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jack nipper jack nipper video game gremlin graphics released 1986 zx spectrum commodore 64 amstrad cpc msx followed sequel character loosely based british comic strip character sweeny toddler jack nipper side-view flip screen game puzzle solving platform elements graphics rendered 2d illusion depth achieved allowing characters move forward back within playing area player controls jack naughty child wants break record naughtiness recorded naughtyometer needs carry various wicked pranks unsuspecting inhabitants town comes contact angry adults spanked spanking nappy rash meter increases grows high jack loses life contact monsters ghosts inhabit town also increase nappy rash game went number 2 uk sales charts behind ghosts n'goblins sinclair user described wallyish style reminiscent pyjamarama running wild village searching houses shops gardens objects use create havoc elsewhere environment populated beano -type characters review noted tempting come across well-tended garden happen bottle weed killer ... tin glue false teeth factory ... zx computing praised graphics spectrum version voted number 40 sinclair readers top 100 games time starting april 1987 sinclair magazine published monthly comic strip based character
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Computer architecture
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wdc 65c265 western design center wdc w65c265s microcontroller complete fully static 16-bit computer fabricated single chip using hi-rel low power cmos process w65c265s complements established growing line 65xx products wide range microcomputer applications w65c265s developed hi-rel applications minimum power required w65c265s consists w65c816s static central processing unit cpu 8 kb read memory rom 576 bytes random access memory ram processor defined cache software control eight 16-bit timers maskable interrupts high performance interrupt-driven parallel interface bus pib four universal asynchronous receivers transmitters uart baud rate timers monitor watch dog timer restart interrupt twenty-nine priority encoded interrupts built-in emulation features time day tod clock features twin tone generators tgx bus control register bcr external memory bus control interface circuitry peripheral devices abort input low cost virtual memory interface many low power features innovative architecture demonstrated high performance w65c265s cpu well instruction simplicity result system cost-effectiveness wide range computational power
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Computer architecture
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yellowdog yellowdog limited uk software company headquartered bristol yellowdog hybrid multi-cloud management platform intelligent predictive analytics company currently applications two industries 3d rendering media entertainment batch processing financial services company vision creating world people create discover unleashed limited computing power yellowdog founded gareth williams january 2015 incorporated yellowdog limited january 2015 first render application launched sale november 2015 launched second application batch processing financial services march 2018 originally envisioned peer peer power sharing network yellowdog soon changed power source private providers public cloud infrastructure idle capacity handful company data centers uses power give creative firms processing power need produce complex 3d renderings work yellowdog received crowdfunding seedrs 2015 subsequent investment private equity networks vc investment yellowdog gives creative firms processing power need produce complex 3d renderings work standard yellowdog released october 2015 standard yellowdog yellowdog widely used application supports 3ds max maya cinema 4d v-ray corona redshift mental ray software use across visual effects animation cgi naked yellowdog yellowdog deployed first customer october 2016 allows yellowdog support multiple combinations software supported standard yellowdog yellowdog premise released march 2018 finovate europe 2018 support batch processing banks financial services first public presentation product given live finovate europe 2018 yellowdog headquarters located bristol uk engine shed located bristol quarter enterprise zone engine shed new use part old temple meads station brunel original building partnership university bristol hosts business incubators including setsquared supports hi-tech startup companies public consultation engine shed 2 took place november 2016 yellowdog base engine shed encourages innovation collaboration networks based growth plans yellowdog double size 2018
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Distributed computing architecture
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lexical markup framework language resource management lexical markup framework lmf iso 24613:2008 iso international organization standardization iso/tc37 standard natural language processing nlp machine-readable dictionary mrd lexicons scope standardization principles methods relating language resources contexts multilingual communication goals lmf provide common model creation use lexical resources manage exchange data among resources enable merging large number individual electronic resources form extensive global electronic resources types individual instantiations lmf include monolingual bilingual multilingual lexical resources specifications used small large lexicons simple complex lexicons written spoken lexical representations descriptions range morphology syntax computational semantics computer-assisted translation covered languages restricted european languages cover natural languages range targeted nlp applications restricted lmf able represent lexicons including wordnet edr parole lexicons past lexicon standardization studied developed series projects like genelex edr eagles multext parole simple isle iso/tc37 national delegations decided address standards dedicated nlp lexicon representation work lmf started summer 2003 new work item proposal issued us delegation fall 2003 french delegation issued technical proposition data model dedicated nlp lexicons early 2004 iso/tc37 committee decided form common iso project nicoletta calzolari cnr-ilc italy convenor gil francopoulo tagmatica france monte george ansi usa editors first step developing lmf design overall framework based general features existing lexicons develop consistent terminology describe components lexicons next step actual design comprehensive model best represented lexicons detail large panel 60 experts contributed wide range requirements lmf covered many types nlp lexicons editors lmf worked closely panel experts identify best solutions reach consensus design lmf special attention paid morphology order provide powerful mechanisms handling problems several languages known difficult handle 13 versions written dispatched national nominated experts commented discussed various iso technical meetings five years work including numerous face-to-face meetings e-mail exchanges editors arrived coherent uml model conclusion lmf considered synthesis state art nlp lexicon field iso number 24613 lmf specification published officially international standard 17 november 2008 iso/tc37 standards currently elaborated high level specifications deal word segmentation iso 24614 annotations iso 24611 a.k.a maf iso 24612 a.k.a laf iso 24615 a.k.a synaf iso 24617-1 a.k.a semaf/time feature structures iso 24610 multimedia containers iso 24616 a.k.a mlif lexicons iso 24613 standards based low level specifications dedicated constants namely data categories revision iso 12620 language codes iso 639 scripts codes iso 15924 country codes iso 3166 unicode iso 10646 two level organization forms coherent family standards following common simple rules linguistics constants like /feminine/ /transitive/ defined within lmf recorded data category registry dcr maintained global resource iso/tc37 compliance iso/iec 11179-3:2003 constants used adorn high level structural elements lmf specification complies modeling principles unified modeling language uml defined object management group omg structure specified means uml class diagrams examples presented means uml instance object diagrams xml dtd given annex lmf document lmf composed following components extensions specifically dedicated morphology mrd nlp syntax nlp semantics nlp multilingual notations nlp morphological patterns multiword expression patterns constraint expression patterns following example lexical entry associated lemma clergyman two inflected forms clergyman clergymen language coding set whole lexical resource language value set whole lexicon shown following uml instance diagram elements lexical resource global information lexicon lexical entry lemma word form define structure lexicon specified within lmf document contrary languagecoding language partofspeech commonnoun writtenform grammaticalnumber singular plural data categories taken data category registry marks adorn structure values iso 639-3 clergyman clergymen plain character strings value eng taken list languages defined iso 639-3 additional information like dtdversion feat data expressed following xml fragment example rather simple lmf represent much complex linguistic descriptions xml tagging correspondingly complex first publication lmf specification ratified iso paper became 2015 9th cited paper within language resources evaluation conferences lrec papers semantic representation african languages asian languages european languages semitic languages book published 2013 lmf lexical markup framework entirely dedicated lmf first chapter deals history lexicon models second chapter formal presentation data model third one deals relation data categories iso-dcr 14 chapters deal lexicon system either civil military domain either within scientific research labs industrial applications wordnet-lmf prolmf duelme uby-lmf lg-lmf relish globalatlas global atlas wordscape
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Computational linguistics
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smolt linux smolt computer program used gather hardware information computers running linux submit central server statistical purposes quality assurance support initiated fedora release fedora 7 soon combined effort various linux projects information collection voluntary opt-in anonymous smolt run automatically requested permission uploading new data smolt server october 10 2012 announced smolt would discontinued november 1 2013 effect server http //www.smolts.org responds message smolts project retired smolt widely accepted system assembling linux statistics one place smolt first attempt first accepted major linux distributions collecting kind data across distributions smolt included smolt server stored collected data
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Operating systems
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deskstation tyne deskstation tyne line computer workstations made deskstation technology based mips r4000 r4400 risc microprocessors deskstation tyne designed run windows nt designed conform advanced risc computing standard run associated firmware
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Computer architecture
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burroughs medium systems burroughs b2500 burroughs b4900 series mainframe computers developed manufactured burroughs corporation pasadena california united states 1966 1991 aimed business world instruction set optimized cobol programming language also known burroughs medium systems contrast burroughs large systems burroughs small systems b2500 b3500 computers announced 1966 operated directly cobol-68 primary decimal data types strings 100 digits one ebcdic ascii digit character two 4-bit binary-coded decimal bcd digits per byte portable cobol programs use binary integers b2500 either even memory addresses memory addressed 4-bit digit big-endian style using 5-digit decimal addresses floating point numbers also used base 10 rather binary base 100 mantissa digits typical cobol statement 'codice_1 may use operands different lengths different digit representations different sign representations statement compiled single 12-byte instruction 3 memory operands complex formatting printing accomplished executing single codice_2 instruction detailed format descriptors high level instructions implemented translate buffer e.g ebcdic ascii conversion table buffer sort table using sort requirements table extreme cases single instructions could run several hundredths second mcp could terminate over-long instructions could interrupt resume partially completed instructions resumption prerequisite page style virtual memory operands cross page boundaries machine matched cobol closely cobol compiler simple fast cobol programmers found easy assembly programming well original instruction set operations memory-to-memory visible data registers arithmetic done serially one digit time beginning most-significant digits working rightwards least-significant digits backwards manual right-to-left methods complicated allowed result writing suppressed overflow cases serial arithmetic worked well cobol languages like fortran bpl much less efficient standard word-oriented computers three reserved memory locations used address indexing 'registers third index register dedicated pointing current procedure stack frame call/return stack reserved memory locations controlled operand sizes size constant b3500 similar b2500 faster cycle time expansion choices b2500 maximum 60 k bytes core memory 2 microsecond cycle time b3500 maximum 500 k bytes 1-microsecond cycle time b2500/3500 weighed b2500/b3500 machines followed b2700/b3700/b4700 1972 b2800/b3800/b4800 1976 b2900/b3900/b4900 1980 first range load microcode floppy disk rather implementing hardware read-only memory finally unisys v series machines v340-v560 1985-90 machines prior b4800 cache memory every operand byte result byte required separate main memory cycle limited program performance compensate b3700/b4700 generation used semiconductor main memory faster expensive power hungry dram used competing machines unusual use decimal numbers memory addresses initially problem merely involved using 1-in-5 rather 1-in-8 decoder logic core memory row selects bank selects later machines used standard memory chips expected binary addresses 1000-byte block logical memory could trivially mapped onto subset 1024 bytes chip 2.3 waste denser chips larger total memories entire decimal address crunched shorter quasi binary form sending address chips done cache memory cycle conversion logic slowed machine cycle somewhat attempted redesign 1975 address space called ms-3 medium systems 3rd generation project cancelled machines b2900 allowed input numbers 'undigit values 9 arithmetic gave unspecified results used form hexadecimal arithmetic within mcp also application programmers later versions discontinued instead supported two new opcodes binary decimal decimal binary support addressing hard drives available burroughs acquisition memorex unisys cancelled v series hardware development 1991 support ended 2004 b4900 later machines integer operations 10 digits less handled parallel longer operands continued use serial method floating point operations limited 17 digits precision later medium systems machines added accumulator register accumulator/memory instructions using 32-bit 7-digit integers 48-bit 80-bit floating point values aligned 16-bit word boundaries operating system called mcp master control program shared many architectural features mcp burroughs large systems stack machines entirely different internally coded assembly language algol-derivative programs separate address spaces dynamically relocated base register otherwise virtual memory paging segmentation larger programs squeezed limited code address space explicit overlays nonresident parts mcp also heavily overlaid initially code data shared single 300,000 digit address space later machines separate million-digit spaces program code process data instructions address fields extended 5 digits 6 digits 4 real index registers added early machines used burroughs head-per-track disk systems rather now-standard movable head platter disks one attempt speed mcp overlays carefully laid likely-next overlays would soon arrive read head current overlay completed similar time-dependent layout optimizations early delay-line drum computers turned impractical maintain software changes better results consistently achieved totally randomized layout mcp overlays operating system system software coded bpl burroughs programming language systems programming language derived algol large system espol systems language initial cobol compiler supported ansi 68 specification supported codice_3 syntax allow inline assembly language coding lacked support relative indexed file support later added ansi 74 version compiler released 1982 mcp allowed programs communicate via core-to-core transmissions codice_4 using storage queues codice_5 implemented system calls using codice_6 instruction exposed languages cobol codice_7 unheard except largest ibm s/360 systems time even major operational headache manage interactions multiple program streams medium systems series effective multi-programming machines even basic versions b2500 could support multiprogramming usable scale larger medium systems processors supported major data center activities banks financial institutions well many businesses government customers medium system preferred platform many data processing professionals medium system computer could simultaneously running batch payroll system inputting bank checks micr reader sorter compiling cobol applications supporting on-line transactions test runs new applications colloquially called 'the mix console command 'codice_8 would shows jobs executing unusual running eight ten programs medium-size b2500 medium system installations often tape clusters four drives integrated mid-height cabinet magnetic tape input output free-standing tape drives also available much expensive tape major storage medium computers early days often used father-son batch updating additional disk becoming cheaper time moved became relegated library/backup device contained data files sometimes program files using mfsolt utility particular application customer/client cobol machine code tape resident disk files job headers card input card print spooling accounting system parameter driven —a blank verse unknown b2500 user
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Computer architecture
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chakra jscript engine chakra jscript engine developed microsoft 32-bit version internet explorer 9 ie9 web browser jscript engine developed closed source proprietary software microsoft developed different javascript engine based jscript newer microsoft edge browser also called chakra chakra javascript engine open-sourced mit license distinctive feature engine jit compiles scripts separate cpu core parallel web browser though microsoft past pointed elements rendering marshalling important browser overall performance improvements engine response evolving competing browsers compared ie8 lagging behind terms client-side script processing speed sunspider tests performed november 18 2009 showed pdc version ie9 executing scripts much faster ie8 slower firefox 3.6 chrome 4 webkit nightly test performed march 15 2010 showed first ie9 platform preview using then-current version chakra faster firefox spidermonkey slower safari squirrelfish extreme chrome v8 opera carakan march 8 2011 microsoft published results showing 32-bit internet explorer 9 faster safari firefox tracemonkey chrome opera march 2011 performance tests zdnet concluded internet explorer 9 32-bit chrome 10 firefox 4 release candidate pretty evenly matched 2012 subsequent versions chakra version included internet explorer 10 introduced additional performance changes including jit compilation x64 arm architectures optimizations related floating point math garbage collection last call jsconf 2015 microsoft announced open sourcing chakracore engine january 2016 github chakracore essentially chakra engine powers microsoft edge browser platform-agnostic bindings i.e without specific interfaces utilised within windows universal app platform january 13 2016 microsoft released chakracore mit license github promised
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Programming language topics
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twinbee various twinbee sequels released arcade home console markets following original game spawned audio drama anime adaptations japan twinbee played 2-players simultaneously player takes control cartoon-like anthropomorphic spacecraft player 1 taking control twinbee titular ship player 2 controls winbee game control consists eight-way joystick two buttons one shooting enemies air dropping bombs ground enemies similarly xevious player primary power-ups bells uncovered shooting floating clouds 're hidden player continues shooting bell appears change one four colors regular yellow bells grant bonus points white bell upgrade player gun twin cannon blue bell increases player speed five speed levels green bell allow player create image copies ship additional firepower red bell provide player ship barrier allows sustain damage green red bells combined together power-ups also retrieved ground enemies alternate bell gives player ship three-way gun star eliminates on-screen enemies games genre getting shot single enemy bullet cause player lose life however bullet strikes either side ship instead player ship lose one arms player ship loses arms lose ability throw bombs player must wait ambulance arrive player must navigate ship ambulance repair arms however player ship loses arms second time ambulance arrive two players playing time align ships vertically horizontally together perform powerful attacks twinbee originally appeared arcade game later ported msx family computer famicom version re-released japan famicom mini label game boy advance game officially released first time outside japan part nintendo ds march 2007 name rainbowbell north america although twinbee name restored european release twinbee released japan august 10 2011 regions september 22 2011 nintendo 3ds part 3d classics series release featured amongst games nintendo entertainment system super nes released 3ds tech demo called classic games e3 2010 arcade version twinbee made available microsoft game room service xbox 360 console windows-based pcs december 1 2010 also msx version re-released windows egg project august 19 2014 playstation 4 published hamster corporation japan nes port re-released nintendo switch online november 14 2018 worldwide sp version titled twinbee second helping donburi island released june 12 2019 twinbee version nintendo 3ds received total 68/100 metacritic mixed positive average user score 6.8
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Computer architecture
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arm cortex-a8 arm cortex-a8 32-bit processor core licensed arm holdings implementing armv7-a architecture compared arm11 cortex-a8 dual-issue superscalar design achieving roughly twice instructions per cycle cortex-a8 first cortex design adopted large scale consumer devices key features cortex-a8 core several system-on-chips soc implemented cortex-a8 core including arm cortex force drives mobile devices
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Computer architecture
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core pocket media player core pocket media player tcpmp software media player operates portable devices windows-based pcs discontinued still available official mirror site supported operating systems include palm os symbian os microsoft windows ce mobile also available microsoft zune hd via hack called liberate tcpmp also hardware accelerated playback ati intel 2700g mobiles tapwave zodiac dell axim x50v/x51v development free version software discontinued corecodec favour commercially licensed coreplayer though tcpmp still regarded one versatile media players pocketpc palm os mobile devices according corecodec.com website september 2002 development team planned continue development releases open source version player offsite code would also incorporated commercial player 2004 corecodec.org open source player released betaplayer 0.01a windows ce windows mobile renamed core pocket media player july 2005 upon release palm os windows ce/mobile operating systems release tcpmp symbian os remarked upon information available forums tcpmp project page indicates development languages used assembly c 2006 corecodec inc. discontinued development tcpmp focus commercial coreplayer platform tcpmp supports many audio video image formats including ac3 he-aac later removed amr divx flac h.263 h.264 jpeg monkey audio mjpeg mpeg-1 mp2 mp3 musepack ms-mpeg4-v3 png speex tiff tta vorbis wav wavpack xvid supports many container formats including 3gp asf avi matroska mpeg ogg ogm quicktime windows desktop platform third-party codec support h.264 third-party plugin support youtube videos flash video formats program received consistently positive reviews performance versatility functionality minor criticism user interface issues hpc factor magazine evaluating version 0.66 declared excellent noting need improvement menu space usage complete lack documentation version 0.70 described best free multimedia player pocket pc palm os platform smartphone pocket pc magazine november 2005 2006 treo central review gave score 4/5 use palm os-equipped treo devices pretty cool logical interface albeit drawbacks supporting almost every video encapsulation known humankind without conversion prior playback smartdevice central reviewed version 0.71 palm treo 700 2007 called impressive solid piece software summarizing user interface resembling black-and-white macintosh app late 1980s absolutely eye candy whatsoever corecodec inc. discontinued development tcpmp 2006 renamed coreplayer developed commercial sale one review referred quirky rock solid tcpmp bulletproof compared early version new player later reviews mentioned problems stability
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Operating systems
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jaws scripting language jaws scripting language proprietary programming language facilitates interoperability jaws windows screen reading program practically application–both proprietary off-the-shelf jaws scripting language jsl compiled language allowing source code protection jaws scripting commonly also cumulatively refers customization jaws use built-in user-editable utilities called managers editing configuration files directly combination writing actual scripts scripting language api exposes functionality including combination traditional jaws scripting msaa server direct scripting document object model scripting ensure optimal performance jaws end-users
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Programming language topics
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netbackup computing veritas netbackup called symantec netbackup prior symantec divestiture veritas enterprise-level heterogeneous backup recovery suite provides cross-platform backup functionality large variety windows unix linux operating systems netbackup features central master server manages media servers containing backup media clients core server platforms include solaris hp-ux aix tru64 linux windows netbackup opscenter comes bundled netbackup 7.0 distribution replaces netbackup operations manager nom component used previous versions manage multiple netbackup environments netbackup comes support many hardware devices like tape drives tape libraries disk units supports among many features hot backups major database products like oracle natively backup restore virtual machines major virtualization products like vmware infrastructure use network data management protocol ndmp tape vaulting netbackup also enables lan-free server-free backups san fabric environments
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Computer security
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macintosh lc iii macintosh lc iii personal computer designed manufactured sold apple computer inc. february 1993 february 1994 replaced commercially successful macintosh lc ii apple lineup mid-range computers significantly faster macworld magazine benchmarks showing 2x performance major categories cpu disk video math also significantly less expensive lc iii 80 mb hard disk priced 1,349 usd introduction 700 less lc ii lc iii sold primarily exclusively educational institutions corresponding performa variant called performa 450 sold consumer market speed-bumped version called macintosh lc iii+ released october year 33 mhz cpu three performa variants model released 460 466 467 faster models replaced lc iii performa 450 sales original models continuing end 1993 dealers depleted stocks new sales lc iii+ ended early 1994 apple neared completion transition away 68030 processors 68lc040-based lc 475 performa 475 replacements introduced february 10 1993 introduced october 18 1993
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Computer architecture
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john viega john viega born february 22 1974 american computer security author researcher professional earned ba university virginia undergraduate worked randy pausch stage 3 research group early contributor alice viega earned ms computer science also university virginia john viega co-authored widely used gcm mode operation aes along david a. mcgrew also co-designed predecessor cwc mode john viega also pioneer static analysis security vulnerabilities responsible first publicly available tool its4. well prominent open source rough auditing tool security rats also founded secure software first commercial vendor tools bought fortify software john viega also original author owasp clasp lightweight process relating software development security also former editor-in-chief ieee security privacy magazine addition viega original author gnu mailman mailing list program john viega executive vice president products engineering bae systems applied intelligence joined bae systems 2014 acquisition silversky cloud security provider funded goldman sachs bessemer ventures prior silversky viega mcafee cto saas prior mcafee chief security architect currently teaches nyu previously taught virginia tech co-author building secure software addison wesley 2001 first book teach developers write secure software since co-authored number additional books computer security including myths security o'reilly 2009 beautiful security o'reilly 2009 network security openssl ’ reilly 2002 secure programming cookbook ’ reilly 2003 19 deadly sins software security mcgraw hill 2005
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Computer security
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monoculture computer science computer science monoculture community computers run identical software computer systems community thus vulnerabilities like agricultural monocultures subject catastrophic failure event successful attack concept significant discussing computer security viruses clifford stoll wrote 1989 dealing morris worm dan geer argued microsoft monoculture since majority overall number workstations connected internet running versions microsoft windows operating system many vulnerable attacks
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Computer security
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michael simms software developer michael simms creator tux games website founder linux game publishing simms began using linux university 1992 writing contributing open source software since 1993 strong belief operating systems file formats need open source order make computing competitive 2000 2001 also worked wcities london lead product architect simms beta tester loki software linux ports descent 3 response unable order versions loki titles british reseller spurred create tux games one first online linux game stores website went live ten seconds midnight 1 january 2000 selling first title 3 january response loki demise effect would tux games simms invested £350,000 company porting windows game titles linux linux game publishing founded 15 october 2001 port publish new games linux simms remained ceo well head development decade likes play majesty strategy games 31 january 2012 simms announced stepping ceo handing control clive crous
