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earth fighter rayieza game character designer go nagai also drew illustrations game package game background music composed y. sawamura sawamura included arranged version yellow magic orchestra rydeen battle theme year 2300 human race created earth federation government spread space begin colonizing surrounding planets however alien species far reaches outer space began attacking human forces putting survival human race stake though matter time earth fell enormous power enemy forces earth army commander issued order calling units dispersed around colonized planets return earth player takes role young soldier stationed rayieza unit planet mars journey begins makes way back earth along members unit family computer port game released december 15 1987 though game largely faithful port pc version arrangements made addition side-scrolling screen player lands planet surface rimi able use psychic powers later parts game enemies begin appear frequently new enemy special attacks added lower maximum hit-points allied characters lowered points return next time character level increases
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Computer architecture
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sudo sudo program unix-like computer operating systems allows users run programs security privileges another user default superuser originally stood superuser older versions codice_1 designed run commands superuser however later versions added support running commands superuser also restricted users thus also commonly expanded substitute user although latter case reflects current functionality accurately codice_1 still often called superuser since often used administrative tasks unlike similar command su users must default supply password authentication rather password target user authentication configuration file typically located codice_3 permits user access system invokes requested command configuration file offers detailed access permissions including enabling commands invoking terminal requiring password per user group requiring re-entry password every time never requiring password particular command line also configured permit passing arguments multiple commands robert coggeshall cliff spencer wrote original subsystem around 1980 department computer science suny/buffalo robert coggeshall brought sudo university colorado boulder 1986 1993 code features substantially modified staff university colorado boulder computer science department college engineering applied science including todd c. miller current version publicly maintained openbsd developer todd c. miller since 1994 distributed isc-style license since 1999 november 2009 thomas claburn response concerns microsoft patented sudo characterized suspicions overblown claims narrowly framed particular gui rather sudo concept unlike command su users supply personal password sudo necessary authentication configuration file permits user access system invokes requested command sudo retains user invocation rights grace period 5 minutes per pseudo terminal default see https //www.sudo.ws/man/1.8.27/sudo.man.html allowing user execute several successive commands requested user without provide password sudo may configured log command run user attempts invoke sudo without listed configuration file exception indication presented user indicating attempt recorded root user alerted via mail entry recorded system log file /etc/sudoers contains list users user groups permission execute subset commands privileges root user another specified user program may configured require password system distributions sudo largely supplanted default use distinct superuser login administrative tasks notably linux distributions well apple macos allows secure logging admin commands prevents exploits association selinux sudo used transition roles role-based access control rbac visudo command-line utility allows editing sudo configuration file fail-safe manner prevents multiple simultaneous edits locks performs sanity syntax checks program runas provides similar functionality microsoft windows pass current directories environment variables long command lines child supports running child another user support simple elevation true su sudo windows pass state information start child either elevated another user included hamilton c shell graphical user interfaces exist sudo notably kdesudo gksudo deprecated debian longer included ubuntu release 18.04 user interfaces directly built sudo provide similar temporary privilege elevation administrative purposes user account control microsoft windows mac os x authorization services doas available since openbsd 5.8 october 2015 written order replace sudo openbsd base system latter still made available port
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Computer security
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access level computer science computer programming access level denotes set permissions restrictions provided data type reducing access level effective method limiting failure modes debugging time overall system complexity restricts variable modification methods defined within interface class thus incorporated many fundamental software design patterns general given object created read updated deleted function without sufficient access level two common access levels public private denote respectively permission across entire program scope permission within corresponding class third protected extends permissions subclasses corresponding class access levels modifiers commonly used java well c provides internal level c++ difference struct class default access level private classes public structs illustrate benefit consider public variable accessed part program error occurs culprit could within portion program including various sub-dependencies large code base leads thousands potential sources alternatively consider private variable due access restrictions modifications value must occur via functions defined within class therefore error structurally contained within class often single source file class means debugging requires evaluation single file sufficient modularity minimal access level large code bases avoid many challenges associated complexity retrieved java coffee break q imperative variable balance defined private int ensures classes methods functions accidentally overwrite variable balance instead must access interface class bank_balance whose methods ensure balance drop 0
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Computer security
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cloudflare cloudflare inc. u.s. web infrastructure website security company providing content delivery network services ddos mitigation internet security distributed domain name server services cloudflare services sit website visitor cloudflare user hosting provider acting reverse proxy websites cloudflare headquarters san francisco california additional offices lisbon london singapore munich san jose champaign illinois austin new york city washington d.c. cloudflare faced controversy number times stance providing technical support online hate groups terrorists citing free speech concerns cloudflare ensured continue abide law serve customers explaining proper role internet censor example one time cloudflare provided technical services 8chan image board linked multiple mass shootings united states christchurch mosque shootings new zealand however 2017 cloudflare succumbed pressure longer provide services neo-nazi website daily stormer similarly august 2019 cloudflare stopped services 8chan following mass shooting el paso 2014 cloudflare introduced project galileo response cyber attacks launched important yet vulnerable targets artistic groups humanitarian organizations voices political dissent 2019 cloudflare celebrated five-year anniversary project galileo announced 600 users organisations currently participating cloudflare created 2009 matthew prince lee holloway michelle zatlyn previously worked project honey pot cloudflare launched september 2010 techcrunch disrupt conference received media attention june 2011 providing security lulzsec website june 2012 cloudflare partnered various web hosts including hostpapa implement railgun technology february 2014 cloudflare mitigated largest-ever recorded ddos attack time peaked 400 gbit/s undisclosed customer november 2014 cloudflare reported another massive ddos attack independent media sites targeted 500 gbit/s november 2009 cloudflare raised 2.1 million series round pelion venture partners venrock july 2011 cloudflare raised 20 million series b round new enterprise associates pelion venture partners venrock december 2012 cloudflare raised 50 million series c round new enterprise associates pelion venture partners venrock union square ventures greenspring associates december 2014 cloudflare raised 110 million series round led fidelity investments participation google capital microsoft qualcomm baidu march 2019 cloudflare raised 150 million series e round led franklin templeton investments participation new enterprise associates union square ventures venrock pelion venture partners greenspring associates capitalg microsoft baidu qualcomm fidelity february 2014 acquired stopthehacker offers malware detection automatic malware removal reputation blacklist monitoring december 2016 cloudflare acquired eager view upgrading cloudflare apps platform allow drag-and-drop installation third-party apps onto cloudflare-enabled sites late 2017 cloudflare acquired neumob mobile vpn startup customers cloudflare offers 'm attack mode cloudflare claims mitigate advanced layer 7 attacks presenting javascript computational challenge must completed user browser user access website march 2013 cloudflare defended spamhaus ddos attack exceeded 300 gbit/s akamai chief architect stated time largest publicly announced ddos attack history internet cloudflare also reportedly absorbed attacks peaked 400gbit/s ntp reflection attack cloudflare allows customers paid plans utilize web application firewall service default firewall owasp modsecurity core rule set alongside cloudflare ruleset rulesets popular web applications cloudflare offers free authoritative domain name system dns service clients powered anycast network solvedns found cloudflare consistently one fastest dns lookup speeds worldwide reported lookup speed 5.6ms july 2019 april 1 2018 cloudflare announced 'privacy-first consumer dns service hosted ip addresses 1.1.1.1 1.0.0.1 alternatively service accessed via ipv6 2606:4700:4700 :1111 2606:4700:4700 :1001 november 11 2018 cloudflare announced mobile version 1.1.1.1 service ios android key functionality cloudflare act reverse proxy web traffic cloudflare supports new web protocols including spdy http/2 addition cloudflare offers support http/2 server push cloudflare also supports proxying websockets cloudflare network highest number connections internet exchange points network worldwide cloudflare caches content edge locations act content delivery network cdn requests reverse proxied cloudflare cached content served directly cloudflare 2014 cloudflare introduced project galileo response cyber attacks launched important yet vulnerable targets artistic groups humanitarian organizations voices political dissent working free speech public interest civil society organizations cloudflare extended enterprise-class ddos protection business-level performance benefits ensure websites stay online without violated project galileo compared alphabet project shield different service providing protection vulnerable humanitarian free-speech groups contrast project shield project galileo create guidelines eligible users rather outsourced selection 28 non-profit organisations one accept users program cloudflare ceo matthew prince hopes companies follow suit start similar projects according project galileo users organisations benefit able choose work notion echoed cloudflare ceo since project started 2014 cloudflare remained fairly secretive project part avoid drawing attention organisations might targeted five-year anniversary project blogpost created sharing detail service revealing 600 organisations currently participating announcing number new additions cloudflare created project athenian ensure state local government election websites highest level protection enterprise grade reliability free constituents always access election information voter registration 2019 cloudflare announced new domain registrar service promised offer low-cost wholesale pricing easy ways enable dnssec april 1 2019 cloudflare announced new freemium virtual private network service named warp service would initially available 1.1.1.1 mobile apps desktop app available later june 21 2019 cloudflare announced users would able sync computers time securely cloudflare ntp service cloudflare ’ time service allow users connect network time protocol ntp server supports network time security nts enabling users obtain time authenticated manner cloudflare provides dns services 12 million websites adding approximately 20,000 new customers every day cloudflare provided support services 8chan august 2019 8chan since moved bitmitigate august 3 interview immediately post 2019 el paso shooting guardian matthew prince defended cloudflare support 8chan saying happened el paso today abhorrent every possible way ’ ugly hate ’ association us … us question worse evil cloudflare come pressure multiple occasions due ironclad policy free speech refusing cease technical support dns routing ddos mitigation etc websites lulzsec daily stormer 8chan activists argue cloudflare services allow access content spreads hate led harm deaths cloudflare consider content passes infrastructure protected first amendment matter content consequences.cloudflare broad legal immunity content produced users cloudflare provided dos protection hacker group lulzsec services garnered significant positive media attention time cloudflare young relatively unknown company cloudflare provided dns routing dos protection white supremacist neo-nazi website daily stormer 2017 cloudflare stopped providing services daily stormer announcement controversial website asserted upper-echelons cloudflare secretly supporters ideology previously cloudflare refused take action regarding daily stormer despite widespread public pressure removal addressed blogpost cloudflare emphasized dedication towards freedom speech 'free speech absolutist cloudflare ceo matthew prince vowed never succumb external pressure sought create 'political umbrella future matthew prince addressed dangers large companies deciding allowed stay online concern shared number civil liberties groups privacy experts electronic frontier foundation said services cloudflare adjudicating speech acceptable adding illegal activity like inciting violence defamation occurs proper channel deal legal system according huffington post cloudflare provides services least 7 terrorist groups designated united states department state according article cloudflare provides services taliban hamas al-quds brigades among others aware since least 2012 taken action us justice department asked company discontinue services cloudflare came pressure due technical support provided discussion board 8chan allows users post discuss content free interference site administrator message board linked mass shootings united states christchurch mosque shootings new zealand addition number news organizations including washington post daily dot reported child pornography child rape discussion boards wake 2019 el paso shooting cloudflare announced terminating support 8chan due consistent use site terror purposes announcement ceo matthew prince warned end 8chan described previous events daily stormer unfortunately seen situation good sense play almost exactly two years ago made determination kick another disgusting site cloudflare network daily stormer caused brief interruption site operations quickly came back online using cloudflare competitor competitor time promoted feature fact n't respond legal process today daily stormer still available still disgusting bragged readers ever longer cloudflare problem remain internet problem wake pressured censor daily stormer cloudflare sought create alliance free speech organizations company could stand pressure next time number organizations including electronic frontier foundation u.s. digital rights charity joined project galileo supporting cloudflare free speech stance cloudflare vocal values ceo matthew prince stating one greatest strengths united states belief speech particularly political speech sacred website course nothing speech ... website speech bomb imminent danger creates provider affirmative obligation monitor make determinations theoretically harmful nature speech site may contain cloudflare services used rescator website sells payment card data two islamic state iraq levant top three online chat forums guarded cloudflare u.s. law enforcement asked discontinue service chosen november 2015 anonymous discouraged use cloudflare services following isil attacks paris renewed accusation provides help terrorists cloudflare responded calling accusers 15-year-old kids guy fawkes masks saying whenever concerns raised consult actual anti-terrorism experts abide law breaking long-standing policy total content neutrality cloudflare withdrew access services white supremacist web site daily stormer 16 august 2017 aftermath fatal vehicular attack charlottesville rally four days earlier withdrew website protection distributed denial service attack soon thereafter attackers took website ceo matthew prince stated woke morning bad mood decided kick internet tipping point decision team behind daily stormer made claim secretly supporters ideology andrew anglin editor daily stormer denied team made claim move disconnect daily stormer cloudflare services criticised 'dangerous prince anglin electronic frontier foundation august 2019 cloudflare terminated services 8chan american image board hacker group ugnazi attacked cloudflare partially via flaws google authentication systems june 2012 gaining administrative access cloudflare using deface 4chan cloudflare published full details hack following google publicly announced patched flaw google enterprise app account recovery process allowed hackers bypass two-step verification september 2016 february 2017 major cloudflare bug nicknamed cloudbleed leaked sensitive data—including passwords authentication tokens customer websites sending extra data response web requests leaks resulted buffer overflow occurred according analysis cloudflare approximately 1 every 3,300,000 http requests cloudflare publishes transparency report semi-annual basis show often law enforcement agencies request data clients may 2017 propublica reported cloudflare matter policy relays names email addresses persons complaining hate sites sites question led complainants harassed cloudflare general counsel defended company policies saying base constitutional law people face accusers response cloudflare updated abuse reporting process provide greater control notify complaining party cloudflare listed spamhaus providing spam support services pink contract current list spamhaus listings changes near daily basis reported issues addressed responsible website owner october 2015 report found cloudflare provisioned 40 ssl certificates used phishing sites deceptive domain names resembling banks payment processors july 2019 cloudflare suffered major outage rendered 12 million websites unreachable 27 minutes 80 customers affected websites responded blank 502 error page cloudflare published internal investigation results cause outage pinpointed faulty regular expression
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Computer security
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nimblex nimblex small slackware-based linux distribution optimized run cd usb drive network environment nimblex praised fast boots well small disk footprint considered surprising distribution using kde desktop environment nimblex also remarked web site allows users generate custom bootable images using web browser also covered mainstream romanian press first linux distribution put together romanian nimblex reported boot fast important factor user experience running optical media usb drives review 2007 nimblex edition noted expect boot less half time live cd fedora ubuntu knoppix takes recent review 2008 edition also noted nimblex speed easily one fastest bootups 've seen even tried hinder cripple boot time even dog slow pendrive old dirt test machine still booted amazingly fast desktop applications also fast nimblex also compact distribution review 2007 edition wondered managed include kde mention applications included size 200 mb window-based graphical user interface slimmed kde fit firefox web browser office documents editor koffice pdf reader media player play almost file formats without need install codec photo editing software gimp anti-virus bluetooth support integrated name applications included 2008 installation process major linux distributions customized creating custom installation disks usually called spins creating spin requires certain amount expertise creating spin run installation media requires customization nimblex makes process user-friendly providing web interface process similar embedded linux distributions e.g freewrt features made distribution popular early judge forums nimblex attracted surprisingly large number users relatively unknown distribution nimblex uses 2.6 kernel default gui kde slower computers default desktop environment exchanged one lower resource usage like fluxbox xfce typical office web browsing messaging components included nimblex hardly offers graphical administration tools — administration tasks like adding new user performed command line tradeoff allows nimblex small installation footprint — typical installation 400 megabytes additional applications installed using graphical installer gslapt codice_1 command line brings automatic resolution dependencies slackware packages text-mode hard driver installer available codice_2 considered beta quality 2008 edition 2008 edition comes three standard install images 200mb two smaller even ones 100 69mb installers allow customizations packets installation however nimblex 2008 uses kde 3.5.9 nimblex 2010 beta version also present site based kde 4 support new hardware user also enable compiz fusion via link desktop openoffice.org included instead koffice provided office suite nimblex included 200 mb package useful applications like firefox web browser koffice pdf reader kopete instant messenger klamav anti-virus gimp photo editor bluetooth support remote connection pc important software supported bigger nimblex package openoffice.org java python samba wine windows applications emulator many applications compiled community included distribution nimblex 2008 criticized irresponsible lacking common security features box even though clamav anti-virus guarddog firewall installed default non-root user account created installation root password required log desktop default root password displayed nimblex web site nimblex 2010 also fixed applications removed another problem nimblex packages created repackaging slackware packages since nimblex installs fewer libraries sometimes results uninstallable unusable packages reviews
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Operating systems
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hierarchical music specification language hierarchical music specification language hmsl music programming language written 1980s larry polansky phil burk david rosenboom mills college written top forth allowed creation real-time interactive music performance systems algorithmic composition software kind program requires high degree musical informatics distributed frog peak music runs light memory footprint ~1 megabyte macintosh amiga systems unlike csound languages audio synthesis hmsl primarily language making music interfaces sound-making devices built-in midi classes however high degree built-in understanding music performance practice tuning systems score reading main interface manipulation musical parameters metaphor shapes created altered combined create musical texture either response real-time scheduled events score hmsl widely used composers working algorithmic composition twenty years addition authors also composers hmsl used pieces nick didkovsky hub james tenney tom erbe pauline oliveros java port hmsl developed nick didkovsky name jmsl designed interface jsyn api
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Programming language topics
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.exe exe file contains executable program windows exe short executable standard file extension used windows programs many windows users exe files synonymous windows programs making .exe one recognizable file extensions several file formats may used file extension 16-bit 32-bit windows executable run windows execution starts either ne pe ignores mz code known dos stub started dos stub typically displays message program run dos mode similar exiting cleanly thereby constituting minimal form fat binary dual-mode programs mz-ne mz-pe regedit older winzip self extractors include functional dos section besides also many custom exe formats including limited w3 collection le files used win386.exe w4 compressed collection le files used vmm32.vxd dl mp p2 p3 last three used phar lap extenders
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Operating systems
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mark rasch mark d. rasch attorney author working areas corporate government cybersecurity privacy incident response former chief security evangelist verizon communications vice president deputy general counsel chief privacy data security officer saic 1983 1992 rasch worked u.s. department justice within criminal division fraud section rasch earned j.d 1983 state university new york buffalo 1976 graduate bronx high school science prosecuted robert tappan morris case united states v. morris 1991 also drafted amicus brief related data encryption doj v bernstein prosecuted presidential candidate lyndon larouche organized crime figures new york associated gambino crime family also helped uncover individual responsible so-called craigslist murder boston assisted investigation lead arrest chelsea manning rasch regular contributor securitycurrent securityfocus security boulevard issues related law technology regular contributor wired magazine also longtime columnist storefrontbacktalk now-defunct publication tracked global retail technology appeared quoted msnbc fox news cnn new york times forbes pbs washington post npr national international media
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Computer security
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remark media remark media global digital media company specializes creating technology platforms user interfaces combine content social media spun discovery communications howstuffworks 2007 remark media owns operates international versions howstuffworks china brazil digital publisher certain content world book china company founding partner sharecare searchable social q healthcare platform organizing answering questions health company formerly known hsw international remark media also provides client services including strategic counsel concept design content production technology development implementation project management analytics company clients include major media companies boutique businesses start-ups company publicly listed nasdaq included russell index approximately 100 employees worldwide u.s. offices new york atlanta international offices beijing são paulo 2006 hsw international founded subsidiary howstuffworks bring website global emerging economies one year later company launched first international version howstuffworks – comotudofunciona brazil october 2007 hsw international went public nasdaq connection merger intac international merger facilitated launch company ’ second international version howstuffworks – bowenwang china 2008 2008 company acquired us website dailystrength – social media website hosting health wellness discussions starting 2009 part establishing joint venture harpo studios dr. mehmet oz discovery communications sony pictures television jeff arnold founder webmd company developed launched social q health website sharecare may 2011 partnership discovery communications company developed launched website curiosity.discovery.com – q site discovery channel ’ tv show curiosity october 2011 company announced would change name remark media december 2011 company formally changed name remark media nasdaq stock ticker mark
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Web technology
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amazon elastic file system amazon elastic file system amazon efs cloud storage service provided amazon web services aws designed provide scalable elastic concurrent restrictions encrypted file storage use aws cloud services on-premises resources amazon efs built able grow shrink automatically files added removed amazon efs supports network file system nfs versions 4.0 4.1 nfsv4 protocol control access files portable operating system interface posix permissions according amazon use cases file system service typically include content repositories development environments web server farms home directories big data applications amazon efs provides open-after-close consistency semantics applications expect nfs amazon efs available aws regions asia pacific seoul became available may 2018
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Computer file systems
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gnu fcrypt gnu fcrypt disk encryption software project intended offer multiple hidden partitions fly encryption automatic transparent encryption plausible deniability disbanded project part gnu project november 2012 richard stallman dubbed fcrypt official gnu project program called gnu fcrypt software encryption intended prove resistant cracked quantum computers
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Computer file systems
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synthesis toolkit synthesis toolkit stk open source api real time audio synthesis emphasis classes facilitate development physical modelling synthesizers written c++ written maintained perry cook princeton university gary scavone mcgill university contains low-level synthesis signal processing classes oscillators filters etc higher-level instrument classes contain examples currently available physical modelling algorithms use today stk free software number classes particularly physical modelling algorithms covered patents held stanford university yamaha stk used widely creating software synthesis applications versions stk instrument classes integrated chuck csound real-time cmix max/msp part percolate supercollider faust ported symbianos ios well
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Programming language topics
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appserver.io appserver.io application server php based web environments project consists middleware delivers classical php web applications provides additional services basic idea wildfly equivalent php present within techdivision well july 2013 development project began due technical shortcomings php language time possibility non-blocking socket-based php middleware given using asynchronous event driven workflow forked processes parallel august 2012 threading extension php joe watkins enabled true posix compatible multithreading controversially threads used allow programmer account hardware usage instead relying used runtime environment enable easier communication parallel working batches deciding technical blueprint development began github platform project consisted 36 separate repositories around 80,000 lines code estimated effort 18 years cocomo model appserver.io open-source software osl version 3.0 downloaded either installable package project page source github project aims freemium marketing approach splitting software community professional enterprise edition community edition contained base features open source free charge professional edition could used within microsoft azure cloud service offers additional developer support appserver.io includes runtime environment containing php extended external libraries php extensions service daemons out-of-the-box runtime environment php development use multithreading environment considered break so-called shared nothing concept php allows inter-process communication object level together bundled runtime appserver.io bundles administration version 0.6.0 application management implemented file-based application deployment appserver.io offers servlets objects persist client requests eliminate repeated bootstrapping applications require wrapping bootstrap parts appserver.io offers enterprise bean implementation similar enterprise java beans functionality appserver.io offers modular services used individually internal external applications features appserver.io allows component-based scalability services servers e.g http webserver adjustable size number based xml configuration file additional components configured remote access allowing distributed systems component replication appserver.io early stage development project provided tested pre-release versions github development releases regularly published homepage appserver.io follows naming convention based major minor version numbers major digit specifies context minor version names exist 1.* major version named iron stands mythological view medieval age every minor version 1.x within major release consist noun describing something common major context
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Distributed computing architecture
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loader computing computer systems loader part operating system responsible loading programs libraries one essential stages process starting program places programs memory prepares execution loading program involves reading contents executable file containing program instructions memory carrying required preparatory tasks prepare executable running loading complete operating system starts program passing control loaded program code operating systems support program loading loaders apart highly specialized computer systems fixed set specialized programs embedded systems typically loaders instead code executes directly rom order load operating system part booting specialized boot loader used many operating systems loader resides permanently memory though operating systems support virtual memory may allow loader located region memory pageable case operating systems support virtual memory loader may actually copy contents executable files memory rather may simply declare virtual memory subsystem mapping region memory allocated contain running program code contents associated executable file see memory-mapped file virtual memory subsystem made aware pages region memory need filled demand program execution actually hits areas unfilled memory may mean parts program code actually copied memory actually used unused code may never loaded memory unix loader handler system call codice_1 unix loader tasks include microsoft windows 7 loader codice_3 function contained ntdll.dll following operating systems need relocating loaders adjust addresses pointers executable compensate variations address loading starts operating systems need relocating loaders program always loaded location address space pointers absolute addresses rather offsets program base address well-known examples ibm os/360 system/360 mainframes descendants including z/os z/architecture mainframes os/360 descendant systems privileged operating system facility called iewfetch internal component os supervisor whereas non-privileged loader application perform many functions plus linkage editor entirely external os supervisor although certainly uses many supervisor services iewfetch utilizes highly specialized channel programs theoretically possible load relocate entire executable within one revolution dasd media 16.6 ms maximum 8.3 ms average legacy 3,600 rpm drives load modules exceed track size also possible load relocate entire module without losing revolution media iewfetch also incorporates facilities so-called overlay structures facilitates running potentially large executables minimum memory model small 44 kb versions os 88 kb 128 kb common os nucleus always resident portion supervisor formatted way compatible stripped-down version iewfetch unlike normal executables os nucleus scatter loaded parts nucleus loaded different portions memory particular certain system tables required reside initial 64 kb tables code may reside elsewhere system linkage editor application named iewl iewl main function associate load modules executable programs object modules output say assemblers compilers including automatic calls libraries high-level language built-in functions format may efficiently loaded iewfetch large number editing options conventional application commonly employed load module format includes initial text record followed immediately relocation and/or control record text record followed instances text record relocation and/or control record pairs end module text records usually large relocation and/or control records small iewfetch three relocation and/or control record buffers fixed 260 bytes smaller relocation and/or control records certainly possible 260 bytes maximum possible iewl ensures limitation complied inserting additional relocation records required next text record necessary special case sequence records may ... text record relocation record ... control record text record ... special byte within relocation and/or control record buffer used disabled bit spin communication area initialized unique value read ccw relocation and/or control record program controlled interrupt bit set processor thereby notified ccw accessed channel via special ios exit point processor enters disabled bit spin loop sometimes called shortest loop world byte changes initialized value cpu exits bit spin relocation occurs gap within media relocation and/or control record next text record relocation finished next record nop ccw following read changed tic loading relocating proceed using next buffer channel stop nop ccw restarted iewfetch via another special ios exit three buffers continuous circular queue pointing next last pointing first three buffers constantly reused loading relocating proceeds iewfetch thereby load relocate load module practical size minimum possible time dynamic linking loaders another type loader load link shared libraries like .so files .dll files already loaded running programs
