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oracle fusion middleware oracle fusion middleware fmw also known fusion middleware consists several software products oracle corporation fmw spans multiple services including java ee developer tools integration services business intelligence collaboration content management fmw depends open standards bpel soap xml jms oracle fusion middleware provides software development deployment management service-oriented architecture soa includes oracle calls hot-pluggable architecture designed facilitate integration existing applications systems software vendors ibm microsoft sap ag many products included fmw banner qualify middleware products fusion middleware essentially represents re-branding many oracle products outside oracle core database applications-software offerings—compare oracle fusion oracle acquired many fmw products via acquisitions includes products bea systems stellent order provide standards-based software assist business process automation hp incorporated fmw service-oriented architecture soa portfolio oracle leveraged configurable network computing cnc technology acquired peoplesoft/jd edwards 2005 purchase oracle fusion applications based oracle fusion middleware finally released september 2010 according oracle 2013 120,000 customers using fusion middleware includes 35 world 50 largest companies 750 businessweek global 1000 fmw also supported 7,500 partners january 2008 oracle webcenter content formerly universal content management infoworld technology year award best enterprise content manager oracle soa suite winning award best enterprise service bus 2007 gartner wrote oracle fusion middleware reached degree completeness puts par cases ahead competing software stacks reported revenue suite us 1 billion fy06 estimating revenue genuinely middleware aspects us 740 million
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Distributed computing architecture
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acrojet acrojet 1985 flight simulator video game microprose originally developed commodore 64 c64 ported amstrad cpc msx zx spectrum nec pc-8801 nec pc-9801 emphasized aerial acrobatic flying maneuverability player flies bd5j small agile jet player complete series eight stunt courses routines jet example one set player fly plane around series pylons another player must fly figure eight stunts get harder play progresses game parameters weather configurable ten acrobatic events played four players four levels difficulty ten events player must fly series obstacles compute called acrojet realistic simulation also fun play stating game like microprose products emphasized accurate details controls original c64 version programmed william mike denman edward hill jr sound music done sid meier also researched science along denman stunts bill stealey actually retired united states air force lt colonel command pilot michael haire credited artwork
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Computer architecture
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parameter computer programming computer programming parameter formal argument special kind variable used subroutine refer one pieces data provided input subroutine pieces data values arguments often called actual arguments actual parameters subroutine going called/invoked ordered list parameters usually included definition subroutine time subroutine called arguments call evaluated resulting values assigned corresponding parameters unlike argument usual mathematical usage argument computer science thus actual input expression passed/supplied function procedure routine invocation/call statement whereas parameter variable inside implementation subroutine example one defines codice_1 subroutine codice_2 codice_3 parameters called codice_4 codice_5 arguments note variables expressions thereof calling context arguments subroutine called codice_6 variables codice_7 arguments values codice_5 see parameters arguments section information common case call value parameter acts within subroutine new local variable initialized value argument local isolated copy argument argument variable cases e.g call reference argument variable supplied caller affected actions within called subroutine discussed evaluation strategy semantics parameters declared value arguments passed parameters subroutines defined language details represented particular computer system depend calling conventions system following program c programming language defines function named salestax one parameter named price type price double i.e double-precision floating point number function return type also double function defined invoked follows example function invoked argument 10.00 happens 10.00 assigned price function begins calculating result steps producing result specified enclosed codice_9 indicates first thing multiply 0.05 value price gives 0.50. codice_10 means function produce result codice_9 therefore final result ignoring possible round-off errors one encounters representing decimal fractions binary fractions 0.50 terms parameter argument may different meanings different programming languages sometimes used interchangeably context used distinguish meaning term parameter sometimes called formal parameter often used refer variable found function definition argument sometimes called actual parameter refers actual input supplied function call example one defines function codice_12 codice_13 parameter called codice_14 codice_15 argument parameter unbound variable argument value variable complex expression involving values variables case call value passed function value argument – example codice_16 codice_17 equivalent calls – call reference variable argument passed reference variable even though syntax function call could stay specification pass-by-reference pass-by-value would made function declaration and/or definition parameters appear procedure definitions arguments appear procedure calls function definition codice_18 variable x parameter function call codice_16 value 2 argument function loosely parameter type argument instance parameter intrinsic property procedure included definition example many languages procedure add two supplied integers together calculate sum would need two parameters one integer general procedure may defined number parameters parameters procedure parameters part definition specifies parameters called parameter list contrast arguments expressions supplied procedure called usually one expression matching one parameters unlike parameters form unchanging part procedure definition arguments may vary call call time procedure called part procedure call specifies arguments called argument list although parameters also commonly referred arguments arguments sometimes thought actual values references assigned parameter variables subroutine called run-time discussing code calling subroutine values references passed subroutine arguments place code values references given parameter list discussing code inside subroutine definition variables subroutine parameter list parameters values parameters runtime arguments example c dealing threads common pass argument type void* cast expected type better understand difference consider following function written c function sum two parameters named addend1 addend2 adds values passed parameters returns result subroutine caller using technique automatically supplied c compiler code calls sum function might look like variables value1 value2 initialized values value1 value2 arguments sum function context runtime values assigned variables passed function sum arguments sum function parameters addend1 addend2 evaluated yielding arguments 40 2 respectively values arguments added result returned caller assigned variable sum_value difference parameters arguments possible supply inappropriate arguments procedure call may supply many arguments one arguments may wrong type arguments may supplied wrong order situations causes mismatch parameter argument lists procedure often return unintended answer generate runtime error within eiffel software development method language terms argument parameter distinct uses established convention term argument used exclusively reference routine inputs term parameter used exclusively type parameterization generic classes consider following routine definition routine codice_20 takes two arguments codice_21 codice_22 called routine formal arguments call codice_20 specifies actual arguments shown codice_24 codice_25 parameters also thought either formal actual formal generic parameters used definition generic classes example class codice_26 declared generic class two formal generic parameters codice_27 representing data interest codice_28 representing hash key data class hash_table g k hashable class becomes client codice_26 formal generic parameters substituted actual generic parameters generic derivation following attribute declaration codice_30 used character string based dictionary data key formal generic parameters substituted actual generic parameters type codice_31 strongly typed programming languages parameter type must specified procedure declaration languages using type inference attempt discover types automatically function body usage dynamically typed programming languages defer type resolution run-time weakly typed languages perform little type resolution relying instead programmer correctness languages use special keyword e.g void indicate subroutine parameters formal type theory functions take empty parameter list whose type void rather unit exact mechanism assigning arguments parameters called argument passing depends upon evaluation strategy used parameter typically call value may specified using keywords programming languages ada c++ clojure common lisp fortran 90 python ruby tcl windows powershell allow default argument explicitly implicitly given subroutine declaration allows caller omit argument calling subroutine default argument explicitly given value used provided caller default argument implicit sometimes using keyword optional language provides well-known value null empty zero empty string etc value provided caller powershell example default arguments seen special case variable-length argument list languages allow subroutines defined accept variable number arguments languages subroutines must iterate list arguments powershell example programming languages—such ada windows powershell—allow subroutines named parameters allows calling code self-documenting also provides flexibility caller often allowing order arguments changed arguments omitted needed powershell example lambda calculus function exactly one parameter thought functions multiple parameters usually represented lambda calculus function takes first argument returns function takes rest arguments transformation known currying programming languages like ml haskell follow scheme languages every function exactly one parameter may look like definition function multiple parameters actually syntactic sugar definition function returns function etc function application left-associative languages well lambda calculus looks like application function multiple arguments correctly evaluated function applied first argument resulting function applied second argument etc output parameter also known parameter return parameter parameter used output rather usual use input using call reference parameters call value parameters value reference output parameters idiom languages notably c c++ languages built-in support output parameters languages built-in support output parameters include ada see fortran since fortran 90 see various procedural extensions sql pl/sql see pl/sql functions transact-sql c .net framework swift scripting language tscript see tscript function declarations precisely one may distinguish three types parameters parameter modes output parameters often denoted codice_32 codice_33 codice_34 codice_35 input argument argument input parameter must value initialized variable literal must redefined assigned output argument must assignable variable need initialized existing value accessible must assigned value input/output argument must initialized assignable variable optionally assigned value exact requirements enforcement vary languages – example ada 83 output parameters assigned read even assignment removed ada 95 remove need auxiliary accumulator variable analogous notion value expression r-value value l-value assigned r-value/l-value value assigned respectively though terms specialized meanings c. cases input input/output distinguished output considered specific use input/output cases input output input/output supported default mode varies languages fortran 90 input/output default c sql extensions input default tscript parameter explicitly specified input output syntactically parameter mode generally indicated keyword function declaration codice_36 c conventionally output parameters often put end parameter list clearly distinguish though always followed tscript uses different approach function declaration input parameters listed output parameters separated colon return type function function computes size text fragment parameter modes form denotational semantics stating programmer intent allowing compilers catch errors apply optimizations – necessarily imply operational semantics parameter passing actually occurs notably input parameters implemented call value output input/output parameters call reference – straightforward way implement modes languages without built-in support – always implemented distinction discussed detail ada '83 rationale emphasizes parameter mode abstracted parameter passing mechanism reference copy actually implemented instance c input parameters default keyword passed value output input/output parameters codice_33 codice_38 passed reference pl/sql input parameters codice_39 passed reference output input/output parameters codice_40 codice_41 default passed value result copied back passed reference using codice_42 compiler hint syntactically similar construction output parameters assign return value variable name function found pascal fortran 66 fortran 77 pascal example semantically different called function simply evaluated – passed variable calling scope store output primary use output parameters return multiple values function use input/output parameters modify state using parameter passing rather shared environment global variables important use returning multiple values solve semipredicate problem returning value error status – see semipredicate problem multivalued return example return two variables function c one may write codice_13 input parameter codice_44 codice_45 output parameters common use case c related languages exception handling function places return value output variable returns boolean corresponding whether function succeeded archetypal example codice_46 method .net especially c parses string integer returning codice_47 success codice_48 failure following signature may used follows similar considerations apply returning value one several possible types return value specify type value stored one several output variables output parameters often discouraged modern programming essentially awkward confusing low-level – commonplace return values considerably easier understand work notably output parameters involve functions side effects modifying output parameter semantically similar references confusing pure functions values distinction output parameters input/output parameters subtle since common programming styles parameters simply input parameters output parameters input/output parameters unusual hence susceptible misunderstanding output input/output parameters prevent function composition since output stored variables rather value expression thus one must initially declare variable step chain functions must separate statement example c++ following function composition written output input/output parameters instead becomes codice_49 output parameter codice_27 input/output parameter special case function single output input/output parameter return value function composition possible output input/output parameter c/c++ address also returned function case becomes various alternatives use cases output parameters returning multiple values function alternative return tuple syntactically clearer automatic sequence unpacking parallel assignment used go python returning value one several types tagged union used instead common cases nullable types option types return value null indicate failure exception handling one return nullable type raise exception example python one might either idiomatically micro-optimization requiring local variable copying return using output variables also applied conventional functions return values sufficiently sophisticated compilers usual alternative output parameters c related languages return single data structure containing return values example given structure encapsulating width height one write object-oriented languages instead using input/output parameters one often use call sharing passing reference object mutating object though changing object variable refers
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Programming language topics
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personal internet security 2011 personal internet security 2011 scareware rogue anti-virus fake computer protection program induces users think number viruses personal internet security fact virus program encourages users pay certain amount subscription clean computers protect computers users also notice different number viruses listed every time virus pops
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Computer security
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speech recognition speech recognition interdisciplinary subfield computational linguistics develops methodologies technologies enables recognition translation spoken language text computers also known automatic speech recognition asr computer speech recognition speech text stt incorporates knowledge research linguistics computer science electrical engineering fields speech recognition systems require training also called enrollment individual speaker reads text isolated vocabulary system system analyzes person specific voice uses fine-tune recognition person speech resulting increased accuracy systems use training called speaker independent systems systems use training called speaker dependent speech recognition applications include voice user interfaces voice dialing e.g call home call routing e.g would like make collect call domotic appliance control search e.g find podcast particular words spoken simple data entry e.g. entering credit card number preparation structured documents e.g radiology report determining speaker characteristics speech-to-text processing e.g. word processors emails aircraft usually termed direct voice input term voice recognition speaker identification refers identifying speaker rather saying recognizing speaker simplify task translating speech systems trained specific person voice used authenticate verify identity speaker part security process technology perspective speech recognition long history several waves major innovations recently field benefited advances deep learning big data advances evidenced surge academic papers published field importantly worldwide industry adoption variety deep learning methods designing deploying speech recognition systems key areas growth vocabulary size speaker independence processing speed raj reddy first person take continuous speech recognition graduate student stanford university late 1960s previous systems required users pause word reddy system issued spoken commands playing game chess around time soviet researchers invented dynamic time warping dtw algorithm used create recognizer capable operating 200-word vocabulary dtw processed speech dividing short frames e.g 10ms segments processing frame single unit although dtw would superseded later algorithms technique carried achieving speaker independence remained unsolved time period late 1960s leonard baum developed mathematics markov chains institute defense analysis decade later cmu raj reddy students james baker janet m. baker began using hidden markov model hmm speech recognition james baker learned hmms summer job institute defense analysis undergraduate education use hmms allowed researchers combine different sources knowledge acoustics language syntax unified probabilistic model 1980s also saw introduction n-gram language model much progress field owed rapidly increasing capabilities computers end darpa program 1976 best computer available researchers pdp-10 4 mb ram could take 100 minutes decode 30 seconds speech two practical products point vocabulary typical commercial speech recognition system larger average human vocabulary raj reddy former student xuedong huang developed sphinx-ii system cmu sphinx-ii system first speaker-independent large vocabulary continuous speech recognition best performance darpa 1992 evaluation handling continuous speech large vocabulary major milestone history speech recognition huang went found speech recognition group microsoft 1993 raj reddy student kai-fu lee joined apple 1992 helped develop speech interface prototype apple computer known casper lernout hauspie belgium-based speech recognition company acquired several companies including kurzweil applied intelligence 1997 dragon systems 2000 l h speech technology used windows xp operating system l h industry leader accounting scandal brought end company 2001 speech technology l h bought scansoft became nuance 2005 apple originally licensed software nuance provide speech recognition capability digital assistant siri 2000s darpa sponsored two speech recognition programs effective affordable reusable speech-to-text ears 2002 global autonomous language exploitation gale four teams participated ears program ibm team led bbn limsi univ pittsburgh cambridge university team composed icsi sri university washington ears funded collection switchboard telephone speech corpus containing 260 hours recorded conversations 500 speakers gale program focused arabic mandarin broadcast news speech google first effort speech recognition came 2007 hiring researchers nuance first product goog-411 telephone based directory service recordings goog-411 produced valuable data helped google improve recognition systems google voice search supported 30 languages united states national security agency made use type speech recognition keyword spotting since least 2006 technology allows analysts search large volumes recorded conversations isolate mentions keywords recordings indexed analysts run queries database find conversations interest government research programs focused intelligence applications speech recognition e.g darpa ears program iarpa babel program early 2000s speech recognition still dominated traditional approaches hidden markov models combined feedforward artificial neural networks today however many aspects speech recognition taken deep learning method called long short-term memory lstm recurrent neural network published sepp hochreiter jürgen schmidhuber 1997 lstm rnns avoid vanishing gradient problem learn deep learning tasks require memories events happened thousands discrete time steps ago important speech around 2007 lstm trained connectionist temporal classification ctc started outperform traditional speech recognition certain applications 2015 google speech recognition reportedly experienced dramatic performance jump 49 ctc-trained lstm available google voice smartphone users use deep feedforward non-recurrent networks acoustic modeling introduced later part 2009 geoffrey hinton students university toronto li deng colleagues microsoft research initially collaborative work microsoft university toronto subsequently expanded include ibm google hence shared views four research groups subtitle 2012 review paper microsoft research executive called innovation dramatic change accuracy since 1979 contrast steady incremental improvements past decades application deep learning decreased word error rate 30 innovation quickly adopted across field researchers begun use deep learning techniques language modeling well long history speech recognition shallow form deep form e.g recurrent nets artificial neural networks explored many years 1980s 1990s years 2000s methods never non-uniform internal-handcrafting gaussian mixture model/hidden markov model gmm-hmm technology based generative models speech trained discriminatively number key difficulties methodologically analyzed 1990s including gradient diminishing weak temporal correlation structure neural predictive models difficulties addition lack big training data big computing power early days speech recognition researchers understood barriers hence subsequently moved away neural nets pursue generative modeling approaches recent resurgence deep learning starting around 2009–2010 overcome difficulties hinton et al deng et al reviewed part recent history collaboration colleagues across four groups university toronto microsoft google ibm ignited renaissance applications deep feedforward neural networks speech recognition early 2010s speech recognition also called voice recognition clearly differentiated speaker recognition speaker independence considered major breakthrough systems required training period 1987 ad doll carried tagline finally doll understands – despite fact described children could train respond voice 2017 microsoft researchers reached historical human parity milestone transcribing conversational telephony speech widely benchmarked switchboard task multiple deep learning models used optimize speech recognition accuracy speech recognition word error rate reported low 4 professional human transcribers working together benchmark funded ibm watson speech team task acoustic modeling language modeling important parts modern statistically-based speech recognition algorithms hidden markov models hmms widely used many systems language modeling also used many natural language processing applications document classification statistical machine translation modern general-purpose speech recognition systems based hidden markov models statistical models output sequence symbols quantities hmms used speech recognition speech signal viewed piecewise stationary signal short-time stationary signal short time-scale e.g. 10 milliseconds speech approximated stationary process speech thought markov model many stochastic purposes another reason hmms popular trained automatically simple computationally feasible use speech recognition hidden markov model would output sequence n -dimensional real-valued vectors n small integer 10 outputting one every 10 milliseconds vectors would consist cepstral coefficients obtained taking fourier transform short time window speech decorrelating spectrum using cosine transform taking first significant coefficients hidden markov model tend state statistical distribution mixture diagonal covariance gaussians give likelihood observed vector word general speech recognition systems phoneme different output distribution hidden markov model sequence words phonemes made concatenating individual trained hidden markov models separate words phonemes described core elements common hmm-based approach speech recognition modern speech recognition systems use various combinations number standard techniques order improve results basic approach described typical large-vocabulary system would need context dependency phonemes phonemes different left right context different realizations hmm states would use cepstral normalization normalize different speaker recording conditions speaker normalization might use vocal tract length normalization vtln male-female normalization maximum likelihood linear regression mllr general speaker adaptation features would so-called delta delta-delta coefficients capture speech dynamics addition might use heteroscedastic linear discriminant analysis hlda might skip delta delta-delta coefficients use splicing lda-based projection followed perhaps heteroscedastic linear discriminant analysis global semi-tied co variance transform also known maximum likelihood linear transform mllt many systems use so-called discriminative training techniques dispense purely statistical approach hmm parameter estimation instead optimize classification-related measure training data examples maximum mutual information mmi minimum classification error mce minimum phone error mpe decoding speech term happens system presented new utterance must compute likely source sentence would probably use viterbi algorithm find best path choice dynamically creating combination hidden markov model includes acoustic language model information combining statically beforehand finite state transducer fst approach possible improvement decoding keep set good candidates instead keeping best candidate use better scoring function scoring rate good candidates may pick best one according refined score set candidates kept either list n-best list approach subset models lattice scoring usually done trying minimize bayes risk approximation thereof instead taking source sentence maximal probability try take sentence minimizes expectancy given loss function regards possible transcriptions i.e. take sentence minimizes average distance possible sentences weighted estimated probability loss function usually levenshtein distance though different distances specific tasks set possible transcriptions course pruned maintain tractability efficient algorithms devised score lattices represented weighted finite state transducers edit distances represented finite state transducer verifying certain assumptions dynamic time warping approach historically used speech recognition largely displaced successful hmm-based approach dynamic time warping algorithm measuring similarity two sequences may vary time speed instance similarities walking patterns would detected even one video person walking slowly another walking quickly even accelerations deceleration course one observation dtw applied video audio graphics – indeed data turned linear representation analyzed dtw well-known application automatic speech recognition cope different speaking speeds general method allows computer find optimal match two given sequences e.g. time series certain restrictions sequences warped non-linearly match sequence alignment method often used context hidden markov models neural networks emerged attractive acoustic modeling approach asr late 1980s since neural networks used many aspects speech recognition phoneme classification isolated word recognition audiovisual speech recognition audiovisual speaker recognition speaker adaptation neural networks make fewer explicit assumptions feature statistical properties hmms several qualities making attractive recognition models speech recognition used estimate probabilities speech feature segment neural networks allow discriminative training natural efficient manner however spite effectiveness classifying short-time units individual phonemes isolated words early neural networks rarely successful continuous recognition tasks limited ability model temporal dependencies one approach limitation use neural networks pre-processing feature transformation dimensionality reduction step prior hmm based recognition however recently lstm related recurrent neural networks rnns time delay neural networks tdnn demonstrated improved performance area deep neural networks denoising autoencoders also investigation deep feedforward neural network dnn artificial neural network multiple hidden layers units input output layers similar shallow neural networks dnns model complex non-linear relationships dnn architectures generate compositional models extra layers enable composition features lower layers giving huge learning capacity thus potential modeling complex patterns speech data success dnns large vocabulary speech recognition occurred 2010 industrial researchers collaboration academic researchers large output layers dnn based context dependent hmm states constructed decision trees adopted recent overview articles one fundamental principle deep learning away hand-crafted feature engineering use raw features principle first explored successfully architecture deep autoencoder raw spectrogram linear filter-bank features showing superiority mel-cepstral features contain stages fixed transformation spectrograms true raw features speech waveforms recently shown produce excellent larger-scale speech recognition results since 2014 much research interest end-to-end asr traditional phonetic-based i.e. hmm-based model approaches required separate components training pronunciation acoustic language model end-to-end models jointly learn components speech recognizer valuable since simplifies training process deployment process example n-gram language model required hmm-based systems typical n-gram language model often takes several gigabytes memory making impractical deploy mobile devices consequently modern commercial asr systems google apple 2017 deployed cloud require network connection opposed device locally first attempt end-to-end asr connectionist temporal classification ctc -based systems introduced alex graves google deepmind navdeep jaitly university toronto 2014 model consisted recurrent neural networks ctc layer jointly rnn-ctc model learns pronunciation acoustic model together however incapable learning language due conditional independence assumptions similar hmm consequently ctc models directly learn map speech acoustics english characters models make many common spelling mistakes must rely separate language model clean transcripts later baidu expanded work extremely large datasets demonstrated commercial success chinese mandarin english 2016 university oxford presented lipnet first end-to-end sentence-level lip reading model using spatiotemporal convolutions coupled rnn-ctc architecture surpassing human-level performance restricted grammar dataset large-scale cnn-rnn-ctc architecture presented 2018 google deepmind achieving 6 times better performance human experts alternative approach ctc-based models attention-based models attention-based asr models introduced simultaneously chan et al carnegie mellon university google brain bahdanau et al university montreal 2016 model named listen attend spell las literally listens acoustic signal pays attention different parts signal spells transcript one character time unlike ctc-based models attention-based models conditional-independence assumptions learn components speech recognizer including pronunciation acoustic language model directly means deployment need carry around language model making practical deployment onto applications limited memory end 2016 attention-based models seen considerable success including outperforming ctc models without external language model various extensions proposed since original las model latent sequence decompositions lsd proposed carnegie mellon university mit google brain directly emit sub-word units natural english characters university oxford google deepmind extended las watch listen attend spell wlas handle lip reading surpassing human-level performance typically manual control input example means finger control steering-wheel enables speech recognition system signalled driver audio prompt following audio prompt system listening window may accept speech input recognition simple voice commands may used initiate phone calls select radio stations play music compatible smartphone mp3 player music-loaded flash drive voice recognition capabilities vary car make model recent car models offer natural-language speech recognition place fixed set commands allowing driver use full sentences common phrases systems therefore need user memorize set fixed command words health care sector speech recognition implemented front-end back-end medical documentation process front-end speech recognition provider dictates speech-recognition engine recognized words displayed spoken dictator responsible editing signing document back-end deferred speech recognition provider dictates digital dictation system voice routed speech-recognition machine recognized draft document routed along original voice file editor draft edited report finalized deferred speech recognition widely used industry currently one major issues relating use speech recognition healthcare american recovery reinvestment act 2009 arra provides substantial financial benefits physicians utilize emr according meaningful use standards standards require substantial amount data maintained emr commonly referred electronic health record ehr use speech recognition naturally suited generation narrative text part radiology/pathology interpretation progress note discharge summary ergonomic gains using speech recognition enter structured discrete data e.g. numeric values codes list controlled vocabulary relatively minimal people sighted operate keyboard mouse significant issue ehrs expressly tailored take advantage voice-recognition capabilities large part clinician interaction ehr involves navigation user interface using menus tab/button clicks heavily dependent keyboard mouse voice-based navigation provides modest ergonomic benefits contrast many highly customized systems radiology pathology dictation implement voice macros use certain phrases – e.g. normal report automatically fill large number default values and/or generate boilerplate vary type exam – e.g. chest x-ray vs. gastrointestinal contrast series radiology system alternative navigation hand cascaded use speech recognition information extraction studied way fill handover form clinical proofing sign-off results encouraging paper also opens data together related performance benchmarks processing software research development community studying clinical documentation language-processing prolonged use speech recognition software conjunction word processors shown benefits short-term-memory restrengthening brain avm patients treated resection research needs conducted determine cognitive benefits individuals whose avms treated using radiologic techniques substantial efforts devoted last decade test evaluation speech recognition fighter aircraft particular note us program speech recognition advanced fighter technology integration afti /f-16 aircraft f-16 vista program france mirage aircraft programs uk dealing variety aircraft platforms programs speech recognizers operated successfully fighter aircraft applications including setting radio frequencies commanding autopilot system setting steer-point coordinates weapons release parameters controlling flight display working swedish pilots flying jas-39 gripen cockpit englund 2004 found recognition deteriorated increasing g-loads report also concluded adaptation greatly improved results cases introduction models breathing shown improve recognition scores significantly contrary might expected effects broken english speakers found evident spontaneous speech caused problems recognizer might expected restricted vocabulary proper syntax could thus expected improve recognition accuracy substantially eurofighter typhoon currently service uk raf employs speaker-dependent system requiring pilot create template system used safety-critical weapon-critical tasks weapon release lowering undercarriage used wide range cockpit functions voice commands confirmed visual and/or aural feedback system seen major design feature reduction pilot workload even allows pilot assign targets aircraft two simple voice commands wingmen five commands speaker-independent systems also developed test f35 lightning ii jsf alenia aermacchi m-346 master lead-in fighter trainer systems produced word accuracy scores excess 98 problems achieving high recognition accuracy stress noise pertain strongly helicopter environment well jet fighter environment acoustic noise problem actually severe helicopter environment high noise levels also helicopter pilot general wear facemask would reduce acoustic noise microphone substantial test evaluation programs carried past decade speech recognition systems applications helicopters notably u.s. army avionics research development activity avrada royal aerospace establishment rae uk work france included speech recognition puma helicopter also much useful work canada results encouraging voice applications included control communication radios setting navigation systems control automated target handover system fighter applications overriding issue voice helicopters impact pilot effectiveness encouraging results reported avrada tests although represent feasibility demonstration test environment much remains done speech recognition overall speech technology order consistently achieve performance improvements operational settings training air traffic controllers atc represents excellent application speech recognition systems many atc training systems currently require person act pseudo-pilot engaging voice dialog trainee controller simulates dialog controller would conduct pilots real atc situation speech recognition synthesis techniques offer potential eliminate need person act pseudo-pilot thus reducing training support personnel theory air controller tasks also characterized highly structured speech primary output controller hence reducing difficulty speech recognition task possible practice rarely case faa document 7110.65 details phrases used air traffic controllers document gives less 150 examples phrases number phrases supported one simulation vendors speech recognition systems excess 500,000 usaf usmc us army us navy faa well number international atc training organizations royal australian air force civil aviation authorities italy brazil canada currently using atc simulators speech recognition number different vendors asr commonplace field telephony becoming widespread field computer gaming simulation telephony systems asr predominantly used contact centers integrating ivr systems despite high level integration word processing general personal computing field document production asr seen expected increases use improvement mobile processor speeds made speech recognition practical smartphones speech used mostly part user interface creating predefined custom speech commands language learning speech recognition useful learning second language teach proper pronunciation addition helping person develop fluency speaking skills students blind see blindness education low vision benefit using technology convey words hear computer recite well use computer commanding voice instead look screen keyboard students physically disabled suffer repetitive strain injury/other injuries upper extremities relieved worry handwriting typing working scribe school assignments using speech-to-text programs also utilize speech recognition technology freely enjoy searching internet using computer home without physically operate mouse keyboard speech recognition allow students learning disabilities become better writers saying words aloud increase fluidity writing alleviated concerns regarding spelling punctuation mechanics writing also see learning disability use voice recognition software conjunction digital audio recorder personal computer running word-processing software proven positive restoring damaged short-term-memory capacity stroke craniotomy individuals people disabilities benefit speech recognition programs individuals deaf hard hearing speech recognition software used automatically generate closed-captioning conversations discussions conference rooms classroom lectures and/or religious services speech recognition also useful people difficulty using hands ranging mild repetitive stress injuries involve disabilities preclude using conventional computer input devices fact people used keyboard lot developed rsi became urgent early market speech recognition speech recognition used deaf telephony voicemail text relay services captioned telephone individuals learning disabilities problems thought-to-paper communication essentially think idea processed incorrectly causing end differently paper possibly benefit software technology bug proof also whole idea speak text hard intellectually disabled person due fact rare anyone tries learn technology teach person disability type technology help dyslexia disabilities still question effectiveness product problem hindering effective although kid may able say word depending clear say technology may think saying another word input wrong one giving work fix causing take time fixing wrong word performance speech recognition systems usually evaluated terms accuracy speed accuracy usually rated word error rate wer whereas speed measured real time factor measures accuracy include single word error rate swer command success rate csr speech recognition machine complex problem however vocalizations vary terms accent pronunciation articulation roughness nasality pitch volume speed speech distorted background noise echoes electrical characteristics accuracy speech recognition may vary following mentioned earlier article accuracy speech recognition may vary depending following factors discontinuous speech full sentences separated silence used therefore becomes easier recognize speech well isolated speech continuous speech naturally spoken sentences used therefore becomes harder recognize speech different isolated discontinuous speech constraints often represented grammar speech recognition multi-levelled pattern recognition task e.g known word pronunciations legal word sequences compensate errors uncertainties lower level telephone speech sampling rate 8000 samples per second computed every 10 ms one 10 ms section called frame analysis four-step neural network approaches explained information sound produced air medium vibration register ears machines receivers basic sound creates wave two descriptions amplitude strong frequency often vibrates per second speech recognition become means attack theft accidental operation example activation words like alexa spoken audio video broadcast cause devices homes offices start listening input inappropriately possibly take unwanted action voice-controlled devices also accessible visitors building even outside building heard inside attackers may able gain access personal information like calendar address book contents private messages documents may also able impersonate user send messages make online purchases two attacks demonstrated use artificial sounds one transmits ultrasound attempt send commands without nearby people noticing adds small inaudible distortions speech music specially crafted confuse specific speech recognition system recognizing music speech make sounds like one command human sound like different command system popular speech recognition conferences held year two include speechtek speechtek europe icassp interspeech/eurospeech ieee asru conferences field natural language processing acl naacl emnlp hlt beginning include papers speech processing important journals include ieee transactions speech audio processing later renamed ieee transactions audio speech language processing since sept 2014 renamed ieee/acm transactions audio speech language processing—after merging acm publication computer speech language speech communication books like fundamentals speech recognition lawrence rabiner useful acquire basic knowledge may fully date 1993 another good source statistical methods speech recognition frederick jelinek spoken language processing 2001 xuedong huang etc computer speech manfred r. schroeder second edition published 2004 speech processing dynamic optimization-oriented approach published 2003 li deng doug o'shaughnessey updated textbook speech language processing 2008 jurafsky martin presents basics state art asr speaker recognition also uses features front-end processing classification techniques done speech recognition comprehensive textbook fundamentals speaker recognition depth source date details theory practice good insight techniques used best modern systems gained paying attention government sponsored evaluations organised darpa largest speech recognition-related project ongoing 2007 gale project involves speech recognition translation components good accessible introduction speech recognition technology history provided general audience book voice machine building computers understand speech roberto pieraccini 2012 recent book speech recognition automatic speech recognition deep learning approach publisher springer written microsoft researchers d. yu l. deng published near end 2014 highly mathematically oriented technical detail deep learning methods derived implemented modern speech recognition systems based dnns related deep learning methods related book published earlier 2014 deep learning methods applications l. deng d. yu provides less technical methodology-focused overview dnn-based speech recognition 2009–2014 placed within general context deep learning applications including speech recognition also image recognition natural language processing information retrieval multimodal processing multitask learning terms freely available resources carnegie mellon university sphinx toolkit one place start learn speech recognition start experimenting another resource free copyrighted htk book accompanying htk toolkit recent state-of-the-art techniques kaldi toolkit used 2017 mozilla launched open source project called common voice gather big database voices would help build free speech recognition project deepspeech available free github using google open source platform tensorflow commercial cloud based speech recognition apis broadly available aws azure ibm gcp demonstration on-line speech recognizer available cobalt webpage software resources see list speech recognition software
