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red hat linux red hat linux created company red hat widely used linux distribution discontinuation 2004 early releases red hat linux called red hat commercial linux red hat published first non-beta release may 1995 first linux distribution use rpm package manager packaging format time served starting point several distributions mandriva linux yellow dog linux 2003 red hat discontinued red hat linux line favor red hat enterprise linux rhel enterprise environments fedora developed community-supported fedora project sponsored red hat free-of-cost alternative intended home use red hat linux 9 final release hit official end-of-life april 30 2004 although updates published 2006 fedora legacy project shut early 2007 version 3.0.3 one first linux distributions support executable linkable format instead older a.out format red hat linux introduced graphical installer called anaconda developed ketan bagal intended easy use novices since adopted linux distributions also introduced built-in tool called lokkit configuring firewall capabilities version 6 red hat moved glibc 2.1 egcs-1.2 2.2 kernel also introduced kudzu software library automatic discovery configuration hardware version 7 released preparation 2.4 kernel although first release still used stable 2.2 kernel glibc updated version 2.1.92 beta upcoming version 2.2 red hat used patched version gcc cvs called 2.96 decision ship unstable gcc version due gcc 2.95 bad performance non-i386 platforms especially dec alpha newer gccs also improved support c++ standard caused much existing code compile particular use non-released version gcc caused criticism e.g linus torvalds gcc steering committee red hat forced defend decision gcc 2.96 failed compile linux kernel software used red hat due stricter checks also incompatible c++ abi compilers distribution included previous version gcc compiling kernel called kgcc red hat linux 7.0 utf-8 enabled default character encoding system little effect english-speaking users enabled much easier internationalisation seamless support multiple languages including ideographic bi-directional complex script languages along european languages however cause negative reactions among existing western european users whose legacy iso-8859-based setups broken change version 8.0 also second include bluecurve desktop theme used common theme gnome-2 kde 3.0.2 desktops well openoffice-1.0 kde members appreciate change claiming best interests kde version 9 supported native posix thread library ported 2.4 series kernels red hat red hat linux lacked many features due possible copyright patent problems example mp3 support disabled rhythmbox xmms instead red hat recommended using ogg vorbis patents mp3 support however could installed afterwards although royalties required everywhere mp3 patented support microsoft ntfs file system also missing could freely installed well red hat linux originally developed exclusively inside red hat feedback users coming bug reports contributions included software packages – contributions distribution changed late 2003 red hat linux merged community-based fedora project new plan draw codebase fedora creating new red hat enterprise linux distributions fedora replaces original red hat linux download retail version model similar relationship netscape communicator mozilla staroffice openoffice.org although case resulting commercial product also fully free software release dates drawn announcements comp.os.linux.announce version names chosen cognitively related prior release yet related way release fedora red hat projects merged september 22 2003
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Operating systems
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codea codea lua code editor ios devices made two lives left designed rapidly prototyping visual ideas especially games simulations finished projects exported directly app xcode closely related processing programming language using many methods drawing functions found processing codea released app store late 2011 making one first ios lua editors april 2012 first game programmed entirely ipad using codea released app store march 2014 codea 2.0 released added 64-bit architecture redesigned code editor various api improvements october 4 2017 version 2.5 released added 3d voxel editing capability construction 3d worlds loading 3d models wavefront .obj file format also added february 2018 latest version codea released 2.52
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Programming language topics
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input/output configuration program original s/360 s/370 architectures processor set i/o channels addressed i/o devices 12-bit cuu address containing 4-bit channel number 8-bit unit device number sent channel bus order select device operating system configured reflect processor cuu address device operating system logic queue pending i/o channel handle selection alternate channels initiating i/o channel different processor required causing shoulder tap interrupt processor could initiate i/o starting ibm 3081 ibm 4381 s/370-extended architecture mode ibm changed i/o architecture allow channel subsystem handle channel scheduling operating system handle s/370 mode new i/o architecture used 16-bit channel path id chpid channel subsystem responsible mapping chpid channel device numbers queuing i/o requests selecting available paths installation responsible defining input/output configuration data sets iocds operator could select specific iocds part power reset por input/output configuration program iocp program ibm mainframes compiles description channel subsystem lpar configuration optionally loading input/output configuration data set iocds recognizes syntax mvs configuration program mvscp input need maintain separate input files direct use iocp mvscp mostly supplanted hardware configuration definition hcd
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Operating systems
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mobile security mobile security specifically mobile device security become increasingly important mobile computing particular concern security personal business information stored smartphones users businesses use smartphones communicate also plan organize users work also private life within companies technologies causing profound changes organization information systems therefore become source new risks indeed smartphones collect compile increasing amount sensitive information access must controlled protect privacy user intellectual property company smartphones computers preferred targets attacks attacks exploit weaknesses inherent smartphones come communication mode—like short message service sms aka text messaging multimedia messaging service mms wifi bluetooth gsm de facto global standard mobile communications also exploits target software vulnerabilities browser operating system malicious software relies weak knowledge average user security countermeasures developed applied smartphones security different layers software dissemination information end users good practices observed levels design use development operating systems software layers downloadable apps smartphone user exposed various threats use phone last two-quarters 2012 number unique mobile threats grew 261 according abi research threats disrupt operation smartphone transmit modify user data applications must guarantee privacy integrity information handle addition since apps could malware functionality activities limited example restricting apps accessing location information via gps blocking access user address book preventing transmission data network sending sms messages billed user etc. three prime targets attackers number threats mobile devices including annoyance stealing money invading privacy propagation malicious tools source attacks actors found non-mobile computing space smartphone infected attacker attacker attempt several things attacks derive flaws management sms mms mobile phone models problems managing binary sms messages possible sending ill-formed block cause phone restart leading denial service attacks user siemens s55 received text message containing chinese character would lead denial service another case standard requires maximum size nokia mail address 32 characters nokia phones verify standard user enters email address 32 characters leads complete dysfunction e-mail handler puts commission attack called curse silence study safety sms infrastructure revealed sms messages sent internet used perform distributed denial service ddos attack mobile telecommunications infrastructure big city attack exploits delays delivery messages overload network another potential attack could begin phone sends mms phones attachment attachment infected virus upon receipt mms user choose open attachment opened phone infected virus sends mms infected attachment contacts address book real-world example attack virus commwarrior uses address book sends mms messages including infected file recipients user installs software received via mms message virus began send messages recipients taken address book attacker may try break encryption mobile network gsm network encryption algorithms belong family algorithms called a5 due policy security obscurity possible openly test robustness algorithms originally two variants algorithm a5/1 a5/2 stream ciphers former designed relatively strong latter designed weak purpose allow easy cryptanalysis eavesdropping etsi forced countries typically outside europe use a5/2 since encryption algorithm made public proved possible break encryption a5/2 could broken fly a5/1 6 hours july 2007 3gpp approved change request prohibit implementation a5/2 new mobile phones means decommissioned longer implemented mobile phones stronger public algorithms added gsm standard a5/3 a5/4 block ciphers otherwise known kasumi uea1 published etsi network support a5/1 a5 algorithm implemented phone base station specify a5/0 null-algorithm whereby radio traffic sent unencrypted even case mobile phones able use 3g 4g much stronger encryption 2g gsm base station downgrade radio communication 2g gsm specify a5/0 encryption basis eavesdropping attacks mobile radio networks using fake base station commonly called imsi catcher addition tracing mobile terminals difficult since time mobile terminal accessing accessed network new temporary identity tmsi allocated mobile terminal tsmi used identity mobile terminal next time accesses network tmsi sent mobile terminal encrypted messages encryption algorithm gsm broken attacker intercept unencrypted communications made victim smartphone attacker try eavesdrop wi-fi communications derive information e.g username password type attack unique smartphones vulnerable attacks often wi-fi means communication access internet security wireless networks wlan thus important subject initially wireless networks secured wep keys weakness wep short encryption key connected clients addition several reductions search space keys found researchers wireless networks protected wpa security protocol wpa based temporal key integrity protocol tkip designed allow migration wep wpa equipment already deployed major improvements security dynamic encryption keys small networks wpa pre-shared key based shared key encryption vulnerable length shared key short limited opportunities input i.e numeric keypad mobile phone users might define short encryption keys contain numbers increases likelihood attacker succeeds brute-force attack successor wpa called wpa2 supposed safe enough withstand brute force attack gsm attacker succeeds breaking identification key possible attack phone also entire network connected many smartphones wireless lans remember already connected mechanism prevents user re-identify connection however attacker could create wifi access point twin parameters characteristics real network using fact smartphones remember networks could confuse two networks connect network attacker intercept data transmit data encrypted form lasco worm initially infects remote device using sis file format sis file format software installation script script file executed system without user interaction smartphone thus believes file come trusted source downloads infecting machine security issues related bluetooth mobile devices studied shown numerous problems different phones one easy exploit vulnerability unregistered services require authentication vulnerable applications virtual serial port used control phone attacker needed connect port take full control device another example phone must within reach bluetooth discovery mode attacker sends file via bluetooth recipient accepts virus transmitted example cabir worm spreads via bluetooth connection worm searches nearby phones bluetooth discoverable mode sends target device user must accept incoming file install program installing worm infects machine attacks based flaws os applications phone mobile web browser emerging attack vector mobile devices common web browsers mobile web browsers extended pure web navigation widgets plug-ins completely native mobile browsers jailbreaking iphone firmware 1.1.1 based entirely vulnerabilities web browser result exploitation vulnerability described underlines importance web browser attack vector mobile devices case vulnerability based stack-based buffer overflow library used web browser libtiff vulnerability web browser android discovered october 2008 iphone vulnerability due obsolete vulnerable library significant difference iphone vulnerability android sandboxing architecture limited effects vulnerability web browser process smartphones also victims classic piracy related web phishing malicious websites software run background etc big difference smartphones yet strong antivirus software available sometimes possible overcome security safeguards modifying operating system real-world examples section covers manipulation firmware malicious signature certificates attacks difficult 2004 vulnerabilities virtual machines running certain devices revealed possible bypass bytecode verifier access native underlying operating system results research published detail firmware security nokia symbian platform security architecture psa based central configuration file called swipolicy 2008 possible manipulate nokia firmware installed fact downloadable versions file human readable possible modify change image firmware vulnerability solved update nokia theory smartphones advantage hard drives since os files rom changed malware however systems possible circumvent symbian os possible overwrite file file name windows os possible change pointer general configuration file editable file application installed signing application verified series certificates one create valid signature without using valid certificate add list symbian os certificates directory firmware changes explained easy insert seemingly valid malicious certificate 2015 researchers french government agency agence nationale de la sécurité des systèmes d'information anssi demonstrated capability trigger voice interface certain smartphones remotely using specific electromagnetic waveforms exploit took advantage antenna-properties headphone wires plugged audio-output jacks vulnerable smartphones effectively spoofed audio input inject commands via audio interface juice jacking physical hardware vulnerability specific mobile platforms utilizing dual purpose usb charge port many devices susceptible data exfiltrated malware installed onto mobile device utilizing malicious charging kiosks set public places hidden normal charge adapters jail-breaking also physical access vulnerability mobile device users initiate hack devices unlock exploit weaknesses operating system mobile device users take control device jail-breaking customize interface installing applications change system settings allowed devices thus allowing tweak mobile devices operating systems processes run programs background thus devices expose variety malicious attack lead compromise important private data 2010 researcher university pennsylvania investigated possibility cracking device password smudge attack literally imaging finger smudges screen discern user password researchers able discern device password 68 time certain conditions outsiders may perform over-the-shoulder victims watching specific keystrokes pattern gestures unlock device password passcode smartphones permanent point access internet mostly compromised easily computers malware malware computer program aims harm system resides mobile malware variants increased 54 year 2017 trojans worms viruses considered malware trojan program smartphone allows external users connect discreetly worm program reproduces multiple computers across network virus malicious software designed spread computers inserting legitimate programs running programs parallel however must said malware far less numerous important smartphones computers nonetheless recent studies show evolution malware smartphones rocketed last years posing threat analysis detection typically attack smartphone made malware takes place 3 phases infection host accomplishment goal spread malware systems malware often uses resources offered infected smartphones use output devices bluetooth infrared may also use address book email address person infect user acquaintances malware exploits trust given data sent acquaintance infection means used malware get smartphone either use one faults previously presented may use gullibility user infections classified four classes according degree user interaction malware infected phone also seek accomplish goal usually one following monetary damage damage data and/or device concealed damage malware infected smartphone always aims spread one way another various malware exist world smartphones short description mobile ransomware type malware locks users mobile devices pay-to-unlock-your-device ploy grown leaps bounds threat category since 2014 specific mobile computing platforms users often less security-conscious particularly pertains scrutinizing applications web links trusting native protection capability mobile device operating system mobile ransomware poses significant threat businesses reliant instant access availability proprietary information contacts likelihood traveling businessman paying ransom unlock device significantly higher since disadvantage given inconveniences timeliness less likely direct access staff recent ransomware attack caused stir world attack caused many internet connected devices work companies spent large amount recover attacks diagram loads different behaviors smartphone malware terms effects smartphones see graph least 50 malware varieties exhibit negative behavior except ability spread multitude malware partly due variety operating systems smartphones however attackers also choose make malware target multiple platforms malware found attacks os able spread different systems begin malware use runtime environments like java virtual machine .net framework also use libraries present many operating systems malware carry several executable files order run multiple environments utilize propagation process practice type malware requires connection two operating systems use attack vector memory cards used purpose synchronization software used propagate virus security mechanisms place counter threats described presented section divided different categories act level range management security operating system behavioral education user threats prevented various measures depending case considering two cases mentioned first case one would protect system corruption application second case installation suspicious software would prevented first layer security smartphone operating system os beyond needing handle usual roles operating system e.g resource management scheduling processes device must also establish protocols introducing external applications data without introducing risk central paradigm mobile operating systems idea sandbox since smartphones currently designed accommodate many applications must mechanisms ensure applications safe phone applications data system user malicious program reaches mobile device vulnerable area presented system must small possible sandboxing extends idea compartmentalize different processes preventing interacting damaging based history operating systems sandboxing different implementations example ios focus limiting access public api applications app store default managed open allows restrict apps access types data android bases sandboxing legacy linux trustedbsd following points highlight mechanisms implemented operating systems especially android operating system security layer security software layer composed individual components strengthen various vulnerabilities prevent malware intrusions identification user human user authentication contains software components learned experience computer security however smartphones software must deal greater constraints see limitations mobile antivirus product would scan files compare database known mobile malware code signatures application passes various security barriers take actions designed actions triggered activity malicious application sometimes detected one monitors various resources used phone depending goals malware consequences infection always malicious applications intended harm devices deployed following sections describe different ways detect suspicious activity various points mentioned indications provide certainty legitimacy activity application however criteria help target suspicious applications especially several criteria combined network traffic exchanged phones monitored one place safeguards network routing points order detect abnormal behavior mobile use network protocols much constrained computer expected network data streams predicted e.g protocol sending sms permits detection anomalies mobile networks production distribution chain mobile devices responsibility manufacturers ensure devices delivered basic configuration without vulnerabilities users experts many aware existence security vulnerabilities device configuration provided manufacturers retained many users listed several points manufacturers consider much malicious behavior allowed carelessness user smartphone users found ignore security messages application installation especially application selection checking application reputation reviews security agreement messages simply leaving device without password precise control permissions granted applications added smartphone user large responsibility cycle security vector intrusion precaution especially important user employee company stores business data device detailed precautions user take manage security smartphone recent survey internet security experts bullguard showed lack insight rising number malicious threats affecting mobile phones 53 users claiming unaware security software smartphones 21 argued protection unnecessary 42 admitted n't crossed mind using apa 2011 statistics show consumers concerned security risks believe serious problem key always remember smartphones effectively handheld computers vulnerable latest android smartphones come inbuilt encryption setting securing information saved device makes difficult hacker extract decipher information case device compromised settings – security – encrypt phone encrypt sd card precautions measures leave easy solution intrusion people malicious applications smartphone users careful many attacks defeated especially phishing applications seeking obtain rights device one form mobile protection allows companies control delivery storage text messages hosting messages company server rather sender receiver phone certain conditions met expiration date messages deleted security mechanisms mentioned article large extent inherited knowledge experience computer security elements composing two device types similar common measures used antivirus software firewalls however implementation solutions necessarily possible least highly constrained within mobile device reason difference technical resources offered computers mobile devices even though computing power smartphones becoming faster limitations computing power furthermore common find updates exist developed deployed always done one example find user know newer version operating system compatible smartphone user may discover known vulnerabilities corrected end long development cycle allows time exploit loopholes expected four mobile environments make security framework
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Computer security
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barbara mcnamara barbara a. mcnamara born circa 1942 nsa deputy director october 1997 june 2000 succeeded william b black jr.. mcnamara joined nsa 1963 chinese linguist rose number analytic operational managerial positions leaving operational directorate 1983 mcnamara became first woman named deputy director operations 1994 1997 became second woman named agency deputy director june 2000 received us intelligence community highest award national intelligence distinguished service medal time one highest ranked women united states intelligence community served nsa senior u.s. liaison officer london england shortly retirement 2003 currently board member signalscape intec billing
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Computer security
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style jukebox style jukebox hi-fi high-resolution audio cloud music streaming storage player windows ios android windows phone platforms web player also available mac windows linux style jukebox allows users upload personal music collection computer style jukebox servers listen another compatible device android ios windows mac windows phone streaming downloading songs offline playback basic accounts 10 gb storage pro accounts 2 tb music july 2016 style jukebox 250,000 registered users december 1st 2017 style jukebox discontinued service small post home page details released style jukebox consists cloud-based services user management music storage programmatic interfaces apis clients music streaming storage desktop mobile operating systems upload available desktop client style jukebox enables users drop music files folders music player automatically uploaded synced style jukebox cloud-based services made available user computers devices also style jukebox client installed style jukebox cloud-based services automatically transcodes formats match device supported formats example 320kbit/s wma transcoded 320kbit/s mp3 ios devices flac lossless transcoded wma lossless windows phone devices
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Distributed computing architecture
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nokia e63 nokia e63 budget business smartphone announced 12 november 2008 released later year based symbian s60 platform although looks similar nokia e71 fascia made plastic aluminium e71 plastic chassis also keypad made different material laid slightly different e71 many specifications identical e71 except lack gps infrared lesser ram lack hsdpa lower-quality camera fixed-focus lens e63 come ability use camera flash light present e71 also standard 3.5 mm audio jack e71 uses 2.52 mm jack e63 retailed 199 euros taxes specifications current firmware version 510.21.010 released 28 march 2011 operating frequency
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Operating systems
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sql anywhere sap sql anywhere proprietary relational database management system rdbms product sap sql anywhere known sybase sql anywhere prior acquisition sybase sap sql anywhere run windows windows ce mac os x various unix platforms including linux aix hp-ux solaris database files independent operating system allowing copied supported platforms product provides several standard interfaces odbc jdbc ado.net number special interfaces php perl engine supports stored procedures user functions using watcom sql t-sql java c/c++ triggers referential integrity row-level locking replication high availability proxy tables events scheduled system events strong encryption supported database files client-server communication sql anywhere used several contexts including embedded database particularly application data store example used intuit quickbooks network management products backup products ability used minimal administration distinguishing feature role used database server work groups small medium-sized businesses also function mobile database includes scalable data synchronization technology provides change-based replication separate databases including large server-based rdbms systems sql anywhere server high performing embeddable relational database-management system rdbms scales thousands users server environments desktop mobile applications used widely deployed zero-administration environments ultralite ultralite database-management system designed small-footprint mobile devices pdas smart phones mobilink mobilink highly-scalable session-based synchronization technology exchanging data among relational databases non-relational data sources qanywhere qanywhere facilitates development robust secure store-and-forward mobile messaging applications sql remote sql remote technology based store forward architecture allows occasionally connected users synchronize data sql anywhere databases using file message transfer mechanism
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Databases
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share operating system share operating system sos created 1959 improvement general motors gm-naa i/o operating system first operating system share user group main target improve sharing programs gm-naa i/o share operating system provided new methods manage buffers input/output devices like gm-naa i/o allowed execution programs written assembly language initially worked ibm 709 computer transistorized compatible successor ibm 7090 series articles describing innovations system appears april 1959 journal association computing machinery 1962 ibm discontinued support sos announced entirely new incompatible operating system ibm 7090/94 ibsys
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Operating systems
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dataadapter ado.net dataadapter functions bridge data source disconnected data class dataset simplest level specify sql commands provide elementary crud functionality advanced level offers functions required order create strongly typed datasets including datarelations data adapters integral part ado.net managed providers set objects used communicate data source dataset addition adapters managed providers include connection objects data reader objects command objects adapters used exchange data data source dataset many applications means reading data database dataset writing changed data dataset back database however data adapter move data source dataset example could adapter moves data microsoft exchange server dataset sometimes data work primarily read-only rarely need make changes underlying data source situations also call caching data memory minimize number database calls data change data adapter makes easy accomplish things helping manage data disconnected mode data adapter fills dataset object reading data writes single batch persisting changes back database data adapter contains reference connection object opens closes connection automatically reading writing database additionally data adapter contains command object references select insert update delete operations data data adapter defined table dataset take care communication database need tell data adapter load write database
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Operating systems
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influence ibm pc personal computer market following introduction ibm personal computer ibm pc many personal computer architectures became extinct within years ibm pc introduced personal computer market dominated systems using 6502 z80 8-bit microprocessors trs 80 commodore pet apple ii series used proprietary operating systems computers running cp/m ibm introduced ibm pc 1984 ibm pc clones became dominant computers 1983 byte forecast 1990 ibm would command 11 business computer sales commodore predicted hold slim lead highly competitive market 11.9 around 1978 several 16-bit cpus became available examples included data general mn601 fairchild 9440 ferranti f100-l general instrument cp1600 cp1610 national semiconductor ins8900 panafacom mn1610 texas instruments tms9900 notably intel 8086 new processors expensive incorporate personal computers used 16-bit data bus needed rare thus expensive 16-bit peripheral support chips 50 new business-oriented personal computer systems came market year ibm released ibm pc used 16- 32-bit microprocessor 8-bit systems generally believed vendors perfectly adequate intel 8086 expensive use main manufacturers selling 8-bit business systems period august 12 1981 ibm released ibm personal computer one far-reaching decisions made ibm pc use open architecture leading large market third party add-in boards applications finally also many competitors creating ibm-compatible machines ibm pc used then-new intel 8088 processor like 16-bit cpus could access 1 megabyte ram used 8-bit-wide data bus memory peripherals design allowed use large readily available relatively inexpensive family 8-bit-compatible support chips ibm decided use intel 8088 first considering motorola 68000 intel i8086 two considered powerful needs although already established rivals like apple radio shack many advantages company new microcomputers ibm reputation business computing allowed ibm pc architecture take substantial market share business applications many small companies sold ibm-compatible software hardware rapidly grew size importance including tecmar quadram ast research microsoft mid-1982 three mainframe minicomputer companies sold microcomputers unlike ibm hewlett-packard xerox control data corporation chose cp/m operating system many companies made business personal computers using proprietary designs still using 8-bit microprocessors ones used intel x86 processors often used generic non-ibm-compatible specific version ms-dos cp/m-86 8-bit systems intel 8080 compatible cpu normally used cp/m within year ibm pc introduction microsoft licensed ms-dos 70 companies one first computers achieve 100 pc compatibility compaq portable released november 1982 remained compatible clone 1984 pc yet dominate market however x86-based systems clones ibm pc design different internal designs like cp/m-based 8-bit systems preceded ibm pc difficult obtain several years introduction many makers ms-dos computers intentionally avoided full ibm compatibility expected market infoworld described ordinary pc clones would decline shortage real pcs ended feared fate companies sold computers plug-compatible ibm mainframes 1960s 1970s—many went bankrupt ibm changed specifications—and believed market existed personal computers similar selection software ibm pc better hardware even years ibm pc introduction manufacturers digital hp sanyo tandy texas instruments tulip computers nec wang laboratories xerox continued introduce personal computers barely compatible ibm pc even though used x86 processors ran ms-dos used ms-dos way microsoft originally envisioned way 8-bit systems used cp/m implemented standard rom bios routines achieve hardware independence 8080 z80 compatibles machine different bios long software made standard ms-dos calls would ensure compatibility microsoft used sophisticated installer dos programs like multiplan provided device drivers many non ibm pc-compatible computers software vendors columbia university discussed difficulty kermit support many different clones ms-dos computers peter norton earlier encouraged vendors write software ran many different computers early 1985 admitted—after experiencing difficulty rewriting norton utilities—that practical way software creators write generic software dealers found carrying multiple versions software clones varying levels compatibility difficult get best results 8088 modest performance many popular software applications written specifically ibm pc developers programs opted write directly computer video memory peripheral chips bypassing ms-dos bios example program might directly update video refresh memory instead using ms-dos calls device drivers alter appearance screen many notable software packages spreadsheet program lotus 1-2-3 microsoft microsoft flight simulator 1.0 directly accessed ibm pc hardware bypassing bios therefore work computers even trivially different ibm pc especially common among pc games result systems fully ibm pc-compatible could n't run software quickly became obsolete rendered obsolete cp/m-inherited concept oem versions ms-dos meant run bios calls non ibm-pc hardware 1984 phoenix technologies began licensing clone ibm pc bios phoenix bios competitors ami bios made possible anyone market pc compatible computer without develop compatible bios like compaq although based i8086 enabling creation relatively low-cost x86-based systems intel 80186 quickly lost appeal x86-based pc builders supporting circuitry inside intel 80186 chip incompatible used standard pc chipset implemented ibm rarely used personal computers 1982 february 1984 byte described personal computer market seems shadowed cloud compatibility drive compatible ibm personal computer family assumed near-fetish proportions stated inevitable light phenomenal market acceptance ibm pc magazine cited announcement north star fall 1983 first pc-compatible microcomputer founded 1976 north star long successful 8-bit s-100 bus products introduced proprietary 16-bit products company acknowledged ibm pc become standard one north star needed follow byte described announcement representative great impact ibm made industry magazine expressed concern ibm burgeoning influence pc community stifling innovation many companies mimicking big blue admitting dealers asked kaypro also introduced company first ibm compatible year tandy—which much 60 personal-computer market attempted keep technical information secret monopolize software peripheral sales—also began selling non-proprietary computers four years jon shirley predicted infoworld new ibm pc major market would ibm addicts magazine 1985 similarly called ibm compatibility tandy 1000 small concession big blue dominating stranglehold company struggling openly blood-soaked arena personal computers 1000 compatible pc compatible tandy 2000 ms-dos computer ibm mainframe rivals bunch introduced compatibles hewlett-packard introduced vectra infoworld stated company responding demands customers full ibm pc compatibility mitch kapor lotus development corporation said 1984 either pc-compatible special compatibility proven safe path microsoft executive jim harris stated 1985 infoworld wrote ibm competitors whipped conformity designs total failure every company tried improve ibm pc customers wanted run pc applications like 1-2-3 developers cared massive pc installed base non-compatible—no matter technical superiority—from company apple failed lack customers software compatibility became important dave winer joked year referring pc incomplete compatibility ibm pc company introduce machine n't pc compatible survive ibm 1985 shortage ibm pcs ended causing financial difficulties many vendors compatibles nonetheless harris said ones done worse compatibles noncompatibles pc standard similarly dominant europe honeywell bull olivetti ericsson selling compatibles software companies focusing pc products end year pc magazine stated even ibm could longer introduce rumored proprietary non-compatible operating system noting company unsuccessful pcjr cardinal sin n't pc compatible magazine wrote backward compatibility ibm pc single largest concern hardware software developers user community large demanding accept radical changes abandon solutions worked past within years introduction fully compatible pc clones almost rival business personal computer systems alternate x86 using architectures gone market despite inherent dangers industry based de facto standard thriving pc clone industry emerged non-ibm pc-compatible systems remained systems classified home computers apple ii series business systems offered features available ibm pc high level integration e.g. bundled accounting inventory fault-tolerance multitasking multi-user features compaq prices comparable ibm company emphasized pc compatibles features quality corporate customers mid-1985 compute described wave inexpensive clones american asian companies caused prices decline end 1986 equivalent 1600 real ibm pc 256k ram two disk drives cost little 600 lower price apple iic consumers began purchasing dos computers home large numbers tandy estimated half 1000 sales went homes new leading edge model comprised 1 us home-computer market year toy discount stores sold clone made hyundai like stereo without demonstrator model salesman tandy inexpensive clones succeeded consumers—who saw superior lower-end game machines—where ibm failed two years earlier pcjr inexpensive home computers years earlier comparable price commodore amiga atari st apple iigs unlike pcjr clones fast faster ibm pc highly compatible users could bring work home large dos software library reassured worried orphaned technology consumers used spreadsheets entertainment former ability justifying buying computer could also perform latter pcs compatibles also gained significant share educational market longtime leader apple lost share january 1987 consumer electronics show commodore atari announced clones 1987 pc industry growing quickly formerly business-only platform become largest important market computer game companies outselling games apple ii commodore 64 ega video card inexpensive clone better games computers 1989 80 readers compute owned dos computers magazine announced greater emphasis ms-dos home computing ibm influence industry decreased competition increased rivals introduced computers improved ibm designs maintaining compatibility 1986 compaq deskpro 386 first computer based intel 80386 1987 ibm unsuccessfully attempted regain leadership market personal system/2 line proprietary microchannel architecture 1990 computer gaming world told reader complaining many reviews pc games companies attempting get ms-dos products door first reported ms-dos comprised 65 computer-game market amiga 10 computers including macintosh 10 declining amiga others st various msx2 computers remained market pc compatibles gained sufficient multimedia capabilities compete home computers advent inexpensive versions vga video card sound blaster sound card clones remaining home computers driven market 1995 macintosh almost new consumer-oriented systems sold ibm pc clones macintosh originally used motorola 68000 family processors later migrating powerpc architecture throughout 1990s apple would steadily transition macintosh platform proprietary expansion interfaces use standards pc world ide pci usb 2006 apple converted macintosh intel x86 architecture modern macintosh computers essentially ibm pc compatibles capable booting microsoft windows running ibm pc-compatible software still retain unique design elements support apple mac os x operating system 2008 sid meier listed ibm pc one three important innovations history video games shortly ibm pc released obvious split appeared systems opted use x86-compatible processor chose another architecture almost x86 systems provided version ms-dos others used many different operating systems although z80-based systems typically offered version cp/m common usage ms-dos unified x86-based systems promoting growth x86/ms-dos ecosystem non-x86 architectures died x86 systems standardized fully ibm pc compatible clones market filled dozens different competing systems reduced near-monoculture x86-based ibm pc compatible ms-dos systems early launch ibm pc 1981 still dozens systems ibm pc-compatible use intel x86 chips used intel 8088 8086 80186 processors almost without exception offered oem version ms-dos opposed oem version customized ibm use however generally made attempt copy ibm pc architecture machines different i/o addresses different system bus different video controllers differences original ibm pc differences sometimes rather minor used improve upon ibm pc design result differences software directly manipulated hardware would run correctly cases x86-based systems n't use fully ibm pc compatible design n't sell well enough attract support software manufacturers though computer manufacturers arranged compatible versions popular applications developed sold specifically machines fully ibm pc-compatible clones appeared market shortly thereafter advantages cloning became impossible ignore notable systems x86-compatible real clones manufacturers immediately switched intel x86 microprocessor family ms-dos companies continued releasing systems based non-intel architectures systems used 32-bit microprocessor popular motorola 68000 others continued use 8-bit microprocessors many systems eventually forced market onslaught ibm pc clones although architectures may superior capabilities especially area multimedia pc architectures era often cga display sound system internal pc speaker three systems era extinct thriving legacies