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Computer architecture
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composite application computing composite application software application built combining multiple existing functions new application technical concept compared mashups however composite applications use business sources e.g. existing modules even web services information mashups usually rely web-based often free sources wrong assume composite applications definition part service-oriented architecture soa composite applications built using technology architecture composite application consists functionality drawn several different sources components may individual selected functions within applications entire systems whose outputs packaged business functions modules web services composite applications often incorporate orchestration local application logic control composed functions interact produce new derived functionality composite applications based soa ws-caf web services standard composite applications
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Web technology
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host based security system host based security system hbss official name given united states department defense dod commercial-off-the-shelf cots suite software applications used within dod monitor detect defend dod computer networks systems enterprise-wide information assurance computer network defense solutions steering group essg sponsored acquisition hbss system use within dod enterprise network hbss deployed non-classified internet protocol routed network niprnet secret internet protocol routed network siprnet networks priority given installing niprnet hbss based mcafee inc epolicy orchestrator epo mcafee point product security applications host intrusion prevention system hips seeing need supply comprehensive department-wide security suite tools dod system administrators essg started gather requirements formation host-based security system summer 2005 march 2006 bae systems mcafee awarded contract supply automated host-based security system department award 22 pilot sites identified receive first deployments hbss pilot roll dod system administrators around world identified trained using hbss software preparation software deployment across dod october 9 2007 joint task force global network operations jtf-gno released communications tasking order cto 07-12 deployment host based security system hbss mandating deployment hbss combatant command service agency cc/s/a networks within dod completion date 3rd quarter 2008 release cto brought hbss attention major department heads cc/s/a providing essg necessary authority enforce deployment agencies willing comply cto risked disconnected dod global information grid gig lack compliance lessons learned pilot deployments provided valuable insight hbss program eventually leading defense information systems agency disa supplying pre-loaded hbss hardware well providing hbss software image could loaded compliant hardware platforms proved invaluable easing deployment task newly trained hbss system administrators provided consistent department-wide software baseline disa provided step-by-step documentation completing hbss baseline creation freshly installed operating system lessons learned niprnet deployments simplified process deploying hbss siprnet throughout lifetime hbss undergone several major baseline updates well minor maintenance releases first major release hbss known baseline 1.0 contained mcafee epolicy orchestrator engine hips software compliance profiler scp rogue system detection rsd asset baseline manager abm assets software new releases introduced software products evolved new products added cases completely replaced different products january 2011 hbss currently baseline 4.5 maintenance release 2.0 mr2 mr2 contains following software heart mcafee epolicy orchestrator epo management engine hbss mcafee tools responsible mcafee considers point product individual software applications controlled epo server hbss point products consist following host intrusion prevention system hips consists host-based firewall application-level blocking consolidated single product hips component one significant components hbss provides capability block known intrusion signatures restrict unauthorized services applications running host machines policy auditor pa introduced hbss baseline 2.0 policy auditor responsible ensuring compliance mandates payment card industry data security standard pci dss sarbanes–oxley act 2002 sox gramm–leach–bliley act 1999 glba health insurance portability accountability act 1996 hipaa federal information security management act 2002 fisma well best practice frameworks control objectives information related technology cobit pa maps controls predefined policy content mcafee policy auditor helps report consistently accurately key industry mandates internal policies across infrastructure specific targeted systems policy auditor agent-based audit solution leverages security content automation protocol scap automate processes required internal external audits assets baseline module released baseline 1.0 government off-the-shelf gots product used address system baseline configurations changes order respond information operations condition infocon infocon changes necessary times heightened security threats system initial deployment stages hbss assets module juvenile lacked much products intended capabilities however application fully evolved robust feature packed version capable handling original software design goals abm originally known assets 1.0 upgraded assets 2.0 hbss baseline 2.0 later called assets 3000 hbss baseline 3.0 rogue system detector rsd component hbss used provide real-time detection new hosts attaching network rsd monitors network segments reports hosts seen network epo server epo server determines whether system connected epo server mcafee agent installed identified exception considered rogue epo server take appropriate action concerning rogue host specified rsd policy hbss baseline 1.0 introduced rsd 1.0 rsd updated 2.0 hbss baseline 2.0 dcm component hbss introduced hbss baseline 2.0 specifically address use usb devices dod networks jtf-gno cto 09-xxx removable flash media device implementation within department defense dod networks released march 2009 allowed use usb removable media provided meets conditions stated within cto one conditions requires use hbss dcm module installed configured manage usb devices attached system dcm renamed data loss prevention dlp hbss baseline 3.0 mr3 assets publishing service aps hbss introduced hbss baseline 4.0 allow enclaves report asset information third-party dod entity standards-compliant format adds contextual information hbss assets allows improved reporting features systems relying hbss data according jtf-gno cto 07-12 dod agencies required deploy hbss networks disa made hbss software available download pki protected patch server users attempting download software required common access card cac .mil network disa provides software updates free charge dod entities additionally hbss administrators require satisfactory completion hbss training commonly appointed unit section commander writing order receive administer hbss system system administrators must satisfactorily complete online class hbss training well identified hbss administrator online training takes 30 hours complete class training requires four days excluding travel advanced hbss class also available hbss administrators wishing acquire in-depth knowledge system hbss online class training managed disa information pertaining training classes obtained disa information assurance support environment iase website disa risk management executive office formerly field security office fso provides free technical support hbss administrators help desk disa three tiers support tier tier iii tier tier ii support provided disa fso tier iii support provided mcafee disa fso support available using one following methods current pace hbss updated several times original baseline 1.0 current baseline 3.0 mr3 version within baseline 3.0 maintenance releases introduced every two four months bringing better stability security release hbss follows mcafee epo version updates closely expected continue trend epo continuously developed
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Computer security
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tibero tibero relational databases database management system utility developed tmaxsoft tmaxsoft developing tibero since 2003 2008 second company world deliver shared-disk-based cluster tac main products tibero tibero mmdb tibero prosync tibero infinidata tibero datahub tibero relational database management system rdbms considered alternative oracle databases due complete compatibility oracle products including sql tibero guarantees reliable database transactions logical sets sql statements supporting acid atomicity consistency isolation durability providing enhanced synchronization databases tibero 5 enables reliable database service operation multi node environment tibero implemented unique tibero thread architecture address disadvantages previous dbms result tibero make efficient use system resources cpu memory fewer server processes ensures tibero offers combination performance stability expandability facilitating development administration functions additionally provides users developers various standard development interface easily integrate dbms 3rd party tools addition block transfer technology applied improve ‘ tibero active cluster ’ shared db clustering technology similar oracle rac tibero supports self-tuning based performance optimization reliable database monitoring performance management korea tibero adopted 450 companies across range industries finance manufacturing communication public sector globally 14 companies july 2011 tibero uses multiple working processes working process uses multiple threads number processes threads changed user requests handled thread pool removes overhead dispatcher handles input/output processing memory usage number os processes reduced using thread pool number simultaneous processes changed tibero following three processes listener receives requests new connections clients assigns available working thread listener plays intermediate role clients working threads using independent executable file tblistener background processes independent processes primarily perform time-consuming disk operations specified intervals request working thread another background process following processes belong background process group tibero rdbms provides distributed database links data replication database clustering tibero active cluster tac similar oracle rac. parallel query processing query optimizer conforms sql standard specifications development interfaces guarantees high compatibility types databases features include row-level locking multi-version concurrency control parallel query processing partition table support tibero rdbms enables stable efficient management dbmss guarantees high-performance transaction processing using tibero active cluster hereafter tac technology failover operation based shared disk clustering system environment tac allows instances different nodes share data via shared disk supports stable system operation 24x365 fail-over function optimal transaction processing guaranteeing integrity data instance ’ memory tac main feature tibero providing high scalability availability instances executed tac environment execute transactions using shared database access shared database mutually controlled data consistency conformity processing time reduced larger job divided smaller jobs jobs performed several nodes multiple systems share data files based shared disks nodes act use single shared cache sending receiving data blocks necessary organize tac high speed private network connects nodes even node stops operating nodes continue services transition happens quickly transparently tac cluster system application level provides high availability scalability types applications recommended apply replication architecture servers also hardware storage devices helps improve high availability virtual ip vip assigned node tac cluster node tac cluster failed public ip accessed virtual ip used connections connection failover following main components tac
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Databases
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ggpo ggpo short good game peace middleware designed help create near-lagless online experience various emulated arcade games fighting games program created tony cannon co-founder fighting game community site shoryuken popular evolution championship series creation ggpo creator tony cannon completely dissatisfied 2006 xbox 360 re-release experiencing criticized online capabilities reaction service cannon began development ggpo released first ever version late 2006 cannon later demonstrated ggpo capcom positively received downloadable ggpo client supported many games capcom snk including super street fighter ii turbo king fighters 2002 metal slug x use built-in emulator video game companies also implemented licensed version ggpo games using include skullgirls killer instinct 2013 video game ggpo uses netcode technique called “ rollback ” rather waiting input received players simulating next frame ggpo predicts inputs send simulates next frame without delay using assumption players ’ inputs arrive input ’ match prediction ggpo rolls back state game last correct state replays players ’ revised inputs back current frame hope predictions correct time allowing smooth play minimal sudden changes game state system highly similar client-side prediction applied peer-to-peer setup client program allow players manually adjust latency high-ping situations either creating possibly-jerky yet accurate representation smoother game input delay ggpo originally bundled client enabled users play supported games online players matchmaking system allowed players request challenges users non-participants could spectate match chat challenge initiated match ran rom prepackaged emulator finalburn alpha client discontinued superseded clients make use ggpo networking middleware
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Distributed computing architecture
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runscanner runscanner freeware microsoft windows system utility scans windows system configured running programs autostart locations program created best worlds effort combine positive features similar programs like hijackthis autoruns silentrunners unlike similar programs runscanner connects online database rate good bad items main purpose database whitelisting instead blacklisting runscanner scans windows autostart locations gives user possibility delete misconfigured malware items inexperienced users post log files forums specialist helpers help solve malware problems advanced users use features modern malware fighters come expect unlike similar software runscanner also exchange binary files users
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Computer security
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virtual machine introspection computing virtual machine introspection vmi technique monitoring runtime state system-level virtual machine vm helpful debugging forensic analysis term introspection application virtual machines introduced garfinkel rosenblum invented approach protecting security application attack malicious software called vmi vmi common term different virtual machine forensics analysis methods vmi-based approaches widely used security applications software debugging systems management vmi tools may located inside outside virtual machine act tracking events interrupts memory writes sending requests virtual machine virtual machine monitor usually provides low-level information like raw bytes memory converting low-level view something meaningful user known semantic gap problem solving problem requires analysis understanding systems monitored programs running inside vm may provide information processes information may sent network interface virtual devices like serial port examples vivo introspection programs windbg gdb servers interact remote debugger drawback approach requires functioning os within vm os hangs n't loaded yet introspection agent could n't work vmi tools may implemented within virtual machine monitor separate programs capture information e.g. contents memory virtual machine monitor data interpreted understand processes system one popular tools interpretation volatility framework framework contains profiles many popular operating systems may extract different information like process tree list kernel objects
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Operating systems
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bootstrapping compilers computer science bootstrapping technique producing self-compiling compiler — compiler assembler written source programming language intends compile initial core version compiler bootstrap compiler generated different language could assembly language successive expanded versions compiler developed using minimal subset language many compilers many programming languages bootstrapped including compilers basic algol c c pascal pl/i factor haskell modula-2 oberon ocaml common lisp scheme go java rust python scala nim eiffel bootstrapping compiler following advantages note points assume language runtime also written language one needs compile compiler language x written language x issue first compiler compiled different methods used practice solving chicken egg problem include methods distributing compilers source code include providing portable bytecode version compiler bootstrap process compiling compiler t-diagram notation used explain compiler bootstrap techniques cases convenient way get complicated compiler running system little software involves series ever sophisticated assemblers compilers assemblers first language tools bootstrap first high-level language provide bootstrap neliac 1958 first widely used languages burroughs b5000 algol 1961 lisp 1962 hart levin wrote lisp compiler lisp mit 1962 testing inside existing lisp interpreter improved compiler point could compile source code self-hosting technique possible interpreter already exists language compiled borrows directly notion running program input also used various proofs theoretical computer science proof halting problem undecidable due security concerns regarding trusting trust attack various attacks binary trustworthiness multiple projects working reduce effort bootstrapping source also allowing everyone verify source executable correspond include bootstrappable builds project reproducible builds project following programming languages self-hosting compilers
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Programming language topics
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underground dreyfus book underground tales hacking madness obsession electronic frontier 1997 book suelette dreyfus researched julian assange describes exploits group australian american british black hat hackers late 1980s early 1990s among assange book also mentions hackers contacts protagonists among erik bloodaxe legion doom corrupt masters deception first chapter underground relates diffusion reactions computer security community wank worm attacked dec vms computers decnet 1989 purportedly coded melbourne hacker book sold 10,000 copies author made electronic edition book freely available 2001 announced slashdot server housing book crashed due demand book reached 400,000 downloads within two years 2002 documentary realm hackers directed kevin anderson centered phoenix electron inspired book
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Computer security
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open group open group industry consortium seeks enable achievement business objectives developing open vendor-neutral technology standards certifications 625 members provides number services including strategy management innovation research standards certification test development established 1996 x/open merged open software foundation open group certifying body unix trademark publishes single unix specification technical standard extends posix standards open group also develops manages togaf standard industry standard enterprise architecture framework 625 members include range vendors buyers well government agencies including example capgemini fujitsu oracle hpe orbus software ibm huawei philips u.s. department defense nasa obligation product developers vendors adopt standards developed association early 1990s major unix system vendors begun realize standards rivalries often called unix wars causing participants harm good leaving unix industry open emerging competition microsoft cose initiative 1993 considered first unification step merger open software foundation osf x/open 1996 ultimate step end skirmishes osf previously merged unix international 1994 meaning new entity effectively represented elements unix community time january 1997 responsibility x window system transferred open group defunct x consortium 1999 x.org formed manage x window system management services provided open group x.org members made number releases including x11r6.8 open group provided management services 2004 x.org open group worked together establish newly formed x.org foundation took control x.org domain name stewardship x window system see history x window system open group best-known services certification programs including certification products best practices posix north american state lotteries association naspl unix open group offers certifications professionals addition togaf certification covers tools services people certification open group also administers open group certified architect open ca program open group certified specialist open cits certification program latter skills experience based certification programs open group also offers certification archimate tools people well people certification open fair it4it open group provides platform members discuss requirements work jointly development adoption industry standards facilitate enterprise integration note open group documents available members especially development based area interest members join one semi-autonomous forums include members come together open group quarterly events member meetings open group also provides range services initial setup ongoing operational support collaboration standards best practices development assistance market impact activities assist organizations setting business objectives strategy procurement also provide certification test development includes services government agencies suppliers companies organizations set governments
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Operating systems
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windows nt windows nt family operating systems produced microsoft first version released july 27 1993 processor-independent multiprocessing multi-user operating system first version windows nt windows nt 3.1 produced workstations server computers intended complement consumer versions windows based ms-dos including windows 1.0 windows 3.1x gradually windows nt family expanded microsoft general-purpose operating system product line personal computers deprecating windows 9x family nt formerly expanded new technology longer carries specific meaning starting windows 2000 nt removed product name included product version string nt first purely 32-bit version windows whereas consumer-oriented counterparts windows 3.1x windows 9x 16-bit/32-bit hybrids multi-architecture operating system initially supported several instruction set architectures including ia-32 mips dec alpha support powerpc itanium x64 arm added later latest versions support x86 specifically ia-32 x64 arm major features windows nt family include windows shell windows api native api active directory group policy hardware abstraction layer ntfs bitlocker windows store windows update hyper-v suggested dave cutler intended initialism wnt play vms incrementing letter one however project originally intended follow-on os/2 referred nt os/2 receiving windows brand one original nt developers mark lucovsky states name taken original target processor—the intel i860 code-named n10 n-ten 1998 question-and-answer session bill gates revealed letters previously expanded new technology longer carry specific meaning letters dropped names releases windows 2000 later though microsoft described product built nt technology main design goal nt hardware software portability various versions nt family operating systems released variety processor architectures initially ia-32 mips dec alpha powerpc itanium x86-64 arm supported later releases idea common code base custom hardware abstraction layer hal platform however support mips alpha powerpc later dropped windows 2000 broad software compatibility achieved support several api personalities including windows api posix os/2 apis – latter two phased starting windows xp partial ms-dos compatibility achieved via integrated dos virtual machine – although feature phased x86-64 architecture nt supported per-object file function role access control lists allowing rich set security permissions applied systems services nt supported windows network protocols inheriting previous os/2 lan manager networking well tcp/ip networking microsoft would implement tcp/ip stack derived first streams-based stack spider systems later rewritten in-house windows nt 3.1 first version windows use 32-bit flat virtual memory addressing 32-bit processors companion product windows 3.1 used segmented addressing switches 16-bit 32-bit addressing pages windows nt 3.1 featured core kernel providing system api running supervisor mode ring 0 x86 referred windows nt kernel mode platforms set user-space environments apis included new win32 environment os/2 1.3 text-mode environment posix environment full preemptive multitasking kernel could interrupt running tasks schedule tasks without relying user programs voluntarily give control cpu windows 3.1 windows applications although ms-dos applications preemptively multitasked windows starting windows/386 notably windows nt 3.x several i/o driver subsystems video printing user-mode subsystems windows nt 4 video server printer spooler subsystems moved kernel mode windows nt first gui strongly influenced programmatically compatible windows 3.1 windows nt 4 interface redesigned match brand new windows 95 moving program manager windows shell design ntfs journaled secure file system created nt windows nt also allows installable file systems starting versions 3.1 nt could installed fat hpfs file systems windows nt introduced driver model windows nt driver model incompatible older driver frameworks windows 2000 windows nt driver model enhanced become windows driver model first introduced windows 98 based nt driver model windows vista added native support windows driver foundation also available windows xp windows server 2003 extent windows 2000 microsoft decided create portable operating system compatible os/2 posix supporting multiprocessing october 1988 development started november 1989 windows nt known os/2 3.0 third version operating system developed jointly microsoft ibm ensure portability initial development targeted intel i860xr risc processor switching mips r3000 late 1989 intel i386 1990 microsoft also continued parallel development dos-based less resource-demanding windows environment resulting release windows 3.0 may 1990 windows 3 eventually successful microsoft decided change primary application programming interface still unreleased nt os/2 known extended os/2 api extended windows api decision caused tension microsoft ibm collaboration ultimately fell apart ibm continued os/2 development alone microsoft continued work newly renamed windows nt though neither operating system would immediately popular microsoft ms-dos windows products windows nt would eventually far successful os/2 microsoft hired group developers digital equipment corporation led dave cutler build windows nt many elements design reflect earlier dec experience cutler vms rsx-11 also unreleased object-based operating system developed dave cutler dec prism team joined selected members disbanded os/2 team including moshe dunie operating system designed run multiple instruction set architectures multiple hardware platforms within architecture platform dependencies largely hidden rest system kernel mode module called hal hardware abstraction layer windows nt kernel mode code distinguishes kernel whose primary purpose implement processor- architecture-dependent functions executive designed modified microkernel windows nt kernel influenced mach microkernel developed carnegie mellon university meet criteria pure microkernel kernel executive linked together single loaded module ntoskrnl.exe outside module little distinction kernel executive routines directly accessible example kernel-mode device drivers api sets windows nt family implemented subsystems atop publicly undocumented native api allowed late adoption windows api win32 subsystem windows nt one earliest operating systems use unicode internally windows nt 3.1 3.51 incorporated program manager file manager windows 3.1x series windows nt 4.0 onwards replaced programs windows explorer including taskbar start menu originally appeared windows 95 first release given version number 3.1 match contemporary 16-bit windows magazines era claimed number also used make version seem reliable .0 release also novell ipx protocol apparently licensed 3.1 versions windows software nt version number generally used marketing purposes still used internally said reflect degree changes core operating system however application compatibility reasons microsoft kept major version number 6 releases following vista changed later 10 windows 10 build number internal identifier used microsoft developers beta testers windows nt written c c++ small amount written assembly language c mostly used kernel code c++ mostly used user-mode code assembly language avoided possible would impede portability order prevent intel x86-specific code slipping operating system developers used developing x86 chips windows nt 3.1 initially developed using non-x86 development systems ported x86 architecture work initially based intel i860-based dazzle system later mips r4000-based jazz platform systems designed internally microsoft windows nt 3.1 released intel x86 pc compatible pc-98 dec alpha arc-compliant mips platforms windows nt 3.51 added support powerpc processor 1995 specifically prep-compliant systems ibm power series desktops/laptops motorola powerstack series despite meetings michael spindler bill gates power macintosh prep compliant power macintosh project failed ship intergraph corporation ported windows nt clipper architecture later announced intention port windows nt 3.51 sun microsystems sparc architecture neither version sold public retail product two windows nt 4.0 variants ia-32 alpha full set service packs available ports done third parties motorola intergraph etc publicly available updates windows nt 4.0 last major release support alpha mips powerpc though development windows 2000 alpha continued august 1999 compaq stopped support windows nt architecture three days later microsoft also canceled alphant program even though alpha nt 5 windows 2000 release reached rc1 status microsoft announced january 5 2011 next major version windows nt family include support arm architecture microsoft demonstrated preliminary version windows version 6.2.7867 running arm-based computer 2011 consumer electronics show eventually led commercial release windows 8-derived windows rt october 26 2012 implementation nt ce windows phone 8 according microsoft common misconception xbox xbox 360 use modified windows 2000 kernel xbox operating system built scratch implements subset windows apis 64-bit versions windows nt originally intended run itanium dec alpha latter used internally microsoft early development 64-bit windows continued time microsoft publicly announced cancelling plans ship 64-bit windows alpha alpha versions windows nt 32-bit windows 2000 supports intel ia-32 32-bit windows xp server 2003 server 2008 server 2008 r2 one edition dedicated itanium-based systems comparison itanium microsoft adopted x64 greater scale every version windows since windows xp dedicated x64 edition x64 editions minimum hardware specification required run release professional workstation version windows nt fairly slow-moving 6.0 vista release requires minimum 15 gb free disk space 10-fold increase free disk space alone previous version
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Computer architecture
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arcaos arcaos operating system developed marketed arca noae llc derived os/2 based last release ibm development continues stated goal add wider compatibility modern computing platforms including uefi gpt support limited pae support ram excess 4 gb utilized ram disk utilizing smp kernel supports 64 physical cpus real cpu cores hyper-threading recommended arcaos 32-bit operating system runs x86 processor architecture real virtualized arcaos based ibm os/2 warp 4.52 also known merlin convenience pack 2 mcp2 arcaos 5.0.3 acpi 6.2a-compliant acpica 20180508 arcaos compatible x86-based personal computers including portables desktops servers availability traditional bios case uefi-based systems complete csm arcaos includes device drivers number network adapters either using arca noae multimac technology employs freebsd driver code older ibm third-party-supplied drivers selection genmac drivers support wireless networking somewhat limited though multimac support select chipsets planned arcaos supports usb 2.0 connectivity development usb 3.0 driver ongoing audio support utilizes uniaud generic audio driver maintained arca noae uniaud based alsa addition selection device-specific drivers included os distribution video support provided panorama generic unaccelerated vesa driver snap accelerated video driver acceleration supported limited number graphics chipsets features zooming multi-head also available limited number chipsets snap lacks support many modern chipsets though support additional chips planned storage drivers available ide ahci select number scsi adapters supported nvme driver yet available arcaos includes capable dos vdm ships modified version windows 3.11 winos2 capable running 16-bit windows applications also capable running 32-bit windows applications utilizing odin project based part wine addition ported native os/2 code linux applications quite common well qt applications ported linux qt applications included distribution may installed rpm packages several available yum repositories openjdk 6 included arcaos capable running wide range java applications heimdal kerberos authentication client included arcaos distribution based 1.5.3 heimdal code arcaos native file system jfs though hpfs also supported os may booted either filesystem fat12 fat16 fat32 also supported using either kernel fat driver ifs driver arcaos supports several file systems use additional ifs drivers cdfs udf netdrive os/2 provides access samba 4 shares via ifs driver arcaos distribution includes limited license version netdrive fully licensed version capable mounting number local native foreign file systems arcaos formally announced october 23 2015 warpstock 2015 event os/2 ecomstation user group event code name blue lion arca noae managing member lewis rosenthal planned features blue lion announced time warpstock 2015 conference initial release projected late third quarter 2016 arca noae also stated actual release date set pre-orders arcaos ever taken announced name arcaos first published tech republic article may 26 2016 arcaos.com domain registered december 20 2015 tech republic article lewis rosenthal quoted saying first release arcaos would version 5.0 follows onto last release os/2 warp ibm 4.52 also stated arcaos 5.1 provide french spanish italian german dutch versions operating system arcaos 5.0 code name blue lion released may 15 2017 two editions released commercial edition intended enterprise use including 12 months upgraded/prioritized technical support personal edition targeted non-business users including six months standard technical support reduced price pricing listed 229 per license commercial edition 129 per license personal edition 99 promotional price effect first 90 days following release 9 july 2017 arcaos 5.0.1 released contained fixes installer arca noae current drivers ahci driver updated along multimac fix virtualpc use ibm ’ smouse driver version 5.0.2 arcanoae added usb booting support allowing os/2 boot usb media addition optical media version 5.0.2 released february 10 2018 19 august 2018 version 5.0.3 released included several updates bundled drivers programs 21 july 2019 version 5.0.4 released introduced new updater feature allowing arcaos installations upgraded latest release without reinstalling operating system
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Computer architecture
