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buildhive buildhive free cloud-hosted continuous integration service github projects based jenkins buildhive detect build test number common project types apache maven play without need configuration developer starts build test cycle every time sees new commit registered github repository also automatically schedule builds github pull requests leave pass/fail comment pull request project owners know whether pull requests pass tests merging contributors wait tests run machine submitting pull request number features provided commercial jenkins plugins cloudbees also makes available paying customers buildhive support private github repositories complex configurations commercial cloudbees service available requirements buildhive originally started christmas side project developer kohsuke kawaguchi
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Distributed computing architecture
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mips magnum mips magnum line computer workstations designed mips computer systems inc. based mips series risc microprocessors first magnum released march 1990 production various models continued 1993 sgi bought mips technologies sgi cancelled mips magnum line promote workstations including entry-level sgi indy early r3000-based magnum series ran risc/os variant bsd unix subsequent magnum workstations based jazz architecture ran risc/os windows nt addition proprietary operating systems linux netbsd ported jazz-based mips magnum machines models mips magnum rebadged sold groupe bull olivetti addition headless i.e. without framebuffer video card versions marketed servers name mips millennium model number information mips magnum 3000 25 33 mhz mips r3000a microprocessor mips magnum r4000 pc-50 mips r4000pc processor 16 kb l1 cache l2 cache running external clock rate 50 mhz internally doubled microprocessor 100 mhz mips magnum r4000 sc-50 identical magnum r4000pc includes one megabyte secondary cache addition primary cache main memory mips magnum 3000 accepted 30-pin true-parity 80ns simms maximum 128 mb mips magnum r4000 accepted eight 72-pin true-parity simms maximum 256 mb mips magnum r4000 r4000 pc-50 r4000 sc-50 includes single on-board scsi bus using on-board ncr 53c94 fast-narrow scsi chipset internal cable four 50-pin connections links internal scsi devices also interfaces external scsi devices via endlink mounted rear case mips magnum r4000 includes on-board sonic ethernet chipset aui ethernet connector mounted case video output magnum r4000 consists proprietary framebuffer available custom full-length option card — g364 framebuffer g364 includes sun 13w3-style output converted common vga pin-out capable pixel screen resolutions 640x480 800x600 1024x768 1280x1024 simple framebuffer g364 include accelerated graphics functions mips magnum r4000 also includes two standard rs232-capable serial ports ibm at-compatible parallel port also mips magnum r4000 ibm at-compatible floppy disk controller single floppy drive bay mips magnum 3000 used mips r3000 processor custom proprietary motherboard incorporated turbochannel bus noted dec also manufactured decstation line workstations running ultrix also used mips processors turbochannel bus magnum 3000 ran risc/os mips computer systems inc. proprietary port bsd unix including system v features later magnums mips magnum r4000pc mips magnum r4000sc also used mips microprocessor — mips r4000 full 64-bit microprocessor available either low-cost version r4000pc 16 kb l1 cache l2 cache higher-performance version r4000sc 1 mb secondary cache addition 16 kb primary cache mips computer systems inc. co-founded advanced computing environment consortium silicon graphics microsoft motorola others mips magnum r4000 intended mips entry windows nt workstation market however mips computer systems inc. in-house effort design mips-based windows nt system met delays mips technologies abandoned in-house efforts instead licensed jazz design microsoft developed early 1990s facilitate porting development windows nt noted windows nt first developed mips architecture later ported intel 386 alpha powerpc architectures mips magnum r4000 indeed jazz-based systems acer pica nec riscstation olivetti m700 etc incorporated many features common intel-based pc commercial unix workstations era — example magnum r4000 included eisa bus used ibm ps/2-compatible keyboards mice used commodity chipset components whose control registers mapped memory locations set forth ibm standard mips magnum r4000 ran either windows nt beginning version 3.1 equipped little-endian arc firmware risc/os mips computer systems inc. proprietary big-endian firmware mips monitor installed firmware could switched arc mips monitor loading either one magnum flash memory/nvram floppy disk thus magnum r4000 could dual-boot windows unix mips magnum r4000 supported windows nt version 3.1 released 1993 version 4.0 released 1996 however support microsoft mips systems ended release windows nt version 4.0 useful software windows/mips — either microsoft third-party vendors — scarce even mips supported example microsoft never ported microsoft office suite mips mips magnum 3000 unlike mips magnum r4000 able run windows nt magnums could run risc/os mips computer system inc. proprietary port unix running risc/os mips magnum r4000 requires use big-endian mips monitor firmware mips magnum run netbsd also ran openbsd one point lack developer interest proper resources lead termination arch support prior december 1 1998 2.4 release earlier risc/os-only mips magnum 3000 machines correct port netbsd/mipsco later windows nt-capable mips magnum r4000 correct port netbsd/arc mips magnum r4000 among earliest supported machines effort port linux kernel mips initial support begun april 1995 support magnum r4000 became stable 2.1 development tree around 1999 however support magnum linux atrophied since qemu pc emulator version 0.9.1 emulate mips magnum acer pica 61 using -m parameter -m magnum -m pica61 qemu run mips compiled version debian gnu/linux x86 platform along windows nt 3.5,3.51 4.0 binaries
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Computer architecture
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messages server messages server component os x server apple inc first introduced ichat server release mac os x server 10.4 upgraded version 2 release mac os x 10.5 server october 2007. ichat server originally based jabberd 1.4.3 named apple ichat online chat client software version 2 software based jabberd2 2.0s9 supports server federation allows chat clients talk directly systems support xmpp also supports server-based chat archiving
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Operating systems
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utility computing utility computing computer utility service provisioning model service provider makes computing resources infrastructure management available customer needed charges specific usage rather flat rate like types on-demand computing grid computing utility model seeks maximize efficient use resources and/or minimize associated costs utility packaging system resources computation storage services metered service model advantage low initial cost acquire computer resources instead resources essentially rented repackaging computing services became foundation shift demand computing software service cloud computing models propagated idea computing application network service initial skepticism significant shift however new model computing caught eventually became mainstream ibm hp microsoft early leaders new field utility computing business units researchers working architecture payment development challenges new computing model google amazon others started take lead 2008 established utility services computing storage applications utility computing support grid computing characteristic large computations sudden peaks demand supported via large number computers utility computing usually envisioned form virtualization amount storage computing power available considerably larger single time-sharing computer multiple servers used back end make possible might dedicated computer cluster specifically built purpose rented even under-utilized supercomputer technique running single calculation multiple computers known distributed computing term grid computing often used describe particular form distributed computing supporting nodes geographically distributed cross administrative domains provide utility computing services company bundle resources members public sale might paid portion revenue clients one model common among volunteer computing applications central server dispense tasks participating nodes behest approved end-users commercial case paying customers another model sometimes called virtual organization vo decentralized organizations buying selling computing resources needed go idle definition utility computing sometimes extended specialized tasks web services utility computing merely means pay use regards computing power utility computing new concept rather quite long history among earliest references ibm mainframe providers conducted kind business following two decades often referred time-sharing offering computing power database storage banks large organizations worldwide data centers facilitate business model mainframe operating systems evolved include process control facilities security user metering advent mini computers changed business model making computers affordable almost companies intel amd increased power pc architecture servers new generation processor data centers became filled thousands servers late 90 utility computing re-surfaced insynq inc. launched on-demand applications desktop hosting services 1997 using hp equipment 1998 hp set utility computing division mountain view ca assigning former bell labs computer scientists begin work computing power plant incorporating multiple utilities form software stack services ip billing-on-tap marketed hp introduced utility data center 2001 sun announced sun cloud service consumers 2000 december 2005 alexa launched alexa web search platform web search building tool underlying power utility computing alexa charges users storage utilization etc space market specific industries applications well niche applications powered utility computing example polyserve inc. offers clustered file system based commodity server storage hardware creates highly available utility computing environments mission-critical applications including oracle microsoft sql server databases well workload optimized solutions specifically tuned bulk storage high-performance computing vertical industries financial services seismic processing content serving database utility file serving utility enable organizations independently add servers storage needed retask workloads different hardware maintain environment without disruption spring 2006 3tera announced applogic service later summer amazon launched amazon ec2 elastic compute cloud services allow operation general purpose computing applications based xen virtualization software commonly used operating system virtual computers linux though windows solaris supported common uses include web application saas image rendering processing also general-purpose business applications decision support business intelligence 8th edition page 680
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Distributed computing architecture
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shared medium telecommunication shared medium medium channel information transfer serves one user time channels function correctly one user transmitting channel access method always effect circuit switching user typically gets fixed share channel capacity multiplexing scheme divides capacity medium common multiplexing schemes include time-division multiplexing frequency-division multiplexing channel access methods circuit switching include time-division multiple access frequency-division multiple access etc packet switching sharing dynamic — user takes little none capacity idle utilize entire capacity transmitting users idle channel access methods packet switching include carrier sense multiple access token passing etc
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Internet protocols
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silicon graphics international silicon graphics international corp. sgi formerly rackable systems inc. american manufacturer computer hardware software including high-performance computing solutions x86-based servers datacenter deployment visualization products founded rackable systems 1999 adopted sgi name 2009 acquiring silicon graphics inc.. november 1 2016 hewlett packard enterprise completed acquisition sgi 275 million rackable systems inc. went public june 2005 6.25 million shares offered 12 per share 2006 rackable announced signed agreement acquire terrascale technologies inc. april 1 2009 rackable announced agreement acquire silicon graphics inc. 25 million purchase ultimately 42.5 million finalized may 11 2009 time rackable announced adoption sgi global name brand following week company changed nasdaq stock ticker symbol rack sgi new sgi began two main product lines servers storage continuing original rackable systems servers storage visualization professional services acquired silicon graphics inc. time acquisition completion sgi said anticipated survival majority two companies product lines although consolidation likely areas high overlap products 2010 sgi announced purchase assets assumed limited amount liabilities copan systems copan provider storage archive products real-time access long-term persistent data copan products offered part sgi storage line 2011 sgi acquired outstanding shares sgi japan ltd year company announced acquisition opencfd ltd december company announced mark j. barrenechea resignation president chief executive officer member board directors mark reported join open text corporation shortly thereafter announced barrenechea agreed continue serve sgi board february 2012 announced jorge luis titinger would become sgi president chief executive officer 2013 sgi acquired filetek inc. august 11 2016 announced hewlett packard enterprise would acquire sgi 7.75 per share cash transaction valued approximately 275 million net cash debt deal completed november 1 2016
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Computer architecture
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et-188 et-188 ibm pc xt compatible computer made yugoslav company novkabel novosadska fabrika kabela novi sad cable factory novi sad serbia 1980s novkabel already experience developing computer systems era 20 era 60 others used make et-188 original design compatible ibm pc xt save space lower cost et-188 used 8mhz intel 80188 cpu integrated timer dma interrupt controller also made faster original xt et-188 offered public 1985 advertised yugoslav computer press improved et-188a model may 1986 presented public belgrade technical fair beogradski sajam tehnike ram new redesigned case among things et-188a used education classrooms throughout vojvodina province
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Computer architecture
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hibernate framework hibernate orm hibernate short object-relational mapping tool java programming language provides framework mapping object-oriented domain model relational database hibernate handles object-relational impedance mismatch problems replacing direct persistent database accesses high-level object handling functions hibernate free software distributed gnu lesser general public license 2.1 hibernate primary feature mapping java classes database tables mapping java data types sql data types hibernate also provides data query retrieval facilities generates sql calls relieves developer manual handling object conversion result set mapping java classes database tables implemented configuration xml file using java annotations using xml file hibernate generate skeleton source code persistence classes auxiliary annotations used hibernate use xml file java annotations maintain database schema provided facilities arrange one-to-many many-to-many relationships classes addition managing associations objects hibernate also manage reflexive associations wherein object one-to-many relationship instances class type hibernate supports mapping custom value types makes following scenarios possible definition objects object-oriented application follow oop principles objects back-end follow database normalization principles resulting different representation requirements problem called object-relational impedance mismatch mapping way resolving object-relational impedance mismatch problem mapping informs orm tool java class object store database table hibernate provides sql inspired language called hibernate query language hql writing sql-like queries hibernate data objects criteria queries provided object-oriented alternative hql criteria query used modify objects provide restriction objects hql hibernate query language object-oriented version sql generates database independent queries need write database-specific queries without capability changing database would require individual sql queries changed well leading maintenance issues hibernate provides transparent persistence plain old java objects pojos strict requirement persistent class no-argument constructor though necessarily proper behavior applications also requires special attention methods object classes hibernate recommends providing identifier attribute planned mandatory requirement future release collections data objects typically stored java collection classes implementations interfaces java generics introduced java 5 also supported hibernate configured lazy load associated collections lazy loading default hibernate 3 related objects configured cascade operations one object example parent class object configured cascade operations child class objects hibernate used standalone java applications java ee applications using servlets ejb session beans jbi service components also included feature programming languages example adobe integrated hibernate version 9 coldfusion runs j2ee app servers abstraction layer new functions syntax added cfml hibernate jargon entity stand-alone object hibernate persistent mechanism manipulated independently objects contrast component subordinate entity manipulated respect entity example album object may represent entity tracks object associated album objects would represent component album entity assumed tracks saved retrieved database album object unlike j2ee hibernate switch databases hibernate started 2001 gavin king colleagues cirrus technologies alternative using ejb2-style entity beans original goal offer better persistence capabilities offered ejb2 simplifying complexities supplementing certain missing features early 2003 hibernate development team began hibernate2 releases offered many significant improvements first release jboss inc. part red hat later hired lead hibernate developers order development 2005 hibernate version 3.0 released key features included new interceptor/callback architecture user defined filters jdk 5.0 annotations java metadata feature hibernate 3 version 3.5.0 certified implementation java persistence api 2.0 specification via wrapper core module provides conformity jsr 317 standard dec 2011 hibernate core 4.0.0 final released includes new features multi-tenancy support introduction serviceregistry major change hibernate builds manages services better session opening sessionfactory improved integration via org.hibernate.integrator.spi.integrator auto discovery internationalization support message codes logging distinction api spi implementation classes december 2012 hibernate orm 4.1.9 final released mar 2013 hibernate orm 4.2 final released december 2013 hibernate orm 4.3.0 final released features java persistence api 2.1 september 2015 hibernate orm 5.0.2 final released improved bootstrapping hibernate-java8 hibernate-spatial karaf support november 2018 hibernate orm 5.1.17 final released final release 5.1 series october 2018 hibernate orm 5.3 final released featured java persistence api 2.2 inheritance caching december 2018 hibernate orm 5.4.0 final released hibernate api provided java package org.hibernate org.hibernate.session interface represents hibernate session i.e. main point manipulation performed database entities latter activities include among things managing persistence state transient persisted detached objects fetching persisted ones database management transaction demarcation session intended last long logical transaction database due latter feature session implementations expected thread safe used multiple clients hibernate software includes following components
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Databases
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jreap joint range extension applications protocol jreap enables tactical data messages transmitted long-distance networks e.g satellite links thereby extending range tactical data links tdls jreap documented u.s. military standard mil-std 3011 nato standardization agreement stanag 5518 interoperability standard joint range extension applications protocol jreap jreap developed due need communicate data long distances without degradation message format content jreap takes message format originally formatted changes protocol message transmitted beyond line-of sight media jreap protocol message structure transmission reception pre-formatted messages communications media messages designed jreap provides foundation joint range extension jre link 16 tactical data links overcome line-of-sight limitations radio terminals joint tactical information distribution system jtids multifunctional information distribution system mids extends coverage data links use long-haul media
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Internet protocols
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list bpmn 2.0 engines list notable business process model notation 2.0 bpmn 2.0 workflow management systems wfmss
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Distributed computing architecture
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slide attack slide attack form cryptanalysis designed deal prevailing idea even weak ciphers become strong increasing number rounds ward differential attack slide attack works way make number rounds cipher irrelevant rather looking data-randomizing aspects block cipher slide attack works analyzing key schedule exploiting weaknesses break cipher common one keys repeating cyclic manner attack first described david wagner alex biryukov bruce schneier first suggested term slide attack used 1999 paper describing attack requirements slide attack work cipher broken multiple rounds identical f function probably means cyclic key schedule f function must vulnerable known-plaintext attack slide attack closely related related-key attack idea slide attack roots paper published edna grossman bryant tuckerman ibm technical report 1977 grossman tuckerman demonstrated attack weak block cipher named new data seal nds attack relied fact cipher identical subkeys round cipher cyclic key schedule cycle one key makes early version slide attack summary report including description nds block cipher attack given cipher systems beker piper 1982 first introduce notation section assume cipher takes n bit blocks key-schedule using formula_1 keys length slide attack works breaking cipher identical permutation functions f f function may consist one round cipher defined key-schedule example cipher uses alternating key schedule switches formula_2 formula_3 round f function would consist two rounds formula_4 appear least f next step collect formula_5 plaintext-ciphertext pairs depending characteristics cipher fewer may suffice birthday paradox formula_5 needed pairs denoted formula_7 used find slid pair denoted formula_8 slid pair property formula_9 formula_10 slid pair identified cipher broken vulnerability known-plaintext attacks key easily extracted pairing slid pair thought happens message one application function f ’ slid ’ one encryption round attack gets name process finding slid pair somewhat different cipher follows basic scheme one uses fact relatively easy extract key one iteration f choose pair plaintext-ciphertext pairs formula_8 check see keys corresponding formula_9 formula_10 keys match slid pair otherwise move next pair formula_5 plaintext-ciphertext pairs one slid pair expected along small number false-positives depending structure cipher false positives eliminated using keys different message-ciphertext pair see encryption correct probability wrong key correctly encipher two messages low good cipher sometimes structure cipher greatly reduces number plaintext-ciphertext pairs needed thus also large amount work clearest examples feistel cipher using cyclic key schedule reason given formula_15 search formula_16 reduces possible paired messages formula_17 formula_5 since half message fixed formula_19 plaintext-ciphertext pairs needed order find slid pair
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Computer security
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highly available storage highly available storage hast protocol tool set freebsd written pawel jakub dawidek core freebsd developer hast provides block device synchronized two servers use filesystem two machines comprise cluster machine cluster node hast uses primary-secondary master-slave configuration one cluster node active time hast-provided devices appear like disk devices /dev/hast/ directory freebsd used like standard block devices hast similar raid1 mirror raid component provided across network one cluster node
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Operating systems
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slipstream computer science slipstream processor architecture designed reduce length running program removing non-essential instructions form speculative computing non-essential instructions include things results written memory compare operations always return true also statistically branch instructions taken makes sense assume always case speculation involved slipstream processors generally described two parallel executing streams one optimized faster a-stream executing reduced code slower r-stream runs behind a-stream executes full code r-stream runs faster single stream due data prefetched a-stream effectively hiding memory latency due a-stream assistance branch prediction two streams complete faster single stream would 2005 theoretical studies shown configuration lead speedup around 20 main problem approach accuracy a-stream becomes accurate less speculative overall system runs slower furthermore large enough distance needed a-stream r-stream cache misses generated a-stream slow r-stream
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Computer architecture
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pod slurping pod slurping act using portable data storage device ipod digital audio player illicitly download large quantities confidential data directly plugging computer data held may inside firewall work development fixes problem including number third-party security products allow companies set security policies related usb device use features within operating systems allow administrators users disable usb port altogether unix-based unix-like systems easily prevent users mounting storage devices microsoft released instructions preventing users installing usb mass storage devices operating systems additional measures include physical obstruction usb ports measures ranging simple filling ports epoxy resin commercial solutions deposit lockable plug port following external links act indirect mechanism learning topic e.g. detailed descriptions examples implementations
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Computer security
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sokoban video game version game includes 50 levels 1988 sokoban published us spectrum holobyte commodore 64 ibm-pc apple ii series soko-ban sokoban hit japan sold 400,000 units country time spectrum holobyte imported united states 1988 review computer gaming world praised spectrum holobyte soko-ban pure simple playable mentally challenging citing addictive qualities also reviewed 1988 dragon 132 hartley patricia kirk lesser role computers column reviewers gave game 4½ 5 stars
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Computer architecture
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x86 memory segmentation x86 memory segmentation refers implementation memory segmentation intel x86 computer instruction set architecture segmentation introduced intel 8086 1978 way allow programs address 64 kb 65,536 bytes memory intel 80286 introduced second version segmentation 1982 added support virtual memory memory protection point original model renamed real mode new version named protected mode x86-64 architecture introduced 2003 largely dropped support segmentation 64-bit mode real protected modes system uses 16-bit segment registers derive actual memory address real mode registers cs ds ss es point currently used program code segment cs current data segment ds current stack segment ss one extra segment determined programmer es intel 80386 introduced 1985 adds two additional segment registers fs gs specific uses defined hardware way segment registers used differs two modes choice segment normally defaulted processor according function executed instructions always fetched code segment stack push pop data reference referring stack uses stack segment references data use data segment extra segment default destination string operations example movs cmps fs gs hardware-assigned uses instruction format allows optional segment prefix byte used override default segment selected instructions desired real mode v86 mode size segment range 1 byte 65,536 bytes using 16-bit offsets 16-bit segment selector segment register interpreted significant 16 bits linear 20-bit address called segment address remaining four least significant bits zeros segment address always added 16-bit offset instruction yield linear address physical address mode instance segmented address 06efh:1234h suffix h means hexadecimal segment selector 06efh representing segment address 06ef0h offset added yielding linear address 06ef0h 1234h 08124h way segment address offset added single linear address mapped 2 4096 distinct segment offset pairs example linear address 08124h segmented addresses 06efh:1234h 0812h:0004h 0000h:8124h etc could confusing programmers accustomed unique addressing schemes also used advantage example addressing multiple nested data structures real mode segments always 64 kb long practical effect segment longer 64 kb rather every segment must 64 kb long protection privilege limitation real mode even segment could defined smaller 64 kb would still entirely programs coordinate keep within bounds segments program always access memory since arbitrarily set segment selectors change segment addresses absolutely supervision therefore real mode well imagined variable length segment range 1 65,536 bytes enforced cpu effective 20-bit address space real mode limits addressable memory 2 bytes 1,048,576 bytes 1 mb derived directly hardware design intel 8086 subsequently closely related 8088 exactly 20 address pins packaged 40-pin dip packages even 20 address lines address data buses multiplexed fit address data lines within limited pin count segment begins multiple 16 bytes called paragraph beginning linear flat address space 16 byte intervals since segments 64 kb long explains overlap occur segments location linear memory address space accessed many segment offset pairs actual location beginning segment linear address space calculated segment×16 segment value 0ch 12 would give linear address c0h 192 linear address space address offset added number 0ch:0fh 12:15 would c0h+0fh=cfh 192+15=207 cfh 207 linear address address translations carried segmentation unit cpu last segment ffffh 65535 begins linear address ffff0h 1048560 16 bytes end 20 bit address space thus access offset 65,536 bytes 65,520 65536−16 bytes past end 20 bit 8088 address space 8088 address accesses wrapped around beginning address space 65535:16 would access address 0 65533:1000 would access address 952 linear address space programmers using feature led gate a20 compatibility issues later cpu generations linear address space expanded past 20 bits 16-bit real mode enabling applications make use multiple memory segments order access memory available one 64k-segment quite complex viewed necessary evil smallest tools could less memory root problem appropriate address-arithmetic instructions suitable flat addressing entire memory range available flat addressing possible applying multiple instructions however leads slower programs memory model concept derives setup segment registers example tiny model cs=ds=ss program code data stack contained within single 64 kb segment small memory model ds=ss data stack reside segment cs points different code segment 64 kb 80286 protected mode extends processor address space 2 bytes 16 megabytes adjusting shift value instead 16-bit segment registers contain index table segment descriptors containing 24-bit base addresses offset added support old software processor starts real mode mode uses segmented addressing model 8086 small difference though resulting physical address longer truncated 20 bits real mode pointers 8086 pointers refer addresses 100000 10ffef roughly 64-kilobyte region memory known high memory area hma later versions ms-dos could use increase available conventional memory i.e within first mb addition hma total address space approximately 1.06 mb though 80286 truncate real-mode addresses 20 bits system containing 80286 hardware external processor gating 21st address line a20 line ibm pc provided hardware full backward compatibility software original ibm pc pc/xt models subsequent at-class pc clones well 286 protected mode seldom used would excluded large body users 8086/88 machines moreover still necessitated dividing memory 64k segments like done real mode limitation worked around 32-bit cpus permit use memory pointers greater 64k size however segment limit field 24-bit long maximum segment size created 16mb although paging used allocate memory individual segment may exceed 16mb method commonly used windows 3.x applications produce flat memory space although os still 16-bit api calls could made 32-bit instructions thus still necessary place code performs api calls 64k segments 286 protected mode invoked could exited except performing hardware reset machines following rising ibm pc/at standard could feign reset cpu via standardised keyboard controller significantly sluggish windows 3.x worked around problems intentionally triggering triple fault interrupt-handling mechanisms cpu would cause cpu drop back real mode nearly instantly logical address consists 16-bit segment selector supplying 13+1 address bits 16-bit offset segment selector must located one segment registers selector consists 2-bit requested privilege level rpl 1-bit table indicator ti 13-bit index attempting address translation given logical address processor reads 64-bit segment descriptor structure either global descriptor table ti=0 local descriptor table ti=1 performs privilege check cpl current privilege level found lower 2 bits cs register rpl requested privilege level segment selector dpl descriptor privilege level segment found descriptor privilege levels integers range 0–3 lowest number corresponds highest privilege inequality false processor generates general protection gp fault otherwise address translation continues processor takes 32-bit 16-bit offset compares segment limit specified segment descriptor larger gp fault generated otherwise processor adds 24-bit segment base specified descriptor offset creating linear physical address privilege check done segment register loaded segment descriptors cached hidden parts segment registers intel 80386 later protected mode retains segmentation mechanism 80286 protected mode paging unit added second layer address translation segmentation unit physical bus also importantly address offsets 32-bit instead 16-bit segment base segment descriptor also 32-bit instead 24-bit general operation segmentation unit otherwise unchanged paging unit may enabled disabled disabled operation 80286 paging unit enabled addresses segment virtual addresses rather physical addresses 80286 segment starting address offset final 32-bit address segmentation unit derived adding two virtual logical addresses paging unit enabled segmentation unit generates validates 32-bit virtual addresses enabled paging unit finally translates virtual addresses physical addresses physical addresses 32-bit 386 larger newer processors support physical address extension 80386 also introduced two new general-purpose data segment registers fs gs original set four segment registers cs ds es ss 386 cpu put back real mode clearing bit cr0 control register however privileged operation order enforce security robustness way comparison 286 could returned real mode forcing processor reset e.g triple fault using external hardware x86-64 architecture use segmentation long mode 64-bit mode four segment registers cs ss ds es forced 0 limit 2 segment registers fs gs still nonzero base address allows operating systems use segments special purposes unlike global descriptor table mechanism used legacy modes base address segments stored model-specific register x86-64 architecture provides special swapgs instruction allows swapping kernel mode user mode base addresses instance microsoft windows x86-64 uses gs segment point thread environment block small data structure thread contains information exception handling thread-local variables per-thread state similarly linux kernel uses gs segment store per-cpu data x64 cpu powers real mode indistinguishable 32-bit pentium 4 64-bit instructions used unless long mode set long mode operating 16-bit instructions virtual x86 mode disabled protected mode disappears gs/fs also used gcc thread-local storage canary-based stack protector logical addresses explicitly specified x86 assembly language e.g syntax intel syntax mov dword fs eax 42 however segment registers usually used implicitly segmentation turned x86-32 processors true 64-bit mode well beyond scope discussion many 32-bit operating systems simulate flat memory model setting segments bases 0 order make segmentation neutral programs instance linux kernel sets 4 general purpose segments since base set 0 cases limit 4 gib segmentation unit affect addresses program issues arrive paging unit course refers 80386 later processors earlier x86 processors paging unit current linux also uses gs point thread-local storage segments defined either code data system segments additional permission bits present make segments read read/write execute etc protected mode code may always modify segment registers except cs code segment selector current privilege level cpl processor stored lower 2 bits cs register ways raise processor privilege level reload cs lcall far call int interrupt instructions similarly ways lower privilege level reload cs lret far return iret interrupt return instructions real mode code may also modify cs register making far jump using undocumented codice_1 instruction 8086 8088 course real mode privilege levels programs absolute unchecked access memory cpu instructions information segmentation see ia-32 manuals freely available amd intel websites
