chinnock larry shelley company objectives twofold provide in-house computer processing support golden united life insurance develop independent business computer time-sharing industry renting time pdp-10 midrange computers business hours spun separate company 1975 trading nasdaq symbol cmpu concurrently company recruited executives shifted focus offering time-sharing services customers wrote applications one focused packaged applications first new executives robert tillson left service bureau corporation subsidiary control data corporation originally formed division ibm become compuserve executive vice president marketing recruited charles mccall followed jeff wilkins ceo later became ceo medical information firm hbo co. maury cox became ceo departure mccall robert massey followed cox ceo 1977 compuserve board changed company name compuserve incorporated 1979 began offering dial-up online information service consumers 1980 h r block acquired compuserve aol entry pc market 1991 marked beginning end cis aol charged 2.95 hour versus 5.00 hour compuserve aol used freely available gui-based client compusserve n't free supported subset system functionality response cis lowered hourly rates several occasions subsequently aol switched monthly subscription instead hourly rates active users aol much less expensive late 1994 compuserve offering unlimited use standard services including news sports weather ... limited electronic mail 8.95 per month new york times called probably best deal cis number users grew peaking april 1995 3 million worldwide point aol 20 million users united states alone peak 27 million due customers leaving lower-cost offerings 1997 number users leaving online services dialup internet service providers reaching climax original 1969 dial-up technology fairly simple—the local phone number cleveland example line connected time-division multiplexer connected via leased line matched multiplexer columbus connected time-sharing host system earliest buildups line terminated single machine compuserve host different numbers used reach different computers later central multiplexers columbus replaced pdp-8 minicomputers pdp-8s connected dec pdp-15 minicomputer acted switches phone number tied particular destination host finally compuserve developed packet switching network implemented dec pdp-11 minicomputers acting network nodes installed throughout us later countries interconnected time compuserve network evolved complicated multi-tiered network incorporating asynchronous transfer mode atm frame relay fr internet protocol ip x.25 technologies 1981 times explained compuserve technology one sentence compuserve offering video-text-like service permitting personal computer users retrieve software mainframe computer telephone lines new york times described international big three noted reached local phone call 700 cities compuserve also world leader commercial services one financial services group collected consolidated financial data myriad data feeds including compustat disclosure i/b/e/s well price/quote feeds major exchanges compuserve developed extensive screening reporting tools used many investment banks wall street 1979 radio shack marketed residential information service micronet home users accessed computers evening hours compuserve computers otherwise idle success prompted compuserve drop micronet name favor compuserve origin approximately concurrent source services operating early 1979 first online services micronet made popular issue 2 commodore disk user included instructions connect run micronet programs mid-1980s compuserve one largest information networking services companies largest consumer information service operated commercial branches 30 us cities selling primarily network services major corporations throughout united states consumer accounts could bought computer stores box instruction manual trial account login awareness service extremely high 1987 consumer side would 50 compuserve revenues corporate culture entrepreneurial encouraging skunkworks projects alexander sandy trevor secluded weekend writing cb simulator chat system soon became one cis popular features instead hiring employees manage forums contracted sysops received compensation based success forum boards libraries chat areas july 1980 working associated press compuserve began hosting text versions columbus dispatch new york times virginian-pilot ledger star washington post san francisco examiner san francisco chronicle los angeles times added 1981 additional newspapers followed although accessing articles newspapers made 5 compuserve traffic reading entire newspaper using method impractical text 0.20 print edition newspaper would take two six hours download cost 5 per hour 6 p.m. another major unit compuserve compuserve network services formed 1982 generate revenue selling connectivity nationwide packet network compuserve built support time-sharing service compuserve designed manufactured network processors based dec pdp-11 wrote software ran network often erroneously called x.25 network compuserve network implemented mixture standardized proprietary layers throughout network one proprietary layers called adaptive routing adaptive routing system implemented two powerful features one network operated entirely self-discovery mode new switch added network connecting neighbor via leased telephone circuit new switch discovered absorbed network without explicit configuration change network configuration needed add remove connections network would automatically reconfigure second feature implemented adaptive routing often talked network engineering circles implemented cns establishing connection paths basis real-time performance measurements one circuit became busy traffic diverted alternative paths prevent overloading poor performance users cns network based x.25 protocol network presented standard x.25 interface outside world providing dialup connectivity corporate hosts allowing compuserve form alliances private networks tymnet telenet among others gave compuserve largest selection local dial-up phone connections world era network usage charges expensive still lower long distance charges networks permitted compuserve access still locations including international locations usually substantial connect-time surcharges common early 1980s pay 30-per-hour charge connect compuserve time cost 5 6 per hour factoring connect-time surcharges resulted company nicknamed compuspend compu erve ci cns primary supplier dial-up communications credit-card authorizations 20 years competence developed long relationship visa international peak line business compuserve carried millions authorization transactions month representing several billion dollars consumer purchase transactions many businesses always-on connection extravagance dialup option made better sense today service remains operation deeply embedded within verizon see competitors remaining market company notable introducing number online services personal computer users compuserve began offering electronic mail capabilities technical support commercial customers 1978 name infoplex also pioneer real-time chat market cb simulator service introduced february 21 1980 first public commercial multi-user chat program compuserve also introduced number online games around 1981 compuserve introduced compuserve b protocol file-transfer protocol allowing users send files later expanded higher-performance b+ version intended downloads cis although b+ protocol widely supported software used default time cis b+ protocol later extended include host-micro interface hmi mechanism communicating commands transaction requests server application running mainframes hmi could used front end client software present gui-based interface cis without use error-prone cli route commands compuserve began expand reach outside united states entered international arena japan 1986 fujitsu nissho iwai developed japanese-language version compuserve called nifty-serve 1989 1993 compuserve hong kong launched joint venture hutchison telecom able acquire 50,000 customers dialup isp frenzy 1994 1995 fujitsu compuserve co-developed worldsaway interactive virtual world 2014 original world launched compuserve 1995 known dreamscape still operating late 1980s possible log compuserve via worldwide x.25 packet switching networks bridged onto compuserve existing us-based network gradually introduced direct dial-up access network many countries economical solution network expansion compuserve also extended marketing commercial services opening branches london munich compuserve first online service offer internet connectivity albeit limited access early 1989 connected proprietary e-mail service allow incoming outgoing messages exchanged internet-based e-mail addresses early 1990s compuserve hundreds thousands users visiting thousands moderated forums forerunners discussion sites web like web many forums managed independent producers administered forum recruited moderators called sysops among many hardware software companies offered customer support broadened audience primarily business users technical geek crowd migrated byte magazine apos bix online service special forums special groups many relatively large premiums premium data bases charges 7.50 time enter search request 1992 compuserve hosted first known wysiwyg e-mail content forum posts fonts colors emoticons encoded 7-bit text-based messages via third party product navcis dvorak development running dos windows 3.1 windows 95 operating systems navcis included features offline work similar offline readers used bulletin board systems allowing users connect service exchange new mail forum content largely automated fashion run complete user edited messages locally offline mode system also allowed interactive navigation system support services like chat system many services remained text based compuserve later introduced compuserve information manager cim compete directly aol unlike navigator cim tuned online work used point-and-click interface similar aols later versions interacted hosts using hmi communications protocol areas service support hmi older text-based interface could used wincim also allowed caching forum messages news articles e-mail reading posting could performed off-line without incurring hourly connect costs previously luxury navcis autosig tapcis applications power users one big advantages cis internet users could purchase services software compuserve members using compuserve account early 1990s hourly rate fell 10 hour 1.95 hour march 1992 launched online signups credit card based payments desktop application connect online check emails april 1995 compuserve topped three million members still largest online service provider launched netlauncher service providing www access capability via spry mosaic browser aol however introduced far cheaper flat-rate unlimited-time advertisement-supported price plan us compete compuserve hourly charges conjunction aol marketing campaigns caused significant loss customers compuserve responded similar plan 24.95 per month late 1997 world wide web grew popularity general public company company closed once-busy compuserve customer support forums offer customer support larger audience directly company websites area compuserve forums time could address yet introduced universal www access 1992 compuserve acquired mark cuban company microsolutions 1997 compuserve began converting forums proprietary host-micro interface hmi html web standards 1997 change discontinued text based access forums forums accessible web well thorough compuserve proprietary hmi protocol 2004 compuserve discontinued hmi converted forums web access forums remained active compuserve.com end 2017 compuserve made number acquisitions history acquired h r block compuserve special military section help veterans military brats members non-members 1994-founded military brats america mba connect later mba established bulletin board within vietnam veterans america aol portal widespread adoption internet world wide web united kingdom first national major-brands online shopping service developed uk arm compuserve/cis part proprietary closed-system collection consumer services andrew gray set compuserve uk operations european arm us company back late 1980s later became company european general manager david gilroy compuserve uk director customer services service continued grow offered technical support managed suzanne gautier sales managed colin campbell service proposed paul stanfield independent business-to-consumer electronic commerce consultant martin turner product marketing director cis uk august 1994 turner agreed project started september rapid market research product development sales online space major uk retail catalogue companies included wh smith tesco virgin/our price great universal stores/gus interflora dixons retail past times pc world retailer innovations service launched thursday 27 april 1995 paul stanfield purchase book wh smith shop repeat first formal test service 9 february 1995 included secure payment subsequent fulfilment order royal mail postal delivery interactive media retail group imrg uk industry association e-retailing believes uk first national shopping service secure online transaction purchase wh smith book compuserve centre approximately 1,000,000 uk customers access shops time british retailers first major exposure