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Computer architecture
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heuristic analysis heuristic analysis method employed many computer antivirus programs designed detect previously unknown computer viruses well new variants viruses already wild heuristic analysis expert based analysis determines susceptibility system towards particular threat/risk using various decision rules weighing methods multicriteria analysis mca one means weighing method differs statistical analysis bases available data/statistics antivirus programs utilize heuristic analysis perform function executing programming commands questionable program script within specialized virtual machine thereby allowing anti-virus program internally simulate would happen suspicious file executed keeping suspicious code isolated real-world machine analyzes commands performed monitoring common viral activities replication file overwrites attempts hide existence suspicious file one virus-like actions detected suspicious file flagged potential virus user alerted another common method heuristic analysis anti-virus program decompile suspicious program analyze machine code contained within source code suspicious file compared source code known viruses virus-like activities certain percentage source code matches code known viruses virus-like activities file flagged user alerted heuristic analysis capable detecting many previously unknown viruses new variants current viruses however heuristic analysis operates basis experience comparing suspicious file code functions known viruses means likely miss new viruses contain previously unknown methods operation found known viruses hence effectiveness fairly low regarding accuracy number false positives new viruses discovered human researchers information added heuristic analysis engine thereby providing engine means detect new viruses heuristic analysis method detecting viruses examining code suspicious properties traditional methods virus detection involve identifying malware comparing code program code known virus types already encountered analyzed recorded database – known signature detection useful still use signature detection method also become limited due development new threats exploded around turn century continuing emerge time counter problem heuristic model specifically designed spot suspicious characteristics found unknown new viruses modified versions existing threats well known malware samples cybercriminals constantly developing new threats heuristic analysis one methods used deal huge volume new threats seen daily heuristic analysis also one methods capable combating polymorphic viruses — term malicious code constantly changes adapts heuristic analysis incorporated advanced security solutions offered companies like kaspersky labs detect new threats cause harm without need specific signature heuristic analysis employ number different techniques one heuristic method known static heuristic analysis involves de-compiling suspect program examining source code code compared viruses already known heuristic database particular percentage source code matches anything heuristic database code flagged possible threat another method known dynamic heuristics scientists want analyze something suspicious without endangering people contain substance controlled environment like secure lab conduct tests process similar heuristic analysis — virtual world isolates suspicious program piece code inside specialized virtual machine — sandbox — gives antivirus program chance test code simulate would happen suspicious file allowed run examines command activated looks suspicious behaviors self-replication overwriting files actions common viruses potential issues reported user heuristic analysis ideal identifying new threats effective heuristics must carefully tuned provide best possible detection new threats without generating false positives perfectly innocent code reason heuristic tools often typically one weapon sophisticated antivirus arsenal typically deployed along methods virus detection signature analysis proactive technologies
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Computer security
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mqtt mqtt message queuing telemetry transport iso standard iso/iec prf 20922 publish-subscribe-based messaging protocol works top tcp/ip protocol suite designed connections remote locations small code footprint required network bandwidth limited publish-subscribe messaging pattern requires message broker andy stanford-clark ibm arlen nipper cirrus link authored first version protocol 1999 2013 ibm submitted mqtt v3.1 oasis specification body charter ensured minor changes specification could accepted mqtt-sn variation main protocol aimed embedded devices non-tcp/ip networks zigbee historically mq mqtt came ibm mq 'mqseries message queuing product line however queuing required supported standard feature situations alternative message-oriented middleware includes advanced message queuing protocol amqp streaming text oriented messaging protocol stomp ietf constrained application protocol xmpp dds opc ua web application messaging protocol wamp mqtt system consists clients communicating server often called broker client may either publisher information subscriber client connect broker information organized hierarchy topics publisher new item data distribute sends control message data connected broker broker distributes information clients subscribed topic publisher need data number locations subscribers subscribers turn configured data publishers broker receives topic current subscribers discard topic unless publisher indicates topic retained allows new subscribers topic receive current value rather waiting next update publisher publishing client first connects broker set default message sent subscribers broker detects publishing client unexpectedly disconnected broker clients interact broker system may contain several broker servers exchange data based current subscribers topics minimal mqtt control message little two bytes data control message carry nearly 256 megabytes data needed fourteen defined message types used connect disconnect client broker publish data acknowledge receipt data supervise connection client server mqtt relies tcp protocol data transmission variant mqtt-sn used transports udp bluetooth mqtt sends connection credentials plain text format include measures security authentication provided underlying tcp transport using measures protect integrity transferred information interception duplication waits connection established server creates link nodes waits mqtt client finish work must tcp/ip session disconnect returns immediately application thread passing request mqtt client connection broker specify quality service measure classified increasing order overhead field affect handling underlying tcp data transmissions used mqtt senders receivers several projects implement mqtt examples
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Internet protocols
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real-time operating system real-time operating system rtos operating system os intended serve real-time applications process data comes typically without buffer delays processing time requirements including os delay measured tenths seconds shorter increments time real-time system time bound system well defined fixed time constraints processing must done within defined constraints system fail either event driven time sharing event driven systems switch tasks based priorities time sharing systems switch task based clock interrupts rtoss use pre-emptive scheduling algorithm key characteristic rtos level consistency concerning amount time takes accept complete application task variability 'jitter 'hard real-time operating system less jitter 'soft real-time operating system chief design goal high throughput rather guarantee soft hard performance category rtos usually generally meet deadline soft real-time os meet deadline deterministically hard real-time os rtos advanced algorithm scheduling scheduler flexibility enables wider computer-system orchestration process priorities real-time os frequently dedicated narrow set applications key factors real-time os minimal interrupt latency minimal thread switching latency real-time os valued quickly predictably respond amount work perform given period time see comparison real-time operating systems comprehensive list also see list operating systems types operating systems common designs time sharing designs switch tasks often strictly needed give smoother multitasking giving illusion process user sole use machine early cpu designs needed many cycles switch tasks cpu could nothing else useful example 20 mhz 68000 processor typical late 1980s task switch times roughly 20 microseconds contrast 100 mhz arm cpu 2008 switches less 3 microseconds early oses tried minimize wasting cpu time avoiding unnecessary task switching typical designs task three states tasks blocked ready time generally one task run time per cpu number items ready queue vary greatly depending number tasks system needs perform type scheduler system uses simpler non-preemptive still multitasking systems task give time cpu tasks cause ready queue greater number overall tasks ready executed state resource starvation usually data structure ready list scheduler designed minimize worst-case length time spent scheduler critical section preemption inhibited cases interrupts disabled choice data structure depends also maximum number tasks ready list never tasks ready list doubly linked list ready tasks likely optimal ready list usually contains tasks occasionally contains list sorted priority way finding highest priority task run require iterating entire list inserting task requires walking ready list reaching either end list task lower priority task inserted care must taken inhibit preemption search longer critical sections divided small pieces interrupt occurs makes high priority task ready insertion low priority task high priority task inserted run immediately low priority task inserted critical response time sometimes called flyback time time takes queue new ready task restore state highest priority task running well-designed rtos readying new task take 3 20 instructions per ready-queue entry restoration highest-priority ready task take 5 30 instructions advanced systems real-time tasks share computing resources many non-real-time tasks ready list arbitrarily long systems scheduler ready list implemented linked list would inadequate commonly used rtos scheduling algorithms multitasking operating system like unix poor real-time tasks scheduler gives highest priority jobs lowest demand computer way ensure time-critical job access enough resources multitasking systems must manage sharing data hardware resources among multiple tasks usually unsafe two tasks access specific data hardware resource simultaneously three common approaches resolve problem general-purpose operating systems usually allow user programs mask disable interrupts user program could control cpu long wishes modern cpus allow user mode code disable interrupts control considered key operating system resource many embedded systems rtoss however allow application run kernel mode greater system call efficiency also permit application greater control operating environment without requiring os intervention single-processor systems application running kernel mode masking interrupts lowest overhead method prevent simultaneous access shared resource interrupts masked current task make blocking os call current task exclusive use cpu since task interrupt take control critical section protected task exits critical section must unmask interrupts pending interrupts execute temporarily masking interrupts done longest path critical section shorter desired maximum interrupt latency typically method protection used critical section instructions contains loops method ideal protecting hardware bit-mapped registers bits controlled different tasks shared resource must reserved without blocking tasks waiting flash memory written better use mechanisms also available general-purpose operating systems mutex os-supervised interprocess messaging mechanisms involve system calls usually invoke os dispatcher code exit typically take hundreds cpu instructions execute masking interrupts may take one instruction processors non-recursive mutex either locked unlocked task locked mutex tasks must wait mutex unlocked owner original thread task may set timeout wait mutex several well-known problems mutex based designs priority inversion deadlocks priority inversion high priority task waits low priority task mutex lower priority task given cpu time finish work typical solution task owns mutex 'inherit priority highest waiting task simple approach gets complex multiple levels waiting task waits mutex locked task b waits mutex locked task c handling multiple levels inheritance causes code run high priority context thus cause starvation medium-priority threads deadlock two tasks lock mutex without timeouts wait forever task mutex creating cyclic dependency simplest deadlock scenario occurs two tasks alternately lock two mutex opposite order deadlock prevented careful design approach resource sharing tasks send messages organized message passing scheme paradigm resource managed directly one task another task wants interrogate manipulate resource sends message managing task although real-time behavior less crisp semaphore systems simple message-based systems avoid protocol deadlock hazards generally better-behaved semaphore systems however problems like semaphores possible priority inversion occur task working low-priority message ignores higher-priority message message originating indirectly high priority task incoming message queue protocol deadlocks occur two tasks wait send response messages since interrupt handler blocks highest priority task running since real-time operating systems designed keep thread latency minimum interrupt handlers typically kept short possible interrupt handler defers interaction hardware possible typically necessary acknowledge disable interrupt wo n't occur interrupt handler returns notify task work needs done done unblocking driver task releasing semaphore setting flag sending message scheduler often provides ability unblock task interrupt handler context os maintains catalogues objects manages threads mutexes memory updates catalogue must strictly controlled reason problematic interrupt handler calls os function application act also os function called interrupt handler could find object database inconsistent state application update two major approaches deal problem unified architecture segmented architecture rtoss implementing unified architecture solve problem simply disabling interrupts internal catalogue updated downside interrupt latency increases potentially losing interrupts segmented architecture make direct os calls delegates os related work separate handler handler runs higher priority thread lower interrupt handlers advantage architecture adds cycles interrupt latency result oses implement segmented architecture predictable deal higher interrupt rates compared unified architecture similarly system management mode x86 compatible hardware take much time returns control operating system generally wrong write real-time software x86 hardware memory allocation critical real-time operating system operating systems first stability memory leaks memory allocated freed use device work indefinitely without ever needing reboot reason dynamic memory allocation frowned upon whenever possible required memory allocation specified statically compile time another reason avoid dynamic memory allocation memory fragmentation frequent allocation releasing small chunks memory situation may occur available memory divided several sections rtos incapable allocating large enough continuous block memory although enough free memory secondly speed allocation important standard memory allocation scheme scans linked list indeterminate length find suitable free memory block unacceptable rtos since memory allocation occur within certain amount time mechanical disks much longer unpredictable response times swapping disk files used reasons ram allocation discussed simple fixed-size-blocks algorithm works quite well simple embedded systems low overhead
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Operating systems
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wireless datagram protocol wireless datagram protocol wdp defines movement information receiver sender resembles user datagram protocol internet protocol suite wireless datagram protocol wdp protocol wap architecture covers transport layer protocols internet model general transport service wdp offers upper layers invisible interface independent underlying network technology used consequence interface common transport protocols upper layer protocols wap architecture operate independently underlying wireless network letting transport layer deal physical network-dependent issues global interoperability acquired using mediating gateways
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Internet protocols
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tensilica tensilica company based silicon valley semiconductor intellectual property core business part cadence design systems tensilica known customizable xtensa configurable processor microprocessor core products include hifi audio/voice dsps software library 225 codecs cadence 100 software partners vision dsps handle complex algorithms imaging video computer vision neural networks connx family baseband dsps ranging dual-mac connx d2 64-mac connx bbe64ep tensilica founded 1997 chris rowen one founders mips technologies employed earl killian contributed mips architecture director architecture march 11 2013 cadence design systems announced intent buy tensilica approximately 380 million cash cadence completed acquisition april 2013 cash outlay closing approximately 326 million cadence tensilica develops sip blocks included chip ic designs products licensees system chip embedded systems tensilica processors delivered synthesizable rtl easy integration chip designs xtensa processors range small low-power cache-less microcontroller high-performance 16-way simd processors 3-issue vliw dsp cores 1 tmac/sec neural network processors cadence standard dsps based xtensa architecture xtensa architecture offers user-customizable instruction set automated customization tools extend xtensa base instruction set including simd instructions new register files xtensa instruction set 32-bit architecture compact 16- 24-bit instruction set base instruction set 80 risc instructions includes 32-bit alu 64 general-purpose 32-bit registers six special-purpose registers amd trueaudio found e.g playstation 4 kaveri desktop apus amd graphics cards based cadence tensilica hifi ep audio dsp microsoft hololens uses special custom-designed tsmc-fabricated 28nm coprocessor 24 tensilica dsp cores around 65 million logic gates 8 mb sram additional layer 1 gb low-power ddr3 ram espressif esp8266 esp32 wi-fi iot socs spreadtrum licensed hifi dsp smartphones via technologies uses hifi dsp soc set top box tablets mobile devices realtek standardized hifi audio dsp mobile pc products brand name tensilica combination word tensile meaning capable extended word silica silicon element integrated circuits primarily made
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Computer architecture
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f16c f16c previously/informally known cvt16 instruction set x86 instruction set architecture extension provides support converting half-precision standard ieee single-precision floating-point formats cvt16 instruction set announced amd may 1 2009 extension 128-bit sse core instructions x86 amd64 instruction set cvt16 revision part sse5 instruction set proposal announced august 30 2007 supplemented xop fma4 instruction sets revision makes binary coding proposed new instructions compatible intel avx instruction extensions functionality instructions unchanged recent documents name f16c formally used intel amd x86-64 architecture specifications variants convert four floating-point values xmm register 8 floating-point values ymm register instructions abbreviations vector convert packed half packed single vice versa 8-bit immediate argument codice_5 selects rounding mode values 0–4 select nearest truncate mode set codice_6 support instructions indicated bit 29 ecx cpuid eax=1
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Computer architecture
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university michigan executive system university michigan executive system umes batch operating system developed university michigan 1958 widely used many universities based general motors executive system ibm 701 umes revised work mainframe computers use university michigan time ibm 704 709 7090 work better small student jobs expected primary work load university umes use university michigan 1967 mts phased take advantage newer virtual memory time-sharing technology became available ibm system/360 model 67
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Operating systems
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arc processor arc argonaut risc core embedded processors family 32-bit central processing units cpus originally designed arc international arc processors optimized wide range uses widely used system chip soc devices storage home mobile automotive internet things iot applications licensed 200 organizations shipped 1.5 billion products per year arc processors use reduced instruction set computing risc employ 16-/32-bit arcompact instruction set architecture isa provides good performance code density embedded host soc applications arc concept developed initially within argonaut games series 3d pipeline development projects starting super fx chip super nintendo entertainment system 1995 argonaut split argonaut technologies limited atl variety technology projects argonaut software limited asl start 1996 general manager argonaut john edelson started reducing atl projects brender motion capture investing development arc concept september 1996 rick clucas decided value arc processor people using rather argonaut projects using asked bob terwilliger join ceo rick clucas took role cto 1997 following investment apax partners atl became arc international totally independent argonaut games prior initial public offering london stock exchange underwritten goldman sachs five investment banks three related technology companies acquired metaware santa cruz california development modeling software vautomation nashua new hampshire peripheral semiconductor ip precise software nepean ontario rtos arc international acquired synopsys 2010 arc processors part synopsys designware series designers differentiate products using patented configuration technology tailor arc processor instance meet specific performance power area requirements configuration arc processors occurs design time using architect processor configurator core designed extensible allowing designers add custom instructions significantly increase performance reduce power consumption unlike embedded microprocessors extra instructions registers functionality added modular fashion customers analyse task break operations choose appropriate extensions develop create custom microprocessor might optimise speed energy efficiency code density extensions include example memory management unit mmu fast multiplier–accumulator usb host viterbi path decoder user proprietary rtl functions processors synthesizable implemented foundry process supported complete suite development tools
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Computer architecture
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tcp half-open term half-open refers tcp connections whose state synchronization two communicating hosts possibly due crash one side connection process established also known embryonic connection lack synchronization could due malicious intent according rfc 793 tcp connection referred half-open host one end tcp connection crashed otherwise removed socket without notifying end remaining end idle connection may remain half-open state unbounded periods time nowadays however term half-open connection often used describe embryonic connection i.e tcp connection process established tcp three state system opening connection first originating endpoint sends syn packet destination b embryonic state specifically syn_sent awaiting response b updates kernel information indicate incoming connection sends request open channel back syn/ack packet point b also embryonic state specifically syn_rcvd note b put state another machine outside b control normal circumstances see denial-of-service attack deliberate failure cases receive syn/ack b update tables enough information send receive send final ack back b b receives final ack also sufficient information two-way communication connection fully open endpoints established state
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Internet protocols
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project 25 project 25 p25 apco-25 suite standards digital mobile radio communications designed use public safety organizations north america p25 radios direct replacement analog uhf example fm radios add ability transfer data well voice allowing natural implementation encryption messaging p25 radios commonly implemented dispatch organizations police fire ambulance emergency rescue service using vehicle-mounted radios combined walkie-talkie handheld use starting around 2012 products became available newer phase 2 modulation protocol older protocol known p25 became p25 phase 1 p25 phase 2 products use advanced ambe2+ vocoder allows audio pass compressed bitstream provides two tdma voice channels rf bandwidth 12.5 khz phase 1 provide one voice channel two protocols compatible however p25 phase 2 infrastructure provide dynamic transcoder feature translates phase 1 phase 2 needed addition phase 2 radios backwards compatible phase 1 modulation analog fm modulation per standard hand eu area created standard terrestrial trunked radio similar project 25 p25 fills similar role tetra dmr protocols public safety radios upgraded analog fm digital since 1990s increased use data radio systems features gps location trunking text messaging metering encryption various user protocols different public safety radio spectrum made difficult public safety agencies achieve interoperability widespread acceptance however lessons learned disasters united states faced past decades forced agencies assess requirements disaster basic infrastructure failed meet growing demands public safety digital radio communication united states federal communications commission fcc direction united states congress initiated 1988 inquiry recommendations users manufacturers improve existing communication systems based recommendations find solutions best serve needs public safety management october 1989 apco project 25 came existence coalition steering committee consisting representatives above-mentioned agencies along fpic department homeland security federal partnership interoperable communication coast guard department commerce national institute standards technology nist office law enforcement standards established decide priorities scope technical development p25 interoperable emergency communication integral initial response public health community safety national security economic stability problems experienced disaster events one serious poor communication due lack appropriate efficient means collect process transmit important information timely fashion cases radio communication systems incompatible inoperable within jurisdiction within departments agencies community non-operability occurs due use outdated equipment limited availability radio frequencies isolated independent planning lack coordination cooperation agencies community priorities competing resources funding ownership control communications systems recognizing understanding need project 25 p25 initiated collaboratively public safety agencies manufacturers address issue emergency communication systems p25 collaborative project ensure two-way radios interoperable goal p25 enable public safety responders communicate thus achieve enhanced coordination timely response efficient effective use communications equipment p25 established address need common digital public safety radio communications standards first-responders homeland security/emergency response professionals telecommunications industry association tr-8 engineering committee facilitates work role ansi-accredited standards development organization sdo published p25 suite standards tia-102 series documents include 49 separate parts land mobile radio tdma implementations technology public safety p25-compliant systems increasingly adopted deployed radios communicate analog mode legacy radios either digital analog mode p25 radios additionally deployment p25-compliant systems allow high degree equipment interoperability compatibility p25 standards use proprietary improved multi-band excitation imbe advanced multi-band excitation ambe+2 voice codecs designed digital voice systems inc. encode/decode analog audio signals rumored licensing cost voice-codecs used p25 standard devices main reason cost p25 compatible devices high p25 may used talk around mode without intervening equipment two radios conventional mode two radios communicate repeater base station without trunking trunked mode traffic automatically assigned one voice channels repeater base station protocol supports use data encryption standard des encryption 56 bit 2-key triple-des encryption three-key triple-des encryption advanced encryption standard aes encryption 256 bits keylength rc4 40 bits sold motorola advanced digital privacy encryption protocol also supports accordion 1.3 baton firefly mayfly saville type 1 ciphers p25 suite standards specify eight open interfaces various components land mobile radio system interfaces p25-compliant technology deployed two main phases future phases yet finalized phase 1 radio systems operate 12.5 khz digital mode using fdma access method phase 1 radios use continuous 4 level fm c4fm modulation—a special type 4fsk modulation—for digital transmissions 4,800 baud 2 bits per symbol yielding 9,600 bits per second total channel throughput 9,600 4,400 voice data generated imbe codec 2,800 forward error correction 2,400 signalling control functions receivers designed c4fm standard also demodulate compatible quadrature phase shift keying cqpsk standard parameters cqpsk signal chosen yield signal deviation symbol time c4fm phase 1 uses imbe voice codec systems involve standardized service facility specifications ensuring manufacturers compliant subscriber radio access services described specifications abilities include backward compatibility interoperability systems across system boundaries regardless system infrastructure addition p25 suite standards provides open interface radio frequency rf subsystem facilitate interlinking different vendors systems improve spectrum use p25 phase 2 developed trunking systems using 2-slot tdma scheme required new trunking systems 700 mhz band phase 2 uses ambe+2 voice codec reduce needed bitrate one voice channel require 6,000 bits per second including error correction signalling phase 2 backwards compatible phase 1 due tdma vs fdma operation although tdma radios systems capable operating phase 1 fdma required subscriber radio use tdma transmissions without time source therefore direct radio radio communications talkaround resorts fdma subscriber radios also resort narrow-band fm least common denominator almost two way radio could make analog narrow-band fm de facto interoperability mode time originally implementation phase 2 planned use 6.25 khz bandwidth per frequency allocation fdma however proved advantageous use existing 12.5 khz frequency allocations tdma mode number reasons first eliminated huge administrative process reallocating frequency assignments fcc existing phase 1 users second reduced amount base station transmitters one transmitter needed broadcast two voice slots third allowed subscriber radios save battery life transmitting half time also yields ability subscriber radio listen respond system requests transmissions phase 2 known 6.25 khz bandwidth equivalent satisfies fcc requirement voice transmissions occupy less bandwidth voice traffic phase 2 system transmits full 12.5 khz per frequency allocation phase 1 system however faster data rate 12 kbit/s allowing two simultaneous voice transmissions subscriber radios also transmit full 12.5 khz on/off repeating fashion resulting half transmission thus equivalent 6.25 khz per radio accomplished using ambe voice coder uses half rate phase 1 imbe voice coders 2000 2009 european telecommunications standards institute etsi tia working collaboratively public safety partnership project project mesa mobility emergency safety applications sought define unified set requirements next-generation aeronautical terrestrial digital wideband/broadband radio standard could used transmit receive voice video high-speed data wide-area multiple-agency networks deployed public safety agencies final functional technical requirements released etsi expected shape next phases american project 25 european dmr dpmr tetra interest industry followed since requirements could met available commercial off-the-shelf technology project closed 2010 united states 2008 wireless spectrum auction fcc allocated 20 mhz 700 mhz uhf radio band spectrum freed digital tv transition public safety networks fcc expects providers employ lte high-speed data video applications p25 systems resort using band signaling continuous tone-coded squelch system ctcss tone digital-coded squelch dcs codes access control instead use called network access code nac included outside digital voice frame 12 bit code prefixes every packet data sent including carrying voice transmissions nac feature similar ctcss dcs analog radios radios programmed pass audio receiving correct nac nacs programmed three-hexadecimal-digit code transmitted along digital signal transmitted since nac three-hexadecimal-digit number 12 bits 4,096 possible nacs programming far analog methods combined three possible nacs special functions adoption standards slowed budget problems us however funding communications upgrades department homeland security usually requires migrating project 25 also used countries worldwide including australia new zealand brazil canada india russia mid-2004 660 networks p25 deployed 54 countries time 2005 european terrestrial trunked radio tetra deployed sixty countries preferred choice europe china countries largely based tetra systems many times cheaper p25 systems 900 vs 6,000 radio time however p25 radio prices rapidly approaching parity tetra radio prices increased competition p25 market majority p25 networks based northern america advantage p25 system coverage frequency bandwidth earlier analog systems use channels easily upgraded one one p25 networks also allow intelligent migration analog radios digital radios operating within network p25 tetra offer varying degrees functionality depending available radio spectrum terrain project budget interoperability major goal p25 many p25 features present interoperability challenges theory p25 compliant equipment interoperable practice interoperable communications n't achievable without effective governance standardized operating procedures effective training exercises inter-jurisdictional coordination difficulties inherent developing p25 networks using features digital voice encryption trunking sometimes result feature-backlash organizational retreat minimal feature-free p25 implementations fulfill letter project 25 migration requirement without realizing benefits thereof additionally technical issue per se frictions often result unwieldy bureaucratic inter-agency processes tend develop order coordinate interoperability decisions securecomm 2011 conference london security researcher steve glass presented paper written co-author matt ames explained des-ofb motorola proprietary adp rc4 based ciphers vulnerable brute force key recovery research result op25 project uses gnu radio ettus universal software radio peripheral usrp implement open source p25 packet sniffer analyzer op25 project founded steve glass early 2008 performing research wireless networks part phd thesis paper available download nicta website 2011 wall street journal published article describing research security flaws system including user interface makes difficult users recognize transceivers operating secure mode according article r esearchers university pennsylvania overheard conversations included descriptions undercover agents confidential informants plans forthcoming arrests information technology used surveillance operations researchers found messages sent radios sent segments blocking portion segments result entire message jammed research also shows radios effectively jammed single radio short range using highly modified pink electronic child ’ toy standard used radios 'provides convenient means attacker continuously track location radio ’ user systems jammers expend lot power block communications p25 radios allow jamming relatively low power enabling researchers prevent reception using 30 toy pager designed pre-teens report presented 20th usenix security symposium san francisco august 2011 report noted number security flaws project 25 system specific way implemented inherent security design report find breaks p25 encryption however observed large amounts sensitive traffic sent clear due implementations problems found switch markings secure clear modes difficult distinguish ∅ vs. exacerbated fact p25 radios set secure mode continue operate without issuing warning another party switches clear mode addition report authors said many p25 systems change keys often increasing risk individual radio net may properly keyed forcing users net transmit clear maintain communications radio one design choice use lower levels error correction portions encoded voice data deemed less critical intelligibility result bit errors may expected typical transmissions harmless voice communication presence errors force use stream ciphers tolerate bit errors prevents use standard technique message authentication codes macs protect message integrity stream cipher attacks varying levels error correction implemented breaking p25 message frames subframes allows attacker jam entire messages transmitting certain short subframes critical reception entire frame result attacker effectively jam project 25 signals average power levels much lower power levels used communication attacks targeted encrypted transmissions forcing users transmit clear project 25 radios designed work existing two-way radio frequency channels use spread spectrum modulation inherently jam-resistant optimal spread spectrum system require effective jammer use 1,000 times much power 30 db individual communicators according report p25 jammer could effectively operate 1/25th power 14 db less communicating radios authors developed proof-of-concept jammer using texas instruments cc1110 single chip radio found inexpensive toy certain metadata fields project 25 protocol encrypted allowing attacker perform traffic analysis identify users project 25 radios respond bad data packets addressed retransmission request attacker deliberately send bad packets forcing specific radio transmit even user attempting maintain radio silence tracking authorized users considered feature p25 referred presence report authors concluded saying reasonable wonder protocol developed many years used sensitive critical applications difficult use vulnerable attack authors separately issued set recommendations p25 users mitigate problems found include disabling secure/clear switch using network access codes segregate clear encrypted traffic compensating unreliability p25 over-the-air rekeying extending key life p25 tetra used fifty-three countries worldwide public safety private sector radio networks differences features capacities