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Operating systems
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logicworks logicworks cloud computing managed hosting company headquartered new york city offices seattle washington d.c. london logicworks enterprise cloud automation managed service provider company founded february 1993 1998 logicworks changed focus standard web hosting complex types managed hosting high points years included logicworks getting first mysql enterprise partner designation 2003 expanding private cloud hosting 2007 focus cloud continues today starting logicworks cloud 2010 adding another data center bring company three 2011 april 2011 logicworks received 7.6 million venture funding round logicworks cloud offerings marketed traditional cloud computing offers instead remote hosting solutions december 14 2016 logicworks announced raised 135 million private equity firm pamplona capital grow automation consulting business logicworks provides managed services amazon web services cloud infrastructure called managed amazon web services logicworks adds management layer top aws cloud strategize architect implement scale aws cloud instances tools applications 2015 logicworks added aws premier partner network since logicworks added many services including logicworks private cloud offerings based vmware ’ virtualization platform logicworks specializes hipaa pci compliance hosting infrastructure design aws private cloud environments
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Distributed computing architecture
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debug new debug_new refers technique c++ overload and/or redefine operator new operator delete order intercept memory allocation deallocation calls thus debug program memory usage often involves defining macro named debug_new makes new become something like new __file__ __line__ record file/line information allocation microsoft visual c++ uses technique microsoft foundation classes ways extend method avoid using macro redefinition still able display file/line information platforms many inherent limitations method applies c++ catch memory leaks c functions like malloc however simple use also fast compared complete memory debugger solutions
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Operating systems
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next3 next3 journaled file system linux based ext3 adds snapshots support yet retains compatibility ext3 on-disk format next3 implemented open-source software licensed gpl license snapshot read-only copy file system frozen point time versioning file systems like next3 internally track old versions files make snapshots available special namespace advantage copy-on-write next3 writes new data blocks containing old data retained allowing snapshot version file system maintained next3 snapshots created quickly since data composing snapshot already stored also space efficient since unchanged data shared among file system snapshots traditional linux logical volume manager volume level snapshots implementation requires storage space allocated advance next3 uses dynamically provisioned snapshots meaning require pre-allocation storage space snapshots instead allocating space needed storage space conserved sharing unchanged data among file system snapshots since next3 aims forward backward compatible earlier ext3 on-disk structures identical ext3 file system mounted read existing ext3 implementations modification next3 like ext3 lacks number features recent designs extents snapshots next3 performance equivalent ext3 performance snapshots minor overhead per write metadata block copy-on-write smaller overhead ~1 per write data block move-on-write 2011 next4 project porting next3 snapshot capabilities ext4 file system mostly completed porting attributed members pune institute computer technology pict chinese academy sciences
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Computer file systems
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peerblock peerblock free open-source personal firewall blocks packets coming going maintained list black listed hosts peerblock windows successor software peerguardian currently maintained linux blocks incoming outgoing connections ip addresses included blacklists made available internet addresses specified user peerblock mainly uses blacklists provided iblocklist.com peerblock 1.0 based code peerguardian 2 rc1 test3 vista version adds support 32- 64-bit windows vista windows 7 windows 8 peerguardian project ended developer phoenix labs encouraged current peerguardian users migrate peerblock peerblock development small team developers led mark bulas hosting well signed driver funded donations public future donations intended contribute future signed drivers hosting possibly rent virtual private server team able build real online-update feature future releases peerblock introduced 2017 peerblocklist.com offers modern blocklists p2p format compatible peerblock peerblock multiple features latest version program include constantly updating blocklist managed home site manager lets choose lists include block program allows user turn ip http trackers well including log showing time source ip address destination protocol tracker list settings allows users customize program interface well operations september 2013 i-blocklist supplier blocking lists peerblock uses supported unlimited free list updating since september 2013 updates limited weekly except paid subscribers peerblock hard-coded use i-blocklist lists entered revenue-sharing agreement i-blocklist late 2015 blocklists longer available without payment subscription late 2017 peerblocklist.com began offering free blocklists malicious hosts ad-servers peerblock peerguardian users
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Computer security
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harlequin rip harlequin rip raster image processor first released 1990 name scriptworks running command-line application render postscript language files unix developed harlequin software company based cambridge england harlequin rip started life 1986 final year university project software developer andy cave project build subset postscript interpreter could preview result converting tex/latex files postscript phd students would n't waste much paper new laserwriter although subset required cave ended creating quite complete implementation 1987 cave joined harlequin limited founding rip division bringing work 'd done bath university early 1990s harlequin commissioned xenotron develop raster image processor rip run macintosh computers drive ultre-based image setters exposing onto film resin-coated rc paper macintosh version proved successful harlequin signed number original equipment manufacturer oem partners sell including pongrass ecrm autologic xitron koronix purup graphic enterprises compose 1992 dos variation core rip developed also sold oem partners replaced version running microsoft windows 1993 1999 harlequin group went receivership bought global graphics harlequin group including staff assets renamed global graphics software limited unix-based command-line version rip phased years later rip finally renamed scriptworks harlequin rip 2004 onwards global graphics expanded reach harlequin rip producing number variants different market sectors harlequin rip sold oem partners builds prepress system digital front end dfe controller therefore sold variety names always easy identify whether system uses harlequin rip current versions harlequin rip interpret harlequin embedded sdk also supports printer command language 5e pcl 5c pcl xl including hpgl printer job language pjl file formats interpreted natively without conversion intermediate format pdf converted postscript vice versa example global graphics claims processing without conversion allows higher speeds avoids artifacts arising conversion native processing live transparency pdfs recognized several awards publishing essential impact award rip year 1997 1998 silver award pre-press news publishing awards 1997 rip/server product year harlequin rip also explicitly supports pdf/x-1a:2001 pdf/x-1a:2003 pdf/x-3:2002 pdf/x-3:2003 pdf/x-4 pdf/x-4p pdf/x-5g pdf/x-5pg set reject files comply standards include conformance information control strip proof harlequin oem partners built dfes full support additional formats personalized print markup language ppml around harlequin rip number extra components available variants harlequin rip leading descriptions harlequin server rip prepress workflow box included additional options include harlequin host renderer launched 2005 version 1.3 released late 2009 core rip functionality hhr tracked harlequin server rip except hhr currently following additional features comparison hsr 8.3 hhr supported linux windows harlequin embedded sdk ebd optimized use within home office printers end supports several versions printer control language pcl well printer job language pjl hewlett-packard graphics language hpgl ebd version 3 released 2009 supported variety real-time near-real-time operating systems including embedded windows xp linux vxworks threadx variety hardware architectures including intel freescale arm without system-on-a-chip soc around cpu global graphics announced partnership conexant provide combination hardware page description language pdl software home small office printers
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Programming language topics
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time-sharing computing time-sharing sharing computing resource among many users means multiprogramming multi-tasking time introduction 1960s emergence prominent model computing 1970s represented major technological shift history computing allowing large number users interact concurrently single computer time-sharing dramatically lowered cost providing computing capability made possible individuals organizations use computer without owning one promoted interactive use computers development new interactive applications earliest computers extremely expensive devices slow comparison later models machines typically dedicated particular set tasks operated control panels operator manually entering small programs via switches order load run series programs programs might take hours even weeks run computers grew speed run times dropped soon time taken start next program became concern batch processing methodologies evolved decrease dead periods queuing programs soon one program completed next would start support batch processing operation number comparatively inexpensive card punch paper tape writers used programmers write programs offline typing punching complete programs submitted operations team scheduled run important programs started quickly long less important programs started unpredictable program run finally completed output generally printed returned programmer complete process might take days time programmer might never see computer alternative allowing user operate computer directly generally far expensive consider users might long periods entering code computer remained idle situation limited interactive development organizations could afford waste computing cycles large universities part programmers universities decried behaviors batch processing imposed point stanford students made short film humorously critiquing experimented new ways interact directly computer field today known human–computer interaction time-sharing developed realization single user would make inefficient use computer large group users together would due pattern interaction typically individual user entered bursts information followed long pauses group users working time would mean pauses one user would filled activity others given optimal group size overall process could efficient similarly small slices time spent waiting disk tape network input could granted users concept claimed first described john backus 1954 summer session mit later bob bemer 1957 article consider computer automatic control magazine paper published december 1958 w. f. bauer wrote computers would handle number problems concurrently organizations would input-output equipment installed premises would buy time computer much way average household buys power water utility companies implementing system able take advantage initially difficult batch processing effectively methodological development top earliest systems since computers still ran single programs single users time primary change batch processing time delay one program next developing system supported multiple users time completely different concept state user programs would kept machine switched quickly would take computer cycles slow machines era concern however computers rapidly improved speed especially size core memory users states retained overhead time-sharing continually decreased relatively speaking first project implement time-sharing user programs initiated john mccarthy mit 1959 initially planned modified ibm 704 later additionally modified ibm 709 one first computers powerful enough time-sharing one deliverables project known compatible time-sharing system ctss demonstrated november 1961 ctss good claim first time-sharing system remained use 1973 another contender first demonstrated time-sharing system plato ii created donald bitzer public demonstration robert allerton park near university illinois early 1961 special-purpose system bitzer long said plato project would gotten patent time-sharing university illinois lost patent two years joss began time-sharing service january 1964 first commercially successful time-sharing system dartmouth time sharing system throughout late 1960s 1970s computer terminals multiplexed onto large institutional mainframe computers centralized computing systems many implementations sequentially polled terminals see whether additional data available action requested computer user later technology interconnections interrupt driven used parallel data transfer technologies ieee 488 standard generally computer terminals utilized college properties much places desktop computers personal computers found today earliest days personal computers many fact used particularly smart terminals time-sharing systems dartmouth time sharing system creators wrote 1968 response time averages 10 seconds destroys illusion one computer conversely timesharing users thought terminal computer rise microcomputing early 1980s time-sharing became less significant individual microprocessors sufficiently inexpensive single person could cpu time dedicated solely needs even idle however internet brought general concept time-sharing back popularity expensive corporate server farms costing millions host thousands customers sharing common resources early serial terminals web sites operate primarily bursts activity followed periods idle time bursting nature permits service used many customers usually perceptible communication delays unless servers start get busy genesis 1960s several companies started providing time-sharing services service bureaus early systems used teletype model 33 ksr asr teletype model 35 ksr asr machines ascii environments ibm selectric typewriter-based terminals especially ibm 2741 two different seven-bit codes would connect central computer dial-up bell 103a modem acoustically coupled modems operating 10–15 characters per second later terminals modems supported 30–120 characters per second time-sharing system would provide complete operating environment including variety programming language processors various software packages file storage bulk printing off-line storage users charged rent terminal charge hours connect time charge seconds cpu time charge kilobyte-months disk storage common systems used time-sharing included sds 940 pdp-10 ibm 360 companies providing service included ge geisco ibm subsidiary service bureau corporation tymshare founded 1966 national css founded 1967 bought dun bradstreet 1979 dial data bought tymshare 1968 bolt beranek newman bbn time sharing ltd. u.k.. 1968 32 service bureaus serving us national institutes health nih alone auerbach guide timesharing 1973 lists 125 different timesharing services using equipment burroughs cdc dec hp honeywell ibm rca univac xds 1975 said one major super-mini computer manufacturers biggest end-user market currently time-sharing dec second largest computer company ibm also true pdp-10 ibm 360/67 widely used commercial timesharing services compuserve on-line systems ols rapidata time sharing ltd although many time-sharing services simply closed rapidata held became part national data corporation still sufficient interest 1982 focus user guide statistics programs rapidata timesharing system even revenue fell 66 national data subsequently developed problems attempts made keep timesharing business going beginning 1964 multics operating system designed computing utility modeled electrical telephone utilities 1970s ted nelson original xanadu hypertext repository envisioned service seemed computer industry grew consolidation computing resources would occur timesharing systems 1990s concept however revived somewhat modified form banner cloud computing time-sharing first time multiple processes owned different users running single machine processes could interfere one another example one process might alter shared resources another process relied variable stored memory one user using system would result possibly wrong output multiple users might mean users got see information meant see prevent happening operating system needed enforce set policies determined privileges process example operating system might deny access certain variable certain process first international conference computer security london 1971 primarily driven time-sharing industry customers significant early timesharing systems
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Operating systems
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lha file format lha freeware compression utility associated file format created 1988 originally named lharc complete rewrite lharc tentatively named lhx eventually released lh renamed lha avoid conflicting then-new ms-dos 5.0 lh load high command according early documentation lha pronounced like la although longer much used west lha remains popular japan used id software compress installation files earlier games including doom quake lha ported many operating systems still main archiving format used amiga computer although competed lzx mid 1990s due aminet world largest archive amiga-related software files standardising stefan boberg implementation lha amiga microsoft released windows xp add-on microsoft compressed lzh folder add-on designed japanese version operating system japanese version windows 7 ships lzh folder add-on built-in users non-japanese versions windows 7 enterprise ultimate also install lzh folder add-on installing optional japanese language pack windows update lzh archive compression method stored five-byte text string third seventh bytes file lharc compresses files using algorithm yoshizaki earlier lzhuf product modified lzari developed uses huffman coding instead arithmetic coding lzari uses lempel–ziv–storer–szymanski arithmetic coding compression method applied source data method introduced lharc version 1 supports 4 kib sliding window support maximum 60 bytes matching length dynamic huffman encoding used method supports 8 kib sliding window support maximum 256 bytes matching length dynamic huffman encoding used methods 4 5 6 7 support 4 8 32 64 kib sliding window respectively support maximum 256 bytes matching length static huffman encoding used lh5 first introduced lharc 2 followed lh6 lha 2.66 msdos lh7 lha 2.67 beta msdos lha never compresses lh4 technically compression method used .lzh archive indicate compressed object empty directory joe jared extended lzss use larger dictionaries dictionary sizes 64 128 256 512 1024 2048 kib respectively unlha32.dll uses method testing purposes uses 128–256 kib dictionary compression methods created pmarc cp/m archiver created miyo archive usually .pma extension popcom compressed executable archive compression method applied source data used indicate pmarc self-extracting archive larc uses file format .lzh written kazuhiko miki haruhiko okumura ken masuyama extension name .lzs supports 2 kib sliding window support maximum 17 bytes matching length similar lzs except dictionary size match length changed compression method applied source data supports 4 kib sliding window support maximum 17 bytes matching length copies lhice marked version 1.14 according okumura lhice written yoshi bug timestamps since year 2011 set 1980 meaning utilities need patched
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Computer file systems
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scalable source routing scalable source routing ssr routing protocol unstructured networks mobile ad hoc networks mesh networks sensor networks combines source routing routing along virtual ring based idea pushing chord underlay ssr operates flat address space organized virtual ring popular concept peer-to-peer overlay networks like chord common knowledge ring structure enables nodes route packets without knowing topology underlying physical network physical network dynamic structure virtual ring remains rather static therefore flooding physical network avoided packets travel along ring decrease virtual distance destination absolute difference addresses node knows correct predecessor successor virtual ring delivery correct receiving node guaranteed ring said consistent often routing assumed defined orientation ring merely help simplify theory practice necessary even detrimental performance finger table chord provides shortcuts virtual ring replaced route cache physical network ssr utilizes source routing relaying nodes opportunistically cache traversed part source route given packet facilitates collection routing information inhibiting polluting nodes route caches outdated information node need complete path destination route cache make use cache line instead message routed towards physical nearest node makes progress virtual ring message arrives intermediate node node adds information route cache source route step repeated needed message arrives final destination path optimization using dijkstra algorithm route update message sent originator node thus updating originators route cache technique facilitates usage fixed size route caches limits per-node state makes ssr viable option low memory environments ssr complete routing protocol cf osi model network layer also provides semantics distributed hash table reduces overhead overlay protocol top traditional routing protocol greatly expedites lookup operations manets otherwise would rely flooding provided application supports modified support key-based routing provided dht functionality also used implement scalable network services absence servers every node periodically broadcasts hello message physical neighbors notifying neighbors existence hello messages include list physical neighbors node node finds included hello message another node assumes bidirectional connection adds node list physical peers later use routing node also sends neighbor notification message assumed successor join virtual ring contacted node detects correct successor replies message containing best guess successor inquiring node repeated correct virtual neighbors found detailed description process called isprp see another way bootstrapping linearization node routes message ssr reactive well proactive components making hybrid routing protocol virtual ring routing conceptually similar biggest difference usage source routing ssr compared building per-node state routing tables vrr
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Distributed computing architecture
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law enforcement information exchange law enforcement information exchange database maintained naval criminal investigative service eugene r. fidell described database constituting domestic spying according ncis website naval criminal investigative service ncis launched law enforcement information exchange linx initiative 2003 linx designed enhance information sharing local state federal law enforcement areas strategic importance department navy linx provides participating law enforcement partner agencies secure access regional crime incident data tools needed process enabling investigators search across jurisdictional boundaries help solve crimes resolve suspicious events linx designed facilitate cooperation sharing ownership control data remains agency provided
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Computer security
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fira os fira os linux-based mobile operating system software platform developed fira subsidiary indonesian electronic giant polytron member djarum group introduced january 28 2016 forked android installed newer polytron smartphones since 2016 fira os based android open source project aosp linux kernel built comply indonesian regulation requiring 40 minimum local content 4g lte smartphones sold indonesia starting 2017 fira os features applications usually available aosp-based operating systems fira check pulsa fira store fira pay fira directory others
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Operating systems
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jaguar microarchitecture amd jaguar family 16h low-power microarchitecture designed amd used apus succeeding bobcat family microarchitecture 2013 succeeded amd puma architecture 2014 two-way superscalar capable out-of-order execution used amd semi-custom business unit design custom processors used amd four product families kabini aimed notebooks mini pcs temash aimed tablets kyoto aimed micro-servers g-series aimed embedded applications playstation 4 xbox one use chips based jaguar microarchitecture powerful gpus amd sells commercially available jaguar apus jaguar core support following instruction sets instructions mmx sse sse2 sse3 ssse3 sse4a sse4.1 sse4.2 avx f16c clmul aes bmi1 movbe move big-endian instruction xsave/xsaveopt abm popcnt/lzcnt amd-v. socs using socket am1 2017 derivative jaguar microarchitecture announced apu microsoft xbox one x project scorpio revision xbox one project scorpio apu described 'customized derivative jaguar microarchitecture utilizing eight cores clocked 2.3 ghz puma successor jaguar released 2014 targeting entry level notebooks tablets
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Computer architecture
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anti-tamper software anti-tamper software tamper-resistant software software makes harder attacker modify measures involved passive obfuscation make reverse engineering difficult active tamper-detection techniques aim make program malfunction operate modified essentially tamper resistance implemented software domain shares certain aspects also differs related technologies like copy protection trusted hardware though often used combination anti-tampering technology typically makes software somewhat larger also performance impact provably secure software anti-tampering methods thus field arms race attackers software anti-tampering technologies tampering malicious gain control aspect software unauthorized modification alters computer program code behaviour examples include installing rootkits backdoors disabling security monitoring subverting authentication malicious code injection purposes data theft achieve higher user privileges altering control flow communication license code bypassing purpose software piracy code interference extract data algorithms counterfeiting software applications vulnerable effects tampering code changes throughout lifecycle development deployment operation maintenance anti-tamper protection applied either internally externally application protected external anti-tampering normally accomplished monitoring software detect tampering type defense commonly expressed malware scanners anti-virus applications internal anti-tampering used turn application security system generally done specific code within software detect tampering happens type tamper proofing defense may take form runtime integrity checks cyclic redundancy checksums anti-debugging measures encryption obfuscation execution inside virtual machine become common anti-tamper method used recent years commercial software used example starforce securom anti-tamper software uses white-box cryptography cryptographic keys revealed even cryptographic computations observed complete detail debugger recent research trend tamper-tolerant software aims correct effects tampering allow program continue unmodified simple easily defeated scheme kind used diablo ii video game stored critical player data two copies different memory locations one modified externally game used lower value anti-tamper software used many types software products including embedded systems financial applications software mobile devices network-appliance systems anti-cheating games military license management software digital rights management drm systems general-purpose packages developed wrap existing code minimal programing effort example securom similar kits used gaming industry though downside semi-generic attacking tools also exist counter malicious software observed using anti-tampering techniques example mariposa botnet
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Computer security
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list features android list features android operating system android devices include still/video cameras touchscreens gps accelerometers gyroscopes barometers magnetometers dedicated gaming controls proximity pressure sensors thermometers accelerated 2d bit blits hardware orientation scaling pixel format conversion accelerated 3d graphics
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Operating systems
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acl2 acl2 computational logic applicative common lisp software system consisting programming language extensible theory first-order logic automated theorem prover acl2 designed support automated reasoning inductive logical theories mostly purpose software hardware verification input language implementation acl2 written common lisp acl2 free open-source software acl2 programming language applicative side-effect free variant common lisp acl2 untyped acl2 functions total — every function maps object acl2 universe another object universe acl2 base theory axiomatizes semantics programming language built-in functions user definitions programming language satisfy definitional principle extend theory way maintains theory logical consistency core acl2 theorem prover based term rewriting core extensible user-discovered theorems used ad-hoc proof techniques subsequent conjectures acl2 intended industrial strength version boyer–moore theorem prover nqthm toward goal acl2 many features support clean engineering interesting mathematical computational theories acl2 also derives efficiency built common lisp example specification basis inductive verification compiled run natively 2005 authors boyer-moore family provers includes acl2 received acm software system award pioneering engineering effective theorem prover ... formal methods tool verifying safety-critical hardware software acl2 numerous industrial applications 1995 j strother moore matt kaufmann tom lynch used acl2 prove correctness floating point division operation amd k5 microprocessor wake pentium fdiv bug interesting applications page acl2 documentation summary uses system industrial users acl2 include amd centaur technology ibm intel oracle rockwell collins
