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domain-specific entertainment language domain-specific entertainment languages group domain-specific languages used describe computer games environments potentially used entertainment video music
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Programming language topics
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firefox 3.6 mozilla firefox 3.6 version firefox web browser released january 2010 release main improvement firefox 3.5 improved performance due speed improvements tracemonkey javascript engine uses gecko 1.9.2 engine compared 1.9.1 ff 3.5 improves compliance web standards codenamed namoroka version support x bitmap images dropped release marked beginning new development cycle firefox well receiving major updates browser also received minor updates new features allow users receive new features quickly dawn new roadmap reflected changes superseded firefox 4 released next year although ff 3.6 prolonged period use version 4 noted user interface changes firefox 3.6 last major version official firefox release run powerpc-based macintoshes see tenfourfox much-more-recent version firefox powerpc-based computers running mac os x soon 4 much less weight given major version numbers 6 numbers used september year 4 5 6 7 8 9 compared 3 nearly decade firefox development 1 2 3 firefox versions 4 9 reached end-of-life status mozilla continued supporting firefox 3.6 security updates coinciding proposal cater enterprise users optional extended support releases beginning 2012 based upon firefox 10 mozilla discontinued support firefox 3.6 april 24 2012 automatic update firefox 12 pushed compatible devices june 2012 development version started december 1 2008 first alpha version 3.6 released august 7 2009 first beta version released october 30 followed beta 2 november 10 beta 3 november 17 beta 4 november 26 beta 5 december 17 release candidate 1 released january 8 2010 followed release candidate 2 january 17 final version released january 21 2010 firefox 3.6.2 released march 23 2010 followed version 3.6.3 april 1 closed bugs aslr dep handling found pwn2own contest 2010 firefox developers created new feature called lorentz named lorentz national park preview version lorentz firefox 3.6.3plugin1 made available april 8 2010 betas firefox 3.6.4 made available starting april 20 2010 firefox 3.6.4 released june 22 2010 windows linux versions incorporate out-of-process plug-ins oopp isolates execution plug-ins adobe flash apple quicktime microsoft silverlight default separate process significantly reduces number firefox crashes experienced users watching online videos playing games user simply refresh page continue mozilla states 30 browser crashes caused third-party plugins support plug-ins default oopp mac os x platform become available firefox 4 firefox 3.6.6 lengthens amount time plug-in allowed unresponsive point plug-in quits firefox 3.6.7 security stability update fixed several issues firefox 3.6.8 security update released mere three days 3.6.7 fix another security fault firefox 3.6.9 addition fixing security stability issues introduced support codice_1 http response header help prevent clickjacking firefox 3.6.10 security stability update fixed several issues firefox 3.6.11 security stability update fixed several issues firefox 3.6.12 security update fixed critical security issue firefox 3.6.13 security stability update fixed several issues firefox 3.6.14 security stability update fixed several issues firefox 3.6.15 stability update fixed java applets issue firefox 3.6.16 security update blacklisted invalid https certificates firefox 3.6.17 security stability update fixed several issues firefox 3.6.18 security stability update fixed several issues firefox 3.6.19 stability update fixed several issues firefox 3.6.20 security stability update fixed several issues firefox 3.6.21 security update blacklisted compromised https certificate firefox 3.6.22 security update revoked ssl certificates staten der nederlanden due fraudulent ssl certificate issuance well fixing error .gov.uk domain names firefox 3.6.23 security stability update fixed several issues firefox 3.6.24 security stability update fixed several issues firefox 3.6.25 security stability update fixed several issues firefox 3.6.26 security stability update fixed several issues firefox 3.6.27 security update fixed several issues firefox 3.6.28 security stability update fixed several issues new features firefox 3.6 include mozilla discontinued support firefox 3.6 april 24 2012 27 months support made longest supported version firefox even longer firefox 2 26 months total support underlying gecko 1.9.2 engine continued used updates camino
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Internet protocols
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generally accepted privacy principles generally accepted privacy principles gapp framework intended assist chartered accountants certified public accountants creating effective privacy program managing preventing privacy risks framework developed joint consultation canadian institute chartered accountants cica american institute certified public accountants aicpa aicpa/cica privacy task force gapp framework previously known aicpa/cica privacy framework founded single privacy principle personally identifiable information must collected used retained disclosed compliance commitments entity privacy notice criteria set gapp issued aicpa/cica privacy objective supported ten main principles seventy objectives associated measurable criteria privacy defined generally accepted privacy principles rights obligations individuals organizations respect collection use retention disclosure disposal personal information
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Computer security
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national interop national interop systems integration company earliest experience radio ip technologies deployed public safety communications company founded public safety personnel one principals company testified u.s. senate 2007 applicability radio ip roip alternative expensive statewide interoperable radio systems proposed funding federal government costs us 1b per state company designed implemented roip-powered system air evac lifeteam spanning 14 states 80+ radio towers 24x7 9-1-1 type dispatch center well numerous smaller roip systems national interop works roip technologies may best suited particular public safety application
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Computer architecture
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windows live onecare windows live onecare previously windows onecare live codenamed a1 computer security performance enhancement service developed microsoft windows core technology onecare multi-platform rav reliable anti-virus microsoft purchased gecad software srl 2003 subsequently discontinued software available annual paid subscription could used three computers 18 november 2008 microsoft announced windows live onecare would discontinued 30 june 2009 instead offering users new free anti-malware suite called microsoft security essentials available however virus definitions support onecare would continue subscription expires end-of-life announcement microsoft noted windows live onecare would upgraded work windows 7 would also work windows xp mode windows live onecare entered beta state summer 2005 managed beta program launched public beta located betaplace microsoft former beta delivery system 31 may 2006 windows live onecare made official debut retail stores united states beta version windows live onecare 1.5 released early october 2006 microsoft version 1.5 released manufacturing 3 january 2007 made available public 30 january 2007 4 july 2007 beta testing started version 2.0 final version released 16 november 2007 microsoft acquired komoku 20 march 2008 merged computer security software windows live onecare windows live onecare 2.5 build 2.5.2900.28 final released 3 july 2008 day microsoft also released windows live onecare server 2.5 windows live onecare features integrated anti-virus personal firewall backup utilities tune-up utility integrated functionality windows defender malware protection future addition registry cleaner considered added significant customer advantages functionality version 2 added features multi-pc home network management printer sharing support start-time optimizer proactive fixes recommendations monthly reports centralized backup online photo backup windows live onecare built ease-of-use designed home users onecare also attempts minimal interface lessen user confusion resource use adds icon notification area tells user glance status system health using three alert colors green good yellow fair red risk version 1.5 onecare compatible 32 bit versions windows xp windows vista version 2 onecare supports 64 bit compatibility vista version 2.5 microsoft released windows live onecare server supports windows server 2008 standard 64-bit windows small business server 2008 standard premium editions edition onecare operates safe mode windows live onecare support windows 7 development discontinued replaced microsoft security essentials windows live onecare requires users activate product wish continue using free trial period 90 days valid windows live id product activated grey message bar top program disappears subscription remains active 1 year date activation windows live onecare require operating system checked windows genuine advantage windows live onecare protection plus security component onecare suite consists three parts windows live onecare 1.5 onwards also monitors internet explorer 7 8 security settings ensures automatic website checking feature phishing filter enabled windows live onecare performance plus component performs monthly pc tune-up related tasks windows live onecare backup restore component aids backing important files files backed various recordable media external hard disks cds dvds restoring files entirety subset also restored networked computer long running onecare well backup restore component supports backup software features incremental backups scheduling windows live onecare criticized users competing security software companies microsoft acquisition gecad rav core technology onecare subsequent discontinuation product deprived gnu/linux platform others one leading virus scanning tools e-mail servers bringing microsoft ultimate intentions question 26 january 2006 windows live onecare criticized foundstone division competing mcafee anti-virus integrated firewall default white lists allow java applications digitally signed software bypass user warnings since neither applications carry assurances security flaws written malicious intent microsoft since responded criticism justifying decision java applications widely used third party applications popular trusted program among users highly unusual malware signed windows live onecare also criticized lack adherence industry firewall standards concerning intrusion detection tests conducted agnitum developers outpost firewall shown onecare failing detect trojans malware hijack applications already resident infected machine february 2007 first windows vista anti-virus product testing virus bulletin magazine sister company sophos developers sophos anti-virus found windows live onecare failed detect 18.6 viruses fifteen anti-virus products tested pass virus bulletin vb100 test anti-virus product detect 100 viruses av-comparatives also released results placed windows live onecare last testing seventeen anti-virus products response jimmy kuo microsoft security research response msrr team pledged add truly important actively spread malware soon possible test detection numbers get better better malware par majors arena also expressed confidence improvements soon majors need catch us april 2008 windows live onecare passed vb100 test windows vista sp1 business edition august 2008 windows live onecare placed 14th 16 anti-virus products on-demand virus detection rates hand may 2009 windows live onecare placed 2nd proactive/retrospective performance test conducted av-comparatives av-comparatives.org test issuer denotes false alarms good achievement publisher also points false positives cause much harm genuine infections furthermore anti-virus scanners prone false alarms essentially achieve higher detection scores
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Computer security
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macintosh ii family macintosh ii family personal computers designed manufactured sold apple computer inc. 1987 1993 macintosh ii initial model representing high-end macintosh line time course next six years seven models produced culminating short-lived macintosh iivi macintosh iivx models apple retired macintosh ii name moved motorola 68040 processors centris quadra names used instead unlike prior macintosh models all-in-one designs macintosh ii models modular systems include built-in monitors expandable beginning macintosh ii culminating macintosh iifx macintosh ii family apple high-end line 1987 introduction motorola 68040-based macintosh quadra computers 1991 expansion provided way nubus become standard expansion bus entire macintosh line almost decade macintosh ii first support color displays first apart macintosh xl support screen resolution larger 512x384 macintosh ii also first use motorola 68000 series processor motorola 68000 except original macintosh ii launched line motorola 68020 clocked 16 mhz exclusively used motorola 68030 microprocessor even motorola 68040 introduced apple would eventually adopt '040 introduction quadra 700 900 positioning models high-end workstation-class machines graphics scientific computing positioning macintosh ii family mainstream desktop computer macintosh ii series lifespan rose become among powerful personal computers available macintosh ii series replaced macintosh centris quadra macintosh lc performa families continued use ii 68030 technology long 68040 introduced powerbook continued use '030 power macintosh era
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Computer architecture
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local variable computer science local variable variable given local scope local variable references function block declared override variable name larger scope programming languages two levels visibility local variables contrasted global variables hand many algol-derived languages allow number nested levels visibility private variables functions constants types hidden within either nested blocks nested functions local variables fundamental procedural programming generally modular programming variables local scope used avoid issues side-effects occur global variables local variables may lexical dynamic scope though lexical static scoping far common lexical scoping lexical scope also called static scoping static scope variable name scope certain block scope program text block definition within block text variable name exists bound variable value outside block text variable name exist contrast dynamic scoping dynamic scope variable name scope certain block scope block functions transitively called block except overridden another declaration block ends variable name exist languages like perl common lisp allow programmer choose static dynamic scoping defining redefining variable examples languages use dynamic scoping include logo emacs lisp shell languages bash dash mirbsd korn shell mksh local declaration languages provide lexically scoped local variables languages local variables automatic variables stored call stack directly means recursive function calls local variables instance function given distinct addresses hence variables scope declared written read without risk side-effects functions outside block declared programming languages employ call value semantics provide called subroutine local copy arguments passed languages local parameters treated local variables within subroutine contrast call reference call name semantics allow parameters act aliases values passed arguments allowing subroutine modify variables outside scope special type local variable called static local available many mainstream languages including c/c++ visual basic vb.net allows value retained one call function another – static variable local scope case recursive calls function also access single statically allocated variable languages static variables declared special storage class keyword e.g. codice_1 static locals global functions lifetime static global variables value remains memory life program function scope global scope automatic local variables distinct usages codice_1 keyword several different meanings various languages perl supports dynamic lexically-scoped local variables keyword codice_3 used define local dynamically-scoped variables codice_4 used local lexically-scoped variables since dynamic scoping less common today perl documentation warns codice_3 n't people think “ local ” instead codice_3 keyword gives temporary dynamically-scoped value global package variable lasts end enclosing block however variable visible function called within block create lexically-scoped local variables use codice_4 operator instead understand works consider following code output happens since global variable modified new temporary local meaning inside global value restored upon leaving scope using codice_4 case instead codice_3 would printed 1 three times since case codice_10 variable would limited static scope function seen randal l. schwartz tom phoenix argue operator codice_3 different name like codice_12 ruby language inspired also perl case notation made simpler global variable name must preceded sign like codice_13 local variable simply sign front name like codice_14 perl scalar values front note ruby provides built-in support statically-scoped local variables like perl codice_4 dynamically-scoped local variables like perl codice_3 least one library ruby provides dynamically-scoped variables
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Programming language topics
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non-interference security non-interference strict multilevel security policy model first described goguen meseguer 1982 amplified 1984 simple terms computer modeled machine inputs outputs inputs outputs classified either low low sensitivity highly classified high sensitive viewed uncleared individuals computer non-interference property sequence low inputs produce low outputs regardless high level inputs low uncleared user working machine respond exactly manner low outputs whether high cleared user working sensitive data low user able acquire information activities high user let formula_1 memory configuration let formula_2 formula_3 projection memory formula_1 low high parts respectively let formula_5 function compares low parts memory configurations i.e. formula_6 iff formula_7 let formula_8 execution program formula_9 starting memory configuration formula_1 terminating memory configuration formula_11 definition non-interference deterministic program formula_9 following formula_13 strict policy computer system covert channels may comply say bell–lapadula model comply non-interference reverse could true reasonable conditions system labelled files etc except classified information startup exceptions noted however non-interference shown stronger non-deducibility strictness comes price difficult make computer system property may one two commercially available products verified comply policy would essentially simple switches one-way information filters although could arranged provide useful behaviour computer time=0 high i.e. classified information within low users create high information subsequent time=0 so-called write-up allowed many computer security policies computer legally leak high information low user still said comply non-interference policy low user able learn anything high user activities learn high information created means actions high users von oheimb 2004 computer systems comply bell-lapadula model suffer problem since explicitly forbid read-up consequently computer system complies non-interference necessarily comply bell-lapadula model thus bell–lapadula model non-interference model incomparable bell-lapadula model stricter regarding read-up non-interference model stricter respect covert channels legitimate multilevel security activities treat individual data records e.g. personal details sensitive allow statistical functions data e.g. mean total number released widely achieved non-interference machine
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Computer security
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recursive join recursive join operation used relational databases also sometimes called fixed-point join compound operation involves repeating join operation typically accumulating records time repetition makes change results compared results previous iteration example database family relationships searched record person mother father fields recursive join would one way retrieve person known ancestors first person direct parents records would retrieved parents information would used retrieve grandparents records new records found example many real cases repetition involves single database table specifically recursive self-join recursive joins time-consuming unless optimized indexing addition extra key fields techniques recursive joins highly characteristic hierarchical data therefore become serious issue xml data xml operations determining whether one element contains another extremely common recursive join perhaps obvious way implement xml data stored relational database standard way define recursive joins standard way recursive common table expressions database management systems support recursive ctes include microsoft sql server oracle postgresql others
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Databases
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romeo file system romeo extension iso 9660 file system optical media cd-roms developed adaptec allows use long filenames 128 characters however romeo backwards compatible iso 9660 discs authored using file system read windows 9x windows nt platforms thus allowing exchange files operating systems non-roman characters involved arabic japanese cyrillic example ü becomes ³
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Computer file systems
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gordano messaging suite gms gms commercial mail groupware server developed gordano ltd runs windows linux solaris aix originally called ntmail first commercially available mail windows platform products rebranded gordano messaging suite august 2002 reflect support additional hardware platforms operating systems features gms include encrypted access using ssl anti-virus anti-spam protection over-the-air handheld synchronization web based webmail calendaring interfaces plugin microsoft outlook allowing microsoft exchange style functionality administration performed web browser using http native support full groupware features exists clients reviews version 15
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Internet protocols
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matt kaufmann matt kaufmann senior research scientist department computer sciences university texas austin united states recipient 2005 acm software system award along robert s. boyer j strother moore work boyer-moore theorem prover
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Programming language topics
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position-independent code computing position-independent code pic position-independent executable pie body machine code placed somewhere primary memory executes properly regardless absolute address pic commonly used shared libraries library code loaded location program address space overlap uses memory example shared libraries pic also used older computer systems lacking mmu operating system could keep applications away even within single address space mmu-less system position-independent code executed memory address without modification differs absolute code must loaded specific location function correctly load-time locatable ltl code linker program loader modifies program execution run particular memory location generating position-independent code often default behavior compilers may place restrictions use language features disallowing use absolute addresses position-independent code use relative addressing instructions refer directly specific memory addresses sometimes execute faster replacing equivalent relative-addressing instructions may result slightly slower execution although modern processors make difference practically negligible early computers ibm 701 april 29 1952 ibm system/360 april 7 1964 code position-dependent program built loaded run particular address multitasking operating system allowed multiple jobs run using separate programs time operations scheduled two concurrent jobs would run programs required load addresses example payroll program accounts receivable program built run address 32k could run time ibm dos/360 1966 ability relocate programs loading sometimes multiple versions program maintained built different load address special class programs called self-relocating programs coded relocate loading ibm os/360 1966 relocated executable programs loaded memory one copy program required loaded program could moved way comparison early segmented systems burroughs mcp burroughs b5000 1961 multics 1964 paging systems ibm tss/360 1967 base bounds systems gecos ge 625 exec univac 1107 code inherently position-independent since addresses program relative current segment rather absolute position-independent code developed eliminate restrictions non-segmented systems position-independent program could loaded address memory invention dynamic address translation function provided mmu originally reduced need position-independent code every process could independent address space range addresses however multiple simultaneous jobs using code created waste physical memory two jobs run entirely identical programs dynamic address translation provides solution allowing system simply map two different jobs address 32k bytes real memory containing single copy program different programs may share common code example payroll program accounts receivable program may contain identical sort subroutine shared module shared library form shared module gets loaded mapped two address spaces procedure calls inside shared library typically made small procedure linkage table stubs call definitive function notably allows shared library inherit certain function calls previously loaded libraries rather using versions data references position-independent code usually made indirectly global offset tables gots store addresses accessed global variables one got per compilation unit object module located fixed offset code although offset known library linked linker links modules create shared library merges gots sets final offsets code necessary adjust offsets loading shared library later position independent functions accessing global data start determining absolute address got given current program counter value often takes form fake function call order obtain return value stack x86 special register powerpc sparc mips probably least risc processors esa/390 stored predefined standard register processor architectures motorola 68000 motorola 6809 wdc 65c816 knuth mmix arm x86-64 allow referencing data offset program counter specifically targeted making position-independent code smaller less register demanding hence efficient dynamic-link libraries dlls microsoft windows use variant e8 call instruction call near relative displacement relative next instruction instructions need fixed dll loaded global variables e.g arrays string literals virtual function tables expected contain address object data section resp code section dynamic library therefore stored address global variable needs updated reflect address dll loaded dynamic loader calculates address referred global variable stores value global variable triggers copy-on-write memory page containing global variable pages code pages global variables contain pointers code global data remain shared processes operation needs done os load dynamic library arbitrary address windows vista later versions windows relocation dlls executables done kernel memory manager shares relocated binaries across multiple processes images always relocated preferred base addresses achieving address space layout randomization aslr versions windows prior vista require system dlls prelinked non-conflicting fixed addresses link time order avoid runtime relocation images runtime relocation older versions windows performed dll loader within context process resulting relocated portions image longer shared processes handing dlls windows differs earlier os/2 procedure derives os/2 presents third alternative attempts load dlls position-independent dedicated shared arena memory maps loaded users dll able use in-memory copy multics procedure conceptually code segment linkage segment code segment contains code linkage section serves template new linkage segment pointer register 4 pr4 points linkage segment procedure call procedure saves pr4 stack loading pointer callee linkage segment procedure call uses indirect pointer pair flag cause trap first call dynamic linkage mechanism add new procedure linkage segment known segment table kst construct new linkage segment put segment numbers caller linkage section reset flag indirect pointer pair ibm s/360 time sharing system tss/360 tss/370 procedure may read-only public csect writable private prototype section psect caller loads v-constant routine general register 15 gr15 copies r-constant routine psect 19th word save area pointed gr13 dynamic loader load program pages resolve address constants first page fault position-independent executables pie executable binaries made entirely position-independent code systems run pic executables reasons used pie binaries used security-focused linux distributions allow pax exec shield use address space layout randomization prevent attackers knowing existing executable code security attack using exploits rely knowing offset executable code binary return-to-libc attacks apple macos ios fully support pie executables versions 10.7 4.3 respectively warning issued non-pie ios executables submitted approval apple app store hard requirement yet non-pie applications rejected openbsd pie enabled default architectures since openbsd 5.3 released support pie statically linked binaries executables codice_1 codice_2 directories added near end 2014 beginning fedora 23 fedora maintainers decided build packages pie enabled default ubuntu 17.10 pie enabled default across architectures gentoo new profiles support pie default android enabled support pies jelly bean removed non-pie linker support lollipop
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Operating systems
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apache drill apache drill open-source software framework supports data-intensive distributed applications interactive analysis large-scale datasets drill open source version google dremel system available infrastructure service called google bigquery one explicitly stated design goal drill able scale 10,000 servers able process petabytes data trillions records seconds drill apache top-level project drill supports variety nosql databases file systems including alluxio hbase mongodb mapr-db hdfs mapr-fs amazon s3 azure blob storage google cloud storage swift nas local files single query join data multiple datastores example join user profile collection mongodb directory event logs hadoop drill datastore-aware optimizer automatically restructures query plan leverage datastore internal processing capabilities addition drill supports data locality drill datastore nodes apache drill 1.9 added dynamic user defined functions apache drill 1.11 added cryptographic-related functions pcap file format support drill primarily focused non-relational datastores including apache hadoop text files nosql cloud storage following datastores supported new datastore added developing storage plugin drill schema-free json data model enables query non-relational datastores in-situ papers influenced birth design partial list
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Distributed computing architecture