medium retailers joined service soon included sainsbury wine jaguar cars branded lifestyle goods compuserve uk commissioned writer sue schofield produce 'retail pack including new uk compuserve book free cd-rom containing cis software access service compuserve closed private network system slow react rapid development open world wide web long major uk retailers started develop web sites independently compuserve original compuserve user ids consisted seven octal digits form 7xxxx xx legacy pdp-10 architecture later eight nine octal digits form 7xxxx xxx 7xxxx xxxx finally ten octal digits form 1xxxxx xxxx generated advance issued printed snap paks 1989 compuserve users email access internet using user id form xxxxx.xxxx compuserve.com comma original id replaced period 1996 users allowed create alias internet e-mail address could also used personal web page longest-term members allowed first choice new addresses 1998 users offered option switching mailbox newer system provided pop3 access via internet internet mail program could used current compuserve email addresses look like xxxxxx cs.com users compuserve 2000 service compuserve long history offering custom portal compuserve information service airline industry beginning 1970s compuserve offered customized version service allows pilots flight attendants bid flight schedules airline compuserve offered customized solutions industries well including service called compuserve lawyers another african-american culture arts forum long largest online service provider 1987 compuserve 380,000 subscribers compared 320,000 dow jones news/retrieval 80,000 source 70,000 genie compuserve 3 million worldwide users peak compared aol 27 million early 1999 many home uses switched standard dial-up internet access compuserve slipped 2 million largely business professional users one popular use compuserve 1980s file exchange particularly pictures indeed 1985 hosted perhaps first online comic world witches stitches compuserve introduced simple black-and-white image format known rle run-length-encoding standardize images could shared among different microcomputer platforms introduction powerful machines universally supporting color compuserve introduced much capable gif format invented steve wilhite gif went become de facto standard 8-bit images internet early mid-1990s compuserve outside telecommunications attorney randy may led appeals federal communications commission fcc exempt data networks pay common carrier access charge ccac levied telephone local exchange carriers primarily baby bell companies long distance carriers primary argument data networking brand new industry country would better served exposing important new industry aberrations voice telephone economics ccac mechanism used subsidize cost local telephone service long distance revenue fcc agreed compuserve position consequence dial-up networking united states whether private networks public internet much less expensive otherwise would 1991 compuserve sued defamation one early cases testing application traditional law internet cubby v. compuserve although defamatory content posted one forums compuserve liable content unaware content exercise editorial control forum november 1993 copyright infringement lawsuit regarding 900 songs settled two years later payment divided among publishers whose songs involved 1995 compuserve blocked access sex-oriented newsgroups pressured bavarian prosecutors 1997 compuserve reopened newsfeeds felix somm former managing director compuserve germany charged violating german child pornography laws material compuserve network carrying germany first convicted november 1997 another hearing sentenced two years probation may 28 1998 cleared appeal november 17 1999 wow styled wow online service run compuserve starting march 1996 closure announced november year effective end january 1997 among promised features first internet service offered monthly 'unlimited rate 17.95 software bugs random shutdowns service loss email messages limited service small loyal fan base closed january 31 1997 several class-action lawsuits filed claiming wow sold stockholders false misleading information wow supposed make company competitive aol proprietary service aimed families novice computer users late-1995 announced wow information service supposed commence microsoft windows 95 sr2 first include internet explorer knowing bundling browser would considered anti-competitive microsoft also planned bundle installers several major isps windows compuserve software ready aol retained wow.com domain name since acquired compuserve kept dormant shutdown wow 2007 mid-2007 aol considered moving digg-style news aggregator hosted netscape.com wow.com ultimately moving propeller.com toward end year aol reportedly working using domain social networking service focused popular online role-playing game world warcraft october 2010 2015 shutdown moved subdomain joystiq wow.com domain simultaneously relaunched deal day site similar groupon however site also short-lived shutting late 2011 january 2019 wow.com search engine powered bing using back-end aol search part oath inc battle customers aol compuserve became one handing customers back forth using free hours enticements technical problems—the thousands new generation u.s. robotics dialup modems deployed network would crash high call volumes first time decades compuserve began losing money prodigious rate effort code-named red-dog initiated convert compuserve long-time pdp-10 based technologies servers based intel x86 architectures microsoft windows nt operating system parent h r block going management changes time beginning retirement ceo henry bloch series successors ensured 1997 h r block announced intention divest compuserve number potential buyers came forefront terms offered unacceptable management aol likely buyer made several offers purchase compuserve using aol stock h r block management sought cash least higher quality stock february 1998 john w. sidgmore vice chairman worldcom former ceo uunet devised complex transaction ultimately met goals parties step one worldcom purchased shares compuserve 1.2 billion wcom stock next day worldcom sold compuserve information service portion company aol retaining compuserve network services portion aol turn sold networking division advanced network services ans worldcom sidgmore said point world balance accountants taxes aol information services worldcom networks worldcom newly acquired compuserve network services renamed worldcom advanced networks continued operate discrete company within worldcom combined aol network subsidiary ans existing worldcom networking company called gridnet 1999 worldcom acquired mci became mci worldcom worldcom advanced networks briefly became mci worldcom advanced networks mci worldcom advanced networks ultimately absorbed uunet soon thereafter worldcom began spiral bankruptcy re-emerging mci 2006 mci sold verizon result organization networking business within compuserve part verizon business process splitting compuserve two major businesses compuserve information services compuserve network services worldcom aol desired make use compuserve name trademarks consequently jointly owned holding company formed purpose hold title various trademarks patents intellectual property license intellectual property cost worldcom verizon aol 2015 verizon acquired aol compuserve original properties reunited verizon september 2003 compuserve information service become division aol added compuserve basic product lines selling via netscape.com cis positioned value market-provider several million customers part aol web products group recent u.s. versions compuserve client software — essentially enhanced web browser — used gecko layout engine developed mozilla within derivative aol client using aol dialup network previous compuserve service offering re-branded compuserve classic remained available us also countries compuserve 2000 offered uk germany compuserve 2000 introduced 1999 withdrawn 2001 failure german market compuserve classic service remained compuserve germany introduced products dialup dsl internet access client software called compuserve 4.5 light january 2007 compuserve e-mail members windows vista supported suggested switching aol-branded service like many older programs however compuserve client software run windows vista compatibility mode july 2007 compuserve pacific announced cessation august 31 2007 september 2007 announced compuserve france would close operations november 30 2007 pacific region australia new zealand etc fujitsu australia ran compuserve pacific franchise 1998 35,000 customers towards end operations area thought far fewer compuserve pacific pricing plans changed since 1998 e.g. 14.95 2 hours per month july 2008 compuserve germany informed customers would close operations july 31 2008 legacy service compuserve classic would affected decision compuserve forums tightly linked compuserve channels compuserve.com currently runs slightly trimmed-down version now-defunct netscape.com web portal latter shut 2006 compuserve announced april 15 2009 compuserve classic would longer operate internet service provider would close june 30 2009 compuserve classic services including ourworld web pages taken offline date compuserve classic e-mail users would able continue using compuserve e-mail addresses via new e-mail system aol used compuserve brand compuserve 2000 rebranded low-cost offering closed 2011 including mac compuserve dialer low-cost dialup isp became web portal compuserve announced november 2017 compuserve forums would shut december 15 2017 36 years since compuserve forums begun 1981 moved forumania elsewhere time several graphical user interfaces written accessing compuserve unlike aol gave free new york times wrote compuserve ought give away among names wincim tapcis navcis time subscribers paid timed access well long distance calls countries spend time online reading replying messages goal bypass compuserve wincim interface streamline sending pre-written email forum postings user written offline receiving new messages downloading requested files logging compuserve tapcis access program compuserve information service automated ms-dos-based software application sped access management compuserve email accounts forum memberships pc users 1981 2004 advances compuserve technology rendered obsolete described archaic-looking .. remains powerful tool accessing compuserve forums tapcis written borland turbo pascal howard banner marketing executive wilmington delaware joined compuserve 1981 died melanoma june 1990 aged 44 software shareware retailed community users continued maintain website since able issue administrative commands tapcis preferred tool dozens compuserve system operators sysops regarding wincim predecessor cim pc magazine wrote give broader view available using easily navigate service explicitly caution unlike tapcis wo n't save money ... could actually take longer retrieve answer messages ... without although ozcis ozwin windows-based successor described free personal use pc magazine shareware like wincim tapcis navcis programming done steve sneed using pascal-like delphi software published ozarks west software inc. like tapcis sysop features moving deleting messages administering file libraries flagging users giving/denying sysop rights unlike offline readers tapcis navcis added proprietary ways formatting text colors fonts attributes ozwin always remained plain text never displayed custom styles may 2005 compuserve discontinued access ozcis tapcis forums compuserve autosig free unlike wincim tapcis navcis ozcis/ozwin
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Internet protocols
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high-level shading language high-level shader language high-level shading language hlsl proprietary shading language developed microsoft direct3d 9 api augment shader assembly language went become required shading language unified shader model direct3d 10 higher hlsl analogous glsl shading language used opengl standard similar nvidia cg shading language developed alongside hlsl shaders enable profound speed detail increases well many special effects 2d 3d computer graphics hlsl programs come six forms pixel shaders fragment glsl vertex shaders geometry shaders compute shaders tessellation shaders hull domain shaders raytracing shaders ray generation shaders intersection shaders hit/closest hit/miss shaders vertex shader executed vertex submitted application primarily responsible transforming vertex object space view space generating texture coordinates calculating lighting coefficients vertex tangent binormal normal vectors group vertices normally 3 form triangle come vertex shader output position interpolated form pixels within area process known rasterization pixels comes pixel shader whereby resultant screen colour calculated optionally application using direct3d 10/11/12 interface direct3d 10/11/12 hardware may also specify geometry shader shader takes input vertices primitive triangle/line/point uses data generate/degenerate tessellate additional primitives change type primitives sent rasterizer d3d11.3 d3d12 introduced shader model 5.1 later 6.0 gpus listed hardware first supported given specifications manufacturers generally support lower shader models drivers note games may claim require certain directx version n't necessarily require gpu confirming full specification version developers use higher directx api version target lower-direct3d-spec hardware instance directx 9 exposes features directx7-level hardware directx7 targeting fixed-function l pipeline 32 64 executed instructions means 32 texture instructions 64 arithmetic instructions