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Computer security
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kernel debugger kernel debugger debugger present operating system kernels ease debugging kernel development kernel developers kernel debugger might stub implementing low-level operations full-blown debugger gdb running another machine sending commands stub serial line network connection might provide command line used directly machine debugged operating systems operating system kernels contain kernel debugger
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Computer architecture
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wannacry ransomware attack wannacry ransomware attack may 2017 worldwide cyberattack wannacry ransomware cryptoworm targeted computers running microsoft windows operating system encrypting data demanding ransom payments bitcoin cryptocurrency propagated eternalblue exploit developed united states national security agency nsa older windows systems eternalblue stolen leaked group called shadow brokers months prior attack microsoft released patches previously close exploit much wannacry spread organizations applied using older windows systems past end-of-life wannacry also took advantage installing backdoors onto infected systems attack stopped within days discovery due emergency patches released microsoft discovery kill switch prevented infected computers spreading wannacry attack estimated affected 200,000 computers across 150 countries total damages ranging hundreds millions billions dollars security experts believed preliminary evaluation worm attack originated north korea agencies working country december 2017 united states united kingdom australia formally asserted north korea behind attack new variant wannacry ransomware forced taiwan semiconductor manufacturing company tsmc temporarily shut several chip-fabrication factories august 2018 virus spread 10,000 machines tsmc advanced facilities wannacry ransomware cryptoworm targeted computers running microsoft windows operating system encrypting data demanding ransom payments bitcoin cryptocurrency worm also known wannacrypt wana decrypt0r 2.0 wanacrypt0r 2.0 wan na decryptor considered network worm also includes transport mechanism automatically spread transport code scans vulnerable systems uses eternalblue exploit gain access doublepulsar tool install execute copy wannacry versions 0 1 2 created using microsoft visual c++ 6.0 eternalblue exploit windows server message block smb protocol released shadow brokers much attention comment around event occasioned fact u.s. national security agency nsa exploit likely stolen already discovered vulnerability used create exploit offensive work rather report microsoft microsoft eventually discovered vulnerability tuesday 14 march 2017 issued security bulletin ms17-010 detailed flaw announced patches released windows versions currently supported time windows vista windows 7 windows 8.1 windows 10 windows server 2008 windows server 2008 r2 windows server 2012 windows server 2016 doublepulsar backdoor tool also released shadow brokers 14 april 2017 starting 21 april 2017 security researchers reported tens thousands computers doublepulsar backdoor installed 25 april reports estimated number infected computers could several hundred thousand numbers increasing every day wannacry code take advantage existing doublepulsar infection installs executed wannacry malware first checks kill switch domain name found ransomware encrypts computer data attempts exploit smb vulnerability spread random computers internet laterally computers network modern ransomware payload displays message informing user files encrypted demands payment around us 300 bitcoin within three days us 600 within seven days three hardcoded bitcoin addresses wallets used receive payments victims wallets transactions balances publicly accessible even though cryptocurrency wallet owners remain unknown several organizations released detailed technical writeups malware including microsoft cisco malwarebytes symantec mcafee attack began friday 12 may 2017 evidence pointing initial infection asia 07:44 utc initial infection likely exposed vulnerable smb port rather email phishing initially assumed within day code reported infected 230,000 computers 150 countries organizations installed microsoft security update april 2017 affected attack still running unsupported versions microsoft windows windows xp windows server 2003 particularly high risk security patches released since april 2014 exception one emergency patch released may 2014 kaspersky lab study reported however less 0.1 percent affected computers running windows xp 98 percent affected computers running windows 7 controlled testing environment cybersecurity firm kryptos logic found unable infect windows xp system wannacry using exploits payload failed load caused operating system crash rather actually execute encrypt files however executed manually wannacry could still operate windows xp experts quickly advised affected users paying ransom due reports people getting data back payment high revenues would encourage campaigns 14 june 2017 attack subsided total 327 payments totaling us 130,634.77 51.62396539 xbt transferred day initial attack may microsoft released out-of-band security updates end life products windows xp windows server 2003 windows 8 patches created february year following tip vulnerability january year organizations advised patch windows plug vulnerability order protect cyber attack head microsoft cyber defense operations center adrienne hall said “ due elevated risk destructive cyber-attacks time made decision take action applying updates provides protection potential attacks characteristics similar wannacrypt alternative name wannacry ” researcher marcus hutchins accidentally discovered kill switch domain hardcoded malware registering domain name dns sinkhole stopped attack spreading worm ransomware encrypted computer files unable connect domain computers infected wannacry website registration unable help already infected systems severely slowed spread initial infection gave time defensive measures deployed worldwide particularly north america asia attacked extent elsewhere 14 may first variant wannacry appeared new second kill-switch registered matt suiche day followed second variant third last kill-switch 15 may registered check point threat intelligence analysts days later new version wannacry detected lacked kill switch altogether 19 may reported hackers trying use mirai botnet variant effect distributed attack wannacry kill-switch domain intention knocking offline 22 may hutchins protected domain switching cached version site capable dealing much higher traffic loads live site separately researchers university college london boston university reported paybreak system could defeat wannacry several families ransomware recovering keys used encrypt user data discovered windows encryption apis used wannacry may completely clear prime numbers used generate payload private keys memory making potentially possible retrieve required key yet overwritten cleared resident memory key kept memory wannacry process killed computer rebooted infected behaviour used french researcher develop tool known wannakey automates process windows xp systems approach iterated upon second tool known wanakiwi tested work windows 7 server 2008 r2 well within four days initial outbreak new infections slowed trickle due responses linguistic analysis ransom notes indicated authors likely fluent chinese proficient english versions notes languages probably human-written rest seemed machine-translated according analysis fbi cyber behavioral analysis center computer created ransomware language files hangul language fonts installed evidenced presence \fcharset129 rich text format tag metadata language files also indicated computers created ransomware set used korea google security researcher initially posted tweet referencing code similarities wannacry previous malware cybersecurity companies kaspersky lab symantec said code similarities previously used lazarus group believed carried cyberattack sony pictures 2014 bangladesh bank heist 2016—and linked north korea could also either simple re-use code another group attempt shift blame—as cyber false flag operation leaked internal nsa memo alleged also linked creation worm north korea brad smith president microsoft said believed north korea originator wannacry attack uk national cyber security centre reached conclusion 18 december 2017 united states government formally announced publicly considers north korea main culprit behind wannacry attack president trump homeland security advisor tom bossert wrote op-ed wall street journal charge saying make allegation lightly based evidence press conference following day bossert said evidence indicates kim jong-un given order launch malware attack bossert said canada new zealand japan agree united states assessment evidence links attack north korea united kingdom foreign commonwealth office says also stands behind united states assertion north korea however denied responsible cyberattack 6 september 2018 us department justice doj announced formal charges park jin-hyok involvement sony pictures hack 2014 doj contended park north korean hacker working part team experts north korean reconnaissance general bureau department justice asserted team also involved wannacry attack among activities ransomware campaign unprecedented scale according europol estimates around 200,000 computers infected across 150 countries according kaspersky lab four affected countries russia ukraine india taiwan one largest agencies struck attack national health service hospitals england scotland 70,000 devices – including computers mri scanners blood-storage refrigerators theatre equipment – may affected 12 may nhs services turn away non-critical emergencies ambulances diverted 2016 thousands computers 42 separate nhs trusts england reported still running windows xp 2018 report members parliament concluded 200 nhs hospitals organizations checked wake wannacry attack still failed cyber security checks nhs hospitals wales northern ireland unaffected attack nissan motor manufacturing uk tyne wear england halted production ransomware infected systems renault also stopped production several sites attempt stop spread ransomware spain telefónica fedex deutsche bahn hit along many countries companies worldwide attack impact said relatively low compared potential attacks type could much worse marcus hutchins discovered kill-switch built creators specifically targeted highly critical infrastructure like nuclear power plants dams railway systems according cyber-risk-modeling firm cyence economic losses cyber attack could reach us 4 billion groups estimating losses hundreds millions following alphabetical list organisations confirmed affected number experts highlighted nsa non-disclosure underlying vulnerability loss control eternalblue attack tool exploited edward snowden said nsa privately disclosed flaw used attack hospitals found lost attack may happened british cybersecurity expert graham cluley also sees culpability part u.s. intelligence services according others could done something ages ago get problem fixed n't also said despite obvious uses tools spy people interest duty protect countries citizens others also commented attack shows practice intelligence agencies stockpile exploits offensive purposes rather disclosing defensive purposes may problematic microsoft president chief legal officer brad smith wrote repeatedly exploits hands governments leaked public domain caused widespread damage equivalent scenario conventional weapons would u.s. military tomahawk missiles stolen russian president vladimir putin placed responsibility attack u.s. intelligence services created eternalblue 17 may 2017 united states bipartisan lawmakers introduced patch act aims exploits reviewed independent board balance need disclose vulnerabilities national security interests increasing transparency accountability maintain public trust process 15 june 2017 united states congress hold hearing attack two subpanels house science committee hear testimonies various individuals working government non-governmental sector us improve protection mechanisms systems similar attacks future cybersecurity researcher working loose collaboration uk national cyber security centre researched malware discovered kill switch later globally dispersed security researchers collaborated online develop open source tools allow decryption without payment circumstances snowden states nsa-enabled ransomware eats internet help comes researchers spy agencies asks case experts also used publicity around attack chance reiterate value importance good regular secure backups good cybersecurity including isolating critical systems using appropriate software latest security patches installed adam segal director digital cyberspace policy program council foreign relations stated patching updating systems broken basically private sector government agencies addition segal said governments apparent inability secure vulnerabilities opens lot questions backdoors access encryption government argues needs private sector security arne schönbohm president germany federal office information security bsi stated current attacks show vulnerable digital society wake-up call companies finally take security seriously effects attack also political implications united kingdom impact national health service quickly became political claims effects exacerbated government underfunding nhs particular nhs ceased paid custom support arrangement continue receiving support unsupported microsoft software used within organization including windows xp home secretary amber rudd refused say whether patient data backed shadow health secretary jon ashworth accused health secretary jeremy hunt refusing act critical note microsoft national cyber security centre ncsc national crime agency received two months previously others argued hardware software vendors often fail account future security flaws selling systems − due technical design market incentives − eventually wo n't able properly receive apply patches nhs denied still using xp claiming 4.7 devices within organization ran windows xp cost attack nhs estimated £92 million disruption services upgrades attack nhs digital refused finance estimated £1 billion meet cyber essentials plus standard information security certification organized uk ncsc saying would constitute value money invested £60 million planned spend £150 million next two years address key cyber security weaknesses suggested future attack magnitude may defined terrorism act parliament adds provision stating malicious use computer matter world located degrades seriously harms healthcare power life support critical infrastructure form terrorism may elicit proportional response possibly could added revision policing crime act 2017 late june hundreds computer users reported sent email someone multiple people claiming developers wannacry email threatened destroy victims data unless sent 0.1 btc bitcoin address hackers
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Computer security
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modelica modelica object-oriented declarative multi-domain modeling language component-oriented modeling complex systems e.g. systems containing mechanical electrical electronic hydraulic thermal control electric power process-oriented subcomponents free modelica language developed non-profit modelica association modelica association also develops free modelica standard library contains 1360 generic model components 1280 functions various domains version 3.2.1 modelica resembles object-oriented programming languages c++ java differs two important respects first modelica modeling language rather conventional programming language modelica classes compiled usual sense translated objects exercised simulation engine simulation engine specified language although certain required capabilities outlined second although classes may contain algorithmic components similar statements blocks programming languages primary content set equations contrast typical assignment statement left-hand side statement assigned value calculated expression right-hand side equation may expressions right- left-hand sides example equations describe assignment equality modelica terms equations pre-defined causality simulation engine may usually must manipulate equations symbolically determine order execution components equation inputs outputs modelica design effort initiated september 1996 hilding elmqvist goal develop object-oriented language modeling technical systems order reuse exchange dynamic system models standardized format modelica 1.0 based phd thesis hilding elmqvist experience modeling languages allan dymola nmf objectmath omola sidops+ smile hilding elmqvist key architect modelica many people contributed well see appendix e september 1997 version 1.0 modelica specification released basis prototype implementation within commercial dymola software system year 2000 non-profit modelica association formed manage continually evolving modelica language development free modelica standard library year usage modelica industrial applications started table presents timeline modelica specification history commercial front-ends modelica include amesim french company imagine sa part siemens plm software dymola swedish company dynasim ab part dassault systemes cymodelica american company cydesign labs esi group wolfram systemmodeler formerly mathmodelica swedish company wolfram mathcore ab part wolfram research simulationx german company esi iti gmbh maplesim canadian company maplesoft catia systems jmodelica.org extensible modelica-based open source platform optimization simulation analysis complex dynamic systems main objective project create industrially viable open source platform simulation optimization modelica models offering flexible platform serving virtual lab algorithm development research openmodelica open-source modelica-based modeling simulation environment intended industrial academic usage long-term development supported non-profit organization – open source modelica consortium osmc goal openmodelica effort create comprehensive open source modelica modeling compilation simulation environment based free software distributed binary source code form research teaching industrial usage free simulation environment scicos uses subset modelica component modeling support larger part modelica language currently development nevertheless still incompatibility diverging interpretation different tools concerning modelica language following code fragment shows simple example first order system formula_1 model firstorder equation end firstorder interesting things note example 'parameter qualifier indicates given variable time-invariant 'der operator represents symbolically time derivative variable also worth noting documentation strings associated declarations equations main application area modelica modeling physical systems basic structuring concepts shown hand simple examples electrical domain modelica four built-in types real integer boolean string typically user-defined types derived associate physical quantity unit nominal values attributes type voltage real quantity= electricalpotential unit= v type current real quantity= electricalcurrent unit= interaction component components defined physical ports called connectors e.g. electrical pin defined connector pin electrical pin end pin drawing connection lines ports meaning corresponding connector variables without flow prefix identical v corresponding connector variables flow prefix defined zero-sum equation sum corresponding flow variables zero motivation automatically fulfill relevant balance equations infinitesimally small connection point basic model component defined model contains equations describe relationship connector variables declarative form i.e. without specifying calculation order model capacitor equation end capacitor goal connected set model components leads set differential algebraic discrete equations number unknowns number equations identical modelica achieved requiring called balanced models full rules defining balanced models rather complex read however cases simple rule issued counts variables equations way simulation tools given variables equations must counted according following rule note standard input connectors realinput integerinput contribute count variables since new variables defined inside reason rule understood thinking capacitor defined pins contain flow variable i.e current check connected nothing corresponds set equation pin.i=0 pin must add equation flow variable obviously example extended cases kinds flow variables involved e.g forces torques etc. capacitor connected another balanced model one pins connection equation generated substitute two i=0 equations pins connected since connection equation corresponds two scalar equations connection operation leave balanced larger model constituted capacitor model connected capacitor model balanced since verification using openmodelica model gives fact another example containing input connectors physical connectors following component modelica standard library model signalvoltage equation end signalvoltage component signalvoltage balanced since checking openmodelica gives hierarchical model built-up basic models instantiating basic models providing suitable values model parameters connecting model connectors typical example following electrical circuit model circuit equation end circuit via language element annotation ... definitions added model influence simulation annotations used define graphical layout documentation version information basic set graphical annotations standardized ensure graphical appearance layout models different modelica tools freely available book modelica example contains many examples like along detailed explanations nearly language features modelica version 3.3 modelica designed domain neutral result used wide variety applications fluid systems example steam power generation hydraulics etc automotive applications especially powertrain mechanical systems example multi-body systems mechatronics etc. automotive sector many major automotive oems using modelica include ford general motors toyota bmw daimler modelica also increasingly used simulation thermo-fluid energy systems characteristics modelica acausal object-oriented domain neutral make well suited system-level simulation domain modelica well established
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Programming language topics
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windows go windows go feature windows 8 enterprise windows 8.1 enterprise windows 10 education windows 10 enterprise windows 10 pro limited education enterprise image allows boot run certain usb mass storage devices usb flash drives external hard disk drives certified microsoft compatible fully manageable corporate windows environment intended allow enterprise administrators provide users imaged version windows reflects corporate desktop creation windows go drives officially supported non-enterprise education windows 8.1 editions however enterprise education versions windows 10 supported information published describing various ways install windows go using version windows 8.x 10 bootable usb device windows 8 embedded versions windows windows embedded standard 7 supported booting usb storage devices april 2011 leak windows 8 build 7850 users noticed builds included program called portable workspace creator indicating intended create bootable usb drives windows 8 september 2011 microsoft officially announced windows go build conference distributed bootable 32 gb usb flash drives windows go pre-installed windows go several significant differences compared standard installation windows 8 non-removable storage hard disk drives solid-state drives windows go works usb 2.0 faster usb connections legacy bios uefi firmware usb drives used environment microsoft set specific requirements usb drive must meet order supported device june 2017 12 usb devices listed supported microsoft windows go using pc host hardware certified use either windows 7 windows 8 work well windows go although microsoft provide support feature windows rt macintosh computers possible boot windows go mac new companion device license microsoft software assurance employees use windows go software assurance licensed computer well home pc simon bisson writing zdnet called windows go one interesting features windows 8 noting even though using usb 2.0 port performance good noticeable lag calling useful way running windows 8 michael s. lasky writing laptopmag.com wrote departments want ensure employees safely access corporate network windows go usb drives incredibly convenient ability instantly remake windows pc secure personal computer worthwhile productive time-saver release windows 10 may 2019 update version 1903 microsoft announced windows go longer developed feature support os major feature updates therefore enable user stay current specific certified type performant usb media needed feature provide good user experience also longer produced oems
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Operating systems
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toa technologies toa technologies provides software service-based field service management software customer appointment scheduling solutions services enterprises worldwide headquartered beachwood ohio company develops markets sells etadirect web-based applications solution provides advanced tools companies small medium large mobile workforces automate optimize planning scheduling appointment booking well routing job allocation real-time management type field service event etadirect include applications forecasting capacity management routing real-time field management/dispatch advanced html 5-based mobility app field employees also includes apps collaboration location-based information customer communications etadirect powered patented algorithm continuously learns mobile employees ’ work patterns analyzes statistically uses pattern recognition accurately predict employee time arrival customer location length job/appointment take thereby providing enhanced accuracy planning customer experience management etadirect typically narrows wait window less 60 minutes using time-based predictions etadirect communicate consumers exact time field service employee arrive via voice/ivr email text/sms twitter communications channels reducing customer frustration wasted time inquiry calls service provider call centers software delivered businesses internet using software service/esaas model etadirect currently used seven top ten cable television companies north america including cox communications major broadband operators europe virgin media ono spain global communications companies telefonica global utility companies like e.on toa technologies founded yuval brisker irad carmi 2003 company privately held employs 550 employees worldwide headquartered beachwood ohio additional offices london united kingdom sao paulo brazil principal venture shareholders technology crossover ventures draper triangle ventures dfj network affiliate intel capital sutter hill ventures toa stands time arrival concept time central etadirect software solution set central algorithm measures time predicts performance based resource specific pattern recognition predictive analytics yields accurate time arrival estimates alternative managing service appointments according averages human resource capabilities availability december 2013 toa 85,000 users oracle corporation announced acquiring toa technologies july 31 2014 april 6 2010 toa issued u.s. patent 7,693,735 entitled dynamic schedule mediation predictive performance-pattern based mobile workforce management system proactive customer communications methodology october 2012 gartner recognized toa technologies leader magic quadrant field service management first time toa technologies named leader gartner magic quadrant field service management 2013 report gartner stated toa best-of-breed field service optimization vendor based solely cloud toa named one america promising companies 2013 forbes magazine july 2013 toa closed major round funding technology crossover ventures raising 66 million transform global field service management july 31 2014 oracle corporation announced buying toa technologies transaction closed mid-september 2014
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Distributed computing architecture
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international committee computational linguistics international committee computational linguistics iccl founded dr. david hays rand corporation 1965 promote biennial international conference computational linguistics since third conference stockholm known acronym coling swedish fictional character kolingen albert engström current president iccl professor jun-ichi tsujii university tokyo membership committee permanent
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Computational linguistics
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real time streaming protocol real time streaming protocol rtsp network control protocol designed use entertainment communications systems control streaming media servers protocol used establishing controlling media sessions end points clients media servers issue vhs-style commands play record pause facilitate real-time control media streaming server client video demand client server voice recording transmission streaming data task rtsp rtsp servers use real-time transport protocol rtp conjunction real-time control protocol rtcp media stream delivery however vendors implement proprietary transport protocols rtsp server software realnetworks example also used realnetworks proprietary real data transport rdt rtsp developed realnetworks netscape columbia university first draft submitted ietf 1996 standardized multiparty multimedia session control working group mmusic wg internet engineering task force ietf published rfc 2326 1998 rtsp 2.0 published rfc 7826 2016 replacement rtsp 1.0 rtsp 2.0 based rtsp 1.0 backwards compatible basic version negotiation mechanism similar ways http rtsp defines control sequences useful controlling multimedia playback http stateless rtsp state identifier used needed track concurrent sessions like http rtsp uses tcp maintain end-to-end connection rtsp control messages sent client server commands travel direction i.e server client presented basic rtsp requests typical http requests like options request also available default transport layer port number 554 tcp udp latter rarely used control requests rtsp using rtp rtcp allows implementation rate adaptation many cctv security cameras often called ip cameras support rtsp streaming especially onvif profiles g
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Internet protocols
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real-time transport protocol real-time transport protocol rtp network protocol delivering audio video ip networks rtp used communication entertainment systems involve streaming media telephony video teleconference applications including webrtc television services web-based push-to-talk features rtp typically runs user datagram protocol udp rtp used conjunction rtp control protocol rtcp rtp carries media streams e.g. audio video rtcp used monitor transmission statistics quality service qos aids synchronization multiple streams rtp one technical foundations voice ip context often used conjunction signaling protocol session initiation protocol sip establishes connections across network rtp developed audio-video transport working group internet engineering task force ietf first published 1996 superseded 2003 rtp designed end-to-end real-time transfer streaming media protocol provides facilities jitter compensation detection packet loss out-of-order delivery common especially udp transmissions ip network rtp allows data transfer multiple destinations ip multicast rtp regarded primary standard audio/video transport ip networks used associated profile payload format design rtp based architectural principle known application-layer framing protocol functions implemented application opposed operating system protocol stack real-time multimedia streaming applications require timely delivery information often tolerate packet loss achieve goal example loss packet audio application may result loss fraction second audio data made unnoticeable suitable error concealment algorithms transmission control protocol tcp although standardized rtp use normally used rtp applications tcp favors reliability timeliness instead majority rtp implementations built user datagram protocol udp transport protocols specifically designed multimedia sessions sctp dccp although widespread use rtp developed audio/video transport working group ietf standards organization rtp used conjunction protocols h.323 rtsp rtp specification describes two protocols rtp rtcp rtp used transfer multimedia data rtcp used periodically send control information qos parameters data transfer protocol rtp carries real-time data information provided protocol include timestamps synchronization sequence numbers packet loss reordering detection payload format indicates encoded format data control protocol rtcp used quality service qos feedback synchronization media streams bandwidth rtcp traffic compared rtp small typically around 5 rtp sessions typically initiated communicating peers using signaling protocol h.323 session initiation protocol sip rtsp jingle xmpp protocols may use session description protocol specify parameters sessions rtp session established multimedia stream audio video streams may use separate rtp sessions enabling receiver selectively receive components particular stream session consists destination ip address pair ports rtp rtcp specification recommends rtp port numbers chosen even associated rtcp port next higher odd number however single port chosen rtp rtcp applications multiplex protocols rtp rtcp typically use unprivileged udp ports 1024 65535 may also use transport protocols notably sctp dccp protocol design transport independent one design considerations rtp carry range multimedia formats allow new formats without revising rtp standard end information required specific application protocol included generic rtp header instead provided separate rtp profiles associated payload formats class application e.g. audio video rtp defines profile one associated payload formats complete specification rtp particular application usage requires profile payload format specifications profile defines codecs used encode payload data mapping payload format codes payload type pt field rtp header profile accompanied several payload format specifications describes transport particular encoded data audio payload formats include g.711 g.723 g.726 g.729 gsm qcelp mp3 dtmf video payload formats include h.261 h.263 h.264 h.265 mpeg-1/mpeg-2 mapping mpeg-4 audio/video streams rtp packets specified h.263 video payloads described examples rtp profiles include rtp packets created application layer handed transport layer delivery unit rtp media data created application begins rtp packet header rtp header minimum size 12 bytes header optional header extensions may present followed rtp payload format determined particular class application fields header follows functional network-based system includes protocols standards conjunction rtp protocols sip jingle rtsp h.225 h.245 used session initiation control termination standards h.264 mpeg h.263 used encode payload data specified applicable rtp profile rtp sender captures multimedia data encodes frames transmits rtp packets appropriate timestamps increasing timestamps sequence numbers sender sets payload type field accordance connection negotiation rtp profile use rtp receiver detects missing packets may reorder packets decodes media data packets according payload type presents stream user
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Internet protocols
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authorized program analysis report apar authorized program analysis report pronounced a-par rhymes far ibm designation document intended identify situations could result potential problems also serves request correction defect current releases ibm-supplied programs occasionally ibm software bug ascertained situation caused problems third-party hardware software user configuration errors ibm support staff suspect defect current release ibm program cause file formal report confirming existence issue addition confirming existence issue apars include information known workarounds information whether formal fix scheduled included future releases whether program temporary fix ptf planned ibm program facilitate documenting problem least 2 levels fix ptf permanent correction respect vrm version release modification level product applicable temporary fix sense problem correction temporarily available permanent fix later incorporated product base code thereby longer fix although associated ptf and/or apar numbers rule included source documentation associated ensuing base code update sidr xerox acronym covering apar ptf acronym referred system improvement difficulty report sir system improvement request terminology digital equipment corporation used much xerox used sidr
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Operating systems
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internet security association key management protocol isakmp internet security association key management protocol protocol defined rfc 2408 establishing security associations sa cryptographic keys internet environment isakmp provides framework authentication key exchange designed key exchange independent protocols internet key exchange kerberized internet negotiation keys provide authenticated keying material use isakmp example ike describes protocol using part oakley part skeme conjunction isakmp obtain authenticated keying material use isakmp security associations ah esp ietf ipsec doi isakmp defines procedures authenticating communicating peer creation management security associations key generation techniques threat mitigation e.g denial service replay attacks framework isakmp typically utilizes ike key exchange although methods implemented kerberized internet negotiation keys preliminary sa formed using protocol later fresh keying done isakmp defines procedures packet formats establish negotiate modify delete security associations sas contain information required execution various network security services ip layer services header authentication payload encapsulation transport application layer services self-protection negotiation traffic isakmp defines payloads exchanging key generation authentication data formats provide consistent framework transferring key authentication data independent key generation technique encryption algorithm authentication mechanism isakmp distinct key exchange protocols order cleanly separate details security association management key management details key exchange may many different key exchange protocols different security properties however common framework required agreeing format sa attributes negotiating modifying deleting sas isakmp serves common framework isakmp implemented transport protocol implementations must include send receive capability isakmp using udp port 500 openbsd first implemented isakmp 1998 via isakmpd 8 software ipsec services service microsoft windows handles functionality kame project implements isakmp linux open source bsds modern cisco routers implement isakmp vpn negotiation leaked nsa presentations released der spiegel indicate isakmp exploited unknown manner decrypt ipsec traffic ike researchers discovered logjam attack state breaking 1024-bit diffie–hellman group would break 66 vpn servers 18 top million https domains 26 ssh servers consistent researchers claim consistent leaks
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Internet protocols
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melvin currie melvin mel robert currie american mathematician cryptographer former chief cryptographic research design division national security agency recognitions include 2007 crypto-mathematics institute leadership award director distinguished service medal author 2018 popular mathematics book mathematics rhyme reason published jointly american mathematical society mathematical sciences research institute currie african-american born pittsburgh pennsylvania 1948 parents separated six currie spent rest childhood living mother younger brother maternal grandparents currie received ba yale university majored mathematics economics went graduate school university pittsburgh received phd 1983 advisor william fleissner title dissertation metric characterization irrationals via group operation
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Computer security
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expression-oriented programming language expression-oriented programming language programming language every nearly every construction expression thus yields value typical exceptions macro definitions preprocessor commands declarations expression-oriented languages often treat statements rather expressions expression-oriented languages introduce void return type yielded expressions merely cause side-effects algol 68 lisp examples expression-oriented languages pascal expression-oriented language functional programming languages expression-oriented critics including language designers blame expression-orientation entire class programming mistakes wherein programmer introduces assignment expression meant test equality example designers ada java worried type mistake restricted control expressions evaluate strictly boolean data type designers python similar worries took alternative strategy implementing assignment statement rather expression thus prohibiting assignment nesting inside statement expression
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Programming language topics