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package manager package manager package-management system collection software tools automates process installing upgrading configuring removing computer programs computer operating system consistent manner package manager deals packages distributions software data archive files packages contain metadata software name description purpose version number vendor checksum list dependencies necessary software run properly upon installation metadata stored local package database package managers typically maintain database software dependencies version information prevent software mismatches missing prerequisites work closely software repositories binary repository managers app stores package managers designed eliminate need manual installs updates particularly useful large enterprises whose operating systems based linux unix-like systems typically consisting hundreds even tens thousands distinct software packages software package archive file containing computer program well necessary metadata deployment computer program source code compiled built first package metadata include package description package version dependencies packages need installed beforehand package managers charged task finding installing maintaining uninstalling software packages upon user command typical functions package management system include computer systems rely dynamic library linking instead static library linking share executable libraries machine instructions across packages applications systems complex relationships different packages requiring different versions libraries results challenge colloquially known dependency hell microsoft windows systems also called dll hell working dynamically linked libraries good package management vital systems framework system openstep attempt solving issue allowing multiple versions libraries installed simultaneously software packages specify version linked system administrators may install maintain software using tools package management software example local administrator may download unpackaged source code compile install may cause state local system fall synchronization state package manager database local administrator required take additional measures manually managing dependencies integrating changes package manager tools available ensure locally compiled packages integrated package management distributions based .deb .rpm files well slackware linux checkinstall recipe-based systems gentoo linux hybrid systems arch linux possible write recipe first ensures package fits local package database particularly troublesome software upgrades upgrades configuration files since package managers least unix systems originated extensions file archiving utilities usually either overwrite retain configuration files rather applying rules exceptions usually apply kernel configuration broken render computer unusable restart problems caused format configuration files changes instance old configuration file explicitly disable new options disabled package managers debian dpkg allow configuration installation situations desirable install packages default configuration overwrite configuration instance headless installations large number computers kind pre-configured installation also supported dpkg give users control kinds software allowing installed system sometimes due legal convenience reasons distributors side software often downloaded number software repositories user interacts package management software bring upgrade customary present user list actions executed usually list packages upgraded possibly giving old new version numbers allow user either accept upgrade bulk select individual packages upgrades many package managers configured never upgrade certain packages upgrade critical vulnerabilities instabilities found previous version defined packager software process sometimes called version pinning instance advanced package management features offer cascading package removal packages depend target package packages target package depends also removed although commands specific every particular package manager large extent translatable package managers offer similar functions arch linux pacman/rosetta wiki offers extensive overview package managers like dpkg existed early 1994 linux distributions oriented binary packages rely heavily package management systems primary means managing maintaining software mobile operating systems android linux-based ios unix-like windows phone rely almost exclusively respective vendors app stores thus use dedicated package management systems package manager often called install manager lead confusion package managers installers differences include software configuration management systems treat building software deploying software separate independent steps build automation utility typically takes human-readable source code files already computer automates process converting binary executable package computer later package manager typically running computer downloads pre-built binary executable packages internet installs however kinds tools many commonalities example dependency graph topological sorting used package manager handle dependencies binary components also used build manager handle dependency source components example many makefiles support building executables also installing codice_1 example every package manager portage sorcery homebrew etc supports converting human-readable source code binary executables installing tools maak a-a-p designed handle building deployment used either build automation utility package manager also known binary repository manager software tool designed optimize download storage binary files artifacts packages used produced software development process package managers aim standardize way enterprises treat package types give users ability apply security compliance metrics across artifact types universal package managers referred center devops toolchain common universal package managers sonatype nexus repository manager jfrog artifactory inedo proget package manager relies format metadata packages manage package managers need groups files bundled specific package manager along appropriate metadata dependencies often core set utilities manages basic installation packages multiple package managers use utilities provide additional functionality example yum relies rpm backend yum extends functionality backend adding features simple configuration maintaining network systems another example synaptic package manager provides graphical user interface using advanced packaging tool apt library turn relies dpkg core functionality alien program converts different linux package formats supporting conversion linux standard base lsb compliant .rpm packages .deb stampede .slp solaris .pkg slackware .tgz .txz .tbz .tlz packages mobile operating systems google play consumes android application package apk package format windows store uses appx xap formats google play windows store eponymous package managers nature free open source software packages similar compatible licenses available use number operating systems packages combined distributed using configurable internally complex packaging systems handle many permutations software manage version-specific dependencies conflicts packaging systems free open source software also released free open source software one typical difference package management proprietary operating systems mac os x windows free open source software linux free open source software systems permit third-party packages also installed upgraded mechanism whereas package managers mac os x windows upgrade software provided apple microsoft respectively exception third party drivers windows ability continuously upgrade third party software typically added adding url corresponding repository package management configuration file beside system-level application managers add-on package managers operating systems limited capabilities programming languages developers need latest libraries contrast system-level package managers application-level package managers focus small part software system typically reside within directory tree maintained system-level package manager however might case package managers deal programming libraries leading possible conflict package managers may claim file might break upgrades ian murdock commented package management single biggest advancement linux brought industry blurs boundaries operating system applications makes easier push new innovations ... marketplace ... evolve os
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Operating systems
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diamond mine video game diamond mine video game first published mrm software acorn electron bbc micro home computers 1984 reissued blue ribbon 1985 ported systems 1985 1986 blue ribbon also released sequel diamond mine ii time games similar 1982 arcade game anteater maze design limited pipe length non-stop movement make first game original diamond mine ii could considered anteater clone aim game guide pipe maze-like mine collect diamonds avoiding hitting walls patrolling monsters player set length pipe level pipe started moving stop retracted section pipe lost pipe hit monster hits wall twice amount pipe lost diamonds placed sporadically maze way kill monsters sequel similar fundamental changes game play pipe pause retracted time without penalty walls hit monsters killed touching end pipe move pipe retracted maze also populated regular diamonds resemble dots pac-man maze
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Computer architecture
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dr web dr.web software suite developed russian anti-malware company doctor web first released 1992 became first anti-virus service russia company also offers anti-spam solutions used yandex scan e-mail attachments also features add-on major browsers checks links online version dr web dr.web withdrawn av tests virus bulletin vb100 around 2008 stating believe virus scans viruses different subject real world malware attacks staunch anti-adware policy led software developers complaints dr web treated virus free applications virus receive responds dr web try contact dr web resolve issue dr.web discovered trojan backdoor.flashback variant affected 600,000 macs dr.web discovered trojan.skimer.18 trojan works like atm software skimmer trojan intercept transmit bank card information processed atms well data stored card pin code dr.web discovered ransomware linux.encoder.1 affected 2,000 linux users linux.encoder.2 discovered later turned earlier version ransomware doctor web received threat supposedly trojan writers criminal organization sponsoring malware development promotion march 31 two arson attacks carried igor daniloff anti-virus laboratory st. petersburg company received second threat doctor web released statement company considers duty provide users ultimate protection encroachments cybercriminals consequently efforts aimed identifying studying atm threats atm shield
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Computer security
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proget proget package management system designed inedo software company allows users host manage personal enterprise-wide packages applications components originally designed private nuget package manager microsoft development platform manager symbol source server enterprises utilize proget “ package applications components ” aim ensuring software built deployed consistently across environments gartner lists proget tool aligned “ preprod ” section devops toolchain used “ hold/stage software ready release ” proget currently supports growing list package managers including nuget chocolatey bower npm maven powershell rubygems helm debian python visual studio extensions .vsix proget also supports docker containers jenkins build artifacts plugin vulnerability scanning possible monitor feeds proget interface features also available managed number clients interfaces proget main features include originally proget designed run microsoft windows beginning version 4.4 also run linux via docker proget used asos.com cellenza abanca webmd health services sitecore infragistics among others
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Operating systems
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acknowledgement data networks data networking telecommunications computer buses acknowledgement ack signal passed communicating processes computers devices signify acknowledgement receipt message part communications protocol negative-acknowledgement nak nack signal sent reject previously received message indicate kind error acknowledgements negative acknowledgements inform sender receiver state adjust state accordingly oftentimes data messages telecommunications contain checksums verify integrity payload header checksums work way single bit data corrupted checksum would different value provide inexpensive way check probable signal integrity message received invalid checksum data received would different checksum message receiver know information corrupted often checksums employed corrupted message received either served ack signal served nak signal ascii code used communicate computer terminals terminal send enquiry character request condition receiver character respond ack 0000110 6 indicate operating normally nak 0010101 15 indicate error condition unicode provides visible symbols characters u+2406 ␆ u+2415 ␕ many protocols acknowledgement-based meaning positively acknowledge receipt messages internet transmission control protocol tcp example acknowledgement-based protocol computers communicate via tcp received packets acknowledged sending back packet ack bit set tcp protocol allows acknowledgements included data sent opposite direction protocols send single acknowledgement per packet information protocols tcp zmodem allow many packets transmitted receiving acknowledgement procedure necessary fill high bandwidth-delay product links large number bytes flight protocols nak-based meaning respond messages problem examples include reliable multicast protocols send nak receiver detects missing packets still protocols make use naks acks binary synchronous communications bisync adaptive link rate energy-efficient ethernet examples still protocols rc-5 user datagram protocol udp x10 protocols perform blind transmission acknowledgement often transmitting message multiple times hopes least one copy message gets acknowledgement function used automatic repeat request arq function acknowledgement frames numbered coordination frames received sent transmitter allows transmitter avoid overflow underrun receiver become aware missed frames binary synchronous communications nak used indicate transmission error detected previously received block receiver ready accept retransmission block bisync use single ack character two control sequences alternate even/odd block acknowledgement computer buses dedicated acknowledge wire control bus used acknowledge bus operations dack used isa dma datack used stebus data transfer acknowledge pin motorola 68000 inspired title dtack grounded etc computer buses always acknowledge every write writes use posted write i²c serial bus time slot acknowledgment bit byte
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Internet protocols
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twitterrific twitterrific mac os x ios client social networking site twitter created iconfactory first twitter desktop client come mac os x lets users view tweets micro-blog posts twitter website real time well publish twitterrific closed source software program main window uses translucent black theme similar certain palettes used aperture iphoto apple inc. software users may choose view full public timeline friends feed users also click links view poster profile mark tweet favorite twitterrific also provides functionality upload images videos posting twitter version 2.1 twitterrific supports growl notifications enhanced applescript capabilities used sites services use twitter api version 3 changed twitterrific advertising supported shareware every hour ad refreshed top list users buy program receive ads changes version 3 mostly added compatibility mac os x 10.5 incorporated newer twitter features like direct messaging ios version twitterrific 2008 apple design award best iphone social networking application april 1 2010 iconfactory released twitterrific ipad version 1.0 ready ipad us launch april 3 june 24 version twitterrific launched version 3.0 universally compatible iphone ipod touch ipad february 14 2017 kickstarter project launched iconfactory try revive twitterrific mac application october 10 2017 mac application received 5.0 update added mac app store
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Internet protocols
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sandy bridge sandy bridge codename microarchitecture used second generation intel core processors core i7 i5 i3 sandy bridge microarchitecture successor nehalem microarchitecture intel demonstrated sandy bridge processor 2009 released first products based architecture january 2011 core brand sandy bridge manufactured 32 nanometer process intel subsequent generation ivy bridge announced 2011 uses 22 nanometer die shrink known tick–tock model core i7 2600 sandy bridge cpu 3.4 ghz 1333 mhz ddr3 memory reaches 83 gflops performance whetstone benchmark 118,000 mips dhrystone benchmark last intel microarchitecture windows vista driver support officially exists intel demonstrated sandy bridge processor a1 stepping 2 ghz intel developer forum september 2009 upgraded features nehalem include sandy bridge processors one two four cores report cpuid model 0206a7h closely related stepping number seen cpuid pci configuration space later sandy bridge-e processors eight cores graphics using cpuids 0206d6h 0206d7h ivy bridge cpus cpuid 0306a9h date built four different configurations differing number cores l3 cache gpu execution units processors featuring intel hd 3000 graphics set bold processors feature hd 2000 graphics hd graphics pentium celeron models graphics core graphics clock rate indicated n/a suffixes denote note 3970x 3960x 3930k 3820 actually sandy bridge-e edition suffixes denote 31 january 2011 intel issued recall 67-series motherboards due flaw cougar point chipset hardware problem exists chipset sata ii ports may fail time causing failure connection sata devices though data risk intel claims problem affect 5 users 3 years however heavier i/o workloads exacerbate problem intel stopped production flawed b2 stepping chipsets began producing b3 stepping chipsets silicon fix shipping new chipsets started 14 february 2011 intel estimated full recovery volume april 2011 motherboard manufacturers asus gigabyte technology computer manufacturers dell hewlett-packard stopped selling products involved flawed chipset offered support affected customers options ranged swapping b3 motherboards product refunds sandy bridge processor sales temporarily hold one use cpu without motherboard however processor release dates affected two weeks intel continued shipping chipsets manufacturers agree set terms prevent customers encountering bug motherboard manufacturer websites instruction identify chipset stepping version using bios lshw produces partial output output says 'version 05 intel 6 series chipset intel c200 series chipset specification update google intel h61 revision 05 result 1 'pch device revision identification page 13 says '05h located 'b3 rev id 'b3 chipset stepping version suffix h means hexadecimal '05h means 5 sandy bridge intel tied speed every bus usb sata pci pci-e cpu cores uncore memory etc single internal clock generator issuing basic base clock bclk cpus multiplier locked way overclock increase bclk raised 5–7 without hardware components failing work around intel made available k/x-series processors feature unlocked multipliers multiplier cap 57 sandy bridge sandy bridge e platform alternative method known bclk ratio overclock idf intel developer forum 2010 intel demonstrated unknown sandy bridge cpu running stably overclocked 4.9 ghz air cooling non-k edition cpus overclock four bins turbo multiplier refer chipset support sandy ivy bridge processors vpro capability security features remotely disable pc erase information hard drives useful case lost stolen pc commands received 3g signals ethernet internet connections aes encryption acceleration available useful video conferencing voip applications sandy ivy bridge processors contain drm technology video streaming web sites rely restrict use content web sites offer 1080p streaming users cpus downgrade quality users introduction sandy bridge microarchitecture intel also introduced intel data plane development kit intel dpdk help developers communications applications take advantage platform packet processing applications network processors intel demonstrated haswell architecture september 2011 released 2013 successor sandy bridge ivy bridge
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Computer architecture
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region-based memory management computer science region-based memory management type memory management allocated object assigned region region also called zone arena area memory context collection allocated objects efficiently deallocated like stack allocation regions facilitate allocation deallocation memory low overhead flexible allowing objects live longer stack frame allocated typical implementations objects region allocated single contiguous range memory addresses similarly stack frames typically allocated simple example consider following c code allocates deallocates linked list data structure region *r createregion listnode *head null int 1 1000 i++ // ... // use list destroyregion r although required many operations construct linked list destroyed quickly single operation destroying region nodes allocated need traverse list simple explicit regions straightforward implement following description based hanson region implemented linked list large blocks memory block large enough serve many allocations current block maintains pointer next free position block block filled new one allocated added list region deallocated next-free-position pointer reset beginning first block list blocks reused next region created alternatively region deallocated list blocks appended global freelist regions may later allocate new blocks simple scheme possible deallocate individual objects regions overall cost per allocated byte scheme low almost allocations involve comparison update next-free-position pointer deallocating region constant-time operation done rarely unlike typical garbage collection systems need tag data type basic concept regions old first appearing early 1967 douglas t. ross aed free storage package memory partitioned hierarchy zones zone allocator zone could freed all-at-once making zones usable regions 1976 pl/i standard included area data type 1990 hanson demonstrated explicit regions c called arenas could achieve time performance per allocated byte superior even fastest-known heap allocation mechanism explicit regions instrumental design number early c-based software projects including apache http server calls pools postgresql database management system calls memory contexts like traditional heap allocation schemes provide memory safety possible programmer access region deallocated dangling pointer forget deallocate region causing memory leak 1988 researchers began investigating use regions safe memory allocation introducing concept region inference creation deallocation regions well assignment individual static allocation expressions particular regions inserted compiler compile-time compiler able way guarantee dangling pointers leaks occur early work ruggieri murtagh region created beginning function deallocated end use data flow analysis determine lifetime static allocation expression assign youngest region contains entire lifetime 1994 work generalized seminal work tofte talpin support type polymorphism higher-order functions standard ml functional programming language using different algorithm based type inference theoretical concepts polymorphic region types region calculus work introduced extension lambda calculus including regions adding two constructs due syntactic structure regions nested meaning r created r must also deallocated r result stack regions moreover regions must deallocated function created restrictions relaxed aiken et al extended lambda calculus intended serve provably memory-safe intermediate representation compiling standard ml programs machine code building translator would produce good results large programs faced number practical limitations resolved new analyses including dealing recursive calls tail recursive calls eliminating regions contained single value work completed 1995 integrated ml kit version ml based region allocation place garbage collection permitted direct comparison two medium-sized test programs yielding widely varying results 10 times faster four times slower depending region-friendly program compile times however order minutes ml kit eventually scaled large applications two additions scheme separate compilation modules hybrid technique combining region inference tracing garbage collection following development ml kit regions began generalized language environments systems using regions may experience issues regions become large deallocated contain large proportion dead data commonly called leaks even though eventually freed eliminating leaks may involve restructuring program typically introducing new shorter-lifetime regions debugging type problem especially difficult systems using region inference programmer must understand underlying inference algorithm examine verbose intermediate representation diagnose issue tracing garbage collectors effective deallocating type data timely manner without program changes one justification hybrid region/gc systems hand tracing garbage collectors also exhibit subtle leaks references retained data never used region-based memory management works best number regions relatively small contains many objects programs contain many sparse regions exhibit internal fragmentation leading wasted memory time overhead region management presence region inference problem difficult diagnose mentioned rc uses hybrid regions reference counting limiting overhead reference counting since references internal regions n't require counts updated 're modified similarly mark-region hybrid methods combine tracing garbage collection regions function dividing heap regions performing mark-sweep pass regions containing live objects marked freeing unmarked regions require continual defragmentation remain effective
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Operating systems
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transana transana software package used analyze digital video audio data transana used gpl licensed software become proprietary software recent releases transana lets user analyze manage data transcribe identify analytically interesting clips assign keywords clips arrange rearrange clips create complex collections interrelated clips explore relationships applied keywords share analysis colleagues goal find new way focus data manage large collections video audio files clips transana product digital insight project developed funding national science foundation national partnership computational infrastructure san diego supercomputer center talkbank project carnegie mellon university
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Computational linguistics
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sgi octane octane similar octane2 irix workstations marketed sgi two-way multiprocessing-capable workstations originally based mips technologies r10000 microprocessor newer octanes based r12000 r14000 octane2 four improvements compared octane revised power supply system board xbow octane2 also shipped vpro graphics supports vpro cards later revisions octane also included improvements introduced octane2 codenames octane octane2 racer speedracer respectively octane direct successor indigo2 succeeded tezro immediate sibling o2 sgi withdrew octane2 price book may 26 2004 ceased octane2 production june 25 2004 support octane2 ceased june 2009 new system named octane iii introduced early 2010 octane iii intel xeon-based desk-side cluster system confused octane octane2 octane system-board designated ip30 system based sgi xtalk architecture means use system bus instead crossbow application specific integrated circuit asic referred xbow dynamic crossbar switch connects xio ports hub one ports used processor memory subsystem one available pci-x expansion four xio slots packet-based high-bandwidth bus somewhat similar hypertransport makes similar single node origin 200 system xio could bridged pci-x using chip named bridge bridging included system board ioc3 multi-i/o chip two isp1040b scsi controllers rad1 audio menet cards four ioc3s pci cage used pci cards octane octane uses arcs boot firmware like contemporary sgi computer systems processors octane series computers octane series single dual cpu modules second cpu added option replace whole cpu module octane supports 256 mb 8 gb system memory using proprietary 200-pin dimms two system board revisions first revision part number 030-0887-003 supports 2 gb ram second part number 030-1467-001 allows 8 gb memory subsystem vast reserves bandwidth directly served xbow router xio card octane memory controller named heart acts bridge processor memory sdram xio bus graphics octane provided series cards si si+t ssi mxi updated xio versions solid impact si high impact si+t maximum impact mxi sgi indigo2 internally designated sgi 'mardigras boards accelerated reengineered faster geometry engine texture modules create new versions se se+t sse mxe si/se provides 13.5 mb framebuffer memory sse mxe 27 mb framebuffer '+t indicates additional high speed rambus rdram-based texture board gives 4 mb texture memory practically indispensable though quite expensive fragile si/se+t one texture board mxi/mxe 2 texture boards however 2 boards mxi/mxe double available texture memory system doubles texture performance later octanes octane2 support sgi vpro graphics board series designated 'odyssey first vpro series cards v6 v8 main differentiator v6 32 mb ram unlike mardigras option framebuffer memory texture memory come pool v8 128 mb later v10 32 mb v12 128 mb introduced main difference new vpro v10/v12 series double geometry performance older v6/v8 v6 v10 8 mb ram allocated textures 2x textured-enabled mardigras options v8 v12 108 mb ram used textures vpro graphics subsystem consists sgi proprietary chip set associated software chip set consists buzz asic pixel blaster jammer pb j asic associated sdram buzz asic single-chip graphics pipeline operates 251 mhz contains on-chip sram buzz asic three interfaces mardigras boards vpro boards support opengl mardigras opengl 1.1 sgi extensions vpro upgraded support opengl 1.2 opengl arb imaging extensions allowing hardware acceleration numerous imaging operations real-time rates note cards texture memory offer hardware accelerated texturing however add hardware texturing tramless card adding tram modules audio hardware standard even without extensions support low-latency 3 ms input-to-output audio streams alesis adat 8-channel 24-bit optical ports built-in along s/pdif aes/ebu optical coaxial ports makes octane respectable digital audio workstation octane cases large wxhxd 30x40x35 cm heavy 25 kg yet internal 5.25 drive bays external cd-rom drives must connected desired extensions include video i/o audio i/o networking realtime video compression boards external storage options scsi fibre-channel firewire octanes use standard pci cards optional pci cardcage provides 2-full length 1 half-length 5v pci-64 slots pci xio adapter known 'shoehorn provides single 3.3/5v 64-bit pci slot older octanes upgraded vpro graphics however v10 v12 graphics board require xbow revision 1.4 cherokee power supply vpro v6 v8 require xbow revision 1.3 cherokee power supply distinct difference cherokee 747 watt older lucent 623 watt power supplies mounting handle silver cherokee international manufactured power supplies original lucent manufactured ones black handles octane skins come three types original octane green skins original sgi 'cube logo later model octanes skins colour original octane2-style lettering logos octane2 systems blue skins modern lowercase letter-only sgi logo octane series two scsi controllers supports ultra wide scsi devices systems maximum three internal 3.5 scsi sca devices using proprietary mounting sleds also compatible origin 2000 origin 200 onyx2 external ultra wide scsi port used connecting external devices sgi octane impact-class graphics first supported irix version 6.4 vpro-class graphics supported since irix version 6.5.10 v6 v8 v10 v12 graphics supported 6.5.11 6.5.10 special driver patch linux runs octane series although patch experimental impact vpro graphics supported x window system available impactsr series openbsd port runs octane series well
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Computer architecture