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Computational linguistics
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link capacity adjustment scheme link capacity adjustment scheme lcas method dynamically increase decrease bandwidth virtual concatenated containers lcas protocol specified itu-t g.7042 allows on-demand increase decrease bandwidth virtual concatenated group hitless manner brings bandwidth-on-demand capability data clients like ethernet mapped tdm containers lcas also able temporarily remove failed members virtual concatenation group failed member automatically cause decrease bandwidth repair bandwidth increase hitless fashion together diverse routing provides survivability data traffic without requiring excess protection bandwidth allocation
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Internet protocols
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mvel mvflex expression language mvel hybrid dynamic/statically typed embeddable expression language runtime java platform originally started utility language application framework project developed completely independently mvel typically used exposing basic logic end-users programmers configuration xml files annotations may also used parse simple javabean expressions runtime allows mvel expressions executed either interpretively pre-compilation process support runtime bytecode generation remove overhead since mvel meant augment java-based software borrows syntax directly java programming language minor differences additional capabilities example side effect mvel typing model treats class method references regular variables possible use class function pointers static methods mvel also allows collections represented folds projections lisp-like syntax mvel relies java namespaces classes possess ability declare namespaces classes example quicksort algorithm implemented mvel 2.0 demonstrating scripting capabilities language
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Programming language topics
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backus–naur form computer science backus–naur form backus normal form bnf notation technique context-free grammars often used describe syntax languages used computing computer programming languages document formats instruction sets communication protocols applied wherever exact descriptions languages needed instance official language specifications manuals textbooks programming language theory many extensions variants original backus–naur notation used exactly defined including extended backus–naur form ebnf augmented backus–naur form abnf idea describing structure language using rewriting rules traced back least work pāṇini ancient indian sanskrit grammarian revered scholar hinduism lived sometime 7th 4th century bce notation describe sanskrit word structure notation equivalent power backus many similar properties western society grammar long regarded subject teaching rather scientific study descriptions informal targeted practical usage first half 20th century linguists leonard bloomfield zellig harris started attempts formalize description language including phrase structure meanwhile string rewriting rules formal logical systems introduced studied mathematicians axel thue 1914 emil post 1920s–40s alan turing 1936 noam chomsky teaching linguistics students information theory mit combined linguistics mathematics taking essentially thue formalism basis description syntax natural language also introduced clear distinction generative rules context-free grammars transformation rules 1956 john backus programming language designer ibm proposed metalanguage metalinguistic formulas describe syntax new programming language ial known today algol 58 1959 notation first used algol 60 report bnf notation chomsky context-free grammars apparently backus familiar chomsky work proposed backus formula defined classes whose names enclosed angle brackets example codice_1 names denotes class basic symbols development algol led algol 60 committee 1963 report peter naur called backus notation backus normal form donald knuth argued bnf rather read backus–naur form normal form conventional sense unlike instance chomsky normal form name pāṇini backus form also suggested view fact expansion backus normal form may accurate pāṇini independently developed similar notation earlier bnf described peter naur algol 60 report metalinguistic formula another example algol 60 report illustrates major difference bnf metalanguage chomsky context-free grammar metalinguistic variables require rule defining formation formation may simply described natural language within brackets following algol 60 report section 2.3 comments specification exemplifies works purpose including text among symbols program following comment conventions hold equivalence meant three structures shown left column may replaced occurrence outside strings symbol shown line right column without effect action program naur changed two backus symbols commonly available characters := symbol originally ≡ symbol originally word bar expr := term expr addop term first symbol alternative may class defined repetition explained naur function specifying alternative sequence recursively begin previous alternative repeated number times example codice_3 defined codice_4 followed number codice_5 later metalanguages schorre meta ii bnf recursive repeat construct replaced sequence operator target language symbols defined using quoted strings codice_6 codice_7 bracket removed mathematical grouping codice_8 added codice_3 rule would appear meta ii expr term '+ term .out 'add '- term .out 'sub changes made meta ii derivative programming languages able define extend metalanguage ability use natural language description metalinguistic variable language construct description lost many spin-off metalanguages inspired bnf see meta ii tree-meta metacompiler bnf class describes language construct formation formation defined pattern action forming pattern class name expr described natural language codice_4 followed sequence codice_5 class abstraction talk independent formation talk term independent definition added subtracted expr talk term specific data type expr evaluated specific combinations data types even reordering expression group data types evaluation results mixed types natural-language supplement provided specific details language class semantics used compiler implementation programmer writing algol program natural-language description supplemented syntax well integer rule good example natural metalanguage used describe syntax integer := digit integer digit specifics white space far rule states could space digits natural language complement bnf metalanguage explaining digit sequence white space digits english one possible natural languages translations algol reports available many natural languages origin bnf important impact programming language development period immediately following publication algol 60 report bnf basis many compiler-compiler systems directly used bnf like syntax directed compiler algol 60 developed edgar t. irons compiler building system developed brooker morris others changed programming language schorre metacompilers made programming language changes codice_12 became symbol identifiers dropping enclosing using quoted strings symbols target language arithmetic like grouping provided simplification removed using classes grouping value meta ii arithmetic expression rule shows grouping use output expressions placed meta ii rule used output code labels assembly language rules meta ii equivalent class definitions bnf unix utility yacc based bnf code production similar meta ii yacc commonly used parser generator roots obviously bnf bnf today one oldest computer-related languages still use bnf specification set derivation rules written symbol nonterminal __expression__ consists one sequences symbols sequences separated vertical bar indicating choice whole possible substitution symbol left symbols never appear left side terminals hand symbols appear left side non-terminals always enclosed pair := means symbol left must replaced expression right example consider possible bnf u.s. postal address opt-suffix-part := sr. jr. roman-numeral translates english note many things format first-name apartment specifier zip-code roman numeral left unspecified necessary may described using additional bnf rules bnf syntax may represented bnf like following note empty string original bnf use quotes shown codice_13 rule assumes whitespace necessary proper interpretation rule codice_14 represents appropriate line-end specifier ascii carriage-return line-feed depending operating system codice_15 codice_16 substituted declared rule name/label literal text respectively u.s. postal address example entire block-quote syntax line unbroken grouping lines rule example one rule begins codice_17 part rule aside line-end expression consists two lists separated pipe codice_18 two lists consists terms three terms two terms respectively term particular rule rule-name many variants extensions bnf generally either sake simplicity succinctness adapt specific application one common feature many variants use regular expression repetition operators codice_19 codice_20 extended backus–naur form ebnf common one another common extension use square brackets around optional items although present original algol 60 report instead introduced years later ibm pl/i definition notation universally recognised augmented backus–naur form abnf routing backus–naur form rbnf extensions commonly used describe internet engineering task force ietf protocols parsing expression grammars build bnf regular expression notations form alternative class formal grammar essentially analytic rather generative character many bnf specifications found online today intended human-readable non-formal often include many following syntax rules extensions
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Programming language topics
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rmx operating system irmx real-time operating system designed specifically use intel 8080 intel 8086 family processors acronym real-time multitasking executive intel developed irmx 1970s originally released rmx/80 1976 rmx/86 1980 support create demand processors multibus system platforms functional specification rmx/86 authored bruce schafer miles lewitt completed summer 1978 soon intel relocated entire multibus business santa clara california aloha oregon schafer lewitt went manage one two teams developed rmx/86 product release schedule 1980 effective 2000 irmx supported maintained licensed worldwide tenasys corporation exclusive licensing arrangement intel irmx layered design containing kernel nucleus basic i/o system extended i/o system human interface installation need include components required intertask synchronization communication subsystems filesystem extended memory management command shell etc native filesystem specific irmx many similarities original unix v6 filesystem 14 character path name components file nodes sector lists application readable directories etc irmx supports multiple processes known jobs rmx parlance multiple threads supported within process task addition interrupt handlers threads exist run response hardware interrupts thus irmx multi-processing multi-threaded pre-emptive real-time operating system rtos following list commands supported irmx 86 several variations irmx developed since original introduction intel 8080 irmx ii iii irmx-86 irmx-286 dos-rmx irmx windows recently intime many original variants irmx still use irmx iii irmx windows intime currently supported development new real-time applications three supported variants irmx require intel 80386 equivalent higher processor run significant architectural difference intime rtos irmx variants support address segments see x86 memory segmentation original 8086 family processors relied heavily segment registers overcome limitations associated addressing large amounts memory via 16-bit registers irmx operating system compilers developed irmx include features exploit segmented addressing features original x86 architecture intime variant irmx include explicit support segmentation opting instead support simpler common 32-bit flat addressing scheme note despite fact native processes written intime operate using unsegmented flat-mode addressing possible port run older irmx applications use segmented addressing intime kernel intel introduced intel 80386 processor addition expanding irmx rtos support 32-bit registers irmx iii also included support four distinct protection rings named rings 0 3 describe protected-mode mechanism intel 32-bit architecture practice systems ever used rings 0 3 implement protection schemes ii iii -286 -86 variants intended standalone real-time operating systems number development utilities applications made irmx compilers pl/m fortran c editor aedit process data acquisition applications cross compilers hosted vax/vms system also made available intel irmx iii still supported today used core technology newer real-time virtualization rtos products including irmx windows intime irmx iii intel multibus hardware used majority core systems clscs london underground central line signals control system supplied westinghouse invensys commissioned late 1990s central line automatic train operation line automatic train protection trackside train borne equipment use irmx automatic train supervision elements use mix irmx multibus solaris sparc computers 16 irmx local site computers distributed along central line together 6 central irmx computers control centre 22 irmx computers dual redundant irmx clscs continues full operation oslo metro uses similar although less complex westinghouse-supplied irmx control system central common tunnel tracks expected decommissioned 2011 dos-rmx variant standalone irmx operating system designed allow two operating systems share single hardware platform simplest terms ms-dos irmx operate concurrently single ibm pc compatible computer irmx tasks processes scheduling priority dos kernel interrupts applications irmx events e.g. hardware interrupts pre-empt dos kernel ensure tasks respond real-time events time-deterministic manner functional sense dos-rmx predecessor irmx windows intime practice dos-rmx appears tsr ms-dos kernel loaded tsr irmx takes cpu changing protected mode running dos virtual machine within rmx task combination provides rmx real-time functionality well full ms-dos services like dos-rmx system provides hybrid mixture services capabilities defined ms-dos microsoft windows irmx inter-application communication via enhanced windows dde capability allows rmx tasks communicate windows processes irmx windows originally intended use combination 16-bit version microsoft windows 2002 irmx windows reintroduced adding rmx personalities intime rtos windows allowing used conjunction 32-bit protected-mode versions windows windows nt windows 2000 etc. like irmx predecessors intime real-time operating system like dos-rmx irmx windows runs concurrently general-purpose operating system single hardware platform intime 1.0 originally introduced 1997 conjunction windows nt operating system since upgraded include support subsequent protected-mode microsoft windows platforms including windows vista windows 7 intime also used stand-alone rtos intime binaries able run unchanged running stand-alone node intime rtos unlike windows intime run intel 80386 equivalent processor current versions windows operating system generally require least pentium level processor order boot execute introduction intime 3.0 included several important enhancements among support multi-core processors ability debug real-time processes intime kernel using microsoft visual studio intime smp operating system thus support multi-core processors restricted special form asymmetric multiprocessing used multi-core processor intime configured run one cpu core windows runs remaining processor core use cases viewed tenasys website
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Operating systems
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apple a10 apple a10 fusion 64-bit arm-based system chip soc designed apple inc. manufactured tsmc first appeared iphone 7 7 plus introduced september 7 2016 addition a10 chip processor sixth-generation ipad seventh-generation ipod touch a10 first apple-designed quad-core soc two high-performance cores two energy-efficient cores apple states 40 greater cpu performance 50 greater graphics performance compared predecessor apple a9 a10 internally t8010 built tsmc 16 nm finfet process contains 3.3 billion transistors including gpu caches die size 125 mm features two apple-designed 64-bit 2.34 ghz armv8-a cores called hurricane die size 4.18 mm first apple-produced quad-core soc two high-performance cores designed demanding tasks like gaming also featuring two energy-efficient apple-designed 64-bit cores codenamed zephyr 0.78 mm normal tasks configuration similar arm big.little technology however unlike implementations big.little snapdragon 820 exynos 8890 one core type active time either high-performance low-power cores thus a10 fusion appears software benchmarks dual core chip apple claims high-performance cores 40 faster apple previous a9 processor two high-efficiency cores consume 20 power high performance hurricane cores used performing simple tasks checking email new performance controller decides realtime pair cores run given task order optimize performance battery life a10 l1 cache 64 kb data 64 kb instructions l2 cache 3 mb shared cores 4 mb l3 cache services entire soc new 6-core gpu built a10 chip 50 faster consuming 66 power a9 predecessor analysis suggested apple kept gt7600 used apple a9 replaced portions powervr based gpu proprietary designs changes appear using lower half-precision floating-point numbers allowing higher-performance lower power consumption embedded a10 m10 motion coprocessor a10 also includes new image processor apple says twice throughput prior image processor a10 adds hardware encoding heif hevc a10 packaged new info packaging tsmc reduces height package package also four lpddr4 ram chips integrating 2 gb ram iphone 7 ipad 6th generation ipod touch 7th generation 3 gb iphone 7 plus
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Computer architecture
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arcus ii silent symphony
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Computer architecture
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trsdos trsdos stood tandy radio shack disk operating system operating system tandy trs-80 line 8-bit zilog z80 microcomputers sold radio shack late 1970s early 1980s tandy manuals recommended pronounced triss-doss trsdos confused tandy dos version ms-dos licensed microsoft tandy x86 line personal computers pcs original trs-80 model 1977 trsdos primarily way extending mbasic basic rom additional i/o input/output commands worked disk files rather cassette tapes used non-disk model systems later disk-equipped model iii computers used completely different version trsdos radio shack culminated 1981 trsdos version 1.3 1983 disk-equipped trs-80 model 4 computers used trsdos version 6 development model iii ldos logical systems inc last updated 1987 released ls-dos 6.3 completely unrelated version trsdos radio shack trs-80 model ii professional computer 1979 also based z80 equipped 8 inch disk drives later machines line models 12 16 6000 used z80 alternate cpu main motorola 68000 chip could run version trsdos backwards compatibility older z80 applications software model trsdos supports four floppy mini-diskette drives use 5¼-inch diskettes capacity 89kb later 160kb formatted double-density sectors versions trsdos models 4 ii support double-density double sided floppy diskettes formatted 80 tracks per side including 3.5 inch microfloppy drives available 1985 drives numbered 0 3 system diskettes contain trsdos code utilities present drive 0 times trsdos uses overlays satisfy system requests disk directories maintained memory tandy corporation trs-80 microcomputer disk drive disk operating system release first version trsdos randy cook buggy others wrote alternatives including newdos ldos disputes cook ownership source code tandy hired logical systems ldos developer continue trsdos development trsdos 6 shipped trs-80 model 4 1983 identical ldos 6.00 typical trsdos utilities although ms-dos owes heritage closely cp/m thence tops-10 many file manipulation commands similar trsdos comparison cp/m command copying files called pip pun pip printers chain copy centers era acronym standing peripheral interchange program
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Operating systems
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tarantool tarantool open-source nosql database management system lua application server maintains databases memory ensures crash resistance write-ahead logging includes lua interpreter interactive console also accepts connections programs several languages mail.ru one largest internet companies russia started project 2008 part development moy mir world social network 2010 project head hired former technical lead mysql open-source contributors active especially area external-language connectors c perl php python ruby node.js tarantool became part mail.ru backbone used dynamic content user sessions unsent instant messages task queues caching layer traditional relational databases mysql postgresql 2014 tarantool also adopted social network services badoo odnoklassniki latter affiliated mail.ru since 2010 june 2014 researchers polytechnic institute coimbra university coimbra portugal conducted first formal independent performance test nosql systems included tarantool tests used standard ycsb benchmark nosql systems cassandra hbase oracle nosql redis voldemort scalaris elasticsearch mongodb orientdb data maintained memory ram data persistence ensured write-ahead logging snapshotting reasons industry observers compared tarantool membase replication asynchronous failover getting one tarantool server take another possible either replica server hot standby server locks tarantool uses lua-style coroutines asynchronous i/o result application programs stored procedures must written cooperative multitasking mind rather popular preemptive multitasking database storage basic unit tuple tuples tuple sets handle role rows tables relational databases tuples arbitrary number fields fields need names every tuple database one unique null primary key one secondary keys enabled immediate lookup via indexes supported index types binary tree hash bitmap r-tree spatial fields tuple type-agnostic specific numeric string data types users may insert update delete select granted appropriate privileges tarantool 2017 introduced optional on-disk storage engine allows databases larger memory size tarantool 2019 introduced optional sql interface complies mandatory features official sql standard tarantool comes part official distributions linux distros debian fedora ubuntu tarantool organization also supplies downloads linux distributions os x freebsd tarantool extended modules installed using luarocks includes selection extension rocks
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Distributed computing architecture
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yubikey yubikey hardware authentication device manufactured yubico supports one-time passwords public-key encryption authentication universal 2nd factor u2f fido2 protocols developed fido alliance allows users securely log accounts emitting one-time passwords using fido-based public/private key pair generated device yubikey also allows storing static passwords use sites support one-time passwords facebook uses yubikey employee credentials google supports employees users password managers support yubikey yubico also manufactures security key device similar yubikey focused public-key authentication yubikey implements hmac-based one-time password algorithm hotp time-based one-time password algorithm totp identifies keyboard delivers one-time password usb hid protocol yubikey neo yubikey 4 include protocols openpgp card using 2048-bit rsa elliptic curve cryptography ecc p256 p384 near field communication nfc fido u2f yubikey allows users sign encrypt decrypt messages without exposing private keys outside world 4th generation yubikey launched november 16 2015 support openpgp 4096-bit rsa keys pkcs 11 support piv smart cards feature allows code signing docker images founded 2007 ceo stina ehrensvärd yubico private company offices palo alto seattle stockholm yubico cto jakob ehrensvärd lead author original strong authentication specification became known universal 2nd factor u2f yubico founded 2007 began offering pilot box developers november year original yubikey product shown annual rsa conference april 2008 robust yubikey ii model launched 2009 yubikey ii later models two slots available storing two distinct configurations separate aes secrets settings authenticating first slot used briefly pressing button device second slot gets used holding button 2 5 seconds 2010 yubico began offering yubikey oath yubikey rfid models yubikey oath added ability generate 6- 8-character one-time passwords using protocols initiative open authentication oath addition 32-character passwords used yubico otp authentication scheme yubikey rfid model included oath capability plus also included mifare classic 1k radio-frequency identification chip though separate device within package could configured normal yubico software usb connection yubico announced yubikey nano february 2012 miniaturized version standard yubikey designed would fit almost entirely inside usb port expose small touch pad button later models yubikey also available standard nano sizes 2012 also saw introduction yubikey neo improved upon previous yubikey rfid product implementing near-field communication nfc technology integrating usb side device yubikey neo neo-n nano version device able transmit one-time passwords nfc readers part configurable url contained nfc data exchange format ndef message neo also able communicate using ccid smart-card protocol addition usb hid human interface device keyboard emulation ccid mode used piv smart card openpgp support usb hid used one-time password authentication schemes 2014 yubikey neo updated fido universal 2nd factor u2f support later year yubico released fido u2f security key specifically included u2f support none one-time password static password smart card nfc features previous yubikeys launch correspondingly sold lower price point 18 compared 25 yubikey standard 40 nano version 50 yubikey neo 60 neo-n pre-release devices issued google fido/u2f development reported yubico winusb gnubby gnubby1 april 2015 company launched yubikey edge standard nano form factors slotted neo fido u2f products feature-wise designed handle otp u2f authentication include smart card nfc support yubikey 4 family devices first launched november 2015 usb-a models standard nano sizes yubikey 4 includes features yubikey neo including increasing allowed openpgp key size 4096 bits vs. previous 2048 dropped nfc capability neo ces 2017 yubico announced expansion yubikey 4 series support new usb-c design yubikey 4c released february 13 2017 android os usb-c connection one-time password feature supported android os yubikey features currently supported including universal 2nd factor u2f 4c nano version became available september 2017 april 2018 company brought security key yubico first device implement new fido2 authentication protocols webauthn reached w3c candidate recommendation status march client authenticator protocol ctap still development may 2018 launch device available standard form factor usb-a connector like previous fido u2f security key blue color uses key icon button distinguished number 2 etched plastic button keyring hole also less expensive yubikey neo yubikey 4 models costing 20 per unit launch lacks otp smart card features previous devices though retains fido u2f capability used one-time passwords stored static passwords yubikey emits characters using modified hexadecimal alphabet intended independent system keyboard settings possible alphabet referred modhex modified hexadecimal consists characters cbdefghijklnrtuv corresponding hexadecimal digits 0123456789abcdef due yubikeys using raw keyboard scan codes usb hid mode problems using devices computers set different keyboard layouts dvorak recommended either use operating system features temporarily switch standard us keyboard layout similar using one-time passwords although yubikey neo later devices configured alternate scan codes match layouts n't compatible modhex character set u2f authentication yubikeys security keys bypasses problem using alternate u2fhid protocol sends receives raw binary messages instead keyboard scan codes ccid mode acts smart card reader use hid protocols yubico replaced open-source components yubikey 4 closed-source code longer independently reviewed security flaws yubico states internal external review code done yubikey neos still using open-source code may 16 2016 yubico cto jakob ehrensvärd responded open-source community concerns blog post affirming company strong open source support addressing reasons benefits updates yubikey 4 october 2017 security researchers found vulnerability known roca implementation rsa keypair generation cryptographic library used large number infineon security chips vulnerability allows attacker reconstruct private key using public key yubikey 4 yubikey 4c yubikey 4 nano devices within revisions 4.2.6 4.3.4 affected vulnerability yubico remedied issue shipping yubikey 4 devices switching different key generation function offered free replacements affected keys replacement offer ended march 31 2019 cases issue bypassed generating new keys outside yubikey importing onto device june 2019 yubico released security advisory reporting reduced randomness fips-certified devices shortly power-up company offered free replacements affected keys
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Computer security
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code wheel code wheel type copy protection used older computer games often published late 1980s early 1990s evolved original manual protection system program would require user enter specific word manual game would start continue beyond certain point system popular allowed actual media backed replaced freely retaining security increased availability photocopiers wishing distribute games simply started copying manuals well defeat measure although whole code wheels could directly photocopied component wheels could disassembled individually photocopied components could crafted together duplicate wheel contents code wheels could also copied onto paper user unlicensed copy could simply apply mathematical formula presented challenges calculate correct response suitable formula found code wheels actually made process copying easier since amount information could contain low compared manual potentially unlimited size thus code wheels rapidly phased favor regular manual protection protection based around color public access color photocopying time expensive uncommon made obsolete return protection based game media cd-roms introduced code wheel physical object consisting several circular sheets paper card different sizes fastened center creating set concentric circles game issues user set challenges symbols words identifiers instruct user manipulate wheel order reveal response single symbol word user must enter order start game entering anything expected response would result game halting performing behaviour associated unauthorised usage software example game starflight would send unbeatable police ships destroy player spaceship simple 2-ply code wheel consisted two circular sheets challenge symbols printed intervals around rim back sheet containing table responses printed fit circle front sheet series holes allowing responses viewed hole labelled challenge symbol computer would present three challenge symbols user would read response rotating front sheet first two challenge symbols aligned rim wheel read response hole indicated third challenge symbol type codewheel used large number games neuromancer cybercon 3 used code wheel printed carbon paper one usage single-ply code wheel two challenge symbols used amiga game rocket ranger player turned wheel match ranger current location read value hole corresponding location wanted fly holes simple column since mechanism player specify wanted fly impossible crackers remove game without destroying entire gameplay 3-ply code wheel used games star control fool errand retained back wheel printed responses front wheel holes added middle wheels front back contained mixture printed responses holes allowed next wheel show particular challenge symbols aligned interactive code wheels online oldgames.sk
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Computer security
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simula simula name two simulation programming languages simula simula 67 developed 1960s norwegian computing center oslo ole-johan dahl kristen nygaard syntactically fairly faithful superset algol 60 also influenced design simscript simula 67 introduced objects classes inheritance subclasses virtual procedures coroutines discrete event simulation features garbage collection also forms subtyping besides inheriting subclasses introduced simula derivatives simula considered first object-oriented programming language name suggests simula designed simulations needs domain provided framework many features object-oriented languages today simula used wide range applications simulating vlsi designs process modeling protocols algorithms applications typesetting computer graphics education influence simula often understated simula-type objects reimplemented c++ object pascal java c several languages computer scientists bjarne stroustrup creator c++ james gosling creator java acknowledged simula major influence following account based jan rune holmevik historical essay kristen nygaard started writing computer simulation programs 1957 nygaard saw need better way describe heterogeneity operation system go ideas formal computer language describing system nygaard realized needed someone computer programming skills ole-johan dahl joined work january 1962 decision linking language algol 60 made shortly may 1962 main concepts simulation language set simula born special purpose programming language simulating discrete event systems kristen nygaard invited visit eckert–mauchly computer corporation late may 1962 connection marketing new univac 1107 computer visit nygaard presented ideas simula robert bemer director systems programming univac bemer sworn algol fan found simula project compelling bemer also chairing session second international conference information processing hosted ifip invited nygaard presented paper simula -- extension algol description discrete-event networks norwegian computing center got univac 1107 august 1963 considerable discount dahl implemented simula contract univac implementation based univac algol 60 compiler simula fully operational univac 1107 january 1965 following couple years dahl nygaard spent lot time teaching simula simula spread several countries around world simula later implemented burroughs b5500 computers russian ural-16 computer 1966 c. a. r. hoare introduced concept record class construct dahl nygaard extended concept prefixing features meet requirements generalized process concept dahl nygaard presented paper class subclass declarations ifip working conference simulation languages oslo may 1967 paper became first formal definition simula 67 june 1967 conference held standardize language initiate number implementations dahl proposed unify type class concept led serious discussions proposal rejected board simula 67 formally standardized first meeting simula standards group ssg february 1968 simula influential development smalltalk later object-oriented programming languages also helped inspire actor model concurrent computation although simula supports coroutines true concurrency late sixties early seventies four main implementations simula implementations ported wide range platforms tops-10 implemented concept public protected private member variables procedures later integrated simula 87 simula 87 latest standard ported wide range platforms mainly four implementations november 2001 dahl nygaard awarded ieee john von neumann medal institute electrical electronics engineers introduction concepts underlying object-oriented programming design implementation simula 67 april 2002 received 2001 a. m. turing award association computing machinery acm citation ideas fundamental emergence object oriented programming design programming languages simula simula 67 unfortunately neither dahl nygaard could make acm turing award lecture scheduled delivered november 2002 oopsla conference seattle died june august year respectively simula research laboratory research institute named simula language nygaard held part-time position opening 2001 new computer science building university oslo named ole johan dahl house dahl honour main auditorium named simula empty computer file minimal program simula measured size source code consists one thing dummy statement however minimal program conveniently represented empty block begins executing immediately terminates language return value program example hello world program simula simula case-insensitive realistic example use classes subclasses virtual procedures example one super class glyph two subclasses char line one virtual procedure two implementations execution starts executing main program simula concept abstract classes since classes pure virtual procedures instantiated means example classes instantiated calling pure virtual procedure however produce run-time error simula supports call name jensen device easily implemented however default transmission mode simple parameter call value contrary algol used call name source code jensen device must therefore specify call name parameters compiled simula compiler another much simpler example summation function formula_1 implemented follows code uses call name controlling variable k expression u allows controlling variable used expression note simula standard allows certain restrictions controlling variable loop code therefore uses loop maximum portability following formula_2 implemented follows simula includes simulation package discrete event simulations simulation package based simula object oriented features coroutine concept sam sally andy shopping clothes share one fitting room one browsing store 12 minutes uses fitting room exclusively three minutes following normal distribution simulation fitting room experience follows main block prefixed codice_1 enabling simulation simulation package used block simulations even nested simulating someone simulations fitting room object uses queue codice_2 getting access fitting room someone requests fitting room use must wait queue codice_3 someone leaves fitting room first one released queue codice_4 accordingly removed door queue codice_5 person subclass process activity described using hold time browsing store time spent fitting room calls procedures fitting room object requesting leaving fitting room main program creates objects activates person objects put event queue main program holds 100 minutes simulated time program terminates
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Programming language topics