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translattice translattice software company based santa clara california geographically distributes databases applications enterprise cloud hybrid environments translattice offers newsql database application platform translattice founded 2007 officially launched 2010 company co-founders frank huerta ceo mike lyle executive vp engineering robert geiger previously worked together recourse technologies translattice based santa clara california august 2008 company received 9.5 million series funding dcm early stage capital venture funding company 2013 translattice acquired stormdb database-as-a-service startup stormdb clustered postgresql fork open sourced 2014 name postgres-xl translattice specializes distributed databases application platforms enterprise cloud systems company developed geographically-distributed computing-architecture allows single database run multiple nodes located anywhere translattice elastic database ted newsql database management system enables building highly available fault tolerant data fabric multiple nodes located anywhere world translattice database fully sql/acid-compliant ted operates cohesive single database translattice provided world first geographically-distributed relational database management system rdbms deploy multiple public-cloud-provider networks time well virtual machines physical hardware combination thereof
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Databases
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litespeed web server litespeed web server lsws proprietary web server software 4th popular web server estimated used 4.6 websites august 2019 lsws developed privately held litespeed technologies software uses configuration format apache http server compatible apache features lsws released 2003 august 2008 became 16th popular web server november 2016 litespeed market share grew 0.39 3.29 increasing position 10th 4th popular web server according netcraft 2017 team hong kong polytechnic university found one six popular web servers estimated team rwth aachen university running 9.2 http/2-enabled websites august 2019 lsws used 58.9 websites using quic litespeed web server lsws compatible commonly-used apache features including mod_rewrite .htaccess mod_security lsws load apache configuration files directly works drop-in replacement apache fully integrating popular control panels lsws replaces apache functions uses event driven approach handle requests litespeed technologies founded early 2002 team engineers led george wang july 1 2003 litespeed web server officially released full-featured web server 2007 litespeed web server became litespeed web server enterprise configured apache drop-in replacement year web server integrated cpanel directadmin plesk litespeed web server officially began supporting http/2 2015 version 5.0 also released lscache cache plugin wordpress esi version 5.0.10 2017 lsws released quic support
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Web technology
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zipit zipit shareware data compression utility archiving compressing files classic mac os mac os x platforms designed highly compatible pkzip ms-dos machines reading writing files well performing necessary line ending conversion macbinary encoding ensure files usable platforms advanced user interface offered number automation features including applescript support first released 1993 latest version zipit version 2.2.2 released late 2002 unique feature original mac file system use forks essentially two separate files finder maintained illusion single file files copied storage media automatically copied forks systems support feature risked problem transmitting one two forks producing unusable file led number archive formats combined two forks along extended metadata single file suitable hosting platforms original pkzip archive format include number features intended help support file systems like mac including things like longer filenames basic metadata however support forks therefore directly capable supporting mac files zip archives present major problem many use-cases mac archive utilities support features like stuffit compact pro early 1990s however zip format becoming almost universal number systems required data exchange notable among fidonet mailers offline mail readers like qwk format times mac users exchange simple files like text file pc user utilities like unzip maczip worked single files include mac-like interface suitable basic tasks zipit introduced address problem explicitly modeling program user interface compact pro lauded one easiest use archivers available zipit essentially replaced compact pro internal compression system pkzips producing program looked similar read wrote zip files instead cpt zipit also included number automation features notably support applescript allowed used programs like freddie qwk reader setting zterm allowed downloaded zip files automatically associated zipit making download-and-open simple task initial stable version 1.1.1 released march 1993 allowed multiple archives opened created one separate window version support hierarchical directories instead encoded files single-level archive downside would allow one file given name archive addressed 1.2.x versions settled final version 1.2.x series version 1.2.6 1994 2001 version 2.0 released version supported mac os x mac os 9 tests 1.1.1 zipit consistently outperformed compact pro stuffit terms compression 10 average speed stuffit making half speed fast compact pro
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Computer file systems
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firebird database server firebird open-source sql relational database management system runs linux microsoft windows macos several unix platforms database forked borland open source edition interbase 2000 since firebird 1.5 code largely rewritten within week interbase 6.0 source released borland 25 july 2000 firebird project created sourceforge firebird 1.0 released linux microsoft windows mac os x 11 march 2002 ports solaris freebsd 4 hp-ux following next two months work porting codebase c c++ began 2000 23 february 2004 firebird 1.5 released first stable release new codebase version 1.5 featured improved query optimizer sql-92 conditional expressions savepoints support explicit locking firebird 2.0 released 12 november 2006 adding support 64-bit architectures tables nested clauses programmable lock timeouts blocking transactions previous stable release version 2.1.6 added new features including procedural triggers recursive queries support merge statements firebird 2.5 introduced new features like improved multithreading regular expression syntax ability query remote databases recent stable version firebird 3.0 released 19 april 2016 focus performance security major re-architecture code allowed total support smp machines using superserver version google summer code 2013 work begun integrating firebird replacement hsqldb libreoffice april 2003 mozilla organization announced rename web browser phoenix firebird trademark dispute phoenix technologies decision caused concern within firebird database project due assumption users internet search engines would confused database web browser using name firebird mozilla developers issued statement making clear software package called mozilla firebird firebird statement also said mozilla firebird name project codename dispute resolved february 9 2004 mozilla changed name browser mozilla firefox thus ending conflict firebird inherited storage architecture interbase ensure acid properties transactions database engine keeps different versions record changed active users database transactions committed last version every changed record marked definitive transactions rolled back database engine keeps mark original record versions leaving untouched result firebird disk writes reduced compared databases use traditional transaction log architecture writing transactions prevent reading vice versa one sees version database tradeoff maintenance “ sweeping ” required time time clean old record versions free disk space multi-generational architecture ensures oltp dss/olap operations run simultaneously without delays caused locking mechanisms found products firebird makes indices database behave like well-tuned “ clustered indexes ” used architectures firebird index buckets ’ subject two-phase locking boolean “ ” “ ” operations performed intermediate bitmaps negligible cost eliminating need optimizer choose alternative indexes firebird database engine modules released open-source license initial developer public license idpl variant mozilla public license mpl version 1.1 require developer open products using firebird even custom-derivatives made source code developer chooses terms conditions honored idpl allows developer make proprietary closed-source applications use firebird based firebird native api used directly indirectly applications middleware connect firebird database implemented client library fbclient.dll windows systems libfbclient.so unix ones services api special function set accessing controlling service administration tasks user management backup/restore statistics gathering embedded sql technique simplifies development c/c++ cobol firebird applications using preprocessor called gpre allows embedding sql statements directly source code host language
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Databases
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hengzhi chip hengzhi chip 联想 恒智 安全芯片 microcontroller store secured information designed people republic china government manufactured china functionalities similar offered trusted platform module unlike tpm follow trusted computing group specifications lenovo selling pcs installed hengzhi security chips chip could development ibm ess embedded security subsystem chip public key smart card placed directly motherboard system management bus september 2006 public specifications chip available
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Computer security
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reduced instruction set computer reduced instruction set computer risc one whose instruction set architecture isa allows fewer cycles per instruction cpi complex instruction set computer cisc various suggestions made regarding precise definition risc general concept computer small set simple general instructions rather large set complex specialized instructions another common risc trait load/store architecture memory accessed specific instructions rather part instructions although number computers 1960s 1970s identified forerunners riscs modern concept dates 1980s particular two projects stanford university university california berkeley associated popularization concept stanford mips would go commercialized successful mips architecture berkeley risc gave name entire concept commercialized sparc another success era ibm effort eventually led ibm power instruction set architecture powerpc power isa projects matured wide variety similar designs flourished late 1980s especially early 1990s representing major force unix workstation market well embedded processors laser printers routers similar products many varieties risc designs include arc alpha am29000 arm atmel avr blackfin i860 i960 m88000 mips pa-risc power isa including powerpc risc-v superh sparc use arm architecture processors smartphones tablet computers ipad android devices provided wide user base risc-based systems risc processors also used supercomputers summit world fastest supercomputer ranked top500 project alan turing 1946 automatic computing engine ace design many characteristics risc architecture number systems going back 1960s credited first risc architecture partly based use load/store approach term risc coined david patterson berkeley risc project although somewhat similar concepts appeared cdc 6600 designed seymour cray 1964 used load/store architecture two addressing modes register+register register+immediate constant 74 operation codes basic clock cycle 10 times faster memory access time partly due optimized load/store architecture cdc 6600 jack dongarra says considered forerunner modern risc systems although number technical barriers needed overcome development modern risc system michael j. flynn views first risc system ibm 801 design begun 1975 john cocke completed 1980 801 eventually produced single-chip form ibm romp 1981 stood 'research opd office products division micro processor name implies cpu designed mini tasks also used ibm rt pc 1986 turned commercial failure 801 inspired several research projects including new ones ibm would eventually lead ibm power instruction set architecture public risc designs however results university research programs run funding darpa vlsi program vlsi program practically unknown today led huge number advances chip design fabrication even computer graphics berkeley risc project started 1980 direction david patterson carlo h. sequin berkeley risc based gaining performance use pipelining aggressive use technique known register windowing traditional cpu one small number registers program use register time cpu register windows huge number registers e.g 128 programs use small number e.g eight one time program limits eight registers per procedure make fast procedure calls call simply moves window eight set eight registers used procedure return moves window back berkeley risc project delivered risc-i processor 1982 consisting 44,420 transistors compared averages 100,000 newer cisc designs era risc-i 32 instructions yet completely outperformed single-chip design followed 40,760 transistor 39 instruction risc-ii 1983 ran three times fast risc-i mips project grew graduate course john l. hennessy stanford university 1981 resulted functioning system 1983 could run simple programs 1984 mips approach emphasized aggressive clock cycle use pipeline making sure could run full possible mips system followed mips-x 1984 hennessy colleagues formed mips computer systems commercial venture resulted new architecture also called mips r2000 microprocessor 1985 early 1980s significant uncertainties surrounded risc concept uncertain could commercial future mid-1980s concepts matured enough seen commercially viable 1986 hewlett packard started using early implementation pa-risc computers meantime berkeley risc effort become well known eventually became name entire concept 1987 sun microsystems began shipping systems sparc processor directly based berkeley risc-ii system us government committee innovations computing communications credits acceptance viability risc concept success sparc system success sparc renewed interest within ibm released new risc systems 1990 1995 risc processors foundation 15 billion server industry since 2010 new open source instruction set architecture isa risc-v development university california berkeley research purposes free alternative proprietary isas 2014 version 2 user space isa fixed isa designed extensible barebones core sufficient small embedded processor supercomputer cloud computing use standard chip designer defined extensions coprocessors tested silicon design rocket soc also available open source processor generator chisel language common misunderstanding phrase reduced instruction set computer mistaken idea instructions simply eliminated resulting smaller set instructions fact years risc instruction sets grown size today many larger set instructions many cisc cpus risc processors powerpc instruction sets large cisc ibm system/370 example conversely dec pdp-8—clearly cisc cpu many instructions involve multiple memory accesses—has 8 basic instructions extended instructions term reduced phrase intended describe fact amount work single instruction accomplishes reduced—at single data memory cycle—compared complex instructions cisc cpus may require dozens data memory cycles order execute single instruction particular risc processors typically separate instructions i/o data processing term load/store architecture sometimes preferred risc architectures fixed-length instructions commonly 32 bits simple encoding simplifies fetch decode issue logic considerably one drawback 32-bit instructions reduced code density adverse characteristic embedded computing workstation server markets risc architectures originally designed serve address problem several architectures arm power isa mips risc-v adapteva epiphany optional short feature-reduced instruction format instruction compression feature sh5 also follows pattern albeit evolved opposite direction added longer media instructions original 16-bit encoding given level general performance risc chip typically far fewer transistors dedicated core logic originally allowed designers increase size register set increase internal parallelism features typically found risc architectures risc designs also likely feature harvard memory model instruction stream data stream conceptually separated means modifying memory code held might effect instructions executed processor cpu separate instruction data cache least special synchronization instruction issued upside allows caches accessed simultaneously often improve performance many early risc designs also shared characteristic branch delay slot branch delay slot instruction space immediately following jump branch instruction space executed whether branch taken words effect branch delayed instruction keeps alu cpu busy extra time normally needed perform branch nowadays branch delay slot considered unfortunate side effect particular strategy implementing risc designs modern risc designs generally away powerpc recent versions sparc mips aspects attributed first risc- labeled designs around 1975 include observations memory-restricted compilers time often unable take advantage features intended facilitate manual assembly coding complex addressing modes take many cycles perform due required additional memory accesses argued functions would better performed sequences simpler instructions could yield implementations small enough leave room many registers reducing number slow memory accesses simple designs instructions uniform length similar structure arithmetic operations restricted cpu registers separate load store instructions access memory properties enable better balancing pipeline stages making risc pipelines significantly efficient allowing higher clock frequencies early days computer industry programming done assembly language machine code encouraged powerful easy-to-use instructions cpu designers therefore tried make instructions would much work feasible advent higher level languages computer architects also started create dedicated instructions directly implement certain central mechanisms languages another general goal provide every possible addressing mode every instruction known orthogonality ease compiler implementation arithmetic operations could therefore often results well operands directly memory addition register immediate attitude time hardware design mature compiler design also reason implement parts functionality hardware microcode rather memory constrained compiler generated code alone advent risc philosophy became retroactively known complex instruction set computing cisc cpus also relatively registers several reasons important force encouraging complexity limited main memories order kilobytes therefore advantageous code density—the density information held computer programs—to high leading features highly encoded variable length instructions data loading well calculation mentioned issues higher priority ease decoding instructions equally important reason main memories quite slow common type ferrite core memory using dense information packing one could reduce frequency cpu access slow resource modern computers face similar limiting factors main memories slow compared cpu fast cache memories employed overcome limited size may partly explain highly encoded instruction sets proven useful risc designs modern computers risc developed alternative known cisc years strategies implemented alternatives risc cisc examples long instruction word vliw minimal instruction set computer misc mid-1970s researchers particularly john cocke ibm similar projects elsewhere demonstrated majority combinations orthogonal addressing modes instructions used programs generated compilers available time proved difficult many cases write compiler limited ability take advantage features provided conventional cpus also discovered microcoded implementations certain architectures complex operations tended slower sequence simpler operations thing part effect fact many designs rushed little time optimize tune every instruction used often optimized sequence instructions could faster less-tuned instruction performing equivalent operation sequence one infamous example vax codice_1 instruction mentioned elsewhere core memory long since slower many cpu designs advent semiconductor memory reduced difference still apparent registers later caches would allow higher cpu operating frequencies additional registers would require sizeable chip board areas time 1975 could made available complexity cpu logic reduced yet another impetus risc designs came practical measurements real-world programs andrew tanenbaum summed many demonstrating processors often oversized immediates instance showed 98 constants program would fit 13 bits yet many cpu designs dedicated 16 32 bits store suggests reduce number memory accesses fixed length machine could store constants unused bits instruction word would immediately ready cpu needs much like immediate addressing conventional design required small opcodes order leave room reasonably sized constant 32-bit instruction word since many real-world programs spend time executing simple operations researchers decided focus making operations fast possible clock rate cpu limited time takes execute slowest sub-operation instruction decreasing cycle-time often accelerates execution instructions focus reduced instructions led resulting machine called reduced instruction set computer risc goal make instructions simple could easily pipelined order achieve single clock throughput high frequencies later noted one significant characteristics risc processors external memory accessible load store instruction instructions limited internal registers simplified many aspects processor design allowing instructions fixed-length simplifying pipelines isolating logic dealing delay completing memory access cache miss etc two instructions led risc designs referred load/store architectures one issue complex instructions difficult restart e.g following page fault cases restarting beginning work although wasteful many cases would give incorrect results therefore machine needs hidden state remember parts went remains done load/store machine program counter sufficient describe state machine main distinguishing feature risc instruction set optimized highly regular instruction pipeline flow features associated risc—branch delay slots separate instruction data caches load/store architecture large register set etc.—may seem random assortment unrelated features helpful maintaining regular pipeline flow completes instruction every clock cycle cpus specifically designed small set instructions – designs different classic risc designs given names minimal instruction set computer misc transport triggered architecture tta etc risc architectures traditionally successes desktop pc commodity server markets x86 based platforms remain dominant processor architecture however may change arm architecture based processors developed higher performance systems manufacturers including cavium amd qualcomm released arm architecture based server processors arm partnered cray 2017 produce arm architecture based supercomputer desktop microsoft announced part partnership qualcomm planned support pc version windows 10 qualcomm snapdragon-based devices 2017 devices support x86 based win32 software via x86 processor emulator outside desktop arena however arm architecture risc widespread use smartphones tablets many forms embedded device also case since pentium pro p6 intel using internal risc processor core processors early risc designs differed significantly contemporary cisc designs 2000 highest performing cpus risc line almost indistinguishable highest performing cpus cisc line risc architectures used across wide range platforms cellular telephones tablet computers world fastest supercomputers summit fastest top500 list beginning 21st century majority low end mobile systems relied risc architectures examples include
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Computer architecture
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attrition website attrition information security-related website updated least weekly all-volunteer staff 21 may 2001 attrition maintained largest mirror defaced cracked websites available world wide web defacement mirror since ceased updating site contains variety information including movie music reviews poetry security tips covering topics like forensics data theft security advisories republican communications aide todd shriber sacked job attempted hire attrition crack former university website 2001 attrition.org given cease desist order lawyers mastercard posting parodies priceless advertising campaign violated copyright law attrition formerly hosted several electronic mailing lists relating information security infosec news also maintained data loss database records data breaches companies
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Computer security
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intrusion detection system evasion techniques intrusion detection system evasion techniques modifications made attacks order prevent detection intrusion detection system ids almost published evasion techniques modify network attacks 1998 paper insertion evasion denial service eluding network intrusion detection popularized ids evasion discussed evasion techniques areas correct interpretation ambiguous depending targeted computer system 'fragroute 'fragrouter programs implement evasion techniques discussed paper many web vulnerability scanners 'nikto 'whisker 'sandcat also incorporate ids evasion techniques idss modified detect even reverse basic evasion techniques ids evasion countering ids evasion still active fields ids evaded obfuscating encoding attack payload way target computer reverse ids way attacker exploit end host without alerting ids application layer protocols like http allow multiple encodings data interpreted value example string cgi-bin url encoded 63 67 69 2d 62 69 6e i.e. hexadecimal web server view string act accordingly ids must aware possible encodings end hosts accept order match network traffic known-malicious signatures attacks encrypted protocols https read ids unless ids copy private key used server encrypt communication ids wo n't able match encrypted traffic signatures n't account signature-based ids often look common attack patterns match malicious traffic signatures detect buffer overflow attacks ids might look evidence nop slides used weaken protection address space layout randomization obfuscate attacks attackers use polymorphic shellcode create unique attack patterns technique typically involves encoding payload fashion e.g. xor-ing byte 0x95 placing decoder front payload sending target executes code runs decoder rewrites payload original form target executes polymorphic attacks n't single detectable signature making difficult signature-based ids even anomaly-based ids detect shikata ga nai helped popular polymorphic encoder metasploit framework used convert malicious shellcode difficult-to-detect polymorphic shellcode using xor additive feedback attackers evade ids crafting packets way end host interprets attack payload correctly ids either interprets attack incorrectly determines traffic benign quickly one basic technique split attack payload multiple small packets ids must reassemble packet stream detect attack simple way splitting packets fragmenting adversary also simply craft packets small payloads 'whisker evasion tool calls crafting packets small payloads 'session splicing small packets evade ids reassembles packet streams however small packets modified order complicate reassembly detection one evasion technique pause sending parts attack hoping ids time target computer second evasion technique send packets order confusing simple packet re-assemblers target computer another evasion technique craft series packets tcp sequence numbers configured overlap example first packet include 80 bytes payload second packet sequence number 76 bytes start first packet target computer reassembles tcp stream must decide handle four overlapping bytes operating systems take older data take newer data ids n't reassemble tcp way target manipulated either missing portion attack payload seeing benign data inserted malicious payload breaking attack signature technique also used ip fragmentation similar manner ids evasion techniques involve deliberately manipulating tcp ip protocols way target computer handle differently ids example tcp urgent pointer handled differently different operating systems ids n't handle protocol violations manner consistent end hosts vulnerable insertion evasion techniques similar mentioned earlier attacks spread across long period time large number source ips nmap slow scan difficult pick background benign traffic online password cracker tests one password user every day look nearly identical normal user mistyped password due fact passive ids inherently fail-open opposed fail-closed launching denial-of-service attack ids network feasible method circumventing protection adversary accomplish exploiting bug ids consuming computational resources ids deliberately triggering large number alerts disguise actual attack packets captured ids stored kernel buffer cpu ready process cpu high load ca n't process packets quickly enough buffer fills new possibly malicious packets dropped buffer full attacker exhaust ids cpu resources number ways example signature-based intrusion detection systems use pattern matching algorithms match incoming packets signatures known attacks naturally signatures computational expensive match others exploiting fact attacker send specially-crafted network traffic force ids use maximum amount cpu time possible run pattern matching algorithm traffic algorithmic complexity attack overwhelm ids relatively small amount bandwidth ids also monitors encrypted traffic spend large portion cpu resources decrypting incoming data order match certain signatures ids required keep state related connections monitoring example ids must maintain tcp control blocks tcbs chunks memory track information sequence numbers window sizes connection states established related closed etc tcp connection monitored ids ids random-access memory ram consumed forced utilized virtual memory hard disk much slower ram leading performance problems dropped packets similar effects cpu exhaustion ids n't garbage collect tcbs correctly efficiently attacker exhaust ids memory starting large number tcp connections quickly similar attacks made fragmenting large number packets larger number smaller packets send large number out-of-order tcp segments alerts generated ids acted upon order value attacker reduce availability ids overwhelming human operator inordinate number alerts sending large amounts malicious traffic intended generate alerts ids attacker perform actual attack using alert noise cover tools 'stick 'snot designed purpose generate large number ids alerts sending attack signatures across network trigger alerts ids maintain application protocol context
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Computer security
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extended validation certificate extended validation certificate ev certificate conforming x.509 proves legal entity owner signed certificate authority key issue ev certificates ev certificates used manner x.509 certificates including securing web communications https signing software documents ev certificates different domain-validated certificates organization-validation certificates issued subset certificate authorities cas require verification requesting entity legal identity certificate issuance august 2019 google chrome mozilla firefox apple safari web browsers show verified legal identity user interface either instead domain name plan remove distinction near future mobile browsers typically show difference ev certified websites desktop behaviour phased recent versions popular browsers example safari browser apple macos mojave ten popular websites online none use ev certificates trend away usage software verified legal identity displayed user operating system e.g. microsoft windows proceeding installation extended validation certificates stored file format specified typically use encryption organization-validated certificates domain-validated certificates compatible server user agent software criteria issuing ev certificates defined guidelines extended validation promulgated ca/browser forum voluntary organization whose members include leading cas vendors internet software well representatives legal audit professions issue extended validation certificate ca requires verification requesting entity identity operational status control domain name hosting server 2005 melih abdulhayoglu ceo comodo group convened first meeting organization became ca/browser forum hoping improve standards issuing ssl/tls certificates june 12 2007 ca/browser forum officially ratified first version extended validation ev ssl guidelines took effect immediately formal approval successfully brought close two years effort provided infrastructure trusted web site identity internet april 2008 forum announced version 1.1 guidelines building practical experience member cas relying-party application software suppliers gained months since first version approved use major browsers created special user interface indicators pages loaded via https secured ev certificate soon creation standard includes microsoft edge 12 google chrome 1.0 internet explorer 7.0 firefox 3 safari 3.2 opera 9.5 furthermore mobile browsers including safari ios windows phone firefox android chrome android ios added ui indicators usually browsers ev support display validated identity—usually combination organization name jurisdiction—contained ev certificate 'subject field implementations enhanced display includes clicking lock symbol user obtain information certificate including name certificate authority ca issued ev certificate august 2019 google chrome 76 firefox 70 browsers plan remove ui indicators ev certificates important motivation using digital certificates ssl/tls add trust online transactions requiring website operators undergo vetting certificate authority ca order get certificate however commercial pressures led cas introduce domain-validated certificates domain-validated certificates existed validation standards generally require proof domain control particular domain-validated certificates assert given legal entity relationship domain although domain may resemble particular legal entity past browsers user interfaces clearly differentiate low-validation certificates undergone rigorous vetting since successful ssl/tls connection would cause green padlock icon appear browsers users likely aware whether website owner validated result fraudsters including phishing websites could use tls add perceived credibility websites users modern browsers always check identity certificate owners examining details issued certificate always indicates certificate owner information name organization location ev certificates validated baseline requirements extended validation requirements place additional requirements authorities vet companies include manual checks domain names requested applicant checks official government sources checks independent information sources phone calls company confirm position applicant certificate accepted government-registered serial number business well physical address stored ev certificate establishing stricter issuing criteria requiring consistent application criteria participating cas ev certificates intended restore confidence among users website operator legally established business organization verifiable identity said still concern lack accountability led loss public confidence domain-validated certificates lead lax certification practices erode value ev certificates well cas pass independent qualified audit review may offer ev cas globally must follow detailed issuance requirements aim exception extended validation certificates .onion domains otherwise possible get wildcard extended validation certificate – instead fully qualified domain names must included certificate inspected certificate authority ev certificates standard x.509 digital certificates primary way identify ev certificate referencing certificate policies extension field issuer uses different object identifier oid field identify ev certificates oid documented issuer certification practice statement root certificate authorities general browsers may recognize issuers ev https certificates contain subject x.509 oids codice_1 codice_2 codice_3 codice_4 codice_5 codice_6 pointing id relevant secretary state us government business registrar outside us well ca-specific policy identifier ev-aware software web browser recognize criteria issuing extended validation certificates require issuing certificate authorities immediately support online certificate status protocol revocation checking however requirement timely response revocation checks browser prompted certificate authorities previously done implement ocsp support section 26-a issuing criteria requires cas support ocsp checking certificates issued dec. 31 2010 legal entity names unique therefore attacker wants impersonate entity might incorporate different business name e.g. different state country obtain valid certificate use certificate impersonate original site one demonstration researcher incorporated business called stripe inc. kentucky showed browsers display similarly display certificate payment processor stripe inc. incorporated delaware researcher claimed demonstration setup took hour time us 100 legal costs us 77 certificate also noted enough mouse clicks user may able view city state entity incorporated neither helpful typical user likely blindly trust bright green indicator since ev certificates promoted reported mark trustworthy website small business owners voiced concerns ev certificates give undue advantage large businesses published drafts ev guidelines excluded unincorporated business entities early media reports focused issue version 1.0 ev guidelines revised embrace unincorporated associations long registered recognized agency greatly expanding number organizations qualified extended validation certificate 2006 researchers stanford university microsoft research conducted usability study ev display internet explorer 7 paper concluded participants received training browser security features notice extended validation indicator outperform control group whereas participants asked read internet explorer help file likely classify real fake sites legitimate proponents ev certificates claim help phishing attacks security expert peter gutmann states new class certificates restore ca profits eroded due race bottom occurred among issuers industry gutmann calls phenomenon pki-me-harder introduction … so-called high-assurance extended validation ev certificates allow cas charge standard ones simply case rounding twice usual number suspects—presumably somebody ’ going impressed effect phishing minimal since fixing problem phishers exploiting indeed cynics would say exactly problem certificates cas supposed solve first place “ high-assurance ” certificates way charging second time existing service years ago certificates still cost several hundred dollars shifting baseline certificate prices quality moved point obtained 9.95 even nothing big commercial cas reinvent defining new standard convincing market go back prices paid good old days deja-vu-all-over-again approach seen examining verisign ’ certificate practice statement cps document governs certificate issuance security requirements ev-certificate 2008 cps except minor differences legalese used express practically identical requirements class 3 certificates listed verisign ’ version 1.0 cps 1996 ev certificates simply roll back clock approach already failed first time tried 1996 resetting shifting baseline charging 1996 prices side-effect even proposals kind sliding-window approach certificate value inevitable race bottom cheapens effective value established classes certificates ’ regarded less less effective software uses them…
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Computer security
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evercookie evercookie javascript-based application created samy kamkar produces zombie cookies web browser intentionally difficult delete 2013 top-secret nsa document leaked edward snowden citing evercookie method tracking tor users traditional http cookie relatively small amount textual data stored user browser cookies used save preferences login session information however also employed track users marketing purposes due concerns privacy major browsers include mechanisms deleting and/or refusing accept cookies websites adobe systems claimed size restrictions likelihood eventual deletion simple textual nature traditional cookies motivated add local shared object lso mechanism adobe flash player adobe published mechanism deleting lso cookies store 100 kb data per website default met criticism security privacy experts since version 4 firefox treated lso cookies way traditional http cookies deleted together samy kamkar released v0.4 beta evercookie september 13 2010 open source according project website evercookie merely difficult delete actively resists deletion copying different forms user machine resurrecting notices copies missing expired specifically creating new cookie evercookie uses following storage mechanisms available developer looking add following features
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Computer security
