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boulder dash boulder dash video game released 1984 first star software atari 8-bit computers numerous versions sequels series numerous interactive platforms including apple ii msx zx spectrum commodore 64 colecovision nes bbc micro acorn electron ibm pc amstrad cpc amiga mac os platforms also influenced games rocks-and-diamonds genre repton addition rather direct clones emerald mine original boulder dash created canadian developers peter liepa chris gray october 28 1983 acquired first star software owns rights game intellectual property including registered trademark boulder dash game protagonist called rockford must dig caves collecting gems diamonds reach exit within time limit avoiding various types dangerous creatures well obstacles like falling rocks constant danger crushed trapped avalanche killed underground explosion january 1 2018 first star software name website owned bbg entertainment gmbh also purchased intellectual property rights pertaining games including boulder dash ii computing said bright colorful animation coupled breezy story line make game momentary diversion compute favorably reviewed boulder dash construction kit noting sample game much difficult original boulder dash mean machines gave game boy port boulder dash score 90 praising one finest video games ever written describing game one buy soon possible noting faithfulness original commodore 64 version publication reviewed nes version favourably stating extremely impressive title one greatest games ever written given 92 rating zx spectrum version placed ninth sinclair top 100 speccy games time ever journalist stuart campbell ign reviewed virtual console release commodore 64 version although graphics sound found dated enjoyed game stating still feels fresh 1984 concluded stating though n't look like much boulder dash rocks
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Computer architecture
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return-to-libc attack return-to-libc attack computer security attack usually starting buffer overflow subroutine return address call stack replaced address subroutine already present process ’ executable memory bypassing no-execute bit feature present ridding attacker need inject code first example attack wild contributed alexander peslyak bugtraq mailing list 1997 posix-compliant operating systems c standard library codice_1 commonly used provide standard runtime environment programs written c programming language although attacker could make code return anywhere codice_1 likely target almost always linked program provides useful calls attacker codice_3 function used execute shell commands non-executable stack prevent buffer overflow exploitation however prevent return-to-libc attack return-to-libc attack existing executable code used hand attacks call preexisting functions stack-smashing protection prevent obstruct exploitation may detect corruption stack possibly flush compromised segment ascii armoring technique used obstruct kind attack ascii armoring system libraries e.g libc addresses contain null byte 0x00 commonly done placing first 0x01010101 bytes memory pages 16 mb dubbed ascii armor region every address including value contains least one null byte makes impossible emplace code containing addresses using string manipulation functions codice_4 however technique work attacker way overflow null bytes stack program large fit first 16 mib protection may incomplete technique similar another attack known return-to-plt instead returning libc attacker uses procedure linkage table plt functions loaded binary e.g codice_5 etc. address space layout randomization aslr makes type attack extremely unlikely succeed 64-bit machines memory locations functions random 32-bit systems aslr provides little benefit since 16 bits available randomization defeated brute force matter minutes
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Computer security
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imperva imperva cyber security software services company provides protection enterprise data application software company headquartered redwood shores california imperva originally named webcohort founded 2002 shlomo kramer amichai shulman mickey boodaei following year company shipped first product securesphere web application database protection web application firewall 2004 company changed name imperva 2011 imperva went public listed new york stock exchange nyse impv 2014 company acquired remaining shares incapsula cloud security gateway startup named skyfence real-time mainframe security auditing agents tomium software 2016 imperva published free scanner designed detect devices infected vulnerable mirai botnet february 2017 imperva sold skyfence forcepoint 40 million february 2017 imperva purchased camouflage data masking company august 2017 imperva named chris hylen former ceo citrix getgo new president ceo imperva former ceo anthony bettencourt resigned chairman board directors february 2018 august 2018 imperva acquired prevoty runtime application self-protection rasp security company also 2018 imperva identified bug popular web browser google chrome allowing attackers steal information via html tags audio video files 2019 imperva acquired private equity firm thoma bravo
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Computer security
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james hall iii james w. hall iii born 1958 former united states army warrant officer signals intelligence analyst germany sold eavesdropping code secrets east germany soviet union 1983 1988 hall convicted espionage july 20 1989 fined 50,000 given dishonorable discharge serving 40-year sentence activities united states disciplinary barracks fort leavenworth kansas released september 2011 hall assigned nsa field station berlin teufelsberg one premier listening posts cold war 1982 1985 spied east germany soviet union 1983 1988 hall betrayed hundreds military secrets includes project trojan worldwide electronic network ability pinpoint armored vehicles missiles aircraft recording signal emissions wartime complete national sigint requirements list nsrl 4258-page document nsa activities government requirements sigint capabilities country hall sometimes spent two hours workday reproducing classified documents provide soviets east germans concerned putting regular duty time consistently worked late complete regular assignments used shopping bags smuggle originals documents photocopied frankfurt flat help east berlin associate using illegal income hall paid cash brand new volvo new truck also made large payment home took flying lessons said given military colleagues least six conflicting stories explain lavish life style 1986 hall stationed fort monmouth new jersey returning germany passed promotion sergeant first class year hall also applying appointment warrant officer part routine background investigation associated warrant appointment one supervisors major hall time staff sergeant commented investigator found strange hall could drive car volvo major could n't afford major went explain asked hall apparent disparity hall responded wealthy aunt died left large trust received 30,000 annually major found story plausible reiterated investigators visit investigators thanked major information told already knew trust hall co-workers fully taken duplicity unusual activities never drew much attention returning germany us traveled vienna austria meet soviet handler co-workers wondered would re-enlist become warrant officer several times conveying dissatisfaction army life course warrant officer rank allowed greater access classified material 1977–1981 tour detachment schneeberg intelligence gathering outpost vii corps 326th asa army security agency company west german-czechoslovakian border cold war hall generally good working relationship peers considered peers average analyst would sometimes erupt become upset trivial day-to-day problems however part considered sociable colleague also quickly picked working knowledge german language james also met future wife worked local restaurant bischofsgruen popular tourist town majority detachment soldiers lived hall eventually arrested december 21 1988 savannah georgia bragging undercover fbi agent period six years sold top secret intelligence data east germany soviet union time hall believed speaking soviet contact conversation claimed motivated money told fbi agent posing soviet intelligence officer n't terribly short money decided n't ever want worry next dollar coming 'm anti-american wave flag much anybody else case hall apparently began based tip manfred severin code-named canna clay stasi instructor acted translator courier james hall rejected german staatschutz cia army foreign counterintelligence fca eventually sponsored big tip james hall james hall apprehended severin exfiltrated west family arrest hall said many indicators visible around involved questionable activity hall activities inflicted grave damage u.s. signals intelligence considered perpetrator one costly damaging breaches security long cold war hall confessed giving handlers information us military liaison mission usmlm tank photography new year eve 1984 march 24 1985 inspection tour soviet military facilities ludwigslust german democratic republic us army major arthur d. nicholson jr. unarmed member usmlm shot death soviet sentry jailhouse interview first ever author kristie macrakis designated treasonous bastard cold war spy fbi also arrested hüseyin yıldırım turk served conduit hall east german intelligence officers hall received 100,000 payments reunification germany july 24 1992 almost documents hall copied handed stasi 13,088 pages total given back nsa federal commissioner stasi records joachim gauck later president germany ordered federal ministry interior us government pressure without consulting informing german parliamentary intelligence oversight committee prerequisite giving files away required law hundred pages retained kept top secret gauck well director agency hansjörg geiger later claimed remember ordered return documents agents place us government military worked mole either kgb russian foreign intelligence service svr include
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Computer security
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mongoose-v mongoose-v 32-bit microprocessor spacecraft onboard computer applications radiation-hardened expanded 10–15 mhz version mips r3000 cpu mongoose-v developed synova inc. melbourne florida usa support nasa goddard space flight center mongoose-v processor first flew nasa earth observing-1 eo-1 satellite launched november 2000 functioned main flight computer second mongoose-v controlled satellite solid-state data recorder mongoose-v requires 5 volts packaged 256-pin ceramic quad flatpack cqfp examples spacecraft use mongoose-v include
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Computer architecture
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jericho forum jericho forum international group working define promote de-perimeterisation initiated david lacey royal mail grew loose affiliation interested corporate cisos chief information security officers discussing topic summer 2003 initial meeting hosted cisco officially founded january 2004 declared success merged open group industry consortium security forum 2014 created founding members claimed one else appropriately discussing problems surrounding de-perimeterisation felt need create forum define solve consistently issues one earlier outputs group position paper entitled jericho forum commandments set principles describe best survive de-perimeterised world jericho forum consisted user members vendor members originally user members allowed stand election december 2008 relaxed allowing either vendor user members eligible election day-to-day management provided open group jericho forum foundations uk nearly initial members worked corporates global responsibilities involvement grew europe north america asia pacific initial focus defining problem de-perimeterisation forum moved onto focussing defining solution delivered publication collaboration oriented architecture coa paper coa framework paper next focus jericho forum securely collaborating clouds involves applying coa concepts emerging cloud computing paradigm basic premise collaborative approach essential gain value cloud final major piece jericho forum work 2009 around identity culminating 2011 publication identity entitlement access management commandments final months jericho forum contributed thinking debate around smart data handed security forum within open group continue jericho forum declared success sunsetted london conference opengroup 29 october 2013 video jericho forum work identity carried global identity foundation not-for-profit organisation working define components global digital identity ecosystem identity commandments directly translating principles behind identity 3.0
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Computer security
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zcoin zcoin cryptocurrency aimed using cryptography provide better privacy users compared cryptocurrencies bitcoin late 2014 poramin insom student masters security informatics johns hopkins university wrote paper implementing zerocoin protocol cryptocurrency matthew green faculty member project create standalone cryptocurrency implementing zerocoin protocol named moneta 28 september 2016 zcoin xzc first cryptocurrency implement zerocoin protocol launched poramin insom team 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 april 2018 cryptographic flaw found zerocoin protocol allowed attackers steal destroy create zcoins zcoin cryptocurrency team acknowledging flaw stated high difficulty performing attacks low probability giving economic benefit attacker 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 month zcoin released academic paper proposing lelantus protocol remove need trusted setup hides origin amount coins transaction 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
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Internet protocols
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simple sensor interface protocol simple sensor interface ssi protocol simple communications protocol designed data transfer computers user terminals smart sensors ssi protocol application layer protocol osi model ssi protocol developed jointly nokia vaisala suunto ionific mermit university oulu currently ssi developed within mimosa project part european union framework programmes research technological development ssi protocol used point-to-point communications uart networking nanoip applications ssi also provides polling sensors streaming sensor data rfid sensor tags ssi specifies memory map sensor data criteria ssi protocol development sample implementation ssi protocol msp430 microcontrollers published open source august 2006 nokia ssi message consists 2-byte header n -byte payload header consists one byte address wildcard 0x3f ascii one byte message/command type different possible values message/command type presented ssi v1.2 command base group commands used find configure sensor units utilizing ssi-protocol group commands used read sensor data infrequently data streaming purposes defined commands point-to-point messaging ssi done ssi/uart ssi uart message consists 3-byte uart header ssi message payload optional cyclic redundancy check checksum use checksum defined ssi message/command type lower case commands indicating use crc header consists start byte 0xfe 2-byte total length message 2-byte bitwise negation length help identify frame start ssi networking variable environment done using nanoip typical case using ssi individual message important nanoudp simplified udp defined nanoip used message format individual messages important nanotcp used provides flow control retransmission cost message size increase network traffic nanoudp message consists 5-byte nanoudp header n -byte message payload optional 2-byte crc checksum header consists one protocol byte 2-byte message length total length including header crc 1-byte source port 1-byte destination port number destination port number 0x28 ssi messages
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Internet protocols
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k1810vm86 k1810vm86 soviet 16-bit microprocessor clone intel 8086 cpu binary pin compatible developed 1982 1985 original k1810vm86 supported clock frequency 5 mhz 8 mhz allowed later k1810vm86m к1810вм86m corresponding intel 8086-2 k1810vm86 manufactured plastic 40-pin dual in-line package kr1810vm86 кр1810вм86 40-pin ceramic dual in-line package km1810vm86 км1810вм86 commercial version m1810vm86 м1810вм86 military version clone related intel 8088 8-bit bus manufactured k1810vm88 also plastic ceramic packages k1810vm86 manufactured n-mos process family consists following chips brevity table lists chip variants plastic dip prefix кр listed separately variants ceramic dip prefix км commercial version prefix м military version additionally many devices k580 series could used k1810 series well unlike earlier kr580vm80a popular soviet union little used elsewhere k1810vm86 widely used throughout eastern bloc due one first 16-bit microprocessors available among one x86 instruction set allowing run ms-dos examples personal computers built based k1810vm86 8-bit bus variant k1810vm88 cmos versions equivalent intel 80c86 named kr1834vm86 кр1834вм86 developed kiev 1989 1990 manufactured minsk kr1835vm86 кр1835вм86 original kr1810vm86 still shown price list 2 february 2018 kvazar plant kiev together various support chips k580 k1810 series newer cmos versions appear longer production clone intel 80c286 manufactured name kr1847vm286 кр1847вм286 apparently see widespread use processors x86 instruction set designed soviet union much later 1875vd1t 1875вд1т equivalent intel 80c186 1875vd2t 1875вд2т equivalent intel 80386extb
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Computer architecture
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marc maiffret marc maiffret chief technology officer beyondtrust security compliance management company maiffret joined beyondtrust way acquisition eeye digital security co-founded 1998 along firas bushnaq maiffret created one first vulnerability management web application firewall products date deployed worldwide numerous product awards maiffret credited discovering first major vulnerability discoveries microsoft software leads beyondtrust ’ advanced research labs responsible identifying new trends enterprise security benefit beyondtrust product roadmap maiffret left eeye three-year period served chief security architect fireeye returned eeye july 2010 brief time away eeye maiffret also founded invenio security eventually merged veteran consulting firm digitrust group digitrust maiffret managed company professional services division including network security consulting managed security services maiffret also responsible helping expand firm ’ internal research development efforts maiffret known running eeye top security research team nearly 10 years present well discovering critical microsoft security vulnerabilities code red maiffret accepted three invitations testify united states congress matters national cybersecurity critical security threats posed public private infrastructures named one people magazine magazine ’ 30 people 30 featured cover stories details los angeles times entrepreneur magazine usa today addition numerous television appearances maiffret featured mtv ’ true life 'm hacker october 1999 marc guest speaker episode 91 security leo laporte steve gibson influential industry marc spoken variety conferences including issa los angeles infosec 2011 featured several publications including cnn fox news security week sc magazine pc world computer world marc 'chameleon hacking group 'rhino9 marc also known 'sn1per hacking group no|d august 22 2013 yahoo news reported maiffret prompting hackers support raising 10,000 reward khalil shreateh august 20 maiffret stated already raised 9,000 efforts including 2,000 contributed hackers alike denounced facebook actions maiffret said sitting palestine research five-year-old laptop looks like half broken something might help big way
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Computer security
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qualcomm qualcomm incorporated american multinational semiconductor telecommunications equipment company designs markets wireless telecommunications products services derives revenue chipmaking bulk profit patent licensing businesses company headquarter located san diego california united states 224 worldwide locations parent company qualcomm incorporated qualcomm number wholly owned subsidiaries qualcomm cdma technologies qct sells qualcomm ’ products services including chipsets qualcomm technology licensing qtl responsible patent licensing business qualcomm technologies inc. qti operates nearly qualcomm r activities qualcomm created july 1 1985 seven former linkabit employees led dr. irwin jacobs company named qualcomm “ quality communications. ” started contract research development center largely government defense projects qualcomm merged omninet 1988 raised 3.5 million funding order produce omnitracs satellite communications system trucking companies qualcomm grew eight employees 1986 620 employees 1991 due demand omnitracs 1989 qualcomm 32 million revenues 50 percent omnitracs contract schneider national omnitracs profits helped fund qualcomm research development code-division multiple access cdma technologies cell phone networks qualcomm operating loss 1990s due investment cdma research obtain funding company filed initial public offering september 1991 raising 68 million additional 486 million raised 1995 sale 11.5 million shares second funding round done raise money mass manufacturing cdma-based phones base-stations equipment us-based cellular networks announced would adopt cdma standard company 383 million annual revenue 1995 814 million 1996 1991 qualcomm acquired eudora email client software pc could used omnitracs system acquisition associated widely used email client company little-known time 1998 qualcomm restructured leading 700-employee layoff cell-phone manufacturing business also spun-off order focus higher-margin patents business following year qualcomm fastest growing stock market 2,621 percent growth one year 2000 qualcomm grown 6,300 employees 3.2 billion revenues 670 million profit 39 percent sales cdma technology followed licensing 22 wireless 22 products 17 around time qualcomm established offices europe asia pacific latin america 2001 65 percent qualcomm revenues originated outside united states 35 percent coming south korea 2005 paul e. jacobs son qualcomm founder dr. irwin jacobs appointed qualcomm new ceo whereas irwin jacobs focused cdma patents paul jacobs refocused much qualcomm new research development projects related internet things qualcomm announced steven mollenkopf would succeed paul jacobs ceo december 2013 mollenkopf said would expand qualcomm focus wireless technology cars wearable devices new markets european commission fined qualcomm €997 million abuse dominant market position january 24 2018 march 16 2018 qualcomm removed executive chairman paul jacobs broached long-shot bid buyout earlier week 2018 qualcomm filed lawsuit intel several meet-and-confers exchanges written correspondence may 18 intel appeared willing cooperate offering 'limited supplemental production technical materials relating relevant components designed 2018 iphone models exchange qualcomm agreement limited production would satisfy certain requests document subpoena us federal court filing states court us march 15 2019 ruled apple must indemnify qualcomm infringing three patents related mobile technologies jury ruled apple pay 31 million chip maker 1.41 per iphone used company ’ technology without authorization fiscal year 2018 qualcomm reported loss us 4.86 billion annual revenue us 22.7 billion increase 2 previous fiscal cycle qualcomm shares traded 51 75 per share market capitalization end fiscal 2018 valued us 105 billion company ranked 133rd fortune 500 list largest united states corporations revenue qualcomm pioneered commercialization cdmaone is-95 standard wireless cellular communications following cdma2000 early standard third-generation 3g mobile today company leading patent holder advanced 3g mobile technologies including cdma2000 1xev-do evolutions wcdma higher-speed variant known hspa evolutions td-scdma well patents 4g license streams patents inventions related products major component qualcomm business june 2011 qualcomm announced would release set application programming interfaces geared give web-based applications deeper links hardware beginning 1991 qualcomm participated development globalstar satellite system along loral space communications uses low earth orbit leo satellite constellation consisting 44 active satellites system used voice telephony via hand-held satellite phones asset tracking data transfer using mobile satellite modems system designed normal is-95 system used satellite bent pipe repeater transfer cellular signals handset terrestrial base station unlike iridium system routes phone calls satellites globalstar satellite must always able see handset base station establish connection therefore coverage earth poles satellite orbits also coverage locations large globalstar base stations view locations south atlantic example globalstar hardware manufactured qualcomm like satellite phone networks globalstar went bankrupt 1999 bought group investors currently running system january 2017 apple announced 1 billion lawsuit qualcomm overcharging chips failing pay 1 billion rebates qualcomm however rejected accusations calling claims baseless week apple lawsuit qualcomm shares dropped federal trade commission accused company demanding excessive royalties technologies essential industry standards qualcomm sued group shareholders wake aforementioned ftc ruling apple lawsuit january 4 2019 ftc trial began judge lucy koh united states district court northern district california january 24 2018 european commission announced €997 million fine 1.2 billion 4.9 2017 turnover qualcomm violating antitrust laws means deals apple january 14 2019 apple coo jeff williams said apple wanted use qualcomm modems iphone xs xr qualcomm refused sell apple sued licensing practices leading apple using intel modems instead april 16 2019 opening arguments begun suit two companies settled apple pay unspecified amount enter six-year patent licensing agreement multi-year agreement qualcomm provide hardware company intel concurrently announced would longer develop 5g modems mobile devices later announced july 2019 would sell majority smartphone modem business apple 1 billion april 2006 dispute reliance communications qualcomm royalty fees cost qualcomm approximately 11.7b market capitalization july 2007 reliance qualcomm decided settle matter agreed expand use cdma technology india june 2007 u.s. international trade commission blocked import new cell phone models based particular qualcomm microchips found qualcomm microchips infringe patents owned broadcom broadcom also initiated patent litigation u.s. courts issue issue software designed extend battery life chips users make out-of-network calls october itc administrative judge made initial ruling qualcomm violated broadcom patent covering feature commission later affirmed decision sprint nextel corp. using software patch qualcomm get around u.s. government agency ban new phones qualcomm chips august 2007 judge rudi brewster held qualcomm engaged litigation misconduct withholding relevant documents lawsuit brought broadcom qualcomm employees lied involvement july 2009 south korea antitrust watchdog fined qualcomm record won260bn 207m unfair business practices related chipset sales sparking strong protests company fair trade commission accused qualcomm abusing dominant position korean market cdma mobile phone chips charging higher royalties handset makers bought modem chips competitors offering rebates customers bought products mainly us group regulator said statement 2009 qualcomm broadcom entered settlement multi-year patent agreement ending litigation companies 2012 federal probe launched company ’ compliance foreign corrupt practices act bars companies well individuals bribing foreign officials gain business 2014 china anti-monopoly regulator announced qualcomm suspected overcharging abusing market position february 2015 china moved fine qualcomm record 975 million tactics government claimed hurt consumers july 16 2015 european commission announced opened two antitrust investigations qualcomm behavior field baseband chipsets consumer devices july 2016 group women filed class-action gender discrimination lawsuit qualcomm alleging firm discriminated women science technology engineering mathematics areas class 3,400 employees suit settled august 2017 firm agreed pay 19.5 million plaintiff law firm said company also institute significant changes policies practices help eliminate gender disparities foster equal employment opportunity going forward march 2017 south korea found qualcomm prevented samsung selling chips phone makers current umts air interfaces part based qualcomm patents royalties patents represent significant part qualcomm revenue followed series patent-related lawsuits antitrust complaints spearheaded broadcom us 2006 broadcom started series patent-related lawsuits antitrust complaints qualcomm get broadcom regarded fair terms access w-cdma technologies broadcom soon joined nokia others complaints also filed european commission 2007 european commission launched inquiry qualcomm possible abusing dominant position market third-generation phones complaints first lodged 2005 leading handset manufacturers ericsson nokia nec panasonic texas instruments october 2008 nokia announced make one-time payment 2.29 billion us qualcomm part patent agreement company chinese tdscdma 3g technology developed primarily avoid qualcomm licensing fees although qualcomm claims chinese technology still infringes many qualcomm patents qchat push-to-talk ptt technology qchat software application developed qualcomm internet services qis division qualcomm part qualcomm wireless internet group qis offers set software products content enablement services support accelerate growth wireless data market qualcomm developed qchat provide reliable method instant connection two-way communication users different locations operating within type network architecture prior existence cellular personal communications services networks type communication limited private land mobile radio system lmr technology used public safety utility service agencies lmr limitations specifically usage restricted geographic coverage area use disparate frequency bands qchat application developed brew platform ptt communication technology 3g networks qchat handsets server software allow users connect instantaneously qchat users anywhere world push button addition qchat enables one-to-one private one-to-many group calls 3g networks qchat uses standard voice internet protocol voip technologies voip voice delivery mechanism uses internet protocol manage delivery voice information voice information sent digital form ip-based data networks including cdma discrete packets rather traditional circuit-switched protocols used public switched telephone network pstn qchat users 3g wireless devices connect worldwide either private group calls push button qchat uses voice internet protocol voip technologies allow subscribers communicate using ptt button handset instead making standard cellular call qchat calls created combining separate point-to-point connections ip endpoint process managed qchat applications server deployed carrier ip-based wide area network wan initiate call user presses ptt button receives immediate indication whether call recipient available caller begin speaking immediately recipient unavailable caller simply hear negative response tone instead busy signal voicemail october 16 2006 sprint nextel announced agreement qualcomm use qchat provide high performance push-to-talk services customers nationwide sprint pcs network using cdma2000 1xev-do revision technology qchat able inter-operate iden push-to-talk handsets nextel national network sprint phones supporting qchat technology released starting april 2008 trial business customers kansas colorado sprint announced nextel direct connect devices powered qchat available 40 markets june 2008 ending production new qchat devices november 2009 supported models included august 2016 computer security company check point found several serious security problems qualcomm chips bug called quadrooter ability let hackers read information android phones even worse hackers full access affected user installs app exploits one vulnerabilities according check point affects 900 million android users affected phones include recent android phones check point published scan tool android users blackberry developing repair tool qualcomm released fixes four issues three included android updates top google phones time publication bug
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Computer architecture
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space-cadet keyboard space-cadet keyboard keyboard designed john l. kulp used lisp machines massachusetts institute technology mit inspired several still-current jargon terms field computer science influenced design emacs inspired knight keyboard developed knight tv system used mit incompatible timesharing system symbolics-labeled version shown used lm-2 symbolics repackaged version mit cadr later symbolics systems used greatly simplified keyboard symbolics keyboard retained basic layout commonly used function modifier keys space-cadet keyboard space-cadet keyboard equipped seven modifier keys four keys bucky bits three shift keys called labeled top introduced earlier knight keyboard introduced keyboard group row thus allowing easy pressing several modifier keys via chording example could pressed fingers one hand pressing another key hand many keys three symbols accessible via shift keys letter symbol top greek letter front example key l two-way arrow ↔ top greek letter lambda λ front pressing key right hand playing appropriate chord left hand shift keys user could get following results might addition typed combination keys keyboard possible type 8,000 different characters allowed user type complicated mathematical text also thousands single-character commands disposal many users willing memorise command meanings many characters reduced typing time attitude shaped interface emacs compare use key vi due convenient position key adm-3a terminal users however thought many bucky bits overkill objected design grounds keyboard require three four hands operate result emacs making frequent use multiple modifiers easy space-cadet keyboard substantially harder use modern keyboards whose layout generally follows model ibm pc keyboard modifier keys grouped together thus harder press together also reason emacs uses m- prefix describing key presses m- stood space-cadet keyboard emacs ported pcs key used place keyboard included key limited application support also included four roman numeral keys allowed easy interaction lists four fewer choices
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Programming language topics
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gnu common lisp gnu common lisp gcl gnu project ansi common lisp compiler evolutionary development kyoto common lisp produces native object code first generating c code calling c compiler gcl implementation choice several large projects including mathematical tools maxima axiom hol88 acl2 gcl runs eleven different architectures linux freebsd solaris mac os x microsoft windows gcl remains active development stable releases 2014-10-28 prerelease development followed using git revision control system
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Programming language topics
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andrew appel andrew wilson appel born 1960 eugene higgins professor computer science princeton university new jersey especially well-known compiler books modern compiler implementation ml series well compiling continuations also major contributor standard ml new jersey compiler along david macqueen john h. reppy matthias blume others one authors rog-o-matic andrew appel son mathematician kenneth appel proved four-color theorem 1976 appel gained a.b summa cum laude physics princeton university 1981 ph.d. computer science carnegie-mellon university 1985 became acm fellow 1998 due research programming languages compilers 1981 appel developed better approach n-body problem linearithmic instead quadratic time july 2005 july 2006 visiting researcher institut national de recherche en informatique et en automatique inria rocquencourt france sabbatical princeton university andrew appel campaigns issues related interaction law computer technology testified penalty phase microsoft antitrust case 2002 opposed introduction computerized voting machines deemed untrustworthy 2007 received attention purchased number voting machines purpose investigating security
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Programming language topics
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oracle enterprise manager oracle enterprise manager oem em set web-based tools aimed managing software hardware produced oracle corporation well non-oracle entities oracle enterprise manager includes three releases oracle enterprise manager database control oldest arguably best-known release aims manage oracle databases originated java client able configure manage databases oracle application server also web-interface manage application server managing lots databases application servers according oracle corporation preferably grid solution one could use oracle enterprise manager grid control manage multiple instances oracle deployment platforms recent edition also allows management monitoring platforms microsoft .net microsoft sql server netapp filers bea weblogic others partners organizations build extensions oracle enterprise manager make available enterprise manager users via oracle hosted web site called oracle enterprise manager extensibility exchange system monitoring features include monitoring functionality supports detection notification impending problems monitors oracle database instances oracle real application clusters oracle application server farms clusters oem grid control comes set performance health metrics allow monitoring technology components applications application servers databases well back-end components rely hosts operating systems storage architecture oem grid control three distinct components oma runs target host collects information hardware operating system applications run target oms runs one two servers collects data generated omas oms pulls information omas aggregates collections repository oms also acts user-interface — generating web-pages database administrators view status systems services omr comprises instance oracle database stores data collected oms installers make omr highly available fault-tolerant running oracle rac instance across multiple nodes plug-ins omas customise manipulate data presented oem extending data omas collect administrators customize analysis data management packs look specific collections data display system performance release oem allows design configuration custom plug-ins monitor application desired omas collect data using custom-built plug-in transmit results xml format back oms stores analyzes data desired oracle enterprise manager continues expand monitoring scope offering management plug-ins non-oracle components oracle-developed developed partnership third-party vendors example plug-ins veritas storage foundation vmware vsphere emc clariion available key features oem grid control oracle release since 13c oracle enterprise manager performs much activity intelligent agents oracle corporation refers oracle management agents run autonomous proxy processes managed node perform execution monitoring tasks oracle enterprise manager communicating using hypertext transfer protocol http https default upon installation oma enables several packs change management performance tuning diagnostics configuration management without regard customer licensed users need de-select unlicensed packs installing agent target database oem uses default codice_1 schema oracle database super-administrator account/repository utility programs codice_2 codice_3 carry actual functions oem also provides command-line alternative emcli em command line interface verbs provide functionality ui-based em
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Databases