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Operating systems
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windows activation services windows process activation service also known process activation mechanism introduced within internet information services v7.0 windows activation service builds existing internet information services v6.0 powerful provides support protocols besides http tcp named pipes windows activation service extends asp.net http hosting concept asmx web services standalone windows component windows activation service completely separated iis hosting environment provides protocol-agnostic activation mechanism limited http windows activation service allows developers choose appropriate protocol needs http data transfer relies asp.net http protocols tcp named pipes windows activation service leverages extensibility points asp.net transferring data capabilities implemented form protocol handlers manage communication worker process windows service two types protocol handlers loaded activates worker process instance process protocol handler pph app domain protocol handler adph
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Operating systems
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nokia x5 nokia x5-00/01 pair smartphones x-series nokia mobile phones original china model comes symbian os 9.3 worldwide model uses s60 3rd edition fp2 x5-00 released china second quarter 2010 x6 could released region due china still using partial-3g td-scdma mobile network mobile phones unlike selected countries started use 3.5g hsdpa mobile network although original version x5 china alternative version original x6 large on-board memory comes music service later june 2010 nokia announced x5 gain release countries china named x5-01 features wider smaller 2.36-inch screen better microsdhc support 32 gb sdhc use hsdpa network mode released september 2010 july 2018 hmd global released new android phone name nokia x5 2018 original x5 candybar mobile phone alpha-numeric keypad features carl zeiss 5-megapixel camera equipped dual led flash 256 mb internal memory use 8 gb microsd card nokia x5-01 slider mobile phone qwerty/qwertz keypad depending country sale features five megapixels camera led flash arm 11 600 mhz processor 200 mb internal memory 32 gb microsd 2 gb card included sales package x5-01 wi-fi phone models bluetooth connectivity running symbian os 9.3 series 60 v3.2 ui design original x5 mixed reviews despite china-only release design x5-01 come great criticism vastly deficient dimensions phone 74.3 × 66.4 × 16.8 mm weight 129 grams display 2.36 phone comes full qwerty keypad available six colors yellow green purple pink azure graphite black phone comes additional 3 labeled soft keys media keys volume keys navi keys
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Operating systems
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circular dependency software engineering circular dependency relation two modules either directly indirectly depend function properly modules also known mutually recursive circular dependencies natural many domain models certain objects domain depend however software design circular dependencies larger software modules considered anti-pattern negative effects however circular cyclic dependencies found widespread among source files real-world software mutually recursive modules however somewhat common functional programming inductive recursive definitions often encouraged circular dependencies cause many unwanted effects software programs problematic software design point view tight coupling mutually dependent modules reduces makes impossible separate re-use single module circular dependencies cause domino effect small local change one module spreads modules unwanted global effects program errors compile errors circular dependencies also result infinite recursions unexpected failures circular dependencies may also cause memory leaks preventing certain primitive automatic garbage collectors use reference counting deallocating unused objects large software designs software engineers may lose context inadvertently introduce circular dependencies tools analyze software find unwanted circular dependencies circular dependencies often introduced inexperienced programmers need implement kind callback functionality experienced programmers avoid unnecessary circular dependencies applying design patterns like observer pattern implementation circular dependencies c/c++ bit tricky structure class definition must placed usage file circular dependency classes b thus require definition placed b definition b placed course impossible forward declaration therefore needed accomplish following example illustrates done note although name e.g codice_1 declared multiple times forward declarations defined one definition rule following another example forward declaration might useful application needs self-sustaining array objects able add remove objects run-time static variables first last defined declaration reserve memory space note static variables change object object stay given class also initialized 0 null know start
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Programming language topics
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alcazar forgotten fortress alcazar forgotten fortress dungeon action-adventure game similar dungeon master legend zelda released 1985 coleco adam computer accessory also port colecovision created tom loughry activision graphics keri janssen longaway game also ported commodore 64 later plot alcazar get main castle alcazar going multiple enemy castles retrieve stolen crown game starts world map contains 22 castles player main goal move character various castles ultimately arrive main castle fortress right side map castle multiple rooms traps floors map routes change every time new game started game four difficulty levels beginner intermediate advanced expert various items may also obtained game pistol used attacking hook used cross gaps also map bottom left corner help prevent lost castle dungeons also many traps enemies present player either fight evade player incurs much damage lose life losing lives ends game though extra lives may also obtained well game continues adam version game supports saving game one earliest adventure games demo mode shows demonstration game play wait title screen 30 seconds game go mode ahoy praised alcazar beautifully written theme song stated graphics insufficiently detailed magazine concluded game enticing blend mental physical stimulation ... electronic passport hours entertainment
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Computer architecture
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playstation 2 online functionality selected games sony playstation 2 video game console offer online gaming online capabilities games enable feature provide free online play use broadband internet connection playstation 2 network adaptor since service official name sometimes referred either ps2 network play ps2 network gaming ps2 online service launched july 2001 japan august 2002 north america june 2003 europe slimline models network adapter integrated hardware games also allowed online gameplay using dial-up connection available models lan play connecting two network adapters/slimline consoles together directly ethernet cable router network instead unified online service like seganet xbox live online multiplayer ps2 responsibility game publisher run third-party servers however later ps2 online games required console authorized sony dynamic network authentication system dnas connecting server unofficial servers also exist could connected setting dns settings connect unofficial dns server recent ps2 online games developed exclusively support broadband internet access last official online server final fantasy xi ultimately shut march 31 2016 dnas following couple days later april 4 indirectly shutting several remaining unofficial servers exception ones support non-dnas ps2 titles tony hawk pro skater 3 despite dnas shutdown several fan created servers still exist require dnas workaround connect exceptions call duty 3 older models non-slim playstation 2 console network adapter needed play online use hard drive versions network adapter provide ethernet port north american versions also featured phone-line port dial-up connection newer slimline versions however ethernet port built making network adapter unnecessary hard drive use nearly impossible well ruling need keep network adapter production playing online games requires users set system network connection configuration saved memory card done network startup disk came network adapter using one many games utility built resident evil outbreak set network settings new slimline playstation 2 came disk box default last version disk network startup disk 5.0 included newer scph 90004 model released 2009 however december 31 2012 playstation 2 discontinued servers games since shut released 2002 final fantasy xi first ever console game offer cross-platform play connecting playstation 2 personal computer released august year one first video games allowed voice chat console pal games supported online gaming display net play logo cover north american games feature online icon lower right corner cover games support dial-up connectivity broadband also found logo time game servers shut however computer programs xbslink svdl xlink kai allow users achieve online play ps2 games using network configuration simulates worldwide lan
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Computer architecture
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trishneet arora trishneet arora born 2 november 1993 founder ceo tac security security company arora written books cyber security ethical hacking web defence named forbes 30 30 2018 asia list fortune magazine 40 40 2019 list india brightest business minds arora founded tac security cyber security company provides protection corporations network vulnerabilities data theft clients reliance industries central bureau investigation punjab police india gujarat police helps punjab gujarat police investigating cyber crimes conducted training sessions officials arora company mainly provides vulnerability assessment penetration testing services according arora increase number attacks portals companies 2016 tac security raised pre-series funding indian investor vijay kedia prior tac security inducted subinder khurana former vice president cognizant board film-maker sunil bohra working biographical film arora expected released 2019
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Computer security
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hessian web service protocol hessian binary web service protocol makes web services usable without requiring large framework without learning new set protocols binary protocol well-suited sending binary data without need extend protocol attachments hessian developed caucho technology inc company released java python actionscript adobe flash implementations hessian open source license apache license third-party implementations several languages c++ c javascript perl php ruby objective-c erlang also available open-source although hessian primarily intended web services adapted tcp traffic using hessianinput hessianoutput classes caucho java implementation
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Web technology
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tagged message delivery agent tmda open-source software application designed reduce amount junk email user receives tmda main difference anti-spam systems use controversial challenge/response system bulk mailing machines programs either unwilling save bandwidth unable due lack programming answer technical countermeasures used tmda thwart spam include
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Computer security
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port knocking computer networking port knocking method externally opening ports firewall generating connection attempt set prespecified closed ports correct sequence connection attempts received firewall rules dynamically modified allow host sent connection attempts connect specific port variant called single packet authorization exists single knock needed consisting encrypted packet primary purpose port knocking prevent attacker scanning system potentially exploitable services port scan unless attacker sends correct knock sequence protected ports appear closed port knocking usually implemented configuring daemon watch firewall log file connection attempts certain points modify firewall configuration accordingly also performed kernel level using kernel-level packet filter iptables userspace process examining packets higher level using packet capture interfaces pcap allowing use already open tcp ports used within knock sequence port knock similar secret handshake consist number tcp udp even sometimes icmp protocol packets numbered ports destination machine complexity knock anything simple ordered list e.g tcp port 1000 tcp port 2000 udp port 3000 complex time-dependent source-ip-based other-factor-based encrypted hash portknock daemon firewall machine listens packets certain ports either via firewall log packet capture client user would carry extra utility could simple netcat modified ping program complicated full hash-generator use attempted connect machine usual way portknocks stateful systems first part knock received successfully incorrect second part would allow remote user continue indeed would give remote user clue far sequence failed usually indication failure end knock sequence port expected open opened packets sent remote user time technique securing access remote network daemons widely adopted security community actively used many rootkits even year 2000 defeating port knocking protection requires large-scale brute force attacks order discover even simple sequences anonymous brute force attack three-knock tcp sequence e.g port 1000 2000 3000 would require attacker test every three port combination 1–65535 range scan port attacks uncover changes port access target system since port knocking definition stateful requested port would open correct three-port number sequence received correct order without receiving intervening packets source average case scenario requires approximately 141 trillion 65535 2 packets determine correct three-port number technique combination knock attempt-limiting longer complex sequences cryptographic hashes makes successful port access attempts extremely difficult successful port knock sequence supplied open port firewall rules generally open port ip address supplied correct knock adding dynamic functionality firewall behaviour instead using preconfigured static ip whitelist firewall authorised user situated anywhere world would able open necessary port without assistance server administrator system could also configured allow authenticated user manually close port session close automatically using timeout mechanism establish new session remote user would required reauthenticate using correct sequence stateful behaviour port knocking allows several users different source ip addresses varying levels port knock authentication simultaneously allowing legitimate user correct knock sequence firewall firewall middle port attack multiple ip addresses assuming bandwidth firewall completely consumed attacking ip address ports firewall still appear closed using cryptographic hashes inside port knock sequence defends packet sniffing source target machines preventing discovery port knock sequence using information create traffic replay attacks repeat prior port knock sequences port knocking used part defense depth strategy even attacker successfully gain port access port security mechanisms still place along assigned service authentication mechanisms opened ports implementation technique straightforward using bare minimum shell script server windows batch file command line utility client overhead server client terms traffic cpu memory consumption minimal port knock daemons complex code type vulnerability within code obvious auditable port knock system implemented ports ssh sidesteps issue brute force password attacks logins case ssh ssh daemon activated without correct port knock attack filtered tcp/ip stack rather using ssh authentication resources attacker daemon inaccessible correct port knock supplied port knocking flexible customisable system add-in administrator chooses link knock sequence activity running shell script changes implementing additional firewall rules open ports specific ip addresses easily incorporated script simultaneous sessions easily accommodated addition mitigating brute force password attacks inevitable growth logs associated process daemon port knocking also protects protocol vulnerability exploits exploit discovered could compromise daemon default configuration using port knocking listening port reduces possibility compromise software process updated authorized users would continue served provide correct knock sequence random access attempts would ignored port knocking viewed part overall network defense strategy providing protection random targeted attacks complete standalone solution network security professionals largely ignored port knocking solution past since early implementations relied solely providing correct port combinations achieve access modern port knock systems incorporate features secure cryptographic hashes blacklists whitelists dynamic attack responses increase system capability port knocking effective means maximizing server resources internet facing networks properly implemented port knocking lower overall security system effective measure provides additional layer security minimal server resource overhead worst systems port knocking introduce new security issues poor implementation expose ambivalent administration attitudes situations risk compensation port knocking totally dependent robustness port knocking daemon failure daemon deny port access users usability security perspective undesirable single point failure modern port knocking implementations mitigate issue providing process-monitoring daemon restart failed stalled port knocking daemon process systems use cryptographic hashes vulnerable ip address spoofing attacks attacks form denial service use port knocking functionality lock known ip addresses e.g administrator management stations sending packets spoofed ip address random ports servers using static addressing especially vulnerable types denials service addresses well known port knocking problematic networks exhibiting high latency port knocking depends packets arriving correct sequence access designed functionality tcp/ip hand designed function assembling order packets coherent message situations solution client continue resending correct sequence packets periodic basis sequence acknowledged server port knocking used sole authentication mechanism server security perspective simple port knocking relies security obscurity unintended publication knock sequence infers compromise devices supporting sequence furthermore unencrypted port knocking vulnerable packet sniffing network trace suitable length detect correct knock sequence single ip address thus provide mechanism unauthorised access server extension attached network compromised log files device source valid knock sequences revealing another point failure solutions treating knock sequence one-time password defeat aim simplified administration practice port knocking must combined forms authentication vulnerable replay man-in-the-middle attacks whole system effective
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Computer security
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broadway microprocessor broadway codename 32-bit central processing unit cpu used nintendo wii video game console designed ibm initially produced using 90nm soi process later produced 65nm soi process according ibm processor consumes 20 less power predecessor 180 nm gekko used nintendo gamecube video game console broadway produced ibm 300 mm semiconductor development manufacturing facility east fishkill new york bond assembly test operation broadway module performed ibm facility bromont quebec official details released public nintendo ibm unofficial reports claim derived 486 mhz gekko architecture used gamecube runs 50 faster 729 mhz powerpc 750cl released 2006 stock cpu offered ibm virtually identical broadway difference 750cl came variants ranging 400 mhz 1000 mhz
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Computer architecture
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nec riscstation nec riscstation line computer workstations made nec mid-1990s based mips risc microprocessors designed run microsoft windows nt series nearly identical machines also sold nec headless i.e. video card framebuffer configuration riscserver series intended use windows nt workgroup servers riscstations based modified jazz architecture licensed mips computer systems inc. originally designed microsoft although architecturally similar contemporaneous intel 80386-based personal computers including example pci bus riscstations faster pentium-based workstations time although based jazz design riscstations use g364 framebuffer instead using s3 968-based video card 3dlabs glint-based adapter pci slot riscstations used standard ibm at-style tower minitower case motherboard also met form factor standard pci peripherals video card peripheral expansion several operating systems supported riscstations like jazz-based mips computers mips magnum riscstations ran arc console firmware boot windows nt little-endian mode mips iii architecture capable either little-endian big-endian operation however microsoft stopped supporting mips architecture windows nt version 4.0 riscstations ceased production 1996 addition windows nt nec ported version unix system v riscstation although support lacking linux/mips riscstation series supported netbsd netbsd/arc supported openbsd prior termination port 1998 riscstation line included march 1995 dual-cpu configuration riscstation 2000 priced 14,000 came equipped two 150 mhz mips r4400 cpus 64 mb ram 1 gb scsi hard drive 3x cd-rom drive 17-inch nec-brand crt monitor
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Computer architecture
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t.38 t.38 itu recommendation allowing transmission fax ip networks foip real time t.38 fax relay standard devised 1998 way permit faxes transported across ip networks existing group 3 g3 fax terminals t.4 related fax standards published itu 1980 rise internet late 1990s voip voice ip began gain ground alternative conventional public switched telephone network pstn however voip systems optimized use aggressive lossy bandwidth-saving compression voice rather data calls conventional fax machines worked poorly due network impairments delay jitter packet loss thus way transmitting fax ip needed practical scenarios t.38 fax call least part call carried pstn although required t.38 definition two t.38 devices send faxes particular type device called internet-aware fax device iaf capable initiating completing fax call towards ip network typical scenario t.38 used t.38 fax relay t.30 fax device sends fax pstn t.38 fax gateway converts encapsulates t.30 protocol t.38 data stream sent either t.38 enabled end point fax machine fax server another t.38 gateway converts back pstn pcm analog signal terminates fax t.30 device t.38 recommendation defines use tcp udp transport t.38 packets implementations tend use udp due tcp requirement acknowledgement packets resulting retransmission packet loss introduces delays using udp t.38 copes packet loss using redundant data packets t.38 call setup protocol thus t.38 devices need use standard call setup protocols negotiate t.38 call e.g h.323 sip mgcp two primary ways fax transactions conveyed across packet networks t.37 standard specifies fax image encapsulated e-mail transported ultimately recipient using store-and-forward process intermediary entities t.38 however defines protocol supports use t.30 protocol sender recipient terminals see diagram t.38 lets one transmit fax across ip network real time original g3 fax standards traditional time-division multiplexed tdm network also called public switched telephone network pstn special protocol needed real-time fax ip internet protocol since existing fax terminals supported pstn connections information flow generally smooth uninterrupted opposed jittery arrival ip packets trick come protocol makes ip network “ invisible ” endpoint fax terminals would mean user legacy fax terminal need know fax call traversing ip network network interconnections supported t.38 shown two fax terminals either side figure communicate using t.30 fax protocol published itu 1980 interconnection pstn ip packet network requires “ gateway ” pstn ip networks pstn-ip gateways support tdm voice pstn side voip foip packet side voice sessions gateway take voice packets ip side accumulate packets ensure smooth flow tdm data upon release meter tdm eventually heard human stored computer later playback gateway employs packet-management techniques enhance quality speech presence network errors taking advantage natural ability listener really hear occasional missing repeated packet facsimile data transmitted modems ’ forgiving human ear speech missing packets often cause fax session fail worst create one image lines error best job t.38 “ fool ” terminal “ thinking ” ’ communicating directly another t.30 terminal also correct network delays so-called spoofing techniques missing delayed packets fax-aware buffer-management techniques spoofing refers logic implemented protocol engine t.38 relay modifies protocol commands responses tdm side keep network delays ip side causing transaction fail done example padding image lines deliberately causing message re-transmitted render network delays transparent sending/receiving fax terminals networks packet loss excessive delay exhibit acceptable fax performance without t.38 provided pcm clocks gateways high accuracy explained t.38 removes effect pcm clocks synchronized also reduces required network bandwidth factor 10 corrects packet loss delay shown diagram t.38 gateway composed two primary elements fax modems t.38 subsystem fax modems modulate demodulate pcm samples analog data turning sampled-data representation fax terminal ’ analog signal binary translation vice versa pstn network samples analog signal voice modem signal ’ know difference 8,000 times per second sps encodes 8-bit data bytes means 8000 samples-per-second times 8-bits per sample 64,000 bits per second bit/s represent modem voice data one direction directions modem transaction consumes 128,000 bits network bandwidth however typical modem fax terminal transmits image data 33,600 bit/s analog data first converted digital content represent 33,600 bits plus network overhead bytes needed since t.30 fax half-duplex protocol network needed one direction time refer rfc 3261 diagram sample-rate clock fax terminal one gateway ’ modems used trigger sampling analog line 8,000 times per second clocks usually quite accurate low-cost terminal adapters one two-line gateway pcm clock surprisingly inaccurate terminal sending data gateway gateway ’ clock slow buffers jitter buffers gateway eventually overflow causing transaction fail since difference often quite small problem occurs long detailed fax images giving clocks time cause jitter buffer gateway either underflow overflow missing duplicated packets t.38 provides facilities eliminate effects packet loss data redundancy packet sent either zero one two three even previously sent packets repeated specification impose limit increases network bandwidth required ’ still much less using t.38 allows receiving gateway reconstruct complete packet sequence even fairly high level packet loss
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Internet protocols
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diameter credit-control application diameter credit-control application networking protocol diameter application used implement real-time credit-control variety end user services ietf standard first defined rfc 4006 updated rfc 8506 purpose diameter credit control application provide framework real-time charging primarily meant communication gateways/control-points back-end account/balance systems typically online charging system application specifies methods diameter credit control application specify type units bought/used items charged left service context specified separately semantics examples units used/bought examples items charged diameter credit control also specifies handle fairly complex issue multiple unit types used/charged single user balance instance user may pay online time download bytes single account balance session-based credit control process uses several interrogations may include first intermediate last interrogation interrogation money reserved user account session-based charging typically used scenarios charged units continuously consumed e.g charging bytes upload/download event-based credit control process uses events charging mechanism event-based charging typically used units continuously consumed e.g user sending mms order support credit control via diameter two diameter messages ccr credit control request cca credit control answer command code ccr/cca 272 defined rfc 4006 quota management client sends ccr server requesting units reporting consumption server grants units charges user simple debit/credit client sends ccr asking server credit/debit user account price inquiries client ask server price unit server responds price message flows general driven control-point asking units server granting message may also generated diameter applications nasreq rfc4005 sessions time/usage-limited following diagram shows simplified message flow session using quota grants client starts requesting 10 units server server verifies user/subscriber enough balance example server grants client units requested subscriber insufficient balance could granted less units rejected completely subscriber session used granted units client sends update server telling many units used many would like granted time client allowed request units previous grant completely used order avoid suspending subscriber session talking server example client sends request 7 units 10 previously granted units used ask 10 units server grants server use used-units count debiting subscriber balance granting units indicate used used-units avp contains actual usage also possible server tell client long grant valid case client expected send update grant timer expires many update messages session finally subscriber ended session client sends termination message server containing last used-units server use termination message clear related reservations made back-end balance management system subscriber terminate session instead depleted balance server would responded earlier reject update message possibly telling client/control-point redirect traffic normally makes sense http/wap traffic new command codes cca ccr may require avps indicated bold avps new dcca table uses following symbols
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Internet protocols
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fado fado stands false authentic documents online european image-archiving system set help combat illegal immigration organised crime established joint action council european union enacted 1998 proliferation genuine false documents means frequent updating essential ever sophisticated techniques used produce genuine documents forgeries computerised system restricted access therefore built enables fast secure information exchange general secretariat council european union document experts european union member states iceland norway switzerland database established fado joint acts includes following data fado currently available document experts 31 fado partner states member states european union eu iceland norway switzerland part information shared document experts classified restricted system fado made publicly available via public register authentic documents online prado website managed council european union document descriptions fado available 24 official languages european union documents introduced document experts languages standardised descriptions translated automatically thus documents immediately available supported languages additional free text information contained translated later specialised linguists general secretariat council
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Computer security