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keystroke logging keystroke logging often referred keylogging keyboard capturing action recording logging keys struck keyboard typically covertly person using keyboard unaware actions monitored data retrieved person operating logging program keylogger either software hardware programs legal many designed allow employers oversee use computers keyloggers often used purpose stealing passwords confidential information keylogging also used study human–computer interaction numerous keylogging methods exist range hardware software-based approaches acoustic analysis software-based keyloggers computer programs designed work target computer software keyloggers used organizations troubleshoot technical problems computers business networks families business people use keyloggers legally monitor network usage without users direct knowledge even microsoft publicly admitted windows 10 operation system built-in keylogger final version “ improve typing writing services ” however malicious individuals use keyloggers public computers steal passwords credit card information keyloggers stopped https encryption protects data transit computers thus threat user computer technical perspective several categories keystroke logging established research method study writing processes different programs developed collect online process data writing activities including inputlog scriptlog translog keystroke logging legitimately used suitable research instrument number writing contexts include studies cognitive writing processes include keystroke logging used research writing specifically also integrated educational domains second language learning programming skills typing skills software keyloggers may augmented features capture user information without relying keyboard key presses sole input features include hardware-based keyloggers depend upon software installed exist hardware level computer system mid 1970s soviet union developed deployed hardware keylogger targeting typewriters termed selectric bug measured movements print head ibm selectric typewriters via subtle influences regional magnetic field caused rotation movements print head early keylogger written perry kivolowitz posted usenet news group net.unix-wizards net.sources november 17 1983 posting seems motivating factor restricting access /dev/kmem unix systems user-mode program operated locating dumping character lists clists assembled unix kernel 1970s spies installed keystroke loggers us embassy consulate buildings moscow installed bugs selectric ii selectric iii electric typewriters soviet embassies used manual typewriters rather electric typewriters classified information—apparently immune bugs 2013 russian special services still use typewriters writing simple software applications keylogging trivial like nefarious computer program distributed trojan horse part virus trivial attacker however installing covert keystroke logger without getting caught downloading data logged without traced attacker manually connects host machine download logged keystrokes risks traced trojan sends keylogged data fixed e-mail address ip address risks exposing attacker researchers devised several methods solving problem presented deniable password snatching attack keystroke logging trojan installed using virus worm 2000 fbi used flashcrest ispy obtain pgp passphrase nicodemo scarfo jr. son mob boss nicodemo scarfo also 2000 fbi lured two suspected russian cyber criminals us elaborate ruse captured usernames passwords keylogger covertly installed machine used access computers russia fbi used credentials hack suspects computers russia order obtain evidence prosecute effectiveness countermeasures varies keyloggers use variety techniques capture data countermeasure needs effective particular data capture technique case windows 10 keylogging microsoft enough change privacy settings computer example on-screen keyboard effective hardware keyloggers transparency defeat some—but all—screenloggers anti-spyware application disable hook-based keyloggers ineffective kernel-based keyloggers also keylogger program authors may able update code adapt countermeasures may proven effective anti-keylogger piece software specifically designed detect keyloggers computer typically comparing files computer database keyloggers looking similarities might signal presence hidden keylogger anti-keyloggers designed specifically detect keyloggers potential effective conventional antivirus software antivirus software consider keylogger virus circumstances keylogger considered legitimate piece software rebooting computer using live cd write-protected live usb possible countermeasure software keyloggers cd clean malware operating system contained secured fully patched infected soon started booting different operating system impact use hardware bios based keylogger many anti-spyware applications able detect software based keyloggers quarantine disable cleanse however many keylogging programs legitimate pieces software circumstances anti spyware often neglects label keylogging programs spyware virus applications able detect software-based keyloggers based patterns executable code heuristics keylogger behaviours use hooks certain apis software-based anti-spyware application 100 effective keyloggers also software-based anti-spyware defeat non-software keyloggers example hardware keyloggers attached keyboards always receive keystrokes software-based anti-spyware application however particular technique anti-spyware application uses influence potential effectiveness software keyloggers general rule anti-spyware applications higher privileges defeat keyloggers lower privileges example hook-based anti-spyware application defeat kernel-based keylogger keylogger receive keystroke messages anti-spyware application could potentially defeat hook- api-based keyloggers network monitors also known reverse-firewalls used alert user whenever application attempts make network connection gives user chance prevent keylogger phoning home typed information automatic form-filling programs may prevent keylogging removing requirement user type personal details passwords using keyboard form fillers primarily designed web browsers fill checkout pages log users accounts user account credit card information entered program automatically entered forms without ever using keyboard clipboard thereby reducing possibility private data recorded however someone physical access machine may still able install software able intercept information elsewhere operating system transit network transport layer security tls reduces risk data transit may intercepted network sniffers proxy tools using one-time passwords may keylogger-safe password invalidated soon used solution may useful someone using public computer however attacker remote control computer simply wait victim enter his/her credentials performing unauthorised transactions behalf session active use smart cards security tokens may improve security replay attacks face successful keylogging attack accessing protected information would require hardware security token well appropriate password/passphrase knowing keystrokes mouse actions display clipboard etc used one computer subsequently help attacker gain access protected resource security tokens work type hardware-assisted one-time password system others implement cryptographic challenge-response authentication improve security manner conceptually similar one time passwords smartcard readers associated keypads pin entry may vulnerable keystroke logging so-called supply chain attack attacker substitutes card reader/pin entry hardware one records user pin on-screen keyboards on-screen keyboard comes windows xp send normal keyboard event messages external target program type text software key loggers log typed characters sent one program another additionally keylogging software take screenshots displayed screen periodically and/or upon mouse click means although certainly useful security measure on-screen keyboard protect keyloggers keystroke interference software also available programs attempt trick keyloggers introducing random keystrokes although simply results keylogger recording information needs attacker task extracting keystrokes interest—the security mechanism specifically well stands cryptanalysis unclear similar on-screen keyboards speech-to-text conversion software also used keyloggers since typing mouse movements involved weakest point using voice-recognition software may software sends recognized text target software recognition took place also many pdas lately tablet pcs already convert pen also called stylus movements touchscreens computer understandable text successfully mouse gestures use principle using mouse movements instead stylus mouse gesture programs convert strokes user-definable actions typing text similarly graphics tablets light pens used input gestures however less common everyday potential weakness speech recognition applies technique well help many programs seemingly meaningless text expanded meaningful text time context-sensitively e.g en.wikipedia.org expanded web browser window focus biggest weakness technique programs send keystrokes directly target program however overcome using 'alternating technique described i.e sending mouse clicks non-responsive areas target program sending meaningless keys sending another mouse click target area e.g password field switching back-and-forth alternating typing login credentials typing characters somewhere else focus window cause keylogger record information need although could easily filtered attacker similarly user move cursor using mouse typing causing logged keystrokes wrong order e.g. typing password beginning last letter using mouse move cursor subsequent letter lastly someone also use context menus remove cut copy paste parts typed text without using keyboard attacker able capture parts password larger key space attack chose execute brute-force attack another similar technique uses fact selected text portion replaced next key typed e.g. password secret one could type dummy keys asdfsd dummies could selected mouse next character password e typed replaces dummies asdfsd techniques assume incorrectly keystroke logging software directly monitor clipboard selected text form take screenshot every time keystroke mouse click occurs may however effective hardware keyloggers
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Computer security
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federated database system federated database system type meta-database management system dbms transparently maps multiple autonomous database systems single federated database constituent databases interconnected via computer network may geographically decentralized since constituent database systems remain autonomous federated database system contrastable alternative sometimes daunting task merging several disparate databases federated database virtual database composite constituent databases federated database system actual data integration constituent disparate databases result data federation data abstraction federated database systems provide uniform user interface enabling users clients store retrieve data multiple noncontiguous databases single query—even constituent databases heterogeneous end federated database system must able decompose query subqueries submission relevant constituent dbmss system must composite result sets subqueries various database management systems employ different query languages federated database systems apply wrappers subqueries translate appropriate query languages mcleod heimbigner among first define federated database system mid 1980s fdbs one define architecture interconnect databases minimize central authority yet support partial sharing coordination among database systems description might accurately reflect mcleod/heimbigner definition federated database rather description fits mcleod/heimbigner called composite database mcleod/heimbigner federated database collection autonomous components make data available members federation publication export schema access operations unified central schema encompasses information available members federation among surveys practitioners define federated database collection cooperating component systems autonomous possibly heterogeneous three important components fdbs autonomy heterogeneity distribution another dimension also considered networking environment computer network e.g. many dbss lan many dbss wan update related functions participating dbss e.g. updates nonatomic transitions atomic updates dbms classified either centralized distributed centralized system manages single database distributed manages multiple databases component dbs dbms may centralized distributed multiple dbs mdbs classified two types depending autonomy component dbs federated non federated nonfederated database system integration component dbms autonomous federated database system consists component dbs autonomous yet participate federation allow partial controlled sharing data federated architectures differ based levels integration component database systems extent services offered federation fdbs categorized loosely tightly coupled systems multiple dbs fdbs specific type characterized along three dimensions distribution heterogeneity autonomy another characterization could based dimension networking example single databases multiple databases lan wan distribution data fdbs due existence multiple dbs fdbs built data distributed among multiple databases could stored single computer multiple computers computers could geographically located different places interconnected network benefits data distribution help increased availability reliability well improved access times heterogeneities databases arise due factors differences structures semantics data constraints supported query language differences structure occur two data models provide different primitives object oriented oo models support specialization inheritance relational models differences due constraints occur two models support two different constraints example set type codasyl schema may partially modeled referential integrity constraint relationship schema codasyl supports insertion retention captured referential integrity alone query language supported one dbms also contribute heterogeneity component dbmss example differences query languages data models different versions query languages could contribute heterogeneity semantic heterogeneities arise disagreement meaning interpretation intended use data schema data level classification possible heterogeneities include creating federated schema one resolve heterogeneities integrating component db schemas dealing incompatible data types query syntax obstacle concrete implementation fdbs systems planned top-down generic problem lies matching semantically equivalent differently named parts different schemas =data models tables attributes pairwise mapping n attributes would result formula_1 mapping rules given equivalence mappings number quickly gets large practical purposes common way provide global schema comprises relevant parts member schemas provide mappings form database views two principal approaches depend direction mapping examples data integration called schema matching problem fundamental difference mdbs fdbs concept autonomy important understand aspects autonomy component databases addressed component dbs participates fdbs four kinds autonomies addressed heterogeneities fdbs primarily due design autonomy ansi/x3/sparc study group outlined three level data description architecture components conceptual schema internal schema external schema databases three level architecture however inadequate describing architectures fdbs therefore extended support three dimensions fdbs namely distribution autonomy heterogeneity five level schema architecture explained heterogeneity autonomy requirements pose special challenges concerning concurrency control fdbs crucial correct execution concurrent transactions see also global concurrency control achieving global serializability major correctness criterion requirements characterized difficult unsolved commitment ordering introduced 1991 provided general solution issue see global serializability see commitment ordering also architectural aspects solution five level schema architecture includes following accurately representing state art data integration five level schema architecture suffer major drawback namely imposed look feel modern data users demand control data presented needs somewhat conflict bottom-up approaches data integration
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Databases
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hidemyass hidemyass hma virtual private network vpn provider founded 2005 united kingdom subsidiary czech cybersecurity company avast since 2016 hidemyass created 2005 norfolk england jack cator time cator sixteen years-old created hma order circumvent restrictions school accessing games music network according cator first hidemyass service created hours using open-source code first product free website users typed url delivered website user browser cator promoted tool online forums featured front page digg attracting one thousand users cator incorporated ads hma take venture capital funding generated 1,000 2,000 per month founder went college pursue degree computer science 2009 cator dropped college focus hma added paid vpn service early hma employees freelancers found odesk.com 2012 one freelancers set-up competing business hma responded hiring contractors full-time employees establishing physical offices london 2012 united kingdom government sent hidemyass court order demanding provide information cody andrew kretsinger use hma service hack sony member lulzsec hacking group hma provided information authorities hma said violation company terms use use software illegal activities 2013 hma added software anonymize internet traffic mobile devices first added 2013 2014 company introduced hidemyphone service allowed mobile phone users make calls appear come different location 2014 service 10 million users 215,000 paying subscribers vpn service made £11 million revenue year hma 100 staff established international offices belgrade kiev 2015 hma became one largest vpn providers may 2015 acquired avg technologies 40 million became part avast 2016 acquisition avg technologies 2017 security vulnerability discovered allowed hackers access user laptop obtain elevated privileges device 2019 reported hma received directive russian authorities join state sponsored registry banned websites would prevent russian hma users circumventing russian state censorship hma reportedly given one month comply face blocking russian authorities hidemyass provides digital software services intended help users remain anonymous online encrypt online traffic software used access websites may blocked user country anonymize information could otherwise used hackers something unscrupulous without identified hma privacy policy terms use prohibit using illegal activity hma hides user ip address identifying information routing user internet traffic remote server however experts note company log connection data including originating ip address duration vpn session amount bandwidth used may 2018 company 830 servers 280 locations across globe provided 3000 ip addresses 2015 review tom hardware said hidemyass easy use good customer service large number server locations choose criticized slowing internet speeds contrast digital trends said hidemyass strong speeds good server selection n't full-proof ensuring anonymity stored user activity logs 2017 pc world noted difficult measure effect vpn service internet speed variables like location internet service speeds hardware 2016 review pc magazine gave hma android app 3 5 stars praised hma server selection user interface criticized price speed lack advanced features 2018 pc magazine gave similar feedback hma vpn service pc world ’ 2017 review also praised hma simple user interface criticized lack advanced features saying software ideal casual users need advanced configuration options
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Computer security
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jslee jslee jain service logic execution environment java programming language api developing deploying network services standardized java specification requests jsr 22 jsr 240 sun microsystems opencloud metaswitch participation 80 operators software vendors technical specification designed implementations meet stringent requirements communications applications like high throughput low latency scalability availability software portability furthermore allows software developers write robust components integrates acid properties transactions programming model jslee environment acts integration point multiple network resources communications protocols
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Programming language topics
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palm iiixe palm iiixe discontinued palm personal digital assistant designed manufactured palm inc cost us 249 new manufacturer part number 3c80304u note requirements palm desktop pim software originally shipped palm iii xe os required apple mac os 7.5.3 later microsoft windows 95 microsoft windows 98 microsoft windows nt 4.0 later palm iiixe introduced marketplace february 2000 one two remaining models palm iiic iii series line palm personal digital assistants palm iiixe unit came black flip lid infrared port top lets users beam memos addresses etc another palm handheld personal computer right software iiixe also used universal remote control bottom unit serial port hotsyncing user desktop computer way cradle serial port also support various peripherals including palmpix camera stowaway foldable gotype keyboards like palms series bottom portion screen features silkscreen used graffiti input system provide shortcuts calculator application list application menu search unit comes seven physical buttons power/backlight date book address book scroll buttons list memo pad buttons except scroll buttons used turn unit iiixe features 16 mhz motorola 68328 ez dragonball cpu powered two aaa batteries last month two depending use also features enhanced 160x160 pixel grayscale super-twisted nematic display area palm iiie palm iiix 4-bit display 16 greyscales 8 mb ram 2 mb internal flash memory system upgrades third party applications unit shipped palm os 3.5 patched later versions palm os 3.5.2 fixed memory leak version 3.5 palm os palm os 3.5.3 fixed flow control problem dynamic ui pointer issue caused incompatibilities 3rd party applications latest version palm os runs iiixe version 4.1 released november 2001 unlike free version 3.5 updates palm os 4.1 available paid upgrade cd-rom peculiar note palm iii series top battery inserts backwards positive terminal battery contacts battery compartment spring however bottom battery inserts usual way negative terminal battery touching spring battery compartment nimh batteries used extend runtime reduce waste alkaline batteries palm iiic iiixe vx units manufactured october 1999 may 2000 dram defect could overwrite user data randomly palm released diagnostics patch correct problem
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Computer architecture
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microwork microwork series small tasks together comprise large unified project completed many people internet microwork considered smallest unit work virtual assembly line often used describe tasks efficient algorithm devised require human intelligence complete reliably term developed 2008 leila chirayath janah samasource microtasking process splitting large job small tasks distributed internet many people since inception microwork many online services developed specialize different types microtasking rely large voluntary workforce composed internet users around world typical tasks offered repetitive simple automated good candidates microtasks following characteristics may also known ubiquitous human computing human-based computation focused computational tasks complex distributed computing microtasks distinguished macrotasks typically done independently require fixed amount time require specialized skill wage paid range cents per task hundreds dollars per project amazon mechanical turk allows workers choose perform simple tasks online reporting directly platform receive payments exchange task complex algorithm writing simple labelling photos videos describing products transcribing scanned documents employers submit tasks set payments often pennies task crowdsourcing project initiated amazon way users find duplicate webpages soon became service individuals contract computer programmers individuals finish tasks computers unable accomplish since project expanded original form nowadays people complete various mechanical turk projects extra income side liveops uses distributed network people run cloud call center virtual call center contact center contracted workers answer calls provide call center facilities without need physical building equipment traditional call center red cross utilized system successfully hurricane katrina 2005 process 17,000+ calls without open hire staff call center similar model used text message question-answering services like 63336 researchers connect service home receive questions submitted innocentive allows businesses post problems offer payment answers questions often far less simple tasks posted services like mechanical turk payments accordingly higher example think find way prevent orange juice stored see-through bottles turning brown may 20,000 samasource non-profit organization allows people living poverty opportunity complete microwork living wage service specializes online content moderation digital transcription data gathering promotion galaxy zoo scientific effort use online crowdsourcing classify large number galaxies astronomical images 2010 company internet eyes launched service return potential reward home viewers would watch live cctv streams alert shop owners potential theft progress uses microtasking services involve processing data especially online include driving traffic websites gathering data like email addresses labelling tagging data online also used accurately translate transcribe audio clips pictures since activities better suited humans computers used practical data conversion purposes also improve upon test fidelity machine learning algorithms identification pictures humans used help missing persons searches though little effect manipulation data services also good platform reaching large population social studies surveys since make easy offer monetary incentives companies also outsource projects specialists otherwise would expended resources hiring screening method pay per task attractive employers therefore companies like microsoft yahoo currently crowdsourcing work crowdflower company specializes allocating jobs foreign local crowd workers crowdflower alone completed 450 million completed human intelligence tasks 2007 2012 crowdflower operates differently amazon mechanical turk jobs taken company turn allocated right workers range channels implemented system called virtual play allows users play free games would turn accomplish useful tasks company 2011 estimated 375 million contributed digital crowdsourced labour india united states together make roughly 92 workers amazon mechanical turk u.s. making 56 however percentage indian turkers quadrupled one year 2008 2009 2009 indian turkers much younger educated american counterparts citation needed average age indian workers 26 american workers 35 addition 45 digital workforce india bachelor degrees 21 master degrees contrast 38 american turkers bachelor degree 17 master degree nonetheless majority digital workforce educated young adults major difference american indian workforce lies gender 63 indian turkers male compared 37 makes american turkers microtasking services implemented allow workers work home workers complete tasks voluntary basis time-sensitive jobs like call centers choose jobs complete complete workers work anywhere world receive payment directly internet workers reside anywhere world microwork provide job opportunities large fortune 500 companies many smaller companies people living poverty would otherwise able make living wage services like samasource work wealth distributed companies developed countries large volume families poverty especially women youth would otherwise able generate income services like amazon mechanical turk restrict countries workers connect employers microtasking services provide platform quickly get project online start receiving results many workers time services offer large workforces complete tasks concurrently large volumes small tasks completed quickly furthermore since task discretely contained tasks usually simple nature individual worker fully trained complete knowledge project contribute work united states tax law workers treated independent contractors means employers withhold taxes need file form 1099-misc internal revenue service given worker earns 600 per year workers responsible paying income taxes including self-employment tax would otherwise paid employer microtasking services criticized providing healthcare retirement benefits sick pay minimum wage pay piece treat workers independent contractors rather employees also avoid laws child labor labor rights additionally workers may little idea work used result may workers end contributing project negative impact morally opposed services especially amazon mechanical turk services pay pennies task called digital sweatshops analogy sweatshops manufacturing industry exploit workers maintain poor conditions wages vary considerably depending speed worker per-piece price offered workers choose tasks complete based task price experience employer employers bid higher faster completion higher-quality workers average unskilled turkers earn less 2.00 hour minimum wage united states however india well minimum cities india 1200 minimum wages global services outsource work underdeveloped developing regions competitive pricing task completion could result lower wages possibility also exists true brick mortar sweatshops exploit microtasking services enlisting poor afford computer aggregating work wages also possibility requesters may tell worker reject work cheat worker using anyway avoid paying however dispersed geography microwork used keep wages low networks fragment labour process also used workers organising resistance san francisco-based company crowdflower facilitated outsourcing digital tasks countries poverty stimulate local economies crowdsourcing company partnership samasource non-profit organization brings computer based work developing countries currently outsourced millions repetitive microwork kenyan refugee camps workers make 2 hour locals average refugees asked exploitation lukas biewald crowdflower argues digital sweatshop much better job people developing world opposed working manufacturing sweatshop states treatment received workers far superior categorized sweatshop great thing digital work really hard make sweatshop digital work really hard force someone work ca n't beat someone computer screen
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Web technology
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terminfo terminfo library database enables programs use display terminals device-independent manner mark horton implemented first terminfo library 1981–1982 improvement termcap improvements include terminfo included unix system v release 2 soon became preferred form terminal descriptions system v rather termcap bsd continued use imitated pcurses 1982–1984 pavel curtis available unix implementations adapting incorporating fixes mark horton information refer posting comp.sources.unix newsgroup december 1986 terminfo database describe capabilities hundreds different display terminals allows external programs able character-based display output independent type terminal configurations terminfo databases consist one descriptions terminals description must contain canonical name terminal may also contain one aliases name terminal canonical name aliases keys library searches terminfo database description contains one capabilities conventional names capabilities typed boolean numeric string terminfo library predetermined types capability name checks types capability syntax applications use terminfo know types respective capabilities obtain values capabilities terminfo database using library calls return successfully capability name corresponds one predefined typed capabilities like termcap string capabilities represent escape sequences may sent host pressing special keys keyboard capabilities represent strings may sent application terminal latter case terminfo library functions termcap library substituting application parameters string sent functions provide stack-based expression parser primarily used help minimize number characters sent control sequences optional parameters sgr select graphic rendition contrast termcap libraries provide limited set operations useful terminals terminfo descriptions constructed including contents one description another suppressing capabilities included description overriding adding capabilities matter storage model used terminfo library returns terminal description requested description using data compiled using standalone tool e.g. tic terminfo data stored binary file making less simple modify termcap data retrieved terminfo library files stored data organized tables boolean numeric string capabilities respectively scheme devised mark horton except differences regarding available names used terminfo implementations x/open specify format compiled terminal description fact even mention common tic infocmp utilities compiled terminfo entries contain metadata identifying indices within tables capability assigned necessarily compatible implementations however since implementations use overall table structure including sizes header data items possible automatically construct customized terminfo libraries read data given implementation example ncurses built match terminfo data several implementations original common implementation terminfo library retrieves data directory hierarchy using first character name terminal description one component pathname name terminal description name file retrieve terminfo library usually outperforms searching large termcap file implementations terminfo store terminal description hashed database e.g. something like berkeley db version 1.85 store two types records aliases point canonical entry canonical entry contains data terminal capabilities open group documents limits terminfo minimum guaranteed values apply source file two special interest 14-character limit addresses old filesystems could represent filenames longer filesystems generally obsolete limits documented late 1980s unreviewed since 32,767 limit positive values signed two complement 16-bit value terminfo entry may use negative numbers represent cancelled absent values unlike termcap terminfo source compiled representation limits compiled representation unspecified however implementations note documentation tic terminal information compiler compiled entries exceed 4,096 bytes size
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Databases
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microsoft diagnostics msd microsoft diagnostics software tool developed microsoft assist diagnostics 1990s-era computers users primarily deployed tool provide detailed technical information user software hardware print gathered information usually use support technicians troubleshooting resolving problems assumptions made program valid late 1990s handle plug-and-play usb new technologies appeared around 2000 pc dos 6.1 codice_1 provides similar functionality commercial alternatives include manifest codice_2 quarterdeck qemm codice_3 first shipped microsoft word windows later included windows 3 ms-dos 6 windows 9x cd-roms os/2 windows nt contain code forked dos dos 5 level versions codice_3 included correspond era i.e version 2.0 windows nt 3 4 codice_5 program similar features however dos/windows specific functions replaced similar windows nt concerns codice_6 included resource kits provides print functionality codice_3 codice_5 since nt 5 windows 2000 codice_9 loader codice_10 users generally started program dos command prompt using command codice_11 starting program dos window either windows os/2 shows dos details allocated dos session machine general aspects system codice_3 provided technical information microsoft replaced codice_3 codice_10 similar features targets recent machines first appeared ms-word later distributed plus windows 95 windows 98. codice_10 windows xp stores system history wmi xml files codice_16 interest backward compatibility codice_5 became loader codice_18
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Computer architecture
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jelastic jelastic cloud services provider combines paas platform service caas container service single package hosting providers telecommunication companies enterprises developers platform available public cloud 60 data centers worldwide private cloud virtual premise hybrid multicloud jelastic provides support java php ruby node.js python .net go environments custom docker containers jelastic founded 2011 public cloud initially paas specifically targeted java hosting 2012 company got java duke choice award 2013-2015 platform added support php ruby python node.js .net support docker containers latest runtime addition 2017 integrating golang 2014 introduced private cloud solution 2015 platform could already used hybrid multi-cloud jelastic closed set funding rounds runa capital almaz capital partners foresight ventures maxfield capital june 2013 jelastic announced hiring mark zbikowski former microsoft architect contributor ms-dos senior adviser july 2013 rasmus lerdorf creator php joined jelastic senior adviser november 2014 creator java programming language james gosling brazilian java man bruno souza joined jelastic team jelastic keeps working improvement java technology user experience thereby 2018 platform proved leading position direction getting duke choice award second time platform installed bare metal iaas public cloud vpc private on-premise hybrid multi-cloud jelastic paas installed fully configured jelastic ops team performed automatically top google cloud ms azure well top bare metal using iso image platform configuration includes integration billing systems like whmcs odin system automation cleverbridge custom billing required jelastic provides pay-as-you-use pricing model within public cloud resources charged hourly base ram cpu cloudlet resource unit disk space external traffic public ip ssl price resource unit depends chosen hosting provider estimated monthly daily hourly base within dev panel cloud hosting expenses tracked optimized using built-in billing details whole account specific application private cloud installation charged monthly license base per physical server two types licensing installation self-administering installation managed services partnership service providers built franchise model revenue sharing jelastic installed wide range hosting providers telcos among datacenter finland telecom italia eapps locaweb primetel layershift elastx innofield others also jelastic used system integrators companies different spheres finance software sport gaming etc like fa solutions international football association board gmv g5 games miele philips lighting others
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Distributed computing architecture
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richard h. lathwell richard dick henry lathwell 1973 recipient larry breed roger moore grace murray hopper award association computing machinery
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Programming language topics