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tunneling protocol computer networks tunneling protocol communications protocol allows movement data one network another involves allowing private network communications sent across public network internet process called encapsulation tunneling involves repackaging traffic data different form perhaps encryption standard hide nature traffic run tunnel tunneling protocol works using data portion packet payload carry packets actually provide service tunneling uses layered protocol model osi tcp/ip protocol suite usually violates layering using payload carry service normally provided network typically delivery protocol operates equal higher level layered model payload protocol tunneling protocol may example allow foreign protocol run network support particular protocol running ipv6 ipv4 another important use provide services impractical unsafe offered using underlying network services providing corporate network address remote user whose physical network address part corporate network users also use tunneling sneak firewall using protocol firewall would normally block wrapped inside protocol firewall block http firewall policy specifically exclude kind wrapping trick function get around intended firewall policy set interlocked firewall policies another http-based tunneling method uses http connect method/command client issues http connect command http proxy proxy makes tcp connection particular server port relays data server port client connection creates security hole connect-capable http proxies commonly restrict access connect method proxy allows connections specific ports 443 https example network layer network layer generic routing encapsulation gre protocol running ip ip protocol number 47 often serves carry ip packets rfc 1918 private addresses internet using delivery packets public ip addresses case delivery payload protocols payload addresses incompatible delivery network also possible establish connection using data link layer layer 2 tunneling protocol l2tp allows transmission frames two nodes tunnel encrypted default relies tcp/ip protocol chosen determine level security ssh uses port 22 enable data encryption payloads transmitted public network internet connection thereby providing vpn functionality ipsec end-to-end transport mode also operate tunneling mode trusted security gateway understand particular protocol stack imposed tunneling network engineers must understand payload delivery protocol sets secure shell ssh tunnel consists encrypted tunnel created ssh protocol connection users may set ssh tunnels transfer unencrypted traffic network encrypted channel example microsoft windows machines share files using server message block smb protocol non-encrypted protocol one mount microsoft windows file-system remotely internet someone snooping connection could see transferred files mount windows file-system securely one establish ssh tunnel routes smb traffic remote fileserver encrypted channel even though smb protocol contains encryption encrypted ssh channel travels offers security ssh connection established tunnel starts ssh listening port remote local host connections forwarded specified address port originating opposing remote local previously host tunneling tcp- encapsulating payload ppp tcp-based connection ssh port forwarding known tcp-over-tcp induce dramatic loss transmission performance problem known tcp meltdown virtual private network software may instead use protocol simpler tcp tunnel connection however often problem using openssh port forwarding many use cases entail tcp-over-tcp tunneling meltdown avoided openssh client processes local client-side tcp connection order get actual payload sent sends payload directly tunnel tcp connection server side openssh server similarly unwraps payload order wrap routing final destination naturally wrapping unwrapping also occurs reverse direction bidirectional tunnel ssh tunnels provide means bypass firewalls prohibit certain internet services long site allows outgoing connections example organization may prohibit user accessing internet web pages port 80 directly without passing organization proxy filter provides organization means monitoring controlling user sees web users may wish web traffic monitored blocked organization proxy filter users connect external ssh server create ssh tunnel forward given port local machine port 80 remote web server access remote web server users would point browser local port nowiki http //localhost/ /nowiki ssh clients support dynamic port forwarding allows user create socks 4/5 proxy case users configure applications use local socks proxy server gives flexibility creating ssh tunnel single port previously described socks free user limitations connecting predefined remote port server application n't support socks proxifier used redirect application local socks proxy server proxifiers proxycap support ssh directly thus avoiding need ssh client recent versions openssh even allowed create layer 2 layer 3 tunnels ends enabled tunneling capabilities creates codice_1 layer 3 default codice_2 layer 2 virtual interfaces ends connection allows normal network management routing used used routers traffic entire subnetwork tunneled pair codice_2 virtual interfaces function like ethernet cable connecting ends connection join kernel bridges
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Computer security
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live file system live file system term microsoft uses describe packet writing method creating discs windows vista later allows files added incrementally media discs use udf file system live file system option used default autoplay formatting/erasing cd/dvd -r -rw older windows versions support reading latest udf versions users create dvd/cds windows vista using udf 2.50 may readable systems including windows xp older pre-mac os 10.5 apple systems unless third-party udf reader driver installed ensure compatibility disks created windows vista udf 2.01 lower selected
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Computer file systems
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phase-fired controller phase-fired control pfc also called phase cutting phase angle control method power limiting applied ac voltages works modulating thyristor scr triac thyratron gated diode-like devices conduction predetermined phase applied waveform phase-fired control pfc often used control amount voltage current power power supply feeds load create average value output supply dc output time base importance deciding pulse supply value pulsed continuous pfc differs pulse-width modulation pwm addresses supplies output modulated waveform sinusoidal ac waveform national grid outputs becomes important supply pulse correct position modulation cycle known value achieved example controller could turn peak waveform base cycle time base taken consideration phase-fired controllers take name fact trigger pulse output certain phase input modulation cycle essence pfc controller synchronise modulation present input phase-fired controllers use thyristors solid state switching devices control elements thyristor-based controllers may utilise gate turn-off gto thyristors allowing controller decide switch output turn rather wait waveform return zero phase-fired controller like buck topology switched-mode power supply able deliver output maximum equal present input minus losses occurring control elements provided modulation cycle predictable repetitive national grid ac mains obtain output lower input phase-fired control simply switches given phase angle input modulation cycle triggering device conduction phase angle greater 0 degrees point modulation cycle starts fraction total energy within cycle present output achieve boost -like effect pfc designs must derated maximum present input higher nominal output requirements supply first turned operating nominal conditions controller continually delivering less 100 input boost required controller delivers percentage closer 100 maximum input available derating mains powered phase-fired controllers important often used control resistive loads heating elements time resistance heating elements increase account phase-fired control must able provide degree extra voltage draw heating current element way achieving purposely design supply require less 100 input modulation cycle elements first put place progressively opening supply towards delivering 100 input modulation cycle elements age common application dimmer switches domestic lighting control industrial applications previously extremely expensive heavy multi-tapped transformers used supplies elements corresponding winding tap connected element produce desired temperature limited temperature resolution number tap combinations available often find way controllers designed equipment electric ovens furnaces modern usually high power equipment transformer replaced phase-fired controllers connecting load directly mains resulting substantially cheaper lighter system however method usually limited use equipment would unrealistic without removal mains transformer means load electrical continuity input industrial ovens furnaces input often national grid ac electrically referenced ground controller output referenced ground user need contact earth one output terminals risk receiving electrical shock many high-power items equipment running three-phase 415 v high current inputs enclosure framework present earthed grounded serious risk must carefully assessed first patent phase-fired controllers derives 1912 however realization first possible 1920s mercury-arc valve rectifiers control grids became available however method voltage regulation common time limitations mercury arc valves became widespread invention solid-state thyristors end 1950s burst-fired controllers
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Internet protocols
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syntax programming languages computer science syntax computer language set rules defines combinations symbols considered correctly structured document fragment language applies programming languages document represents source code markup languages document represents data syntax language defines surface form text-based computer languages based sequences characters visual programming languages based spatial layout connections symbols may textual graphical documents syntactically invalid said syntax error.when designing syntax language designer starts writing examples legal illegal strings trying figure general rules examples syntax therefore refers form contrasted semantics – meaning processing computer languages semantic processing generally comes syntactic processing however cases semantic processing necessary complete syntactic analysis done together concurrently compiler syntactic analysis comprises frontend semantic analysis comprises backend middle end phase distinguished computer language syntax generally distinguished three levels distinguishing way yields modularity allowing level described processed separately often independently first lexer turns linear sequence characters linear sequence tokens known lexical analysis lexing second parser turns linear sequence tokens hierarchical syntax tree known parsing narrowly speaking thirdly contextual analysis resolves names checks types modularity sometimes possible many real-world languages earlier step depends later step – example lexer hack c tokenization depends context even cases syntactical analysis often seen approximating ideal model parsing stage divided two parts parse tree concrete syntax tree determined grammar generally far detailed practical use abstract syntax tree ast simplifies usable form ast contextual analysis steps considered form semantic analysis adding meaning interpretation syntax alternatively informal manual implementations syntactical rules would difficult awkward describe implement formally levels generally correspond levels chomsky hierarchy words regular language specified lexical grammar type-3 grammar generally given regular expressions phrases context-free language cfl generally deterministic context-free language dcfl specified phrase structure grammar type-2 grammar generally given production rules backus–naur form bnf phrase grammars often specified much constrained grammars full context-free grammars order make easier parse lr parser parse dcfl linear time simple lalr parser even simpler parser efficient parse grammars whose production rules constrained principle contextual structure described context-sensitive grammar automatically analyzed means attribute grammars though general step done manually via name resolution rules type checking implemented via symbol table stores names types scope tools written automatically generate lexer lexical specification written regular expressions parser phrase grammar written bnf allows one use declarative programming rather need procedural functional programming notable example lex-yacc pair automatically produce concrete syntax tree parser writer must manually write code describing converted abstract syntax tree contextual analysis also generally implemented manually despite existence automatic tools parsing often implemented manually various reasons – perhaps phrase structure context-free alternative implementation improves performance error-reporting allows grammar changed easily parsers often written functional languages haskell scripting languages python perl c c++ example codice_1 syntactically valid lisp program assuming 'add function exists else name resolution fails adding 1 1 however following invalid note lexer unable identify first error – knows producing token left_paren remainder program invalid since word rule begins second error detected parsing stage parser identified list production rule due token match thus give error message general may ambiguous type errors undeclared variable errors sometimes considered syntax errors detected compile-time usually case compiling strongly-typed languages though common classify kinds error semantic errors instead example python code contains type error adds string literal integer literal type errors kind detected compile-time detected parsing phrase analysis compiler uses separate rules allow integerliteral integerliteral stringliteral integerliteral though likely compiler use parsing rule allows expressions form literaloridentifier literaloridentifier error detected contextual analysis type checking occurs cases validation done compiler errors detected runtime dynamically typed language type determined runtime many type errors detected runtime example python code syntactically valid phrase level correctness types b determined runtime variables types python values whereas disagreement whether type error detected compiler called syntax error rather static semantic error type errors detected program execution time always regarded semantic rather syntax errors syntax textual programming languages usually defined using combination regular expressions lexical structure backus–naur form grammatical structure inductively specify syntactic categories nonterminals terminal symbols syntactic categories defined rules called productions specify values belong particular syntactic category terminal symbols concrete characters strings characters example keywords define let void syntactically valid programs constructed language different equivalent grammars equivalent regular expressions lexical levels different phrase rules generate language using broader category grammars lr grammars allow shorter simpler grammars compared restricted categories grammar may require longer grammars rules different equivalent phrase grammars yield different parse trees though underlying language set valid documents simple grammar defined using notation regular expressions extended backus–naur form describes syntax s-expressions data syntax programming language lisp defines productions syntactic categories expression atom number symbol list grammar specifies following decimal digits upper- lower-case characters parentheses terminal symbols following examples well-formed token sequences grammar 'codice_2 'codice_3 'codice_4' grammar needed specify programming language classified position chomsky hierarchy phrase grammar programming languages specified using type-2 grammar i.e. context-free grammars though overall syntax context-sensitive due variable declarations nested scopes hence type-1 however exceptions languages phrase grammar type-0 turing-complete languages like perl lisp specification implementation language allows constructs execute parsing phase furthermore languages constructs allow programmer alter behavior parser combination effectively blurs distinction parsing execution makes syntax analysis undecidable problem languages meaning parsing phase may finish example perl possible execute code parsing using codice_5 statement perl function prototypes may alter syntactic interpretation possibly even syntactic validity remaining code colloquially referred perl parse perl code must executed parsing modify grammar strongly even perl parse perl undecidable similarly lisp macros introduced codice_6 syntax also execute parsing meaning lisp compiler must entire lisp run-time system present contrast c macros merely string replacements require code execution syntax language describes form valid program provide information meaning program results executing program meaning given combination symbols handled semantics either formal hard-coded reference implementation syntactically correct programs semantically correct many syntactically correct programs nonetheless ill-formed per language rules may depending language specification soundness implementation result error translation execution cases programs may exhibit undefined behavior even program well-defined within language may still meaning intended person wrote using natural language example may possible assign meaning grammatically correct sentence sentence may false following c language fragment syntactically correct performs operation semantically defined p null pointer operations p- real p- im meaning simpler example syntactically valid semantically defined uses uninitialized variable even though compilers programming languages e.g. java c would detect uninitialized variable errors kind regarded semantic errors rather syntax errors quickly compare syntax various programming languages take look list hello world program examples
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Programming language topics
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gamin gamin monitoring system files directories independently implements subset fam file alteration monitor running service allows detection modifications file directory gam_server functions daemon gamin word gamin french also female form gamine refers boy gamin project built earlier project called marmot french means child brat linux gamin uses inotify dnotify monitor filesystem activity freebsd gamin uses kqueue/kevent native freebsd kernel event notification mechanism case kqueue one major drawback compared inotify inotify filename-based monitoring facility kqueue uses file descriptors identification monitored files freebsd gam_server open file monitored directory issue monitoring directories many files stored system could easily reach kernel limits maximum file descriptor count kern.maxfiles kern.maxfilesperproc
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Operating systems
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knopperdisk knopperdisk operating system specifically designed usb pen drive floppy disks knopperdisk fairly minimal text system used rescue disk although usb pen drive version software packages installed used different purposes despite similarity name knoppix based gentoo linux
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Operating systems
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windows imaging format windows imaging format wim file-based disk image format developed microsoft help deploy windows vista subsequent versions windows operating system family well windows fundamentals legacy pcs like disk image formats wim file contains set files associated filesystem metadata however unlike sector-based formats iso vhd wim file-based fundamental unit information wim file primary advantages file-based hardware independence single-instance storage file referenced multiple times filesystem tree since files stored inside single wim file overhead opening closing many individual files reduced cost reading writing many thousands individual files local disk negated hardware software-based disk caching well sequential reading writing data wim files contain multiple disk images referenced either numerical index unique name due use single-instance storage successive disk image common previous images added wim file less new data added wim also split spanned multiple parts .swm extension wim images made bootable windows boot loader supports booting windows within wim file windows setup dvd windows vista later use wim files case boot.wim contains bootable version windows pe installation performed setup files held install.wim imagex command-line tool used create edit deploy windows disk images windows imaging format distributed part free windows automated installation kit waik starting windows vista windows setup uses waik api install windows first distributed prototype imagex build 6.0.4007.0 main.030212-2037 allowed microsoft oem partners experiment imaging technology developed parallel longhorn alpha prototypes first introduced milestone 4 longhorn project used later builds longhorn build 6.0.5384.4 added significant advantages previous versions like read-only read/write folder mounting capabilities splitting multiple image files swm wim filter driver latest lzx compression algorithms used since pre-rc release candidates windows vista deployment image service management tool dism tool introduced windows 7 windows server 2008 r2 perform servicing tasks windows installation image online image i.e one user running offline image within folder wim file features include mounting unmounting images querying installed device drivers offline image adding device driver offline image possible repair dism image using either windows installation cd windows update windows server 2012 windows 8 dism incorporated majority imagex functions imagex still needed image capture however dism deprecated imagex windows 8 since april 30 2012 open source library handling wim format available library used unix-like systems well windows thanks project gnu/linux distributions imagex clone called wimlib-imagex allows mounting wim images managing read/write like file system wim images basically using lzx compression algorithm accessed using file archivers like 7-zip operating systems might support format still possible convert .wim images commonly used iso image using windows assessment deployment kit windows
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Operating systems
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multiple dispatch multiple dispatch multimethods feature programming languages function method dynamically dispatched based run time dynamic type general case attribute one arguments generalization single dispatch polymorphism function method call dynamically dispatched based derived type object method called multiple dispatch routes dynamic dispatch implementing function method using combined characteristics one arguments developers computer software typically organize source code named blocks variously called subroutines procedures subprograms functions methods code function executed calling – executing piece code references name transfers control temporarily called function function execution completed control typically transferred back instruction caller follows reference function names usually selected descriptive function purpose sometimes desirable give several functions name often perform conceptually similar tasks operate different types input data cases name reference function call site sufficient identifying block code executed instead number type arguments function call also used select among several function implementations conventional i.e. single-dispatch object-oriented programming languages invoking method sending message smalltalk calling member function c++ one arguments treated specially used determine potentially many methods name applied many languages special argument indicated syntactically example number programming languages put special argument dot making method call codice_1 codice_2 would produce roar whereas codice_3 would produce cheep contrast languages multiple dispatch selected method simply one whose arguments match number type function call special argument owns function/method carried particular call common lisp object system clos early well-known example multiple dispatch working languages discriminate data types compile time selecting among alternatives occur act creating alternative functions compile time selection usually referred overloading function programming languages defer data type identification run time i.e. late binding selection among alternative functions must occur based dynamically determined types function arguments functions alternative implementations selected manner referred generally multimethods run time cost associated dynamically dispatching function calls languages distinction overloading multimethods blurred compiler determining whether compile time selection applied given function call whether slower run time dispatch needed estimate often multiple dispatch used practice muschevici et al studied programs use dynamic dispatch analyzed nine applications mostly compilers written six different languages common lisp object system dylan cecil multijava diesel nice results show 13–32 generic functions use dynamic type one argument 2.7–6.5 use dynamic type multiple arguments remaining 65–93 generic functions one concrete method overrider thus considered use dynamic types arguments study reports 2–20 generic functions two 3–6 three concrete function implementations numbers decrease rapidly functions concrete overriders multiple dispatch used much heavily julia multiple dispatch central design concept origin language collecting statistics muschevici average number methods per generic function found julia standard library uses double amount overloading languages analyzed muschevici 10 times case binary operators data papers summarized following table dispatch ratio codice_4 average number methods per generic function choice ratio codice_5 mean square number methods better measure frequency functions large number methods degree specialization dos average number type-specialized arguments per method i.e. number arguments dispatched theory multiple dispatching languages first developed castagna et al. defining model overloaded functions late binding yielded first formalization problem covariance contravariance object-oriented languages solution problem binary methods distinguishing multiple single dispatch may made clearer example imagine game among user-visible objects spaceships asteroids two objects collide program may need different things according hit language multiple dispatch common lisp might look like common lisp example shown similarly methods explicit testing dynamic casting used presence multiple dispatch traditional idea methods defined classes contained objects becomes less appealing—each collide-with method attached two different classes one hence special syntax method invocation generally disappears method invocation looks exactly like ordinary function invocation methods grouped classes generic functions julia built-in multiple dispatch central language design julia version example might look like collide_with x :asteroid :asteroid ... deal asteroid hitting asteroid collide_with x :asteroid :spaceship ... deal asteroid hitting spaceship collide_with x :spaceship :asteroid ... deal spaceship hitting asteroid collide_with x :spaceship :spaceship ... deal spaceship hitting spaceship perl 6 like past versions uses proven ideas languages type systems shown offer compelling advantages compiler-side code analysis powerful user-side semantics via multiple dispatch multimethods multisubs since operators subroutines also multiple dispatched operators along usual type constraints also constraints allow making specialized subroutines subset mass real 0 ^..^ inf role stellar-object class asteroid stellar-object class spaceship stellar-object str destroyed obliterated destroyed mangled str damaged « damaged 'collided 'was damaged » multi sub infix « » stellar-object stellar-object b a.mass b.mass proto sub collide stellar-object stellar-object multi sub collide b b multi sub collide b b multi sub collide b multi sub collide spaceship spaceship b == b multi sub collide asteroid mass asteroid mass b spaceship enterprise .= new mass 1 :name 'the enterprise collide asteroid.new mass .1 enterprise collide enterprise spaceship.new mass .1 collide enterprise asteroid.new mass 1 collide enterprise spaceship.new mass 1 collide asteroid.new mass 10 asteroid.new mass 5 languages support multiple dispatch language definition syntactic level python often possible add multiple dispatch using library extension example module multimethods.py provides clos-style multimethods python without changing underlying syntax keywords language multimethods import dispatch game_objects import asteroid spaceship game_behaviors import asfunc ssfunc safunc collide dispatch collide.add_rule asteroid spaceship asfunc collide.add_rule spaceship spaceship ssfunc collide.add_rule spaceship asteroid safunc def aafunc b collide.add_rule asteroid asteroid aafunc collide thing1 thing2 functionally similar clos example syntax conventional python using python 2.4 decorators guido van rossum produced sample implementation multimethods simplified syntax multimethod asteroid asteroid def collide b multimethod asteroid spaceship def collide b goes define multimethod decorator peak-rules package provides multiple dispatch syntax similar example later replaced pyprotocols reg library also supports multiple predicate dispatch c dynamic dispatch must implemented manually form often enum used identify subtype object dynamic dispatch done looking value function pointer branch table simple example c typedef void *collisioncase void void collision_aa void /* handle asteroid-asteroid collision */ void collision_as void /* handle asteroid-spaceship collision */ void collision_sa void /* handle spaceship-asteroid collision */ void collision_ss void /* handle spaceship-spaceship collision*/ typedef enum thing collisioncase collisioncases num_thing_types num_thing_types void collide thing thing b int main void c object system library c support dynamic dispatch similar clos fully extensible need manual handling methods dynamic message methods dispatched dispatcher cos faster objective-c example cos // classes defclass asteroid // data members endclass defclass spaceship // data members endclass // generics defgeneric _bool collide_with _1 _2 // multimethods defmethod _bool collide_with asteroid asteroid endmethod defmethod _bool collide_with asteroid spaceship endmethod defmethod _bool collide_with spaceship asteroid endmethod defmethod _bool collide_with spaceship spaceship endmethod // example use int main void c++ natively supports single dispatch though adding multi-dispatch considered methods working around limit analogous use either visitor pattern dynamic cast library pointer-to-method lookup table class thing class asteroid public thing class spaceship public thing thing :collisionhandlermap thing :collisioncases const std :uint32_t asteroid :cid typeid asteroid .hash_code const std :uint32_t spaceship :cid typeid spaceship .hash_code void asteroid :initcases void spaceship :initcases int main yomm2 library provides fast orthogonal implementation open multimethods syntax declaring open methods inspired proposal native c++ implementation library requires user registers classes used virtual arguments sub-classes require modifications existing code methods implemented ordinary inline c++ functions overloaded passed pointer limit number virtual arguments arbitrarily mixed non-virtual arguments library uses combination techniques compressed dispatch tables perfect integer hash implement method calls constant time mitigating memory usage dispatching call open method single virtual argument takes 15-30 time calling ordinary virtual member function modern optimizing compiler used asteroids example implemented follows using yorel :yomm2 :virtual_ class thing class asteroid public thing class spaceship public thing register_class thing register_class spaceship thing register_class asteroid thing declare_method void collidewith virtual_ thing virtual_ thing define_method void collidewith thing left thing right define_method void collidewith asteroid left asteroid right define_method void collidewith asteroid left spaceship right define_method void collidewith spaceship left asteroid right define_method void collidewith spaceship left spaceship right int main stroustrup mentions design evolution c++ liked concept multimethods considered implementing c++ claims unable find efficient sample implementation comparable virtual functions resolve possible type ambiguity problems states although feature would still nice approximately implemented using double dispatch type based lookup table outlined c/c++ example low priority feature future language revisions many object-oriented programming languages natively supports single dispatch however possible emulate open multimethods library function d. openmethods library example // declaration matrix plus virtual matrix virtual matrix // override two densematrix objects method matrix _plus densematrix densematrix b // override two diagonalmatrix objects method matrix _plus diagonalmatrix diagonalmatrix b language single dispatch java multiple dispatch emulated multiple levels single dispatch interface collideable class asteroid implements collideable class spaceship implements collideable run time codice_6 checks one levels also used also multi-parameter type classes haskell scala used emulate multiple dispatch
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Programming language topics
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open grid services infrastructure open grid services infrastructure ogsi published global grid forum ggf proposed recommendation june 2003 intended provide infrastructure layer open grid services architecture ogsa ogsi takes statelessness issues along others account essentially extending web services accommodate grid computing resources transient stateful web services groups started integrate approaches capturing state web services resource framework wsrf release gt4 open source tool kit migrating back pure web services implementation rather ogsi via integration wsrf ogsi former set extensions web services provide stateful interactions -- would say point obsolete jay unger said model used globus toolkit 3.0 replaced wsrf ws-security broader set web services standards ogsa focuses specific service definition areas execution components execution modeling grid data components information virtualization still important role play evolution standards open source tool kits like globus
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Distributed computing architecture
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common lisp object system common lisp object system clos facility object-oriented programming part ansi common lisp clos powerful dynamic object system differs radically oop facilities found static languages c++ java clos inspired earlier lisp object systems mit flavors commonloops although general either originally proposed add-on clos adopted part ansi standard common lisp adapted lisp dialects eulisp emacs lisp basic building blocks clos classes methods instances classes generic functions clos provides macros define codice_1 codice_2 codice_3 instances created function codice_4 classes multiple superclasses list slots member variables c++/java parlance special metaclass slots allocated class instances class share slot instance slot name value slot accessed name using function codice_5 additionally special generic functions defined write read values slots slot clos class must unique name clos multiple dispatch system means methods specialized upon required arguments oo languages single-dispatch meaning methods specialized first argument another unusual feature methods belong classes classes provide namespace generic functions methods methods defined separately classes special access e.g self protected class slots methods clos grouped generic functions generic function object callable like function associates collection methods shared name argument structure specialized different arguments since common lisp provides non-clos classes structures built-in data types numbers strings characters symbols ... clos dispatch works also non-clos classes clos also supports dispatch individual objects eql specializers clos default support dispatch common lisp data types example dispatch work fully specialized array types types introduced codice_6 however common lisp implementations provide metaobject protocol allows generic functions provide application specific specialization dispatch rules dispatch clos also different oo languages dispatch mechanism works runtime adding removing methods thus may lead changed effective methods even generic function called arguments runtime changing method combination also may lead different effective methods example like oo systems dynamic languages clos enforce encapsulation slot accessed using codice_5 function via optionally auto-generated accessor methods access via codice_5 know name slot cl programmers use language package facility declare functions data structures intended export apart normal primary methods also codice_9 codice_10 codice_11 auxiliary methods former two invoked prior primary method particular order based class hierarchy codice_11 method control whether primary method executed additionally programmer specify whether possible primary methods along class hierarchy called one providing closest match standard method-combination provides primary around methods explained method-combinations method types new simple complex method-combinations method types defined clos allows multiple inheritance default order methods executed multiple inheritance correct programmer may resolve diamond inheritance problems specifying order method combinations clos dynamic meaning contents also structure objects modified runtime clos supports changing class definitions on-the-fly even instances class question already exist well changing class membership given instance codice_13 operator clos also allows one add redefine remove methods runtime circle-ellipse problem readily solved clos oop design patterns either disappear qualitatively simpler clos prototype language classes must defined objects instantiated members class outside ansi common lisp standard widely implemented extension clos called metaobject protocol mop mop defines standard interface underpinnings clos implementation treating classes slot-descriptions generic-functions methods instances metaclasses allows definition new metaclasses modification clos behavior flexibility clos mop prefigures aspect-oriented programming later developed engineers gregor kiczales mop defines behavior whole object system set protocols defined terms clos thus possible create new object-systems extending changing provided clos functionality book art metaobject protocol describes use implementation clos mop various common lisp implementations slightly different support meta-object protocol closer project aims provide missing features flavors successor new flavors object system mit lisp machine large parts lisp machine operating systems many applications use flavors new flavors flavors introduced multiple inheritance mixins among features flavors mostly obsolete though implementations common lisp exist flavors using message passing paradigm new flavors introduced generic functions commonloops successor loops xerox interlisp-d commonloops implemented common lisp portable implementation called portable commonloops pcl first implementation clos pcl widely ported still provides base clos implementation several common lisp implementations pcl implemented mostly portable common lisp system dependent parts power expressivity clos well historical availability tinyclos simplified portable clos implementation written gregor kiczales use scheme clos-like mop-based object systems become de facto norm lisp dialect implementations well finding way languages oop facilities
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Programming language topics
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win–loss analytics win–loss analytics involves identifying analyzing reasons visitor website n't persuaded engage desired action conversion information allows web teams improve website navigation content identify individuals likely convert improve marketing efforts determining one person engaged desired action another long topic interest sales measurement conversion always possible sales data contrast marketing mostly concerned targeting masses results marketing traditionally difficult accurately measure internet much easier marketers collect data analysis evaluation order understand demonstrate effectiveness ineffectiveness efforts make changes improve thus yielding best result specific marketing campaign win-loss analytics web analytics tools existed since early days internet ubiquitous tools provide bird eye view website traffic information gathered allows webmasters make informed decisions making changes order improve website win–loss analytics tools track individual perspectives visitor uncovering visitor products qualified well persuaded n't convert win loss programs typically focus different elements buying process including gathering buyer feedback solution sold whether product service buyer perception effectiveness sales representative sales team buyer perceptions selling vendor overall firm reputation long-term financial viability price categories broken greater detail refined feedback example questions product service might include intuitiveness user interface effectiveness specific features functionality
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Web technology
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extended wordnet extended wordnet project university texas dallas funded national science foundation aims improve wordnet semantically parsing glosses thus making information contained definitions available automatic knowledge processing systems freely available bsd style license although updated since november 2004 recent version based wordnet 2.0 still remains useful resource database available set four xml files one verbs adverbs nouns adjectives following information extracted glosses example following information available synset excellent first-class fantabulous gloss word sense disambiguation parse tree logic form gloss first tagged using brill tagger glosses parsed using charniak parser in-house collins style parser parsed gloss assigned level quality page currently available