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Programming language topics
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p.i.p.s p.i.p.s term recursive acronym symbian software libraries means p.i.p.s posix symbian os intended help c language programmers migration desktop server middleware applications symbian os based mobile smartphone devices pips software libraries provides c c++ application programming interfaces standard c libraries p.i.p.s environment support true signalling basic signal support emulated using threads open c open c++ extensions nokia p.i.p.s contrast mere p.i.p.s. series 60 phones name result internal competition symbian developer marketing department organised bruce carney developer marketing erik jacobson product manager full-stops inserted symbian legal department ensure trademark copyright infringements
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Operating systems
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forte 4gl forté 4gl proprietary application server developed forté software used developing scalable highly available enterprise applications forté 4gl created integrated solution developing managing client/server applications forté 4gl consists application server tools deploying monitoring application object oriented proprietary programming language tool transactional object oriented language given tool runs forté application server many users simply refer tool applications forté applications first release forté 4gl published august 1994 releasing initial product forté inc. proceeded build several extensions including 1999 forté software came version forte based java instead tool named synerj also referred forté java original tool-based products consisted development ide code repository runtime environment new java product interest sun microsystems bought company tool-based extensions listed bundled together re-branded unified development server uds integration server iplanet division server modules later bundled together enterprise application integration eai sun declared product end-of-life indicating future plans continue development product sun official support forte ended april 2009 enterprise application development system forté 4gl supported close linkage number different relational database systems including oracle sybase microsoft sql server informix db2 linkages could via sql embedded within tool code via sql constructed fly also support distributed applications developer would create instance specific class would placed user-specified server calls methods instance would sent across network transparently developer would need know underlying details call would transmitted tool object-oriented language following features among others tool code case-insensitive statement always terminated semicolon compound statements enclosed keywords codice_2 codice_3 comments indicated // -- remainder line becomes comment /* ... */ data types simple data types corresponding object data types examples arrays indicated keywords codice_4 first element array indexed 1 variable declaration conditional statements if-statement case-statement iteration loops events event posted e.g following statement statement posts event named codice_5 event one argument named id events handled event handlers example exception handling multithreading new thread launched statement like codice_6
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Programming language topics
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openospfd openospfd isc licensed implementation open shortest path first protocol network routing software suite allows ordinary general purpose computers used routers exchanging routes computer systems speaking ospf protocol openospfd developed esben nørby claudio jeker openbsd project companion daemon openbgpd software developed alternative packages quagga routing software suite licensed gpl openospfd developed openbsd ports exist freebsd netbsd design goals openospf include secure non-exploitable reliable lean easy use configuration language intended powerful easy enough users
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Operating systems
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narcissus javascript engine narcissus open source javascript engine written brendan eich also wrote first javascript engine spidermonkey name based mythical figure narcissus fell love relates fact javascript engine metacircular interpreter engine also written javascript albeit using non-standard extensions specific spidermonkey narcissus engine plugged firefox via zaphod add-on run scripts web pages since narcissus simpler code-base real javascript engines used prototype new language features less effort
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Programming language topics
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gpg4win gpg4win email file encryption package versions microsoft windows uses gnupg public-key cryptography data encryption digital signatures original creation gpg4win supported germany federal office information security however gpg4win included tools free open source software typically non-proprietary option privacy recommended windows users
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Computer security
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communications amp information services corps communications information services corps cis – formerly army corps signals – one combat support corps irish defence forces military ireland responsible installation maintenance operation communications information systems command control administration defence forces facilitation accurate real-time sharing intelligence army naval service air corps branches home overseas cis corps headquartered mckee barracks dublin comes command officer colonel rank known director cis corps formerly army corps signals communications information services corps responsible development operation information technology telecommunications systems support defence forces tasks also responsible coordinating communications – radio line – information systems communications research updating communications line modern developments operational requirements cis corps tasked utilising networking information technologies order dramatically increase defence force operational effectiveness provision timely accurate information appropriate commander along real time efficient sharing information intelligence army naval service air corps well multinational partners involved international peacekeeping actors required role includes development maintenance secure nationwide defence forces telecommunications network dftn support protected voice data services provision maintenance encrypted military communications equipment use defence forces personnel home abroad cis corps units dispersed throughout df giving communications support army brigades naval service air corps defence forces training centre dftc defence forces headquarters dfhq cis corps base workshops detailed maintenance research development conducted cis corps collar flash features angel gabriel messenger god behind signal shield caption cór comharthaíochta irish translation 'signals corps translation communications information services corps cór seirbhísí cumarsáide agus eolais communications information services cis corps works defence forces intelligence branch directorate military intelligence j2 regards signals intelligence sigint houses dedicated sigint element within corps df cis corps ability intercept monitor communications remotely collect data process irish legislation criminal justice surveillance act 2009 interception postal packets telecommunications messages regulation act 1993 provides defence forces legal authority conduct domestic intelligence operations involving espionage electronic communications stored electronic information order safeguard maintain security state cis corps along garda síochána national police force provide significant domestic support role national cyber security centre ncsc department communications climate action environment countering cyber-attacks protecting critical national infrastructure securing government communications cis responsible cyber security within defence forces maintains capability area purpose protecting networks users domestic foreign 2016 establishment computer incident response team cirt dfhq cis company revealed july 2015 leaked email correspondence hacking team – private italian spying eavesdropping software company – reportedly showed members irish cis corps discussions company purchase intrusion surveillance solutions lawful interception online communications monitoring incoming outgoing emails browsing activity skype calls remotely switching webcams microphones remotely taking control devices defence forces spokesperson said operational security reasons could comment specific elements activities cis corps confirmed goods services purchased company question soldiers join communications information services corps one following apprenticeship trades personnel basic military training cis school runs large number cis related courses including degree programme military communications cis technicians association institute technology carlow 3 sections cis school providing training areas operational procedures technical proficiency simulation procedural operations section proc/ops technical section simulation section dirt range digital indoor shooting range trainees assessed marksmanship skills various small arms weapons used df helps develop proficiencies methodically without firing live ammunition regular basis €1 million facility based department defence properties kilworth camp county cork reserve defence forces rdf units integrated permanent defence forces pdf units part single force concept
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Computer security
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hop software hop lisp-like programming language manuel serrano web 2.0 also name web broker server proxy implements language written bigloo scheme project funded inria hop stratified language means single program file contains instructions server client server executes cpu demanding computations operations require system privileges accessing files resources clients may many browsers cell phones etc dedicated executing actions related programming graphical user interfaces code snippet illustrates concepts given recent introduction hop currently exhibits number weaknesses
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Programming language topics
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minid minid electronic login system used secure range internet services norwegian public sector communication done minid encrypted secure information unauthorized usage everyone registered norwegian population register age 13 years create public id minid april 2010 2 million people living norway created user accounts minid create public id pin-codes norwegian tax administration needed purpose minid communicate electronic identity users authorized use electronic services secure way minid user database social security numbers pin-codes saved minid used access 50 online services various norwegian public agencies including norwegian labour welfare administration directorate taxes state educational loan agency public management e-government difi controller personal data handled minid agency public management egovernment norwegian direktoratet forvaltning og informasjons- og kommunikasjonsteknologi difi government agency subordinate norwegian ministry government administration reform responsible help public sector achieve quality efficiency user friendliness openness participation well helping public sector organized led good way good intersectoral cooperation users minid user profile contains mobile phone number and/or e-mail address data used administrate minid use e-mail address needed order send user temporary password forgets password phone number needed order send sms-code log temporary password user forgets password according law users claim full access handling personal data users also right information data handled saved correct delete inaccurate data users time choose delete user minid user profile deleted minid user database minid passes user social security number chosen language public services logs user go public services without new login
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Computer security
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sam spade software sam spade name windows software tool designed assist tracking sources e-mail spam also name free web service provides access similar online tools sam spade utility authored steve atkins 1997 named fictional character sam spade main features query tools last fully functional version website available 2004-02-26 since experienced various outage problems due blackholing samspade.org several rirs general heavy usage longer online url currently redirects https //tools.wordtothewise.com/ contains similar set web tools brand name wisetools hosted atkins email software business word wise
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Computer security
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squirrel systems squirrel systems burnaby-based point sale vendor specializing hospitality management systems squirrel based burnaby canada squirrel systems founded 1984 released first restaurant point sale system use integrated diskless touchscreen terminal order management originally wholly owned subsidiary sulcus hospitality technologies corporation 1998 sulcus merged eltrax systems incorporated nasdaq smallcap eltx squirrel currently wholly owned subsidiary marin investments ltd. one unique characteristics squirrel original product use hardened lcd touchscreen terminals unlike systems used keyboards crt monitors squirrel terminals moving parts easily adapted operating environment original squirrel terminals reached 35,000 installed units worldwide first integrate lcd panel credit card reader employee id reader cpu inside single unit later units would incorporate ip connectivity remote booting customized linux operating system java virtual machine 1998 squirrel systems released squirrel embedded linux sel customized distribution linux thin client terminal architecture sel several characteristics unique time development including primary support diskless workstations customized high-volume touchscreen drivers integrated java virtual machine hardware control two-stage booting windows server
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Distributed computing architecture
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bluetooth mesh networking bluetooth mesh networking conceived 2015 adopted protocol based upon bluetooth low energy allows many-to-many communication bluetooth radio defined mesh profile specification mesh model specification communication carried messages may 384 bytes long using segmentation reassembly sar mechanism messages fit one segment 11 bytes message starts opcode may single byte special messages 2 bytes standard messages 3 bytes vendor-specific messages every message source destination address determining devices process messages devices publish messages destinations single things groups things everything message sequence number protects network replay attacks message encrypted authenticated two keys used secure messages 1 network keys – allocated single mesh network 2 application keys – specific given application functionality e.g turning light vs reconfiguring light messages time live ttl time message received retransmitted ttl decremented limits number hops eliminating endless loops bluetooth mesh flood network based nodes relaying messages every relay node receives network packet authenticates known network key message cache ttl ≥ 2 retransmitted ttl ttl 1 message cache used prevent relaying messages recently seen bluetooth mesh layered architecture multiple layers yet determined practical limits bluetooth mesh technology limits built specification though version 1.0 bluetooth mesh specification following standard models model groups defined foundation models defined core specification two mandatory mesh nodes provisioning process installing device network mandatory step build bluetooth mesh network provisioning process provisioner securely distributes network key unique address space device provisioning protocol uses p256 elliptic curve diffie-hellman key exchange create temporary key encrypt network key information provides security passive eavesdropper also provides various authentication mechanisms protect network information active eavesdropper uses man-in-the-middle attack provisioning process key unique device known device key derived elliptic curve shared secret provisioner device provisioning process device key used provisioner encrypt messages specific device security provisioning process analyzed paper presented ieee cns 2018 conference provisioning performed using bluetooth gatt connection advertising using specific bearer
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Distributed computing architecture
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uswsusp uswsusp abbreviated userspace software suspend stylized µswsusp set userspace command-line utilities linux act primarily wrappers around linux kernel hibernation functionality implement sleep mode utility referred suspend ram hibernation utility referred suspend disk hybrid sleep utility referred suspend supports linux kernel versions 2.6.17 newer uswsusp supports image checksumming data compression disk encryption integration splashy fbsplash
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Operating systems
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goody video game goody platform game developed gonzalo gonzo suárez released 1987 spanish company opera soft game released amstrad cpc ms-dos msx zx spectrum platforms experienced thief john nelson brainner stravinsky known goody mission break bank spain equipped ladder goody explores catacombs city buildings along way may collect treasure needed purchase tools dynamite drill find access code main vault many objects enemies remote-control combat helicopters vipers gorillas policeman rodríguez ghosts evil moon try stop goody remake game linux windows titled goody remake released coptron game studios 2007 version brings brand new graphics music theme sound effects keeps gameplay atmosphere authentic goody version mobile phones created exelweiss published ebrain mobile 2007 called goody returns version uses 2.5d graphics video game called speakerman released 2019 art style game world heavily inspired goody
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Computer architecture
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virtual private server virtual private server vps virtual machine sold service internet hosting service virtual dedicated server vds also similar meaning vps runs copy operating system os customers may superuser-level access operating system instance install almost software runs os many purposes functionally equivalent dedicated physical server software-defined able much easily created configured priced much lower equivalent physical server however share underlying physical hardware vpses performance may lower depending workload executing virtual machines force driving server virtualization similar led development time-sharing multiprogramming past although resources still shared time-sharing model virtualization provides higher level security dependent type virtualization used individual virtual servers mostly isolated may run full-fledged operating system independently rebooted virtual instance partitioning single server appear multiple servers increasingly common microcomputers since launch vmware esx server 2001 physical server typically runs hypervisor tasked creating releasing managing resources guest operating systems virtual machines guest operating systems allocated share resources physical server typically manner guest aware physical resources save allocated hypervisor vps runs copy operating system customers superuser-level access operating system instance install almost software runs os however due number virtualization clients typically running single machine vps generally limited processor time ram disk space ultimately used decrease hardware costs condensing failover cluster single machine thus decreasing costs dramatically providing services server roles features generally designed operate isolation example windows server 2019 requires certificate authority domain controller exist independent servers independent instances windows server additional roles features adds areas potential failure well adding visible security risks placing certificate authority domain controller poses potential root access root certificate directly motivates demand virtual private servers order retain conflicting server roles features single hosting machine also advent virtual machine encrypted networks decreases pass-through risks might otherwise discouraged vps usage legitimate hosting server many companies offer virtual private server hosting virtual dedicated server hosting extension web hosting services several challenges consider licensing proprietary software multi-tenant virtual environments unmanaged self-managed hosting customer left administer server instance unmetered hosting generally offered limit amount data-transferred fixed bandwidth line usually unmetered hosting offered 10 mbit/s 100 mbit/s 1000 mbit/s high 10gbit/s means customer theoretically able use ~3 tb 10 mbit/s ~300 tb 1000 mbit/s line per month although practice values significantly less virtual private server shared bandwidth fair usage policy involved unlimited hosting also commonly marketed generally limited acceptable usage policies terms service offers unlimited disk space bandwidth always false due cost carrier capacities technological boundaries
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Computer security
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comparison triplestores comparison triplestores also known subject-predicate-object databases database management systems built database engines scratch others built top existing commercial relational database engines e.g. sql-based like early development online analytical processing olap databases intermediate approach allowed large powerful database engines constructed little programming effort initial phases triplestore development long-term though seems native triplestores advantage performance difficulty implementing triplestores sql although triples may thus stored implementing efficient querying graph-based rdf model e.g. mapping sparql onto sql queries difficult following table overview available triplestores technical implementation support sparql world wide web consortium w3c recommendations available application programming interfaces api
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Databases
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roger moore computer scientist roger d. moore november 16 1939 – march 21 2019 1973 recipient larry breed richard lathwell grace murray hopper award association computing machinery acm given work design implementation apl\ 360 setting new standards simplicity efficiency reliability response time interactive systems moore cofounder i. p. sharp associates held senior position company many years contributed subalgol compiler stanford university wrote algol 60 compiler ferranti-packard 6000 ict 1900 along work programming language apl also instrumental development ipsanet private packet switching data network roger d. moore born redlands california graduation worked operator burroughs 220 computer stanford time provided support larry breed ’ card stunt system also spent time studying burroughs 220 balgol compiler resulted butterfly described george forsythe grader program written balgol-language procedure compiled together procedure called butterfly written moore result relocatable machine-language procedure mechanism equating variables variables balgol program form balgol compiler ’ machine-language library procedures sin write read etc forsythe anticipated problem described bob braden balgol stanford outlived b220 hardware 1962 stanford contracted ibm obtain ibm 7090 campus computing created great consternation forsythe ’ office significant body faculty students familiar balgol high compiling speed bac vital academic environment subject community production-oriented system software offered ibm including slow fortran compiler cumbersome operating system would moved academic computing stanford backward several years address problem december 1961 moore hired forsythe work subalgol compiler ibm 7090 braden breed hired soon afterward completion subalgol hired ferranti-packard write algol 60 compiler fp6000 compiler part software package included sale fp6000 international computers tabulators december 1964 employees ferranti-packard computer group laid along six former fp employees formed i. p. sharp associates vice-president incorporation retirement 1989 1966 larry breed richard lathwell began work apl\360 interpreter lastly apl\360 owes much superior time-sharing performance roger d. moore i.p sharp associates toronto principally responsible supervisor design described extent deserves team received grace murray hopper award association computing machinery acm given work design implementation apl\360 setting new standards simplicity efficiency reliability response time interactive systems 1970 moore became project leader ipsa speculative dos/360 cobol compiler project although compiler satisfactory performance market accept ipsa offered apl time-sharing service starting 1969 1975 inflexibility communication error intolerance time-division multiplexing longer tolerable became chief architect ipsanet packet switching computer network 1976 system deployed north america london 1984 ipsa released sharp apl ibm pc package included 370 emulator written moore retiring ipsa early 1989 became interested opera chamber music along attending many performances supported concerts commissions advanced music education moore funded composing many works
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Programming language topics
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compaq portable series compaq first computers portable 'lunchbox 'luggable computers belong compaq portable series computers measured approximately 1×1 foot side approx 2½ ft wide products evolved laptops notebooks created offing new level portability caused market explode portables portable portable ii crt monitors others portable iii portable 386 flat single-color usually amber plasma displays portables came/could come internal hard disk drives .5 shock mount springs diskette drives usually 5 double- quadruple-density drives batteries and/or dual-isa expansion chassis one full-drive-height wide later products included mono color lcd screens battery powered
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Computer architecture
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helix headroom headroom dos context switching multitasking memory manager produced helix software company late 1980s early 1990s headroom managed multiple terminate stay resident programs first tsr manager allow sharing address space interrupts among tsrs dos headroom v1.0 released september 1988 april 1989 helix software released headroom v1.1 together headroom network extensions version added support network communications processes headroom network extensions intercepted buffered netbios tcp/ip communications requests allowing headroom manage network communications software mainframe terminal emulators e-mail programs background communications programs would continue programs swapped headroom would reactivate swapped-out programs activity occurred netbios tcp/ip sockets october 1989 helix software released headroom v2.0 included support microsoft windows lim ems v4.0 starting march 1990 version headroom bundled ast research rampage rampage plus sixpack memory expansion boards june 1990 helix software licensed technology headroom digital communications associates use irma boards irmalan software january 1991 helix released final version headroom v2.03 thereafter incorporated headroom features netroom lan memory manager decision caused market confusion
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Computer architecture
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zonnon zonnon programming language along oberon modula pascal language line jürg gutknecht author programming language zonnon general purpose programming language pascal modula-2 oberon family conceptual model based objects definitions implementations modules computing model concurrent based active objects interact via syntax controlled dialogs language developed eth zürich institute computer systems prof. jürg gutknecht zonnon introduces concept 'active objects used represent real world concurrent objects within computer programs zonnon language report written brian kirk director robinsons associates david lightfoot oxford brookes university working prof. jürg gutknecht eth zürich dr. eugene zueff евгений зуев moscow state university first book zonnon published n. i. lobachevsky state university nizhny novgorod a.k.a nizhni novgorod state university zonnon member pascal family languages two beneficial consequences general purpose language b immediately familiar pascal modula-2 oberon programmers pascal programs domain algorithms data structures successfully compiled zonnon compiler minor modifications however perspective “ programming-in-the-large ” zonnon much elaborate compared predecessors four different kinds program units zonnon objects modules definitions implementations first two instantiated runtime third compile time unit abstraction fourth unit composition brief characterization zonnon uses compositional inheritance model based aggregation typically object module composed number functional components presenting clients form abstract definition set definitions plus object ’ intrinsic interface set public elements object constitutes interface object clients zonnon allows adding behavior objects modules purpose notion active object imported active oberon language generalized towards unified model hierarchic activities activities encapsulated threads come two flavors local activities agent activities local activities express intrinsic object dynamics typical context block statements representing “ launch logic ” set mutually independent activities assumption end block acts barrier passed activities terminated agent activities control interoperability objects terms formal dialogs agent activity within “ callee ” object serves template formal dialog caller callee agent activities typically implement parser predefined syntax constitutes kind contract two communication partners formal dialogs generalization asynchronous method calls reflected form syntax borrowed ordinary method calls
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Programming language topics