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settlers iv settlers iv released settlers fourth edition north america real-time strategy video game city-building elements developed blue byte published ubi soft released germany microsoft windows february 2001 united kingdom march north america august fourth game settlers series following settlers 1993 settlers ii 1996 settlers iii 1998 august blue byte released expansion settlers iv mission cd featuring new single-player campaign missions new maps single-player multiplayer modes random map generator map editor gameplay improvements bug fixes december released second expansion settlers iv trojans elixir power containing new single-player campaigns additional single multiplayer maps improved graphics additional gameplay tweaks march 2002 settlers iv gold edition released containing original game expansions plus fan-made maps multiplayer mode two minigames november 2009 gameloft ported original game ios title settlers although featuring updated graphics utilising touch controls gameplay game mechanics storyline identical original april 2010 settlers released webos specifically optimised palm pre gameloft later released hd versions ipad bada symbian android 2013 gold edition released gog.com 2018 game re-released settlers iv history edition game single-player campaign player controls three races romans vikings mayans initially fight one another joining forces combat much greater threat posed exiled god morbus banished earth instigating failed rebellion great god unable bear touching foliage morbus leads mysterious dark tribe sets attempting erase natural greenery planet surface trojans elixir power takes place many centuries later war dark tribe faded memory three victorious civilisations returned fighting one another however morbus proves threat attempting permanently cure allergy greenery creating powerful elixir falls trojans unite others stand dark tribe acting feedback fans felt settlers iii focused combat designers aimed return core supply demand-based gameplay first two titles series result game designed strike balance economic planning military conquest although basic gameplay remains relatively unchanged settlers iii game mechanics altered example first time series offensive strength player military tied economic value settlement player access rank soldier beginning mission ability select rank every soldier prior recruitment game single-player campaign focuses race defeated solely military means specialty units squad leaders added enhance tactical aspects combat warships also made available allowing combat sea settlers iv received mixed reviews critics feeling similar settlers iii many opining blue byte failed steer gameplay away over-reliance combat although graphics animations generally praised ai mission variety limited combat strategy criticised reviews comparing game unfavourably titles age empires ii handheld version received positive reviews lauded replicating original game portable device successfully adapting controls touchscreen common criticism concerned lack free play multiplayer modes settlers iv real-time strategy game city-building elements controlled via point click interface general gameplay game mechanics similar settlers iii primary goal maps build settlement functioning economy producing sufficient military and/or specialist units conquer rival territories achieve end player must engage economic micromanagement construct buildings generate resources game played one two modes single-player multiplayer single-player mode player play either campaign missions individual non-campaign games free maps campaign mode player must complete series missions goal defeat computer controlled opponent opponents gaining possession territory case dark tribe destroying temple using gardeners original release game three separate campaigns three missions one campaign romans vikings mayans fourth campaign twelve missions player controls three races fight dark tribe mission cd expansion added three additional campaigns five missions race plus three settlement missions three conflict missions trojans elixir power expansion added three campaigns four missions original three races four settlement missions new campaign twelve missions player controls trojans dark tribe free maps multiplayer mode played via lan online player chooses map play refines game various ways adjusting number computer controlled opponents amount raw materials available start game and/or victory conditions player also select type game played choosing conflict mode player/race competes one another ranking list players receive points end game ranking blue byte online league table cooperation mode players combine forces achieve predetermined objective computer controlled races economic mode winner player produce goods least four seven categories within time limit settlefest players compete separate identical single-player maps first reach given objective free settle mode one player/race whether playing single-player multiplayer mode game begins way player small settlement set amount raw materials tools predetermined number settlers basic gameplay revolves around serfs titular settlers transport materials tools produce populate perform requisite task building settlers iii new settlers acquired construction residences point player directly control normal settler instead general orders issued ordering construction building ai handling delegation orders specific settlers however player control specialist settlers four types pioneers extend player territory digging border thieves scout enemy territory steal resources geologists test mountainous ground raw materials gardeners reclaim terrain corrupted dark tribe playing multiplayer game player also access fifth specialist unit saboteur attack destroy enemy buildings military installations settlers iii players construct road network instead settlers walk freely around player territory ai handling pathfinding like previous games series settlers iv adjustable goods priority system determines order items transported players also build marketplaces allow establishment trade routes areas geographical region shipyards allow manufacture warships ferries transport specialist settlers soldiers war machines trade ships transport items landing dock different geographical region original game player controlled three races romans vikings mayans trojans elixir power added trojans fourth race settlers iii race slightly different economic model example romans trojans construction industries require roughly equal amounts wood stone vikings wood stone mayans stone wood race also specific skills example romans produce manna using two buildings vikings build war machines warships use manna rather physical ammunition mayans utilise desert terrain grow agave plants necessary production tequila economy player control throughout game adjustable multiple ways example player control distribution goods selecting percentage given resource transported given building similar manner player select tools made tool production important insofar buildings require raw materials worker right tool example player built mine building still empty despite presence idle settlers pickaxe need manufactured toolsmith game also uses notification system alerts player building occupied either due lack right tool absence available settlers settlers iii game features magic whereby race call upon deities economic and/or military assistance player manna priests finite access number spells nature depends race spells include limited tuning fish stone turning enemy soldiers allies romans turning stone iron temporarily freezing enemies vikings turning wood gold turning enemy bowmen butterflies mayans turning sulphur iron turning enemy soldiers normal settlers trojans player territory expanded using pioneers building military complex near territory border complex must least one soldier garrisoned territory expand recruit soldiers player must build barracks individual soldier requiring requisite weapon transition settler soldier player also build lookout towers manned regular settlers see great distances n't grant new territory three classes soldier common races swordsmen bowmen squad leaders level swordsmen bowmen set player prior recruitment types soldier three ranks determined amount gold necessary recruitment gold level 1 one gold bar level 2 two gold bars level 3 squad leaders available one rank require sword suit armour three gold bars recruit well stronger health level 3 swordsman also affect troops around improving formations increasing combat strategy enhancing abilities additionally player assigns squad leader group soldiers orders need issued squad leader squad automatically follow destination ordered player race also produce warships war machines catapults romans magical lightning generators vikings canons mayans ballistae trojans special military units medics romans axe warriors vikings blowgun warriors mayans backpack catapultists trojans swordmen bowmen special military units three levels recruitment order player attack enemy building must click near building soldiers selected player units defeat soldiers stationed building occupy player territory increasing according building radius defense player military buildings automatic enemies attack soldiers stationed building defend nearby soldiers also defend building unless ordered soldiers fighting within territory strength always 100 fighting outside strength tied economic value settlement especial importance improving strength one army eyecatchers decorative monuments worth double construction value relation player military strength game begins shortly failure rebellion instigated dark god morbus great god treachery banishes morbus earth morbus hated place universe due vast amounts greenery unable bear touching foliage morbus determines destroy earth plant life dark gardener eventually develops substance known shadow-weed sucks energy land killing nearby foliage transforming terrain blackened wasteland dark lands meanwhile unaware presence morbus war raging three races recently come contact one another romans vikings mayans first encounter dark lands romans whose scouts return word effects shadow-weed initially believe new mayan weapon result romans attack destroy nearby mayan colony quickly realise dark lands mayans mayans also encountered dark lands suggest temporary alliance romans reluctantly agree however begin investigate dark lands mayans turn elsewhere vikings also encounter effects shadow-weed discover one sacred burial grounds surrounded dark lands setting reclaim territory attacked army mindless soldiers nearby romans learn secret dark army created human settlers converted shamans servants morbus thus forming dark tribe put work mushroom farms converting mushroom spores manna transported nearest dark temple used create dark army clearer understanding dark tribe romans ally vikings determine destroy farms however mayans see alliance romans vikings direct threat attacking colonies belonging realise alliance focused attacking combating dark tribe time however find surrounded dark lands despite previous animosity romans vikings save mayans three unite going offensive effort wipe dark tribe eventually vikings locate believe final dark temple destroy remnants dark tribe survive rally final battle secure knowledge one victory required mayans launch attack prove victorious dark tribe temples farms eradicated way breeding new troops morbus retreats lair begging mercy morbus horrified see vines infesting building quickly wrapping around turning stone trojans elixir power begins many centuries events main game morbus remains petrified state territory controlled trojans unaware races morbus identity war dark tribe story begins morbus assistant q'nqüra spreads shadow-weed around statue releasing trojans discover statue gone effects shadow-weed spreading elect abandon area landing new island encounter friendly romans hostile mayans allying romans trojans tell disappearance morbus statue romans tell history war call meeting four races shocked however learn dark tribe using aerial vehicles dubbed manacopters easily infiltrate lines inflict huge losses romans vikings mayans attacked trojans tasked destroying dark tribe research lab manacopter blueprints raid lab however discover morbus plan dark gardeners attempting create elixir cure inability touch greenery using complex combination herbs one herb final breakthrough four races divide land sectors search final herb shortly thereafter vikings locate priests begin harvest dark tribe soon arrive trojans develop poison use herb vikings unable harvest time viking priest ambushed killed dark tribe acquire herb however remains unclear priest able use poison death meanwhile morbus temple located trojans lead assault succeed destroying morbus able create drink elixir emerging ruins temple see greenery surrounding laughs declares nothing stop game cuts time later site temple stands small cottage garden full blooming flowers morbus emerges cottage happily attends garden fully cured hatred foliage settlers iv announced blue byte ects august 1999 however volker wertich created settlers series designed programmed original settlers settlers iii would involved development later explained blue byte wanted ready release christmas 2000 opinion sufficient time create worthy title game first shown e3 event may 2000 blue byte stated gameplay would emphasise economic planning military conquest citing negative feedback fans felt settlers iii combat-orientated designers intended new game return core supply demand-based gameplay settlers settlers ii also revealed game would feature three playable races romans vikings mayans new non-playable race dark tribe speaking importance dark tribe economic-based gameplay project manager co-designer hans-jürgen brändle explained interview gameszone brändle stated made sure balance settling combat virtually every rule change new feature addressing game would feature nearly identical economic processes settlers iii despite refocused gameplay explained majority feedback gave us clear understanding economy settlers simply great game artificially inflated new goods people fun ease playing overwhelmed unnecessarily complex contexts speaking ign later year brändle reiterated designers hopes game would fully integrate economic-based settling combat previous title three races game brändle explained developers chose romans traditional settlers race vikings fan-requested race mayans needed race used stone wood construction industry developers felt mayans somewhat historically mysterious culture gameszone interview brändle also addressed issue similarity graphics new game settlers iii explaining deliberately programmed engine much like previous one wanted make fans feel like back familiar world settlers settlers iii buildings game created using 3d studio max adobe photoshop used create textures race assigned specific artist worked nothing except buildings particular race according lead artist/co-designer/co-writer torsten hess done style buildings within people uniform however certain overriding rules individual artists adhere one important technique hess employed settlers iii textures applied dirtied create lived-in real-world sense hess explains rigid straight edges avoided beautiful curves moving lines instead used suggest life settlers world textures means stronger colours slightly higher contrast figures well lot detail use many different colour families definitely want avoid sterile look also draw textures hand settlers designers also used basic techniques developed settlers iii figures could n't graphically complex since small details would lost given size 32 pixels height however time designs detailed enough seem least somewhat realistic even small size solve problem settlers proportions exaggerated weapons tools designed proportionally big correctly sized implements would far small seen process animating settlers character animator/co-writer thorsten wallner explains place skeleton behind settler controls movement sequences skeleton dictates standard movements bending running standing additional animations added individual characters technology need animate every settler anew add additional animations july 2000 blue byte advertised 5,000 participants online closed beta however beta postponed early august due technical issues related lobby software causing disruption battle isle andosia war late august blue byte revealed would least mid-september beta began october blue byte released smack thief minigame designed promote main game variation whac-a-mole smack thief player must click viking thieves raid roman stores escape available free download blue byte website game allowed players upload high scores global high score table early november online beta cancelled blue byte stating decided take step concentrate completing game conducting large public beta test requires lot additional resources want invest specifically development quality assurance instead ensured internal testing department interview planet games brändle explained resources filter sort anticipated feedback beta test currently concentrating exclusively completion product following week blue byte announced slated december release pushed back january 2001 thomas hertzler blue byte ceo series producer explaining know many gamers particularly looking forward settlers iv year course understand settlers fans disappointed end however made decision players mind settlers iv shelves christmas fans receive game corresponds blue byte high quality standard january german release date pushed back february 15 february 6 ubi soft announced acquisition blue byte revealing plans publish game internationally president ceo yves guillemot stating february 15 game released germany planned however suffered numerous bugs leading negative reaction fans criticism game blue byte german gaming press although blue byte issued patch day game released introduced additional problems leading negative press second patch released four days later correct problems introduced first patch according german magazine pc games 76 players experienced technical difficulties release version game co-designer thorsten mutschall later admitted ready release february held back additional playtesting programming march 19 ubi soft announced game would released throughout europe end month explaining reasons behind unfortunate delay product essentially quality assurance issues november 2009 working conjunction blue byte license ubisoft gameloft ported game ios released title settlers april 2010 game ported webos specifically optimised use palm pre september gameloft released hd versions ipad bada optimised wave s8500 settlers hd later released symbian january 2011 android may although handheld versions game feature updated graphics gameplay game mechanics identical original storyline including full twenty-one single-player missions original release three roman missions three viking missions three mayan missions twelve mission dark tribe campaign main change game involves hud redesigned accommodate touchscreen controls example rather building menu always present onscreen accessed pressing icon opens build menu within menu player access various submenus basic buildings food buildings military buildings similarly access menu control specialist settlers player touches another icon available player settlers available pressing icon two seconds brings brief help screen icon pausing game allows player access full help menu replacing extended tool tips appeared on-screen original settlers iv received mixed average reviews aggregate score 74 100 metacritic based five reviews 71 gamerankings based seventeen reviews ios version received positively aggregate score 79 gamerankings based six reviews pc player damian knaus scored original game 85 100 giving gold player award although impressed dark tribe criticised integration gardeners gameplay calling unnecessary extravagance also critical lack real innovations absence female settlers however despite reservations felt game best settlers title thus far especially impressed graphics pc games rüdiger steidle scored 77 lowest score magazine ever given settlers title issue review appeared editorial justifying score text box within review titled 77 magazine stated review steidle criticised game similarity settlers iii writing blue byte altered concept although praised graphics tutorials variety mission objectives critical bugs writing typical blue byte fashion game appeared time first patch concluded anyone like fan series disappointed pc gamer jim preston scored 72 although praised economic system game built criticised lack variety within writing 're forced create entire supporting infrastructure settlement way every time also referred gameplay complication masquerading depth ign dan adams scored 7 10 comparing unfavourably biggest criticism concerned lack differentiation settlers iii writing aside improved graphics small additions hard tell really new game also critical ai pathfinding repetitive missions felt designers failed steer gameplay away over-reliance combat although praised graphics animations game great personality concluded blue byte n't managed find new ideas might keep series becoming serious pool stagnant gaming quickly becoming gamespy bernard dy scored 67 100 comparing unfavourably age empires ii like adams felt similar settlers iii although praised appealing graphics fascinating animations felt blue byte failed return gameplay economic focus writing nearly every scenario race build military also criticised ai lack combat strategy mission variety however praise free settle multiplayer modes concluded settlers fourth edition charming moments long surpassed games better character superior combat gamespot ron dulin scored 6.4 10 finding similar problems adams dy comparing unfavourably impressions games city building series finding similar settlers iii felt blue byte failed move away reliance combat also criticised mission variety lack combat strategy writing never complex moving units slowly enemy territory hoping 'll left opponent n't although praised basic supply demand-based gameplay graphics concluded settlers fourth edition really old game old problems computer gaming world mark asher scored 3 5 criticising scenarios differ minor ways arguing best part game free settler mode although praised graphics called game pleasant enough experience noted offered major differences previous settlers titles would interest existing fanbase opined may getting bored formula game commercial success 2001 highest selling german-developed game february 2002 awarded platinum award verband der unterhaltungssoftware deutschland e.v vud award given titles costing dm55 sell 200,000 units nationally within first twelve months release august 2002 game sold 300,000 units germany appspy andrew nesvadba scored ios version 5 5 praising graphics touchscreen controls writing settlers everything great strategy games easy enough jump muck around progressing ultimately complex amazingly detailed set interactions players learn arron hirst 148apps scored 4 5 although critical lack free play multiplayer modes praised controls replication original game mechanics concluding game immersive addicting toucharcade also scored 4 5 criticising lack free play praising graphics sound effects calling game solid experience pocket gamer tracy erickson scored 8 10 giving silver award calling surprisingly good largely positive although critical lack free play multiplayer modes felt playing area oftentimes cluttered icons menus concluded praising deep economic strategy gameplay pocket gamer wayne turton scored bada version settlers hd 7 10 giving bronze award praising tutorials controls graphics however critical absence non-campaign missions multiplayer mode combat system writing victory usually comes side field units concluded magical quality settlers hd draws depth keep playing symbian ewan spence scored symbian version 76 although critical ai feeling screen becomes cluttered especially combat concluded hits required marks game like pocket gamer brendan caldwell scored android version 8 10 giving silver award calling almost resounding victory although critical tutorials felt n't adequately explain intricacies game controls argued n't quite accuracy speed truly emulate traditional mouse keyboard setup concluded depth often enjoyed android titles settlers hd enthralling game game first expansion settlers iv mission cd released germany august 2001 featuring three five-mission single-player campaigns three settlement missions focusing building player settlement achieving economic goals opposed military conquest three conflict missions focusing combat sixteen new maps single-player mode eighteen new maps multiplayer mode terms gameplay mission cd features improved ai varied mission objectives sophisticated scripting within missions higher difficulty single-player games expansion also features random map generator map editor numerous bug fixes stabilisations blue byte released second expansion settlers iv trojans elixir power december featuring thirteen new maps single-player mode thirteen new maps multiplayer mode three new four-mission single-player campaigns original three races four settlement missions new twelve-mission campaign player controls new race trojans expansion also features improved graphics adjustable difficulty random map generator map editor included mission cd terms gameplay importance eyecatchers modified whereas original game player could increase offensive strength beyond 100 building enough eyectachers building large numbers single eyectacher trojans elixir power maximum offensive strength achievable 100 reached player builds least one every eyecatcher released march 2002 settlers iv gold edition contains original game mission cd trojans elixir power also features fan-made maps multiplayer mode smack thief minigame new minigame dark side microsoft windows wallpapers settlers -themed skins winamp icq 2013 gold edition released gog.com blue byte later released two german-language expansions november 2002 released die siedler iv die neue welt set shortly vikings discover america game begins mayans organising feast vikings travelling europe aim taking possession wonders world beginning colossus rhodes vikings meanwhile discover map amongst mayans possessions leading mythological island inhabited women promptly set find trojans expelled troy romans searching new homeland head west time romans attempting reconquer world beginning newly discovered continent expansion features four five-mission single-player campaigns one three original races one trojans multiple objectives many optional economic-based rather military-based also two new single-player maps three new multiplayer maps enhanced graphics textures november 2003 released die siedler iv community pack expansion features four fan-created single-player campaigns based real historical conflicts roman attack carthage third punic war viking invasion england huaxtec resistance spanish conquistadors battle troad wars diadochi november 2018 ubisoft re-released game standalone history edition part settlers history collection optimised windows 10 re-release contains original game mission cd trojans elixir power die neue welt community pack expansions features autosave 4k monitor support dual monitor support adjustable resolutions texture quality vsync online multiplayer available uplay history collection also includes re-releases settlers settlers ii settlers iii
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Operating systems
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iphone 5s iphone 5s stylized marketed iphone 5s smartphone designed marketed apple inc seventh generation iphone succeeding iphone 5 device unveiled september 10 2013 apple cupertino headquarters released september 20 2013 along lower-cost counterpart iphone 5c iphone 5s maintains almost external design predecessor iphone 5 although 5s received new white/gold color scheme addition white/silver space gray/black 5s vastly upgraded internal hardware however introduced a7 64-bit dual-core system-on-chip first 64-bit processor used smartphone accompanied m7 motion co-processor redesigned home button touch id fingerprint recognition system used unlock phone authenticate app store itunes store purchases also introduced camera also updated larger aperture dual-led flash optimized different color temperatures iphone 5s originally shipped ios 7 introduced revamped visual appearance among new features designed jony ive ios 7 departed skeuomorphic elements used previous versions ios favor flat colorful design among new software features introduced iphone 5s airdrop ad-hoc wi-fi sharing platform control center control panel containing number commonly used functions itunes radio internet radio service earphones known earpods included 5s apple released accessories including case dock reception towards device generally positive outlets considering best smartphone available market due upgraded hardware touch id changes introduced ios 7 criticized iphone 5s keeping design small display iphone 5 others expressed security concerns touch id system nine million units iphone 5s iphone 5c sold weekend release breaking apple sales record iphones iphone 5s best selling phone major u.s. carriers september 2013 iphone 5s succeeded apple flagship smartphone larger iphone 6 september 2014 march 21 2016 5s received direct replacement announcement iphone se incorporated internal hardware similar iphone 6s retaining smaller form factor design 5s iphone 5s iphone supported six major versions ios second ios device support six major updates first ipad 2 supported ios 4 9 official unveiling media speculation primarily centered reports next iphone would include fingerprint scanner including apple july 2012 acquisition authentec developer mobile security products references fingerprint sensor home button beta release ios 7 leaked packaging iphone 5s showing traditional home button metallic ring around similar ring-based imagery seen official invitation apple iphone press event september 2013 new device unveiled shortly official unveiling wall street journal also reported rumor apple announced iphone 5c iphone 5s media event cupertino headquarters september 10 2013 iphone 5c became available preorder september 13 2013 iphone 5s available preorder devices released september 20 2013 promotion focused touch id 64-bit apple a7 processor also highlight event schiller showed demos infinity blade iii demonstrate a7 processing power device camera using untouched photographs release ios 7 september 18 2013 also announced keynote iphone 5s released september 20 2013 united states united kingdom canada china france germany australia japan hong kong singapore released 25 additional countries october 25 2013 12 countries november 1 2013 indonesia last country receive iphone 5s january 26 2014 september 19 2014 iphone 5s succeeded apple flagship smartphone iphone 6 iphone 6 plus older model remained available purchase reduced price 64gb version discontinued gold edition iphone 5s discontinued september 9 2015 apple revealed iphone 6s iphone 6s plus iphone 5s discontinued march 21 2016 succeeded iphone se continues form factor features vastly upgraded internals similar flagship iphone 6s break apple product positioning trend north america western europe starting iphone 4s released october 2011 gave newly released model one year flagship phone moving midrange second year production third final year entry-level offering discontinuation iphone 5s expected continue sale september 2016 replacing a7 processor early meant apple reduced long-term chip support window year ios addition new iphone launch meant stimulate demand sales iphone 6s 6s plus met expectations since september 2015 release iphone family expected suffer first ever negative growth quarter 2016 iphone 5s maintains similar design iphone 5 lcd multi-touch retina display screen resolution 640×1136 326 ppi home button updated new flat design using laser-cut sapphire cover surrounded metallic ring button longer concave contain familiar squircle icon seen previous models phone thick weighs phone uses aluminum composite frame device available three color finishes space gray replacing black slate trim iphone 5 white silver trim white gold trim iphone 5s first iphone available gold color decision influenced fact gold seen popular sign luxury product among chinese customers iphone 5s powered apple a7 system-on-chip first 64-bit processor ever used smartphone device operating system pre-loaded software optimized run 64-bit mode promising increased performance although third-party app developers would need optimize apps take advantage enhanced capabilities a7 processor designed apple manufactured samsung a7 processor accompanied m7 motion co-processor dedicated processor processing motion data iphone accelerometer gyroscopes without requiring attention main processor integrates ios 7 new coremotion apis a7 soc m7 motion co-processor also found ipad air ipad mini 2 released quarter iphone 5s phone includes 1560 mah battery provides 10 hours talk time 250 hours standby time camera still 8 megapixels resolution image capture size 3264 × 2448 4:3 lens larger aperture 2.2 larger sized pixels image sensor previous iphone models flashlight dual true tone flashes consisting amber led white led variably used based color temperature photo improve color balancing camera also includes automatic image stabilization dynamic tone mapping 10 fps burst mode best shot mode slow motion video 120 fps home button iphone 5s incorporates fingerprint recognition system known touch id based technology authentec company apple acquired 2012 sensor uses capacitive cmos-based sensor detect sub-epidermal layers fingers 500 pixels per inch uses 360-degree design read print angle sensor activated touch-sensitive metallic ring surrounding button touch id used various authentication activities within operating system unlocking device authenticating app store itunes purchases instead apple id password sensor trained recognize fingerprints multiple fingers multiple users fingerprint data stored encrypted format within secure enclave a7 chip accessible apps servers including icloud iphone 5s camera paired double led flash allowing higher quality nighttime photos included ios 7 new camera app allowing iphone 5s capture fast continuous shots record slow-motion videos earphones known apple earpods included iphone 5s according technology commentators design earphones aimed improve sound quality allowing air travel freely apple states design earphones allows rival high-end headphones cost hundreds dollars reviews gizmodo techradar reported although earphones sounded better predecessor reviewers felt quality sound produced poor techradar opined earpods inferior earphones similar price iphone 5s initially supplied ios 7 released september 20 2013 jonathan ive designer ios 7 new elements described update bringing order complexity highlighting features refined typography new icons translucency layering physics gyroscope-driven parallaxing major changes design design ios 7 os x yosemite version 10.10 noticeably departs skeuomorphic elements green felt game center wood newsstand leather calendar favor flat colorful design ios 7 adds airdrop ad-hoc wi-fi sharing platform users share files iphone 5 onwards ipod touch 5th generation ipad 4th generation onwards ipad mini 1st generation onwards operating system also adds control center control panel accessed swiping bottom screen control center contains number commonly used functions volume brightness controls along toggles enabling wi-fi bluetooth airplane mode using rear camera flash led flashlight itunes radio internet radio service also included iphone 5s free ad-supported service available itunes users featuring siri integration ios users able skip tracks customize stations purchase station songs itunes store users could also search history previous songs apple announced june 2018 iphone 5s support ios 12 update made iphone 5s longest supported ios device supported six major versions ios operating system par ipad 2 supported ios 4 ios 9 iphone 5s also receive major speed boosts 70 according apple includes camera keyboard functions supported 6 versions ios ios 7 ios 12 iphone revealed iphone 5s receiving ios 13 update debuted june 3 2019 wwdc come later 2019 autumn keynote apple announced case iphone 5s made soft microfiber inside leather outside case announced along iphone 5c case first cases apple announced since iphone 4 bumpers docks iphone 5s 5c found apple online store announcement casing difference iphone 5s 5c separate docks made specifically respective phone iphone 5s received mostly positive reception reviewers commentators walt mossberg things digital gave phone favorable review saying touch id sounds like gimmick ’ real advance biggest step ever biometric authentication everyday devices labeled best smartphone market david pogue new york times praised touch id said innovation smartphone market saturated maybe age annual mega-leaps focused much review ios 7 believed biggest change device previous generations praising new siri features control center airdrop editorial pogue stated ios 7 biggest change iphone series citing utilitarian interface changes main contributor scott stein cnet criticized lack design change iphone 5 said although iphone 5s required upgrade easily fastest advanced apple smartphone date although praised camera 64-bit a7 chip m7 motion-chip fingerprint scanning capabilities investors thought iphone 5s although notable improvement iphone 5 still relatively unchanged predecessor worried iphone line become stagnant dull product apple share price fell 5.4 launch close month low 467.71 nasdaq darrell etherington techcrunch praised iphone 5s best smartphone available said looks may different iphone 5 internal components dramatic impact day-to-day activities normal smartphone user went detail explaining impact improved camera specifications phone etherington suggested 64-bit a7 processor reach full potential developers create applications supporting myriam joire engadget found iphone 5s could benefit significantly a7 developers created applications optimized 64-bit processor anand lal shimpi anandtech praised phone a7 processor describing seriously impressive stated futureproof iphone ever launched much pains use word futureproof one people likes hold onto device iphone 5s good starting point scott lowe ign also spoke highly 64-bit processor substantial lead processing power htc one samsung galaxy s4 accounting graphics boost 32 38 cpu benchmarks debut apple 64-bit a7 processor took rival android smartphone makers surprise particularly qualcomm whose 64-bit system-on-chip released 2015 reviewers recommended iphone 5s iphone 5c released time 5c retained almost hardware discontinued iphone 5 iphone 5s featured substantially improved performance/features thanks new 64-bit a7 processor well extra storage space relatively small additional upfront cost iphone 5c us 650 versus us 550 march 2014 especially case ios 8 released iphone 5s iphone 5c moved mid low end iphone range respectively iphone 5s still 16 32 gb storage available iphone 5c make 8 gb storage 4.9gb available user installing ios 8 furthermore 5c polycarbonate exterior received mixed reception seen cost-cutting downgrade compared iphone 5 aluminum/glass case 5s retained latter design looked even premium due additional gold finish 2015–16 still significant number customers preferred 4-inch screen size iphone 5s remained second-most popular iphone iphone 6 ahead iphone 6s apple stated event sold 30 million 4-inch iphones 2015 even form factor succeeded flagship iphone redesigned larger display 4.7/5.5-inch iphone 6 6 plus back september 2014 furthermore 5/5s design regarded long golden child apple phone design benchmark phones general 5s gold finish adding premium touch 5 already well-regarded look succeeding 6 6s design less critically acclaimed felt little bit wrong though holding slick 650 bar soap iphone 5 described elegance rooted way aluminum glass work together felt streamlined yet substantial different iphone 6 feels substantial size alone plus unlike ubiquitous rounded corners 6 iphone 5 ’ really look like anything else market time however iphone 5/5s design suited scaling contrast iphone 6/6s could better accommodate growing consumer trend towards larger screen sizes indeed spawned 6/6s plus phablet models apple discontinued iphone 5s replaced iphone se outwardly appears almost identical 5s even se internal hardware upgraded significantly iphone 5s 5c sold nine million units first three days setting record first weekend smartphone sales 5s selling three times units 5c first day release 1 iphones us iphone 5ss 0.3 iphone 5cs. ref name= cnet ip5s/c sales 1 /ref gene munster piper jaffray reported line fifth avenue apple store contained 1,417 people release day compared 1,300 iphone 4 2010 549 iphone 3g 2008 respective release days first time apple launched two models simultaneously first-day release china also contributed record sales result launch day major in-stock shortages reported stores across countries iphone 5s initially went sale great many customers line outside apple stores worldwide left disappointed due severe shortages across 5s models gold model particular highly limited supply situation eased us days following launch countries reported receiving restocks commentators questioned apple handled initial release online pre-orders offered iphone 5s meaning large numbers people queuing outside physical stores line receiving unit us apple offered online reservation system customers could keep checking units available local apple stores order pickup online orders also short supply launch day shipping date across model sizes colors changing 7-10 working days october countries within hours online orders taken iphone 5s best selling phone sprint verizon t-mobile september 2013 united states outselling iphone 5c samsung galaxy s4 according consumer intelligence research partners iphone 5s outsold 5c two-to-one margin september release confirming apple ceo tim cook view high-end smartphone market reaching point market saturation commentators viewed 5c flop supply chain cuts signifying decline demand 5s viewed massive success apple admitted failed anticipate sales ratio leading overstocking 5c shortages 5s six months release iphone 5s march 25 2014 apple announced sales iphone brand exceeded 500 million units may 2014 despite market eight months iphone 5s reportedly outsold newly released samsung galaxy s5 40 7 million iphone 5s units versus 5 million galaxy s5 units galaxy s5 failure oust iphone 5s top selling spot major setback samsung mobile preceding samsung galaxy siii samsung galaxy s4 first quarter releases outsold iphone 4s iphone 5 respectively number technology writers including adrian kingsley-hughes zdnet kevin roose new york believed fingerprint scanning functionality iphone 5s could help spur adoption technology alternative passwords mainstream users especially bring device scenarios fingerprint-based authentication systems enjoyed wider usage enterprise environments however citing research biometrics engineer geppy parziale roose suggested cmos-based sensor could become inaccurate wear time unless apple designed sensor prevent occurring brent kennedy researcher united states computer emergency readiness team recommended users immediately rely technology citing uncertainty whether system could properly reject spoofed fingerprint following release iphone 5s german chaos computer club announced september 21 2013 bypassed apple new touch id fingerprint sensor using easy everyday means group explained security system defeated photographing fingerprint glass surface using captured image make latex model thumb pressed sensor gain access spokesman group stated hope finally puts rest illusions people fingerprint biometrics plain stupid use something ca n't change leave everywhere every day security token however 2013 39 american smartphone users used security measures protect smartphone others also tried chaos computer club method concluded easy process either time effort given user use high resolution photocopy complete fingerprint special chemicals expensive equipment spoofing process takes time achieve several problems experienced iphone 5s hardware release widely reported issue angle reported phone level sensor drifted several degrees caused gyroscope compass accelerometer become inaccurate reports suggested hardware-induced problem encountered problems crashing blue screen restarting power button making rattling noise phone shaken overheating microphone working touch id working itunes purchases issues since fixed software updates