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ntfs junction point ntfs junction point symbolic link directory acts alias directory feature ntfs file system offers benefits windows shell shortcut .lnk file allowing access files within directory via windows explorer command prompt etc unlike ntfs symbolic links junction points link absolute path local volume junction points local volume remote share unsupported junction points type ntfs reparse point internally represented mount point introduced ntfs 3.0 default file system windows 2000 windows 2000 windows 2003 resource kits include program called create junction points mark russinovich winternals released tool called junction provided complete functionality windows xp includes fsutil masatoshi kimura released filter driver soft/symbolic link functionality existing windows xp ntfs version accessible end user windows vista windows server 2008 later operating systems include mklink command-line utility creating junction points setting junction point points directory containing particular version piece software may possible add another version software redirect junction point point version desired contents junction use almost disk space simply point original directory need multiple points entry large directory junction points serve purpose well junction points confused copy something junctions simply point original directories need modified separately junction used provide distinct copy directory files within since reinstalling windows installing new version often requires deleting contents c drive advantageous create multiple partitions one partition needs deleted installation however programs n't let user choose installation directory install files c drive even installed different drive creating junction point program tricked installing different directory list junctions present current directory obtained elevated command prompt admin executing codice_1 list junctions present disk volume executing codice_2 c volume scan junction point created vista later delete vista later use junction point created xp installing server 2003 resource kit delete xp use neither windows nt startup process windows vista startup process support junction points impossible redirect certain system folders however possible redirect non-critical folders creating junctions \users \programdata pointing another drive recommended breaks updates windows store apps creating junctions \users \programdata \program files \program files x86 pointing locations breaks installation resp upgrade windows creating junctions \program files \program files x86 pointing another drive breaks windows component based servicing hardlinks files repository \windows\sxs installation directory
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Computer file systems
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frame check sequence frame check sequence fcs refers error-detecting code added frame communications protocol frames used send payload data source destination frames bits bytes fields contained within susceptible errors variety sources fcs field contains number calculated source node based data frame number added end frame sent destination node receives frame fcs number recalculated compared fcs number included frame two numbers different error assumed frame discarded fcs provides error detection error recovery must performed separate means ethernet example specifies damaged frame discarded specify action cause frame retransmitted protocols notably transmission control protocol tcp notice data loss initiate retransmission error recovery fcs often transmitted way receiver compute running sum entire frame together trailing fcs expecting see fixed result zero correct ethernet ieee 802 protocols fixed result also known magic number crc32 residue 0xc704dd7b transmitted used way fcs generally appears immediately frame-ending delimiter far popular fcs algorithm cyclic redundancy check crc used ethernet ieee 802 protocols 32 bits x.25 16 32 bits hdlc 16 32 bits frame relay 16 bits point-to-point protocol ppp 16 32 bits data link layer protocols protocols internet protocol suite tend use checksums
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Internet protocols
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string interpolation computer programming string interpolation variable interpolation variable substitution variable expansion process evaluating string literal containing one placeholders yielding result placeholders replaced corresponding values form simple template processing formal terms form quasi-quotation logic substitution interpretation string interpolation allows easier intuitive string formatting content-specification compared string concatenation string interpolation common many programming languages make heavy use string representations data apache groovy kotlin perl php python ruby scala swift tcl unix shells two modes literal expression usually offered one interpolation enabled without termed raw string placeholders usually represented bare named sigil typically codice_1 codice_2 e.g codice_3 codice_4 expansion string usually occurs run time languages offer string interpolation instead offering standard function one parameter printf format string provide values placeholder ruby uses codice_5 symbol interpolation allows interpolating expression variables languages may support advanced interpolation special formatting function codice_6 first argument format specifies pattern remaining arguments substituted two main types expand variable algorithms variable interpolation string interpolation like string concatenation may lead security problems user input data improperly escaped filtered system exposed sql injection script injection xml external entity injection xxe cross-site scripting xss attacks sql injection example codice_7 replaced codice_8 executing query wipe data table following perl code works identically php produces output codice_9 output output output coldfusion markup language cfml script syntax tag syntax output output output groovy interpolated strings known gstrings output output java support direct string interpolation versions 5 static method codice_10 used interpolation javascript ecmascript 2015 es6 standard supports string interpolation using backticks codice_11 feature called template literals example output output also supports advanced formatting features output output output output output output rust provides string interpolation via std :fmt module interfaced various macros format write print macros converted rust source code compile-time whereby argument interacts formatter formatter supports positional parameters named parameters argument types defining various formatting traits let apples bananas 4 3 println apples bananas apples bananas output scala 2.10+ implemented following string interpolators f raw also possible write custom ones override standard ones f interpolator compiler macro rewrites format string embedded expressions invocation string.format verifies format string well-formed well-typed scala 2.10+ string interpolation allows embedding variable references directly processed string literals example output sciter function name starting considered interpolating function interpolation customizable context sensitive gets compiled swift new string value created mix constants variables literals expressions including values inside string literal item inserted string literal wrapped pair parentheses prefixed backslash output tool command language always supported string interpolation quote-delimited strings output order actually format simply replace values formatting function version 1.4 typescript supports string interpolation using backticks codice_11 example output codice_13 function used codice_6 function example rewritten thusly output remains visual basic 14 string interpolation supported visual basic print hello tom
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Programming language topics
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cb unix columbus unix cb unix discontinued variant unix operating system used internally bell labs administrative databases transaction processing developed columbus ohio branch based v6 v7 pwb unix little-known outside company cb unix developed address deficiencies inherent research unix notably lack interprocess communication ipc file locking considered essential database management system several bell system operation support system products based cb unix switching control center system primary innovations power-fail restart line disciplines terminal types ipc features interprocess communication features developed cb unix message queues semaphores shared memory support eventually appeared mainstream unix systems starting system v 1983 collectively known system v ipc
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Operating systems
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openmosix openmosix free cluster management system provided single-system image ssi capabilities e.g automatic work distribution among nodes allowed program processes threads migrate machines node network would able run process faster process migration particularly useful running parallel applications low moderate input/output i/o released linux kernel patch also available specialized live cds openmosix development halted developers linuxpmi project continuing development former openmosix code openmosix originally forked mosix moshe bar february 10 2002 mosix became proprietary software openmosix considered stable linux kernel 2.4.x x86 architecture porting linux 2.6 kernel remained alpha stage support 64-bit amd64 architecture started 2.6 version july 15 2007 bar announced openmosix project would reach end life march 1 2008 due decreasing need ssi clustering low-cost multi-core processors increase availability openmosix used distributed gentoo linux kernel choice removed gentoo linux portage tree february 2007 march 1 2008 openmosix read-only source code still hosted sourceforge linuxpmi project continuing development former openmosix code clusterknoppix specialized linux distribution based knoppix distribution uses openmosix kernel traditionally clustered computing could achieved setting individual rsh keys creating nfs shares editing host files setting static ips applying kernel patches manually clusterknoppix effectively renders work unnecessary distribution contains autoconfiguration system new clusterknoppix-running computers attached network automatically join cluster clusterknoppix modified knoppix distro using openmosix kernel linux live cds openmosix include
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Distributed computing architecture
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mike mcmahon computer scientist mike mcmahon programmer mit computer science artificial intelligence laboratory 1970s worked richard stallman emacs also wrote eine first implementation emacs lisp machines daniel weinreb eine stands eine emacs eine later became zwei meaning zwei eine initially one founders symbolics inc. company developing selling lisp machines 1980s 1990s mike mcmahon co-developed new error system symbolics main inspiration common lisp condition system mike mcmahon designed implemented new window system mit lisp machine 1980 together howard cannon window system implemented using flavors object-oriented extension lisp machine lisp
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Programming language topics
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oracle iplanet web server oracle iplanet web server oiws web server designed medium large business applications oracle iplanet web server builds earlier sun java system web server sun one web server iplanet web server netscape enterprise server products oracle iplanet web server available solaris windows hp-ux aix gnu/linux supports jsp java servlet technologies php nsapi cgi coldfusion netscape enterprise server web server developed originally netscape communications corporation 1996 based 1994 release netsite product renamed sun java system web server reflecting product acquisition sun microsystems oracle acquired sun 2010 oracle iplanet web server january 2009 sun open sourced core components sun java system web server 7.0 bsd license open web server open source version kept sync commercial releases january 2010 7.0 update 8 since oracle acquisition sun open source releases 2010 oracle renamed product sun java system web server oracle iplanet web server although documentation links still process updated reflect
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Web technology
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distributed codec engine distributed codec engine dce api implementation software library libdce texas instruments library released revised bsd license additional terms enables provides remote access hardware acceleration audio video decoding iva-hd omap4-based platforms via syslink/rcm shim layer accessing omap codec engine api codec interface co-processor ducati/m3 host linux without needing openmax ducati sub system comprises two arm cortex-m3 processors cpus asics iva-hd iss uses custom vanity license use established free open source software license
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Internet protocols
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event bubbling event bubbling type event propagation event first triggers innermost target element successively triggers ancestors parents target element nesting hierarchy till reaches outermost dom element document object provided handler initialized one way events handled browser events actions done user button click changing field etc event handlers used perform methods according event occurred e.g steps need done button clicked webpage completes loading etc consider dom structure 3 elements nested following order element 1 div element 2 span element 3 button whose on-click handlers handler1 handler2 handler3 respectively button clicked event handler element 3 triggered first event bubbles handler immediate parent element element 2 called followed handler element 1 till reaches outermost dom element event handling order handler3 handler2 handler1 innermost element event triggered called target element browsers consider event bubbling default way event propagation however another approach event propagation known event capturing direct opposite event bubbling event handling starts outermost element document dom structure goes way target element executing target element handler last order event handlers consider event bubbling default way event handling user manually select way propagation specifying last parameter addeventlistener element javascript capturemode false event handled using event bubbling capturemode true event handled using event capturing user ’ specify value capturemode argument default considered event bubbling.most browser support event bubbling event capturing except ie 9 opera 7.0 support event capturing javascript also provides event property called bubbles check whether event bubbling event returns boolean value true false depending whether event bubble parent elements dom structure isbubblepossible true event bubble ancestors isbubblepossible false event bubble handle cases one event one handler event bubbling concept implemented.the major use event bubbling registration default functions present program recent times many developers use event capturing bubbling particular necessary implement event bubbling may become complicated users keep track actions getting executed event since browsers default support event bubbling sometimes useful stop event bubbling user might get confused single trigger one element lead multiple triggers ancestors simple individual requirement user wants one event one element another another bubbling event necessity stop event bubbling user use following approaches 1 stoppropagation method stops propagation particular event parents invoking event handler target element although supported w3c compliant browsers method ’ work internet explorer version 9 lesser ie 9 stop bubbling using following code w3c compliant browsers 2 stopimmediatepropagation method stop propagation also stops handler target event executing dom multiple handlers event independent stopping execution one event handler generally ’ affect handlers target stopimmediatepropagation method prevents execution handler target w3c compliant browsers another approach stop event bubbling cancelling event preventdefault return false .but prevents target handler execution well therefore advisable use aim prevent event bubbling user still wants actions associated target element
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Programming language topics
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factory reset factory reset also known master reset software restore electronic device original system state erasing information stored device attempt restore device original manufacturer settings effectively erase data settings applications previously device often done fix issue device could also done restore device original settings electronic devices include smartphones since factory reset entails deleting information stored device essentially concept reformatting hard drive pre-installed applications data card storage card microsd card erased factory reset performed caution effectively destroys data stored unit factory resets fix many chronic performance issues freezing remove device operating system factory resets achieved variety ways depending electronic device devices could done going device service menu devices may require complete re-installation software following section lists common electronic devices factory reset computer factory resets restore computer computer original operating system delete user data stored computer microsoft windows 8 windows 10 apple macos options android devices factory data reset option settings appear erase device data reset settings method typically used device issue fixed using methods owner wants destroy personal data selling device performing study avast reported data recoverable using fairly generic publicly available forensics software factory data reset option effect knox flag reset device original factory settings way return device state compatible manufacturer warranty data sim card microsd card erased device modded custom recovery twrp able custom install custom roms sure back data well stock rom necessary many devices restored factory settings like televisions gps units tablets many electronic devices menu tools settings called service menu service menu commonly includes tool performs factory reset tool common devices displays television sets computer monitors menus usually accessed sequence button presses
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Computer security
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firewall computing computing firewall network security system monitors controls incoming outgoing network traffic based predetermined security rules firewall typically establishes barrier trusted internal network untrusted external network internet firewalls often categorized either network firewalls host-based firewalls network firewalls filter traffic two networks run network hardware host-based firewalls run host computers control network traffic machines term firewall originally referred wall intended confine fire within building later uses refer similar structures metal sheet separating engine compartment vehicle aircraft passenger compartment term applied late 1980s network technology emerged internet fairly new terms global use connectivity predecessors firewalls network security routers used late 1980s separated networks one another thus halting spread problems one network another first reported type network firewall called packet filter packet filters act inspecting packets transferred computers packet match packet filter set filtering rules packet filter either drops silently discards packet rejects packet discards generates internet control message protocol notification sender else allowed pass packets may filtered source destination network addresses protocol source destination port numbers bulk internet communication 20th early 21st century used either transmission control protocol tcp user datagram protocol udp conjunction well-known ports enabling firewalls era distinguish thus control specific types traffic web browsing remote printing email transmission file transfer unless machines side packet filter used non-standard ports first paper published firewall technology 1988 engineers digital equipment corporation dec developed filter systems known packet filter firewalls bell labs bill cheswick steve bellovin continued research packet filtering developed working model company based original first generation architecture 1989–1990 three colleagues bell laboratories dave presotto janardan sharma kshitij nigam developed second generation firewalls calling circuit-level gateways second-generation firewalls perform work first-generation predecessors also maintain knowledge specific conversations endpoints remembering port number two ip addresses using layer 4 transport layer osi model conversation allowing examination overall exchange nodes type firewall potentially vulnerable denial-of-service attacks bombard firewall fake connections attempt overwhelm firewall filling connection state memory marcus ranum wei xu peter churchyard released application firewall known firewall toolkit fwtk october 1993 became basis gauntlet firewall trusted information systems key benefit application layer filtering understand certain applications protocols file transfer protocol ftp domain name system dns hypertext transfer protocol http useful able detect unwanted application service attempting bypass firewall using disallowed protocol allowed port detect protocol abused harmful way 2012 so-called next-generation firewall ngfw wider deeper inspection application layer example existing deep packet inspection functionality modern firewalls extended include firewalls generally categorized network-based host-based network-based firewalls positioned gateway computers lans wans intranets either software appliances running general-purpose hardware hardware-based firewall computer appliances firewall appliances may also offer functionality internal network protect acting dhcp vpn server network host-based firewalls positioned network node control network traffic machines host-based firewall may daemon service part operating system agent application endpoint security protection advantages disadvantages however role layered security firewalls also vary type depending communication originates intercepted state communication traced network layer firewalls also called packet filters operate relatively low level tcp/ip protocol stack allowing packets pass firewall unless match established rule set firewall administrator may define rules default rules may apply term packet filter originated context bsd operating systems network layer firewalls generally fall two sub-categories stateful stateless commonly used packet filters various versions unix ipfw freebsd mac os x 10.7 npf netbsd pf mac os x 10.4 openbsd bsds iptables ipchains linux ipfilter application-layer firewalls work application level tcp/ip stack i.e. browser traffic telnet ftp traffic may intercept packets traveling application application firewalls function determining whether process accept given connection application firewalls accomplish function hooking socket calls filter connections application layer lower layers osi model application firewalls hook socket calls also referred socket filters application firewalls work much like packet filter application filters apply filtering rules allow/block per process basis instead filtering connections per port basis generally prompts used define rules processes yet received connection rare find application firewalls combined used conjunction packet filter also application firewalls filter connections examining process id data packets rule set local process involved data transmission extent filtering occurs defined provided rule set given variety software exists application firewalls complex rule sets standard services sharing services per-process rule sets limited efficacy filtering every possible association may occur processes also per-process rule sets defend modification process via exploitation memory corruption exploits limitations application firewalls beginning supplanted new generation application firewalls rely mandatory access control mac also referred sandboxing protect vulnerable services proxy server running either dedicated hardware software general-purpose machine may act firewall responding input packets connection requests example manner application blocking packets proxy server gateway one network another specific network application sense functions proxy behalf network user proxies make tampering internal system external network difficult misuse one internal system would necessarily cause security breach exploitable outside firewall long application proxy remains intact properly configured conversely intruders may hijack publicly reachable system use proxy purposes proxy masquerades system internal machines use internal address spaces enhances security crackers may still employ methods ip spoofing attempt pass packets target network firewalls often network address translation nat functionality hosts protected behind firewall commonly addresses private address range defined rfc 1918 firewalls often functionality hide true address computer connected network originally nat function developed address limited number ipv4 routable addresses could used assigned companies individuals well reduce amount therefore cost obtaining enough public addresses every computer organization although nat considered security feature hiding addresses protected devices become often used defense network reconnaissance
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Computer security
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data general business basic data general business basic basic interpreter based mai basic four version developed data general nova minicomputer 1970s later ported data general eclipse mv aviion computers business applications nova developed business basic business basic integer-only language inspired cobol contained powerful string-handling functions ability manipulate indexed files quickly also provided full control display screen cursor positioning attribute setting region-blanking commands business basic could interface data general infos ii database make calls directly operating system lock server gave multiple concurrent users efficient access database records small business programs could developed debugged rapidly business basic interactive nature interpreter language provide many structured programming features programs grew larger maintenance became problem limited memory space business basic programs nova programmers often resorted tricks self-modifying programs easy program business basic complicated debug original version language double precision i.e 32-bit integer used two 16-bit nova words data general ported language mv line included two copies language one double precision one triple precision unfortunately two incompatible subtle ways although data general improved language ways adding multiple-line else end statements failed lift many constraints language mv machines 9,999 line maximum 384 variable limit maximum 16 open files early competitor data general business basic bluebird business basic compiled language running proprietary superdos bluebird platform bluebird basic fully compatible data general b32 business basic highly compatible interpreter ran eclipse mv line lifted many data general business basic constraints ran significantly faster using full power 32-bit processor b32 stored variables internally 64-bit emulated double triple precision required also provided new language features b32 ported unix later dos allowing data general customers readily move hardware vendors b32 also substantial compatibility bluebird business basic transoft produced another competitor data general business basic universal business basic ubb ran unix dos substantially compatible data general business basic transoft purchased b32 1992 data general ported business basic aviion b32 ubb already available platform data general programmers one major success aviion unveiled new version business basic shootout b32 ubb data general added caching mechanism speed business basic disk access outperformed companies products within month b32 ubb added caching mechanisms drawn ahead data general transoft ubb sold universal business language
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Programming language topics
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cyber intelligence house cyber intelligence house formerly kinkayo singapore-based cyber intelligence agency specializes cyber exposure company detects monitors cyber exposure via dark web deep web data breaches alert individuals businesses potential cyber threats cyber exposure index cei company research-driven project world first proprietary global scoring system calculates exposure index listed companies based exposed credentials hacker-group activity leaked sensitive information cei sort cyber risk score given public companies listed stock exchanges hosted 11 countries australia finland germany hong kong indonesia italy south africa uk usa malaysia singapore cei scores 6,000 listed companies levels exposure analysing data collected company publicly available sources dark web deep web published data breaches companies evaluated given score ranging 0 300+ 0 indicating exposure past 12 months 300+ indicating company represent top 10 exposed companies globally index first launched october 2017 results concluded publicly listed companies australia hong kong singapore least exposed cyber threats october 2018 results updated singapore malaysia indonesia earmarked least exposed countries world also led speculation cyber threat exposure location centric asia pacific firms tend lower exposure american eu counterparts cei faced negative press south africa ranked 3rd exposed country october 2017 south african banking risk information centre sabric speculated research findings may cause unnecessary fear uncertainty doubt hacked cyber exposure monitoring app individuals launched june 2018 company aim android application alert people whenever sensitive information compromised provides free e-mail account monitoring however premium plan subscription users monitor credit cards usernames id numbers physical addresses well
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Computer security
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halalgoogling halalgoogling islamic internet search engine holy month ramadan halalgoogling used block content deemed haram sharia law collects results web search engines google bing presents halal results users
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Web technology
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compilers principles techniques tools compilers principles techniques tools computer science textbook alfred v. aho monica s. lam ravi sethi jeffrey d. ullman compiler construction first published 1986 widely regarded classic definitive compiler technology text affectionately known dragon book generations computer scientists cover depicts knight dragon battle metaphor conquering complexity name also refer aho ullman older principles compiler design first edition 1986 informally called red dragon book distinguish second edition aho ullman ’ 1977 principles compiler design sometimes known green dragon book topics covered first edition include following tradition two predecessors second edition 2006 features dragon knight cover informally known purple dragon monica s. lam stanford university became co-author edition second edition includes several additional topics including
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Programming language topics
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delay slot computer architecture delay slot instruction slot gets executed without effects preceding instruction common form single arbitrary instruction located immediately branch instruction risc dsp architecture instruction execute even preceding branch taken thus design instructions appear execute illogical incorrect order typical assemblers automatically reorder instructions default hiding awkwardness assembly developers compilers branch instruction involved location following delay slot instruction pipeline may called branch delay slot branch delay slots found mainly dsp architectures older risc architectures mips pa-risc etrax cris superh sparc risc architectures single branch delay slot powerpc arm alpha risc-v dsp architectures single branch delay slot include vs dsp µpd77230 tms320c3x sharc dsp mips-x use double branch delay slot processor execute pair instructions following branch instruction branch takes effect following example shows delayed branches assembly language sharc dsp registers r0 r9 cleared zero order number register cleared r6 r7 r9 instruction executes goal pipelined architecture complete instruction every clock cycle maintain rate pipeline must full instructions times branch delay slot side effect pipelined architectures due branch hazard i.e fact branch would resolved instruction worked way pipeline simple design would insert stalls pipeline branch instruction new branch target address computed loaded program counter cycle stall inserted considered one branch delay slot sophisticated design would execute program instructions dependent result branch instruction optimization performed software compile time moving instructions branch delay slots in-memory instruction stream hardware supports another side effect special handling needed managing breakpoints instructions well stepping debugging within branch delay slot ideal number branch delay slots particular pipeline implementation dictated number pipeline stages presence register forwarding stage pipeline branch conditions computed whether branch target buffer btb used many factors software compatibility requirements dictate architecture may change number delay slots one generation next inevitably requires newer hardware implementations contain extra hardware ensure architectural behavior followed despite longer relevant load delay slot instruction executes immediately load register memory see need wait result load load delay slots uncommon load delays highly unpredictable modern hardware load may satisfied ram cache may slowed resource contention load delays seen early risc processor designs mips isa implemented r2000 r3000 microprocessors suffers problem following example mips assembly code showing load delay slot branch delay slot
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Computer architecture
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jffs2 journalling flash file system version 2 jffs2 log-structured file system use flash memory devices successor jffs jffs2 included linux kernel since september 23 2001 merged linux kernel mainline part kernel version 2.4.10 release jffs2 also available bootloaders like das u-boot open firmware ecos rtos rtems rtos redboot prominent usage jffs2 comes openwrt least three file systems developed jffs2 replacements logfs ubifs yaffs jffs2 introduced jffs changes files directories logged flash nodes two types jffs nodes start valid created become obsolete newer version created elsewhere unlike jffs however circular log instead jffs2 deals blocks unit size erase segment flash medium blocks filled one time nodes bottom clean block one contains valid nodes dirty block contains least one obsolete node free block contains nodes garbage collector runs background turning dirty blocks free blocks copying valid nodes new block skipping obsolete ones done erases dirty block tags special marker designating free block prevent confusion power lost erase operation make wear-levelling even prevent erasures concentrated mostly-static file systems garbage collector occasionally also consume clean blocks due log-structured design jffs2 disadvantages include following
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Computer file systems
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nemesis 2 msx departure games instead controlling vic viper available ship called metalion unlike titles game heavier focus story told cut-scenes gameplay mostly unchanged rest series though powerups temporally gives ship enhancements also bosses defeated metalion flies mini-level accessed order obtain new permanent upgrades mini levels successfully cleared director general space science agency dr. venom exiled planet sard failed coup d'état year 6665 escapes invades planet nemesis seven planets controls help bacterion nemesis high council sends james burton ex-pilot vic viper pilot metalion attack dr. venom bacterion invaders game takes place year 6666 sharp x68000 port essentially enhanced remake nemesis 2 graphical quality par gradius iii br includes two new stages exclusive version game 4 new bosses two replace rematches fought msx version aside remade nemesis '90 kai nemesis 2 also ported mobile phones 2006 sony psp 2007 part salamander portable collection re-released wii virtual console 2009 project egg 2015 wii u virtual console 2016 japan
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Computer architecture