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distributed access control system distributed access control system dacs light-weight single sign-on attribute-based access control system web servers server-based software dacs primarily used apache web servers provide enhanced access control web pages cgi programs servlets web-based assets federate apache servers released open-source license dacs provides modular authentication framework supports array common authentication methods rule-based authorization engine grant deny access resources named urls based identity requestor contextual information administrators configure dacs identify users employing authentication methods user accounts already available within organization resulting dacs identities recognized dacs jurisdictions federated addition simple web-based apis command-line interfaces also provided much functionality web-based apis return xml json documents development dacs began 2001 first open source release made available 2005 dacs use following authentication methods account types extensible architecture allows new methods introduced dacs distribution includes various cryptographic functionality message digests hmacs symmetric public key encryption ciphers chacha20 openssl digital signatures password-based key derivation functions hkdf pbkdf2 memory-hard key derivation functions scrypt argon2 much available simple scripting language dacs also act identity provider infocards function relying party although functionality deprecated dacs performs access control evaluating access control rules specified administrator expressed set xml documents rules consulted run-time determine whether access given resource granted denied access control rules arbitrary computations combines attribute-based access control role-based access control policy-based access control delegated access control approaches architecture provides many possibilities administrators
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Computer security
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firefox mozilla firefox simply firefox free open-source web browser developed mozilla foundation subsidiary mozilla corporation firefox officially available windows 7 newer macos linux unofficial ports available various unix unix-like operating systems including freebsd openbsd netbsd illumos solaris unix sibling firefox android also available firefox uses gecko layout engine render web pages implements current anticipated web standards 2017 firefox began incorporating new technology code name quantum promote parallelism intuitive user interface additional version firefox ios released november 12 2015 due platform restrictions uses webkit layout engine instead gecko ios web browsers firefox created 2002 codename phoenix mozilla community members desired standalone browser rather mozilla application suite bundle beta phase firefox proved popular testers praised speed security add-ons compared microsoft then-dominant internet explorer 6 firefox released november 9 2004 challenged internet explorer dominance 60 million downloads within nine months firefox spiritual successor netscape navigator mozilla community created netscape 1998 acquisition aol firefox usage grew peak 32.21 end 2009 version 3.5 overtaking internet explorer 7 although versions internet explorer whole usage declined competition google chrome firefox 9.53 usage share desktop browser according statcounter making second-most popular browser google chrome 71.03 usage share across platforms lower 4.48 third-most popular overall according mozilla december 2014 half billion firefox users around world project began experimental branch mozilla project dave hyatt joe hewitt blake ross believed commercial requirements netscape sponsorship developer-driven feature creep compromised utility mozilla browser combat saw mozilla suite software bloat created stand-alone browser intended replace mozilla suite april 3 2003 mozilla organization announced planned change focus mozilla suite firefox thunderbird community-driven seamonkey formed eventually replaced mozilla application suite 2005 firefox project undergone several name changes nascent browser originally named phoenix mythical bird rose triumphantly ashes dead predecessor case ashes netscape navigator sidelined microsoft internet explorer first browser war phoenix renamed due trademark claim phoenix technologies replacement name firebird provoked intense response firebird database software project mozilla foundation reassured browser would always bear name mozilla firebird avoid confusion pressure mozilla firebird became mozilla firefox february 9 2004 name firefox said derived nickname red panda became mascot newly named project firefox project went many versions version 1.0 released november 9 2004 abbreviation firefox mozilla prefers fx fx though often abbreviated ff 2016 mozilla announced project known quantum sought improve firefox gecko engine components improve firefox performance modernize architecture transition browser multi-process model improvements came wake decreasing market share google chrome well concerns performance lapsing comparison despite improvements changes required existing add-ons firefox made incompatible newer versions favor new extension system designed similar chrome recent browsers firefox 57 released november 2017 first version contain enhancements quantum thus named firefox quantum mozilla executive stated quantum biggest update browser since version 1.0 may 3 2019 expiration intermediate signing certificate caused firefox automatically disable browser extensions add-ons mozilla began roll-out fix shortly thereafter using mozilla studies component features include tabbed browsing spell checking incremental search live bookmarking smart bookmarks download manager private browsing location-aware browsing also known geolocation based google service integrated search system uses google default markets additionally firefox provides environment web developers use built-in tools error console dom inspector extensions firebug recently integration feature pocket firefox hello implementation webrtc added october 2014 allows users firefox compatible systems video call extra feature screen file sharing sending link firefox hello scheduled removed september 2016 functions added add-ons created third-party developers add-ons primarily coded using html javascript api known webextensions designed similar google chrome microsoft edge extension systems firefox previously supported add-ons using xul xpcom apis allowed directly access manipulate much browser internal functionality compatible multi-process architecture xul add-ons deemed legacy add-ons longer supported firefox 57 newer firefox themes added users create download third parties change appearance browser firefox add-on website also gives users ability add applications games ad-blockers screenshot apps many apps firefox implements many web standards including html4 almost full html5 xml xhtml mathml svg 2 partial css extensions ecmascript javascript dom xslt xpath apng animated png images alpha transparency firefox also implements standards proposals created whatwg client-side storage canvas element standards implemented gecko layout engine spidermonkey javascript engine firefox passed acid2 standards-compliance test since version 3.0 mozilla originally stated intend firefox pass acid3 test fully believed svg fonts part test become outdated irrelevant due woff agreed upon standard major browser makers svg font tests removed acid3 test september 2011 firefox 4 greater scored 100/100 firefox also implements safe browsing proprietary protocol google used exchange data related phishing malware protection since version 38 windows vista newer firefox supports playback video content protected html5 encrypted media extensions eme security privacy reasons eme implemented within wrapper open source code allows execution proprietary drm module adobe systems—adobe primetime content decryption module cdm cdm runs within sandbox environment limit access system provide randomized device id prevent services uniquely identifying device tracking purposes drm module downloaded enabled disabled manner plug-ins since version 47 google widevine cdm windows mac os x streaming services like amazon video switch silverlight encrypted html5 video also supported mozilla justified partnership adobe google stating important step mozilla roadmap remove npapi plugin support upon introduction eme support builds firefox windows also introduced exclude support eme free software foundation cory doctorow condemned mozilla decision support eme html5 web standards test firefox 68 scores 513 582 points firefox allowed sandbox security model manage privileges accorded javascript code feature since deprecated limits scripts accessing data websites based same-origin policy also provides support smart cards web applications authentication purposes uses tls protect communications web servers using strong cryptography using https protocol freely available https everywhere add-on enforces https even regular http url entered firefox supports http/2 mozilla foundation offers bug bounty us 3,000 us 7,500 cash reward researchers discover severe security holes firefox official guidelines handling security vulnerabilities discourage early disclosure vulnerabilities give potential attackers advantage creating exploits firefox generally fewer publicly known security vulnerabilities internet explorer see comparison web browsers improved security often cited reason switch internet explorer firefox washington post reported exploit code known critical security vulnerabilities internet explorer available 284 days 2006 comparison exploit code known critical security vulnerabilities firefox available nine days mozilla issued patch remedy problem 2006 symantec study showed although firefox surpassed browsers number vendor-confirmed vulnerabilities year september vulnerabilities patched far quickly found browsers firefox vulnerabilities fixed average one day exploit code made available compared nine days internet explorer symantec later clarified statement saying firefox still fewer security vulnerabilities internet explorer counted security researchers 2010 study national institute standards technology nist based data compiled national vulnerability database nvd firefox listed fifth-most vulnerable desktop software internet explorer eighth google chrome first infoworld cited security experts saying firefox becomes popular vulnerabilities found claim mitchell baker president mozilla foundation denied idea market share alone make vulnerabilities relational said october 2009 microsoft security engineers acknowledged firefox vulnerable security issue found 'windows presentation foundation browser plug-in since february year .net framework 3.5 sp1 windows update silently installed vulnerable plug-in firefox vulnerability since patched microsoft firefox 3.6 known unpatched security vulnerabilities according secunia internet explorer 8 five unpatched security vulnerabilities worst rated less critical secunia mozilla claims patched vulnerabilities mozilla products publicly listed january 28 2013 mozilla recognized trusted internet company privacy 2012 study performed ponemon institute result survey 100,000 consumers united states february 2013 plans announced firefox 22 disable third-party cookies default however introduction feature delayed mozilla developers could collect analyze data effect blocking third-party cookies mozilla also collaborated stanford university cookie clearinghouse project develop blacklist whitelist sites used filter version 23 released august 2013 followed lead competitors blocking iframe stylesheet script resources served non-https servers embedded https pages default additionally javascript could also longer disabled firefox preferences javascript automatically re-enabled users upgraded 23 higher disabled change made due use across majority websites potential repercussions non-experienced users unaware impact along availability extensions noscript disable javascript controlled fashion following release added ability disable javascript developer tools testing purposes january 2015 torrentfreak reported using firefox connected internet using vpn serious security issue due browser support webrtc beginning firefox 44 extensions must signed mozilla used release beta versions firefox firefox 43 blocked unsigned extensions allowed enforcement extension signing disabled extensions must submitted mozilla add-ons subject code analysis order signed although extensions listed service order signed may 2 2019 mozilla announced would strengthening signature enforcement methods included retroactive disabling old extensions deemed insecure firefox update may 3 led bug reports extensions disabled found result overlooked certificate policy change set go effect june 10 firefox versions prior 7.0 information bar appears browser first start asking users whether would like send performance statistics telemetry mozilla enabled default development versions firefox release versions according mozilla privacy policy statistics stored aggregate format personally identifiable information transmitted user ip address november 2018 firefox began using sandbox isolate web tabs rest system lack feature previously earned negative comparisons google chrome microsoft edge since version 60 firefox includes option use dns https doh causes dns lookup requests sent encrypted https protocol use feature user must set certain preferences beginning network.trr trusted recursive resolver network.trr.mode 0 doh disabled 1 activates doh addition unencrypted dns 2 causes doh used unencrypted dns use doh value must 3 setting network.trr.uri url https //mozilla.cloudflare-dns.com/dns-query special cloudflare servers activated mozilla privacy agreement server host restricts collection information incoming dns requests may 21 2019 firefox updated include ability block scripts used computer cpu mine cryptocurrency without user permission firefox version 67.0 update also allowed users block known fingerprinting scripts track activity across web however resist fingerprinting july 2 2019 mozilla introduced mechanism allow firefox automatically trust os-installed certificates prevent tls errors firefox widely localized web browser first official release november 2004 available 24 different languages 28 locales including british english american english european spanish argentine spanish chinese traditional chinese characters simplified chinese characters currently supported versions 68.0.2 68.0.2esr 60.8.0esr available 89 locales 79 languages desktop version firefox available supported microsoft windows macos linux firefox android available android formerly firefox mobile also ran firefox os firefox source code may compiled various operating systems however officially distributed binaries provided following firefox 1.0 released windows 9x well windows nt 4.0 later users reported 1.x builds operable installable windows nt 3.51 september 2013 metro-style version firefox optimized touchscreen use introduced aurora release channel however project since cancelled mozilla citing lack user adoption beta versions version 43.0 included first x64 builds made windows 7 server 2008 r2 version 49.0 dropped support processors without sse2 instruction set windows april 2017 users firefox 52.0.2 windows xp windows vista windows server 2003 windows server 2008 automatic updates enabled migrated firefox 52 esr support projected end operating systems last release june 2018 first official release firefox version 1.0 supported macos called mac os x powerpc architecture mac os x builds ia-32 architecture became available via universal binary debuted firefox 1.5.0.2 2006 starting version 4.0 firefox released x64 architecture macos migrated since inception firefox linux supported 32-bit memory architecture ia-32 instruction set 64-bit builds introduced 4.0 release 46.0 release replaced gtk+ 2.18 3.4 system requirement linux systems running x.org starting 53.0 32-bit builds require sse2 instruction set firefox android codenamed fennec web browser smaller non-pc devices mobile phones pdas originally first released nokia maemo operating system specifically nokia n900 january 28 2010 march 29 2011 besides maemo version 4 added android release mobile version browser version number bumped 2 4 synchronizing future desktop releases firefox rendering engines used browsers version 7 last release maemo n900 user interface completely redesigned optimized small screens controls hidden away web content shown screen uses touchscreen interaction methods includes awesome bar tabbed browsing add-on support password manager location-aware browsing ability synchronize user computer firefox browser using firefox sync april 2013 then-mozilla ceo gary kovacs said firefox would come ios long apple required use webkit layout engine one reason given mozilla prior ios 8 apple supplied third-party browsers inferior version javascript engine hobbled performance making impossible match safari javascript performance ios platform apple later opened nitro javascript engine third-party browsers 2015 mozilla announced moving forward firefox ios preview release made available new zealand september year november 2016 firefox released new ios app titled firefox focus private web browser firefox also ported freebsd netbsd openbsd openindiana os/2 skyos beos/haiku unofficial rebranded version called timberwolf available amigaos 4 unofficial continuation mac os x powerpc release continues tenfourfox firefox port openbsd maintained landry breuil since 2010 firefox regularly built current branch operating system latest versions packaged release remain frozen next release 2017 landry began hosting packages newer firefox versions openbsd releases 6.0 onwards making available installations without ports system solaris port firefox including opensolaris maintained oracle solaris desktop beijing team march 2017 team disbanded also unofficial port firefox 3.6.x ibm aix v1.7.x unixware besides official releases mozilla provides development builds firefox distribution channels named order least stable beta developer edition former aurora renamed november 10 2014 nightly starting firefox 54 developer edition based beta build firefox esr version firefox organizations groups need extended support mass deployments esr release based regular version released time supported approximately one year unlike regular rapid releases esrs updated new features performance enhancements every six weeks rather updated high-risk-reduction high-impact security fixes major stability fixes point releases end esr cycle firefox source code free software released mozilla public license mpl version 2.0 license permits anyone view modify redistribute source code result several publicly released applications built netscape flock miro gnu icecat iceweasel songbird pale moon comodo icedragon past firefox licensed solely mpl version 1.1 free software foundation criticized weak copyleft license permitted limited ways proprietary derivative works additionally code licensed mpl 1.1 could legally linked code gpl address concerns mozilla re-licensed firefox tri-license scheme mpl 1.1 gpl 2.0 lgpl 2.1 since re-licensing developers free choose license received code suit intended use gpl lgpl linking derivative works one licenses chosen mpl use including possibility proprietary derivative works chose mpl however january 3 2012 mozilla released gpl-compatible mpl 2.0 release firefox 13 june 5 2012 mozilla used replace tri-licensing scheme crash reporting service initially closed-source switched version 3 program called talkback open-source breakpad socorro server name mozilla firefox registered trademark along official firefox logo may used certain terms conditions anyone may redistribute official binaries unmodified form use firefox name branding distribution restrictions placed distributions modify underlying source code name firefox derives nickname red panda mozilla placed firefox logo files open-source licenses trademark guidelines allow displaying altered similar logos contexts trademark law applies controversy mozilla foundation intentions stopping certain open source distributions using firefox trademark open source browsers enable greater choice innovation market rather aiming mass-market domination mozilla foundation chairperson mitchell baker explained interview 2007 distributions could freely use firefox trademark modify source-code mozilla foundation concern users getting consistent experience used firefox allow distributions code without using official branding firefox build system contains branding switch switch often used alphas auroras future firefox versions allows code compiled without official logo name allow derivative work unencumbered restrictions firefox trademark produced unbranded build trademarked logo name replaced freely distributable generic globe logo name release series modified version derived distributing modified versions firefox firefox name required explicit approval mozilla changes made underlying code required use official branding example permissible use name firefox without also using official logo debian project decided stop using official firefox logo 2006 mozilla copyright restrictions time incompatible debian guidelines told representative mozilla foundation acceptable asked either comply published trademark guidelines cease using firefox name distribution ultimately debian switched branding modified version firefox iceweasel 2016 switched back firefox along mozilla software gnu icecat another derived version firefox distributed gnu project maintains separate branding early firebird phoenix releases firefox considered reasonable visual designs fell short compared many professional software packages october 2003 professional interface designer steven garrity wrote article covering everything considered wrong mozilla visual identity shortly afterwards mozilla foundation invited garrity head new visual identity team release firefox 0.8 february 2004 saw introduction new branding efforts included new icon designs silverorange group web developers long-standing relationship mozilla final renderings jon hicks worked camino logo later revised updated fixing several flaws found enlarged animal shown logo stylized fox although firefox usually common name red panda panda according hicks n't really conjure right imagery widely known firefox icon trademark used designate official mozilla build firefox software builds official distribution partners reason software distributors distribute modified versions firefox use icon june 2019 firefox announced rebranding introduced new logo new logo meant encompass larger family products firefox adopted rapidly 100 million downloads first year availability followed series aggressive marketing campaigns starting 2004 series events blake ross asa dotzler called marketing weeks firefox continued heavily market releasing marketing portal dubbed spread firefox sfx september 12 2004 debuted along firefox preview release creating centralized space discussion various marketing techniques release manifesto stated mozilla project global community people believe openness innovation opportunity key continued health internet two-page ad edition december 16 new york times placed mozilla foundation coordination spread firefox featured names thousands people worldwide contributed mozilla foundation fundraising campaign support launch firefox 1.0 web browser sfx portal enhanced get firefox button program giving users referrer points incentive site lists top 250 referrers time time sfx team sfx members launch marketing events organized spread firefox website part spread firefox campaign attempt break world download record release firefox 3 resulted official certified guinness world record eight million downloads february 2011 mozilla announced would retiring spread firefox sfx three months later may 2011 mozilla officially closed spread firefox mozilla wrote currently plans create new iteration website spread firefox later date celebration third anniversary founding mozilla foundation world firefox day campaign established july 15 2006 ran september 15 2006 participants registered friend website nomination names displayed firefox friends wall digital wall displayed headquarters mozilla foundation firefox community also engaged promotion web browser 2006 firefox contributors oregon state university made crop circle firefox logo oat field near amity oregon near intersection lafayette highway walnut hill road firefox reached 500 million downloads february 21 2008 firefox community celebrated visiting freerice earn 500 million grains rice initiatives included live chat service mozilla launched 2007 allowed users seek technical support volunteers service later retired promote launch firefox quantum november 2017 mozilla partnered reggie watts produce series tv ads social media content december 2005 internet week ran article many readers reported high memory usage firefox 1.5 mozilla developers said higher memory use firefox 1.5 least partially due new fast backwards-and-forwards fastback feature known causes memory problems malfunctioning extensions google toolbar older versions adblock plug-ins older versions adobe acrobat reader pc magazine 2006 compared memory usage firefox 2 opera 9 internet explorer 7 found firefox used approximately much memory two browsers softpedia noted firefox 1.5 took longer start browsers confirmed speed tests ie 6 launched swiftly firefox 1.5 windows xp since many components built os loaded system startup workaround issue preloader application created loaded components firefox startup similar internet explorer windows vista feature called superfetch performs similar task preloading firefox used often enough tests performed pc world zimbra 2006 indicated firefox 2 used less memory internet explorer 7 firefox 3 used less memory internet explorer 7 opera 9.50 beta safari 3.1 beta firefox 2 tests performed mozilla cybernet browser world mid-2009 betanews benchmarked firefox 3.5 declared performed nearly ten times better xp microsoft internet explorer 7 january 2010 lifehacker compared performance firefox 3.5 firefox 3.6 google chrome 4 stable dev versions safari 4 opera 10.1 stable 10.5 pre-alpha versions lifehacker timed long browsers took start reach page right boot-up running least already timed long browsers took load nine tabs tested javascript speeds using mozilla dromaeo online suite implements apple sunspider google v8 tests measured memory usage using windows 7 process manager concluded firefox 3.5 3.6 fifth- sixth-fastest browsers respectively startup 3.5 third- 3.6 sixth-fastest load nine tabs 3.5 sixth- 3.6 fifth-fastest javascript tests also concluded firefox 3.6 efficient memory usage followed firefox 3.5 february 2012 tom hardware performance tested chrome 17 firefox 10 internet explorer 9 opera 11.61 safari 5.1.2 windows 7 tom hardware summarized tests four categories performance efficiency reliability conformance performance category tested html5 java javascript dom css 3 flash silverlight webgl webgl 2 current version 51 java silverlight stop working version 52 —they also tested start time page load time performance tests showed firefox either acceptable strong categories winning three categories html5 html5 hardware acceleration java finishing weak css performance efficiency tests tom hardware tested memory usage management category determined firefox acceptable performing light memory usage strong performing heavy memory usage reliability category firefox performed strong amount proper page loads final category conformance determined firefox strong conformance javascript html5 conclusion tom hardware determined firefox best browser windows 7 os narrowly beat google chrome june 2013 tom hardware performance tested firefox 22 chrome 27 opera 12 internet explorer 10 found firefox slightly edged browsers performance index examined wait times javascript execution speed html5/css3 rendering hardware acceleration performance firefox also scored highest non-performance index measured memory efficiency reliability security standards conformance finishing substantially ahead chrome runner-up tom hardware concluded declaring firefox sound winner performance benchmarks january 2014 benchmark testing memory usage firefox 29 google chrome 34 internet explorer 11 indicated firefox used least memory substantial number tabs open benchmark testing early 2015 high-end windows machine comparing microsoft edge internet explorer firefox chrome opera firefox achieved highest score three seven tests four different javascript performance tests gave conflicting results firefox bested others peacekeeper benchmark behind microsoft products tested sunspider measured mozilla kraken came second place chrome google octane challenge took third behind chrome opera firefox took lead webxprt runs several typical html5 javascript tasks firefox chrome opera achieved highest possible score oort online test measuring webgl rendering speed webgl 2 current terms html5 compatibility testing firefox ranked middle group similar set benchmark tests 2016 showed firefox javascript performance kraken newer jetstream tests trailing slightly behind tested browsers except internet explorer performed relatively poorly octane firefox came ahead ie safari slightly behind rest including vivaldi microsoft edge edge took overall first place jetstream octane benchmarks adoption firefox 57 mozilla quantum project entering production browsers november 2017 firefox tested faster chrome independent javascript tests demonstrated use less memory many browser tabs opened techradar rated fastest web browser may 2019 report downloads continued increasing rate since firefox 1.0 released november 9 2004 firefox already downloaded one billion times number include downloads using software updates third-party websites represent user count one download may installed many machines one person may download software multiple times software may obtained third-party july 2010 ibm asked employees 400,000 use firefox default browser firefox second-most used web browser november 2011 google chrome surpassed according mozilla firefox 450 million users firefox second-most widely used desktop browser position makes fourth-most popular approximately 11.78 worldwide usage share web browsers across platforms according firefox public data report mozilla active monthly count desktop clients decreased around 310 million 2017 260 million 2019
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Internet protocols
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albatross programming language albatross general purpose programming language verified statically
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Programming language topics
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real mode real mode also called real address mode operating mode x86-compatible cpus real mode characterized 20-bit segmented memory address space giving exactly 1 mib addressable memory unlimited direct software access addressable memory i/o addresses peripheral hardware real mode provides support memory protection multitasking code privilege levels release 80286 introduced protected mode real mode available mode x86 cpus backward compatibility x86 cpus start real mode reset though possible emulate real mode systems starting modes 286 architecture introduced protected mode allowing among things hardware-level memory protection using new features however required new operating system specifically designed protected mode since primary design specification x86 microprocessors fully backward compatible software written x86 chips 286 chip made start 'real mode – mode turned new memory protection features could run operating systems written 8086 8088 2018 current x86 cpus including x86-64 cpus able boot real mode operating systems run software written almost previous x86 chip without emulation virtualization pc bios ibm introduced operates real mode dos operating systems ms-dos dr-dos etc. early versions microsoft windows ran real mode windows/386 made possible make use protected mode fully realized windows 3.0 could run either real mode make use protected mode manner windows/386 windows 3.0 actually several modes real mode standard mode 386-enhanced mode latter required virtualization features 80386 processor thus would run 80286 windows 3.1 removed support real mode first mainstream operating environment required least 80286 processor windows 95 architecture evolution windows workgroups 386 enhanced mode none versions could considered modern x86 operating system since switched protected mode certain functions unix linux os/2 windows nt 3.x later etc considered modern os switch cpu protected mode startup never return real mode provide benefits protected mode time 64-bit operating systems use another stepping stone get long mode worth noting protected mode 80286 considerably primitive improved protected mode introduced 80386 latter sometimes called 386 protected mode mode modern 32-bit x86 operating systems run 8086 8088 80186 20-bit address bus unusual segmented addressing scheme intel chose processors actually produces effective addresses 21 significant bits scheme shifts 16-bit segment number left four bits making 20-bit number four least-significant zeros adding 16-bit address offset maximum sum occurs segment offset 0xffff yielding 0xffff0 0xffff 0x10ffef 8086 8088 80186 result effective address overflows 20 bits address wraps around zero end address range i.e taken modulo 2^20 2^20 1048576 0x10000 however 80286 24 address bits computes effective addresses 24 bits even real mode therefore segment 0xffff offset greater 0x000f 80286 would actually make access beginning second mebibyte memory whereas 80186 earlier would access address equal offset -0x10 beginning first mebibyte note 80186 earlier first kibibyte address space starting address 0 permanent immovable location interrupt vector table actual amount memory addressable 80286 later x86 cpus real mode 1 mib 64 kib – 16 b 1114096 b programs predating 80286 designed take advantage wrap-around modulo memory addressing behavior 80286 presented problem backward compatibility forcing 21st address line actual logic signal wire coming chip logic low representing zero results modulo-2^20 effect match earlier processors address arithmetic 80286 internal capability perform function ibm used 80286 ibm pc/at solved problem including software-settable gate enable disable force zero a20 address line a20 pin 80286 system bus known gate-a20 a20 gate still implemented pc chipsets day versions himem.sys extended memory driver ibm-/ms-dos famously displayed upon loading message installed a20 handler piece software control gate-a20 coordinate needs programs protected mode a20 line needs enabled else physical addressing errors occur likely leading system crash intel introduced protected mode x86 family intention operating systems used would run entirely new mode programs running protected mode operating system would run protected mode well substantial differences real mode even rather limited 286 protected mode programs written real mode run protected mode without rewritten therefore wide base existing real mode applications users depended abandoning real mode posed problems industry programmers sought way switch modes however intel consistent intentions processor usage provided easy way switch protected mode 80286 easy way switch back real mode 386 way switch protected mode back real mode reset processor reset always starts real mode compatible earlier x86 cpus back 8086 resetting processor clear system ram awkward inefficient actually feasible protected mode processor state saved memory processor reset restarts real mode executes real mode code restore saved state memory run real mode code program ready switch back protected mode switch real mode costly terms time technique allows protected mode programs use services bios runs entirely real mode designed originally 8088-based ibm personal computer model machine type 5150 mode-switching technique also one used dpmi real emulated dos dos extenders like dos/4gw allow protected mode programs run dos dpmi system dos extender switches real mode invoke dos bios calls switches back return application program runs protected mode changing towards nt kernel resulted operating system needing dos boot computer well unable use need restart computer real mode ms-dos declined windows 3.1x longer supported windows way currently running dos applications require real mode within newer versions windows using emulators dosbox x86 virtualization products