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Operating systems
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automatic number-plate recognition automatic number-plate recognition anpr see also names technology uses optical character recognition images read vehicle registration plates create vehicle location data use existing closed-circuit television road-rule enforcement cameras cameras specifically designed task anpr used police forces around world law enforcement purposes including check vehicle registered licensed also used electronic toll collection pay-per-use roads method cataloguing movements traffic example highways agencies automatic number-plate recognition used store images captured cameras well text license plate configurable store photograph driver systems commonly use infrared lighting allow camera take picture time day night anpr technology must take account plate variations place place concerns systems centered privacy issues government tracking citizens movements misidentification high error rates increased government spending critics described form mass surveillance anpr sometimes known various terms anpr invented 1976 police scientific development branch britain prototype systems working 1979 contracts awarded produce industrial systems first emi electronics computer recognition systems crs wokingham uk early trial systems deployed a1 road dartford tunnel first arrest detection stolen car made 1981 however anpr become widely used new developments cheaper easier use software pioneered 1990s collection anpr data future use i.e solving then-unidentified crimes documented early 2000s first documented case anpr used help solve murder occurred november 2005 bradford uk anpr played vital role locating subsequently convicting killers sharon beshenivsky software aspect system runs standard home computer hardware linked applications databases first uses series image manipulation techniques detect normalize enhance image number plate optical character recognition ocr extract alphanumerics license plate anpr systems generally deployed one two basic approaches one allows entire process performed lane location real-time transmits images many lanes remote computer location performs ocr process later point time done lane site information captured plate alphanumeric date-time lane identification information required completed approximately 250 milliseconds information easily transmitted remote computer processing necessary stored lane later retrieval arrangement typically large numbers pcs used server farm handle high workloads found london congestion charge project often systems requirement forward images remote server require larger bandwidth transmission media anpr uses optical character recognition ocr images taken cameras dutch vehicle registration plates switched different style 2002 one changes made font introducing small gaps letters p r make distinct therefore legible systems license plate arrangements use variations font sizes positioning—anpr systems must able cope differences order truly effective complicated systems cope international variants though many programs individually tailored country cameras used existing road-rule enforcement closed-circuit television cameras well mobile units usually attached vehicles systems use infrared cameras take clearer image plates 1990s significant advances technology took automatic number-plate recognition anpr systems limited expensive hard set fixed based applications simple point shoot mobile ones made possible creation software ran cheaper pc based non-specialist hardware also longer needed given pre-defined angles direction size speed plates would passing camera field view scaled-down components cost-effective price points led record number deployments law enforcement agencies around world smaller cameras ability read license plates higher speeds along smaller durable processors fit trunks police vehicles allowed law enforcement officers patrol daily benefit license plate reading real time interdict immediately despite effectiveness noteworthy challenges related mobile anprs one biggest processor cameras must work fast enough accommodate relative speeds 100 mph 160 km/h likely scenario case oncoming traffic equipment must also efficient since power source vehicle battery equipment must small minimize space requires relative speed one issue affects camera ability actually read license plate algorithms must able compensate variables affect anpr ability produce accurate read time day weather angles cameras license plates system illumination wavelengths also direct impact resolution accuracy read conditions installing anpr cameras law enforcement vehicles requires careful consideration juxtaposition cameras license plates read using right number cameras positioning accurately optimal results prove challenging given various missions environments hand highway patrol requires forward-looking cameras span multiple lanes able read license plates high speeds city patrol needs shorter range lower focal length cameras capturing plates parked cars parking lots perpendicularly parked cars often require specialized camera short focal length technically advanced systems flexible configured number cameras ranging one four easily repositioned needed states rear-only license plates additional challenge since forward-looking camera ineffective oncoming traffic case one camera may turned backwards seven primary algorithms software requires identifying license plate complexity subsections program determines accuracy system third phase normalization systems use edge detection techniques increase picture difference letters plate backing median filter may also used reduce visual noise image number possible difficulties software must able cope include problems corrected within software primarily left hardware side system work solutions difficulties increasing height camera may avoid problems objects vehicles obscuring plate introduces increases problems adjusting increased skew plate cars tow bars may obscure one two characters license plate bikes bike racks also obscure number plate though countries jurisdictions victoria australia bike plates supposed fitted small-scale systems allow errors license plate used giving specific vehicles access barricaded area decision may made acceptable error rate one character likelihood unauthorized car similar license plate seen quite small however level inaccuracy would acceptable applications anpr system front end anpr system imaging hardware captures image license plates initial image capture forms critically important part anpr system accordance garbage garbage principle computing often determine overall performance license plate capture typically performed specialized cameras designed specifically task although new software techniques implemented support ip-based surveillance camera increase utility anpr perimeter security applications factors pose difficulty license plate imaging cameras include speed vehicles recorded varying level ambient light headlight glare harsh environmental conditions dedicated license plate capture cameras incorporate infrared illumination order solve problems lighting plate reflectivity many countries use license plates retroreflective returns light back source thus improves contrast image countries characters plate reflective giving high level contrast reflective background lighting conditions camera makes use active infrared imaging normal colour filter lens infrared illuminator next benefits greatly infrared waves reflected back plate possible dedicated anpr cameras however cameras used purposes must rely heavily software capabilities full-colour image required well use anpr-retrieved details necessary one infrared-enabled camera one normal colour camera working together avoid blurring ideal shutter speed dedicated camera set 1/1000 second also important camera uses global shutter opposed rolling shutter assure taken images distortion-free car moving slower shutter speeds could result image blurred read using ocr software especially camera much higher vehicle slow-moving traffic camera lower level vehicle angle approaching camera shutter speed need fast shutter speeds 1/500 second cope traffic moving 40 mph 64 km/h 1/250 second 5 mph 8 km/h license plate capture cameras produce usable images vehicles traveling maximize chances effective license plate capture installers carefully consider positioning camera relative target capture area exceeding threshold angles incidence camera lens license plate greatly reduce probability obtaining usable images due distortion manufacturers developed tools help eliminate errors physical installation license plate capture cameras several state police forces department justice victoria use fixed mobile anpr systems new south wales police force highway patrol first trial use fixed anpr camera system australia 2005 2009 began roll-out mobile anpr system known officially manpr three infrared cameras fitted highway patrol fleet system identifies unregistered stolen vehicles well disqualified suspended drivers well 'persons interest persons outstanding warrants city mechelen uses anpr system since september 2011 scan cars crossing city limits inbound outbound cars listed 'black lists insurance stolen etc generate alarm dispatching room intercepted patrol early 2012 1 million cars per week automatically checked way police service ontario uses automatic licence-plate recognition software nab drivers behind wheels vehicles ontario number plates technique tested danish police permanent use since mid 2016 180 gantries major roads built throughout country together 250 fixed cameras enable levy eco tax lorries 3.5 tonnes system currently opposed whilst may collecting data vehicles passing cameras eco tax charged 11 march 2008 federal constitutional court germany ruled areas laws permitting use automated number plate recognition systems germany violated right privacy specifically court found retention sort information i.e. number plate data pre-destined use e.g. use tracking suspected terrorists enforcement speeding laws violation german law systems provided jenoptik robot gmbh called trafficapture 2012 state consortium formed among hungarian ministry interior national police headquarters central commission public administration electronic services aim install operate unified intelligent transportation system nationwide coverage end 2015 within system 160 portable traffic enforcement data-gathering units 365 permanent gantry installations brought online anpr speed detection imaging statistical capabilities since data points connected centrally located member consortium able separately utilize range administrative enforcement activities remote vehicle registration insurance verification speed lane traffic light enforcement wanted stolen vehicle interception among others several hungarian auxiliary police units also use system called matrix police cooperation police consists portable computer equipped web camera scans stolen car database using automatic number-plate recognition system installed dashboard selected patrol vehicles pda-based hand-held versions also exist mainly used control license plate parking cars auxiliary police authority order moving vehicles stop stolen car found formal police informed vehicle registration plates saudi arabia use white background several vehicle types may different background united states diplomatic plates letters 'usd arabic reads 'dsu read right left direction arabic script 17 arabic letters used registration plates challenge plates recognition saudi arabia size digits plates use eastern arabic numerals 'western arabic equivalents research source code available apnr arabic digits technique tested swedish police authority nine different locations sweden several cities tested—and put service—the kgys kent guvenlik yonetim sistemi city security administration system i.e. capital ankara debuted kgys- consists registration plate number recognition system main arteries city exits system used two cameras per lane one plate recognition one speed detection system widened network registration number cameras together enforcing average speed preset distances arteries limit photo evidence date-time details posted registration address speed violation detected 2012 fine exceeding speed limit 30 approximately us 175 project system integration « olli technology » ministry internal affairs ukraine department state traffic inspection sti experiments introduction modern technical complex capable locate stolen cars drivers deprived driving licenses problem cars real time ukrainian complex video control working principle video fixing car recognition license plates check data base home office states purpose automatic number-plate recognition united kingdom help detect deter disrupt criminality including tackling organised crime groups terrorists vehicle movements recorded network nearly 8000 cameras capturing 25 30 million anpr ‘ read ’ records daily records stored two years national anpr data center accessed analysed used evidence part investigations uk law enforcement agencies 2012 uk parliament enacted protection freedoms act includes several provisions related controlling restricting collection storage retention use information individuals act home office published code practice 2013 use surveillance cameras including anpr government law enforcement agencies aim code help ensure use characterised surveillance consent consent part community must informed consent assumed system operator surveillance consent regarded analogous policing consent addition set standards introduced 2014 data infrastructure data access management united states anpr systems commonly referred alpr automatic license plate reader/recognition technology due differences language i.e. number plates referred license plates american english mobile anpr use widespread among us law enforcement agencies city county state federal level according 2012 report police executive research forum approximately 71 us police departments use form anpr mobile anpr becoming significant component municipal predictive policing strategies intelligence gathering well recovery stolen vehicles identification wanted felons revenue collection individuals delinquent city state taxes fines monitoring amber alerts widespread implementation technology many u.s. states issue misdemeanor citations 500 license plate identified expired incorrect vehicle successfully recognized plates may matched databases including wanted person protection order missing person gang member known suspected terrorist supervised release immigration violator national sex offender lists addition real-time processing license plate numbers anpr systems us collect indefinitely store data license plate capture images dates times gps coordinates stockpiled help place suspect scene aid witness identification pattern recognition tracking individuals department homeland security proposed federal database combine monitoring systems cancelled privacy complaints 1998 washington d.c. police lieutenant pleaded guilty extortion blackmailing owners vehicles parked near gay bar 2015 los angeles police department proposed sending letters home addresses vehicles enter areas high prostitution early private sector mobile anpr applications vehicle repossession recovery although application anpr private companies collect information privately owned vehicles collected private property example driveways become issue sensitivity public debate anpr uses include parking enforcement revenue collection individuals delinquent city state taxes fines technology often featured reality tv show parking wars featured e network show tow truck drivers booting teams use anpr find delinquent vehicles high amounts unpaid parking fines laws vary among states regarding collection retention license plate information 14 states limits long data may retained lowest new hampshire 3 minutes colorado 3 years supreme court virginia ruled 2018 data collected alprs constitute personal information anpr used speed limit enforcement australia austria belgium dubai uae france italy netherlands spain south africa uk kuwait works tracking vehicles travel time two fixed points calculating average speed cameras claimed advantage traditional speed cameras maintaining steady legal speeds extended distances rather encouraging heavy braking approach specific camera locations subsequent acceleration back illegal speeds developed monitoring system named covering 2500 km 2012 tutor system also able intercept cars changing lanes average speed cameras trajectcontrole place netherlands since 2002 july 2009 12 cameras operational mostly west country along a12 divided several “ sections ” allow cars leaving entering motorway first experimental system tested short stretch a2 1997 deemed big success police reducing overspeeding 0.66 compared 5 6 regular speed cameras used location first permanent average speed cameras installed a13 2002 shortly speed limit reduced 80 km/h limit noise air pollution area 2007 average speed cameras resulted 1.7 million fines overspeeding total 9.7 millions according dutch attorney general average number violation speed limits motorway sections equipped average speed cameras 1 2 compared 10 15 elsewhere one notable stretches average speed cameras uk found a77 road scotland monitored kilmarnock girvan 2006 confirmed speeding tickets could potentially avoided 'specs cameras changing lanes rac foundation feared people may play russian roulette changing one lane another lessen odds caught however 2007 system upgraded multi-lane use 2008 manufacturer described myth “ categorically untrue ” exists evidence implementation systems specs considerable effect volume drivers travelling excessive speeds stretch road mentioned a77 glasgow ayr noted huge drop speeding violations since introduction specs system recent innovations contributed adoption anpr perimeter security access control applications government facilities within us homeland security efforts protect alleged acts terrorism resulted adoption anpr sensitive facilities embassies schools airports maritime ports military federal buildings law enforcement government facilities transportation centers anpr marketed able implemented networks ip based surveillance cameras perform double duty alongside facial recognition object tracking recording systems purpose monitoring suspicious anomalous behavior improving access control matching watch lists anpr systems commonly installed points significant sensitivity ingress egress major us agencies department homeland security department justice department transportation department defense purchased anpr perimeter security applications large networks anpr systems installed cities boston london new york city provide citywide protection acts terrorism provide support public gatherings public spaces center evidence-based crime policy george mason university identifies following randomized controlled trials automatic number-plate recognition technology rigorous addition government facilities many private sector industries facility security concerns beginning implement anpr solutions examples include casinos hospitals museums parking facilities resorts us private facilities typically access government police watch lists may develop match databases customers vips critical personnel banned person lists addition providing perimeter security private anpr service applications valet recognized customer vip recognition logistics key personnel tracking sales advertising parking management logistics vendor support vehicle tracking many cities districts developed traffic control systems help monitor movement flow vehicles around road network typically involved looking historical data estimates observations statistics cctv cameras used help traffic control centres giving live data allowing traffic management decisions made real-time using anpr footage possible monitor travel individual vehicles automatically providing information speed flow various routes details highlight problem areas occur help centre make informed incident management decisions counties united kingdom worked siemens traffic develop traffic monitoring systems control centres public projects hampshire county council romanse provide interactive real-time website showing details traffic city site shows information car parks ongoing road works special events footage taken cctv cameras anpr systems used provide average point-to-point journey times along particular routes displayed variable-message sign vms giving drivers ability plan route romanse also allows travellers see current situation using mobile device internet connection wap gprs 3g allowing view mobile device cctv images within hampshire road network uk company trafficmaster used anpr since 1998 estimate average traffic speeds non-motorway roads without results skewed local fluctuations caused traffic lights similar company operates network 4000 anpr cameras claims four central digits identified numberplate data retained ieee intelligent transportation systems society published papers plate number recognition technologies applications ontario 407 etr highway uses combination anpr radio transponders toll vehicles entering exiting road radio antennas located junction detect transponders logging unique identity vehicle much way anpr system without anpr second system would possible monitor traffic drivers opt rent transponder c 2.55 per month charged video toll charge c 3.60 using road heavy vehicles gross weight 5,000 kg required use one using either system users highway notified usage charges post numerous electronic toll collection networks use combination radio frequency identification anpr include portuguese roads old highways toll stations drivers pay cards also lanes electronic collection systems however new highways option electronic toll collection system electronic toll collection system comprises three different structures smart tag installed vehicle car quickly identified owner bank account automatically deducted process realized speed 250 km per hour car smart tag driver required go pay station pay tolls 3rd 5th day surplus charge fails owner sent letter home heavy fine paid increases five-fold car inserted police database vehicle impounding system also used limited access areas main cities allow entry pre-registered residents planned implemented roads city entrance toll collection/access restriction efficacy system considered high almost impossible driver complain london congestion charge example system charges motorists entering payment area transport london tfl uses anpr systems charges motorists daily fee £11.50 enter leave move around within congestion charge zone 7 a.m. 6:00 p.m. monday friday reduced fee £10.50 paid vehicle owners sign automatic deduction scheme fines traveling within zone without paying charge £65 per infraction paid deadline doubling £130 per infraction thereafter currently 1,500 cameras use automatic number plate recognition anpr technology also number mobile camera units may deployed anywhere zone estimated around 98 vehicles moving within zone caught camera video streams transmitted data centre located central london anpr software deduces registration plate vehicle second data centre provides backup location image data front back number plates captured vehicles going – gives four chances capture number plates vehicle entering exiting zone list compared list cars whose owners/operators paid enter zone – paid fined registered owner vehicle looked database provided dvla johannesburg south africa anpr used etoll fee collection owners cars driving inner city must pay charge.the number tolls passed depends distance travelled particular freeway freeways anpr n12 n3 n1 etc stockholm sweden anpr used stockholm congestion tax owners cars driving inner city must pay charge depending time day 2013 also gothenburg congestion tax also includes vehicles passing city main highways several uk companies agencies use anpr systems include vehicle operator services agency vosa driver vehicle licensing agency dvla transport london anpr systems may also used for/by vehicle owners used variety techniques attempt evade anpr systems road-rule enforcement cameras general one method increases reflective properties lettering makes likely system unable locate plate produce high enough level contrast able read typically done using plate cover spray though claims regarding effectiveness latter disputed jurisdictions covers illegal covered existing laws countries law disallow use sprays users attempted smear license plate dirt utilize covers mask plate novelty frames around texas license plates made illegal texas 1 september 2003 texas senate bill 439 caused problems anpr devices law made class c misdemeanor punishable fine us 200 class b punishable fine us 2,000 180 days jail proven owner deliberately obscure plates law later clarified 2007 allow novelty frames anpr system read plate flag image attention human operators looking see able identify alphanumerics order avoid surveillance penalty charges upsurge car cloning usually achieved copying registration plates another car similar model age difficult detect especially cloners may change registration plates travel behavior hinder investigations 2013 researchers sunflex zone ltd created privacy license plate frame uses near infrared light make license plate unreadable license plate recognition systems introduction anpr systems led fears misidentification furthering 1984 -style surveillance united states gregg easterbrook oppose call machines issue speeding tickets red-light tickets beginning slippery slope towards automated justice system similar criticisms raised countries easterbrook also argues technology employed maximize revenue state rather promote safety electronic surveillance system produces tickets us often excess 100 virtually impossible citizen contest court without help attorney revenues generated machines shared generously private corporation builds operates creating strong incentive tweak system generate many tickets possible older systems notably unreliable uk known lead charges made incorrectly vehicle owner pay £10 order issued proof offense improvements technology drastically decreased error rates false accusations still frequent enough problem perhaps best known incident involving abuse anpr database north america case edmonton sun reporter kerry diotte 2004 diotte wrote article critical edmonton police use traffic cameras revenue enhancement retaliation added anpr database high-risk drivers attempt monitor habits create opportunity arrest police chief several officers fired result office privacy commissioner canada expressed public concern growing police use technology spy motorists concerns include storage information could used identify people store details driving habits daily life contravening data protection act along similar legislation see personally identifiable information laws uk strict system uses cctv footage identify individuals also concern safety data mined following discovery police surveillance records lost gutter also case uk saying use anpr cameras unlawful regulation investigatory powers act 2000 breach exists say fact anpr used monitor activities law-abiding citizens treats everyone like suspected criminals intended surveyed act police known refer system anpr 24/7 traffic movement database diversion intended purpose identifying vehicles involved criminal activities opposing viewpoint plates cloned 'read innocent motorist vehicle allow elimination vehicle investigation visual examination images stored likewise stolen vehicles read anpr systems time theft report police assisting investigation associated press reported august 2011 new york police department cars license plate tracking equipment purchased federal hidta high intensity drug trafficking area funds used spy muslims mosques track license plate numbers worshipers police unmarked cars outfitted electronic license plate readers would drive street automatically catalog plates everyone parked near mosque amassing covert database would distributed among officers used profile muslims public 2013 american civil liberties union aclu released 26,000 pages data anpr systems obtained local state federal agencies freedom information laws documents paint startling picture technology deployed rules becoming tool mass routine location tracking surveillance wrote aclu aclu reported many locations devices used store location information vehicles suspected particular offense private companies also using license plate readers sharing information collect police little oversight privacy protections lack regulation means policies governing long location data kept vary widely aclu said 2012 aclu filed suit department homeland security funds many local state anpr programs grants agency failed provide access records aclu requested freedom information act programs mid-august 2015 boston discovered license plate records million people online unprotected many anpr systems claim accuracy trained match plates single jurisdiction region fail trying recognize plates jurisdictions due variations format font color layout plate features jurisdictions offer vanity affinity plates particularly us create many variations within single jurisdiction time time us states make significant changes license plate protocol affect ocr accuracy may add character add new license plate design alpr systems must adapt changes quickly order effective another challenge alpr systems states license plate protocol example one state uses standard three letters followed four numbers time alpr systems alarms user ’ responsibility make sure plate caused alarm matches state associated license plate listed in-car computer maximum effectiveness anpr system able recognize plates jurisdiction jurisdiction associated many variables make tasks difficult currently least one us anpr provider platesmart claims system independently reviewed able accurately recognize us state jurisdiction license plates one european anpr provider claims system differentiate eu plate jurisdictions anpr software vendors publish accuracy results based image benchmarks results may vary depending images vendor chosen include test 2017 sighthound reported 93.6 accuracy private image benchmark 2017 openalpr reported accuracy rates commercial software range 95-98 public image benchmark april 2018 research brazil ’ federal university paraná federal university minas gerais compared systems reported median recognition rate 93.53 stated significant improvement 81.8 rate obtained previous works
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Computer security
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font bomb font bomb javascript bookmarklet blow web pages script loaded clicking web page starts countdown countdown reaches zero uses cascading style sheets scatter nearby text across page script wraps affected letters tag moved individually
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Programming language topics
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android tactical assault kit android tactical assault kit atak android smartphone geospatial infrastructure military situational awareness app built using nasa worldwind initially created 2010 air force research laboratory based nasa worldwind mobile codebase development deployment grew slowly rapidly since 2016 2013 officials draper laboratory said system would compatible android mobile operating systems could used navigation spatial awareness controlling drones atak plugin architecture allows developers add functionality atak polaris integrated ground guidance software atak plugin allow off-road routing mounted dismounted soldiers accounting terrain weather enemy activity equipment load connections programs atak began august 2010 originally based nasa worldwind mobile goal demonstrate robust information sharing mobile format oct 14 2014 u.s. army geospatial center recommended afrl android tactical assault kit atak world-leader esri commercial joint mapping tool kit cjmtk nasa world wind army globe engine age map engine driving nett warrior end user device atak selected due similar capabilities cjmtk similar risk less one-third total cost read full public released report nett warrior map engine trade study september 2015 darpa reported atak used successful demonstration persistent close air support program use thousands users according january 2016 article national defense magazine atak already fielded afsoc units atak excellent suitability coordinating people geography atak made available federal government users contractors need coordination atak also made available government researchers wish experiment geospatial collaboration without building systems versions addition android version also windows version wintak iphone version development itak wintak application developed microsoft windows operating system uses maps allow precise targeting intelligence surrounding land formations navigation generalized situational awareness developed conjunction atak provide similar functionality windows platform commercial licensing january 2015 afrl began licensing atak techlink u. s. companies commercial use support state/local government uses well civilian uses november 2015 twenty-five companies licensed atak commercial uses techlink licensing site