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docuware docuware provider solutions document management workflow automation also referred enterprise content management ecm recently content services company headquartered germany united states docuware also name flagship product offered company besides offered cloud-based software service saas also available feature parity installation on-premises software available 16 languages docuware distributed via global network 500 authorized docuware partners adp well directly key accounts january 2017 docuware used 16,000 customers 70 countries october 27 1988 docunet gmbh founded germering germany near munich president jürgen biffar since 1990 mr biffar managing company colleague thomas schneck currently president sales docunet ag renamed docuware ag august 2000 since 1999 docuware outsourced parts development sofia bulgaria 2016 nemetschek ood 42 employees working docuware product docuware gmbh holds 20 percent stake nemetschek ood • docuware corporation new windsor founded january 1 2001 • docuware ltd nottinghamshire founded april 1 2005 • docuware sarl paris founded september 1 2008 • docuware s.l barcelona founded july 1 2009 april 2012 investment agreement signed company morgan stanley expansion capital lp morgan stanley investment management private equity fund aim promoting accelerating global growth docuware legal form ag public holding company changed gmbh limited liability corporation company acquired u.s.-based westbrook technologies inc. developer fortis ecm software august 2013 2014 westbrook technologies inc. merged docuware corporation beginning 2016 docuware appointed dr michael berger chief technology officer cto dr berger joined company 2008 vice president research development 1988 – development dacs-board dacs document archiving communication system 1990 – dacs office first software solution running windows 3.0 store search display print documents windows 3.0 released may 22 1990 1993 – docuware 3.0 customizable file cabinets structure pre-set sending documents docuware 1998 – docuware 4.0 first 32-bit version 2006 – docuware 5.0 new development based .net technology 2008 – docuware web client web-based document management 2009 – docuware saas first saas via private cloud 2012 – docuware online first saas via public cloud 2014 – docuware online renamed docuware cloud ported microsoft azure platform iso 9001 soc 2 idw ers fait 3 hipaa-compliant keypoint intelligence buyers lab bli 2018 outstanding content workflow management platform buyers laboratory inc. bli 2014 5-star rated product program version 6 online buyers laboratory inc. bli 2013 5-star rated product program version 6 wins summer pick award outstanding document management solution
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Distributed computing architecture
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relational model relational model rm database management approach managing data using structure language consistent first-order predicate logic first described 1969 english computer scientist edgar f. codd data represented terms tuples grouped relations database organized terms relational model relational database purpose relational model provide declarative method specifying data queries users directly state information database contains information want let database management system software take care describing data structures storing data retrieval procedures answering queries relational databases use sql data definition query language systems implement regarded engineering approximation relational model table sql database schema corresponds predicate variable contents table relation key constraints constraints sql queries correspond predicates however sql databases deviate relational model many details codd fiercely argued deviations compromise original principles relational model central idea describe database collection predicates finite set predicate variables describing constraints possible values combinations values content database given time finite logical model database i.e set relations one per predicate variable predicates satisfied request information database database query also predicate models hierarchical model network model systems using older architectures still use today data centers high data volume needs existing systems complex abstract would cost-prohibitive migrate systems employing relational model also note newer object-oriented databases several attempts produce true implementation relational database model originally defined codd explained date darwen others none popular successes far rel one recent attempts relational model first database model described formal mathematical terms hierarchical network databases existed relational databases specifications relatively informal relational model defined many attempts compare contrast different models led emergence rigorous descriptions earlier models though procedural nature data manipulation interfaces hierarchical network databases limited scope formalization relational model invented edgar f. codd general model data subsequently promoted chris date hugh darwen among others third manifesto first published 1995 date darwen attempt show relational model allegedly accommodate certain desired object-oriented features codd years publication 1970 model proposed three-valued logic true false missing/null version deal missing information relational model database management version 2 1990 went step four-valued logic true false missing applicable missing inapplicable version never implemented presumably attending complexity sql null construct intended part three-valued logic system fell short due logical errors standard implementations fundamental assumption relational model data represented mathematical n -ary relations n -ary relation subset cartesian product n domains mathematical model reasoning data done two-valued predicate logic meaning two possible evaluations proposition either true false particular third value unknown applicable either often associated concept null data operated upon means relational calculus relational algebra equivalent expressive power relational model data permits database designer create consistent logical representation information consistency achieved including declared constraints database design usually referred logical schema theory includes process database normalization whereby design certain desirable properties selected set logically equivalent alternatives access plans implementation operation details handled dbms engine reflected logical model contrasts common practice sql dbmss performance tuning often requires changes logical model basic relational building block domain data type usually abbreviated nowadays type tuple ordered set attribute values attribute ordered pair attribute name type name attribute value specific valid value type attribute either scalar value complex type relation consists heading body heading set attributes body n -ary relation set n -tuples heading relation also heading tuples relation defined set n -tuples mathematics relational database model set unordered collection unique non-duplicated items although dbmss impose order data mathematics tuple order allows duplication e.f. codd originally defined tuples using mathematical definition later one e.f. codd great insights using attribute names instead ordering would much convenient general computer language based relations insight still used today though concept changed name tuple immediate important consequence distinguishing feature relational model cartesian product becomes commutative table accepted visual representation relation tuple similar concept row relvar named variable specific relation type times relation type assigned though relation may contain zero tuples basic principle relational model information principle information represented data values relations accordance principle relational database set relvars result every query presented relation consistency relational database enforced rules built applications use rather constraints declared part logical schema enforced dbms applications general constraints expressed using relational comparison operators one subset ⊆ theoretically sufficient practice several useful shorthands expected available important candidate key really superkey foreign key constraints fully appreciate relational model data essential understand intended interpretation relation body relation sometimes called extension interpreted representation extension predicate set true propositions formed replacing free variable predicate name term designates something one-to-one correspondence free variables predicate attribute names relation heading tuple relation body provides attribute values instantiate predicate substituting free variables result proposition deemed account appearance tuple relation body true contrariwise every tuple whose heading conforms relation appear body deemed false assumption known closed world assumption often violated practical databases absence tuple might mean truth corresponding proposition unknown example absence tuple 'john 'spanish table language skills necessarily taken evidence john speak spanish formal exposition ideas see section set-theoretic formulation data type used typical relational database might set integers set character strings set dates two boolean values true false corresponding type names types might strings int char date boolean etc important understand though relational theory dictate types supported indeed nowadays provisions expected available user-defined types addition built-in ones provided system attribute term used theory commonly referred column similarly table commonly used place theoretical term relation though sql term means synonymous relation table data structure specified list column definitions specifies unique column name type values permitted column attribute value entry specific column row john doe 35 tuple basically thing row except sql dbms column values row ordered tuples ordered instead attribute value identified solely attribute name never ordinal position within tuple attribute name might name age relation table structure definition set column definitions along data appearing structure structure definition heading data appearing body set rows database relvar relation variable commonly known base table heading assigned value time specified table declaration body recently assigned invoking update operator typically insert update delete heading body table resulting evaluation query determined definitions operators used expression query note sql heading always set column definitions described possible column name also two columns name also body always set rows sql possible row appear body sql initially pushed standard language relational databases deviates relational model several places current iso sql standard n't mention relational model use relational terms concepts however possible create database conforming relational model using sql one use certain sql features following deviations relational model noted sql note database servers implement entire sql standard particular allow deviations whereas null ubiquitous example allowing duplicate column names within table anonymous columns uncommon users programs request data relational database sending query written special language usually dialect sql although sql originally intended end-users much common sql queries embedded software provides easier user interface many web sites wikipedia perform sql queries generating pages response query database returns result set list rows containing answers simplest query return rows table often rows filtered way return answer wanted often data multiple tables combined one join conceptually done taking possible combinations rows cartesian product filtering everything except answer practice relational database management systems rewrite optimize queries perform faster using variety techniques number relational operations addition join include project process eliminating columns restrict process eliminating rows union way combining two tables similar structures difference lists rows one table found intersect lists rows found tables product mentioned combines row one table row depending sources consult number operators – many defined terms listed include semi-join outer operators outer join outer union various forms division operators rename columns summarizing aggregating operators permit relation values attributes relation-valued attribute operators group ungroup select statement sql serves handle except group ungroup operators flexibility relational databases allows programmers write queries anticipated database designers result relational databases used multiple applications ways original designers foresee especially important databases might used long time perhaps several decades made idea implementation relational databases popular businesses relations classified based upon types anomalies 're vulnerable database first normal form vulnerable types anomalies database domain/key normal form modification anomalies normal forms hierarchical nature lowest level first normal form database meet requirements higher level normal forms without first met requirements lesser normal forms idealized simple example description relvars relation variables attributes design six relvars customer order order line invoice invoice line product bold underlined attributes candidate keys non-bold underlined attributes foreign keys usually one candidate key chosen called primary key used preference candidate keys called alternate keys candidate key unique identifier enforcing tuple duplicated would make relation something else namely bag violating basic definition set foreign keys superkeys includes candidate keys composite composed several attributes tabular depiction relation example customer relvar relation thought value attributed relvar attempted insert new customer id 1234567890 would violate design relvar since customer id primary key already customer 1234567890 dbms must reject transaction would render database inconsistent violation integrity constraint foreign keys integrity constraints enforcing value attribute set drawn candidate key another relation example order relation attribute customer id foreign key join operation draws information several relations joining relvars example could query database customers orders invoices wanted tuples specific customer would specify using restriction condition wanted retrieve orders customer 1234567890 could query database return every row order table customer id 1234567890 join order table order line table based order flaw database design invoice relvar contains order attribute tuple invoice relvar one order implies precisely one order invoice reality invoice created many orders indeed particular order additionally order relvar contains invoice attribute implying order corresponding invoice always true real world order sometimes paid several invoices sometimes paid without invoice words many invoices per order many orders per invoice many-to-many relationship order invoice also called non-specific relationship represent relationship database new relvar introduced whose role specify correspondence orders invoices order relvar one-to-many relationship orderinvoice table invoice relvar want retrieve every invoice particular order query orders order order relation equals order orderinvoice invoice orderinvoice equals invoice invoice basic notions relational model relation names attribute names represent strings person name usually use variables formula_1 formula_2 range another basic notion set atomic values contains values numbers strings first definition concerns notion tuple formalizes notion row record table next definition defines relation formalizes contents table defined relational model relation closely corresponds usually called extension predicate first-order logic except identify places predicate attribute names usually relational model database schema said consist set relation names headers associated names constraints hold every instance database schema one simplest important types relation constraints key constraint tells us every instance certain relational schema tuples identified values certain attributes superkey set column headers values columns concatenated unique across rows formally candidate key superkey subdivided form another superkey functional dependency property value tuple may derived another value tuple input set fds contain subsets header h
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Databases
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cyber storm iii cyber storm iii international cyber security exercise sponsored united states department homeland security 2010 week-long exercise centered washington dc concluded oct. 1st
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Computer security
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space communications protocol specifications space communications protocol specifications scps set extensions existing protocols new protocols developed consultative committee space data systems ccsds improve performance internet protocols space environments scps protocol stack consists scps protocol seen use commercially scps-tp usually deployed performance enhancing proxy pep improve tcp performance satellite links
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Internet protocols
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socket ft3 amd socket ft3 bga-769 targets mobile devices designed apus codenamed kabini temash beema mullins socket ft3b kabini temash -branded products combine jaguar islands gcn uvd 3 vce 2.0 video acceleration amd eyefinity-based multi-monitor support maximum two monitors beema mullins -branded products puma amd radeon rx 200 series gcn uvd 3 vce 2.0 video acceleration amd eyefinity-based multi-monitor support maximum two monitors desktop counterpart socket am1
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Computer architecture
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demandware demandware software technology company headquartered burlington massachusetts provides cloud-based unified e-commerce platform mobile ai personalization order management capabilities related services b2c b2b retailers brand manufacturers around world founded 2004 demandware acquired salesforce 2016 2.8b.. company subsequently renamed salesforce commerce cloud demandware founded 2004 stephan schambach provide hosted service would enable companies develop manage easy-to-use customizable e-commerce websites rather building site scratch service launched first quarter 2005 schambach previously founded early e-commerce company intershop 1992 seed money demandware provided venture capital firms general catalyst partners north bridge venture partners march 15 2012 demandware began trading new york stock exchange raising 88 million initial public offering 16 per share following ipo shares 50 ipo price next morning november 2013 demandware announced underwritten registered public offering demandware headquartered burlington massachusetts company also offices salt lake city utah deerfield beach florida united kingdom france denmark germany netherlands australia hong kong china japan
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Distributed computing architecture
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vectored interrupt computer science vectored interrupt processing technique interrupting device directs processor appropriate interrupt service routine contrast polled interrupt system single interrupt service routine must determine source interrupt checking potential interrupt sources slow relatively laborious process vectored interrupts achieved assigning interrupting device unique code typically four eight bits length device interrupts sends unique code data bus processor telling processor interrupt service routine execute
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Computer architecture
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numina application framework numina application framework product numina solutions llc provides single sign-on capabilities application framework building applications features numina application framework include three main components numina application framework
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Computer security
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ryan lackey ryan donald lackey born march 17 1979 entrepreneur computer security professional co-founder havenco world first data also speaks numerous conferences trade shows including def con rsa data security conference various topics computer security field appeared cover wired magazine numerous television radio print articles havenco sealand lackey operated blueiraq vsat communications company serving dod domestic markets iraq afghanistan us conflicts lackey born west chester pennsylvania also lived throughout us europe anguilla sealand dubai iraq teenager briefly involved globewide network academy lackey attended mit majored course 18 mathematics student mit later dropped due financial constraints lackey became interested electronic cash distributed systems originally massively multiplayer online gaming interest led attending several conferences financial cryptography 98 various mit presentations participating mailing lists cypherpunks dbs eventually implementing patented chaumian digital cash underground library hinde ian goldberg named hinde ten berge dutch cypherpunk also present fc98 part contributed cypherpunks movement one longest anonymous remailer operators 1999 lackey lived san francisco bay area period anguilla moving unrecognized state sealand coast united kingdom establishing havenco december 2002 left havenco following dispute company directors sealand royal family eventually blueiraq business model became economically unfeasible due escalation anti-western violence primarily form improvised explosive devices troop draw downs blueiraq sought venture capital transform large general consumer cellular telephone company however 2008 financial crisis instability iraq afghanistan made fund raising impossible lackey returned us located san francisco worked number start-up companies applying combinator accepted combinator summer 2011 round lackey founded cryptoseal vpn service start-up small group people well known computer security community secured funding ron conway well known venture capital fund june 2014 cryptoseal acquired cloudflare br
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Computer security
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motorola x8 mobile computing system motorola x8 mobile computing system chipset motorola android-based smartphones based qualcomm snapdragon system chip s4 pro cpu s4 pro arm-compatible dual-core krait gpu chip 4-core adreno 320 several low-power dsp chips added motorola s4 pro chipset process audio inputs sensors
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Computer architecture
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speakable items speakable items part speech recognition feature classic mac os macos operating systems allows user control computer natural speech without train computer beforehand commands must present speakable items folder though created something simple shortcut applescript keyboard command automator workflows speakable items first introduced part apple speech recognition software plaintalk 1993 originally available quadra av models later integrated system 7.1.2 release macintosh system software release mac os x v10.4 featured 12 list features os x mountain lion speakable items relocated accessibility panel system preferences mac os x v10.4 added automator workflows also used speakable items workflow saved application put speakable items folder becomes available speech recognition software words computer recognize execute command name saved automator application words might misspelt computer know proper pronunciation example computer best recognizes les misérables lay mizzer ob automator made comply applescript applications third party non applescript applications limewire final cut studio apps work speakable items unless configure commands define keyboard command 'll select application making keyboard command speakable items useful well innovative recognition gets hard distorted times
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Operating systems
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crunchbang linux crunchbang linux abbreviated linux distribution derived debian philip newborough commonly known username corenominal crunchbang designed use comparatively system resources instead desktop environment used customized implementation openbox window manager many preinstalled applications used gtk+ widget toolkit crunchbang software repository drew vast majority packages debian repositories philip newborough announced 6 february 2015 stopped developing crunchbang users would benefit using vanilla debian linux distributions arisen place effort continue environment among significant bunsenlabs crunchbang++ crunchbang linux provided openbox version i686 i486 amd64 architectures october 2010 also lite version fewer installed applications lite version effectively discontinued distribution based – ubuntu 9.04 – reached end-of-life crunchbang prepared switch different base system crunchbang 10 made available february 2011 first version based debian final version crunchbang 11 made available 6 may 2013 crunchbang linux release given version number well code name using name muppet show character first letter code name first letter upstream debian release previously debian squeeze crunchbang statler currently debian wheezy crunchbang waldorf may 2013 jim lynch desktoplinuxreviews.com reviewed crunchbang 11 newborough announced february 2015 abandoning development crunchbang linux feeling longer served purpose users agree number proceeded develop successor distributions bunsenlabs crunchbang++ ++ crunchbang-monara bunsenlabs linux community-organized successor crunchbang based debian 9 stretch stable release 17 30 september 2015 crunchbang domain began redirecting bunsenlabs crunchbang plusplus ++ developed response newborough announcement end crunchbang based debian jessie release 8.1 distribution release 1.0 announced 29 april 2015 latest version based debian 10.0 released 8 july 2019 crunchbang-monara another successor crunchbang based debian 8 stable release
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Operating systems
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blackberry playbook blackberry playbook mini tablet computer developed blackberry made quanta computer original design manufacturer odm first released sale april 19 2011 canada united states playbook first device run blackberry tablet os based qnx neutrino runs apps developed using adobe air later announced blackberry tablet os would merged existing blackberry os produce new operating system blackberry 10 would used universally across blackberry product line second major revision blackberry playbook os released february 2012 playbook also supports android os applications allowing sold installed blackberry app world store early reviews mixed saying although hardware good several features missing shipments totaled approximately 500,000 units first quarter sales 200,000 following quarter many 700,000 units shipped retailers allegedly remained shelves months prompting blackberry introduce dramatic price reductions november 2011 increase sales sales rebounded following price cuts blackberry shipping approximately 2.5 million blackberry playbooks june 1 2013 end month ceo announced platform would developed rumors forthcoming computer nicknamed 'blackpad press expected similarity apple competing ipad circulated several months announcement research motion co-ceo mike lazaridis adobe systems cto kevin lynch staged first public demonstration playbook october 25 2010 onstage opening-day keynote adobe max 2010 conference among features demonstrated tight integration support adobe air applications full flash support according lazaridis 're trying dumb internet mobile device 've done bring mobile devices level desktop computers lazaridis announced end presentation developers get adobe air applications approved blackberry app world would eligible free blackberry playbook tablets since free playbook offer extended include webworks applications blackberry playbook supports 1080p video playback playbook features 3 mp front-facing camera video chatting wi-fi rear-facing 5 mp camera record 1080p video playbook 1024×600 wsvga aspect ratio 16:9 making device perfectly acceptable viewing hd video content media 7-inch display 3d graphics acceleration features variety sensors including invensense 6-axis gyroscope magnetometer accelerometer playbook uses dual-core texas instruments omap4430 processor newer faster playbook included dual-core texas instruments omap4460 processor blackberry playbook supports high resolution video playback h.264 mpeg4 wmv audio mp3 aac 5.1 wma 5.1 audio playback formats also micro-hdmi port hdmi video output blackberry playbook receives score 428 html5 test browser placing 4th tablets beating chrome beta chrome 18 ios 7 safari ios 6.0 safari opera mobile 12.10 silk 2.2 amazon kindle fire internet explorer 11 android 4.0 browsers blackberry tablet os 2.1 adobe flash version 11.1.121.74 support flash content usable blackberry playbook released canada usa april 19 2011 uk netherlands june 16 2011 united arab emirates june 25 2011 early reviews product mixed praising playbook fluid ui adobe flash supported webkit-based browser flash video support fast javascript html 5.0 web page rendering hdmi output multitasking capabilities playbook criticized initially requiring blackberry native email calendar applications although third party email calendar applications supported platform also relatively native third party applications compared platforms though number available steadily risen following mixed reviews blackberry playbook began gain traction receive better reviews temporary issues solved walt mossberg columnist wall street journal wrote got strong impression rim scrambling get product market rim co-ceo jim balsillie countered critics noting 60 million blackberry smartphones use ability pair playbook april 2013 blackberry ceo thorsten heins stated interview five years n't think 'll reason tablet anymore position analysts attributed blackberry spectacular failure tablet market playbook time launch 2,000 3,000 apps available blackberry app world may 1 2012 24,700 playbook applications available blackberry app world blackberry announced march 24 2011 would expand application ecosystem playbook include blackberry java android-based applications press release blackberry stated developers would able simply repackage code sign submit android apps blackberry app world however first update android 2.3 applications able run playbook applications became available blackberry tablet os 2.0 released february 21 2012 however java applications available future update popular android applications ported onto blackberry world pinterest whatsapp installed users sideloading process however 2.1 os update rim denied sideloading process first decision blackberry ship playbook without native applications e-mail calendar became source criticism derision reviewers users way access email web browser blackberry bridge third-party applications app world blackberry chose security reasons however blackberry made native applications available update system software playbook os 2.0 released february 21 2012 software update added integrated native email calendar contact apps also included visual changes operating system support variety android applications also brought three new applications built os press reader newspaper reader news rss reader print go used send documents pc playbook bbm aka blackberry messenger support included 2.0 update although blackberry intends support bbm future update bbm still supported blackberry bridge software allowing users continue access bridged blackberry smartphone october 3 2012 blackberry released playbook os 2.1 january 30 2013 blackberry confirmed wi-fi playbook newer cellular playbooks would receiving update new blackberry 10 operating system 2013 june 28 2013 company announced plans bring blackberry 10 playbook canceled sparking fears device potential scrapping according blackberry ceo thorsten heins multiple teams spent great deal time energy investigating ways bring os device ultimately heins intervened cancel project citing dissatisfaction level performance user experience immediate decisions device future certain heins promise blackberry would support playbook existing software platforms configurations blackberry bridge accesses mail calendar contacts directly tethered blackberry phone playbook meets encryption standards blackberry phone cryptographic components blackberry os kernels cryptography-related os java modules certified fips 140-2 makes tablet eligible use u.s. federal government agencies blackberry playbook os2.1 update september 2012 enabled full-disk encryption device using algorithm previously used limited enterprise kernel handling tethered content paired blackberry phone first playbook tablet wi-fi connectivity dual core 1 ghz texas instruments omap 4430 processor customers could purchase wifi playbook 16 gb 32 gb 64 gb storage configurations june 2012 16 gb model discontinued however 32 64 gb wi-fi versions remained sale august 2012 playbook 4g lte released canada featured dual-core 1.5 ghz processor 4g lte umts/hspa+ cellular connectivity nfc chip unlike earlier playbook model playbook 4g lte sold carrier channels november 2012 another variant 1.5 ghz playbook playbook 3g+ released uk unlike wi-fi models 4g lte 3g+ models available 16 gb 64 gb versions following launch blackberry 10 operating system blackberry z10 smartphone blackberry ceo thorsten heins confirmed company exploring opportunities future tablet releases announced plans tablet market playbook would converted new blackberry 10 os decided stop efforts focus core hardware portfolio mobile phones thereby bringing playbook end-of-life march 2015 blackberry announced blackberry secutablet tablet uses samsung knox hardware samsung galaxy tab 10.5 august 2011 blackberry advertised following made playbook accessories leather slipcase valextra italy premium charger delvaux belgium envelope-style leather case leather journal rapid charging pod neoprene zip sleeve convertible case blackberry earphones ganzo japan leather zipped pocket porter japan nylon canvas sleeve zipped bag want les essentiels de la vie canada leather zippered wallet-style case soft shell leather sleeve rapid travel charger brooklyn japan calfskin case ettinger england leather case neoprene sleeve torch smartphone accessing emails leather envelope various sources estimated sales figure launch day alone approximately 50,000 exceeding analyst expectations blackberry announced quarterly earnings half million playbook tablets shipped first quarter however lukewarm market reception reports company allegedly revised second-quarter estimates 2.4 million 800,000 – 900,000 units following several months poor sales blackberry started discounting price playbook original retail price improve product run rate retail december 2011 blackberry took 485 million write-down account offering price discounts sales improved subsequent quarters result according strategy analytics figures 2011 second quarter playbook market share middle 2011 3.3 compared ios ipads apple 61.3 android google 30.1 various windows microsoft 4.6 however playbook remained relatively popular tablet canada earlier years accounting nearly 20 tablet market research motion home country report released july 2012 strong discounting older wi-fi playbooks resulted strong sales uk christmas 2012
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Operating systems
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incremental rendering incremental rendering refers feature built modern web browsers specifically refers browser ability display partially downloaded web page user browser awaits remaining files server advantage user perceived improvement responsiveness web browser web site purpose incremental rendering similar purpose interlaced jpeg improves presentation speed user quickly displaying low-resolution version image improves high-resolution rather image slowly paints top bottom without incremental rendering web browser must wait code page fully loaded present content user earlier web browsers offered something compromise displaying html page entire html file retrieved inserting images one-by-one retrieved afterwards although utility incremental rendering seems intuitively obvious making happen something art well science sequence various elements web page render almost never strictly top-to-bottom programming fills missing pieces must certain amount guesswork determine best display partial content images particular virtually always loaded following html page browser must consult html file order know images request server server n't present automatically without follow-up request web designers web design software often include hints assist process example including expected heights widths images html code browser may allocate correct amount screen space image actually retrieved server
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Web technology
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digital multiplex system digital multiplex system dms name shared among several different telephony product lines nortel networks wireline wireless operators among dms-1 originally named dms-256 rural/urban digital loop carrier dms-10 telephone switch dms supernode family telephone switches dms-100 dms-200 dms-250 dms-300 dms-500 dms-gsp dms-msc dms-mtx s/dms optical transmission system exploratory development technology began northern telecom bell northern research labs ottawa ontario 1971 first class 5 switch dms-10 began service 21 october 1977 fort white florida first toll switch class 4 dms-200 entered service 1979 ottawa ontario dms-10 first commercially successful class 5 digital switch north american market profound impact industry numerous digital switching products introduced north american telephone market late 1970s nortel dms family still production genband acquired nortel cvas assets including dms line 2011 rolled ip-based genius platform genius-750nt first product include adaptive nano-tech compression resynchronization modules ericsson replace digital cross-connect dcs place since earliest dms releases previously new technology entered telecommunications industry slowly telephone companies amortizing equipment periods long forty years intending delay introduction digital switching 1990s dms introduction digital technology changed industry became one antecedents encouraged growth internet october 16 2006 nortel received special recognition award canada telecommunications hall fame role pioneering digital communications digital multiplex system dms name arose designation switching matrix design developed exploratory phase project digital multiplexed switch selected basic switching design project product intended successor nortel first electronic switch sp1 called sp2 however dms acronym mellifluous eventually 1975 adopted designation dms-10 dms-100 family products standing system rather switch applied entire digital switching family well dms-1 family digital transmission concentrators dms favoured many european cable operators switching platform voice networks dms-10 widely used rural wireline providers dms-100 200 switches widely deployed throughout u.s. canada regional bell operating companies bell canada independent telephone companies well us military dms-250 backbone number carriers long distance networks dms-300 international gateway switch dms-500 commonly deployed competitive local exchange carriers combines dms-100 250 capabilities dms switches run proprietary multitasking operating system known sos user interface called mapci consists series multi-level menus usually accessed connected vt100 compatible dumb terminal terminal emulator level overlay performs different functions
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Internet protocols
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codd theorem codd theorem states relational algebra domain-independent relational calculus queries two well-known foundational query languages relational model precisely equivalent expressive power database query formulated one language expressed theorem named edgar f. codd father relational model database management domain independent relational calculus queries precisely relational calculus queries invariant choosing domains values beyond appearing database queries may return different results different domains excluded example forbidden query query select tuples occurring relation r r relation database assuming different domains i.e. sets atomic data items tuples constructed query returns different results thus clearly domain independent codd theorem notable since establishes equivalence two syntactically quite dissimilar languages relational algebra variable-free language relational calculus logical language variables quantification relational calculus essentially equivalent first-order logic indeed codd theorem known logicians since late 1940s query languages equivalent expressive power relational algebra called relationally complete codd codd theorem includes relational calculus relational completeness clearly imply interesting database query expressed relationally complete languages well-known examples inexpressible queries include simple aggregations counting tuples summing values occurring tuples operations expressible sql relational algebra computing transitive closure graph given binary edge relation see also expressive power codd theorem also n't consider sql nulls three-valued logic entail logical treatment nulls remains mired controversy additionally sql allows duplicate rows multiset semantics nevertheless relational completeness constitutes important yardstick expressive power query languages compared
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Databases