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Operating systems
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streams computer networking streams native framework unix system v implementing character device drivers network protocols inter-process communication framework stream chain coroutines pass messages program device driver pair programs streams originated version 8 research unix streams capitalized streams design modular architecture implementing full-duplex i/o kernel device drivers frequent uses developing terminal i/o line discipline networking subsystems system v release 4 entire terminal interface reimplemented using streams important concept streams ability push drivers custom code modules modify functionality network interface device together form stack several drivers chained together order streams based streams i/o subsystem introduced eighth edition research unix v8 dennis ritchie used terminal i/o subsystem internet protocol suite version yet called streams capitals fit new functionality existing device i/o system calls open close read write ioctl application limited terminal i/o protocols providing pipe-like i/o semantics i/o system ported system v release 3 robert israel gil mcgrath dave olander her-daw che maury bach part wider framework intended support variety transport protocols including tcp iso class 4 transport sna lu 6.2 npack protocol used rfs first released network support utilities nsu package unix system v release 3 port added putmsg getmsg poll system calls nearly equivalent purpose send recv select calls berkeley sockets putmsg getmsg system calls originally called send recv renamed avoid namespace conflict system v release 4 streams extended used terminal i/o framework pipes providing useful new functionality like bidirectional pipes file descriptor passing port unicos also produced eric s. raymond quotes ritchie saying complexity system v streams compared v8 streams streams means something different shouted concurrent system v release 3 port developed protocol-independent streams message passing guidelines link network transport layers osi model layers 2-4 due typically close implementation coupling network transport protocols given protocol stack typical practice implementing layers 5-7 outside kernel link transport layer streams service interfaces later standardized x/open conjunction transport message passing model transport layer interface later adopted x/open transport interface defined provide transport protocol-independent api application development also library supporting session presentation application layers defined later standardized open group streams required conformance single unix specification versions 1 unix 95 2 unix 98 result refusal bsd linux developers provide streams marked optional posix compliance austin group version 3 unix 03 posix.1-2008 tc1 ieee std 1003.1 2013 edition designated streams 'marked obsolescent meaning said functionality may removed future version specification however specific definition 'obsolescent used also says strictly conforming posix applications 'shall use obsolescent features version 7 unix command connected terminal keyboard screen keyboard printer mechanism called line discipline would buffer single line input i.e. wait user press return key sending input program processing allowed simple error correction streams replaced set processing modules organized linear chain allowed bidirectional communication neighboring modules programs could push new module onto one end chain change behavior terminal character device ritchie gives example chain terminal module chained datakit network module achieve remote login network aside characters bytes going program device vice versa streams could carry control messages hangup drop connection ioctl messages streams could also used inter-process communication connecting two processes pseudoterminals possibility mpx window system blit graphics terminal could display multiple terminal emulator windows window process communicated window system pseudoterminal line discipline driver installed sending typed characters receiving text graphics display control signals designated user wish switch windows close actual streams modules live kernel space unix installed pushed removed popped ioctl system call example install aforementioned line discipline file descriptor codice_1 referring terminal device one would write c perform input/output stream one either uses codice_2 codice_3 system calls regular file descriptors set streams-specific functions send control messages ritchie admitted regretting implement streams kernel rather processes felt compelled reasons efficiency later plan 9 implementation implement modules user-level processes streams mostly used system v unix world however implementations exist linux include streams functionality without third-party add-ons caldera pushed streams included linux ca 1998 support netware linux rejected outright linux kernel developers technical grounds mainly performance compatibility layers linux operating systems convert streams operations sockets early possible implementation used caldera lis company called gcom later figured legal battles caldera successor sco group linux sco claiming linux streams infringed believed copyrights system v
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Operating systems
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overclocking computing overclocking practice increasing clock rate computer exceed certified manufacturer commonly operating voltage also increased maintain component operational stability accelerated speeds semiconductor devices operated higher frequencies voltages increase power consumption heat overclocked device may unreliable fail completely additional heat load removed power delivery components meet increased power demands many device warranties state overclocking and/or over-specification voids warranty purpose overclocking increase operating speed given component normally modern systems target overclocking increasing performance major chip subsystem main processor graphics controller components system memory ram system buses generally motherboard commonly involved trade-offs increase power consumption heat fan noise cooling targeted components components designed margin safety deal operating conditions outside manufacturer control examples ambient temperature fluctuations operating voltage overclocking techniques general aim trade safety margin setting device run higher end margin understanding temperature voltage must strictly monitored controlled user examples operating temperature would need strictly controlled increased cooling part less tolerant increased temperatures higher speeds also base operating voltage may increased compensate unexpected voltage drops strengthen signalling timing signals low-voltage excursions likely cause malfunctions higher operating speeds modern devices fairly tolerant overclocking devices finite limits generally given voltage parts maximum stable speed still operate correctly past speed device starts giving incorrect results cause malfunctions sporadic behavior system depending pc context usual result system crash subtle errors go undetected long enough time give unpleasant surprises data corruption incorrectly calculated results worse writing storage incorrectly system failing certain specific tasks general usage internet browsing word processing appear fine application wanting advanced graphics crashes system point increase operating voltage part may allow headroom increases clock speed increased voltage also significantly increase heat output point limit imposed ability supply device sufficient power user ability cool part device maximum voltage tolerance achieves destructive failure overzealous use voltage and/or inadequate cooling rapidly degrade device performance point failure extreme cases outright destroy speed gained overclocking depends largely upon applications workloads run system components overclocked user benchmarks different purposes published conversely primary goal underclocking reduce power consumption resultant heat generation device trade-offs lower clock speeds reductions performance reducing cooling requirements needed keep hardware given operational temperature knock-on benefits lowering number speed fans allow quieter operation mobile devices increase length battery life per charge manufacturers underclock components battery-powered equipment improve battery life implement systems detect device operating battery power reduce clock frequency accordingly underclocking almost always involved latter stages undervolting seeks find highest clock speed processor stably operate given voltage overclocking seeks maximize clock speed temperature power constraints underclocking seeks find highest clock speed device reliably operate fixed arbitrary power limit given device may operate correctly stock speed even undervolted case underclocking would employed reductions voltage finally destabilizes part point user would need determine last working voltage speed satisfactorily lowered power consumption needs – performance must sacrificed lower clock chosen underclock testing progressively lower voltages would continue point lower bound device fails function and/or supporting circuitry reliably communicate part underclocking undervolting would attempted desktop system operate silently home entertainment center potentially offering higher performance currently offered low-voltage processor offerings would use standard-voltage part attempt run lower voltages attempting keep desktop speeds meet acceptable performance/noise target build also attractive using standard voltage processor low voltage application avoided paying traditional price premium officially certified low voltage version however like overclocking guarantee success builder time researching given system/processor combinations especially time tedium performing many iterations stability testing need considered usefulness underclocking like overclocking determined processor offerings prices availability specific time build underclocking also sometimes used troubleshooting overclocking become accessible motherboard makers offering overclocking marketing feature mainstream product lines however practice embraced enthusiasts professional users overclocking carries risk reduced reliability accuracy damage data equipment additionally manufacturer warranties service agreements cover overclocked components incidental damages caused use overclocking still option increasing personal computing capacity thus workflow productivity professional users importance stability testing components thoroughly employing production environment overstated overclocking offers several draws overclocking enthusiasts overclocking allows testing components speeds currently offered manufacturer speeds officially offered specialized higher-priced versions product general trend computing industry new technologies tend debut high-end market first later trickle performance mainstream market high-end part differs increased clock speed enthusiast attempt overclock mainstream part simulate high-end offering give insight over-the-horizon technologies perform officially available mainstream market especially helpful users considering plan ahead purchase upgrade new feature officially released hobbyists enjoy building tuning hot-rodding systems competitive benchmarking competitions competing like-minded users high scores standardized computer benchmark suites others purchase low-cost model component given product line attempt overclock part match expensive model stock performance another approach overclocking older components attempt keep pace increasing system requirements extend useful service life older part least delay purchase new hardware solely performance reasons another rationale overclocking older equipment even overclocking stresses equipment point failure earlier little lost already depreciated would needed replaced case technically component uses timer clock synchronize internal operations overclocked efforts computer components however focus specific components processors a.k.a cpu video cards motherboard chip sets ram modern processors derive effective operating speeds multiplying base clock processor bus speed internal multiplier within processor cpu multiplier attain final speed computer processors generally overclocked manipulating cpu multiplier option available processor components also overclocked increasing base speed bus clock systems allow additional tuning clocks system clock influence bus clock speed multiplied processor allow finer adjustments final processor speed oem systems expose user adjustments needed change processor clock speed voltage precludes overclocking warranty support reasons processor installed different motherboard offering adjustments allow user change given component ultimately stop operating reliably past certain clock speed components generally show sort malfunctioning behavior indication compromised stability alerts