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snobol snobol string oriented symbolic language series computer programming languages developed 1962 1967 bell laboratories david j. farber ralph e. griswold ivan p. polonsky culminating snobol4 one number text-string-oriented languages developed 1950s 1960s others included comit trac snobol4 stands apart programming languages era patterns first-class data type i.e data type whose values manipulated ways permitted data type programming language providing operators pattern concatenation alternation later object-oriented languages javascript patterns type object admit various manipulations strings generated execution treated programs executed eval function languages snobol4 quite widely taught larger us universities late 1960s early 1970s widely used 1970s 1980s text manipulation language humanities 1980s 1990s use faded newer languages awk perl made string manipulation means regular expressions fashionable snobol4 patterns subsume bnf grammars equivalent context-free grammars powerful regular expressions regular expressions current versions awk perl fact extensions regular expressions traditional sense regular expressions unlike snobol4 patterns recursive gives distinct computational advantage snobol4 patterns recursive expressions appear perl 5.10 though released december 2007 one designers snobol ralph griswold designed successors snobol4 called sl5 icon combined backtracking snobol4 pattern matching standard algol-like structuring well adding features initial snobol language created tool used authors work symbolic manipulation polynomials written assembly language ibm 7090 simple syntax one datatype string functions declarations little error control however despite simplicity personal nature use began spread groups result authors decided extend tidy rewrote added functions standard user-defined released result snobol3 snobol2 exist short-lived intermediate development version without user-defined functions never released snobol3 became quite popular rewritten computers ibm 7090 programmers result several incompatible dialects arose snobol3 became popular authors received requests extensions language also began receive complaints incompatibility bugs versions n't written address take advantage new computers introduced late 1960s decision taken develop snobol4 many extra datatypes features based virtual machine allow improved portability across computers snobol4 language translator still written assembly language however macro features assembler used define virtual machine instructions snobol implementation language sil much improved portability language making relatively easy port virtual machine hosted translator recreating virtual instructions machine included macro assembler indeed high level language snobol4 supports number built-in data types integers limited precision real numbers strings patterns arrays tables associative arrays also allows programmer define additional data types new functions snobol4 programmer-defined data type facility advanced time—it similar earlier cobol later pascal records snobol command lines form five elements optional general subject matched pattern object present matched portion replaced object via rules replacement transfer absolute branch conditional branch dependent upon success failure subject evaluation pattern evaluation pattern match object evaluation final assignment also transfer code created compiled program run snobol pattern simple extremely complex simple pattern text string e.g abcd complex pattern may large structure describing example complete grammar computer language possible implement language interpreter snobol almost directly backus–naur form expression changes creating macro assembler interpreter completely theoretical piece hardware could take little hundred lines new instruction added single line complex snobol patterns things would impractical impossible using primitive regular expressions used pattern matching languages power derives so-called spitbol extensions since incorporated basically modern implementations original snobol 4 language although possible achieve power without part power comes side effects possible produce pattern matching operation including saving numerous intermediate/tentative matching results ability invoke user-written functions pattern match perform nearly desired processing influence ongoing direction interrupted pattern match takes even indeed change pattern matching operation patterns saved like first-class data item concatenated used within patterns used create complex sophisticated pattern expressions possible write example snobol4 pattern matches complete name international postal mailing address well beyond anything practical even attempt using regular expressions snobol4 pattern-matching uses backtracking algorithm similar used logic programming language prolog provides pattern-like constructs via dcgs algorithm makes easier use snobol logic programming language case languages snobol stores variables strings data structures single garbage-collected heap snobol rivals apl distinctiveness format programming style radically unlike standard procedural languages basic fortran c. hello world program might follows ... end simple program ask user name use output sentence ... end choose three possible outputs ... meh output hi username end love output nice meet username end hate output oh username end continue requesting input forthcoming ... namecount namecount 1 getinput output please give name namecount 1 end classic implementation pdp-10 used study compilers formal grammars artificial intelligence especially machine translation machine comprehension natural languages original implementation ibm 7090 bell labs holmdel n.j. snobol4 specifically designed portability first implementation started ibm 7094 1966 completed ibm 360 1967 rapidly ported many platforms normally implemented interpreter difficulty implementing high-level features compiler spitbol compiler provides nearly facilities interpreter provides gnat ada compiler comes package gnat.spitbol implements spitbol string manipulation semantics called within ada program file editor michigan terminal system mts provided pattern matching based snobol4 patterns several implementations currently available macro snobol4 c written phil budne free open source implementation capable running almost platform catspaw inc provided commercial implementation snobol4 language many different computer platforms including dos macintosh sun rs/6000 others implementations available free catspaw minnesota snobol4 viktors berstis closest pc implementation original ibm mainframe version even including fortran-like format statement support also free although snobol structured programming features snobol preprocessor called snostorm designed implemented 1970s fred g. swartz use michigan terminal system mts university michigan snostorm used eight fifteen sites ran mts also available university college london ucl 1982 1984 snocone andrew koenig adds block-structured constructs snobol4 language snocone self-contained programming language rather proper superset snobol4 spitbol implementation also introduced number features using traditional structured programming keywords nevertheless used provide many equivalent capabilities normally thought structured programming notably nested if/then/else type constructs features since added recent snobol4 implementations many years commercial product april 2009 spitbol released free software gnu general public license according dave farber griswold polonsky finally arrived name symbolic expression interpreter sexi common backronyms snobol 'string oriented symbolic language quasi-initialism 'string oriented symbolic language
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Programming language topics
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ambient desktop environment ambient mui-based desktop environment morphos development started 2001 david gerber main goals fully asynchronous simple fast ambient remotely resembles workbench directory opus magellan trying mix best worlds ambient strictly follow amiga workbench interface paradigm still many similarities programs called tools program attributes called tooltypes data files projects directories drawers ambient localized various languages part morphos also available separately various visual effects ambient taking advantage hardware accelerated visual effects morphos native icon format ambient png icon built-in support amiga icon formats ambient introduced special icon format called datatype icons icon simply image file renamed include .info extension icons read using amiga datatype system 2005 david gerber released ambient source code gpl developed ambient development team
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Operating systems
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side effect computer science computer science operation function expression said side effect modifies state variable value outside local environment say observable effect besides returning value main effect invoker operation state data updated outside operation may maintained inside stateful object wider stateful system within operation performed example side effects include modifying non-local variable modifying static local variable modifying mutable argument passed reference performing i/o calling side-effect functions presence side effects program behaviour may depend history order evaluation matters understanding debugging function side effects requires knowledge context possible histories degree side effects used depends programming paradigm imperative programming commonly used produce side effects update system state contrast declarative programming commonly used report state system without side effects functional programming side effects rarely used lack side effects makes easier formal verifications program functional languages standard ml scheme scala restrict side effects customary programmers avoid functional language haskell expresses side effects i/o stateful computations using monadic actions assembly language programmers must aware hidden side effects—instructions modify parts processor state mentioned instruction mnemonic classic example hidden side effect arithmetic instruction implicitly modifies condition codes hidden side effect explicitly modifies register overt effect one potential drawback instruction set hidden side effects many instructions side effects single piece state like condition codes logic required update state sequentially may become performance bottleneck problem particularly acute processors designed pipelining since 1990 out-of-order execution processor may require additional control circuitry detect hidden side effects stall pipeline next instruction depends results effects absence side effects necessary sufficient condition referential transparency referential transparency means expression function call replaced value requires expression pure say expression must deterministic always give value input side-effect free side effects caused time taken operation execute usually ignored discussing side effects referential transparency cases hardware timing testing operations inserted specifically temporal side effects e.g codice_1 codice_2 instructions change state taking amount time complete function codice_3 side effects said idempotent sequential composition codice_4 called twice list arguments second call side effects assuming procedures called end first call start second call instance consider following python code codice_5 idempotent second call codice_5 argument change visible program state codice_7 already set 5 first call set 5 second call thus keeping value note distinct idempotence function composition codice_8 example absolute value idempotent function composition one common demonstration side effect behavior assignment operator c++ example assignment returns right operand side effect assigning value variable allows syntactically clean multiple assignment operator right associates equates result assigning 3 codice_9 gets assigned codice_10 presents potential hangup novice programmers may confuse
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Programming language topics
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personal identity system personal identity system pis established 1947 register pakistani citizens personal identity system replaced national database registration authority 1972 independence pakistan prime minister liaquat ali khan launched personal identity system pis program registered managed issued national identification cards citizens pakistan muslim refugees settling pakistan
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Databases
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mybatis mybatis java persistence framework couples objects stored procedures sql statements using xml descriptor annotations mybatis free software distributed apache license 2.0 mybatis fork ibatis 3.0 maintained team includes original creators ibatis unlike orm frameworks mybatis map java objects database tables java methods sql statements mybatis lets use database functionality like stored procedures views queries complexity vendor proprietary features often good choice legacy de-normalized databases obtain full control sql execution simplifies coding compared jdbc sql statements executed single line mybatis provides mapping engine maps sql results object trees declarative way sql statements built dynamically using built-in language xml-like syntax apache velocity using velocity integration plugin mybatis integrates spring framework google guice feature allows one build business code free dependencies mybatis supports declarative data caching statement marked cacheable data retrieved database stored cache future executions statement retrieve cached data instead hitting database mybatis provides default cache implementation based java hashmap default connectors integrating oscache ehcache hazelcast memcached provides api plug cache implementations sql statements stored xml files annotations depicts mybatis mapper consists java interface mybatis annotations sentence executed follows sql statements mappings also externalized xml file follows statements also executed using mybatis api details please refer user guide available mybatis site see external links mybatis integrates spring framework module allows mybatis participate spring transactions also build mybatis mappers sessions inject beans following sample shows basic xml configuration sets mapper injects blogservice bean calling mybatis calling bean velocity language driver lets use apache velocity generate dynamic sql queries fly mybatis provides code generator mybatis generator introspect database table many tables generate mybatis artifacts needed perform crud operations create retrieve update delete eclipse plugin available preserve custom code case regeneration use eclipse plugin mybatis migrations java command line tool keeps track database schema changes managing ddl files known migrations migrations allows query current status database apply schema changes also undo also helps detect solve concurrent database schema changes made different developers mybatis project subsidiary ibatis 3.0 maintained team includes original creators ibatis project created may 19 2010 apache ibatis 3.0 published team announced development continue new name new home google code november 10 2013 project announced movement github
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Databases
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fortinet fortinet american multinational corporation headquartered sunnyvale california develops markets cybersecurity software appliances services firewalls anti-virus intrusion prevention endpoint security fortinet founded 2000 brothers ken michael xie company first product fortigate firewall later adding wireless access points sandboxing messaging security 2004 fortinet raised 90 million funding company went public november 2009 raising 156 million initial public offering 2016 fortinet released security fabric architecture included integration automation network security devices third-party vendors product later adapted include multi-cloud iot sd-wan capabilities prior fortinet ken xie founded served executive netscreen michael xie served executive servegate 2000 co-founded appligation inc company renamed apsecure december 2000 later renamed fortinet based phrase fortified networks 2004 amid fundraising fortinet netscreen acquired juniper networks 4 billion fortinet spent two years research development introducing first product fortigate 2002 company raised 13 million private funding 2000 early 2003 additional 30 million financing raised august 2003 followed 50 million march 2004 fortinet first channel program established october 2003 company began distributing products canada december 2003 westcon canada uk february 2004 norwood adam 2004 fortinet offices asia europe north america april 2005 german court issued preliminary injunction fortinet uk subsidiary relation source code gpl-licensed elements dispute ended month later fortinet agreed make source code available upon request fortinet became profitable third quarter 2008 late year company acquired database security auditing intellectual property iplocks extended job offers company 28 employees august 2009 acquired intellectual property assets woven systems ethernet switching company according market research firm idc november 2009 held 15 percent unified threat management market also 2009 crn magazine survey-based annual report card arc placed fortinet first network security hardware seventh 2007 november 2009 fortinet initial public offering wherein company planned raise 52.4 million sale 5.8 million shares 6 million shares also sold stockholders first day trading fortinet increased share price 9 12.50 price increased market 16.62 end first day trading company raised 156 million financing 2010 fortinet 324 million annual revenues held largest share market according idc july 2013 fortinet made changes reseller program security operations center soc box order provide monthly financing options managed security service vendors less experience less capital program previously reorganized 2006 enterprise companies fortinet made three notable acquisitions 2012 2015 company acquired app-hosting service xdn formerly known 3crowd december 2012 coyote point 2013 wi-fi hardware company meru networks 2015 june 2016 fortinet acquired security monitoring analytics software vendor accelops july 2014 fortinet announced technical certification program called network security expert nse included eight levels certification later march 2016 company launched network security academy help fill open cyber security jobs u.s. fortinet donated equipment provided information universities help train students jobs field also 2016 fortinet launched program called fortivet recruit military veterans cybersecurity jobs january 2017 announced philip quade former member nsa would become company chief information officer end 2017 fortinet reported 416.7 million revenue 15 percent increase previous year december 31 2017 fortinet 467 u.s. foreign-issued patents 291 pending june 2018 fortinet acquired bradford networks maker access control iot security solutions january 2019 announced fortinet founder ken xie would participate annual world economic forum held davos switzerland fortinet released first product fortigate firewall 2002 followed anti-spam anti-virus software fortigate updated use application-specific integrated circuit asic architecture fortinet products later merged network security including firewalls anti-spam anti-virus software one appliance april 2016 fortinet began building security fabric architecture multiple network security products could communicate one platform later year company added security information event management siem products analyzed hardware software security alerts high gigabit port density consolidated network security features mid-sized businesses enterprise branch locations addition cloud security september 2016 company announced would integrate siem products security systems vendors 2017 fortinet announced addition switches access points analyzers sandboxes cloud capabilities security fabric addition endpoints firewalls later 2017 fortinet created standalone subsidiary fortinet federal develop cybersecurity products government agencies fortinet historically received security effectiveness certifications nss labs gartner research consulting firm ranked fortinet within top three companies magic quadrant enterprise network firewalls measures market trends direction july 2018 company launched fortigate sd-wan proprietary sd-wan service fortigate sd-wan included within gartner magic quadrant wan edge infrastructure later year later 2018 fortinet released fortiguard ai better detect new unknown threats also announced 6.0 version fortios security operating system enhanced centralized management expanded cloud capabilities may 2004 trend micro competing cyber security defense company filed legal complaint fortinet though international trade commission initially ruled fortinet trend micro patents center dispute later declared invalid 2010 2005 fortinet responded questions related employee relationship burma prime minister use fortinet appliances internet censorship myanmar fortinet stated products sold third party resellers acknowledged us embargoes 2005 fortinet created fortiguard labs internal security research team 2008 fortinet researchers sent report facebook highlighting widget zango appeared tricking users downloading spyware 2014 fortinet four research development centers asia well others us canada france march 2014 fortinet founded cyber threat alliance cta palo alto networks order share security threat data across vendors later joined mcafee symantec 2015 cta published white paper cryptowall ransomware detailed attackers obtained 325 million ransoms paid victims regain access files april 2015 fortinet provided threat intelligence interpol order help apprehend ringleader several online scams based nigeria scams resulted compromise business emails ceo fraud cost one business 15 million following year march 2016 fortinet technology company cisco joined nato data-sharing agreement improve information security capabilities january 2017 fortinet worked interpol conduct investigation web security several southeast asian countries investigation identified compromised websites including government-operated web servers later month fortinet researchers discovered spyware scammed victims impersonating irs also 2017 researchers helped identify malware called rootnik ransomware called macransom targeted android macos systems respectively 2018 fortinet entered information-sharing agreement interpol
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Computer security
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tugzip tugzip freeware file archiver microsoft windows handles great variety archive formats including commonly used ones like zip rar gzip bzip2 sqx 7z also view disk image files like bin c2d img iso nrg tugzip repairs corrupted zip archives encrypt files 6 different algorithms since release tugzip 3.5.0.0 development suspended due lack time kindahl side tugzip supports following file formats
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Computer file systems
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frogger frogger 1981 arcade game developed gremlin industries konami published sega object game direct frogs homes one one crossing busy road navigating river full hazards frogger positively received followed several clones sequels 2005 frogger various home video game incarnations sold 20 million copies worldwide including 5 million united states game found way popular culture including television music objective game guide frog empty frog homes top screen game starts three five seven frogs depending settings used operator losing ends game player control 4 direction joystick used navigate frog push direction causes frog hop direction frogger either single-player two players alternating frog starts bottom screen contains horizontal road occupied cars trucks bulldozers speeding along player must guide frog opposing lanes traffic avoid becoming roadkill results loss life road median strip separating two major parts screen upper portion screen consists river logs alligators turtles moving horizontally across screen jumping swiftly moving logs backs turtles alligators player guide frog safety player must avoid snakes otters open mouths alligators brightly colored lady frog sometimes log may carried bonus points top screen contains five frog homes destinations frog sometimes contain insects good lurking alligators bad game opening tune first verse japanese children song called inu omawarisan dog policeman japanese tunes played gameplay include themes anime hana ko lunlun araiguma rascal united states release kept opening song intact added yankee doodle softline 1982 stated frogger earned ominous distinction 'the arcade game ways die many different ways lose life illustrated skull crossbones symbol frog including hit running road vehicle jumping river water running snakes otters alligator jaws river jumping home invaded alligator staying top diving turtle completely submerged riding log alligator turtle side screen jumping home already occupied frog jumping side home bush running time five frogs homes game progresses next level increased difficulty five levels game gets briefly easier yet getting progressively harder level player 30 seconds guide frog one homes timer resets whenever life lost frog reaches home safely every forward step scores 10 points every frog arriving safely home scores 50 points 10 points also awarded per unused second time guiding lady frog home eating fly scores 200 points 5 frogs reach home end level player earns 1,000 points single bonus frog 20,000 points 99,990 points maximum high score achieved original arcade cabinet players may exceed score game keeps last 5 digits frogger ported many contemporary home systems several platforms capable accepting rom cartridges magnetic media systems commodore 64 received multiple versions game sierra on-line gained magnetic media rights sublicensed developers published systems normally supported sierra cornsoft published official trs-80/dragon 32 timex sinclair 1000 timex sinclair 2068 ports even atari 2600 received multiple releases cartridge cassette supercharger sierra released disk and/or tape ports c64 apple ii original 128k macintosh ibm pc atari 2600 supercharger well cartridge versions trs-80 color computer parker brothers received license sega cartridge versions produced cartridge ports frogger atari 2600 intellivision atari 5200 colecovision atari 8-bit family ti-99/4a vic-20 commodore 64 parker brothers spent 10 million advertising frogger sold three million cartridges company successful first-year product beating sales revenues previous best-seller merlin coleco also released stand-alone mini-arcade tabletop versions frogger along pac-man galaxian donkey kong sold three million units combined frogger also ported 1983 gakken compact vision tv boy one 6 launch titles ed driscoll reviewed atari vcs version frogger space gamer 58 driscoll commented liked arcade version save lot quarters price line cartridges also proves atari n't one making home versions major arcade games vcs danny goodman creative computing video arcade games wrote 1983 atari 2600 version frogger one detailed translations seen noting addition wraparound screen 2013 entertainment weekly named frogger one top ten games atari 2600 hasbro interactive released vastly expanded remake original microsoft windows playstation 1997 unlike original game consisted multiple levels different preceding one commercial success pc version alone selling nearly one million units less four months 1998 hasbro released series ports original game sega genesis super nes game com game boy game boy color port featured game different graphics sega genesis port featuring graphics original arcade game sega genesis snes versions last games released consoles north america despite using box art ports otherwise unrelated 1997 remake 2005 infospace teamed konami digital entertainment create mobile game frogger prizes players across u.s. competed multiplayer tournaments win daily weekly prizes 2006 mobile game version frogger grossed 10 million united states java port game available compatible mobile phones port frogger released xbox live arcade xbox 360 july 12 2006 developed digital eclipse published konami two new gameplay modes versus speed mode co-op play music including familiar frogger theme removed version replaced music version included compilation konami classics vol 1 home versions frogger numerous sequels including frogger great quest frogger helmet chaos frogger shown bipedal wearing shirt crossed-out truck frogger also inspired unofficial sequel sega 1991 called ribbit featured improved graphics simultaneous two-player action additionally prototype game based gameplay elements frogger developed sega game gear never released prototype contained additional features redesigned levels unofficial clones include ribbit apple ii 1981 acornsoft hopper 1983 bbc micro acorn electron f software frogger 1983 bbc micro zx spectrum pss ’ personal software services hopper oric 1 uk 1983 later release oric atmos froggy zx spectrum released djl software 1984 solo software frogger sharp mz-700 1984 uk version newbrain name leap frog several clones retained basic gameplay frogger changing style and/or plot pacific coast highway 1982 atari 8-bit family splits gameplay two alternating screens one highway one water preppie 1982 atari 8-bit family changes frog preppy retrieving golf balls country club frostbite 1983 atari 2600 uses frogger river gameplay arctic theme crossy road 2014 ios android windows phone randomly generated series road river sections game one endless level one life single point given forward hop atari 2600 game freeway often considered clone frogger game developed independently released 1981 2008 city melbourne created spin-off called grogger part public service campaign encourage people take safe transportation home night drinking frogger tied american popular culture found film television music 1983 frogger made animated television debut segment cbs saturday supercade cartoon lineup frogger voiced bob sarlatte worked investigative reporter segment aired one season 1998 game featured seinfeld episode frogger jerry george visit soon-to-be-closed pizzeria frequented teenagers discover frogger machine still place george decade-old high score still recorded buys machine tries get across street without letting lose power would erase high score initials glc season 4 episode george lopez friends n't let friends marry drunks george says son max play one frog tries cross street obvious reference frogger frogger also appears films wreck-it ralph pixels ralph breaks internet music frogger referenced also found 1982 buckner garcia recorded song called froggy lament using sound effects game released album pac-man fever punk band bad religion recorded song called frogger traffic los angeles song includes sample game theme music beginning frontman greg graffin claims playing frogger life result traffic song included band 1985 ep back known 2004 remaster debut album could hell worse uk girl group sugababes sampled coin-insert tone frogger game 2002 hit single freak like addition film television music frogger found popular culture mediums well 2006 group austin texas used modified roomba dressed frogger play real-life version game realm science frogger name given transposon jumping gene family fruit fly drosophila melanogaster november 26 1999 rickey world famous sauce offered 10,000 first person could score 1,000,000 points frogger 1,000 new world record prior january 1 2000 march 25 2005 robert mruczek offered 1,000 beating fictitious world record 860,630 set george costanza famous episode seinfeld 250 new world record end year december 1 2006 john cunningham offered 250 exceeding fictitious world record 860,630 points february 28 2007 one ever able achieve bounties scores surpassed bounties expired first score verified beaten fictional george costanza seinfeld score 860,630 points set pat laffaye december 22 2009 896,980 points surpassed michael smith springfield virginia usa score 970,440 points july 15 2012 current frogger world record holder pat laffaye westport connecticut usa august 15 2017 scored 1,029,990 points becoming first person ever break one million points original arcade machine
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Computer architecture
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statistical semantics linguistics statistical semantics applies methods statistics problem determining meaning words phrases ideally unsupervised learning degree precision least sufficient purpose information retrieval term statistical semantics first used warren weaver well-known paper machine translation argued word sense disambiguation machine translation based co-occurrence frequency context words near given target word underlying assumption word characterized company keeps advocated j.r. firth assumption known linguistics distributional hypothesis emile delavenay defined statistical semantics statistical study meanings words frequency order recurrence furnas et al 1983 frequently cited foundational contribution statistical semantics early success field latent semantic analysis research statistical semantics resulted wide variety algorithms use distributional hypothesis discover many aspects semantics applying statistical techniques large corpora statistical semantics focuses meanings common words relations common words unlike text mining tends focus whole documents document collections named entities names people places organizations statistical semantics subfield computational semantics turn subfield computational linguistics natural language processing many applications statistical semantics listed also addressed lexicon-based algorithms instead corpus-based algorithms statistical semantics one advantage corpus-based algorithms typically labour-intensive lexicon-based algorithms another advantage usually easier adapt new languages lexicon-based algorithms however best performance application often achieved combining two approaches
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Computational linguistics
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anti-spam research group anti-spam research group asrg research group started within internet research task force irtf charter concluded 18 march 2013 still reference melting pot anti-spam research theorization particular wiki lives dedicated research curbing spam internet-wide level consists mailing list coordinate work small web site wiki irtf groups asrg contributed internet engineering task force ietf process drafts documents assistance creation new working groups one ietf group spun asrg marid asrg sporadically active little evolves anti-spam landscape activity happening mailing list 2008 asrg worked internet drafts dnsbls 2010 standardization feedback loop email
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Computer security
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query string internet query string part uniform resource locator url assigns values specified parameters query string commonly includes fields added base url web browser client application example part html form web server handle hypertext transfer protocol request either reading file file system based url path handling request using logic specific type resource cases special logic invoked query string available logic use processing along path component url typical url containing query string follows server receives request page may run program passing query string case codice_1 unchanged program question mark used separator part query string web frameworks may provide methods parsing multiple parameters query string separated delimiter example url multiple query parameters separated ampersand codice_2 order queries n't matter codice_3 codice_4 produce results exact structure query string standardized methods used parse query string may differ websites link web page may url contains query string html defines three ways user agent generate query string one original uses contain content html form also known web form particular form containing fields codice_5 codice_6 codice_7 submitted content fields encoded query string follows definitive standard web frameworks allow multiple values associated single field e.g codice_11 field form query string contains pair codice_12 web forms may include fields visible user fields included query string form submitted convention w3c recommendation w3c recommends web servers support semicolon separators addition ampersand separators allow application/x-www-form-urlencoded query strings urls within html documents without entity escape ampersands form content encoded url query string form submission method get encoding used default submission method post result submitted http request body rather included modified url forms added html browsers rendered element single-line text-input control text entered control sent server query string addition get request base url another url specified attribute intended allow web servers use provided text query criteria could return list matching pages text input indexed search control submitted encoded query string follows though element deprecated browsers longer support render still vestiges indexed search existence example source special handling plus sign 'codice_13 within browser url percent encoding today deprecation indexed search redundant codice_15 also web servers supporting cgi e.g. apache process query string command line arguments contain equals sign 'codice_8 per section 4.4 cgi 1.1 cgi scripts still depend use historic behavior urls embedded html characters part url example space characters special meaning url example character codice_17 used specify subsection fragment document html forms character codice_8 used separate name value uri generic syntax uses url encoding deal problem html forms make additional substitutions rather applying percent encoding characters space encoded 'codice_13 codice_15 html 5 specifies following transformation submitting html forms get method web server following brief summary algorithm octet corresponding tilde codice_35 permitted query strings rfc3986 required percent-encoded html forms codice_36 encoding space 'codice_13 selection as-is characters distinguishes encoding rfc 3986 form embedded html page follows form action= cgi-bin/test.cgi method= get /form user inserts strings “ field ” “ clear already ” two text fields presses submit button program codice_38 program specified codice_39 attribute codice_40 element example receive following query string codice_41 form processed server cgi script script may typically receive query string environment variable named codice_42 program receiving query string ignore part requested url corresponds file program whole query string ignored however regardless whether query string used whole url including stored server log files facts allow query strings used track users manner similar provided http cookies work every time user downloads page unique identifier must chosen added query string urls links page contains soon user follows one links corresponding url requested server way download page linked previous one example web page containing following requested unique string codice_43 chosen page modified follows addition query string change way page shown user user follows example first link browser requests page codice_44 server ignores follows codice_45 sends page codice_46 expected adding query string links well way subsequent page request user carry query string codice_43 making possible establish pages viewed user query strings often used association web beacons main differences query strings used tracking http cookies according http specification various ad hoc limitations request-line length found practice recommended http senders recipients support minimum request-line lengths 8000 octets url long web server fails 414 request-uri long http status code common workaround problems use post instead get store parameters request body length limits request bodies typically much higher url length example limit post size default 2 mb iis 4.0 128 kb iis 5.0 limit configurable apache2 using codice_48 directive specifies number bytes 0 meaning unlimited 2147483647 2 gb allowed request body
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Web technology
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discretionary access control computer security discretionary access control dac type access control defined trusted computer system evaluation criteria means restricting access objects based identity subjects and/or groups belong controls discretionary sense subject certain access permission capable passing permission perhaps indirectly subject unless restrained mandatory access control discretionary access control commonly discussed contrast mandatory access control mac occasionally system whole said discretionary purely discretionary access control way saying system lacks mandatory access control hand systems said implement mac dac simultaneously dac refers one category access controls subjects transfer among mac refers second category access controls imposes constraints upon first meaning term practice clear-cut definition given tcsec standard tcsec definition dac impose implementation least two implementations owner widespread example capabilities term dac commonly used contexts assume every object owner controls permissions access object probably many systems implement dac using concept owner tcsec definition say anything owners technically access control system n't concept owner meet tcsec definition dac users owners dac implementation ability make policy decisions and/or assign security attributes straightforward example unix file mode represent write read execute 3 bits user group others prepended another bit indicates additional characteristics another example capability systems sometimes described providing discretionary controls permit subjects transfer access subjects even though capability-based security fundamentally restricting access based identity subjects capability systems general allow permissions passed subject subject wanting pass permissions must first access receiving subject subjects generally access subjects system
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Computer security