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Programming language topics
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function-level programming computer science function-level programming refers one two contrasting programming paradigms identified john backus work programs mathematical objects value-level programming 1977 turing award lecture backus set forth considered need switch different philosophy programming language design programming languages appear trouble successive language incorporates little cleaning features predecessors plus ... new language claims new fashionable features ... plain fact languages make programming sufficiently cheaper reliable justify cost producing learning use designed fp first programming language specifically support function-level programming style function-level program variable-free cf point-free programming since program variables essential value-level definitions needed function-level programs function-level style programming program built directly programs given outset combining program-forming operations functionals thus contrast value-level approach applies given programs values form succession values culminating desired result value function-level approach applies program-forming operations given programs form succession programs culminating desired result program result function-level approach programming invites study space programs program-forming operations looking derive useful algebraic properties program-forming operations function-level approach offers possibility making set programs mathematical space emphasizing algebraic properties program-forming operations space programs another potential advantage function-level view ability use strict functions thereby bottom-up semantics simplest kind yet another existence function-level definitions lifted lifted lower value-level higher function-level image existing value-level one often terse function-level definitions represent powerful style programming available value-level backus studied publicized function-level style programming message mostly misunderstood supporting traditional functional programming style languages instead fp successor fl backus calls functional programming applicative programming function-level programming particular constrained type key distinction functional languages backus language following hierarchy types ... way generate new functions use one functional forms fixed build functional form least within fp within ffp formal fp restriction means functions fp module generated built-in functions algebra functional forms thus algebraically tractable instance general question equality two functions equivalent halting problem undecidable equality two functions fp equality algebra thus backus imagines easier even today many users lambda style languages often misinterpret backus function-level approach restrictive variant lambda style de facto value-level style fact backus would disagreed 'restrictive accusation argued precisely due restrictions well-formed mathematical space could arise manner analogous way structured programming limits programming restricted version control-flow possibilities available plain unrestricted unstructured programs value-free style fp closely related equational logic cartesian-closed category canonical function-level programming language fp others include fl j
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Programming language topics
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microsoft smartscreen smartscreen officially called windows smartscreen windows defender smartscreen smartscreen filter different places cloud-based anti-phishing anti-malware component included several microsoft products including windows 8 later internet explorer microsoft edge outlook.com designed help protect users attacks utilize social engineering drive-by downloads infect system scanning urls accessed user blacklist websites containing known threats windows 10 creators update microsoft placed smartscreen settings windows defender security center smartscreen first introduced internet explorer 7 known phishing filter phishing filter check every website visited user known suspicious release internet explorer 8 phishing filter renamed smartscreen extended include protection socially engineered malware every website download checked local list popular legitimate websites site listed entire address sent microsoft checks labeled impostor harmful internet explorer 8 show screen prompting site reported harmful n't visited user either visit homepage visit previous site continue unsafe page user attempts download file location reported harmful download cancelled effectiveness smartscreen filtering reported superior socially engineered malware protection browsers according microsoft smartscreen technology used internet explorer 8 successful phishing malicious sites blocking socially engineered malware beginning internet explorer 8 smartscreen enforced using group policy building top smartscreen filter introduced internet explorer 8 internet explorer 9 protection malware downloads extended smartscreen application reputation detects untrustworthy executables warns person downloading executable program without safe reputation site safe reputation internet explorer mobile 10 first release internet explorer mobile support smartscreen filter smartscreen filtering desktop level performing reputation checks default file application downloaded internet introduced windows 8 similar way smartscreen works internet explorer 9 program established good reputation user alerted running program may harm computer smartscreen left default settings administrator needs launch run program microsoft faced concerns surrounding privacy legality effectiveness new system suggesting automatic analysis files involves sending cryptographic hash file user ip address server could used build database users downloads online use outdated ssl 2.0 protocol communication could allow attacker eavesdrop data response microsoft later issued statement noting ip addresses collected part normal operation service would periodically deleted smartscreen windows 8 would use ssl 3.0 security reasons information gathered via smartscreen would used advertising purposes sold third parties outlook.com uses smartscreen protect users unsolicited email messages spam fraudulent emails phishing malware spread via e-mail system mainly controls used e-mail hyperlinks attachments filter spam smartscreen filter uses machine learning microsoft research learns known spam threats user feedback emails marked spam user time preferences help smartscreen filter distinguish characteristics unwanted legitimate e-mail also determine reputation senders number emails checked using algorithms reputation sender scl rating spam confidence level score assigned e-mail message lower score desirable score -1 0 1 considered spam message delivered recipient inbox score 5 6 7 8 9 considered spam delivered recipient junk folder scores 5 6 considered suspected spam score 9 considered certainly spam scl score email found various x-headers received email smartscreen filter also analyses email messages fraudulent suspicious web links suspicious characteristics found email message either directly sent spam folder red information bar top message warns suspect properties smartscreen also protects spoofed domain names spoofing emails verify whether email sent domain claims sent uses technology sender id domainkeys identified mail dkim smartscreen filter also ensures one email authenticated senders distinguish easily putting green shield icon subject line emails f smartscreen also included microsoft outlook microsoft exchange server late 2010 results browser malware testing undertaken nss labs published study looked browser capability prevent users following socially engineered links malicious nature downloading malicious software test browser ability block malicious web pages code according nss labs internet explorer 9 blocked 99 malware downloads compared 90 internet explorer 8 smartscreen application reputation feature opposed 13 achieved firefox chrome safari use google safe browsing malware filter opera 11 found block 5 malware smartscreen filter also noted adding legitimate sites blocklists almost instantaneously opposed several hours took blocklists updated browsers early 2010 similar tests given internet explorer 8 85 passing grade 5 improvement attributed continued investments improved data intelligence comparison research showed chrome 6 firefox 3.6 safari 5 scored 6 19 11 respectively opera 10 scored 0 failing detect socially engineered malware samples manufacturers browsers criticized test focusing upon lack transparency urls tested lack consideration layered security additional browser google commenting report clearly states evaluate browser security related vulnerabilities plug-ins browsers opera commenting results appeared odd received results data providers social malware protection indicator overall browser security july 2010 microsoft claimed smartscreen internet explorer blocked billion attempts access sites containing security risks according microsoft smartscreen filter included outlook.com blocks 4.5 billion unwanted e-mails daily reaching users microsoft also claims 3 incoming email junk mail test cascade insights says half junk mail still arrives inbox users september 2011 blog post microsoft stated 1.5 billion attempted malware attacks 150 million attempted phishing attacks stopped october 2017 criticisms regarding url submission methods addressed creation report unsafe site url submission page microsoft supports url submissions form opposed previous experience user visit site use in-product reporting methods smartscreen filter bypassed phishing attacks use phishing email linking front-end url microsoft database clicking url email redirects user malicious site report website option internet explorer reports currently-open page front-end url phishing attack reported microsoft remains accessible smartscreen filter creates problem small software vendors distribute updated version installation binary files internet whenever updated version released smartscreen responds stating file commonly downloaded therefore install harmful files system fixed author digitally signing distributed software reputation based file hash signing certificate well common distribution method authors bypass smartscreen warnings pack installation program example setup.exe zip-archive distribute way though confuse non-expert users another criticism smartscreen makes non-commercial/small end software development unaffordable developers either purchase standard code signing certificates expensive extended validation certificates extended validation certificates allow developer immediately establish reputation smartscreen often unaffordable people developing software either free immediate profit standard code signing certicates however pose catch-22 developers since smartscreen warnings make people reluctant download software consequence get downloads requires first passing smartscreen passing smartscreen requires getting reputation getting reputation dependent downloads want contribute smartscreen report site smartscreen via https //feedback.smartscreen.microsoft.com/feedback.aspx url= type http -address url=
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Computer security
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insane software insane proprietary interactive streaming animation engine developed lucasarts primarily programmer/game designer vincent lee using custom video compression technology greatly compresses moving images high quality full-screen videos displayed even hi-res graphics modes pc early version first developed followed much enhanced version full throttle outlaws dig also used 1998 games mortimer riddles medallion compression technology incorporated star wars episode insider guide jar jar journey adventure book use full throttle caused problems since insane intended photorealistic contrasting general cartoony feeling rendered environment scaled match rest game world later enhancements made compression technology optimize cartoon style imagery used outlaws
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Distributed computing architecture
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openiked openiked free permissively licensed internet key exchange ikev2 daemon developed part openbsd operating system
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Operating systems
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darknet dark net darknet umbrella term describing portions internet purposefully open public view hidden networks whose architecture superimposed internet darknet often associated encrypted part internet called tor network illicit trading takes place infamous online drug bazaar called silk road also considered part deep web.. anonymous communication whistle-blowers journalists news organisations facilitated darknet tor network use applications including securedrop term originally described computers arpanet hidden programmed receive messages respond acknowledge anything thus remaining invisible dark.an account detailed first online transaction related drugs transpired 1971 students massachusetts institute technology stanford university traded marijuana using arpanet accounts former artificial intelligence laboratory term later usage incorporated services dark web overlay network accessed specific software configurations authorization often using non-standard communication protocols ports types dark webs include friend-to-friend networks usually used file sharing peer-to-peer connection privacy networks tor reciprocal term encrypted darknet clearnet surface web referring content indexable search engines term darknet often used interchangeably dark web due quantity hidden services tor darknet term often inaccurately used interchangeably deep web due tor history platform could search-indexed mixing uses terms described inaccurate commentators recommending terms used distinct fashions darknet coined 1970s designate networks isolated arpanet government-founded military/academical network evolved internet security purposes darknet addresses could receive data arpanet appear network lists would answer pings inquiries term gained public acceptance following publication darknet future content distribution 2002 paper peter biddle paul england marcus peinado bryan willman four employees microsoft argued presence darknet primary hindrance development workable digital rights management drm technologies made copyright infringement inevitable paper described darknet generally type parallel network encrypted requires specific protocol allow user connect journalist j. d. lasica 2005 book darknet hollywood war digital generation described darknet reach encompassing file sharing networks subsequently 2014 journalist jamie bartlett book dark net used term describe range underground emergent subcultures including camgirls cryptoanarchists darknet drug markets self harm communities social media racists transhumanists telegram features encryption ban territory different countries also belongs darknet anonymity contains encrypted channels sale prohibited substances recruiting various organizations coordinating anti-government actions darknets general may used various reasons darknets require specific software installed network configurations made access tor accessed via customised browser vidalia aka tor browser bundle alternatively via proxy configured perform function
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Distributed computing architecture
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linux userland filesystem linux userland filesystem lufs file system linux similar fuse file system driver provides bridge kernel mode user mode lufs possible among things mount remote directories via ssh ftp gnutella fuse lufs filesystem developed little effort comparable normal application addition fuse linux kernel lufs lost relevance longer developed
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Computer file systems
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titan rain titan rain designation given federal government united states series coordinated attacks american computer systems since 2003 known ongoing least three years attacks originated guangdong china activity known titan rain believed associated state-sponsored advanced persistent threat titan rain hackers gained access many united states defense contractor computer networks targeted sensitive information including lockheed martin sandia national laboratories redstone arsenal nasa series attacks believed actions people ’ liberation army pla unit 61398 hackers attacked american defense intelligence agency – dod british government departments ministry defence – mod british government incident 2006 part house commons computer system shut “ organised chinese hacking group. ” chinese government denied responsibility ‘ titan rain ’ caused friction u.s. chinese governments u.s. government blamed chinese government attacks 2004 unclassified although potentially fatal information alan paller sans institute research director stated attacks came individuals “ intense discipline ” “ organisation could military ” sophistication evidence pointed toward chinese military people ’ liberation army attackers ‘ titan rain ’ reportedly attacked multiple high-end political systems nasa fbi although sensitive classified information reported stolen hackers however able steal unclassified information e.g information home computer fact information classified somewhat irrelevant comes together could reveal strengths weaknesses u.s. making attack damaging ‘ titan rain ’ caused distrust countries united kingdom russia – superpowers china distrust occurred countries likely attacked either detect attack released statements attacked united kingdom stated officially governmental offices attacked hackers chinese source events ‘ titan rain ’ caused rest world cautious attacks china countries well thereby causing however small slight distrust countries distrust may affect future agreements dealings affect relationship china
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Computer security
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vortex86 vortex86 computing system-on-a-chip soc based core compatible x86 microprocessor family produced dm p electronics originated rise technology vortex86 previously belonged sis got basic design rise technology sis sold dm p electronics taiwan adopting vortex86 series dm p manufactured m6117d intel 386sx compatible 25–40 mhz soc vortex86 cpus implement i586 architecture early versions vortex86 original vortex86sx floating point unit fpu code runs i486sx cpu without 487 run vortex86 code runs i586 use floating point instructions i586 code run vortex86dx later linux kernels build-time option emulate fpu cpu missing one program uses i586-level floating point instructions work vortex86 family cpu kernel albeit slowly model fpu advanced models fpus i686-level instructions fucomi code intended i686 may fail cpu lacks conditional move cmov instruction instruction combines effect conditional branch move instruction compilers asked optimize code advanced cpu example gnu compiler -march=i686 option generate code uses cmov linux systems intended run i686 generally runnable vortex86 gnu c library built i686 uses cmov instruction assembly language strcmp function dynamic loader ld.so uses hence program uses shared libraries even start technically cmov optional i686 architecture intel i686 product pentium pro consequently things generate code typically consider cmov available ask generate code i686 devices vortex86dx3 run fedora 17 i686 live cd successfully unlike use versions vortex86 implies vortex86dx3 implements i686 features others properties vortex86 original cpu reported linux kernel tool codice_1 note cpu later version fpu dm p provides embedded linux distribution customized use socs features netbsd/i386 able boot least dx3 sis55x/rise mp6 simply vortex86 – developed sis three integer mmx pipelines branch prediction 300 mhz 16 kb data 16 kb instruction l1 cache fpu l2 cache use sd ddr2 ram 600 mhz 1 ghz 2.02 w 800 mhz 16 kb data 16 kb instruction l1 cache fpu 256 kb l2 cache 6-staged pipeline address 1 gib ddr2 ram pdx-600 version vortex86dx differs number rs-232 ports 3 instead 5 i²c servo controllers thus targeting embedded industrial market netbooks similar belco 450r use chip package single 581-pin bga package 1 ghz cpu core hardly differs vortex86dx according several sources processor appear implemented simd multi-media instructions mmx version drops conformance isa integrates gpu hd audio controller also integrates udma/100 ide controller consumer grade version known pmx-1000 current models gecko edubook use xcore86 rebadge vortex86mx 32kb write 2-way l1 cache 256kb write through/write back 4-way l2 cache pci rev 2.1 32-bit bus interface 33 mhz ddr2 rom controller ipc internal peripheral controllers dma interrupt timer/counter included fast ethernet fifo uart usb2.0 host ata controller mx+ adds vga controller chip shared memory package single 720-pin bga package 32kb write 4-way l1 cache 16k instruction 16k data 256kb write through/write back 4-way l2 cache pci rev 2.1 32-bit bus interface 33 mhz ddr2 rom controller ipc internal peripheral controllers dma interrupt timer/counter included vga 100 mbps ethernet fifo uart usb2.0 host ata controller enhancements dx include com ports 9 2gb ram hd audio codec well gpio pins package single 720-pin bga package 32kb write 2-way l1 cache 128kb write through/write back 2-way l2 cache pci-e bus interface 300 mhz ddr3 rom controller ipc internal peripheral controllers dma interrupt timer/counter included fast ethernet fifo uart usb2.0 host ata controller package single 288-pin tfbga-package 1.0 ghz dual-core cpu i686-compatible vortex86 eight-way 32k i-cache eight-way 32k d-cache four-way 512 kb l2 cache write-through write-back policy support 2gb ddr3 ram pci-e bus interface 100 mbps ethernet fifo uart usb 2.0 host ata controller ide controller pata 100 2x hdd 2x sd primary channel sata 1.5gbit/s 1 port secondary channel package single 720-pin bga-package ex2 model two asymmetrical master/slave cpu cores master core runs 600mhz 16k i-cache 16k d-cache four-way 128 kb l2 cache write-through write-back policy slave core operates 400 mhz also 16kb i-cache 16kb d-cache l2 cache built-in fpu maximum ddr3 ram capacity 2gb produced using 65nm manufacturing process uses 19x19mm lfbga-441 package
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Computer architecture
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alan woodward computer scientist alan woodward british computer scientist visiting professor university surrey specialist computer security fellow institute physics chartered physicist chartered practitioner chartered engineer fellow british computer society eur ing fellow royal statistical society
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Computer security
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dataflow architecture dataflow architecture computer architecture directly contrasts traditional von neumann architecture control flow architecture dataflow architectures program counter concept executability execution instructions solely determined based availability input arguments instructions order instruction execution unpredictable i.e behavior nondeterministic although commercially successful general-purpose computer hardware used dataflow architecture successfully implemented specialized hardware digital signal processing network routing graphics processing telemetry recently data warehousing also relevant many software architectures today including database engine designs parallel computing frameworks synchronous dataflow architectures tune match workload presented real-time data path applications wire speed packet forwarding dataflow architectures deterministic nature enable programmers manage complex tasks processor load balancing synchronization accesses common resources meanwhile clash terminology since term dataflow used subarea parallel programming dataflow programming hardware architectures dataflow major topic computer architecture research 1970s early 1980s jack dennis mit pioneered field static dataflow architectures manchester dataflow machine mit tagged token architecture major projects dynamic dataflow research however never overcame problems related instructions data dependencies proved fine-grained effectively distributed large network time instructions tagged results travel large connection network longer time actually computations nonetheless out-of-order execution ooe become dominant computing paradigm since 1990s form restricted dataflow paradigm introduced idea execution window execution window follows sequential order von neumann architecture however within window instructions allowed completed data dependency order accomplished cpus dynamically tag data dependencies code execution window logical complexity dynamically keeping track data dependencies restricts ooe cpus small number execution units 2-6 limits execution window sizes range 32 200 instructions much smaller envisioned full dataflow machines designs use conventional memory addresses data dependency tags called static dataflow machines machines allow multiple instances routines executed simultaneously simple tags could differentiate designs use content-addressable memory cam called dynamic dataflow machines use tags memory facilitate parallelism normally control flow architecture compilers analyze program source code data dependencies instructions order better organize instruction sequences binary output files instructions organized sequentially dependency information recorded binaries binaries compiled dataflow machine contain dependency information dataflow compiler records dependencies creating unique tags dependency instead using variable names giving dependency unique tag allows non-dependent code segments binary executed order parallel compiler detects loops break statements various programming control syntax data flow programs loaded cam dynamic dataflow computer tagged operands instruction become available output previous instructions and/or user input instruction marked ready execution execution unit known activating firing instruction instruction completed execution unit output data sent tag cam instructions dependent upon particular datum identified tag value marked ready execution way subsequent instructions executed proper order avoiding race conditions order may differ sequential order envisioned human programmer programmed order instruction along required data operands transmitted execution unit packet also called instruction token similarly output data transmitted back cam data token packetization instructions results allows parallel execution ready instructions large scale dataflow networks deliver instruction tokens execution units return data tokens cam contrast conventional von neumann architecture data tokens permanently stored memory rather transient messages exist transit instruction storage
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Computer architecture
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pitfall ii lost caverns pitfall ii lost caverns platform video game originally released atari 2600 activision 1984 sequel pitfall 1982 games designed programmed david crane star jungle explorer pitfall harry pitfall ii major additions much larger world vertical scrolling rivers swim balloons grabbed float locations released north american video game crash 1983 interest 2600 waning pitfall ii one last major releases console one technically impressive cartridge contains custom display processor chip designed david crane allow improved visuals four channel music instead two system normally capable pitfall ii ported atari 5200 colecovision tandy color computer apple ii atari 8-bit family msx commodore 64 ibm pc compatibles self-booting disk game plot loosely remade super pitfall famicom/nes 1985 sega released arcade version pitfall ii different visual style ported sg-1000 console japan pitfall involved player avoiding danger forms crocodiles scorpions cobras quicksand lost caverns expands scope environment dramatically player descends deep underground addition familiar screen-flipping harry travels right left game adds element vertical scrolling harry falls cliff flies around grabbing onto balloon unlike first game pitfall harry unlimited time lives making impossible lose game harry touches dangerous creature simply loses points moves back last continue point marked red cross touched along journey unlike original pitfall however ground level underground pitfall ii 27 horizontal levels predominantly height stacked atop levels span full eight screens length openly accessible way across portions blocked cave walls force harry travel areas order progress quicksand tar pits replaced rivers chasms balloons let harry ascend new areas two new unplayable characters debut lost caverns quickclaw harry cowardly pet mountain lion rhonda adventure-seeking niece characters also appear harry saturday supercade children cartoon based pitfall games fact rhonda quickclaw created saturday supercade full year game released collecting rhonda quickclaw diamond ring necessary win game versions without second cave upon collection three game ends spot maximum possible score 199,000 differs atari 8-bit 5200 versions see another creature cave rat shown next screen right quickclaw shown beginning game platform harry starting point however harry able reach quickclaw facing rat head-on via third screen hole river advancing left attempts rat push back river addition previous game addition soundtrack musical cues act subtle rewards punishments performance main heroic theme plays short reaching loop acoustic music harry collects treasure main theme begins harry dies slower minor key version theme plays progresses back atmospheric theme finally harry ascends using balloon sobre las olas waves played atari 5200 atari 8-bit versions called adventurer edition title screens contain additional content programmer mike lorenzen reused david crane code 2600 version added entirely new level game would playable initial game finished marketing would allow two versions different demanded additional game stripped atari version instead left easter egg pitfall ii lost caverns named 1 best 25 atari 2600 games time issue 46 retro gamer magazine gamasutra included open world game game design essentials series