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criticism windows xp criticism windows xp deals issues security performance presence product activation errors specific microsoft operating system windows xp windows xp criticized vulnerabilities due buffer overflows susceptibility malware viruses trojan horses worms nicholas petreley register notes windows xp first version windows reflect serious effort isolate users system users private files limited system privileges however users default receive administrator account provides unrestricted access underpinnings system administrator account compromised limit control asserted pc windows xp home edition also lacks ability administer security policies denies access local users groups utility microsoft executives stated release security patches often causes spread exploits flaws crackers figure problems patches fix launch attacks unpatched systems example august 2003 blaster worm exploited vulnerability present every unpatched installation windows xp capable compromising system even without user action may 2004 sasser worm spread using buffer overflow remote service present every installation patches prevent well-known worms already released microsoft increasingly widespread use service pack 2 greater use personal firewalls may also contribute making worms like less common many attacks windows xp systems come form trojan horse e-mail attachments contain worms user opens attachment unknowingly infect computer may e-mail worm people notable worms sort infected windows xp systems include mydoom netsky bagle discourage users running programs service pack 2 includes attachment execution service records origin files downloaded internet explorer received attachment outlook express user tries run program downloaded untrusted security zone windows xp service pack 2 prompt user warning spyware adware continuing problem windows xp versions windows spyware also concern microsoft regard service pack updates barry goff group product manager microsoft said spyware could cause computers freeze upon installation service pack 2 january 2005 microsoft released free beta version windows defender removes spyware adware computers windows xp offers useful security benefits windows update set install security patches automatically built-in firewall user n't install updates long time windows update icon displayed toolbar windows automatically install restart computer lead loss unsaved data user away computer updates installed service pack 2 enables firewall default also adds increased memory protection let operating system take advantage new execute technology built cpus amd64 allows windows xp prevent buffer overflow exploits april 8 2014 extended support windows xp ended means security vulnerabilities longer patched general advice given microsoft security specialists longer use windows xp light united states v. microsoft corp. case resulted microsoft convicted illegally abusing operating system monopoly overwhelm competition markets windows xp drawn fire integrating user applications windows media player windows messenger operating system well close ties windows live id microsoft account service 2001 procomp – group including several microsoft rivals including oracle sun netscape – claimed bundling distribution windows media player windows xp continuance microsoft anticompetitive behavior integration windows live id time microsoft passport windows xp example microsoft attempting gain monopoly web services claims rebutted association competitive technology act computing technology industry association comptia partially funded microsoft battle fought fronts side subject heated exchange oracle larry ellison microsoft bill gates microsoft responded freedom innovate web site pointing earlier versions windows microsoft integrated tools disk defragmenters graphical file managers tcp/ip stacks protest microsoft anti-competitive microsoft asserted tools moved special general usage therefore belonged operating system avoid possibility injunction might delayed release windows xp microsoft changed licensing terms allow pc manufacturers hide access internet explorer remove competitors dismissed trivial gesture later microsoft released utility part service pack 1 sp1 allows icons links bundled software internet explorer windows media player windows messenger confused similar-named windows live messenger formerly msn messenger removed components remain system microsoft maintains necessary key windows functionality html help system windows desktop removing completely may result unwanted consequences one critic shane brooks argued internet explorer could removed without adverse effects demonstrated product xplite dino nuhagic created nlite software remove many components xp prior installation product addition first release windows xp buy music online feature always used microsoft internet explorer rather web browser user may set his/her default pressure united states department justice microsoft released patch early 2004 corrected problem migrating windows 9x xp issue users dependent upon ms-dos although xp comes ability run dos programs virtual dos machine still trouble running many old dos programs largely windows nt system use dos base os windows nt architecture different windows 9x dos programs run natively xp notably programs rely direct access hardware run emulators dosbox virtual machines like vmware virtual pc virtualbox also applies programs require direct access certain common emulated hardware components like memory keyboard graphics cards serial ports dos emulators 32-bit versions windows xp run almost program designed previous microsoft operating system 64-bit versions xp major backward-compatibility issues old 16-bit windows programs require tool called ntvdm present 32-bit version os however true every version windows comes 32-bit 64-bit versions specific xp attempt reduce piracy microsoft introduced product activation windows xp activation required computer user activate microsoft either online phone within certain amount time order continue using operating system user computer system ever changes — example two relevant components computer upgraded — windows return unactivated state need activated within defined grace period user tried reactivate frequently system refuse activate online user must contact microsoft telephone obtain new activation code however activation applied retail system builder intended use small local pc builders copies windows royalty oem used large pc vendors copies instead locked special signature machine bios demand activation moved system whose motherboard signature volume license copies require activation led pirates simply using volume license copies volume license keys widely distributed internet addition activation windows xp service packs refuse install windows xp systems product keys known widely used unauthorized installations product keys either intended use one copy retail system builder one oem bios locked copies one company volume license copies included product however number volume licence product keys mentioned avoid need activation posted internet used large number unauthorized installations service packs contain list keys update copies windows xp use microsoft developed new key verification engine windows xp service pack 2 could detect illicit keys even never used outcry security consultants feared denying security updates illegal installations windows xp would wide-ranging consequences even legal owners microsoft elected disable new key verification engine service pack 2 checks small list commonly used keys service pack 1 means service pack 2 install copies windows xp use older set copied keys use keys posted recently may able update systems try curb piracy based leaked generated volume license keys microsoft introduced windows genuine advantage wga wga comprises two parts verification tool must used get certain downloads microsoft user notification system wga windows followed verification systems internet explorer 7 windows media player 11 windows defender microsoft office 2007 certain updates late 2007 microsoft removed wga verification installer internet explorer 7 saying purpose change make ie7 available windows users license key judged genuine displays nag screen regular intervals asking user buy license microsoft addition user access microsoft update restricted critical security updates new versions enhancements microsoft products longer able downloaded installed august 26 2008 microsoft released new wga activation program displays plain black desktop background computers failing validation background changed reverts 1 hour common criticisms wga included description critical security update causing automatic updates download without user intervention default settings behavior compared spyware phoning home microsoft every time computer connected internet failure inform end users exactly wga would installed rectified 2006 update failure provide proper uninstallation method beta testing users given manual removal instructions work final build sensitivity hardware changes cause repeated need reactivation hands developers also user connection internet phone difficult activate normally strictly speaking neither download install notifications mandatory user change automatic update settings allow choose updates may downloaded installation update already downloaded user choose accept supplemental eula provided notifications cases user also request update presented newer critical security updates may still installed update hidden however setting effect existing version notifications appear new version 2006 california resident brian johnson attempted bring class action lawsuit microsoft grounds windows genuine advantage notifications violated spyware laws state lawsuit dismissed 2010
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Operating systems
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web cache communication protocol web cache communication protocol wccp cisco-developed content-routing protocol provides mechanism redirect traffic flows real-time built-in load balancing scaling fault tolerance service-assurance failsafe mechanisms cisco ios release 12.1 later releases allow use either version 1 wccpv1 version 2 wccpv2 protocol wccp allows utilization cisco cache engines caches running wccp localize web traffic patterns network enabling content requests fulfilled locally traffic localization reduces transmission costs download time wccpv1 wccpv2 whilst originally designed cisco content cache appliance since added support products including vendors also implemented wccp support products allows clustering transparent deployment networks using cisco routers/switches without additional hardware wccp particular use vendors web cache/proxy/security appliances redirection web traffic list includes
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Internet protocols
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list web service frameworks list web service frameworks
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Web technology
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storage violation computing storage violation hardware software fault occurs task attempts access area computer storage permitted access storage violation instance consist reading writing freeing storage owned task common type storage violation known stack buffer overflow program attempts exceed limits set call stack also refer attempted modification memory owned another thread incomplete memory protection storage violations occur transaction systems cics circumstances possible write storage owned transaction violations reduced enabling features storage protection transaction isolation storage violations difficult detect program often run period time violation crashes example pointer freed area memory retained later reused causing error result efforts focus detecting violations occur rather later problem observed systems cics storage violations sometimes detected cics kernel use signatures tested see overlaid alternative runtime library may used better detect storage violations cost additional overhead programming languages use software bounds checking prevent occurrences program debugging software also detect violations testing
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Operating systems
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parity flag computer processors parity flag indicates numbers set bits odd even binary representation result last operation normally single bit processor status register example assume machine set parity flags indicates even parity result last operation 26 11010 binary parity flag would 0 since number set bits odd similarly result 10 1010 binary parity flag would 1 x86 processors parity flag reflects parity least significant byte result set number set bits ones even put another way parity bit set sum bits even according 80386 intel manual parity flag changed x86 processor family following instructions conditional jumps parity flag used e.g jp instruction jumps given target parity flag set jnp instruction jumps set flag may also read directly instructions pushf pushes flags register stack one common reason test parity flag check unrelated fpu flag fpu four condition flags c0 c3 tested directly must instead first copied flags register happens c0 placed carry flag c2 parity flag c3 zero flag c2 flag set e.g incomparable floating point values nan unsupported format compared fucom instructions
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Computer architecture
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boot image boot image type disk image computer file containing complete contents structure computer storage media transferred onto boot device allows associated hardware boot usually includes operating system utilities diagnostics well boot data recovery information also includes applications used organization-wide specialized image particular type user department called typically departmental boot image building image take days weeks involve complex decisions licensing permissions including passwords store boot image require users type requires experts software integration however built boot image simply copied onto devices patched within reasonable limits remains disposable case problems viruses particular possible unlike hard drive images may contain data et al pure boot images contain mission-critical data definition pure boot image contains data reproduced configurations off-the-shelf executables particular end-user data part boot image although operating systems require copy user preferences configuration files kept within boot image e.g microsoft windows registry utilities like norton ghost keep backup copy boot image quick re-imaging often called re-installation event problem thus avoiding need diagnose specific problem specific machine virtual machine infrastructure directly import export boot image direct installation bare metal i.e disk standard technique oems install identical copies operating system many identical machines boot image created virtual machine exported created one disk copied via boot image control infrastructure also makes virtual machine copies vmware vcenter converter instance lets users convert physical machines virtual machines free part company suite products make images easier back manage equivalents exist xen vm systems keeping boot image entirely separate disposable mandating boot image control organizations seek keep total cost operations including total cost ownership component low often organizations look uptime service one goal boot image control minimize number boot images used organization reduce support costs includes least many organizations use thin clients applications require high security involve unreliable users repurpose older machines continued use cascading strategy involves re-imaging older off-spec machines thin client boot images may continue use less demanding access-controlled applications
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Operating systems
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general dynamics mission systems general dynamics mission systems business unit american defense aerospace company general dynamics general dynamics mission systems integrates secure communication information systems technology general dynamics mission systems core manufacturing secure communications networks radios satellite technology defense cyber public safety intelligence communities general dynamics mission systems formed january 2015 general dynamics combined company c4 systems advanced information systems general dynamics c4 systems originally owned gte operated gte government systems general dynamics acquired gte government systems 1999 general dynamics advanced information systems provided mission-related systems development integration operations support general dynamics c4 systems leading integrator secure communications information systems technology lte general dynamics mission systems cell wheels cow deployable emergency lte solution used first responders public safety officials mobile cell tower able cover six square miles network created 2013 fortress lte technology includes virtual core network vcn enodeb base stations lte band 14 outdoor omni-directional user equipment c-band lte user equipment lte usb stick modem 4g evolved node b enodeb base stations software defined radios house digital baseband radio frequency rf circuits compact rugged mountable enclosure eliminate external interfaces reduce installation errors setup time range enodeb form factors offered different deployment scenarios support standard 4g lte band classes frequency ranges 400 mhz 6 ghz virtual core network vcn virtual 4g core network deployed wide range cots computing platforms vcn evolved packet core epc solution cyber cyber defense products include taclane network encryptors protecd r data-at-rest encryptors gem x™ encryptor manager pitbull operating system trusted network environment maritime strategic systems general dynamics mission systems acquired bluefin robotics february 2016 manufacturer unmanned undersea vehicles uuvs perform wide range missions u.s. military commercial customers independence-variant littoral combat ship lcs built general dynamics mission systems open architecture computing infrastructure open ci austal contracted build u.s. navy prime contractor subsequent 3.5 billion block buy 2010 august 2016 company successfully completed at-sea testing matador torpedo detection system build canada innovation program bcip tests conducted boat royal canadian navy ship matador acoustic processing system detecting tracking heavyweight anti-ship torpedoes radio communications cm-300/350 series version 2 radios latest additions air traffic control atc radios based faa nexcom segment 2 radio requirements rack mounted transmitter receiver systems specifically designed meet dynamic mission requirements air traffic control centers commercial airports military air stations range installations radio astronomy meerkat telescope array precursor telescope south africa ’ planned square kilometer array ska comprises 64 radio antennas south africa ’ northern cape province completed 2016 meerkat largest powerful radio telescope southern hemisphere ska array completed 2024 meerkat covers eight kilometers facilitate research cosmic magnetism galactic evolution large-scale structure cosmos dark matter nature transient radio sources among science projects space general dynamics mission systems provides integrated ground segments mobile user objective system muos used u.s. navy soon provide cell phone-like communications warfighters move intelligence systems tac-maas motion imagery processing exploitation system stanag 4609 nga motion imagery standard profile misp compliant international equivalent product d-vex sold australian-based subsidiary general dynamics mediaware win-t program win-t warfighter information network-tactical win-t army tactical communications system general dynamics army prime contractor win-t part general dynamics mission systems tactical voice data communications systems soldier network increment 1 fully deployed began fielding 2004 completed fielding 2012 november 2007 general dynamics announced 78 million order indefinite delivery quantity contract win-t increment 1 april 2015 general dynamics mission systems awarded 36 million army contract maintenance repair products related increment 1 june 2015 general dynamics secured contract increment 2 valued 219 million increment 2 includes additional capabilities mobile broadband increment 1 2 equipment remain field battalion company levels increment 3 completed
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Computer security
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bcode bcode identifier sent mobile phone/device used ticket/voucher/identification type token bcode sms message read electronically screen mobile device bcodes sent text message standard sms received 99 devices bcodes many uses advertising loyalty programs promotions ticketing bcode developed australian company 2003-2005 bcode simple sms text message looks something like text message read screen mobile phone/device decoded unique token id id used supply consumer unique experience
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Computer security
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apache kudu apache kudu free open source column-oriented data store apache hadoop ecosystem compatible data processing frameworks hadoop environment provides completeness hadoop storage layer enable fast analytics fast data open source project build apache kudu began internal project cloudera first version apache kudu 1.0 released 19 september 2016 kudu designed optimized olap workloads like hbase real-time store supports key-indexed record lookup mutation kudu differs hbase since kudu datamodel traditional relational model hbase schemaless kudu on-disk representation truly columnar follows entirely different storage design hbase/bigtable
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Distributed computing architecture
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telnet telnet application protocol used internet local area network provide bidirectional interactive text-oriented communication facility using virtual terminal connection user data interspersed in-band telnet control information 8-bit byte oriented data connection transmission control protocol tcp telnet developed 1969 beginning rfc 15 extended rfc 855 standardized internet engineering task force ietf internet standard std 8 one first internet standards name stands teletype network historically telnet provided access command-line interface usually operating system remote host including network equipment operating systems configuration utility including systems based windows nt however serious security concerns using telnet open network internet use purpose waned significantly favor ssh term telnet also used refer software implements client part protocol telnet client applications available virtually computer platforms telnet also used verb telnet means establish connection using telnet protocol either command line client graphical interface example common directive might change password telnet server log run passwd command cases user would telnetting unix-like server system network device router telnet client-server protocol based reliable connection-oriented transport typically protocol used establish connection transmission control protocol tcp port number 23 telnet server application telnetd listening telnet however predates tcp/ip originally run network control program ncp protocols even though telnet ad hoc protocol official definition march 5 1973 name actually referred teletype network protocol rfc 206 nic 7176 telnet makes connection clear many extensions made telnet negotiable options protocol architecture extensions adopted internet standards ietf documents std 27 std 32 extensions widely implemented others proposed standards ietf standards track see telnet best understood context user simple terminal using local telnet program known client program run logon session remote computer user communications needs handled telnet server program telnet initially developed 1969 users networked computers computer departments academic institutions large private government research facilities environment security nearly much concern became bandwidth explosion 1990s rise number people access internet extension number people attempting hack people servers made encrypted alternatives necessary experts computer security sans institute recommend use telnet remote logins discontinued normal circumstances following reasons security-related shortcomings seen usage telnet protocol drop rapidly especially public internet favor secure shell ssh protocol first released 1995 ssh practically replaced telnet older protocol used days rare cases access decades old legacy equipment support modern protocols ssh provides much functionality telnet addition strong encryption prevent sensitive data passwords intercepted public key authentication ensure remote computer actually claims happened early internet protocols extensions telnet protocol provide transport layer security tls security simple authentication security layer sasl authentication address concerns however telnet implementations support extensions relatively little interest implementing ssh adequate purposes note large number industrial scientific devices telnet available communication option built standard rs-232 port use serial server hardware appliance provide translation tcp/telnet data rs-232 serial data cases ssh option unless interface appliance configured ssh ibm 5250 3270 workstation emulation supported via custom telnet clients tn5250/tn3270 ibm servers clients servers designed pass ibm 5250 data streams telnet generally support ssl encryption ssh include 5250 emulation os/400 also known ibm port 992 default port secured telnet data octets except 0xff transmitted telnet sometimes used telnet client applications establish interactive raw tcp session due commonly mistaken belief session use iac functionally identical example user could make http request hand using command line version telnet client application follows case however network virtual terminal nvt rules requirement bare carriage return character cr ascii 13 followed nul ascii 0 character distinguish telnet protocol raw tcp sessions hand many systems possess true raw tcp clients netcat socat unix putty windows also used manually talk services without specialized client software nevertheless telnet still sometimes used debugging network services smtp irc http ftp pop3 servers issue commands server examine responses protocols ftp really uses telnet data format another difference telnet raw tcp session telnet 8-bit clean default 8-bit mode may negotiated high-bit-set octets may garbled mode requested requested non-telnet connection 8-bit mode named binary option intended transmit binary data characters though standard suggests interpretation codes 0000–0176 ascii offer meaning high-bit-set data octets attempt introduce switchable character encoding support like http nothing known actual software support
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Internet protocols
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microsoft dynamics 365 dynamics 365 product line enterprise resource planning erp customer relationship management crm applications announced microsoft july 2016 general release november 1 2016 part microsoft dynamics product line dynamics 365 sold two editions business edition small medium-sized enterprises smes smbs enterprise edition medium large organizations business edition includes financials application based project code-named 'madeira enterprise edition comprises dynamics crm applications field service sales project service automation customer service plus microsoft powerapps together microsoft premier erp product known dynamics 365 operations july 1 2017 dynamics 365 line repackaged crm applications called customer engagement plan erp application called microsoft dynamics 365 finance operations however available part unified operations plan also includes standalone applications dynamics 365 talent dynamics 365 retail together two plans form dynamics 365 plan microsoft dynamics 365 contains 11 core modules
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Distributed computing architecture
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active object symbian os active object framework callback-based form multitasking computer systems specifically form cooperative multitasking important feature symbian operating system within framework active objects may make requests asynchronous services e.g sending sms message asynchronous request made control returned calling object immediately i.e without waiting call complete caller may choose things returns control back operating system typically schedules tasks puts machine sleep makes request calling object includes reference asynchronous task completes operating system identifies thread containing requesting active object wakes active scheduler thread identifies object made request passes control back object implementation active objects symbian based around thread request semaphore incremented thread makes asynchronous request decremented request completed outstanding requests thread put sleep practice may many active objects thread task interact requesting things active objects threads may even request things implementation old idea developed handle software interruptions 70s operating system acting first object peripheral second one
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Operating systems
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text nailing text nailing tn information extraction method semi-automatically extracting structured information unstructured documents tn combines two concepts 1 human-interaction narrative text identify highly prevalent non-negated expressions 2 conversion expressions notes non-negated alphabetical-only representations create homogeneous representations traditional machine learning approaches text classification human expert required label phrases entire notes supervised learning algorithm attempts generalize associations apply new data contrast using non-negated distinct expressions eliminates need additional computational method achieve generalizability tn developed massachusetts general hospital tested multiple scenarios including extraction smoking status family history coronary artery disease identifying patients sleep disorders improve accuracy framingham risk score patients non-alcoholic fatty liver disease classify non-adherence type-2 diabetes comprehensive review regarding extracting information textual documents electronic health record available importance using non-negated expressions achieve increased accuracy text-based classifiers emphasized letter published communications acm october 2018 sample code extracting smoking status narrative notes using nailed expressions available github july 2018 researchers virginia tech university illinois urbana–champaign referred tn example progressive cyber-human intelligence pchi chen asch 2017 wrote machine learning situated peak inflated expectations soften subsequent crash “ trough disillusionment ” fostering stronger appreciation technology ’ capabilities limitations letter published communications acm beyond brute force emphasized brute force approach may perform better traditional machine learning algorithms applied text letter stated ... machine learning algorithms applied text rely assumption language includes infinite number possible expressions contrast across variety medical conditions observed clinicians tend use expressions describe patients conditions viewpoint published june 2018 concerning slow adoption data-driven findings medicine uri kartoun co-creator text nailing states ... text nailing raised skepticism reviewers medical informatics journals claimed relies simple tricks simplify text leans heavily human annotation tn indeed may seem like trick light first glance actually fairly sophisticated method finally caught attention adventurous reviewers editors ultimately accepted publication human in-the-loop process way generate features using domain experts using domain experts come features novel concept however specific interfaces method helps domain experts create features likely novel case features experts create equivalent regular expressions removing non-alphabetical characters matching smokesppd equal regular expression /smokes ^a-za-z *ppd/ using regular expressions features text classification novel given features classifier manually set threshold authors decided performance set documents classifier parameters classifier case threshold set manually given features documents almost machine learning algorithm able find threshold likely better one authors note using support vector machines svm hundreds documents give inferior performance specify features documents svm trained/tested fair comparison would use features document sets used manual threshold classifier
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Computational linguistics