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closure computer programming programming languages closure also lexical closure function closure technique implementing lexically scoped name binding language first-class functions operationally closure record storing function together environment environment mapping associating free variable function variables used locally defined enclosing scope value reference name bound closure created unlike plain function closure allows function access captured variables closure copies values references even function invoked outside scope concept closures developed 1960s mechanical evaluation expressions λ-calculus first fully implemented 1970 language feature pal programming language support lexically scoped first-class functions peter j. landin defined term closure 1964 environment part control part used secd machine evaluating expressions joel moses credits landin introducing term closure refer lambda expression whose open bindings free variables closed bound lexical environment resulting closed expression closure usage subsequently adopted sussman steele defined scheme 1975 lexically scoped variant lisp became widespread term closure often used synonym anonymous function though strictly anonymous function function literal without name closure instance function value whose non-local variables bound either values storage locations depending language see lexical environment section example following python code values codice_1 codice_2 closures cases produced returning nested function free variable enclosing function free variable binds value parameter codice_3 enclosing function closures codice_1 codice_2 functionally identical difference implementation first case used nested function name codice_6 second case used anonymous nested function using python keyword codice_7 creating anonymous function original name used defining irrelevant closure value like value need assigned variable instead used directly shown last two lines example usage may deemed anonymous closure nested function definitions closures free variable yet bound enclosing function evaluated value parameter free variable nested function bound creating closure returned enclosing function lastly closure distinct function free variables outside scope non-local variables otherwise defining environment execution environment coincide nothing distinguish static dynamic binding distinguished names resolve values example program functions free variable codice_3 bound non-local variable codice_3 global scope executed environment codice_3 defined immaterial whether actually closures often achieved function return since function must defined within scope non-local variables case typically scope smaller also achieved variable shadowing reduces scope non-local variable though less common practice less useful shadowing discouraged example codice_11 seen closure codice_3 body codice_11 bound codice_3 global namespace codice_3 local codice_6 use closures associated languages functions first-class objects functions returned results higher-order functions passed arguments function calls functions free variables first-class returning one creates closure includes functional programming languages lisp ml well many modern multi-paradigm languages python rust closures also frequently used callbacks particularly event handlers javascript used interactions dynamic web page closures also used continuation-passing style hide state constructs objects control structures thus implemented closures languages closure may occur function defined within another function inner function refers local variables outer function run-time outer function executes closure formed consisting inner function code references upvalues variables outer function required closure closures typically appear languages first-class functions—in words languages enable functions passed arguments returned function calls bound variable names etc. like simpler types strings integers example consider following scheme function example lambda expression codice_17 appears within function codice_18 lambda expression evaluated scheme creates closure consisting code lambda expression reference codice_19 variable free variable inside lambda expression closure passed codice_20 function calls repeatedly determine books added result list discarded closure reference codice_19 use variable time codice_20 calls function codice_20 might defined completely separate file example rewritten javascript another popular language support closures codice_24 keyword used instead codice_7 codice_26 method instead global codice_20 function otherwise structure effect code function may create closure return following example closure case outlives execution function creates variables codice_11 codice_29 live function codice_30 returns even though execution left scope longer visible languages without closures lifetime automatic local variable coincides execution stack frame variable declared languages closures variables must continue exist long existing closures references commonly implemented using form garbage collection closure used associate function set private variables persist several invocations function scope variable encompasses closed-over function accessed program code stateful languages closures thus used implement paradigms state representation information hiding since closure upvalues closed-over variables indefinite extent value established one invocation remains available next closures used way longer referential transparency thus longer pure functions nevertheless commonly used impure functional languages scheme closures many uses note speakers call data structure binds lexical environment closure term usually refers specifically functions closures typically implemented special data structure contains pointer function code plus representation function lexical environment i.e. set available variables time closure created referencing environment binds non-local names corresponding variables lexical environment time closure created additionally extending lifetime least long lifetime closure closure entered later time possibly different lexical environment function executed non-local variables referring ones captured closure current environment language implementation easily support full closures run-time memory model allocates automatic variables linear stack languages function automatic local variables deallocated function returns however closure requires free variables references survive enclosing function execution therefore variables must allocated persist longer needed typically via heap allocation rather stack lifetime must managed survive closures referencing longer use explains typically languages natively support closures also use garbage collection alternatives manual memory management non-local variables explicitly allocating heap freeing done using stack allocation language accept certain use cases lead undefined behaviour due dangling pointers freed automatic variables lambda expressions c++11 nested functions gnu c. funarg problem functional argument problem describes difficulty implementing functions first class objects stack-based programming language c c++ similarly version 1 assumed programmer knows delegates automatic local variables references invalid return definition scope automatic local variables stack – still permits many useful functional patterns complex cases needs explicit heap allocation variables version 2 solved detecting variables must stored heap performs automatic allocation uses garbage collection versions need track usage variables passed strict functional languages immutable data e.g erlang easy implement automatic memory management garbage collection possible cycles variables references example erlang arguments variables allocated heap references additionally stored stack function returns references still valid heap cleaning done incremental garbage collector ml local variables lexically scoped hence define stack-like model since bound values objects implementation free copy values closure data structure way invisible programmer scheme algol-like lexical scope system dynamic variables garbage collection lacks stack programming model suffer limitations stack-based languages closures expressed naturally scheme lambda form encloses code free variables environment persist within program long possibly accessed used freely scheme expression closures closely related actors actor model concurrent computation values function lexical environment called acquaintances important issue closures concurrent programming languages whether variables closure updated updates synchronized actors provide one solution closures closely related function objects transformation former latter known defunctionalization lambda lifting see also closure conversion different languages always common definition lexical environment definitions closure may vary also commonly held minimalist definition lexical environment defines set bindings variables scope also closures language capture however meaning variable binding also differs imperative languages variables bind relative locations memory store values although relative location binding change runtime value bound location languages since closure captures binding operation variable whether done closure performed relative memory location often called capturing variable reference example illustrating concept ecmascript one language function codice_31 closures referred variables codice_11 codice_6 use relative memory location signified local variable codice_3 instances behaviour may undesirable necessary bind different lexical closure ecmascript would done using codice_35 example expected behaviour would link emit id clicked variable e bound scope lazy evaluated click actually happens click event emits id last element 'elements bound end loop variable codice_36 would need bound scope block using codice_37 codice_38 keyword hand many functional languages ml bind variables directly values case since way change value variable bound need share state closures—they use values often called capturing variable value java local anonymous classes also fall category—they require captured local variables codice_39 also means need share state languages enable choose capturing value variable location example c++11 captured variables either declared codice_40 means captured reference codice_41 means captured value yet another subset lazy functional languages haskell bind variables results future computations rather values consider example haskell binding codice_42 captured closure defined within function codice_31 computation codice_44—which case results division zero however since computation captured value error manifests closure invoked actually attempts use captured binding yet differences manifest behavior lexically scoped constructs codice_45 codice_46 codice_47 statements constructs general considered terms invoking escape continuation established enclosing control statement case codice_46 codice_47 interpretation requires looping constructs considered terms recursive function calls languages ecmascript codice_45 refers continuation established closure lexically innermost respect statement—thus codice_45 within closure transfers control code called however smalltalk superficially similar operator codice_52 invokes escape continuation established method invocation ignoring escape continuations intervening nested closures escape continuation particular closure invoked smalltalk implicitly reaching end closure code following examples ecmascript smalltalk highlight difference code snippets behave differently smalltalk codice_52 operator javascript codice_45 operator analogous ecmascript example codice_55 leave inner closure begin new iteration codice_56 loop whereas smalltalk example codice_57 abort loop return method codice_31 common lisp provides construct express either actions lisp codice_59 behaves smalltalk codice_57 lisp codice_61 behaves javascript codice_55 hence smalltalk makes possible captured escape continuation outlive extent successfully invoked consider closure returned method codice_31 invoked attempts return value invocation codice_31 created closure since call already returned smalltalk method invocation model follow spaghetti stack discipline facilitate multiple returns operation results error languages ruby enable programmer choose way codice_45 captured example ruby codice_66 codice_7 example ways create closure semantics closures thus created different respect codice_45 statement scheme definition scope codice_45 control statement explicit arbitrarily named 'return sake example following direct translation ruby sample languages features simulate behavior closures languages java c++ objective-c c vb.net features result language object-oriented paradigm c libraries support callbacks sometimes implemented providing two values registering callback library function pointer separate codice_70 pointer arbitrary data user choice library executes callback function passes along data pointer enables callback maintain state refer information captured time registered library idiom similar closures functionality syntax codice_70 pointer type safe c idiom differs type-safe closures c haskell ml callbacks extensively used gui widget toolkits implement event-driven programming associating general functions graphical widgets menus buttons check boxes sliders spinners etc application-specific functions implementing specific desired behavior application gcc extension nested function used function pointer emulate closures providing containing function exit example invalid typedef int *fn_int_to_int int //type function int- int fn_int_to_int adder int number int main void java enables classes defined inside methods called local classes classes named known anonymous classes anonymous inner classes local class either named anonymous may refer names lexically enclosing classes read-only variables marked codice_39 lexically enclosing method capturing codice_39 variables enables capture variables value even variable want capture non-codice_39 always copy temporary codice_39 variable class capturing variables reference emulated using codice_39 reference mutable container example single-element array local class able change value container reference able change contents container advent java 8 lambda expressions closure causes code executed local classes one types inner class declared within body method java also supports inner classes declared non-static members enclosing class normally referred inner classes defined body enclosing class full access instance variables enclosing class due binding instance variables inner class may instantiated explicit binding instance enclosing class using special syntax upon execution print integers 0 9 beware confuse type class nested class declared way accompanied usage static modifier desired effect instead classes special binding defined enclosing class java 8 java supports functions first class objects lambda expressions form considered type codice_77 domain u image type expression called codice_78 method standard method call apple introduced blocks form closure nonstandard extension c c++ objective-c 2.0 mac os x 10.6 snow leopard ios 4.0 apple made implementation available gcc clang compilers pointers block block literals marked codice_52 normal local variables captured value block created read-only inside block variables captured reference marked codice_80 blocks need persist outside scope created may need copied c sharp programming language |c anonymous methods lambda expressions support closure visual basic .net many language features similar c also supports lambda expressions closures programming language |d closures implemented delegates function pointer paired context pointer e.g class instance stack frame heap case closures version 1 limited closure support example code work correctly variable stack returning test longer valid use probably calling foo via dg return 'random integer solved explicitly allocating variable heap using structs class store needed closed variables construct delegate method implementing code closures passed functions long used referenced values still valid example calling another function closure callback parameter useful writing generic data processing code limitation practice often issue limitation fixed version 2 variable automatically allocated heap used inner function delegate function escape current scope via assignment dg return local variables arguments referenced delegates referenced delegates escape current scope remain stack simpler faster heap allocation true inner class methods references function variables c++ enables defining function object overloading codice_81 objects behave somewhat like functions functional programming language may created runtime may contain state implicitly capture local variables closures c++11|the 2011 revision c++ language also supports closures type function object constructed automatically special language construct called lambda-expression c++ closure may capture context either storing copies accessed variables members closure object reference latter case closure object escapes scope referenced object invoking codice_81 causes undefined behavior since c++ closures extend lifetime context eiffel programming language |eiffel includes inline agents defining closures inline agent object representing routine defined giving code routine in-line example argument codice_83 agent representing procedure two arguments procedure finds country corresponding coordinates displays whole agent subscribed event type codice_84 certain button whenever instance event type occurs button — user clicked button — procedure executed mouse coordinates passed arguments codice_3 codice_86 main limitation eiffel agents distinguishes closures languages reference local variables enclosing scope design decision helps avoiding ambiguity talking local variable value closure latest value variable value captured agent created codice_87 reference current object analogous codice_88 java features arguments agent accessed within agent body values outer local variables passed providing additional closed operands agent embarcadero c++builder provides reserve word __closure provide pointer method similar syntax function pointer standard c could write pointer function type using following syntax typedef void *tmyfunctionpointer void similar way declare pointer method using following syntax typedef void __closure *tmymethodpointer category programming language concepts category implementation functional programming languages category subroutines category articles example python code category articles example scheme code category articles example javascript code category articles example c++ code category articles example eiffel code category articles example c sharp code category articles example code category articles example objective-c code category articles example java code category articles example ruby code category articles example smalltalk code category articles example haskell code
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Programming language topics
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openpuff openpuff steganography watermarking sometimes abbreviated openpuff puff freeware steganography tool microsoft windows created cosimo oliboni still maintained independent software program notable first steganography tool version 1.01 released december 2004 last revision supports wide range carrier formats openpuff used primarily anonymous asynchronous data sharing advantage steganography cryptography alone messages attract attention plainly visible encrypted messages — matter unbreakable — arouse suspicion may incriminating countries encryption illegal therefore whereas cryptography protects contents message steganography said protect messages communicating parties watermarking action signing file id copyright mark openpuff invisible steganographic way applied supported carrier invisible mark password protected accessible everyone using program openpuff semi-open source program cryptographic algorithms 16 taken aes nessie cryptrec joined unique multi-cryptography algorithm extensive testing performed statistical resistance properties csprng multi-cryptography modules using ent nist diehard test suites provided results taken 64kb 128kb ... 256mb samples security performance steganalysis resistance conflicting trade-offs security vs performance whitening security vs. steganalysis cryptography whitening data carrier injection encrypted whitened small amount hidden data turns big chunk pseudorandom suspicious data carrier injection encodes using non linear covering function takes also original carrier bits input modified carriers need much less change con1 lowering random-like statistical response deceive many steganalysis tests con2 always non-negligible probability detected even hidden stream behaves like “ natural container ” unpredictable side-effects caught flagrante delicto etc. resisting unpredictable attacks also possible even user forced legal physical coercion provide valid password deniable steganography decoy-based technique allows user deny convincingly fact sensitive data hidden user needs provide expendable decoy data would plausibly want keep confidential reveal attacker claiming
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Computer security
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nokia nseries nokia nseries multimedia smartphone tablet product family engineered marketed nokia corporation nseries devices commonly supported multiple high-speed wireless technologies 3g wireless lan digital multimedia services music playback photo/video capture viewing gaming internet services also supported line replaced 2011 nokia lumia line company flagship smartphone portfolio nokia n1 tablet introduced november 2014 revived n prefix marketed 'nseries 27 april 2005 nokia announced new brand multimedia devices press conference mobile phone manufacturers amsterdam first three nseries devices introduced conference consists n70 n90 n91 2 november 2005 nokia announced n71 n80 n92 25 april 2006 nokia announced n72 n73 n93 26 september 2006 nokia announced n75 n95 8 january 2007 nokia announced nokia n76 nokia n77 nokia n93i 29 august 2007 nokia announced n95 8gb n81 n81 8gb 14 november 2007 nokia announced n82 first nokia xenon flash 2008 gsma held barcelona n96 n78 unveiled two new nseries devices revealed end august 2008 nokia n79 nokia n85 december 2 2008 nokia nseries announced nokia n97 february 17 2009 nokia announced nokia n86 8 mp nokia first 8-megapixel phone nokia n8 12-megapixel camera announced april 2010 21 june 2011 nokia showcased nokia n9 based meego os fourth non-symbian nseries device n800 n810 n900 nseries retired replaced lumia year company introduced nokia n1 tablet november 18 2014 marked return n prefix 'nseries branding still absent nokia nseries aimed users looking pack many features possible one device better-than-average cameras often found nseries devices many using higher-quality carl zeiss optics one example video music playback photo viewing capabilities devices resemble standalone portable media devices 2008 recently launched devices gps mp3 player wlan functionality also present numbers describe traits phone exceptions though considering n8x n82 n86 8mp top-of-the-range smartphones advanced cameras clearly 'high-end fellow n9x models first nseries device n90 ran symbian os 8.1 mobile operating system n70 n72 nokia n8 released september 2010 world first phone run symbian^3 first phone nokia featuring 12-megapixel autofocus lens also last nseries phone run symbian os n800 n810 n900 nokia chose use linux-based maemo operating system last nseries mobile phones n9 developer-only n950 released september 2011 maemo merged intel moblin create meego may 2010 nokia opted use meego harmattan 1.2 n9/n950 november 18 2014 nokia announced n1 android 5.0 tablet june nokia connections singapore nokia launched new n9 meego 1.2 harmattan os company calls qt device whole app ui framework written qt also world first pure touch phone buttons home screen great new swipe ui reviews average good phone reviewers liking phone good quality operating system expressing concern fact loses competitors terms specs device expected sold selected regions q3 2011
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Operating systems
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tail call computer science tail call subroutine call performed final action procedure tail call might lead subroutine called later call chain subroutine said tail-recursive special case recursion tail recursion tail-end recursion particularly useful often easy handle implementations tail calls implemented without adding new stack frame call stack frame current procedure longer needed replaced frame tail call modified appropriate similar overlay processes function calls program jump called subroutine producing code instead standard call sequence called tail call elimination tail call elimination allows procedure calls tail position implemented efficiently goto statements thus allowing efficient structured programming words guy l. steele general procedure calls may usefully thought goto statements also pass parameters uniformly coded machine code jump instructions programming languages require tail call elimination however functional programming languages tail call elimination often guaranteed language standard allowing tail recursion use similar amount memory equivalent loop special case tail recursive calls function calls may amenable call elimination general tail calls language semantics explicitly support general tail calls compiler often still optimize sibling calls tail calls functions take return types caller function called computer must remember place called return address return location result call complete typically information saved call stack simple list return locations order times call locations describe reached tail calls need remember caller – instead tail call elimination leaves stack alone except possibly function arguments local variables newly-called function return directly original caller tail call n't appear lexically statements source code important calling function return immediately tail call returning tail call result since calling function never get chance anything call optimization performed non-recursive function calls usually optimization saves little time space since many different functions available call dealing recursive mutually recursive functions recursion happens tail calls however stack space number returns saved grow significant since function call directly indirectly creating new call stack frame time tail call elimination often asymptotically reduces stack space requirements linear n constant 1 tail call elimination thus required standard definitions programming languages scheme languages ml family among others scheme language definition formalizes intuitive notion tail position exactly specifying syntactic forms allow results tail context implementations allowing unlimited number tail calls active moment thanks tail call elimination also called 'properly tail-recursive besides space execution efficiency tail call elimination important functional programming idiom known continuation-passing style cps would otherwise quickly run stack space tail call located syntactical end function codice_1 codice_2 calls codice_3 last thing procedure executes returning thus tail position however tail calls necessarily located syntactical end subroutine calls codice_3 codice_5 tail position lies end if-branch respectively even though first one syntactically end codice_6 body code call codice_1 tail position codice_8 tail position either codice_9 codice_10 control must return caller allow inspect modify return value returning following program example scheme written tail recursion style multiplication function tail position compared program assumes applicative-order evaluation inner procedure codice_11 calls last control flow allows interpreter compiler reorganize execution would ordinarily look like efficient variant terms space time reorganization saves space state except calling function address needs saved either stack heap call stack frame codice_11 reused intermediate results storage also means programmer need worry running stack heap space extremely deep recursions typical implementations tail recursive variant substantially faster variant constant factor programmers working functional languages rewrite recursive code tail-recursive take advantage feature often requires addition accumulator argument codice_13 example function cases filtering lists languages full tail recursion may require function previously purely functional written mutates references stored variables tail recursion modulo cons generalization tail recursion optimization introduced david h. d. warren context compilation prolog seen explicitly set language described though named daniel p. friedman david s. wise 1974 lisp compilation technique name suggests applies operation left perform recursive call prepend known value front list returned perform constant number simple data-constructing operations general call would thus tail call save modulo said cons operation prefixing value start list exit recursive call appending value end growing list entry recursive call thus building list side effect implicit accumulator parameter following prolog fragment illustrates concept thus tail recursive translation call transformed first creating new list node setting codice_14 field making tail call pointer node codice_15 field argument filled recursively following fragment defines recursive function c duplicates linked list form function tail-recursive control returns caller recursive call duplicates rest input list even allocate head node duplicating rest would still need plug result recursive call codice_16 field call function almost tail-recursive warren method pushes responsibility filling codice_16 field recursive call thus becomes tail call sentinel head node used simplify code callee appends end growing list rather caller prepend beginning returned list work done way forward list start recursive call proceeds instead backward list end recursive call returned result thus similar accumulating parameter technique turning recursive computation iterative one characteristically technique parent frame created execution call stack tail-recursive callee reuse call frame tail-call optimization present tail-recursive implementation converted explicitly iterative form accumulating loop paper delivered acm conference seattle 1977 guy l. steele summarized debate goto structured programming observed procedure calls tail position procedure best treated direct transfer control called procedure typically eliminating unnecessary stack manipulation operations since tail calls common lisp language procedure calls ubiquitous form optimization considerably reduces cost procedure call compared implementations steele argued poorly implemented procedure calls led artificial perception goto cheap compared procedure call steele argued general procedure calls may usefully thought goto statements also pass parameters uniformly coded machine code jump instructions machine code stack manipulation instructions considered optimization rather vice versa steele cited evidence well optimized numerical algorithms lisp could execute faster code produced then-available commercial fortran compilers cost procedure call lisp much lower scheme lisp dialect developed steele gerald jay sussman tail call elimination guaranteed implemented interpreter tail recursion important high-level languages especially functional logic languages members lisp family languages tail recursion commonly used way sometimes way available implementing iteration language specification scheme requires tail calls optimized grow stack tail calls made explicitly perl variant goto statement takes function name codice_18 however language implementations store function arguments local variables call stack default implementation many languages least systems hardware stack x86 implementing generalized tail call optimization presents issue size callee activation record different caller additional cleanup resizing stack frame may required cases optimizing tail recursion remains trivial general tail call optimization may harder implement efficiently example java virtual machine jvm tail-recursive calls eliminated reuses existing call stack general tail calls changes call stack result functional languages scala target jvm efficiently implement direct tail recursion mutual tail recursion gcc llvm/clang intel compiler suites perform tail call optimization c languages higher optimization levels codice_19 option passed though given language syntax may explicitly support compiler make optimization whenever determine return types caller callee equivalent argument types passed function either require amount total storage space call stack various implementation methods available tail calls often optimized interpreters compilers functional programming logic programming languages efficient forms iteration example scheme programmers commonly express loops calls procedures tail position rely scheme compiler interpreter substitute tail calls efficient jump instructions compilers generating assembly directly tail call elimination easy suffices replace call opcode jump one fixing parameters stack compiler perspective first example initially translated pseudo-assembly language fact valid x86 assembly tail call elimination replaces last two lines single jump instruction subroutine codice_20 completes return directly return address codice_21 omitting unnecessary codice_22 statement typically subroutines called need supplied parameters generated code thus needs make sure call frame properly set jumping tail-called subroutine instance platforms call stack contain return address also parameters subroutine compiler may need emit instructions adjust call stack platform code codice_23 codice_24 parameters compiler might translate tail call optimizer could change code code efficient terms execution speed use stack space since many scheme compilers use c intermediate target code tail recursion must encoded c without growing stack even c compiler optimize tail calls many implementations achieve using device known trampoline piece code repeatedly calls functions functions entered via trampoline function tail-call another instead calling directly returning result returns address function called call parameters back trampoline called trampoline takes care calling function next specified parameters ensures c stack grow iteration continue indefinitely possible implement trampolines using higher-order functions languages support groovy visual basic .net c using trampoline function calls rather expensive normal c function call least one scheme compiler chicken uses technique first described henry baker unpublished suggestion andrew appel normal c calls used stack size checked every call stack reaches maximum permitted size objects stack garbage-collected using cheney algorithm moving live data separate heap following stack unwound popped program resumes state saved garbage collection baker says appel method avoids making large number small trampoline bounces occasionally jumping empire state building garbage collection ensures mutual tail recursion continue indefinitely however approach requires c function call ever returns since guarantee caller stack frame still exists therefore involves much dramatic internal rewriting program code continuation-passing style tail recursion related control flow operator means transformation following construct transforms preceding x may tuple involving one variable care must taken designing assignment statement x ← bar x dependencies respected one may need introduce auxiliary variables use swap construct general uses tail recursion may related control flow operators break continue following bar baz direct return calls whereas quux quuux involve recursive tail call foo translation given follows
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Programming language topics
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data descriptor computing data descriptor structure containing information describes data data descriptors may used compilers software structure run time languages like ada pl/i hardware structure computers burroughs large systems data descriptors typically used run-time pass argument information called subroutines hp openvms multics system-wide language-independent standards argument descriptors descriptors also used hold information data fully known run-time dynamically allocated array unlike dope vector data descriptor contain address information following descriptor used ibm enterprise pl/i describe character string source array descriptor multics definitions include structure base array information structure dimension multics ran systems 36-bit words
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Programming language topics
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comparison programming languages basic instructions comparison programming languages common topic discussion among software engineers basic instructions several programming languages compared bold literal code non-bold interpreted reader statements guillemets « … » optional indicates necessary indent whitespace standard constants codice_1 codice_2 used determine many 'codice_3 'codice_4 usefully prefixed 'codice_5 'codice_6 actually size 'codice_5 'codice_8 'codice_6 available constants codice_10 codice_11 codice_12 etc standard constants codice_39 codice_40 used determine many 'codice_3 'codice_4 usefully prefixed 'codice_43 'codice_44 actually size 'codice_43 'codice_46 'codice_44 available constants codice_48 codice_49 codice_50 etc constants codice_51 codice_52 codice_53 available type machine epsilon value n provided codice_54 intrinsic function specifically strings arbitrary length automatically managed language separate character type characters represented strings length 1 expressions except codice_65 codice_66 operators values array types c automatically converted pointer first argument see c syntax arrays details syntax pointer operations classes supported pascal declaration blocks see comparison programming languages basic instructions functions types regular objects assign single instruction written line following colon multiple instructions grouped together block starts newline indentation required conditional expression syntax follow rule codice_74 n used change loop interval codice_74 omitted loop interval 1 common lisp allows codice_80 codice_81 codice_82 define restarts use codice_83 unhandled conditions may cause implementation show restarts menu user unwinding stack pascal declaration blocks see comparison programming languages basic instructions functions see reflection calling declaring functions strings string signed decimal number br algol 68 additionally unformatted transput routines codice_91 codice_92 br codice_93 codice_94 read unformatted text stdin use gets recommended fortran 2008 newer
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Programming language topics
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behat computer science behat test framework behavior-driven development written php programming language behat created konstantin kudryashov development hosted github behat intended aid communication developers clients stakeholders software development process allows clear documentation testable examples software intended behaviour behat test scenarios written gherkin business-readable domain-specific language following defined patterns tests run point new code introduced codebase confirm regressions within existing test coverage introduced integrated selenium browser emulators generate screenshots failures like bdd frameworks behat scenarios series given steps explain business case definition steps exist within method annotations class extends behatcontext preconditions given correspond php method name execute
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Programming language topics
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publius publishing system publius web protocol developed lorrie cranor avi rubin marc waldman gives individuals ability publish information web anonymously high guarantee publications censored modified third party nine design goals publius development team publius web system consists following agents publius system relies static list web servers publisher wishes add contents web first encrypts using random symmetric key k k split n shares parts least k n shares required reconstruction k see also secret sharing subset servers receives another share k encryption result using key k e k br retriever wishes obtain original contents follows generated url corresponds contents combined portion k appears subset servers list gathering k different shares copy e k allows retriever reconstruct key k shares decrypt e k back modification removal server hosted contents issued original publishers using combination password hosting server domain name present publius supports hosting html pages images file formats pdfs postscripts publius protocol allows following operations publisher wishes add web contents publius web publius client software publius client proxy executes following steps br diagram describing selection servers servers list hold encrypted contents hashed directory names publish operation done chosen server location formula_6 servers list holds following files directory named formula_7 retriever wishes browse web contents publius web publius client software publius client proxy executes following steps delete operation implemented invoking cgi script running servers server hash result formula_22 namely md5 hash result concatenation server domain name publisher password sent along corresponding formula_7 string compared one already stored password file directory formula_7 match file file removed directory update operation similarly uses hashed concatenation server domain name publisher password order authenticate original ownership hosted contents operation update done adding additional update file formula_7 contains new publius url matching updated contents recall publius url tied published contents share encryption key verified contents retrieved fact update operation equivalent publish operation addition adding update file old formula_7 directory redirecting future retrieve request new url retrieve operation issued old url publius proxy client redirected fetch new url done rest k -1 chosen servers k resulting urls match another set k servers chosen retrieval encrypted web contents publius protocol traceable publius urls following format formula_27 formula_28 concatenation hash results original contents combined key share described publish operation previous section options section url 16 bits represented two characters ascii string containing
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Internet protocols
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il network protocol internet link protocol il connection-based transport layer protocol designed bell labs originally part plan 9 operating system used carry 9p assigned internet protocol number 40 similar tcp much simpler main features fourth edition plan 9 2003 il deprecated favor tcp/ip n't handle long-distance connections well
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Internet protocols
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rsx-11 rsx-11 discontinued family multi-user real-time operating systems pdp-11 computers created digital equipment corporation widespread use late 1970s early 1980s rsx-11 influential development later operating systems vms windows nt designed mainly used process control also popular program development rsx-11 began port pdp-11 architecture earlier rsx-15 operating system pdp-15 minicomputer first released 1971 main architect rsx-15 later renamed xvm/rsx dan brevick commenting rsx acronym brevik says porting effort first produced small paper tape based real-time executives rsx-11a rsx-11c later gained limited support disks rsx-11b rsx-11b evolved fully fledged rsx-11d disk-based operating system first appeared pdp-11/40 pdp-11/45 early 1973 project leader rsx-11d version 4 henry krejci rsx-11d completed digital set adapt small memory footprint giving birth rsx-11m first released 1973 1971 1976 rsx-11m project spearheaded noted operating system designer dave cutler first project principles first tried rsx-11m appear also later designs led cutler dec vms microsoft windows nt direction ron mclean derivative rsx-11m called rsx-20f developed run pdp-11/40 front-end processor kl10 pdp-10 cpu meanwhile rsx-11d saw developments direction garth wolfendale project leader 1972–1976 system redesigned saw first commercial release support 22-bit pdp-11/70 system added wolfendale originally uk also set team designed prototyped ias operating system uk ias variant rsx-11d suitable time sharing later development release ias led andy wilson digital uk facilities estimated release dates rsx-11 ias data taken printing date associated documentation general availability date expected come closely manuals different printing dates latest date used rsx-11s proper subset rsx-11m release dates always assumed corresponding version rsx-11m side rsx-11m plus enhanced version rsx-11m expected later corresponding version rsx-11m rsx-11 proprietary software copyright asserted binary files source code documentation alike entirely developed internally digital therefore part open source however copy kernel source comments removed present every rsx distribution used system generation process notable exception rule micro-rsx came pre-generated autoconfiguring binary kernel commented kernel source code available separate product already binary license reference purposes ownership rsx-11s rsx-11m rsx-11m plus micro/rsx transferred digital mentec inc. march 1994 part broader agreement mentec inc. us subsidiary mentec limited irish firm specializing pdp-11 hardware software support december 2006 mentec inc. acquired irish firm calyx sell pdp-11 related services goods new commercial licenses therefore legally unobtainable hobbyists run rsx-11m version 4.3 earlier rsx-11m plus version 3.0 earlier simh emulator thanks free license granted may 1998 mentec inc. legal ownership rsx-11a rsx-11b rsx-11c rsx-11d ias never changed hands therefore passed compaq acquired digital 1998 hewlett-packard 2002 late 2015 hewlett-packard split two separate companies hp inc. hewlett packard enterprise current owner firmly established new commercial licenses issued least since october 1979 rsx-11a rsx-11b rsx-11c 1990 ias one operating systems ever licensed hobbyist use 1968 soviet government decided manufacturing copies ibm mainframes dec minicomputers cooperation comecon countries practical pursuing original designs cloning dec designs began 1974 name sm-evm cyrillic см эвм см эвм acronym 'система малых электронно-вычислительных машин russian 'system small electronic computing machines happened es evm mainframes based system/360 architecture russians allies sometimes significantly modified western designs therefore every sm-evm machine compatible dec offerings time clone rsx-11m operating system ran romanian-made coral family computers coral 2030 clone pdp-11 rsx-11 often used general-purpose timeshare computing even though target market competing rsts/e operating system rsx-11 provided features ensure better maximum necessary response time peripheral device input i.e real-time processing original intended use features included ability lock process called task rsx memory part system boot assign process higher priority would execute processes lower priority order support large programs within pdp-11 relatively small virtual address space 64 kb sophisticated semi-automatic overlay system used given program overlay scheme produced rsx taskbuilder program called tkb overlay scheme especially complex taskbuilding could take rather long time hours days standard rsx prompt mcr monitor console routine commands shortened first three characters entered correspondingly commands unique first three characters login command hello executed user yet logged hello chosen login command first three characters hel relevant allows non-logged user execute help command run certain pdp-11 processors dec operating system displays characteristic light pattern processor console panel system idle patterns created idle task running lowest level rsx-11m light pattern two sets lights sweep outwards left right center console inwards ind indirect command file processor program currently running contrast ias light pattern single bar lights swept leftwards correspondingly jumbled light pattern reflecting memory fetches visible indication computer load idle task executed pdp-11 operating systems rsts/e distinctive patterns console lights