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Computer architecture
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carrier-sense multiple access carrier-sense multiple access csma media access control mac protocol node verifies absence traffic transmitting shared transmission medium electrical bus band electromagnetic spectrum transmitter attempts determine whether another transmission progress initiating transmission using carrier-sense mechanism tries detect presence carrier signal another node attempting transmit carrier sensed node waits transmission progress end initiating transmission using csma multiple nodes may turn send receive medium transmissions one node generally received nodes connected medium variations basic csma include addition collision-avoidance collision-detection collision-resolution techniques variations csma use different algorithms determine initiate transmission onto shared medium key distinguishing feature algorithms aggressive persistent initiating transmission aggressive algorithm may begin transmission quickly utilize greater percentage available bandwidth medium typically expense increased likelihood collision transmitters broadcasting vehicular ad hoc networks original 1-persistence p-persistence strategies often cause broadcast storm problem improve performance engineers developed three modified techniques weighted p-persistence slotted 1-persistence slotted p-persistence
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Internet protocols
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macos server macos server product formerly called mac os x server os x server mac os x server stand-alone operating system whereas macos server sold operating system add-on app provides additional server programs along management administration tools ios macos prior version 10.7 lion mac os x server separate similar unix server operating system apple inc. architecturally identical desktop counterpart mac os x release version 10.7 lion mac os x mac os x server combined one release separate server operating system longer sold server-specific server applications work group management administration software tools mac os x server offered macos server add-on package macos sold mac app store 19.99 june 2019 along workgroup manager 10.8 available apple support web site tools simplify access key network services including mail transfer agent afp smb servers ldap server domain name server others also included particularly later versions numerous additional services tools manage web server wiki server chat server calendar server many others mac os x server provided operating system xserve computers rack mounted server computers designed apple also optionally pre-installed mac mini mac pro sold separately use macintosh computer meeting minimum requirements macos server based open source foundation called darwin uses open industry standards protocols included services applications file sharing sharing contact information calendars schedule events send secure instant messages conduct live video conferences send receive email contribute comment wikis publish company-wide blog produce distribute podcasts set websites first version mac os x mac os x server 1.0 mac os x server 1.0 – 1.2v3 based rhapsody hybrid openstep next computer mac os 8.5.1 gui looked like mixture mac os 8 platinum appearance openstep next-based interface included runtime layer called blue box running legacy mac os-based applications within separate window discussion implementing 'transparent blue box would intermix mac os applications written rhapsody yellow box environment would happen mac os x classic environment apple file services macintosh manager quicktime streaming server webobjects netboot included mac os x server 1.0 – 1.2v3 could use firewire devices released may 21 2001 mac os x server 10.0 included new aqua user interface apache php mysql tomcat webdav support macintosh manager netboot released september 25 2001 released august 23 2002 10.2 mac os x server release includes updated open directory user file management release based ldap beginning deprecation next-originated netinfo architecture new workgroup manager interface improved configuration significantly release also saw major updates netboot netinstall many common network services provided ntp snmp web server apache mail server postfix cyrus ldap openldap afp print server inclusion samba version 3 allows tight integration windows clients servers mysql v4.0.16 php v4.3.7 also included released october 24 2003 10.3 mac os x server release includes updated open directory user file management release based ldap beginning deprecation next-originated netinfo architecture new workgroup manager interface improved configuration significantly many common network services provided ntp snmp web server apache mail server postfix cyrus ldap openldap afp print server inclusion samba version 3 allows tight integration windows clients servers mysql v4.0.16 php v4.3.7 also included released april 29 2005 10.4 release adds 64-bit application support access control lists xgrid link aggregation e-mail spam filtering spamassassin virus detection clamav gateway setup assistant servers software update ichat server using xmpp boot camp assistant dashboard weblogs august 10 2006 apple announced first universal binary release mac os x server version 10.4.7 supporting powerpc intel processors time apple announced release intel-based mac pro xserve systems released october 26 2007 leopard server sold 999 unlimited client license features released august 28 2009 snow leopard server sold 499 included unlimited client licenses new features released july 20 2011 releasing developer preview mac os x lion february 2011 apple indicated beginning lion mac os x server would bundled operating system would marketed separate product however months later company said would instead sell server components us 49.99 add-on lion distributed mac app store well lion combined cost upgrade lion purchase os x server add-on costs approximately us 50 nonetheless significantly lower retail cost snow leopard server us 499 lion server came unlimited client licenses snow leopard server lion server includes new versions ical server wiki server mail server significantly lion server used ios mobile device management released july 25 2012 like lion mountain lion separate server edition os x server package available mountain lion mac app store us 19.99 included server management application called server well additional administrative tools manage client profiles xsan mountain lion server like lion server provided unlimited client licenses purchased could run unlimited number systems released october 22 2013 separate server edition mavericks separate server edition mountain lion package available mac app store 19.99 includes server management app called server well additional administrative tools manage client profiles xsan purchased run unlimited number machines enrolled mac ios developer programs given code download os x server free released october 16 2014 separate server edition yosemite separate server edition mavericks package available mac app store 19.99 includes server management app called server well additional administrative tools manage client profiles xsan purchased run unlimited number machines enrolled mac ios developer programs given code download os x server free released september 16 2015 version 5.0.3 os x server operates either os x yosemite 10.10.5 os x el capitan 10.11 released march 21 2016 os x server 5.1 requires 10.11.4 el capitan previous versions os x server ’ work 10.11.4 el capitan released september 20 2016 version 5.2 macos server operates either os x el capitan 10.11 macos sierra 10.12 released march 17 2017 version 5.3 macos server operates macos sierra 10.12.4 later released september 25 2017 version 5.4 macos server operates macos high sierra 10.13 later released january 23 2018 version 5.5 macos server operates macos high sierra 10.13.3 later released april 24 2018 version 5.6 macos server operates macos high sierra 10.13.5 later released september 28 2018 version 5.7 macos server operates macos mojave 10.14 later version apple stopped bundling open source services calendar server contacts server mail server dns dhcp vpn server websites macos server included services limited profile manager open directory xsan released march 25 2019 version 5.8 macos server operates macos mojave 10.14 later profile manager supports new restrictions payloads commands file print services directory services authentication mail services calendaring web hosting collaboration services application servers media streaming client management networking vpn distributed computing high-availability features file systems management features macos server available english japanese french german simplified chinese dutch italian korean spanish traditional chinese
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Operating systems
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byte addressing byte addressing refers hardware architectures support accessing individual bytes data rather larger units called words would word-addressable computers sometimes called byte machines contrast word machines basic unit digital storage called bit storing single 0 1 many common architectures address 8 bits data time example intel 386sx processor handle 16-bit two-byte data since data transferred 16-bit bus however data memory may various lengths 64-bit architecture machine might still need access 8-bit data 64-bit address line data returned bottom 8 bits longer data line byte addressable memory refers architectures data accessed addressed units narrower bus eight-bit processor like intel 8008 addresses eight bits full width bus regarded word-addressable 386sx addresses memory 8-bit units fetch store 16 bits time termed byte-addressable bytes always meant 8 bits fact depending platform byte sizes 1 48 bits used past therefore term octet used context makes byte-length ambiguous example 1980s honeywell mainframes 36-bit words byte-addressable 9-bit bytes nonets used 7- 8-bit character codes either stored one 9-bit byte making characters individually addressable illustrate byte addressing useful consider ibm 7094 word-addressable concept byte 36-bit words stores six-bit character codes six word change 16th character string program determine fourth character third word string fetch third word mask old value fourth character value held register new one store back amended word least six machine instructions usually relegated subroutine every store fetch single character involves overhead calling subroutine returning byte addressing achieved one instruction store character code byte address text programs easier write smaller run faster advantage word addressing memory addressed number bits ibm 7094 15-bit addresses could address 32,768 words 36 bits machines often built full complement addressable memory addressing 32,768 bytes 6 bits would much less useful scientific engineering users consider 32-bit pentium processor 32-bit address bus address 4 billion different items using word addressing 32-bit address bus could address 4 gigawords 16 gigabytes using modern 8-bit byte 386sx successors used word addressing scientists engineers gamers could enjoyed programs 4x larger 32-bit machines word processing rendering html text applications would run slowly computers costly mainly used science engineering word addressing obvious mode became cost-effective use computers handling text hardware designers moved byte addressing systems pdp-10 use word addressing facilitate access individual bytes using special instructions access memory using byte pointer contains word address index specific byte within word
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Computer architecture
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gnome mobile amp embedded initiative gnome mobile embedded initiative gmae also known gnome mobile initiative developing promoting use gnome platform mobile devices announced embedded linux conference santa clara california april 19 2007 gnome mobile strips deprecated components desktop backward compatibility adds mobile-specific components like matchbox window manager window manager optimized mobile integrated devices gnome mobile uses optimizes mainline codebase used desktop merely scaling design smaller form factor
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Operating systems
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rpm package manager rpm package manager rpm originally red hat package manager recursive acronym free open-source package management system name rpm refers file format package manager program rpm intended primarily linux distributions file format baseline package format linux standard base although created use red hat linux rpm used many linux distributions also ported operating systems novell netware version 6.5 sp3 ibm aix version 4 centos fedora fedora project also sponsored red hat oracle linux versions variants linux operating systems use rpm package manager rpm package contain arbitrary set files rpm files “ binary rpms ” brpms containing compiled version software also “ source rpms ” srpms containing source code used build binary package appropriate tag file header distinguishes normal b rpms causing extracted /usr/src installation srpms customarily carry file extension “ .src.rpm ” .spm file systems limited 3 extension characters e.g old dos fat rpm originally written 1997 erik troan marc ewing based experiences system administrator performing software installation maintenance use package management rather manual building advantages simplicity consistency ability processes automated non-interactive features rpm include packages may come within particular distribution example red hat enterprise linux built parties example rpm fusion fedora circular dependencies among mutually dependent rpms so-called dependency hell problematic cases single installation command needs specify relevant packages rpms often collected centrally one repositories internet site often rpm repositories may either act local mirrors internet repositories locally maintained collections useful rpms several front-ends rpm ease process obtaining installing rpms repositories help resolving dependencies include working behind scenes package manager rpm database stored uses berkeley db back-end consists single database containing meta information installed rpms multiple databases created indexing purposes replicating data speed queries database used keep track files changed created user using rpm installs package thus enabling user via rpm reverse changes remove package later database gets corrupted possible rpm client killed index databases recreated command whilst rpm format across different linux distributions detailed conventions guidelines may vary across rpm delivered single file normally filename format example package filename associated source package would named rpms extension depend particular cpu architecture example rpms may contain graphics text programs use may also contain shell scripts programs written interpreted programming languages python rpm contents also include package label contains following pieces information package label fields need match filename libraries distributed two separate packages version one contains precompiled code use run-time second one contains related development files headers etc packages -devel appended name field system administrator ensure versions binary development packages match format binary consists four sections recipe creating rpm package spec file spec files end .spec suffix contain package name version rpm revision number steps build install clean package changelog multiple packages built single rpm spec file desired rpm packages created rpm spec files using rpmbuild tool spec files usually distributed within srpm files contain spec file packaged along source code typical rpm pre-compiled software ready direct installation corresponding source code also distributed done srpm also includes spec file describing software built srpm also allows user compile perhaps modify code software package could contain platform independent scripts case developer could provide srpm still installable rpm special version srpm contains spec file optionally patches include sources usually license two versions rpm development one led fedora project red hat separate group led previous maintainer rpm former employee red hat rpm.org community first major code revision july 2007 version 4.8 released january 2010 version 4.9 march 2011 4.10 may 2012 4.11 january 2013 4.12 september 2014 4.13 july 2015 version used distributions fedora red hat enterprise linux derivatives opensuse suse linux enterprise unity linux mageia openembedded tizen openmandriva lx formerly mandriva jeff johnson rpm maintainer since 1999 continued development efforts together participants several distributions rpm version 5 released may 2007 version used distributions wind river linux wind river linux 10 rosa linux openmandriva lx former mandriva linux switched rpm5 2011 also openpkg project provides packages common unix-platforms openmandriva lx going switch back rpm.org 4.0 release openembedded last major user rpm5 switched back rpm.org due issues rpm5
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Operating systems
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gunther schmidt gunther schmidt born 1939 rüdersdorf german mathematician works also informatics schmidt began studying mathematics 1957 göttingen university studying carl ludwig siegel returned göttingen spending time united states wwii 1960 transferred ludwig-maximilians-universität münchen studied functions several complex variables karl stein schmidt wrote thesis analytic continuation functions 1962 schmidt began work tu münchen students robert sauer beginning labs tutorials later mentoring administration schmidt interests turned toward programming collaborated hans langmaack rewriting braid group 1969 friedrich l. bauer klaus samelson establishing software engineering university schmidt joined group 1974 1977 submitted habilitation programs partial graphs became professor 1980 shortly appointed hold chair late klaus samelson one half years 1988 retirement 2004 held professorship faculty computer science universität der bundeswehr münchen classroom instructor beginners courses well special courses mathematical logic semantics programming languages construction compilers algorithmic languages working thomas strohlein authored textbook relations graphs published german 1989 english 1993 2012 2001 became involved large project 17 nations european cooperation science technology schmidt chairman project cost 274 tarski theory application relational structures knowledge instruments 2014 festschrift organized celebrate 75th year calculus relations relatively low profile among mathematical topics twentieth century schmidt others raised profile partial order binary relations organized grouping closure 2018 schmidt michael winter published relational topology reviews classical mathematical structures binary operations topological space lens calculus relations 1981 participated international summer school marktoberdorf edited lecture notes theoretical foundations programming methodology manfred broy gunther schmidt mainly known work relational mathematics co-founder ramics conference series 1994 textbooks calculus relations exhibit applications potential algebraic logic
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Programming language topics
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paper generator paper generator computer software composes scholarly papers style appear academic journals conference proceedings typically generator uses technical jargon field compose sentences grammatically correct seem erudite actually nonsensical prose supported tables figures references may valid randomly inserted rather relevant examples include postmodernism generator snarxiv scigen latter used generate many computer science papers accepted publication
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Computational linguistics
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malta maritime authority malta maritime authority mma awtorità marittima ta malta used independent state corporation government agency responsible governance operation regulation promotion ports mediterranean archipelago nation malta operation principal cargo port malta freeport done conjunction malta freeport terminals company established 1988 malta smaller ports provide service pleasure craft yacht marinas ferry services fishing industry local trade mma ports directorate port authority ports malta malta international ship register department mma 2010 mma longer exists separate entity forms part transport malta governmental institution encompasses transport control islands sea land air malta rich maritime heritage principal ports include
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Databases
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android oreo android oreo codenamed android development eighth major release 15th version android mobile operating system first released alpha quality developer preview march 2017 released public august 21 2017 contains number major features including notification grouping picture-in-picture support video performance improvements battery usage optimization support autofillers bluetooth 5 system-level integration voip apps wide color gamuts wi-fi aware android oreo also introduces two major platform features android go – software distribution operating system low-end devices – support implementing hardware abstraction layer 28.3 android devices run oreo 12.9 8.0 15.4 8.1 making oreo major release commonly used version android android oreo internally codenamed oatmeal cookie march 21 2017 google released first developer preview android available nexus 5x nexus 6p nexus player pixel c pixel smartphones second considered beta quality released may 17 2017 third developer preview released june 8 2017 offered finalized version api dp3 finalized release api api level 26 changed camera ui reverted wi-fi cellular connectivity levels status bar back wi-fi left added themed notifications added battery animation settings battery new icon darker background clock app teardrop icon shape apps july 24 2017 fourth developer preview released included final system behaviors latest bug fixes optimizations android officially released august 21 2017 name oreo lawn statue unveiled promotional event across chelsea market new york city—a building formerly housed nabisco factory oreo cookies first produced factory images made available compatible pixel nexus devices later day sony xperia xz1 sony xperia xz1 compact first devices available oreo pre-installed android 8.1 released december 2017 pixel nexus devices features minor bug fixes user interface changes notifications snoozed batched topic-based groups known channels 'major ongoing feature orders alerts priority pinning important application top slot android oreo contains integrated support picture-in-picture modes supported youtube app youtube premium subscribers settings app features new design white theme deeper categorization different settings ringtone alarm notification sound settings contain option adding custom sounds list android 8.1 update supports display battery percentages connected bluetooth devices makes notification shade slightly translucent dims on-screen navigation keys order reduce possibility burn-in android oreo adds support neighborhood aware networking nan wi-fi based wi-fi aware bluetooth 5 wide color gamuts apps api autofillers multiprocess google browsing support webviews api allow system-level integration voip apps launching activities remote displays android runtime art features performance improvements android oreo contains additional limits apps background activities order improve battery life apps specify adaptive icons differently-shaped containers specified themes circles squares squircles android oreo supports new emoji included unicode 10 standard new emoji font also introduced notably redesigns face figures use traditional circular shape opposed blob design introduced kitkat underlying architecture android revised low-level vendor-specific code supporting device hardware separated android os framework using hardware abstraction layer known vendor interface vendor interfaces must made forward compatible future versions android new architecture called project treble allows quicker development deployment android updates devices vendors would need make necessary modifications bundled software devices shipping oreo must support vendor interface feature optional devices updated oreo earlier version seamless updates system introduced android 7.0 also modified download update files directly system partition rather requiring downloaded user partition first reduces storage space requirements system updates android oreo introduces new automatic repair system known rescue party operating system detects core system components persistently crashing startup automatically perform series escalating repair steps automatic repair steps exhausted device reboot recovery mode offer perform factory reset android 8.1 update also introduces neural network api designed provide apps hardware acceleration on-device machine learning operations api designed use machine learning platforms tensorflow lite specialized co-processors pixel visual core featured google pixel 2 smartphones dormant 8.1 installed also provides cpu fallback mode tailored distribution low-end devices known android go unveiled oreo intended devices 1 gb ram less mode platform optimizations designed reduce mobile data usage including enabling data saver mode default special suite google mobile services designed less resource- bandwidth-intensive google play store also highlight lightweight apps suited devices operating system interface also modified quick settings panel providing greater prominence information regarding battery mobile data limit available storage recent apps menu using modified layout limited four apps order reduce ram consumption api allowing mobile carriers implement data tracking top-ups within android settings menu google play services also modularized reduce memory footprint android go made available oems android 8.1 android oreo re-brands automatic scanning google play store sideloaded apps google play protect gives feature well find device formerly android device manager higher prominence security menu settings app opposed single system-wide setting enabling installation apps sources outside google play store function implemented permission granted individual apps i.e clients third-party app repositories amazon appstore f-droid verified boot includes rollback protection feature enforces restriction rolling back device previous version android aimed preventing potential thief bypassing security measures installing previous version operating system n't place
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Operating systems
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comparison javascript engines dom support following tables compare document object model dom compatibility support number javascript engines used web browsers features fully supported based dom level 2 dom level 3 modules w3c recommendation exact version number given certain feature added version dom level 0 dom level 3 modules still development included see list ecmascript engines full list interfaces within section considered fundamental must fully implemented conforming implementations dom including html dom implementations interfaces defined form part dom core specification objects expose interfaces never encountered dom implementation deals html interfaces found within section mandatory section extends dom core api describe objects methods specific html documents xhtml documents general functionality needed manipulate hierarchical document structures elements attributes found core section functionality depends specific elements defined html found section elements deprecated since html 4.01 listed elements attributes listed deprecated xhtml 1.1 example presentation attributes image maps frames targets interfaces found within section mandatory interfaces section base interfaces used represent type style sheet interfaces within section considered fundamental css interfaces must supported conforming implementations css module interfaces represent css style sheets specifically interfaces found within section mandatory interfaces found within section mandatory first goal design generic event system allows registration event handlers describes event flow tree structure provides basic contextual information event second goal event model provide common subset current event systems used dom level 0 browsers see also dom events details interfaces found within section mandatory document may one views associated e.g. computed view document applying css stylesheet multiple presentations e.g html frame document client view alternate representation presentation associated source document interfaces found within section mandatory interfaces provide easy-to-use robust selective traversal document contents interfaces found within section mandatory includes methods creating moving range methods manipulating content ranges interfaces within section considered fundamental must fully implemented conforming implementations dom load save module interfaces found within section mandatory module provides interfaces guide construction editing xml documents examples guided editing queries like combine questions like schema allow insert/delete insert/delete document still valid
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Programming language topics
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ip avian carriers computer networking ip avian carriers ipoac proposal carry internet protocol ip traffic birds homing pigeons ip avian carriers initially described rfc 1149 request comments rfc issued internet engineering task force ietf written d. waitzman released april 1 1990 one several april fools day request comments waitzman described improvement protocol rfc 2549 ip avian carriers quality service 1 april 1999 later rfc 6214—released 1 april 2011 13 years introduction ipv6—carpenter hinden published adaptation rfc 1149 ipv6 ipoac successfully implemented nine packets data packet loss ratio 55 due operator error response time ranging 3,000 seconds ≈54 minutes 6,000 seconds ≈1.77 hours thus technology suffers poor latency nevertheless large transfers avian carriers capable high average throughput carrying flash memory devices effectively implementing sneakernet last 20 years information density storage media thus bandwidth avian carrier increased 3 times fast bandwidth internet ipoac may achieve bandwidth peaks orders magnitude internet used multiple avian carriers rural areas example 16 homing pigeons given eight 512 gb sd cards take hour reach destination throughput transfer would 145.6 gbit/s excluding transfer sd cards 28 april 2001 ipoac actually implemented bergen linux user group name cpip carrier pigeon internet protocol sent nine packets distance approximately five kilometers three miles carried individual pigeon containing one ping icmp echo request received four responses real life implementation mentioned french mp martine billard french assemblée nationale debates hadopi implementation noted song paper pings steve savitzky december 2005 gartner report bird flu concluded “ pandemic would n't affect systems directly ” humorously criticized neglecting consider rfc 1149 rfc 2549 analysis although collisions unlikely packets lost particularly raptors rafting photographers already use pigeons sneakernet transport digital photos flash media camera tour operator 30-mile distance single pigeon may able carry tens gigabytes data around hour average bandwidth basis compares favorably current adsl standards even accounting lost drives march 12 2004 yossi vardi ami ben-bassat guy vardi sent 3 homing pigeons 100 km distance carrying 20-22 tiny memory cards msystems disk-on-chip containing 1.3 gb amounting total 4 gb data achieving effective throughput 2.27 mbps purpose test measure confirm improvement rfc 2549 since developers used flash memory instead paper notes specified rfc 2549 experiment widely criticized example optimized implementation breaks official standard inspired rfc 2549 9 september 2009 marketing team unlimited regional company south africa decided host tongue-in-cheek pigeon race pet pigeon winston local telecom company telkom sa race send 4 gigabytes data howick hillcrest approximately 60 km apart pigeon carried microsd card competed telkom adsl line winston beat data transfer telkom adsl line total time two hours six minutes 57 seconds uploading data microsd card completion download card time winston victory adsl transfer 4 complete november 2009 australian comedy/current-affairs television program hungry beast repeated experiment hungry beast team took challenge fiery parliament session wherein government time blasted opposition supporting telecommunications investments saying opposition way australians would data transfer carrier pigeons hungry beast team read south african experiment assumed developed western country australia would higher speeds experiment team transfer 700mb file via three delivery methods determine fastest carrier pigeon microsd card car carrying usb stick telstra australia largest telecom provider adsl line data transferred tarana rural new south wales western-sydney suburb prospect new south wales distance 132 km road approximately halfway race internet connection unexpectedly dropped transfer restarted pigeon race time approximately 1 hour 5 minutes car came second 2 hours 10 minutes internet transfer finish dropped second time coming back estimated time upload completion one point high 9 hours point estimated upload time fall 4 hours similar pigeon race conducted september 2010 tech blogger trefor.net isp timico cto trefor davies farmer michelle brumfield rural yorkshire england delivering five-minute video bbc correspondent 75 miles away skegness pigeon pitted carrying memory card 300mb hd video davies haircut upload youtube via british telecom broadband pigeon released 11.05 arrived loft one hour fifteen minutes later upload still incomplete failed interim