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msx msx standardized home computer architecture announced microsoft june 16 1983 conceived marketed kazuhiko nishi vice-president microsoft japan director ascii corporation nishi conceived project attempt create unified standards among various home computing system manufacturers period msx systems popular japan several countries difficult determine many msx computers sold worldwide eventually 5 million msx-based units sold japan alone despite microsoft involvement msx-based machines released united states great success nintendo family computer msx platform major japanese game studios konami hudson soft produced video games metal gear series example first written msx hardware exact meaning msx abbreviation remains matter debate 2001 kazuhiko nishi recalled many assumed derived microsoft extended referring built-in microsoft extended basic msx basic specifically adapted microsoft msx system others believed stood matsushita-sony however said team original definition machines software exchangeability conflicts earlier explanation 1985 named msx mx missile early 1980s home computers manufactured japan nec pc-6001 pc-8000 series fujitsu fm-7 fm-8 hitachi basic master featured variant microsoft basic interpreter integrated on-board roms hardware design computers various dialects basics incompatible japanese consumer electronics firms panasonic canon casio yamaha pioneer sanyo searching ways enter new home computer market nishi proposed msx attempt create single industry standard home computers inspired success vhs standard video cassette recorders many japanese electronic manufacturers along goldstar philips spectravideo built promoted msx computers piece hardware software msx logo compatible msx products manufacturers particular expansion cartridge form function part standard msx expansion game cartridge would work msx computer nishi standard built around spectravideo sv-328 computer standard consisted primarily several off-the-shelf parts main cpu 3.58 mhz zilog z80 texas instruments tms9918 graphics chip 16 kb dedicated vram sound partial i/o support provided ay-3-8910 chip manufactured general instrument gi intel 8255 programmable peripheral interface chip used parallel i/o keyboard choice components shared many home computers games consoles period colecovision home computer emulator later available msx systems could run software sega sg-1000 video game system reduce overall system cost many msx models used custom ic known msx-engine integrated glue logic 8255 ppi ym2149 compatible soundchip sometimes even z80 cpu however almost msx systems used professional keyboard instead chiclet keyboard driving price compared original sv-328 consequently components alongside microsoft msx basic made msx competitive though somewhat expensive home computer package 27 june 1983 msx formally announced press conference slew big japanese firms declared plans introduce machines japanese companies avoided intensely competitive u.s. home computer market throes commodore-led price war spectravideo yamaha briefly marketed msx machines u.s. spectravideo msx enjoyed little success yamaha cx5m model built interface various types midi equipment billed digital music tool standard personal computer 1980s europe became largest computer games market opposed console games world extremely popular commodore 64 atari 8-bit sinclair zx spectrum computers dominated time msx launched europe several popular 8-bit home computers also arrived far late capture extremely crowded european 8-bit computer market problem game software developers method msx-1 computers addressed video ram could quite slow compared systems gave direct access video memory fact completely different features msx-1 video chip using msx video access method compensate slower video access efficiently used porting mostly spectrum software made msx-1 appear slower running ported games minor compatibility issues also plagued ported spectrum games example toshiba hx-10 machine unable read certain key combinations time preventing spectrum standard q p steering whereas machines manufacturers worked fine later ported games tended use msx-1 joystick port used msx official arrow keys space bar offered option choose keys control program solving problem larger problem designers msx standard bank switching protocol prescribe hardware manufacturers banks cartridges importantly ram found moreover msx bios provide information either thus requiring programmers implement complex routines find resources often programmers assumed ram cartridges would available default bank switch location reality systems ram cartridge slot default location another bank switch location i.e toshiba hx-20 cases programs failed run saw 32 kb available memory instead full 64 kb almost msx-1 machines offered mainstream msx-1 machines offered least full 64 kb ram exceptions early phillips msx-1 models vg8000 offered 16 kb ram vg8010 32 kb casio pv-7 low budget msx targeted playing games 8 kb msx spawned four generations msx 1983 msx2 1985 msx2+ 1988 msx turbor 1990 first three 8-bit computers based z80 microprocessor msx turbor based custom 16-bit r800 microprocessor developed ascii corporation time msx turbor standard announced 1990 panasonic manufacturing msx computers initial model fs-a1st met moderate success upgraded model fs-a1gt introduced 1991 sold poorly due high retail cost 99800 yen production turbor ended 1993 panasonic decided focus release 3do msx3 scheduled market 1990 delays development vdp—then named v9978 pre-release spec sheets—caused yamaha miss time market deadline place improved msx2+ released msx turbor features new r800 processor dma 24-bit addressing disabled vdp eventually delivered two years planned deadline time market moved attempt reduce financial loss yamaha stripped nearly v9958 compatibility marketed resulting v9990 e-vdp iii video-chipset pc vga graphic cards moderate success sony also employed v7040 rgb encoder chip many products msx-fan magazine also mentions impressive power v9990 able compete much expensive hardware sharp x68000 japan south korea argentina brazil msx paramount home computer system 1980s also quite popular continental europe especially netherlands spain uk hand popular affordable model toshiba hx-10p msx computer commonly seen available around entire nation france italy enjoyed moderate success philips vg-8020 computer much impact netherlands spain italy belgium france canon v-20 affordable n't much success impact like amstrad cpc thomson to7/mo5 series computers classrooms full networked yamaha msx used teaching informatics schools arab countries soviet union cuba wildly popular government education schools centers however msx never took u.s. canada mexico china taiwan hong kong denmark singapore malaysia philippines indonesia czech republic hungary poland serbia bulgaria romania south africa india portugal never became worldwide standard makers envisioned msx lack success markets became apparent us manufacturer commodore business machines overhauled product line early 1980s introduced models plus/4 commodore 16 intended better compete features msx computers cuban government moved modernize studies computer systems 1985 higher pedagogical institutes schools pre-university education supplied toshiba panasonic msx systems resident msx basic language popularly known intelligent keyboards proved useful minister education continued process installing similar systems throughout secondary junior high centers finalized elementary schools adult education institutions newly nationwide formed “ computer electronic youth clubs ” 1987 forming computer clubs allowed cuban government interest educate common citizen computer subjects since selling systems personal private computer public banned see censorship cuba 1980s sakhr صخر computers developed al alamiah kuwaiti company started production first arabic version msx computers started producing yamaha ax100 models including msx2 msx2+ popular affordable model within arab states persian gulf sakhr msx ax170 also first arabise basic msx logo al-alamiah produced common models including ax100 ax123 ax150 ax170 ah200 ax200 ax230 ax235 ax250 ax330 ax350-i ax350-ii ax355 ax370 ax500 ax550 ax660 ax990 msx console famicom game slot msx computer ax330 user switch msx famicom modes pressing button back computer variants compatible sega mega drive ax660 ax990 sega master system pal cartridges playable ax660 ax990 tv game computer cartridge converter master system converter attached time connecting sega master system cartridge game inlet computer attaching master system converter play sega master cartridges ax660 ax990 possible inlet depth physical shape master system converter prevent converter attached correctly ax660 ax990 computers many msx computers used 1980s former eastern bloc countries tool subtitling pirated films vhs betamax cassettes msx computers used simplicity ability display prepared titles real time superimposed text mastering tapes msx arrived argentina late 1984 popular model talent msx dpc-200 based daewoo msx dpc-200 models spectravideo svi 728 svi x´press 3.5 built-in drive later came toshiba smaller numbers gradiente models brazil late 1987 talent presented msx2 tpc-310 ´turbo´ argentine market ´turbo´ name referring msx2+ also based daewoo design msx highly successful computer argentina commodore 64 thanks use education national level msx-logo language widely used schools msxii+ never made market argentina msx production ceased 1990 total 9 million msx computers sold japan making relatively popular still global standard intended comparison rival 8-bit computers commodore 64 sold 17 million units worldwide lifetime apple ii sold 6 million units zx spectrum 5 million units atari 8-bit sold least 4 million units amstrad cpc sold 3 million units tandy trs-80 model 1 sold 250,000 units sony msx2 machine launched space board russian mir spacecraft one professional broadcast video workstation based sony hitbit hb-f900 msx2 computer system msx closely resembled spectravideo sv-328 home computer spectravideo even claimed msx compatible advertisements actual launch msx systems fact completely compatible led new short-lived kind software cracking converting since msx games unplayable sv-328 computer sv-328 crackers developed method modifying msx games make work sv-328 cases included downloading msx bios sv-328 tape floppy disk spectravideo later launched svi-728 completely adhered msx standard sega sg-1000 memotech mtx colecovision many similarities msx1 standard none really compatible porting games systems somewhat easy also common port games zx spectrum msx since cpu spectrum 128 soundchip zx spectrum graphic mode could easily emulated msx screen-2 mode default msx machines hardcoded character set keyboard scan code handling algorithm msx full application software compatibility firmware bios level due minor hardware differences replacement bios another different pc may render incorrect scan code translations thus incorrect behaviour keyboard subsystem application software 2011 age labs introduced language pack firmware aiming make model support several localizations default installed gr8bit instead kanji-rom allows changing character set keyboard layout machine startup allowed changing japanese russian international portuguese locales ability change locales machine operation using newly introduced basic command lang selected locale setting stored unused rtc nvram memory space 2001 kazuhiko nishi initiated 'msx revival around official msx emulator called msxplayer official msx emulator msx copyrights maintained msx association 2004 dutch company bazix announced become representatives msx association europe english contact questions regarding msx trademarks copyrights licensing october 17 2006 bazix launched woomb.net website selling msx games english languages selection 14 games japan game sales began earlier project egg woomb.net english counterpart japanese services offered d4 enterprise also announced august 2006 launch new msx2 compatible system called one chip-msx system based altera cyclone ep1c12q240c8 fpga one chip-msx similar concept c-one commodore 64 clone also built basis single fpga chip new msx system housed box made transparent blue plastic used standard monitor tv pc keyboard two msx cartridge slots supports audio extensions msx-music scc+ sd/mmc-flashcard used external storage medium emulating disk drive used boot msx-dos due vhdl programmable hardware possible give device new hardware extensions simply running reconfiguration program msx-dos one chip-msx also two usb connectors used adding supporting vhdl code june 7 2008 msx resource center foundation reported msx trademark moved msx association msx licensing corporation referring benelux trademark register page msx names msx licensing corporation entitled entity till 28-10-2013 time website msx licensing corporation linked source text saying 'we planning revitalize msx innovative computer platform however website later changed contain logo itny partners link itny partners english japanese websites mention msx licensing corporation bazix reported website front page longer representative msx association due unable achieve goals bringing commercial msx revival beyond japanese borders transfer msx trademark msx association msx licensing corporation outlook progress western one chip msx project time soon result woomb.net taken offline well website redirecting bazix website solution free msx association contributions completed according post cooperate d4 enterprise msx licensing corporation one retro gaming related projects july 4 2008 msx association european contact website states official contact place msx association europe reports msx trademark copyright msx licensing corporation holding ever since 1983 explains msx association chaired dr. kazuhiko nishi operational division msx licensing corporation manages trademarks logo copyrights msx according article d4 enterprise refuse pay royalties msx association use ese artists factory work 1chipmsx software licenses project egg thus deal kazuhiko nishi 'directly msx licensing corporation article mentions well ese msx system 3 1chipmsx also known one chip msx ocm based july 5 2008 msx association europe website posted announcement reporting d4 enterprise selling 1chipmsx illegally post stated bazix longer representative europe due bazix cutting relationship 2011 age labs announced launch msx kit called gr8bit do-it-yourself computer learning purposes licensed msx licensing corporation kit priced 499 includes necessary components assemble working msx2 compatible computer except atx chassis power supply floppy drive hard disk ps/2 keyboard monitor also comes assembly operational manuals supplement compiled vendor community support gr8bit engineering community korean forum members made zemmix neo created new version msx called mini iq3000 cutie similar features iq-2000 msx2 made korea daewoo electronics based 1chipmsx special features like 'scan line generator 'multi language support scan line generator generates scan lines show msx screen better quality supports 2 languages time normally shows korean font working korean version msx pressing 'del key booting changes japanese mode even though default mode korean default font allocation table japanese shows japanese characters executing japanese version software popular famous msx games written japanese software-houses konami hudson soft several popular video game franchises initially established msx others received various installments msx including several titles unique system largely reworked versions games formats note clones unlicensed equipment keyboard functionally separate unit could connected non-multiplexed multiplexed interfaces multiplexed keyboard units feature additional data direction line allowing sending scan line number keyboard using data lines used return scan code decreasing overall number wires keyboard machine non-multiplexed interface usually used internal keyboards external keyboards like panasonic cf-3300 multiplexed interface used external keyboards e.g yamaha yis805 model keyboard organized matrix maximum 11 input lines 8 output lines accounting maximum 88 keys including control numerical alphanumerical keys scan line regularly queried identify state keys line query speed identified system interrupt frequency organization allows system sense state key exhibiting notorious problem 8042 microcontroller-based keyboards pressing several keys simultaneously usually 3 generates wrong input characters renders inability sense press keys due keyboard scan controlled system interrupts one troubleshooting hints msx machine display image assuming power present press caps key see respective led toggles toggle system likely suffering serious problem lack image screen i.e problem video cable video display interface overall 2009 kamil karimov designed adapter board connect ps/2 keyboard multiplexed msx keyboard interface firmware embedded attiny chip tailored daewoo cpc machines 2011 age labs embedded ps/2 keyboard controller unit based microchip microcontroller gr8bit do-it-yourself machine firmware developed directly convert ps/2 scan codes msx keyboard scan codes thus fully transparent applications allowing use controller unit different msx-compatible machines different localization setups msx standard requires least 1 cartridge slot msx models 2 slots interchangeable cases makes difference slot cartridge inserted physical connector 50 pin 2 x 25 contacts standard 2.54 mm 0.1 inch pitch edge connector using cartridge slots wide variety peripherals could connected regular game cartridges size audio cassette so-called konami size despite higher cost popular format due reliability ease use around 1985 hudson soft released credit card-sized bee card meant cheaper convenient alternative rom cartridges commercial failure titles released format source files development msx cartridges available age labs eagle msx systems generally built-in disk drive games published mainly cartridge cassette tape sony created battery backed ram cartridge hbi-55 data cartridge computers hit-bit line msx systems could used store programs data alternative cassette tapes floppy disk drives available msx however form cartridge containing disk interface electronics bios extension rom floppy disk drive interface connected external case drive south-america many systems used floppy disk drive europe drives popular japan msx1 systems included built-in 3.5 disk drive like panasonic previously named matsushita cf-3000 europe range philips msx2 systems nms 8230 8235 8245 8250 featured either 360 720 kb 3.5 floppy drives 1985 msx2 released systems often always included built-in 3.5 disk drive consequently popular media games software shifted floppy disks msx-dos disk operating system internal software mechanisms much like cp/m cp/m software could ported reasonably easily file system compatible ms-dos user commands also similar early ms-dos versions way microsoft could promote msx home use promoting ms-dos based personal computers office environments msx 3.5 floppy disks directly compatible ms-dos although details like file undeletion boot sector code different like ms-dos 1 msx disks formatted msx-dos 1 support subdirectories september 2012 age labs extended standard including support 1.44mb 3.5 ” format 1.44mb diskette size goes two configurations standard 1 sector per cluster 9 fat sectors compatible 4 sectors per cluster 3 fat sectors msx computers emulated many platforms today early msx emulators often based code pioneer fmsx portable msx emulator marat fayzullin many emulators removed fayzullin z80 emulation code entirely later versions avoid legal problems time fmsx n't free software somewhat later fmsx source code became free use non-profit use however license still required commercial use december 31 2013 windows version fmsx 3.7 released free anyone use official msx emulator msxplayer produced msx association inventor msx standard kazuhiko nishi president version 0.146.u mess currently supports 90 percent msx versions february 2007 nintendo japan announced msx games available wii virtual console emulator confirmed games would cost 700 wii points become available middle 2007 also became available wii u december 25 2013 ultimately 13 games mainly konami titles wii plus 1 wii u released service japan
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Computer architecture
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protocol converter protocol converter device used convert standard proprietary protocol one device protocol suitable device tools achieve interoperability protocols software installed routers convert data formats data rate protocols one network protocols network data navigating varieties protocols used different fields like power generation transmission distribution oil gas automation utilities remote monitoring applications major protocol translation messages involve conversion data messages events commands time synchronization general architecture protocol converter includes internal master protocol communicating external slave devices data collected used update internal database converter external master requests data internal slave collects data database send external master different schemes handling spontaneous reporting events commands different physical medium communication protocol-x include rs-232 rs-485 ethernet etc protocol converter applications vary industry industry protocol converter software converter hardware converter integrated converter depending protocols major protocols used area application listed list automation protocols protocol converters generally used transforming data commands one device application another necessarily involves transformation data commands representation encoding framing achieve conversion simple complex types conversions depending application domain used simplest commonly used conversion protocol conversion modbus rtu modbus tcp conversion change overall framing hence easy take serial modbus rtu frame encapsulate tcp/udp socket send ethernet since protocol framings except actual physical layer transmission application layers interpret data similarly long communication interfaces made transparent however exist complex conversions example data formatted data types supported object models etc different conversion engine needs make modifications framing mapping information type data command cases object models also might user configurations required defining mapping supported non-supported data types transformations however bring conversion advantages communication delay processing latency overall end end processing time finite needs considered solution designs latency end-to-end communication depends processing delay hardware and/or software used protocol conversion complexity solution architecture latencies vary typical industrial energy automation applications 10—20 milliseconds high 1 second solution architectures using protocol converters need consider latency impact project converters considered also majority architectures would involve configuration mapping require considerable engineering effort engineering time need considered defining project schedules
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Computer architecture
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comparison object pascal c computer programming languages c object pascal similar times origin influences purposes used design compile compilers early lifetimes c pascal old programming languages original pascal definition appeared 1969 first compiler 1970 first version c appeared 1972 c n't change much time pascal evolved lot nowadays vast majority pascal programming done modern object pascal old procedural pascal old procedural pascal today essentially limited microcontroller programming tools mikropascal object pascal main dialect used tools delphi lazarus ide free pascal documented modern object pascal used free pascal delphi c documented c99 standardized 1999 syntactically object pascal much algol-like c. english keywords retained c uses punctuation symbols — pascal codice_1 codice_2 codice_3 c uses codice_4 codice_5 codice_6 example however c actually algol-like pascal regarding simple declarations retaining type-name variable-name syntax example c accept declarations start block outer block function another subtle difference role semicolon pascal semicolons separate individual statements within compound statement whereas terminate statement c. also syntactically part statement c transforming expression statement difference manifests primarily two situations superfluous semicolon put last line end thereby formally inserting empty statement traditional c codice_9 since c99 also codice_10 object pascal codice_11 codice_12 codice_13 c pascal differ interpretation upper lower case c case sensitive pascal thus codice_14 codice_15 distinct names c identical pascal languages identifiers consist letters digits rule first character may digit c underscore counts letter even _abc valid name names leading underscore often used differentiate special system identifiers c. pascal also accepts character part identifiers difference c. c pascal use keywords words reserved use language examples const goto keywords happen common languages c basic built-in type names also keywords e.g int char combinations keywords e.g unsigned char pascal built-in type names predefined normal identifiers recent object pascal compilers however allow escape keywords feature mainly need directly communication foreign oop systems like com cocoa might use fields methods based pascal keywords c way escape keywords pascal procedure definitions start keywords procedure function type definitions type c function definitions determined syntactical context type definitions use keyword codice_16 languages use mix keywords punctuation definitions complex types instance arrays defined keyword array pascal punctuation c enumerations defined keyword codice_17 c punctuation pascal pascal functions begin end delimit block statements proper c functions use delimit block statements optionally preceded declarations c prior c99 strictly defines declarations must occur statements within particular block allows blocks appear within blocks way go around pascal strict declarations must occur statements allows definitions types functions variable declarations encapsulated function definitions level depth grammars languages similar size implementation perspective main difference two languages parse c necessary access symbol table types pascal one construct assignment instance c fragment codice_18 could declaration codice_19 object whose type pointer codice_20 statement-expression multiplies codice_20 codice_19 corresponding pascal fragment codice_23 unambiguous without symbol table pascal requires variable function declarations specify type explicitly traditional c type name may omitted contexts default type codice_24 corresponds codice_25 pascal implicitly assumed however defaults considered bad practice c often flagged warnings c accommodates different sizes signed unsigned modes integers using modifiers codice_26 codice_27 codice_28 codice_29 etc exact meaning resulting integer type machine-dependent however guaranteed codice_30 shorter codice_24 codice_24 shorter codice_33 however c standard least minimal sizes types specified guarantees codice_34 single byte codice_24 least two bytes pascal similar end performed declaring subrange integer compiler may choose allocate smaller amount storage declared variable subrange feature supported c. major subtle difference c pascal promote integer operations pascal operations integers integer subranges effect operands promoted full integer c defined rules promote different types integers typically resultant type operation two integers precision greater equal precisions operands make machine code generated c efficient many processors highly optimizing pascal compiler reduce eliminate effect standard pascal rules pre-standard implementation c well small-c et al allowed integer pointer types relatively freely intermixed c character type codice_34 kind integer longer codice_33 expressions codice_38 therefore perfectly legal declarations codice_39 codice_40 integer nature codice_34 eight-bit byte machines clearly illustrated declarations whether codice_34 type regarded codice_28 codice_29 default implementation pascal characters integers distinct types inbuilt compiler functions codice_45 codice_46 used typecast single characters corresponding integer value character set use vice versa e.g systems using ascii character set codice_47 codice_48 tab character addition codice_49 type object pascal also codice_50 represent unicode characters c usually implemented macro codice_16 name codice_52 simply alias codice_24 pascal boolean enumerated type possible values boolean false true ordinal value false=0 true=1 values undefined conversion integer ord used standard function integer boolean however conversion simple practice c binary valued relational operators == may regarded boolean sense always give results either zero one tests || etc performed zero-checks false represented zero true represented value interface com object pascal added codice_54 codice_55 codice_56 type whose size respects prefix follow c truth table free pascal added proper pascal boolean types size suffix codice_57 interface glib uses codice_58 32-bit boolean type pascal truth table c programmer may sometimes use bitwise operators perform boolean operations care needs taken semantics different operands make use one bit represent value pascal another abstract high level method dealing bitwise data sets sets allow programmer set clear intersect unite bitwise data values rather using direct bitwise operators example pascal c although bit operations integers operations sets considered similar sets implemented using bits direct parallel uses unless non-standard conversion integers sets possible pascal could also bitwise operations exactly way c use codice_1 codice_2 codice_61 codice_62 operators operators normally work booleans operands integers behave bitwise operators made possible boolean integer distinct incompatible types therefore c code could written pascal c string remains pointer first element null-terminated array char 1972 one still use library support codice_63 manipulate strings object pascal many string types new type introduced old one kept backwards compatibility happened twice delphi 2 introduction ansistring delphi 2009 unicodestring besides main string types short- ansi- wide- unicodestring corresponding character types ansichar widechar=unicodechar types derived character type string properties pointer char array char dynamic array char pointer array char etc. object pascal codice_64 compiler-managed type reference-counted i.e. storage management handled compiler accurately runtime code inserted compiler executable string concatenation done codice_65 operator string comparison done standard relational operators case sensitive codice_66 object pascal also provides c-compatible strings type codice_67 manipulation routines defined codice_68 unit moreover object pascal provides wide variety string types convenience plain codice_76 type provided depending compiler switch could mean codice_69 codice_71 codice_74 additional convention used limit number characters given codice_69 otherwise codice_81 codice_82 strings freely intermixed manipulating strings compiler silent conversion required note target string type codice_69 silent truncation might happen due maximum length allowed example c real concept array pseudo construct declare storage multiple variables type arrays c n't know length 're referenced pointer first element 're always 0 based example get array length one calculate codice_84 therefore count length integer array use codice_85 common mistake calculate function expecting array argument despite appearance function accept pointer argument real array therefore inside function array treated plain pointer example common solution problem always pass array length function argument functions expect array argument also provide placeholder length despite treatment pointer pointer style constructs could used array example code would compile fine would cause access violation executed care taken designing code documentation explicitly state prevent users mistake assignment static arrays n't allowed one must use codice_86 function variants copy data arrays pascal array declared using codice_87 keyword specifying lower upper bound base type latter usually defined range type example arrays know upper lower bounds implicitly length bounds passed along function expects array argument functions codice_88 codice_89 codice_90 retrieve lower bound upper bound array length respectively context without explicit cast arrays ca n't wo n't converted pointers compile time error property type-safe programming assignment static arrays allowed assignment copies items source array destination mandatory upper lower bounds compatible source destination somehow 're different one use codice_91 partially copy data however since codice_91 low-level function one must use care programmer responsibility ensure data movement exceeds neither destination source boundary example c language support declaring using dynamic arrays however due pointer dereference syntax dynamic array could implemented memory management functions usually codice_93 example seen length n't maintained automatically reallocation use additional variable protect enough memory error assignment dynamic arrays follows pointer assignment rule object pascal provides language-level support dynamic arrays declared lower upper bound omitted one must call codice_94 function allocate storage dynamic arrays object pascal reference counted one n't worry freeing storage dynamic arrays always zero-based three functions codice_88 codice_89 codice_90 would still retrieve lower bound upper bound array length correctly example assignment dynamic arrays copies reference source array destination real copy required one use codice_98 function example
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Programming language topics
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ndiswrapper ndiswrapper free software driver wrapper enables use windows xp network device drivers devices pci cards usb modems routers linux operating systems ndiswrapper works implementing windows kernel ndis apis dynamically linking windows network drivers implementation result works systems based instruction set architectures supported windows namely ia-32 x86-64 native drivers network adapters available linux manufacturers maintain proprietary interfaces write cross-platform drivers ndiswrapper allows use windows drivers available virtually modern pc network adapters three steps creating linux driver installing using ndiswrapper composed two main parts command-line tool used installation time windows subsystem used application calls wi-fi subsystem outcome ndiswrapper installation sort linux driver able work linux applications first action user compile couple windows files ndiswrapper version windows ddk linux kernel module done tool named ndiswrapper resultant linux driver installed often manually os linux application send request linux driver automatically needed adaptations call its—now—internal windows driver ddk achieve compilation ndiswrapper requires least .inf .sys files invariably supplied parts windows driver example driver called mydriver files mydriver.inf mydriver.sys vendorid productid 0000:0000 ndiswrapper installs driver /etc/ndiswrapper/mydriver/ directory contains three files graphical frontends ndiswrapper ndisgtk ndisconfig allow ndiswrapper installed using graphical user interface rather console commands ndiswrapper enables unix-like system use windows drivers type ndis wifi useful time linux wi-fi drivers common wi-fi cards composed ndiswrapper uses windows inf files linux application calls device registered linux ndiswrapper device ndiswrapper determines windows driver targeted converts linux query windows parlance calls windows driver waits result translates linux parlance sends result back linux application possible linux driver ndiswrapper linux driver call windows driver execute address space linux kernel windows driver composed layered drivers example one ethernet one usb upper layer driver called upper layer create new calls irp windows parlance calling mini ntoskrnl mini ntoskrnl must know drivers must registered internal database priori reading windows .inf files
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Operating systems
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innodb innodb storage engine database management system mysql mysql 5.5 december 2010 later use default replacing myisam provides standard acid-compliant transaction features along foreign key support declarative referential integrity included standard binaries distributed mysql ab exception oem versions innodb became product oracle corporation acquisition finland-based innobase oy october 2005 software dual licensed distributed gnu general public license also licensed parties wishing combine innodb proprietary software innodb supports
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Databases
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mobile service architecture mobile service architecture msa jsr 248 specification describes end-to-end wireless environment java msa includes full set 16 jsrs subset 8 jsrs msa subset includes following jsrs msa includes msa subset following jsrs
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Programming language topics
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oracle webcenter oracle webcenter oracle portfolio user engagement software products built top jsf-based oracle application development framework three main products make webcenter portfolio purchased together suite individually products separate connected markets webcenter content competes enterprise content management market webcenter sites competes web experience management market webcenter portal competes self-service portal content delivery market space different combinations products frequently used together oracle bundled together within webcenter product family oracle webcenter contains set components building rich web applications portals team collaboration/social sites oracle webcenter targeted enterprise larger accounts significant content management requirements need deliver information internal external portals customer-facing websites within integrated business applications oracle made particular effort integrate webcenter leading business applications e-business suite peoplesoft jd edwards content centrally managed one location shared across multiple applications development community advanced business users webcenter provides development environment includes webcenter framework webcenter services along out-of-the-box application team collaboration enterprise social networking according oracle strategic portal product eventually replacing oracle portal well portal products acquired bea product costs 70000 per cpu webcenter services 125,000 per cpu webcenter suite production installation users expect deploy least 4 cpus base system likely additional cpus development testing webcenter includes embedded us licenses oracle secure enterprise search oracle universal content management oracle bpel process manager addition webcenter needs database store information supported licensed database oracle database ms sql server ibm db2 work three major products webcenter product stack base webcenter framework allows user embed portlets adf taskflows/pages content customizable components oracle adf application framework pieces integrated oracle jdeveloper ide providing access resources webcenter services set independently deployable collaboration services incorporates web 2.0 components content collaboration communication services full list provided webcenter services includes oracle adf user interface components called taskflows embedded directly adf applications addition apis utilized create custom uis integrate services non-adf applications finally webcenter spaces closed source application built webcenter framework services offers prebuilt project collaboration solution compared solutions like microsoft sharepoint atlassian confluence limited mechanisms extend application note product called webcenter interaction built core webcenter stack former plumtree portal product also oracle portal products oracle included webcenter suite umbrella products products included suite regardless whether built adf based webcenter framework webcenter comprises furthermore several editions among others webcenter suite plus webcenter portal webcenter content webcenter sites webcenter sites satellite server distributed caching mechanism stores assembles pagelets elements output webcenter universal content management seven webcenter adapters one wce management available social networking services enables users maximize productivity collaboration shared services provides features social networking personal productivity personal productivity services focuses requirements individual rather group webcenter framework supports following standards 22 february 2012 oracle released webcenter 11g release 1 patch set 5 includes many bug fixes addition several new enhancements patch set mainly targeted releasing customer bug fixes january 2011 oracle released webcenter 11g release 1 patch set 3 converged portal platform major new release many features integrated previously acquired portal products including greatly improved flexible portal framework improved gui personalization server brand new navigation model support hierarchical pages spaces jsr 286 improved performance webcenter framework services lacks support notable technologies