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actiance actiance inc formerly known facetime communications american-based multinational corporation develops platforms required enable security management compliance unified communications web 2.0 social media channels headquartered redwood city california actiance supports leading social networks unified communications providers instant messaging platforms including facebook linkedin twitter aol google yahoo skype microsoft ibm cisco established 1997 actiance provided call center crm enablement instant messaging web chat email working closely aol yahoo msn microsoft actiance established industry first cap agreements certified access programs providing enhanced access public im networks 2000 actiance awarded innovative use real-time collaboration microsoft exchange conference 2001 company launched first compliance security solution im networks im auditor aimed specifically financial services sector needed comply government regulations enabled financial services organizations ability leverage power public instant messaging networks aol microsoft yahoo time-sensitive communications ensuring administrative controls place comply government regulations 2003 50 top 100 financial services firms worldwide needed comply securities exchange commission nasd record retention supervisory requirements using im auditor whilst others still questioning whether im place business networks actiance introduced first network appliance control use im enterprise 2004 capable preventing unauthorized im connections stopping peer-to-peer p2p filesharing sites kazaa grokster morpheus real time guardian rtg identified controlled access growing number applications traversed network without department ’ knowledge actiance continued add features rtg including support unified communication platforms microsoft office communications server ibm lotus sametime 2005 response growing threat worms spyware traversing im networks zero day defence system added 2008 actiance added new capabilities rtg ’ successor unified security gateway usg providing managers management security control 140 social networking sites 20,000 individual facebook widgets 400 web real-time applications making usg first secure web gateway combine content monitoring management security web 2.0 applications social networks instant messaging unified communications url filtering malware web antivirus protection 2010 saw another first actiance launched vantage imauditor ’ successor included stringent security compliance controls skype enterprise vantage provides granular security policy controls compliance features real time unified communications uc – providing management widest variety uc real time communications platforms including microsoft office communications server ibm lotus sametime public instant messaging platforms windows live skype web conferencing industry focused networks like reuters bloomberg yellowjacket later year include support microsoft lync server also 2010 actiance launched socialite enable security management compliance solution enterprises using social networks socialite provides granular control applications facebook linkedin twitter allows organisations comply regulatory compliance demanded organizations financial industry regulatory authority finra financial services authority available software-as-a-service deployment saas on-premises installation module usg socialite enable allows organizations control social media features communications users corporate network situated remotely january 2011 facetime communications announced changed name actiance following purchase facetime brand apple june 2011 actiance announced socialite engage new platform allows distributed teams share content engage clients prospects analyze impact content social media sites designed specifically enable investment insurance professionals distribute pre-approved content socialite engage enables organization manage social media secure compliant environment allowing users see glance content impact also leverages third party data sources internal systems data feeds highlights channels effective identifies potential sales leads
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Computer security
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cloud-based design manufacturing cloud-based design manufacturing cbdm refers service-oriented networked product development model service consumers able configure products services reconfigure manufacturing systems infrastructure-as-a-service iaas platform-as-a-service paas hardware-as-a-service haas software-as-a-service saas adapted original cloud computing paradigm introduced realm computer-aided product development cloud-based design manufacturing gaining significant momentum attention academia industry cloud-based design manufacturing includes two aspects cloud-based design cloud-based manufacturing another related concept cloud manufacturing general popular cloud-based design cbd refers networked design model leverages cloud computing service-oriented architecture soa web 2.0 e.g. social network sites semantic web technologies support cloud-based engineering design services distributed collaborative environments cloud-based manufacturing cbm refers networked manufacturing model exploits on-demand access shared collection diversified distributed manufacturing resources form temporary reconfigurable production lines enhance efficiency reduce product lifecycle costs allow optimal resource allocation response variable-demand customer generated tasking enabling technologies cloud-based design manufacturing include cloud computing web 2.0 internet things iot service-oriented architecture soa term cloud-based design manufacturing cbdm initially coined dazhong wu david rosen dirk schaefer georgia tech 2012 purpose articulating new paradigm digital manufacturing design innovation distributed collaborative settings main objective cbdm reduce time cost associated maintaining information communication technology ict infrastructures design manufacturing enhancing digital manufacturing design innovation distributed collaborative environments adapting rapidly changing market demands 2014 research group also published worldwide first two books subjects cloud-based design manufacturing cbdm social product development spd springer edited dirk schaefer cbdm exhibits following key characteristics cbdm differs traditional collaborative distributed design manufacturing systems web-based systems agent-based systems number perspectives including 1 computing architecture 2 data storage 3 sourcing process 4 information communication technology infrastructure 5 business model 6 programming model 7 communication similar cloud computing cbdm services categorized four major deployment models public cloud private cloud hybrid cloud community cloud
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Distributed computing architecture
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jean-louis gassée jean-louis gassée born march 1944 paris france business executive best known former executive apple computer worked 1981 1990 also founded inc. creators beos computer operating system leaving became chairman palmsource inc. november 2004 gassée worked six years hewlett-packard 1968 1974 responsible overseeing launching company ’ first desktop scientific computer development sales organization france promotion sales manager europe geneva switzerland 1974 1981 gassée served chief executive officer french affiliates data general exxon office systems 1981 gassée became director european operations apple computer 1985 learning steve jobs plan oust ceo john sculley memorial day weekend sculley china gassée preemptively informed board directors eventually led jobs resignation apple later sculley personally appointed gassée jobs old position head macintosh development gassée introduced several macintosh products on-stage late 1980s including macintosh portable 1989 also macintosh iifx product introductions often comical gassée less formal many executives wore tailored suits necessary often addressed employees wearing black lambskin leather jacket single diamond-stud earring idea licensing mac os companies use brought various members apple jean-louis refused give idea maintaining macintosh powerful computer present superior architectural roadmap future expansion computer although many companies interested use os equipment—they interested idea then-ceo made personal phone call sculley gassée would none idea licensing mac os shelved mid-80s gassée started skunkworks project create eventually became newton messagepad 1987 apple ceo john sculley published memoir odyssey hope inspiring excellence ordered hardback copy apple employee apple expense shortly afterward gassée ordered paperback copy fred brooks mythical man-month product-development employees hope inspiring good sense project management brooks gave lecture nearby de anza college room filled apple employees copies book told stories confirmed conclusions 1988 gassée became head apple advanced product development worldwide marketing rumors taking president apple sculley circling rumors concerning michael spindler also circulating one point 1990 number apple employees held demonstration marching around circles carrying signs lawn front one apple building petition apple management retain gassée usa today reporter saw demonstration asked employee employee well aware apple rules divulging trade secrets press succinctly explained issues next day usa today reported apple employees many wearing black leather jackets berets honor gassée demonstrated persuade management keep apple fact person wearing leather jacket brown goatskin a-2 beret person asked explain purpose demonstration 1989 gassée successfully killed claris project 'drama aimed start new brand sell low-end macintosh computers gassée argued consumers would continue willing pay price premium full macintosh experience despite gassée efforts supporters 1990 left apple forced sculley apple board members dissatisfied performance delivering new products spindler got top job 1991 gassée started new venture inc. ambitious goal creating entire new computer platform hardware software ground number apple employees left including steve sakoman developer apple newton developed new operating system optimized multiple cpus multithreaded applications became known simply operating system beos beos written dual-processor machine bebox later development releases beos ported run macintosh macintosh clone makers including power computing motorola signed deals ship beos hardware os finalized light stopped production bebox selling around 2000 units focused entirely development beos 1996 apple computer decided abandon copland project rewrite modernize macintosh operating system beos many features apple sought around christmas time offered buy 120 million later raising bid 200 million however despite estimates total worth approximately 80 million gassée held 275 million apple balked surprise move apple went purchase next company former co-founder steve jobs earlier left apple found 429 million high price justified apple getting jobs next engineers tow nextstep used basis new operating system mac os x return jobs apple withdrew license make macintosh clones intel assistance beos moved plan b port x86 platform arguably never grew past cult following sold enough copies nascent development user community several thousand programs available including several dozen commercial products beos also used embedded operating system multimedia production systems edirol teac level control systems however partially due behind-the-scenes pressure microsoft successful getting top-tier oems bundle beos hardware hitachi ast major europe time gassée saw fundamental success end 1999 focus shift giving desktop os away free commercial distributions sold third-party vendors similar linux distributions focus beia build beos specifically targeted internet appliances company lost several employees disagreed strategy desire work appliance os vendor interest beia least one shipping product based sony evilla market internet appliances proved nearly non-existent laid employees 2001 assets remaining engineers bought palm inc. 11 million august gassée stayed transition left january 2002 leaving gassée served president ceo computer access technology corporation catc company made network protocol analyzers left within year catc purchased fall 2004 lecroy corporation competitor gassée resurfaced general partner allegis capital venture capital fund based palo alto california still position november 2004 gassée became chairman palmsource inc. several former executives engineers still worked beos technology worked use palm os cobalt version 6 february 2006 major customers—including palm inc. itself—who committed using cobalt release march 2006 started writing blog french called le blog de jean-louis gassée english jean-louis gassée blog blog active month contains four entries seen google tech talk february 2007 2009 started contributing regularly monday note blog newsletter covering intersection media technology 2010 gassée says asked nokia consult future company suggested nokia fire ceo olli-pekka kallasvuo drop symbian operating system favour google android february 2019 gassée member medium
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Operating systems
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chosen-plaintext attack chosen-plaintext attack cpa attack model cryptanalysis presumes attacker obtain ciphertexts arbitrary plaintexts goal attack gain information reduces security encryption scheme modern ciphers aim provide semantic security also known ciphertext indistinguishability chosen-plaintext attack therefore design generally immune chosen-plaintext attacks correctly implemented chosen-plaintext attack adversary possibly adaptively ask ciphertexts arbitrary plaintext messages formalized allowing adversary interact encryption oracle viewed black box attacker ’ goal reveal part secret encryption key may seem infeasible practice attacker could obtain ciphertexts given plaintexts however modern cryptography implemented software hardware used diverse range applications many cases chosen-plaintext attack often feasible see also practice chosen-plaintext attacks become extremely important context public key cryptography encryption key public attackers encrypt plaintext choose two forms chosen-plaintext attacks general batch chosen-plaintext attack carried follows consider following extension situation last step cipher indistinguishable encryptions chosen-plaintext attack running experiment =1 adversary ca n't guess correctly probability non-negligibly better 1/2 following examples demonstrate ciphers meet security definitions may broken chosen-plaintext attack following attack caesar cipher allows full recovery secret key intricate complex encryption methodologies decryption method becomes resource-intensive however core concept still relatively following attack one-time pad allows full recovery secret key suppose message length key length equal world war ii us navy cryptanalysts discovered japan planning attack location referred af believed af might midway island locations hawaiian islands codewords began prove hypothesis af corresponded midway island asked us forces midway send plaintext message low supplies japanese intercepted message immediately reported superiors af low water confirming navy hypothesis allowing position force win battle also world war ii allied codebreakers bletchley park would sometimes ask royal air force lay mines position n't abbreviations alternatives german naval system grid reference hope germans seeing mines would use enigma machine encrypt warning message mines clear message removed giving allies enough information message break german naval enigma process planting known-plaintext called gardening allied codebreakers also helped craft messages sent double agent juan pujol garcía whose encrypted radio reports received madrid manually decrypted re-encrypted enigma machine transmission berlin helped codebreakers decrypt code used second leg supplied original text modern day chosen-plaintext attacks cpas often used break symmetric ciphers considered cpa-secure symmetric cipher must vulnerable chosen-plaintext attacks thus important symmetric cipher implementors understand attacker would attempt break cipher make relevant improvements chosen-plaintext attacks small part plaintext may need chosen attacker attacks known plaintext injection attacks chosen-plaintext attack powerful known-plaintext attack attacker directly target specific terms patterns without wait appear naturally allowing faster gathering data relevant cryptanalysis therefore cipher prevents chosen-plaintext attacks also secure known-plaintext ciphertext-only attacks however chosen-plaintext attack less powerful chosen-ciphertext attack attacker obtain plaintexts arbitrary ciphertexts cca-attacker sometimes break cpa-secure system example el gamal cipher secure chosen plaintext attacks vulnerable chosen ciphertext attacks unconditionally malleable
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Computer security
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scuttle software scuttle php/mysql-based open source social bookmarking application contains code php-based projects drupal jquery scuttle offers functionality social bookmarking websites tagging rss multiple languages security settings public private also supports bookmark imports delicious delicious api means programs widgets might also work backups available via xml mysql backend lacks administrator backend although one commercially available called scuttle plus advanced semantic scuttle provides anti-spam protection structured tags collaborative tag description
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Web technology
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winlinux winlinux linux distribution installer runs inside windows operating system also configuration tool run inside windows set hardware options linux os installed directory existing fat32 partition means ability share windows partition disk space latest version winlinux 2003 launched like windows application shortcut causes pc reboot winlinux exiting winlinux allow pc go back windows next bootup able run linux applications ships kde default desktop distribution currently inactive
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Operating systems
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interest flooding attack interest flooding attack ifa denial-of-service attack information-centric network content-centric networking ccn named data networking ndn attacker requests existing non-existing content order overload distribution infrastructure implemented sending interest packets resolved resolved fast enough thus lead malicious cpu memory consumption attack previously denoted open problem icn heuristic countermeasures available 2016 aubrey alston tamer refaei mitre corporation presented exact solution problem utilizes in-packet cryptographic mechanism remove ability high-volume interest traffic overload distribution infrastructure network
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Computer security
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exec amiga exec kernel amigaos 13 kb multitasking microkernel enabled pre-emptive multitasking little 256 kb memory supplied first amiga 1000s exec provided functions multitasking memory management handling interrupts dynamic shared libraries acts scheduler tasks running system providing pre-emptive multitasking prioritized round-robin scheduling exec also provides access libraries high-level inter-process communication via message passing comparable microkernels performance problems need copy messages address spaces since amiga one address space exec message passing quite efficient fixed memory address amiga software address 4 pointer codice_1 used access libraries exec designed implemented carl sassenrath unlike newer modern operating systems exec kernel run privileged contemporary operating systems 68000 atari tos sunos used trap instructions invoke kernel functions made kernel functions run 68000 supervisor mode user software ran unprivileged user mode contrast exec function calls made library jump table kernel code normally executes user mode whenever supervisor mode needed either kernel user programs library functions codice_2 codice_3 used one limit exec kernel uncooperative program could disable multitasking long time indefinitely invoking exec calls codice_4 codice_5 later invocation corresponding codice_6 codice_7 causing environment run one task multitasking could also disabled programs software bug intent modify exec data structures code stored random-access memory ram possibly due lack memory management unit mmu support even limits exec satisfies definition preemptive scheduling algorithm using preemptive scheduling routine basing interrupt intervals clock linux kernel developer linus torvalds described amiga design cooperative even though uses preemptive scheduling policy reason argued lack memory protection tasks meant task could hinder system operating preemptively tasks would need choose stop preemptive mechanism would reduce kind inverted cooperative system kind conflation protection scheduler policy nonstandard execsg second generation kernel used amigaos 4 kernel licensed hyperion entertainment thomas frieden hans-jörg frieden exposes functions structures commodore amiga exec kernel runs powerpc cpus ultimate origin execsg unspecified
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Computer architecture
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termium plus termium plus electronic terminological database operated maintained translation bureau government canada database offers millions english french terms various specialized fields terms spanish portuguese also available multilingual database termium plus initially developed université de montréal october 1970 database initially named banque de terminologie de l ’ université de montréal btum direction marcel paré vision produce flexible bilingual language file would available btum initially funded private donors government subsidies grew help professionals field translation following years 1975 btum able obtain data user responses collaboration language services bell canada end 1974 however translation bureau canadian secretary state department showed interest operation btum goal translation bureau time standardize terminology throughout public service well federal public administration january 1976 canadian secretary state department officially acquired btum renamed database termium terminologie université de montréal system transferred central computer federal government ottawa began integrate approximately 175,000 files btum initially compiled files translation bureau working years follow bureau began sorting process along input process onto computer database grew 900,000 records 1987 terminological records grew termium database canadian government received proposal 1985 toronto-based company launch termium cd-rom format order make database accessible users fall 1987 pilot project cd-rom launched investigate responses users included services translation bureau private canadian companies data compilation investigation bureau incorporated indexing system improve speed accuracy term extraction 1990 termium cd-rom commercially available subscription annual fee 1,100 1,500 updates released every three four months 1996 termium cd-rom received award atio association translators interpreters ontario october 2009 termium plus array language tools language portal canada launched free online access termium initially developed contain terminological records canada ’ official languages english french system upgraded third-generation version 1985 contained records languages spanish order accommodate growing range users worth noting however “ multilingual ” records term source language would english french equivalent non-official language currently vast collection specialized domains fields covered termium plus ranging administration including appellations arts sciences law justice aside millions entries recorded termium plus database also contains writing tools english french language canadian style writing style guide dictionnaire des cooccurrences guide french collocations archived glossaries well link language portal canada containing various french english writing resources
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Computational linguistics
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verilog verilog standardized ieee 1364 hardware description language hdl used model electronic systems commonly used design verification digital circuits register-transfer level abstraction also used verification analog circuits mixed-signal circuits well design genetic circuits 2009 verilog standard ieee 1364-2005 merged systemverilog standard creating ieee standard 1800-2009 since verilog officially part systemverilog language current version ieee standard 1800-2017 hardware description languages verilog similar software programming languages include ways describing propagation time signal strengths sensitivity two types assignment operators blocking assignment non-blocking assignment non-blocking assignment allows designers describe state-machine update without needing declare use temporary storage variables since concepts part verilog language semantics designers could quickly write descriptions large circuits relatively compact concise form time verilog introduction 1984 verilog represented tremendous productivity improvement circuit designers already using graphical schematic capture software specially written software programs document simulate electronic circuits designers verilog wanted language syntax similar c programming language already widely used engineering software development like c verilog case-sensitive basic preprocessor though less sophisticated ansi c/c++ control flow keywords if/else case etc equivalent operator precedence compatible c. syntactic differences include required bit-widths variable declarations demarcation procedural blocks verilog uses begin/end instead curly braces many minor differences verilog requires variables given definite size c sizes assumed 'type variable instance integer type may 8 bits verilog design consists hierarchy modules modules encapsulate design hierarchy communicate modules set declared input output bidirectional ports internally module contain combination following net/variable declarations wire reg integer etc concurrent sequential statement blocks instances modules sub-hierarchies sequential statements placed inside begin/end block executed sequential order within block however blocks executed concurrently making verilog dataflow language verilog concept 'wire consists signal values 4-state 1 0 floating undefined signal strengths strong weak etc. system allows abstract modeling shared signal lines multiple sources drive common net wire multiple drivers wire readable value resolved function source drivers strengths subset statements verilog language synthesizable verilog modules conform synthesizable coding style known rtl register-transfer level physically realized synthesis software synthesis software algorithmically transforms abstract verilog source netlist logically equivalent description consisting elementary logic primitives flip-flops etc available specific fpga vlsi technology manipulations netlist ultimately lead circuit fabrication blueprint photo mask set asic bitstream file fpga verilog one first popular hardware description languages invented created prabhu goel phil moorby chi-lai huang douglas warmke late 1983 early 1984 chi-lai huang earlier worked hardware description lalsd language developed professor s.y.h su phd work wording process automated integrated design systems later renamed gateway design automation 1985 hardware modeling language gateway design automation purchased cadence design systems 1990 cadence full proprietary rights gateway verilog verilog-xl hdl-simulator would become de facto standard verilog logic simulators next decade originally verilog intended describe allow simulation automated synthesis subsets language physically realizable structures gates etc developed language achieved widespread usage verilog portmanteau words verification logic increasing success vhdl time cadence decided make language available open standardization cadence transferred verilog public domain open verilog international ovi known accellera organization verilog later submitted ieee became ieee standard 1364-1995 commonly referred verilog-95 time frame cadence initiated creation verilog-a put standards support behind analog simulator spectre verilog-a never intended standalone language subset verilog-ams encompassed verilog-95 extensions verilog-95 submitted back ieee cover deficiencies users found original verilog standard extensions became ieee standard 1364-2001 known verilog-2001 verilog-2001 significant upgrade verilog-95 first adds explicit support 2 complement signed nets variables previously code authors perform signed operations using awkward bit-level manipulations example carry-out bit simple 8-bit addition required explicit description boolean algebra determine correct value function verilog-2001 succinctly described one built-in operators » generate/endgenerate construct similar vhdl generate/endgenerate allows verilog-2001 control instance statement instantiation normal decision operators case/if/else using generate/endgenerate verilog-2001 instantiate array instances control connectivity individual instances file i/o improved several new system tasks finally syntax additions introduced improve code readability e.g always named parameter override c-style function/task/module header declaration verilog-2001 version verilog supported majority commercial eda software packages confused systemverilog verilog 2005 ieee standard 1364-2005 consists minor corrections spec clarifications new language features uwire keyword separate part verilog standard verilog-ams attempts integrate analog mixed signal modeling traditional verilog advent hardware verification languages openvera verisity e language encouraged development superlog co-design automation inc acquired synopsys foundations superlog vera donated accellera later became ieee standard p1800-2005 systemverilog systemverilog superset verilog-2005 many new features capabilities aid design verification design modeling 2009 systemverilog verilog language standards merged systemverilog 2009 ieee standard 1800-2009 current version ieee standard 1800-2017 simple example two flip-flops follows operator verilog another aspect hardware description language opposed normal procedural language known non-blocking assignment action register always block executed means order assignments irrelevant produce result flop1 flop2 swap values every clock assignment operator referred blocking assignment assignment used purposes logic target variable updated immediately example statements used blocking operator instead flop1 flop2 would swapped instead traditional programming compiler would understand simply set flop1 equal flop2 subsequently ignore redundant logic set flop2 equal flop1 example counter circuit follows example delays always clause illustrates type method use i.e executes whenever entities list b e changes one changes immediately assigned new value due blocking assignment b assigned new value afterward taking account new value delay 5 time units c assigned value b value c e tucked away invisible store 6 time units assigned value tucked away signals driven within process initial always block must type reg signals driven outside process must type wire keyword reg necessarily imply hardware register definition constants verilog supports addition width parameter basic syntax width bits base letter number examples several statements verilog analog real hardware e.g display consequently much language used describe hardware examples presented classic subset language direct mapping real gates next interesting structure transparent latch pass input output gate signal set pass-through captures input stores upon transition gate signal hold output remain stable regardless input signal gate set hold example pass-through level gate would value clause true i.e gate 1 read gate true din fed latch_out continuously clause false last value latch_out remain independent value din flip-flop next significant template verilog d-flop simplest modeled significant thing notice example use non-blocking assignment basic rule thumb use posedge negedge statement within always clause variant d-flop one asynchronous reset convention reset state first clause within statement next variant including asynchronous reset asynchronous set condition convention comes play i.e reset term followed set term note model used model set/reset flip flop simulation errors result consider following test sequence events 1 reset goes high 2 clk goes high 3 set goes high 4 clk goes high 5 reset goes low followed 6 set going low assume setup hold violations example always statement would first execute rising edge reset occurs would place q value 0 next time always block executes would rising edge clk would keep q value 0 always block executes set goes high reset high forces q remain 0 condition may may correct depending actual flip flop however main problem model notice reset goes low set still high real flip flop cause output go 1 however model occur always block triggered rising edges set reset — levels different approach may necessary set/reset flip flops final basic variant one implements d-flop mux feeding input mux d-input feedback flop allows gated load function note initial blocks mentioned description split fpga asic synthesis tools structure fpga tools allow initial blocks reg values established instead using reset signal asic synthesis tools n't support statement reason fpga initial state something downloaded memory tables fpga asic actual hardware implementation two separate ways declaring verilog process always initial keywords always keyword indicates free-running process initial keyword indicates process executes exactly constructs begin execution simulator time 0 execute end block always block reached end rescheduled common misconception believe initial block execute always block fact better think initial-block special-case always-block one terminates completes first time classic uses two keywords two significant additional uses common always keyword without ... sensitivity list possible use always shown always keyword acts similar c language construct 1 .. sense execute forever interesting exception use initial keyword addition forever keyword example functionally identical always example fork/join pair used verilog create parallel processes statements blocks fork/join pair begin execution simultaneously upon execution flow hitting fork execution continues join upon completion longest running statement block fork join way written possible either sequences abc bac print order simulation first write second write depends simulator implementation may purposefully randomized simulator allows simulation contain accidental race conditions well intentional non-deterministic behavior notice vhdl dynamically spawn multiple processes like verilog order execution n't always guaranteed within verilog best illustrated classic example consider code snippet printed values b depending order execution initial blocks could zero zero alternately zero arbitrary uninitialized value display statement always execute assignment blocks completed due 1 delay note operators shown order precedence ieee 1364 standard defines four-valued logic four states 0 1 z high impedance x unknown logic value competing vhdl dedicated standard multi-valued logic exists ieee 1164 nine levels system tasks available handle simple i/o various design measurement functions simulation system tasks prefixed distinguish user tasks functions section presents short list frequently used tasks means comprehensive list pli provides programmer mechanism transfer control verilog program function written c language officially deprecated ieee std 1364-2005 favor newer verilog procedural interface completely replaces pli pli vpi enables verilog cooperate programs written c language test harnesses instruction set simulators microcontroller debuggers example provides c functions codice_1 codice_2 used write read argument current verilog task function respectively information verilog simulators see list verilog simulators