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Computational linguistics
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unarchiver unarchiver proprietary freeware data decompression utility supports formats archive utility formerly known bomarchivehelper built-in archive unpacker program macos also handle filenames various character encodings created using operating system versions use character encodings latest version requires mac os x lion higher unarchiver compress files corresponding command line utilities codice_1 codice_2 run microsoft windows linux macos
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Computer file systems
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gfa basic gfa basic dialect basic programming language frank ostrowski name derived company gfa systemtechnik gmbh distributed software mid-1980s 1990s enjoyed popularity advanced basic dialect mostly superseded several programming languages official support ended early 2000s gfa basic developed frank ostrowski gfa systemtechnik gmbh later gfa software german company kiel düsseldorf gfa acronym gesellschaft für automatisierung company automation gave name software first gfa basic version released 1986 mid late 1980s became popular atari st home computer range since atari st basic shipped primitive later ports commodore amiga dos windows marketed version 2.0 popular release gfa basic offered many advanced features compared alternatives gfa basic 3.0 included improvements like support user-defined structures agglomerated data types final released version 3.6 around 2002 gfa software ceased gfa basic activities shut mailinglist website 2005 due missing official support availability gfa basic user community took support installed communication infrastructure version 2.0 popular release gfa basic modern programming language time line numbers used one line equivalent one command greatly simplify maintenance long listings ide even allowed code folding reasonable range structured programming commands — procedures local variables parameter passing value reference loop constructs etc modularization rudimentary making gfa basic 2.0 best suited small medium-sized projects gfa basic interpreter compact reasonably fast shipped runtime could distributed freely one programs compiler made available execution speed could increased approximately factor 2 gfa basic allowed extreme optimisations execution speed supporting direct assembler-level calls even ability embed sections assembler code directly within basic source code gfa basic integrated neatly gem tos atari st operating system providing menus dialog boxes mouse control see wimp interface although source code usually stored tokenized version save room disk pieces code could also saved ascii form made possible set reusable libraries tokenized source files benefit ways — instance gfa basic allowed users include binary data basic code via inline statement could even integrated gfa assembler allow users develop machine code programs inside inline statements order accelerate particular areas program also meant basic interpreter later compiler n't need tokenise program loaded would significant load-time overhead larger gfa basic programs written editions gfa manual printed black ink red paper attempt thwart photocopying bootlegging effectiveness tactic questionable manual returned usual black-on-white format complaints colour blind users proliferation re-typed copies internet gfa basic microsoft windows included thorough implementation windows api calls although product number technical advantages popular products combination easy language robust architecture fast compiled reliable code n't achieve great success windows market software professionals wanted high-performance code tended stay technical languages regard basics inferior professionals n't problem basic number well-established software tool vendors microsoft borland actively promoting new visual programming systems visual basic allowed users create windows dialog boxes populated standard components text buttons frame outlines help drag-and-drop interface object-oriented editing one advantages gfa basic windows compiler sold separately could create stand-alone .exe files also included relatively easy option creating dynamic link library .dll files windows allowed user write test routines within gfa basic export functions windows .dll file access pre-compiled functions within tools programs visual basic 3.0 unable produce compiled code feature allowed gfa basic used number-crunching add-on product visual basic writing high-speed routines applications database sorting media signal processing would impractical then-current version visual basic gfa basic company recognition product recognition factors companies microsoft borland united states market simple text-based code creation system lacked exciting new visual user interfaces better-known competitors although gfa basic windows developed include support visual basic components use gfa technical visual basic without large marketing budget clear reason journalists write gfa basic windows remained comparatively obscure product éric chahi wrote game editor gfa basic create game another world including scene design game scripting game engine polygon rendering music done assembler editor used make ports game including consoles collector edition windows released 2006 dashboard sustainability coded mostly gfa basic source 500kb plus 100kb assembly mainly accessing 32-bit windows functions
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Programming language topics
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device mapper device mapper framework provided linux kernel mapping physical block devices onto higher-level virtual block devices forms foundation logical volume manager lvm software raids dm-crypt disk encryption offers additional features file system snapshots device mapper works passing data virtual block device provided device mapper another block device data also modified transition performed example case device mapper providing disk encryption simulation unreliable hardware behavior article focuses device mapper implementation linux kernel device mapper functionality also available netbsd dragonfly bsd applications like lvm2 enterprise volume management system evms need create new mapped devices talk device mapper via codice_1 shared library turn issues ioctls codice_2 device node configuration device mapper also examined configured interactivelyor shell scriptsby using utility two userspace components source code maintained alongside lvm2 source functions provided device mapper include linear striped error mappings well crypt multipath targets example two disks may concatenated one logical volume pair linear mappings one disk another example crypt target encrypts data passing specified device using linux kernel crypto api following mapping targets available following linux kernel features projects built top device mapper
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Operating systems
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shared disk architecture shared disk architecture sd distributed computing architecture disks accessible cluster nodes contrasts shared nothing architecture nodes sole access distinct disks multiple processors access disks directly via intercommunication network every processor local memory shared disk two advantages shared memory firstly processor memory memory bus bottleneck secondly system offers simple way provide degree fault tolerance
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Distributed computing architecture
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trusted third party cryptography trusted third party ttp entity facilitates interactions two parties trust third party third party reviews critical transaction communications parties based ease creating fraudulent digital content ttp models relying parties use trust secure interactions ttps common number commercial transactions cryptographic digital transactions well cryptographic protocols example certificate authority ca would issue digital identity certificate one two parties next example ca becomes trusted-third-party certificates issuance likewise transactions need third party recordation would also need third-party repository service kind another 'trusted means system need trusted act interests option either involuntarily act interest 'trusted also means way verify system operating interests hence need trust corollary system verified operate interests would need trust shown operate interests one would use suppose alice bob wish communicate securely – may choose use cryptography without ever met bob alice may need obtain key use encrypt messages case ttp third party may previously seen bob person otherwise willing vouch key typically identity certificate belongs person indicated certificate case bob discussions third person often called trent trent gives alice uses send secure messages bob alice trust key bob trusts trent discussions simply assumed valid reasons course issue alice bob able properly identify trent trent someone impersonating trent arrange trustable third parties type unsolved problem long motives greed politics revenge etc. perform supervise work done entity provide potential loopholes necessary trust may leak problem perhaps unsolvable one ancient notorious large impersonal corporations make promises accuracy attestations correctness claimed public-key-to-user correspondence e.g. certificate authority part public key infrastructure changes little many environments strength trust weak weakest link infrastructure trusted ca breached whole chain trust broken 2011 incident ca diginotar broke trust dutch governments pki textbook example weaknesses system effects bruce schneier pointed 2013 mass surveillance disclosures third party fact ever trusted pgp cryptosystem includes variant ttp form web trust pgp users digitally sign identity certificates instructed confident person public key belong together key signing party one way combining get-together certificate signing nonetheless doubt caution remain sensible users careless signing others certificates trusting humans organizational creations risky example financial matters bonding companies yet find way avoid losses real world outside cryptography law many places makes provision trusted third parties upon whose claims one may rely instance notary public acts trusted third party authenticating acknowledging signatures documents ttp role cryptography much least principle certificate authority partially fills notary function attesting identity key owner whether party mentally aware apparent free duress certificate authority attest date signature
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Computer security
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iobit malware fighter iobit malware fighter introduced 2004 anti-malware anti-virus program microsoft windows operating system windows xp later designed remove protect malware including trojans rootkits ransomware iobit malware fighter freeware version run alongside user existing anti-virus solution paid edition product comes anti-virus protection version 6 released 2018 product includes bitdefender engine commercial version along anti-malware engine new features latest release include improved user interface safe box feature protect specific folders unauthorized access mbr guard protects malicious attacks goldeneye/petya cryptocurrency mining scripts 2010 first beta iobit malware fighter 1.0 released public 2013 iobit malware fighter 2 released version iobit debuted cloud security component user upload file cloud determine whether malicious 2015 version 3 released 2016 version 4 added bitdefender anti-virus engine commercial edition 2017 version 5 released among new features anti-ransomware component version 6 released may 2018
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Computer security
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warshipping warshipping using physical package delivery service deliver attack vector target concept first described 2008 def con hacking convention robert graham david maynor part talk entitled “ bringing sexy back breaking style ” included various penetration testing methods implementation iphone box modified include larger battery powered jailbroken iphone first-generation iphone chosen attack based reported run-time 5 days coupled external battery whereas newer 3g iphones era would reportedly run 1½ days social engineering security pretext described would trick recipient believing iphone order explain shipment advancement low-power electronics thanks part maker culture greatly increased effectiveness methodology credible method attacking networks 2019 ibm x-force red coined name “ warshipping ” described attack platform included several low-cost components could combined shipped targets controlled remotely 2-3 weeks solar component also described allow devices run indefinitely aspects modern warshipping attack include following increasing use large online retailers contributes relevancy attack 2019 united states postal service reports deliver 484.8 million mailpieces per day name analogy wardriving wardialling
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Computer security
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process management computing process management integral part modern-day operating system os os must allocate resources processes enable processes share exchange information protect resources process processes enable synchronization among processes meet requirements os must maintain data structure process describes state resource ownership process enables os exert control process modern operating system one instance program loaded memory time example one user could executing program user separate copies program loaded memory programs possible one copy loaded memory several users shared access execute program-code program said re-entrant processor instant executing one instruction one program several processes sustained period time assigning process processor intervals remainder become temporarily inactive number processes executed period time instead time called concurrent execution multiprogramming multitasking os system executing many processes concurrently multiprogramming requires processor allocated process period time de-allocated appropriate moment processor de-allocated execution process must done way restarted later easily possible two possible ways os regain control processor program ’ execution order os perform de-allocation allocation stopping one process starting restarting another process called context switch context change many modern operating systems processes consist many sub-processes introduces concept thread thread may viewed sub-process separate independent sequence execution within code one process threads becoming increasingly important design distributed client–server systems software run multi-processor systems common trait observed among processes associated computer programs alternate cpu cycles i/o cycles portion time required cpu cycles process executed i.e occupying cpu time required i/o cycles process using processor instead either waiting perform input/output actually performing input/output example reading writing file disk prior advent multiprogramming computers operated single-user systems users systems quickly became aware much time computer allocated single user processor idle user entering information debugging programs example computer scientists observed overall performance machine could improved letting different process use processor whenever one process waiting input/output uni-programming system n users execute programs individual execution times ... total time service n processes consecutively n users would however process consumes cpu cycles i/o cycles time process actually uses cpu small fraction total execution time process process time process spends using cpu br total execution time process i.e time cpu cycles plus i/o cycles carried executed completion process fact usually sum processor time used n processes rarely exceeds small fraction time execute one processes therefore uni-programming systems processor lay idle considerable proportion time overcome inefficiency multiprogramming implemented modern operating systems linux unix microsoft windows enables processor switch one process x another whenever x involved i/o phase execution since processing time much less single job runtime total time service n users multiprogramming system reduced approximately operating systems need ways create processes simple system designed running single application e.g. controller microwave oven may possible processes ever needed present system comes general-purpose systems however way needed create terminate processes needed operation four principal events cause process created operating system booted typically several processes created foreground processes interacts human user perform work background processes associated particular users instead specific function example one background process may designed accept incoming e-mails sleeping day suddenly springing life incoming e-mail arrives another background process may designed accept incoming request web pages hosted machine waking request arrives service request process creation unix linux done fork clone system calls several steps involved process creation first step validation whether parent process sufficient authorization create process upon successful validation parent process copied almost entirely changes unique process id parent process user-space new process gets user space many reasons process termination operating system ’ principal responsibility controlling execution processes includes determining interleaving pattern execution allocation resources processes one part designing os describe behaviour would like process exhibit simplest model based fact process either executed processor thus process may considered one two states running running operating system creates new process process initially labeled running placed queue system running state process portion exists main memory waits queue opportunity executed period time currently running process interrupted moved running state running state making processor available different process dispatch portion os select queue running processes one waiting processes transfer processor chosen process relabeled running state running state execution either begun new process resumed process interrupted earlier time model identify design elements os although two-state process management model perfectly valid design operating system absence blocked state means processor lies idle active process changes cpu cycles i/o cycles design make efficient use processor three-state process management model designed overcome problem introducing new state called blocked state state describes process waiting i/o event take place case i/o event mean use device signal another process three states model instant process one one three states single processor computer one process running state one instant many processes ready blocked states states associated queue processes processes entering system must go initially ready state processes enter running state via ready state processes normally leave system running state three states process occupies space main memory reason transitions one state another might obvious may clear three state model sufficient describe behavior processes given events extend model allow possible events sophisticated design particular use portion hard disk emulate main memory called virtual memory requires additional states describe state processes suspended main memory placed virtual memory disk course processes future time resumed transferred back main memory medium level scheduler controls events process suspended running ready blocked state giving rise two states namely ready suspend blocked suspend running process suspended becomes ready suspend blocked process suspended becomes blocked suspend process suspended number reasons significant arises process swapped memory memory management system order free memory processes common reasons process suspended one suspends execution debugging program system monitoring processes five-state process management model consider following transitions described next sections process system represented data structure called process control block pcb process descriptor linux performs function traveller passport pcb contains basic information job including process identification process uniquely identified user ’ identification pointer connecting descriptor process status indicates current status process ready running blocked ready suspend blocked suspend process state contains information needed indicate current state job accounting contains information used mainly billing purposes performance measurement indicates kind resources process used long contemporary processors incorporate mode bit define execution capability program processor bit set kernel mode user mode kernel mode also commonly referred supervisor mode monitor mode ring 0 kernel mode processor execute every instruction hardware repertoire whereas user mode execute subset instructions instructions executed kernel mode called kernel privileged protected instructions distinguish user mode instructions example i/o instructions privileged application program executes user mode perform i/o instead must request os perform i/o behalf system may logically extend mode bit define areas memory used processor kernel mode versus user mode mode bit set kernel mode process executing processor access either kernel user partition memory however user mode set process reference user memory space frequently refer two classes memory user space system space kernel supervisor protected space general mode bit extends operating system protection rights mode bit set user mode trap instruction also called supervisor call instruction instruction sets mode bit branches fixed location system space since system code loaded system space system code invoked via trap os completed supervisor call resets mode bit user mode prior return parts os critical correct operation execute kernel mode software generic system software application programs execute user mode fundamental distinction usually irrefutable distinction operating system system software part system executing kernel supervisor state called kernel nucleus operating system kernel operates trusted software meaning designed implemented intended implement protection mechanisms could covertly changed actions untrusted software executing user space extensions os execute user mode os rely correctness parts system software correct operation os hence fundamental design decision function incorporated os whether needs implemented kernel implemented kernel execute kernel supervisor space access parts kernel also trusted software parts kernel function implemented execute user mode access kernel data structures however advantage normally require limited effort invoke function kernel-implemented functions may easy implement trap mechanism authentication time call usually relatively expensive kernel code runs fast large performance overhead actual call subtle important point two techniques program executing user mode request kernel services operating systems designed one two facilities first assume user process wishes invoke particular target system function system call approach user process uses trap instruction idea system call appear ordinary procedure call application program os provides library user functions names corresponding actual system call stub functions contains trap os function application program calls stub executes trap instruction switches cpu kernel mode branches indirectly os table entry point function invoked function completes switches processor user mode returns control user process thus simulating normal procedure return message passing approach user process constructs message describes desired service uses trusted send function pass message trusted os process send function serves purpose trap carefully checks message switches processor kernel mode delivers message process implements target functions meanwhile user process waits result service request message receive operation os process completes operation sends message back user process distinction two approaches important consequences regarding relative independence os behavior application process behavior resulting performance rule thumb operating system based system call interface made efficient requiring messages exchanged distinct processes case even though system call must implemented trap instruction even though trap relatively expensive perform efficient message passing approach generally higher costs associated process multiplexing message formation message copying system call approach interesting property necessarily os process instead process executing user mode changes kernel mode executing kernel code switches back user mode returns os call hand os designed set separate processes usually easier design gets control machine special situations kernel simply collection functions executed users processes kernel mode even procedure-based operating system usually find necessary include least system processes called daemons unix handle situation whereby machine otherwise idle scheduling handling network
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Operating systems
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xpeak xpeak standard device management based xml platform agnostic initially focused financial applications restricted serves purpose apis like cen/xfs j/xfs restricted one operating system language since works client/server model using xml way homogenise communication application device services flexibility allows different parts whole business implemented different languages application various devices implemented java c++ still others device firmware designed based experiences cen/xfs j/xfs javapos instead using standards organization uses open source model develop architecture tools used project like base complete open source software solution named xpeaker way updated quickly openly users using internet means communication rather meetings requiring physical presence xpeak follows open source model participation project totally free moderated r open source foundation participated equal parts sun microsystems intecna initial code contribution responsibility cashware one leading companies devices connectivity use standards cen/xfs j/xfs xpeaker collection software projects integrally developed cashware philosophy open source commercialized dual license xpeaker public license commercial licence xpeaker includes following elements eclipse plugin permits made high level api access xpeak services xpeaking permits access said services different programming languages java c c++ c pascal
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Operating systems
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arith-matic arith-matic extension grace hopper a-2 programming language developed around 1955 arith-matic originally known a-3 renamed marketing department remington rand univac
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Programming language topics
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brandz brandz brand equity database managed marketing firm millward brown holds data 650,000 consumers professionals across 31 countries comparing 23,000 brands database used estimate brand valuations year since 2006 used generate list top 100 global brands credibility interbrand brandz league tables cast doubt article written marketing week mark ritson lack clear definitions valuation dates companies methodology raise questions subjectivity involved brand valuations part multinational advertising groups interbrand kantar millward brown also suffer risk objectivity transparency objectivity two requirements iso 10668 standard monetary brand valuations
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Databases
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wsfn programming language wsfn stands nothing interpreted programming language controlling robots created li-chen wang designed small possible tiny language similar wang earlier effort palo alto tiny basic wsfn first published dr. dobb journal september 1977 language consists primarily single-letter commands tell robot move certain directions commands perform tests basic mathematical operations grouped named macros produce complex programs original version also included code simulated robot cursor vdm-1 display graphically cromemco dazzler display today known turtle graphics extended wsfn implementation created atari 8-bit family home computers written harry stewart published atari program exchange 1981 addition supporting turtle graphics adds number commands control graphics sound capabilities platform offered beginner language emphasis graphics wsfn consists number single-letter commands control movement turtle commands repeated prefixing number instance codice_1 moves turtle forward one step codice_2 moves 25 steps codice_3 codice_4 make turtle turn one unit right left respectively also reset point codice_5orth step sizes turn units defined robot hardware set one pixel 45 degrees turtle graphics versions missing robot versions computer versions codice_6 returns turtle home center screen codice_7 clears previous drawing thus one draw square string instructions set drawing color black clears screen fills current color sets color white homes turtle resets turtle point north draws series four lines 25 steps long rotating 90 degrees one result white square lower-left corner center screen lists commands surrounded parentheses create macros instance square drawn placing code draw one side square inside parentheses calling four times macros called within macros instance code draws series eight squares offset 45 degrees rotating around center screen macros assigned name using codice_8efine command extended wsfn used codice_9 instead code defines macro named x clear screen reset drawing another z draws square uses draw rotating square example wsfn rudimentary math capabilities consisting single accumulator codice_10 incremented decremented codice_11 codice_12 letter codice_10 placed anywhere number could appear one make series squares grow larger incrementing accumulator 5 times step side-effect syntax codice_14 would set accumulator zero performs decrement instruction number likewise codice_15 doubles value accumulator program control equally rudimentary consisting number commands handled if/then/else structures basic form codice_16est command follows one two paths accumulator greater equal zero instance command causes turtle turn 90 degrees left accumulator non-zero 45 right zero variations codice_16 branching construct include codice_18 randomly jumps first second branch 50 time codice_19ensor tests contact sensor robot triggered extended wsfn modified codice_19 return color front turtle allowing hit detection previous drawing added codice_21dge test jumps right side macro turtle hit edge drawing area original wsfn lacks equivalent codice_21 instead wraps drawing area turtle re-appears opposite side screen extended wsfn supports style playfield wrapping option uses one-letter commands recursive syntax wsfn code exceedingly cryptic example wsfn program draw sierpiński curves note definition macro includes calls within key aspect wsfn concept language highly recursive nature makes programming self-similar patterns like fractals easy accomplish lines code key concept extended wsfn keyboard always active even macros running allows keyboard input interrupt running programs using technique one make macros moving turtle certain ways assign letters keyboard perform movements pressing different keys succession aided adding codice_23ait command places give user time respond drawing takes place original dr. dobbs article extended wsfn manual
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Programming language topics
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scitech snap scitech snap system neutral access protocol operating system portable dynamically loadable native-size 32-bit/64-bit device driver architecture scitech snap defines architecture loading operating system neutral binary device driver type hardware device graphics controller audio controller scsi controller network controller scitech snap drivers source code portable different microprocessor platforms binary drivers operating system portable within particular microprocessor family snap drivers originally developed intel 386+ cpu 32-bit operating system environment supported cpu introduction snap 3.0 native binary snap drivers available 32-bit powerpc cpus 64-bit x86-64 cpus 2002-08-27 scitech software inc. announced intention release scitech snap driver development kit 2006-11-16 scitech software inc. announced ceased development snap device driver technology favor new line web business logic technologies scitech also announced would begin looking buyer scitech snap december 2008 alt richmond inc. closed acquisition scitech software ’ snap technology plans scitech software 2008 create opensnap open source version driver technology therefore longer option unless alt richmond decides pick may 2015 arca noae llc announced reached agreement alt richmond inc. license source code snap graphics os/2 scitech display doctor 6.5 included replacement video driver windows 95 higher works hardware supported sdd sdd 7 driver renamed scitech nucleus graphics driver nucleus graphics driver later incorporated scitech snap graphics snap 3 nucleus renamed snap scitech snap graphics version 2 also included vbetest/lite vesa bios extensions vbe compliance test version 8.00 later removed scitech snap graphics 3 scitech snap 3 dos opengl tests scitech display doctor 7 beta found gactrl driver control center windows version scitech snap graphics maintained user interface found sdd 7 beta first product scitech snap line provides accelerated graphics scitech snap graphics ported dos os/2 microsoft windows ce nt 2000 xp qnx smx sunos/solaris port minix linux time rtos-32 unununium os operating systems supported hardware included video processors 3dfx 3dlabs alliance semiconductor amd geode gx2 ark logic ati chips technologies cirrus logic cyrix ibm integraphics intel matrox neomagic number nine nvidia oak philips rendition s3 sigma designs silicon motion sis tseng labs trident via weitek well video card supporting vbe 1.2 higher although scitech snap graphics offer standalone vbe driver snap driver accelerates applications using vbe calls via scitech snap graphics driver snap graphics windows also accelerate vbe 3 calls dos programs run windows dos box scitech also offer scitech snap graphics pe personal edition scitech site allows registered users download snap driver hardware operating system specified users user account download two drivers per week driver generated service run six months scitech snap graphics pe tools gactrl gamode gaoption gaperf dos tools included gldirect tests included windows driver similar scitech snap graphics provides os-independent audio drivers ported windows nt 4.0 supported hardware include ac'97 intel hda hda support modem function designed provide easy access attached display order program directly via i²c simply read monitor edid record
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Operating systems
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monetdb monetdb open-source column-oriented database management system developed centrum wiskunde informatica cwi netherlands designed provide high performance complex queries large databases combining tables hundreds columns millions rows monetdb applied high-performance applications online analytical processing data mining geographic information system gis resource description framework rdf text retrieval sequence alignment processing data mining projects 1990s required improved analytical database support resulted cwi spin-off called data distilleries used early monetdb implementations analytical suite data distilleries eventually became subsidiary spss 2003 turn acquired ibm 2009 monetdb current form first created 2002 doctoral student peter boncz professor martin l. kersten part 1990s magnum research project university amsterdam initially called simply monet french impressionist painter claude monet first version open-source software license modified version mozilla public license released september 30 2004 monetdb version 4 released open-source domain many extensions code base added monetdb/cwi team included new sql frontend supporting standard monetdb introduced innovations layers dbms storage model based vertical fragmentation modern cpu-tuned query execution architecture often gave monetdb speed advantage algorithm typical interpreter-based rdbms one first database systems tune query optimization cpu caches monetdb includes automatic self-tuning indexes run-time query optimization modular software architecture 2008 follow-on project called x100 monetdb/x100 started evolved vectorwise technology vectorwise acquired actian corporation integrated ingres database sold commercial product 2011 major effort renovate monetdb codebase started part code monetdb 4 kernel xquery components frozen monetdb 5 parts sql layer pushed kernel resulting changes created difference internal apis transitioned monetdb instruction language mil monetdb assembly language mal older no-longer maintained top-level query interfaces also removed first xquery relied monetdb 4 never ported version 5 experimental jaql interface support removed october 2014 release july 2015 release monetdb gained support read-only data sharding persistent indices release deprecated streaming data module datacell also removed main codebase effort streamline code addition license changed mozilla public license version 2.0 monetdb architecture represented three layers set optimizers front-end top layer providing query interface sql sciql sparql interfaces development queries parsed domain-specific representations like relational algebra sql optimized generated logical execution plans translated monetdb assembly language mal instructions passed next layer middle back-end layer provides number cost-based optimizers mal bottom layer database kernel provides access data stored binary association tables bats bat table consisting object-identifier value columns representing single column database monetdb internal data representation also relies memory addressing ranges contemporary cpus using demand paging memory mapped files thus departing traditional dbms designs involving complex management large data stores limited memory query recycling architecture reusing byproducts operator-at-a-time paradigm column store dbms recycling makes use generic idea storing reusing results expensive computations unlike low-level instruction caches query recycling uses optimizer pre-select instructions cache technique designed improve query response times throughput working self-organizing fashion authors cwi database architectures group composed milena ivanova martin kersten niels nes romulo goncalves best paper runner acm sigmod 2009 conference work query recycling monetdb one first databases introduce database cracking database cracking incremental partial indexing and/or sorting data directly exploits columnar nature monetdb cracking technique shifts cost index maintenance updates query processing query pipeline optimizers used massage query plans crack propagate information technique allows improved access times self-organized behavior database cracking received acm sigmod 2011 j.gray best dissertation award number extensions exist monetdb extend functionality database engine due three-layer architecture top-level query interfaces benefit optimizations done backend kernel layers monetdb/sql top-level extension provides complete support transactions compliance standard monetdb/gis extension monetdb/sql support simple features access standard open geospatial consortium ogc sciql sql-based query language science applications arrays first class citizens sciql allows monetdb effectively function array database sciql used european union planetdata teleios project together data vault technology providing transparent access large scientific data repositories data vaults map data distributed repositories sciql arrays allowing improved handling spatio-temporal data monetdb sciql extended human brain project data vault database-attached external file repository monetdb similar sql/med standard data vault technology allows transparent integration distributed/remote file repositories designed scientific data data exploration mining specifically remote sensing data support geotiff earth observation fits astronomy miniseed seismology netcdf formats data stored file repository original format loaded database lazy fashion needed system also process data upon ingestion data format requires result even large file repositories efficiently analyzed required data processed database data accessed either monetdb sql sciql interfaces data vault technology used european union teleios project aimed building virtual observatory earth observation data data vaults fits files also used processing astronomical survey data int photometric h-alpha survey iphas monetdb sam/bam module efficient processing sequence alignment data aimed bioinformatics research module sam/bam data loader set sql udfs working dna data module uses popular samtools library monetdb/rdf sparql-based extension working linked data adds support rdf allowing monetdb function triplestore development linked open data 2 project monetdb/r module allows udfs written r executed sql layer system done using native r support running embedded another application inside rdbms case previously monetdb.r connector allowed using monetdb data sources process r session newer r integration feature monetdb require data transferred rdbms r session reducing overhead improving performance feature intended give users access functions r statistical software in-line analysis data stored rdbms complements existing support c udfs intended used in-database processing similarly embedded r udfs monetdb database support udfs written python/numpy implementation uses numpy arrays python wrappers c arrays result limited overhead providing functional python integration speed matching native sql functions embedded python functions also support mapped operations allowing user execute python functions parallel within sql queries practical side feature gives users access python/numpy/scipy libraries provide large selection statistical/analytical functions following release remote driver r monetdb.r r udfs monetdb monetdb/r authors created embedded version monetdb r called monetdblite distributed r package removing need manage database server required previous r integrations dbms runs within r process eliminating socket communication serialisation overhead greatly improving efficiency idea behind deliver sqlite-like package r performance in-memory optimized columnar store number former extensions deprecated removed stable code base time notable examples include xquery extension removed monetdb version 5 jaql extension streaming data extension called data cell