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Operating systems
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parody generator parody generators computer programs generate text syntactically correct usually meaningless often style technical paper particular writer also called travesty generators random text generators purpose often satirical intending show little difference generated text real examples many work using techniques markov chains reprocess real text examples alternatively may hand-coded generated texts vary essay length paragraphs tweets term quote generator also used software randomly selects real quotations
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Computational linguistics
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motd unix /etc/motd file unix-like systems contains message day used send common message users efficient manner sending e-mail message systems might also motd feature motd info segment multics contents file /etc/motd displayed unix login command successful login executes login shell newer unix-like systems may generate message dynamically host boots user logs motd also become common feature online component windows pc games half-life call duty battlefield similar feature called motd displayed logging irc servers
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Operating systems
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parser cgi language parser free server-side cgi web scripting language developed art lebedev studio released gpl originally parser merely simple macro processing language latest 3rd revision march 2006 introduced object-oriented programming features compiler language developed c++ studio employees konstantin morshnev alexander petrosyan automate often repeated tasks especially maintenance already existing websites used many web projects studio since revision 3 released free software used websites mostly russia according partial list language website language supports technologies needed common web design tasks xml document object model dom perl compatible regular expressions pcre others
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Programming language topics
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rick francona lieutenant colonel rick francona born 31 august 1951 author commentator media military analyst retired united states air force intelligence officer experience middle east including tours duty national security agency defense intelligence agency central intelligence agency contract nbc news appeared regularly nbc msnbc cnbc well radio canada media 2013 became military analyst cnn francona served 27 years u.s. air force middle east fluent arabic served region national security agency defense intelligence agency central intelligence agency bachelor degree chapman college chapman university government arabic language master degree troy state university international relations concentration middle east studies cousin current cleveland indians manager terry francona francona wife emily also retired air force intelligence officer reside port orford oregon francona enlisted united states air force 1970 served vietnamese linguist 1973 conducting combat aerial reconnaissance missions vietnam laos variety strategic tactical aircraft arabic language training served variety locations middle east 1975 1977 supported evacuation u.s. embassy beirut lebanon 1976 1978 became arabic language instructor defense language institute monterey california following commissioning 1979 francona instructor air force intelligence school denver colorado 1982 1984 middle east operations officer national security agency united states overseas 1984 assigned advisor royal jordanian air force amman jordan 1987 assigned defense intelligence agency assistant defense intelligence officer middle east assignment spent much 1987 1988 u.s. embassy baghdad iraq liaison officer iraqi armed forces directorate military intelligence francona worked observer iraqi combat operations iranian forces flew sorties iraqi air force observations key discovery iraqi chemical weapons capabilities ballistic missile modifications immediately following iraqi invasion kuwait august 1990 gulf war francona deployed gulf interpreter advisor iraqi armed forces commander chief u.s. central command general norman schwarzkopf jr. lead interpreter ceasefire talks iraqi military safwan iraq march 1991 end gulf war francona served office secretary defense principal author department defense report congress conduct gulf war 1992 selected first air attaché u.s. embassy damascus syria returning united states 1995 1995 1996 francona served central intelligence agency participated variety sensitive operations middle east one operations survived attempt life iraqi intelligence service agents later awarded cia bronze seal medallion service cia 1996 selected lead development joint services counterterrorism intelligence branch direct result success creating special task force asked lead special operations team supporting nato forces bosnia late 1997 returned united states retired active duty 1998 decorations include defense distinguished service medal defense superior service medal bronze star nine air medals well campaign awards service vietnam persian gulf balkans francona awarded central intelligence agency seal medallion service agency 2006 francona inducted defense language institute hall fame francona media analyst middle east political-military events formerly contract nbc news appeared regularly nbc nightly news today show msnbc hardball chris matthews scarborough country countdown keith olbermann others also writes articles msnbc council foreign relations blog middle east perspectives frequently speaks conventions public service audiences 2010 francona appeared subject matter expert iraqi military saddam hussein episode spike tv deadliest warrior 2013 began working military analyst cnn commenting syrian civil war chemical warfare issues 2014 deteriorating situation iraq april 2008 documents obtained new york times reporter david barstow revealed francona recruited one 75 retired military officers involved pentagon military analyst program participants appeared television radio news shows military analysts and/or penned newspaper op/ed columns program launched early 2002 then-assistant secretary defense public affairs victoria clarke idea recruit key influentials help sell wary public possible iraq invasion
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Computer security
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sparcstation lx sparcstation lx sun 4/30 workstation designed manufactured sold sun microsystems based sun4m architecture enclosed lunchbox chassis shares code name sunergy low-end range sparcclassic sparcclassic x sparcstation zx sparcstation zx sparcstation lx sun zx leo 24-bit color framebuffer sparcstation lx single 50 mhz microsparc processor three banks two dsimm slots official maximum configuration uses 16mb modules first bank also hold 32mb modules giving maximum 128mb memory hold one internal 50-pin single ended fast-narrow scsi drive floppy drive also supports external scsi devices ide/atapi support comes on-board amd lance ethernet chipset providing 10baset networking standard 10base2 10base5 via aui transceiver openboot rom able boot network using rarp tftp like sparcstation systems ssc holds system information mac address serial number nvram battery chip dies system able boot possible set mac address manually boot sparcstation lx accelerated cg6 framebuffer compared sparcclassic cg3 lx also features 16-bit audio opposed 8-bit audio sparcclassic motherboards two systems otherwise similar use chassis following operating systems run sparcstation lx
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Computer architecture
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advfs advfs also known tru64 unix advanced file system file system developed late 1980s mid-1990s digital equipment corporation osf/1 version unix operating system later digital unix/tru64 unix june 2008 released free software gnu gplv2 license advfs used high-availability systems fast recovery downtime essential advfs uses relatively advanced concept storage pool called file domain logical file systems called file sets file domain composed number block devices could partitions lvm lsm devices file set logical file system created single file domain administrators add remove volumes active file domain providing enough space remaining file domain case removal one trickier original features implement data metadata residing disk removed first migrated online disks prior removal file sets balanced meaning file content file sets balanced across physical volumes particular files file set striped across available volumes administrators take snapshot clone active inactive file set allows easy on-line backups another feature allows administrators add remove block devices file domain file domain active users add/remove feature allows migration larger devices migration potentially failing hardware without system shutdown features include linux advfs supports additional ‘ ’ syncv ’ ’ system call atomically commit changes multiple files advfs also known tru64 unix advanced file system developed digital equipment corporation engineers late 1980s mid-1990s bellevue wa decwest previously worked earlier cancelled mica ozix projects first delivered dec osf/1 system later digital unix/tru64 unix time development moved teams located bellevue wa nashua nh versions always one version number behind operating system version thus dec osf/1 v3.2 advfs v2.x digital unix 4.0 advfs v3.x tru64 unix 5.x advfs v4.x generally considered advfs v4 matured production level stability sufficient set tools get administrators kind trouble original team enough confidence log based recovery release without fsck style recovery utility assumption file system journal would always allocated mirrored drives 1996 lee thekkath described use advfs top novel disk virtualisation layer known petal later paper thekkath et al describe file system frangapani built top petal compare performance advfs running storage layer shapiro miller compared performance files stored advfs oracle rdbms version 7.3.4 blob storage compaq sierra parallel file system pfs created cluster file system based multiple local advfs filesystems testing carried lawrence livermore national laboratory llnl 2000–2001 found underlying advfs filesystem adequate performance albeit high cpu utilisation pfs clustering layer top performed poorly june 23 2008 source code released hewlett-packard gnu general public license version 2 instead recently released gplv3 sourceforge order compatible also gplv2 licensed linux kernel license
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Computer file systems
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univa grid engine univa grid engine batch-queuing system forked sun grid engine sge software schedules resources data center applies policy management tools product deployed run on-premises using cloud computing hybrid cloud environment roots grid engine commercial product date back 1993 names codine later variation product grd comprehensive genealogy product described sun grid engine grid engine first distributed genias software 1999 company merger gridware inc 2000 sun microsystems acquired gridware sun renamed codine/grd sun grid engine later year released open-source 2001 2010 oracle corporation acquired sun thus renamed sge oracle grid engine oracle grid engine 6.2u6 source code included binaries changes put back project source repository response grid engine community started open grid scheduler son grid engine projects continue develop maintain free implementation grid engine january 18 2011 univa announced hired principal engineers sun grid engine team univa grid engine development led cto fritz ferstl founded grid engine project ran business within sun/oracle past 10 years october 22 2013 univa announced acquired oracle grid engine assets intellectual property making sole commercial provider grid engine software june 24 2018 univa announced massive scalability operating single cluster 1 million cores aws univa grid engine 8.0 first version released april 12 2011 forked sge 6.2u5 last open source release adds improved third party application integration license policy management enhanced support software hardware platforms cloud management tools univa grid engine 8.0.1 released october 4 2011 adds improved support multi-core hardware integration nvidia gpus new job submission verifier extensions additional bug fixes univa grid engine 8.1.0 announced may 2 updated latest release level 8.1.3 nov 15 2012 8.1.x releases deliver important new functionality job classes postgres spooling resource maps fair urgency deterministic wildcard pe selection improved diagnostics pre-configured mpi integations improved apache hadoop integration well many bug fixes performance improvements univa grid engine 8.1.6 announced oct 14 2013 update include improvements grid engine scheduler larger clusters qmaster stability improvements spooling qalter commands univa grid engine 8.2.0 released sept 02 2014 new univa grid engine version 8.2 includes native windows support univa grid engine 8.3.0 released june 22 2015 new preemption feature univa grid engine 8.3.0 allows users set priorities different work higher priority application must use resources currently allocated lower priority application lower priority application effectively “ paused ” —not lost—and work automatically resume higher priority application completed among handful new features added grid engine 8.3.0 improve overall reliability efficiency cluster new run time modification resources feature run time modification resources feature means much efficient use cluster resources univa grid engine 8.3.1 released august 28 2015 release contained new features univa grid engine 8.3.0 additional fixes enhancements identified since release 8.3.0 univa grid engine 8.4.0 released may 31 2016 release supports docker containers automatically dispatch run jobs user specified docker image univa grid engine 8.5.0 released march 7 2017 release univa grid engine 2x faster open source grid engine 6.2u5 grid engine 8.5.0 also includes significant improvement docker support including mobility gpu apps within cluster 8.6.0 released july 17 2018 univa grid engine supports nvidia docker 2.0 new univa grid engine docker integration allows flexibility running docker containers univa grid engine environment univa grid engine 8.6.1 released august 8 2018 providing improved control gpu devices new affinity features allowing jobs gravitate towards away certain compute nodes 8.6.2 released august 16 2018 univa grid engine performance scalability improved several key areas network communications job submission memory allocation scheduler optimizations update also improved univa grid engine job dispatch information 8.6.3 released september 27 2018 new update provided bulk configuration changes univa grid engine hosts new bulk configuration commands perform operations many hosts simultaneously makes easier manage large univa grid engine cluster 8.6.4 released november 23 2018 providing new core binding strategies make easier distribute nodes cores jobs also providing flexibility new affinity-based job placement policy included update jobs submitted using affinity either packed close together “ positive affinity ” “ negative affinity ” across cluster based resources requested new univa grid engine resource maps control access host devices nvidia gpus allows jobs request gpus gpu exclusively assigned job univa grid engine also directly communicates nvidia data center gpu manager collect gpu metrics scheduling accounting univa grid engine 8.6.5 released may 6 2019 new key features 8.6.7 released august 5 2019 among numerous enhancements univa grid engine 8.6.7 offers red hat linux 8 support nvidia gpu dcgm job usage
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Distributed computing architecture
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dollarrevenue dollarrevenue adware program made company name displays advertisements infected pc installs ucmore toolbar track internet searches usually comes bundled another program december 2007 dutch government agency opta fined two unnamed individuals three companies eur 1 million infecting 22 million computers worldwide june 2013 dutch corporate appeals court cbb overturned around eur 1 million worth fines imposed opta dollarrevenue cbb said opta adequately establish happened infected pcs
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Computer security
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series 80 software platform series 80 formerly crystal short-lived mobile software platform enterprise professional level smartphones made nokia introduced 2000 uses symbian os common physical properties symbian os user interface type screen resolution 640×200 pixels full qwerty keyboard series 80 used large size communicator screens best effect needed separate development relatively small market nokia 9300i announced 2005 final series 80 device nokia use series 80 platform final communicator nokia e90
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Operating systems
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federal office information security federal office information security abbreviated bsi german upper-level federal agency charge managing computer communication security german government areas expertise responsibility include security computer applications critical infrastructure protection internet security cryptography counter eavesdropping certification security products accreditation security test laboratories located bonn 600 employees current president since 1 february 2016 former business executive arne schönbohm took presidency michael hange bsi predecessor cryptographic department germany foreign intelligence agency bnd bsi still designs cryptographic algorithms libelle cipher initiated development gpg4win cryptographic suite bsi similar role unlike organizations bsi focused it-security rather part organisation general it-standards remit bsi separate germany signals intelligence part military foreign intelligence service bnd december 2018 arne schönbohm stated bsi yet seen evidence chinese telecommunications company huawei used equipment conduct espionage behalf china
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Computer security
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bogomips bogomips bogus mips unscientific measurement cpu speed made linux kernel boots calibrate internal busy-loop often-quoted definition term number million times per second processor absolutely nothing bogomips value used verify whether processor question proper range similar processors i.e bogomips represents processor clock frequency well potentially present cpu cache usable performance comparisons among different cpus 1993 lars wirzenius posted usenet message explaining reasons introduction linux kernel comp.os.linux approximate guide bogomips pre-calculated following table given rating typical cpu current applicable linux version index ratio bogomips per clock speed cpu intel 386dx cpu comparison purposes source complete list refer bogomips mini-howto 2.2.14 linux kernel caching setting cpu state moved behind bogomips calculation although bogomips algorithm n't changed kernel onward bogomips rating current pentium cpus twice rating change changed bogomips outcome effect real processor performance linux command visualization bogomips cat /proc/cpuinfo kernel 2.6.x bogomips implemented codice_1 kernel source file computes linux kernel timing parameter codice_2 see jiffy value explanation source code codice_2 used implement codice_4 delay microseconds codice_5 delay nanoseconds functions functions needed drivers wait hardware note busy waiting technique used kernel effectively blocked executing codice_5/codice_4 functions i386 architecture codice_8 implemented codice_9 equivalent following assembler code rewritten c-pseudocode full complete information details bogomips hundreds reference entries found outdated bogomips mini-howto 2012 arm contributed new codice_4 implementation allowing system timer built many armv7 cpus used instead busy-wait loop implementation released version 3.6 linux kernel timer-based delays robust systems use frequency scaling dynamically adjust processor speed runtime codice_11 values may necessarily scale linearly also since timer frequency known advance calibration needed boot time one side effect change bogomips value reflect timer frequency cpu core frequency typically timer frequency much lower processor maximum frequency users may surprised see unusually low bogomips value comparing systems use traditional busy-wait loops
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Computer architecture
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topsy labs topsy labs social search analytics company based san francisco california company certified twitter partner maintained comprehensive index tweets numbering hundreds billions dating back twitter inception 2006 topsy made products search analyze draw insights conversations trends public social websites including twitter google+ company acquired apple inc. december 2013 shut december 16 2015 topsy founded 2007 vipul ved prakash rishab aiyer ghosh gary iwatani justin foutts company raised usd 27 million venture capital bluerun ventures ignition partners founders fund scott banister investors company 40 employees offices san francisco washington dc operating data centers december 2013 topsy acquired apple inc. reported value around 225 million december 16 2015 topsy service shut website redirected apple support page discussing search functionality ios 9 topsy.com real-time search engine social posts socially shared content primarily twitter google plus service ranked results using proprietary social influence algorithm measured social media authors much others supported saying service also provided access metrics term mentioned twitter via free analytic service analytics.topsy.com users could compare three terms content past hour day week month announced september 2013 topsy would include every public tweet ever published twitter search analysis topsy pro analytics commercial web dashboard application allowed users conduct interactive analysis keywords authors activity influence exposure sentiment language geography users could discover relevant tweets links photos videos term topsy ’ index hundreds billions tweets users able group terms saved topics setup customized alerts daily activity digests topsy pro analytics version topsy pro analytics product government agencies intended purpose product facilitate disaster response quantify political issues detect disease outbreak monitor global anomalies topsy provided set rest apis programmatically access twitter data metrics users could also access data via ad-hoc report requests index co-developed twitter topsy debuted august 2012 originally compared social sentiment two primary american presidential candidates index also co-developed twitter topsy debuted january 2013 originally compared social sentiment films nominated academy awards six categories best picture best actor best actress best supporting actor best supporting actress best director topsy sentiment analysis used index correctly predicted five six award recipients march 2013 mashable topsy co-produced mashable sxsw trendspotter mobile-enabled website visitors could see trending sxsw event based real-time analysis twitter conversations sxsw trendspotter provided analysis
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Web technology
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modified harvard architecture modified harvard architecture variation harvard computer architecture unlike pure harvard architecture allows contents instruction memory accessed data modern computers documented harvard architecture fact modified harvard architecture original harvard architecture computer harvard mark employed entirely separate memory systems store instructions data cpu fetched next instruction loaded stored data simultaneously independently contrast von neumann architecture computer instructions data stored memory system without complexity cpu cache must accessed turn physical separation instruction data memory sometimes held distinguishing feature modern harvard architecture computers microcontrollers entire computer systems integrated onto single chips use different memory technologies instructions e.g flash memory data typically read/write memory von neumann machines becoming popular true distinction harvard machine instruction data memory occupy different address spaces words memory address uniquely identify storage location von neumann machine also necessary know memory space instruction data address belongs computer von neumann architecture advantage pure harvard machines code also accessed treated data vice versa allows example data read disk storage memory executed code self-optimizing software systems using technologies just-in-time compilation write machine code memory later execute another example self-modifying code allows program modify disadvantage methods issues executable space protection increase risks malware software defects addition systems notoriously difficult document code flow also make debugging much difficult accordingly pure harvard machines specialty products modern computers instead implement modified harvard architecture modifications various ways loosen strict separation code data still supporting higher performance concurrent data instruction access harvard architecture common modification builds memory hierarchy cpu cache separating instructions data unifies except small portions data instruction address spaces providing von neumann model programmers never need aware fact processor core implements modified harvard architecture although benefit speed advantages programmers write instructions data memory need aware issues cache coherency another change preserves separate address space nature harvard machine provides special machine operations access contents instruction memory data data directly executable instructions machines always viewed modified harvard architecture harvard architecture processors maxq execute instructions fetched memory segment – unlike original harvard processor execute instructions fetched program memory segment processors like harvard architecture processors – unlike pure von neumann architecture – read instruction read data value simultaneously 're separate memory segments since processor least two separate memory segments independent data buses obvious programmer-visible difference kind modified harvard architecture pure von neumann architecture – executing instruction one memory segment – memory segment simultaneously accessed data three characteristics may used distinguish modified harvard machines pure harvard von neumann machines pure harvard machines address zero instruction space refers instruction storage location separate address zero data space refers distinct data storage location contrast von neumann split-cache modified harvard machines store instructions data single address space address zero refers one location whether binary pattern location interpreted instruction data defined program written however like pure harvard machines instruction-memory-as-data modified harvard machines separate address spaces separate addresses zero instruction data space therefore distinguish type modified harvard machines pure harvard machines point pure modified harvard machines co-exist flexible general von neumann architecture separate memory pathways cpu allow instructions fetched data accessed time improving throughput pure harvard machines separate pathways separate address spaces split-cache modified harvard machines separate access paths cpu caches tightly coupled memories unified address space covers rest memory hierarchy von neumann processor unified address space programmer point view modified harvard processor instruction data memories share address space usually treated von neumann machine cache coherency becomes issue self-modifying code program loading confusing issues usually visible systems programmers integrators modified harvard machines like pure harvard machines regard original harvard machine mark stored instructions punched paper tape data electro-mechanical counters however entirely due limitations technology available time today harvard machine pic microcontroller might use 12-bit wide flash memory instructions 8-bit wide sram data contrast von neumann microcontroller arm7tdmi modified harvard arm9 core necessarily provides uniform access flash memory sram 8 bit bytes cases outside applications cacheless dsp microcontroller required modern processors cpu cache partitions instruction data also processors harvard machines rigorous definition program data memory occupy different address spaces modified weak sense operations read and/or write program memory data example lpm load program memory spm store program memory instructions atmel avr implement modification similar solutions found microcontrollers pic z8encore many families digital signal processors ti c55x cores instruction execution still restricted program address space processors unlike von neumann machines separate address spaces creates certain difficulties programming high-level languages directly support notion tables read-only data might different address space normal writable data thus need read using different instructions c programming language support multiple address spaces either non-standard extensions standardized extensions support embedded processors
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Computer architecture
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web counter web counter hit counter computer software program indicates number visitors hits particular webpage received set counters incremented one every time web page accessed web browser number usually displayed inline digital image plain text image rendering digits may use variety fonts styles classic example wheels odometer counter often accompanied date set last reset without becomes impossible estimate within time number page loads counted occurred web counters simply web bugs used webmasters track hits included visible on-page elements counters popular 1990s later replaced web traffic measures self-hosted scripts like analog later remote systems used javascript like google analytics systems typically include on-page elements displaying count thus seeing web counter modern web page one example retrocomputing internet one seo spamming technique companies pay site listed html code free hit counter thus user puts page small link appear bottom quick way sites accumulate inbound links often performed sites competitive web fields like online gambling 2008 google removed number high-ranking mesothelioma sites using counters top results
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Web technology
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pumpkin adventure iii hunt unknown pumpkin adventure iii hunt unknown video game msx created umax released 1995 sunrise foundation role-playing game turn-based fighting system los angeles attack strange creatures nobody knows creatures sent last hope l.a. government sets special police team s.o.d.o.m even s.o.d.o.m able stop threat last resort brilliant professor steinein uses time machine find brave people history people steve damien bishop stopped lucifer taking world pumpkin adventure 2 three together s.o.d.o.m member jeff tates start quest find source creatures destroy
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Computer architecture
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gdium gdium subnotebook netbook computer produced emtec gdium product distinguished unique loongson mips processor use usb key primary storage device gdium netbook marketed interface device gdium learning community —a website provides hardware support mips builds open-source software linux computing tips educational resources targeted towards teachers students within k-12 demographic emtec gdium liberty 1000 built stmicroelectronics loongson 2f mips microprocessor uses proprietary form-factored usb key called g-key primary storage medium g-key fits specially designed usb slot recessed within unit available 8gb 16gb capacities key generates noise less susceptible mechanical shock damage hard drives also includes sd card reader provides support mmc sd sdhc cards supplemental storage gdium uses mandriva sole operating system boots approximately 30 seconds desktop uses metacity window manager lxplanel idesk-based interface like modern linux distributions open-source software applications openoffice.org mozilla firefox thunderbird gimp included default installation compilations microsoft windows os x ubuntu available mips architecture e.g debian offers packages compiled mips emtec gdium liberty 1000 specifications follows website went around sept 2013 unsure community still alive elsewhere
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Computer architecture
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inductive data type inductive data type may refer
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Programming language topics
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ipad air ipad air first-generation ipad air tablet computer designed developed marketed apple inc announced october 22 2013 released november 1 2013 ipad air features thinner design similarities contemporaneous ipad mini 2 64-bit apple a7 processor m7 coprocessor discontinued launch 9.7 inch ipad pro march 21 2016 successor ipad air 2 announced october 16 2014 sold discontinuation march 21 2017 ipad air name brought back announcement third-generation ipad air march 18 2019 june 3 2019 apple announced ipados supporting ipad air first generation stay ios 12 ipad air announced keynote yerba buena center arts october 22 2013 keynote named 'we still lot cover ipad air came ios 7 operating system released september 18 2013 jonathan ive designer ios 7 new elements described update bringing order complexity highlighting features refined typography new icons translucency layering physics gyroscope-driven parallaxing major changes design design ios 7 os x mavericks version 10.9 noticeably depart skeuomorphic elements green felt game center wood newsstand leather calendar favor flat colourful design act hotspot carriers sharing internet connection wi-fi bluetooth usb also access apple app store digital application distribution platform ios service allows users browse download applications itunes store developed xcode ios sdk published apple app store garageband imovie iphoto iwork apps pages keynote numbers available ipad air comes several applications including siri safari mail photos video music itunes app store maps notes calendar game center photo booth contacts like ios devices ipad sync content data mac pc using itunes although ios 5 later managed backed without computer although tablet designed make phone calls cellular network users use headset built-in speakers microphone place phone calls wi-fi cellular using voip application skype device dictation application using voice recognition technology iphone 4s enables users speak ipad types say screen though ipad must internet connection via wi-fi cellular network speech processed apple servers apple also began giving away popular ilife iphoto imovie garageband iwork pages keynote numbers apps device june 8 2015 announced wwdc ipad air would support ios 9 new features released q3 2015 air users ios 9 able take advantage two features called slide picture picture slide allows user slide second app side screen smaller window display information alongside initial app picture picture allows user watch video small resizable moveable window remaining another app another feature dubbed split view allows user run two apps simultaneously 50/50 view supported air instead run ipad air 2 announced wwdc 2016 ipad air along various ios devices support ios 10 announced wwdc 2017 ipad air support latest version ios ios 11 dropping support immediate predecessor 4th generation ipad apple announced ipad air together apple a7 powered devices support ios 12 update making ipad air one longest supported ios device support six major versions ios ios 7 way ios 12 june 2019 apple announced drop support ipad air release ipados ipad air marks first major design change ipad since ipad 2 thinner design 7.5 millimeters thick smaller screen bezel similar ipad mini apple reduced overall volume ipad air using thinner components resulting 22 reduction weight ipad 2 though still uses 9.7-inch retina display previous ipad model improved front-facing camera makes using facetime much clearer new front-facing camera capable video 720p hd includes face detection backside illumination rear camera received upgrade well called isight camera addition functions front camera also contains 5mp cmos hybrid ir filter fixed ƒ/2.4 aperture device available space gray silver colors previous generations apple continued use recyclable materials enclosure ipad air milled solid block aluminum making 100 recyclable ipad air also free harmful materials bfrs pvc although air inherits hardware components iphone 5s 64-bit apple a7 system-on-chip apple m7 motion processor uses home button built previous ipad models therefore support touch id fingerprint sensor a7 present ipad air slightly different however use pop design stacks ram top soc also features metal heat spreader compensate slightly faster clock speed better thermal management air also includes 5 megapixel rear-facing camera isight facetime hd front-facing camera support 802.11n estimated 10 hours battery life boots faster previous ipad model previous generations iphone ipad hardware four buttons one switch ipad air device portrait orientation home button face device display returns user home screen wake/sleep button top edge device two buttons upper right side device performing volume up/down functions switch whose function varies according device settings functioning either switch device silent mode lock/unlock orientation screen addition wifi version weighs 469 grams cellular model weighs 478 grams – 25 lighter respective predecessors display responds sensors ambient light sensor adjust screen brightness 3-axis accelerometer sense orientation switch portrait landscape modes unlike iphone ipod touch built-in applications work three orientations portrait landscape-left landscape-right ipad built-in applications support screen rotation four orientations including upside-down consequently device intrinsic native orientation relative position home button changes ipad air available 16 32 64 128 gb internal flash memory expansion option apple also sells camera connection kit sd card reader used transfer photos videos announcement ipad pro 9.7-inch march 21 2016 ipad air discontinued models connect wireless lan offer dual band wi-fi support tablet also manufactured either without capability communicate cellular network ipad air ipad mini 2 cellular model comes two variants support nano-sims quad-band gsm penta-band umts dual-band cdma ev-do rev b. additionally one variant also supports lte bands 1-5 7 8 13 17-20 25 26 variant supports lte bands 1-3 5 7 8 18-20 td-lte bands 38 39 40 apple ability handle many different bands one device allowed offer first time single ipad variant supports cellular bands technologies deployed major north american wireless providers time device introduction audio playback ipad air stereo two speakers located either side lightning connector ipad air received mainly positive reviews writing anandtech anand lal shimpi writes ipad air feels like true successor ipad 4 praising reduced weight size shimpi states air hits balance features design ergonomics n't think 've ever seen ipad uk editor-in-chief techradar patrick goss gave ipad air positive review giving praise a7 chip camera upgrades well crisp colorful display concludes stating hard put words much apple improved ipad offering stunning level detail power build quality unrivalled christina bonnington wired awarded air rating 8 10 calling performance outstanding noting high-definition video streams gaming animations smooth stutter free also praised loading speeds safari web browser bonnington criticized speakers slightly muddled apple inc. co-founder steve wozniak criticized focus decreasing size weight rather increasing storage space stated want ipad air fit personal needs dave smith international business times wrote two less positive reviews air arguing device nice bring anything new ipad smith strongly criticized lack touch id noted updates increased speed decreased size weight slight improvements launch date ipad air see large turnout usual apple products however expected analysts due delayed release ipad mini 2 air sold hong kong two hours becoming available online
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Operating systems
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myanimelist myanimelist often abbreviated mal anime manga social networking social cataloging application website site provides users list-like system organize score anime manga facilitates finding users share similar tastes provides large database anime manga site claims 4.4 million anime 775,000 manga entries 2015 site received 120 million visitors month site launched april 2006 garrett gyssler maintained solely 2008 originally website called animelist garret gyssler decided incorporate possessive beginning following fashion important social network years myspace august 4 2008 craveonline men entertainment lifestyle site owned atomiconline purchased myanimelist undisclosed sum money 2015 dena announced purchased myanimelist craveonline would partner anime consortium japan stream anime service via daisuki myanimelist announced april 2016 embed episodes crunchyroll hulu directly onto site 20,000 episodes made available site april 2017 myanimelist added king avatar first chinese animation site database march 8 2018 myanimelist opened online manga store partnership kodansha comics viz media allowing users purchase manga digitally website service originally launched canada later expanded united states united kingdom several english-speaking countries mal became inaccessible several days may june 2018 site staff took offline maintenance citing security privacy concerns site operators also disabled api third-party apps rendering unusable moves done efforts conform european union gdpr program myanimelist acquired media january 2019 purchase announced intention focus marketing e-book sales strengthen site myanimelist lists anime japanese animation aeni korean animation donghua chinese animation similarly myanimelist information manga japanese comics manwha korean comics manhua chinese comics well dōjinshi fan comics light novels users create lists strive complete users submit reviews write recommendations blogs post site forum create clubs unite people similar interests subscribe rss news feed anime manga related news mal also starts challenges users complete 'lists myanimelist allows users score anime manga list scale 1 10 scores aggregated give show database rank best worst show rank calculated twice day using following formula formula_1 formula_2 stands total number user votes formula_3 average user score formula_4 minimum number votes required get calculated score currently 50 formula_5 average score across entire anime/manga database scores user completed least 20 anime/manga calculated