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Programming language topics
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dicom digital imaging communications medicine dicom standard communication management medical imaging information related data dicom commonly used storing transmitting medical images enabling integration medical imaging devices scanners servers workstations printers network hardware picture archiving communication systems pacs multiple manufacturers widely adopted hospitals making inroads smaller applications like dentists doctors offices dicom files exchanged two entities capable receiving image patient data dicom format different devices come dicom conformance statements clearly state dicom classes support standard includes file format definition network communications protocol uses tcp/ip communicate systems national electrical manufacturers association nema holds copyright published standard developed dicom standards committee whose members also partly members nema also known nema standard ps3 iso standard 12052:2017 health informatics -- digital imaging communication medicine dicom including workflow data management dicom used worldwide store exchange transmit medical images dicom central development modern radiological imaging dicom incorporates standards imaging modalities radiography ultrasonography computed tomography ct magnetic resonance imaging mri radiation therapy dicom includes protocols image exchange e.g. via portable media dvds image compression 3-d visualization image presentation results reporting dicom standard divided related independent parts dicom standard developed american college radiology acr national electrical manufacturers association nema beginning 1980s difficult anyone manufacturers computed tomography magnetic resonance imaging devices decode images machines generated radiologists medical physicists wanted use images dose-planning radiation therapy acr nema joined forces formed standard committee 1983 first standard acr/nema 300 entitled digital imaging communications released 1985 soon release became clear improvements needed text vague internal contradictions 1988 second version released version gained acceptance among vendors image transmission specified dedicated 2 pair cable eia-485 first demonstration acr/nema v2.0 interconnectivity technology held georgetown university may 21–23 1990 six companies participated event dejarnette research systems general electric medical systems merge technologies siemens medical systems vortech acquired kodak year 3m commercial equipment supporting acr/nema 2.0 presented annual meeting radiological society north america rsna 1990 vendors many soon realized second version also needed improvement several extensions acr/nema 2.0 created like papyrus developed university hospital geneva switzerland spi standard product interconnect driven siemens medical systems philips medical systems first large-scale deployment acr/nema technology made 1992 us army air force part mdis medical diagnostic imaging support program based ft. detrick maryland loral aerospace siemens medical systems led consortium companies deploying first us military pacs picture archiving communications system major army air force medical treatment facilities teleradiology nodes large number us military clinics dejarnette research systems merge technologies provided modality gateway interfaces third party imaging modalities siemens spi network veterans administration navy also purchased systems contract 1993 third version standard released name changed digital imaging communications medicine abbreviated dicom new service classes defined network support added conformance statement introduced initially dicom standard referred dicom 3.0 distinguish predecessors dicom constantly updated extended since 1993 intent changes backward compatible except rare cases earlier specification incorrect ambiguous officially version standard except current standard hence 3.0 version number longer used minor versions standard e.g. thing dicom 3.1 current plans develop new incompatible version standard i.e. dicom 4.0 standard referenced without specification date release particular published edition except specific conformance requirements invoked depend retired feature longer documented current standard dicom standard achieved near universal level acceptance amongst medical imaging equipment vendors healthcare organizations standard limitations dicom standard directed addressing technical interoperability issues medical imaging framework architecture achieving useful clinical workflow integrating healthcare enterprise ihe initiative layered top dicom hl-7 defines profiles select features standards implement transactions specific medical imaging interoperability use cases though always internet compatible based transport tcp time increasing need support port 80 http transport make use easier within web browser recently family dicom restful web services defined allow mobile device friendly access dicom objects services include wado-rs stow-rs qido-rs together constitute dicomweb initiative derivations dicom standard application areas include diconde digital imaging communication nondestructive evaluation established 2004 way nondestructive testing manufacturers users share image data dicos digital imaging communication security established 2009 used image sharing airport security dicom groups information data sets example file chest x-ray image may contain patient id within file image never separated information mistake similar way image formats jpeg also embedded tags identify otherwise describe image dicom data object consists number attributes including items name id etc. also one special attribute containing image pixel data i.e logically main object header merely list attributes including pixel data single dicom object one attribute containing pixel data many modalities corresponds single image however attribute may contain multiple frames allowing storage cine loops multi-frame data another example nm data nm image definition multi-dimensional multi-frame image cases three- four-dimensional data encapsulated single dicom object pixel data compressed using variety standards including jpeg lossless jpeg jpeg 2000 run-length encoding rle lzw zip compression used whole data set pixel data rarely implemented dicom uses three different data element encoding schemes explicit value representation vr data elements vrs ob ow sq ut un format data element group 2 bytes element 2 bytes vr 2 bytes lengthinbyte 2 bytes data variable length explicit data elements implicit data elements see section 7.1 part 5 dicom standard basic format used applications including network file usage written file usually true header containing copies key attributes details application wrote added promote identical grayscale image display different monitors consistent hard-copy images various printers dicom committee developed lookup table display digitally assigned pixel values use dicom grayscale standard display function gsdf images must viewed printed devices lookup curve devices calibrated gsdf curve addition value representation attribute also value multiplicity indicate number data elements contained attribute character string value representations one data element encoded successive data elements separated backslash character dicom consists services involve transmission data network file format offline media later addition standard dicom store service used send images persistent objects structured reports etc picture archiving communication system pacs workstation dicom storage commitment service used confirm image permanently stored device either redundant disks backup media e.g burnt cd service class user scu similar client modality workstation etc. uses confirmation service class provider scp similar server archive station instance make sure safe delete images locally enables workstation find lists images objects retrieve picture archiving communication system dicom modality worklist service provides list imaging procedures scheduled performance image acquisition device sometimes referred modality system items worklist include relevant details subject procedure patient id name sex age type procedure equipment type procedure description procedure code procedure order referring physician accession number reason exam image acquisition device ct scanner queries service provider ris get information presented system operator used imaging device populate details image metadata prior use dicom modality worklist service scanner operator required manually enter relevant details manual entry slower introduces risk misspelled patient names data entry errors complementary service modality worklist enables modality send report performed examination including data images acquired beginning time end time duration study dose delivered etc helps give radiology department precise handle resource acquisition station use also known mpps service allows modality better coordinate image storage servers giving server list objects send actually sending objects dicom print service used send images dicom printer normally print x-ray film standard calibration defined dicom part 14 help ensure consistency various display devices including hard copy printout format off-line media files specified part 10 dicom standard files sometimes referred part 10 files dicom restricts filenames dicom media 8 characters systems wrongly use 8.3 conform standard information must extracted names ps3.10 section 6.2.3.2 common source problems media created developers read specifications carefully historical requirement maintain compatibility older existing systems also mandates presence media directory dicomdir file provides index summary information dicom files media dicomdir information provides substantially greater information file filename could less need meaningful file names dicom files typically .dcm file extension part dicom media requires without extension mime type dicom files defined rfc 3240 application/dicom uniform type identifier type dicom files org.nema.dicom also ongoing media exchange test connectathon process cd media network operation organized ihe organization core application dicom standard capture store distribute medical images standard also provides services related imaging managing imaging procedure worklists printing images film digital media like dvds reporting procedure status like completion imaging acquisition confirming successful archiving images encrypting datasets removing patient identifying information datasets organizing layouts images review saving image manipulations annotations calibrating image displays encoding ecgs encoding cad results encoding structured measurement data storing acquisition protocols dicom information object definitions encode data produced wide variety imaging device types including ct computed tomography mri magnetic resonance imaging ultrasound x-ray fluoroscopy angiography mammography breast tomosynthesis pet positron emission tomography spect single photon emission computed tomography endoscopy microscopy whole slide imaging oct optical coherence tomography dicom also implemented devices associated images imaging workflow including pacs picture archiving communication systems image viewers display stations cad computer-aided detection/diagnosis systems 3d visualization systems clinical analysis applications image printers film scanners media burners export dicom files onto cds dvds etc media importers import dicom files cds dvds usbs etc ris radiology information systems vna vendor-neutral archives emr electronic medical record systems radiology reporting systems many fields medicine dedicated working group within dicom dicom applicable field medicine imaging prevalent including radiology cardiology oncology nuclear medicine radiotherapy neurology orthopedics obstetrics gynecology ophthalmology dentistry maxillofacial surgery dermatology pathology clinical trials veterinary medicine medical/clinical photography dicom reserved following tcp udp port numbers internet assigned numbers authority iana 104 well-known port dicom transmission control protocol tcp user datagram protocol udp since 104 reserved subset many operating systems require special privileges use 2761 registered port dicom using integrated secure communication layer iscl tcp udp 2762 registered port dicom using transport layer security tls tcp udp 11112 registered port dicom using standard open communication tcp udp standard recommends require use port numbers according paper presented international symposium 2008 dicom standard problems related data entry major disadvantage dicom standard possibility entering probably many optional fields disadvantage mostly showing inconsistency filling fields data image objects often incomplete fields left blank filled incorrect data hand file format admits executable code maybe exists possibility contains malware dvtk open source project testing validating diagnosing communication protocols scenarios medical environments supports dicom hl7 ihe integration profiles health level 7 non-profit organization involved development international healthcare informatics interoperability standards hl7 dicom manage joint working group harmonize areas two standards overlap address imaging integration electronic medical record integrating healthcare enterprise ihe industry sponsored non-profit organization profiles use standards address specific healthcare use cases dicom incorporated variety imaging related ihe profiles systematized nomenclature medicine snomed systematic computer-processable collection medical terms human veterinary medicine provide codes terms synonyms definitions cover anatomy diseases findings procedures microorganisms substances etc dicom data makes use snomed encode relevant concepts xnview supports codice_1 codice_2 mime type codice_3
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Internet protocols
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macfusion macfusion open-source network file-system client based fuse curlftpfs sshfs 64-bit macintosh computers using 64-bit os macfusion needs instead old unmaintained macfuse one newer implementations fuse like osxfuse fuse4x
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Computer file systems
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xiafs xiafs file system linux kernel conceived developed frank xia based minix file system today obsolete use except possibly historic installations linux originally used minix file system number limitations example length filenames limited 14 characters partition size limited 64 mb replace minix file system extended file system ext developed however ext retained problems poor performance lack date stamps two contenders replacing ext quickly developed ext2 xiafs two file systems included standard kernel december 1993 linux 0.99.15 ext2 xiafs goal offer good performance reasonable limitations fixing flaws ext initially xiafs stable ext2 fairly minimalistic modification minix file system well suited future extension end result xiafs changed little ext2 evolved considerably rapidly improving stability performance adding extensions ext2 shakedown time quickly became standard file system linux since ext2 developed mature robust file system xiafs original ext removed linux version 2.1.21 longer use maintained ext2 ext3 successor ext4 linux kernel exercise computer history file system tutorial xiafs ported modern linux 2013 xiafs less powerful offered less functionality ext2 maximum size file 64 mib maximum size partition 2 gib improvement ext measure ext2 xiafs used less disk space control structures greater stability time
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Computer file systems
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sparcstation 20 sparcstation 20 a.k.a ss20 codename kodiak discontinued sun microsystems workstation based supersparc hypersparc cpu last model sparcstation family sun pizza box computers superseded ultrasparc design 1995 sparcstation 20 dual 50 mhz mbus ports allow use faster cpus sparcstation 10 two dual-cpu modules updated firmware sparcstation 20 supports maximum 4 cpus fastest cpu produced sparcstation 20 200 mhz ross hypersparc prom sparcstation 20 determines cpu compatibility version 2.25r last prom release sparcstation 20 sparcstation 20 8 200-pin dsimm slots supports maximum 512 mb memory 64 mb modules memory modules sparcstation 20 compatible sparcstation 10 sun ultra 1 computers sun4m sun4u families physically incompatible simm slots found pc computers 2 8 simm slots wider others used non-memory peripherals like caching nvsimm video vsimm cards sparcstation 20 two internal sca bays external scsi connector two bays cd-rom floppy drives earlier revisions sparcstation20 case contain cd-rom floppy bays slightly shorter standard 3.5 bay regular devices intended pc compatible computers usually fit later revisions sparcstation20 sparcstation5 narrower slot floppy drive more-standard cd-rom fit scsi host controller integrated motherboard sparcstation 20 support ide devices limitation releases openboot prom sparcstation 20 prevents booting point disk past 2 gigabyte mark sparcstation 20 one integrated amd lance 10baset ethernet interface additional ethernet interfaces added sbus card sparcstation 20 built 13w3 video socket driven optional sx cg14 framebuffer built onto vsimm vsimm available 4mb 8mb capacity capable 1280x1024 8mb 1152x900 4mb 24-bit color two vsimms installed auxiliary video board must also installed provide second 13w3 video socket alternatively sbus cards used including zx leo turbo gx cg6 others sparcstation 20 integrated sound 4 standard 3.5 mm audio jacks headphones microphone line line sparcstation 20 uses battery-backed nvram module hold data system host id serial number mac address battery chip dies nvram module must replaced modified use external battery nvram must reprogrammed mac address host id optionally m48t08-100pc1 used sunos 4.1.3_u1b onwards solaris 2.3 9 linux debian gentoo suse 7.0 7.3 probably others miros bsd netbsd openbsd run sparcstation 20 certain cpu modules sun supersparc nextstep 3.3 openstep 4.x also run
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Computer architecture
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graphics core next graphics core next gcn codename series microarchitectures well instruction set gcn developed amd gpus successor terascale microarchitecture/instruction set first product featuring gcn launched january 9 2012 gcn risc simd rather simt microarchitecture contrasting vliw simd architecture terascale gcn requires considerably transistors terascale offers advantages gpgpu computation makes compiler simpler also lead better utilization gcn graphics chips fabricated cmos 28 nm finfet 14 nm samsung electronics globalfoundries 7 nm tsmc available selected models radeon hd 7000 hd 8000 200 300 400 500 vega series amd radeon graphics cards including separately released radeon vii gcn also used graphics portion amd accelerated processing units apu playstation 4 xbox one apus gcn instruction set owned amd also owns x86-64 instruction set gcn instruction set developed specifically gpus gpgpu example micro-operation division documentation available llvm code generator compiler back-end available gcn instruction set used mesa 3d miaow open-source rtl implementation amd southern islands gpgpu instruction set aka graphics core next november 2015 amd announced boltzmann initiative amd boltzmann initiative shall enable porting cuda-based applications common c++ programming model super computing 15 amd showed heterogeneous compute compiler hcc headless linux driver hsa runtime infrastructure cluster-class high performance computing hpc heterogeneous-compute interface portability hip tool porting cuda-based applications common c++ programming model july 2017 family microarchitectures implementing identically called instruction set graphics core next seen five iterations differences instruction set rather minimal differentiate much one another exception fifth generation gcn architecture heavily modified stream processors improve performance support simultaneous processing two lower precision numbers place single higher precision number graphics command processor gcp functional unit gcn microarchitecture among tasks responsible asynchronous shaders short video amd asynchronous shaders visualizes differences multi thread preemption asynchronous shaders asynchronous compute engine ace distinct functional block serving computing purposes purpose similar graphics command processor since third iteration gcn hardware contains two schedulers one schedule wavefronts shader execution cu scheduler see new one schedule execution draw compute queues latter helps performance executing compute operations cus underutilized graphics commands limited fixed function pipeline speed bandwidth limited functionality known async compute given shader gpu drivers also need select good instruction order order minimize latency done cpu sometimes referred scheduling geometry processor contains geometry assembler tesselator vertex assembler gcn tesselator geometry processor capable tessellation hardware defined direct3d 11 opengl 4.5 see amd january 21 2017 gcn tesselator amd current sip block earlier units ati truform hardware tessellation terascale one compute unit combines 64 shader processors 4 tmus compute unit separate feed render output units rops compute unit consists cu scheduler branch message unit 4 simd vector units 16-lane wide 4 64kib vgpr files 1 scalar unit 4 kib gpr file local data share 64 kib 4 texture filter units 16 texture fetch load/store units 16 kib l1 cache four compute units wired share instruction cache 16 kib size scalar data cache 32kib size backed l2 cache simd-vu operates 16 elements time per cycle su operate one time one/cycle addition su handles operations like branching every simd-vu private memory stores registers two types registers scalar registers s0 s1 etc hold 4 bytes number vector registers v0 v1 etc represent set 64 4 bytes numbers operate vector registers every operation done parallel 64 numbers every time work actually work 64 inputs example work 64 different pixels time inputs slightly different thus get slightly different color end every simd-vu room 512 scalar registers 256 vector registers cu scheduler hardware functional block choosing simd-vu wavefronts execute picks one simd-vu per cycle scheduling confused schedulers hardware software gcn-gpus “ wavefront ” consists 64 threads nvidia gpus “ warp ” consists 32 threads amd solution attribute multiple wavefronts simd-vu hardware distributes registers different wavefronts one wavefront waiting result lies memory cu scheduler decides make simd-vu work another wavefront wavefronts attributed per simd-vu simd-vus exchange wavefronts max 10 wavefronts attributed per simd-vu thus 40 per cu amd codexl shows tables relationship number sgprs vgprs number wavefronts basically sgprs min 104 512/numwavefronts vgprs 256/numwavefronts note conjunction sse instructions concept basic level parallelism often called vector width vector width characterized total number bits simd vector unit simd-vu 10 wavefront instruction buffer takes 4 cycles execute one wavefront many implementations gcn typically accompanied several amd asic blocks including limited unified video decoder video coding engine amd trueaudio preview 2011 anandtech wrote unified virtual memory supported graphics core next specific hsa features implemented hardware need support operating system kernel subsystems and/or specific device drivers example july 2014 amd published set 83 patches merged linux kernel mainline 3.17 supporting graphics core next-based radeon graphics cards special driver titled hsa kernel driver resides directory /drivers/gpu/hsa drm-graphics device drivers reside /drivers/gpu/drm augments already existent drm driver radeon cards first implementation focuses single works alongside existing radeon kernel graphics driver kgd used perform scheduling offload assignment compute queues aces driver hardware buffering queues least one empty queue least one ace causing hws immediately assign buffered queues aces queues full queues safely assign part scheduling work performed includes prioritized queues allow critical tasks run higher priority tasks without requiring lower priority tasks preempted run high priority task therefore allowing tasks run concurrently high priority tasks scheduled hog gpu much possible letting tasks use resources high priority tasks using essentially asynchronous compute engines lack dispatch controllers first introduced fourth generation gcn microarchitecture present third generation gcn microarchitecture internal testing purposes driver update enabled hardware schedulers third generation gcn parts production use unit discards degenerate triangles enter vertex shader triangles cover fragments enter fragment shader unit introduced fourth generation gcn microarchitecture asynchronous compute engines controlling computation dispatching zerocore power long idle power saving technology shutting functional units gpu use amd zerocore power technology supplements amd powertune discrete gpus southern islands family gcn 2nd generation introduced radeon hd 7790 also found radeon hd 8770 r7 260/260x r9 290/290x r9 295x2 r7 360 r9 390/390x well steamroller-based desktop kaveri apus mobile kaveri apus puma-based beema mullins apus multiple advantages original gcn including freesync support amd trueaudio revised version amd powertune technology gcn 2nd generation introduced entity called shader engine se shader engine comprises one geometry processor 44 cus hawaii chip rasterizers rops l1 cache part shader engine graphics command processor 8 aces l2 cache memory controllers well audio video accelerators display controllers 2 dma controllers pcie interface a10-7850k kaveri contains 8 cus compute units 8 asynchronous compute engines independent scheduling work item dispatching amd developer summit apu november 2013 michael mantor presented radeon r9 290x discrete gpus sea islands family integrated apus gcn 3rd generation introduced 2014 radeon r9 285 r9 m295x tonga gpu features improved tessellation performance lossless delta color compression order reduce memory bandwidth usage updated efficient instruction set new high quality scaler video new multimedia engine video encoder/decoder delta color compression supported mesa however double precision performance worse compared previous generation discrete gpus integrated apus gpus arctic islands-family introduced q2 2016 amd radeon 400 series 3d-engine i.e gca graphics compute array gfx identical found tonga-chips polaris feature newer display controller engine uvd version 6.3 etc polaris-based chips polaris 30 produced 14 nm finfet process developed samsung electronics licensed globalfoundries slightly newer refreshed polaris 30 built 12 nm lp finfet process node developed samsung globalfoundries fourth generation gcn instruction set architecture compatible third generation optimization 14 nm finfet process enabling higher gpu clock speeds 3rd gcn generation architectural improvements include new hardware schedulers new primitive discard accelerator new display controller updated uvd decode hevc 4k resolutions 60 frames per second 10 bits per color channel discrete gpus fp64 performance gcn 4th generation gpus fp32 performance amd began releasing details next generation gcn architecture termed 'next-generation compute unit january 2017 new design expected increase instructions per clock higher clock speeds support hbm2 larger memory address space discrete graphics chipsets also include hbcc high bandwidth cache controller integrated apus additionally new chips expected include improvements rasterisation render output units stream processors heavily modified previous generations support packed math rapid pack math technology 8-bit 16-bit 32-bit numbers significant performance advantage lower precision acceptable example processing two half-precision numbers rate single single precision number nvidia introduced tile-based rasterization binning maxwell big reason maxwell efficiency increase january anandtech assumed vega would finally catch nvidia regarding energy efficiency optimizations due new dsbr draw stream binning rasterizer introduced vega also added support new shader stage – primitive shaders primitive shaders provide flexible geometry processing replace vertex geometry shaders rendering pipeline december 2018 primitive shaders ca n't used required api changes yet done vega 10 vega 12 use 14 nm finfet process developed samsung electronics licensed globalfoundries vega 20 uses 7 nm finfet process developed tsmc discrete gpus integrated apus double-precision floating-point fp64 performance gcn 5th generation gpus except vega 20 fp32 performance vega 20 fp32 performance gcn 5th generation gpus support half-precision floating-point fp16 calculations double fp32 performance