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Distributed computing architecture
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palm iiix palm iiix pda palm computing released 1999 briefly scaled palm iiie introduced marketplace palm iiix improved upon palm iii featuring new enhanced easier read lcd 4 mb ram opposed 2 mb palm iii palm iiix also 16 mhz motorola dragonball ez cpu faster along claims efficient 16 mhz motorola dragonball cpu found previous palm models palm iiix featured new inverse electroluminescent backlight illuminated screen text instead screen background new feature area controversy many people disliked feature many found improvement palm iiix shipped palm os 3.1 including many fixes previous version palm os 3.0 palm iiix also featured expansion slot inside casing slot could accommodate 3rd party upgrade card expand palm iiix functionality storage ability model suffered design defect cpu wherein date would often fail change midnight especially batteries fresh os upgrade last palm os downloaded www.palm.com website 3.3 however last os iiix 4.1 bought time came cd cds discontinued bit hard find
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Computer architecture
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w3perl w3perl free software logfile analyser parse web/ftp/mail/cups/dhcp/ssh squid logfiles major web logfile formats supported web clf/eclf/neclf unix iis/w3c microsoft mail postfix/sendmail/exim well split/compressed files page tagging counter also supported logfiles access output spread html pages graphics sortable table stats run single command line web browser essential features like hosts pages scripts countries filetype traffic hourly daily weekly monthly referrer user agent error available along specific w3perl stats like real-time session stats w3perl administration interface allows building configuration files web interface one also manage configuration files package updates run scripts see stats output written perl w3perl installed operating system supports perl installed unix windows mac os x installer available windows mac os x. w3perl licensed gnu gpl running scripts administration interface restricted login/password blocking referrer spam added based blacklist file must updated regularly real-time stats run prevent overloading server
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Web technology
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swedish open cultural heritage soch swedish open cultural heritage web service used searching retrieving data museum historical environment sectors sweden soch aggregate metadata different central regional local databases order facilitiate applications search present cultural heritage data via open api aim facilitate application developers build applications exploit soch march 2013 +10 different applications built using soch api one first applications built soch mobile phone application displaying ancient monuments map layer number museums also building applications soch order make stuff available online 2012 commercial applications started appear using soch data soch operated developed swedish national heritage board snhb snhb used soch api applications http //www.kringla.nu http //www.platsr.se
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Databases
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magic sysrq key magic sysrq key key combination understood linux kernel allows user perform various low-level commands regardless system state often used recover freezes reboot computer without corrupting filesystem effect similar computer hardware reset button power switch many options much control key combination provides access powerful features software development disaster recovery sense considered form escape sequence principal among offered commands means forcibly unmount file systems kill processes recover keyboard state write unwritten data disk respect tasks feature serves tool last resort magic sysrq key work certain conditions kernel panic hardware failure preventing kernel running properly key combination consists another key controls command issued may released pressing command key long remains held combinations always assume qwerty keyboard layout example dvorak simplified keyboard combination shut system uses key instead furthermore keyboards may provide separate key case separate key present devices notably laptops key may need pressed use magic key e.g thinkpad carbon x1 activated pressing simultaneously releasing still holding see magic sysrq key may also accessible serial console sending rs-232 break signal sysctl option set allow user space programs command line shell sysrq may accessed writing e.g. common use magic sysrq key perform safe reboot linux computer otherwise locked abbr reisub prevent required reboot gives programs chance save emergency backups unsaved work qwerty azerty mnemonics raising elephants utterly boring reboot even system utterly broken simply word busier read backwards often used remember following sysrq-keys sequence magic keys used kill frozen graphical program program chance restore text mode make everything unreadable commands part svgalib command restore text mode make console readable distributions include command key command may sometimes able force return text console use ... n highest number text consoles set distribution would normally used reenter gui mode system x server crashed also distributions opens text consoles reenter gui mode reenter gui mode login page order log another user feature controlled compile-time option kernel configuration sysctl kernel parameter newer kernels since 2.6.12 possible fine-grained control magic sysrq key used machines number written 0 1 number greater 1 bitmask indicating features allow ubuntu set boot time value defined magic sysrq key originally implemented part kernel keyboard handler debugging functionality also exposed via proc filesystem commonly used provide extended management capabilities headless remote systems linux daemons provide method accessing sysrq features tcp connection authenticating plain-text password daemon invoke pre-configured sysrq triggers system load average exceeds certain threshold xen hypervisor functionality send magic commands hosted domains via command additionally sysrq command invoked xen paravirtual console sending break sequence followed desired key many embedded systems attached keyboard instead use serial console text input/output running system possible invoke magic sysrq feature serial console sending serial break followed desired key method sending break dependent terminal program hardware used connect serial console chromebooks keyboard dedicated sysrq key use instead however keys different function ibm power systems servers invoke magic sysrq feature using followed desired key hardware management console ibm mainframe partitions invoke magic sysrq feature using followed desired key 3270 hmc console
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Operating systems
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spoken dialog systems spoken dialog system computer system able converse human voice two essential components exist written text dialog system speech recognizer text-to-speech module written text dialog systems usually use input systems provided os distinguished command control speech systems respond requests attempt maintain continuity time spoken dialog systems vary complexity directed dialog systems simple require developer create graph typically tree manages task may correspond needs user information access systems typically based forms allow users flexibility example order retrieval constraints specified use optional constraints limited capabilities problem-solving dialog systems may allow human users engage number different activities may include information access plan construction possible execution latter examples systems include pionieers dialogue systems companies like speech recognizer system seventies cselt laboratories led european research projects eighties e.g sundial end darpa project us field spoken dialog systems quite large includes research featured scientific conferences sigdial interspeech large industrial sector meetings speechtek avios following might provide good technical introductions
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Computational linguistics
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cynbe ru taren jeffrey prothero march 15 1956–november 16 2016 american computer programmer author citadel arguably first virtual world system one longest-running open source projects digital anatomist software better known visible human project original pascal strek.pas star trek game program first loglan parsers mythryl production-grade port sml/nj prothero used screenname cynbe ru taren online cynbe ru taren name fictional alien poul anderson 1964 science fiction novel star fox sbn 425-03772-x novel cynbe ru taren aleriona intellect master garden war fleet admiral military strategist grand commission negotiators died november 16 2016 battle colorectal cancer prothero born march 15 1956 london ontario academic parents john jack joyce prothero attended kindergarten ontario first form london england second form cambridge england third grade boston massachusetts fourth twelfth seattle washington prothero lived seattle programming designing virtual worlds 1997 moved austin texas live wife allucquere rosanne stone professor university texas austin beginning 1998 prothero stone divided time santa cruz tahoe city california maintaining residence austin school sessions prothero enrolled university washington 1974 spending time campus computer center learned craft visual techniques laboratory using pdp10 mohawk data 600lpm printer long working full-time programmer department biological structure headed john w. sundsten john prothero wrote skandha visualization system assembled microscopic sections biological material three-dimensional images could manipulated minutely reveal details interior objects human body biological structure department named effort digital anatomist project image database supplied raw digital material wolfgang rauschning swedish researcher microtomy microscopy specialized producing ultrathin tissue cross-sections rauschning method subtractive ablating layer carefully frozen tissue thousand molecules thick coating exposed surface glycerol mixture rauschning adapted specific tissue photographing surface high resolution repeating tissue completely sectioned rauschning sent image via internet digital anatomist database university washington seattle method produced extremely high resolution digital images vivid color almost none distortion would normally caused displacement forces generated action conventional microtome extreme thinness settings sundsten jeffrey prothero john prothero asked rauschning include fiduciaries sections enabled prothero skandha 3d visualization software assemble huge digital database three-dimensional flythrough-capable anatomical images extremely fine grain group made prothero tapes 3d reconstructions freely available website hearing work national library medicine issued call proposals national 3d anatomical reconstruction database would later become visible human project astonishment digital anatomist group found university colorado made strong bid contract using prothero ’ data tapes examples work technically nothing illegal since tapes freely available colorado bid mention provenance colorado contract continued display prothero ’ work without attribution first three years contract although later work based methodology developed digital anatomist project colorado specimen sectioning system involved something rather like bandsaw produced considerably coarser-grained reconstructions shortly afterward chief scientists uw digital anatomist project resigned frustration 1980 prothero completed building second computer heath h89 homebrew power supply silent 700 acoustic coupler began writing code december 14 released first version citadel december 24 first release used phone number connected hardware prothero study first call program citadel instead named ode phone number acronym ode-data later changed odd-data suggestion friends version citadel released december 24 1980 written c fast responsive self-maintaining ran 90kb floppy disc world consisted collection rooms connected “ clues ” since rooms invisible clue included name clued room part clue details citadel room architecture see citadel software page details citadel program architecture see even early stage new social forms enabled citadel system allowed users display aberrant antisocial behavior well-known among virtual world researchers including griefing unresolvable arguments misreadings innocuous remarks resulting flame wars hardware problems finally brought system prothero felt enough peacekeeping wanted concentrate programming consequently passed software system david mitchell friend lived bainbridge island washington far prothero ’ home system mitchell acquired went become canonical citadel april 1982 prothero released citadel v.2.11 c users group mailing list social experiment distribute power broadly v.2.1.1 provided class people neither sysadmins users partial sysadmin powers afford measure accountability actions produced unerasable paper trail v.2.11 also implemented secure database encrypting disc using simple xor hash prothero continued make innovations citadel software moving projects prothero posted citadel source code rcp/m archive network 1990 code cited one longest running open source projects
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Programming language topics
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lawrence m. breed lawrence larry moser breed born july 17 1940 computer scientist artist inventor best known involvement programming language apl undergraduate stanford university 1961 created first computer animation language system used stanford football half-times coordinate images produced 100 ft-by-100 ft array rooters holding colored cards graduate student stanford corresponded apl inventor ken iverson correct formal description ibm system/360 used iverson notation receiving m.s stanford 1965 academic supervisor niklaus wirth joined iverson group ibm thomas j. watson research center yorktown heights new york created first implementation apl philip s. abrams mainframe computer ibm 7090 1965 later created apl implementations experimental ibm little computer ibm 360 1966 ibm 1130 breed 1973 recipient dick lathwell roger moore grace murray hopper award association computing machinery work design implementation apl\360 setting new standards simplicity efficiency reliability response time interactive systems dan dyer others co-founded scientific time sharing corporation 1969 led development apl plus time-sharing system 1972 francis bates iii wrote one world first worldwide email systems named mailbox breed rejoined ibm 1977 helped develop international organization standardization iso apl standard joined ibm efforts port berkeley software distribution bsd unix onto ibm platforms worked compilers programming language c floating-point arithmetic standardization radix conversion retiring 1992 breed became significant contributor burning man festival playa name ember conceived built first trash fence capture windborne debris created spiraling flaming sculpture chaotick built artistic bicycle light effects edited proofread black rock gazette newspaper role continues co-founder director successor black rock beacon burning man materials earth guardian promoted leave trace ethos particularly post-event cleanup 1973 1974 took first place co-solver donna breed dictionary rally associated burning man activities breed devised gray-b-gon evaporator graywater disposal bay area workshops directed construction burning man campers 100 units 2012
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Programming language topics
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ibm a2 ibm a2 massively multicore capable multithreaded 64-bit power isa processor core designed ibm using power isa v.2.06 specification versions processors based a2 core range 2.3 ghz version 16 cores consuming 65 w less powerful four core version consuming 20 w 1.4 ghz a2 core capable four-way multithreading 16 kb+16 kb instruction data cache per core core variants execute instructions in-order a2 core processor core designed customization embedded use system chip-devices implements 64-bit power isa v.2.06 book iii-e embedded platform specification support embedded hypervisor features 4-way simultaneous multithreaded core 4×32 64-bit general purpose registers gpr full support little big endian byte ordering core fine grain branch prediction unit bpu eight 1024-entry branch history tables 16 kb 8-way set-associative level-1 data cache 4-way set-associative 16 kb level-1 instruction cache executes simple in-order pipeline capable issuing two instructions per cycle one 6-stage arithmetic logic unit alu one optional auxiliary execution unit axu includes memory management unit floating point unit fpu facilities handled axu support number standardized customized macros floating point units vector units dsps media accelerators units instruction sets registers part power isa core system interface unit used connect die cores 256-bit interface data writes 128-bit interface instruction data reads full core speed poweren power edge network wire-speed processor designed hybrid regular networking processors switching routing typical server processor manipulating packaging data revealed february 8 2010 isscc 2010 chip 8 mb cache well multitude task-specific engines besides general-purpose processors xml cryptography compression regular expression accelerators mmus four 10 gigabit ethernet ports two pcie lanes four chips linked smp system without additional support chips chips said extremely complex according charlie johnson chief architect ibm use 1.43 billion transistors die size 428 mm² fabricated using 45 nm process blue gene/q processor 18 core chip running 1.6 ghz special features fast thread context switching quad simd floating point unit 5d torus chip-to-chip network 2 gb/s external i/o cores linked crossbar switch half core speed 32 mb edram l2 cache l2 cache multi-versioned supports transactional memory speculative execution blue gene/q chip two ddr3 memory controllers running 1.33 ghz supporting 16 gb ram uses 16 cores computing one core operating system services 17th core take care interrupts asynchronous i/o mpi flow control ras functionality 18th core used spare case one cores permanently damaged instance manufacturing shut functional operation blue gene/q chip manufactured ibm copper soi process 45 nm deliver peak performance 204.8 gflops 1.6 ghz draws 55 watts chip die size 19×19 mm 359.5 mm² uses 1.47 billion transistors
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Computer architecture
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fast tcp fast tcp also written fasttcp tcp congestion avoidance algorithm especially targeted long-distance high latency links developed netlab california institute technology commercialized fastsoft fastsoft acquired akamai technologies 2012 fasttcp compatible existing tcp algorithms requiring modification computer sending data name fast recursive acronym fast aqm scalable tcp aqm stands active queue management tcp stands transmission control protocol role congestion control moderate rate data transmitted according capacity network rate users transmitting like tcp vegas fast tcp uses queueing delay instead loss probability congestion signal current congestion control algorithms detect congestion slow discover packets dropped average sending rate depends loss probability two drawbacks first low loss probabilities required sustain high data rates case tcp reno low loss probabilities required even new congestion avoidance algorithms h-tcp bic tcp hstcp require loss rates lower provided wireless wide area networks moreover packet loss provides single bit information congestion level whereas delay continuous quantity principle provides information network fast tcp flow seeks maintain constant number packets queues throughout network number packets queues estimated measuring difference observed round trip time rtt base rtt defined round trip time queueing base rtt estimated minimum observed rtt connection packets queued sending rate increased many queued rate decreased respect direct descendant tcp vegas difference tcp vegas fast tcp lies way rate adjusted number packets stored small large tcp vegas makes fixed size adjustments rate independent far current rate target rate fast tcp makes larger steps system equilibrium smaller steps near equilibrium improves speed convergence stability delay-based algorithms principle maintain constant window size avoiding oscillations inherent loss-based algorithms however also detect congestion earlier loss-based algorithms since delay corresponds partially filled buffers loss results totally filled buffers either strength weakness protocol used network delay-based inefficiency loss avoided however loss-based delay-based protocols share network delay-based algorithms tend less aggressive overcome suitable choice parameters leading complex interactions studied tang et al delay measurements also subject jitter result operating system scheduling bus contention whether strengths weaknesses prevail clear depends large part particular scenario propagation delay used fast window control algorithm clean network queueing delay maintained existing fast flows may mistaken part propagation delay new flows join later shown ns-2 simulations effect estimation error equivalent modifying underlying utility functions favor new flows existing flows method eliminate error suggested fast tcp shown promising terms system stability throughput fairness however requires buffering increases linearly number flows bottlenecked link paper proposes new tcp algorithm extends fast tcp achieve α n -proportional fairness steady state yielding buffer requirements grow nth power number flows authors call new algorithm generalized fast tcp prove stability case single bottleneck link homogeneous sources absence feedback delay simulation results verify new scheme stable presence feedback delay buffering requirements made scale significantly better standard fast tcp unlike tcp congestion avoidance algorithms fast tcp protected several patents instead seeking standardization ietf inventors fast notably steven h. low cheng jin seeking commercialize company fastsoft currently fastsoft sells 1-unit rack appliance deployed sender-side software hardware modifications needed either end
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Internet protocols
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ipad pro ipad pro family line ipad tablet computers designed developed marketed apple inc. runs ios ipados mobile operating systems current generation available two screen sizes four options internal storage capacities 64 256 512 gb 1 tb first ipad pro 12.9-inch version announced september 9 2015 released november 11 2015 larger previous ipad models first ipad tablet feature lpddr4 ram 12.9-inch tablet later followed smaller 9.7-inch version announced march 21 2016 released march 31 year june 5 2017 second generation ipad pro announced features a10x fusion processors basic storage 64 gb optional 512 gb upgraded displays include new 10.5-inch version replace 9.7-inch model 12.9-inch version refreshed following announcement models first generation ipad pro discontinued third generation ipad pro announced october 30 2018 available two screen sizes feature full screen displays 11-inch model replacing 10.5-inch model previous generation also feature 1 tb storage face id works vertical horizontal orientations feature apply iphones face id third generation feature home button 12.9-inch version ipad pro announced apple special event september 9 2015 released november 11 2015 gold silver space gray color options prices ranging us 799.99 1,229.99 based storage size cellular connectivity march 21 2016 9.7 inch version ipad pro announced apple keynote additional rose gold color option 9.7 inch version also introduced ability choose base 32gb model cellular wifi option previously cellular wifi option available 128gb ipad pro models 9.7 inch model priced 599 1,129 depending configuration released march 31 2016 9.7-inch ipad pro compared ipad air 2 features faster cpu better camera first ipad feature true tone flash retina flash also highest storage ipad time 256 gb storage option true tone display allows lcd adapt ambient lighting change color intensity different environments ipad pro models include a9x chip apple m9 motion co-processor 9.7 inch model however slightly underclocked cpu 2.16 ghz compared 2.26 ghz 12.9 inch model 2 gb ram number features carried standard ipad touch id retina display new features include smart connector keyboard four stereo speakers located pairs top bottom device 12.9 inch model 2732-by-2048 retina display 264 pixels per inch 9.7 inch model 2048-by-1536 retina display 264 pixels per inch features variable refresh rate first apple 12.9 inch version ipad pro first ipad include 4 gb ram customized 12.9 inch ipad pro also designed jony ive submitted time design auction special edition ipad pro edition 1 1 label engraved back comes custom yellow-gold anodised finish blue leather smart cover orange leather apple pencil case cover sold apple elsewhere second generation ipad pro announced june 5 2017 alongside ios 11 2017 wwdc second-generation ipad pro models 10.5-inch 12.9-inch a10x hexa-core cpu 12-core gpu apple promotion display technology supports hdr10 dolby vision content ios 11 later 120 hz refresh rate true tone display 50 percent brighter earlier models sizes also 12-megapixel rear-facing camera quad-led true-tone flash 7-megapixel front-facing camera retina flash usb-c connection speeds using lightning cables usb-c fast-charge support second generation ipad pro storage capacities 512 gb march 18 2019 10.5-inch ipad pro discontinued replaced 10.5-inch ipad air third generation ipad pro announced october 30 2018 apple special event howard gilman opera house brooklyn new york redesigned 2018 models feature new edge-to-edge liquid retina displays face id improved 12mp 7mp cameras usb-c connectors apple a12x bionic processors tablets offered 11-inch 12.9-inch sizes first ipad models offer tap-to-wake lcd displays following iphone x 1tb internal storage additionally third generation tablets lack touch id headphone jack former superseded face id released november 7 2018 available silver space gray four accessories made specifically ipad pro sold separately smart screen cover attachable keyboard smart keyboard active bluetooth tracking stylus apple pencil form-fitted silicone case compatible smart keyboard smart keyboard docks ipad pro using smart connector magnetic connection provides data transfer power smart keyboard doubles kickstand comparable competing microsoft surface pro design smart keyboard similar design smart cover accessory first generation apple pencil precision stylus exclusive ipad pro ipad 2018 ipad air ipad mini released 2019 accessory rechargeable via lightning port tablet ipad pro introduces new display increased responsiveness precision previous ipad displays apple pencil support added keynote apple demonstrated drawing managing publication layout document annotation second generation apple pencil functions exclusively 2018 ipad pro models new features include gesture controls wireless pairing charge wirelessly ipad ipad pro 9.7-inch version set record among currently released tablets tested color accuracy screen reflectance peak brightness contrast rating high ambient light smallest color variation however ipad pro 12.9-inch version tested better contrast ratio dark despite apple advertising tablets pc replacements reviewers noted could replace laptop running microsoft windows macos linux desktop operating systems current operating system scott stein cnet praised faster processor new accessories available however criticized cost unit accessories noting slightly slower processor less ram compared larger 12.9-inch model matt swider techradar complimented easy handling large 256gb configuration true tone display upset high starting price gareth beavis gave positive review commending expansive screen audio quality stated battery life could made longer max parker trustedreviews gareth beavis techradar praised 10.5-inch model high-quality audio performance though critics noted expensive reviewing 12.9 inch second-generation ipad pro lauren goode verge complimented quality camera a10x processor large screen size argued device could cheaper third generation ipad pro models praised better displays slimmed bezels general speed well cpu improvements ben sin forbes noted although screen still lcd screen 120 hz refresh rate makes feel smooth switch usb-c connectors received mixed reviews external monitor support device charging added cost extra dongles use older cables headphones reviewers noted although hardware updates great steps forward ios limitations including lack external storage capabilities prevents third generation competing computers high prices also criticized upcoming ipados address lack external storage supported ipads moreover body criticized ability bend break easily users forum boards reported ipad bending days use carrying around backpack youtuber zack nelson published video channel jerryrigeverything showing device cracking snapping half applying small amount pressure hands center device nelson concluded two weakest points right dead center either side ipad pro crack happened poorly placed microphone hole new apple pencil 2 charging duct reports devices already bent right box devices cellular models also surfaced apple responded reports quickly asserting normal non-issue response criticized according apple bending byproduct new manufacturing process apple added support page relating issues
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Operating systems
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unit generator unit generators ugens basic formal units many music-n-style computer music programming languages sometimes called opcodes particularly csound though expression accurate machine-level instructions unit generators form building blocks designing synthesis signal processing algorithms software example simple unit generator called osc could generate sinusoidal waveform specific frequency given input argument function class represents unit generator env could unit generator delineates breakpoint function thus env could used drive amplitude envelope oscillator osc equation osc*env unit generators often use predefined arrays values functions filled waveforms shapes calling specific generator function unit generator theory sound synthesis first developed implemented max mathews colleagues bell labs 1950s supercollider language .ar method sinosc class ugen generates sine wave example makes sine wave frequency 440 phase 0 amplitude 0.5
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Programming language topics
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twinge attack internet-based computer-networking twinge attack flood false icmp packets attempt cripple system attack spoofed random fake internet source addresses used makes difficult identify attacker idea attack either degrade performance attacked computer make crash attacking program called twinge icmp packets particular signature gives identity away long computer safely behind router firewall nothing worry attack attack used compromise system steal information simply annoyance easy way avoid attack set router firewall ignore icmp ping packets internet
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Computer security
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backup software backup software computer programs used perform backup create supplementary exact copies files databases entire computers programs may later use supplementary copies restore original contents event data loss hence 're useful users several features backup software make effective backing data voluming allows ability compress split backup data separate parts storage smaller removable media cds often used cds easy transport off-site inexpensive compared hard drives servers however recent increase hard drive capacity decrease drive cost made voluming far less popular solution introduction small portable durable usb drives increase broadband capacity provided easier secure methods transporting backup data off-site since hard drive space cost compressing data reduce size allowing less drive space used save money many backup solutions offer plug-in access exclusive use locked files backup solutions generally support differential backups incremental backups addition full backups material newer changed compared backed data actually backed effect increase significantly speed backup process slow networks decreasing space requirements backup schedules usually supported reduce maintenance backup tool increase reliability backups prevent data theft backup software offers cryptography features protect backup prevent loss previously backed data backup backup software e.g areca backup argentum backup offer transaction mechanism commit rollback management critical processes backups merges guarantee backups integrity
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Computer security
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winter games winter games sports video game developed epyx released europe u.s. gold based sports featured winter olympic games snow-and-ice themed follow-up highly successful summer games winter games released 1985 commodore 64 later ported several popular home computers video game consoles 1980s game presented virtual multi-sport carnival called epyx winter games official ioc licensing place 8 players choosing country represent taking turns competing various events try medal events available vary slightly depending platform include following game allowed compete events sequentially choose events choose one event practice event winter games ported amiga apple ii atari st apple macintosh apple ii amstrad cpc zx spectrum dos computer platforms atari 2600 atari 7800 nintendo entertainment system family computer disk system video game consoles 2004 featured one games c64 direct-to-tv virtual console version released europe february 20 2009 winter games epyx best-selling commodore game late 1987 sales surpassed 250,000 copies november 1989 info rated winter games four-plus stars five stating event good enough sold separately concluding sports simulation best 1985 zzap 64 gave 94 game calling another classic sport simulation epyx lemon64 website users given average vote 8.6 places game top 20 list site game reviewed 1988 dragon 132 hartley patricia kirk lesser role computers column reviewers gave game 3½ 5 stars spectrum version topped charts month april however nes famicom disk system versions critically panned unresponsive controls abysmal music poor graphics
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Computer architecture
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ancient unix ancient unix term coined santa cruz operation describe early releases unix code base released prior unix system iii particularly research unix releases prior including version 7 base unix/32v well later developments unix publication lions book work undertaken release earlier versions codebase sco first released code limited educational license later january 2002 caldera international sco group relicensed made available several versions four-clause bsd license namely far widespread use code used emulator systems version 5 unix made run nintendo game boy advance using simh pdp-11 emulator version 6 unix provided basis mit xv6 teaching system update version ansi c x86 platform example relicensing old unix code bases affected modern computing community bsd vi text editor based code ed line editor early unixes therefore traditional vi could distributed freely various work-alikes nvi created code longer encumbered traditional vi adapted modern unix-like operating systems sco group inc. previously called caldera international result sco group inc. v. novell inc. case novell inc. found transferred copyrights unix sco group inc concerns raised regarding validity caldera license suggesting may valid
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Operating systems
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test x86 instruction x86 assembly language codice_1 instruction performs bitwise two operands flags codice_2 codice_3 codice_4 modified result discarded codice_5 codice_6 flags set codice_7 codice_8 flag undefined 9 different opcodes test instruction depending type size operands compare 8-bit 16-bit 32-bit 64-bit values also compare registers immediate values register indirect values test operation sets flags codice_6 codice_5 zero codice_2 set significant bit result result codice_7 codice_3 set codice_14 otherwise set codice_7 parity flag set bitwise xnor least significant byte result codice_14 number ones byte even codice_7 otherwise value codice_8 undefined
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Computer architecture