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Internet protocols
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windows embedded compact 7 windows embedded compact 7 formerly known windows embedded ce 7.0 seventh major release windows embedded ce operating system windows embedded compact 7 real-time os separate windows nt line designed target enterprise specific tools industrial controllers consumer electronics devices digital cameras gps systems also automotive infotainment systems windows embedded compact designed run multiple cpu architectures supports x86 sh automotive arm development microsoft employee working division claimed microsoft working hard release shares underlying kernel windows phone microsoft officially confirmed said windows phone 7 based windows embedded ce 6.0 r3 features borrowed windows embedded compact 7 thus making hybrid solution windows embedded compact 7 released march 1 2011 windows embedded compact 7 contains features
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Operating systems
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datareader ado.net datareader broad category objects used sequentially read data data source datareaders provide efficient way access data thought firehose cursor asp classic except server-side cursor used datareader parses tabular data stream microsoft sql server methods retrieving data sources datareader usually accompanied command object contains query optionally parameters connection object run query datareader class ado.net number classes implement idatareader interface datareaders small footprint good performance tailor-made task hand however makes difficult write application moved one backend data source another provider-specific datareaders expose types used underlying database example values null microsoft sql server .net framework prior version 2.0 using datareader retrieve data developer choose read field values strongly typed manner example weakly typed manner returning example approaches pros cons using strongly typed retrieval methods cumbersome especially without specific knowledge underlying data numeric values database translate several .net types trying retrieve value using wrong type results exception thrown stops code running slows application also true use right type encounter value avoided using boolean function datareader class benefit retrieval method data validation performed sooner improving probability data correction possible weakly typed data retrieval allows quick code writing allows data used fashion developer n't know beforehand types returned effort programmer extract value variable proper type using methods datareader datareader cases used place datatable however many programmers experienced connection bloat following approach datareader used already open database connection connection n't closed datareader method called exception thrown data processed example described strong weak typing method never called developer writes code explicitly declaring disposing datareader without use block c construct good way avoid problem shown code example sample accessing sql data using datareader
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Operating systems
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kernelcare kernelcare live kernel patching service provides security patches bugfixes range popular linux kernels installed without rebooting system kernelcare software released gpl2 first beta introduced march 2014 commercially launched may 2014 kernelcare supports centos/rhel 5.x 6.x 7.x cloudlinux 5.x 6.x 7.x parallels cloud server oracle linux/rhel 6.x 7.x amazon linux virtuozzo openvz rhel6/rhel proxmox 3.x 4.x 5.x virt-sig/xen4centos debian 6.x 7.x 8.x 9.x ubuntu 14.04 lts 16.04 lts 18.04 lts kernelcare agent resides user server periodically checks kernelcare distribution servers new patches available currently running kernel kernelcare agent downloads applies patches running kernel kernelcare patch piece code used substitute vulnerable buggy code kernel arbitrary code line modification missing security check set functions even modified data structures patch compiled usual generated code additional information changed code pieces caused original source code modification information apply code pieces resulting code modifications safely applied running kernel special kernelcare kernel module applies patches loads patches kernel address space sets relocations i.e. fixes references original kernel code data safely switches execution path original code updated code blocks code ensures patch applied safely cpu n't execute original code blocks moment switching new version
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Operating systems
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fsck system utility fsck file system consistency check tool checking consistency file system unix unix-like operating systems linux macos freebsd similar command chkdsk exists microsoft windows ancestor ms-dos agreed pronunciation pronounced f-s-c-k f-s-check fizz-check f-sack fisk fizik f-sick f-sock f-sek feshk sibilant fsk fix farsk fusk generally fsck run either automatically boot time manually system administrator command works directly data structures stored disk internal specific particular file system use fsck command tailored file system generally required exact behaviors various fsck implementations vary typically follow common order internal operations provide common command-line interface user fsck utilities provide options either interactively repairing damaged file systems user must decide fix specific problems automatically deciding fix specific problems user answer questions reviewing problems need resolved file system without actually fixing partially recovered files original file name reconstructed typically recovered lost+found directory stored root file system system administrator also run fsck manually believe problem file system file system normally checked unmounted mounted read-only system special maintenance mode modern journaling file systems designed tools fsck need run unclean shutdown i.e crash ufs2 file system freebsd background fsck usually necessary wait fsck finish accessing disk full copy-on-write file systems zfs btrfs designed avoid causes corruption traditional fsck repair tool scrub utility examines repairs problems background mounted file system equivalent programs microsoft windows ms-dos chkdsk scandisk severity file system corruption led terms fsck fscked becoming used among unix system administrators minced oath fuck fucked unclear whether usage cause effect report question answer session usenix 1998 claims fsck originally different name go fsck occasionally used online injunction person go correct issue attitude ignorance subject matter etc way running fsck involves fixing fundamental errors following example checks file system configured mounted /usr partition file system needs unmounted first following example checks linux jfs file system mdadm software raid device
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Computer file systems
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breach breach backronym browser reconnaissance exfiltration via adaptive compression hypertext security exploit https using http compression breach built based crime security exploit breach announced august 2013 black hat conference security researchers angelo prado neal harris yoel gluck idea discussed community announcement crime attack presented general attack could work effectively large number protocols exploits spdy request compression tls compression demonstrated largely mitigated browsers servers crime exploit http compression mitigated even though authors crime warned vulnerability might even widespread spdy tls compression combined breach instance crime attack http compression—the use gzip deflate data compression algorithms via content-encoding option within http many web browsers servers given compression oracle rest breach attack follows general lines crime exploit performing initial blind brute-force search guess bytes followed divide-and-conquer search expand correct guess arbitrarily large amount content breach exploits compression underlying http protocol therefore turning tls compression makes difference breach still perform chosen-plaintext attack http payload result clients servers either forced disable http compression completely thus reducing performance adopt workarounds try foil breach individual attack scenarios using cross-site request forgery csrf protection another suggested approach disable http compression whenever referrer header indicates cross-site request header present approach allows effective mitigation attack without losing functionality incurring performance penalty affected requests around 2013-2014 ietf draft proposal tls extension length-hiding padding theory could used mitigation attack allows actual length tls payload disguised insertion padding round fixed set lengths randomize external length thereby decreasing likelihood detecting small changes compression ratio basis breach attack however draft since expired without action
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Computer security
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self-service password reset self-service password reset sspr defined process technology allows users either forgotten password triggered intruder lockout authenticate alternate factor repair problem without calling help desk common feature identity management software often bundled software package password synchronization capability typically users forgotten password launch self-service application extension workstation login prompt using another user web browser telephone call users establish identity without using forgotten disabled password answering series personal questions using hardware authentication token responding notification e-mail less often providing biometric sample voice recognition users either specify new unlocked password ask randomly generated one provided self-service password reset expedites problem resolution users fact thus reduces help desk call volume also used ensure password problems resolved adequate user authentication eliminating important weakness many help desks social engineering attacks intruder calls help desk pretends intended victim user claims forgotten account password asks new password rather merely asking users answer security questions modern password reset systems may also leverage sequence authentication steps despite benefits self-service password reset relies solely answers personal questions introduce new vulnerabilities since answers questions often obtained social engineering phishing techniques simple research users frequently reminded never reveal password less likely treat sensitive answers many commonly used security questions pet names place birth favorite movie much information may publicly available users personal home pages answers elicited someone pretending conduct opinion survey offering free dating service since many organizations standard ways determining login names real names attacker knows names several employees organization choose one whose security answers readily obtained vulnerability strictly due self-service password reset—it often exists help desk prior deployment automation self-service password reset technology often used reduce type vulnerability introducing stronger caller authentication factors human-operated help desk using prior deployment automation september 2008 yahoo e-mail account governor alaska vice president united states nominee sarah palin accessed without authorization someone able research answers two security questions zip code date birth able guess third met husband incident clearly highlighted choice security questions important prevent social engineering attacks password systems jakobsson stolterman wetzel yang proposed use preferences authenticate users password reset underlying insights preferences stable long period time publicly recorded approach includes two phases -- setup authentication setup user asked select items either like dislike several categories items dynamically selected big candidate set presented user random order authentication phase users asked classify preferences like dislike selected items displayed random order jakobsson stolterman wetzel yang evaluated security approach user experiments user emulations attacker simulations two-factor authentication 'strong authentication method adds another layer security password reset process cases consists preference based authentication plus second form physical authentication using something user possesses i.e smartcards usb tokens etc. one popular method sms email advanced sspr software requires user provide mobile phone number personal e-mail address setup event password reset pin code sent user phone email need enter code password reset process modern technology also allows authentication via voice biometrics using voice recognition technology major problem self-service password reset inside corporations similar organizations enabling users access system forgot primary password since sspr systems typically web-based users need launch web browser fix problem yet log workstation problem solved various approaches addressing catch-22 compromises e.g. desktop software deployment domain-wide password reset account telephone access visiting neighbour continuing call help desk etc. companies created software presents restricted web browser login screen sole ability access password reset page without logging system example novell client login extension technology technologies effectively give user access computer resources specifically web browser reset passwords without authenticating computer security high priority capabilities limited user expected mode two additional problems related one locked users conjunction preference-based authentication self-service password reset procedures could also rely network existing human relations among users scenario user forgot password asks colleague assistance helper colleague authenticates password reset application vouches user identity scenario problem changes one authenticating user forgot password one understanding users ability vouch users
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Computer security
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absolute linux absolute linux lightweight linux distribution works older hardware based slackware linux client designed everyday use internet multimedia documents absolute linux default file window managers icewm rox programs offered default include gimp libreoffice firefox xfburn p7zip qbittorrent many script utilities included absolute linux aid configuration maintenance system
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Operating systems
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tinfoil hat linux tinfoil hat linux thl compact security-focused linux distribution designed high security developed shmoo group first version 1.000 released february 2002 appears low priority project image files source available gzip format thl used almost modern pc requires intel 80386 better computer least 8 mb ram distribution fits single hd floppy small footprint provides additional benefits beyond making system easy understand verify- computer need even hard drive making easier sanitize computer use logo tinfoil hat tux linux mascot wearing tinfoil hat tinfoil hat uses number measures defeat hardware software surveillance methods like keystroke logging video camera tempest advantage thl used virtually modern pc using x86 processor architecture example one might install computer kept locked room connected network used cryptographically signing keys fairly easy create tinfoil hat booting floppy microsoft windows verifying checksum tricky text documentation salted jokes reinforces humor stark contrast serious paranoiac tone surrounding text- name pokes fun tinfoil hats commonly ascribed paranoiacs method protecting oneself mind-control waves tinfoil hat linux requires one work text-only environment linux i.e starting straight bourne shell editor vi graphical user interface uses busybox instead normal util-linux gnu coreutils formerly known fileutils shellutils textutils common unix tools tinfoil hat also offers gnu nano text editor
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Operating systems
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christien rioux christien rioux also known handle dildog co-founder chief scientist burlington massachusetts based company veracode main patent holder educated mit rioux computer security researcher l0pht heavy industries company stake later bought symantec stake looked security weaknesses software led development smart risk analyzer sra co-authored best-selling windows password auditing tool stake lc l0phtcrack antisniff network intrusion detection system also member cult dead cow ninja strike force formerly member l0pht dildog best known author original code back orifice 2000 open source remote administration tool also well known author tao windows buffer overflow
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Computer security
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school app school ios android social network mobile application allows users defined network currently high schools share anonymous text-based posts images others july 2016 school users 20,000 american high schools according ceo michael callahan app created network “ teens could use express reach others ask offer help fellow teens distress. ” app created michael callahan cory levy one inc. debuted mid-november 2014 re-release app april 2015 school implemented “ mature content ” filters age verification 24/7 live anonymous support first fastest internet response system threats february 2016 school announced raising 16.4 million series round app also detects threatening harmful messages using language algorithms enforces single-report immediate user removal violations
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Operating systems
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ftp bounce attack ftp bounce attack exploit ftp protocol whereby attacker able use port command request access ports indirectly use victim machine middle man request technique used port scan hosts discreetly access specific ports attacker access direct connection example nmap port scanner nearly modern ftp server programs configured default refuse port commands would connect host originating host thwarting ftp bounce attacks
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Computer security
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flock web browser flock discontinued web browser specialized providing social networking web 2.0 facilities built user interface earlier versions flock used gecko html rendering engine mozilla version 2.6.2 released january 27 2011 last version based mozilla firefox starting version 3 flock based chromium used webkit rendering engine flock available free download supported microsoft windows mac os x one time linux well support flock discontinued april 2011 flock successor round two raised money bessemer venture partners catamount ventures shasta ventures angel investors bart decrem geoffrey arone co-founded company flock raised 15 million fourth round funding led fidelity ventures may 22 2008 estimated total 30 million according cnet company previous investors bessemer venture partners catamount ventures shasta ventures also participated round january 2011 flock inc. acquired zynga browser discontinued support ending april 26 2011 flock 2.5 integrated social networking media services including myspace facebook youtube twitter flickr blogger gmail yahoo mail etc logging supported social services flock could track updates friends profiles uploaded photos flock latest 2.5 version added twitter search functionality multi-casting status updates multiple services introduction instant messaging via facebook chat browser features include december 2007 flock mashable open web awards applications widgets march 2008 flock south southwest web award community cnet gave mac os x version flock 1.0 title best mac software 2007 pc world harry mccracken reviewed flock new favorite web browser february 2008 aol announced would discontinue support netscape browser recommended flock firefox alternative browsers userbase netscape 9 users netscape 8 userbase aol recommended flock browser users march 2008 flock announced seen nearly 3 million downloads 135 increase active users first two months 2008 also announced 70 percent flock users making default browser choice may 2008 flock social networking category webby awards flock nominated award along facebook bebo ning flock discontinuation announced april 2011 reviewer joey sneddon omg ubuntu offered analysis whether poor implementation design wise one needs glance 'rockmelt example social browser done right general apathy towards alerts twitter flickr facebook digg et al face time moot flock flocked innovation never quite lived hype upon exiting beta flock number awards
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Internet protocols
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waits waits heavily modified variant digital equipment corporation monitor operating system later renamed better known tops-10 pdp-6 pdp-10 mainframe computers used stanford artificial intelligence laboratory sail mid-1960s 1991 mainframe computer ran also went name sail never official expansion waits common variant west-coast alternative another variant worst acronym invented timesharing system name endorsed sail community public vote choosing among alternatives two contenders saints stanford ai new timesharing system sinners stanford incompatible non-new extensively rewritten system proposed systems programmers though waits less visible frequent exchange people ideas two communities innovations pioneered waits exerted enormous indirect influence waits alumni xerox parc elsewhere also played major roles developments led xerox star apple macintosh sun workstation later sold sun microsystems early screen modes emacs example directly inspired waits e editor -- one family editors first real-time editing editing commands invisible one typed text point insertion/overwriting modern style multi-region windowing said originated system also featured unusual level support called multimedia computing allowing analog audio video signals including tv radio switched programming terminals switching capability terminal video even allowed users separate offices view type virtual terminal single user instantly switch among multiple full virtual terminals also invented bucky bits thus alt key every ibm pc waits legacy one waits feature notable pre-web days news-wire search engine called ns news service allowed waits hackers instantly find store notified selected ap new york times news-wire stories searches using arbitrary combinations words news story retrieval search instantaneous story automatically indexed words came wire
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Operating systems
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universal data element framework universal data element framework udef controlled vocabulary developed open group provided framework categorizing naming indexing data assigned every item data structured alphanumeric tag plus controlled vocabulary name describes meaning data allowed relating data elements similar elements defined organizations udef defined dewey-decimal like code concept example employee number often used human resource management udef tag a.5_12.35.8 controlled vocabulary description employee.person_employer.assigned.identifier udef superseded open data element framework o-def application used hospital last name first name several people could include following example concepts examples following udef ids available
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Computer architecture
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cryptgenrandom cryptgenrandom deprecated cryptographically secure pseudorandom number generator function included microsoft cryptoapi win32 programs microsoft recommends use anywhere random number generation needed 2007 paper hebrew university suggested security problems windows 2000 implementation cryptgenrandom assuming attacker control machine microsoft later acknowledged problems exist windows xp vista microsoft released fix bug windows xp service pack 3 mid-2008 win32 api includes comprehensive support cryptographic security including native tls support via schannel api code signing capabilities built native windows libraries cryptographic operations rsa aes key generation libraries turn rely cryptographically secure pseudorandom number generator csprng cryptgenrandom standard csprng win32 programming environment microsoft-provided cryptography providers share implementation cryptgenrandom currently based internal function called rtlgenrandom general outline algorithm published rtlgenrandom generates specified fips 186-2 appendix 3.1 sha-1 g function entropy nowiki /nowiki omitted long lists low-level system information fields performance counters nowiki /nowiki security cryptosystem csprng significant origin dynamic key material keys needed fly aes tls session keys protect https sessions bank websites originate csprngs pseudorandom numbers predictable session keys predictable well cryptgenrandom de facto standard csprng win32 environments security critical windows users specifics cryptgenrandom algorithm officially published unpublished random number generation algorithm may susceptible theoretical weaknesses including use outdated algorithms reliance entropy gathering several monotonically-increasing counters might estimated controlled extent attacker local access system cryptanalysis cryptgenrandom published november 2007 leo dorrendorf others hebrew university jerusalem university haifa found significant weaknesses windows 2000 implementation algorithm take advantage vulnerability attacker would first need compromise program running random number generator weaknesses paper depend attacker siphoning state bits generator attacker position carry attack would typically already position defeat random number generator instance simply sniff outputs generator fix memory known values however hebrew university team notes attacker need steal state bits order persistently violate security cryptgenrandom instance also use information glean determine past random numbers generated potentially compromising information credit card numbers already sent paper attacks based fact cryptgenrandom uses stream cipher rc4 run backwards state known also take advantage fact cryptgenrandom runs user mode allowing anyone gains access operating system user level example exploiting buffer overflow get cryptgenrandom state information process finally cryptgenrandom refreshes seed entropy infrequently problem aggravated fact win32 process instance cryptgenrandom state means compromise one process transitively compromise every process may also increase longevity successful break details cryptgenrandom algorithm public dorrendorf team used reverse engineering tools discern algorithm works paper first published record windows cryptographic random number generator operates windows 2000 xp 2003 successfully undergone eal4+ evaluations including cryptgenrandom fipsgenrandom implementations security target documentation available common criteria portal indicates compliance eal4 requirements conclusions drawn security algorithm result eal4 measures products best practices stated security objectives rarely involves in-depth cryptanalysis microsoft obtained validation rng implementations following environments tests designed test conformance various approved rng specifications rather provide measure product ’ security ... thus validation interpreted evaluation endorsement overall product security conclusions drawn security algorithm result fips evaluations necessarily inspect source code evaluate way rng seeds generated windows developers several alternative means accessing cryptgenrandom functionality alternatives invoke algorithm share security characteristics may advantages historically always told developers use functions rand generate keys nonces passwords rather use functions like cryptgenrandom creates cryptographically secure random numbers problem cryptgenrandom need pull cryptoapi cryptacquirecontext fine 're using crypto functions default windows xp later install cryptgenrandom calls function named advapi32 rtlgenrandom require load cryptapi stuff fact new whidbey crt function rand_s calls rtlgenrandom programmers using .net use rngcryptoserviceprovider class cng long term replacement deprecated crypto api provides equivalent function bcryptgenrandom well dedicated functions key generation
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Operating systems
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logical link control ieee 802 reference model computer networking logical link control llc data communication protocol layer upper sublayer data link layer layer 2 seven-layer osi model llc sublayer provides multiplexing mechanisms make possible several network protocols e.g ip ipx decnet appletalk coexist within multipoint network transported network medium also provide flow control automatic repeat request arq error management mechanisms llc sublayer acts interface media access control mac sublayer network layer llc sublayer primarily concerned multiplexing protocols transmitted mac layer transmitting demultiplexing receiving also provide node-to-node flow control error management flow control error management capabilities llc sublayer used protocols netbios frames protocol however protocol stacks running atop 802.2 use llc sublayer flow control error management cases flow control error management taken care transport layer protocol tcp application layer protocol higher layer protocols work end-to-end fashion i.e re-transmission done original source final destination rather individual physical segments protocol stacks multiplexing capabilities llc sublayer used llc sublayer key component early packet switching networks x.25 networks lapb data link layer protocol flow control error management carried node-to-node fashion meaning error detected frame frame retransmitted one switch next instead extensive handshaking nodes made networks slow ieee 802.2 standard specifies llc sublayer ieee 802 local area networks ieee 802.3/ethernet ethertype field used ieee 802.5 ieee 802.11 ieee 802.2 also used non-ieee 802 networks fddi since bit errors rare wired networks ethernet provide flow control automatic repeat request arq meaning incorrect packets detected cancelled retransmitted except case collisions detected csma/cd mac layer protocol instead retransmissions rely higher layer protocols ethertype ethernet frame using ethernet ii framing used multiplex different protocols top ethernet mac header seen llc identifier however ethernet frames lacking ethertype llc identifier ethernet header instead use ieee 802.2 llc header ethernet header provide protocol multiplexing function wireless communications bit errors common wireless networks ieee 802.11 flow control error management part csma/ca mac protocol part llc layer llc sublayer follows ieee 802.2 standard non-ieee 802 protocols thought split mac llc layers example hdlc specifies mac functions framing packets llc functions protocol multiplexing flow control detection error control retransmission dropped packets indicated protocols cisco hdlc use hdlc-like packet framing llc protocol telephone network modems ppp link layer protocols considered llc protocol providing multiplexing provide flow control error management telephone network bit errors might common meaning error management crucial today provided modern protocols today modem protocols inherited llc features older lapm link layer protocol made modem communication old x.25 networks gprs llc layer also ciphering deciphering sn-pdu sndcp packets another example data link layer split llc flow error control mac multiple access itu-t g.hn standard provides high-speed local area networking existing home wiring power lines phone lines coaxial cables