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Computer architecture
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start input/output mvs/370 successor versions ibm mainframe operating systems start input/output startio macro instruction branch entry low-level device access programmer responsible providing list device-specific ccws channel program executed i/o channels control units devices number exits several may immediate returns input/output supervisor ios invokers startio must supervisor mode key 0 startio interfaces directly ios component mvs start input/output differs excp including xdap simply dasd-only subset excp excpvr following fundamental way start input/output low level facility supports e.g. selection channel paths selection exposures execute channel program high level facility supports e.g. ccw translation page fixing serialization related requests vio callers execute channel program must tcb mode ibm documents excpvr privileged unprivileged access method code uses sam-e processing dasd data sets except special cases application may use execute channel program data control block dcb opened made accessible application system open/close/end-of-volume supervisor services svcs 19 20 55 respectively callers startio must privileged must page fix storage areas related request must use global storage srb/iosb may refer device real ucb even device allocated address space device need opened startio initiation sequence usually referred front end may tcb mode srb mode startio termination sequence usually referred back end always srb mode startio always utilizes srb/iosb pair srb service request block utilized schedule processor activity required available processor connection related i/o request i/o request necessarily run processor caller running indeed cases iosb input/output supervisor block describes related i/o request passes parameters receives responses ios ios generally calls appendages enabled srb mode special cases calls appendage disabled interrupt exit die unit control block ucb device points device descriptor table ddt identified routines needed device dependent processing e.g. handling attention interrupts appending reserve ccws appending set file mask seek although use startio customers supported ibm nevertheless macro instruction associated branch entry remained remarkably stable throughout forty-year-long 2014 transition mvs/370 z/os startio sole method performing lowest-level physical i/o operations channel-attached devices mvs/370 subsequent instances os particular vsam vtam use startio course excp xdap excpvr certain instances ims/vs jes particularly channel-to-channel operations involved additional branch entry added es/390 performs essentially function original retained compatibility existing programs additional branch entry implicitly obtains address related tcb psatold rather explicitly obtaining tcb= keyword parameter original branch entry catastrophic error occur ios processing related i/o request tcb usually caller job step tcb abnormally terminated whichever tcb happened active error detected basic design ios run asynchronously tasks address spaces could tcb address space indeed tcb e.g. srb perhaps likely system wait task runs os master scheduler address space perhaps best description startio application white paper entitled start input/output interface mvs written peter haas amdahl corp subsequently liquidated haas white paper contained application program example illustrated required optional parameters exits employed startio interface detailed description excp vr startio available logic manual
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Operating systems
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turing programming language turing pascal-like programming language developed 1982 ric holt james cordy university toronto toronto ontario canada turing descendant euclid pascal sp/k features clean syntax precise machine-independent semantics turing 4.1.0 latest stable version turing turing 4.1.1 turing 4.1.2 allow stand alone .exe files created versions turing 4.1.0 outdated syntax outdated functions named british computer scientist alan turing turing used primarily teaching language high school university level two versions exist object-oriented turing turing plus systems programming variant september 2001 object oriented turing renamed turing original turing renamed classic turing turing longer supported holt software associates toronto ontario currently microsoft windows supported platform turing widely used high schools ontario introduction programming november 28 2007 turing previously commercial programming language became freeware available download developer website free charge personal commercial educational use. ref name= holtsoft/old_index /ref makers turing holt software associates since ceased operations turing seen development since november 25 2007 turing designed lightweight readable intuitive syntax entire hello world program turing syntax highlighting turing avoids semicolons braces using explicit end markers language constructs instead allows declarations anywhere complete program defining using traditional recursive function calculate factorial currently two open source alternative implementations turing open turing open source version original interpreter tplus native compiler concurrent systems programming language variant turing plus opent project develop compiler turing longer development open turing open-source implementation original turing interpreter windows written tristan hume includes speed improvements new features opengl 3d new code editor fully backwards compatible closed-source implementation tplus open-source implementation original non-object-oriented turing systems programming extensions developed university toronto ported linux solaris mac os x queen university late 1990s tplus implements turing+ turing plus concurrent systems programming language based original turing programming language features turing plus eventually subsumed present object-oriented turing language turing plus extends original turing processes monitors specified c.a.r hoare well language constructs needed systems programming binary input-output separate compilation variables absolute addresses type converters features opent abandoned open-source language compiler ide developed members dteam computer science canada shares many similarities turing fully backwards compatible addition usual graphics drawing functions turing features special functions drawing maple leaves allow easier drawing canadian flag turing+ turing plus concurrent systems programming language based turing programming language designed james cordy ric holt university toronto canada 1987 features turing+ eventually subsumed object-oriented turing turing+ extended original turing processes monitors specified c.a.r hoare well language constructs needed systems programming binary input-output separate compilation variables absolute addresses type converters features turing+ explicitly designed replace concurrent euclid systems-programming applications tunis operating system originally written concurrent euclid recoded turing+ minitunis implementation turing+ used implement several production software systems including txl programming language object-oriented turing extension turing programming language replacement turing plus created ric holt university toronto canada 1991 imperative object-oriented concurrent modules classes single inheritance processes exception handling optional machine-dependent programming integrated development environment x window system demo version versions exist sun-4 mips rs-6000 nextstep windows 95 others
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Programming language topics
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dead peer detection dead peer detection dpd method detecting dead internet key exchange ike peer method uses ipsec traffic patterns minimize number messages required confirm availability peer dpd used reclaim lost resources case peer found dead also used perform ike peer failover
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Internet protocols
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jeus jeus abbreviation java enterprise user solution korean web application server developed tmaxsoft jeus provides web application server component tmaxsoft middleware-tier framework solution widely adopted korea holds largest 42.1 share market tmaxsoft released jeus 1.0 2000 2001 received j2ee 1.2 certification jeus 3.0. 2013 received world ’ first java ee 7 certification jeus 8 jeus launched april 2000 following table shows list versions release dates jeus 7 provides following features domain architecture jeus 7 supports massive scale computing environment lightweight speedy distributed clustering dynamic clustering core function enables rapid elasticity allows administrator easily add delete idle resources needed graceful redeployment application redeployment needed operation continuous service environment provided guaranteeing completion processing session requests prior redeployment superior performance provided large-scale requests improved caching function memory managed efficiently use optimized lru processing algorithm improves performance connected webtob server stable large-scale transaction processing ability exhibited due multiplexing i/o request queuing dynamic load balancing stream pipe communication reloading modified class instead entire class function modified development productivity dramatically improved webtob web server component complements jeus tmaxsoft middleware-tier solution webtob uses multi-thread architecture allows address multiple requests single process features include disk memory caching load balancing clustering dynamic queuing ability add additional nodes without interrupting operations help improve server speed stability webtob uses secure sockets layer operates without open firewall ports inherently provides stronger data security administrators also configure access control lists following shows minimum installation requirements jeus windows 2000 2003 xp vista solaris hp-ux aix linux two editions jeus available
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Web technology
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fedora version history fedora popular linux distribution developed community-supported fedora project sponsored red hat fedora attempts maintain six-month release schedule offering new versions may november although releases experienced minor delays releases red hat linux listed fedora 30 released april 30 2019 fedora 29 released october 30 2018. notable new features fedora modularity across variants new optional package repository called modular also referred application stream appstream gnome 3.30 zram arm images fedora scientific vagrant images fedora 28 released may 1 2018 red hat enterprise linux 8 derivatives based fedora 28. notable new features modular software repository curated 3rd-party software repositories fedora 27 released november 14 2017 workstation edition fedora 27 features gnome 3.26 display network configuration panels updated along overall settings panel appearance improvement system search shows results including system actions release also features libreoffice 5.4 fedora 26 released july 11 2017 fedora 25 released november 22 2016 notable changes see use wayland display system unicode 9 php 7.0 node.js 6 ibus emoji typing fedora 24 released june 21 2016 notable system wide changes see use gnome 3.20 gcc 6 python 3.5 fedora 23 released november 3 2015 see also fedora 22 released may 26 2015 major features include fedora 21 first version without codename released december 9 2014 fedora 20 codenamed heisenbug released december 17 2013 features fedora 20 include fedora 19 codenamed schrödinger cat released july 2 2013 red hat enterprise linux 7 derivatives based fedora 19 features fedora 19 include fedora 18 codenamed spherical cow released january 15 2013 features fedora 18 include next release operating system fedora 17 codenamed beefy miracle released may 29 2012 features fedora 17 include fedora 16 codenamed verne released november 8 2011 fedora 16 also dedicated memory dennis ritchie died month release features fedora 16 included fedora 15 codenamed lovelock released may 24 2011 features fedora 15 include fedora 14 codenamed laughlin released november 2 2010 features fedora 14 include fedora 13 codenamed goddard released may 25 2010 early development fedora project-leader paul frields anticipated looking fit finish issues tended build really tight ship fedora want make décor cabins little sumptuous polish deck chairs railings features fedora 13 include fedora 12 codenamed constantine released november 17 2009 red hat enterprise linux 6 derivatives based fedora 12 features fedora 12 fedora 11 codenamed leonidas released june 9 2009 first release whose artwork determined name instead users voting themes features fedora 11 fedora 10 codenamed cambridge released november 25 2008 flaunts new solar artwork features include fedora 9 codenamed sulphur released may 13 2008 new features fedora 9 included fedora 9 featured new artwork entitled waves like infinity fedora 8 changes wallpaper reflect time day fedora 8 codenamed werewolf released november 8 2007 new features updates fedora 8 included fedora 8 also included new desktop artwork entitled infinity new desktop theme called nodoka unique feature infinity wallpaper change day reflect time day february 2008 new xfce live cd spin announced x86 x86-64 architectures live cd version uses xfce desktop environment aims fast lightweight still visually appealing easy use like gnome kde spins xfce spin installed hard disk fedora 7 codenamed moonshine released may 31 2007 biggest difference fedora core 6 fedora 7 merging red hat core community extras repositories dropping core name fedora core new build system put place manage packages release used entirely new build compose tools enabled user create fully customized fedora distributions could also include packages third party provider three official spins available fedora 7 fedora 7 featured gnome 2.18 kde 3.5 new theme entitled flying high openoffice.org 2.2 firefox 2.0 fast user switching fully integrated enabled default also number updates selinux including new setroubleshoot tool debugging selinux security notifications new comprehensive system-config-selinux tool fine-tuning selinux setup two core releases introduced specific artwork defined trend continued later fedora versions fedora core 5 released march 20 2006 codename bordeaux introduced fedora bubbles artwork first fedora release include mono tools built beagle f-spot tomboy also introduced new package management tools pup pirut see yellowdog updater modified also first fedora release include long deprecated kept compatibility linuxthreads replaced native posix thread library fedora core 6 released october 24 2006 codenamed zod release introduced fedora dna artwork replacing fedora bubbles artwork used fedora core 5 codename derived infamous villain general zod superman dc comic books version introduced support compiz compositing window manager aiglx technology enables gl-accelerated effects standard desktop shipped firefox 1.5 default web browser smolt tool allows users inform developers hardware use fedora core 1 first version fedora released november 6 2003 codenamed yarrow fedora core 1 based red hat linux 9 shipped version 2.4.19 linux kernel version 2.4 gnome desktop environment k desktop environment 3.1 fedora core 2 released may 18 2004 codenamed tettnang shipped linux 2.6 gnome 2.6 kde 3.2 selinux selinux disabled default due concerns radically altered way fedora core ran xfree86 replaced newer x.org merger previous official x11r6 release additionally included number updates xrender xft xcursor fontconfig libraries significant improvements fedora core 3 released november 8 2004 codenamed heidelberg first release fedora core include mozilla firefox web browser well support indic scripts release also saw lilo boot loader deprecated favour grub selinux also enabled default new targeted policy less strict policy used fedora core 2 fedora core 3 shipped gnome 2.8 kde 3.3 first release include new fedora extras repository fedora core 4 released june 13 2005 codename stentz shipped linux 2.6.11 kde 3.4 gnome 2.10 version introduced new clearlooks theme inspired red hat bluecurve theme also shipped openoffice.org 2.0 office suite well xen high performance secure open source virtualization framework also introduced support powerpc cpu architecture 80 new policies selinux
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Operating systems
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oracle rac database computing oracle real application clusters rac — option oracle database software produced oracle corporation introduced 2001 oracle9i — provides software clustering high availability oracle database environments oracle corporation includes rac enterprise edition provided nodes clustered using oracle clusterware oracle rac allows multiple computers run oracle rdbms software simultaneously accessing single database thus providing clustering non-rac oracle database single instance accesses single database database consists collection data files control files redo logs located disk instance comprises collection oracle-related memory background processes run computer system oracle rac environment 2 instances concurrently access single database allows application user connect either computer access single coordinated set data instances connected interconnect enables instances sync accessing data main aim oracle rac implement clustered database provide performance scalability resilience high availability data instance level oracle rac depends infrastructure component oracle clusterware coordinate multiple servers sharing data storage fan fast application notification technology detects down-states rac administrators use codice_1 tool manage rac configurations prior oracle 9 network-clustered oracle databases used storage device data-transfer medium meaning one node would write data block disk another node would read data disk inherent disadvantage lackluster performance oracle 9i addressed issue rac uses dedicated network connection communications internal cluster since computers/instances rac access database overall system must guarantee coordination data changes different computers whenever computer queries data receives current version — even another computer recently modified data oracle rac refers functionality cache fusion cache fusion involves ability oracle rac fuse in-memory data cached physically separately computer single global cache oracle grid naming service gns handles name resolution cluster registry trace file analyzer tfa aids collecting rac diagnostic data relative single-instance oracle database oracle rac adds additional complexity database automation makes sense single-instance databases becomes even necessary clustered databases increased complexity oracle real application clusters rac introduced oracle 9i 2001 supersedes oracle parallel server ops database option whereas oracle9i required external clusterware known vendor clusterware like trucluster veritas cluster server sun cluster unix flavors except linux windows oracle provided free clusterware called cluster ready services crs oracle 10g oracle clusterware product available operating systems release oracle database 10g release 2 10.2 cluster ready services renamed oracle clusterware using oracle 10g higher oracle clusterware clusterware need platforms oracle rac operates except tru cluster case need vendor clusterware still use clusterware vendors clusterware certified oracle rac rac write-transaction must take ownership relevant area database typically involves request across cluster interconnection local ip network transfer data-block ownership another node one wishing write takes relatively long time tens milliseconds compared single database-node using in-memory operations many types applications time spent coordinating block access across systems low relative many operations system rac scale comparably single system moreover high read-transactional databases data-warehousing applications work well rac need ownership-transfer exists oracle 11g made many enhancements area performs lot better earlier versions read-only workloads overhead resource mastering ownership-transfer minimal fewer three nodes request resource cluster obtained maximum three hops owner-master-requestor makes oracle rac horizontally scalable many nodes application vendors sap use oracle rac demonstrate scalability application biggest oltp benchmarks oracle rac oracle rac 11g supports 100 nodes applications rac may require careful application partitioning enhance performance application scales linearly smp machine may scale linearly rac however application scale linearly smp scale ported rac short application scalability based well application scales single instance shared-nothing shared-everything architectures advantages dbms vendors industry analysts regularly debate matter example microsoft touts comparison sql server 2005 oracle 10g rac oracle corporation offered shared nothing architecture rdbms advent ibm sp sp2 release 7.x mpp editions virtual shared drives vsd used create shared everything implementation shared nothing architecture shared-everything architectures share data disk data memory nodes cluster contrast shared-nothing architectures share none commercially available databases offer shared-everything architecture ibm db2 z/os ibm mainframe operating-system provided high-performance data-sharing option since mid-1990s ibm released mainframe hardware software-clustering infrastructure late 2009 ibm announced db2 purescale shared-disk clustering scheme db2 9.8 aix mimics parallel sysplex implementation behind db2 data sharing mainframe february 2008 sybase released adaptive server enterprise cluster edition resembles oracle rac shared-everything design although technically shared-everything sybase also provides column-based relational database focused analytic datawarehouse applications called sybase iq configured run shared disk mode shared-nothing architectures share neither data disk data memory nodes cluster contrast shared-everything architectures share competitive products offering shared-nothing architectures include
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Distributed computing architecture
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ipsw ipsw ipod software file format used itunes install ios firmware apple devices share ipsw file format ios firmware allowing users flash devices itunes macos windows .ipsw file compressed archive file similar zip archive containing three apple disk image files one containing root file system ios two ram disks restore update file also holds firmware folder contains ibss ibec dfu battery images low full charging also baseband firmware files .bbfw format baseband firmware two files named build manifest restore manifest apple property list .plist format checks compatibility holds hashes base64 format instructs device find specific firmware parts restore buildmanifest.plist sent apple tss server checked order obtain shsh blob every restore without shsh blobs firmware refuse restore thus making downgrades impossible official fashion due apple limitation archive password-protected dmg images inside encrypted aes apple release keys extracted using different iboot bootloader exploits limera1n created george hotz commonly known geohot since many tools created decryption modification root file system 2015 san bernardino attack fbi recovered shooter iphone 5c belonged san bernardino county department public health fbi recovered icloud backups one half months shooting wanted access encrypted files device u.s. government ordered apple produce ipsw file would allow investigators brute force passcode iphone order used writs act originally created judiciary act 1789 demand firmware way smartphone manufacturers ordered comply tim cook responded company webpage outlining need encryption arguing produce backdoor one device would inevitably used compromise privacy iphone users
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Operating systems
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parafe parafe abbreviation passage automatisé rapide aux frontières extérieures automated fast-track crossing external borders passport verification program operated france direction centrale de la police aux frontières dcpaf border police parafe incorporating automated self-service barriers operated dcpaf located immigration checkpoints arrival departure halls paris marseille nice lyon airports london st. pancras train station offering alternative using desks staffed immigration officers gates use facial recognition technology verify user identity data stored chip biometric passport present european economic area swiss citizens use parafe egates provided aged 18 years holding valid biometric passports minors aged 12-17 also use gates certain arrival controls never departure french authorities strict rules unaccompanied minors leaving country use parafe gates traveller must biometric passport france certain countries epassports biometric logo front cover passports biometric logo front cover computer gate scanner reads information contained chip inside passport camera takes picture passenger biometric patterns verified picture saved passport chip epassport gate scanner reads information contained chip inside passport runs data numerous databases determine traveller security risk camera takes picture traveller officer control station behind gates checks image captured camera matches one passport facial recognition data verification facial recognition process complete doors automatically either open signifying traveller permitted enter and/or exit country remain closed stop icon illuminate demonstrating traveller failed security checks personally meet immigration officials present parafe egates available following locations previous generation parafe egates used fingerprint technology verify identity passenger first introduced 2010 phased since considered insufficiently intuitive hand finger slower process non-french citizens actively sign french airport every 5 years able use egates first egates replaced early 2017 pilot project facial recognition technology extended airports st pancras station throughout rest 2017 2018 still gates left work fingerprint technology new registrations still accepted
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Computer security
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jack nipper ii coconut capers jack nipper ii coconut capers video game gremlin graphics released 1987 several home computer systems sequel jack nipper following naughty exploits jack nipper jack family exiled australia unhappy jack jumped plane using nappy parachute finds middle african jungle surrounded dangerous animals natives father also following close behind determined give boy good spanking jack must cause much mischief possible avoiding punishment previous game jack nipper ii side-view flip screen game puzzle solving platform elements however false-3d effect removed making gameplay pure 2d jack must perform naughty pranks time human animal inhabitants jungle evading father hot pursuit game reviewed 1990 dragon 158 hartley patricia kirk lesser role computers column part mastertronic mega pack 10 games previously released europe reviewers gave game 3½ 5 stars calling rather cute arcade game on-screen character running around africa
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Computer architecture
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vpnfilter vpnfilter malware designed infect routers certain network attached storage devices 24 may 2018 estimated infected approximately 500,000 routers worldwide though number at-risk devices larger steal data contains kill switch designed disable infected router command able persist user reboot router fbi believes created russian fancy bear group vpnfilter malware infecting number different kinds network routers storage devices seems designed part target serial networking devices using modbus protocol talk control industrial hardware factories warehouses malware special dedicated code target control systems using scada initial infection vector still unknown cisco talos security group hypothesizes malware exploits known router security vulnerabilities infect devices software installs multiple stages vpnfilter uses multiple third stage operations initial infection one function vpnfilter sniff network data network connected infected device gather credentials supervisory control data data encrypted exfiltrated via tor network also serve relay point hide origin subsequent attacks cisco symantec suggest people affected devices factory reset typically accomplished using small pointed object straightened paperclip push small reset button back unit 10 30 seconds time varies model remove malware also restores router original settings router remote management enabled factory reset often disable default setting many routers remote management thought one possible vector initial attack connecting factory-reset router internet device default passwords changed prevent reinfection initial worm installs vpnfilter attack devices running embedded firmware based busybox linux compiled specific processors include non-embedded linux devices workstations servers manufacturer-provided firmware following router models known risk vpnfilter described cisco talos infected many 500,000 devices worldwide perhaps 54 different countries though proportionately focus ukraine fbi taken high-profile role addressing malware conducting investigation resulted seizure domain name toknowall.com ostensibly used redirect queries stage 1 malware allowing locate install copies stages 2 3 us justice department also compelled site photobucket disable known urls used distribute malware stage 2 25 may 2018 fbi recommended users reboot at-risk devices would temporarily remove stages 2 3 malware stage 1 would remain leading router try re-downloading payload infecting router however prior recommendation us justice department seized web endpoints malware uses stage 2 installation without urls malware must rely fallback socket listener stage 2 installation method requires threat actor command control systems contact system install stage 2 increasing threat actor risk identified fbi recommended users disable remote management devices update firmware firmware update removes stages malware though possible device could reinfected fbi said would help find servers distributing payload
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Computer security