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Databases
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treebank linguistics treebank parsed text corpus annotates syntactic semantic sentence structure construction parsed corpora early 1990s revolutionized computational linguistics benefitted large-scale empirical data exploitation treebank data important ever since first large-scale treebank penn treebank published however although originating computational linguistics value treebanks becoming widely appreciated linguistics research whole example annotated treebank data crucial syntactic research test linguistic theories sentence structure large quantities naturally occurring examples term treebank coined linguist geoffrey leech 1980s analogy repositories seedbank bloodbank syntactic semantic structure commonly represented compositionally tree structure term parsed corpus often used interchangeably term treebank emphasis primacy sentences rather trees treebanks often created top corpus already annotated part-of-speech tags turn treebanks sometimes enhanced semantic linguistic information treebanks created completely manually linguists annotate sentence syntactic structure semi-automatically parser assigns syntactic structure linguists check necessary correct practice fully checking completing parsing natural language corpora labour-intensive project take teams graduate linguists several years level annotation detail breadth linguistic sample determine difficulty task length time required build treebank treebanks follow specific linguistic theory syntactic annotation e.g bultreebank follows hpsg try less theory-specific however two main groups distinguished treebanks annotate phrase structure example penn treebank ice-gb annotate dependency structure example prague dependency treebank quranic arabic dependency treebank important clarify distinction formal representation file format used store annotated data treebanks necessarily constructed according particular grammar grammar may implemented different file formats example syntactic analysis john loves mary shown figure right may represented simple labelled brackets text file like following penn treebank notation type representation popular light resources tree structure relatively easy read without software tools however corpora become increasingly complex file formats may preferred alternatives include treebank-specific xml schemes numbered indentation various types standoff notation computational perspective treebanks used engineer state-of-the-art natural language processing systems part-of-speech taggers parsers semantic analyzers machine translation systems computational systems utilize gold-standard treebank data however automatically parsed corpus corrected human linguists still useful provide evidence rule frequency parser parser may improved applying large amounts text gathering rule frequencies however obvious process correcting completing corpus hand possible identify rules absent parser knowledge base addition frequencies likely accurate corpus linguistics treebanks used study syntactic phenomena example diachronic corpora used study time course syntactic change parsed corpus contain frequency evidence showing common different grammatical structures use treebanks also provide evidence coverage support discovery new unanticipated grammatical phenomena another use treebanks theoretical linguistics psycholinguistics interaction evidence completed treebank help linguists carry experiments decision use one grammatical construction tends influence decision form others try understand speakers writers make decisions form sentences interaction research particularly fruitful layers annotation e.g semantic pragmatic added corpus possible evaluate impact non-syntactic phenomena grammatical choices semantic treebank collection natural language sentences annotated meaning representation resources use formal representation sentence semantic structure semantic treebanks vary depth semantic representation notable example deep semantic annotation groningen meaning bank developed university groningen annotated using discourse representation theory example shallow semantic treebank propbank provides annotation verbal propositions arguments without attempting represent every word corpus logical form deep syntax treebank treebank lying interface syntax semantics representation structure interpreted graph representing subject infinitival phrases extraction it-clef construction shared subject ellipsis extend many syntactic treebanks developed wide variety languages facilitate researches multilingual tasks researchers discussed universal annotation scheme cross-languages way people try utilize merge advantages different treebanks corpora instance universal annotation approach dependency treebanks universal annotation approach phrase structure treebanks one key ways extract evidence treebank search tools search tools parsed corpora typically depend annotation scheme applied corpus user interfaces range sophistication expression-based query systems aimed computer programmers full exploration environments aimed general linguists wallis 2008 discusses principles searching treebanks detail reviews state art
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Computational linguistics
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cern httpd cern httpd later also known w3c httpd early discontinued web server http daemon originally developed cern 1990 onwards tim berners-lee ari luotonen henrik frystyk nielsen implemented c first ever web server software cern httpd originally developed next computer running nextstep later ported unix-like operating systems openvms systems unix emulation layers e.g os/2 emx+gcc could also configured web proxy server version 0.1 released june 1991 august 1991 berners-lee announced usenet newsgroup alt.hypertext availability source code server daemon world wide web software cern ftp site server presented hypertext 91 conference san antonio part cern program library cernlib later versions server based libwww library development cern httpd later taken world wide web consortium w3c last release version 3.0a 15 july 1996 1996 onwards w3c focused development java-based jigsaw server initial version public domain software last one mit license
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Web technology
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barrel processor barrel processor cpu switches threads execution every cycle cpu design technique also known interleaved fine-grained temporal multithreading unlike simultaneous multithreading modern superscalar architectures generally allow execution multiple instructions one cycle like preemptive multitasking thread execution assigned program counter hardware registers thread architectural state barrel processor guarantee thread execute one instruction every n cycles unlike preemptive multitasking machine typically runs one thread execution tens millions cycles threads wait turn technique called c-slowing automatically generate corresponding barrel processor design single-tasking processor design n -way barrel processor generated way acts much like n separate multiprocessing copies original single-tasking processor one running roughly 1/ n original speed one earliest examples barrel processor i/o processing system cdc 6000 series supercomputers executed one instruction portion instruction 10 different virtual processors called peripheral processors returning first processor one motivation barrel processors reduce hardware costs case cdc 6x00 ppus digital logic processor much faster core memory rather ten separate processors ten separate core memory units ppus share single set processor logic another example honeywell 800 8 groups registers allowing 8 concurrent programs instruction processor would cases switch next active program sequence barrel processors also used large-scale central processors tera mta 1988 large-scale barrel processor design 128 threads per core mta architecture seen continued development successive products cray urika-gd originally introduced 2012 yarcdata urika targeted data-mining applications barrel processors also found embedded systems particularly useful deterministic real-time thread performance example xmos xcore xs1 2007 four-stage barrel processor eight threads per core xs1 found ethernet usb audio control devices applications i/o performance critical barrel processors also used specialized devices eight-thread ubicom ip3023 network i/o processor 2004 8-bit microcontrollers padauk technology feature barrel processors 8 threads per core single-tasking processor spends lot time idle anything useful whenever cache miss pipeline stall occurs advantages employing barrel processors single-tasking processors include disadvantages barrel processors
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Computer architecture
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norton power eraser norton power eraser npe small portable executable uses norton insight in-the-cloud application ratings scan computer system program matches application found user computer list trusted malicious applications list trusted applications power eraser leaves system list bad applications marked deletion unknown list reported suspicious marked removal instead program recommends remote scan upload file symantec servers check virus definitions power eraser aggressive unknown threats whitelisted instead marked removal sent analysis tool also features rootkit scanning requires system restart threat removal also performed restart next boot avoid self-protection viruses trojans
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Computer security
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petname petname systems naming systems claim possess three naming properties zooko triangle global secure memorable software uses system satisfy three requirements systems used enhance security preventing phishing attacks unlike traditional identity systems focus service provider petname systems decentralized designed facilitate needs enduser interact multiple services though petname model formally described 2005 mark stiegler potential system discovered several people successively capdesk – desktop environment petname tool extension available firefox allows petnames assigned secure websites use extension help prevent phishing attacks petname markup language pnml proposal embedding petname information systems using custom markup language pnml consists two tags
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Computer security
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dell technologies dell technologies inc. american multinational technology company headquartered round rock texas formed result september 2016 merger dell emc corporation later became dell emc dell products include personal computers servers smartphones televisions computer software computer security network security well information security services dell ranked 35th 2018 fortune 500 rankings largest united states corporations total revenue approximately 50 company revenue derived united states dell operates 3 divisions follows dell also owns 5 separate businesses rsa security pivotal software secureworks virtustream boomi inc. october 12 2015 dell announced intent acquire emc corporation enterprise software storage company 67 billion transaction labeled highest-valued tech acquisition history addition michael dell singapore temasek holdings silver lake partners major dell shareholders supported transaction september 7 2016 dell inc. completed merger emc corp. involved issuance 45.9 billion debt 4.4 billion common stock dell services dell software group dell emc enterprise content divisions sold shortly thereafter proceeds 7.0 billion used repay debt october 2017 reported dell would invest 1 billion iot research development dell inc. returned private ownership 2013 claiming faced bleak prospects would need several years public eye rebuild business emc pressured elliott management corporation hedge fund holding 2.2 emc stock reorganize unusual federation structure emc divisions effectively run independent companies elliott argued structure deeply undervalued emc core emc ii data storage business increasing competition emc ii vmware products confusing market hindering companies wall street journal estimated 2014 dell revenue 27.3 billion personal computers 8.9 billion servers emc 16.5 billion emc ii 1bn rsa security 6bn vmware 230 million pivotal software emc owned around 80 stock vmware acquisition maintained vmware separate company held via new tracking stock rest emc rolled dell acquisition required dell publish quarterly financial results ceased going private 2013 dell technologies products services field scale-out architecture converged infrastructure private cloud computing january 29 2018 reported dell technologies considering reverse merger vmware subsidiary order take company public december 28 2018 dell technologies became public company
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Distributed computing architecture
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partial evaluation computing partial evaluation technique several different types program optimization specialization straightforward application produce new programs run faster originals guaranteed behave way computer program prog seen mapping input data output data formula_2 static data part input data known compile time partial evaluator transforms formula_3 formula_4 precomputing static input compile time formula_5 called residual program run efficiently original program act partial evaluation said residualize formula_6 formula_5 particularly interesting example use partial evaluation first described 1970s yoshihiko futamura prog interpreter programming language source code designed run inside said interpreter partial evaluation interpreter respect data/program produces prog* version interpreter runs source code written implementation language interpreter require source code resupplied runs faster original combination interpreter source case prog* effectively compiled version technique known first futamura projection three furthermore applying tool 3 yields tool quine first described futamura 1983
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Programming language topics
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bertrand meyer bertrand meyer born 21 november 1950 french academic author consultant field computer languages created eiffel programming language idea design contract bertrand meyer received master degree engineering école polytechnique paris second master degree stanford university phd université de nancy technical managerial career nine years électricité de france three years member faculty university california santa barbara october 2001 early 2016 professor software engineering eth zürich swiss federal institute technology pursued research building trusted components reusable software elements guaranteed level quality chair eth computer science department 2004 2006 13 years 2003–2015 taught introduction programming course taken eth computer science students resulting widely disseminated programming textbook touch class springer currently professor polytechnic university milan arrived erc advanced investigator grant project meyer activities include associate professorships innopolis university 2015–16 chair excellence university toulouse 1998 2003 adjunct professor monash university melbourne australia member french academy technologies also active consultant object-oriented system design architectural reviews technology assessment trainer object technology software topics conference speaker many years meyer active issues research education policy founding president 2006–2011 informatics europe association european computer science departments meyer pursues ideal simple elegant user-friendly computer languages one earliest vocal proponents object-oriented programming oop book object-oriented software construction widely considered best work presenting case oop books written include eiffel language description eiffel language object success discussion object technology managers reusable software discussion reuse issues solutions introduction theory programming languages touch class authored numerous articles edited conference proceedings initial designer eiffel method language continued participate evolution originator design contract development method experiences object technology simula language well early work abstract data types formal specification including z notation provided background development eiffel eiffel influential development languages including java c python 2005 meyer senior award winner first aito dahl-nygaard award prize named two creators object technology awarded annually senior junior researchers made significant technical contributions field object orientation meyer received honorary doctorates itmo university saint petersburg russia 2004 university york uk 2015 2006 meyer received software system award acm impact software quality recognition design eiffel 2008 fellow acm also 2009 recipient harlan mills award ieee computer society 28 december 2005 anonymous user falsely announced meyer death german wikipedia biography meyer hoax reported five days later heise news ticker article immediately corrected many major news media outlets germany switzerland picked story meyer went publish positive evaluation wikipedia concluding system succumbed one potential flaws quickly healed n't affect big picture like rumors wikipedia downfall grossly exaggerated
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Programming language topics
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eager evaluation computer programming eager evaluation also known strict evaluation greedy evaluation evaluation strategy used traditional programming languages eager evaluation expression evaluated soon bound variable opposite alternative eager evaluation lazy evaluation expressions evaluated dependent expression evaluated depending upon defined evaluation strategy effects eager evaluation include imperative programming languages order execution implicitly defined structure source code almost always use eager evaluation order avoid unexpected behaviour occur certain contexts out-of-order execution e.g using multithreaded software concurrent execution code etc. unexpected behaviour result data races atomicity violations potentially unwanted hard control bugs effects many modern compilers capable re-ordering execution better optimize processor resources often eliminate unnecessary expressions executed entirely determined results expressions visible rest program however divert flow compiled program away evaluation strategy defined programming language compiled code written notable exception potential bugs introduced compiler avoid problem modern high-level languages provide constructs allow programmer direct compiler regards optimisations example using block-level construct lock c allows programmer define code block executed order defined source code effectively barring compiler performing re-order operations code block church encoding eager evaluation operators maps strict evaluation functions reason strict evaluation sometimes called eager
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Programming language topics
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suretype suretype qwerty-based character input method cell phones used blackberry pearl suretype combines traditional telephone keypad qwerty-based keyboard create non-standard way input text cell phone addition suretype contains list 35,000 english words user types beginning word possible words start letters show screen additional words also added word list suretype developed blackberry vendor research motion
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Operating systems
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rdrand codice_1 previously known bull mountain instruction returning random numbers intel on-chip hardware random number generator seeded on-chip entropy source codice_1 available ivy bridge processors part intel 64 ia-32 instruction set architectures amd added support instruction june 2015 random number generator compliant security cryptographic standards nist sp 800-90a fips 140-2 ansi x9.82 intel also requested cryptography research inc. review random number generator 2012 resulted paper analysis intel ivy bridge digital random number generator codice_3 similar codice_1 provides higher level access entropy hardware codice_3 generator processor instruction codice_6 available intel broadwell cpus amd zen cpus codice_7 instruction used check whether central processing unit cpu supports codice_1 instruction amd intel cpus supported bit 30 ecx register set calling cpuid standard function codice_9 amd processors checked feature using test codice_3 availability checked intel cpus similar manner codice_3 supported bit 18 ebx register set calling cpuid standard function codice_12 opcode codice_1 codice_14 followed modrm byte specifies destination register optionally combined rex prefix 64 bit mode intel secure key intel name codice_1 instruction underlying random number generator rng hardware implementation codenamed bull mountain development intel calls rng digital random number generator drng generator takes pairs 256-bit raw entropy samples generated hardware entropy source applies advanced encryption standard aes cbc-mac mode conditioner reduces single 256-bit conditioned entropy sample deterministic random-bit generator called ctr_drbg defined nist sp 800-90a seeded output conditioner providing cryptographically secure random numbers applications requesting via codice_1 instruction hardware issue maximum 511 128-bit samples changing seed value using codice_3 operation provides access conditioned 256-bit samples aes-cbc-mac codice_3 instruction added intel secure key seeding another pseudorandom number generator available broadwell cpus entropy source codice_3 instruction runs asynchronously self-timed circuit uses thermal noise within silicon output random stream bits rate 3 ghz slower effective 6.4gbit/s obtainable codice_1 rates shared cores threads codice_3 instruction intended seeding software prng arbitrary width whereas codice_1 intended applications merely require high-quality random numbers cryptographic security required software prng xorshift usually faster intel core i7-7700k 4500 mhz 45 x 100 mhz processor kaby lake-s microarchitecture single codice_1 codice_3 instruction takes 110ns 463 clock cycles regardless operand size 16/32/64 bits number clock cycles applies processors skylake kaby lake microarchitecture silvermont microarchitecture processors instructions take around 1472 clock cycles regardless operand size ivy bridge processors codice_1 takes 117 clock cycles amd ryzen cpu instructions takes around 1200 clock cycles 16-bit 32-bit operand around 2500 clock cycles 64-bit operand astrophysical monte carlo simulator examined time generate 10 64-bit random numbers using codice_1 quad-core intel i7-3740 qm processor found c implementation codice_1 ran 2x slower default random number generator c 20x slower mersenne twister although python module codice_1 constructed found 20x slower default random number generator python gcc 4.6+ clang 3.2+ provide intrinsic functions rdrand -mrdrnd specified flags also setting __rdrnd__ allow conditional compilation newer versions additionally provide codice_29 wrap built-ins functions compatible version 12.1+ intel c compiler functions write random data location pointed parameter return 1 success option generate cryptographically-secure random numbers using codice_1 codice_3 openssl help secure communications first scientific application rdrand found astrophysics radio observations low-mass stars brown dwarfs revealed number emit bursts radio waves radio waves caused magnetic reconnection process causes solar flares sun rdrand used generate large quantities random numbers monte carlo simulator model physical properties brown dwarfs effects instruments observe found 5 brown dwarfs sufficiently magnetic emit strong radio bursts also evaluated performance rdrand instruction c python compared random number generators september 2013 response new york times article revealing nsa effort weaken encryption theodore ts publicly posted concerning use rdrand /dev/random linux kernel linus torvalds dismissed concerns use rdrand linux kernel pointed used source entropy /dev/random rather used improve entropy combining values received rdrand sources randomness however taylor hornby defuse security demonstrated linux random number generator could become insecure backdoor introduced rdrand instruction specifically targets code using hornby proof-of-concept implementation works unmodified linux kernel prior version 3.13 developers changed freebsd kernel away using rdrand via padlock directly comment freebsd 10 going backtrack remove rdrand padlock backends feed yarrow instead delivering output directly /dev/random still possible access hardware random number generators rdrand padlock etc. directly inline assembly using openssl userland required trust
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Computer architecture
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zipf–mandelbrot law /math probability theory statistics zipf–mandelbrot law discrete probability distribution also known pareto-zipf law power-law distribution ranked data named linguist george kingsley zipf suggested simpler distribution called zipf law mathematician benoit mandelbrot subsequently generalized probability mass function given formula_6 given may thought generalization harmonic number formula formula_8 rank data formula_9 formula_10 parameters distribution limit formula_11 approaches infinity becomes hurwitz zeta function formula_12 finite formula_11 formula_14 zipf–mandelbrot law becomes zipf law infinite formula_11 formula_14 becomes zeta distribution distribution words ranked frequency random text corpus approximated power-law distribution known zipf law one plots frequency rank words contained moderately sized corpus text data versus number occurrences actual frequencies one obtains power-law distribution exponent close one see powers 1998 gelbukh sidorov 2001 zipf law implicitly assumes fixed vocabulary size harmonic series =1 converge zipf-mandelbrot generalization 1 furthermore evidence closed class functional words define language obeys zipf-mandelbrot distribution different parameters open classes contentive words vary topic field register ecological field studies relative abundance distribution i.e graph number species observed function abundance often found conform zipf–mandelbrot law within music many metrics measuring pleasing music conform zipf–mandelbrot distributions
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Computational linguistics
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caddy web server caddy sometimes clarified caddy web server mostly open source http/2-enabled web server written go uses go standard library http functionality one caddy notable features enabling https default author matthew holt began developing caddy december 2014 released april 2015 since advanced two hundred developers adding example support quic caddy supports variety web technologies available statically-compiled binaries windows mac linux android bsd operating systems i386 amd64 arm architectures variety web site technologies served caddy also act reverse proxy load balancer caddy features implemententations found go library enhancements available middleware exposed directives caddyfile text file used configure caddy caddy vulnerable number widespread cves including heartbleed drown poodle beast addition caddy uses tls_fallback_scsv prevent protocol downgrade attacks june 2 2015 version 0.7.1 released patch vulnerability timing attacks caddy basic authentication middleware regards protocols cipher suites caddy uses tls 1.0-1.2 prefers ecdhe ecdsa aes-256 gcm sha-384 although dozen different ciphers supported caddy also used cloudflare platform serve experimental tls 1.3 implementation traditional privilege de-escalation performed c programs non-trivial possible go programs caddy activates https default sites qualifying domain names names tls certificate negotiated via acme protocol redirects http requests https obtains certificates needed startup keeps renewed lifetime server let encrypt default certificate authority user may customize acme ca used often necessary testing configurations q1 2016 caddy accounted 2 certificates issued let encrypt alternate configuration allows caddy obtain certificates needed tls handshakes rather startup feature dubbed on-demand tls enable feature user must specify maximum number certificates issued way caddy receives request hostname yet certificate negotiate new certificate via acme serve immediately caching obtained certificate memory storing disk process usually takes seconds subject tight rate limits serving tls caddy automatically rotate session ticket keys periodically help preserve perfect forward secrecy starting version 0.11 caddy telemetry opt-in disabled default downloading caddy official website opt-out enabled default building source
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Web technology
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comparison file archivers following tables compare general technical information number file archivers please see individual products articles information neither all-inclusive entries necessarily date unless otherwise specified footnotes section comparisons based stable versions— without add-ons extensions external programs note archivers names purple longer development basic general information archivers creator/company license/price etc operating systems archivers run without emulation compatibility layer linux ubuntu gui archive manager example open create many archive formats including rar archives even extent splitting parts encryption ability read native program presumably compatibility layer notes information common archiver features implemented natively without third-party add-ons notes information archive formats archivers read external links lead information support future versions archiver extensions provide functionality note gzip bzip2 xz rather compression formats archive formats notes information archive formats archivers write create external links lead information support future versions archiver extensions provide functionality note gzip bzip2 xz rather compression formats archive formats notes peazip full support various lpaq paq formats quad balz highly efficient rolz based compressors freearc format native pea format 7-zip includes read support .msi cpio xar plus apple dmg/hfs disk images deb/.rpm package distribution formats beta versions 9.07 onwards full support lzma2-compressed .xz format
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Computer file systems
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.net framework version history microsoft started development .net framework late 1990s originally name next generation windows services ngws late 2001 first beta versions .net 1.0 released first version .net framework released 13 february 2002 bringing managed code windows nt 4.0 98 2000 xp since first version microsoft released nine upgrades .net framework seven released along new version visual studio two upgrades .net framework 2.0 4.0 upgraded common language runtime clr new versions .net framework replace older versions clr version .net framework family also includes two versions mobile embedded device use reduced version framework .net compact framework available windows ce platforms including windows mobile devices smartphones additionally .net micro framework targeted severely resource-constrained devices first version .net framework released 13 february 2002 windows 98 nt 4.0 2000 xp mainstream support version ended 10 july 2007 extended support ended 14 july 2009 exception windows xp media center tablet pc editions 19 june 2001 tenth anniversary release visual basic .net framework 1.0 beta 2 released .net framework 1.0 supported windows 98 nt 4.0 2000 xp server 2003 applications utilizing .net framework 1.0 also run computers .net framework 1.1 installed supports additional operating systems .net framework 1.0 service pack 1 released 18 march 2002 .net framework 1.0 service pack 2 released 7 february 2005 .net framework 1.0 service pack 3 released 30 august 2004 version 1.1 first minor .net framework upgrade available redistributable package software development kit published 3 april 2003 also part second release visual studio .net 2003 first version .net framework included part windows operating system shipping windows server 2003 mainstream support .net framework 1.1 ended 14 october 2008 extended support ended 8 october 2013 .net framework 1.1 last version support windows nt 4.0 provides full backward compatibility version 1.0 except rare instances application run checks version number library changes 1.1 include .net framework 1.1 supported windows 98 nt 4.0 2000 xp server 2003 vista server 2008 .net framework 1.1 service pack 1 released 30 august 2004 version 2.0 released 22 january 2006 also released along visual studio 2005 microsoft sql server 2005 biztalk 2006 software development kit version released 29 november 2006 last version support windows 98 windows changes 2.0 include .net framework 2.0 supported windows 98 2000 xp server 2003 vista server 2008 server 2008 r2 applications utilizing .net framework 2.0 also run computers .net framework 3.0 3.5 installed supports additional operating systems .net framework 2.0 service pack 1 released 19 november 2007 .net framework 2.0 service pack 2 released 16 january 2009 requires windows 2000 sp4 plus kb835732 kb891861 update windows xp sp2 plus windows installer 3.1 last version support windows 2000 although unofficial workarounds use subset functionality version 3.5 windows 2000 .net framework 3.0 formerly called winfx released 21 november 2006 includes new set managed code apis integral part windows vista windows server 2008 also available windows xp sp2 windows server 2003 download major architectural changes included release .net framework 3.0 uses clr .net framework 2.0 unlike previous major .net releases .net compact framework release made counterpart version version 3.0 .net framework shipped windows vista also shipped windows server 2008 optional component disabled default .net framework 3.0 consists four major new components .net framework 3.0 supported windows xp server 2003 vista server 2008 server 2008 r2 applications utilizing .net framework 3.0 also run computers .net framework 3.5 installed supports additional operating systems .net framework 3.0 service pack 1 released 19 november 2007 .net framework 3.0 service pack 2 released 22 february 2010 version 3.5 .net framework released 19 november 2007 .net framework 3.0 version 3.5 uses common language runtime clr 2.0 version .net framework version 2.0 addition .net framework 3.5 also installs .net framework 2.0 sp1 3.0 sp1 later 3.5 sp1 instead installing 2.0 sp2 3.0 sp2 adds methods properties bcl classes version 2.0 required version 3.5 features language integrated query linq changes affect applications written version 2.0 however previous versions new .net compact framework 3.5 released tandem update order provide support additional features windows mobile windows embedded ce devices source code framework class library version partially released debugging reference microsoft reference source license .net framework 3.5 supported windows xp server 2003 vista server 2008 7 server 2008 r2 8 server 2012 8.1 server 2012 r2 10 server 2016 .net framework 3.5 service pack 1 released 11 august 2008 release adds new functionality provides performance improvements certain conditions especially wpf 20–45 improvements expected two new data service components added ado.net entity framework ado.net data services two new assemblies web development system.webabstraction system.webrouting added used asp.net mvc framework reportedly used future release asp.net forms applications service pack 1 included sql server 2008 visual studio 2008 service pack 1 also featured new set controls called visual basic power packs brought back visual basic controls line shape version 3.5 sp1 .net framework shipped windows 7 also shipped windows server 2008 r2 optional component disabled default .net framework 3.5 sp1 also new variant .net framework called .net framework client profile 28 mb significantly smaller full framework installs components relevant desktop applications however client profile amounts size using online installer windows xp sp2 .net frameworks installed using windows update using off-line installer os download size still 250 mb key focuses release .net framework 4.0 supported windows xp service pack 3 windows server 2003 vista server 2008 7 server 2008 r2 applications utilizing .net framework 4.0 also run computers .net framework 4.5 4.6 installed supports additional operating systems .net framework 4.0 last version support windows xp windows server 2003 microsoft announced intention ship .net framework 4 29 september 2008 public beta released 20 may 2009 28 july 2009 second release .net framework 4 beta made available experimental software transactional memory support functionality available final version framework 19 october 2009 microsoft released beta 2 .net framework 4 time microsoft announced expected launch date .net framework 4 22 march 2010 launch date subsequently delayed 12 april 2010 10 february 2010 release candidate published version rc 12 april 2010 final version .net framework 4.0 launched alongside final release microsoft visual studio 2010 18 april 2011 version 4.0.1 released supporting customer-demanded fixes windows workflow foundation design-time component requires visual studio 2010 sp1 adds workflow state machine designer 19 october 2011 version 4.0.2 released supporting new features microsoft sql server version 4.0.3 released 4 march 2012 release .net framework 4 microsoft released set enhancements named windows server appfabric application server capabilities form appfabric hosting in-memory distributed caching support .net framework 4.5 released 15 august 2012 set new improved features added version .net framework 4.5 supported windows vista later .net framework 4.5 uses common language runtime 4.0 additional runtime features .net framework 4.5 supported windows vista server 2008 7 server 2008 r2 8 server 2012 8.1 server 2012 r2 applications utilizing .net framework 4.5 also run computers .net framework 4.6 installed supports additional operating systems metro-style apps originally designed specific form factors leverage power windows operating system two subset .net framework available building metro-style apps using c visual basic one windows 8 windows 8.1 called .net apis windows 8.x store apps another universal windows platform uwp called .net apis uwp version .net framework well runtime libraries used metro-style apps part windows runtime new platform development model metro-style apps ecosystem houses many platforms languages including .net framework c++ html5 javascript managed extensibility framework mef library creating lightweight extensible applications allows application developers discover use extensions configuration required also lets extension developers easily encapsulate code avoid fragile hard dependencies mef allows extensions reused within applications across applications well release .net framework 4.5.1 announced 17 october 2013 along visual studio 2013 version requires windows vista sp2 later included windows 8.1 windows server 2012 r2 new features .net framework 4.5.1 release .net framework 4.5.2 announced 5 may 2014 version requires windows vista sp2 later windows forms applications improvements made high dpi scenarios asp.net higher reliability http header inspection modification methods available new way schedule background asynchronous worker tasks .net framework 4.6 announced 12 november 2014 released 20 july 2015 supports new just-in-time compiler jit 64-bit systems called ryujit features higher performance support sse2 avx2 instruction sets wpf windows forms received updates high dpi scenarios support tls 1.1 tls 1.2 added wcf version requires windows vista sp2 later cryptographic api .net framework 4.6 uses latest version windows cng cryptography api result nsa suite b cryptography available .net framework suite b consists aes sha-2 family hashing algorithms elliptic curve diffie–hellman elliptic curve dsa .net framework 4.6 supported windows vista server 2008 7 server 2008 r2 8 server 2012 8.1 server 2012 r2 10 server 2016 however .net framework 4.6.1 4.6.2 drops support windows vista server 2008 .net framework 4.6.2 drops support windows 8 release .net framework 4.6.1 announced 30 november 2015 version requires windows 7 sp1 later new features apis include preview .net framework 4.6.2 announced march 30 2016 released august 2 2016 version requires windows 7 sp1 later new features include 5 april 2017 microsoft announced .net framework 4.7 integrated windows 10 creators update promising standalone installer windows versions update visual studio 2017 released date add support targeting .net framework 4.7 promised standalone installer windows 7 later released 2 may 2017 prerequisites included package new features .net framework 4.7 include .net framework 4.7 supported windows 7 server 2008 r2 server 2012 8.1 server 2012 r2 10 server 2016 server 2019 .net framework 4.7.1 released 17 october 2017 amongst fixes new features corrects d3dcompiler dependency issue also adds compatibility .net standard 2.0 box .net framework 4.7.2 released 30 april 2018 amongst changes improvements asp.net bcl clr clickonce networking sql wcf windows forms workflow wpf version included server 2019 .net framework 4.8 released 18 april 2019 includes additional enhancements high-resolution displays performance updates security enhancements .net framework 4.8 supported windows 7 server 2008 r2 server 2012 8.1 server 2012 r2 10 server 2016 server 2019 most-recent release 4.8.0 build 3928 released july 25 2019 offline installer size 111mb digital signature date july 25 2019
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Operating systems
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job submission description language job submission description language extensible xml specification global grid forum description simple tasks non-interactive computer execution systems currently version 1.0 released november 7 2005 specification focuses description computational task submissions traditional high-performance computer systems like batch schedulers jsdl describes submission aspects job attempt describe state running historic jobs instead jsdl includes descriptions following software known currently support jsdl
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Distributed computing architecture