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Internet protocols
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image mastering api image mastering application programming interface imapi component microsoft windows operating system used cd dvd authoring recording windows applications windows media player windows media center windows movie maker windows dvd maker windows explorer use imapi create iso images burn discs windows refers discs created using imapi mastered burns contrast term live file system implies packet writing use imapi imapi originally introduced windows xp imapi version 2.0 released windows vista windows server 2008 26 june 2007 version released update windows xp windows server 2003 microsoft received requests hardware software vendors 19 january 2009 microsoft released windows feature pack storage 1.0 update allows imapi 2.0 support recordable blu-ray disc bd-r rewritable blu-ray disc bd-re media also adds support universal disk format udf 2.5 file system windows feature pack storage available windows xp later integrated windows 7 imapi provides ability create burn single-session multi-session discs including bootable discs also provides low-level access burn engine developing support new devices well access extended recorder properties imapi supports every major writable cd dvd format including imapi supports writing disks iso 9660 including cdda audio joliet imapi v2.0 also supports writing discs universal disk format file system imapi version 2.0 supports following additional features unlike imapi version 1.0 imapi version 2.0 implemented dll rather windows service imapi 2.0 suffers limitations notably allow filesystem imported raw image .iso file optical drive effect means generate disk images used modify
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Operating systems
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copy-on-write copy-on-write cow cow sometimes referred implicit sharing shadowing resource-management technique used computer programming efficiently implement duplicate copy operation modifiable resources resource duplicated modified necessary create new resource resource shared copy original modifications must still create copy hence technique copy operation deferred first write sharing resources way possible significantly reduce resource consumption unmodified copies adding small overhead resource-modifying operations copy-on-write finds main use sharing virtual memory operating system processes implementation fork system call typically process modify memory immediately executes new process replacing address space entirely thus would wasteful copy process memory fork instead copy-on-write technique used copy-on-write implemented efficiently using page table marking certain pages memory read-only keeping count number references page data written pages kernel intercepts write attempt allocates new physical page initialized copy-on-write data although allocation skipped one reference kernel updates page table new writable page decrements number references performs write new allocation ensures change memory one process visible another copy-on-write technique extended support efficient memory allocation page physical memory filled zeros memory allocated pages returned refer page zeros marked copy-on-write way physical memory allocated process data written allowing processes reserve virtual memory physical memory use memory sparsely risk running virtual address space combined algorithm similar demand paging copy-on-write pages also used linux kernel kernel same-page merging feature loading libraries application also use copy-on-write technique dynamic linker maps libraries private like follows writing action libraries trigger cow virtual memory management codice_1 cow also used library application system code multithreaded systems cow implemented without use traditional locking instead use compare-and-swap increment decrement internal reference counter since original resource never altered safely copied multiple threads reference count increased without need performance-expensive locking mutexes reference counter turns 0 definition 1 thread holding reference resource safely de-allocated memory without use performance-expensive locking mechanisms benefit copy resource resulting performance gain traditional deep-copying therefore valid single- multithreaded systems string class provided c++ standard library specifically designed allow copy-on-write implementations initial c++98 standard newer c++11 standard php programming language types except references implemented copy-on-write example strings arrays passed reference modified duplicated non-zero reference counts allows act value types without performance problems copying assignment making immutable qt framework many types copy-on-write implicitly shared qt terms qt uses atomic compare-and-swap operations increment decrement internal reference counter since copies cheap qt types often safely used multiple threads without need locking mechanisms mutexes benefits cow thus valid single- multithreaded systems cow may also used underlying mechanism snapshots provided logical volume management file systems btrfs zfs database servers microsoft sql server typically snapshots store modified data stored close main array weak form incremental backup substitute full backup systems also use cow technique avoid fuzzy backups otherwise incurred file set files backed changes backup implementing snapshots two techniques despite names copy-on-write usually refers first technique cow two data writes compared row one difficult implement efficiently thus used infrequently copy-on-write technique used emulate read-write storage media require wear leveling physically write read many qcow2 qemu copy write disk image format uses copy-on-write technique reduce disk image size live cds live usbs use copy-on-write techniques give impression able add delete files directory without actually making changes cd usb flash drive phantom os uses cow levels database file system time computer running system fail starts software operating system resume operation small amounts work lost basic approach program data kept virtual memory schedule summary software data written virtual memory forming log tracks current value location value computer fails recent copy log data remain safe disk operation resumes operating system software reads log restore consistent copies programs data approach uses copy-on-write levels software including application software requires support within application programming language practice phantom os permits languages generate java byte codes
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Operating systems
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co-ment co-ment online word processor allowing collaborative writing commenting inspired software package stet created handle gnu gpl version 3 online revision free software available affero gpl co-ment allows groups users collaboratively elaborate online texts offers wiki-style editing environment supporting many syntaxes allows finely controlled layouts including table images main interest comment feature allowing users attach remarks specific extracts text leading text building procedure based strong equipped debates advanced comment navigation features also provided help discover new annotations go history debate also possible set email alerts text edits new comments co-ment fitted many import/export formats support txt doc odt html co-ment special focus layout respect exported file types available free web service extended pro accounts following wordpress model source code available website also bundled drupal module greatest use cases co-ment education particular first language literature teaching secondary education co-ment inspired stet tool created handle online revision gpl v3 since used licenses mozilla public license creative commons licence family co-ment also used legal works administrative works advocacy works
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Web technology
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collocation extraction collocation extraction task using computer extract collocations automatically corpus traditional method performing collocation extraction find formula based statistical quantities words calculate score associated every word pairs proposed formulas mutual information t-test z test chi-squared test likelihood ratio within area corpus linguistics collocation defined sequence words terms co-occur often would expected chance 'crystal clear 'middle management 'nuclear family 'cosmetic surgery examples collocated pairs words words often found together make compound noun example 'riding boots 'motor cyclist
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Computational linguistics
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etcher software balenaetcher commonly referred 'etcher free open-source utility used writing image files .iso .img files well zipped folders onto storage media create live sd cards usb flash drives developed balena licensed apache license 2.0 etcher developed using electron framework supports windows macos linux latest stable release balenaetcher version 1.5.51. balenaetcher originally called etcher name changed october 29 2018 resin.io changed name balena balenaetcher uses google analytics mixpanel even 'send anonymous usage data checkbox checked etcher primarily used graphical user interface additionally command line interface available active development future planned features include support persistent storage allowing live sd card usb flash drive used hard drive well support flashing multiple boot partitions single sd card usb flash drive
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Operating systems
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macadam bumper macadam bumper also known pinball wizard computer pinball construction set developed ere informatique france first released 8-bit computers 1985 atari st 1986 ms-dos 1987 st pc versions released us pinball wizard 1988 accolade game includes full-featured graphics sound lights even tilt capability game features four simulations varying obstacles atari st flipper back-board controls manipulated mouse moving mouse much activate tilt sensors players customize game changing parameters point scores table slope bumper elasticity number game balls parts menu player assemble pinball machine paint decorate game ’ paint menu 1988 dragon gave game 4½ 5 stars
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Computer architecture
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kill pill computing kill pill term given mechanisms technologies designed render systems useless either user command predefined set circumstances kill pill technology commonly used disable lost stolen devices security purposes also used enforcement rules contractual obligations kill pill technology used prominently smartphones especially disablement lost stolen devices notable example find iphone service allows user password protect wipe idevice remotely aiding protection private data similar applications exist smartphone operating systems including android blackberry windows phone kill pill technology notably used anti-piracy measure windows vista released ability severely limit functionality determined copy obtained piracy feature later dropped complaints false positives caused genuine copies vista act though pirated concept kill pill also applied remote removal server malicious files applications client system technology standard component handheld computing devices mainly due generally limited operating systems means obtaining applications functionality also reportedly available applications downloaded windows store windows 8 operating systems kill pill technology used frequently vehicles variety reasons remote vehicle disablement used prevent vehicle starting prevent moving prevent vehicle continued operation non-remotely vehicles require driver recognition starting moving asking password form biometrics driver kill pill technology often used governments prevent drunk driving repeat offenders punishment deterrent installation ignition interlock devices sentencing alternative drunk drivers almost 50 united states device requires driver blow breathalyzer starting vehicle driver found legal blood alcohol content limit vehicle start kill pill technology also implemented contextually disable certain aspects smartphone functionality patent obtained apple claims ability disable antenna screen camera smartphone settings like theaters schools areas high security sensitivity kill pill technology criticized allowing suppression personal liberties kill pill utilized school setting prevent academic dishonesty suggested governments may also use suppress people example disabling phone camera antenna area protest ability remotely remove files applications user device also come fire apple apparent ability blacklist applications rendering unusable idevice raised concerns user rights downloading app store july 2014 applications appear apple blacklist website
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Computer security
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navy directory navy directory formerly navy list naval register official list naval officers ranks seniority ships command appointed etc. published government naval authorities country navy list fulfills important function international law warships required article 29 united nations convention law sea commanded commissioned officer whose name appears appropriate service list past copies navy list also important sources information historians genealogists navy list royal navy longer published hard-copy royal navy united kingdom publishes annual lists active reserve officers biennial lists retired officers equivalent united states navy naval register updated online continuous basis ship removed naval vessel register united states naval list country ship said stricken 2015 navy list renamed 'navy directory good sources historical data royal navy navy lists current editor navy list cliona willis
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Databases
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squish 'em squish'em also known squish'em sam 1983 video game designed tony ngo published sirius software atari 8-bit family vic-20 commodore 64 msx colecovision console colecovision version features digitised speech without additional hardware published squish'em featuring sam game sequel sewer sam squish'em vertically scrolling game likened 1980 arcade game crazy climber players guide sam top uncompleted 48 storey buildings order collect suitcases money time sam reaches top building grabs money parachutes order attempt next building building represented grid girders connected vertically horizontally different patterns sometimes single way next storey building style buildings change grid layout colors change sam progresses game sam moves shimmying horizontally across grid climbing upwards moved storey climb back buildings patrolled dangerous enemies move horizontally across grid debris dropped sam must avoid making contact enemy without jumping hit falling debris results sam knocked building losing life player starts game four lives extra lives collected play 128 held player enemies 'squished jumped also jumped avoided ascending next storey enemy squished rendered harmless short period turning white becoming invulnerable enemy turned white must avoided jumped jumping enemies difficult landing squishing play progresses enemies become taller faster making harder squish avoid falling debris prevents players climbing many storeys enemies must avoided skillfully order prevent sam cornered invulnerable enemy tall easily jumped colecovision version game digitised speech employed sam performs certain actions instance exclaims squish 'em successfully attacking enemy money money money collecting suitcase top building one colecovision games contain speech unlike rival intellivision console colecovision lacks speech module craig holyoak deseret news rated colecovision version 3 5 praising game voice effects criticizing unoriginal despite boundaries technology pushed stated game contains plenty cute enabling appeal ages genders also stated little new keep experienced gamer long screen holyoak played game intensely number days lost interest mastering ability squish dangerous enemies finished stating less jaded looking climbing game new twist squish 'em may well unofficial homebrew clone even using name released atari 2600 2007
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Computer architecture
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msx-engine msx-engine chip specially developed integrated circuit home computers built according msx specifications generally chip combines functions many separate older/simpler chips one done reduce required circuit board space power consumption importantly production costs complete systems first msx-engine chip t7775 operated next standard zilog z80-clone chip main cpu system later versions engine also included z80 clone cpu single chip package s-1990 special case really msx-engine chip used glue logic msx-engine external r800 cpu t9769 used msx 2 computers msx 1 computers mostly t7775 t7937 used also find s-1985 s-3527 systems msx 2 generation msx2+ onwards toshiba took complete production msx engine chips last generation msx turbo-r used nec s-1990 turbor bus controller together r800 cpu msx engine chips yamaha mostly used msx-computers sony philips toshiba chips mostly used computers sanyo matsushita panasonic/national short overview msx-engine chips note ic also used many msx2 computers include msx2-specific functions machines implemented using additional ic's s1990 msx-engine acts like bus controller combining element combines z80 inside t9769c actual msx engine r800 cpu memory slot logic hardware inside t9769c also contains hardware assists debugging software
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Computer architecture
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admb admb ad model builder free open source software suite non-linear statistical modeling created david fournier developed admb project creation non-profit admb foundation ad ad model builder refers automatic differentiation capabilities come autodif library c++ language extension also created david fournier implements reverse mode automatic differentiation related software package admb-re provides additional support modeling random effects markov chain monte carlo methods integrated admb software making useful bayesian modeling addition bayesian hierarchical models admb provides support modeling random effects frequentist framework using laplace approximation importance sampling admb widely used scientists academic institutions government agencies international commissions commonly ecological modeling particular many fisheries stock assessment models built using software admb freely available new bsd license versions available windows linux mac os x opensolaris operating systems source code admb made publicly available march 2009 work david fournier 1970s development highly parameterized integrated statistical models fisheries motivated development autodif library ultimately admb likelihood equations models typically non-linear estimates parameters obtained numerical methods early fournier work became clear general numerical solutions likelihood problems could reliably achieved using function minimization algorithms incorporate accurate information gradients likelihood surface computing gradients i.e partial derivatives likelihood respect model variables must also done accuracy likelihood computation fournier developed protocol writing code compute required derivatives based chain rule differential calculus protocol similar suite methods came known reverse mode automatic differentiation statistical models using methods typically included eight constituent code segments model developers usually interested first constituents programming tools reduce overhead developing maintaining seven greatly increase productivity bjarne stroustrup began development c++ 1970s bell labs enhancement c programming language c++ spread widely 1989 c++ compilers available personal computers polymorphism c++ makes possible envisage programming system mathematical operators functions overloaded automatically compute derivative contributions every differentiable numerical operation computer program fournier formed otter research ltd. 1989 1990 autodif library included special classes derivative computation requisite overloaded functions c++ operators functions standard c++ math library autodif library automatically computes derivatives objective function accuracy objective function thereby frees developer onerous task writing maintaining derivative code statistical models equally important standpoint model development autodif library includes gradient stack quasi-newton function minimizer derivative checker container classes vectors matrices first application autodif library published 1992 autodif library however completely liberate developer writing model constituents listed 1993 fournier abstracted writing statistical models creating admb special template language simplify model specification creating tools transform models written using templates autodif library applications admb produces code manage exchange model parameters model function minimizer automatically computes hessian matrix inverts provide estimate covariance estimated parameters admb thus completes liberation model developer tedious overhead managing non-linear optimization thereby freeing focus interesting aspects statistical model mid-1990s admb earned acceptance researchers working aspects resource management population models based admb used monitor range endangered species commercially valuable fish populations including whales dolphins sea lions penguins albatross abalone lobsters tunas marlins sharks rays anchovy pollock admb also used reconstruct movements many species animals tracked electronic tags 2002 fournier teamed hans skaug introduce random effects admb development included automatic computation second third derivatives use forward mode automatic differentiation followed two sweeps reverse model ad certain cases 2007 group admb users included john sibert mark maunder anders nielsen became concerned admb long-term development maintenance agreement reached otter research sell copyright admb purpose making admb open-source project distributing without charge non-profit admb foundation created coordinate development promote use admb admb foundation drafted proposal gordon betty moore foundation funds purchase admb otter research moore foundation provided grant national center ecological analysis synthesis university california santa barbara late 2007 regents university california could purchase rights admb purchase completed mid-2008 complete admb libraries posted admb project website december 2008 may 2009 3000 downloads libraries occurred source code made available december 2009 mid-2010 admb supported common operating systems windows linux macos sun/sparc common c++ compilers gcc visual studio borland 32 64 bit architectures admb foundation efforts first two years admb project focused automating building admb different platforms streamlining installation creation user-friendly working environments planned technical developments include parallelization internal computations implementation hybrid mcmc improvement large sparse matrix use random effects models
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Programming language topics
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conda package manager conda open-source cross-platform language-agnostic package manager environment management system originally developed solve difficult package management challenges faced python data scientists today popular python/r package manager released berkeley software distribution license anaconda inc big difference conda pip package manager package dependencies managed significant challenge python data science reason conda created pip installs python package dependencies required whether conflict packages previously installed working installation example google tensorflow suddenly stop working pip-install new package needs different version numpy library insidiously everything might still appear work get different results unable reproduce results elsewhere n't pip-install order conda analyses current environment everything installed version limitations specify e.g want tensorflow 2.0 figures install compatible dependencies tell want ca n't done pip contrast install package specify dependencies even breaks packages conda allows users easily install different versions binary software packages required libraries appropriate computing platform also allows users switch package versions download install updates software repository conda written python programming language manage projects containing code written language e.g. r including multi-language projects conda install python programming language similar python-based cross-platform package managers wheel pip popular conda channel bioinformatics software bioconda provides multiple software distributions computational biology fact conda package environment manager included versions anaconda miniconda anaconda repository
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Operating systems
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exploit kit exploit kit simply collection exploits simple one-in-all tool managing variety exploits altogether exploit kits act kind repository make easy users without much technical knowledge use exploits users add exploits use simultaneously apart pre-installed ones one earlier kits mpack 2006 exploit kits often designed modular easy use enabling addition new vulnerabilities removal existing ones exploit kits also provide user interface person controls typically includes information success rates types statistics well ability control settings typical kit collection php scripts target security holes commonly used programs apple quicktime mozilla firefox widely used software oracle java adobe systems products targeted particularly often exploit kits come packed variety tools ranging hunting vulnerabilities automated exploitation security loopholes discovered basically follows simple hierarchy five steps hacking exploit kit gathers information victim machine finds vulnerabilities determines appropriate exploit delivers exploit typically silently drive-by downloads executes malware running post-exploitation modules maintain remote access compromised system lastly measure cover tracks uses special techniques like erasing logs avoid detection days pass exploit kits becoming ever sophisticated tend neatly packaged require understanding exploits little computer proficiency kits may web interface showing active victims statistics may support period updates like commercial software exploit kits sold cybercriminal circles often vulnerabilities already loaded onto study solutionary security engineering research team sert found 70 exploit kits released q4 2012 come russia followed china brazil 20 attributed typical relatively unsophisticated kit may cost us 500 per month licenses advanced kits reported cost much 10,000 per month exploit kits often encoded instead plain php prevent unlicensed use complicate anti-malware analysis research recorded future threat intelligence team revealed adobe flash player provided six top 10 vulnerabilities used exploit kits 2016 flash player popularity cyber criminals remains even increased adobe security issue mitigation efforts.kits continue include exploitation vulnerabilities patched years back continues significant population unpatched machines exploit kits tend deployed covertly legitimate web sites hacked unknown site operators visitors exploit kits named include mpack phoenix blackhole crimepack rig angler nuclear neutrino magnitude exploit kits
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Computer security
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cbrp cbrp cluster based routing protocol routing protocol wireless mesh networks cbrp originally designed mid 1998 national university singapore subsequently published internet draft august 1998 cbrp one earlier hierarchical ad-hoc routing protocols cbrp nodes dynamically form clusters maintain structural routing support minimize excessive discovery traffic typical ad-hoc routing many performance studies cbrp conducted area vehicular ad-hoc network vanet cbrp shown perform moderately well large high density mesh networks
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Distributed computing architecture
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data protection act 1998 data protection act 1998 c 29 united kingdom act parliament designed protect personal data stored computers organised paper filing system enacted eu data protection directive 1995 provisions protection processing movement data dpa 1998 individuals legal rights control information act apply domestic use example keeping personal address book anyone holding personal data purposes legally obliged comply act subject exemptions act defined eight data protection principles ensure information processed lawfully superseded data protection act 2018 dpa 2018 23 may 2018 dpa 2018 supplements eu general data protection regulation gdpr came effect 25 may 2018 gdpr regulates collection storage use personal data significantly strictly 1998 act replaced data protection act 1984 access personal files act 1987 implemented eu data protection directive 1995 privacy electronic communications ec directive regulations 2003 altered consent requirement electronic marketing positive consent opt-in box exemptions remain marketing similar products services existing customers enquirers still given permission opt basis jersey data protection law modelled uk law section 1 defines personal data data used identify living individual anonymised aggregated data less regulated act providing anonymisation aggregation done reversible way individuals identified various means including name address telephone number email address act applies data held intended held computers 'equipment operating automatically response instructions given purpose held 'relevant filing system cases paper records may classified 'relevant filing system address book salesperson diary used support commercial activities freedom information act 2000 modified act public bodies authorities durant case modified interpretation act providing case law precedent person data processed following rights schedule 1 lists eight data protection principles personal data processed fairly lawfully order data classed 'fairly processed least one six conditions must applicable data schedule 2 except mentioned exceptions individual needs consent collection personal information use purpose question european data protection directive defines consent “ …any freely given specific informed indication wishes data subject signifies agreement personal data relating processed ” meaning individual may signify agreement writing however non-communication interpreted consent additionally consent appropriate age capacity individual circumstances case e.g. organisation intends continue hold use personal data relationship individual ends consent cover even consent given n't assumed last forever although cases consent lasts long personal data needs processed individuals may able withdraw consent depending nature consent circumstances personal information collected used data protection act also specifies sensitive personal data must processed according stricter set conditions particular consent must explicit act structured processing personal data covered act providing number exceptions part iv notable exceptions act grants acknowledges various police court powers act details number civil criminal offences data controllers may liable data controller failed gain appropriate consent data subject however 'consent specifically defined act common law matter uk data protection act large act reputation complexity basic principles honoured protecting privacy interpreting act always simple many companies organisations individuals seem unsure aims content principles act hide behind act refuse provide even basic publicly available material quoting act restriction act also impacts way organisations conduct business terms contacted marketing purposes telephone direct mail also electronically led development permission based marketing strategies definition personal data data relating living individual identified sensitive personal data concerns subject race ethnicity politics religion trade union status health sex life criminal record information commissioner office website states regarding subject access requests sars right find organisation using storing personal data called right access exercise right asking copy data commonly known making ‘ subject access request general data protection regulation gdpr came force 25 may 2018 organisations could charge specified fee responding sar £10 requests following gdpr copy personal data provided free organisation may charge additional copies charge fee thinks request ‘ manifestly unfounded excessive ’ may ask reasonable fee administrative costs associated request compliance act regulated enforced independent authority information commissioner office maintains guidance relating act january 2017 information commissioner office invited public comments eu ’ article 29 working party proposed changes data protection law anticipated introduction extensions interpretation act guide general data protection regulation