user given speed stable always possibility component permanently fail without warning even voltages kept within pre-determined safe values maximum speed determined overclocking point first instability accepting last stable slower setting components guaranteed operate correctly rated values beyond different samples may different overclocking potential end-point given overclock determined parameters available cpu multipliers bus dividers voltages user ability manage thermal loads cooling techniques several factors individual devices semiconductor clock thermal tolerances interaction components rest system several things considered overclocking first ensure component supplied adequate power voltage sufficient operate new clock rate supplying power improper settings applying excessive voltage permanently damage component professional production environment overclocking likely used increase speed justifies cost expert support required possibly reduced reliability consequent effect maintenance contracts warranties higher power consumption faster speed required often cheaper costs considered buy faster hardware electronic circuits produce heat generated movement electric current clock frequencies digital circuits voltage applied increase heat generated components running higher performance levels also increases relationship clock frequencies thermal design power tdp linear however limit maximum frequency called wall overcome issue overclockers raise chip voltage increase overclocking potential voltage increases power consumption consequently heat generation significantly proportionally square voltage linear circuit example requires cooling avoid damaging hardware overheating addition digital circuits slow high temperatures due changes mosfet device characteristics conversely overclocker may decide decrease chip voltage overclocking process known undervolting reduce heat emissions performance remains optimal stock cooling systems designed amount power produced non-overclocked use overclocked circuits require cooling powerful fans larger heat sinks heat pipes water cooling mass shape material influence ability heatsink dissipate heat efficient heatsinks often made entirely copper high thermal conductivity expensive aluminium widely used good thermal characteristics though good copper significantly cheaper cheaper materials steel good thermal characteristics heat pipes used improve conductivity many heatsinks combine two materials achieve balance performance cost water cooling carries waste heat radiator thermoelectric cooling devices actually refrigerate using peltier effect help high thermal design power tdp processors made intel amd early twenty-first century thermoelectric cooling devices create temperature differences two plates running electric current plates method cooling highly effective generates significant heat elsewhere must carried away often convection-based heatsink water cooling system cooling methods forced convection phase transition cooling used refrigerators adapted computer use liquid nitrogen liquid helium dry ice used coolants extreme cases record-setting attempts one-off experiments rather cooling everyday system june 2006 ibm georgia institute technology jointly announced new record silicon-based chip clock rate rate transistor switched cpu clock rate 500 ghz done cooling chip using liquid helium cpu frequency world record 8.794 ghz november 2012 extreme methods generally impractical long term require refilling reservoirs vaporizing coolant condensation form chilled components moreover silicon-based junction gate field-effect transistors jfet degrade temperatures roughly eventually cease function freeze since silicon ceases semiconducting using extremely cold coolants may cause devices fail submersion cooling used cray-2 supercomputer involves sinking part computer system directly chilled liquid thermally conductive low electrical conductivity advantage technique condensation form components good submersion liquid fluorinert made 3m expensive another option mineral oil impurities water might cause conduct electricity overclocked component operates outside manufacturer recommended operating conditions may function incorrectly leading system instability another risk silent data corruption undetected errors failures might never correctly diagnosed may instead incorrectly attributed software bugs applications device drivers operating system overclocked use may permanently damage components enough cause misbehave even normal operating conditions without becoming totally unusable large-scale 2011 field study hardware faults causing system crash consumer pcs laptops showed four 20 times increase depending cpu manufacturer system crashes due cpu failure overclocked computers eight-month period general overclockers claim testing ensure overclocked system stable functioning correctly although software tools available testing hardware stability generally impossible private individual thoroughly test functionality processor achieving good fault coverage requires immense engineering effort even resources dedicated validation manufacturers faulty components even design faults always detected particular stress test verify functionality specific instruction sequence used combination data may detect faults operations example arithmetic operation may produce correct result incorrect flags flags checked error go undetected complicate matters process technologies silicon insulator soi devices display hysteresis—a circuit performance affected events past without carefully targeted tests possible particular sequence state changes work overclocked rates one situation another even voltage temperature often overclocked system passes stress tests experiences instabilities programs overclocking circles stress tests torture tests used check correct operation component workloads selected put high load component interest e.g graphically intensive application testing video cards different math-intensive applications testing general cpus popular stress tests include prime95 everest superpi occt aida64 linpack via linx intelburntest guis sisoftware sandra boinc intel thermal analysis tool memtest86 hope functional-correctness issues overclocked component show tests errors detected test component deemed stable since fault coverage important stability testing tests often run long periods time hours even days overclocked computer sometimes described using number hours stability program used prime 12 hours stable overclockability arises part due economics manufacturing processes cpus components many cases components manufactured process tested manufacture determine actual maximum ratings components marked rating chosen market needs semiconductor manufacturer manufacturing yield high higher-rated components required may produced manufacturer may mark sell higher-performing components lower-rated marketing reasons cases true maximum rating component may exceed even highest rated component sold many devices sold lower rating may behave ways higher-rated ones worst case operation higher rating may problematical notably higher clocks must always mean greater waste heat generation semiconductors set high must dump ground often cases means chief drawback overclocked part far heat dissipated maximums published manufacturer pentium architect bob colwell calls overclocking uncontrolled experiment better-than-worst-case system operation benchmarks used evaluate performance become kind sport users compete highest scores discussed stability functional correctness may compromised overclocking meaningful benchmark results depend correct execution benchmark benchmark scores may qualified stability correctness notes e.g overclocker may report score noting benchmark runs completion 1 5 times signs incorrect execution display corruption visible running benchmark widely used test stability prime95 built-in error checking fails computer unstable using benchmark scores may difficult judge difference overclocking makes overall performance computer example benchmarks test one aspect system memory bandwidth without taking consideration higher clock rates aspect improve system performance whole apart demanding applications video encoding high-demand databases scientific computing memory bandwidth typically bottleneck great increase memory bandwidth may unnoticeable user depending applications used benchmarks 3dmark attempt replicate game conditions commercial system builders component resellers sometimes overclock sell items higher profit margins seller makes money overclocking lower-priced components found operate correctly selling equipment prices appropriate higher-rated components equipment normally operate correctly practice may considered fraudulent buyer unaware overclocking sometimes offered legitimate service feature consumers manufacturer retailer tests overclocking capability processors memory video cards hardware products several video card manufactures offer factory-overclocked versions graphics accelerators complete warranty usually price intermediate standard product non-overclocked product higher performance speculated manufacturers implement overclocking prevention mechanisms cpu locking prevent users buying lower-priced items overclocking measures sometimes marketed consumer protection benefit often criticised buyers many motherboards sold advertised extensive facilities overclocking implemented hardware controlled bios settings cpu locking process permanently setting cpu clock multiplier amd cpus unlocked early editions model locked later editions nearly intel cpus locked recent models resistant unlocking prevent overclocking users amd ships unlocked cpus opteron fx ryzen black series line-up intel uses monikers extreme edition x-series intel usually one two extreme edition cpus market well x series k series cpus analogous amd black edition amd majority desktop range black edition users unlock cpus allow underclocking overclocking front side bus speed older cpus compatibility certain motherboards unlocking invalidates manufacturer warranty mistakes cripple destroy cpu locking chip clock multiplier necessarily prevent users overclocking speed front-side bus pci multiplier newer cpus still changed provide performance increase amd athlon athlon xp cpus generally unlocked connecting bridges jumper-like points top cpu conductive paint pencil lead cpu models determinable serial number require different procedures increasing front-side bus northbridge/pci clock overclock locked cpus throws many system frequencies whack since ram pci frequencies modified well one easiest ways unlock older amd athlon xp cpus called pin mod method possible unlock cpu without permanently modifying bridges user could simply put one wire new multiplier/vcore socket unlock cpu overclocking components noticeable benefit component critical path process bottleneck disk access speed internet connection limit speed process 20 increase processor speed unlikely noticed overclocking cpu benefit game limited speed graphics card graphics cards overclocked utilities achieve evga precision rivatuner amd overdrive amd cards msi afterburner zotac firestorm zotac cards peg link mode asus motherboards overclocking gpu often yield marked increase performance synthetic benchmarks usually reflected game performance sometimes possible see graphics card pushed beyond limits permanent damage done observing on-screen artifacts two discriminated warning bells widely understood green-flashing random triangles appearing screen usually correspond overheating problems gpu white flashing dots appearing randomly usually groups screen often mean card ram overheating common run one problems overclocking graphics cards symptoms time usually means card severely pushed beyond heat clock rate voltage limits seen overclocked indicate faulty card clock speed excessive without overheating artifacts different general rule usually core pushed hard black circles blobs appear screen overclocking video memory beyond limits usually results application entire operating system crashing reboot video settings reset standard values stored graphics card firmware maximum clock rate specific card known overclockers apply potentiometer graphics card manually adjust voltage invalidates warranty results much greater flexibility overclocking software graphics cards rarely able adjust voltage excessive voltage increases may destroy graphics card flashing unlocking used improve performance video card without technically overclocking flashing refers using firmware different card core compatible firmware effectively making higher model card difficult may irreversible sometimes standalone software modify firmware files found e.g nibitor geforce 6/7 series well regarded aspect without using firmware better model video card example video cards 3d accelerators two voltage clock rate settings one 2d one 3d designed operate three voltage stages third somewhere aforementioned two serving fallback card overheats middle-stage going 2d 3d operation mode therefore could wise set middle-stage prior serious overclocking specifically fallback ability card drop clock rate reducing sometimes dozen depending setting percent efficiency cool without dropping 3d mode afterwards return desired high performance clock voltage settings cards abilities directly connected overclocking example nvidia geforce 6600gt agp flavor temperature monitor used internally card invisible user standard firmware used modifying firmware display 'temperature tab unlocking refers enabling extra pipelines pixel shaders 6800le 6800gs 6800 agp models first cards benefit unlocking models either 8 12 pipes enabled share 16x6 gpu core 6800gt ultra pipelines shaders beyond specified disabled gpu may fully functional may found faults affect operation lower specification gpus found fully functional unlocked successfully although possible sure undiscovered faults worst case card may become permanently unusable overclocked processors first became commercially available 1983 amd sold overclocked version intel 8088 cpu 1984 consumers overclocking ibm version intel 80286 cpu replacing clock crystal