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web compatibility test mobile browsers web compatibility test mobile browsers often mobile acid test test page published promoted world wide web consortium w3c expose web page rendering flaws mobile web browsers applications render html developed spirit acid test web standards project test relevant parts mobile browser need support test uses parts javascript test different technologies browser accomplish 16 different subtest indicated 4 x 4 raster squares mobile acid test tests variety web standards published world wide web consortium internet engineering task force specifically mobile acid test tests
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Web technology
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system management interface tool system management interface tool smit menu-based management tool ibm aix operating system allows user navigate menu hierarchy commands rather using command line
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Operating systems
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hp management software hp management software family enterprise software products micro focus result spin-merge hewlett packard enterprise software assets micro focus 2017 division formerly owned hewlett packard enterprise following separation hewlett-packard hp inc. hewlett packard enterprise 2015 management software family technology helps companies manage infrastructures people processes required reap greatest amount responsiveness effectiveness today multi-layered highly complex data centers beginning september 2005 hp purchased several software companies part publicized deliberate strategy augment catalog management software offerings large business customers according zdnet idc hp world sixth largest software company hp management software largest category software sold hp software division concept behind management software needs support business run business rather cost center discipline includes software help businesses manage portfolio assets gain greater quality govern processes improve security name according computerworld management software designed help businesses align spend resources based business priorities companies develop sell management software include ibm bmc software borland ca compuware micro focus sells several categories software including business service management software application lifecycle management software mobile apps big data analytics service portfolio management software automation orchestration software enterprise security software micro focus also provides software service saas cloud computing solutions software services including consulting education professional services support information see micro focus hp software division vivit worldwide independent hp software community designed help members develop expertise careers education community advocacy programs almost two decades vivit independent unbiased trusted field-tested community thousands hp software customers developers partners areas world business industry vivit membership free actual user group itrc online forum hp software solutions products new hp user group hp software solutions community officially launched publicly april 2010 includes number former software-related communities june 2011 hp software announced new discover performance community online resource center designed serve executives cios
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Distributed computing architecture
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yuji matsumoto 1979 got bachelor degree information science kyoto university received master place two year later ended ph.d. 1990 1984 1985 became visiting professor imperial college science technology department university london 1985 1987 deputy chief institute new generation computer technology 1988 1989 served associated professor data processing center division kyoto university next year position place worked department electrical engineering 1993 became professor nara institute science technology 1988 became takahashi incentive award recipient 1989 awarded motooka commemorative award 1994 received astem software award three years later became recipient best paper award information processing society japan following best author award place 2000 acceptance fellowship 2006 2002 2004 annually awarded best presentation association natural language processing 2005 awarded best paper award japanese society artificial intelligence received one next year dews two year later jsai awarded achievement award 2011 named fellow association computational linguistics
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Computational linguistics
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xbox one system software xbox one system software sometimes called xbox os operating system eighth-generation home video game console xbox one microsoft windows-based operating system using hyper-v virtual machine monitor contains separate operating systems games applications run console located internal hdd day-to-day usage also duplicated internal nand storage console recovery purposes factory reset functionality xbox one allows users download applications add functionality dashboard june 2014 onwards entertainment apps longer required user signed valid xbox live gold account order use features advertised given app since launch microsoft updating os monthly updates downloaded xbox live service directly xbox one subsequently installed using offline recovery images downloaded via pc november 2015 major system update known new xbox one experience released brought significant changes design functionality system windows 10-based core replaced windows 8-based one update new system sometimes referred windows 10 xbox one xbox one console runs operating system includes windows 10 core although initially included windows 8 core xbox one release xbox one system software contains heavily modified hyper-v hypervisor known nanovisor host os two partitions one partitions exclusive partition custom virtual machine vm games partition shared partition custom vm running multiple apps shared partition contained windows 8 core launch november 2015 via system update known new xbox one experience upgraded windows 10 core windows 10 universal windows platform apps became available xbox one according current head microsoft gaming division phil spencer importance entertainment games windows ecosystem become really prevalent company program microsoft launched allows developers build single app run wide variety devices including personal computers xbox one video game consoles according polygon microsoft removed distinction xbox one windows pc starting february 2014 microsoft invited select users join preview program enables receive early builds upcoming system updates experiment features prior public launch software registered xbox one preview program participants test early features included update provide feedback private forum opt future waves xbox feedback website microsoft soliciting input consumers features taking requests future additions console low battery notifications blu-ray 3d support two examples ideas among top vote-getters site xbox one system software interface uses geometrical placement squares rectangular items scrolls continuous horizontal line using metro design language also seen windows 8 windows 10 microsoft products dashboard divided home community oneguide store sections home section contains recent apps games list shortcuts pinned apps games community section allows users view friends in-game activities captures post status updates well view trending content oneguide section aggregates television online video content store section serves portal games video music app marketplaces general top level menu xbox one feels lot less cluttered xbox 360 dashboard example friends tab removed replaced dedicated app users load see connections couple columns settings options area pinned favorites main screen showing current recent apps games user played used small new section highlighting recently added content total interface clean sparse microsoft also introduced new way multitask called snap allows xbox one users open multiple panes single window microsoft upgraded windows 8-based core windows 10-based one made tour new user interface xbox wire promising faster easier navigation improved community features return xbox avatars main feature home screen list recently played games selecting given title give users information announcements achievements social activity forth also focused actual games playing part parcel company ’ new direction phil spencer current head microsoft xbox division like video game consoles xbox one primarily designed playing games game console entertainment hub games television music videos mainly console focuses functionality entertainment whole gamescom 2014 microsoft unveiled new plan remedy make earnest xbox one ’ label all-in-one entertainment solution way expanding media support xbox one media player quite similar xbox 360 playback suite terms form function however newer console supports 30 formats including mkv container gif files xbox one console also unique things example owners control television broadcasts using device well use functioning dvr apart streaming music videos via play charms devices play also networked approach two primary ways first stream media computer tablet second play directly usb flash drive advantage method play system users wherever sit via xbox one instead sending video pc console aside multimedia files xbox one plays cds dvds blu-ray discs also comes dlna mkv support means downloaded video files streamed via pc transported via external hard drive usbs meanwhile interactive tv guide allows users turn control television voice furthermore system comes comprehensive range applications related multimedia features united states video channels include example amazon instant video crackle hulu plus netflix microsoft announced xbox one awarded multimedia capabilities 66th annual technology engineering emmy awards early 2015 prize given xbox one television-on-demand functions xbox one backward compatible either original xbox xbox 360 console launch microsoft admitted attempts use cloud streaming allow xbox 360 games played xbox one proved problematic however e3 press conference june 15 2015 microsoft announced plans introduce xbox 360 backward compatibility using software method xbox one supported xbox 360 games supposed run within software emulator provided updated system software implementing hardware software xbox 360 xbox one recording broadcasting features supported along xbox 360 multiplayer achievements cloud save access unlike xbox 360 emulation original xbox games specifically patched need repackaged xbox one format users digitally-purchased games automatically appear library download available games physical media executed directly disc inserting disc initiates download repackaged version xbox one titles disc must inserted play validation purposes least 100 xbox 360 games officially supported available feature public launch alongside november 2015 new xbox one experience system update xbox one preview program members received early access limited number titles upon announcement microsoft expected number supported games increase significantly time xbox 360 games supported—this explicitly includes games require kinect access usb peripherals xbox division head phil spencer stated idea possibly adding support games original xbox silly xbox division focusing xbox 360 compatibility first june 11 2017 microsoft announced would backwards compatibility original xbox june 10 2019 microsoft announced wound bring addition new titles program order focus backward compatibility efforts project scarlett 2016 build conference announced xbox one consoles could updated include development kit universal windows applications xbox one official support platform cortana coming summer 2016 along introducing improvements fixes native console apps software monthly updates xbox one system software introduce major features voted requested community though months included one update starting february 2014 beta releases updates tested going live check unwanted bugs stability day console launch 2013 system update released remove controversial always-online drm announced electronic entertainment expo 2013 drm would required xbox one connect internet least every twenty-four hours else games would cease function wave backlash gamers press alike microsoft forced reverse policies regarding early users go online least receive patch february 2014 update introduced ability see much hard disk space available also introduced support usb keyboards enabling users plug keyboard console thus eliminating need use on-screen keyboard year later july 2015 phil spencer head xbox team vowed mouse support would added sometime future part cross-platform gameplay windows 10 devices xbox one console march 2014 update added support video output 50 frames per second rather 60 allowing smoother video 50 hz displays common europe united states refresh rates screens higher 60 hz europe june 2014 support added external hard drives 256 gigabytes allowing two connected console time via usb 3.0 part july 2014 update consoles could better understand voice commands spoken different accents dialects english german month later purchases official xbox website smartglass app enabled allowing easier content purchasing october 2014 update media player app added support many formats codecs including matroska container well dlna streaming networked devices march 2015 new screenshot feature added console along tile transparency allowing owners share game screenshots online use one menu background april 2015 due criticisms power consumption needed instant-on feature system update prompted users select instant-on energy saving mode instant-on enabled default u.s. drawing criticism natural resources defense council electronic entertainment expo 2015 june microsoft discussed three major features later came xbox one consoles november 2015 windows 10 streaming xbox 360 backward compatibility interface redesign known new xbox one experience advance public release windows 10 july 2015 update let users stream games xbox one device running windows 10 feature announced january 2015 service streams one device time february 2016 update slew new features became available example global leaderboards game ability hide unused expired beta games demos user game collection february 2016 update allowed users rearrange customized 'pins via controller whereas previously users use xbox one smartglass application use feature march 2016 update builds features introduced february 2016 update new features included march 2016 update ability purchase xbox 360 compatible games xbox one party chat broadcasting twitch streams customizable dvr recording lengths means owners record clip 5 minutes long improvements included ability track achievement progress xbox one guide video playback xbox one activity feed ability 16 people party chat ability track xbox 360 achievements xbox one activity feed improvements march 2016 update include ability launch web links youtube videos directly game hubs ability user compare avatars friends additionally update also introduces ability factory reset console without deleting installed games applications june 6 2016 first preview update windows 10 anniversary update made available participants preview program included many new features enhancements software build 14352 one first builds introduce cortana main aim help users undertake certain tasks setting party using voice commands unlike older kinect voice commands cortana gives users audio feedback commands similar pc windows mobile versions update also included refreshed design xbox store cementing relationship xbox one windows 10 pcs well redesigned 'my games apps interface includes vertical design rather older horizontal design 'my games apps interface build 14352 also gives user information downloading games apps percentage completed current download size total download size current download speed june 2016 update also includes new 'facebook friend finder allows users find add friends facebook xbox live final release public published july 30 2016 coincide release windows 10 anniversary update released days later august 2 2016 final release introduced newly redesigned universal store well integration universal windows platform march 29 2017 update released public known creators update coincide pc version released weeks later april 6 2017 released xbox insiders late february 2017 testing evaluation creators update featured number updates including refreshed homepage design new guide design new video screenshot capture controls well new game streaming service called beam accessibility also improved new feature called microsoft co-pilot allows users physical impairments 'hook second controller allow friend assist controls tapping xbox guide button longer takes user back home screen instead opens guide represents significant design paradigm shift compared older releases october 16 2017 fall update released major changes include ui overhaul using microsoft fluent design system modular home menu faster dashboard content transfer feature support usb webcams new guide menu improvements game dvr several miscellaneous functionality interface tweaks april 24 2018 april xbox update released changes include new video features auto low-latency mode support variable refresh rate output amd radeon freesync freesync 2 compatible displays addition xbox one x xbox one support output 2560 x 1440 1440p resolution games media improvements mixer share controller option start mixer broadcasts anywhere xbox one share captured screenshots clips directly twitter several audio improvements community tournaments available directly game hubs supported games club feeds also gained new filters may 18 2018 may xbox update released changes include support 120hz refresh rate powerful new enhancement pins called “ groups ” users create multiple collections content made anything within games apps trim recent game captures directly guide improved family settings improvements xbox accessories app several changes button commands throughout dashboard additionally then-forthcoming update added captive portal support console allowing users connect wireless networks requiring authentication commonly used colleges hotels well wireless hotspots provided internet service providers microsoft aims release frequent updates xbox one console mainly containing new improved features faster installation loading times games apps largest november 2015 named new xbox experience update gaming platforms microsoft gaming platforms generation gaming platforms seventh generation
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Operating systems
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quakec quakec interpreted language developed 1996 john carmack id software program parts video game quake using quakec programmer able customize quake great extents adding weapons changing game logic physics programming complex scenarios used control many aspects game parts ai triggers changes level quake engine game engine use quakec following engines used dll game modules customization written c c++ id tech 4 quakec source original id software quake game logic published 1996 used basis modifications like capture flag others quakec source code compiled using tool called qcc bytecode kept file called progs.dat programmers quake modifications could publish progs.dat bytecode without revealing source code quake mods published way quakec allowed quake engine dominate direction first-person shooter genre thanks carmack idea extending video game life adding unlimited expandability extensibility already played big role doom enormous internet community gamers programmers alike arisen many modern multiplayer games extensible form quakec known interpreted quake runs continually interpreting progs.dat file syntax quakec based c programming language explaining name support implementation new types structures arrays kind referencing entity type always reference quakec also suffers fact many built-in functions functions prototyped quakec code actually defined within game engine written c return strings temporary string buffer hold one string given time words construct fail second call codice_2 converts floating-point value string overwrites string returned first call somefunction something quakec contain string handling functions file handling functions simply needed original game video games time game logic written plain c/c++ compiled executable faster however makes harder community create mods makes process porting game another platform gnu/linux costly despite advantages choice implementing game logic using custom scripting language interpreter dropped next generation quake ii engine favor compiled c code due overall inflexibility quakec increasingly complex game logic performance gained packaging game logic native dynamic link library advantage leveraging already established programming language community tools educational materials documentation distributing native code created new security portability concerns quakec bytecode afforded little opportunity mischief native code access whole machine quakec bytecode also worked machine could run quake compiling native code added additional barrier entry novice mod developers asked set complicated programming environment eventual solution implemented quake iii engine combine advantages original quakec advantages compiling c native code lcc c compiler extended compile standard c bytecode could interpreted virtual machine manner similar quakec addressed security portability tool chain problems lost performance advantage native code solved compiling bytecode native code run time supported machines id software released source codice_3 quakec compiler along original quakec code 1996 modified versions soon sprung including jonathan roy codice_4 ryan frikac smith frikqcc added functionality optimizations compiling speed boosts 1999 id software released code quake engine gnu general public license gpl workings bytecode interpreter examined new quakec compilers released j.p. grossman codice_5 new version frikqcc compilers took advantage newly discovered features backwards-compatible way bytecode could still properly interpreted unmodified quake engines new features include arrays pointers integers loops string manipulation quake engine source code able changed features added quakec form new built-in functions features long yearned quakec coders finally reached realization quakec file string handling functions enlarged string buffers math functions however programmers taking advantage changes lost backwards compatibility unmodified quake engine xonotic since version 0.7 uses gmqcc compiler enhanced quake engines notably darkplaces fteqw support extension regular quakec commonly referred server side quakec ssqc allows client side scripting quake engine especially useful guis huds visually heavy effects need simulated server transferred network
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Programming language topics
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system preferences system preferences application included macos operating system allows users modify various system settings divided separate preference panes system preferences application introduced first version mac os x replace control panel included classic mac os prior mac os x control panel small application enabled user modify software hardware settings sound volume desktop pattern control panels differ extensions allow user specify options whereas extensions provide user interface setting preferences many software distributions extensions provided functionality corresponding control panel provided configuration options release mac os x 2001 users modified system settings using control panels control panels like preference panes found system preferences separate resources cdevs accessed apple menu control panel rudimentary form system preferences dates back 1983 apple lisa preferences menu item included subset configurable settings called convenience settings well settings adapted according programs devices installed lisa office system original control panels earliest versions classic mac os combined one small desk accessory susan kare designed interface original control panel tried make user-friendly possible design used system 3 separate control panel files cdev added accessible solely control panel debut system 7 control panels separated individual small application-like processes accessible finder sub-menu apple menu provided apple menu options mac os 9 last release mac os mac os x included 32 control panels mac os 9 many control panels rewritten true applications mac os x released preference panes replaced control panels preference panes applications loadable bundles system preferences application similar arrangement used system 6 default system preferences organizes preference panes several categories latest version system preferences included mac os x v10.7 categories personal hardware internet wireless system fifth category appears third-party preference panes installed users also choose sort preference panes alphabetically system preferences originally included customizable toolbar frequently-used preference pane icons could dragged removed mac os x v10.4 replaced static toolbar featured back forward navigation buttons search field apple added new preference panes major features added operating system occasionally merges multiple panes one exposé introduced mac os x v10.3 corresponding preference pane added system preferences replaced single dashboard exposé pane mac os x v10.4 introduced dashboard .mac service replaced mobileme corresponding preference pane also renamed control panels included mac os 9 os x mountain lion 10.8 includes following preference panes os x mountain lion universal access pane changed accessibility speech changed dictation speech
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Operating systems
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session web analytics web analytics session visit unit measurement user actions taken within period time regard completion task sessions also used operational analytics provision user-specific recommendations two primary methods used define session time-oriented approaches based continuity user activity navigation-based approaches based continuity chain requested pages definition session varies particularly applied search engines generally session understood consist sequence requests made single end-user visit particular site context search engines sessions query sessions least two definitions session query session may queries made user particular time period may also series queries navigations consistent underlying user need sessions per user used measurement website usage metrics used within research applied web analytics include session length user actions per session session length seen accurate alternative measuring page views reconstructed sessions also used measure total user input including measure number labour hours taken construct wikipedia sessions also used operational analytics data anonymization identifying networking anomalies synthetic workload generation testing servers artificial traffic essential use sessions web analytics able identify known session reconstruction approaches session reconstruction divided two main categories time-oriented navigation-oriented time-oriented approaches session reconstruction look set period user inactivity commonly called inactivity threshold period inactivity reached user assumed left site stopped using browser entirely session ended requests user considered second session common value inactivity threshold 30 minutes sometimes described industry standard argued threshold 30 minutes produces artifacts around naturally long sessions experimented thresholds others simply state time threshold effective identifying sessions one alternative proposed using user-specific thresholds rather single global threshold entire dataset problem assuming thresholds follow bimodal distribution suitable datasets cover long period time navigation-oriented approaches exploit structure websites specifically presence hyperlinks tendency users navigate pages website clicking rather typing full url browser one way identifying sessions looking data build map website user first page identified session actions lasts land page accessed previously-accessed pages takes account backtracking user retrace steps opening new page simpler approach take backtracking account simply require http referer request page already session new session created class heuristics exhibits poor performance websites contain framesets
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Web technology
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palm iiie palm iiie pda palm computing released 1999 briefly expensive advanced palm iiix shared screen palm iiix improved upon palm iii screen featuring new enhanced easier read lcd like previous models offered 2-bit display 4 greyscales palm iiie 2mb ram palm iii 16 mhz motorola dragonball ez cpu said faster efficient 16 mhz motorola dragonball cpu found previous palm models palm iiie featured inverse electroluminescent backlight illuminated screen text instead screen background feature found palm iiix feature area controversy many people disliked many others found improvement like palm iiix palm iiie shipped palm os 3.1 however unlike palm iiix palm iiie upgradeable flash rom instead using permanent rom result palm iiie operating system upgrade path palm iiie palm iii series model ship flash rom later special edition iiie device released translucent clear case
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Computer architecture
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digital amps is-54 is-136 second-generation 2g mobile phone systems known digital amps d-amps development north american 1g mobile system advanced mobile phone system amps prevalent throughout americas particularly united states canada since first commercial network deployed 1993 d-amps considered end-of-life existing networks mostly replaced gsm/gprs cdma2000 technologies system often referred tdma name based abbreviation time division multiple access common multiple access technique used 2g standards including gsm well is-54 is-136 however d-amps competing gsm systems based code division multiple access cdma adoption network carriers although phased favor gsm/gprs cdma2000 technology d-amps uses existing amps channels allows smooth transition digital analog systems area capacity increased preceding analog design dividing 30 khz channel pair three time slots hence time division digitally compressing voice data yielding three times call capacity single cell digital system also made calls secure beginning analogue scanners could access digital signals calls encrypted using cmea later found weak is-136 added number features original is-54 specification including text messaging circuit switched data csd improved compression protocol sms csd available part gsm protocol is-136 implemented nearly identical fashion former large is-136 networks including united states rogers wireless canada upgraded existing is-136 networks gsm/gprs rogers wireless removed 1900 mhz is-136 2003 done 800 mhz spectrum equipment failed rogers deactivated is-136 network along amps may 31 2007 soon followed february 2008 shutting tdma amps alltel primarily uses cdma2000 technology acquired tdma network western wireless shut tdma amps networks september 2008 us cellular also primarily uses cdma2000 technology shut tdma network february 2009 is-54 first mobile communication system provision security first employ tdma technology evolution mobile communication began three different geographic regions north america europe japan standards used regions quite independent earliest mobile wireless technologies implemented wholly analogue collectively known 1st generation 1g technologies japan 1g standards nippon telegraph telephone ntt high capacity version hicap early systems used throughout europe compatible meaning later idea common 'european union viewpoint/technological standard absent time various 1g standards use europe included c-netz germany austria comviq sweden nordic mobile telephones/450 nmt450 nmt900 nordic countries nmt-f french version nmt900 radiocom 2000 rc2000 france tacs total access communication system united kingdom italy ireland north american standards advanced mobile phone system amps narrow-band amps n-amps 1g standards successful amps system despite nordic countries cooperation european engineering efforts divided among various standards japanese standards get much attention developed bell labs 1970s first used commercially united states 1983 amps operates 800 mhz band united states widely distributed analog cellular standard 1900 mhz pcs band established 1994 digital operation success amps kick-started mobile age north america market showed increasing demand higher capacity mobility then-existing mobile communication standards capable handling example bell labs system 1970s could carry 12 calls time throughout new york city amps used frequency division multiple access fdma enabled cell site transmit different frequencies allowing many cell sites built near amps also many disadvantages well primarily ability support ever-increasing demand mobile communication usage cell site much capacity carrying higher numbers calls amps also poor security system allowed people steal phone serial code use making illegal calls triggered search capable system quest resulted is-54 first american 2g standard march 1990 north american cellular network incorporated is-54b standard first north american dual mode digital cellular standard standard motorola narrowband amps n-amps analog scheme increased capacity cutting voice channels 30 khz 10 khz is-54 hand increased capacity digital means using tdma protocols method separates calls time placing parts individual conversations frequency one next tdma tripled call capacity using is-54 cellular carrier could convert system analog voice channels digital dual mode phone uses digital channels available defaults regular amps is-54 backward compatible analogue cellular indeed co-existed radio channels amps analogue customers left behind simply could access is-54 new features is-54 also supported authentication help preventing fraud is-54 employs 30 khz channel spacing frequency bands 824-849 869-894 mhz amps capacity increased preceding analog design dividing 30 khz channel pair three time slots digitally compressing voice data yielding three times call capacity single cell digital system also made calls secure analog scanners could access digital signals is-54 standard specifies 84 control channels 42 shared amps maintain compatibility existing amps cellular telephone system primary forward reverse control channels is-54 cellular systems use signaling techniques modulation scheme binary fsk amps amps/is-54 infrastructure support use either analog amps phones d-amps phones access method used is-54 time division multiple access tdma first u.s. digital standard developed adopted tia 1992 tdma subdivides 30 khz amps channels three full-rate tdma channels capable supporting single voice call later full-rate channels sub-divided two half-rate channels necessary coding compression could also support voice call thus tdma could provide three six times capacity amps traffic channels tdma initially defined is-54 standard specified is-13x series specifications eia/tia channel transmission bit rate digitally modulating carrier 48.6 kbit/s frame six time slots 6.67-ms duration time slot carries 324 bits information 260 bits 13-kbit/s full-rate traffic data 64 bits overhead 28 synchronization contain specific bit sequence known receivers establish frame alignment also gsm known sequence acts training pattern initialize adaptive equalizer is-54 system different synchronization sequences six time slots making frame thereby allowing receiver synchronize preassigned time slots additional 12 bits every time slot sacch i.e system control information digital verification color code dvcc equivalent supervisory audio tone used amps system 256 different 8-bit color codes protected 12 8 3 hamming code base station preassigned color code incoming interfering signals distant cells ignored modulation scheme is-54 7c/4 differential quaternary phase shift keying dqpsk otherwise known differential 7t/4 4-psk π/4 dqpsk technique allows bit rate 48.6 kbit/s 30 khz channel spacing give bandwidth efficiency 1.62 bit/s/hz value 20 better gsm major disadvantage type linear modulation method power inefficiency translates heavier hand-held portable even inconvenient shorter time battery recharges conversation data bits makes data field six slots make complete is-54 frame data slots 1 4 2 5 3 6 make voice circuit dvcc stands digital verification color code arcane terminology unique 8-bit code value assigned cell g means guard time period time slot rsvd stands reserved sync represents synchronization critical tdma data field slot every frame must synchronized others master clock everything work time slots mobile-to-base direction constructed differently base-to-mobile direction essentially carry information arranged differently notice mobile-to-base direction 6-bit ramp time enable transmitter time get full power 6-bit guard band nothing transmitted 12 extra bits base-to-mobile direction reserved future use call comes mobile switches different pair frequencies voice radio channel system carrier made analog digital pair carries call is-54 signal detected gets assigned digital traffic channel one available fast associated channel facch performs handoffs call need mobile go back control channel case high noise facch embedded within digital traffic channel overrides voice payload degrading speech quality convey control information purpose maintain connectivity slow associated control channel sacch perform handoffs conveys things like signal strength information base station is-54 speech coder uses technique called vector sum excited linear prediction vselp coding special type speech coder within large class known code-excited linear prediction celp coders speech coding rate 7.95 kbit/s achieves reconstructed speech quality similar analog amps system using frequency modulation 7.95-kbit/s signal passed channel coder loads bit rate 13 kbit/s new half-rate coding standard reduces overall bit rate call 6.5 kbit/s provide comparable quality 13-kbit/s rate half-rate gives channel capacity six times analog amps discussion communication system complete without explanation system example dual-mode cellular phone specified is-54 standard explained dual-mode phone capable operating analog-only cell dual-mode cell transmitter receiver support analog fm digital time division multiple access tdma schemes digital transmission preferred cellular system digital capability mobile unit assigned digital channel first digital channels available cellular system assign analog channel transmitter converts audio signal radio frequency rf receiver converts rf signal audio signal antenna focuses converts rf energy reception transmission free space control panel serves input/output mechanism end user supports keypad display microphone speaker coordinator synchronizes transmission receives functions mobile unit dual-mode cellular phone consists following 1993 american cellular running capacity despite wide movement is-54 american cellular business continued booming subscribers grew one half million customers 1988 thirteen million subscribers 1993 room existed technologies cater growing market technologies followed is-54 stuck digital backbone laid pragmatic effort launched improve is-54 eventually added extra channel is-54 hybrid design unlike is-54 is-136 utilizes time division multiplexing voice control channel transmissions digital control channel allows residential in-building coverage dramatically increased battery standby time several messaging applications air activation expanded data applications is-136 systems needed support millions amps phones designed manufactured is-54 is-136 considered is-136 added number features original is-54 specification including text messaging circuit switched data csd improved compression protocol is-136 tdma traffic channels use π/4-dqpsk modulation 24.3-kilobaud channel rate gives effective 48.6 kbit/s data rate across six time slots comprising one frame 30 khz channel mobility largest us carrier support d-amps refers tdma turned existing network order release spectrum gsm umts platforms 19 wireless markets started may 30 2007 areas followed june july tdma network markets operated 1900 mhz frequency coexist amps network service remaining 850 mhz tdma markets discontinued along amps service february 18 2008 except areas service provided dobson communications dobson tdma amps network shut march 1 2008 may 31 2007 rogers wireless decommissioned d-amps amps networks moved remaining customers older networks onto gsm network alltel completed shutdown d-amps amps networks september 2008 last carrier united states operate d-amps network u.s. cellular shut d-amps network february 2009