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padding oracle attack cryptography padding oracle attack attack uses padding validation cryptographic message decrypt ciphertext cryptography variable-length plaintext messages often padded expanded compatible underlying cryptographic primitive attack relies padding oracle freely responds queries whether message correctly padded padding oracle attacks mostly associated cbc mode decryption used within block ciphers padding modes asymmetric algorithms oaep may also vulnerable padding oracle attacks symmetric cryptography padding oracle attack applied cbc mode operation oracle usually server leaks data whether padding encrypted message correct data allow attackers decrypt sometimes encrypt messages oracle using oracle key without knowing encryption key standard implementation cbc decryption block ciphers decrypt ciphertext blocks validate padding remove pkcs7 padding return message plaintext server returns invalid padding error instead generic decryption failed error attacker use server padding oracle decrypt sometimes encrypt messages mathematical formula cbc decryption depicted cbc decryption xors plaintext block previous ciphertext block result single-byte modification block formula_3 make corresponding change single byte formula_4 suppose attacker two ciphertext blocks formula_5 wants decrypt second block get plaintext formula_4 attacker changes last byte formula_3 creating formula_8 sends formula_9 server server returns whether padding last decrypted block formula_10 correct equal 0x01 padding correct attacker knows last byte formula_11 formula_12 therefore formula_13 padding incorrect attacker change last byte formula_8 next possible value attacker need make 256 attempts one guess every possible byte find last byte formula_4 decrypted block contains padding information bytes used padding additional attempt need made resolve ambiguity determining last byte formula_4 attacker use technique obtain second-to-last byte formula_4 attacker sets last byte formula_4 formula_19 setting last byte formula_3 formula_21 attacker uses approach described time modifying second-to-last byte padding correct 0x02 0x02 block consists 128 bits aes example 16 bytes attacker obtain plaintext formula_4 255⋅16 4080 attempts significantly faster formula_23 attempts required bruteforce 128-bit key original attack published 2002 serge vaudenay concrete instantiations attack later realised ssl ipsec also applied several web frameworks including javaserver faces ruby rails asp.net well software steam gaming client 2012 shown effective hardened security devices earlier attacks fixed tls implementors following public announcement new variant lucky thirteen attack published 2013 used timing side-channel re-open vulnerability even implementations previously fixed early 2014 attack longer considered threat real-life operation though still workable theory see signal-to-noise ratio certain class machines active area development attacks upon cryptographic protocols used secure internet traffic downgrade attack logjam export rsa/freak attacks trick clients using less-secure cryptographic operations provided compatibility legacy clients secure ones available attack called poodle late 2014 combines downgrade attack ssl 3.0 padding oracle attack older insecure protocol enable compromise transmitted data may 2016 revealed cve-2016-2107 fix lucky thirteen openssl introduced another padding oracle
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Computer security
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allot allot ltd. formerly allot communications multinational offices subsidiaries many countries across world allot provider security monetization products allot solutions include deep packet inspection dpi technology change broadband pipes smart networks offering complete network visibility application control subscriber management 2016 company reported 90.4 million revenue allot founded 1996 michael shurman yigal jacoby served chief executive chairman 2006 jacoby previously founded armon networking manufacturer rmon-based network management solutions sold bay networks 33 million 1996 november 2003 deloitte touche named allot fourth fastest-growing company technology fast 50 list citing company revenue growth nearly 1,900 year time 2004 allot raised 38 million several rounds funding several venture capital funds including genesis partners gemini walden israel jafco investment bancboston capital jerusalem venture partners tamar technology ventures november 2006 allot became publicly traded company nasdaq global market ticker symbol allt ipo raised 78 million november 2010 allot dual listing tel aviv stock exchange approved allot partnered openet january 2011 optimize monetization mobile broadband networks allot featured deloitte fast 50 list 2014 131 growth 2009 2013 allot joined hp opennfv partner program july 2015 allowing expand traffic detection function security services onto hp opennfv platform nokia networks partnered allot january 2016 enhance visibility control security swisscom later year allot partnered intel security release mcafee unified security powered allot focused end-to-end security capabilities telefónica partnered allot february 2017 improve user experience enhance network-based security services also 2017 company announced partnerships several russian satellite network operators 2011 reported equipment sold allot illegally reached iran however january 2012 allot cleared ministry defense wrongdoing investigation concluded company unaware internet monitoring equipment sold danish distributor ended iranian hands also 2011 allot settled class-action lawsuit regarding securities fraud involving stock whereby agreed pay 1.3 million usd september 2002 allot acquired netreality provider network application priority switches naps order enhance quality service qos bandwidth management solutions allot acquired esphion new zealand–based developer network protection solutions carriers internet service providers january 2008 acquisition expanded allot mitigation security threats addition isolation remedy infected subscribers distributed denial service ddos attack prevention may 2012 allot acquired ortiva wireless san diego-based developer video traffic optimization equipment allot acquired oversi networks provider rich-media caching content delivery solutions internet video peer-to-peer p2p traffic july 2012 march 2015 allot acquired global security company optenet expanded company security-as-a-service offerings january 2018 allot acquired netonomy ltd. developer software-based cyber security connected home allot provides network intelligence solutions network-based security products communication service providers csps mobile broadband wireless broadband mobile satellite service dsl carriers well enterprises allot portfolio hardware platforms software applications employs dpi turn broadband pipes smart networks value-added internet services rapidly deployed released 2009 allot service gateway-sigma designed increase subscriber quality experience qoe ability generate additional revenue streams 2014 allot released allot service gateway tera unified framework physical virtual deployment across access networks december 2014 allot unveiled allot cloud access optimization designed enterprises cloud managed service providers three levels coverage used office 365 adds visibility control security applications allot smartengage designed enhance company engagement subscribers launched february 2015 smartengage uses allot service gateway traffic awareness feature suggest content based browsing activity may 2015 vodafone germany announced deployment allot websafe personal network-based security-as-a-service offering designed mobile users well small medium business clients includes anti-malware parental control options later year allot released allot service gateway-virtual edition allot sg-ve original service gateway introduced 2007 improve efficiency monetization options companies new framework integrates gateway framework virtual network remove physical hardware constraints february 2016 allot released allot service gateway 9500 expanding capabilities include enterprises data centers service providers june 2016 belgian cable company voo announced began using allot service gateway tera allot serviceprotector network traffic visibility analytics security along allot cmts manage congestion qos assurance 2017 allot released allot secure service gateway built allot service gateway utilizing real-time application-based traffic monitoring analytics deliver granular application level visibility ensure higher qoe users allot ssg combines application-based visibility control web security protects ddos attacks phishing threats
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Computer security
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social blade social blade sometimes spelled socialblade website tracks social media statistics analytics social blade notably tracks youtube platform also analytical information regarding twitch instagram twitter facebook mixer dailymotion social blade functions third-party respective social media platforms jason urgo ceo social blade jason urgo ceo social blade launched website february 2008 track statistics website digg 2010 website switched track youtube statistics october 2012 social blade became llc 2014 social blade launched consulting channel management services october 24 2018 social blade started popular live stream show subscriber difference t-series pewdiepie online competition stream regularly 900 viewers led large increase subscriber count accompany attention april 2019 social blade pulled april fools joke allowed users change subscriber counts ranks ridiculously high numbers frequently asked questions faq page social blade wrote order best scale tracking meet needs millions use social blade pull data youtube public api means 're getting information see public youtube channel pages work examine data across multiple days aggregate display format useful social blade website contains subscriber predictions social blade also provides real-time subscriber count updates social blade also noted work content creators youtube multi-channel networks mcns help creators get partnered official youtube twitter account teamyoutube wrote please know third party apps socialblade accurately reflect subscriber activity social blade twitter account responded tweet commenting n't make data get youtube api rely accuracy social blade community manager danny fratella suggested youtube content creators may notice subscriber view count purges due higher accessibility data-tracking tools like social blade social blade data analytics cited mainstream news media outlets money nbc huffpost outlets focused internet culture well kotaku polygon tubefilter aside using subscriber follower statistics reported social blade media outlets also cite social blade regards content creator account estimated earnings huffpost wrote social blade estimates earnings youtube channel based money generated every thousand ad views estimates n't exact instead create minimum maximum amount channel could earning cases range huge social blade support services manager jenna arnold stated range huge cpms cost per thousand views vary much anywhere 0.25 4.00 average urgo also commented 0.25– 4.00 per 1,000 views range stating data points change time time exact science generally hold true channels social blade blog also noted continuously updated articles news interest content creators helping stay top evolving trends ways better use youtube social media services
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Web technology
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web services semantics web services semantics wsdl-s proposed extension wsdl standard wsdl-s extends standard wsdl include semantic elements improve reusability web services facilitating composition services improving discovery enabling integration legacy software web services framework wsdl-s developed ibm university georgia
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Web technology
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anaphoric macro anaphoric macro type programming macro deliberately captures form supplied macro may referred anaphor expression referring another anaphoric macros first appeared paul graham lisp name reference linguistic anaphora—the use words substitute preceding words codice_1 macro ansi common lisp anaphoric binding codice_2 result test expression clause example sums value non-codice_3 elements codice_2 refers values elements equal codice_3 codice_2 bound output codice_7 true collecting numbers larger 3 one example anaphoric version if-then-else construct introduces anaphor codice_2 bound result test clause another example anaphoric version λ-function binds function anaphor codice_9 allowing recur
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Programming language topics
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gemfire gemfire released japan royal blood ロイヤルブラッド roiyaru buraddo super royal blood スーパーロイヤルブラッド sūpā roiyaru buraddo super famicom version medieval war game msx nintendo entertainment system super nes fm towns mega drive/genesis ms-dos later windows developed koei object game unify fictional island force players use infantry cavalry archers well fantasy units magicians dragons gargoyles order capture castle needed control particular territory sequel royal blood ii released japan market japanese windows game takes place fictitious isle ishmeria upon time six wizards wielding unique brand magic used powers protect island maintain peace disrupted collectively challenged fire dragon summoned forth wizard intent plunging country darkness sea-dwelling dragon peace known pastha charged six wizards task fighting back succeeded sealing fire dragon away ruby top crown became six jewels around crown base crown called gemfire symbol utmost power authority gemfire fell hands current king ishmeria eselred sought abuse object power using embark tyrannical reign instilling fear within oppressed subjects ishmeria fell despair power flourished finally young daughter princess robyn could bear watch father grievous misdeeds longer—she seized gemfire pried six wizard gems loose causing shoot upward sky circle briefly overhead scattering different parts ishmeria furious eselred learned robyn actions locked away tower futile deed already done robyn taken crucial first step toward freeing people meanwhile six wizards take residence prominent family ishmeria two powerful clans blanches led prince erin supported zendor emerald wizard wielder lightning lyles led prince ander backed pluvius sapphire wizard caster meteors four clans flax coryll chrysalis molbrew also wizards scylla empyron chylla skulryk respectively gemfire disposal beginning breaking spell gemfire clans sets unseat eselred claim throne restore order peace ishmeria outset game player option selecting scenario family chosen scenario changes relative power territories families although minor families present one two scenarios every family playable least one scenario except blanche lyle playable four lankshire played ultimately player must conquer entire map win game gameplay divided main world map screen individual battle screens map screen player allowed one action per turn in-game month per territory action player may hire move troops upgrade territory economy defenses engage diplomatic actions sabotage plunder neighboring territory attack adjacent enemy territory adjacent territories may attacked upon attacking attacked enemy focus shifts battle wherein player may field five units archers knights horsemen either wizard hired unit player moves individual companies troops map turn-based tactics fashion certain units may build fences keep enemies one army wins enemy base captured enemy units defeated enemy army runs food
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Computer architecture
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preview macos preview image viewer pdf viewer macos operating system enables users view print digital images portable document format pdf files preview uses apple implementation pdf specification aqua graphical user interface quartz graphics layer imageio core image frameworks like macos originated nextstep operating system company next part every release nextstep os since 1989 preview open following file types version preview included os x 10.3 could loop animated gifs via optional play button could added toolbar os x 10.4 preview lost playback functionality animated gifs would instead display individual frames numbered sequence preview encrypt pdf documents restrict use example possible save encrypted pdf password required copy data document print however encrypted pdfs edited original author always keep unencrypted version features otherwise available professional pdf editing software provided preview possible extract single pages multi-page documents e.g pdf files sort pages drag drop single multiple pages several opened multi-page documents applications attaching opened email message preview offers basic image correction tools using core image processing technology implemented macos features like shape extraction color extraction cropping rotation tools annotating images preview uses vector shapes text image rasterized jpeg png another bitmap format pdf image documents also supplied keywords automatically indexed using macos system-wide spotlight search engine preview directly access image scanners supported macos import images scanner preview convert image formats export bmp jp2 jpeg pdf pict png sgi tga tiff using macos print engine based cups also possible print postscript file pdf-x file directly save file iphoto example scanned photos beginning mac os x 10.7 lion preview restricts format option popup menu save dialog commonly used types possible access full format list holding option key clicking format popup menu gif icns jpeg jpeg-2000 microsoft bmp microsoft icon openexr pdf photoshop png sgi tga tiff new edit button picture edited introduced version 7 edit button allows options insert shapes lines cropping among things os x 10.9.2 preview support iso-standardized pdf iso 32000 saving destroys aspects pdf files without warning user
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Operating systems
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presentation semantics computer science particularly human-computer interaction presentation semantics specify particular piece formal language represented distinguished manner accessible human senses usually human vision example saying codice_1 must render text constructs using bold typeface specification presentation semantics syntax example interactive presentation semantics defining expected behavior hypertext link suitable syntax many markup languages like html css dsssl xsl-fo troff presentation semantics others like xml xlink xpath character encoding standards like unicode also presentation semantics one main goals style sheet languages like css separate syntax used define structured data syntax endowed presentation semantics used render data various ways
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Programming language topics
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refs resilient file system refs codenamed protogon microsoft proprietary file system introduced windows server 2012 intent becoming next generation file system ntfs refs designed overcome problems become significant years since ntfs conceived related data storage requirements changed key design advantages refs include automatic integrity checking data scrubbing removal need running chkdsk protection data degradation built-in handling hard disk drive failure redundancy integration raid functionality switch copy/allocate write data metadata updates handling long paths filenames storage virtualization pooling including almost arbitrarily sized logical volumes unrelated physical sizes used drives requirements arose two major changes storage systems usage – size storage use large massive arrays multi-terabyte drives fairly common need continual reliability result file system needs self-repairing prevent disk checking impractically slow disruptive along abstraction virtualization physical disks logical volumes refs initially added windows server 2012 aim gradual migration consumer systems future versions achieved windows 8.1 initial versions removed ntfs features disk quotas alternate data streams extended attributes re-implemented later versions refs early versions 2012–2013 refs similar slightly faster ntfs tests far slower full integrity checking enabled result attributed relative newness refs pre-release concerns also voiced one blogger storage spaces storage system designed underpin refs reportedly could fail manner prevented refs recovering automatically ability create refs volumes removed windows 10 2017 fall creators update editions except enterprise pro workstations would seem indicate microsoft longer intending refs general replacement ntfs least near future cluster size refs volume either 4 kib 64 kib ntfs features implemented refs include object ids 8.3 filename ntfs compression encrypting file system efs transactional ntfs hard links extended attributes disk quotas addition windows booted refs volume dynamic disks mirrored striped volumes replaced mirrored striped storage pools provided storage spaces however automated error-correction supported mirrored spaces data deduplication missing early versions refs. implemented v3.2 debuting windows server v1709 support alternate data streams initially implemented refs windows 8.1 64-bit server 2012 r2 file system reacquired support alternate data streams lengths 128k automatic correction corruption integrity streams used parity spaces refs initially unsuitable microsoft sql server instance allocation due absence alternate data streams march 2015 review state refs windowsnetworking.com stated ’ least time boot windows refs volume first versions refs ’ include file-level compression encryption disk quotas hard links advantages ntfs fat file systems note refs support sparse files reparse points case-sensitive file names unicode file names perhaps important preserves enforces access control lists acls ’ obvious refs current iteration replacement ntfs ... applications rely specific ntfs features might work refs ... however ... storage conventional data ’ require specific ntfs features ’ supported refs refs handle duty nicely primary use case file servers store extremely large amounts data data integrity recovery mechanisms built file system well means tools designed detect repair file corruption file systems ’ necessary incompatibility refs ’ really issue additionally although refs ’ support file level encrypting file system encryption bitlocker used protect refs volumes ’ much issue either ... refs distinct advantages current reigning windows file system ntfs also drawbacks boasts self-healing powers ability repair files without time less risk data lost ’ power failure due way writes metadata course ability create huge volumes files even give files names longer 255 characters wish ’ quite ready prime time yet refs different versions various degrees compatibility operating system versions aside development versions filesystem usually later operating system versions mount filesystems created earlier os versions backwards compatibility features may compatible feature set os version cluster size features filesystem queried command fsutil fsinfo refsinfo volumename notes issues identified suggested refs running storage spaces intended design include storage developer conference 2015 microsoft developer presented enhancements refs expected released windows server 2016 included technical preview 4 titled refs v2 highlighted refs included capabilities high speed moving reordering cloning blocks files done blocks file particularly needed virtualization stated allow fast provisioning diff merging tiering enhancements cover redo log synchronous disk writes parallelization efficient tracking uninitialized sparse data files efficient 4k i/o refs file integrity enabled also acts like log-structured file system coalescing small random writes large sequential ones efficiency operating systems competing file systems refs best known zfs btrfs sense three designed integrate data protection snapshots silent high speed background healing corruption data errors 2012 phoronix wrote analysis refs vs btrfs copy-on-write file system linux features similar supporting checksums raid-like use multiple disks error detection/correction however refs lacks copy-on-write snapshots compression found btrfs zfs 2014 review refs assessment readiness production use concluded refs least advantages two main file system competitors
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Computer file systems
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chronosync chronosync macos application periodic backups bootable drive clones folder synchronizations offers ability target device folder visible finder volume thumb drive nas disk image server another mac 2014 chronosync received top software pick about.com received 10 10 rating apple daily report
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Computer security
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sparcstation 1 sparcstation 1 sun 4/60 first sparcstation series sparc-based computer workstations sold sun microsystems distinctive slim enclosure square 3 inch high pizza box first sold april 1989 sun support ending 1995 based lsi logic risc cpu running 20 mhz weitek 3170 3172 fpu coprocessor fourth sun computer 4/260 4/110 4/280 use sparc architecture first sun4c architecture motherboard offered three sbus slots built-in aui ethernet 8 khz audio 5 mb/s scsi-1 bus basic display ran 1152×900 256 colours monitors shipped computer 16 19 inch greyscale colour designed ease production compete high-end pcs macs principal competitors macintosh ii ibm ps/2 model 80 next computer sun 3/80 sold us 9,000 hard disks us 20,000 — first year around 35,000 units sold sparcstation 1 features several distinctive design packaging elements driven internally system designer andy bechtolsheim externally design house frogdesign bechtolsheim specified motherboard would size sheet paper sbus expansion cards would size index cards resulting extremely compact footprint external design motif includes dot-patterned cooling vents side echoed dimple pattern front face sun purple feet sparcstation 1 takes 30 pin simms groups four take either 1 mb 4 mb simms long size consistent within bank total four memory banks give total 64 mb memory memory bank nearest floppy disk drive filled first openboot firmware hang memory checking sparcstation 1 space two hard drives one floppy drive internally machine take 50 pin scsi-2 hard drive openboot firmware boot partition starts ends 1024 mb floppy drive like macintosh unusual electromechanical eject mechanism rather conventional eject button therefore must ejected operating system openboot machine connect scsi cd drive via either scsi connector back connecting spare internal scsi connector via 50 pin cable sparcstation 1 comes on-board amd lance ethernet chipset 15-pin aui connector connect 10base2 10base5 10baset via appropriate transceiver openboot rom able boot network using rarp tftp like sparcstation systems sparcstation 1 holds system information mac address serial number nvram battery chip dies system able boot sparcstation 1 uses m48t02 battery-backed rtc ram chip handles real time clock boot parameter storage problem chip battery internal means entire chip must replaced battery runs sparcstation 1s made older battery life chip substantial number systems refuse boot additionally sparcstation 1 design used reserved bits m48t02 nvram non-standard way since later revisions m48t02 chip exert stricter control bits current m48t02 store nvram data rtc function correctly system may fail auto-boot due incompatibilities modern m48t02s common modify failed nvrams cutting encapsulation patching new battery also possible replace entire encapsulation also contains 32.768 khz clock crystal sparcstation 1 1+ ipc slc run following operating systems sparcstation 1+ sun 4/65 pushed cpu 25 mhz lsi l64801 upgraded coprocessor weitek 3172 installed new scsi controller sparcstation ipc sun 4/40 version sparcstation 1+ lunchbox style case onboard video sparcstation slc sun 4/20 version sparcstation 1+ built monitor cabinet sparcstation 2 sun 4/75 machine successor released 1990
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Computer architecture
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check point integrity check point integrity endpoint security software product developed check point software technologies designed protect personal computers networks connect computer worms trojan horses spyware intrusion attempts hackers software aims stop new pc threats attacks signature updates installed pc software includes administrator manages security policies apply groups users central console server check point acquired integrity software part acquisition endpoint security start-up zone labs 2004 integrity software released early 2002 derived zonealarm security technology added central policy management network access control functions integrity integrated network gateways cisco vpn 3000 series ensure pc met security requirements granted access network demand endpoint security grew 2003 sql slammer blaster computer worms reportedly caused extensive damage despite widespread use antivirus software personal computers number destructive worms followed subsequent rise spyware significant problem continued increase demand endpoint security products data privacy integrity regulations required security audits mandated governmental professional authorities along infections damage caused guest pc access also prompted use security software competitors include symantec/sygate cisco security agent mcafee entercept even point products like determina memory firewall
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Computer security
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pwn2own pwn2own computer hacking contest held annually cansecwest security conference beginning 2007 contestants challenged exploit widely used software mobile devices previously unknown vulnerabilities winners contest receive device exploited cash prize masters jacket celebrating year win name pwn2own derived fact contestants must pwn hack device order win pwn2own contest serves demonstrate vulnerability devices software widespread use also providing checkpoint progress made security since previous year first contest conceived developed dragos ruiu response frustration apple lack response month apple bugs month kernel bugs well apple television commercials trivialized security built competing windows operating system time widespread belief despite public displays vulnerabilities apple products os x significantly secure competitors march 20 roughly three weeks cansecwest year ruiu announced pwn2own contest security researchers dailydave mailing list contest include two macbook pros would leave conference floor hooked wireless access point conference attendee could connect wireless access point exploit one devices would able leave conference laptop monetary reward ruiu outlined would progressively loosened restrictions hacks acceptable three days conference first day conference ruiu asked terri forslof zero day initiative zdi participate contest zdi programme purchases zero-day attacks reports affected vendor turns signatures network intrusion detection system increasing effectiveness vulnerabilities sold zdi made public affected vendor issued patch forslof agreed zdi offer purchase vulnerabilities used contest flat price 10,000 first contest intended highlight insecurity apple mac os x operating system since time widespread belief os x far secure competitors contest took place thursday april 18 saturday april 20 2007 two macbook pro laptops one 13 one 15 left conference floor cansecwest joined separate wireless network certain attacks allowed restrictions progressively loosened three days conference order win 15 macbook pro contestants would required escalate privileges root gaining access initial exploit 10,000 prize announced zdi laptops hacked first day shane macaulay called former co-worker dino dai zovi new york urged compete second day starting thursday night dai zovi found exploited previously unknown vulnerability quicktime library loaded safari 3am night following morning dai zovi packaged exploit code sent macaulay conference vancouver macaulay placed dai zovi exploit code website e-mailed contest organizers link clicked contest laptop dai zovi exploit code allowed shane take control laptop winning contest proxy dai zovi thank helping win contest dai zovi let macaulay keep 15 macbook pro dai zovi separately sold vulnerability zdi 10,000 prize successful 2007 contest scope pwn2own contest expanded include wider array operating systems browsers contest would demonstrate widespread insecurity software widespread use consumers dragos refined contest help wide panel industry experts contest administered zdi would offer purchase vulnerabilities demonstration vulnerabilities zdi purchases details vulnerabilities used pwn2own would provided affected vendors public details would withheld patch made available contestants successfully demonstrated exploits contest could sell vulnerabilities zdi prizes 20,000 first day 10,000 second day 5,000 third day pwn2own 2008 took place thursday march 26 saturday march 28 2008 2008 contest three different target laptops running default installation either windows vista ultimate sp1 os x 10.5.2 ubuntu linux 7.10 previous year contest pwn2own took place course three days certain attacks allowed day laptop running os x exploited second day contest exploit safari browser co-written charlie miller jake honoroff mark daniel independent security evaluators exploit targeted open-source subcomponent safari browser laptop running windows vista sp1 exploited third day contest exploit adobe flash co-written shane macaulay alexander sotirov derek callaway contest adobe disclosed co-discovered vulnerability internally working patch time pwn2own laptop running ubuntu exploited considerably success targeting web browsers category software third pwn2own focused popular browsers used consumer desktop operating systems added another category mobile devices contestants challenged hack via many remote attack vectors including email sms messages website browsing pwn2own 2009 took place three days cansecwest thursday march 18 saturday march 20 2009 contestants demonstrated successful exploits contest offered rewards underlying vulnerabilities zdi 5,000 browser exploits 10,000 mobile exploits browser targets internet explorer 8 firefox chrome installed sony vaio running windows 7 beta safari firefox installed macbook running mac os x browsers fully patched default configurations first day contest previous years attack surface contest expanded three days multiple winners per target allowed first contestant exploit laptop would get mobile device targets included blackberry android iphone symbian windows mobile phones default configurations specific devices included browser contest attack surface available contestants expanded three days order prove able successfully compromise device contestants demonstrate could collect sensitive data mobile device incur type financial loss mobile device owner multiple winners per device allowed first contestant exploit mobile device would get along one-year phone contract based increased interest competing year zdi arranged random selection determine team went first target first contestant selected charlie miller exploited safari os x without aid browser plugins interviews winning contest miller stressed took minutes run exploit safari took many days research develop exploit used researcher identified nils selected go miller nils successfully ran exploit internet explorer 8 windows 7 beta writing exploit nils bypass anti-exploitation mitigations microsoft implemented internet explorer 8 windows 7 including data execution protection dep address space layout randomization aslr nils continued trying browsers although miller already exploited safari os x nils exploited platform moved exploit firefox successfully near end first day julien tinnes sami koivu remote successfully exploited firefox safari os x vulnerability java time os x java enabled default allowed reliable exploitation platform however due reported vulnerabilities vendor already tinnes participation fell outside rules contest unable rewarded next days contest attract additional contestants chrome well mobile devices went unexploited pwn2own 2009 competition started march 24 2010 total cash prize pool us 100,000 march 15—nine days contest begin—apple released sixteen patches webkit safari 40,000 100,000 reserved web browsers target worth 10,000 60,000 total 100,000 cash prize pool allotted mobile phone portion contest target worth 15,000 opera web browser left contests target zdi team argued opera low market share chrome safari included due default presence various mobile platforms however opera rendering engine presto present millions mobile platforms 2011 contest took place march 9 11th cansecwest conference vancouver canada web browser targets 2011 contest included microsoft internet explorer apple safari mozilla firefox google chrome new pwn2own contest fact new attack surface allowed penetrating mobile phones specifically cellphone basebands mobile phone targets dell venue pro running windows phone 7 iphone 4 running ios blackberry torch 9800 running blackberry os 6.0 nexus running android 2.3 following teams registered desktop browser contest mobile browser category following teams registered first day competition safari internet explorer defeated researchers safari version 5.0.3 installed fully patched mac os x 10.6.6 french security firm vupen first attack browser five seconds browser visited specially crafted malicious web page launched standard harmless payload demonstrate arbitrary code executed written file hard disk demonstrate sandbox bypassed internet explorer 32-bit version 8 installed 64-bit windows 7 service pack 1 security researcher stephen fewer harmony security successful exploiting ie demonstrated safari day 2 iphone 4 blackberry touch 9800 exploited iphone running ios 4.2.1 however flaw exists version 4.3 ios security researchers charlie miller dion blazakis able gain access iphone address book vulnerability mobile safari visiting exploit ridden webpage blackberry torch 9800 phone running blackberry os 6.0.0.246 team vincenzo iozzo willem pinckaers ralf philipp weinmann took advantage vulnerability blackberry webkit based web browser visiting previously prepared webpage firefox android windows phone 7 scheduled tested day 2 security researchers chosen platforms attempt exploits sam thomas selected test firefox withdrew stating exploit stable researchers chosen test android windows phone 7 show teams showed day three chrome firefox hacked 2012 rules changed capture-the-flag style competition point system new format caused charlie miller successful event past years decide attend pwn2own chrome successfully exploited first time vupen declined reveal escaped sandbox saying would sell information internet explorer 9 windows 7 successfully exploited next firefox third browser hacked using zero day exploit safari mac os x lion browser left standing conclusion zero day portion pwn2own versions safari fully patched running mac os x snow leopard compromised cve portion pwn2own noted significant improvements security mitigations within mac os x introduced lion google withdrew sponsorship event 2012 rules require full disclosure exploits winners specifically exploits break sandboxed environment demonstrated exploits win pwn2own defended decision saying believed hackers would attempt exploit chrome methods disclosed google offered separate pwnium contest offered 60,000 chrome-specific exploits non-chrome vulnerabilities used guaranteed immediately reported appropriate vendor sergey glazunov teenager identified pinkiepie earned 60,000 exploits bypassed security sandbox google issued fix chrome users less 24 hours pwnium exploits demonstrated google returned sponsor rules changed require full disclosure exploits techniques used web browsers google chrome internet explorer firefox along windows 8 java exploited french security firm vupen successfully exploited fully updated internet explorer 10 microsoft surface pro running 64-bit version windows 8 fully bypassed protected mode sandbox without crashing freezing browser vupen team exploited mozilla firefox adobe flash oracle java nils jon mwrlabs successful exploiting google chrome using webkit windows kernel flaws bypass chrome sandbox 100,000 george hotz exploited adobe acrobat reader escaped sandbox win 70,000 james forshaw joshua drake ben murphy independently exploited oracle java win 20,000 apple safari mountain lion targeted teams showed mobile pwn2own 2013 contest held november 13–14 2013 pacsec 2013 conference tokyo japan pinkie pie 50,000 google released chrome updates 14 nov address vulnerabilities exploited pwn2own 2014 vupen successfully exploited fully updated internet explorer 11 adobe reader xi google chrome adobe flash mozilla firefox 64-bit version windows 8.1 win total 400,000—the highest payout single competitor date company used total 11 distinct zero-day vulnerabilities nico joly vupen team—was sole competitor take windows phone lumia 1520 year entering exploit aimed ie 11 mobile successfully able exfiltrate cookie database however sandbox held unable gain full control system apple safari mac os x mavericks adobe flash windows 8.1 successfully exploited liang chen keen team zeguang zhao team509 collected 140,000 prize money internet explorer 11 windows 8.1 successfully exploited sebastian apelt andreas schmidt prize 100,000 mozilla firefox exploited jüri aedla mariusz młyński george hotz independently winning 50,000 anonymous participant exploited google chrome however upon review contest judges declared partial win due one portion presentation ’ collision vulnerability exploited earlier week pwnium competition 2015 every single prize available claimed 2016 chrome microsoft edge safari hacked according brian gorenc manager vulnerability research hpe chosen include firefox year wanted focus browsers made serious security improvements last year 2017 chrome successful hacks although one team attempted target chrome subsequent browsers best fared order firefox safari edge 2018 conference much smaller sponsored primarily microsoft shortly conference microsoft patched several vulnerabilities edge causing many teams withdraw nevertheless certain openings found edge safari firefox hack attempts made chrome although reward offered edge many microsoft products large rewards available anyone able gain access edge successfully exploited
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Computer security