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expression problem expression problem term used discussing strengths weaknesses various programming paradigms programming languages philip wadler coined term response discussion rice university programming languages team plt expression problem new name old problem goal define datatype cases one add new cases datatype new functions datatype without recompiling existing code retaining static type safety e.g. casts ecoop '98 krishnamurthi et al presented design pattern solution problem simultaneously extending expression-oriented programming language tool-set dubbed expressivity problem thought programming language designers could use problem demonstrate expressive power creations plt problem shown construction drscheme drracket solved via rediscovery mixins avoid using programming language problem paper programming languages krishnamurthi et al used old geometry programming problem explain pattern-oriented solution conversations felleisen krishnamurthi ecoop presentation wadler understood pl-centric nature problem pointed krishnamurthi solution used cast circumvent java type system discussion continued types mailing list corky cartwright rice kim bruce williams showed type systems oo languages might eliminate cast response wadler formulated essay stated challenge whether language solve expression problem salient indicator capacity expression label expression problem puns expression much language express expression terms trying represent language expressions others co-discovered variants expression problem around time rice university plt particular thomas kühne dissertation smaragdakis batory parallel ecoop 98 article follow-up work used expression problem showcase power programming language designs expression problem also fundamental problem multi-dimensional software product line design particular application special case fosd program cubes various solutions expression problem solution varies amount code user must write implement language features require
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Programming language topics
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enrique salem enrique salem born 1965 president ceo software company symantec 2009 2012 member u.s. president management advisory board salem joined bain capital ventures 2014 focuses infrastructure software services specialization cybersecurity serves boards several bain capital venture portfolio companies including docusign serves independently boards fireeye feye atlassian team forescout fsct currently serves board directors number privately held startups including cloudgenix attivo networks shieldx leapyear awake security shiftleft red balloon security bettercloud rubrik.. salem served board city year san jose 2015 2018 trustee city year salem attended dartmouth college earned bachelor arts ba degree computer science vice president peter norton computing acquired symantec 1990 manager project create norton desktop windows left symantec returned via brightmail acquisition enrique named 2004 entrepreneur year ernst young 2007 corporate executive year hispanic net salem held vice-president positions security pacific merchant bank ask jeeves oblix inc. salem ceo brightmail company made email program designed screen spam email brightmail acquired symantec 2004 brightmail almost two years salem spent total 19 years symantec took john w. thompson symantec ceo april 2009 july 2012 salem became member president barack obama ’ u.s. president management advisory board march 2011 served til end administration
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Computer security
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leaf group leaf group formerly demand media inc american content company operates online brands including ehow livestrong.com marketplace brands saatchi art society6 company also provides social media platforms existing large company websites distributes content bundled social media tools outlets around web demand media created 2006 former private equity investor shawn colo former chairman myspace richard rosenblatt company employs algorithm identifies topics high advertising potential based search engine query data bids advertising auctions topics typically advice how-to field commissions freelancers produce corresponding text video content content posted variety sites including youtube company sites ehow livestrong.com demand media content media service offering includes leading owned operated online properties publish content text video photography designed visual formats content published across several key categories ehow.com how-to reference do-it-yourself destination livestrong.com health healthy living destination certain niche properties focused specific interests also owns operates leaftv lifestyle resource women produces short-form how-to videos covering stylish living food fashion additionally studiod business develops executes content marketing strategies creates custom content third-party brands agencies publishers marketplaces service offering demand media operates two art design marketplaces large communities artists market sell original artwork original designs printed wide variety products society6.com acquired june 2013 provides artists online commerce platform feature sell original images designs consumer products art prints phone tablet cases t-shirts mugs blankets tapestries wall clocks duvet covers shower curtains throw pillows saatchiart.com acquired august 2014 online art gallery featuring wide selection original paintings drawings sculptures photography provides global community artists curated environment exhibit sell work directly consumers around world 2017 leaf group acquired deny designs modern home furnishings company original designs based colorado demand media co-founded may 2006 richard rosenblatt shawn colo. rosenblatt long history building selling internet media companies chief executive officer intermix media chairman myspace.com rosenblatt one innovators internet social networking colo financial acquisition specialist worked 10 years private equity industry principal spectrum equity investors specializing media communications companies demand media raised 355 million financing first two years investors oak investment partners spectrum equity investors generation partners goldman sachs june 2007 demand media hired charles hilliard former morgan stanley investment banker netzero/united online senior executive initial public offering ipo specialist president chief financial officer acquired byron reese how-to website expertvillage.com austin tx 20 million reese became company chief innovation officer developed algorithm company uses identify topics high advertising potential 2008 demand media acquired 30 domain-name portfolios owned 65 destination websites said 2009 revenue nearly 200 million making profit later reported company never profitable july 2008 reported yahoo interested buying demand media 1.5 billion 2 billion sources close companies said yahoo executives attracted demand media ’ generation advertising impressions ability create niche social networks media sites demand media ceo richard rosenblatt later said company sale deal never got past talking stage reported rosenblatt wanted price closer 3 billion demand media august 2014 demand media acquired online art-gallery marketplace saatchi art named startup top executive sean moriarty new ceo demand media inc company changed name 2016 reflect focus marketplaces media content lifestyle platforms since 2006 demand media acquired collection relatively unknown sites relaunched social networking features video capabilities serve specific niche interests company ’ first six months made nine acquisitions including purchase major registrars enom bulkregister november 6 2008 shawn colo head demand media mergers acquisitions said company would continue buy niche well-trafficked sites company profitable still lot cash bank 2008 demand media acquired pluck company providing social networking commenting solutions websites reported 75 million cash indieclick rss graffiti acquired august 2011 name.com domain name registrar acquired january 7 2013 society6 acquired june 25 2013 saatchi online acquired august 11 2014 august 2014 demand media announced successfully separated rightside group ltd. brands enom name.com online auction site namejet result separation demand media longer provider domain name services april 2016 demand media announced sale brand cracked.com e.w scripps may 2016 demand media announced sale brand trails.com lovetoknow corp owned howard love february 2017 demand media airliners.net site acquired verticalscope majority-owned torstar 2018 leaf acquired website well+good 2018/19 leaf acquired website onlyinyourstate demand media executives say websites content-driven attract visitors showing multiword search-engine queries words typed search engine specific search called long tail search demand media attempts get visitors websites long-tail searches tries retain visitors related content social media tools social media platforms get 3 billion interactions per month clients already well-established brands demand media commissions specific website content distributes websites others advertising revenue sharing agreements demand media owned 135,000 videos 340,000 articles largest contributor youtube uploading 10,000 20,000 new videos per month gets 1.5 million page views per day youtube content generated via process demand media uses algorithms generate titles posts titles screened pool freelance writers video creators list available titles used 100,000 severely curtailed second half 2011 typically writers claim ten titles week submit articles format length dictated guidelines submitted articles go editor also freelancer either clean request rewrite writers submit revised article either accepted rejected payment via paypal twice week demand media ’ acquisition pluck.com 2008 gave means provide specialized content social media platforms website content comes advertising attached website owners get free content sites split advertising revenue demand media april 2010 financial times reported demand media planning initial public offering shares ipo would mean acquisitions would question ipo filing completed august year shares first expected offered december 2010 tender would give demand media value 1.5 billion however result securities exchange commission investigation regarding company novel accounting long-lived content pricing delayed january 12 2011 company announced would price shares 14 16 giving valuation approximately 1.3 billion questions raised demand media claim profitable given ipo filings reported losses past several years demand media attracted criticism internet watchdogs one largest buyers articles videos often commissioning low quality articles cut costs effort mass-produce articles videos appear highly google search results purchasing thousands search-engine-driven content low-paid freelancers use websites attract advertisers israeli startup owned google adsense simpli demand media also criticized methods accounting capitalizing costs content amortizing five years giving appearance profitability
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Web technology
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microsoft office password protection microsoft office password protection security feature protect microsoft office word excel powerpoint documents user-provided password office 2007 uses modern encryption earlier versions used weaker systems considered secure office 2007–2013 employed 128-bit key aes password protection remains secure office 2016 employed 256-bit key aes password protection also remains secure office 97–2003 password protection used 40-bit key rc4 contains multiple vulnerabilities rendering insecure microsoft office applications offer use two main groups passwords set document depending whether encrypt password-protected document passwords encrypt password-protected document different security level features microsoft office applications mentioned lack document encryption passwords mentioned reliably protect document hacker password cracking software remove protection password-protected document little time password encrypts document also restricts user opening document possible set type password microsoft office applications user fails enter correct password field appears attempt open password-protected document viewing editing document possible due encryption document protected password open hacker needs decrypt document get access contents provide improved security microsoft consistently enhancing office encryption algorithm strength excel word 95 prior editions weak protection algorithm used converts password 16-bit key hacking software readily available find 16-bit key decrypt password-protected document instantly excel word 97 2000 key length increased 40 bits protection algorithm also currently considered weak presents difficulties hacking software default protection office xp 2003 changed opportunity use custom protection algorithm added choosing non-standard cryptographic service provider allows increasing key length key used encrypt document ’ found however password-cracking programs enter multiple random passwords speed use csps slow password recovery weak passwords still recovered fast enough even custom csp office 2007 word excel powerpoint protection significantly enhanced since modern protection algorithm named advanced encryption standard used present software break encryption help sha-1 hash function password stretched 128-bit key 50,000 times opening document result time required crack vastly increased excel word 2010 still employ aes 128-bit key number sha-1 conversions doubled 100,000 increasing time required crack password office 2013 access excel onenote powerpoint project word uses 128-bit aes hash algorithm sha-1 default office 2016 access excel onenote powerpoint project word uses 256-bit aes sha-1 hash algorithm cbc cipher block chaining default protection worksheets macros necessarily weaker entire workbook software must able display use excel particularly weak equivalent password easily found form abababababax first 11 chars either b last ascii character number attacks employed find password remove password protection excel word documents password removal done help precomputation tables guaranteed decryption attack attacks target original password set microsoft excel word include dictionary attack rule-based attack brute-force attack mask attack statistics-based attack efficiency attacks considerably enhanced one following means applied multiple cpus distributed attack gpgpu applicable microsoft office 2007–2010 documents cloud computing due weak passwords moment cloud computing facilities capable unlocking many ca 80 files saved office 2007–2010 format passwords sufficient length complexity typically brute-forced office 2013 introduces sha-512 hashes encryption algorithm making brute-force rainbow table attacks slower however noted sha hash algorithms never designed password hashing thus considered secure anymore modern slower thus secure hashes pbkdf2 scrypt kdfs yet implemented office specialized software designed recover lost microsoft office passwords pre-aes encryption ultimately security password-protected document dependent user choosing password sufficient complexity password determined guesswork social engineering underlying cipher important
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Computer security
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mos operating system mos signifies 'mobile operating system soviet clone unix 1980s operating system commonly found sm evm minicomputers also ported es evm elbrus mos also used high-end pdp-11 clones several modifications mos named mnos demos etc
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Operating systems
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secureworks secureworks inc. united states-based subsidiary provides information security services protecting customers computers networks information assets malicious activity cybercrime company approximately 4,400 customers across 61 countries ranging fortune 100 companies mid-sized businesses variety industries became part dell february 2011 branched become public organization april 2016 still majority-owned dell secureworks founded privately held company 1998 michael pearson joan wilbanks 2002 michael r. cote became president ceo 2005 2006 company named inc. 500 inc. 5000 lists 2006 deloitte ’ fast 500 2006 secureworks merged lurhq corporation new entity continued secureworks corporate name lurhq founded 1996 myrtle beach sc provided managed security services large enterprises similar company cultures leadership secureworks according gartner merger created stronger company merger secureworks able leverage sherlock lurhq portal unify combined customer base onto single integrated security management platform 2009 secureworks acquired managed security services mss business verisign inc. provider internet infrastructure services networked world grew 500 employees worldwide acquisition expanded clients approximately 2,600 50 countries including united kingdom saudi arabia taiwan finland spain brazil mexico includes four fortune 10 also 2009 secureworks acquired 10-year-old dns limited acquisition expanded secureworks operation include uk-based operations center additional offices london edinburgh january 4 2011 dell announced would acquire secureworks part dell services dell secureworks officially began operating dell subsidiary february 7 2011 dell secureworks continued expand portfolio around world may 2013 arrived anz region move australia new zealand put dell ring security services market companies like ibm hp verizon dell secureworks opened operations center sydney meet demands local australia businesses demand services area penetration testing forensic investigations ongoing monitoring environments attacks december 17 2015 dell subsidiary secureworks filed go public april 22 2016 secureworks announced ipo raising 112 million pricing ipo 14 per share however company expecting initial price 15.50- 17.50 first tech ipo u.s. 2016 august 2017 secureworks rebranded logo changed capitalization w name lower case
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Computer security
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list unix daemons list unix daemons found various unix-like operating systems unix daemons typically name ending
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Operating systems
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comic bakery comic bakery computer game msx made konami 1984 later ported commodore 64 imagine software game set bakery town baker tries bake deliver bread croissants msx version fighting raccoons pieces bread move along factory line raccoons try eat bread switch machines player required keep machinery running also scare away raccoons player succeeds delivery truck loaded bread drives advancing player next level level maintains format last difficulty increasing player progresses levels music sound effects c64 version made martin galway title chiptune covered press play tape visa röster instant remedy msx version unique music using yankee doodle instead song comic bakery also used games jurassic park game boy color platypus pc
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Computer architecture
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unicode microsoft windows microsoft one first companies implement unicode back ucs-2 evolved utf-16 products still 2019 improving operating system support utf-8 windows nt first operating system used wide characters system calls using ucs-2 encoding scheme first upgraded utf-16 starting windows 2000 allowing representation additional planes surrogate pairs current windows versions back windows xp prior windows nt 3.x 4.0 shipped system libraries support string encoding two types 16-bit unicode utf-16 since windows 2000 sometimes multibyte encoding called code page incorrectly referred ansi code page 16-bit functions names suffixed -w wide codice_1 code page oriented functions use suffix -a ansi codice_2 conventions used apis copied systems codice_3 codice_4 split necessary many languages including c provide clean way pass 8-bit 16-bit strings function functions implemented wrapper translates text using current code page utf-16 calls w function functions return strings opposite conversion apparently put characters n't exist current locale microsoft attempted support unicode portably providing unicode switch compiler switches unsuffixed generic calls w interface converts string constants wide utf-16 versions actually work translate utf-8 outside string constants resulting code attempts open files compiling earlier independent unicode switch windows also provides mbcs api switch changes functions n't work mbcs codice_5 mbcs-aware one codice_6 notice lot microsoft documentation uses term unicode mean 8-bit text windows ce utf-16 used almost exclusively api mostly missing limited set ansi api available windows ce 5.0 use reduced set locales may selectively built onto runtime image 2001 microsoft released special supplement microsoft ’ old windows 9x systems includes dynamic link library unicows.dll 240 kb containing 16-bit flavor ones letter w end basic functions windows api microsoft windows code page designated utf-8 code page 65001 prior windows 10 insider build 17035 november 2017 impossible set locale code page 65001 leaving code page available microsoft claimed utf-8 locale might break functions possible example _mbsrev written assume multibyte encodings used 2 bytes per character thus code pages bytes gb 18030 cp54936 utf-8 could set locale means narrow functions particular codice_8 opens files called utf-8 strings fact way open possible files using codice_8 matter locale set and/or bytes put string none available locales produce possible utf-16 characters problem also applies api takes returns 8 bit strings including windows ones codice_10 modern non-windows platforms string passed codice_8 effectively utf-8 produces incompatibility platforms windows normal work-around add windows-specific code convert utf-8 utf-16 using multibytetowidechar call wide function another popular work-around convert name 8.3 filename equivalent necessary codice_8 inside library function takes string filename altered proposals add new apis portable libraries boost necessary conversion adding new functions opening renaming files functions would pass filenames unchanged unix translate utf-16 windows would allow code portable required many code changes calling wide functions insider build 17035 april 2018 update nominal build 17134 windows 10 beta use unicode utf-8 worldwide language support checkbox appeared setting locale code page utf-8 allows calling narrow functions including codice_8 codice_2 utf-8 strings microsoft compilers often fail producing utf-8 string constants utf-8 source files reliable method turn unicode mark input file utf-8 i.e use bom arrange string constants utf-8 bytes bom added microsoft compiler interpret strings utf-8 convert utf-16 convert back current locale thus destroying utf-8 without bom using single-byte locale microsoft compilers leave bytes quoted string unchanged
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Operating systems
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fxscript fxscript scripting language final cut pro final cut express fxbuilder scripting utility users able modify existing fcp fxscripts program completely new ones example scale image two lines necessary scale image full size half size first region might rectangle scaled statement scale parameters statement blitrect copies region image changed region origregion new region different sizes final cut pro scales image fit new region statement command accomplishes single action example statements scale blitrect fxbuilder users create test fxscripts optionally multiple windows inside final cut pro/express fxscript three types effects fxscript two parts normally flow script top bottom users take flow control using loops example for/next conditional branches example if/else fxscript also allows breaking scripts subroutines called parts script using names
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Programming language topics
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msx character set msx character sets group single- double-byte character sets developed microsoft msx computers based code page 437 since graphic characters corresponding unicode representation portably displayed web browser following table shows msx characters corresponding unicode glyph code point otherwise unicode replacement character u+fffd � hyphen code point control characters non-printing characters represented names character set differences exist depending target market machine variations german din international character sets identical apart style zero 0 character international character set zero slash din character set dotted zero msx terminal compatible vt-52 escape codes plus extra control codes shown brazilian manufacturer gradiente initially included modified msx character set v1.0 machines allow writing correct portuguese differences shown boxed symbol 0x9e 158 currency symbol brazilian cruzado used anymore later brazilian msx models v1.1 higher included standardized character set named brascii solved accentuation incompatibility problems amongst different makers
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Computer architecture
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shamoon shamoon also known w32.distrack modular computer virus discovered 2012 targeting recent 32-bit nt kernel versions microsoft windows virus noted behavior differing malware attacks due destructive nature cost attack recovery known years later biggest hack history virus apparently intended cyber warfare shamoon spread infected machine computers network system infected virus continues compile list files specific locations system upload attacker erase finally virus overwrites master boot record infected computer making unusable virus used cyber warfare national oil companies saudi arabia saudi aramco qatar rasgas discovery announced 16 august 2012 symantec kaspersky lab seculert similarities highlighted kaspersky lab seculert shamoon flame malware malware unique used target saudi government causing destruction state owned national oil company saudi aramco attackers posted pastie pastebin.com hours prior wiper logic bomb occurring citing oppression al-saud regime reason behind attack attack well-staged according chris kubecka former security advisor saudi aramco attack group leader security aramco overseas unnamed saudi aramco employee information technology team opened malicious phishing email allowing initial entry computer network around mid-2012 kubecka also detailed black hat usa talk saudi aramco placed majority security budget ics control network leaving business network risk major incident behalf anti-oppression hacker group fed crimes atrocities taking place various countries around world especially neighboring countries syria bahrain yemen lebanon egypt ... also dual approach world community nations want hit main supporters disasters action one main supporters disasters al-saud corrupt regime sponsors oppressive measures using muslims oil resources al-saud partner committing crimes hands infected blood innocent children people first step action performed aramco company largest financial source al-saud regime step penetrated system aramco company using hacked systems several countries sended malicious virus destroy thirty thousand computers networked company destruction operations began wednesday aug 15 2012 11:08 local time saudi arabia completed within hours shamoon attack designed two things replace data hard drives image burning american flag report addresses infected computers back computer inside company ’ network virus consisted three components dropper wiper reporter dropper main component source infection component drops wiper reporter onto infected computer copies network shares executes creates service start whenever windows starts wiper destructive component component gathers files locations infected computers erases sends information files attacker erased files overwritten corrupted files recovered reporter component sends infected information back attacker 15 august 11:08 local time 30,000 windows based systems began overwritten symantec found affected systems image american flag whilst data deleted overwritten saudi aramco announced attack facebook page went offline company statement issued 25 august 2012 statement falsely reported normal business resumed 25 august 2012 however middle eastern journalist leaked photographs taken 1 september 2012 showing kilometers petrol trucks unable loaded due backed business systems still inoperable saudi aramco restored main internal network services impacted august 15 2012 malicious virus originated external sources affected 30,000 workstations workstations since cleaned restored service precaution remote internet access online resources restricted saudi aramco employees returned work august 25 2012 following eid holidays resuming normal business company confirmed primary enterprise systems hydrocarbon exploration production unaffected operate isolated network systems production plants also fully operational control systems also isolated august 29 2012 attackers behind shamoon posted another pastie pastebin.com taunting saudi aramco proof still retained access company network post contained username password security network equipment new password aramco ceo khalid al-falih attackers also referenced portion shamoon malware proof pastie internet service routers three info follows core router sa-ar-co-1 password telnet c1sc0p ss-ar-cr-tl enable c1sc0p ss-ar-cr-bl backup router sa-ar-co-3 password telnet c1sc0p ss-ar-bk-tl enable c1sc0p ss-ar-bk-bl middle router sa-ar-co-2 password telnet c1sc0p ss-ar-st-tl enable c1sc0p ss-ar-st-bl khalid a. al-falih ceo email info follows khalid.falih aramco.com password kal ram sa1960 security appliances used according kubecka order restore operations saudi aramco used large private fleet aircraft available funds purchase much world hard drives driving price new hard drives required quickly possible oil prices affected speculation september 1 2012 gasoline resources dwindling public saudi arabia 17 days august 15th attack rasgas also affected different variant crippling similar manner unclear attacker may interest actually destroying infected pc kaspersky labs hinted 900 kb malware could related wiper used cyber attack iran april 2-day analysis company erroneously concluded malware likely come scriptkiddies inspired wiper later blog post eugene kaspersky clarified use shamoon categorizing cyber warfare virus hit companies within oil energy sectors group named cutting sword justice claimed responsibility attack 35,000 saudi aramco workstations causing company spend week restoring services group later indicated shamoon virus used attack computer systems rasgas also knocked offline unidentified computer virus security experts attributing damage shamoon shamoon made surprise comeback november 2016 according symantec involved new attack 23 january 2017 malware logic bomb triggered master boot record data wiping payload 11:08am local time wednesday august 15 attack occurred month ramadan 2012 would appear attack timed occur staff gone holiday reducing chance discovery maximum damage could caused hampering recovery shamoon uses number components infect computers first component dropper creates service name ‘ ntssrv ’ remain persistent infected computer spreads across local network copying computers drop additional components infected computers dropper comes 32-bit 64-bit versions 32-bit dropper detects 64-bit architecture drop 64-bit version malware also contains disk wiping component utilizes eldos-produced driver known rawdisk achieve direct user-mode access hard drive without using windows apis component overwrites files portions image 2012 attack used image burning u.s. flag 2016 attack used photo body alan kurdi
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Computer security
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