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Databases
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opal storage specification opal storage specification set specifications features data storage devices disk drives enhance security example defines way encrypting stored data unauthorized person gains possession device see data specification self-encrypting drives sed specification published trusted computing group storage workgroup opal ssc security subsystem class implementation profile storage devices built opal ssc encompasses functions radboud university researchers indicated november 2018 hardware encryption including opal implementations security vulnerabilities
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Computer security
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richard bird computer scientist richard simpson bird born 1943 london supernumerary fellow computation lincoln college oxford england former director oxford university computing laboratory oxford university department computer science bird research interests lie algorithm design functional programming known regular contributor journal functional programming author introduction functional programming using haskell books name associated bird-meertens formalism calculus deriving programs specifications functional programming style previously bird university reading
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Programming language topics
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autofetch autofetch mechanism automatically tuning object-relational mapping queries ali ibrahim william cook university texas developed idea autofetch including implementation hibernate followed later implementation ebean autofetch uses program state typically call stack classify queries means autofetch tune query depending called example data access api codice_1 tuned differently depending callers method autofetch automatically gathers profiling information developers need manually try gather information apply performance optimizations code autofetch monitor object graph usage usage changes tuning query change suit reduces code maintenance issues developers maintains optimal performance usage changes time autofetch collects object graph usage queries executed collects 'profile information later used automatically tune query subsequent executions orm query tuned determining automatically adding correct prefetch directives query improves performance application reducing lazy loading orms support partial objects autofetch also tune query including properties application uses rather properties autofetch profiling also used select optimal query strategies array fetching object graph use known uneven typically weighted first object graphs list could lead much efficient higher performing object graph traversal currently possible current techniques employed orm tools
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Databases
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secure operating system secure operating system may refer
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Operating systems
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voxforge voxforge free speech corpus acoustic model repository open source speech recognition engines voxforge set collect transcribed speech create free gpl speech corpus use open source speech recognition engines speech audio files 'compiled acoustic models use open source speech recognition engines julius isip sphinx htk note htk distribution restrictions voxforge used librivox source audio data since 2007
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Computational linguistics
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musix gnu+linux musix gnu+linux live cd dvd linux distribution ia-32 processor family based debian contains collection software audio production graphic design video editing general purpose applications initiator co-director project marcos germán guglielmetti musix gnu+linux one gnu/linux distributions recognized free software foundation primarily available sites distributing free software excluding non-free information practical use musix developed team argentina spain mexico brazil main language used development discussion documentation spanish however musix community users speak spanish portuguese english musix 0.x 1.0 rx versions released 2005 2008 musix 1.0 r6 last stable release dvd musix 1.0 r2r5 last stable release cd live-cd system 1350 software packages runs directly cd/dvd without need install anything pc installed pc relatively easily desired minutes like knoppix kanotix live-dvd 1.0 r3 test5 2279 software packages programs include rosegarden ardour musicians inkscape vectorial design gimp manipulation images cinelerra video editing blender 3d animation desktop light 18 mb ram x.org based icewm/rox-filer unique feature multiple pinboards ordered general purpose apps help office root/admin midi internet graphics audio pinboards arrays desktop backgrounds icons small version kde desktop installed default live-cd version live-dvd full kde version supporting several languages musix 2.0 developed using live-helper scripts debian-live project first alpha version musix 2.0 released 2009-03-25 including two realtime-patched linux-libre kernels 2009-05-17 first beta version musix 2.0 released final musix gnu+linux 2.0 version cd dvd usb launched november 2009 daniel vidal suso comesaña carlos sanchiavedraz joseangon musix developers version presented palau firal de congressos de tarragona españa suso comesaña quite similar linux-version developed brazilian music teacher gilberto andré borges named adriane musixbr version fork derived knoppix 6.1 adriane
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Operating systems
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national security operations center national security operations center nsoc directorate k part united states national security agency responsible current operations time-sensitive signals intelligence sigint reporting united states sigint system usss one two centers watching directorate v ntoc assesses threats nsoc operations center 24 hours day 7 days week basis providing total situational awareness across nsa/css enterprise foreign signals intelligence information assurance maintains cognizance national security information needs monitors unfolding world events 1969 u.s. navy ec-121 patrol plane shot sea japan ensuing hours nsa leaders raced office office gather information necessary assemble coordinated response agency national leadership incident demonstrated need dedicated watch center respond breaking world events center established 1968 national sigint watch center nswc renamed national sigint operations center nsoc 1973 nerve center nsa got current name 1996 september 11 2001 attacks nsoc mission broadened watch center operations center today
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Computer security
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general data protection regulation general data protection regulation eu 2016/679 gdpr regulation eu law data protection privacy individual citizens european union eu european economic area eea also addresses transfer personal data outside eu eea areas gdpr aims primarily give control individuals personal data simplify regulatory environment international business unifying regulation within eu superseding data protection directive 95/46/ec regulation contains provisions requirements pertaining processing personal data individuals formally called data subjects gdpr inside eea applies enterprise established eea or—regardless location data subjects citizenship—that processing personal information data subjects inside eea controllers personal data must put place appropriate technical organisational measures implement data protection principles business processes handle personal data must designed built consideration principles provide safeguards protect data example using pseudonymization full anonymization appropriate use highest-possible privacy settings default datasets publicly available without explicit informed consent used identify subject without additional information must stored separately personal data may processed unless processing done lawful basis specified regulation unless data controller processor received unambiguous individualized affirmation consent data subject data subject right revoke consent time processor personal data must clearly disclose data collection declare lawful basis purpose data processing state long data retained shared third parties outside eea data subjects right request portable copy data collected processor common format right data erased certain circumstances public authorities businesses whose core activities centre around regular systematic processing personal data required employ data protection officer dpo responsible managing compliance gdpr businesses must report data breaches within 72 hours adverse effect user privacy cases violators gdpr may fined €20 million 4 annual worldwide turnover preceding financial year case enterprise whichever greater gdpr adopted 14 april 2016 became enforceable beginning 25 may 2018 gdpr regulation directive directly binding applicable provide flexibility certain aspects regulation adjusted individual member states gdpr 2016 eleven chapters concerning general provisions principles rights data subject duties data controllers processors transfers personal data third countries supervisory authorities cooperation among member states remedies liability penalties breach rights miscellaneous final provisions regulation applies data controller organisation collects data eu residents processor organisation processes data behalf data controller like cloud service providers data subject person based eu certain circumstances regulation also applies organisations based outside eu collect process personal data individuals located inside eu regulation apply processing data person purely personal household activity thus connection professional commercial activity recital 18 according european commission personal data information relates identified identifiable individual directly identify individual information need consider whether individual still identifiable take account information processing together means reasonably likely used either person identify individual.the precise definitions terms personal data processing data subject controller processor stated article 4 regulation regulation purport apply processing personal data national security activities law enforcement eu however industry groups concerned facing potential conflict laws questioned whether article 48 gdpr could invoked seek prevent data controller subject third country laws complying legal order country law enforcement judicial national security authorities disclose authorities personal data eu person regardless whether data resides eu article 48 states judgement court tribunal decision administrative authority third country requiring controller processor transfer disclose personal data may recognised enforceable manner unless based international agreement like mutual legal assistance treaty force requesting third non-eu country eu member state data protection reform package also includes separate data protection directive police criminal justice sector provides rules personal data exchanges national european international levels single set rules apply eu member states member state establish independent supervisory authority sa hear investigate complaints sanction administrative offences etc sas member state co-operate sas providing mutual assistance organising joint operations business multiple establishments eu single sa lead authority based location main establishment main processing activities take place lead authority act one-stop shop supervise processing activities business throughout eu articles 46–55 gdpr european data protection board edpb co-ordinate sas edpb replace article 29 data protection working party exceptions data processed employment context national security still might subject individual country regulations articles 2 2 88 gdpr unless data subject provided informed consent data processing one purposes personal data may processed unless least one legal basis article 6 states lawful purposes informed consent used lawful basis processing consent must explicit data collected purpose data used article 7 defined article 4 consent must specific freely-given plainly-worded unambiguous affirmation given data subject online form consent options structured opt-out selected default violation gdpr consent unambiguously affirmed user addition multiple types processing may bundled together single affirmation prompt specific use data individual permissions freely-given recital 32 data subjects must allowed withdraw consent time process must harder opt article 7 3 data controller may refuse service users decline consent processing strictly necessary order use service article 7 4 consent children defined regulation less 16 years old although option member states individually make low 13 years old article 8 1 must given child parent custodian verifiable article 8 consent processing already provided data protection directive data controller re-obtain consent processing documented obtained compliance gdpr requirements recital 171 article 12 requires data controller provides information 'data subject concise transparent intelligible easily accessible form using clear plain language particular information addressed specifically child right access article 15 data subject right gives citizens right access personal data information personal data processed data controller must provide upon request overview categories data processed article 15 1 b well copy actual data article 15 3 furthermore data controller inform data subject details processing purposes processing article 15 1 data shared article 15 1 c acquired data article 15 1 g data subject must able transfer personal data one electronic processing system another without prevented data controller data sufficiently anonymised excluded data de-identified remains possible link individual question providing relevant identifier practice however providing identifiers challenging case apple siri voice transcript data stored personal identifier manufacturer restricts access online behavioural targeting relies heavily device fingerprints challenging capture send verify data 'provided data subject data 'observed behaviour included addition data must provided controller structured commonly used standard electronic format right data portability provided article 20 gdpr right forgotten replaced limited right erasure version gdpr adopted european parliament march 2014 article 17 provides data subject right request erasure personal data related one number grounds within 30 days including noncompliance article 6 1 lawfulness includes case f legitimate interests controller overridden interests fundamental rights freedoms data subject require protection personal data see also google spain sl google inc. v agencia española de protección de datos mario costeja gonzález able demonstrate compliance gdpr data controller must implement measures meet principles data protection design default article 25 requires data protection measures designed development business processes products services measures include pseudonymising personal data controller soon possible recital 78 responsibility liability data controller implement effective measures able demonstrate compliance processing activities even processing carried data processor behalf controller recital 74 data collected data subjects must clearly informed extent data collection legal basis processing personal data long data retained data transferred third-party and/or outside eu automated decision-making made solely algorithmic basis data subjects must informed privacy rights gdpr including right revoke consent data processing time right view personal data access overview processed right obtain portable copy stored data right erasure data certain circumstances right contest automated decision-making made solely algorithmic basis right file complaints data protection authority data subject must also provided contact details data controller designated data protection officer applicable data protection impact assessments article 35 conducted specific risks occur rights freedoms data subjects risk assessment mitigation required prior approval data protection authorities required high risks article 25 requires data protection designed development business processes products services privacy settings must therefore set high level default technical procedural measures taken controller make sure processing throughout whole processing lifecycle complies regulation controllers also implement mechanisms ensure personal data processed unless necessary specific purpose report european union agency network information security elaborates needs done achieve privacy data protection default specifies encryption decryption operations must carried locally remote service keys data must remain power data owner privacy achieved report specifies outsourced data storage remote clouds practical relatively safe data owner cloud service holds decryption keys gdpr refers pseudonymisation process required data stored alternative option complete data anonymisation transform personal data way resulting data attributed specific data subject without use additional information example encryption renders original data unintelligible process reversed without access correct decryption key gdpr requires additional information decryption key kept separately pseudonymised data another example pseudonymisation tokenisation non-mathematical approach protecting data rest replaces sensitive data non-sensitive substitutes referred tokens tokens extrinsic exploitable meaning value allow specific data fully partially visible processing analytics sensitive information kept hidden tokenisation alter type length data means processed legacy systems databases may sensitive data length type also requires much fewer computational resources process less storage space databases traditionally-encrypted data pseudonymisation privacy-enhancing technology recommended reduce risks concerned data subjects also help controllers processors meet data protection obligations recital 28 records processing activities must maintained include purposes processing categories involved envisaged time limits records must made available supervisory authority request article 30 article 33 states data controller legal obligation notify supervisory authority without undue delay unless breach unlikely result risk rights freedoms individuals maximum 72 hours becoming aware data breach make report individuals notified high risk adverse impact determined article 34 addition data processor notify controller without undue delay becoming aware personal data breach article 33 however notice data subjects required data controller implemented appropriate technical organisational protection measures render personal data unintelligible person authorised access encryption article 34 article 37 requires appointment data protection officer processing carried public authority except courts independent judicial authorities acting judicial capacity processing operations involve regular systematic monitoring data subjects large scale processing large scale special categories data personal data relating criminal convictions offences articles 9 article 10 data protection officer dpo —a person expert knowledge data protection law practices—must designated assist controller processor monitoring internal compliance regulation designated dpo current member staff controller processor role outsourced external person agency service contract case processing body must make sure conflict interest roles interests dpo may hold contact details dpo must published processing organisation example privacy notice registered supervisory authority dpo similar compliance officer also expected proficient managing processes data security including dealing cyberattacks critical business continuity issues around holding processing personal sensitive data skill set required stretches beyond understanding legal compliance data protection laws regulations dpo must maintain living data inventory data collected stored behalf organization details function role data protection officer given 13 december 2016 revised 5 april 2017 guideline document organisations based outside eu must also appoint eu-based person representative point contact gdpr obligations article 27 distinct role dpo although overlap responsibilities suggest role also held designated dpo eu representative eu-based designee “ ambassador ” non-eu establishment data controller data processor subject general data protection regulation gdpr eu natural individual moral corporation person play role eu representative eu representative controller ’ processor ’ contact person vis-à-vis european privacy supervisors data subjects matters relating processing ensure compliance gdpr purpose representation enable european data protection supervisory authorities ensure compliance gdpr able control supervise activities non-eu establishments subject gdpr respective representatives eu non-eu establishments subject gdpr obliged designate eu representative worth reiterating fact non-eu establishment shall subject gdpr regularly undertakes one following activities offering goods services irrespective whether payment data subject required data subjects eu and/or b monitoring behaviour data subjects eu far behaviour takes place within eu provision concerns company offers goods services online eu customers uses cookies similar technologies track eu data subjects establishments must comply gdpr thus obliged designate eu representative however non-eu establishment exempted designating eu representative processing occasional include large scale processing special categories data referred article 9 1 gdpr processing personal data relating criminal convictions offences referred article 10 gdpr processing unlikely result risk rights freedoms natural persons taking account nature context scope purposes processing non-eu public authorities bodies equally exempted foreign company subject gdpr refuses designate eu representative required former infringing gdpr runs risk imposed administrative fine ten million euros 10 000 000 eur 2 percent company ’ total worldwide annual turnover preceding financial year whichever higher ignorance gdpr would excuse intentional negligent willful blindness character infringement failure designate eu representative may rather constitute aggravating factors reasons foreign companies haste designate respective eu representatives eu-based data protection specialized companies rendered things easier european data protection specialized companies offer cheap efficient representation services especially data privacy day-to-day activity like heads state designate ambassadors letters credence non-eu establishment must issue duly signed document letter accreditation designating given individual company eu representative said designation given writing gdpr art 27 1 eu-based data protection companies already draft letters accreditation would simply forward interested companies sign send post besides definitions criminal offence according national law following article 83 gdpr following sanctions imposed within gdpr distinct difference business consumer b2c business business b2b marketing gdpr six equally valid grounds process personal data two relevant direct b2b marketing consent legitimate interest recital 47 gdpr states processing personal data direct marketing purposes may regarded carried legitimate interest using legitimate interest basis b2b marketing involves ensuring key conditions met additionally article 6.1 f gdpr states processing lawful necessary purposes legitimate interests pursued controller third-party except interests overridden interests fundamental rights freedoms individual require protection personal information particular individual child therefore companies continue use marketing data purposes b2b engagement long appropriate steps taken ensure data aligned specific objective campaign one phrase used correct marketing correct person part companies need keep marketing databases crm date order carry valid legitimate balance checks eu commission stated unified data privacy laws create extraordinary opportunities motivating innovation businesses within europe also organization willing business european states already running business european states commission aims companies maintain communications build regulation supporting relationships ensure best data practices legitimate balance checks following cases covered regulation conversely entity precisely enterprise engaged economic activity covered gdpr economic activity defined broadly european union competition law proposal new regulation gave rise much discussion controversy. ref name= taylor wessing 9/2016 dpo burden /ref thousands amendments proposed area gdpr consent number implications businesses record calls matter practice typical disclaimer considered sufficient gain assumed consent record calls additionally recording commenced caller withdraw consent agent receiving call must able stop previously started recording ensure recording get stored professionals expect compliance gdpr require additional investment overall 80 percent surveyed expected gdpr-related spending least usd 100,000. ref name= babel 7/11/2017 high cost gdpr /ref concerns echoed report commissioned law firm baker mckenzie found around 70 percent respondents believe organizations need invest additional budget/effort comply consent data mapping cross-border data transfer requirements gdpr total cost eu companies estimated around €200 billion us companies estimate 41.7 billion argued smaller businesses startup companies might financial resources adequately comply gdpr unlike larger international technology firms facebook google regulation ostensibly meant target first foremost lack knowledge understanding regulations also concern lead-up adoption counter-argument companies made aware changes two years prior coming effect therefore enough time prepare regulations including whether enterprise must data protection officer criticized potential administrative burden unclear compliance requirements although data minimisation requirement pseudonymisation one possible means regulation provide guidance constitutes effective data de-identification scheme grey area would considered inadequate pseudonymisation subject section 5 enforcement actions also concern regarding implementation gdpr blockchain systems transparent fixed record blockchain transactions contradicts nature gdpr many media outlets commented introduction right explanation algorithmic decisions legal scholars since argued existence right highly unclear without judicial tests limited best gdpr garnered support businesses regard opportunity improve data management mark zuckerberg also called positive step internet called gdpr-style laws adopted us consumer rights groups european consumer organisation among vocal proponents legislation supporters attributed passage whistleblower edward snowden free software advocate richard stallman praised aspects gdpr called additional safeguards prevent technology companies manufacturing consent academic experts participated formulation gdpr wrote law consequential regulatory development information policy generation gdpr brings personal data complex protective regulatory regime said ideas contained within gdpr entirely european new gdpr ’ protections found – albeit weaker less prescriptive forms – u.s. privacy laws federal trade commission settlements companies despite least two years prepare many companies websites changed privacy policies features worldwide directly prior gdpr implementation customarily provided email notifications discussing changes criticised resulting fatiguing number communications experts noted reminder emails incorrectly asserted new consent data processing obtained gdpr took effect previously-obtained consent processing valid long met regulation requirements phishing scams also emerged using falsified versions gdpr-related emails also argued gdpr notice emails may actually sent violation anti-spam laws march 2019 provider compliance software found many websites operated eu member state governments contained embedded tracking ad technology providers deluge gdpr-related notices also inspired memes including surrounding privacy policy notices delivered atypical means ouija board star wars opening crawl suggesting santa claus naughty nice list violation recording excerpts regulation former bbc radio 4 shipping forecast announcer blog gdpr hall shame also created showcase unusual delivery gdpr notices attempts compliance contained egregious violations regulation requirements author remarked regulation lot nitty gritty in-the-weeds details lot information comply also acknowledged businesses two years comply making responses unjustified research indicates approximately 25 software vulnerabilities gdpr implications since article 33 emphasizes breaches bugs security experts advise companies invest processes capabilities identify vulnerabilities exploited including coordinated vulnerability disclosure processes effective date international websites began block eu users entirely including instapaper unroll.me tribune publishing-owned newspapers chicago tribune los angeles times redirect stripped-down versions services case national public radio usa today limited functionality and/or advertising order remove liabilities companies klout several online video games ceased operations entirely coincide implementation citing gdpr burden continued operations especially due business model former sales volume online behavioural advertising placements europe fell 25–40 25 may 2018 facebook subsidiaries whatsapp instagram well google llc targeting android immediately sued max schrems non-profit noyb hours midnight 25 may 2018 use forced consent schrems asserts companies violated article 7 4 presenting opt-ins data processing consent individualized basis requiring users consent data processing activities including strictly necessary forbidden using services following journalistic investigation liviu dragnea romanian data protection authority anspdcp used gdpr request demand information rise project sources april 3 2019 google fined record £44m failing comply gdpr cnil france data protection office found google guilty breaking eu privacy rules failing acquire adequate consent users regarding data used personalised advertising regulator also found google n't provide clear easily accessible information consumers regarding data collection retention mass adoption new privacy standards international companies cited example brussels effect phenomenon wherein european laws regulations used global baseline due gravitas u.s. state california passed california consumer privacy act 28 june 2018 taking effect 1 january 2020 grants rights transparency control collection personal information companies similar means gdpr critics argued laws need implemented federal level effective collection state-level laws would varying standards would complicate compliance 9 april 2019 u.s. senators deb fischer mark warner introduced deceptive experiences online users reduction detour act would make unlawful u.s. technology companies 100 million monthly active users use deceptive ambiguous user interface patterns seeking consent collect personal information eu digital single market strategy relates digital economy activities related businesses people eu part strategy gdpr nis directive apply 25 may 2018 proposed eprivacy regulation also planned applicable 25 may 2018 delayed several months eidas regulation also part strategy united kingdom scheduled leave european union 2019 uk granted royal assent data protection act 2018 23 may 2018 contains equivalent regulations protections uk leaves eu become third country purposes transfer personal data outside eu may require adequacy decision european commission suitability uk data protection framework appropriate safeguards may allow transfers take place chapter v currently august 2018 uk government view 'legally-binding data protection agreement eu uk would appropriate 'adequacy finding agreement would include uk information commissioner taking part 'one stop shop mechanism seat european data protection board april 2019 uk information commissioner office ico issued proposed code practice social networking services used minors enforceable gdpr also includes restrictions like streak mechanisms order discourage social media addiction use data processing interests american bar association published 2018 gdpr applies extraterritorially eu commission basis article 45 gdpr determined following countries offer adequate level data protection address new regulation retention disposition applications developed updated since data protection addresses much traditional records management several software solutions emerged include vast array issues facing information professionals
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Computer security
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software remastering software remastering software development recreates system software applications incorporating customizations intent copied run elsewhere off-label usage remastered codebase continue parallel ongoing upstream software development fork remastered version term comes remastering media production similarly distinguished mere copying remastering popularized klaus knopper creator knoppix free software foundation promotes universal freedom recreate distribute computer software example funding projects like gnu project remastered linux bsd opensolaris operating system distributions common copy protected also allowance operating systems grow application taking snapshot installing onto bootable media thumb drive virtual machine hypervisor since 2001 1000 computer operating systems arisen download internet global community linux providers pushes practice remastering developer switching project overtaking merging sharing internet distributions start remastered version another distribution evidenced announcements made distrowatch notably remastering sls linux forked slackware remastering red hat linux helped fork yellow dog linux mandriva turbolinux remastering debian distribution ubuntu started remastered linux mint team might involve critical system software extent customizations made remastering trivial change default setting distribution subsequent provision acquaintance installation media remastered version becomes public becomes distribution microsoft windows also modified remastered various utilities exist combine windows updates device drivers original windows cd/dvd installation media process known slipstreaming remastering distro remastering software applied inside live operating system clone installation package remastering necessarily require remastering software facilitates process example application remastered acquiring modifying recompiling original source code many video games modded upgrading additional content levels features notably counter-strike remastered half-life went marketed commercial product software remastering creates application rebuilding code base software objects existing master repository mastering process assembles distribution release version remaster process subtraction modification addition master repository similarly modified makefile orchestrates computerized version application amount unneeded code cut wanted minimum removes unwanted features original publisher maintainer needs new features added evolves software remastered version may consider feature original bug provides modified copy feature works better way published software remaster maintains integrity named product derived adherence shared software repository modifications intention maintaining good name needing approval approval happen name repository option become master creator published software remaster work evolve software must least arrange maintenance support channels updating user documentation providing forum internet relay chat line wiki providing intent maintain version life usefulness remastering centers around reputation product distribution process requires official sanctioned version differs attitude much free software many cases name product cheap plentiful stable guarantees liabilities offered permission inherently granted redistribution modified version name original repository master creative flavors spins may already offered original producers remaster production supports additional software outside supports new mixture software original repository keeps modifications original masters outside master repository software remastering tolerated maintainers master repository free software modifications encouraged social conventions mklivecd runs linux machine make bootable portable media image linux system works linux distribution probably needs installed first remaster personalized version pclinuxos created according needs individual created using mklivecd script applied installation official flavors pclinuxos official remaster include software components official repository version control community remaster may contain software components outside reference pclinuxos derived pclinuxos based pclinuxos intended distribution several third-party distributions years though may mention connection follow strict guidelines concerning quality maintainability distribution channels subject approval officiating members forum pclinuxos gnome edition example community remaster unity linux intended base platform acts distribution template ensures interoperability packages upon one encouraged remaster new gnu/linux os distributions linux mint remastering tool called mintconstructor creating distributions based linux mint creating iso files also package manager uses .mint files linux mint based ubuntu linux distribution ubuntu based debian distribution linux mint also offers debian edition provide example meeting kind codebase challenges goes remastering branch two distributions gentoo linux uses catalyst user installs configures runs gets one big archive-formatted file /var/tmp/catalyst/builds configuration options target machine architecture development version stamp differentiation stamp example version hardened extra security user must provide catalyst snapshot portage tree point target profile branch portage tree portage tree hierarchy directories oriented names categories packages package managers use normal everyday maintenance software fedora linux uses revisor enable user compose customized installation live media arch linux uses archiso remaster arch installation target machine rare hardware internet connection cases modified deployment occur multiple times remastered isos bootable also used system rescue demonstrations arch setup task testing new software installed rollout custom installation onto many machines etc arch linux wiki also gives procedure manually archiso automatically involves copying portions installation iso using linux commands mount mkdir chroot mksquashfs arch package manager pacman mx linux uses mx-snapshot gui tool remaster live installation single .iso file quickly conveniently cloned image bootable disk usb-thumbdrive maintaining settings way installation conveniently migrated distributed new hard-disk usb-thumbdrive requiring next administrative effort since advanced method copying file system developed antix-linux utilizing bind-mounts performs heavy lifting snapshot also serves essentially complete convenient backup installation examples section show historical operational aspects software remastering occurred microsoft windows 98lite remastering tool windows 95 windows 98 windows without internet explorer written shane brooks written response microsoft claim antitrust proceedings ie integrated windows removed without breaking features 98lite created 1998 original release windows 98 necessity since time brooks slower laptop computer ran windows 95 operating system fine windows 98 simply slow brooks liked stability windows 98 offered well new features need internet explorer browser original 98lite simple dos based installer ran windows 98 installation installer made modifications fresh installation windows preventing installation internet explorer active desktop installation first release 98lite required user extract certain files windows 95 disk 98lite uses windows 95 shell second program called shell swap swapped explorer shell windows 95 explorer contain web features 98 explorer therefore considerably faster lightweight designed existing installations windows 98 original 98lite designed new installation windows third program converted required components addable removable options version 2.0 98lite three programs merged combined single program ie remover combined components converter making ie uninstallable reinstallable add/remove programs control panel applet components user could also choose windows 95 shell keep internet explorer installed user three installation options sleek option allowed user install 98lite windows 95 shell like original release user could choose chubby used windows 98 shell active desktop features disabled final option overweight installed 98lite windows 98 shell nothing disabled internet explorer still removed version 3.0 added support windows 98 second edition upgraded version windows 98 internet explorer 5.0 made 98lite 1.0 2.0 obsolete current 4.x line many improvements including bugfixes support windows installing version directx 98lited windows requires least temporary presence pc health otherwise directx refuses install finishing installation attempt error message directx copy required file revenge mozilla another free application removes internet explorer windows 98 restores windows 95 explorer.exe two versions one original windows 98 release another win98 se version windows longer supported updated also company spun lite-pc produces windows 98 installations small enough easily fit embedded microchips small 8mb using 98eos also many free alternatives mindows nano98 provide either smaller file sizes broad functionality creator 98lite also built similar tool windows 2000 windows xp called 2000-xplite removes windows components intended removable includes out-of-box experience internet explorer outlook express windows media player others 2000-xplite also allows tweaks operating system enhance performance 2000-xplite use text interface 98lite like 98lite 2000-xplite installs windows components removes unwanted components installation nlite designed remove unwanted windows 2000 windows xp 32 64 bit windows server 2003 system components create cut-down customized installation cds nlite built dino nuhagić free personal use purchase options available september 2014 beta-version windows 7 later publicly released user chooses wanted 'functionality options nlite attempts warn user removing dependent components creation custom installer also lets users add device drivers integrate service packs windows updates well remove drivers obsolete unwanted hardware remove unwanted language keyboard options unwanted applications allows customization installation process including product key entry administrator password regional settings creating user account names options normally set control panel installation well numerous 'tweaks various degrees 'unattended installation also possible end installer creation process nlite burn installation direct cd create .iso image later use also option saving loading previous session choices .txt format speed checking modification custom installation required since custom installer contain unwanted components lead smaller installation package faster installation considerable benefit staff still using manual 'roll approach without benefit microsoft sysprep software-minimized cds also allow windows system installed hard disks 512 mb size hfslip open source command line hotfix service pack slipstreaming tool designed update windows 2000 windows xp windows server 2003 installation sources addition hotfixes service packs hfslip slipstreams microsoft updates internet explorer directx 9.0c windows media player windows media codecs also integrates third-party device driver updates including driverpacks hfslip slipstreams replaces original files newer versions found updates microsoft download center hfslip places hotfixes non-standard required special installation procedure svcpack folder installed automatically near end windows setup may 2010 hfslip longer developed main website taken autostreamer free slipstreaming tool windows xp integrate service pack windows xp installation cd-rom image main interface autostreamer wizard guides user slipstreaming process according pc world simplifies once-intimidating chore slipstreaming windows xp cd—producing xp sp2 cd sp1 even vintage original xp cd driverpacks project open source project started wim leers jeff herre leers released first pack 2005 collections device drivers called driverpacks exist cpu chipsets cpu graphics/video ethernet mass storage/removable/usb audio/sound wireless wi-fi/wlan hardware driverpacks base tool integrates driverpacks one uniform windows installation cd works every piece hardware needs additional device drivers installation compatible windows versions based nt 5.1 32-bit kernel windows 2000 windows xp windows server 2003 windows vista windows 7 vlite windows vista 32 64 bit version nlite create cut-down customized installation cd bootable usb stick people reported success using vlite windows 7 vlite fully compatible windows 7 intended support windows 7 sept. 2014 ntlite released support windows 7 later ntlite software tool creator nlite support windows 7 windows 8 windows 8.1 windows 10. ntlite also prevents components installed remove already-installed system using paid version win toolkit create cut-down customized installation cd bootable usb stick windows 7 later versions