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Computer security
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code morphing software code morphing software cms technology used transmeta microprocessors execute x86 instructions broad view cms reads x86 instructions generates instructions proprietary vliw processor style shade cms translation much expensive shade produces much higher quality code cms also contains interpreter simulates user-mode system mode operation
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Programming language topics
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block internet internet block ban technical measure intended restrict access information resources blocking inverse unblocking may implemented owners computers using software countries including china singapore block access certain news information united states children internet protection act requires schools receiving federal funded discount rates internet access install filter software blocks obscene content pornography applicable content harmful minors blocking may also refer denying access web server based ip address client machine certain websites including social networks facebook editable databases like wikimedia projects wikis users apply blocks based either ip number account users deemed undesirable prevent performing certain actions blocks kind may occur several reasons produce different effects social networks users unrestrictedly block users typically preventing sending messages viewing blocker information profile privileged users apply blocks affect access undesirables entire website blocking used moderators administrators social media forums deny access users broken rules likely order ensure peaceful orderly discussion place common reasons blocking spamming trolling flaming criticize cases use bans administrators large websites twitter saying bans may politically financially motivated however websites legal right decide allowed post users often respond voting feet going place administrators see behavior acceptable blocked users may completely unable access part site content usually case censoring filtering mechanisms responsible block shadow ban user given false impression content still posted site reality hidden users ban evasion act attempting get around ban whether temporary permanent website alternate accounts set people evading bans websites referred sockpuppets typically someone caught evading ban sockpuppet sockpuppet account banned original ban temporary may extended even made permanent sometimes user ip address may banned well user access site create new accounts sites may remove traces ban-evader tv tropes wikipedia example may mass-delete pages created ban-evader ban evasion detected tracing user ip address two accounts using ip address could sign ban evasion also use vpn shown rapid drastic changes ip address user short period time also sign user trying get around ban ban evasion also spotted posts contributions two accounts look similar sites email associated multiple accounts identical similar emails sign ban evasion users permanently banned ban evasion may able appeal ban case sites tv tropes creating sockpuppets ban evaders use variety tactics disguise fact new account created previously banned user using new names alternate email address vpns proxy servers mask ip address changing ip address sometimes needing rely dynamic ip address automatically change time using site public internet access locations schools libraries
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Computer security
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cryptographic module testing laboratory cryptographic module testing laboratory cmtl information technology computer security testing laboratory accredited conduct cryptographic module evaluations conformance fips 140-2 u.s. government standard national institute standards technology nist national voluntary laboratory accreditation program nvlap accredits cmtls meet cryptographic module validation program cmvp standards procedures replaced fips 140-2 cryptographic module validation program cmvp laboratories must meet following requirements cmtl also common criteria cc testing laboratory cctl cc fips 140-2 different abstractness focus tests fips 140-2 testing defined cryptographic module provides suite conformance tests four fips 140 security levels fips 140-2 describes requirements cryptographic modules includes areas physical security key management self tests roles services etc standard initially developed 1994 prior development cc cc evaluation protection profile pp usually created user security target st typically pp covers broad range products operational environment modifiable operational environment operating system requirements common criteria applicable fips security levels 2
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Computer security
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sparclite discontinued sparclite risc processor family based 32-bit sparc v8 architecture manufactured approximately 1990s fujitsu designation mb8683x used many embedded applications including number early digital cameras followed fujitsu fr fr-v processors
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Computer architecture
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blackra1n blackra1n program jailbreaks versions 3.1 3.1.1 3.1.2 apple operating system iphone ipod touch known ios program uses bug usb code firmware iphone ipod touch allowing unsigned code executed blackra1n uses exploit patch firmware iphone ipod touch dfu device firmware upgrade mode mode used upgrading firmware itunes also activated user program allows users install cydia icy removed blackra1n rc3 rock package managers applications allow user access tweaks homebrew applications root directory file system ios device blackra1n also perform tethered jailbreaks ipod touch 3g iphone 3gs devices running os 3.1.2 ios 3.1.3 released spiritjb released provided untethered jailbreaks 3.1.2 3.1.3. blackra1n superseded spirit comex
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Computer security
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lyme software bundle lyme lyce software stacks composed entirely free open-source software build high-availability heavy duty dynamic web pages stacks composed lyme lyce bundles combined many free open-source software packages e.g netsniff-ng security testing hardening snort intrusion detection ids intrusion prevention system ips rrdtool diagrams nagios collectd cacti monitoring databases mnesia couchdb well yaws also mochiweb misultin cowboy written erlang web applications developed lyme/lyce may run entirely one erlang virtual machine contrast lamp web server apache application written php perl python might process database always separate process result using erlang lyme lyce applications perform well high load distribution fault tolerance needed query data manipulation language mnesia also erlang rather sql therefore web-application lyme developed using single programming language interest lyme stack begun august 2005 soon cited high-performance web application platform used single development language throughout favorable comparisons popular stacks ruby rails soon forthcoming comparisons lamp also favourable although highlighted difficulties porting sql thinking different context mnesia successful user lyme swedish internet payment-processing company klarna built whole architecture lyme seen successful project demonstrates virtues lyme functional programming general lyme also covered erlang session software practice advancement spa 2008 besides yaws several web servers written erlang e.g mochiweb misultin cowboy besides mnesia couchdb couple databases written erlang e.g. cloudant couchbase server born membase database management system optimized storing data behind interactive web applications riak simpledb part amazon web services
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Web technology
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eurodicautom eurodicautom pioneering terminology database european commission created 1975 initially use translators commission staff 1980 consultable line within commission european community grew expanded six seven nine finally eleven languages plus latin scientific names public user interfaces added later providing general public free access multilingual terminology fields activity european union students rennes university ufr2 lea technical translator terminologist department regularly worked reviewing creating entries existing database several languages 2007 eurodicautom replaced interactive terminology europe iate
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Computational linguistics
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sun workstation sun workstation modular computer system designed stanford university early 1980s became seed technology many commercial products including original workstations sun microsystems 1979 xerox donated alto computers developed palo alto research center stanford computer science department well universities developing early internet altos connected using ethernet form several local area networks sun design inspired alto used lower-cost modular components project name derived initials campus stanford university network professor forest baskett suggested best-known configuration relatively low-cost personal workstation computer-aided logic design work design created 3m computer 1 million instructions per second mips processor 1 megabyte memory 1 megapixel raster scan bit-map graphics display sometimes 10,000 estimated price called fourth — megapenny director computer facilities ralph gorin suggested configurations initially funded project graduate student andy bechtolsheim designed hardware several students staff members assisting software aspects project vaughan pratt became unofficial faculty leader project 1980 three key technologies made sun workstation possible large-scale integration vlsi integrated circuits multibus ecad ecad electronic computer assisted design known electronic design automation allowed single designer quickly develop systems greater complexity stanford artificial intelligence laboratory sail pioneered personal display terminals 1971 system showing age bechtolsheim used stanford university drawing system suds design sun boards sail system suds originally developed foonly computer structured computer aided logic design scald package used verify design automate layout produce wire-wrapped prototypes printed circuit boards vlsi integrated circuits finally allowed high-level hardware functionality included single chip graphics display controller first board designed published 1980 motorola 68000 cpu along memory parallel port controller serial port controller included main cpu board designed bechtolsheim third board interface 2.94 mbits/second experimental ethernet speed standardized 10 mbits/second multibus computer interface made possible use standard enclosures use circuit boards made different vendors create configurations example cpu board combined multi-port serial controller created terminal server called tip terminal interface processor connected many terminals digital equipment corporation time-sharing systems stanford anywhere internet configuring multiple ethernet controllers including commercial ones available one cpu board created router william yeager wrote software later adopted evolved cisco systems version hardware les earnest licensed cpu board one first commercial low-cost laser printer controllers company called imagen processor board combined prototype high performance graphics display students james h. clark group later formed silicon graphics incorporated eventually ten sun workstations built 1981 1982 stanford declined build bechtolsheim licensed hardware design several vendors frustrated none chosen build workstation vinod khosla also stanford convinced bechtolsheim along scott mcnealy found sun microsystems order build sun-1 workstation included improvements earlier design faculty members research using sun workstations included david cheriton brian reid john hennessy
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Computer architecture
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novell storage services novell storage services nss file system used novell netware operating system support nss introduced 2004 suse linux via low-level network ncpfs protocol unique features make especially useful setting shared volumes file server local area network nss 64-bit journaling file system balanced tree algorithm directory structure published specifications netware 6.5
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Computer file systems
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nokia n80 nokia n80 3g smartphone nokia announced november 2 2005 part multimedia nseries line runs symbian os v9.1 s60 3rd edition interface first released june 2006 support high-speed umts/wcdma connections features include 3.1-megapixel camera interpolated 2.0-megapixels built-in flash front camera videoconferencing wi-fi 802.11g universal plug play upnp fm radio bluetooth 1.2 minisd memory card slot support 3d java games 2.1-inch display pixel density 259 ppi due 352x416 resolution 2.1 displaymaking one nokia sharpest displays 2005 2006 n80 world first upnp-compatible phone allowing transfer media files compatible devices wi-fi n80 officially described multimedia computer nokia like successor nokia n95 nokia originally announced n80 supporting bluetooth 2.0 however released bluetooth 1.2 therefore n80 currently support stereo playback bluetooth nokia n80 internet edition second version handset hardware normal n80 released q4 2006 available patina bronze pearl black following additional software included january 2007 pearl black model available sale us 499 nokia announced new internet edition firmware available 'classic n80 using nokia official software updater downloadable nokia.com internet edition firmware made available nokia software updater end users could update n80 specification n80 internet edition flashing n80 firmware n80 internet edition required use several hacked nokia servicing software applications including phoenix service software nokia software update nemesis changing product code method questionable legality jurisdictions may violate terms phone warranty reports occasional failure method due user error unknown reasons leaving phone unusable state properly-equipped service center could recover
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Operating systems
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orion system-on-a-chip orion system-on-a-chip manufactured marvell technology group used network-attached storage based armv5te architecture on-chip support ethernet sata usb used hardware made hewlett-packard d-link among others supported lenny release debian gnu/linux
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Computer architecture
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hp mediasmart server hp mediasmart server home server hewlett-packard ran microsoft windows home server operating system october 2008 hp mediasmart server sold two models ex470 rrp us 599 ex475 rrp us 749 feature 1.8 ghz amd sempron 3400+ processor one gigabit ethernet port four internal sata drive bays four usb 2.0 ports one esata port two models identical exception amount included storage ex470 one 500 gb hard drive preinstalled ex475 two 500 gb hard drives preinstalled hackers enthusiasts modded ex470 adding vga monitor upgrading memory 512 mb 2 gb upgrading processor 2.6 ghz amd le-1640 december 29 2008 hp announced two models ex485 ex487 available pre-orders starting january 8 2009 newer models include support apple time machine backup software also use 2.0 ghz intel celeron processor replacing amd sempron old models features include revamped user interface larger preinstalled hard drives one 750 gb drive ex485 two 750 gb drives ex487 april 30 2009 hp announced mediasmart server lx195 intended low-cost entry home server market new model featured single internal 640 gb drive 1.6 ghz intel atom 230 processor 1 gb ddr2 memory gigabit ethernet four usb ports storage expansion software features included lx195 initial launch features ex485/ex487 server september 14 2009 hp launched two new mediasmart servers ex490 comes 1 tb hard disk storage costs 549 ex495 comes 1.5 tb costs 699 7200 rpm 490 comes intel celeron processor 2.2 ghz 495 intel pentium processor dual core 2.5 ghz november 30 2010 windows home server team microsoft confirmed rumors hp would offering hardware next version windows home server codenamed vail hp would stop selling mediasmart servers altogether end calendar year 2010
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Computer security
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silly window syndrome silly window syndrome problem computer networking caused poorly implemented tcp flow control serious problem arise sliding window operation sending application program creates data slowly receiving application program consumes data slowly server problem unable process incoming data requests clients reduce amount data send time window setting tcp packet server continues unable process incoming data window becomes smaller smaller sometimes point data transmitted smaller packet header making data transmission extremely inefficient name problem due window size shrinking silly value since certain amount overhead associated processing packet increased number packets means increased overhead process decreasing amount data end result thrashing synchronization sender receiver regarding capacity flow data size packet window syndrome problem created silly window syndrome created sender nagle algorithm used nagle solution requires sender send first segment even small one wait ack received maximum sized segment mss accumulated silly window syndrome created receiver david clark solution used clark solution closes window another segment maximum segment size mss received buffer half empty 3 causes sws sws efficiency communication almost 0 sws duration short possible heuristic method send tcp must allow sending application make write calls collect data transferred call transmitting large segment sending tcp delays sending segments accumulate reasonable amounts data known clumping heuristic method receiver uses maintain internal record available window delay advertising increase window size sender advance significant amount amount depends receiver buffer size maximum segment size using method prevents small window advertisements received applications extract data octets slowly
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Internet protocols
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norwegian international ship register norwegian international ship register nis separate norwegian ship register norwegian vessels aimed competing flags convenience registers panama liberia originally proposed erling dekke næss 1984 established bergen 1987 managed norwegian ship registers 2010 12th ship register gross tonnage representing 1 global tonnage years register established norwegian register lost could compete lower-cost registers main objectives establishing register register highly successful 2002 880 vessels register total around criticism countries opened second registers norway nis germany gis denmark dis fewer restrictions nationality crew allegedly lower safety standards main national register
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Databases
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dadisp dadisp data analysis display pronounced day-disp numerical computing environment developed dsp development corporation allows one display manipulate data series matrices images interface similar spreadsheet dadisp used study signal processing numerical analysis statistical physiological data processing dadisp designed perform technical data analysis spreadsheet like environment however unlike typical business spreadsheet operates table cells contain single scalar values dadisp worksheet consists multiple interrelated windows window contains entire series multi-column matrix window stores data also displays data several interactive forms including 2d graphs xyz plots 3d surfaces images numeric tables like traditional spreadsheet windows linked change data one window automatically updates dependent windows numerically graphically users manipulate data primarily windows dadisp window normally referred letter w followed window number w1 example formula codice_1 assigns series values 1 2 3 w1 formula codice_2 sets second window compute square value w1 w2 contain series 1 4 9 values w1 change 3 5 2 4 values w2 automatically update 9 25 4 16 dadisp includes series based programming language called spl series processing language used implement custom algorithms spl c/c++ like syntax incrementally compiled intermediate bytecode executed virtual machine spl supports standard variables assigned codice_3 hot variables assigned codice_4 example statement codice_5 assigns series 1 2 3 standard variable square values assigned codice_6 variable b contains series 1 3 9 changes b change b preserves values assigned without regard future state however statement codice_7 creates hot variable hot variable analogous window except hot variables display data assignment codice_8 computes square values changes b automatically updates setting codice_9 causes b automatically update 9 25 4 16 dadisp originally developed early 1980s part research project mit explore aerodynamics formula one racing cars original goal project enable researchers quickly explore data analysis algorithms without need traditional programming
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Programming language topics
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pdf/e iso 24517-1:2008 iso standard published 2008 standard defines format pdf/e creation documents used geospatial construction manufacturing workflows ref name= pdf/e-iso-standard iso 24517-1:2008 document management -- engineering document format using pdf -- part 1 use pdf 1.6 pdf/e-1 /ref based pdf reference version 1.6 adobe systems specification also supports interactive media including animation 3d pdf/e subset pdf designed open neutral exchange format engineering technical documentation. ref name= pdf/e-ready-guide creating pdf/e-ready files /ref pdf/e standard specifies portable document format pdf used creation documents engineering workflows key benefits pdf/e include standard define method creation conversion paper electronic documents pdf/e format committee managing iso 24517 pdf/e needs subject-matter experts assist development part 2 standard iso 24517 pdf/e created meet needs organizations need reliably create exchange review engineering documentation however first part standard address 3d video dynamic content address integrated source data
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Programming language topics
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unique user according ifabc global web standards unique user uu ip address plus identifier term unique visitor may used instead unique user terms essentially meaning see sites may use user agent cookie and/or registration id note users allocated ip addresses dynamically example dial-up internet service providers definition may overstate understate real number individual users concerned unique users common way measuring popularity website often quoted potential advertisers investors website unique users usually measured standard period time typically month use performance indicators unique visitors/users controversial greg harmon belden research inferring many companies reporting online performance may overstate number unique visitors remember identifier computer person usually computer identified cookie often specific individual browser computer since increasing percentage people united states least access computer home work school one may divide reported total unique users half another increasing fraction people regularly delete cookies machines—presumably home work—and yet another large fraction use one browser machines means typical news site example people might typically visit day keep breaking news reported unique users might overstate number different people factor four plus side wishing impress advertisers investors reported number sessions visits pageviews probably accurate smaller group people visits much often looks pages raw numbers would suggest similar turf total unduplicated reach frequency metric often used television radio newspaper analyses unique users measure distribution content number distinct consumers common mistake using unique user numbers adding unique user numbers across dimensions unique user metric valid given set dimensions e.g time browsers example website may 100 unique users day day dimension particular week data one extrapolate number weekly unique users unique user count week 100 700 however website administrators track unique user traffic longer period time build reliable view performance direct competitors within sector online businesses tend static conversation rate ratio unique users new business clients calculating movement unique users conversion funnel time period must used every step unique user counts websites typically counted using cookies browser visits website website checks existence particular cookie cookie present cookie value captured cookie present website create cookie unique visitors refers number distinct individuals requesting pages website given period regardless often visit visits refer number times site visited matter many visitors make visits individual goes website tuesday wednesday recorded two visits one visitor purpose tracking unique visitors help marketers understand website user behavior visitor make multiple visits specified period number visits may greater number visitors visitor sometimes referred unique visitor unique user clearly convey idea visitor counted measurement users visitors requires standard time period distorted automatic activity bots classify web content estimation visitors visits traffic statistics usually filtered remove type activity eliminating known ip addresses bots requiring registration cookies using panel data
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Web technology
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anchor modeling anchor modeling agile database modeling technique suited information changes time structure content provides graphical notation used conceptual modeling similar entity-relationship modeling extensions working temporal data modeling technique involves four modeling constructs anchor attribute tie knot capturing different aspects domain modeled resulting models translated physical database designs using formalized rules translation done tables relational database mostly sixth normal form anchor modeling created order take advantage benefits high degree normalization avoiding drawbacks advantages able non-destructively evolve model avoid null values keep information free redundancies gained performance issues due extra joins largely avoided thanks feature modern database engines called 'table elimination order handle changes information content anchor modeling emulates aspects temporal database resulting relational database schema earliest installations using anchor modeling made sweden first dating back 2004 data warehouse insurance company built using technique 2007 technique used data warehouses one oltp system presented internationally lars rönnbäck 2007 transforming data intelligence tdwi conference amsterdam stirred enough interest technique warrant formal description since research concerning anchor modeling done collaboration creators olle regardt lars rönnbäck team department computer systems sciences stockholm university first paper anchor modeling formalized presented 28th international conference conceptual modeling best paper award commercial web site provides material anchor modeling free use creative commons license online modeling tool also available free use open source anchor modeling four basic modeling concepts anchors attributes ties knots anchors used model entities events attributes used model properties anchors ties model relationships anchors knots used model shared properties states attributes ties historized changes information model need kept example model showing different graphical symbols concepts seen symbols resemble used entity–relationship modeling couple extensions double outline attribute tie indicates history changes kept knot symbol outlined square rounded edges also available anchor modeling handles two types informational evolution structural changes content changes changes structure information represented extensions high degree normalization makes possible non-destructively add necessary modeling concepts needed capture change way every previous schema always remains subset current schema since existing schema touched gives benefit able evolve database highly iterative manner without causing downtime changes content information done emulating similar features temporal database relational database anchor modeling pieces information tied points time intervals time open closed time points events occur modeled using attributes e g birth dates persons time purchase intervals time value valid captured historization attributes ties e g changes hair color person period time person married relational database achieved adding single column data type granular enough capture speed changes table corresponding historized attribute tie adds slight complexity one row table examined order know interval closed points intervals time directly related domain modeled points time information entered database handled use metadata anchor modeling rather mentioned constructs information changes database needs kept bitemporal anchor modeling used addition updates also delete statements become non-destructive anchor modeling one-to-one mapping symbols used conceptual model tables relational database every anchor attribute tie knot corresponding table database unambiguously defined structure conceptual model thereby translated relational database schema using simple automated rules vice versa different many modeling techniques complex sometimes subjective translation steps conceptual logical physical levels anchor tables contain single column identities stored identity assumed property entity always present immutable identities rarely available domain modeled instead technically generated e g incrementing number sequence example anchor identities nephews donald duck set 1-tuples codice_1 knots thought combination anchor single attribute knot tables contain two columns one identity one value due storing identities values together knots historized usefulness comes able reduce storage requirements improve performance since tables referencing knots store short value rather long string example knot genders set 2-tuples codice_2 static attribute tables contain two columns one identity entity value belongs one actual property value historized attribute tables extra column storing starting point time interval knotted attribute table value column identity references knot table example static attribute names set 2-tuples codice_3 example knotted static attribute genders set 2-tuples codice_4 example historized attribute changing colors outfits set 3-tuples codice_5 static tie tables relate two anchors contain two columns storing identities historized tie tables extra column storing starting point time interval knotted tie tables additional column referenced knot example static tie sibling relationship set 2-tuples codice_6 resulting tables sixth normal form except ties columns part primary key
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Databases
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gyrodine note player fire guns time
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Computer architecture
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