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Operating systems
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bsd authentication bsd authentication otherwise known bsd auth authentication framework software api employed openbsd accompanying software openssh originated bsd/os although specification implementation donated freebsd project bsdi openbsd chose adopt framework release 2.9 pluggable authentication modules pam serves similar purpose operating systems linux freebsd netbsd bsd auth performs authentication executing scripts programs separate processes one requiring authentication prevents child authentication process interfering parent except narrowly defined inter-process communication api technique inspired principle least privilege known privilege separation behaviour significant security benefits notably improved fail-safeness software robustness malicious accidental software bugs pam uses alternative system modules providing authentication dynamically linked requesting process method considered flexible bsd auth provide privilege separation without additional configuration
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Operating systems
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intel 8255 intel 8255 i8255 programmable peripheral interface ppi chip developed manufactured intel first half 1970s intel 8080 microprocessor 8255 provides 24 parallel input/output lines variety programmable operating modes 8255 member mcs-85 family chips designed intel use 8085 8086 microprocessors descendants first available 40-pin dip later 44-pin plcc packages found wide applicability digital processing systems later cloned manufacturers 82c55 cmos version higher speed lower current consumption functionality 8255 mostly embedded larger vlsi processing chips sub-function cmos version 8255 still made renesas mostly used expand i/o microcontrollers 8255 similar function mos technology 6522 versatile interface adapter 6526 mos technology cia complex interface adapter developed 6502 family chips originally available 40-pin dil package 8255 provides 24 usable i/o pins whereas mos chips provide 16 i/o pins plus 4 control pins however mos chips contain functions two programmable reload timers simple i/o shift register function furthermore mos devices allow direction input output i/o pins individually programmed 8255 i/o pins four programmable direction bits one port 7:0 one port b 7:0 one port c 3:0 one port c 7:4 comparable microprocessor i/o chips 2655 programmable peripheral interface signetics 2650 family motorola 6820 pia peripheral interface adapter motorola 6800 family western design center wdc 65c21 8255 widely used many microcomputer/microcontroller systems home computers sv-328 msx models 8255 used original ibm-pc pc/xt pc/jr clones along numerous homebuilt computers n8vem 8255 gives cpu digital system access programmable parallel i/o 8255 24 input/output pins divided three 8-bit ports b c port port b used 8-bit input/output ports port c used 8-bit input/output port two 4-bit input/output ports produce handshake signals ports b three ports grouped follows eight data lines d0–d7 available 8-bit data buffer read/write data ports control register status formula_1rd pin 5 formula_1wr pin 36 active-low signals read write operations respectively address lines allow access data register port control register listed control signal chip select formula_1cs pin 6 used enable 8255 chip active-low signal i.e. formula_1cs 0 8255 enabled reset input pin 35 connected reset line system like 8085 8086 etc. system reset ports initialized input lines done prevent 8255 and/or peripheral connected destroyed due mismatch ports example consider input device connected 8255 port previous operation port initialized output port 8255 reset using current configuration possibility damage either input device connected 8255 since 8255 device connected sending data control register control logic command word register 8-bit register used select modes operation input/output designation ports two basic operational modes 8255 two modes selected basis value present bit control word register 1 8255 operates i/o mode 0 operates bsr mode bit set/reset bsr mode available port c line port c pc pc set reset writing suitable value control word register bsr mode i/o mode independent selection bsr mode affect operation ports i/o mode selection port c pin determined follows example needed pc set control word thus per values 0b hex loaded control word register cwr mode selected bit control word register 1 three i/o modes example port b upper port c initialized input ports lower port c port output ports mode 0 hence desired operation control word register loaded 10001010 8a hex mode ports used simple i/o operations without handshaking signals port port b provide simple i/o operation two halves port c either used together additional 8-bit port used individual 4-bit ports since two halves port c independent may used one-half initialized input port half initialized output port input/output features mode 0 follows 'latched means bits put storage register array flip-flops holds output constant even inputs change latched 8255 outputs latched hold last data written required data stays bus one cycle without latching outputs would become invalid soon write cycle finishes inputs latched cpu read current values store data cpu register memory needs referenced later time input changes port read result may indeterminate wish use port port b handshake strobed input output operation initialise port mode 1 port port b initilalised operate different modes i.e. e.g. port operate mode 0 port b mode 1 pins port c function handshake lines port b mode irrespective whether acting input port output port pc0 pc1 pc2 pins function handshake lines port initialised mode 1 input port pc3 pc4 pc5 function handshake signals pins pc6 pc7 available use input/output lines mode 1 supports handshaking following features input handshaking signals output handshaking signals port initialized mode port used bidirectional handshake data transfer means data input output eight lines pa0 pa7 pins pc3 pc7 used handshake lines port remaining pins port c pc0 pc2 used input/output lines group b initialized mode 0 handshaking port b group b initialized mode 1 mode 8255 may used extend system bus slave microprocessor transfer data bytes floppy disk controller acknowledgement handshaking signals provided maintain proper data flow synchronisation data transmitter receiver
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Computer architecture
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lxle linux lxle linux distribution based upon recent ubuntu/lubuntu lts release using lxde desktop environment lxle lightweight distro focus visual aesthetics works well old new hardware january 2014 review full circle magazine gabriele tettamanzi noted lxle minor localization issues otherwise described nice light fast desktop rich software stable jesse smith reviewed lxle 12.04.3 distrowatch weekly jesse smith also reviewed lxde 14.04
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Operating systems
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clio software company clio legal technology company headquartered burnaby british columbia clio offers law firms cloud-based software handles various law practice management tasks including client intake contact management calendaring document management timekeeping billing trust accounting clio established 2007 jack newton rian gauvreau felt software commonly use law firms time expensive difficult use company launched software 2008 first cloud-based practice management software developed law firms 2012 clio series b raised 6 million time investment second-largest ever made british columbia-based internet company company also made first version application programming interface available 2012 september 2013 clio released mobile application provides access company software ios devices release occurred company first annual cloud conference event gained prominence legal technology industry 2014 clio received 20 million series c funding also announced android version mobile application major product update october 2016 clio published first legal trends report annual publication references aggregated metrics company user base analyze trends benchmarks law firm operations october 5 2018 clio announced acquired client intake software provider lexicata lexicata product would converted new product called clio grow time clio also supported 120 integrations legal software applications
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Distributed computing architecture
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guidestar guidestar usa inc. information service specializing reporting u.s. nonprofit companies 2016 database provided information 2.5 million organizations guidestar one first central sources information u.s. nonprofits world largest source information nonprofit organizations guidestar founded williamsburg virginia september 1994 received tax-exempt status 1996 year company began posting nonprofit organizations financial reports world wide web guidestar also serves verify recipient organization established donated funds go donor intended individuals looking give wake disasters 2013 guidestar announced major changes guidestar exchange program allows nonprofits supplement public information available irs guidestar nonprofit profiles implemented three seals based information nonprofit provides profile bronze silver gold 2016 new seal allowed nonprofits share progress results mission guidestar platinum introduced 2019 guidestar merged foundation center form new organization candid charity watch investigator compared charity navigator charity watch better business bureau combined federal campaign great nonprofits investigator praised guidestar offering information rather making judgments guidestar placed notice pages charities listed southern poverty law center splc hate list one groups sued guidestar defamation charities echoed criticism guidestar use splc list
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Databases
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loadhigh computing abbreviated internal dos command command.com used load program upper memory area uma instead conventional memory command introduced ms-dos 5.0 pc dos 5.0 1991 copying built-in command earlier introduced dr dos 5.0 1990 dr dos 6.0 added support naming variant well 1991 due design ibm pc dos suffered known 640 kib barrier size memory area known conventional memory fixed independent amount system memory actually installed various schemes developed support extra memory see also ems xms dos extenders conventional memory still issue due compatibility issues scarce resource many applications demanded large part basic memory fragment runtime therefore often necessary move high tsr programs like mouse driver disk caching driver like smartdrv prior running memory-hungry application achieved using called program name parameter load tsrs high within config.sys installhigh directive must used instead command equivalent device drivers devicehigh usable within config.sys also supported since dr dos 6.0 dr dos 5.0 higher also support hiinstall hidevice respectively modern operating systems run protected mode support unsegmented flat memory model 640 kb constraint methods freeing conventional memory largely become obsolete
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Computer architecture
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internet cache protocol internet cache protocol icp udp-based protocol used coordinating web caches purpose find appropriate location retrieve requested object situation multiple caches use single site icp use caches efficiently possible minimize number remote requests originating server hierarchically queried cache either parent sibling parents usually sit closer internet connection child child cache find object query usually sent parent cache fetch cache pass request siblings caches equal hierarchical status whose purpose distribute load amongst siblings request comes one cache cluster siblings icp used query siblings object requested sibling object usually transferred instead queried original server often called near miss — object found cache “ miss ” loaded nearby cache instead remote server icp protocol designed lightweight order minimize round-trip time caches intended unreliable quick connections approach reduce numbers server retrievals also prevent storage multiple copies instance data leads potential drawback increased intercache communication slow system icp protocol described rfc 2186 application hierarchical web caching rfc 2187 web proxies support icp include htcp designed successor icp attempts handle various problems found icp deployments icp message consists two sections header header length fixed 20 octets five 32-bit words data data variable length limited maximum icp message size including header 16,384 octets icp header consists 8 fields 2 optional fields fifth sixth field optional pink background table appropriately named “ options ” “ option data ”
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Internet protocols
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maccharlie maccharlie hardware add-on apple macintosh made dayna communications name refers ibm pc advertising campaign time featuring charlie chaplin little tramp character allowed users run dos software ibm pc clipping unit onto chassis 128k macintosh well keyboard extender provide function keys numeric keypad absent apple original keyboard clip-on unit sat side mac like contemporary amiga sidecar contained essentially complete ibm pc compatible 8088 processor 256k ram expandable 640k single 5.25 floppy drive stored 360k second floppy drive could added running dos software users could still access macintosh menu bar desk accessories maccharlie used mac terminal performing dos processing sending video data relatively slow serial link mac display slowness coupled declining prices real ibm pc compatibles contributed short market life maccharlie
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Computer architecture
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outbound laptop outbound laptop apple macintosh-compatible laptop computer powered 15-mhz motorola 68000 processor later versions increased clock speed 20 mhz outbound systems inc. located boulder colorado due kangaroo logo many believed australian company outbound laptop introduced 1989 significantly lighter 4 kg easier carry apple macintosh portable released around time due apple refusal license macintosh toolbox read-only memory rom outbound users install mac rom make computer work rom typically removed older mac process would render donor mac unusable even additional cost typical price us 4,000 compared favorably mac portable outbound featured built-in pointing device located keyboard named trackbar earlier models referring trademark isopoint cylinder scrolled slid left right ran standard camcorder batteries rather expensive custom batteries commonly found portable computers around time outbound laptop succeeded outbound notebook 1991 notebook ran style lead-acid camcorder batteries earlier laptop 9.7 passive-matrix monochrome lcd display used 2.5 ide hard drive unusual time apple n't start using ide drives powerbooks powerbook 150 1994 notebook internal microphone speaker headphone jack two serial ports adb port scsi port notebook scsi port unique supported outbound outrigger full-page external monochrome monitor attached via scsi port notebook cpu ram mac rom optional 68882 fpu mounted removable daughtercard permitted easy ram installation optional upgrades daughtercard could simply swapped another one faster cpu fpu inserted available socket daughtercard four 30-pin simm sockets due notebook design 4mb ram could addressed mac system software even system 7 additional ram would appear silicon disk outbound specific ram disk apple introduction powerbook 1991 led demise mac-compatible laptop aftermarket probably significant increased competition fact outbound using roms licensing agreement apple apple refused license use subsequent proprietary roms outbound company ability manufacture laptops ended 68000 processors required roms access became difficult obtain short time outbound went business small group former employees set company perfit handle service warranty issues perfit ceased operations 1994
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Computer architecture
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axway software axway software publicly held information technology company provides software tools enterprise software enterprise application integration business activity monitoring business analytics mobile application development web api management listed compartment b companies market capitalizations €150 million €1 billion paris euronext since june 2011 axway software incorporated 28 december 2000 software infrastructure division french services company sopra spun-out subsidiary sopra subsequently merged another french services company steria form sopra steria 2014 sopra used axway vehicle expansion enterprise application integration market subsequently number acquisitions made axway swedish company viewlocity acquired early 2002 christophe fabre became ceo axway 2005 remained position 2015 axway acquired us company cyclone commerce january 2006 much executive management axway relocated phoenix arizona february 2007 axway acquired atos b2b software business germany us company tumbleweed communications acquired june 2008 june 2011 axway spun sopra group listed paris euronext november 2012 irish company vordel api management vendor acquired brazilian company sci soluções acquired september 2013 january 2014 axway acquired assets information gateway australia axway acquired french company systar developer business activity monitoring software june 2014 january 2016 axway acquired us company appcelerator creator appcelerator titanium open-source framework multiplatform native mobile app development axway acquired us company syncplicity developer file share synchronization service february 2017 2017 sopra steria holds 33.52 axway sopra gmt holding company sopra steria axway holds 21.65 may 2016 sopra steria acquired 8.62 stake axway formerly held société générale axway component cac small 2016 axway 11,000 customers 100 countries since going public 2011 annual revenues grown €217.2 million 2011 €301.1 million 2016 profits grown €35.3 million 2011 €50.8 million 2016 axway headquartered phoenix arizona puteaux paris company development centers france annecy also site axway registered office lyon paris romania bucharest bulgaria sofia united states scottsdale arizona santa clara california also various support centers including one noida india acquisition sci 2013 lead establishment axway south america regional headquarters são paulo brazil 2017 axway main product amplify platform amplify acts data integration platform number formerly independent legacy products including appcelerator titanium provides uniform user interface various components amplify allows creation api-based services supports embedded real-time predictive analytics provides dashboards summarize data information provided different components sources axway also provides marketplace third party products services related apis titanium-built mobile apps
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Distributed computing architecture
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ututo ututo linux distribution consisting entirely free software distribution named variety gecko found northern argentina ututo first fully free linux-based system recognized gnu project founder gnu project richard stallman formerly endorsed distribution nearly exclusively used personal computer switched gnewsense later trisquel ututo first released 2000 diego saravia national university salta argentina one first live cd distributions world first linux distribution argentina ututo carried simusol system simulate solar energy projects ututo simple install need configuration automatically detected hardware machine asked move mouse time distribution worked way 2002 ututo-r created offered possibility operating like software router version created marcos zapata used buenos aires public schools 2004 ututo-e project born swiftly becoming important derivative ututo project started daniel olivera 2006 ututo declared national interest argentine chamber deputies ututo xs current stable version ututo ututo xs compiled using gentoo linux ebuilds emerge software documentation spanish emergence xs series many new features added including faster system installer ututo used different hardware projects ifreetablet pablo manuel rizzo designed package management system ututo-get modelled debian apt however gentoo-based distros ututo compatible portage ututo different binaries optimized different intel amd processors releases since 2012 distribution considered dormant ututo ul ubuntu-libre current developed version ututo ututo ul utilize ubuntu distro base nonfree software removed usual ututo project linux-libre kernel 2017 original idea distributing simusol system simulate solar energy projects returned heart project tux machines reviewed utoto 2006
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Computer architecture
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paedophile unit paedophile unit branch metropolitan police service child abuse investigation command based scotland yard london england operates manufacture distribution child pornography online child grooming predatory paedophiles online organised crime associated unit subject series bbc television programmes concerning hunt britain paedophiles subject record 23,000 calls bbc audience line responsible final break-up advocacy group called paedophile information exchange paedophile unit works conjunction hi-tech crime unit examine computers used suspected offenders including computers used public areas via remote connections use technology identify arrest suspects referred proactive policing paedophile unit began life early 1960s obscene publications public morals branch although name shortened 1990 obscene publications branch opb common name however even among police hierarchy always obscene publications squad ops often colloquially known porn squad dirty squad set part clubs vice unit following passing obscene publications act 1959 originally operated pornography restrictions adult hardcore pornography began effectively rendered unenforceable advent internet unit restructured 1995 focus solely child sex offences renamed paedophile child pornography unit responsibility future investigation adult pornography transferred directly 1 area clubs vice unit charing cross police station originally part criminal investigation department transferred uniformed branch november 1972 revealed officers taking bribes pornography industry several later jailed corruption offences although staffed uniformed officers although continued usually operate plain clothes detectives initially continued part serious crime squad c1 department cid although 1990 part territorial operations to13 1993 returned cid control allowing officers use detective prefix front ranks became part so1 4 international organised crime branch specialist operations reorganisation 1995 became part organised crime group officer charge chief inspector 1972 superintendent thereafter assisted inspector number sergeants constables 1993 sixteen police officers ten civilian staff responsible administration storing evidence along officers viewing assessing material 1995 newsreader julia somerville partner arrested unit took nude pictures somerville daughter bath development boots later released without charge crime committed
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Computer security
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nvidia gameworks nvidia gameworks middleware software suite developed nvidia visual fx physx optix sdks provide wide range enhancements pre-optimised nvidia gpus gameworks distributed form compiled dlls rather traditional source code competing solution development amd gpuopen announced free open-source software mit license march 2016 nvidia made source code gameworks available github nvidia gameworks consists several main components addition suite contains sample code directx opengl developers well tools debugging profiling optimization android development gameworks criticized proprietary closed nature competing gpu manufacturers amd intel unable properly optimize nvidia libraries hardware due developers allowed see code necessary properly optimize products amd chief gaming scientist richard huddy claimed developers use gameworks contractually forbidden work amd also claims gameworks adds specific performance-crippling effects older nvidia cards unnecessary tessellation marginally affects recent cards 2014 amd considering making open source gameworks competitor released gpuopen december 2015
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Distributed computing architecture
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software shelf international software shelf international multinational corporation headquartered clearwater florida develops manufactures licenses supports range software programming services predominantly related business institutional printing print management data recovery software shelf established 1994 silicon valley redwood city california reseller distributor enterprise tools north american business markets company began develop line software programs utilities including print manager plus focused environmentally conscious sustainable business software solutions company developed first all-software solution reduce escalating ink paper hardware waste business academic institutional environment company currently maintains offices west sussex england menlo park california
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Distributed computing architecture
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need know term need know used government organizations particularly related military espionage describes restriction data considered sensitive need-to-know restrictions even one necessary official approvals security clearance access certain information one would given access information read clandestine operation unless one specific need know access information must necessary one conduct one official duties term also includes anyone people knowledge deemed necessary share security mechanisms aim make difficult unauthorized access occur without inconveniencing legitimate access need-to-know also aims discourage browsing sensitive material limiting access smallest possible number people battle normandy 1944 example need-to-know restriction though thousands military personnel involved planning invasion small number knew entire scope operation rest informed data needed complete small part plan true trinity project first test nuclear weapon 1945 like security measures need know misused persons wish refuse others access information hold attempt increase personal power prevent unwelcome review work prevent embarrassment resulting actions thoughts need know also invoked hide extra-legal activities may considered necessary use detrimental abuse policy considered different perspectives need know detrimental workers efficiency speed computations ibm mechanical calculators los alamos dramatically increased calculators operators told numbers meant discretionary access control mechanisms operating systems used enforce need know case owner file determines whether another person access need know often concurrently applied mandatory access control schemes lack official approval clearance may absolutely prohibit person accessing information need know subjective assessment mandatory access control schemes also audit accesses order determine need know violated term also used concept graphical user interface design computers controlling complex equipment airplanes usage many different pieces data dynamically competing finite user interface space safety-related messages given priority
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Computer security
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tactical network solutions tactical network solutions maryland-based information security company specializing 802.11 wi-fi protected setup wps wps exploitation tool released open source community vulnerability wps publicly disclosed stefan viehbock december 27 2011
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Computer security
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ieee 802.1x ieee 802.1x ieee standard port-based network access control pnac part ieee 802.1 group networking protocols provides authentication mechanism devices wishing attach lan wlan ieee 802.1x defines encapsulation extensible authentication protocol eap ieee 802 known eap lan eapol eapol originally designed ieee 802.3 ethernet 802.1x-2001 clarified suit ieee 802 lan technologies ieee 802.11 wireless fiber distributed data interface iso 9314-2 802.1x-2004 eapol protocol also modified use ieee 802.1ae macsec ieee 802.1ar secure device identity devid 802.1x-2010 support service identification optional point point encryption local lan segment 802.1x authentication involves three parties supplicant authenticator authentication server supplicant client device laptop wishes attach lan/wlan term 'supplicant also used interchangeably refer software running client provides credentials authenticator authenticator network device provides data link client network allow block network traffic two ethernet switch wireless access point authentication server typically trusted server receive respond requests network access tell authenticator connection allowed various settings apply client connection setting authentication servers typically run software supporting radius eap protocols cases authentication server software may running authenticator hardware authenticator acts like security guard protected network supplicant i.e. client device allowed access authenticator protected side network supplicant identity validated authorized 802.1x port-based authentication supplicant must initially provide required credentials authenticator specified advance network administrator could include user name/password permitted digital certificate authenticator forwards credentials authentication server decide whether access granted authentication server determines credentials valid informs authenticator turn allows supplicant client device access resources located protected side network eapol operates data link layer ethernet ii framing protocol ethertype value 0x888e 802.1x-2001 defines two logical port entities authenticated port—the controlled port uncontrolled port controlled port manipulated 802.1x pae port access entity allow authorized state prevent unauthorized state network traffic ingress egress to/from controlled port uncontrolled port used 802.1x pae transmit receive eapol frames 802.1x-2004 defines equivalent port entities supplicant supplicant implementing 802.1x-2004 may prevent higher level protocols used content authentication successfully completed particularly useful eap method providing mutual authentication used supplicant prevent data leakage connected unauthorized network typical authentication procedure consists windows xp windows vista windows 7 support 802.1x network connections default windows 2000 support latest service pack sp4 wired connections windows mobile 2003 later operating systems also come native 802.1x client open source project known open1x produces client xsupplicant client currently available linux windows main drawbacks open1x client provide comprehensible extensive user documentation fact linux vendors provide package general wpa_supplicant used 802.11 wireless networks wired networks support wide range eap types iphone ipod touch support 802.1x release ios 2.0 android support 802.1x since release 1.6 donut chrome os supported 802.1x since mid-2011 mac os x offered native support since 10.3 avenda systems provides supplicant windows linux mac os x also plugin microsoft nap framework avenda also offers health checking agents windows defaults responding 802.1x authentication requests 20 minutes failed authentication cause significant disruption clients block period configured using hkey_local_machine\software\microsoft\dot3svc\blocktime dword value hkey_local_machine\software\microsoft\wlansvc\blocktime wireless networks registry entered minutes hotfix required windows xp sp3 windows vista sp2 make period configurable wildcard server certificates supported eaphost windows component provides eap support operating system implication using commercial certification authority individual certificates must purchased windows xp major issues handling ip address changes result user-based 802.1x authentication changes vlan thus subnet clients microsoft stated back port sso feature vista resolves issues users logging roaming profiles hotfix must downloaded installed authenticating via peap peap-mschapv2 windows vista based computers connected via ip phone may authenticate expected result client placed wrong vlan hotfix available correct windows 7 based computers connected via ip phone may authenticate expected result client placed wrong vlan hotfix available correct windows 7 respond 802.1x authentication requests initial 802.1x authentication fails cause significant disruption clients hotfix available correct enterprises deploying rolling operating systems remotely worth noting windows pe native support 802.1x however support added winpe 2.1 winpe 3.0 hotfixes available microsoft although full documentation yet available preliminary documentation use hotfixes available via microsoft blog linux distributions support 802.1x via wpa_supplicant desktop integration like networkmanager eduroam international roaming service mandates use 802.1x authentication providing network access guests visiting eduroam enabled institutions bt british telecom plc employs identity federation authentication services delivered wide variety industries governments devices support 802.1x authentication examples include network printers ethernet-based electronics like environmental sensors cameras wireless phones devices used protected network environment alternative mechanisms must provided authenticate one option would disable 802.1x port leaves port unprotected open abuse another slightly reliable option use mab option mab configured port port first try check connected device 802.1x compliant reaction received connected device try authenticate aaa server using connected device mac address username password network administrator must make provisions radius server authenticate mac-addresses either adding regular users implementing additional logic resolve network inventory database many managed ethernet switches offer options summer 2005 microsoft steve riley posted article detailing serious vulnerability 802.1x protocol involving man middle attack summary flaw stems fact 802.1x authenticates beginning connection authentication possible attacker use authenticated port ability physically insert perhaps using workgroup hub authenticated computer port riley suggests wired networks use ipsec combination ipsec 802.1x would secure eapol-logoff frames transmitted 802.1x supplicant sent clear contain data derived credential exchange initially authenticated client therefore trivially easy spoof shared media used part targeted dos wired wireless lans eapol-logoff attack malicious third party access medium authenticator attached repeatedly sends forged eapol-logoff frames target device mac address authenticator believing targeted device wishes end authentication session closes target authentication session blocking traffic ingressing target denying access network 802.1x-2010 specification began 802.1af addresses vulnerabilities previous 802.1x specifications using macsec ieee 802.1ae encrypt data logical ports running top physical port ieee 802.1ar secure device identity devid authenticated devices stopgap enhancements widely implemented vendors extended 802.1x-2001 802.1x-2004 protocol allowing multiple concurrent authentication sessions occur single port prevents traffic devices unauthenticated mac addresses ingressing 802.1x authenticated port stop malicious device snooping traffic authenticated device provides protection mac spoofing eapol-logoff attacks ietf-backed alternative protocol carrying authentication network access pana also carries eap although works layer 3 using udp thus tied 802 infrastructure
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Computer security