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Computer architecture
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fx.25 forward error correction fx.25 protocol extension ax.25 link layer protocol fx.25 provides forward error correction fec capability maintaining legacy compatibility non-fec equipment fx.25 created stensat group 2005 presented technical paper 2006 tapr digital communications conference tucson az fx.25 intended complement ax.25 protocol replace provides encapsulation mechanism alter ax.25 data functionalities error correction capability introduced bottom layer 2 osi model ax.25 link layer protocol extensively used amateur radio communications packets validated 16-bit crc discarded one errors detected many cases space-to-earth telemetry packets broadcast unidirectionally back-channel may available request retransmission errored elements consequently ax.25 links inherently intolerant errors fx.25 protocol extension provides error correction wrapper around ax.25 packet allowing removal errors receiving end data fields carefully chosen allow reception ax.25 packet data within fx.25 frame non-fec decoder composite fx.25 entity called frame distinguishing ax.25 packet contained within fx.25 frame contains following elements preamble correlation tag ax.25 packet ax.25 packet start ax.25 packet body ax.25 packet frame check sequence fcs ax.25 packet end pad bit-to-byte alignment fec check symbols postamble fec codeblock contains elements except preamble correlation tag postamble three elements exist outside correction-space fec algorithm preamble postamble blocks variable length included account delays typically found radio links transmitter key stable operation receiver squelch latency etc correlation tag gold code contains inherent error tolerance necessary provide start frame marker without requiring dependency fec capability fec frame currently implements reed solomon error correction algorithms restricted performance improvement function ax.25 packet size combined noise characteristics transmission channel initial performance testing involved transmission 61 fx.25 frames interval 15 minutes 9 frames received without errors 19 frames received correctable errors 33 frames received uncorrectable errors 15 ax.25 packets 9/61 decodable without fec capability 46 ax.25 packets 9+19 /61 decodable fec capability
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Internet protocols
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joint source channel coding information theory joint source–channel coding encoding redundant information source transmission noisy channel corresponding decoding using single code instead conventional steps source coding followed channel coding joint source–channel coding proposed implemented variety situations including speech videotransmission
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Computer security
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list computers running cp/m many microcomputer makes models could run version derivation cp/m disk operating system eight-bit computers running cp/m 80 built around intel 8080/8085 zilog z80 compatible cpu cp/m 86 ran intel 8086 8088 computers suitable cp/m delivered others needed hardware modifications memory expansion modification new boot roms addition floppy disk drive popular home computers using processors supported cp/m plug-in z80 compatible processors allowing use cp/m retaining base machine keyboard peripherals sometimes video display memory following alphabetical list computers running cp/m
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Operating systems
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bliss image bliss default computer wallpaper microsoft windows xp operating system unedited photograph green hill blue sky clouds los carneros american viticultural area california wine country charles o'rear made photo 1996 microsoft bought rights 2000 former national geographic photographer charles o'rear resident nearby napa valley took photo film medium-format mamiya rz67 camera way visit girlfriend 1996 widely believed later image digitally manipulated even created software adobe photoshop o'rear says never sold corbis use stock photo several years later microsoft engineers chose digitized version image licensed o'rear next decade claimed viewed photograph world time january 1996 former national geographic photographer charles o'rear way home st. helena california napa valley north san francisco visit girlfriend daphne irwin later married city every friday afternoon working irwin book wine country particularly alert photo opportunity day since storm passed recent winter rains left area especially green driving along sonoma highway california state route 12 121 saw hill free vineyards normally covered area pulled years earlier following phylloxera infestation god grass perfect green sun clouds remembered thinking stopped somewhere near napa–sonoma county line pulled road set mamiya rz67 medium-format camera tripod choosing fujifilm velvia film often used among nature photographers known saturate colors o'rear credits combination camera film success image made difference think helped 'bliss photograph stand even said think shot 35 mm would nearly effect setting camera said possible clouds picture came everything changing quickly time took four shots got back truck according o'rear image digitally enhanced manipulated way since pertinent wine-country book o'rear made available corbis stock photo available use interested party willing pay appropriate licensing fee 2000 microsoft windows xp development team contacted o'rear corbis believes used instead larger competitor getty images also based seattle former company owned microsoft founder bill gates idea looking recalls looking image peaceful looking image tension microsoft said wanted license image use xp default wallpaper buy rights offered o'rear says second-largest payment ever made photographer single image however signed confidentiality agreement disclose exact amount reported low six figures o'rear needed send microsoft original film sign paperwork however couriers delivery services became aware value shipment declined since higher insurance would cover software company bought plane ticket seattle personally delivered offices idea going go said n't think engineers anybody microsoft idea would success microsoft gave photo name made key part marketing campaign xp although o'rear manipulated image way company admitted cropping original image slightly left order better fit desktop making greens stronger photographer estimates image seen billion computers worldwide based number copies xp sold since november 2006 goldin+senneby visited site sonoma valley bliss image taken re-photographing view full grapevines pictured work microsoft first shown exhibition paris yesterday gallery la vitrine april 2007 later exhibited 300m³ gothenburg o'rear concedes despite photographs took national geographic probably remembered bliss anybody age 15 rest life remember photograph said since origins image widely known several years xp release considerable speculation landscape guesses included locations france england switzerland north otago region new zealand southeastern washington dutch users believed photograph shot ireland county kerry since image named ireland dutch release software similarly image named alentejo portuguese version leading users speaking language believe taken eponymous region portugal users speculated image real location sky came separate image spliced together hill o'rear adamant microsoft minor alterations digitized version nothing darkroom contrasting adams monolith 2012 david clark british magazine amateur photographer commented bliss nowiki /nowiki aesthetic qualities critics might argue image bland lacks point interest supporters would say evocation bright clear day beautiful landscape subject wrote notes dreamlike quality created filtered sunlight hillside distinguishing image made microsoft choose image others asked although company never told o'rear anyone else clark thought could guess attractive easy eye n't detract items might screen contributing factors may also chosen unusually inviting image verdant landscape one promotes sense wellbeing desk-bound computer users
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Operating systems
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network allocation vector network allocation vector nav virtual carrier-sensing mechanism used wireless network protocols ieee 802.11 wi-fi ieee 802.16 wimax virtual carrier-sensing logical abstraction limits need physical carrier-sensing air interface order save power mac layer frame headers contain duration field specifies transmission time required frame time medium busy stations listening wireless medium read duration field set nav indicator station long must defer accessing medium nav may thought counter counts zero uniform rate counter zero virtual carrier-sensing indication medium idle nonzero indication busy medium shall determined busy station sta transmitting ieee 802.11 nav represents number microseconds sending sta intends hold medium busy maximum 32,767 microseconds sender sends request send receiver waits one sifs sending clear send sender wait one sifs sending data receiver wait sifs sending ack nav duration first sifs ending ack time medium considered busy wireless stations often battery-powered conserve power stations may enter power-saving mode station decrements nav counter becomes zero time awakened sense medium nav virtual carrier sensing mechanism prominent part csma/ca mac protocol used ieee 802.11 wlans nav used dcf pcf hcf
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Internet protocols
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biometric device biometric device security identification authentication device devices use automated methods verifying recognising identity living person based physiological behavioral characteristic characteristics include fingerprints facial images iris voice recognition biometric devices used man long period time non-automated biometric devices used us since 500 bc seen babylonian business transactions recorded clay tablets included fingerprints automation biometric devices first seen 1960s federal bureau investigation fbi 1960s introduced indentimat started checking fingerprints maintain criminal records first systems measured shape hand length fingers although discontinued 1980s system set precedent future biometric devices characteristic human body used access information users according characteristics sub-divided groups biometrics used establish better accessible records hours employee work increase buddy punching case employees clocked coworkers fraudulently inflated work hours employers looked towards new technology like fingerprint recognition reduce fraud additionally employers also faced task proper collection data entry exit times biometric devices make largely foul proof reliable ways enabling collect data employees present enter biometric details unique demand air travel grows people travel modern day airports implement technology way long queues biometrics implemented airports enable quick recognition passengers hence lead lower volume people standing queue one example dubai international airport plans make immigration counters relic past implement iris move technology iom help seamless departures arrivals passengers airport fingerprint sensors found mobile devices fingerprint sensor used unlock device authorize actions like money file transfers example used prevent device used unauthorized person one highly recognised acceptable biometrics corporate surroundings verification taken one step capturing signature taking account many parameters revolving around like pressure applied signing speed hand movement angle made surface pen used make signature system also ability learn users signature styles vary user hence taking sample data system able increase accuracy iris recognition involves device scanning retina subject cross referencing data stored database one secure forms authentication fingerprints left behind surfaces iris prints extremely hard stolen iris recognition widely applied organisations dealing masses one aadhaar identification carried government india keep records population reason iris recognition makes use iris prints humans hardly evolve one lifetime extremely stable biometric spoofing method fooling biometric identification management system counterfeit mold presented front biometric scanner counterfeit mold emulates unique biometric attributes individual confuse system artifact real biological target gain access sensitive data/materials one high-profile case biometric spoofing came limelight found german defence minister ursula von der leyen fingerprint successfully replicated chaos computer club group used high quality camera lenses shot images 6 feet away used professional finger software mapped contours ministers thumbprint although progress made stop spoofing using principle pulse oximetry- liveliness test subject taken account measure blood oxygenation heart rate reduces attacks like ones mentioned although methods n't commercially applicable costs implementation high reduces real world application hence makes biometrics insecure methods commercially viable accuracy major issue biometric recognition passwords still extremely popular password static nature biometric data subject change one voice becoming heavier due puberty accident face could lead improper reading facial scan data testing voice recognition substitute pin-based systems barclays reported voice recognition system 95 percent accurate statistic means many customers voices might still recognised even correct uncertanity revolving around system could lead slower adoption biometric devices continuing reliance traditional password-based methods researchers targeting drawbacks present-day biometric devices developing reduce problems like biometric spoofing inaccurate intake data technologies developed are-