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Operating systems
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microsoft push notification service microsoft push notification service commonly referred mpns mobile service developed microsoft allows developers send push data servers windows phone applications mpns natively supported applications target windows phone 8 operating system microsoft announced windows notification service windows 8 windows phone 8.1 2011 effectively replacing mpns service mpns used applications installed windows phone 8.1 source code migrated microsoft silverlight application modified target windows phone 8.1 already registered use mpns upgrade mpns natively designed use windows phone 8 applications implement service allows developers send toast notifications well update tile image flip notification text application windows metro start screen tile accomplished developers sending post messages mpns server network request relevant content user typically must allow data notifications received application register mpns notification data mpns implemented send notification data using encrypted channel developer purchases ssl certificate third-party provider uploads private key certificate data microsoft developer portal account otherwise mpns implemented send notification data using unencrypted channel applications utilize unencrypted channels rate size limitations notification requests content updated displayed device limits lifted purchasing ssl certificate switching utilize mpns encryption mpns consists servers internal interfaces maintain store channel uri identifiers device information authenticate post requests received developer servers enqueue deliver requested data mobile devices application registers data notifications receives unique channel uri identifiers mpns network identifier used application developer third-party server reference device particular data delivery request sent mobile device receives channel uri identifier sent developer server stored server sends post message mpns network data delivery channel uri identifier included within message payload along data deliver parameter options specified mpns network authenticate identifier enqueue data delivery mobile device
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Operating systems
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jasbug jasbug security bug disclosed february 2015 affecting core components microsoft windows operating system vulnerability dated back 2000 affected supported editions windows server 2003 windows vista windows server 2008 windows 7 windows server 2008 r2 windows 8 windows server 2012 windows rt windows 8.1 windows server 2012 r2 windows rt 8.1 vulnerability allows hackers remotely take control windows devices connect active directory domain jasbug registered common vulnerabilities exposures system industrial control systems cyber emergency response team part department homeland security issued ics-alert-15-041-01 warning control systems owners expedite applying critical jasbug fixes microsoft released two patches ms15-011 ms15-014 address jasbug day vulnerability disclosed fixes took microsoft year develop deploy due complexity jasbug vulnerability time disclosure 300 million computers believed vulnerable exploit jasbug disclosed public microsoft part patch tuesday february 10th 2015 vulnerability initially reported microsoft january 2014 jeff schmidt founder jas global advisors microsoft publicly announced security vulnerability garnered name jasbug reference role jas global advisors played discovering exploit 2014 jas global advisors working engagement internet corporation assigned names numbers icann organization governing standards internet research potential technical issues surrounding rollout new generic top level domains gtlds internet working research jas global advisors business partner simmachines uncovered vulnerability applying big data analytical techniques large technical data sets jasbug principally affects business government users home users less likely affected jasbug use domain-configured computers white house cybersecurity advisor michael daniel spoke importance addressing jasbug meeting information security privacy advisory board national institute standards technology office management budget department homeland security immediately took steps fix vulnerability federal networks suzanne e. spaulding serving secretary national protection programs directorate nppd department homeland security mentioned jasbug february 2015 house representatives hearing touched potential effect dhs funding hiatus aftermath jasbug various government agencies updated technical specifications mitigate exploit risks example united states department veteran affairs decided may 2015 unapprove use windows server 2003 based jasbug risks according microsoft exploit takes advantage group policy receives applies policy data domain-joined system connects domain controller one likely exploitation flaw involves deceiving user domain-configured system network controlled hacker despite potential effect indication jasbug vulnerability ever used cyberhackers access corporate government computers jasbug affects windows vista windows server 2008 windows 7 windows server 2008 r2 windows 8 windows 8.1 windows server 2012 windows server 2012 r2 windows rt windows rt 8.1 windows server 2003 also affected jasbug patch platform microsoft indicated feasible build fix version jasbug also affects windows xp windows 2000 patch made available operating systems longer supported microsoft unlike high-profile vulnerabilities like heartbleed shellshock gotofail poodle jasbug design problem implementation problem making type vulnerability unusual much difficult fix fix required microsoft re-engineer core components operating system add several new features including additional hardening group policy feature organizations use centrally manage windows systems applications user settings active directory environments microsoft able fix jasbug flaw windows server 2003 systems noting architecture properly support fix provided update exist windows server 2003 systems making infeasible build fix windows server 2003 unpatched unpatchable platforms may vulnerable jasbug security firms like symantec recommend organizations use intrusion prevention systems ips monitor network activity possible malicious jasbug traffic
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Computer security
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archie search engine archie tool indexing ftp archives allowing people find specific files considered first internet search engine original implementation written 1990 alan emtage postgraduate student mcgill university montreal bill heelan studied concordia university montreal worked mcgill university time archie service began project students volunteer staff mcgill university school computer science 1987 peter deutsch systems manager school emtage heelan asked connect school computer science internet earliest versions archie written alan emtage simply contacted list ftp archives regular basis contacting roughly month waste many resources remote servers requested listing listings stored local files searched using unix grep command name derives word archive without v. alan emtage said contrary popular belief association archie comics despised despite early internet search technologies jughead veronica named characters comics anarchie one earliest graphical ftp clients named ability perform archie searches archie developed tool mass discovery concept simple developers populated engine servers databases anonymous ftp host directories used find specific file titles since list plugged searchable database websites bill heelan peter deutsch wrote script allowing people log search collected information using telnet protocol host archie.mcgill.ca 132.206.2.3 later efficient front- back-ends developed system spread local tool network-wide resource popular service available multiple sites around internet collected data would exchanged neighbouring archie servers servers could accessed multiple ways using local client archie xarchie telnetting server directly sending queries electronic mail later via world wide web interface zenith fame archie search engine accounted 50 montreal internet traffic 1992 emtage along peter deutsch financial help mcgill university formed bunyip information systems world first company expressly founded dedicated providing internet information services licensed commercial version archie search engine used millions people worldwide bill heelan followed bunyip soon together bibi ali sandro mazzucato part so-called archie group group significantly updated archie database indexed web-pages work search engine ceased late 1990s legacy archie server still maintained active historic purposes poland university warsaw interdisciplinary centre mathematical computational modelling
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Internet protocols
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storsimple storsimple privately held company based santa clara california marketing cloud storage storsimple funded venture capital index ventures redpoint ventures ignition partners mayfield fund total 31.5 million founded 2009 former cisco systems brocade communications systems executives ursheet parikh guru pangal storsimple marketed cloud storage gateway computer appliance called cloud-integrated storage cis approach claimed integrate primary storage data deduplication automated tiered storage data across local cloud storage data compression encryption significantly faster data backup disaster recovery times storsimple certified microsoft windows server 2008 vmware integrated cloud storage amazon google microsoft rackspace 2012 storsimple considered forefront genre appliance iscsi interface using 10 gigabit ethernet used serial ata disks well solid-state drives april 2012 storsimple announced replacement 2u 5010 2.5tb raw capacity 7010 5tb raw models 5020 2tb raw capacity 7020 4tb 5520 10tb 4u 7520 20tb october 16 2012 microsoft agreed acquire storsimple finalized november 15 acquisition microsoft integrated storsimple azure product suite refreshed hardware launching 8100 8600 on-premise fixed-configuration storage arrays 2014 8100 offered 10tb 40tb locally depending data compression data de-duplication 200tb maximum capacity inclusive azure cloud storage 8600 offered 40tb 100tb locally 500tb inclusive cloud storage like predecessors appliances combined solid state standard disk drives virtualised version platform running virtual machine azure cloud initially marketed 1100 re-branded 8010 2015 replaced 8020 offering 64tb maximum compared predecessor ’ 30tb
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Distributed computing architecture
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86-dos 86-dos discontinued operating system developed marketed seattle computer products scp intel 8086-based computer kit initially known qdos quick dirty operating system name changed 86-dos scp started licensing operating system 1980 86-dos command structure application programming interface imitated digital research cp/m operating system made easy port programs latter system licensed purchased microsoft developed ms-dos pc dos 86-dos created sales seattle computer products 8086 computer kit demonstrated june 1979 shipped november languishing due absence operating system software scp could sell board microsoft standalone disk basic-86 microsoft developed prototype scp hardware scp wanted offer 8086-version cp/m digital research announced release date uncertain first time digital research lagged behind hardware developments two years earlier slow adapt cp/m new floppy disk formats hard disk drives april 1980 scp assigned 24-year-old tim paterson develop substitute cp/m-86 using cp/m-80 manual reference paterson modeled 86-dos architecture interfaces adapted meet requirements intel 8086 16-bit processor easy partially automated source-level translatability many existing 8-bit cp/m programs porting either dos cp/m-86 equally difficult eased fact intel already published method could used automatically translate software intel 8080 processor cp/m designed new 8086 instruction set time made number changes enhancements address saw cp/m shortcomings cp/m cached file system information memory speed required user force update disk removing user forgot disk would become corrupt paterson took safer slower approach updating disk operation cp/m pip command copied files supported several special file names referred hardware devices printers communication ports paterson built names operating system device files program could use gave copying program intuitive name copy rather implementing cp/m file system drew microsoft standalone disk basic-86 file allocation table fat file system mid-1980 scp advertised 86-dos priced 95 owners 1290 8086 board 195 others touted software ability read zilog z80 source code cp/m disk translate 8086 source code promised minor hand correction optimization needed produce 8086 binaries october 1980 ibm developing would become original ibm personal computer cp/m far popular operating system use time ibm felt needed cp/m order compete ibm representatives visited digital research discussed licensing digital research licensing representative dorothy kildall née mcewen hesitated sign ibm non-disclosure agreement although nda later accepted digital research would accept ibm proposal 250,000 exchange many copies ibm could sell insisting usual royalty-based plan later discussions ibm bill gates gates mentioned existence 86-dos ibm representative jack sams told get license microsoft purchased non-exclusive license 86-dos seattle computer products december 1980 25,000 may 1981 hired tim paterson port system ibm pc used slower less expensive intel 8088 processor specific family peripherals ibm watched developments daily submitting 300 change requests accepted product wrote user manual july 1981 month pc release microsoft purchased rights 86-dos scp 50,000 met ibm main criteria looked like cp/m easy adapt existing 8-bit cp/m programs run notably thanks trans command would translate source files 8080 8086 machine instructions microsoft licensed 86-dos ibm became pc dos 1.0 license also permitted microsoft sell dos companies deal spectacularly successful scp later claimed court microsoft concealed relationship ibm order purchase operating system cheaply scp ultimately received 1 million settlement payment digital research founder gary kildall examined pc dos found duplicated cp/m programming interface wanted sue ibm time claimed pc dos product however digital research attorney believe relevant law clear enough sue nonetheless kildall confronted ibm persuaded offer cp/m-86 pc exchange release liability controversy continued surround similarity two systems perhaps sensational claim came jerry pournelle said kildall personally demonstrated dos contained cp/m code entering command dos displayed kildall name pournelle never revealed command nobody come forward corroborate story 2004 book kildall says used encrypted message demonstrate manufacturers copied cp/m say found message dos instead kildall memoir source book pointed well-known interface similarity paterson insists 86-dos software original work denied referring otherwise using cp/m code writing 2004 book appeared sued authors publishers defamation court ruled summary judgment defamation occurred book claims opinions based research provably false following list commands supported 86-dos 1982 ibm asked microsoft release version dos compatible hard disk drive pc dos 2.0 almost complete rewrite dos march 1983 little 86-dos remained enduring element 86-dos primitive line editor edlin remained editor supplied microsoft versions dos june 1991 release ms-dos 5.0 included text-based user interface editor called ms-dos editor based qbasic edlin still used contemporary machines since emulated dos environment windows 10 32 bit seattle computer products 86-dos supported fat12 filesystem range 8-inch 5.25-inch floppy disk drives s-100 floppy disk controller hardware manufactured cromemco tarbell electronics north star computers western digital fd1771-based cromemco tarbell boards supported one-sided single-density soft-sectored drives tarbell double-density board utilizing fd1791 supported well later scp offered advanced floppy disk controllers like disk master series 86-dos take advantage fat id byte bios parameter block bpb later dos versions distinguish different media formats instead different drive letters hard-coded time compilation associated different physical floppy drives sides densities meant depending type disk addressed certain drive letter recognized correctly concept later emulated flexibility driver.sys dos 3.x later versions two logical format variants 86-dos 12-bit fat format existed — original format 16-byte directory entries later format since 86-dos 0.42 32-byte directory entries second one logically compatible fat12 format known since release ms-dos pc dos ms-dos still mount volumes absence bpb falls back retrieve fat id fat entry design fat file system clust 0cluster 0 choose among hard-coded disk geometry profiles formats volume formatted ms-dos would otherwise supported systems typically also formats id located first byte logical sector 1 — volume second sector physical cylinder-head-sector chs address 0/0/2 logical block addressing lba address 1 — since ms-dos assumes single reserved sector boot sector 86-dos reserved sectors area significantly larger whole tracks therefore prototypical fat id located elsewhere disk making impossible ms-dos retrieve even would hard-coded disk profile associated would take larger reserved sectors region 86-dos account cp/m 2 floppy media readable rdcpm 86-dos offer specific support fixed disks third-party solutions form hard disk controllers corresponding i/o system extensions 86-dos available companies like tallgrass technologies making hard disks accessible similar superfloppies within size limits fat12 file system various oem versions ms-dos 1.2x 2.x supported number similar 8.0 fat12 floppy disk formats well although identical supported 86-dos disk formats supported one last versions developed tim paterson microsoft ms-dos 1.25 march 1982 scp gazelle computer scp controller cromemco 16fdc controller default version supported ms-dos-compatible variants 8.0 formats single reserved sector could built provide two extra drive letters read write floppies previous scp 86-dos 8.0 disk formats since 0.42 well 1984 seattle computer products released oem version ms-dos 2.0 scp s-100 computer scp-500 disk master floppy controller added support 5.25 dd/1s 180 kb dd/2s 360 kb fat12 formats supported older formats well although possibly parameters modified compared ms-dos 1.25
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Operating systems
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gnome web gnome web called epiphany 2012 free open-source lightweight web browser based webkitgtk developed gnome linux unix-like systems browser forked galeon 2002 developers disagreements galeon growing complexity since developed part gnome core applications uses gnome technology settings applicable follows gnome human interface guidelines gnome web originally used mozilla gecko version 2.28 starting version 2.20 september 2007 switched webkitgtk due technical problems gecko change allows relatively small developer community maintain sufficient level modern web standards support features gnome web includes best integration gnome reuse gnome configuration settings built-in integration gnome keyring securely store passwords first-class support new linux technologies like major gtk versions wayland small package size 2mb debian ubuntu full multimedia support using gstreamer reader mode/reading mode since v3.30 september 2018 mouse gestures smart bookmarks web application integration user desktop management page support google safe browsing since v3.28 2018-03 gnome web default web browser elementary os recommended excellent web application integration security benefits related marco pesenti gritti initiator galeon originally developed epiphany 2002 fork galeon fork occurred divergent aims gritti rest galeon development team new features gritti regarded galeon monolithic design number user-configurable features factors limiting galeon maintainability user base expansion rest galeon developers wanted see features added time gnome project created gnome human interface guidelines promoted simplification user interfaces galeon oriented towards power users developers saw implementation guidelines unacceptable result gritti created new browser based galeon codebase non-mission-critical features removed intended epiphany comply fully gnome human interface guidelines simple user-interface epiphany theme settings uses gnome settings specified gnome control center gritti explained motivations galeon continued fork lost momentum due remaining developers failure keep new features changes mozilla introduced galeon development finally stalled developers decided work set extensions bring galeon advanced features epiphany instead epiphany early philosophy included commitment creating web browser specifically gnome gritti ended work epiphany project gnome team led xan lopez christian persch jean-françois rameau direct project gritti died cancer 23 may 2015 promote epiphany default web browser linux distributions gnome default desktop environment distros offer firefox instead minimalist distributions epiphany installed gnome meta-package packages group first version epiphany released december 24 2002 epiphany initially used gecko layout engine mozilla project display web pages provided gnome integrated graphical user interface gecko instead mozilla xul interface development process epiphany mainly focused numerous small usability improvements notable new text entry widget first appeared 1.8 stable version series new widget supported icons inside text area reduced amount screen space needed present information improved gnome integration second major milestone version 1.0 epiphany development 2.14 release first epiphany release followed gnome version numbering also featured network awareness using networkmanager smart bookmarks-related improvements possibility compiled xulrunner latter critical previously epiphany could use firefox mozilla/seamonkey layout engine provider could installed alongside one browsers xulrunner support made possible install epiphany sole web browser system development process suffered major problems related gecko backend address issues july 2007 epiphany team added support webkit alternative rendering engine epiphany backend development advanced epiphany team announced would stop using gecko rendering engine proceed using webkit size development team complexity porting whole browser new backend caused epiphany re-release version 2.22 bugfixes instead actual development code browser development remained stagnant project team announced epiphany 2.26 would final gecko-based version eventually september 2009 webkit-powered epiphany 2.28 released part gnome 2.28 gnome 3.4 release epiphany renamed web however name epiphany still used internally development bug tracking source code package remains epiphany-browser debian-based distros epiphany redhat-based distros gnome web based webkit browser engine provides support html 4 xhtml css 1 2 substantial degree implementation html5 css 3 features web inspector html javascript debugging tool npapi including adobe flash icedtea-web plug-ins support web reuses gnome frameworks settings therefore user interface theme gnome default theme network settings gnome networkmanager configuration printing gnome printing system settings gsettings gnome default applications settings used internet media types handling built-in preference manager web designed present user basic browser-specific settings advanced configuration done stand-alone gsettings configurator tools gnome default dconf command line dconf-editor graphical follows gnome human interface guidelines follows platform-wide design changes example web 3.4 release menu application-wide actions moved gnome shell top panel application menu menubar replaced super menu button triggers display window-specific menu entries browsers feature hierarchical folder-based bookmark system web uses categorized bookmarks single bookmark web exist multiple categories web browsers gnome computer software special category includes bookmarks yet categorized another innovative concept supported web though originally galeon smart bookmarks take single argument specified address bar textbox toolbar bookmarks along browsing history accessed address bar find-as-you-type manner gnome web extensible official third-party extensions version 3.6 plug-in system called web extensions package distributed developers gnome web contained official extensions version 3.8 system removed due problems stability maintainability popular extensions ad blocking moved core application instead since gnome 3.2 released september 2011 web allows creating application launchers web applications subsequent invocation launcher brings plain site-specific browser single instance web limited one domain off-site links opening normal browser launcher created way accessible desktop limited gnome shell instance may used unity used ubuntu feature facilitates integration desktop world wide web goal web developers similar features found windows version google chrome purpose mozilla foundation previously developed standalone application mozilla prism superseded project chromeless web applications managed within epiphany main instance applications deleted page accessible special uri applications approach supposed temporary solution common gnome-wide application management intended implemented gnome 3.4 rolled since gnome 3.26 web support firefox sync allows users sync bookmarks history passwords open tabs firefox sync shared copy firefox web user signs firefox sync since gnome 3.28 gnome web support google safe browsing help prevent users visiting malicious websites component gnome desktop environment web neither software hardware dependencies beyond gnome platform though gnome project list minimum system requirements states gnome 3 run modern computer gnome web run many hardware platforms including i386 amd64 several instruction set architectures reviewing webkit-powered epiphany 2.28 september 2009 ryan paul ars technica said epiphany quite snappy gnome 2.28 scores 100/100 acid3 test using webkit help differentiate epiphany firefox shipped default browser major linux distributors reviewing epiphany 2.30 july 2010 jack wallen described efficient different noted problem crashes first started working epiphany crashed sites visited little research little debugging realized issue javascript epiphany current release strange reason n't like javascript way around disable javascript yes means lot features wo n't work lot sites – also means sites load faster wo n't prone issues like crashing browser wallen concluded positively browser although epiphany n't fully replaced chrome firefox one-stop-shop browser use much would previously small footprint fast startup clean interface march 2011 veronica henry reviewed epiphany 2.32 saying fair would hard sell primary desktop browser users fact n't even setting let designate default browser instance need fire lighting-fast browser quick surfing epiphany trick noted though still use firefox primary browser lately seems run snail pace one first things noticed epiphany quickly launches subsequent page loads system equally fast henry criticized epiphany short list extensions singling lack firebug deficiency web instead supports web inspector offered webkit engine similar functionality april 2012 ryan paul ars technica used web example criticism gnome 3.4 design decisions aside poor initial discoverability panel menu model works reasonably well simple applications ... unfortunately n't scale well complex applications best example approach pose difficulties gnome default web browser ... application functionality split across two completely separate menus constitute usability improvement addressed later versions single unified menu october 2016 review bertel king jr. noted makeuseof later versions offer best integration find gnome shell lacks add-ons found mainstream browsers users like minimalism speed tab isolation prevents one misbehaving site crashing entire browser
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Internet protocols
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simple mail transfer protocol simple mail transfer protocol smtp communication protocol electronic mail transmission internet standard smtp first defined 1982 updated 2008 extended smtp additions protocol variety widespread use today mail servers message transfer agents use smtp send receive mail messages proprietary systems microsoft exchange ibm notes webmail systems outlook.com gmail yahoo mail may use non-standard protocols internally use smtp sending receiving email outside systems smtp servers commonly use transmission control protocol port number 25 user-level email clients typically use smtp sending messages mail server relaying typically submit outgoing email mail server port 587 465 per rfc 8314 retrieving messages imap pop3 standard proprietary servers also often implement proprietary protocols e.g. exchange activesync various forms one-to-one electronic messaging used 1960s users communicated using systems developed specific mainframe computers computers interconnected especially u.s. government arpanet standards developed permit exchange messages different operating systems smtp grew standards developed 1970s smtp traces roots two implementations described 1971 mail box protocol whose implementation disputed discussed rfcs sndmsg program according ray tomlinson bbn invented tenex computers send mail messages across arpanet fewer 50 hosts connected arpanet time implementations include ftp mail mail protocol 1973 development work continued throughout 1970s arpanet transitioned modern internet around 1980 jon postel proposed mail transfer protocol 1980 began remove mail reliance ftp smtp published november 1981 also postel smtp standard developed around time usenet one-to-many communication network similarities smtp became widely used early 1980s time complement unix unix copy program uucp mail better suited handling email transfers machines intermittently connected smtp hand works best sending receiving machines connected network time use store forward mechanism examples push technology though usenet newsgroups still propagated uucp servers uucp mail transport virtually disappeared along bang paths used message routing headers sendmail released 4.1cbsd right one first mail transfer agents implement smtp time bsd unix became popular operating system internet sendmail became common mta mail transfer agent popular smtp server programs include postfix qmail novell groupwise exim novell netmail microsoft exchange server oracle communications messaging server message submission smtp-auth introduced 1998 1999 describing new trends email delivery originally smtp servers typically internal organization receiving mail organization outside relaying messages organization outside time went smtp servers mail transfer agents practice expanding roles become message submission agents mail user agents relaying mail outside organization e.g company executive wishes send email trip using corporate smtp server issue consequence rapid expansion popularity world wide web meant smtp include specific rules methods relaying mail authenticating users prevent abuses relaying unsolicited email spam work message submission originally started popular mail servers would often rewrite mail attempt fix problems example adding domain name unqualified address behavior helpful message fixed initial submission dangerous harmful message originated elsewhere relayed cleanly separating mail submission relay seen way permit encourage rewriting submissions prohibiting rewriting relay spam became prevalent also seen way provide authorization mail sent organization well traceability separation relay submission quickly became foundation modern email security practices protocol started purely ascii text-based deal well binary files characters many non-english languages standards multipurpose internet mail extensions mime developed encode binary files transfer smtp mail transfer agents mtas developed sendmail also tended implemented 8-bit-clean alternate send eight strategy could used transmit arbitrary text data 8-bit ascii-like character encoding via smtp mojibake still problem due differing character set mappings vendors although email addresses still allowed ascii 8-bit-clean mtas today tend support 8bitmime extension permitting binary files transmitted almost easily plain text recently smtputf8 extension created support utf-8 text allowing international content addresses non-latin scripts like cyrillic chinese many people contributed core smtp specifications among jon postel eric allman dave crocker ned freed randall gellens john klensin keith moore email submitted mail client mail user agent mua mail server mail submission agent msa using smtp tcp port 587 mailbox providers still allow submission traditional port 25 msa delivers mail mail transfer agent mail transfer agent mta often two agents instances software launched different options machine local processing done either single machine split among multiple machines mail agent processes one machine share files processing multiple machines transfer messages using smtp machine configured use next machine smart host process mta smtp server right boundary mta uses domain name system dns look mail exchanger record mx record recipient domain part email address right mx record contains name target host based target host factors mta selects exchange server see article mx record mta connects exchange server smtp client message transfer occur single connection two mtas series hops intermediary systems receiving smtp server may ultimate destination intermediate relay stores forwards message gateway may forward message using protocol smtp hop formal handoff responsibility message whereby receiving server must either deliver message properly report failure final hop accepts incoming message hands mail delivery agent mda local delivery mda saves messages relevant mailbox format sending reception done using one multiple computers diagram mda depicted one box near mail exchanger box mda may deliver messages directly storage forward network using smtp protocol local mail transfer protocol lmtp derivative smtp designed purpose delivered local mail server mail stored batch retrieval authenticated mail clients muas mail retrieved end-user applications called email clients using internet message access protocol imap protocol facilitates access mail manages stored mail post office protocol pop typically uses traditional mbox mail file format proprietary system microsoft exchange/outlook lotus notes/domino webmail clients may use either method retrieval protocol often formal standard smtp defines message transport message content thus defines mail envelope parameters envelope sender header except trace information body message std 10 define smtp envelope std 11 define message header body formally referred internet message format smtp connection-oriented text-based protocol mail sender communicates mail receiver issuing command strings supplying necessary data reliable ordered data stream channel typically transmission control protocol tcp connection smtp session consists commands originated smtp client initiating agent sender transmitter corresponding responses smtp server listening agent receiver session opened session parameters exchanged session may include zero smtp transactions smtp transaction consists three command/reply sequences besides intermediate reply data server reply either positive 2xx reply codes negative negative replies permanent 5xx codes transient 4xx codes reject permanent failure client send bounce message server received drop positive response followed message discard rather delivery initiating host smtp client either end-user email