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preimage attack cryptography preimage attack cryptographic hash functions tries find message specific hash value cryptographic hash function resist attacks preimage set possible inputs context attack two types preimage resistance compared collision resistance computationally infeasible find two distinct inputs x x ′ hash output i.e. collision resistance implies second-preimage resistance guarantee preimage resistance conversely second-preimage attack implies collision attack trivially since addition x ′ x already known right start definition ideal hash function fastest way compute first second preimage brute-force attack n -bit hash attack time complexity 2 considered high typical output size n 128 bits complexity best achieved adversary hash function considered preimage-resistant however general result quantum computers perform structured preimage attack 2 also implies second preimage thus collision attack faster preimage attacks found cryptanalysing certain hash functions specific function significant preimage attacks already discovered yet practical practical preimage attack discovered would drastically affect many internet protocols case practical means could executed attacker reasonable amount resources example preimaging attack costs trillions dollars takes decades preimage one desired hash value one message practical one costs thousand dollars takes weeks might practical currently known practical almost-practical attacks md5 sha-1 collision attacks general collision attack easier mount preimage attack restricted set value two values used collide time complexity collision attack contrast 2 improve resistance collision attacks double hashing good solution case someone discovers preimage attack first hash bitcoin system uses double hashed sha256 common way slow hashing searches 2000s
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Computer security
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wally feurzeig wallace wally feurzeig june 10 1927 – january 4 2013 co-inventor seymour papert cynthia solomon programming language logo well-known researcher artificial intelligence ai wallace feurzeig born chicago parents mandel pauline feurzeig earned bachelor philosophy bachelor science degrees university chicago master science degree illinois institute technology worked argonne national laboratory university chicago joining bolt beranek newman bbn early 1960s bolt beranek newman become major center computer science research innovative applications 1962 wally feurzeig joined firm work newly available facilities artificial intelligence department one earliest ai organizations colleagues actively engaged pioneering ai work computer pattern recognition natural-language understanding automated theorem proving lisp language development robot problem solving much work done collaboration distinguished researchers massachusetts institute technology mit marvin minsky john mccarthy regular bbn consultants early 1960s groups bbn original work cognitive science instructional research man-computer communication first work knowledge representation reasoning semantic networks question answering interactive computer graphics computer-aided instruction cai actively underway j. c. r. licklider spiritual scientific leader much work championing cause on-line interaction era almost computing done via batch processing wally initial focus expanding intellectual abilities extant teaching systems led first intelligent cai system mentor employed production rules support problem-solving interactions medical diagnosis decision-making domains 1965 wally organized bbn educational technology department development computer methods improve learning teaching focus work shifted investigating programming languages educational environments shift partly due two recent technological advances invention computer time-sharing development first high-level conversational programming language idea sharing computer cycles among autonomous users working simultaneously stirred imagination cambridge 1963 1964 bbn mit teams raced first realize concept bbn winning days holding first successful demonstration computer time-sharing 1964 bbn initial system designed sheldon boilen supported five simultaneous users dec pdp-1 sharing one cathode-ray tube crt screen output seeing dynamic displays several distinct programs simultaneously asynchronously time tune breathtaking experience time sharing made feasible economic use remote distributed terminals opened possibilities interactive computer use schools bbn recently implemented telcomp one new breed high-level interactive programming languages telcomp dialect joss first conversational interpreted language developed 1962–63 cliff shaw rand corporation syntax similar language basic yet appeared like basic telcomp fortran-derived language originally designed numerical computational applications shortly telcomp created wally decided introduce children tool teach mathematics 1965–66 u.s. office education support explored use auxiliary resource eight elementary secondary schools served bbn time-sharing system students introduced telcomp worked standard arithmetic algebra trigonometry problems writing telcomp programs project strongly confirmed expectations use interactive computation high-level interpretive language would highly motivating students wally collaborators research daniel bobrow richard grant cynthia solomon bbn consultant seymour papert recently arrived mit jean piaget institute geneva idea programming language expressly designed children arose directly project group realized extant languages designed computation generally lacked facilities nonnumeric symbolic manipulation current languages inappropriate education respects also often employed extensive data type declarations got way students expressive impetus serious deficiencies control structures programs lacked procedural constructs facilities dynamic definition execution well-developed articulate debugging diagnostic editing facilities essential educational uses
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Programming language topics
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kenneth p. weiss kenneth p. weiss american entrepreneur human factors engineer inventor invented securid card trademark rsa security weiss holds bachelor degree university bridgeport continued graduate studies research university new hampshire temple university received doctorate neotarian fellowship founded security dynamics 1984 served ceo 1986 chairman board cto 1996 initiated purchase 1993 rsa security small encryption company working internet commerce 1994 security dynamics went public nasdaq stock exchange weiss company largest individual shareholder.. company developed sold securid card rsa encryption technologies computer security electronic commerce identity authentication resigned 1996 citing policy disagreements directors company operations policies company achieved market capitalization 4 billion 2006 company purchased emc corporation 1994 published article enumerating regarded seven significant flaws clipper chip initiative weiss ’ position article contributed abandonment multibillion-dollar u.s. government program weiss asserted would allowed electronic eavesdropping us citizen surveillance chip embedded private electronic communication equipment weiss taught penn state university bridgeport nasson college king college chairman psychology department seven years professor textbook author editorial board journal information systems security chairman identification authentication division american defense preparedness association committee computer security also member technology ethics committee information systems security association issa currently weiss founder ceo universal secure registry usr company based newton massachusetts develops technologies identification authentication mobile phone applications holds 22 u.s. patents well foreign patents weiss member american association advancement science honor societies sigma xi psi chi weiss also involved philanthropic work cape ann symphony rockport chamber music society gloucester stage co. gloucester schooner festival historical meeting house restoration cape ann historical association perfect storm foundation addison gilbert beverly hospitals lahey clinic political action groups
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Computer security
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iarchiver iarchiver software utility handling file archives apple macintosh renamed rucksack iarchiver designed universal tool working archives used create extract convert large number common legacy archive formats drag-and-drop interface iarchiver developed currently maintained dare creative ltd software company based vienna austria
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Computer file systems
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playstation 3 cluster considerable computing capability playstation 3 cell microprocessors raised interest using multiple networked ps3s various tasks require affordable high-performance computing national center supercomputing applications already built cluster based playstation 2 terra soft solutions version yellow dog linux playstation 3 sells ps3s linux pre-installed single units 8 32 node clusters addition rapidmind pushing stream programming package ps3 january 3 2007 dr. frank mueller associate professor computer science north carolina state university clustered 8 ps3s mueller commented 256 mb system ram limitation particular application considering attempting retrofit ram software includes fedora core 5 linux ppc64 mpich2 openmp v2.5 gnu compiler collection cellsdk 1.1 summer 2007 gaurav khanna professor physics department university massachusetts dartmouth independently built message-passing based cluster using 8 ps3s running fedora linux cluster built support sony computer entertainment first cluster generated published scientific results dubbed ps3 gravity grid ps3 cluster performs astrophysical simulations large supermassive black holes capturing smaller compact objects khanna claims cluster performance exceeds 100+ intel xeon core based traditional linux cluster simulations ps3 gravity grid gathered significant media attention 2007 2008 2009 2010 khanna also created diy website build clusters accessible general public november 2010 air force research laboratory created powerful supercomputer nicknamed condor cluster connecting together 1,760 sony ps3s include 168 separate graphical processing units 84 coordinating servers parallel array capable performing 500 trillion floating-point operations per second 500 tflops built condor cluster 33rd largest supercomputer world would used analyse high definition satellite imagery even single ps3 used significantly accelerate computations marc stevens arjen k. lenstra benne de weger demonstrated using single ps3 perform md5 bruteforce hours say essentially single playstation 3 performs like cluster 30 pcs price one november 2007 march 22 2007 sce stanford university expanded folding home project ps3 along thousands pcs already joined internet ps3 owners able lend computing power game systems study improper protein folding associated diseases alzheimer parkinson huntington cystic fibrosis several forms cancer software included part 1.6 firmware update march 22 2007 set run manually automatically ps3 idle cross media bar processed information sent back project central servers internet processing power ps3 users greatly contributing folding home project ps3s third nvidia amd gpus terms teraflops contributed march 2011 million ps3 owners allowed folding home software run systems 27,000 currently active total 8.1 petaflops comparison world powerful supercomputer november 2010 tianhe-ia peak performance 2.56 petaflops 2,566 teraflops latest report stated folding home passed 5 native petaflop mark 767 teraflops supplied playstation 3 clients computational biochemistry biophysics lab barcelona launched distributed computing project called ps3grid project expected run sixteen times faster equivalent project standard pc like distributed computing projects designed run computer idle ehits lightning first virtual screening molecular docking software ps3 released simbiosys reported bio-it world july 2008 application runs 30x faster single ps3 regular single cpu pc also runs ps3 clusters achieving screening huge chemical compound libraries matter hours days rather weeks used standard expectation march 28 2010 sony announced would disabling ability run operating systems v3.21 update due security concerns otheros update would affect existing supercomputing clusters due fact connected psn would forced update however would make replacing individual consoles compose clusters difficult impossible since newer models v3.21 higher would support linux installation directly caused end ps3 common use clustered computing though projects like condor still created older ps3 units come online april 1 2010 update released possible workaround might replace damaged tsop older ie ps3 fat consoles non-fatal hardware failures defective shaders ylod combined x-ray bga rework affected memory chips would acceptable applications principle would custom hardware dmca classed reverse engineering additional modifications would include upgrading thermal profile ie larger fan/more voltage replacing tsop completely socket surplus 256mb xd card installed place hackers already done development purposes
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Computer architecture
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gambas gambas name object-oriented dialect basic programming language well integrated development environment accompanies designed run linux unix-like computer operating systems name recursive acronym gambas almost means basic gambas also word prawns spanish french portuguese languages project logos derived gambas developed french programmer benoît minisini first release coming 1999 benoît grown basic language decided make free software development environment could quickly easily make programs user interfaces gambas 1.x versions featured interface made several different separate windows forms ide dialogues similar fashion interface gimp could also develop applications using qt oriented towards development applications kde last release 1.x versions gambas 1.0.19 first 2.x versions released january 2 2008 three four years development featured major redesign interface forms functions embedded single window well changes gambas syntax although part code compatibility kept featured major updates existing gambas components well addition new ones new components could use gtk+ sdl drawing utilize opengl acceleration gambas 2.x versions load run gambas 1.x projects occasional incompatibilities next major iteration gambas 3.x versions released december 31 2011 2015 benchmark published gambas website showed gambas 3.8.90 scripting faster varying degrees perl 5.20.2 outdated 2.7.10 version python many tests gambas designed build graphical programs using qt currently qt 4.x 5.x gtk+ toolkit gtk 3.x also supported 3.6.0 gambas ide written gambas gambas includes gui designer aid creating user interfaces also make command line applications gambas runtime environment needed run executables functionality provided variety components selected provide additional features drawing provided either qt gtk+ toolkits additional component designed switch drawing also provided simple directmedia layer currently version 1.x 2.x support works also utilized audio playback separate sound component component openal specification also added gpu acceleration support available opengl component well hardware functionally provided various components also components handling specialized tasks gambas developers also use databases mysql postgresql build kde qt gnome gtk+ applications dcop translate visual basic programs gambas run linux build network solutions create cgi web applications ide also includes tool creation installation packages supporting gnu autotools slackpkg pacman rpm debs latter two tailored specific distributions fedora/rhel/centos mageia mandriva opensuse debian ubuntu/mint gambas since version 3.2 ide integrated profiler started use just-in-time compilation technology gambas intended provide similar experience developing microsoft visual basic free software clone popular proprietary program author gambas makes clear similarities visual basic syntax basic programs integrated development environment gambas written start development environment seeks improve formula object model class represented file archiver package program inspired java programming language gambas intended alternative former visual basic developers decided migrate linux also important distinctions gambas visual basic one notable example gambas array indexes always start 0 whereas visual basic indexes start 0 1 gambas also supports += -= shorthand found classic visual basic features visual basic .net however several programs many forms example code written using gambas freecode formerly freshmeat listed 23 applications developed using gambas gambas wiki listed 70 several specialized sites list gambas applications code even gambas written application named gambas3 showcase acts software center download install gambas 3 applications several community sites including community forums mailing lists also exist gambas gambas included repositories number linux distributions debian fedora mandriva linux ubuntu microsoft windows version gambas run cygwin environment although version significantly less tested linux counterparts command-line cooperative linux derivatives also used well specialized linux virtual machines independent contributor françois gallo also worked porting gambas 3.x mac os x freebsd based using local versions x11 system gambas version 3.2 run raspberry pi offers just-in-time compilation november 2013 future portability gambas discussed listing main concerns linux kernel features utilized interpreter components using linux specific software libraries primarily x11-tying qt gtk+ desktop integration components however partly due need upgrade newer toolkits gtk 3 added 3.6.0 qt 5 3.8.0 future versions would less x11 tied making projects like cygwin utterly native versions platforms possible benoît minisini stated intended encapsulate x11 specific code aid attempt replace x11 support desktop component moved component 3.6.0 october 27 2016 screenshot setup guide released main page running gambas fully cygwin including components graphical toolkits complete ide relevant patches mainlined version 3.9.2 replaces prior recommended method using freenx forwarding linux server hello world program graphical user interface public sub main end program computes 100-term polynomial 500000 times repeats ten times used benchmarking private sub test x float float end public sub main end
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Programming language topics
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dynamic video memory technology dynamic video memory technology dvmt allows dynamic allocation system memory use video memory ensure efficient use available resources maximum 2d/3d graphics performance amount video memory dependent upon amount pre-allocated memory set system plus something called dvmt dvmt name implies dynamically allocates system memory use video memory ensure efficient use available resources maximum 2d/3d graphics performance technology used intel fulfill needs graphically demanding games
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Operating systems
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jeremy ashkenas jeremy ashkenas computer programmer known creation co-creation coffeescript livescript programming languages respectively backbone.js javascript framework underscore.js javascript library ashkenas speaker numerous conferences events worked graphics department new york times september 2015 returned september 2016 shared 2015 gerald loeb award images/graphics/interactives 2018 works observable company founded mike bostock aims create interactive notebooks
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Programming language topics
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legacy-free pc legacy-free pc type personal computer lacks floppy drive legacy ports industry standard architecture isa bus sometimes internal expansion bus according microsoft basic goal requirements operating system devices end users detect presence following isa slots devices legacy floppy disk controller fdc ps/2 serial parallel game ports legacy ports usually replaced universal serial bus usb ports usb adapter may used older device must connected pc lacking ports according 2001 edition microsoft pc system design guide legacy-free pc must able boot usb device away older usually bulky ports devices allows legacy-free pc much compact earlier systems many fall nettop one form factor netbooks ultrabooks could also considered portable form legacy-free pc legacy-free pcs difficult upgrade traditional beige box pc typically expected replaced completely become obsolete many legacy-free pcs include modern devices may used replace ones omitted memory card reader replacing floppy drive first decade 21st century progressed legacy-free pc went mainstream legacy ports removed commonly available computer systems form factors however ps/2 keyboard connector still retains use offer uses e.g implementation n-key rollover offered usb apple imac g3 first example legacy-free pc drawing much criticism lack legacy peripherals floppy drive apple desktop bus adb connector however success popularized usb november 1999 july 2000 dell webpc early less-successful wintel legacy-free pc legacy-free pcs introduced around 2000 prevalence usb broadband internet made many older ports devices obsolete largely took form low-end consumer systems motivation making computers less expensive easier use stable manageable dell studio hybrid asus eee box msi wind pc examples later more-successful intel-based legacy-free pcs apple introduced apple modem october 12 2005 removed internal 56k modem new computers macbook air introduced january 29 2008 also omits built-in superdrive wired ethernet connectivity available mac computers sold time superdrive would later removed macs end 2016 wired ethernet would later removed macbook models relaunched macbook 2015 dropped features magsafe charging port secure digital sd memory card reader kept two types ports 3.5mm audio jack usb 3.1 type-c port configuration later found way macbook pro 2016 difference two four usb ports included instead one addition macbook pro except entry-level model replaced function keys touch bar changes led criticism many users utilised features apple removed
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Distributed computing architecture
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x704 x704 microprocessor implements 32-bit version powerpc instruction set architecture isa developed exponential technology microprocessor notable high clock frequency time circa 1997 range 400 533 mhz use bipolar transistors logic cmos circuits memory failure see use apple macintosh opposite industry observers microprocessor report expected exponential technology eventually failed result x704 lack success former employees founded intrinsity start-up developed high clock frequency mips implementation fastmath company left microprocessor business licenses fast14 dynamic logic third parties ati gpus x704 superscalar microprocessor issued three instructions per cycle arithmetic logic unit alu floating-point unit fpu branch unit realize short cycle times caches kept small limiting performance three levels cache first consisted separate 2 kb instruction data caches direct-mapped l2 cache on-die 32 kb large eight-way set set-associative l3 cache larger supporting capacities 512 kb 2 mb located externally x704 contained 2.7 million transistors 0.7 million bipolar transistors 2.0 million metal oxide semiconductor mos measured 15 mm 10 mm 150 mm fabricated 0.5 µm bicmos process six levels interconnect used 3.6 2.1 v power supplies dissipated less 85 w 533 mhz x704 packaged 356-ball ball grid array bga
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Computer architecture
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wwf file format wwf modification open standard pdf format document exchange endorsed world wide fund nature also abbreviated wwf germany wwf format promoted environmentally friendly comparable document exchange formats e.g pdf doc since documents format designed difficult print motivation behind use format prevent unnecessary printing documents website claims file format able read programs open ordinary pdf files present software creating wwf files available mac os x 10.4 windows xp later open source equivalent available linux windows xp later wwf files simply pdf files security settings printing set allowed file extension .wwf thus inability print files comes drm built adobe reader looks flag pdf see whether printing allowed pdf readers ghostscript may honour no-print flag rendering wwf files printable initiative criticised restricting users rights ineffective non-adobe readers ghostscript print documents format violating bsd license incompatible goals free open source software movement software contacting wwf without user consent criticised wwf international director corporate relations maria boulos misleading launched global product despite created wwf german division without consultation wwf international
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Programming language topics
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password cracking cryptanalysis computer security password cracking process recovering passwords data stored transmitted computer system common approach brute-force attack try guesses repeatedly password check available cryptographic hash password purpose password cracking might help user recover forgotten password installing entirely new password less security risk involves system administration privileges gain unauthorized access system preventive measure system administrators check easily crackable passwords file-by-file basis password cracking utilized gain access digital evidence judge allowed access particular file access restricted time crack password related bit strength see password strength measure password entropy details password stored methods password cracking require computer produce many candidate passwords checked one example brute-force cracking computer tries every possible key password succeeds common methods password cracking dictionary attacks pattern checking word list substitution etc attempt reduce number trials required usually attempted brute force higher password bit strength exponentially increases number candidate passwords must checked average recover password reduces likelihood password found cracking dictionary ability crack passwords using computer programs also function number possible passwords per second checked hash target password available attacker number billions trillions per second since offline attack possible rate depends whether authentication software limits often password tried either time delays captchas forced lockouts number failed attempts another situation quick guessing possible password used form cryptographic key cases attacker quickly check see guessed password successfully decodes encrypted data kinds password hash ordinary desktop computers test hundred million passwords per second using password cracking tools running general purpose cpu billions passwords per second using gpu-based password cracking tools see john ripper benchmarks rate password guessing depends heavily cryptographic function used system generate password hashes suitable password hashing function bcrypt many orders magnitude better naive function like simple md5 sha user-selected eight-character password numbers mixed case symbols commonly selected passwords dictionary matches filtered reaches estimated 30-bit strength according nist 2 one billion permutations would cracked seconds hashing function naive ordinary desktop computers combined cracking effort done botnets capabilities password cracking considerably extended 2002 distributed.net successfully found 64-bit rc5 key four years effort included 300,000 different computers various times generated average 12 billion keys per second graphics processors speed password cracking factor 50 100 general purpose computers 2011 available commercial products claim ability test 2,800,000,000 passwords second standard desktop computer using high-end graphics processor device crack 10 letter single-case password one day work distributed many computers additional speedup proportional number available computers comparable gpus emergence hardware acceleration past decade gpu resources used increase efficiency speed brute force attack 2012 stricture consulting group unveiled 25-gpu cluster achieved brute force attack speed 350 billion guesses per second allowing check formula_1password combinations 5.5 hours using ocl-hashcat plus virtual opencl cluster platform linux-based gpu cluster used crack 90 percent 6.5 million password hashes belonging users linkedin despite capabilities desktop cpus slower cracking passwords purpose-built password breaking machines 1998 electronic frontier foundation eff built dedicated password cracker using asics opposed general purpose cpus machine deep crack broke des 56-bit key 56 hours testing 90 billion keys per second 2010 georgia tech research institute developed method using gpgpu crack passwords coming minimum secure password length 12 characters passwords difficult remember reduce security system users might need write electronically store password using insecure method b users need frequent password resets c users likely re-use password similarly stringent requirements password strength e.g mix uppercase lowercase letters digits change monthly greater degree users subvert system memorability security passwords jeff yan et al examines effect advice given users good choice password found passwords based thinking phrase taking first letter word memorable naively selected passwords hard crack randomly generated passwords combining two unrelated words another good method personally designed algorithm generating obscure passwords another good method however asking users remember password consisting mix uppercase lowercase characters similar asking remember sequence bits hard remember little bit harder crack e.g 128 times harder crack 7-letter passwords less user simply capitalizes one letters asking users use letters digits often lead easy-to-guess substitutions e → 3 → 1 substitutions well known attackers similarly typing password one keyboard row higher common trick known attackers research detailed april 2015 paper several professors carnegie mellon university shows people choices password structure often follow several known patterns result passwords may much easily cracked mathematical probabilities would otherwise indicate passwords containing one digit example disproportionately include end password july 16 1998 cert reported incident attacker found 186,126 encrypted passwords time discovered already cracked 47,642 passwords december 2009 major password breach rockyou.com website occurred led release 32 million passwords attacker leaked full list 32 million passwords identifiable information internet passwords stored cleartext database extracted sql injection vulnerability imperva application defense center adc analysis strength passwords june 2011 nato north atlantic treaty organization experienced security breach led public release first last names usernames passwords 11,000 registered users e-bookshop data leaked part operation antisec movement includes anonymous lulzsec well hacking groups individuals july 11 2011 booz allen hamilton large american consulting firm substantial amount work pentagon servers hacked anonymous leaked day leak dubbed 'military meltdown monday includes 90,000 logins military personnel—including personnel uscentcom socom marine corps various air force facilities homeland security state department staff looks like private sector contractors leaked passwords wound hashed unsalted sha-1 later analyzed adc team imperva revealing even military personnel used passwords weak 1234 july 18 2011 microsoft hotmail banned password 123456 july 2015 group calling impact team stole user data ashley madison many passwords hashed using relatively strong bcrypt algorithm weaker md5 hash attacking latter algorithm allowed 11 million plaintext passwords recovered best method preventing password cracked ensure attackers get access even hashed password example unix operating system hashed passwords originally stored publicly accessible file /etc/passwd modern unix similar systems hand stored shadow password file /etc/shadow accessible programs running enhanced privileges i.e. system privileges makes harder malicious user obtain hashed passwords first instance however many collections password hashes stolen despite protection another strong approach combine site-specific secret key password hash prevents plaintext password recovery even hashed values purloined third approach use key derivation functions reduce rate passwords guessed unfortunately many common network protocols transmit passwords cleartext use weak challenge/response schemes modern unix systems replaced traditional des-based password hashing function crypt stronger methods bcrypt scrypt systems also begun adopt methods instance cisco ios originally used reversible vigenère cipher encrypt passwords uses md5-crypt 24-bit salt enable secret command used newer methods use large salt values prevent attackers efficiently mounting offline attacks multiple user accounts simultaneously algorithms also much slower execute drastically increases time required mount successful offline attack many hashes used storing passwords md5 sha family designed fast computation efficient implementation hardware result ineffective preventing password cracking especially methods like rainbow tables using key stretching algorithms pbkdf2 form password hashes significantly reduce rate passwords tested solutions like security token give formal proof answer constantly shifting password solutions abruptly reduce timeframe brute forcing attacker needs break use password within single shift reduce value stolen passwords short time validity 2013 long-term password hashing competition announced choose new standard algorithm password hashing many password cracking software tools popular aircrack cain abel john ripper hashcat hydra davegrohl elcomsoft many litigation support software packages also include password cracking functionality packages employ mixture cracking strategies algorithm brute force dictionary attacks proving productive increased availability computing power beginner friendly automated password cracking software number protection schemes allowed activity taken script kiddies
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Computer security
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browser isolation browser isolation cybersecurity model aims physically isolate internet user browsing activity associated cyber risks away local networks infrastructure browser isolation technologies approach model different ways seek achieve goal effective isolation web browser user browsing activity method securing web browsers browser-based security exploits well web-borne threats ransomware malware browser isolation technology delivered customers cloud hosted service known remote browser isolation rbi model enables organizations deploy browser isolation solution users without managing associated server infrastructure also client side approaches browser isolation based client-side hypervisors depend servers order isolate users browsing activity associated risks instead activity virtually isolated local host machine client-side solutions break security physical isolation model allow avoid server overhead costs associated remote browser isolation solutions browser isolation white paper includes high level overview browser isolation cybersecurity concept explains differences client server side browser isolation models architectures browser isolation typically leverages virtualization containerization technology isolate users web browsing activity away endpoint device significantly reducing attack surface rogue links files browser isolation way isolate web browsing hosts high-risk behaviors away mission-critical data infrastructure browser isolation process physically isolate users browsing activity away local networks infrastructure isolating malware browser based cyber-attacks process 2017 american research group gartner identified remote browser browser isolation one top technologies security gartner report also forecast 50 enterprises would actively begin isolate internet browsing reduce impact cyber attacks coming three years similar research conducted transparency market research shows remote browser isolation market projected reach us 5079.8 end 2025 expanding exceptional cagr 19.6 according market research media remote browser isolation rbi market forecast reach 10 billion 2024 growing cagr 30 period 2019-2024 unlike traditional web security approaches antivirus software secure web gateways browser isolation zero trust approach rely filtering content based known threat patterns signatures traditional approaches ca n't handle 0-day attacks since threat patterns unknown rather browser isolation approach treats websites web content explicitly whitelisted untrusted isolates local device virtual environment container virtual machine web-based files rendered remotely end users access within browser without downloading alternatively files sanitized within virtual environment using file cleansing technologies content disarm reconstruction cdr allowing secure file downloads user device typically browser isolation solutions provide users 'disposable non-persistent browser environments browsing session closed times entire browser environment reset known good state simply discarded malicious code encountered session thus prevented reaching endpoint persisting within network regardless whether threat detected way browser isolation proactively combats known unknown zero-day threats effectively complementing security measures contributing defense-in-depth layered approach web security browser isolation began evolution 'security physical isolation cybersecurity model also known air-gap model security professionals physically isolating critical networks users infrastructures cybersecurity purposes decades although techniques breach 'air-gapped systems exist typically require physical access close proximity air-gapped system order effective use air-gap makes infiltration systems public internet extremely difficult impossible without physical access system first commercial browser isolation platforms leveraged national nuclear security administration lawrence livermore national laboratory los alamos national laboratory sandia national laboratories 2009 browser isolation platforms based virtualization used deliver non-persistent virtual desktops thousands federal government users june 2018 defense information systems agency disa announced request information cloud-based internet isolation solution part endpoint security portfolio rfi puts “ service would redirect act internet browsing end user ’ desktop remote server external department defense information network. ” time rfi largest known project browser isolation seeking cloud based service leveraging concurrent simultaneous use licenses ~60 total user base 3.1 million users