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Computer security
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modula-3 modula-3 programming language conceived successor upgraded version modula-2 known modula-2+ influential research circles influencing designs languages java c python adopted widely industry designed luca cardelli james donahue lucille glassman mick jordan olivetti software technology laboratory bill kalsow greg nelson digital equipment corporation dec systems research center src olivetti research center orc late 1980s modula-3 main features simplicity safety preserving power systems-programming language modula-3 aimed continue pascal tradition type safety introducing new constructs practical real-world programming particular modula-3 added support generic programming similar templates multithreading exception handling garbage collection object-oriented programming partial revelation explicit mark unsafe code design goal modula-3 language implements important features modern imperative languages quite basic forms thus allegedly dangerous complicating features multiple inheritance operator overloading omitted modula-3 project started november 1986 maurice wilkes wrote niklaus wirth ideas new version modula wilkes working dec prior point returned england joined olivetti research strategy board wirth already moved oberon problems wilkes team continuing development modula name language definition completed august 1988 updated version january 1989 compilers dec olivetti soon followed 3rd party implementations design heavily influenced work modula-2+ language use src acorn computers research center arc later orc olivetti bought acorn time language operating system dec firefly multiprocessor vax workstation written acorn compiler acorn c modula execution library camel arc arx operating system project arm based acorn archimedes range computers written revised modula-3 report states language influenced languages mesa cedar object pascal oberon euclid 1990s modula-3 gained considerable currency teaching language never widely adopted industrial use contributing may demise dec key modula-3 supporter especially ceased maintain effectively dec sold compaq 1998 case spite modula-3 simplicity power appears little demand procedural compiled language restricted implementation object-oriented programming time commercial compiler called cm3 maintained one chief implementors prior dec src hired dec sold compaq integrated development environment called reactor extensible java virtual machine licensed binary source formats buildable reactor offered critical mass inc. company ceased active operations 2000 gave sources products software solutions gmbh modula-3 taught universities mostly comparative programming language courses textbooks print essentially corporate supporter modula-3 software solutions gmbh inherited sources critical mass since made several releases cm3 system source binary form reactor ide open source released several years new name cm3-ide march 2002 also took repository another active modula-3 distribution pm3 maintained école polytechnique de montréal later continued work hm3 improved years later obsoleted common example language syntax hello world program programs modula-3 least module file also include interface file used clients access data module like languages modula-3 program must export main module either file named main.m3 file call codice_1 export main module module file names suggested actual module name compiler warn different conventions syntax include naming exported type interface codice_2 since types usually qualified full names type codice_2 inside module named foo named codice_4 aids readability another similar convention naming public object codice_5 oop examples first foremost compilation units either codice_6 implementation codice_7s one flavor another interface compilation unit beginning keyword codice_6 defines constants types variables exceptions procedures implementation module beginning keyword codice_7 provides actual code constants types variables needed implement interface default implementation module implement interface name module may explicitly codice_1 module name example main program exports implementation module main interface compilation unit may codice_11 interfaces although circular imports forbidden may resolved import implementation module entities within imported module may imported instead module name using codice_12 syntax typically one imports interface uses 'dot notation access items within interface similar accessing fields within record typical usage define one data structure record object per interface along support procedures main type get name 't one uses codice_13 event name collision imported module entity within module reserved word codice_14 used codice_15 capability deemed unsafe compiler longer guarantee results consistent example interfacing c programming language keyword codice_16 prefixed front codice_6 codice_7 may used tell compiler enable certain low level features language example unsafe operation bypassing type system using codice_19 copy bits integer floating point codice_20 number interface imports unsafe module must unsafe safe interface may exported unsafe implementation module typical usage interfacing external libraries two interfaces built one unsafe safe generic interface corresponding generic module prefix codice_6 codice_7 keyword codice_23 take formal arguments interfaces thus like c++ templates one easily define use abstract data types unlike c++ granularity module level interface passed generic interface implementation modules actual arguments compiler generate concrete modules example one could define genericstack instantiate interfaces codice_24 codice_25 even interfaces objects long interfaces defines properties required generic modules note bare types codice_26 codice_20 ca n't used modules system generics based upon using modules arguments comparison c++ template bare type would used file integerelem.i3 file genericstack.ig file genericstack.mg file integerstack.i3 file integerstack.m3 identifier traced back originated unlike 'include feature languages compilation unit must import identifiers compilation units using codice_11 statement even enumerations make use 'dot notation used accessing field record modula-3 supports allocation data runtime two kinds memory allocated codice_29 codice_30 difference whether garbage collector see new used allocate data either classes memory codice_16 module codice_32 available free untraced memory object-oriented programming techniques may used modula-3 use required many features provided modula-3 modules generics usually take place object orientation object support intentionally kept simplest terms object type termed class object oriented languages introduced codice_33 declaration essentially syntax codice_34 declaration although object type reference type whereas records modula-3 similar structs c exported types usually named convention create separate public type expose methods data instance defines interface codice_35 two types codice_2 codice_5 defined object two methods codice_38 codice_39 codice_2 defined subtype codice_5 use codice_42 operator create new codice_43 object use built procedure codice_44 method codice_39 modula-3 codice_46 construct provides conceptually simple clean yet powerful mechanism hiding implementation details clients arbitrarily many levels friendliness use codice_46 show full implementation codice_35 interface note use codice_49 keyword brands objects make unique avoid structural equivalence codice_49 also take string argument omitted unique string generated modula-3 one programming languages requires external references module strictly qualified reference module codice_51 object codice_52 exported module codice_53 must take form codice_54 possible modula-3 import exported names module language requirements name qualification method overriding impossible break working program simply adding new declarations interface interface makes possible large programs edited concurrently many programmers without worries naming conflicts also makes possible edit core language libraries firm knowledge existing programs broken process exception handling based codice_55 ... codice_56 block system since become common one feature adopted languages notable exceptions delphi python scala visual basic.net codice_56 construct defined form switch statement possible exception case except clause modula-3 also supports codice_58 ... codice_59 ... codice_60 construct loops codice_59 occurs structure equivalent simple loop inside codice_55 ... codice_56 clause language supports use multi-threading synchronization threads standard module within runtime library m3core named thread supports use multi-threaded applications fact modula-3 runtime may make use separate thread internal tasks garbage collection built-in data structure codice_64 used synchronize multiple threads protect data structures simultaneous access possible corruption race conditions codice_65 corresponding codice_66 statements lock unlock codice_64 codice_64 object objects may derived example i/o section libm3 library readers writers rd.t wr.t derived mutex lock accessing modifying internal data buffers summary language features modula-3 one rare languages whose evolution features documented systems programming modula-3 four essential points language design intensively discussed topics structural vs. name equivalence subtyping rules generic modules parameter modes like codice_69 continuing trend started c programming language many features required write real programs left language definition instead provided via number standard libraries interfaces described detail standard libraries providing following features called standard interfaces required must provided language recommended interfaces implemented available implementations required c i/o also provided via libraries modula-3 called codice_72 codice_73 object-oriented design rd wr readers writers respectively libraries covered detail book greg nelson interesting aspect modula-3 one programming languages whose standard libraries formally verified contain various types bugs including locking bugs done auspices larch/modula-3 see larch family extended static checking projects dec systems research center several compilers available open source since aspect c data structures missing modula-3 union type existing modula-3 implementations able provide good binary compatibility c language type declarations arrays structs none books still print although used copies obtainable digitized partially digitized chapters one previous posterior versions obtainable research reports web although modula-3 gain mainstream status several parts dec-src m3 distribution arguably influential part network objects library formed basis java first rmi implementation including actual network protocol sun moved corba standard iiop based protocol dropped java documentation garbage collection remote objects still refer pioneering work done modula-3 network objects python implementation classes also inspired class mechanism found c++ modula-3
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Programming language topics