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walter bright walter bright american computer programmer created programming language zortech c++ compiler empire computer game bright main developer first c++ compiler translate source code directly object code without using c intermediate zortech c++ later becoming symantec c++ digital mars c++ designing c++ compiler developed datalight c compiler also sold zorland c later zortech c. bright graduated caltech 1979 bachelor science aerospace engineering university wrote empire wargame pdp-10 mainframe completed 1977 walter bright creator programming language implemented compilers several languages considered expert many areas related compiler technology walter regularly writes scientific magazine articles compilers programming blogger dr. dobb journal hired facebook write fast c/c++ preprocessor
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Programming language topics
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national strategy secure cyberspace united states government national strategy secure cyberspace component larger national strategy homeland security national strategy secure cyberspace drafted department homeland security reaction september 11 2001 terrorist attacks released february 14 2003 offers suggestions mandates business academic individual users cyberspace secure computer systems networks prepared year research businesses universities government five months public comment plan advises number security practices well promotion cyber security education national strategy secure cyberspace identifies three strategic objectives 1 prevent cyber attacks america critical infrastructures 2 reduce national vulnerability cyber attacks 3 minimize damage recovery time cyber attacks occur meet objectives national strategy outlines five national priorities first priority creation national cyberspace security response system focuses improving government response cyberspace security incidents reducing potential damage events second third fourth priorities development national cyberspace security threat vulnerability reduction program creation national cyberspace security awareness training program necessity securing governments cyberspace aim reduce threats vulnerabilities cyber attacks fifth priority establishment system national security international cyberspace security cooperation intends prevent cyber attacks could impact national security assets improve international management response attacks ultimately national strategy encourages companies regularly review technology security plans individuals use internet add firewalls anti-virus software systems calls single federal center help detect monitor analyze attacks expanded cyber security research improved government-industry cooperation
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Computer security
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socket ft1 socket ft1 bga413 cpu socket released january 2011 amd apus codenamed desna ontario zacate hondo uber name brazos available chipsets consult fusion controller hubs fch
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Computer architecture
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xop instruction set xop extended operations instruction set announced amd may 1 2009 extension 128-bit sse core instructions x86 amd64 instruction set bulldozer processor core released october 12 2011 however amd removed support xop zen microarchitecture onward xop instruction set contains several different types vector instructions since originally intended major upgrade sse instructions integer instructions also contains floating point permutation floating point fraction extraction instructions see index list instruction types xop revised subset originally intended sse5 changed similar overlapping avx parts overlapped avx removed moved separate standards fma4 floating-point vector multiply–accumulate cvt16 half-precision floating-point conversion implemented f16c intel sse5 instructions equivalent similar instructions avx fma4 instruction sets announced intel changed use coding proposed intel integer instructions without equivalents avx classified xop extension xop instructions opcode byte 8f hexadecimal otherwise almost identical coding scheme avx 3-byte vex prefix commentators seen evidence intel allowed amd use part large vex coding space amd forced use different codes order avoid using code combination intel might possibly using development pipeline something else xop coding scheme close vex scheme technically possible without risking amd codes overlap future intel codes inference speculative since public information available negotiations two companies issue use 8f byte requires m-bits see vex coding scheme value larger equal 8 order avoid overlap existing instructions c4 byte used vex scheme restriction may prevent use m-bits purposes future xop scheme vex scheme another possible problem pp bits value 00 xop scheme value 01 vex scheme instructions legacy equivalent may complicate use pp bits purposes future similar compatibility issue difference fma3 fma4 instruction sets intel initially proposed fma4 avx/fma specification version 3 supersede 3-operand fma proposed amd sse5 amd adopted fma4 intel canceled fma4 support reverted fma3 avx/fma specification version 5 see fma history march 2015 amd explicitly revealed description patch gnu binutils package zen third-generation x86-64 architecture first iteration znver1 – zen version 1 support tbm fma4 xop lwp instructions developed specifically bulldozer family micro-architectures integer version fma instruction set four operand instructions similar fma4 operate signed integers horizontal addition instructions adds adjacent values input vector output size instructions describes wide horizontal addition performed instance horizontal byte word adds two bytes time returns result vector words byte quadword adds eight bytes together time returns result vector quadwords six additional horizontal addition subtraction instructions found ssse3 operate two input vectors two two operations set vector compare instructions take immediate extra argument immediate controls kind comparison performed eight comparison possible instruction vectors compared comparisons evaluate true set corresponding bits destination 1 false comparisons sets bits 0 result used directly vpcmov instruction vectorized conditional move vpcmov works bitwise variant blend instructions sse4 bit selector 1 selects bit first source 0 selects second source used together xop vector comparison instructions used implement vectorized ternary move second input destination conditional move cmov shift instructions differ sse2 shift unit different amount using vector register interpreted packed signed integers sign indicates direction shift rotate positive values causing left shift negative right shift intel specified different incompatible set variable vector shift instructions avx2 vpperm single instruction combines ssse3 instruction palignr pshufb adds compare altivec instruction vperm takes three registers input first two source registers third selector register byte selector selects one bytes one two input registers output selector also apply effects selected bytes setting 0 reverse bit order repeating signicating bit effects input addition inverted vpermil2pd vpermil2ps instructions two source versions vpermilpd vpermilps instructions avx means like vpperm select output fields two inputs instructions extracts fractional part floating point part would lost conversion integer
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Computer architecture
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directory information tree directory information tree dit data represented hierarchical tree-like structure consisting distinguished names dns directory service entries x.500 protocols lightweight directory access protocol ldap use directory information trees fundamental data structure typically x.500 ldap deployment single organization directory information tree consists two parts top level directory information tree frequently represent political geographic divisions original assumption x.500 directory servers would interconnected form single global namespace entries top level tree corresponded countries identified iso 3166 two letter country code entries subordinate country entry would correspond states provinces national organizations naming system particular country determined country national standards body telecommunications provider limitation original directory information tree structure assumption applications searching entry particular organization would navigate directory tree first browsing particular country organization based region organization based locate entry organization search within organization entry question desire support searching broadly individual person particulars person location organization known led experiments directory deployment interconnection common indexing protocol today ldap deployments particular active directory deployments interconnected single global naming space use national country codes basis naming instead deployments follow directory structure top level mirrors domain name system described rfc 2247 example entry organization domain name example.com would distinguished name dc=example dc=com entries organization directory information tree would contain distinguished name suffix elements organization represented directory e.g. people roles devices dit may modeled variety techniques determining factors include early deployments x.500 within corporations institutions entries representing employees organizations often used dit structure mirrored organizational structure organizational unit entries corresponding departments divisions organization relative distinguished names entries employees often formed common names individual employees example dn early x.500/ldap deployment might cn=joe bloggs ou=marketing ou=operations o=example corporation st=ca c=us disadvantage approach organizational structure changed employees change legal name require moving renaming entries directory adds complexity overhead also upset applications designed deal gracefully moves today many large deployments x.500 ldap use single flat namespace entries choose name entries individuals based relative distinguished name organizationally-assigned identifier username employee number today dn might resemble uid=00003 ou=people dc=example dc=com advantage structure entries need moved even employees change name transferred different departments changes effected attribute modification applications may using dn unique identifier e.g database need touched
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Internet protocols
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core animation core animation graphics compositing framework used macos mac os x leopard later ios watchos tvos produce animated user interfaces core animation provides way developers produce animated user interfaces via implicit animation model well explicit model developer specifies original final states object core animation handles interpolation allows animated interfaces created relative ease specific code animation required developer core animation animate visual element provides unified way accessing core image core video quartz technologies core animation rendering accelerated graphics processor gpu animated sequences execute thread independent main run loop allowing application processing occur animation progress way application performance affected animations stopped reversed retargeted progress core animation first appeared mac os x leopard actually first emerged iphone software team shown publicly first time august 7 2006 wwdc 2006 macworld expo 2007 apple announced iphone runs specially adapted version os x uses core animation
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Operating systems
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ascend ascend open source mathematical modelling chemical process modelling system developed carnegie mellon university since late 1978 ascend acronym stands advanced system computations engineering design main uses field chemical process modelling although capabilities general ascend includes nonlinear algebraic solvers differential/algebraic equation solvers nonlinear optimization modelling multi-region 'conditional models matrix operations supported efficient sparse matrix solver called mtx ascend differs earlier modelling systems separates solving strategy model building domain experts people writing models computational engineers people writing solver code work separately developing ascend together number early modelling tools architecture helped inspire newer languages modelica recognised flexible use variables parameters always treats solvable desired software remains active open-source software project part google summer code programme 2009 2010 2011 2012 2013 python software foundation accepted 2015 programme well
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Programming language topics
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memory corruption memory corruption occurs computer program contents memory location modified due programmatic behavior exceeds intention original programmer program/language constructs termed violating memory safety likely cause memory corruption programming error corrupted memory contents used later program leads either program crash strange bizarre program behavior nearly 10 application crashes windows systems due heap corruption modern programming languages like c c++ powerful features explicit memory management pointer arithmetic features designed developing efficient applications system software however using features incorrectly may lead memory corruption errors memory corruption one intractable class programming errors two reasons memory corruption errors broadly classified four categories many memory debuggers purify valgrind insure++ parasoft c/c++test addresssanitizer available detect memory corruption errors
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Computer security
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hacker crackdown hacker crackdown law disorder electronic frontier work nonfiction bruce sterling first published 1992 book discusses watershed events hacker subculture early 1990s notable topic covered operation sundevil events surrounding 1987–1990 war legion doom network raid steve jackson games trial knight lightning one original journalists phrack subsequent formation electronic frontier foundation book also profiles likes emmanuel goldstein publisher former assistant attorney general arizona gail thackeray fletc instructor carlton fitzpatrick mitch kapor john perry barlow 1994 sterling released book internet new afterword though published 1992 released freeware electronic book 1994 book offers unique colorful portrait nature cyberspace early 1990s nature computer crime time events sterling discusses occur cusp mass popularity internet arguably achieved critical mass late 1994 also encapsulates moment information age revolution cyberspace morphed realm telephone modems bbs internet world wide web cory doctorow voiced unabridged podcast book said inspired politically artistically socially
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Computer security
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microsoft xna microsoft xna recursive acronym xna acronymed freeware set tools managed runtime environment provided microsoft facilitates video game development management xna based .net framework versions run windows nt windows phone xbox 360 xna content built xna game studio played using xna framework windows games published native executables xbox 360 windows phone zune many respects xna thought .net analog microsoft better known game development system directx aimed developers primarily interested writing lightweight games run variety microsoft platforms xna basic platform xbox live indie games xna toolset announced march 24 2004 game developers conference san jose california first community technology preview xna build released march 14 2006 xna game studio 2.0 released december 2007 followed xna game studio 3.0 october 30 2008 xna game studio 4.0 released september 16 2010 along windows phone development tools according email sent 31 january 2013 xna longer developed supported new metro interface layers windows 8 windows rt platform open source cross platform version microsoft xna 4 application programming interface called monogame developed crossplatform reimplementation xna api called fna exists well microsoft xna framework based native implementation .net compact framework 2.0 xbox 360 development .net framework 2.0 windows includes extensive set class libraries specific game development promote maximum code reuse across target platforms framework runs version common language runtime optimized gaming provide managed execution environment runtime available windows xp windows vista windows 7 windows phone xbox 360 since xna games written runtime run platform supports xna framework minimal modification games run framework technically written .net-compliant language c xna game studio express ide versions visual studio 2008 2010 xna 4.0 officially supported support visual basic .net added 2011 xna framework encapsulates low-level technological details involved coding game making sure framework takes care difference platforms games ported one compatible platform another thereby allowing game developers focus content gaming experience xna framework integrates number tools cross-platform audio creation tool xact aid content creation xna framework provides support 2d 3d game creation allows use xbox 360 controllers vibrations xna framework games target xbox 360 platform could distributed members microsoft xna creator club/app hub carried 99/year subscription fee desktop applications distributed free charge microsoft current licensing xna build set game asset pipeline management tools help defining maintaining debugging optimizing game asset pipeline individual game development efforts game asset pipeline describes process game content textures 3d models modified form suitable use gaming engine xna build helps identify pipeline dependencies also provides api access enable processing dependency data dependency data analyzed help reduce size game finding content actually used example xna build analysis revealed 40 textures shipped mechcommander 2 unused could omitted xna game studio programming environment development games five revisions released far 2015 new versions developed xna game studio express first version released august 30 2006 intended students hobbyists independent homebrew game developers available free download express provides basic starter kits rapid development specific genres games platform games real-time strategy first-person shooters developers could create windows games free xna framework run games xbox 360 pay annual fee us 99 four-month fee us 49 admission microsoft xna creator club update xna developers could compile xbox 360 binaries share microsoft xna creator club members xna game studio 2.0 released december 13 2007 xna game studio 2.0 features ability used versions visual studio 2005 including free visual c 2005 express edition networking api using xbox live windows xbox 360 better device handling xna game studio 3.0 visual studio 2008 free visual c 2008 express edition allows production games targeting zune platform adds xbox live community support released october 30 2008 supported c 3.0 linq versions visual studio 2008 xna game studio 4.0 released september 16 2010 added support windows phone platform including 3d hardware acceleration framework hardware profiles configurable effects built-in state objects graphics device scalars orientation cross-platform multi-touch input microphone input buffered audio playback visual studio 2010 integration xna game studio 4.0 refresh released 6 october 2011 added support windows phone 7.5 mango visual basic xna framework content pipeline set tools allows visual studio xna studio act key design point around organizing consuming 3d content formerly known xna game studio professional xdk extensions add-on xna game studio requires microsoft xbox 360 development kit available licensed xbox developers extensions include additional managed apis achievements leaderboards features reserved licensed game titles titles developed using xdk extensions include winners microsoft dream.build.play competition among others heavily publicized microsoft xna framework 2.0 eula specifically prohibits distribution commercial networked games connect xbox live and/or games windows live absence specific agreement signed developer microsoft means xna game studio still used develop commercial games programs windows platform although microsoft networking support code xbox/windows live used self-developed network code still used inside developer xna project games created using xna game studio may distributed via windows phone marketplace formerly via xbox live indie games software may also used create commercial games target windows dream build play annual global 75,000 microsoft contest promoting microsoft xna eventually xbox live indie games although predated contest first announced 2006 first opened january 2007 many winners notable developers indie game community xbox 360 games written xna game studio could submitted app hub premium membership required us 99/year games submitted app hub subjected peer review creators game passed review would listed xbox live marketplace creators could set price 80 240 400 points game creator paid 70 total revenue game sales baseline microsoft originally planned take additional percentage revenue provided additional marketing game policy rescinded march 2009 leaving flat rate intact regardless promotion microsoft also distributed free year premium app hub subscription educational establishments dreamspark program msdnaa accounts allowed students develop games xbox 360 developers still needed premium xbox live account submit game marketplace project called mono.xna formed port xna open source cross-platform mono framework codebase mono.xna silversprite new project called monogame formed port xna several mobile devices version 3.0.1 released march 3 2013 support stable ios android including ouya macos linux metro windows 8 windows rt windows phone 8 well playstation mobile 2d playstation mobile 3d raspberry pi development currently progress fna game porter ethan lee full-featured open source reimplementation xna forked monogame used many games seen goal fna preserve xna game library reimplementing xna open source project called grommet contains limited port embedded devices using .net micro framework project called anx available implements version xna using sharpdx stack support linux macos playstation vita progress well using anx developers able write games using code similar xna still considered metro application windows 8
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Operating systems
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transient execution cpu vulnerabilities transient execution cpu vulnerabilities vulnerabilities computer system speculative execution optimization implemented microprocessor exploited leak secret data unauthorized party classic example spectre since january 2018 many different vulnerabilities identified modern computers highly parallel devices composed components different performance characteristics operation branch yet performed earlier slow operation memory read yet completed microprocessor may attempt predict result earlier operation execute later operation speculatively acting prediction correct prediction may based recent behavior system earlier slower operation completes microprocessor determines whether prediction correct incorrect correct execution proceeds uninterrupted incorrect microprocessor rolls back speculatively executed operations repeats original instruction real result slow operation terms directly visible behavior computer speculatively executed code never happened however speculative execution may affect state certain components microprocessor cache effect may discovered careful monitoring timing subsequent operations attacker arrange speculatively executed code may directly written attacker may suitable gadget found targeted system operates secret data unauthorized access different effect cache different values secret data may able discover value secret data starting 2017 multiple examples vulnerabilities identified publication starting early 2018 hardware mitigations impose close zero performance loss firmware and/or os mitigations might incur quite significant performance loss depending workload 8th generation coffee lake architecture table also applies wide range previously released intel cpus limited architectures based intel core pentium 4 intel atom starting silvermont vulnerabilities associated cpu speculative execution
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Computer security
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advanced comprehensive operating system advanced comprehensive operating system acos family mainframe computer operating systems developed nec japanese market consists three systems based general comprehensive operating system family developed general electric honeywell bull two systems acos-2 based gcos 4 acos-4 based gcos 7 still sold although acos-4 active development acos-6 based gcos 8 obsolete high-end mainframe platform ceased active development early 2000s late september 2012 nec announced return ia-64 previous noah line proprietary mainframe processors acos-4 produced quad-core variant 40 nm called noah-6 acos-2 runs intel xeon servers
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Operating systems
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dokan library dokan library software interface windows brings ability create virtual file system achieved running file system code user space dokan kernel driver translates request windows kernel offers compatibility fuse file system using wrapper built cygwin mingw dokan free software originally released terms lgpl mit dokan library project originally created maintained hiroki asakawa 2007 2011 maintained 2011 2014 community different fork since 2014 project actively maintained adrien j. maxime c. fork dokany code signed company islog dokan particularly useful writing virtual file system without requiring windows kernel knowledge gives ability mount virtual hard drive contains whatever developer wants show absolutely virtual using memory like ram disk show remote data like ftp ssh samba databases local storage listed read written deleted
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Computer file systems
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multiseat configuration multiseat multi-station multiterminal configuration single computer supports multiple independent local users time seat consists hardware devices assigned specific workplace one user sits interacts computer consists least one graphics device graphics card output e.g hdmi/vga/displayport port attached monitor/video projector output keyboard mouse input also include video cameras sound cards since 1960s computers shared users especially early days computing computers extremely expensive usual paradigm central mainframe computer connected numerous terminals advent personal computing paradigm largely replaced personal computers one computer per user multiseat setups return multiuser paradigm based around pc supports number zero-clients usually consisting terminal per user screen keyboard mouse multiseat setups great schools libraries family computers situations multiseat also cost-effective necessary buy separate motherboards microprocessors ram hard disks components user example buying one high speed cpu usually costs less buying several slower cpus 1970s commonplace connect multiple computer terminals single mainframe computer even graphical terminals early terminals connected rs-232 type serial connections either directly modems advent internet protocol based networking became possible multiple users log host using telnet – graphic environment – x window system server systems would retain physically secure root console system administration direct access host machine support multiple consoles pc running x interface implemented 2001 miguel freitas using linux operating system x11 graphical system time maintained xfree86 done using patch display server execute several instances x time one captures specific mouse keyboard events graphical content method received name multiseat multiterminal 2002 canadian company userful corporation released userful multiplier multiseat linux software solution enables 10 users simultaneously share one computer earlier worked kernel-based approach multi-station platform computer abandoned idea due problem multiple video card support solutions appeared 2003 svetoslav slavtchev aivils stoss james simmons worked evdev faketty approach modifying kernel linux letting one user independently use machine time linux console project also proposed idea use multiple independent consoles multiple independent keyboards mice project called backstreet ruby backstreet ruby kernel patch linux kernel back port linux-2.4 ruby kernel tree aim linux console developers enhance reorganize input console framebuffer subsystems linux kernel work independent allow multi-desktop operation backstreet ruby idea never finished 2005 c3sl team center scientific computing free software federal university parana brazil created solution based nested display servers xnest xephyr solution nested display server runs screen host display server e.g xorg modification nested servers let one exclusively acquire mouse keyboard 2008 c3sl group released multiseat display manager mdm ease process installation configuration multiseat box group also 2008 conceived live-cd test purposes automatic multiseat usb docking stations feature fedora 17 monitor need connected graphics output video card example make four-head four users would require four monitors four keyboards four mice two dual one quad output video card usb keyboards mice typically recommended instead ps/2 connections connected usb hub additional devices peripherals cameras flash storage drives card readers touch screens could also assigned seat alternative multiple physical video cards connections displaylink usb vt system linux kernel dates back 1993 understand concept multiple seats kmscon systemd-consoled different solutions set multiseat others constantly developed x.org foundation maintains wiki page latest news concerning solutions currently pointed solutions x.org wiki solutions using either multiple xephyr servers deprecated evdev support host xorg run several instances xorg using multiple video devices quite easy configure popular distributions ubuntu provide multiseat environments documented ubuntu multiseatx wiki page multi-seat display manager automseat tool open source tool helps automatize process installation configuration users want try multiseat encouraged try tool avoid old hard way set howtos stated foundation wiki page hand mdm suffers lack updates releases beyond initial announcement another open source tool aims help simplify creation multiseat mainly ubuntu distribution bicefalo wizard userful offers commercially supported multiseat linux solution called userful multiplier enables 10 users simultaneously share one computer works graphics cards supported x.org/xfree86 well usb multiseat devices available 64-bit 32-bit packages rpm deb formats tested major distributions including debian fedora mandriva linux sled suse ubuntu free two-user version userful multiplier software personal trial use available website windows 2000 xp vista operating systems several commercial products implement multiseat configurations two seats operating system designed specifically multiseat setups entitled windows multipoint server announced february 24 2010 uses remote desktop terminal services technologies windows server 2008 r2 provide multiseat functionality functionality incorporated windows server proper windows server 2016 new server role entitled multipoint services server role removed windows server 2019 owing microsoft ceasing development service 2018 instead relying operating system support multiseat configuration hypervisor configured run multiple virtual machines configured interface one connected seat i/o virtualization methods input devices attached virtual machines usb redirection entire gpus attached intel vt-d youtube channel linustechtips demonstrated virtualization-based 2-seat 7-seat systems unraid host operating system seat exclusive control one windows guest operating systems running host dedicated high-end graphics card guest takes full advantage via use vt-d making system capable hosting demanding video game sessions full quality simultaneously seats february 2009 brazil ministry education committed deploy 350,000 linux-based multiseat computing stations 45,000 rural urban schools across country chosen companies implement project canadian multiseat linux software company userful corporation brazilian partner thinnetworks one multiterminal successful cases happening paraná digital project creating multiterminal laboratories 2000 public schools state paraná brazil 1.5 million users benefit 40,000 terminals project finished laboratories four-head multiterminals running debian cost hardware 50 less normal price absolutely cost software project developer c3sl center scientific computing free software since 2008 electrical computer engineering students michigan state university installed multiterminal systems internet access three schools mto wa mbu tanzania purpose project study impact computer systems internet access education system afford educational resources books computer systems run ubuntu 8.04 32-bit utilize open source multiseat display manager created c3sl research eventually used present government officials third world countries effort showcase positive impact cost-effective computing systems schools project sponsored george vickie rock dow chemical company
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Operating systems
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cplink cplink win32/cpllnk.a names microsoft windows shortcut icon vulnerability discovered june 2010 patched 2 august affected windows operating systems vulnerability exploitable windows application display shortcut icons windows explorer browses folder containing malicious shortcut exploit triggered without user interaction regardless shortcut file located june 2010 virusblokada reported detection zero-day attack malware called stuxnet exploited vulnerability install rootkit snooped siemens scada systems wincc pcs 7 according symantec first worm designed reprogram industrial systems spy
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Computer security
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packet analyzer packet analyzer also known packet sniffer computer program piece computer hardware packet capture appliance intercept log traffic passes digital network part network packet capture process intercepting logging traffic data streams flow across network sniffer captures packet needed decodes packet raw data showing values various fields packet analyzes content according appropriate rfc specifications packet analyzer used intercepting traffic wireless networks known wireless analyzer wifi analyzer packet analyzer also referred network analyzer protocol analyzer though terms also meanings wired shared medias networks ethernet token ring fddi networks depending network structure hub switch may possible capture traffic network single machine network modern networks traffic captured using network switch so-called monitoring port mirrors packets pass designated ports switch network tap even reliable solution use monitoring port since taps less likely drop packets high traffic load wireless lans traffic captured one channel time using multiple adapters several channels simultaneously wired broadcast wireless lans capture unicast traffic machines network adapter capturing traffic must promiscuous mode wireless lans even adapter promiscuous mode packets service set adapter configured usually ignored see packets adapter must monitor mode special provisions required capture multicast traffic multicast group packet analyzer already monitoring broadcast traffic traffic captured either entire contents packets recorded headers recorded recording headers reduces storage requirements avoids legal issues yet often provides sufficient information diagnose problems captured information decoded raw digital form human-readable format lets users easily review exchanged information protocol analyzers vary abilities display analyze data protocol analyzers also generate traffic thus act reference device act protocol testers testers generate protocol-correct traffic functional testing may also ability deliberately introduce errors test dut ability handle errors protocol analyzers also hardware-based either probe format increasingly common combined disk array devices record packets slice packet disk array allows historical forensic analysis packets without users recreate fault packet sniffers packet capture used fulfill warrant law enforcement agency wiretap network traffic generated individual internet service providers voip providers united states must comply communications assistance law enforcement act regulations using packet capture storage telecommunications carriers provide legally required secure separate access targeted network traffic able use device internal security purposes collecting data carrier system without warrant illegal due laws interception using end-to-end encryption communications kept confidential telecommunication carriers legal authorities
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Computer security
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remote procedure call distributed computing remote procedure call rpc computer program causes procedure subroutine execute different address space commonly another computer shared network coded normal local procedure call without programmer explicitly coding details remote interaction programmer writes essentially code whether subroutine local executing program remote form client–server interaction caller client executor server typically implemented via request–response message-passing system object-oriented programming paradigm rpc calls represented remote method invocation rmi rpc model implies level location transparency namely calling procedures largely whether local remote usually identical local calls distinguished remote calls remote calls usually orders magnitude slower less reliable local calls distinguishing important rpcs form inter-process communication ipc different processes different address spaces host machine distinct virtual address spaces even though physical address space different hosts physical address space different many different often incompatible technologies used implement concept response–request protocols date early distributed computing late 1960s theoretical proposals remote procedure calls model network operations date 1970s practical implementations date early 1980s bruce jay nelson generally credited coining term remote procedure call 1981 remote procedure calls used modern operating systems trace roots back rc 4000 multiprogramming system used request-response communication protocol process synchronization idea treating network operations remote procedure calls goes back least 1970s early arpanet documents 1978 per brinch hansen proposed distributed processes language distributed computing based external requests consisting procedure calls processes one earliest practical implementations 1982 brian randell colleagues newcastle connection unix machines soon followed lupine andrew birrell bruce nelson cedar environment xerox parc lupine automatically generated stubs providing type-safe bindings used efficient protocol communication one first business uses rpc xerox name courier 1981 first popular implementation rpc unix sun rpc called onc rpc used basis network file system nfs 1990s popularity object-oriented programming alternative model remote method invocation rmi widely implemented common object request broker architecture corba 1991 java remote method invocation rmis turn fell popularity rise internet particularly 2000s rpc request–response protocol rpc initiated client sends request message known remote server execute specified procedure supplied parameters remote server sends response client application continues process server processing call client blocked waits server finished processing resuming execution unless client sends asynchronous request server xmlhttprequest many variations subtleties various implementations resulting variety different incompatible rpc protocols important difference remote procedure calls local calls remote calls fail unpredictable network problems also callers generally must deal failures without knowing whether remote procedure actually invoked idempotent procedures additional effects called easily handled enough difficulties remain code call remote procedures often confined carefully written low-level subsystems let different clients access servers number standardized rpc systems created use interface description language idl let various platforms call rpc idl files used generate code interface client servers notable rpc implementations analogues include
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Distributed computing architecture