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Computer security
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virtuozzo company virtuozzo privately held software company specializing virtualization software divested parallels company 2016 virtuozzo developed first commercially available operating system-level virtualization container technology 2000 open-sourced 2005 form openvz company founded 1997 name swsoft maintained headquarters herndon virginia additional offices throughout north america europe asia research development offices located moscow russia sales offices germany singapore january 2002 virtuozzo 2.0 containers virtualization solution released 2003 swsoft acquired makers plesk web hosting products expanded presence germany novosibirsk russia december 2007 acquisition parallels inc. swsoft company announced plans change name parallels distribute products parallels brand name december 2015 virtuozzo spun became standalone company lead entrepreneur former parallels exec rob lovell may 2016 virtuozzo announced intention join open container initiative plans develop dedicated cloud-based servers well specialized linux distribution month virtuozzo launched virtuozzo application catalog developed partnership bitnami virtuozzo announced strategic partnership jelastic august 2016 produce virtuozzo devops application orchestration platform aimed mid large size companies company named george karidis ceo november 2016 karidis previously headed cloud business unit compucom april 2017 virtuozzo partnered packet.net distribute virtuozzo software packet virtuozzo operating system-level server virtualization solution designed centralize server management consolidate workloads reducing number physical servers required organizations use virtuozzo server consolidation disaster recovery server workload agility virtuozzo generate virtual machine host os like traditional vm software instead creates isolated virtual private servers vpss single physical server instance software run multiple linux vpss linux windows time server vps performs exactly like stand-alone server rebooted independently virtuozzo linux became available 2001 version supports 32- 64-bit microprocessors became available 2005 2002 virtuozzo proved 2.5 version software could run 2,500 instances red hat linux eight-processor dell server result intel partnered virtuozzo 2002 develop partitioning technology ia-64 processors linux architectures support virtuozzo linux x86 ia64 amd64 em64t itanium virtuozzo linux enables multiple linux distributions exist simultaneously one server based openvz linux-based os-level virtualization technology allows physical server run multiple isolated operating system instances 2005 company updated virtuozzo support 64-bit x86 processors virtuozzo requires least pentium iii server least 1 gb memory 4 gb available hard drive virtuozzo ’ management tools compatible microsoft ’ viridian virtual server software virtuozzo container staging processed company container platform openvz virtuozzo 7 incorporated optimized kernel-based virtual machine released july 2016 2012 company released virtuozzo storage targeted container storage second version virtuozzo storage released 2017
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Operating systems
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*lisp time connection machine designed built language actively developed assembly-level language named paris par allel nstruction et became evident better way program machine needed quickly waiting completion connection machine lisp cm lisp implementation high-level programming language lisp parallel computing extensions option cm lisp proposed danny hillis development expected continue several years *lisp interpreter initially developed became apparent quickly *lisp compiler translating *lisp lisp paris would needed attain gigaflops speed attainable theory connection machine *lisp compiler written jeff mincy first released 1986 application achieving two gigaflops helicopter wake simulator developed alan egolf employee united technologies j. p. massar thinking machines employee 1987 *lisp simulator emulator meant run *lisp code standard non-parallel machines developed time j. p. massar simulator still exists ported american national standards institute ansi common lisp cl 2001 older version written original cl exists carnegie mellon university cmu artificial intelligence ai repository later versions *lisp involving significant upgrades functions performance worked cliff lasser jeff mincy j. p. massar 1989 *lisp implemented thinking machines cm5 circa 1990–1991 j. p. massar mario bourgoin starlisp written common lisp cl thus full power cl behind use connection machine one needed host front-end use *lisp front-end run cl symbolics machines using genera sun microsystems workstations running lucid inc. lucid common lisp used operate *lisp starlisp operated p arallel var iable pvars represented connection machine memory essentially vectors one element per cm processor virtual processor starlisp consisted standard operations pvars like vector addition multiplication along communication primitives essentially reordered elements pvar using cm communication hardware optimally route data
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Programming language topics
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starcounter starcounter in-memory application platform built starcounter ab platform based combined in-memory database engine application server combined in-memory database engine application server keeps data one place technology called virtual machine database management system vmdbms patent related technology explains way system environment configured maintain database objects database memory within environment memory application executes application memory within environment memory upon instantiation database object application environment allocates memory database database object database providing master storage database object tables classes consequence vmdbms lets application database virtual memory space implication object-relational mapper orm instead database directly accessed using sql-like queries called newsql application code major drawback in-memory databases main memory volatile therefore ensure durability solution starcounter utilizes write transaction logs disk way done traditional sql databases data needs recovered possible going back transaction logs database maintains acid compliance using transactional scope transactional memory allows long-running transactions nested transactions parallel transactions starcounter uses model-view-viewmodel mvvm pattern view model hosted server server-side code written using c since platform making use .net framework communication client server done using thin client library sends json-patches recommended way build view starcounter applications use html css polymer web components little logic possible client side starcounter likened oracle timesten in-memory database sap hana common based in-memory technology often targeted towards customers use real-time applications main difference way database management system integrated sap hana makes use column-oriented database management system timesten hand uses relational database management system rdbms starcounter unique uses object-oriented approach integrated application vmdbms underlying rdmbs starcounter ab established started development starcounter 2006 received 1.8 million funding vc round led industrifonden 2015 continue development starcounter 2.0 beta version bundles web application framework database released august 2013 starcounter ab named cool vendor in-memory computing technologies 2015 gartner september 2017 starcounter ab took 35 million sek funding existing investors anonymous investor also september 2017 starcounter ab 2.2 million euro prize competition sme instrument open disruptive innovation scheme organized horizon 2020 starcounter used enterprise installations supply chain management application used swedish superstore gekås ullared
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Databases
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com file com file type simple executable file digital equipment operating systems 1970s codice_1 used filename extension text files containing commands issued operating system similar batch file introduction cp/m microcomputer operating system type files commonly associated com extension changed executable files convention later carried dos even complemented general exe file format executables compact com files remained viable frequently used dos codice_1 file name extension relation .com commercial top-level internet domain name however similarity name exploited malicious computer virus writers com format original binary executable format used cp/m including scp msx-dos well dos simple header exception cp/m 3 files contains standard metadata code data simplicity exacts price binary maximum size 65,280 ff00h bytes 256 bytes short 64 kb stores code data one segment since lacks relocation information loaded operating system pre-set address offset 0100h immediately following psp executed hence limitation executable size entry point fixed 0100h issue 8-bit machines since address 64k memory max 16-bit machines much larger address space format fell use intel 8080 cpu architecture 65,536 bytes memory could addressed address range 0000h ffffh cp/m first 256 bytes memory 0000h 00ffh reserved system use zero page user program loaded exactly 0100h executed com files fit model perfectly introduction mp/m concurrent cp/m possibility running one program command time program loaded 0100h run although file format dos cp/m .com files two operating systems compatible dos com files contain x86 instructions possibly dos system calls cp/m com files contain 8080 instructions cp/m system calls programs restricted certain machines could also contain additional instructions 8085 z80 .com files dos set x86 segment registers value sp stack pointer register fffeh thus stack begins top memory segment works original dos 1.x api derivative cp/m api program termination .com file would performed calling int 20h terminate program function else int 21h function 0 served purpose programmer also ensure code data segment registers contained value program termination avoid potential system crash although could used dos version microsoft recommended use int 21h function 4ch program termination dos 2.x onward require data code segment set value possible make .com file run operating systems form fat binary true compatibility instruction level instructions entry point chosen equal functionality different operating systems make program execution jump section operating system use basically two different programs functionality single file preceded code selecting one use cp/m 3 first byte com file c9h 256-byte header since c9h corresponds 8080 instruction codice_3 means com file immediately terminate run earlier version cp/m support extension instruction sets 8085 z80 supersets 8080 instruction set works three processors c9h invalid opcode 8088/8086 cause processor-generated interrupt 6 exception v86 mode 386 later x86 chips since c9h opcode leave since 80188/80186 therefore used first instruction valid program executable loader versions dos rejects com files start c9h avoiding crash files may names ending .com simple format described indicated magic number start file example command.com file dr dos 6.0 actually dos executable format indicated first two bytes mz 4dh 5ah initials mark zbikowski dos memory management provided com files loader execution environment memory simply available com file execution operating system command shell command.com reloaded leaves possibilities com file either simple using single segment arbitrarily complex providing memory management system example complex program command.com dos shell provided loader load com exe programs .com system larger programs available memory size loaded run system loader assumes code data first segment .com program provide organization programs larger available memory large data segments handled dynamic linking necessary code included .com program advantage using .com rather .exe format binary image usually smaller easier program using assembler compilers linkers sufficient power became available longer advantageous use .com format complex programs format still executable many modern windows nt-based platforms run ms-dos-emulating subsystem ntvdm present 64-bit variants com files executed also dos emulators dosbox platform supported emulators windows nt-based operating systems use .com extension small number commands carried ms-dos days although fact presently implemented .exe files operating system recognize .exe file header execute correctly despite technically incorrect .com extension fact .exe file renamed .com still execute correctly use original .com extensions commands ensures compatibility older dos batch files may refer full original filenames commands codice_4 codice_5 codice_6 codice_7 codice_8 codice_9 dos directory contains com file exe file name extension specified com file preferentially selected execution example directory system path contains two files named codice_10 codice_11 following would execute codice_10 user wishing run codice_11 explicitly use complete filename taking advantage default behaviour virus writers malicious programmers used names like codice_14 creations hoping placed directory corresponding exe file command batch file may accidentally trigger program instead text editor codice_15 .com files may fact contain .exe format executable windows nt derivatives windows 2000 windows xp windows vista windows 7 pathext variable used override order preference acceptable extensions calling files without specifying extension command line default value still places codice_16 files codice_17 files closely resembles feature previously found jp software line extended command line processors 4dos 4os2 4nt computer virus writers hoped take advantage modern computer users likely lack knowledge .com file extension associated binary format along likely familiarity .com internet domain name e-mails sent attachment names similar www.example.com unwary microsoft windows users clicking attachment would expect begin browsing site named codice_18 instead would run attached binary command file named codice_19 giving full permission machine whatever author mind nothing malicious com file format exploitation coincidental name collision .com com mand files .com com mercial web sites
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Operating systems
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mnogosearch mnogosearch open-source search engine unix-like computer systems written c. distributed gnu general public license designed organize search within website group websites intranet local system mnogosearch index text/plain text/html text/xml data natively many others datatypes using external parsers engine ready index multilingual websites wide range character sets languages supported detected automatically uses content negotiation technology fetch versions page different languages perform diacritic-insensitive search segment phrases chinese japanese thai possible use synonyms ispell-based fuzzing extend search results results sorted relevance last modified time title windows version mnogosearch features graphical user interface sold commercial license march 2019 software longer maintained available
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Web technology
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activision decathlon activision decathlon sports game written david crane atari 2600 published activision 1983 ported atari 8-bit family atari 5200 commodore 64 colecovision msx platforms four players compete ten different events real-life decathlon either sequence individually game became somewhat notorious amount wear damage inflicted upon console controllers namely atari 2600 version rapid back-and-forth movement joystick propels athlete track game later reissued simply decathlon uk budget label firebird subsequently featured playstation 2 compilation activision anthology atari 2600 version decathlon reviewed video magazine arcade alley column described absolute triumph imaginative programming masterwork
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Computer architecture
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cpuid codice_1 instruction identified codice_1 opcode processor supplementary instruction name derived cpu identification x86 architecture allowing software discover details processor introduced intel 1993 introduced pentium sl-enhanced 486 processors program use codice_1 determine processor type whether features mmx/sse implemented prior general availability codice_1 instruction programmers would write esoteric machine code exploited minor differences cpu behavior order determine processor make model outside x86 family developers mostly still required use esoteric processes involving instruction timing cpu fault triggers determine variations cpu design present motorola 680x0 family -- never cpuid instruction kind -- certain specific instructions required elevated privileges could used tell various cpu family members apart 68000 offered unprivileged move sr 2 different cpus could told apart cpu error condition triggered codice_1 instruction specific x86 architecture architectures like arm often provide on-chip registers read prescribed ways obtain sorts information provided x86 cpuid instruction codice_1 opcode 0fh a2h two bytes a20fh single word assembly language codice_1 instruction takes parameters codice_1 implicitly uses eax register determine main category information returned intel recent terminology called cpuid leaf codice_1 called codice_10 first store eax register highest eax calling parameter leaf cpu implements obtain extended function information codice_1 called significant bit eax set determine highest extended function calling parameter call codice_1 codice_13 cpuid leaves greater 3 less 80000000 accessible model-specific registers ia32_misc_disable.boot_nt4 bit 22 0 default name suggests windows nt4 boot properly unless bit set later versions windows need basic leaves greater 4 assumed visible current windows systems basic valid leaves go 14h information returned leaves disclosed publicly available documentation i.e reserved recently added leaves also sub-leaves selected via ecx register calling cpuid returns cpu manufacturer id string twelve-character ascii string stored ebx edx ecx order highest basic calling parameter largest value eax set calling codice_1 returned eax list processors highest function implemented following known processor manufacturer id strings following known id strings virtual machines instance genuineintel processor values returned ebx 0x756e6547 edx 0x49656e69 ecx 0x6c65746e following code written gnu assembler x86-64 architecture displays vendor id string well highest calling parameter cpu implements returns cpu stepping model family information register eax also called signature cpu feature flags registers edx ecx additional feature info register ebx processor info feature flags manufacturer specific usually intel values used manufacturers sake compatibility reserved fields masked using processor identification purposes returns list descriptors indicating cache tlb capabilities eax ebx ecx edx registers returns processor serial number processor serial number introduced intel pentium iii due privacy concerns feature longer implemented later models psn feature bit always cleared transmeta efficeon crusoe processors also provide feature amd cpus however implement feature cpu models intel pentium iii cpus serial number returned edx ecx registers transmeta efficeon cpus returned ebx eax registers transmeta crusoe cpus returned ebx register note processor serial number feature must enabled bios setting order function two leaves used processor topology thread core package cache hierarchy enumeration intel multi-core hyperthreaded processors amd use leaves alternate ways core enumeration unlike cpuid leaves leaf bh return different values edx depending logical processor cpuid instruction runs value returned edx actually x2apic id logical processor x2apic id space continuously mapped logical processors however gaps mapping meaning intermediate x2apic ids n't necessarily correspond logical processor additional information mapping x2apic ids cores provided registers although leaf bh sub-leaves selected ecx described value returned edx affected logical processor instruction running subleaf processor topology exposed leaf bh hierarchical one strange caveat order logical levels hierarchy n't necessarily correspond order physical hierarchy smt/core/package however every logical level queried ecx subleaf bh leaf correspondence level type either smt core invalid level id space starts 0 continuous meaning level id invalid higher level ids also invalid level type returned bits 15:08 ecx number logical processors level queried returned ebx finally connection levels x2apic ids returned eax 4:0 number bits x2apic id must shifted order obtain unique id next level example dual-core westmere processor capable hyperthreading thus two cores four threads total could x2apic ids 0 1 4 5 four logical processors leaf bh =eax subleaf 0 =ecx cpuid could instance return 100h ecx meaning level 0 describes smt hyperthreading layer return 2 ebx two logical processors smt units per physical core value returned eax 0-subleaf 1 case shifting aforementioned x2apic ids right one bit gives unique core number next level level id hierarchy erases smt id bit inside core simpler way interpret information last bit bit number 0 x2apic id identifies smt/hyperthreading unit inside core example advancing subleaf 1 making another call cpuid eax=bh ecx=1 could instance return 201h ecx meaning core-type level 4 ebx 4 logical processors package eax returned could value greater 3 happens bit number 2 used identify core x2apic id note bit number 1 x2apic id used example however eax returned level could well 4 happens clarkdale core i3 5x0 also gives unique id package level =0 obviusly shifting x2apic id 4 bits finally may wonder eax=4 leaf tell us n't find already eax 31:26 returns apic mask bits reserved package would 111b example bits 0 2 used identifying logical processors inside package bit 1 also reserved although used part logical processor identification scheme words apic ids 0 7 reserved package even though half values n't map logical processor cache hierarchy processor explored looking sub-leaves leaf 4 apic ids also used hierarchy convey information different levels cache shared smt units cores continue example l2 cache shared smt units core physical cores westmere indicated eax 26:14 set 1 information l3 cache shared whole package indicated setting bits least 111b cache details including cache type size associativity communicated via registers leaf 4 beware older versions intel app note 485 contain misleading information particularly respect identifying counting cores multi-core processor errors misinterpreting information even incorporated microsoft sample code using cpuid even 2013 edition visual studio also sandpile.org page cpuid intel code sample identifying processor topology correct interpretation current intel software developer ’ manual clear language open source cross-platform production code wildfire games also implements correct interpretation intel documentation topology detection examples involving older pre-2010 intel processors lack x2apic thus n't implement eax=bh leaf given 2010 intel presentation beware using older detection method 2010 newer intel processors may overestimate number cores logical processors old detection method assumes gaps apic id space assumption violated newer processors starting core i3 5x0 series newer processors also come x2apic topology correctly determined using eax=bh leaf method returns extended feature flags ebx ecx edx highest calling parameter returned eax returns extended feature flags edx ecx amd feature flags follows return processor brand string eax ebx ecx edx codice_1 must issued parameter sequence get entire 48-byte null-terminated ascii processor brand string necessary check whether feature present cpu issuing codice_1 codice_13 first checking returned value greater equal 80000004h function contains processor ’ l1 cache tlb characteristics returns details l2 cache ecx including line size bytes type associativity encoded 4 bits cache size function provides advanced power management feature identifiers returns largest virtual physical address sizes eax bits 07-00 physical address bits bits 15-8 linear address bits bits 31-16 reserved 0 could used hypervisor virtual machine system report physical/virtual address sizes possible virtual cpu specific amd k7 k8 cpus returns string hammer time eax ebx ecx edx information easy access languages well instance c code gcc prints first five values returned cpuid generally useful c implementation works 32- 64-bit systems gcc also provides header called codice_18 systems cpuid codice_19 macro expanding inline assembly typical usage would one requested extended feature present cpu would notice might get random unexpected results safer version also provided codice_18 checks extended features safety checks output values passed using reference-like macro parameters conventional pointers notice ampersands codice_21 conditional statement codice_22 call receives correct request return non-zero value fails zero microsoft visual c compiler builtin function codice_23 cpuid instruction may embedded without using inline assembly handy since x86-64 version msvc allow inline assembly program msvc would borland/embarcadero c compilers bcc32 native asm function calls necessary asm implementation pseudo code many interpreted compiled scripting languages capable using cpuid via ffi library one implementation shows usage ruby ffi module execute assembly language includes cpuid opcode non-x86 cpu architectures also provide certain forms structured information processor abilities commonly set special registers dsp transputer-like chip families taken instruction noticeable way spite relative terms many variations design alternate ways silicon identification might present example dsps texas instruments contain memory-based register set functional unit starts identifiers determining unit type model asic design revision features selected design phase continues unit-specific control data registers access areas performed simply using existing load store instructions thus devices need extending register set device identification purposes according note former intel app note 485 specifically cpuid incorporated intel® 64 ia-32 architectures software developer ’ manual manual however still directs reader app note 485 information latest published version app note 485 dating may 2012 available via archive.org app note 485 contains information easily misinterpreted though particularly respect big intel manuals tend lag behind intel isa document available top page updated even processors yet publicly available thus usually contains cpuid bits example writing isa book revision 19 dated may 2014 documents clflushopt bit leaf 7 big manuals although apparently up-to-date revision 51 dated june 2014 n't mention
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Computer architecture
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udoo udoo single-board computer integrated arduino due compatible microcontroller designed computer science education world makers internet things product launched kickstarter april 2013 reaching wide consensus product line involves three single board computers – udoo quad/dual 2013 udoo neo 2015 udoo x86 2016 – differ various aspects plus udoo blu set udoo bricks udoo development platform merges dual quad core arm freescale cortex-a9 i.mx 6 cpu run linux android operating systems arduino due compatible board dedicated arm atmel sam3x8e cpu udoo joint effort aidilab srl seco usa inc collaboration multidisciplinary team researchers expertise interaction design embedded systems sensor networks cognitive science udoo project launched kickstarter april 9 2013 aidilab — siena university startup — seco embedded computing firm reached goal 27,000 40 hours goal well exceeded 4,172 backers pledged 641,614 udoo board equipped two cpus freescale i.mx 6 arm cortex a9 processor based arm v7 instruction set next generation graphics high-definition video central i.mx 6 series i.mx 6 series supports 1080p60 video playback enabling exceptional high-quality videos low power consumption devices playing high-definition content 3d graphics engine top line i.mx 6 quad i.mx 6 dual processors capable providing 200 mt/s enables ultra-vivid realistic graphics critical multimedia applications combine power main cores until-now-untapped potential 3d engine perform computational tasks otherwise atmel sam3x implements real-time computing allows full compatibility arduino due prototyping board solution udoo used like arduino due microcontroller programmed way stand-alone different clocks shared memory process tasks asynchronously without kind emulation however share communication channels i.mx 6 dual/6 quad application processors latest additions freescale semiconductor growing family multimedia-focused products offering high performance processing optimized lowest power consumption i.mx 6 dual/6 quad processors feature freescale advanced implementation arm cortex-a9 core interfaced ddr3-1066 lv-ddr3-1066 lpddr2-1066 single dual channel dram memory devices i.mx 6 dual/6 quad processor based arm cortex a9 mpcore platform following features arm cortex a9 mpcore complex includes i.mx 6 quad processor makes use dedicated hardware accelerators order meet targeted multimedia performance use hw accelerators key factor inobtaining high performance low power consumption numbers keeping cpu core relatively free perform tasks i.mx 6 quad processor incorporates following hardware accelerators miscellaneous ips interfaces atmel ’ sam3x/a series member family flash microcontrollers based high performance 32-bit arm cortex-m3 risc processor operates maximum speed 84 mhz features 512 kbytes flash 100 kbytes sram peripheral set includes high speed usb host device port embedded transceiver ethernet mac 2x cans high speed mci sdio/sd/mmc external bus interface nand flash controller 5x uarts 2x twis 4x spis well 1 pwm timer 9x general-purpose 32- bit timers rtc 12-bit adc 12-bit dac sam3x/a series ready capacitive touch thanks qtouch library offering easyway implement buttons wheels sliders sam3x/a architecture specifically designed sustain high speed data transfers includes multi-layer bus matrix well multiple sram banks pdc dma channels enable run tasks parallel maximize data throughput operates 1.62v 3.6v available 100- 144-pin qfp lfbga packages sam3x/a devices particularly well suited networking applications industrial home/building automation gateways freescale i.mx 6 atmel sam3x connected uart serial port embedded board works exactly like arduino connected external computer usb cable sam3x linux communicate two way channel exchanging messages tested baudrate 115200 serial connection also accessible external pins 0 1 arduino compatible pinout sam3x programming port accessible way arduino due via usb-to-serial converter directly external pinout serial uart connected imx 6 pins keyrow0 keycol0 sam3x side connected pins urxd utxd shared serial also available micro-usb plug cn6 removing j18 jumper communicate channel becomes shared udoo uses 4 micron mt41j256m16re-15e ram modules 2gbit module total 1gbyte clock frequency 400mhz udoo dual 528mhz udoo quad memory system consists following levels mac-net core conjunction 10/100/1000 mac implements layer 3 network acceleration functions functions designed accelerate processing various common networking protocols ip tcp udp icmp providing wire speed services client applications udoo uses ksz9031rnx ethernet transceiver completely integrated triple-speed 10base-t/100base-tx/1000base-t ethernet physical layer transceiver transmission reception data standard cat-5 unshielded twisted pair utp cable ksz9031rnx provides reduced gigabit media independent interface rgmii direct connection rgmii macs gigabit ethernet processors switches data transfer 10/100/1000 mbit/s ksz9031rnx reduces board costs simplifies board layout using on-chip termination resistors four differential pairs integrating ldo controller drive low-cost mosfet supply 1.2v core gwf-3m08 wlan module supporting ieee 802 11 b/g/n standards 6-pin connector supporting usb 2.0 /1.1 interface small form factor low cost compact wlan module designed wireless connectivity products embedded system module operates 2.4 ghz ism frequency band applies highly integrated mac/bbp rf single chip rt5370 150mbit/s phy rate supporting module built-in embedded applications ip camera ip set top box gps internet radio apparatus directly soldered main pcb features front connectors ports up-side connectors ports summary features gpu3d includes udoo provides one two i.mx 6 lvds outputs external pinout input used communicate rgb data controls external lcd displays lvds interface lvds receivers lvds port may used one single-channel output boot android otg bus switched connect sam3x therefore connection two processors plug usb cable cn3 ’ work since disconnected setup i.mx 6 communicate sam3x using android adk protocol must program sam3x sketch includes specific libraries installs app android configured use adk protocol udoo based dual quad core arm cortex-a9 cpu delivering great performance android linux os dedicated arm processor gpio specifications available accessories udoo board comes two micro sd card optional android ubuntu linux installed
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Computer architecture