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drdo netra netra network traffic analysis software network developed india centre artificial intelligence robotics cair defence research development organisation drdo laboratory used intelligence bureau india domestic intelligence agency research analysis wing raw country external intelligence agency intercept analyse internet traffic using pre-defined filters program tested smaller scales various national security agencies reported deployed nationwide soon january 2014 security agencies looking build system could monitor internet traffic real time basis due rapidly escalating threat posed terrorist criminal elements using data communication brought service providers like blackberry skype gmail focus law enforcement agencies two systems designed one drdo centre artificial intelligence robotics national technical research organisation ntro india technical intelligence agency inter-ministerial committee staffed members ministry home affairs intelligence bureau department telecom department national investigation agency formed evaluate systems select one internet monitoring system ntro system designed help paladion international private company netra designed team 40 scientists cair committee selected cair netra multiple issues ntro system serious security reservations involvement international private company sensitive project doubts ntro ability operate maintain upgrade system independently also raw tested ntro system happy ntro solution reported crashed frequently committee favoured netra indigenous solution involving government scientists personnel component solution outsourced outside agency agency testing netra ib also pleased performance committee observed cair continuously investing r keep fast-changing web technologies unlike ntro system first demonstrated premises sify technologies capture entire internet traffic passing probes netra analyse voice traffic passing software skype google talk intercept messages keywords 'attack 'bomb 'blast 'kill real-time enormous number tweets status updates emails instant messaging transcripts internet calls blogs forums even images generated internet obtain desired intelligence system raw analyses large amount international data crosses internet networks india three security agencies include ib raw allotted maximum 300 gigabytes gb per node totaling 1000 nodes storing intercepted internet traffic 1000 nodes x 300gb 300,000gb total space initially decided set extra 100 gb per node assigned remaining law enforcement agencies internet scanning coordination centre use system monitor internet similar ones used usa uk china iran many nations initially raw current user monitoring system 2013 ministry home affairs recommended use second netra system domestic law enforcement agencies done intelligence gathered external intelligence agency largely irrelevant use law enforcement agencies could handle data note department telecommunications dot stated system provide access multiple security agencies netra deployment discussed 2013 apex inter-ministerial group headed dot included representative cabinet secretariat ministry home affairs drdo cair intelligence bureau c-dot computer emergency response team cert-in drdo scientist dr. g. athithan cair team awarded 'agni award excellence self-reliance 2008 developing netra team comprised scientists indian institute science g.ravindra rahul m. kharge
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Computer security
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zenji video game zenji puzzle game designed matthew hubbard published activision 1984 released atari 5200 atari 8-bit family colecovision commodore 64 msx zx spectrum hubbard previously wrote dolphin atari 2600 zenji maze-based game wherein player controls disembodied mandarin-style head challenge connect series randomly rotated maze-segments attempt align glowing artifact known source acts maze focal point player moves segment maze attempts rotate portion source green light shine region signifying correct alignment portions maze connected successfully end timer player awarded points moves next stage successive mazes introduce greater complexity hazards player survival conclusion review commodore 64 edition zenji author compute gazette stated although final understanding source remains elusive zenji undeniably enjoyable game note last paragraph review also stated zenji appears multiplayer game ... 8 acolytes time ... documentation concerning however
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Computer architecture
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form grabbing form grabbing form malware works retrieving authorization log-in credentials web data form passed internet secure server allows malware avoid https encryption method effective keylogger software acquire user ’ credentials even input using virtual keyboard auto-fill copy paste sort information based variable names email account name password additionally form grabber log url title website data gathered method invented 2003 developer variant trojan horse called downloader.barbew attempts download backdoor.barbew internet bring local system execution however popularized well known type malware attack emergence infamous banking trojan zeus 2007 zeus used steal banking information man-in-the-browser keystroke logging form grabbing like zeus barbew trojan initially spammed large numbers individuals e-mails masquerading big-name banking companies form grabbing method first advanced iterations zeus allowed module detect grabbed form data also determine useful information taken later versions form grabber also privy website actual data submitted leaving sensitive information vulnerable trojan known tinba tiny banker trojan built form grabbing able steal online banking credentials first discovered 2012 another program called weyland-yutani bot first software designed attack macos platform work firefox web injects templates weyland-yutani bot different existing ones zeus spyeye another known version british airways breach september 2018 british airways ’ case organizations ’ servers appeared compromised directly attackers modifying one javascript files modernizr javascript library version 2.6.2 include pii/credit card logging script would grab payment information send information server controlled attacker hosted “ baways com ” domain ssl certificate issued “ comodo ” certificate authority british airways mobile application also loads webpage built css javascript components main website including malicious script installed magecart thus payments made using british airways mobile app also affected due recent increase keylogging form grabbing antivirus companies adding additional protection counter efforts key-loggers prevent collecting passwords efforts taken different forms varying antivirus companies safepay password manager others counter form grabbing users privileges become limited would prevent installing browser helper objects bhos form grabbing software administrators create list malicious servers firewalls
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Computer security
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mactcp mactcp standard tcp/ip implementation classic mac os version 7.5.1 first application-independent implementation tcp stack non-unix platform predates winsock 5 years released 1988 considered obsolete reliability issues incomplete features sometimes prevent operating properly modern internet addition api unique mac os least one developer released berkeley sockets-derived api make porting platforms easier originally substantial purchase carrying 2,500 price tag site license additional 2,500 fee commercial use price lowered mid-1990s sold 60 mactcp included free mac os system 7.5 rising popularity internet made necessity apple replaced 1995 open transport improved interface user configuration although mactcp remained use older systems due generally lower system requirements
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Operating systems
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mcafee institute mcafee institute llc. best known professional certification body administers several board certifications intelligence investigative sectors topics available training include cryptocurrency investigations cyber intelligence investigations counterintelligence human trafficking workplace violence active shooter organized retail crime leadership incident response digital forensics fraud deception detection founded 2010 mcafee institute professional certification training organization focused intelligence investigative sectors 2018 mcafee institute grown offer several industry recognized board certifications governing board mcafee institute oversees certification affairs organization contributes global standards certifications helps institute policy actions membership meetings ballot governing board consists world best federal local state law enforcement intelligence loss prevention cyber security private investigation around globe mcafee institute partnered dept homeland securities national initiative cybersecurity careers studies niccs listed site provider professional certifications space mcafee institute also partner recognized ileeta international law enforcement educators trainers association mcafee institute certified operate missouri dept education proprietary school central focus proprietary school certification program consumer protection accomplished establishment standards school operation monitoring operations ensure students treated fair equitable manner receive education training consistent published objectives instructional programs school mcafee institute cpe sponsor national registry cpe sponsors program offered national association state boards accountancy nasba recognize cpe program sponsors provide continuing professional education cpe programs accordance nationally recognized standards mcafee institutes resident based in-person certification training programs approved veterans administration g.i bill benefits effective november 12 2018 mcafee institute exams approved reimbursement va eligible limit number exams may take number times may take exam va pay exams even fail mcafee institute programs approved post continuing education credits following post missouri peace officer standards training clee mcafee institute headquartered chesterfield missouri teaching faculty organized three different levels independent certified instructors adjunct instructors senior instructors led director training certification michael simmons institute provides following certifications retired credentials 2018
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Computer security
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garant garant complex services based legal information resource developed « garant-service-universitet » scientific-production enterprise limited liability company first large-scale commercial legal information system russia since 1990 containing legislation russian federation also english language garant comprehensive fully cross-referenced legal information resource following elements garant system – legal information database updated daily providing quick precise searches complex analysis legal situation keeping abreast changes legislation online format prime – daily individualised information feed contains legal news hundreds thousands commentaries legal acts court practice enables creating overviews changes legislation legal consulting – access unique body knowledge experts legal consulting solutions tens thousands real practical situations option receiving individual written consultations all-russia satellite online-seminars – interactive participation seminars given authoritative specialists moscow broadcast towns cities throughout russia incorporating possibility getting answers questions asked system electronic express – service providing electronic digital signatures participation electronic trading state municipal procurement initiatives garant vesti garant news – colour publication succinctly informing users important changes legislation interesting court practice new developments field legal information provision effective applications work legal information professional journals – « aktualnaya bukhgalteria » « current bookkeeping » pertinent reliable information bookkeepers « zakonadatelstvo » « legislation » authoritative legal analysis lawyers consultations efficient use system – assistance specialists plus clearly arranged resource materials allowing quick easy retrieval analysis information professional-user certificates also obtainable www.garant.ru legal portal – source timely legal information legislation news just-released documents consultations internet conferences senior state officials dialogue popular trade forum service – assistance solving technical questions working garant legal information resource hot-line dedicated personal managers present garant system contains 30 million documents acts official bodies including laws presidential decrees codes rules regulations court practice materials constantly updated interactive encyclopedias library trade press articles books commentaries legislation official bookkeeping statistical accounting forms economic legal terms explanatory dictionaries six european languages economic reference information business enquiries bookkeeping calendar contact details official bodies etc. system presents legislation 85 regions russian federation also included directory medicines medicine manufacturers garant system primarily intended bookkeepers accountants lawyers managers banking employees specialists including foreign ones whose job duties include solving issues legal character new documents appear electronic garant legal enquiry system l.e.s database direct contracts federal regional governmental bodies every day garant l.e.s gets updated approximately ten thousand documents « garant-maximum russia » electronic texts correspond exactly official texts undergo careful legal processing respective commentaries references schemes hypertext links applied accurately consistently garant l.e.s provides different types information searches main type search « basic search » one line created specially working legal information internet connection available « legal information online » function allows one get access shell system services « legal information support hotline » « legal consulting » user sends question gets answer back expert directly system « time machine » function enables searching texts documents effect particular moment time past « document checking » function allows track histories changes documents « similar documents » function lets one instantly create list documents court practice questions answers theme similar given document « version comparison » function compares two versions document example version latest amendments previous version « news online » function allows loading online within system shell legal news information « online meeting » function provides users network version exchange instant messages like internet messengers incorporate hypertext links documents system system fully integrated internet free-of-charge internet version containing main regulatory documents russia fuller internet version accessible commercial basis « mobile garant online » gives access legal information system convenient flash memory stick internet connection available allows working legal information is/was current given moment time document applicability check function also possibility working internet version system higher patent chamber federal service intellectual property patents trademarks rospatent recognized garant well-known trademark russian federation since january 1 1998 quality management system developer complies iso 9001-2008 standard delivery installation garant legal information resource handled 250 partner organisations 500 towns cities russia