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Internet protocols
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google url shortener google url shortener also known goo.gl discontinued url shortening service offered google launched december 2009 initially used google toolbar feedburner later google launched separate website goo.gl opened public september 2010 user could access list urls shortened past logging google account user could see additional details via details link next shortened url public real-time analytics data including traffic time top referrers visitor profiles could found security google added automatic spam detection based type filtering technology used gmail service accepting new users since april 13 2018 google discontinued service existing users march 30 2019 links previously created still redirect previous destination succeeded firebase dynamic links existing links wo n't become dynamic links automatically
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Web technology
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list grid computing middleware distribution grid middleware distribution software stack set cooperating components services protocols enable users access distributed resources grid
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Distributed computing architecture
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pointer swizzling computer science pointer swizzling conversion references based name position direct pointer references typically performed deserialization loading relocatable object disk executable file pointer-based data structure reverse operation replacing pointers position-independent symbols positions sometimes referred unswizzling performed serialization saving example suppose following linked list data structure easily create linked list data structure memory using object attempt save disk run trouble directly saving pointer values wo n't work architectures nodes almost certainly loaded different memory positions one way dealing assign unique id number node unswizzle pointers turning field indicating id number next node save records disk order information lost options include saving file offset next node number indicating position sequence saved records go load nodes however quickly discover attempting find node based number cumbersome inefficient 'd like original data structure back simply follow next pointers traverse list perform pointer swizzling finding address node turning id_number_of_next_node fields back direct pointers right node potentially unlimited number forms pointer unswizzled popular include security methods must implemented great deal caution particular attacker presentation specially crafted file may allow access addresses outside expected proper bounds systems weak memory protection lead exposure confidential data modification code likely executed system implement guards execution data system may severely compromised installation various kinds malware methods protection include verifications prior releasing data application swizzling general case complicated reference graph pointers might contain arbitrary number cycles complicates maintaining mapping old unswizzled values new addresses associative arrays useful maintaining mapping algorithms breadth-first search help traverse graph although require extra storage various serialization libraries provide general swizzling systems many cases however swizzling performed simplifying assumptions tree list structure references different types swizzling
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Operating systems
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list rockchip products list rockchip products rk3399 flagship soc rockchip dual a72 quad a53 mali-t860mp4 gpu providing high computing multi-media performance rich interfaces peripherals software supports multiple apis opengl es 3.2 vulkan 1.0 opencl 1.1/1.2 openvx1.0 ai interfaces support tensorflow lite/androidnn api rk3399 linux source code hardware documents github wiki opensource website rk3288 high performance iot platform quad-core cortex-a17 cpu mali-t760mp4 gpu 4k video decoding 4k display applied products various industries including vending machine commercial display medical equipment gaming intelligent pos interactive printer robot industrial computer rk3288 linux source code hardware documents github wiki opensource website rk3326 px30 newly announced 2018 designed smart ai solutions px30 variant rk3326 targeting iot market supporting dual vop arm new generation cpu cortex-a35 gpu g31 rk3308 another newly released chipset targeting smart ai solutions entry-level chipset aimed mainstream devices chip multiple audio input interfaces greater energy efficiency featuring embedded vad voice activation detection announcement rv1108 indicated rockchip moves ai/computer vision territory ceva dsp embedded rv1108 powers smart cameras including 360° video camera ipc drone car camcoder sport dv vr etc also deployed new retail intelligent marketing applications integrated algorithms rk1808 rockchip first chip neural processing unit npu artificial intelligence applications rk1808 specifications include rk3530 rk3530 soc ship q3 2019 targeting set-top box market rk3530 specifications include rv1109 rk3358 rv1109 vision processor soc ship q4 2019 rv1109 specifications include rk3358 high-end soc ship q1 2020 rk3358 specifications include rk26xx series released 2006 rk27xx series rockchip first known rk 27xx series efficient mp3/mp4 decoding integrated many low-cost personal media player pmp products rk28xx series rk2806 targeted pmps rk2808a arm926ej-s derivative along arm core dsp coprocessor included native clock speed 560 mhz arm rates performance arm926ej-s 1.1 dmips/mhz performance rockchip 2808 executing arm instructions therefore 660 dmips roughly 26 speed apple a4 processor dsp coprocessor support real-time decoding 720p video files bitrates 2.5 mbit/s chip core many android windows mobile-based mobile internet devices.. rk2816 targeted pmp devices mids specifications rk2806 also includes hdmi output android support 720p hardware video acceleration rk29xx series rockchip rk291x family socs based arm cortex-a8 cpu core presented first time ces 2011 rk292x single core socs based arm cortex-a9 first introduced 2012 rk2918 first chip decode google webm vp8 hardware uses dynamically configurable companion core process various codecs encodes decodes h.264 1080p decode many standard video formats including xvid h.263 avs mpeg4 rv wmv includes vivante gc800 gpu compatible opengl es 2.0 openvg rk2918 compatible android froyo 2.2 gingerbread 2.3 honeycomb 3.x ice cream sandwich 4.0 unofficial support ubuntu linux flavours exists 2013 targeted e-readers rk2906 basically cost-reduced version rk2918 also targeted e-readers 2013 rockchip rk2926 rk2928 feature single core arm cortex a9 running speed 1.0 ghz replaces vivante gc800 gpu older rk291x series arm mali-400 gpu 2013 rk2926 targeted tablets rk2928 targeted tablets android tv dongles boxes rk30xx series rk3066 high performance dual-core arm cortex-a9 mobile processor similar samsung exynos 4 dual core chip terms performance rk3066 samsung exynos 4210 samsung exynos 4212 2013 targeted tablets android tv dongles boxes popular choice tablets devices since 2012 rk3068 version rk3066 specifically targeted android tv dongles boxes package much smaller rk3066 rk3028 low-cost dual-core arm cortex-a9-based processor clocked 1.0 ghz arm mali-400 gpu pin-compatible rk2928 used kids tablets low-cost android hdmi tv dongles rk3026 updated ultra-low-end dual-core arm cortex-a9-based tablet processor clocked 1.0 ghz arm mali-400 mp2 gpu manufactured 40 nm pin-compatible rk2926 features 1080p h.264 video encoding 1080p decoding multiple formats supporting android 4.4 adopted low-end tablets 2014 rk3036 low-cost dual-core arm cortex-a7-based processor released q4 2014 smart set-top boxes support h.265 video decoding rk3188 first product rk31xx series announced production 2nd quarter 2013 rk3188 features quad-core arm cortex-a9 clocked 1.6 ghz frequency targeted tablets android tv dongles boxes popular choice tablets devices requiring good performance rk3188t lower-clocked version rk3188 cpu cores running maximum speed 1.4 ghz instead 1.6 ghz mali-400mp4 gpu also clocked lower speed early 2014 many devices advertised using rk3188 maximum clock speed 1.6 ghz actually rk3188t clock speed limited 1.4 ghz operating system roms specifically made rk3188 may work correctly rk3188t rk3168 first shown april 2013 dual-core cortex a9-based cpu also manufactured using 28 nm process targeted low-end tablets chip seen limited use may 2014 rk3126 entry-level tablet processor introduced q4 2014 manufactured using 40 nm process features quad-core cortex-a7 cpu 1.3 ghz mali-400 mp2 gpu pin-compatible rk3026 rk2926 rk3128 higher-end variant rk3126 also introduced q4 2014 features integrated external interfaces including cvbs hdmi ethernet mac s/pdif audio dac usb targets fully featured tablets set-top boxes rockchip announced rk3288 production second quarter 2014 recent information suggests chip uses quad-core arm cortex-a17 cpu although technically arm cortex-a12 october 1 2014 arm decided also refer cortex-a17 latest production version cortex-a12 performs similar performance level cortex-a17 early reports including rockchip first suggested summer 2013 rk3288 originally designed using quad-core arm cortex-a12 configuration rockchip primary foundry partner globalfoundries announced partnership arm optimize arm cortex-a12 28 nm-slp process process used earlier rockchip chips rk3188 matches choice cortex-a12 cores design rk3288 january 2014 official marketing materials listed cpu cores arm cortex-a17 ces electronics show january 2014 someone apparently corrected cpu specification arm cortex-a12 instead cortex-a17 one panels show booth however since official specifications rockchip website marketing materials well specifications used device manufacturers continued describe cpu quad-core arm cortex-a17 recent testing early rk3288-based tv boxes august/september 2014 provided evidence rk3288 technically contains cortex-a12 cores since arm 0xc0d cpu archtitecture reported cpu-z android reference cortex-a12 original cortex-a17 referred arm 0xc0e however arm community website arm clarified situation october 1 2014 saying cortex-a12 rockchip one known customers called cortex-a17 references cortex-a12 removed arm website arm explained latest production revision cortex-a12 performs close level cortex-a17 improvements cortex-a17 also applied latest version cortex-a12 way rockchip gets official blessing arm listing cores inside rk3288 cortex-a17 first android tv stick based rk3288 launched november 2014 zero devices z5c thinko rockchip announced first member rk33xx family ces show january 2015 rk3368 soc targeting tablets media boxes featuring 64-bit octa-core cortex-a53 cpu opengl es 3.1-class gpu rk3399 announced arm mobile world congress february 2016 features six 64 bit cpu cores including 2 cortex-a72 4 cortex-a53 consumer devices include rockchip provides open source software github maintains wiki linux sdk website offer free downloads soc hardware documents software development resources well third-party development kits info chipsets available rk3399 rk3288 rk3328 rk3036 market socs tablets rockchip faces competition allwinner technology mediatek intel actions semiconductor spreadtrum leadcore technology samsung semiconductor qualcomm broadcom via technologies amlogic establishing position early developing chinese tablet soc market 2012 faced challenge allwinner 2012 rockchip shipped 10.5 million tablet processors compared 27.5 million allwinner however q3 2013 rockchip forecast ship 6 million tablet-use application processors china compared 7 million allwinner mainly shipped single-core products rockchip reported number one supplier tablet-use application processors china q4 2013 q1 2014 q2 2014 chinese soc suppliers cellular baseband technology disadvantage compared companies mediatek also supply smartphone market white-box tablet makers increasingly add phone cellular data functionality products intel corporation made investments tablet processor market heavily subsidizing entry low-cost tablet market 2014 may 2014 intel announced agreement rockchip jointly deliver intel-branded mobile soc platform based intel atom processor 3g modem technology terms agreement two companies deliver intel-branded mobile soc platform quad-core platform based intel atom processor core integrated intel 3g modem technology expected available first half 2015 intel rockchip sell new part oems odms primarily company existing customer base october 2014 rockchip already offering intel xmm 6321 low-end smartphones two chips dual-core application processor either intel processor cores arm cortex-a5 cores integrated modem xg632 integrated rf chip ag620 originates cellular chip division infineon technologies intel acquired time ago application processor may also originate infineon intel rockchip earlier targeted smartphone space material way
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Computer architecture
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clearinghouse networked information discovery retrieval clearinghouse networked information discovery retrieval cnidr organization funded u.s. national science foundation 1993 1997 based microelectronics center north carolina mcnc research triangle park cnidr active research development open source software open standards centered information discovery retrieval emerging internet among software developed cnidr isite open source z39.50 implementation successor free version wais isearch open source text retrieval system cnidr staff involved development open standards internet engineering task force z39.50 implementors group dublin core cnidr collaborated u.s. patent trademark office uspto develop uspto first internet-based patent search systems one provided full text searching images medical patents related research treatment hiv/aids issued us japanese european patent offices another system known us patent bibliographic database provided searching front page bibliographic information us patents since 1976
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Internet protocols
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harvard architecture harvard architecture computer architecture physically separate storage signal pathways instructions data term originated harvard mark relay-based computer stored instructions punched tape 24 bits wide data electro-mechanical counters early machines data storage entirely contained within central processing unit provided access instruction storage data programs needed loaded operator processor could initialize today processors implement separate signal pathways performance reasons actually implement modified harvard architecture support tasks like loading program disk storage data executing harvard architecture need make two memories share characteristics particular word width timing implementation technology memory address structure differ systems instructions pre-programmed tasks stored read-only memory data memory generally requires read-write memory systems much instruction memory data memory instruction addresses wider data addresses system pure von neumann architecture instructions data stored memory instructions fetched data path used fetch data means cpu simultaneously read instruction read write data memory computer using harvard architecture cpu read instruction perform data memory access time even without cache harvard architecture computer thus faster given circuit complexity instruction fetches data access contend single memory pathway also harvard architecture machine distinct code data address spaces instruction address zero data address zero instruction address zero might identify twenty-four-bit value data address zero might indicate eight-bit byte part twenty-four-bit value modified harvard architecture machine much like harvard architecture machine relaxes strict separation instruction data still letting cpu concurrently access two memory buses common modification includes separate instruction data caches backed common address space cpu executes cache acts pure harvard machine accessing backing memory acts like von neumann machine code moved around like data powerful technique modification widespread modern processors arm architecture power isa x86 processors sometimes loosely called harvard architecture overlooking fact actually modified another modification provides pathway instruction memory rom flash memory cpu allow words instruction memory treated read-only data technique used microcontrollers including atmel avr allows constant data text strings function tables accessed without first copied data memory preserving scarce power-hungry data memory read/write variables special machine language instructions provided read data instruction memory instruction memory accessed using peripheral interface distinct instructions embed constant data although individual constants two mechanisms substitute recent years speed cpu grown many times comparison access speed main memory care needs taken reduce number times main memory accessed order maintain performance instance every instruction run cpu requires access memory computer gains nothing increased cpu speed—a problem referred memory bound possible make extremely fast memory practical small amounts memory cost power signal routing reasons solution provide small amount fast memory known cpu cache holds recently accessed data long data cpu needs cache performance much higher cpu get data main memory modern high performance cpu chip designs incorporate aspects harvard von neumann architecture particular split cache version modified harvard architecture common cpu cache memory divided instruction cache data cache harvard architecture used cpu accesses cache case cache miss however data retrieved main memory formally divided separate instruction data sections although may well separate memory controllers used concurrent access ram rom flash memory thus von neumann architecture visible contexts data code come memory controller hardware implementation gains efficiencies harvard architecture cache accesses least main memory accesses addition cpus often write buffers let cpus proceed writes non-cached regions von neumann nature memory visible instructions written data cpu software must ensure caches data instruction write buffer synchronized trying execute just-written instructions principal advantage pure harvard architecture—simultaneous access one memory system—has reduced modified harvard processors using modern cpu cache systems relatively pure harvard architecture machines used mostly applications trade-offs like cost power savings omitting caches outweigh programming penalties featuring distinct code data address spaces even cases common employ special instructions order access program memory though data read-only tables reprogramming processors modified harvard architecture processors
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Computer architecture
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fenix project fenix project codename gnu project create free compiler scripting language derived one created hammer technologies game development suite div games studio however several features added make incompatible games programmed div games studio fenix interpreted language focused 2d video game development main feature inherited div pseudo-parallel programming similar coroutines i.e gives developer chance programming different processes enemies characters etc separately engine synchronize makes video game developing much easier features based simple directmedia layer sdl makes fenix portable project features include full 2d support scaling transparencies blend ops ... 16 bpp color sound .ogg .mod .it .s3m .wav joystick support mode7 extensions via libraries current version 0.92a beta project maintainer currently taking care updating old 0.84 branch — happened quite unstable — retaken splintergu developer argentina cleaned known bugs also gnu default automake/autoconf build system increases portability implemented making easy add support bsd systems fenix although splintergu mainly focused stabilizing 0.84 branch also added new capabilities fenix like better control debug console also making display information fenix 0.8 developers started fenix 2 branch feature completely rewritten core top users game developers may plug required libraries thus increasing flexibility modularity however second effort seems taking long time eta news project given developers might made public soon splintergu publicly showing interest separating fenix core rest interpreter disagreements members community decided fork fenix bennugd continued working bennugd come long way currently much advanced stabilized state current version fenix 0.92a program separated core multiple modules core much improved example optimizing process handling modules tidied many bugfixes done addition improvements language expanded functionality like error handling goto bennu forum quite active bennu wiki good source documentation fenix comes console program several ides around popular fbtwo_project many general-purpose ides easily adapted
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Programming language topics
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colt software colt code orchestra livecoding tool actionscript javascript livecoding tool code orchestra available subscription first version colt released may 2013 time first available livecoding tool actionscript language minor updates included mobile development support using adobe air technology ios android devices version 1.1 included upgraded flex compiler boasting 3x compilation speed increase allowed using compiler bundled application external compiler actionscript ides using external api version 1.2 featured javascript support completely reworked user interface colt separate tool used ide unlike livecoding tools limit user usage specific development environment code/resource routine triggered alteration file within colt project configured paths also provides external api providing methods export project run livecoding sessions production build routines etc ease ide integration prevent application hanging crashing due possible mistypes live code updates colt manages protect running application following potentially dangerous cases version 1.2.2 includes support actionscript javascript programming languages
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Programming language topics
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pal programming language pal pedagogic algorithmic language programming language developed massachusetts institute technology around 1967 help teach programming language semantics design direct descendant iswim owes much philosophy christopher strachey initial implementation pal lisp written peter landin james h. morris jr later redesigned martin richards thomas j. barkalow arthur evans jr. robert m. graham james morris john wozencraft implemented richards barkalow bcpl intermediate-code interpreter ran ibm system/360 called pal/360 rpal right-reference pedagogic algorithmic language functional subset pal implementation sourceforge used university florida teach construction programming languages functional programming programs strictly functional sequence assignment operations
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Programming language topics
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vyatta vyatta subsidiary american telecommunications company provides software-based virtual router virtual firewall vpn products internet protocol networks ipv4 ipv6 free download vyatta available since march 2006 system specialized debian-based linux distribution networking applications quagga openvpn many others standardized management console similar juniper junos cisco ios addition web-based gui traditional linux system commands provides configuration system applications recent versions vyatta web-based management interface supplied subscription edition however functionality available kvm serial console ssh/telnet protocols software runs standard x86-64 servers vyatta also delivered virtual machine file provide vrouter vfirewall vpn functionality xen vmware kvm rackspace softlayer amazon ec2 virtual cloud computing environments october 2012 vyatta also available amazon marketplace purchased service provide vpn cloud bridging network functions users amazon aws services vyatta sells subscription edition includes functionality open source version well graphical user interface access vyatta restful api serial support tacacs+ config sync system image cloning software updates 24x7 phone email technical support training certification vyatta professional available vyatta also offers professional services consulting engagements vyatta system intended replacement cisco ios 1800 asr 1000 series integrated services routers isr asa 5500 security appliances strong emphasis cost flexibility inherent open source linux-based system running commodity x86 hardware vmware esxi microsoft hyper-v citrix xenserver open source xen kvm virtual environments 2012 brocade communications systems acquired vyatta april 2013 brocade renamed product vyatta subscription edition vse brocade vyatta 5400 vrouter latest commercial release brocade vrouter longer open-source based june 2017 brocade sold vyatta software technology communications vyatta vrouter technology still used several actors vrouter market free community vyatta core software vc open source network operating system providing advanced ipv4 ipv6 routing stateful firewalling secure communication ipsec based vpn well ssl based openvpn october 2013 independent group started fork vyatta core name vyos
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Computer security
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cis critical security controls effective cyber defense center internet security critical security controls effective cyber defense publication best practice guidelines computer security project initiated early 2008 response extreme data losses experienced organizations us defense industrial base recently publication initially developed sans institute ownership transferred council cyber security ccs 2013 transferred center internet security cis 2015 earlier known consensus audit guidelines also known cis csc cis 20 ccs csc sans top 20 cag 20 guidelines consist 20 key actions called critical security controls csc organizations take block mitigate known attacks controls designed primarily automated means used implement enforce monitor security controls give no-nonsense actionable recommendations cyber security written language ’ easily understood personnel goals consensus audit guidelines include version 3.0 released april 13 2011 version 5.0 released february 2 2014 council cyber security ccs version 6.0 released october 15 2015 consists security controls version 6.1 released august 31 2016 priorization version 6 version 7 released march 19 2018 version 7.1 released april 4 2019 compared version 5 version 6/6.1 re-prioritized controls changed two controls version 7 controls 3 4 5 reshuffled controls 1-6 considered basic 7-16 foundational 17-20 organizational also released cis ram information security risk assessment method help implement cis controls consensus audit guidelines cag compiled consortium 100 contributors us government agencies commercial forensics experts pen testers authors initial draft include members starting 2009 us department state began supplementing risk scoring program part using consensus audit guidelines according department measurements first year site scoring using approach department reduced overall risk key unclassified network nearly 90 percent overseas sites 89 percent domestic sites
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Computer security
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netrexx netrexx open source originally ibm variant rexx programming language run java virtual machine supports classic rexx syntax reserved keywords along considerable additions support object-oriented programming manner compatible java object model yet used compiled interpreted language option using data types native jvm netrexx runtime package latter offers standard rexx data type combines string processing unlimited precision decimal arithmetic integration jvm platform tight existing java class libraries used unchanged without special setup time java programmer opt use rexx class runtime package improved string handling java syntax source programs netrexx free download rexx language association ibm announced transfer netrexx 3.00 source code rexx language association rexxla june 8 2011 1995 mike cowlishaw ported java os/2 soon started experiment run rexx jvm rexx generally considered first general purpose scripting languages netrexx first alternative language jvm 0.50 release april 1996 contained netrexx runtime classes translator written rexx tokenized turned os/2 executable 1.00 release came available january 1997 contained translator bootstrapped netrexx release 2.00 became available august 2000 major upgrade interpreted execution added mike cowlishaw left ibm march 2010 future ibm netrexx open source unknown ibm finally announced transfer netrexx source code rexx language association rexxla june 8 2011 14 years v1.0 release ibm released netrexx source code rexxla icu license rexxla shortly released netrexx 3.00 followed regular releases latest one 3.07 2018-10-01. icu license approved osi appears variant expat license syntax object model netrexx differ object rexx another ibm object-oriented variant rexx released open source software successor oorexx shares syntactical elements codice_1 codice_2 found classical rexx netrexx written netrexx uses decimal arithmetic rexx specified ansi x3.274
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Operating systems
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fravia fravia spoke six languages including latin degree history early middle ages expert linguistics-related informatics five years made available large quantity material related reverse engineering website also hosted advice reverse engineering experts known reversers provided tutorials essays hack software code well advice related assembly disassembly applications software protection reversing fravia professor high cracking university +hcu founded old red cracker +orc legendary figure reverse engineering conduct research reverse code engineering addition sign front nickname reverser signified membership +hcu website known +fravia pages reverse engineering used challenge programmers well wider society reverse engineer brainwashing corrupt rampant materialism heyday website receiving millions visitors per year influence widespread web presence dates 1995 first got involved research related reverse code engineering rce 2000 changed focus concentrated advanced internet search methods reverse engineering search engine code websites www.fravia.com www.searchlores.org contained large amount specialised information related data mining website www.searchlores.org called useful instrument searching web www.fravia.com site described required reading spy wanting go beyond simple google searches 1980s member esteban canal chess club venice moving ces brussels graduated history university venice 1994 fravia master degree history philosophy 1999 interested studying arts humanities aiming build collective knowledge particular subject learning web-searching art spoke six languages including latin fravia participated speaker 22nd chaos communication congress lecture subject hacking fravia focusing privacy created myth fjalar ravia aka fravia+ msre spini red avenger ~s~ sustrugiel pellet ravia f. protection hostile seekers least two distinct phases internet public work identified first period fravia focused reverse-engineering software protection content copyright software patents steps cracking software protection many cases published website form essays old red cracker lessons fravia asked safety precaution community remove web every copy old site www.fravia.org corresponding period idea convert young crackers ... experiment worked part hence decision couple years ago freeze site nevertheless mirrors still exist fravia website described containing useful tools products according 2001 acm multimedia workshops association computing machinery fravia website contained information could assist hackers certain classification skilled enough mount new novel attack website also analysed brute force attacks steganography period included papers related reality-cracking i.e capacity seeker decode hidden facts behind appearance reverse engineering legitimately bought program studying modifying code knowledge claimed legal fravia least european union restricted conditions transition two phases occurred realizing growing importance internet search engines tools access information according vision access information restricted advocating true openness web information contents strongly criticized large amount advertising internet considered promoting unnecessary products population naive consumers richard stallman web article ubuntu spyware mentions friend fravia alerted fact fravia windows system sent information packet external server detected firewall fravia computer second stage work fravia explained content currently structured world wide web difficulties finding relevant information search engines growing number ads search engines promote today 2005 fravia keynote speaker t2 infosec conference subject speech web bottomless cornucopia immense garbage dump fravia professor high cracking university +hcu founded old red cracker +orc considered genius reverse engineering legendary figure rce advance research reverse code engineering rce addition sign front nickname reverser signified membership +hcu amongst students +hcu top elite windows reversers worldwide +hcu published new reverse engineering problem annually small number respondents best replies qualified undergraduate position university fravia website known +fravia pages reverse engineering used challenge programmers well wider society reverse engineer brainwashing corrupt rampant materialism heyday website received millions visitors per year influence widespread nowadays graduates +hcu migrated linux remained windows reversers information university rediscovered new generation researchers practitioners rce started new research projects field founding cast members first professors denoted symbol +hcu along fravia fravia postings +aesculapius +greythorne technomancer +indian trail +malattia +mammon_ +rezident +sandman fravia described inspiration many hackers reversers friend founder ccc wau holland motivation jon lech johansen understand inner workings computer programs johansen commented blog post fravia site goldmine education reverse engineer later years moved software reversing free software searching web website described meeting point people wanted search web deeper still september 2008 fravia stopped updating site holding conferences diagnosed receiving treatment squamous cell carcinoma tonsil metastasized site frozen half year updated 9 march 2009 fravia slowly recovering focusing gnu/linux fravia died suddenly sunday 3 may 2009 age 56
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Computer security
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china chopper china chopper web shell 4 kilobytes size first discovered 2012 web shell commonly used malicious chinese actors including advanced persistent threat apt groups remotely control web servers web shell two parts client interface executable file receiver host file compromised web server china chopper many commands control features password brute-force attack option code obfuscation file database management graphical user interface originally distributed website www.maicaidao.com fireeye revealed client web shell programmed microsoft visual c++ 6.0 china chopper used attacks eight australian web hosting providers compromised due use unsupported operating system windows server 2008 hackers connected web servers monero mining pool way cryptocurrency miners pool resources mined au 3868 worth monero
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Computer security
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