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v5 interface v5 family telephone network protocols defined etsi allow communications telephone exchange also known specifications local exchange le local loop potentially thousands subscribers connected le problem physically managing thousands wires local subscribers costs associated prior specification v5 manufacturers exchange equipment proprietary solutions problem solutions inter-operate meant tied single manufacturer method exchange v5 provided standard set protocols subscriber le access network defined reference point signalling point le standardised therefore allowed multiple vendor solution provided specifications followed resulted single link case v5.2 multiple links le reducing need many lines along point likely need proprietary solution manage single link final link local loop remained digital signalling isdn analogue signalling basic telephony also known pots industry protocols based principle common-channel signaling message-based signalling subscribers uses signalling channel rather separate channels existing different subscribers v5 comes two forms v5.1 supports control pstn isdn protocols v5.2 also supports bcc link control protection protocols v5 layer 3 protocols transported layer 2 protocol called lapv5 variation lap-d link access procedures channel isdn transport layer v5 protocol stack controls circuit-switched communication paths portions v5 re-used new service known narrowband multimedia delivery service nmds particular pstn protocol re-used combined isdn provide service subscriber allowed digital connection subscribers house re-use analogue phones across digital connection reference point replaced isdn-like nte nte managed analogue service basic rate isdn service subscribers home
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Internet protocols
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novell s-net s-net aka sharenet network operating system set network protocols used talk client machines network released novell 1983 s-net operating system entirely proprietary operating system written motorola 68000 processor used star network topology s-net also called netware 68 68 denoting 68000 processor superseded netware 86 written intel 8086 processor 1985
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Operating systems
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primary key relational model databases primary key specific choice minimal set attributes columns uniquely specify tuple row relation table informally primary key attributes identify record simple cases simply single attribute unique id formally primary key choice candidate key minimal superkey candidate key alternate key primary key may consist real-world observables case called natural key attribute created function key used identification outside database called surrogate key example database people given nationality time location birth could natural key.national identification number another example attribute may used natural key although mainly used today relational database context term primary key pre-dates relational model also used database models relational database terms primary key differ form function key n't primary practice various different motivations may determine choice one key primary another designation primary key may indicate preferred identifier data table primary key used foreign key references tables may indicate technical rather semantic feature table languages software special syntax features used identify primary key e.g primary key constraint sql relational model expressed relational calculus relational algebra distinguish primary keys kinds keys primary keys added sql standard mainly convenience application programmer primary keys defined iso sql standard primary key constraint syntax add constraint existing table defined like primary key also specified directly table creation sql standard primary keys may consist one multiple columns column participating primary key implicitly defined null note rdbms require explicitly marking primary key columns codice_1 primary key consists single column column marked using following syntax circumstances natural key uniquely identifies tuple relation may cumbersome use software development example may involve multiple columns large text fields cases surrogate key used instead primary key situations may one candidate key relation candidate key obviously preferred surrogate key may used primary key avoid giving one candidate key artificial primacy others since primary keys exist primarily convenience programmer surrogate primary keys often used many cases exclusively database application design due popularity surrogate primary keys many developers cases even theoreticians come regard surrogate primary keys inalienable part relational data model largely due migration principles object-oriented programming model relational model creating hybrid object-relational model orm like active record pattern additional restrictions placed primary keys however neither restrictions part relational model sql standard due diligence applied deciding immutability primary key values database application design database systems even imply values primary key columns changed using codice_2 sql statement typically one candidate key chosen primary key candidate keys become alternate keys may unique index assigned order prevent duplicates duplicate entry valid unique column alternate keys may used like primary key single-table select filtering clause typically used join multiple tables
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Databases
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peerindex peerindex london-based company providing social media analytics based footprints use major social media services currently facebook linkedin quora twitter part emerging group social media analytics providers peerindex helps social media contributors assess score influence benefit social capital built peerindex currently tracks approximately 45 million twitter profiles making company one leaders sector peerindex founded 2009 azeem azhar former journalist reuters executive ditlev schwanenflügel former mckinsey consultant bill emmott former editor-in-chief economist backed number internet investors peerindex measures influence measuring activity audience authority metrics chosen maximize relevance insight minimizing vulnerability gaming spambots noise authority measures relevant activity community authority measure boosted whenever others like comment and/or engage activity audience measures reach relative rest population activity measures activity compared rest population
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Web technology
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lisp reader programming language lisp reader codice_1 function parser converts textual form lisp objects corresponding internal object structure original lisp s-expressions consisted symbols integers list constructors codice_2 codice_3 later lisps culminating common lisp added literals floating-point complex rational numbers strings constructors vectors reader responsible parsing list structure interning symbols converting numbers internal form calling read macros reader controlled codice_4 defines meaning character unlike programming languages lisp supports parse-time execution programs called read macros reader macros used extend syntax either universal program-specific ways example quoted form codice_5 operator abbreviated codice_6 codice_7 operator defined read macro reads following list wraps codice_8 similarly backquote operator defined read macro
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Programming language topics
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openssh openssh also known openbsd secure shell suite secure networking utilities based secure shell ssh protocol provides secure channel unsecured network client–server architecture openssh started fork free ssh program developed tatu ylönen later versions ylönen ssh proprietary software offered ssh communications security openssh first released 1999 currently developed part openbsd operating system openssh single computer program rather suite programs serve alternatives unencrypted protocols like telnet ftp openssh integrated several operating systems portable version available package systems openssh created openbsd developers alternative original ssh software tatu ylönen proprietary software although source code available original ssh various restrictions imposed use distribution openssh created fork björn grönvall ossh fork tatu ylönen original free ssh 1.2.12 release last one license suitable forking openssh developers claim application secure original due policy producing clean audited code released bsd license open source license word open name refers openssh first appeared openbsd 2.6 first portable release made october 1999 developments since included addition ciphers e.g. chacha20-poly1305 6.5 january 2014 cutting dependency openssl 6.7 october 2014 extension facilitate public key discovery rotation trusted hosts transition dsa ed25519 public host keys version 6.8 march 2015 19 october 2015 microsoft announced openssh natively supported microsoft windows accessible powershell releasing early implementation making code publicly available openssh-based client server programs included windows 10 since version 1803 ssh client key agent enabled available default ssh server optional feature-on-demand openssh developed part openbsd operating system rather including changes operating systems directly openssh separate portability infrastructure maintained openssh portability team portable releases made periodically infrastructure substantial partly openssh required perform authentication capability many varying implementations model also used openbsd projects openntpd openssh suite includes following command-line utilities daemons openssh server authenticate users using standard methods supported ssh protocol password public-key authentication using per-user keys host-based authentication secure version host trust relationships using public keys keyboard-interactive generic challenge-response mechanism often used simple password authentication also make use stronger authenticators tokens kerberos/gssapi server makes use authentication methods native host operating system include using bsd authentication system pluggable authentication modules pam enable additional authentication methods one-time passwords however occasionally side-effects using pam openssh must run root root privileges typically required operate pam openssh versions 3.7 16 september 2003 allow pam disabled run-time regular users run sshd instances openbsd openssh uses dedicated user default drop privileges perform privilege separation accordance principle least privilege applied throughout operating system including xenocara x server openssh includes ability set secured channel data sent local client-side unix domain sockets local client-side tcp ports may forwarded sent across secured channel routing server side forwarding set server instructed send forwarded data socket tcp host/port host could server localhost host may computer appears computer server originator data forwarding data bidirectional meaning return communication forwarded back client-side manner known ssh tunnel used multiplex additional tcp connections single ssh connection since 2004 conceal connections encrypt protocols otherwise unsecured circumvent firewalls sending/receiving manner data one port allowed firewall example x window system tunnel may created automatically using openssh connect remote host protocols http vnc may forwarded easily 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 tunnel connection protocol simpler tcp 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 addition third-party software includes support tunnelling ssh include distcc cvs rsync fetchmail operating systems remote file systems mounted ssh using tools sshfs using fuse ad hoc socks proxy server may created using openssh allows flexible proxying possible ordinary port forwarding beginning version 4.3 openssh implements osi layer 2/3 tun-based vpn flexible openssh tunnelling capabilities allowing applications transparently access remote network resources without modifications make use socks case using default configuration attacker success probability recovering 14 bits plaintext 2 openssh 5.2 release modified behavior openssh server mitigate vulnerability privilege escalation vulnerability existed openssh 6.8 6.9 cve-2015-6565 due world-writable 622 tty devices believed denial service vulnerability use tiocsti ioctl possible inject characters users terminals execute arbitrary commands linux malicious compromised openssh servers could steal private login keys systems using vulnerability relies undocumented connection-resuming feature openssh client called roaming enabled default client supported openssh server applies versions 5.4 released 8 march 2010 7.1 openssh client fixed openssh 7.1p2 released 14 january 2016 cve numbers associated vulnerability cve-2016-0777 information leak cve-2016-0778 buffer overflow february 2001 tatu ylönen chairman cto ssh communications security informed openssh development mailing list company intended assert ownership ssh secure shell trademarks sought change references protocol secsh secsh order maintain control ssh name proposed openssh change name order avoid lawsuit suggestion developers resisted openssh developer damien miller replied urging ylönen reconsider arguing ssh since long generic trademark time ssh secure shell ssh appeared documents proposing protocol open standard hypothesised without marking within proposal registered trademarks ylönen relinquishing exclusive rights name means describing protocol improper use trademark allowing others use trademark incorrectly results trademark becoming generic term like kleenex aspirin opens mark use others study uspto trademark database many online pundits opined term ssh trademarked merely logo using lower case letters ssh addition six years company creation time began defend trademark openssh receiving threats legal repercussions weighed trademark validity developers openssh ylönen members ietf working group developing new standard several meetings group denied ylönen request rename protocol citing concerns would set bad precedent trademark claims ietf participants argued secure shell ssh generic terms could trademarks
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Operating systems
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foreign key context relational databases foreign key set attributes subject certain kind inclusion dependency constraint specifically constraint tuples consisting foreign key attributes one relation r must also exist necessarily distinct relation furthermore attributes must also candidate key s. simpler words foreign key set attributes references candidate key example table called team may attribute member_name foreign key referencing candidate key employee_name employee table since member_name foreign key value existing name member team must also exist employee name employee table table containing foreign key called child table table containing candidate key called referenced parent table database relational modeling implementation candidate key set zero attributes values guaranteed unique tuple row relation value combination values candidate key attributes tuple duplicated tuple relation since purpose foreign key identify particular row referenced table generally required foreign key equal candidate key row primary table else value null value. rule called referential integrity constraint two tables violations constraints source many database problems database management systems provide mechanisms ensure every non-null foreign key corresponds row referenced table example consider database two tables customer table includes customer data order table includes customer orders suppose business requires order must refer single customer reflect database foreign key column added order table e.g. customerid references primary key customer e.g id primary key table must unique customerid contains values primary key field may assume value customerid identify particular customer placed order however longer assumed order table kept date rows customer table deleted id column altered working tables may become difficult many real world databases work around problem 'inactivating rather physically deleting master table foreign keys complex update programs modify references foreign key change needed foreign keys play essential role database design one important part database design making sure relationships real-world entities reflected database references using foreign keys refer one table another another important part database design database normalization tables broken apart foreign keys make possible reconstructed multiple rows referencing child table may refer row referenced parent table case relationship two tables called one many relationship referenced table referencing table addition child parent table may fact table i.e foreign key refers back table foreign key known self-referencing recursive foreign key database management systems often accomplished linking first second reference table table may multiple foreign keys foreign key different parent table foreign key enforced independently database system therefore cascading relationships tables established using foreign keys likewise foreign keys defined part codice_1 sql statement foreign key single column column marked using following syntax foreign keys defined stored procedure statement database management system enforces referential constraints must ensure data integrity rows referenced table deleted updated dependent rows referencing tables still exist references considered specifies 5 different referential actions shall take place occurrences whenever rows master referenced table deleted updated respective rows child referencing table matching foreign key column deleted updated well called cascade delete update value updated deleted row exists referencing child table references value referenced table similarly row deleted long reference referencing child table understand restrict cascade better may helpful notice following difference might immediately clear referential action cascade modifies behavior child table word cascade used example delete cascade effectively says referenced row deleted table master table delete also however referential action restrict modifies behavior master table child table although word restrict appears child table master table delete restrict effectively says someone tries delete row table master table prevent deletion table course also n't delete main point restrict supported microsoft sql 2012 earlier action restrict much alike main difference action restrict action referential integrity check done trying alter table restrict check trying execute update delete statement referential actions act referential integrity check fails update delete statement result error words update delete statement executed referenced table using referential action action dbms verifies end statement execution none referential relationships violated different restrict assumes outset operation violate constraint using action triggers semantics statement may yield end state foreign key relationships violated time constraint finally checked thus allowing statement complete successfully general action taken dbms set null set default delete update value affected referencing attributes changed null set null specified default value set default referential actions generally implemented implied triggers i.e triggers system-generated names often hidden subject limitations user-defined triggers order execution relative triggers may need considered cases may become necessary replace referential action equivalent user-defined trigger ensure proper execution order work around mutating-table limitations another important limitation appears transaction isolation changes row may able fully cascade row referenced data transaction see therefore cascade onto example transaction attempting renumber customer account simultaneous transaction attempting create new invoice customer cascade rule may fix invoice rows transaction see keep consistent renumbered customer row wo n't reach another transaction fix data database guarantee consistent data two transactions commit one forced roll back often first-come-first-served basis first example illustrate foreign keys suppose accounts database table invoices invoice associated particular supplier supplier details name address kept separate table supplier given 'supplier number identify invoice record attribute containing supplier number invoice 'supplier number primary key supplier table foreign key invoices table points primary key relational schema following primary keys marked bold foreign keys marked italics corresponding data definition language statement follows
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Databases
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syhunt syhunt world wide web network security software company headquarters rio de janeiro brazil syhunt founded august 2003 felipe daragon network security specialist company operations currently centered development software relating assessment web servers web applications 2003 syhunt released web application security assessment software known sandcat focuses open web application security project owasp sans institute vulnerabilities syhunt also produced number security software utilities including worm removal tools worm outbreaks server hardening log analysis tools today company still engaged development web application security assessment software also participates common vulnerabilities exposures cve initiative
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Computer security
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referring expression generation referring expression generation reg subtask natural language generation nlg received scholarly attention nlg concerned conversion non-linguistic information natural language reg focuses creation referring expressions noun phrases identify specific entities called targets task split two sections content selection part determines set properties distinguish intended target linguistic realization part defines properties translated natural language variety algorithms developed nlg community generate different types referring expressions referring expression linguistics noun phrase surrogate noun phrase whose function discourse identify individual object thing event ... technical terminology identify differs great deal one school linguistics another widespread term probably refer thing identified referent example work john lyons linguistics study reference relations belongs pragmatics study language use though also matter great interest philosophers especially wishing understand nature knowledge perception cognition generally various devices used reference determiners pronouns proper names ... reference relations different kinds referents real imaginary world discourse may singular plural collective simplest type referring expressions pronoun linguistics natural language processing communities developed various models predicting anaphor referents centering theory ideally referring-expression generation would based models however nlg systems use much simpler algorithms example using pronoun referent mentioned previous sentence sentential clause entity gender mentioned sentence considerable amount research generating definite noun phrases big red book much builds model proposed dale reiter extended various ways example krahmer et al present graph-theoretic model definite np generation many nice properties recent years shared-task event compared different algorithms definite np generation using tuna corpus recently research generating referring expressions time space references tend imprecise exact meaning tonight also interpreted different ways different people hence may necessary explicitly reason false positive vs false negative tradeoffs even calculate utility different possible referring expressions particular task context ideally good referring expression satisfy number criteria reg goes back early days nlg one first approaches done winograd 1972 developed incremental reg algorithm shrdlu program afterwards researchers started model human abilities create referring expressions 1980s new approach topic influenced researchers appelt kronfeld created programs kamp bertrand considered referring expressions parts bigger speech acts interesting findings fact referring expressions used add information beyond identification referent well influence communicative context gricean maxims referring expressions furthermore skepticism concerning naturalness minimal descriptions made appelt kronfeld research foundation later work reg search simple well-defined problems changed direction research early 1990s new approach led dale reiter stressed identification referent central goal like appelt discuss connection gricean maxims referring expressions culminant paper also propose formal problem definition furthermore reiter dale discuss full brevity greedy heuristics algorithms well incremental algorithm ia became one important algorithms reg 2000 research began lift simplifying assumptions made early reg research order create simple algorithms different research groups concentrated different limitations creating several expanded algorithms often extend ia single perspective example relation many simplifying assumptions still place begun worked also combination different extensions yet done called non-trivial enterprise krahmer van deemter another important change 2000 increasing use empirical studies order evaluate algorithms development took place due emergence transparent corpora although still discussions best evaluation metrics use experimental evaluation already led better comparability algorithms discussion goals reg task-oriented research furthermore research extended range related topics choice knowledge representation kr frameworks area main question kr framework suitable use reg remains open answer question depends well descriptions expressed found lot potential kr frameworks left unused far different approaches usage dale reiter 1995 think referring expressions distinguishing descriptions define entity domain characterised set attribute-value pairs example formula_1type dogformula_2 formula_1gender femaleformula_2 formula_1age 10 yearsformula_2 problem defined follows let formula_7 intended referent formula_8 contrast set set formula_9 attribute–value pairs represent distinguishing description following two conditions hold words generate referring expression one looking set properties apply referent distractors problem could easily solved conjoining properties referent often leads long descriptions violating second gricean maxim quantity another approach would find shortest distinguishing description like full brevity algorithm yet practice common instead include condition referring expressions produced algorithm similar human-produced ones possible although often explicitly mentioned full brevity algorithm always finds minimal distinguishing description meaning shorter distinguishing description regard properties used therefore iterates formula_24 checks every description length formula_25 properties distinguishing description found two problems arise way creating referring expressions firstly algorithm high complexity meaning np-hard makes impractical use secondly human speakers produce descriptions minimal many situations greedy heuristics algorithm approximates full brevity algorithm iteratively adding distinguishing property description distinguishing property means property rules remaining distractors greedy heuristics algorithm efficient full brevity algorithm dale reiter 1995 present following algorithm greedy heuristic let formula_9 set properties realised description let formula_27 set properties known true intended referent formula_7 assume formula_27 non-empty let formula_8 set distractors contrast set initial conditions thus follows order describe intended referent formula_7 respect contrast set formula_8 following incremental algorithm ia dale reiter influential algorithm 2000 based idea preferential order attributes properties speakers go order run incremental algorithm first preference order attributes given algorithm follows order adds properties description rule remaining distractors furthermore dale reiter stress attribute type always included descriptions even rule distractors also type values part subsumption hierarchy including basic level values example pet domain chihuahua subsumed dog dog animal dog defined basic level dog would preferred algorithms chihuahua rule distractors incremental algorithm easy implement also computationally efficient running polynomial time description generated ia contain redundant properties superfluous later added properties creators consider weakness rather making expressions less psycholinguistically implausible following algorithm simplified version dale reiter ’ incremental algorithm krahmer van deemter takes input referent r containing collection domain objects domain-specific ordered list pref preferred attributes notation l description c context set distractors function rulesout returns set objects value different v attribute 2000 evaluation reg systems theoretical nature like one done dale reiter recently empirical studies become popular mostly based assumption generated expressions similar human-produced ones corpus-based evaluation began quite late reg due lack suitable data sets still corpus-based evaluation dominant method moment though also evaluation human judgement first distinction text corpora experimental corpora made text corpora like gnome corpus contain texts kind domains reg used evaluate realization part algorithms content selection part reg hand requires corpus contains properties domain objects well properties used references typically fully semantically transparent created experiments using simple controlled settings experimental corpora separated general-purpose corpora collected another purpose analysed referring expressions dedicated corpora focus specifically referring expressions examples general-purpose corpora pear stories map task corpus coconut corpus bishop corpus drawer corpus tuna corpus count dedicated corpora tuna corpus contains web-collected data two domains furniture people used three shared reg challenges already measure correspondence corpora results reg algorithms several metrics developed measure content selection part dice coefficient masi measuring agreement set-valued items metric used measure overlap properties two descriptions evaluation scores usually averaged references made different human participants corpus also sometimes measure called perfect recall percentage prp accuracy used calculates percentage perfect matches algorithm-produced human-produced reference linguistic realization part reg overlap strings measured using metrics like bleu nist problem occurs string-based metrics example small monkey measured closer small donkey little monkey time consuming way evaluate reg algorithms letting humans judge adequacy clear description fluency description given good clear english generated expression also belz gatt evaluated referring expressions using experimental setup participants get generated description click target extrinsic metrics reading time identification time error rate could evaluated
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Computational linguistics
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lira 512 lira 512 also known lira xt ibm pc xt compatible computer made yugoslav serbian company ei niš late 1980s first presented public april 1988 “ kompjuter ‘ 88 ” computer show belgrade soon lira 512 also presented yugoslav computer press separates lira 512 xt compatibles keyboard included case together 3.5 ’ ’ floppy drive made similar appearance original atari st amiga 500 lira two display adapters monochrome hercules compatible color cga compatible active video adapter chosen back-panel switch 40w power adapter also installed case main purpose lira 512 used computer classrooms lira xt tower released year release original lira 512 realized 512 compact case limits hardware expansion address issue especially allow installation hard disk case changed slimline tower time lira xt tower new lira released similar looking slimline tower case lira compatible ibm pc equipped intel 80286 cpu 1mb ram ega compatible video adapter 2x3.5 floppy drives 40mb hard disk serial production lira started december 1989 1990 design lira 386 based intel 80386 cpu ready production
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Computer architecture
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mint software mint server-based web analytics tool tracks traffic trends http referrers search trends developer shaun inman discontinued sales support december 24 2016
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Web technology
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vba32 antivirus vba32 virus block ada 32 antivirus software vendor virusblokada personal computers running microsoft windows detects neutralizes computer viruses computer worms trojan horses malware backdoors adware spyware etc real time demand vba32 used one antivirus engines virustotal virusblokada antivirus software vendor established 1997 belarus 2010 discovered stuxnet first malware attacks supervisory control data acquisition scada systems 2009 judit papp assessed vba32 antivirus product could detect 26 percent unknown malware compared 67 percent detected avira antivir premium 8 percent detected microworld escan anti-virus
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Computer security
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martin richards computer scientist martin richards born 21 july 1940 british computer scientist known development bcpl programming language part early research portable software ancestor b programming language invented ken thompson early versions unix dennis ritchie turn used basis widely used c programming language richards studied mathematics undergraduate student university cambridge took cambridge diploma computer science phd programming language design implementation senior lecturer university cambridge computer laboratory retirement 2007 addition bcpl richards work includes development tripos portable operating system awarded ieee computer society computer pioneer award 2003 pioneering system software portability programming language bcpl richards fellow st johns college university cambridge
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Programming language topics
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vigilante video game game takes place downtown new york city game plot involves lone professional martial artist became vigilante fight evil gang called skinheads ruled man known giant devil order protect turf save female hostage named madonna kidnapped players control titular character using punches kicks defeat skinheads 2d platform manner sometimes picking using nunchaku players get hurt holding nunchuku become unarmed five stages order appearance street junkyard brooklyn bridge back street scene top building construction skinheads mohawk spiked hairdo attack vigilante knives chains motorbikes rifles kinds weapons also cling stands close arcade game later ported several different home computers consoles sega master system version ported arc system works published exclusively north america europe sega one several games console include fm sound switch enhanced music quality sega master system version madonna renamed maria skinheads called rogues ones commodore 64 zx spectrum atari st amiga amstrad cpc reprogrammed emerald software published u.s. gold mostly europe msx version ported published korean company clover turbografx-16 version ported published japan january 14 1989 irem published north america nec year port matches arcade ports turbografx-16 version later re-released globally nintendo virtual console wii north america february 5 2007 japan february 6 2007 europe february 9 2007 australia july 6 2007 delisted march 30 2012 march 31 europe returned september 2013 also released wii u virtual console japan february 10 2015 north america september 14 2017 europe october 5 2017 sinclair summarised game pretty standard beat 'em 've probably seen buy 're addicted genre 've already got better ones
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Computer architecture
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virtual ip address virtual ip address vip vipa ip address n't correspond actual physical network interface uses vips include network address translation especially one-to-many nat fault-tolerance mobility one-to-many nat vip address advertised nat device often router incoming data packets destined vip address routed different actual ip addresses address translation vip addresses several variations implementation scenarios including common address redundancy protocol carp proxy arp addition multiple actual ip addresses load balancing performed part nat vip addresses also used connection redundancy providing alternative fail-over options one machine work host run interior gateway protocol like open shortest path first ospf appear router rest network advertises virtual links connected via actual network interfaces one network interface fails normal ospf topology reconvergence cause traffic sent via another interface vip address used provide nearly unlimited mobility example application ip address physical subnet application moved host subnet vip addresses advertised subnet application moved anywhere reachable network without changing addresses
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Distributed computing architecture
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argonne national laboratory argonne national laboratory science engineering research national laboratory operated university chicago argonne llc united states department energy located lemont illinois outside chicago largest national laboratory size scope midwest argonne initially formed carry enrico fermi work nuclear reactors part manhattan project designated first national laboratory united states july 1 1946 post-war era lab focused primarily non-weapon related nuclear physics designing building first power-producing nuclear reactors helping design reactors used usa nuclear navy wide variety similar projects 1994 lab nuclear mission ended today maintains broad portfolio basic science research energy storage renewable energy environmental sustainability supercomputing national security uchicago argonne llc operator laboratory brings together expertise university chicago sole member llc jacobs engineering group inc. argonne part expanding illinois technology research corridor argonne formerly ran smaller facility called argonne national laboratory-west simply argonne-west idaho next idaho national engineering environmental laboratory 2005 two idaho-based laboratories merged become idaho national laboratory argonne five main areas focus goals stated doe 2008 consist argonne began 1942 metallurgical laboratory university chicago became part manhattan project met lab built chicago pile-1 world first nuclear reactor stands university chicago sports stadium considered unsafe 1943 cp-1 reconstructed cp-2 today known red gate woods argonne forest cook county forest preserve district near palos hills lab named surrounding argonne forest turn named forest argonne france u.s. troops fought world war i. fermi pile originally going constructed argonne forest construction plans set motion labor dispute brought project halt since speed paramount project moved squash court stagg field football field campus university chicago fermi told sure calculations said would lead runaway reaction would contaminated city activities added argonne next five years july 1 1946 metallurgical laboratory formally re-chartered argonne national laboratory cooperative research nucleonics request u.s. atomic energy commission began developing nuclear reactors nation peaceful nuclear energy program late 1940s early 1950s laboratory moved larger location unincorporated dupage county illinois established remote location idaho called argonne-west conduct nuclear research quick succession laboratory designed built chicago pile 3 1944 world first heavy-water moderated reactor experimental breeder reactor chicago pile 4 built idaho lit string four light bulbs world first nuclear-generated electricity 1951 complete list reactors designed cases built operated argonne viewed reactors designed argonne page knowledge gained argonne experiments conducted reactors 1 formed foundation designs commercial reactors currently used throughout world electric power generation 2 inform current evolving designs liquid-metal reactors future commercial power stations conducting classified research laboratory heavily secured employees visitors needed badges pass checkpoint many buildings classified laboratory fenced guarded alluring secrecy drew visitors authorized—including king leopold iii belgium queen frederica greece—and unauthorized shortly past 1 a.m. february 6 1951 argonne guards discovered reporter paul harvey near perimeter fence coat tangled barbed wire searching car guards found previously prepared four-page broadcast detailing saga unauthorized entrance classified hot zone brought federal grand jury charges conspiracy obtain information national security transmit public indicted nuclear technology went developing reactors however designing scanner reactor fuel elements 1957 argonne physicist william nelson beck put arm inside scanner obtained one first ultrasound images human body remote manipulators designed handle radioactive materials laid groundwork complex machines used clean contaminated areas sealed laboratories caves 1964 janus reactor opened study effects neutron radiation biological life providing research guidelines safe exposure levels workers power plants laboratories hospitals scientists argonne pioneered technique analyze moon surface using alpha radiation launched aboard surveyor 5 1967 later analyzed lunar samples apollo 11 mission addition nuclear work laboratory maintained strong presence basic research physics chemistry 1955 argonne chemists co-discovered elements einsteinium fermium elements 99 100 periodic table 1962 laboratory chemists produced first compound inert noble gas xenon opening new field chemical bonding research 1963 discovered hydrated electron high-energy physics made leap forward argonne chosen site 12.5 gev zero gradient synchrotron proton accelerator opened 1963 bubble chamber allowed scientists track motions subatomic particles zipped chamber 1970 observed neutrino hydrogen bubble chamber first time meanwhile laboratory also helping design reactor world first nuclear-powered submarine u.s.s nautilus steamed 513,550 nautical miles 951,090 km next nuclear reactor model experimental boiling water reactor forerunner many modern nuclear plants experimental breeder reactor ii ebr-ii sodium-cooled included fuel recycling facility ebr-ii later modified test reactor designs including fast-neutron reactor 1982 integral fast reactor concept—a revolutionary design reprocessed fuel reduced atomic waste withstood safety tests failures triggered chernobyl three mile island disasters 1994 however u.s. congress terminated funding bulk argonne nuclear programs argonne moved specialize areas capitalizing experience physics chemical sciences metallurgy 1987 laboratory first successfully demonstrate pioneering technique called plasma wakefield acceleration accelerates particles much shorter distances conventional accelerators also cultivated strong battery research program following major push then-director alan schriesheim laboratory chosen site advanced photon source major x-ray facility completed 1995 produced brightest x-rays world time construction 19 march 2019 reported chicago tribune laboratory constructing world powerful supercomputer costing 500 million processing power 1 quintillion flops applications include analysis stars improvements power grid course history 13 eminent scientists served argonne director argonne builds maintains scientific facilities would expensive single company university construct operate facilities used scientists argonne private industry academia national laboratories international scientific organizations argonne welcomes members public age 16 older take guided tours scientific engineering facilities grounds tours last two half hours children 16 argonne offers range hands-on learning activities suitable k–12 field trips scout outings laboratory also hosts educational science engineering outreach schools surrounding area argonne scientists engineers help advance science engineering mathematics education united states taking part training nearly 1,000 college graduate students post-doctoral researchers every year part research development activities significant portions 1996 chase film chain reaction shot zero gradient synchrotron ring room former continuous wave deuterium demonstrator laboratory