client functionally identified mail user agent mua relay server mail transfer agent mta smtp server acting smtp client relevant session order relay mail fully capable smtp servers maintain queues messages retrying message transmissions resulted transient failures mua knows outgoing mail smtp server configuration relay server typically determines server connect looking mx mail exchange dns resource record recipient domain name mx record found conformant relaying server instead looks record relay servers also configured use smart host relay server initiates tcp connection server well-known port smtp port 25 connecting msa port 587 main difference mta msa connecting msa requires smtp authentication smtp delivery protocol normal use mail pushed destination mail server next-hop mail server arrives mail routed based destination server individual user addressed protocols post office protocol pop internet message access protocol imap specifically designed use individual users retrieving messages managing mail boxes permit intermittently-connected mail server pull messages remote server demand smtp feature initiate mail queue processing remote server see remote message queue starting pop imap unsuitable protocols relaying mail intermittently-connected machines designed operate final delivery information critical correct operation mail relay mail envelope removed remote message queue starting feature smtp permits remote host start processing mail queue server may receive messages destined sending turn command feature however deemed insecure extended etrn command operates securely using authentication method based domain name system information email client needs know ip address initial smtp server given part configuration usually given dns name server deliver outgoing messages behalf user server administrators need impose control clients use server enables deal abuse example spam two solutions common use system isp smtp server allow access users outside isp network precisely server may allow access users ip address provided isp equivalent requiring connected internet using isp mobile user may often network normal isp find sending email fails configured smtp server choice longer accessible system several variations example organisation smtp server may provide service users network enforcing firewalling block access users wider internet server may perform range checks client ip address methods typically used corporations institutions universities provided smtp server outbound mail use internally within organisation however bodies use client authentication methods described user mobile may use different isps connect internet kind usage restriction onerous altering configured outbound email smtp server address impractical highly desirable able use email client configuration information need change modern smtp servers typically require authentication clients credentials allowing access rather restricting access location described earlier flexible system friendly mobile users allows fixed choice configured outbound smtp server smtp authentication often abbreviated smtp auth extension smtp order log using authentication mechanism server accessible wider internet enforce kinds access restrictions known open relay generally considered bad practice worthy blacklisting communication mail servers generally uses standard tcp port 25 designated smtp mail clients however generally n't use instead using specific submission ports mail services generally accept email submission clients one port 2525 others may used individual providers never officially supported internet service providers block outgoing port 25 traffic customers anti-spam measure reason businesses typically configure firewall allow outgoing port 25 traffic designated mail servers typical example sending message via smtp two mailboxes alice theboss located mail domain example.com localhost.com reproduced following session exchange example conversation parts prefixed c server client respectively labels part exchange message sender smtp client establishes reliable communications channel message receiver smtp server session opened greeting server usually containing fully qualified domain name fqdn case smtp.example.com client initiates dialog responding codice_1 command identifying command parameter fqdn address literal none available client notifies receiver originating email address message codice_2 command also return bounce address case message delivered example email message sent two mailboxes smtp server one recipient listed cc header fields corresponding smtp command codice_3 successful reception execution command acknowledged server result code response message e.g. 250 ok transmission body mail message initiated codice_4 command transmitted verbatim line line terminated end-of-data sequence sequence consists new-line cr lf single full stop period followed another new-line since message body contain line period part text client sends two periods every time line starts period correspondingly server replaces every sequence two periods beginning line single one escaping method called dot-stuffing server positive reply end-of-data exemplified implies server taken responsibility delivering message message doubled communication failure time e.g due power shortage sender received 250 reply must assume message delivered hand receiver decided accept message must assume message delivered thus time span agents active copies message try deliver probability communication failure occurs exactly step directly proportional amount filtering server performs message body often anti-spam purposes limiting timeout specified 10 minutes codice_5 command ends session email recipients located elsewhere client would codice_5 connect appropriate smtp server subsequent recipients current destination queued information client sends codice_1 codice_2 commands added seen example code additional header fields message receiving server adds codice_9 codice_10 header field respectively clients implemented close connection message accepted codice_11 last two lines may actually omitted causes error server trying send codice_12 reply original smtp protocol supported unauthenticated unencrypted ascii text communications susceptible man middle attacks spoofing spamming requiring encode binary data transmission number optional extensions specify various mechanisms address problems clients learn server supported options using codice_13 greeting exemplified instead original codice_1 example clients fall back codice_1 server support smtp extensions modern clients may use esmtp extension keyword codice_16 query server maximum message size accepted older clients servers may try transfer excessively sized messages rejected consuming network resources including connect time network links paid minute users manually determine advance maximum size accepted esmtp servers client replaces codice_1 command codice_13 command thus smtp2.example.com declares accept fixed maximum message size larger 14,680,064 octets 8-bit bytes simplest case esmtp server declares maximum codice_16 immediately receiving codice_13 according however numeric parameter codice_16 extension codice_13 response optional clients may instead issuing codice_2 command include numeric estimate size message transferring server refuse receipt overly-large messages original smtp supports transport textual data therefore binary data needs encoded text transfer decoded leading increased size transit 8bitmime command developed alleviate limitation standardized 1994 obsoleted 2011 corresponding new std 71 facilitates transparent exchange e-mail messages containing octets outside seven-bit ascii character set prior availability 8bitmime implementations mail user agents employed several techniques cope seven-bit limitation binary-to-text encodings including ones provided mime utf-7 however workarounds inflates required amount data transmission non-ascii text non-esmtp servers allowed sending 8-bit characters risky send data server whose 8-bit capabilities unknown on-demand mail relay odmr smtp extension standardized allows intermittently-connected smtp server receive email queued connected original smtp supports email addresses composed ascii characters inconvenient users whose native script latin based use diacritic ascii character set limitation alleviated via extensions enabling utf-8 address names introduced experimental codice_24 command later superseded introduced codice_25 command extensions provide support multi-byte non-ascii characters email addresses diacritics language characters greek chinese current support limited strong interest broad adoption related rfcs countries like china large user base latin ascii foreign script mail delivery occur plain text encrypted connections however communicating parties might know advance party ability use secure channel smtp authentication often abbreviated smtp auth describes mechanism client log using authentication mechanism supported server mainly used submission servers authentication mandatory multiple rfcs exist provide different variations mechanism update smtp extensions describe starttls command enables server tell client supports encrypted communications client request upgrade secure channel starttls effective passive observation attacks since starttls negotiation happens plain text active attacker trivially remove starttls command attack sometimes called striptls client would think server send starttls header support starttls server would think client respond starttls header thus support starttls note starttls also defined imap pop3 rfcs protocols serve different purposes smtp used communication message transfer agents imap pop3 end clients message transfer agents electronic frontier foundation maintains starttls everywhere list similarly https everywhere list allows relying parties discover others supporting secure communication without prior communication newer 2018 called smtp mta strict transport security mta-sts aims addresses problem active adversary defining protocol mail servers declare ability use secure channels specific files server specific dns txt records relying party would regularly check existence record cache amount time specified record never communicate insecure channels record expires note mta-sts records apply smtp traffic mail servers communications end client mail server protected http strict transport security https april 2019 google mail announced support mta-sts number protocols allows secure delivery messages fail due misconfigurations deliberate active interference leading undelivered messages delivery unencrypted unauthenticated channels smtp tls reporting describes reporting mechanism format sharing statistics specific information potential failures recipient domains recipient domains use information detect potential attacks diagnose unintentional misconfigurations april 2019 google mail announced support smtp tls reporting original design smtp facility authenticate senders check servers authorized send behalf result email spoofing possible commonly used email spam phishing occasional proposals made modify smtp extensively replace completely one example internet mail 2000 neither made much headway face network effect huge installed base classic smtp instead mail servers use range techniques including domainkeys identified mail sender policy framework dmarc dnsbls greylisting reject quarantine suspicious emails
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Internet protocols
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windows preinstallation environment windows preinstallation environment also known windows pe winpe lightweight version windows used deployment pcs workstations servers troubleshooting operating system offline intended replace ms-dos boot disks booted via usb flash drive pxe ipxe cd-rom hard disk traditionally used large corporations oems preinstall windows client operating systems pcs manufacturing widely available free charge via windows automated installation kit waik winpe originally intended used pre-installation platform deploying microsoft windows operating systems specifically replace dos respect winpe following uses package used developer testing recovery cd/dvd system administrators many customized winpe boot cds packaged third-party applications different uses available volunteers via internet package also used base forensics investigation either capture disk image run analysis tools without mounting available disks thus changing state version 2.0 introduced number improvements extended availability winpe customers corporate enterprise customers downloading installing microsoft windows automated installation kit waik originally designed built small team engineers microsoft windows deployment team including vijay jayaseelan ryan burkhardt richard bond following versions known exist windows recovery environment winre set tools based windows pe help diagnose recover serious errors may preventing windows booting successfully windows installed along windows vista later may booted hard disks optical media operating system installation disc pxe e.g windows deployment services copy windows included installation media aforementioned operating systems successor recovery console windows features include starting windows server 2012 following additional options added windows 10 adds following volumes encrypted bitlocker mounted recovery key available windows recovery environment also installed hard drive partition oems customized additional tools separate system recovery tool restoring computer back original state windows vista sp1 users create bootable cd containing recovery environment microsoft diagnostics recovery toolset dart sold part microsoft desktop optimization pack yet another toolset based windows pe performs diagnostic recovery offline copy windows manage files edit windows registry uninstall previously installed windows updates scan system malware restore deleted files
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Operating systems
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processor register computer architecture processor register quickly accessible location available computer central processing unit cpu registers usually consist small amount fast storage although registers specific hardware functions may read-only write-only registers typically addressed mechanisms main memory may cases assigned memory address e.g dec pdp-10 ict 1900 almost computers whether load/store architecture load data larger memory registers used arithmetic operations manipulated tested machine instructions manipulated data often stored back main memory either instruction subsequent one modern processors use either static dynamic ram main memory latter usually accessed via one cache levels processor registers normally top memory hierarchy provide fastest way access data term normally refers group registers directly encoded part instruction defined instruction set however modern high-performance cpus often duplicates architectural registers order improve performance via register renaming allowing parallel speculative execution modern x86 design acquired techniques around 1995 releases pentium pro cyrix 6x86 nx586 amd k5 common property computer programs locality reference refers accessing values repeatedly holding frequently used values registers improve performance makes fast registers caches meaningful allocating frequently used variables registers critical program performance register allocation performed either compiler code generation phase manually assembly language programmer registers normally measured number bits hold example 8-bit register 32-bit register 64-bit register even instruction sets registers operate various modes breaking storage memory smaller ones 32-bit four 8-bit one instance multiple data vector one dimensional array data loaded operated upon time typically implemented adding extra registers map memory bigger one processors ability execute single instruction multiple data called vector processors processor often contains several kinds registers classified according content instructions operate hardware registers similar occur outside cpus architectures sparc mips first last register integer register file pseudo-register way hardwired always return zero read mostly simplify indexing modes overwritten alpha also done floating-point register file result register files commonly quoted one register many actually usable example 32 registers quoted 31 fit within definition register following table shows number registers several mainstream cpu architectures note x86-compatible processors stack pointer esp counted integer register even though limited number instructions may used operate contents similar caveats apply architectures although listed architectures different almost basic arrangement known von neumann architecture first proposed hungarian-american mathematician john von neumann also noteworthy number registers gpus much higher cpus number registers available processor operations performed using registers significant impact efficiency code generated optimizing compilers strahler number expression tree gives minimum number registers required evaluate expression tree
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Computer architecture
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list typefaces included macos list fonts contains every font shipped mac os x 10.0 macos 10.14 including shipped language-specific updates apple primarily korean chinese fonts fonts shipped mac os x 10.5 please see apple documentation following system fonts added yosemite least following system fonts added el capitan least following system fonts added sierra high sierra added several system fonts additional weights existing system fonts new fonts provided mojave number fonts also provided imovie ilife idvd apple applications hidden folders sole use applications reason fonts hidden unknown licensing issues suggested cause however may easily installed use applications copying library directories installing third-party font notable hidden fonts macos include bank gothic bodoni century gothic century schoolbook garamond several cuts lucida monotype twentieth century
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Operating systems
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qualcomm snapdragon snapdragon suite system chip soc semiconductor products mobile devices designed marketed qualcomm technologies inc snapdragon central processing unit cpu uses arm risc instruction set single soc may include multiple cpu cores adreno graphics processing unit gpu snapdragon wireless modem hexagon digital signal processor dsp qualcomm spectra image signal processor isp software hardware support smartphone global positioning system gps camera video audio gesture recognition ai acceleration snapdragon semiconductors embedded devices various systems including android windows phone netbooks also used cars wearable devices devices addition processors snapdragon line includes modems wi-fi chips mobile charging products first snapdragon product made available consumer device manufacturers qsd8250 released december 2007 included first 1 ghz processor mobile phones qualcomm introduced krait microarchitecture second generation snapdragon socs 2011 allowing processor core adjust speed based device needs 2013 consumer electronics show qualcomm introduced first snapdragon 800 series renamed prior models 200 400 600 series several new iterations introduced since snapdragon 805 810 615 410 qualcomm re-branded modem products snapdragon name december 2014. asus hp lenovo begun selling laptops snapdragon-based cpus running windows 10 name always connected pcs marking entry pc market qualcomm arm architecture qualcomm announced developing scorpion central processing unit cpu november 2007 snapdragon system chip soc announced november 2006 included scorpion processor well semiconductors also included qualcomm first custom hexagon digital signal processor dsp according qualcomm spokesperson named snapdragon snap dragon sounded fast fierce following month qualcomm acquired airgo networks undisclosed amount said airgo 802.11a/b/g 802.11n wi-fi technology would integrated snapdragon product suite early versions scorpion processor core design similar cortex-a8 first snapdragon shipments qsd8250 november 2007 according cnet snapdragon claim fame first 1 ghz mobile processor smartphones time using 500 mhz processors first generation snapdragon products supported 720p resolution 3d graphics 12-megapixel camera november 2008 15 device manufacturers decided embed snapdragon semiconductors consumer electronics products november 2008 qualcomm announced would also compete intel netbook processor market dual-core snapdragon system-on-chips planned late 2009 demonstrated snapdragon processor consumed less power intel chips announced around time claimed would also cost less released month qualcomm introduced snapdragon-based prototype netbook called kayak used 1.5 ghz processors intended developing markets may 2009 java se ported optimized snapdragon november 2009 computex taipei show qualcomm announced qsd8650a addition snapdragon product suite based 45 nanometer manufacturing processes featured 1.2 ghz processor lower power consumption prior models late 2009 smartphone manufacturers announced would using snapdragon socs acer liquid metal htc hd2 toshiba tg01 sony ericsson xperia x10 lenovo announced first netbook product using snapdragon socs december according pc world mobile devices using snapdragon better battery life smaller size using socs june 2010 snapdragon chips embedded 20 available consumer devices incorporated 120 product designs development apple dominant market position smartphones time incorporate snapdragon products success snapdragon therefore relied competing android phones google nexus one htc incredible challenging apple market position android devices end taking market share iphone predominantly used snapdragon unconfirmed widely circulated report speculating apple going start using snapdragon socs verizon-based iphones 2012 apple still using ax semiconductor designs support windows phone 7 operating systems added snapdragon october 2010 2011 snapdragon embedded hewlett packard webos devices 50 market share 7.9 billion smartphone processor market 2012 snapdragon s4 krait core taken dominant share android system-on-chips like nvidia tegra texas instruments omap caused latter exit market july 2014 market share android phones grown 84.6 percent qualcomm snapdragon chips embedded 41 smartphones however september 2013 debut apple 64-bit a7 chip iphone 5s forced qualcomm release competing 64-bit product despite capable performance snapdragon 800/801/805 since existing krait cores 32-bit first 64-bit socs snapdragon 808 810 rushed market using generic cortex-a57 cortex-a53 cores suffered overheating problems throttling particularly 810 led samsung stop using snapdragon galaxy s6 flagship phone galaxy note 5 phablet snapdragon chips also used android-based smartwatches snapdragon products also used virtual reality products vehicles like maserati quattroporte cadillac xts applications june 2010 qualcomm began sampling third generation snapdragon products two dual-core 1.2 ghz system chips soc called mobile station modem msm 8260 8660 8260 gsm umts hspa+ networks 8660 cdma2000 evdo networks november qualcomm announced msm8960 lte networks early 2011 qualcomm announced new processor architecture called krait used arm v7 instruction set based qualcomm processor design processors called s4 feature named asynchronous symmetrical multi-processing asmp meaning processor core adjusted clock speed voltage based device activity order optimize battery usage prior models renamed s1 s2 s3 distinguish generation s4-based generation snapdragon socs began shipping product manufacturers msm8960 february 2012 benchmark tests anandtech msm8960 better performance processor tested overall system benchmark 8960 obtained score 907 compared 528 658 galaxy nexus htc rezound respectively quadrant benchmark test assesses raw processing power dual-core krait processor score 4,952 whereas quad-core tegra 3 4,000 quad-core version apq8064 made available july 2012 first snapdragon soc use qualcomm adreno 320 graphics processing unit gpu adoption snapdragon contributed qualcomm transition wireless modem company one also produces wider range hardware software mobile devices july 2011 qualcomm acquired certain assets gesturetek order incorporate gesture recognition intellectual property snapdragon socs mid-2012 qualcomm announced snapdragon software development kit sdk android devices uplinq developer conference sdk includes tools facial recognition gesture recognition noise cancellation audio recording november qualcomm acquired assets epos development order integrate stylus gesture recognition technology snapdragon products also collaborated microsoft optimize windows phone 8 snapdragon semiconductors 2012 snapdragon s4 krait core taken dominant share android system-on-chips like nvidia tegra texas instruments omap caused latter exit market july 2014 market share android phones grown 84.6 percent qualcomm snapdragon chips powered 41 smartphones however september 2013 debut apple 64-bit a7 chip iphone 5s forced qualcomm rush competing 64-bit solution despite capable performance snapdragon 800/801/805 since existing krait cores 32-bit first 64-bit socs snapdragon 808 810 rushed market using generic cortex-a57 cortex-a53 cores suffered overheating problems throttling particularly 810 led samsung ditching snapdragon galaxy s6 flagship phone entry-level 200 series expanded six new processors using 28 nanometer manufacturing dual quad-core options june 2013 entry-level snapdragon 210 intended low-cost phones announced september 2014 qualcomm first attempt 64-bit system chip created new in-house architecture later models showed better thermal performance especially compared snapdragon models launched 2015 like snapdragon 820 early 2016 qualcomm launched snapdragon 820 arm 64-bit quad-core processor using in-house designed kryo cores qualcomm launched updated snapdragon 821 later year higher clock speeds slightly better performance snapdragon 820 family uses samsung 14-nanometer finfet process qualcomm also released qualcomm snapdragon neural processing engine sdk first ai acceleration smartphones qualcomm announced octa-core snapdragon 835 soc november 17 2016 released following year used kryo 280 cores built using samsung 10-nanometer finfet process initial launch due samsung role manufacturing chip mobile division also acquired initial inventory chip means phone maker able manufacture products containing snapdragon 835 samsung released flagship device year galaxy s8 computex 2017 may qualcomm microsoft announced plans launch snapdragon-based laptops running windows 10 partnered hp lenovo asus release slim portables 2-in-1 devices powered snapdragon 835 december 2017 qualcomm announced octa-core snapdragon 845 uses 10-nanometer manufacturing process earlier snapdragon 835 introduced new processor architecture kryo 385 designed better battery life photography use artificial intelligence apps early 2018 qualcomm introduced 7 series sits 6 8 series terms pricing performance 700 launched octa-core models snapdragon 710 712 using kryo 360 processor architecture built 10-nanometer manufacturing process following year 2019 qualcomm released new variants mobile processors snapdragon 855 replacing 845 snapdragon 855 competes high end system chip solutions like apple a12 kirin 980 snapdragon 855 features kryo 485 cores built tsmc 7-nanometer process along snapdragon 730 730g replacing 710 712 newer 730 730g feature kryo 460 cores built samsung 8-nanometer process snapdragon system chip products typically include graphics processing unit gpu global positioning system gps cellular modem integrated single package software included operates graphics video picture-taking 19 different snapdragon processors 400 600 800 product families spanning low high-end respectively well wi-fi mobile charging products components include adreno graphics processing qualcomm hexagon dsp processors using qualcomm s4 processor architecture addition smartphones 400 series used smart watches 602a intended electronics cars current snapdragon naming scheme implemented snapdragon 800 family announced 2013 consumer electronics show prior models renamed 200 400 600 series new snapdragon 600 also released mid-year embedded new android devices 400 family entry-level 600 mass-market mid-range 800 family high-end flagship phones snapdragon 805 released november 410 intended low-cost phones developing nations announced following month january 2014 qualcomm introduced modified version snapdragon 600 called 602a intended in-car infotainment screens backup cameras driver assistance products quad-core snapdragon 610 eight-core 615 announced february 2014 snapdragon 808 810 announced april 2014 snapdragon 835 announced november 2017 first qualcomm soc built 10 nm architecture qualcomm new flagship chip 2018 845 announced december 2017 according qualcomm 845 25-30 faster 835 february 2015 qualcomm re-branded stand-alone modem products snapdragon name distinguished socs using x designation x7 x12 modem first snapdragon modem 5g networks x50 announced late 2016 followed 2gbs x24 modem 7 nanometer manufacturing process announced february 2018 according cnet phones growing us market share ranked highly cnet reviews due responsiveness snapdragon socs also used windows phones phones entering market mid-2013 lg g2 first phone market using snapdragon 800 august 2013 2017 660 630 replaced 653 626 mid-range models several chips 400 product family revved february 2017 qualcomm introduced snapdragon x20 intended 5g cell phone networks two new chips 802.11ax commercial wi-fi networks followed addition 636 600 product family october qualcomm said would 40 percent faster 630 august 2018 snapdragon 632 439 429 released new soc aimed mid-range devices moto g6 play huawei honor 7a nokia 5 december 2018 qualcomm announced 8cx snapdragon tech summit 2018 8cx qualcomm first soc specifically designed always connected pc acpc platform unlike qualcomm past acpc socs respective mobile socs higher tdp qualcomm also showcased snapdragon x50 5g modem snapdragon 855 qtm052 mmwave antenna module february 2019 qualcomm announced snapdragon x55 5g modem qtm525 mmwave antenna module qet6100 envelope tracker new qat3555 antenna impedance tuner benchmark tests snapdragon 800 processor pc magazine found processing power comparable similar products nvidia benchmarks snapdragon 805 found adreno 420 gpu resulted 40 percent improvement graphics processing adreno 330 snapdragon 800 though slight differences processor benchmarks benchmarks snapdragon 801 inside htc one found bump around benchmark improvements 800 2015 samsung decision use snapdragon 810 galaxy s6 significant detrimental impact snapdragon revenues reputation benchmark tests ars technica confirmed rumors 810 under-performed lower-end models overheating issues qualcomm spokesperson said tests done early versions 810 n't ready commercial use updated version released found moderately improve thermal throttling gpu clock speeds memory latency memory bandwidth tested commercial product xiaomi mi note pro additionally 820/821 835 845 performed substantially better qualcomm led industry sustained gpu performance perf/w release 820 release apple a12
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Computer architecture
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partial application computer science partial application partial function application refers process fixing number arguments function producing another function smaller arity given function formula_1 might fix 'bind first argument producing function type formula_2 evaluation function might represented formula_3 note result partial function application case function takes two arguments partial application sometimes incorrectly called currying related distinct concept intuitively partial function application says fix first arguments function get function remaining arguments example function div x x div parameter x fixed 1 another function div div 1 1/y function inv returns multiplicative inverse argument defined inv 1/ practical motivation partial application often functions obtained supplying arguments function useful example many languages function operator similar codice_1 partial application makes easy define functions example creating function represents addition operator 1 bound first argument languages ml haskell functions defined curried form default supplying fewer total number arguments referred partial application languages first-class functions one define codice_2 codice_3 codice_4 perform currying partial application explicitly might incur greater run-time overhead due creation additional closures haskell use efficient techniques scala implements optional partial application placeholder e.g returns incrementing function scala also support multiple parameter lists currying e.g clojure implements partial application using codice_5 function defined core library c++ standard library provides codice_6 return function object result partial application given arguments given function java codice_7 partially applies function first argument perl 6 codice_8 method creates new function fewer parameters python standard library module codice_9 includes codice_5 function allowing positional named argument bindings returning new function xquery argument placeholder codice_11 used non-fixed argument partial function application simply-typed lambda calculus function product types λ partial application currying uncurrying defined note codice_2 codice_4 codice_2
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Programming language topics
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ampl mathematical programming language ampl algebraic modeling language describe solve high-complexity problems large-scale mathematical computing i.e. large-scale optimization scheduling-type problems developed robert fourer david gay brian kernighan bell laboratories ampl supports dozens solvers open source commercial software including cbc cplex fortmp gurobi minos ipopt snopt knitro lgo problems passed solvers nl files ampl used 100 corporate clients government agencies academic institutions one advantage ampl similarity syntax mathematical notation optimization problems allows concise readable definition problems domain optimization many modern solvers available neos server formerly hosted argonne national laboratory currently hosted university wisconsin madison accept ampl input according neos statistics ampl popular format representing mathematical programming problems ampl features mix declarative imperative programming styles formulating optimization models occurs via declarative language elements sets scalar multidimensional parameters decision variables objectives constraints allow concise description problems domain mathematical optimization procedures control flow statements available ampl support re-use simplify construction large-scale optimization problems ampl allows separation model data ampl supports wide range problem types among ampl invokes solver separate process advantages interaction solver done well-defined nl interface ampl available many popular 32- 64-bit operating systems including linux mac os x unix windows translator proprietary software maintained ampl optimization llc however several online services exist providing free modeling solving facilities using ampl free student version limited functionality free full-featured version academic courses also available ampl used within microsoft excel via solverstudio excel add-in ampl solver library asl allows reading nl files provides automatic differentiation open-source used many solvers implement ampl connection table present significant steps ampl history transportation problem george dantzig used provide sample ampl model problem finds least cost shipping schedule meets requirements markets supplies factories partial list solvers supported ampl
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Programming language topics
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service-oriented middleware service-oriented middleware som aids distributed object middleware dom systems concept services service context number objects behavior objects use predefined interface make service available systems/services som defines communication protocols services provides location- migration-transparent access services thus supporting simple integration services beyond platform boundaries one example som sun oracle jini system called apache river project architectures belonging field web services also belong category middleware
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Distributed computing architecture
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quarth besides arcade version also ports game msx2 built-in scc chip famicom game boy—home releases used quarth name worldwide exception game boy color release europe konami gb collection vol 2 game renamed generic title block game unknown reasons quarth released konami net i-mode service block quarth updated block quarth dx 2001 released without dx suffix 2005 made globally available konami net licensing many i-mode services offered mobile operators europe example available o2 uk o2 ireland telefónica spain 2005 konami also included game nintendo ds title emulated version game released 2006 playstation 2 japan part oretachi geasen zoku sono -series quarth combination tetris -style gameplay fixed shooter space invaders tradition player focus falling blocks action geometrical rather arranging blocks together make row disappearing blocks spaceship positioned bottom screen shoots blocks upwards make falling block pattern squares rectangles blocks arranged properly shape destroyed player awarded points based shape size blocks continue drop top screen various incomplete shapes level progresses blocks drop greater speed frequency also various power-ups could located increase ship speed among bonuses game continues blocks reach dotted line bottom screen whereupon player ship quarthed crushed flat like arcade games game featured multi-player mode arcade demonstrated via split screen player 1 left player 2 right game boy multiplayer required game boy link cable player able view fields game boys msx2 famicom versions two different 2-player modes mode players worked together game mode b arcade split-screen game generally acclaimed many online reviewers though nintendo life gave 6/10
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Computer architecture
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parse thicket parse thicket graph represents syntactic structure paragraph text natural language processing parse thicket includes parse tree sentence paragraph plus arcs relations words syntactic parse thickets constructed constituency parse trees dependency parse trees relations link parse trees within parse thicket assess similarity texts question candidate answers parse thickets generalized image parse thicket coreferences entity-entity links shown solid red rhetoric/speech act relations shown dotted red etap parser tree visualization software used compute generalization two parse thickets one needs find maximum common sub-graph sub-thicket
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Computational linguistics
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abnormal end abend also ab normal end abend abnormal termination software program crash usage derives error message ibm os/360 ibm zos operating systems usually capitalized may appear abend common abend 0c7 data exception abend 0cb division zero abends could soft allowing automatic recovery hard terminating activity errors crashes novell netware network operating system usually called abends communities netware administrators sprung around internet abend.org term jocularly claimed derived german word abend meaning evening
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Operating systems
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vm2000 vm 2000 hypervisor fujitsu formerly siemens nixdorf informationssysteme designed specifically use bs2000 operating system ebcdic-based operating system allows multiple images bs2000 linux operate s-series computer based ibm system/390 architecture also supports bs2000 linux microsoft windows x86-based sq-series mainframes additionally virtualize bs2000 guests sr- sx-series mainframes based mips sparc respectively
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Computer architecture
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application binary interface computer software application binary interface abi interface two binary program modules often one modules library operating system facility program run user abi defines data structures computational routines accessed machine code low-level hardware-dependent format contrast api defines access source code relatively high-level hardware-independent often human-readable format common aspect abi calling convention determines data provided input read output computational routines examples x86 calling conventions adhering abi may may officially standardized usually job compiler operating system library author however application programmer may deal abi directly writing program mix programming languages achieved using foreign function calls abis cover details complete abi intel binary compatibility standard ibcs allows program one operating system supporting abi run without modifications system provided necessary shared libraries present similar prerequisites fulfilled abis standardize details c++ name mangling exception propagation calling convention compilers platform require cross-platform compatibility embedded-application binary interface eabi specifies standard conventions file formats data types register usage stack frame organization function parameter passing embedded software program use embedded operating system compilers support eabi create object code compatible code generated compilers allowing developers link libraries generated one compiler object code generated another compiler developers writing assembly language code may also interface assembly generated compliant compiler eabis designed optimize performance within limited resources embedded system therefore eabis omit abstractions made kernel user code complex operating systems example dynamic linking avoided allow smaller executables faster loading fixed register usage allows compact stacks kernel calls running application privileged mode allows direct access custom hardware operation without indirection calling device driver widely used eabis include powerpc arm eabi2 mips eabi