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Databases
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laptop theft laptop theft significant threat users laptop netbook computers many methods protect data prevent theft developed including alarms laptop locks visual deterrents stickers labels victims laptop theft lose hardware software essential data backed thieves also may access sensitive data personal information systems authorize access based credentials stored laptop including mac addresses web cookies cryptographic keys stored passwords according fbi losses due laptop theft totaled 3.5 million 2005 computer security institute/fbi computer crime security survey found average theft laptop cost company 31,975 study surveying 329 private public organizations published intel 2010 7.1 employee laptops lost stolen end usefulness lifespan furthermore determined average total negative economic impact stolen laptop 49,256—primarily due compromised data efforts retroactively protect organizations people potential consequences compromised data total cost lost laptops organizations involved study estimated 2.1 billion 48b lost u.s. economy result data breaches 28 resulted stolen laptops portable devices 2011 bureau brief prepared nsw bureau crime statistics research reported thefts laptops increase last 10 years attributed part increase ownership also attractive proposition thieves opportunists 2001 2,907 laptops stolen new south wales dwellings 2010 risen 6,492 second cash items taken thieves bureau reports one four break-ins 2010 resulted laptop stolen startling trend burglaries lends increase identity theft fraud due personal financial information commonly found laptops statistics take account unreported losses figures could arguably much higher businesses much lose unencrypted poorly secured laptop misappropriated yet many adequately assess risk take appropriate action loss sensitive company information significant risk businesses measures taken adequately protect data survey conducted multiple countries suggested employees often careless deliberately circumvent security procedures leads loss laptop according survey employees likely lose laptop travelling hotels airports rental cars conference events behling wood examined issue laptop security theft survey employees southern new england highlighted security measures fundamentally basic training employees security measures limited inadequate concluded trends laptop thefts needed monitored assess intervention measures required passwords longer adequate protect laptops many solutions improve strength laptop protection full disk encryption fde increasingly popular cost-effective approach full disk encryption taken software-based approach hardware-based approach end-based approach fde provides protection operating system starts pre-boot authentication however precautions still need taken cold boot attacks number tools available commercial open source enable user circumvent passwords windows mac os x linux one example truecrypt allows users create virtual encrypted disk computer passwords provide basic security measure files stored laptop though combined disk encryption software reliably protect data unauthorized access remote laptop security rls available confidently secure data even laptop owner possession remote laptop security owner laptop deny access rights stolen laptop computer internet access number computer security measures emerged aim protecting data kensington security slot along locking cable provides physical security thefts opportunity cord attached something heavy moved locked case laptop 100 secure noble security lock slot different way attach security cable stop security plates stoplock kits offer additional physical security measures along secure online registry 24/7 toll-free recovery hotline service another possible approach limiting consequences laptop theft issue thin client devices field employees instead conventional laptops data reside server therefore may less liable loss compromise thin client lost stolen easily inexpensively replaced however thin client depends network access server available aboard airliners location without network access approach coupled strong authentication single sign-on sso 2006 laptop custody data analyst stolen contained personal health data 26.5 million active duty troops veterans agency estimated cost 100 million 500 million prevent cover possible losses data theft 2007 united states department veterans affairs agreed pay 20 million current former military personnel settle class action lawsuit 2007 financial services authority fsa fined uk ’ largest building society nationwide £980,000 inadequate procedures employees ’ laptop stolen domestic burglary laptop details 11 million customers ’ names account numbers whilst device password protected information unencrypted fsa noted systems controls fell short given took nationwide three weeks take steps investigate content missing laptop substantial fine invoked reinforce fsa ’ commitment reducing financial crime 2010 va reported theft laptop unidentified contractor computer contained personally identifiable information 644 veterans including data va medical centers records learning unencrypted laptop va investigated many va contractors might complying encryption requirement learned 578 vendors refused sign new contract clauses required encrypt veteran data computers apparent violation rules lojack laptops compiled list top ten places laptops stolen provide context ponemon institute released study indicates 600,000 laptops lost stolen us airports every year 65-69 remaining unclaimed
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Computer security
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tcp wrappers tcp wrappers also known tcp_wrappers host-based networking acl system used filter network access internet protocol servers unix-like operating systems linux bsd allows host subnetwork ip addresses names and/or ident query replies used tokens filter access control purposes original code written wietse venema 1990 monitor cracker activities unix workstations department math computer science eindhoven university technology maintained 1995 june 1 2001 released bsd-style license tarball includes library named libwrap implements actual functionality initially services spawned connection super-server inetd got wrapped utilizing tcpd program however common network service daemons today linked libwrap directly used daemons operate without spawned super-server single process handles multiple connections otherwise first connection attempt would get checked acls compared host access control directives often found daemons configuration files tcp wrappers benefit runtime acl reconfiguration i.e. services n't reloaded restarted generic approach network administration makes easy use anti-worm scripts denyhosts fail2ban add expire client-blocking rules excessive connections and/or many failed login attempts encountered originally written protect tcp udp accepting services examples usage filter certain icmp packets exist 'pingd – userspace ping request responder january 1999 distribution package eindhoven university technology primary distribution site day replaced modified version replacement contained trojaned version software would allow intruder access server installed author spotted within hours upon relocated primary distribution personal site
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Internet protocols
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statistical parsing statistical parsing group parsing methods within natural language processing methods common associate grammar rules probability grammar rules traditionally viewed computational linguistics defining valid sentences language within mindset idea associating rule probability provides relative frequency given grammar rule deduction probability complete parse sentence probability associated grammar rule may induced application grammar rule within parse tree computation probability parse tree based component rules form deduction using concept statistical parsers make use procedure search space candidate parses computation candidate probability derive probable parse sentence viterbi algorithm one popular method searching probable parse search context application search algorithms artificial intelligence example think sentence hold water reader would instantly see object called object performing action 'can i.e able thing object able hold thing object able hold water using linguistic terminology noun phrase composed determiner followed noun hold water verb phrase composed verb followed verb phrase interpretation sentence certainly perfectly valid noun-phrase referring type dance hold water also valid verb-phrase although coerced meaning combined sentence non-obvious lack meaning seen problem linguists discussion point see colorless green ideas sleep furiously pragmatic point view desirable obtain first interpretation rather second statistical parsers achieve ranking interpretations based probability number methods statistical parsing algorithms frequently use algorithms use give good overview general field statistical parsing algorithms based modified form chart parsing modifications necessary support extremely large number grammatical rules therefore search space essentially involve applying classical artificial intelligence algorithms traditionally exhaustive search examples optimisations searching likely subset search space stack search optimising search probability baum-welch algorithm discarding parses similar treated separately viterbi algorithm
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Computational linguistics
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treadmarks treadmarks distributed shared memory system created rice university 1990s
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Distributed computing architecture
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realm database realm open source object database management system initially mobile android/ios also available platforms xamarin react native others including desktop applications windows licensed apache license 2016 september realm mobile platform announced followed first stable release january 2017 allows two-way synchronization realm object server client side databases belong given logged-in user developer commercial edition released along business license integrating database management systems postgresql april 24th 2019 realm announced entered definitive agreement acquired mongodb realm development began end 2010 alexander stigsen along bjarne christiansen name tightdb company started 2011 combinator promoted nosql configurable durability ability share groups data across multiple processes also even multiple devices clusters tightdb renamed product realm september 2014 released public testing march 2015 funding 20 million disclosed realm mentioned trade press including firms ibm realm announced version 1.0 june 2016 released platform real-time two-way synchronization beta 2016 september release 2017 january provided nodejs sdk server-side applications may 2017 uwp support announced notable features realm following realm developed mostly open-source github source code language-specific bindings core database available aspects realm related sync feature however proprietary closed-source
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Databases
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