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Computer architecture
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pia andrews pia andrews née pia smith also formerly known pia waugh born 1979 open government leader executive director digital government new south wales department finance services innovation andrews spearheaded growth australian open government community organising events govhack govcamp events bring together diverse range citizens want see government data made open reuse previously andrews known work australian free software advocate past positions include presidency software freedom international presidency vice-presidency linux australia andrews employed services company volante several years 2005 andrews appointed research co-ordinator australian service knowledge open source software ask-oss project 2006 andrews then-husband jeff waugh director waugh partners australian open source consultancy waugh partners 2007 nsw state pearcey award young achievers work promoting free software australian ict industry project leader member board directors one laptop per child australia program launched 2008 andrews self-taught computer specialist also studied politics tertiary level involved several projects events promoting ict careers children women april 2009 andrews announced appointment policy advisor kate lundy announced role stepping aside leadership advocacy roles community groups would longer work waugh partners november 2012 andrews joined australian government information management office agimo director coordination gov 2.0 technology procurement division finance john sheridan cto australia charge australian national open data site http //data.gov.au/ 2014 andrews recognised innovation named one australia 100 women influence 2014 australian financial review westpac 100 women influence awards andrews included 2018 list world 100 influential people digital government apolitical group august 2018 andrews appointed executive director digital government news south wales australia andrews held several positions free software community
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Operating systems
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jeff bonwick jeff bonwick invented led development zfs file system used oracle corporation zfs storage products well startups including nexenta delphix joyent datto inc. bonwick also inventor slab allocation used many operating systems including macos linux lzjb compression algorithm roles included sun fellow sun storage cto oracle vice president 2010 bonwick co-founded small company called dssd mike shapiro bill moore became chief technical officer co-invented dssd system hardware architecture software developed dssd whole-system simulator enabled team explore possible hardware topologies software algorithms dssd acquired emc corporation 2014 became part dell technologies 2016 end 2016 bill moore left company bonwick remained cto dssd product called d5 cancelled march 2017
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Operating systems
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donkey kong video game game latest series efforts nintendo break north american market hiroshi yamauchi nintendo president time assigned project first-time video game designer named shigeru miyamoto drawing wide range inspirations including popeye beauty beast king kong miyamoto developed scenario designed game alongside nintendo chief engineer gunpei yokoi two men broke new ground using graphics means characterization including cutscenes advance game plot integrating multiple stages gameplay although nintendo american staff initially apprehensive donkey kong succeeded commercially critically north america japan nintendo licensed game coleco developed home console versions numerous platforms companies cloned nintendo hit avoided royalties altogether miyamoto characters appeared cereal boxes television cartoons dozens places lawsuit brought universal city studios later universal studios alleging donkey kong violated trademark king kong ultimately failed success donkey kong nintendo victory courtroom helped position company video game market dominance release 1981 late 1990s following 1980 space panic donkey kong one earliest examples platform game genre even prior term coined u.s. gaming press used climbing game games platforms ladders first platform game feature jumping donkey kong requires player jump gaps obstacles approaching enemies setting template future platform genre four unique stages donkey kong complex arcade game time release one first arcade games feature multiple stages following 1980 phoenix 1981 gorf scramble competitive video gamers referees stress game high level difficulty compared classic arcade games winning game requires patience ability accurately time mario ascent addition presenting goal saving pauline game also gives player score points awarded following leaping obstacles destroying objects hammer power-up collecting items hats parasols purses presumably belonging pauline removing rivets platforms completing stage determined steadily decreasing bonus counter player typically receives three lives bonus awarded 7,000 points although modified via game built dip switches one life lost whenever mario touches donkey kong enemy object falls far gap end platform lets bonus counter reach zero game divided four different single-screen stages represents 25 meters structure donkey kong climbed one stage 25 meters higher previous final stage occurs 100 meters stage one involves mario scaling construction site made crooked girders ladders jumping hammering barrels oil drums tossed donkey kong stage two involves climbing five-story structure conveyor belts transport cement pans third stage involves player riding elevators avoiding bouncing springs fourth final stage requires mario remove eight rivets platforms supporting donkey kong removing final rivet causes donkey kong fall hero reunited pauline four stages combine form level upon completion fourth stage level increments game repeats stages progressive difficulty example donkey kong begins hurl barrels faster sometimes diagonally fireballs speed victory music alternates levels 1 2 fourth level however consists 5 stages final stage 125 meters 22nd level colloquially known kill screen due error game programming kills mario seconds effectively ending game donkey kong considered earliest video game storyline visually unfolds screen eponymous donkey kong character game de facto villain hero carpenter originally unnamed japanese arcade release later named jumpman mario donkey kong kidnaps mario girlfriend originally known lady later renamed pauline player must take role mario rescue first occurrence damsel distress scenario would provide template countless video games come game uses graphics animation vehicles characterization donkey kong smirks upon mario demise pauline pink dress long hair speech balloon crying help appears frequently beside mario depicted red overalls red cap everyman character type common japan graphical limitations low pixel resolution small sprites prompted design drawing mouth pixels infeasible character given mustache programmers could animate hair got cap make arm movements visible needed colored overalls artwork used cabinets promotional materials make cartoon-like character designs even explicit pauline example depicted disheveled like king kong fay wray torn dress stiletto heels donkey kong first example complete narrative told video game form like 1980 pac-man employs cutscenes advance plot game opens gorilla climbing pair ladders top construction site sets pauline stomps feet causing steel beams change shape moves final perch sneers melody plays level stage starts brief animation sets scene adds background gameplay first video games upon reaching end stage another cutscene begins heart appears mario pauline donkey kong grabs climbs higher causing heart break narrative concludes mario reaches end rivet stage pauline reunited short intermission plays gameplay loops beginning higher level difficulty without formal ending late 1980 early 1981 nintendo efforts expand north america failed culminating attempted export otherwise successful radar scope left large number unsold radar scope machines company president hiroshi yamauchi thought simply converting something new approached young industrial designer named shigeru miyamoto working nintendo since 1977 see could design replacement miyamoto said could yamauchi appointed nintendo head engineer gunpei yokoi supervise project nintendo budget development game 100,000 sources also claim ikegami tsushinki involved development played role game creation concept hired provide mechanical programming assistance fix software created nintendo time nintendo also pursuing license make game based popeye comic strip license attempt failed nintendo took opportunity create new characters could marketed used later games miyamoto came many characters plot concepts eventually settled love triangle gorilla carpenter girlfriend mirrors rivalry bluto popeye olive oyl bluto became ape miyamoto said nothing evil repulsive would pet main character funny hang-loose kind guy miyamoto also named beauty beast 1933 film king kong influences although origin comic strip license played major part donkey kong marked first time storyline video game preceded game programming rather simply appended afterthought unrelated popeye games would eventually released nintendo game watch following month arcades 1982 yamauchi wanted primarily target north american market mandated game given english title though many games point english titles anyway miyamoto decided name game ape felt strongest character story miyamoto came name donkey kong varies false urban myth says name originally meant monkey kong misspelled misinterpreted due blurred fax bad telephone connection another credible story claims miyamoto looked japanese-english dictionary something would mean stubborn gorilla donkey meant convey silly stubborn kong common japanese slang gorilla rival claim worked nintendo export manager come title donkey meant represent stupid goofy end miyamoto stated thought name would convey thought stupid ape miyamoto high hopes new project lacked technical skills program alone instead came concepts consulted technicians see possible wanted make characters different sizes move different manners react various ways yokoi thought miyamoto original design complex though difficult suggestions using see-saws catapult hero across screen eventually found hard program though similar concept would appear aforementioned popeye arcade game miyamoto thought using sloped platforms barrels ladders specified game would multiple stages four-man programming team complained essentially asking make game repeatedly nevertheless followed miyamoto design creating total approximately 20 kilobytes content yukio kaneoka composed simple soundtrack serve background music levels story events circuit board radar scope restructured donkey kong radar scope hardware originally inspired namco galaxian hardware designed large number enemies moving around high speeds donkey kong require development team removed unnecessary functions reduced scale circuit board gameplay graphics reworked updated rom chips existing cpu sound hardware monitor left intact character set scoreboard upper hud display font almost identical radar scope palette differences donkey kong hardware memory capacity displaying 128 foreground sprites 16x16 pixels 256 background tiles 8x8 pixels mario moving objects use single sprites taller pauline uses two sprites larger donkey kong uses six sprites hiroshi yamauchi thought game going sell well phoned inform minoru arakawa head nintendo operations u.s. nintendo american distributors ron judy al stone brought arakawa lawyer named howard lincoln secure trademark game sent nintendo america testing sales manager disliked different maze shooter games common time judy lincoln expressed reservations strange title still arakawa adamantly believed would hit american staff began translating storyline cabinet art naming characters chose pauline lady polly james wife nintendo redmond washington warehouse manager james name jumpman name originally chosen similarity popular brands walkman pac-man eventually changed mario likeness mario segale landlord original office space nintendo america character names printed american cabinet art used promotional materials donkey kong ready release stone judy convinced managers two bars seattle washington set donkey kong machines managers initially showed reluctance saw sales 30 day—or 120 plays—for week straight requested units redmond headquarters skeleton crew composed arakawa wife yoko james judy phillips stone set gutting 2,000 surplus radar scope machines converting donkey kong motherboards power supplies japan game officially went sale july 1981 actor harris shore created first live-action mario television advertisements colecovision hand-held donkey kong donkey kong junior video games makers video game consoles also interested taito offered considerable sum buy rights donkey kong nintendo turned three days discussion within company rivals coleco atari approached nintendo japan united states respectively end yamauchi granted coleco exclusive console tabletop rights donkey kong believed hungriest company addition arakawa believed established company u.s. coleco could better handle marketing return nintendo would receive undisclosed lump sum plus 1.40 per game cartridge sold 1 per tabletop unit december 24 1981 howard lincoln drafted contract included language coleco would held liable anything game cartridge unusual clause licensing agreement arakawa signed document next day february 1 1982 yamauchi persuaded coleco representative japan sign without review company lawyers coleco offer game cartridge stand-alone instead bundled colecovision console went sale august 1982 six months later coleco offered atari 2600 intellivision versions company port atari 5200 system comparable opposed less powerful 2600 intellivision coleco sales doubled 500 million earnings quadrupled 40 million coleco console versions donkey kong sold six million cartridges total grossing 153 million earning nintendo 5 million royalties coleco also released stand-alone mini-arcade tabletop versions donkey kong along pac-man galaxian frogger sold three million units combined meanwhile atari got license computer versions donkey kong released atari 400 800 coleco unveiled adam computer running port donkey kong 1983 consumer electronics show chicago illinois atari protested violation licensing agreement yamauchi demanded arnold greenberg coleco president withdraw adam port version game cartridge-based thus violation nintendo license atari still greenberg complied ray kassar atari fired next month home pc version donkey kong released 1983 atari released several computer versions atarisoft label computer ports cement factory level console versions none home versions intermission animations arcade game donkey kong left side screen barrel level arcade game others right side miyamoto created greatly simplified version game watch multiscreen handheld device ports include apple ii atari 7800 intellivision commodore vic-20 famicom disk system ibm pc booter zx spectrum amstrad cpc msx atari 8-bit family mini-arcade versions two separate distinct ports developed commodore 64 first published atarisoft 1983 second ocean software 1986 game ported nintendo family computer famicom console released japan july 15 1983 one system three launch games also early game famicom international redesign nintendo entertainment system nes launched june 1 1986 north america october 15 1986 europe game ported famicom nes developer nintendo research development 2 arcade classics series nes games cement factory level included however cutscenes since initial rom cartridges enough memory available however port includes new song composed yukio kaneoka title screen donkey kong sequel donkey kong jr. included 1988 nes compilation donkey kong classics complete remake original arcade game game boy titled donkey kong referred donkey kong '94 development contains levels original donkey kong donkey kong jr. arcades starts damsel-in-distress premise four basic locations arcade game progresses 97 additional puzzle-based levels first game built-in enhancement super game boy accessory nes version re-released unlockable game animal crossing gamecube also published virtual console wii wii u nintendo 3ds wii u version also last game released celebrate 30-year anniversary japanese version nes famicom original arcade version game appears nintendo 64 game donkey kong 64 must beaten finish game nintendo released nes version e-reader game boy advance classic nes series 2002 2004 respectively 2004 namco released arcade cabinet contains donkey kong donkey kong jr. mario bros. donkey kong original edition port based nes version reinstates cement factory stage includes intermission animations absent original nes version ever released virtual console preinstalled 25th anniversary pal region red wii systems first released europe october 29 2010 japan download code game nintendo 3ds virtual console sent users purchased new super mario bros. 2 nintendo eshop july 28 september 2 2012 north america download code game nintendo 3ds virtual console sent users purchased one five select 3ds games nintendo eshop registered club nintendo october 1 2012 january 6 2013 europe australia released purchase nintendo 3ds eshop released september 18 2014 europe september 19 2014 australia original arcade version re-released part arcade archives series nintendo switch june 14 2018 nes version re-released one launch titles nintendo switch online september 19 2018 1982 book video invaders steve bloom described donkey kong another bizarre cartoon game courtesy japan donkey kong however extremely popular united states canada game initial 2,000 units sold orders made arakawa began manufacturing electronic components redmond waiting shipments japan taking long october donkey kong selling 4,000 units month late june 1982 nintendo sold 60,000 donkey kong machines overall earned 180 million judy stone worked straight commission became millionaires arakawa used nintendo profits buy land redmond july 1982 nintendo earned another 100 million game second year release totaling 280 million remained nintendo top seller mid-1983 donkey kong also sold steadily japan electronic games speculated june 1983 game home versions contributed arcade version extended popularity compared four six months average game lasted january 1983 1982 arcade awards gave best single-player video game award certificate merit runner-up coin-op game year ed driscoll reviewed atari vcs version donkey kong space gamer 59 edwards commented faults really outweigh plusses especially 've got 'donkey kong fever addicted cure lies elsewhere still play game occasionally never may like cartridge however play store copy try friend buy september 1982 arcade express reviewed colecovision port scored 9 10 creative computing video arcade games 1983 stated coleco fabulous job donkey kong best console first five games faithful adaptation original video game seen magazine danny goodman stated coleco three console versions one colecovision best followed surprisingly atari intellivision order computer video games reviewed colecovision port september 1984 issue scored 4 4 four categories action graphics addiction theme famicom version game sold 840,000 units japan april 1982 sid sheinberg seasoned lawyer president mca universal city studios learned game success suspected might trademark infringement universal king kong april 27 1982 met arnold greenberg coleco threatened sue coleco home version donkey kong coleco agreed may 3 1982 pay royalties universal 3 donkey kong net sale price worth 4.6 million meanwhile sheinberg revoked tiger license make king kong game o. r. rissman refused acknowledge universal claim trademark universal threatened nintendo howard lincoln nintendo refused cave preparation court battle ahead universal agreed allow tiger continue producing king kong game long distinguished donkey kong universal sued nintendo june 29 1982 announced license coleco company sent cease desist letters nintendo licensees agreed pay royalties universal except milton bradley ralston purina universal city studios inc. v. nintendo co. ltd. heard united states district court southern district new york judge robert w. sweet seven days universal counsel new york firm townley updike argued names king kong donkey kong easily confused plot game infringement films nintendo counsel john kirby countered universal argued previous case king kong scenario characters public domain judge sweet ruled nintendo favor awarding company universal profits tiger game 56,689.41 damages attorney fees universal appealed trying prove consumer confusion presenting results telephone survey examples print media people allegedly assumed connection two kongs october 4 1984 however court upheld previous verdict nintendo licensees filed counterclaims universal may 20 1985 judge sweet awarded nintendo 1.8 million legal fees lost revenues expenses however denied nintendo claim damages licensees paid royalties nintendo universal parties appealed judgment verdict upheld july 15 1986 nintendo thanked john kirby gift 30,000 sailboat named donkey kong exclusive worldwide rights use name sailboats later nintendo protagonist named kirby honor court battle also taught nintendo could compete larger entertainment industry companies 1996 next generation listed arcade atari 7800 cancelled coleco adam versions number 50 top 100 games time commenting even ignoring massive historical significance donkey kong stands great game due demanding challenges graphics manage elegantly delineate entire scenario single screen february 2006 nintendo power rated 148th best game made nintendo system today donkey kong fifth popular arcade game among collectors donkey kong inspiration 1983 platform game home computers jumpman according game creator super smash bros. brawl features music game arranged hirokazu hip tanaka stage called 75m almost exact replica donkey kong namesake stage contains items pauline missing perch top stage crazy kong officially licensed nintendo manufactured falcon non-us markets nevertheless crazy kong machines found way american arcades often installed cabinets marked congorilla nintendo quick take legal action distributing game us bootleg copies donkey kong also appeared north america france crazy kong konkey kong donkey king names 1982 logger arcade game century electronics direct clone donkey kong large bird standing ape rolling logs instead barrels 1981 o. r. rissman president tiger electronics obtained license use name king kong universal city studios title tiger created handheld game scenario gameplay based directly nintendo creation many home computer clones directly borrowed gorilla theme killer gorilla bbc micro 1983 killer kong zx spectrum 1983 crazy kong 64 commodore 64 1983 kongo kong commodore 64 1983 donkey king trs-80 color computer 1983 kong ti-99/4a 1983 one first releases electronic arts hard hat mack apple ii 1983 three-stage game without ape using construction site setting donkey kong clones recast game different characters cannonball blitz apple ii 1982 soldier cannonballs replacing ape barrels american southwest-themed canyon climber atari 8-bit 1982 epyx jumpman atari 8-bit 1983 reuses prototypical name mario character donkey kong magazine ad game tagline liked donkey kong 'll love jumpman jumpman along miner 2049er atari 8-bit 1982 mr robot robot factory atari 8-bit 1984 focuses traversing platforms level collecting scattered objects instead climbing top many games multiple ladder platforms stages 1983 electronic games described nintendo popeye game yet another variation theme become familiar since success donkey kong year sega released donkey kong clone called congo bongo arcades although using isometric perspective structure gameplay similar atari 8-bit computer port donkey kong contains one longest-undiscovered easter eggs video game programmer landon dyer initials appear player died certain conditions returned title screen remained undiscovered 26 years dyer revealed blog stating easter egg totally worth n't remember bring anyway steps required trigger later discovered hodges used emulator debugger trace game code donkey kong spawned sequel donkey kong jr. 1982 player controlling donkey kong son attempt save father now-evil mario 1983 spinoff mario bros. introduced mario brother luigi single-screen cooperative game set sewer launched mario franchise also 1983 donkey kong 3 appeared form fixed shooter exterminator ridding ape—and insects—from greenhouse nintendo revived donkey kong franchise 1990s series platform games spin-offs developed rare beginning donkey kong country 1994 2004 nintendo released mario vs. donkey kong sequel game boy donkey kong mario must chase donkey kong get back stolen mini-mario toys follow-up donkey kong falls love pauline kidnaps mario uses mini-mario toys help rescue donkey kong racing gamecube development rare canceled microsoft purchased company 2004 nintendo released first donkey konga games rhythm-based game series uses special bongo controller donkey kong jungle beat 2005 unique platform action game uses bongo controller accessory 2007 donkey kong barrel blast released nintendo wii originally developed gamecube game would used bongo controller delayed released exclusively wii game support bongo accessory donkey kong appears game wii u game nes remix features multiple nes games sometimes remixes presenting significantly modified versions games challenges one challenge features link legend zelda traveling first screen save pauline difficulty increased compared original donkey kong link jump zelda late june 1982 donkey kong success prompted 50 parties u.s. japan license game characters mario simian nemesis appeared cereal boxes board games pajamas manga 1983 animation studio ruby-spears produced donkey kong cartoon well donkey kong jr. saturday supercade program cbs show mystery crime-solving plots mode scooby-doo framed around premise mario pauline chasing donkey kong voiced soupy sales escaped circus show lasted two seasons since original release donkey kong success entrenched game american popular culture 1982 buckner garcia r. cade video victims recorded songs donkey kong donkey kong respectively based game artists like dj jazzy jeff fresh prince trace adkins referenced game songs episodes television series simpsons futurama crank yankers fairly oddparents also contained references game even today sound effects atari 2600 version often serve generic video game sounds films television series phrase like donkey kong used various works popular culture november 2010 nintendo applied trademark phrase united states patent trademark office billy mitchell considered hold donkey kong record 1982 august 2000 surpassed tim sczerby 2007 documentary tells story steve wiebe attempts break donkey kong world record early 2010s hank chien set new record 1,138,600 broken four years later robbie lakeman current world record set robbie lakeman february 2 2018 score 1,247,700 2018 mitchell stripped records twin galaxies banned submitting new scores twin galaxies concluded mitchell illicitly used emulators achieve scores twin galaxies prohibits use emulators high scores publish allow undetectable cheating
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Computer architecture
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google goggles google goggles image recognition mobile app developed google used searches based pictures taken handheld devices example taking picture famous landmark searches information taking picture product barcode would search information product google goggles developed use google android operating system mobile devices initially available beta version android phones google announced plans enable software run platforms notably iphone blackberry devices google discuss non-handheld format google product manager shailesh nalawadi indicated google wanted goggles application platform much like google maps single product october 5 2010 google announced availability google goggles devices running ios 4.0 may 2014 update google mobile ios google goggles feature removed google i/o 2017 similar app google lens announced similar functions goggles uses google assistant app officially discontinued august 20 2018 last update directing users download google lens google photos upon launching app system could identify various labels landmarks allowing users learn items without needing text-based search system could identify products barcodes labels allow users search similar products prices save codes future reference similar cuecat late 1990s system also recognized printed text uses optical character recognition ocr produce text snippet cases even translate snippet another language metropolitan museum art announced december 2011 collaboration google use google goggles providing information artworks museum direct links website metropolitan museum art
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Operating systems
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joli os joli os ubuntu-based linux distribution developed french company jolicloud also name operating system version 1.2 joli os open source project source code hosted github 22 november 2013 developers decided discontinue joli os keep source code open jolicloud discontinued april 1 2016 project launched 2008 netvibes founder tariq krim romain huet krim originally wanted build laptop using environmentally friendly manufacturing methods two co-founders refocused effort building operating system purchasing netbooks renewing acquaintance linux rented office space montorgueil area paris later joined another developer tristan groléat alpha version built help developers kernel hackers designers venture capital firms atomico ventures mangrove capital partners provided 4.2 million funding version 1.0 released july 2010 version 1.1 released 7 december 2010 version 1.2 released 9 march 2011 joli os beginning built top ubuntu netbook edition linux distribution tweaked netbooks computers limited disk storage memory screen size joli os built top ubuntu customized kernel joli os designed easy installation wi-fi bluetooth 3g modem support included operating system supports major netbooks including models asus acer dell hp msi samsung sony jolicloud claims os supports 98 netbooks out-of-the-box compatibility also works large number devices 10 years old laptops desktops tablets version 1.0 operating system incorporates user interface built primarily html5 includes application launcher library compatible applications one-click installation removal display machines associated user account social activity stream enables users compare installed applications launcher displays applications supported library identical configuration viewed machine running joli os account management available computer html5-compatible browser jolicloud html5 implementation chromium web browser serves middleware web rendering reviewers evaluating joli os differed appraisals depending whether writing user new linux experienced operating system writing condé nast traveler blog mike haney called joli os easy free os n't code-monkey install everything need netbook quickly put lenovo netbook weekend running like molasses windows 7 'm convert joli os first operating system designed linux targeted beginning netbooks first n't feel like 're using linux funky install procedures code accessing special directories find apps compared joli os look function ios operating system used apple ipad well iphone ipod touch though folders files conventional computer computerworld serdar yegulalp wrote joli os 1.0 feels like second beta 1.0 release needs work truly useful instead one step curiosity yegulalp reported problems launching applications including google chrome browser vlc media player inability peer-to-peer mesh networking power button getting blocked open windows hibernation mode even computer supports noted comparable performance windows 7 slightly faster boot times zdnet reporter david meyer disagreed performance assessment running jolicloud nokia booklet 3g order take advantage device unusual 720p screen resolution wrote device lousy atom z530 processor ... really struggles windows 7 starter edition flies jolicloud ... 'm struggling think rival linux distro easily picked run average user ars technica ryan paul wrote lot good ideas display jolicloud joli os 1.0 nascent product still feels incomplete saw reason linux users particularly ubuntu users switch ubuntu unity environment sophisticated much better integration native applications underlying platform though joli os might better choice users interested web applications noting joli os 1.0 foundation ubuntu 9.04 nearing end support cycle canonical paul wrote real challenge continuing expand scope joli os differentiating features ... ensuring jolicloud users benefit ubuntu steady stream new features tariq krim defended decision stay ubuntu 9.04 joli os 1.0 arguing later ubuntu versions less stable required user-initiated software installations fully functional examples jolicloud developers additional work ensure out-of-the-box functionality include support poulsbo gma500 drivers touchscreens 3g said company moving away ubuntu solution could fit user needs better looking closely chrome os november 2010 jolicloud shipped netbook computer called jolibook ran operating system box computer manufactured uk-based vye computers featured 10.1-inch screen dual core 1.5 ghz intel atom n550 1gb ram 250gb hard drive artwork lid included slogan fast fun connected machine available united kingdom selling £280 via shop.vyepc.com amazon.co.uk longer manufactured jolicloud released version 1.1 december 2010 new version based ubuntu 10.04 lts lucid future patches planned 10.10 maverick among improvements claimed company faster boot times 10–20 seconds devices tested 15 percent battery life improvements tested clevo m1100 netbook intel atom n450 processor three-cell battery support pcs netbooks version 1.2 announced march 2011 renamed joli os new version featured new boot screen auto guest mode log-ins local file system integrated within desktop remote access desktop html5-capable browser optional background updates support latest chromium 10 browser flash 10.2 version 1.2 also includes dropbox integration app creation wizard file browser access local files preview dropbox files edit using google docs uses 2.2 gb disk space installed
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Distributed computing architecture
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link access procedure link access procedure lap protocols data link layer protocols framing transmitting data across point-to-point links lap originally derived hdlc high-level data link control later updated renamed lapb lap balanced lapb data link protocol x.25 related lap protocols
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Internet protocols
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hospital records database hospital records database database provided wellcome trust uk national archives provides information existence location records uk hospitals includes location dates administrative clinical records existence catalogues links online hospital catalogues website proposed resource month royal society medicine 2009
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Databases
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spark programming language spark formally defined computer programming language based ada programming language intended development high integrity software used systems predictable highly reliable operation essential facilitates development applications demand safety security business integrity originally three versions spark language spark83 spark95 spark2005 based ada 83 ada 95 ada 2005 respectively fourth version spark language spark 2014 based ada 2012 released april 30 2014 spark 2014 complete re-design language supporting verification tools spark language consists well-defined subset ada language uses contracts describe specification components form suitable static dynamic verification spark83/95/2005 contracts encoded ada comments ignored standard ada compiler processed spark examiner associated tools spark 2014 contrast uses ada 2012 built-in aspect syntax express contracts bringing core language main tool spark 2014 gnatprove based gnat/gcc infrastructure re-uses almost entirety gnat ada 2012 front-end spark aims exploit strengths ada trying eliminate potential ambiguities insecurities spark programs design meant unambiguous behavior required unaffected choice ada compiler goals achieved partly omitting ada problematic features unrestricted parallel tasking partly introducing contracts encode application designer intentions requirements certain components program combination approaches meant allow spark meet design objectives consider ada subprogram specification subprogram actually pure ada could virtually anything – might increment codice_1 one one thousand might set global counter codice_1 return original value counter codice_1 might absolutely nothing codice_1 spark 2014 contracts added code provide additional information regarding subprogram actually example may alter specification say specifies codice_5 procedure use neither update read global variable data item used calculating new value codice_1 codice_1 alternatively designer might specify specifies codice_5 use global variable codice_9 package codice_5 exported value codice_9 depends imported values codice_9 codice_1 exported value codice_1 depend variables derived constant data gnatprove run specification corresponding body subprogram analyse body subprogram build model information flow model compared specified annotations discrepancies reported user extend specifications asserting various properties either need hold subprogram called preconditions hold execution subprogram completed postconditions example could say following specifies codice_1 derived alone also codice_5 called codice_1 must strictly less last possible value type afterwards codice_1 equal initial value codice_1 plus one gnatprove also generate set verification conditions vcs vcs used attempt establish certain properties hold given subprogram minimum gnatprove generate vcs attempting establish run-time errors occur within subprogram postcondition assertions added subprogram gnatprove also generate vcs require user show properties hold possible paths subprogram hood gnatprove uses why3 intermediate language vc generator cvc4 z3 alt-ergo theorem provers discharge vcs use provers including interactive proof checkers also possible components why3 toolset first version spark based ada 83 produced university southampton uk ministry defence sponsorship bernard carré trevor jennings subsequently language progressively extended refined first program validation limited praxis critical systems limited 2004 praxis critical systems limited changed name praxis high integrity systems limited january 2010 company became altran praxis early 2009 praxis formed partnership adacore released spark pro terms gpl followed june 2009 spark gpl edition 2009 aimed floss academic communities june 2010 altran-praxis announced spark programming language would used software us lunar project cubesat expected completed 2015 january 2013 altran-praxis changed name altran first pro release spark 2014 announced april 30 2014 quickly followed spark 2014 gpl edition aimed floss academic communities spark used several high profile safety-critical systems covering commercial aviation rolls-royce trent series jet engines arinc acams system lockheed martin c130j military aviation eurofighter typhoon harrier gr9 aermacchi m346 air-traffic management uk nats ifacts system rail numerous signalling applications medical lifeflow ventricular assist device space applications vermont technical college cubesat project spark also used secure systems development users include rockwell collins turnstile secureone cross-domain solutions development original multos ca nsa tokeneer demonstrator secunet multi-level workstation muen separation kernel august 2010 rod chapman principal engineer altran praxis implemented skein one candidates sha-3 spark wanted compare performance spark c implementations careful optimization managed spark version 5 10 slower c. later improvement ada middle-end gcc implemented eric botcazou adacore closed gap spark code matching c performance exactly
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Programming language topics
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variable data intelligent postscript printware variable data intelligent postscript printware open language xerox enables highest-performance output variable-data postscript documents used freeflow vi suite vipp front end vipp originally called xgf simply groups postscript dictionaries provide macros simplify writing complex postscript commands postscript powerful language allows variable data printing personalization data stream right commands implement features programmer write sometimes many lines code xerox developed macro procedures postscript language dictionaries make page control easier example merge graphic form data stream requires understanding postscript commands according adobe postscript language reference manual plrm otherwise known red book xerox gives feature simple command formname setform formname name form accessible xerox printer controller docusp freeflow print server several vipp commands identical postscript commands vipp originally written couple xerox systems analysts switzerland enable highest speed postscript printers time 50 pages per minute features xerox proprietary production printing languages pdl fdl provide simple variable data printing xerox corporation adopted idea developed work putting procedures sun microsystems hosts adobe interpreter also resides together modules give complete control printing engine data stream vipp used four different modes database mode line mode xml mode native mode database mode programmer quickly implement printing solution example billing application delimited database file line mode existing print application enhanced form overlays font selection color features offered modern laser printers xml mode xml file turned readable document modes vipp offers conditional logic manipulation data example multi-page bill could printed duplex two-sided mode first page selected paper tray loaded perforated sheet remittance return back side printed disclosures instructions subsequent pages billing detail printed plain paper vipp programmer might even insert ocr micr line remittance processing complete check digit xerox markets interactive development environment vipp called freeflow vi designer freeflow vipp pro publisher help programmer code applications rapidly vipp freeflow vipp pro publisher plugin popular adobe indesign product enabling wysiwyg vipp development vipp licensed specific printer controllers running solaris microsoft windows operating system including postscript capable office devices non-volatile memory hard disk vipp capable installed device postscript interpreter freeflow print server ffps formerly docusp vipp enabled limited producing 200 pages appropriately licensed
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Programming language topics
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udp unicorn udp unicorn free open source dos attack software software attacks computer network connection repeatedly sending udp packets garbage data udp unicorn uses winsock create sockets send udp packets
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Computer security
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ibm xcf ibm mainframes cross-system coupling facility xcf component z/os manages communications applications sysplex applications may system different systems systems communicate using messages transported one two mechanisms parallel sysplex decisions two transport mechanisms use routing specific message made dynamically within single z/os system messages transported using cross-memory services rather routed either physical transport mechanisms applications join specific groups individual members joining group member send receive messages individual messages assigned specific transport classes based message size transport class owns input output buffers routing decisions made transport class level
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Operating systems
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