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Operating systems
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dasient dasient internet security company headquartered sunnyvale california founded 2008 launched first product june 2009 dasient acquired twitter january 2012 dasient provides cloud-based anti-malware services protecting businesses web-based malware malvertising dasient web malware analysis platform uses dynamic behavioral-based engine based sophisticated algorithms anomaly detection technology defend latest attacks using up-to-date intelligence malware platform includes system highly instrumented virtual machines simulate actual users would experience visiting particular web page viewing specific online ad company founded former google personnel neil daswani shariq rizvi former mckinsey strategy consultant ameet ranadive dasient named network world one ten startups watch 2010 company received seed funding mike maples ex-verisign ceo stratton sclavos ex-3com/palm chairman eric benhamou february 2011 announced google ventures invested dasient dasient acquired twitter january 2012
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Computer security
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android beam android beam feature android mobile operating system allows data transferred via near field communication nfc allows rapid short-range exchange web bookmarks contact info directions youtube videos data android beam introduced 2011 android version 4.0 ice cream sandwich improved google acquired bump 2017 computerworld included android beam list once-trumpeted features quietly faded away observing despite admirable marketing effort beam never quite worked particularly well numerous systems sharing stuff proved simpler reliable android beam discontinued android q present second android q beta google pixel 3 android beam activated placing devices back back content shared displayed screen content able sent screen shrink display tap beam top tapping screen sends content one device sound play devices near able beam data sent confirmation tone play negative tone play failed content shrink screen indicating beaming complete sharing one direction device sending content get content receiving device activate android beam devices must support nfc near field communication enabled addition passing lock-screen logging android 4.1 jelly bean devices use android beam send photos videos bluetooth android beam uses nfc enable bluetooth devices instantly pair disable bluetooth complete automatically devices works android devices version 4.1 beaming specific content app allowed control content sent adding android beam support app specify data beaming app open receiving device receiving device app open application page play store beam refers extension android beam samsung first used galaxy iii phones uses near-field communication establish wi-fi direct connection two devices data transfer instead bluetooth connection results faster transfer speeds devices feature beam beam limited devices beam support wi-fi direct nfc htc one samsung galaxy iii external links google play story nfc basics
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Operating systems
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ssh communications security ssh communications security oyj cybersecurity company focusing encryption access control according company products secure privileged access management credentials ssh keys server passwords data-in-transit focus particularly ssh key management one products company privx on-demand access manager aimed securing machine-to-machine communication large organizations replacing permanent access keys customers include many major financial institutions retailers technology companies company founded 1995 tatu ylönen designed first version secure shell ssh protocol software parts still today included openssh continues work company full-time current ceo kaisa olkkonen company listed nasdaq nordic since 2000
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Computer security
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bup bup backup system written python uses several formats git capable handling large files like operating system images block-based deduplication optional par2-based error correction bup development began 2010 accepted debian year bup uses git packfile format writing packfiles directly avoiding garbage collection bup available source notably part following distributions
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Computer security
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domain-specific language domain-specific language dsl computer language specialized particular application domain contrast general-purpose language gpl broadly applicable across domains wide variety dsls ranging widely used languages common domains html web pages languages used one pieces software mush soft code dsls subdivided kind language include domain-specific markup languages domain-specific modeling languages generally specification languages domain-specific programming languages special-purpose computer languages always existed computer age term domain-specific language become popular due rise domain-specific modeling simpler dsls particularly ones used single application sometimes informally called mini-languages line general-purpose languages domain-specific languages always sharp language may specialized features particular domain applicable broadly conversely may principle capable broad application practice used primarily specific domain example perl originally developed text-processing glue language domain awk shell scripts mostly used general-purpose programming language later contrast postscript turing complete language principle used task practice narrowly used page description language design use appropriate dsls key part domain engineering using language suitable domain hand – may consist using existing dsl gpl developing new dsl language-oriented programming considers creation special-purpose languages expressing problems standard part problem-solving process creating domain-specific language software support rather reusing existing language worthwhile language allows particular type problem solution expressed clearly existing language would allow type problem question reappears sufficiently often pragmatically dsl may specialized particular problem domain particular problem representation technique particular solution technique aspects domain domain-specific language created specifically solve problems particular domain intended able solve problems outside although may technically possible contrast general-purpose languages created solve problems many domains domain also business area examples business areas include domain-specific language somewhere tiny programming language scripting language often used way analogous programming library boundaries concepts quite blurry much like boundary scripting languages general-purpose languages domain-specific languages languages often declared syntaxes grammars specific goals design implementation domain-specific language one visual diagramming language created generic eclipse modeling system programmatic abstractions eclipse modeling framework textual languages instance command line utility grep regular expression syntax matches patterns lines text sed utility defines syntax matching replacing regular expressions often tiny languages used together inside shell perform complex programming tasks line domain-specific languages scripting languages somewhat blurred domain-specific languages often lack low-level functions filesystem access interprocess control functions characterize full-featured programming languages scripting otherwise many domain-specific languages compile byte-code executable code various kinds media objects graphviz exports postscript gif jpeg etc. csound compiles audio files ray-tracing domain-specific language like pov compiles graphics files computer language like sql presents interesting case deemed domain-specific language specific specific domain sql case accessing managing relational databases often called another application sql keywords functions many scripting languages often thought language right perhaps prevalence database manipulation programming amount mastery required expert language blurring line many domain-specific languages exposed apis accessed programming languages without breaking flow execution calling separate process thus operate programming libraries domain-specific languages expand time include full-featured programming tools complicates question whether language domain-specific good example functional language xslt specifically designed transforming one xml graph another extended since inception allow particularly 2.0 version various forms filesystem interaction string date manipulation data typing model-driven engineering many examples domain-specific languages may found like ocl language decorating models assertions qvt domain-specific transformation language however languages like uml typically general-purpose modeling languages summarize analogy might useful little language like knife used thousands different ways cutting food cutting trees domain-specific language like electric drill powerful tool wide variety uses specific context namely putting holes things general purpose language complete workbench variety tools intended performing variety tasks domain-specific languages used programmers looking current workbench realize need better drill find particular domain-specific language provides exactly dsls implemented via independent interpreter compiler known external domain specific languages well known examples include latex awk separate category known embedded internal domain specific languages typically implemented within host language library tend limited syntax host language though depends host language capabilities several usage patterns domain-specific languages many domain-specific languages used one way dsl code embedded host language may special syntax support regexes sed awk perl javascript may passed strings adopting domain-specific language approach software engineering involves risks opportunities well-designed domain-specific language manages find proper balance domain-specific languages important design goals contrast general-purpose languages programming idioms methods imposed programmers handle common development tasks e.g general purpose programming languages rarely support idioms domain-specific languages describe e.g examples domain-specific languages include html logo pencil-like drawing verilog vhdl hardware description languages matlab gnu octave matrix programming mathematica maple maxima symbolic mathematics specification description language reactive distributed systems spreadsheet formulas macros sql relational database queries yacc grammars creating parsers regular expressions specifying lexers generic eclipse modeling system creating diagramming languages csound sound music synthesis input languages graphviz grgen software packages used graph layout graph rewriting gml scripting language used gamemaker studio domain-specific language targeted novice programmers easily able learn programming language serves blend multiple languages including delphi c++ basic lack structures data types features full-fledged programming language many built-in functions sandboxed purpose easy portability language primarily serves make easy anyone pick language develop game unix shell scripts give good example domain-specific language data organization manipulate data files user input many different ways domain abstractions notations include streams stdin stdout operations streams redirection pipe abstractions combine make robust language describe flow organization data language consists simple interface script running controlling processes perform small tasks tasks represent idioms organizing data desired format tables graphs charts etc tasks consist simple control-flow string manipulation mechanisms cover lot common usages like searching replacing string files counting occurrences strings frequency counting even though unix scripting languages turing complete differ general purpose languages practice scripting languages used weave together small unix tools grep ls sort wc coldfusion associated scripting language another example domain-specific language data-driven websites scripting language used weave together languages services java .net c++ sms email email servers http ftp exchange directory services file systems use websites coldfusion markup language cfml includes set tags used coldfusion pages interact data sources manipulate data display output cfml tag syntax similar html element syntax erlang open telecom platform originally designed use inside ericsson domain-specific language language offers platform libraries create finite state machines generic servers event managers quickly allow engineer deploy applications support libraries shown industry benchmarks outperform languages intended mixed set domains c c++ language officially open source downloaded website filtermeister programming environment programming language based c specific purpose creating photoshop-compatible image processing filter plug-ins filtermeister runs photoshop plug-in load execute scripts compile export independent plug-ins although filtermeister language reproduces significant portion c language function library contains features used within context photoshop plug-ins adds number specific features useful specific domain template feature mediawiki embedded domain-specific language whose fundamental purpose support creation inclusion reference mediawiki pages mediawiki pages much interest domain-specific languages improve productivity quality software engineering domain-specific language could possibly provide robust set tools efficient software engineering tools beginning make way development critical software systems software cost reduction toolkit example toolkit suite utilities including specification editor create requirements specification dependency graph browser display variable dependencies consistency checker catch missing cases well-formed formulas specification model checker theorem prover check program properties specification invariant generator automatically constructs invariants based requirements newer development language-oriented programming integrated software engineering methodology based mainly creating optimizing using domain-specific languages complementing language-oriented programming well forms domain-specific languages class compiler writing tools called metacompilers metacompiler useful generating parsers code generators domain-specific languages metacompiler compiles domain-specific metalanguage specifically designed domain metaprogramming besides parsing domain-specific languages metacompilers useful generating wide range software engineering analysis tools meta-compiler methodology often found program transformation systems metacompilers played significant role computer science computer industry include meta-ii descendant treemeta unreal unreal tournament unveiled language called unrealscript allowed rapid development modifications compared competitor quake using id tech 2 engine id tech engine used standard c code meaning c learned properly applied unrealscript optimized ease use efficiency similarly development recent games introduced specific languages one common example lua scripting various business rules engines developed automating policy business rules used government private industry ilog oracle policy automation dtrules drools others provide support dsls aimed support various problem domains dtrules goes far define interface use multiple dsls within rule set purpose business rules engines define representation business logic human-readable fashion possible allows subject matter experts developers work understand representation business logic rules engines provide approach simplifying control structures business logic example using declarative rules decision tables coupled alternatives programming syntax favor dsls statistical modelers developed domain-specific languages bugs jags stan languages provide syntax describing bayesian model generate method solving using simulation generate object handling services based interface description language domain-specific language javascript web applications html documentation c++ high-performance code etc done cross-language frameworks apache thrift google protocol buffers gherkin language designed define test cases check behavior software without specifying behavior implemented meant read used non-technical users using natural language syntax line-oriented design tests defined gherkin must implemented general programming language steps gherkin program acts syntax method invocation accessible non-developers prominent examples domain-specific languages include advantages disadvantages
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Programming language topics
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junos os junos os formally juniper network operating system freebsd-based operating system used juniper networks hardware routers operating system used juniper routing switching security devices juniper offers software development kit sdk partners customers allow additional customization biggest competitor junos cisco systems ios junos os formerly branded juniper junos commonly referred simply junos though general brand name juniper networks including product lines junos fusion key benefits junos os include junos provides single code base across juniper platforms juniper issued new release junos every 90 days since 1998 junos supports variety routing protocols introduction srx j-series past version 9.3 platforms also supports flow mode includes stateful firewalling nat ipsec flexible routing policy language used controlling route advertisements path selection junos generally adheres industry standards routing mpls operating system supports high availability mechanisms standard unix graceful restart junos operating system primarily based linux freebsd linux running bare metal freebsd running qemu virtual machine freebsd unix implementation customers access unix shell execute normal unix commands junos runs juniper hardware systems juniper acquired netscreen integrated screenos security functions junos network operating system junos cli text-based command interface configuring troubleshooting monitoring juniper device network traffic associated supports two types command modes functions operational mode include control cli environment monitoring hardware status display information network data passes though hardware configuration mode used configuring juniper router switch security device adding deleting modifying statements configuration hierarchy juniper developer network jdn juniper networks provides junos sdk customers 3rd-party developers want develop applications junos-powered devices juniper networks routers switches service gateway systems provides set tools application programming interfaces apis including interfaces junos routing firewall filter ui traffic services functions juniper networks also employs junos sdk internally develop parts junos many junos applications openflow junos traffic services 2016 juniper maintains market share ethernet switching 16.9 market share enterprise routing 16.1 juniper generated 2,353 million revenue routing 858 million switching 318 million security 2016 juniper revenue stems americas 2,969 million europe middle east africa 1,238 million asia 783 million combining rest annual revenue 2016
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Operating systems
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efm32 efm32 gecko mcus family energy-friendly mixed-signal 32-bit microcontroller integrated circuits energy micro silicon labs based arm cortex-m cpus including cortex-m0+ cortex-m3 cortex-m4 efm32 microcontrollers majority functionality available deep sleep modes sub-microamp current consumption enabling energy efficient autonomous behavior cpu sleeping efm32 combines quick wakeups efficient processing reduce impact cpu code needs executed good example deep sleep peripheral efm32 low energy sensor interface lesense capable duty-cycling inductive capacitive resistive sensors autonomously operating deep sleep mode another important aspect gecko mcus peripherals direct connection allowing communicate without cpu wake intervention interconnect known peripheral reflex system prs significant functionality available lower stop shutoff energy modes stop mode includes analog comparators watchdog timers pulse counters ic links external interrupts shutoff mode 20–100 na current consumption depending product applications access gpio reset real-time counter rtc retention memory efm32 family consists number sub-families ranging efm32 zero gecko based arm cortex-m0+ higher performing efm32 giant gecko wonder gecko based cortex-m3 cortex-m4 respectively efm32 technology also foundation efr32 wireless geckos portfolio sub-ghz 2.4 ghz wireless system chip soc devices product families important advantage efm32 mcu portfolio energy efficiency energy efficiency stems autonomous operations deep sleep modes low active sleep currents fast wakeup times together characteristics reduce integrated energy power time lifetime application efm32 devices also constructed reduce development cycles variety products smart metering industrial applications pin/software compatible scalable across wide application requirements compatible multiple development platforms additionally mcu architecture common fundamental piece wireless gecko portfolio efr32 software hardware pin/package compatibility efm32 products offer simplified pathway wireless applications efm32 mcu family critical features useful iot applications major architectural features low-energy modes design peripheral reflex system prs gives developers peripheral interconnect system eight triggers handle task execution without cpu intervention low level mcu broken eight categories core memory clock management energy management serial interfaces i/o ports timers triggers analog interfaces security modules terms core cpu efm32 mcus integrate arm cortex-m series technology spanning cortex-m0+ cortex-m4 enable gecko mcu operation take advantage ultralow power architecture applications operate main input clock rate 4 mhz 48 mhz reduce need external electronic components efm32 integrates low frequency ultralow frequency clocks well mcus also integrate internal voltage regulators simplified compact system designs addition cpu clock rate flexibility specific applications efm32 portfolio offers broad range memory resource options application storage flash application execution ram needs rtos implementation devices include internal flash memory low 4 kb high 1024 kb ram low 2 kb high 128 kb enable applications sense control communicate single low-power microcontroller efm32 mcus contain complete analog digital interfaces serial digital interfaces include usart low energy uart i2c usb timer triggers block mcu includes cryotimer low energy pulse counter pcnt backup real-time-counter rtc analog modules include adcs dacs operational amplifiers analog comparators applications demand heightened security protections efm32 mcus offer various hardware crypto engines cyclic redundancy check crc general i/o mcus feature 93 gpio pins several variants feature lcd controllers quickly design develop build test efm32 applications developers various resources available free integrated development environment ide performance analysis tools configuration tools utilities flexible compilers development platforms software stacks reference code design examples app notes training videos whitepapers silicon labs simplicity studio free eclipse-based development platform graphical configuration tools energy-profiling tools wireless network analysis tools demos software examples documentation technical support community forums also includes flexible compiler tool options including gcc arm keil iar embedded workbench third-party tools two popular development tools within simplicity studio ide advanced energy monitor aem network debugger called “ packet trace ” advanced energy monitor efm32 tool allows developers energy profiling application running also allows direct code correlation optimize hardware design software network debugger tool allows developers using wireless gecko mcus trace network traffic packets throughout nodes network efm32 supported multiple third-party real-time operating system rtos software libraries drivers stacks rtos solutions enabled efm32s micro-controller operating systems uc/os micrium freertos gnu chopstx embos segger mbed os arm october 2016 silicon labs acquired micrium addition iot-critical middleware stacks tcp/ip micrium provides certified commercial-grade rtos enables embedded iot designs handle task management real time important mcu applications even essential wireless applications example projects found micrium website efm32 starter kits available evaluation purposes gain familiarity portfolio starter kit contains sensors peripherals help illustrate device capabilities well serve starting point application development using simplicity studio software also grants access kit information ability program starter kit demos code examples starter kits contain eeprom board ids enable automated setup kit connected simplicity studio ide efm32 kits arm mbed-enabled kits support arm mbed right box supported simplicity studio development tools community forums featuring giant gecko mcu 1024 kb flash 93 gpio efm32 giant gecko starter kit shown one latest starter kit offerings efm32 family efm32 starter kits include efm32 designed achieve high degree autonomous operation low-energy modes multiple ultralow energy modes available turning energy usage significantly reducing power consumption achieve power energy-efficiency features efm32 products utilize ultralow active idle power fast wakeup processing times important ability intelligently interact peripherals sensors autonomously without waking cpu consuming power active run mode efm32 consumes 114 µa/mhz running real-life code 32 mhz 3v supply also mode process time matters one main benefits 32-bit mcu working power consumption however maximum clock speed silicon labs carefully designs efm32s optimize performance low power together designing maximum clock speed 48 mhz mcus faster clocks 100 mhz+ range inevitably consume power active mode beyond energy savings run mode efm32 ideal low duty cycle applications take advantage operating lower energy states lower energy states outlined section em1 sleep em2 deep sleep em3 stop em4 shutoff autonomous peripherals peripheral reflex system lesense core technologies come play lower energy modes autonomous peripheral feature ensures peripheral devices operate without waking cpu also extensive direct memory address dma support 16 channels depending efm32 peripheral reflex system boosts capability autonomous peripherals allowing flexible configuration create complex powerful interconnections bypass cpu lesense unique efm32 feature allows mcu monitor 16 sensors deep sleep mode efm32 resistive sensing capacitive sensing inductive sensing mode needed efm32 wake deep sleep engage cpu less two microseconds adc sensing applications temperature demonstration wonder gecko mcu standard temperature thermistor setting adc sample thermistor every second 1 hz rate equates 1.3 ua average current real world would equate 220 ma-hr cr2032 coin cell battery lasting close 20 years application could implemented lesense preset thresholds instead using regular time interval adc samples case lesense irregular triggers threshold trigger rate 1 hz would still produce average current 1.5 ua equates 16.85-year battery life low-energy pulse counter metrology using low energy pulse counter efm32 could also used pulsed sensing applications example magnetic hall effect sensor efm32 convert rotational position quantified speed flow rate common situation water heat flow metering efm32 used stop mode em3 count pulses calculate flow operating power consumption state could low 650 na 3vdc significant positive implications battery-operated meters efm32 microcontroller family one two products energy micro efr4d draco soc radios gecko mbed compiler available https //developer.mbed.org/compiler/ nav
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Computer architecture
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user activity monitoring field information security user activity monitoring uam monitoring recording user actions uam captures user actions including use applications windows opened system commands executed checkboxes clicked text entered/edited urls visited nearly every on-screen event protect data ensuring employees contractors staying within assigned tasks posing risk organization user activity monitoring software deliver video-like playback user activity process videos user activity logs keep step-by-step records user actions searched analyzed investigate out-of-scope activities need uam rose due increase security incidents directly indirectly involve user credentials exposing company information sensitive files 2014 761 data breaches united states resulting 83 million exposed customer employee records 76 breaches resulting weak exploited user credentials uam become significant component infrastructure main populations users uam aims mitigate risks contractors used organizations complete information technology operational tasks remote vendors access company data risks even malicious intent external user like contractor major security liability 70 regular business users admitted access data necessary generalized accounts give regular business users access classified company data makes insider threats reality business uses generalized accounts administrator accounts heavily monitored due high profile nature access however current log tools generate “ log fatigue ” admin accounts log fatigue overwhelming sensation trying handle vast amount logs account result many user actions harmful user actions easily overlooked thousands user actions compiled every day according verizon data breach incident report “ first step protecting data knowing access it. ” today ’ environment “ lack oversight control among employees access confidential sensitive information. ” apparent gap one many factors resulted major number security issues companies companies use uam usually separate necessary aspects uam three major components visual forensics involves creating visual summary potentially hazardous user activity user action logged recorded user session completed uam created written record visual record whether screen-captures video exactly user done written record differs siem logging tool captures data user-level system level –providing plain english logs rather syslogs originally created debugging purposes textual logs paired corresponding screen-captures video summaries using corresponding logs images visual forensics component uam allows organizations search exact user actions case security incident case security threat i.e data breach visual forensics used show exactly user everything leading incident visual forensics also used provide evidence law enforcement investigate intrusion user activity alerting serves purpose notifying whoever operates uam solution mishap misstep concerning company information real-time alerting enables console administrator notified moment error intrusion occurs alerts aggregated user provide user risk profile threat ranking alerting customizable based combinations users actions time location access method alerts triggered simply opening application entering certain keyword web address alerts also customized based user actions within application deleting creating user executing specific commands user behavior analytics add additional layer protection help security professionals keep eye weakest link chain monitoring user behavior help dedicated software analyzes exactly user session security professionals attach risk factor specific users and/or groups immediately alerted red flag warning high-risk user something interpreted high-risk action exporting confidential customer information performing large database queries scope role accessing resources ’ accessing forth uam collects user data recording activity every user applications web pages internal systems databases uam spans access levels access strategies rdp ssh telnet ica direct console login etc.… uam solutions pair citrix vmware environments uam solutions transcribe documented activities user activity logs uam logs match video-playbacks concurrent actions examples items logged names applications run titles pages opened urls text typed edited copied/pasted commands scripts uam uses screen-recording technology captures individual user actions video-like playback saved accompanied user activity log playbacks differ traditional video playback screen scraping compiling sequential screen shots video like replay user activity logs combined video-like playback provides searchable summary user actions enables companies read also view exactly particular user company systems companies employees raised issue user privacy aspect uam believe employees resist idea actions monitored even done security purposes reality uam strategies address concerns possible monitor every single user action purpose uam systems snoop employee browsing history uam solutions use policy-based activity recording enables console administrator program exactly ’ monitored many regulations require certain level uam others require logs activity audit purposes uam meets variety regulatory compliance requirements hipaa iso 27001 sox pci etc.… uam typically implemented purpose audits compliance serve way companies make audits easier efficient audit information request information user activity met uam unlike normal log siem tools uam help speed audit process building controls necessary navigate increasingly complex regulatory environment ability replay user actions provides support determining impact regulated information security incident response uam two deployment models appliance-based monitoring approaches use dedicated hardware conduct monitoring looking network traffic software-based monitoring approaches use software agents installed nodes accessed users commonly software requires installation agent systems servers desktops vdi servers terminal servers across users want monitor agents capture user activity reports information back central console storage analysis solutions may quickly deployed phased manner targeting high-risk users systems sensitive information first allowing organization get running quickly expand new user populations business requires
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Computer security
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shell account shell account user account remote server traditionally running unix operating system gives access shell via command-line interface protocol telnet ssh shell accounts made first accessible interested members public internet service providers netcom usa panix world digex although rare instances individuals access shell accounts employer university used file storage web space email accounts newsgroup access software development shell providers often found offer shell accounts low-cost free shell accounts generally provide users access various software services including compilers irc clients background processes ftp text editors nano email clients pine shell providers may also allow tunneling traffic bypass corporate firewalls
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Operating systems
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redox operating system redox unix-like microkernel operating system written programming language rust language strong focus safety stability high performance redox aims secure usable free redox inspired prior kernels operating systems minix plan 9 bsd similar gnu bsd ecosystem memory-safe language modern technology free open-source software distributed mit license redox operating system designed highly secure reflected several design decisions redox full-featured operating system providing packages memory allocator file system display manager core utilities etc together make functional operating system redox relies ecosystem software written rust members project redox supports command-line interface cli programs including redox supports graphical user interface gui programs including redox created jeremy soller first published 20 april 2015 github since developed actively contributions 40 developers second anniversary redox appearing github version 0.2.0 released
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Operating systems