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network access protection network access protection nap microsoft technology controlling network access computer based health nap system administrators organization define policies system health requirements examples system health requirements whether computer recent operating system updates installed whether computer latest version anti-virus software signature whether computer host-based firewall installed enabled computers nap client health status evaluated upon establishing network connection nap restrict deny network access computers compliance defined health requirements nap deprecated windows server 2012 r2 removed windows server 2016 network access protection client agent makes possible clients support nap evaluate software updates statement health nap clients computers report system health nap enforcement point nap enforcement point computer device evaluate nap client ’ health optionally restrict network communications nap enforcement points ieee 802.1x-capable switches vpn servers dhcp servers health registration authorities hras run windows server 2008 later nap health policy server computer running network policy server nps service windows server 2008 later stores health requirement policies provides health evaluation nap clients health requirement policies configured administrators define criteria clients must meet allowed undeterred connection criteria may include version operating system personal firewall up-to-date antivirus program nap-capable client computer contacts nap enforcement point submits current health state nap enforcement point sends nap client ’ health state nap health policy server evaluation using radius protocol nap health policy server also act radius-based authentication server nap client nap health policy server use health requirement server validate health state nap client determine current version software updates need installed nap client example health requirement server might track latest version antivirus signature file nap enforcement point hra obtains health certificates certification authority nap clients determined compliant health requirements nap client determined noncompliant health requirements optionally placed restricted network restricted network logical subset intranet contains resources allow noncompliant nap client correct system health servers contain system health components updates known remediation servers noncompliant nap client restricted network access remediation servers install necessary components updates remediation complete nap client perform new health evaluation conjunction new request network access communication nap client ships windows vista windows 7 windows 8 windows 8.1 windows 10 limited nap client also included windows xp service pack 3 mmc snap-in support authip-based ipsec enforcement managed via command-line tool called netsh ipsec enforcement ike-based microsoft partners provide nap clients operating systems mac os x linux turn network access protection windows 8 simultaneously hold x key windows key computer keyboard mine bottom row 3rd left use arrow select search touch enter key search defaults apps type services click scroll network access protection agent service click status column say running right click left click start status column say running close services window
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Operating systems
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nokia e6 nokia e6-00 smartphone running symbian^3 operating system supersedes nokia e72 new symbian business mobility solution nokia following announcement 12 april 2011 day nokia x7-00 shipped new symbian anna version symbian^3 originally retailed 340 euros taxes smartphone notable backlit 4-rows qwerty keyboard touch screen input methods long battery life talktime 7.5 14.8 h standby 28 31 days out-of-the-box access microsoft exchange activesync microsoft communicator mobile microsoft sharepoint high pixel density vga display 326ppi like predecessors nokia e71/e72 nokia e6-00 integrates stainless steel glass design back removable cover raised panel back camera dual led flash loud speaker contour front made stainless steel front phone except qwerty keyboard short cut buttons navikey covered corning gorilla glass casing three color options black silver white e6 would also last symbian-based device qwerty keyboard later qwerty devices would series 40 asha line nokia asha 302 2012 bears strong design similarities e6 october 2012 vertu released constellation quest blue based e6 predecessor e6-00 eseries consisting business-oriented smartphones nokia e72 shipped november 2009 e71 e72 received mostly praises press worth noting nokia released e7 landscape qwerty slider smartphone eseries based symbian^3 shipped february 2011 first hints nokia e6-00 developed came early january 2011 nokia xml pictures picasa album pictures taken device various information could retrieved xml 8 mp camera vga display qwerty keyboard device officially announced mobile world congress held barcelona 14–17 february 2011 various pictures videos nokia e6-00 leaked months february march officially announced special event named discover symbian 12 april 2011 along nokia x7 latest update symbian software expected released q2 2011 europe price €340 taxes subsidies q3 2011 north america may 2011 nokia e6 became available nokia deutschland online shop preorder price €429 nokia e6-00 powered processor found contemporary symbian devices nokia n8 e7 c7 nokia e series arm11 clocked 680 mhz broadcom bcm2727 gpu supports openvg1.1 opengl es 2.0 support nokia e6-00 62.5 mm diagonally capacitive touchscreen resolution 640 × 480 pixel vga 326 ppi according nokia capable displaying 16.7m colours pixel density highest among smartphones launched time launch nokia lumia 920 screen brightness e6-00 double brightness e72 measured candelas proximity sensor deactivates display touchscreen device brought near face call nokia e6 also understands pictbridge protocol possible directly print phone printer without using computer handle data transfer optical navi key e72 replaced navi key e6-00 also ambient light sensor adjusts display brightness activates backlit 4-row keyboard 3-axis accelerometer present switch display portrait mode device turned sideways however take pictures portrait show right way photo gallery device autonomous gps optional a-gps functionality wi-fi network positioning cell-id comes pre-loaded ovi maps application ovi maps symbian^3 provides free lifetime turn turn voice guided car pedestrian navigation map already downloaded device ovi maps require active data connection work stand-alone gps navigator services example google maps data connection required 8-megapixel 3264 x 2448 px back camera extended depth field feature autofocus dual led flash 2x digital zoom 3x video mode offers high definition 720p 16:9 aspect ratio video recording 25 frame/s 4:3 aspect ratio 0.3-megapixel front camera capable video recording 176 x 144 px 15 frame/s video calling nokia e6 loudspeaker two microphones microphone front device collects voices user another microphone back device collects environmental noise active noise cancellation makes user voice noisy environment sound clearer person end line noise cancellation available using loudspeaker headset front device qwerty keyboard call creation call termination keys home menu calendar contact email shortcut keys short long press features 5-way scrolling navi key top power/lock button right hand side lock/unlock slider also turn torch dual led flash camera button three keys 1 volume 2 volume 3 middle key activating voice commands long press voice recorder short press device locked pressing navi also bring menu allow unlock nokia e6-00 touch screen qwerty keyboard comes variety 24 language versions including arabic thai russian chinese e6-00 microphone loudspeaker located back device 3.5 mm four-contact audio jack simultaneously provides stereo audio output either microphone input video output pal ntsc tv possible using nokia video connectivity cable included upon purchase standard 3.5 mm audio jack rca cable high-speed usb 2.0 usb micro-b connector provided data synchronization mass storage mode client battery charging nokia e6-00 supports usb on-the-go 1.3 ability act usb host using nokia adapter cable usb otg ca-157 included upon purchase built-in bluetooth v3 supports wireless earpieces headphones hsp profile nokia e6-00 also capable stereo audio output a2dp profile built-in car hands-free kits also supported hfp profile file transfer supported ftp along opp profile sending/receiving objects possible remote control device avrcp profile dun profile permits access internet laptop dialing mobile phone wirelessly tethering profiles also supported bip gap gavdp goep hsp pbap sap sdp spp device 87.5-108 mhz 76-90 mhz japan fm receiver rds support wi-fi b/g/n connectivity single band support wep wpa wpa2 aes/tkip security protocols bp-4l 1500 mah li-ion battery performance provided nokia 14.8h talk time 681h standby 9h video playback 4.7h video recording 75h music play back nokia e6-00 8 gb internal storage expanded microsdhc card 32 gb size 1 gb rom 350 mb available user install applications new users nokia e6 experienced problems notification led placed d-pad navigation key previous models e71 e72 however apparent nokia allowed sufficient space d-pad key front face light visible nokia acknowledged problem indicated whether fix possible software adjusting brightness component one solution done aniket patil aniketroxx redirect notification light red mute key used many people alternative d-pad fix solution also helped user see light without opening e6 cover revised nokia e6 hardware change resolve notification light issue started shipping 22 october 2011 many users nokia e6 reported vibration alert strong enough along nokia x7 e6-00 shipped updated symbian^3 software user experience update nicknamed anna offers amongst others preinstalled applications nokia e6-00 include joikuspot premium mobile wifi hotspot world traveler f-secure mobile security quickoffice stock os version symbian anna specially adapted e6 february 2012 nokia belle update heavily criticised failure meet special demands e6 met original stock firmware august 2012 nokia belle refresh made available due vga 640 x 480 resolution compared nhd 640 x 360 symbian^3 devices application may incompatible e6-00 designed nhd display example nokia guidelines stipulate user interface elements touch screen accept button virtual numpad etc ... least 7mm x 7mm high pixel density nokia e6-00 means elements need proportionately larger pixels compared recent symbian^3 devices nokia e6-00 two extra homescreens bringing total 5 homescreens give users opportunity customization devices smaller displays accommodating 3 widgets per homescreen nokia e6 wifi coverage full spectrum channels 1-13 crowded 2.4 ghz waveband compared channels 1-11 e63 example support newer 5 ghz wifi frequencies charging led workaround notifications
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Operating systems
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version 7 unix seventh edition unix also called version 7 unix version 7 v7 important early release unix operating system v7 released 1979 last bell laboratories release see widespread distribution commercialization unix corporation early 1980s v7 originally developed digital equipment corporation pdp-11 minicomputers later ported platforms unix versions bell labs designated edition user manual accompanied released 1979 seventh edition preceded sixth edition first version licensed commercial users development research unix line continued eighth edition incorporated development 4.1bsd tenth edition bell labs researchers concentrated developing plan 9 v7 first readily portable version unix era minicomputers many architectural variations also beginning market 16-bit microprocessors many ports completed within first years release first sun workstations based motorola 68010 ran v7 port unisoft first version xenix intel 8086 derived v7 onyx systems soon produced zilog z8000 computer running v7 vax port v7 called unix/32v direct ancestor popular 4bsd family unix systems group university wollongong ported v6 interdata 7/32 ported v7 machine well interdata sold port edition vii making first commercial unix offering dec distributed pdp-11 version v7 called v7m modified v7m developed dec original unix engineering group ueg contained many enhancements kernel pdp-11 line computers including significantly improved hardware error recovery many additional device drivers ueg evolved group later developed ultrix due power yet elegant simplicity many old-time unix users remember v7 pinnacle unix development dubbed last true unix improvement preceding following unices time release though greatly extended feature set came expense decrease performance compared v6 corrected largely user community number system calls version 7 around 50 later unix unix-like systems continued add many 2002 caldera international released v7 foss permissive bsd-like software license bootable images v7 still downloaded today run modern hosts using pdp-11 emulators simh x86 port developed nordier associates paul allen maintained several publicly accessible historic computer systems including pdp-11/70 running unix version 7 many new features introduced version 7 portable c compiler pcc provided along earlier pdp-11-specific c compiler ritchie first appeared research unix lineage version 7 although early versions already picked pwb/unix feature survive long second way besides pipes inter-process communication multiplexed files process could create special type file codice_1 system call processes could open file get channel denoted file descriptor could used communicate process created multiplexed file mpx files considered experimental enabled default kernel disappeared later versions offered sockets bsd cb unix ipc facilities system v instead although mpx files still present 4.1bsd
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Operating systems
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cell software development software development cell microprocessor involves mixture conventional development practices powerpc-compatible ppu core novel software development challenges regard functionally reduced spu coprocessors open source software-based strategy adopted accelerate development cell ecosystem provide environment develop cell applications including gcc-based cell compiler binutils port linux operating system octopiler ibm prototype compiler allow software developers write code cell processors vmx vector multimedia extensions technology conceptually similar vector model provided spu processors many significant differences vmx java mode conforms java language specification 1 subset default ieee standard extended include ieee c9x compliance java standard falls silent typical implementation non-java mode converts denormal values zero java mode traps emulator processor encounters value ibm ppe vector/simd manual define operations double-precision floating point though ibm published material implying certain double-precision performance numbers associated cell ppe vmx technology compilers cell provide intrinsics expose useful spu instructions c c++ instructions differ type operand ai ah ahi fa dfa addition typically represented single c/c++ intrinsic selects proper instruction based type operand great body code developed ibm power processors could potentially adapted recompiled run spu code base includes vmx code runs powerpc version apple mac os x better known altivec depending many vmx specific features involved adaptation involved range anywhere straightforward onerous completely impractical important workloads spu generally map quite well cases possible port existing vmx code directly vmx code highly generic makes assumptions execution environment translation relatively straightforward two processors specify different binary code format recompilation required minimum even instructions exist behaviors instruction names must mapped well ibm provides compiler intrinsics take care mapping transparently part development toolkit many cases however directly equivalent instruction exist workaround might obvious might example saturation behavior required spu coded adding additional spu instructions accomplish loss efficiency extreme java floating-point semantics required almost impossible achieve spu processor achieve computation spu might require entirely different algorithm written scratch important conceptual similarity vmx spu architecture supporting vectorization model reason algorithms adapted altivec usually adapt successfully spu architecture well transferring data local stores different spus large performance cost local stores individual spus exploited using variety strategies applications high locality dense matrix computations represent ideal workload class local stores cell streaming computations efficiently accommodated using software pipelining memory block transfers using multi-buffering strategy software cache offers solution random accesses sophisticated applications use multiple strategies different data types
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Computer architecture
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wizardry iii legacy llylgamyn wizardry iii legacy llylgamyn originally known wizardry legacy llylgamyn third scenario third scenario wizardry series role-playing video games published 1983 sir-tech software inc city llylgamyn threatened violent forces nature earthquakes volcanic rumblings endanger everyone seeking dragon l'kbreth city saved legacy llylgamyn another six level dungeon crawl although dungeon volcano party journeys upwards rather downwards gameplay spells identical first two scenarios parties six characters could adventure one time characters imported either however since game set years later characters actually descendants original characters kept name class could select new alignment class permitting reset level one alignment made significant—certain areas game accessible appropriately aligned good evil parties first level accessible parties good neutral evil note evil good characters unwilling adventure together party always either good least one good character rest neutral evil least one evil character rest neutral neutral characters neutral second fourth levels could accessed parties evil characters—good neutral parties third fifth levels could accessed parties good characters—evil neutral parties sixth level could accessed party least one good one evil character—no neutral parties neutral characters could travel areas last level theoretically could get game party six characters neutral practically speaking players forced build 6 characters party could function long term without cleric good evil wizard good evil lord good healing effect prolonging gameplay wizardry iii first adventure game window manager released first games apple macintosh philip l. wing reviewed legacy llylgamyn space gamer 72 wing commented wizardry iii legacy llylgamyn best scenario series yet solid story riddles appropriate scenario game recommended original characters solid stats first two games required softline 1983 praised llylgamyn stating n't written composed ... dungeon feels like living breathing entity concluding game best wizardry yet 1984 readers named game second most-popular apple program 1983 behind lode runner computer gaming world scorpia 1991 1993 called game wizardry bells whistles added stated novelty playing two separate groups adventurers one good one evil little distinguish previous two games
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Computer architecture
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rfpolicy rfpolicy states method contacting vendors security vulnerabilities found products originally written hacker security consultant rain forest puppy policy gives vendor five working days respond reporter bug vendor fails contact reporter five days issue recommended disclosed general community reporter help vendor reproduce bug work fix reporter delay notifying general community bug vendor provides feasible reasons requiring vendor fails respond shuts communication reporter problem five working days reporter disclose issue general community issuing alert fix vendor give reporter proper credits reporting bug
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Computer security
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metro design language microsoft design language mdl design language created microsoft design language focused typography simplified icons absence clutter increased content chrome ratio content chrome basic geometric shapes early examples mdl principles found encarta 95 msn 2.0 design language evolved windows media center zune formally introduced metro unveiling windows phone 7 since incorporated several company products including xbox 360 system software xbox one windows 8 windows phone outlook.com microsoft design language title became official microsoft representative qi lu referred modern ui design language mixx conference keynote speech according microsoft metro always codename never meant final product news websites attribute change trademark issues microsoft design language 2 mdl2 developed alongside windows 10 later fluent design language extended design language based design principles classic swiss graphic design early glimpses style could seen windows media center windows xp media center edition favored text primary form navigation interface carried later iterations media center 2006 zune refreshed interface using principles microsoft designers decided redesign interface focus clean typography less ui chrome principles new zune ui carried windows phone much drawn windows 8 zune desktop client also redesigned emphasis typography clean design different zune previous portable media center based ui flat colored live tiles introduced design language early windows phones studies microsoft design language 2 mdl2 developed alongside windows 10 version introduced new set widgets including date pickers toggles switches reduced border thicknesses user interface elements microsoft design team cites inspiration design language signs commonly found public transport systems design language places emphasis good typography large text catches eye microsoft sees design language sleek quick modern refresh icon-based interfaces windows android ios instances use fonts based segoe font family designed steve matteson agfa monotype licensed microsoft zune microsoft created custom version called zegoe ui windows phone microsoft created segoe wp font family fonts mostly differ minor details obvious differences segoe ui segoe wp apparent respective numerical characters segoe ui font windows 8 obvious differences – similar segoe wp characters notable typographic changes included 1 2 4 5 7 8 q. microsoft designed design language specifically consolidate groups common tasks speed usage achieves excluding superfluous graphics instead relying actual content function main ui resulting interfaces favor larger hubs smaller buttons often feature laterally scrolling canvases page titles usually large consequently also take advantage lateral scrolling animation plays large part microsoft recommends consistent acknowledgement transitions user interactions presses swipes form natural animation motion aims give user impression alive responsive ui added sense depth early response language generally positive review zune hd engadget said microsoft continues push towards big big typography providing sophisticated neatly designed layout almost functional attractive cnet complimented design language saying bit daring informal tight sterile icon grids rolodex menus iphone ipod touch idea 2011 ceremony industrial designers society america idsa gave windows phone 7 uses ui gold interactive award people choice award best show award isabel ancona user experience consultant idsa explained windows phone criticism particularly focused use caps text rise internet usage critics compared computer program shouting user journalist lee hutchinson described microsoft use practice macos version onenote terrible claiming cursed insane non-standard application window menus caps ’ much violate os x ’ design conventions take behind shed pour gasoline set fire arrival windows 8 operating system user interface use design language drew generally negative critical responses 25 august 2012 peter bright ars technica reviewed preview release windows 8 dedicating first part review comparison start menu designs used windows 8 windows 7 recounting pros cons peter bright concluded start menu windows 8 dubbed start screen though devoid problems clear winner however concluded windows 8 user interface frustrating various aspects user interface work well together woody leonhard even critical said user standpoint windows 8 failure – awkward mishmash pulls user two directions addition changes start menu windows 8 takes modal approach use full-screen apps steer away reliance icon-based desktop interface however microsoft shifted focus away multitasking business productivity august 2012 verge announced internal memorandum sent developers microsoft employees announcing decision discontinue use term metro discussions important european partner working replacement term technology news outlets ars technica techradar cnet engadget network world mainstream press bits blog new york times company bbc news online published partner mentioned memo could one microsoft retail partners german company metro ag name potential infringe metro trademark microsoft later stated reason de-emphasizing name related current litigation metro internal project codename despite heavily promoted brand public september 2012 microsoft design language adopted official name design style term used microsoft developer network documentation 2012 build conference refer design language related change microsoft dropped use phrase metro-style apps refer mobile apps distributed via windows store
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Operating systems
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dynamicops dynamicops private software company headquartered burlington massachusetts usa backed credit suisse intel capital sierra ventures next world capital dynamicops develops cloud automation management solutions solutions designed help enterprise organizations create scalable private public desktop cloud services days existing technology systems processes acquired vmware 2012 dynamicops origins credit suisse software initially developed inside credit suisse ’ global research development group 2005 help company address operational governance challenges rolling virtualization technology 2008 deployed used software manage thousands virtual machines credit suisse ventures decided form company based technology recruited rich krueger form lead new company—dynamicops dynamicops incorporated january 31 2008 publicly launch later spring—to develop market product leslie muller led development effort credit suisse became founder cto dynamicops company raised total 27m venture funding credit suisse intel capital sierra ventures next world capital july 2012 dynamicops acquired vmware operations virtualization foundational technology dynamicops ’ cloud offerings operations virtualization abstraction layer multiple management systems make cloud infrastructure consumers allows staff apply management layers without layers needing know dynamicops multi-year licensing distribution agreement dell dynamicops software component virtual integrated system solution company technology alliances number companies including amazon web services cisco citrix hp ibm microsoft netapp novell red hat symantec vmware
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Distributed computing architecture
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tempus nova tempus nova denver-based consulting firm specializes migrating large scale on-premises email messaging systems cloud-based g suite founded 2001 tempus nova specializes google enterprise solutions g suite implementations custom application development cloud computing company provides implementation deployment services organizations seeking move on-premises solutions g suite basic business enterprise services include project management technical support training change management continuing support post-deployment custom application development tempus nova works public private enterprises move communications collaboration cloud-based technology tempus nova works google provide services reduce costs companies utilizing cloud 2011 company partnered united states federal government implement cloud-based email system general services administration company also responsible migrating state governments wyoming utah colorado first three u.s. state governments adopt g suite addition partnerships u.s. federal state governments tempus nova worked several major corporations transfer legacy data g suite including retail brand kohl ’ comex group avery dennison denny tempus nova sole developer proprietary interoperability connectivity coexistence migration archiving tools used migrating lotus notes users g suite company provides several enterprise software products used government universities large organizations notable products include tempus nova developed partnerships several organizations solution providers company certified g suite reseller google premier partner google partner advisory board member google cloud transformation partner salesforce reseller ibm premier partner microsoft certified business partner cdw partner exclusive gp strategies partner among others
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Web technology
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apple mail apple mail officially known simply mail email client included apple inc. operating systems macos ios watchos apple mail grew nextmail originally developed next part nextstep operating system apple acquisition next 1997 current version apple mail utilizes smtp message sending pop3 exchange imap message retrieval s/mime end-to-end message encryption also preconfigured work popular email providers yahoo mail aol mail gmail outlook icloud formerly mobileme supports exchange ios features mobile version apple mail added exchange activesync eas support though notoriously missed functionality attaching files reply emails release ios 9 eas supported macos version apple mail app main issue sent messages incorrectly duplicated sent messages folder propagates via sync devices including ios features apple mail include ability configure software receive user email accounts one list ability file emails folders ability search emails ability automatically append signatures outgoing emails also integrates contacts list calendar maps apps apple mail originally developed next nextmail email application nextstep operating system nextmail innovative time supported rich text formatting images voice messaging mime emails also supported plain text tui allow backwards compatibility apple began adapt nextstep become mac os x operating system application went various stages developed beta version codenamed rhapsody various early pre-releases mac os x mail known mailviewer however third developer release mac os x application returned known simply mail apple mail included versions macos including mac os x panther released october 24 2003 integrated apple applications address book ichat ical features remain recent version mail include rules mailboxes junk mail filtering multiple account management mac os x tiger version 10.4 mail version 2 included proprietary single-message-per-file format filename extension .emlx permit indexing spotlight additional features new version also changed ui buttons toolbar whereas previous buttons free-standing defined shapes new buttons featured shapes within lozenge-shaped capsule according many users even apple human interface guidelines time worse usability open-source third-party application reverted icons former shapes available nevertheless apple updated guidelines include capsule-shaped buttons new ui persisted mac os x leopard version 10.5 mail version 3 included personalized stationery handled standard html format addition offered notes to-dos could synced ical well built-in rss reader also introduced imap idle support account inboxes mac os x snow leopard version 10.6 brought microsoft exchange server 2007 support ical address book applications bundled os x 10.6 mac os x lion version 10.7 mail featured redesigned ipad-like user interface full-screen capabilities updated message search interface support microsoft exchange server 2010 yahoo mail via imap also added capability group messages subject similar fashion mail ios 4 bounce function unwanted emails could bounced back sender dropped support exchange push email os x mountain lion version 10.8 mail received vip tagging safari-style inline search words within email message ability sync icloud new sharing features notes split stand-alone application rss reader to-dos discontinued os x mavericks version 10.9 mail ceased support plain-text mime multipart/alternative messages solely retained html rich-text version os x yosemite version 10.10 mail introduced markup inline annotation pdf image files mail drop automatically uploads attachments icloud sends link message instead whole file os x el capitan version 10.11 filter added message list filter various options unread flagged messages attachments conversation display also redesigned various disk space saving optimizations implemented streaming notification support exchange accounts also added support macos new dark mode added mail
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Operating systems
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history berkeley software distribution history berkeley software distribution begins 1970s earliest distributions unix bell labs 1970s included source code operating system allowing researchers universities modify extend unix operating system arrived berkeley 1974 request computer science professor bob fabry program committee symposium operating systems principles unix first presented pdp-11/45 bought run system budgetary reasons machine shared mathematics statistics groups berkeley used rsts unix ran machine eight hours per day sometimes day sometimes night larger pdp-11/70 installed berkeley following year using money ingres database project also 1975 ken thompson took sabbatical bell labs came berkeley visiting professor helped install version 6 unix started working pascal implementation system graduate students chuck haley bill joy improved thompson pascal implemented improved text editor ex universities became interested software berkeley 1977 joy started compiling first berkeley software distribution 1bsd released march 9 1978 1bsd add-on version 6 unix rather complete operating system right thirty copies sent second berkeley software distribution 2bsd released may 1979 included updated versions 1bsd software well two new programs joy persist unix systems day vi text editor visual version ex c shell 75 copies 2bsd sent bill joy feature networking package called berknet developed eric schmidt part master thesis work could connect twenty-six computers provided email file transfer 3bsd see come vax line computers new releases 2bsd pdp-11 still issued distributed usenix example 1982 2.8.1bsd included collection fixes performance problems version 7 unix later releases contained ports changes vax-based releases bsd back pdp-11 architecture 2.9bsd 1983 included code 4.1cbsd first release full os modified v7 unix rather set applications patches recent release 2.11bsd first issued 1992 21st century maintenance updates volunteers continued patch 451 released december 22 2018 vax computer installed berkeley 1978 port unix vax architecture unix/32v take advantage vax virtual memory capabilities kernel 32v largely rewritten berkeley students include virtual memory implementation complete operating system including new kernel ports 2bsd utilities vax utilities 32v released 3bsd end 1979 3bsd also alternatively called virtual vax/unix vmunix virtual memory unix bsd kernel images normally called codice_1 4.4bsd success 3bsd major factor defense advanced research projects agency darpa decision fund berkeley computer systems research group csrg would develop standard unix platform future darpa research vlsi project 4bsd november 1980 offered number enhancements 3bsd notably job control previously released csh delivermail antecedent sendmail reliable signals curses programming library 1985 review bsd releases john quarterman et al wrote 4.1bsd june 1981 response criticisms bsd performance relative dominant vax operating system vms 4.1bsd kernel systematically tuned bill joy could perform well vms several benchmarks release would called 5bsd objections name changed feared confusion unix system v. 4.2bsd august 1983 would take two years implement contained several major overhauls official release came three intermediate versions 4.1a incorporated modified version bbn preliminary tcp/ip implementation 4.1b included new berkeley fast file system implemented marshall kirk mckusick 4.1c interim release last months 4.2bsd development back bell labs 4.1cbsd became basis 8th edition research unix commercially supported version available mtxinu guide design 4.2bsd duane adams darpa formed steering committee consisting bob fabry bill joy sam leffler ucb alan nemeth rob gurwitz bbn dennis ritchie bell labs keith lantz stanford rick rashid carnegie-mellon bert halstead mit dan lynch isi gerald j. popek ucla committee met april 1981 june 1983 apart fast file system several features outside contributors accepted including disk quotas job control sun microsystems provided testing motorola 68000 machines prior release ensuring portability system official 4.2bsd release came august 1983 notable first version released 1982 departure bill joy co-found sun microsystems mike karels marshall kirk mckusick took leadership roles within project point forward lighter note also marked debut bsd daemon mascot drawing john lasseter appeared cover printed manuals distributed usenix 4.3bsd released june 1986 main changes improve performance many new contributions 4.2bsd heavily tuned 4.1bsd code prior release bsd implementation tcp/ip diverged considerably bbn official implementation several months testing darpa determined 4.2bsd version superior would remain 4.3bsd see also history internet 4.3bsd determined bsd would move away aging vax platform power 6/32 platform codenamed tahoe developed computer consoles inc. seemed promising time abandoned developers shortly thereafter nonetheless 4.3bsd-tahoe port june 1988 proved valuable led separation machine-dependent machine-independent code bsd would improve system future portability apart portability csrg worked implementation osi network protocol stack improvements kernel virtual memory system van jacobson lbl new tcp/ip algorithms accommodate growth internet versions bsd incorporated proprietary unix code therefore subject software license source code licenses become expensive several outside parties expressed interest separate release networking code developed entirely outside would subject licensing requirement led networking release 1 net/1 made available non-licensees code freely redistributable terms bsd license released june 1989 4.3bsd-reno came early 1990 interim release early development 4.4bsd use considered gamble hence naming gambling center reno nevada release explicitly moving towards posix compliance according away bsd philosophy posix much based system v reno quite bloated compared previous releases among new features nfs implementation university guelph support hp 9000 range computers originating university utah hpbsd port august 2006 informationweek magazine rated 4.3bsd greatest software ever written commented bsd 4.3 represents single biggest theoretical undergirder internet net/1 bsd developer keith bostic proposed non-at sections bsd system released license net/1 end started project reimplement standard unix utilities without using code example vi based original unix version ed rewritten nvi new vi within eighteen months utilities replaced determined files remained kernel files removed result june 1991 release networking release 2 net/2 nearly complete operating system freely distributable net/2 basis two separate ports bsd intel 80386 architecture free 386bsd william jolitz proprietary bsd/386 later renamed bsd/os berkeley software design bsdi 386bsd short-lived became initial code base netbsd freebsd projects started shortly thereafter bsdi soon found legal trouble unix system laboratories usl subsidiary owners system v copyright unix trademark usl v. bsdi lawsuit filed 1992 led injunction distribution net/2 validity usl copyright claims source could determined lawsuit slowed development free-software descendants bsd nearly two years legal status question result systems based linux kernel legal ambiguity gained greater support although released 1992 development 386bsd predated linux linus torvalds said 386bsd gnu kernel available time probably would created linux lawsuit settled january 1994 largely berkeley favor 18,000 files berkeley distribution three removed 70 modified show usl copyright notices condition settlement usl would file lawsuits users distributors berkeley-owned code upcoming 4.4bsd release marshall kirk mckusick summarizes lawsuit outcome june 1994 4.4bsd released two forms freely distributable 4.4bsd-lite contained source whereas 4.4bsd-encumbered available earlier releases licensees final release berkeley 1995 4.4bsd-lite release 2 csrg dissolved development bsd berkeley ceased since several variants based directly indirectly 4.4bsd-lite freebsd netbsd openbsd dragonfly bsd maintained addition permissive nature bsd license allowed many operating systems free proprietary incorporate bsd code example microsoft windows used bsd-derived code implementation tcp/ip bundles recompiled versions bsd command-line networking tools since windows 2000 also darwin system apple macos built derivative 4.4bsd-lite2 freebsd various commercial unix operating systems solaris also contain varying amounts bsd code bsd base large number operating systems notable among today perhaps major open source bsds freebsd netbsd openbsd derived 386bsd 4.4bsd-lite various routes netbsd freebsd started life 1993 initially derived 386bsd 1994 migrating 4.4bsd-lite code base openbsd forked 1995 netbsd number commercial operating systems also partly wholly based bsd descendants including sun sunos apple inc. macos current bsd operating systems open source available download free charge bsd license notable exception macos also generally use monolithic kernel architecture apart macos dragonfly bsd feature hybrid kernels various open source bsd projects generally develop kernel userland programs libraries together source code managed using single central source repository past bsd also used basis several proprietary versions unix sun sunos sequent dynix next nextstep dec ultrix osf/1 axp tru64 unix parts next software became foundation macos among commercially successful bsd variants general market selection significant unix versions unix-like operating systems descend bsd includes
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