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computer architecture computer engineering computer architecture set rules methods describe functionality organization implementation computer systems definitions architecture define describing capabilities programming model computer particular implementation definitions computer architecture involves instruction set architecture design microarchitecture design logic design implementation first documented computer architecture correspondence charles babbage ada lovelace describing analytical engine building computer z1 1936 konrad zuse described two patent applications future projects machine instructions could stored storage used data i.e stored-program concept two early important examples term “ architecture ” computer literature traced work lyle r. johnson frederick p. brooks jr. members machine organization department ibm ’ main research center 1959 johnson opportunity write proprietary research communication stretch ibm-developed supercomputer los alamos national laboratory time known los alamos scientific laboratory describe level detail discussing luxuriously embellished computer noted description formats instruction types hardware parameters speed enhancements level “ system architecture ” – term seemed useful “ machine organization. ” subsequently brooks stretch designer started chapter 2 book planning computer system project stretch ed w. buchholz 1962 writing brooks went help develop ibm system/360 called ibm zseries line computers “ architecture ” became noun defining “ user needs know ” later computer users came use term many less-explicit ways earliest computer architectures designed paper directly built final hardware form later computer architecture prototypes physically built form transistor–transistor logic ttl computer—such prototypes 6800 pa-risc—tested tweaked committing final hardware form 1990s new computer architectures typically built tested tweaked—inside computer architecture computer architecture simulator inside fpga soft microprocessor both—before committing final hardware form discipline computer architecture three main subcategories types computer architecture following types used bigger companies like intel count 1 computer architecture purpose design computer maximizes performance keeping power consumption check costs low relative amount expected performance also reliable many aspects considered includes instruction set design functional organization logic design implementation implementation involves integrated circuit design packaging power cooling optimization design requires familiarity compilers operating systems logic design packaging instruction set architecture isa interface computer software hardware also viewed programmer view machine computers understand high-level programming languages java c++ programming languages used processor understands instructions encoded numerical fashion usually binary numbers software tools compilers translate high level languages instructions processor understand besides instructions isa defines items computer available program—e.g data types registers addressing modes memory instructions locate available items register indexes names memory addressing modes isa computer usually described small instruction manual describes instructions encoded also may define short vaguely mnemonic names instructions names recognized software development tool called assembler assembler computer program translates human-readable form isa computer-readable form disassemblers also widely available usually debuggers software programs isolate correct malfunctions binary computer programs isas vary quality completeness good isa compromises programmer convenience easy code understand size code much code required specific action cost computer interpret instructions complexity means hardware needed decode execute instructions speed computer complex decoding hardware comes longer decode time memory organization defines instructions interact memory memory interacts design emulation software emulators run programs written proposed instruction set modern emulators measure size cost speed determine particular isa meeting goals computer organization helps optimize performance-based products example software engineers need know processing power processors may need optimize software order gain performance lowest price require quite detailed analysis computer organization example sd card designers might need arrange card data processed fastest possible way computer organization also helps plan selection processor particular project multimedia projects may need rapid data access virtual machines may need fast interrupts sometimes certain tasks need additional components well example computer capable running virtual machine needs virtual memory hardware memory different virtual computers kept separated computer organization features also affect power consumption processor cost instruction set micro-architecture designed practical machine must developed design process called implementation implementation usually considered architectural design rather hardware design engineering implementation broken several steps cpus entire implementation process organized differently often referred cpu design exact form computer system depends constraints goals computer architectures usually trade standards power versus performance cost memory capacity latency latency amount time takes information one node travel source throughput sometimes considerations features size weight reliability expandability also factors common scheme depth power analysis figures keep power consumption low maintaining adequate performance modern computer performance often described ipc instructions per cycle measures efficiency architecture clock frequency since faster rate make faster computer useful measurement older computers ipc counts low 0.1 instructions per cycle simple modern processors easily reach near 1 superscalar processors may reach three five ipc executing several instructions per clock cycle counting machine language instructions would misleading varying amounts work different isas instruction standard measurements count isa actual machine language instructions unit measurement usually based speed vax computer architecture many people used measure computer speed clock rate usually mhz ghz refers cycles per second main clock cpu however metric somewhat misleading machine higher clock rate may necessarily greater performance result manufacturers moved away clock speed measure performance factors influence speed mix functional units bus speeds available memory type order instructions programs two main types speed latency throughput latency time start process completion throughput amount work done per unit time interrupt latency guaranteed maximum response time system electronic event like disk drive finishes moving data performance affected wide range design choices — example pipelining processor usually makes latency worse makes throughput better computers control machinery usually need low interrupt latencies computers operate real-time environment fail operation completed specified amount time example computer-controlled anti-lock brakes must begin braking within predictable short time brake pedal sensed else failure brake occur benchmarking takes factors account measuring time computer takes run series test programs although benchmarking shows strengths n't choose computer often measured machines split different measures example one system might handle scientific applications quickly another might render video games smoothly furthermore designers may target add special features products hardware software permit specific benchmark execute quickly n't offer similar advantages general tasks power efficiency another important measurement modern computers higher power efficiency often traded lower speed higher cost typical measurement referring power consumption computer architecture mips/w millions instructions per second per watt modern circuits less power required per transistor number transistors per chip grows transistor put new chip requires power supply requires new pathways built power however number transistors per chip starting increase slower rate therefore power efficiency starting become important important fitting transistors single chip recent processor designs shown emphasis put focus power efficiency rather cramming many transistors single chip possible world embedded computers power efficiency long important goal next throughput latency increases clock frequency grown slowly past years compared power reduction improvements driven end moore law demand longer battery life reductions size mobile technology change focus higher clock rates power consumption miniaturization shown significant reductions power consumption much 50 reported intel release haswell microarchitecture dropped power consumption benchmark 30-40 watts 10-20 watts comparing processing speed increase 3 ghz 4 ghz 2002 2006 seen focus research development shifting away clock frequency moving towards consuming less power taking less space
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Computer architecture
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meshbox meshbox item computer hardware used provide large scale wireless broadband networks manufactured locustworld devices designed co-operate meshboxes within range passing internet service one box next air reaches final destination coverage area mesh typically measured square miles square kilometres originally released bootable cd-rom called meshap based openap open source software system implemented system image fit within small 32mb compactflash card system functions expanded beyond creating wireless networks provide set-top box services mp3 audio video streaming connection remote windows terminal servers pcs web browsing connection peer-to-peer networks instant messaging file exchange
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Distributed computing architecture
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marc auslander marc alan auslander american computer scientist known contributions pl/8 compiler spent entire career ibm thomas j. watson research center yorktown heights ny auslander received bachelor arts degree mathematics princeton university 1963 joined ibm year 1991 named ibm fellow retired 2004 continues affiliated ibm fellow emeritus 1996 auslander elected national academy engineering contributions reduced instruction set computing risc systems 1999 named acm fellow ieee fellow contributions risc 1970 1972 auslander served chairman acm sigops authored 19 scientific papers holds 14 u.s. patents
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Programming language topics
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distributional semantics distributional semantics research area develops studies theories methods quantifying categorizing semantic similarities linguistic items based distributional properties large samples language data basic idea distributional semantics summed so-called distributional hypothesis linguistic items similar distributions similar meanings distributional hypothesis linguistics derived semantic theory language usage i.e words used occur contexts tend purport similar meanings underlying idea word characterized company keeps popularized firth distributional hypothesis basis statistical semantics although distributional hypothesis originated linguistics receiving attention cognitive science especially regarding context word use recent years distributional hypothesis provided basis theory similarity-based generalization language learning idea children figure use words 've rarely encountered generalizing use distributions similar words distributional hypothesis suggests semantically similar two words distributionally similar turn thus tend occur similar linguistic contexts whether suggestion holds significant implications data-sparsity problem computational modeling question children able learn language rapidly given relatively impoverished input also known problem poverty stimulus distributional semantics favor use linear algebra computational tool representational framework basic approach collect distributional information high-dimensional vectors define distributional/semantic similarity terms vector similarity different kinds similarities extracted depending type distributional information used collect vectors topical similarities extracted populating vectors information text regions linguistic items occur paradigmatic similarities extracted populating vectors information linguistic items items co-occur note latter type vectors also used extract syntagmatic similarities looking individual vector components basic idea correlation distributional semantic similarity operationalized many different ways rich variety computational models implementing distributional semantics including latent semantic analysis lsa hyperspace analogue language hal syntax- dependency-based models random indexing semantic folding various variants topic model distributional semantic models differ primarily respect following parameters distributional semantic models use linguistic items context also referred word space vector space models compositional distributional semantic models extension distributional semantic models characterize semantics entire phrases sentences achieved composing distributional representations words sentences contain different approaches composition explored discussion established workshops semeval simpler non-compositional models fail capture semantics larger linguistic units ignore grammatical structure logical words crucial understanding distributional semantic models applied successfully following tasks
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Computational linguistics
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double tools doublespace double tools doublespace software utility released 1993 menlo park-based company addstor inc utility functioned add-on disk compression software doublespace supplied ms-dos 6.0 adding number features available standard version double tools utilities worked microsoft windows providing graphical view control panel compressed drives computer utilities supplied ms-dos operated dos-mode double tools also contained number disk checking rescue/recovery utilities included utilities called silent tools one unique features time capability defragment doublespace compressed drive background features including background defragmentation capability required user let double tools replace standard compression driver ms-dos dblspace.bin one developed addstor claimed 100 compatible doublespace microsoft real-time compression interface introduced ms-dos 6.0 driver added number extra features use 32-bit code paths detected intel 80386 higher cpu caching capabilities addition supporting use upper memory area also permitted use extended memory buffers reducing driver total footprint conventional upper memory albeit cost somewhat reduced speed features provided double tools ability compressed removable media auto-mounted used instead user manually although capability later introduced standard version doublespace found ms-dos 6.2 double tools also capability put special utility compressed floppy disks made possible access compressed data even computers n't doublespace double tools another interesting function ability split compressed volume multiple floppy disks able see entire volume first disk inserted prompted change discs necessary also possible share compressed volume remote computer
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Computer architecture
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nortel discovery protocol nortel discovery protocol ndp data link layer osi layer 2 network protocol discovery nortel networking devices certain products avaya ciena device topology information may graphically displayed network management software nortel discovery protocol origin synoptics network management protocol sonmp developed synoptics wellfleet communications merger 1994 protocol rebranded bay network management protocol bnmp protocol analyzers referenced bay discovery protocol bdp four years later 1998 bay networks acquired nortel renamed nortel discovery protocol ieee 802.1ab link layer discovery protocol supported nortel equipment standards based vendor-neutral protocol supports multi-vendor environments
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Internet protocols
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osek osek offene systeme und deren schnittstellen für die elektronik kraftfahrzeugen english open systems interfaces electronics motor vehicles standards body produced specifications embedded operating system communications stack network management protocol automotive embedded systems also produced related specifications osek designed provide standard software architecture various electronic control units ecus throughout car supported popular ssl/tls libraries wolfssl optimal security measures osek founded 1993 german automotive company consortium bmw robert bosch gmbh daimlerchrysler opel siemens volkswagen group university karlsruhe 1994 french cars manufacturers renault psa peugeot citroën similar project called vdx vehicle distributed executive joined consortium therefore official name osek/vdx osek open standard published consortium founded automobile industry parts osek standardized iso 17356 documents current osek standard specifies interfaces multitasking functions—generic i/o peripheral access—and thus remains architecture dependent osek systems expected run chips without memory protection features osek implementation usually configured compile-time number application tasks stacks mutexes etc statically configured possible create run time osek recognizes two types tasks/threads/compliance levels basic tasks enhanced tasks basic tasks never block run completion coroutine enhanced tasks sleep block event objects events triggered tasks basic enhanced interrupt routines static priorities allowed tasks first first fifo scheduling used tasks equal priority deadlocks priority inversion prevented priority ceiling i.e priority inheritance specification uses iso/ansi-c-like syntax however implementation language system services specified application binary interface abi also specified comment two claims contradictory 1 static priorities allowed tasks 2 uses priority ceiling states protocol works temporarily raising priorities tasks certain situations thus requires scheduler supports dynamic priority scheduling according german version entry namely scheduling configured two different ways br preemptive scheduling task always preempted means higher priority task. br non-preemptive scheduling task preempted prefixed compile-time points cooperative scheduling br mixed mode also possible autosar consortium reuses osek specifications operating system backwards compatible superset osek os also covers functionality osektime communication module derived osek com osektime specifies standard optional time-triggered real-time operating systems used osektime triggered callbacks run higher priority osek tasks
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Operating systems
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ngrep ngrep network grep network packet analyzer written jordan ritter command-line interface relies upon pcap library gnu regex library ngrep supports berkeley packet filter bpf logic select network sources destinations protocols also allows matching patterns regular expressions data payload packets using gnu grep syntax showing packet data human-friendly way ngrep open source application source code available download ngrep site sourceforge compiled ported multiple platforms works many unix-like operating systems linux solaris illumos bsd aix also works microsoft windows ngrep similar tcpdump ability look regular expression payload packet show matching packets screen console allows users see unencrypted traffic passed network putting network interface promiscuous mode ngrep appropriate bpf filter syntax used debug plain text protocols interactions like http smtp ftp dns among others search specific string pattern using grep regular expression syntax ngrep also used capture traffic wire store pcap dump files read files generated sniffer applications like tcpdump wireshark ngrep various options command line arguments ngrep man page unix-like operating systems show list available options examples assumed eth0 used network interface ngrep -l -q -d eth0 -i ^get |^post tcp port 80 ngrep -l -q -d eth0 -i user-agent tcp port 80 ngrep -l -q -d eth0 -i udp port 53 capturing raw network traffic interface requires special privileges superuser privileges platforms especially unix-like systems ngrep default behavior drop privileges platforms running specific unprivileged user like tcpdump also possible use ngrep specific purpose intercepting displaying communications another user computer entire network privileged user running ngrep server workstation connected device configured port mirroring switch router gateway connected device used network traffic capture lan man wan watch unencrypted information related login id passwords urls content websites viewed network
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Computer security
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psake psake domain-specific language build automation tool written powershell create builds using dependency pattern similar rake msbuild intends simplify build language compared msbuild scripting build script consists tasks task function define dependencies task functions following example psake script psake executes task functions enforces dependencies tasks since psake written real programming language xml lot freedom flexibility build scripts use features powershell .net framework within build output running psake script shown
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Programming language topics
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http message body http message body data bytes transmitted http transaction message immediately following headers case http/0.9 headers transmitted request/response message consists following request/status line headers must end cr lf carriage return followed line feed empty line must consist cr lf whitespace optional http message body data article defines could response web server message body content example text hello world
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Internet protocols
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intelligent database 1980s databases viewed computer systems stored record-oriented business data manufacturing inventories bank records sales transactions database system expected merge numeric data text images multimedia information expected automatically notice patterns data stored late 1980s concept intelligent database put forward system manages information rather data way appears natural users goes beyond simple record keeping term introduced 1989 book intelligent databases kamran parsaye mark chignell setrag khoshafian harry wong concept postulated three levels intelligence systems high level tools user interface database engine high level tools manage data quality automatically discover relevant patterns data process called data mining layer often relies use artificial intelligence techniques user interface uses hypermedia form uniformly manages text images numeric data intelligent database engine supports two layers often merging relational database techniques object orientation twenty-first century intelligent databases become widespread e.g hospital databases call patient histories consisting charts text x-ray images mouse clicks many corporate databases include decision support tools based sales pattern analysis
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Databases
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active template library active template library atl set template-based c++ classes developed microsoft intended simplify programming component object model com objects com support microsoft visual c++ allows developers create variety com objects ole automation servers activex controls atl includes object wizard sets primary structure objects quickly minimum hand coding com client side atl provides smart pointers deal com reference counting library makes heavy use curiously recurring template pattern com objects also created microsoft foundation classes mfc leads larger binaries require support dlls atl hand lightweight alternative situations graphical user interface parts mfc required atl version 7 visual studio 2003 directly succeeded version 3 visual studio 6.0 number mfc classes like cstring made available atl precisely moved atlmfc common layer shared libraries atl version 7 also introduced attributes c++ attempt provide something similar cli attributes however particularly successful deemphasized atl version 8 visual studio 2005 various wizards longer generate default version 7 also introduced new string conversion classes july 28 2009 microsoft released patch atl fix bug could allow activex controls created using atl vulnerable remote code execution security flaw since visual studio 2013 atl code visual c++ 2013 static eliminating dll atl includes many raii classes simplify management com types commonly used classes include although formally part atl microsoft visual c++ also includes additional c++ raii classes simplify management com types compiler com support classes used replacement combination atl includes note visual studio 2012 compiler com support classes include safearray wrapper
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Operating systems
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pymc3 pymc3 python package bayesian statistical modeling probabilistic machine learning focuses advanced markov chain monte carlo variational fitting algorithms rewrite scratch previous version pymc software unlike pymc2 used fortran extensions performing computations pymc3 relies theano automatic differentiation also computation optimization dynamic c compilation pymc3 together stan popular probabilistic programming tools pymc3 open source project developed community fiscally sponsored numfocus pymc3 used solve inference problems several scientific domains including astronomy molecular biology crystallography chemistry ecology psychology previous versions pymc also used widely example climate science public health neuroscience parasitology theano announced plans discontinue development 2017 pymc3 team decided 2018 develop new version pymc named pymc4 pivot tensorflow probability computational backend new version beta pymc3 continue primary target development efforts theano backend supported pymc3 team extended period time pymc3 implements non-gradient-based gradient-based markov chain monte carlo mcmc algorithms bayesian inference stochastic gradient-based variational bayesian methods approximate bayesian inference
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Programming language topics
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socket g2 socket g2 also known rpga 988b intel cpu socket used line mobile core i7 successor core 2 line also several mobile core i5 core i3 processors based intel sandy bridge architecture like predecessor socket g1 systems run dual-channel memory mode data rates 1600 mhz opposed triple-channel mode unique lga-1366 platform subsequent xeon sockets socket g2 cpus also known fcpga988 socket processors pin compatible ppga988 although nearly motherboards using socket intended mobile products like laptops desktop boards using exist supermicro example produced number mini itx motherboards using qm77 chipset rpga 989 sockets shown left take socket socket g1 rpga988a socket socket g2 rpga988b supported memory see also
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Computer architecture
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cd command command also known change directory command-line shell command used change current working directory various operating systems used shell scripts batch files command implemented operating unix dos ibm os/2 metacomco tripos amigaos bare path given cd implied microsoft windows reactos linux ms-dos available versions 2 later dr dos 6.0 also includes implementation commands command also available open source ms-dos emulator dosbox efi shell named hp mpe/ix command analogous stratus openvos command system call affects command operating systems defined posix command line shells windows usually use windows api change current working directory whereas unix systems calls posix c function means command executed new process created migrate directory case commands ls instead shell executes command new process created child process inherits directory parent process created command inherits parent process directory objective command cd never achieved windows powershell microsoft object-oriented command line shell scripting language executes command cmdlet within shell process however since powershell based .net framework different architecture previous shells powershell cmdlets like etc run shell process course true legacy commands still run separate process directory logical section file system used hold files directories may also contain directories command used change subdirectory move back parent directory move way back root directory move given directory consider following subsection unix filesystem shows user home directory represented file three subdirectories user current working directory home directory entering command codice_3 followed might produce following transcript user games directory similar session dos though concept home directory may apply depending specific version would look like dos maintains separate working directories lettered drive also concept current working drive command used change working directory working drive another lettered drive typing drive letter command changes working drive e.g alternatively switch may used change working drive drive working directory one step modern versions windows simulate behaviour backwards compatibility cmd.exe note executing command line arguments different effects different operating systems example executed without arguments dos os/2 windows current working directory displayed equivalent unix codice_4 executed without arguments unix user returned home directory executing command within script batch file also different effects different operating systems dos caller current directory directly altered batch file use command unix caller current directory altered script invocation command unix script usually executed within subshell file transfer protocol respective command spelled control stream available client command-line programs clients also changing working directory locally numerical computing environments matlab gnu octave include codice_5 function similar functionality command also pertains command-line interpreters various application software
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Computer file systems
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sv-328 sv-328 8-bit home computer introduced spectravideo june 1983 business-targeted model spectravideo range sporting rather crowded full-travel keyboard numeric keypad 80 kb ram 64 kb available software remaining 16 kb video memory respectable amount time keyboard ram machine identical little brother sv-318 sv-328 design msx standard based spectravideo msx-compliant successor 328 sv-728 looks almost identical immediately noticeable differences larger cartridge slot central position fit msx standard cartridges lighter shaded keyboard msx badging reference operating system microsoft extended basic confused msx basic although marketing time claimed microsoft extended msx stood back sv-318 sv-328 adapters permit connect peripherals tape drive sv-903 cvbs monitor joysticks however super expander unit options available
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Computer architecture
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cfengine cfengine open-source configuration management system written mark burgess primary function provide automated configuration maintenance large-scale computer systems including unified management servers desktops consumer industrial devices embedded networked devices mobile smartphones tablet computers cfengine project began 1993 way author mark burgess post-doctoral fellow royal society oslo university norway get work done automating management small group workstations department theoretical physics like many post-docs phd students burgess ended task managing unix workstations scripting fixing problems users manually scripting took much time flavours unix significantly different scripts maintained multiple platforms drowning exception logic discussing problems colleague burgess wrote first version cfengine configuration engine published internal report presented cern computing conference gained significant attention wider community able hide platform differences using domain-specific language year later burgess finished post-doc decided stay oslo took job lecturing oslo university college realized little research done configuration management set applying principles scientific modelling understanding computer systems short space time developed notion convergent operators remains core cfengine 1998 burgess wrote computer immunology paper usenix/lisa98 conference laid manifesto creating self-healing systems reiterated years later ibm form autonomic computing started research effort led major re-write cfengine 2 added features machine learning anomaly detection secure communications 1998 2004 cfengine grew adoption along popularity linux computing platform time mark burgess developed promise theory model distributed cooperation self-healing automation 2008 five years research cfengine 3 introduced incorporated promise theory way make cfengine simpler powerful time according burgess significant re-write project date cfengine 3 also integrated knowledge management discovery mechanisms—allowing configuration management scale automate enterprise-class infrastructure june 2008 company cfengine formed collaboration author mark burgess oslo university college oslo innovation centre order support users cfengine april 2009 company launched first commercial version cfengine cfengine enterprise enterprise version downloaded free 25 agents clients february 2011 company received first round funding ferd capital company offices oslo norway mountain view california usa cfengine provides operating system-independent interface unix-like host configuration requires expert knowledge deal peculiarities different operating systems power perform maintenance actions across multiple hosts cfengine used windows hosts well widely used managing large numbers unix hosts run heterogeneous operating systems e.g solaris linux aix tru64 hp-ux shortly inception cfengine inspired field research automated configuration management cfengine project claims attempt place problem configuration management scientific framework author mark burgess developed range theoretical tools results talk problem written several text books monographs explaining one main ideas cfengine changes computer configuration carried convergent manner means change operation made agent character fixed point rather describing steps needed make change cfengine language describes final state one wants end agent ensures necessary steps taken end policy compliant state thus cfengine run whatever initial state system end predictable result cfengine supports item statistical compliance policy meaning system never guarantee exactly ideal desired state rather one approaches converges towards desired state best-effort rate determined ratio frequency environmental change rate cfengine execution cfengine used large small companies well many universities governmental institutions sites large 40,000 machines reported linkedin sites several thousand hosts running cfengine common according statistics cfengine probably several million computers run cfengine around world users 100 countries registered
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Operating systems
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android q android q upcoming tenth major release 17th version android mobile operating system currently public beta final release android q scheduled release q3 2019 google released first beta android q march 13 2019 exclusively pixel phones including first generation pixel pixel xl devices support extended due popular demand total six beta release-candidate versions released final release currently scheduled third quarter 2019 beta program expanded release beta 3 may 7 2019 beta available 14 partner devices 11 oems twice many devices compared android pie beta beta access removed huawei mate 20 pro may 21 2019 due u.s. government sanctions later reverted given access back may 31 google released beta 4 june 5 2019 finalized android q apis sdk api level 29 dynamic system updates dsu also included beta 4 dynamic system update allows android q devices temporarily install gsi generic system image try newer version android top current android version users decide end testing chosen gsi image simply reboot device boot back normal device android version google released beta 5 july 10 2019 final api 29 sdk well latest optimizations bug fixes google released beta 6 final release candidate testing august 7 2019 android q introduces revamped full-screen gesture system gestures swiping either side edge display go back swiping go home screen swiping holding access overview swiping diagonally bottom corner screen activate google assistant swiping along gesture bar bottom screen switch apps support gestures mandatory oems free add gestures alongside core gestures legacy three-key navigation style remains supported use edge swiping gesture back command noted potentially causing conflicts apps utilize sidebar menus functions accessible swiping api used apps opt handling back gesture within specific areas screen sensitivity control added adjusting size target area activate gesture google later stated drawer widget would support peeked long-pressing near edge screen swiped open feature known bubbles used present content supported apps pop-up overlays similarly overlay-based chat heads feature facebook messenger apps spawn bubbles via notifications example use cases feature include chat messaging apps reminders ongoing tasks updates bubbles designed replace existing overlay permission deprecated due security due use clickjacking malware performance concerns go edition forbids use overlay permissions entirely sideloaded apps automatically lose overlay permission 30 seconds apps play store lose overlay permission time device rebooted android q includes system-level dark theme third-party apps automatically engage dark theme mode active platform optimizations made foldable smartphones including app continuity changing modes changes multi-window mode allow apps run simultaneously rather actively-used app running others considered paused additional support multiple displays direct share succeeded sharing shortcuts allows apps return lists direct targets sharing combination app specific contact use within share menus unlike direct share apps publish targets advance polled runtime improving performance several major security privacy changes present q apps restricted users access location data actively used foreground also new restrictions launching activities background apps major change storage access permissions known scoped storage supported q become mandatory apps beginning next major android release 2020 apps allowed access files external storage created preferably contained within app-specific directory audio image video files contained within music pictures videos directories file may accessed via user intervention storage access framework apps must new read privileged phone state permission order read non-resettable device identifiers imei number
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Operating systems
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honeynet project honeynet project international security research organization dedicated investigating latest attacks developing open source security tools improve internet security learning hackers behave honeynet project began 1999 small mailing list group people time group expanded officially dubbed honeynet project june 2000 project includes dozens active chapters around world including brazil indonesia greece india mexico iran australia ireland many united states honeynet project focuses three primary goals honeynet project volunteers collaborate security research efforts covering data analysis approaches unique security tool development gathering data attackers malicious software use project research provides critical additional information motives attacking communicate attack systems actions compromising system information provided know enemy whitepapers project blog posts scan month forensic challenges project uses normal computers without known vulnerabilities monitors network attacks
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Computer security
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ishido way stones ishido way stones puzzle video game released 1990 accolade developed publishing international designed michael feinberg programmed ian gilman michael sandige game producer brad fregger brodie lockard designer shanghai computer game contributed graphics ishido puzzle board game consisting set 72 stones game board 96 squares every stone two attributes color symbol six colors six symbols stone set thus creating 36 unique stones since stone comes pair therefore 72 stones stone set primary objective ishido place 72 stones onto board 96 squares challenge arises stones must placed adjacent others match either color symbol board begins fill objective easily accomplished valuable move 4-way stone placed midst four others two matched color two matched symbol ishido comes 6 differently themed stone sets 5 different game boards variety oriental chimes sound effects ishido originally released macintosh 1990 ports ms-dos amiga game boy sega genesis year atari lynx famicom disk system versions published 1991 microsoft entertainment pack contained adaptation ishido called stones genesis port game involved copyright trial sega v. accolade actual physical board game version ishido published japan ascii 1992 compute called macintosh version ishido addictive ... peaceful encounter oriental flavor new york times wrote one deceptively simple games like go gradually reveal subtleties ... engrossing computer gaming world called game remarkably complex entertainment resource pleasant surprises magazine liked ishido vga graphics concluded would please novice experienced strategy game players atari lynx version game reviewed 1992 dragon 181 hartley patricia kirk lesser role computers column reviewers gave game 5 5 stars entertainment weekly gave game b+ ishido rated 'five mice macuser entered macuser game hall fame also pc magazine best strategy game year award 1990 reviewing ishido re-release 1995 macuser gave 4 5 mice integrated ishido oracle way ask questions ancient chinese book changes ching first user poses question meditate upon playing game attain 4-way match ishido utilizing algorithm authentic yarrow stalk method consulting oracle obtains answer original translation ching used wilhelm/baynes anthony translations primary sources written game michael feinberg original ishido game published publishing international limited edition hand-made walnut slip box following year 1990 accolade published first mass-market version ishido came 20-page booklet legend ishido began story fictional written michael feinberg nevertheless many believed ishido actually ancient game recently re-discovered
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Computer architecture
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macintosh quadra 950 macintosh quadra 950 also sold additional software workgroup server 95 personal computer designed manufactured sold apple computer inc. march 1992 october 1995 replaced quadra 900 introduced several months earlier increasing cpu clock rate 68040 cpu improving graphics support two computers otherwise identical including price macintosh processor upgrade card installed computer known power macintosh 950 1993 950 overtaken performance less expensive quadra 800 840av newer quadras addition interleaved ram well enhanced video system scsi bus however compact mini-tower case offered less expansion capability 950 due mid-tower case allowing 6 slots supported kept continued production server market outliving 800 840av 950 discontinued apple n't offer another 6-slot macintosh power macintosh 9600 1997 quadra 950 replaced powerpc-based power macintosh 9500 may 1995 sales continuing october last macintosh quadra sold apple one last 68k models discontinued due high ram capacity large number nubus slots workgroup server 95 succeeded workgroup server 9150 logic board five nubus slots processor direct slot due positioning pds possible use one nubus slots pds card installed nubus-90 standard partially supported allowing cards run 20 mhz two slots provide 25 watts power instead usual 15 watts logic board 1 mb on-board video ram 4 simm slots allow upgrading 2 mb 950 includes key limit access various subsystems depending computer use environment key switch three positions labelled secure position immediately cuts power prevented computer powered position allows computer operate normally secure position intended use server – power always applied position computer lost power immediately starts power restored also position disables keyboard mouse floppy disk drive workgroup server 95 models include workgroup server pds card provides three capabilities two scsi controllers two internal scsi connectors plus one external connector dms scsi control chip reduces i/o load main cpu 128 kb sram used l2 cache three additional slots provide ability expand l2 cache 512 kb quadra 950 announced march 18 dealers receiving machines around may 18 introduced may 18 1992 introduced march 22 1993
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Computer architecture
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