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out-of-order execution computer engineering out-of-order execution formally dynamic execution paradigm used high-performance central processing units make use instruction cycles would otherwise wasted paradigm processor executes instructions order governed availability input data execution units rather original order program processor avoid idle waiting preceding instruction complete meantime process next instructions able run immediately independently out-of-order execution restricted form data flow computation major research area computer architecture 1970s early 1980s important academic research subject led yale patt hpsm simulator paper james e. smith a. r. pleszkun published 1985 completed scheme describing precise behavior exceptions could maintained out-of-order machines arguably first machine use out-of-order execution cdc 6600 1964 uses scoreboard resolve conflicts although modern usage scoreboarding considered in-order execution out-of-order execution since machines stall first raw conflict – strictly speaking machines initiate execution in-order although may complete execution out-of-order three years later ibm system/360 model 91 1966 introduced tomasulo algorithm makes full out-of-order execution possible 1990 ibm introduced first out-of-order microprocessor power1 although out-of-order execution limited floating-point instructions also case model 91 1990s out-of-order execution became common featured ibm/motorola powerpc 601 1993 fujitsu/hal sparc64 1995 intel pentium pro 1995 mips r10000 1996 hp pa-8000 1996 amd k5 1996 dec alpha 21264 1996 notable exceptions trend include sun ultrasparc hp/intel itanium intel atom silvermont architecture ibm power6 high logical complexity out-of-order technique reason reach mainstream machines mid-1990s many low-end processors meant cost-sensitive markets still use paradigm due large silicon area required implementation low power usage another design goal harder achieve out-of-order execution oooe design vulnerability microprocessor manufacturers implementations out-of-order execution mechanism reported manufacturers june 1 2017 publicized january 2018 exploitable vulnerability led millions vulnerable systems vulnerability named spectre similar vulnerability meltdown disclosed time took advantage assumption manufacturers made loading data processor cache allowing data cached privileged security boundary resulted race condition could timed leak privileged information earlier processors processing instructions performed instruction cycle normally consisting following steps new paradigm breaks processing instructions steps key concept oooe processing allow processor avoid class stalls occur data needed perform operation unavailable outline oooe processor avoids stall occurs step 2 in-order processor instruction completely ready processed due missing data oooe processors fill slots time instructions ready re-order results end make appear instructions processed normal way instructions ordered original computer code known program order processor handled data order order data operands become available processor registers fairly complex circuitry needed convert one ordering maintain logical ordering output processor runs instructions seemingly random order benefit oooe processing grows instruction pipeline deepens speed difference main memory cache memory processor widens modern machines processor runs many times faster memory time in-order processor spends waiting data arrive could processed large number instructions one differences created new paradigm creation queues allows dispatch step decoupled issue step graduation stage decoupled execute stage early name paradigm decoupled architecture earlier in-order processors stages operated fairly lock-step pipelined fashion instructions program may run correct order long end result correct separates fetch decode stages execute stage pipelined processor using buffer buffer purpose partition memory access execute functions computer program achieve high-performance exploiting fine-grain parallelism two effectively hides memory latency processor perspective larger buffer theory increase throughput however processor branch misprediction entire buffer may need flushed wasting lot clock cycles reducing effectiveness furthermore larger buffers create heat use die space reason processor designers today favour multi-threaded design approach decoupled architectures generally thought useful general purpose computing handle control intensive code well control intensive code include things nested branches occur frequently operating system kernels decoupled architectures play important role scheduling long instruction word vliw architectures avoid false operand dependencies would decrease frequency instructions could issued order technique called register renaming used scheme physical registers defined architecture physical registers tagged multiple versions architectural register exist time queue results necessary resolve issues branch mispredictions exceptions/traps results queue allows programs restarted exception requires instructions completed program order queue allows results discarded due mispredictions older branch instructions exceptions taken older instructions ability issue instructions past branches yet resolve known speculative execution
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Computer architecture
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media foundation media foundation mf com-based multimedia framework pipeline infrastructure platform digital media windows vista windows 7 windows 8 windows 8.1 windows 10 intended replacement microsoft directshow windows media sdk directx media objects dmos so-called legacy multimedia apis audio compression manager acm video windows vfw existing directshow technology intended replaced media foundation step-by-step starting features time co-existence media foundation directshow media foundation available previous windows versions including windows xp first release present windows vista focuses audio video playback quality high-definition content i.e hdtv content protection unified approach digital data access control digital rights management drm interoperability integrates dxva 2.0 offloading video processing pipeline hardware better performance videos processed colorspace encoded handed hardware composes image native colorspace prevents intermediate colorspace conversions improve performance mf includes new video renderer called enhanced video renderer evr next iteration vmr 7 9 evr better support playback timing synchronization uses multimedia class scheduler service mmcss new service prioritizes real time multimedia processing reserve resources required playback without tearing glitches second release included windows 7 introduces expanded media format support dxva hd acceleration hd content wddm 1.1 drivers used mf architecture divided control layer core layer platform layer core layer encapsulates functionality media foundation consists media foundation pipeline three components media source media sink media foundation transforms mft media source object acts source multimedia data either compressed uncompressed encapsulate various data sources like file network server even camcorder source specific functionality abstracted common interface source object use source resolver object creates media source uri file bytestream support non-standard protocols added creating source resolver source object also use sequencer object use sequence sources playlist coalesce multiple sources single logical source media sink recipient processed multimedia data media sink either renderer sink renders content output device archive sink saves content onto persistent storage system file renderer sink takes uncompressed data input whereas archive sink take either compressed uncompressed data depending output type data media sources sinks acted upon mfts mfts certain functions transform data another form mfts include multiplexers demultiplexers codecs dsp effects like reverb core layer uses services like file access networking clock synchronization time multimedia rendering part platform layer provides services necessary accessing source sink byte streams presentation clocks object model lets core layer components function asynchronously generally implemented os services pausing stopping fast forward reverse time-compression achieved controlling presentation clock however media pipeline components connected rather presented discrete components application running control layer choose source types transforms sinks needed particular video processing task hand set connections components topology complete data flow pipeline example play back compressed audio/video file pipeline consist file source object demultiplexer specific file container format split audio video streams codecs decompress audio video streams dsp processors audio video effects finally evr renderer sequence video capture application camcorder act video audio sources codec mfts work compress data feed multiplexer coalesces streams container finally file sink network sink write file stream network application also co-ordinate flow data pipeline components control layer pull request samples one pipeline component pass onto next component order achieve data flow within pipeline contrast directshow push model pipeline component pushes data next component media foundation allows content protection hosting pipeline within protected execution environment called protected media path control layer components required propagate data pipeline rate rendering synchronizes presentation clock rate time rendering embedded part multimedia stream metadata source objects extract metadata pass metadata two types coded metadata information bit rate presentation timings descriptive metadata like title author names coded metadata handed object controls pipeline session descriptive metadata exposed application use chooses media foundation provides media session object used set topologies facilitate data flow without application explicitly exists control layer exposes topology loader object application specifies required pipeline topology loader creates necessary connections components media session object manages job synchronizing presentation clock creates presentation clock object passes reference sink uses timer events clock propagate data along pipeline also changes state clock handle pause stop resume requests application theoretically one media foundation architecture media session pipeline media source transform media sink model however architecture complex set considerable scope lightweight relatively easy configure mf components designed handle processing media data simple point solutions thus practical considerations necessitated implementation variations fundamental pipeline design components source reader sink writer operate outside pipeline model developed sources split media foundation architecture three general classes pipeline architecture distinguished use distinct media session object pipeline media data flows one media sources one media sinks optionally zero media transforms media session manages flow media data pipeline pipeline multiple forks branches mf application get access media data traverses media source media sink implementing custom media transform component inserting appropriate location pipeline reader-writer architecture uses component called source reader provide media data sink writer component consume source reader contain type internal pipeline accessible application source reader media source sink writer media sink neither directly included pipeline managed media session general media data flows source reader sink writer actions application application either take packets media data called media samples source reader give directly sink writer set callback function source reader performs operation effect manages data transport application performs similar role media session pipeline architecture application since mf application manages transmission media samples source reader sink writer always access raw media data source reader sink writer components limited ability automatically load media transforms assist conversion format media data however done internally application little control source reader sink writer provide ease use pipeline architecture offers extremely sophisticated control flow media data however many components available pipeline enhanced video renderer simply readily usable reader-writer architecture application since structure media sample produced source reader identical output media source possible set pipeline architecture media samples intercepted pass pipeline copy given media sink known hybrid architecture makes possible application takes advantage sophisticated processing abilities media session pipeline utilizing ease use sink writer sink writer part pipeline interact media session effect media data processed special media sink called sample grabber sink consumes media data hands copy sink writer also possible implement hybrid architecture custom media transform copies media samples passes sink writer pass pipeline cases special component pipeline effectively acts like simple reader-writer application feeds sink writer general hybrid architectures use pipeline sink writer theoretically possible implement mechanism source reader could somehow inject media samples pipeline unlike sample grabber sink standard component exists media foundation transforms mfts represent generic model processing media data used media foundation primarily implement decoders encoders mixers digital signal processors dsps – media sources media sinks media foundation transforms evolution transform model first introduced directx media objects dmos behaviors clearly specified hybrid dmo/mft objects also created applications use mfts inside media foundation pipeline use directly stand-alone objects mfts following type microsoft recommends developers write media foundation transform instead directshow filter windows vista windows 7 windows 8 video editing video capture microsoft recommends using directshow primary focus media foundation windows vista starting windows 7 mfts also support hardware-accelerated video processing encoding decoding avstream-based media devices media foundation uses enhanced video renderer evr rendering video content acts mixer well mix 16 simultaneous streams first stream reference stream reference stream per-pixel transparency information well specified z-order reference stream transparent pixels fixed z-order position back streams final image composited onto single surface coloring pixel according color transparency corresponding pixel streams internally evr uses mixer object mixing streams also deinterlace output apply color correction required composited frame handed presenter object schedules rendering onto direct3d device shares dwm applications using device frame rate output video synchronized frame rate reference stream streams called substreams different frame rate evr discards extra frames substream higher frame rate uses frame lower frame rate windows media audio windows media video default supported formats encoding media foundation windows vista decoding mp3 file source available windows vista read mp3 streams mp3 file sink output mp3 available windows 7 format support extensible however developers add support formats writing encoder/decoder mfts and/or custom media sources/media sinks windows 7 expands upon codec support available windows vista includes avi wav aac/adts file sources read respective formats mpeg-4 file source read mp4 m4a m4v mp4v mov 3gp container formats mpeg-4 file sink output mp4 format similar windows vista transcoding encoding support exposed built-in windows application several codecs included media foundation transforms mfts addition windows media audio windows media video encoders decoders asf file sink file source introduced windows vista windows 7 includes h.264 encoder baseline profile level 3 main profile support aac low complexity aac-lc profile encoder playback various media formats windows 7 also introduces h.264 decoder baseline main high-profile support level 5.1 aac-lc he-aac v1 sbr multichannel he-aac v2 ps stereo decoders mpeg-4 part 2 simple profile advanced simple profile decoders includes decoding popular codec implementations divx xvid nero digital well mjpeg dv mft decoders avi windows media player 12 uses built-in media foundation codecs play formats default midi playback also yet supported using media foundation applications support media foundation include application uses protected media path windows also uses media foundation
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Operating systems
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lambros d. callimahos lambros demetrios callimahos december 16 1910 – october 28 1977 us army cryptologist flute player callimahos born alexandria greek parents family emigrated united states four father journalist main interests school chemistry physics medicine show interest music age fourteen entered high school asbury park callimahos earned degree law rutgers accord fathers wishes attended juilliard music school age nineteen graduated degree 1933 started bottom class became head class second year encouragement teacher arthur lora graduation continued study europe musical debut munich 1935 heralded meisterfloetist also played vienna autumn played all-bach programme munich consisting seven sonatas transcription flute harpsichord b-minor suite two-year tour recitals europe appointed professorship mozarteum two cds performances recorded released april 1937 first united states debut town hall continued tour europe united states joined united states army 1941 hoping interest cryptology could put service taught italian cryptanalysis fort monmouth enrolled japanese course eventually served signals intelligence officer new delhi world war ii assigned army security agency assistant william f. friedman national security agency formed men joined 1950s developed course ca-400 expansion friedman intensive-study course graduates course became members dundee society part course devised zendian problem also revised friedman work produce text military cryptanalytics 1955 established nsa technical journal served technical advisor rest career health problems forced retirement 1976
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Computer security
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miracl security firm miracl formally known certivox london-based web 2.0 security firm develops information security infrastructure service iaas encryption based software service saas solutions enterprises individuals company provides on-demand encryption key management multi-factor authentication cloud specializes elliptical curve cryptography red herring selected miracl finalist 2012 europe top 100 brian spector founded certivox data security specialists 2008 help people protect business individual privacy company opened offices shoreditch 2011 company partnered low-power customer specific standard product cssp provider quicklogic february 2012 efforts jointly develop data security solutions across platforms also february company acquired shamus software creator miracl cryptographic library 2011 certivox received 1.46 million series funding led pentech ventures octopus investments 2012 launched service called privatesky allowing users encrypt messages large files 5gb design offered government businesses individuals one-click security microsoft outlook html5 web browsers however privatesky taken offline company following ripa warrant gchq national technical assistance centre ntac wanted decryption keys customer data certivox launched m-pin strong authentication system july 2013 january 2016 company changed name miracl name acronym multiprecision integer rational arithmetic cryptographic library created dublin city university school computing 1988 company acquired purchase shamus software 2012 ceo shamus software google scholar dr. michael scott also joined miracl chief cryptographer reason given name change reflect “ pivot mission business providing individual products offering complete solutions potential transform industry ”
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Computer security
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bias tee bias tee three-port network used setting dc bias point electronic components without disturbing components bias tee diplexer low-frequency port used set bias high-frequency port passes radio-frequency signals blocks biasing levels combined port connects device sees bias rf called tee 3 ports often arranged shape t. conceptually bias tee viewed ideal capacitor allows ac blocks dc bias ideal inductor blocks ac allows dc although bias tees made simple inductor capacitor wideband bias tees considerably complicated practical components parasitic elements bias tees designed transmission-line environments typically characteristic impedance z 50 ohms 75 ohms impedance capacitor x chosen much less z impedance inductor x chosen much greater z ω angular frequency radians per second f frequency hertz bias tees designed operate range signal frequencies reactances chosen minimal impact lowest frequency wide-range bias tees inductor must large lowest frequency large inductor stray capacitance creates self-resonant frequency high enough frequency stray capacitance presents low-impedance shunt path signal bias tee becomes ineffective practical wide-band bias tees must use circuit topologies avoid shunt path instead one inductor series string inductors addition additional resistors capacitors prevent resonances example picosecond pulse labs model 5580 bias tee works 10 khz 15 ghz consequently simple design would need inductance least 800 μh x j 50 ohms 10 khz inductor must still look like inductor 15 ghz however commercial 820 μh inductor self-resonant frequency 1.8 mhz – four orders magnitude low johnson gives example wideband microstrip bias tee covering 50 khz 1 ghz using four inductors 330 nh 910 nh 18 µh 470 µh series design cribbed commercial bias tee modeled parasitic element values simulated results optimized component selection show advantage additional components johnson provided simulation bias tee used inductors capacitors without q suppression johnson provides simulated actual performance details girardi duplicated improved johnson design points additional construction issues bias tee used insert dc power ac signal power remote antenna amplifiers devices usually positioned receiving end coaxial cable pass dc power external source coaxial cable running powered device bias “ ” consists feed inductor deliver dc connector device side blocking capacitor keep dc passing receiver rf signal connected directly one connector blocking capacitor series internal blocking diode prevents damage bias “ ” reverse supply voltage applied bias tees used variety applications generally used provide rf signal dc power remote device running two separate cables would advantageous biasing often used photodiodes vacuum solid state microchannel plate detectors transistors triodes high frequencies signal leak common power supply rail conversely noise power supply appear signal line examples include power ethernet active antennas low-noise amplifiers converters telephone line plain old telephone service early microphones use bias tee circuit—often gyrator replacing inductor—this enables thin cable 2 conductors send power system device send audio device back system modern microphones often use 3 conductors phantom power circuit similar bias tee circuit several bias tee designs construction horizontal bar based rigid coaxial cable air dielectric radius chosen large possible without allowing higher modes design bias based upon power going remote device seen base station receiver using capacitor rf output terminal effectively creating open circuit dc current incoming rf signal one antenna output dc power front-end bias typically consists bandpass filter low noise amplifier mixer coupled local oscillator one point small slice cut center conductor therefore capacitor formed low frequencies blocked kind capacitor advantage nearly invisible higher frequencies pass frequencies 1 mhz capacitance increased dielectric like npo multiplies capacitance factor 65 thickness capacitor minimal without leading electric breakdown dielectric means avoid peaks electric field means smooth electrodes rounded edges dielectric protruding electrodes doorknob design stack capacitors used every capacitor needs access surface inner conductor hidden behind another capacitor high frequencies wo n't see electric field needs lot time travel dielectric high dielectric constant small coil made fine wire air core mnfezn-core connects inner conductor one sides capacitor port outer conductor leading t. frequencies 1 ghz hit coil side apply equal electric field whole coil therefore higher modes excited within coil inductiveness coil almost current leaks center conductor port frequencies 1 mhz 1 ghz leak port second coil cone shaped core outside outer conductor inside housing avoid interference components cone acts like tapered transmission line transformer starts high impedance lot power reflected rest travel coil leakage low frequency port oscillations capacitor coil composed lc circuit damped dielectric core also small coil 10 ohm resistance damp oscillations avoid ripple transmitted spectrum
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Internet protocols
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tashiro masashi princess ga ippai story hero masashi tashiro rescue four princesses distress one happy ending four unhappy endings used game becoming one first video games multiple endings game successful started appearing frequently getting high prices online auction sites like yahoo 2000 masashi tashiro arrested convicted several times connection voyeurism drug abuse
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Computer architecture
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mongodb inc. mongodb inc. formerly 10gen american software company develops provides commercial support open source database mongodb nosql database stores data json-like documents flexible schemas company first established 2007 10gen based new york city 10gen founded former doubleclick founder cto dwight merriman former doubleclick ceo gilt groupe founder kevin p. ryan former doubleclick engineer shopwiki founder cto eliot horowitz received 81 million venture capital funding flybridge capital partners in-q-tel intel capital new enterprise associates nea red hat sequoia capital union square ventures 10gen originally aimed build platform service architecture based entirely open source components however company unable find existing database platform met principles cloud architecture result company began develop document-oriented database system called mongodb realizing potential software 10gen team decided scrap cloud platform focus maintaining mongodb instead february 2009 10gen released mongodb open source project 10gen opened first west coast office august 2010 offices palo alto reston london dublin barcelona sydney 2012 september 2012 10gen named top software company number 9 overall wall street journal next big thing 2012 april 2013 10gen moved old new york times building office located prince st. august 27 2013 10gen announced would change name mongodb inc. associating closely ultimately became flagship products august 5 2014 dev ittycheria appointed president chief executive officer mongodb inc primary technology product open source nosql database mongodb mongodb inc. employs developers mongodb july 2018 mongodb database downloaded 40 million times 2016 mongodb inc launched mongodb atlas fully managed database service offering atlas available 50 regions amazon web services microsoft azure google cloud platform contains features global clusters automated provisioning upgrades backup restore monitoring 2018 mongodb inc launched mongodb stitch serverless platform stitch provides four core services march 2010 mongodb announced would offer commercial support mongodb mongodb subscription offering includes access mongodb enterprise professional support commercial licensing mongodb 2.4 release mongodb introduced mongodb enterprise part subscription offering mongodb enterprise contains monitoring security features kerberos authentication role-based privileges mongodb 4.0 mongodb enterprise version contains following features ops manager on-premises solution managing mongodb ops manager available part mongodb enterprise advanced subscription features comprehensive support mongodb best sla cloud manager cloud based solution managing mongodb cloud manager automates provisioning aws automation agent installed user mongodb compass allows quickly visualize structure data database perform ad hoc queries – zero knowledge mongodb query language mongodb charts data visualization tool allowing users create graphs charts maps tables json data stored mongodb database mongodb connector bi allows use bi tool choice visualize discover report mongodb data using standard sql queries mongodb world annual developer conference hosted mongodb inc started 2014 mongodb world provides multi-day opportunity communities experts mongodb network learn peers research upcoming trends interesting use cases hear new releases developments mongodb inc. major participants include developers operators cios ctos september 2012 company announced partnership edx offer free mongodb training online 47,000 enrollments first mongodb online education courses 2012 june 2018 1,000,000 course registrations mongodb university addition online education mongodb university offers public training classes well on-site training mongodb inc. known 10gen received funding u.s. government cia-sponsored venture capital arm in-q-tel source concern india
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Distributed computing architecture
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supercollider supercollider environment programming language originally released 1996 james mccartney real-time audio synthesis algorithmic composition since evolving system used developed scientists artists working sound efficient expressive dynamic programming language providing framework acoustic research algorithmic music interactive programming live coding released terms gplv2 2002 supercollider free open-source software starting version 3 supercollider environment split two components server scsynth client sclang components communicate using osc open sound control sc language combines object-oriented structure smalltalk features functional programming languages c-family syntax sc server application supports simple c c++ plugin apis making easy write efficient sound algorithms unit generators combined graphs calculations external control server happens via osc possible use languages applications supercollider sound generation bundled optimised command-line executable named scsynth cases controlled within supercollider programming language used independently audio server following features supernova independent implementation server architecture adds multi-processor support explicit parallel grouping synthesis nodes supercollider programming language dynamically typed garbage-collected single-inheritance object-oriented functional language similar smalltalk syntax similar lisp c programming language architecture strikes balance needs realtime computation flexibility simplicity abstract language like many functional languages implements functions first-class objects may composed functions methods default argument values variable length argument lists called order keyword arguments closures lexical scope lexical dynamic features typical functional languages supported including creation closures via partial application explicit currying tail call optimization list comprehensions coroutines specifics include implicit expansion tuples stateless pattern system constant-time message lookup real-time garbage collection allows large systems efficient handle signal processing flexibly supporting methods reflective conversational literate programming supercollider makes relatively easy find new sound algorithms develop custom software well custom frameworks regards domain specific knowledge general e.g. allows represent properties time pitch variable degrees abstraction copious example implementations specific purposes supercollider language allows users construct cross-platform graphical user interfaces applications standard class library user interface components may extended number available frameworks interactive programming system supports programmatic access rich-text code files may used generate vector graphics algorithmically server controlled using open sound control osc variety applications used control server supercollider language environments see typically used osc-aware systems used pure data third-party clients supercollider server exist including rsc3 scheme client hsc3 based haskell scalacollider based scala overtone based clojure sonic pi distinct development environments mentioned provide interface supercollider programming language instead communicate directly audio server provide approaches facilitating user expression supercollider runs macos linux windows freebsd opensuse operating systems multiple language-editing environments clients used supercollider see also demonstrated supercollider run android ios supercollider code commonly edited used within cross-platform ide supports linux mac windows development environments supercollider support include versatile dynamic programming language supercollider used live coding i.e performances involve performer modifying executing code fly specific kinds proxies serve high level placeholders synthesis objects swapped modified runtime environments allow sharing modification objects process declarations networks various extension libraries support different abstraction access sound objects e.g dewdrop_lib allows live creation modification pseudo-classes -objects
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Programming language topics
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cub linux cub linux computer operating system designed mimic desktop appearance functionality chrome os based ubuntu linux lts 14.04 trusty tahr used openbox window manager tools taken lxde gnome xfce well number utilities cloud-centric operating system heavily focused chromium browser cub linux tagline cub chromium ubuntu cub linux originally called chromixium os developer richjack initially announced project ubuntu user forums september 19 2014 since project released first stable version chromixium 1.0 32 bit live iso april 26 2015 followed service pack address number issues screen tearing slow menu generation july 2015 number updates rolled new release version 1.5 initially 32 bit followed 64 bit release november 2015 point towards end 2015 google owns rights chrome os chromium trademarks requested richjack cease use chromixium mark related websites social media presences january 17 2016 richjack announced chromixium would changing name cub linux immediate effect chromixium name would completely dropped 31 march 2016 towards end 2016 cub linux website mysteriously disappeared github page still open user d4zzy involved cub linux development say sudden end cub killed due private life restrictions one time pick july 19 2017 developer feren os announced would bring ing back cub form phoenix linux page updated since release alpha 2 march 2018 jesse smith distrowatch weekly reviewed chromixium os 1.0
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Computer architecture
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sshfs computing sshfs ssh filesystem filesystem client mount interact directories files located remote server workstation normal ssh connection client interacts remote file system via ssh file transfer protocol sftp network protocol providing file access file transfer file management functionality reliable data stream designed extension secure shell protocol ssh version 2.0 current implementation sshfs using fuse rewrite earlier version rewrite done miklos szeredi also wrote fuse sftp provides secure file transfer secure remote file system sftp clients may transfer files directories related file system may mounted locally using sftp alone using sshfs remote file system may treated way volumes cds dvds usb flash drives shared disks using unix command ls sshfs sometimes list owner file correctly although possible map manually distributed remote file systems multiple users protocols apple filing protocol network file system server message block often used sshfs alternative protocols situations users confident files directories targeted writing another user time advantage sshfs compared network file system protocols given user already ssh access host require additional configuration work opening additional entry ports firewall
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Computer file systems
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fast interrupt request fast interrupt requests fiqs specialized type interrupt request standard technique used computer cpus deal events need processed occur receiving data network card keyboard mouse actions fiqs specific arm cpu architecture supports two types interrupts fiqs fast low latency interrupt handling interrupt requests irqs general interrupts fiq takes priority irq arm system also one fiq source time supported helps reduce interrupt latency interrupt service routine executed directly without determining source interrupt context save required servicing fiq since set banked registers reduces overhead context switching
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Computer architecture
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eye vein verification eye vein verification method biometric authentication applies pattern-recognition techniques video images veins user eyes complex random patterns unique modern hardware software detect differentiate patterns distance eyes veins sclera—the white part eyes—can imaged person glances either side providing four regions patterns one side eye verification employs digital templates patterns templates encoded mathematical statistical algorithms allow confirmation identity proper user rejection anyone else advocates eye vein verification note one technology strengths stability pattern eye blood vessels patterns change age alcohol consumption allergies redness eye veins clear enough reliably imaged cameras smartphones technology works contacts glasses though sunglasses least one version eye vein detection uses infrared illumination part imaging allowing imaging even low-light conditions dr. reza derakhshani university missouri kansas city developed concept using veins whites eyes identification holds several patents technology including 2008 patent concept using blood vessels seen whites eye unique identifier recent research explored using vein patterns iris sclera recognition eye vein verification like methods biometric authentication used range security situations including mobile banking government security healthcare environments eyeverify kansas city kansas company markets eye vein verification system called eyeprint 2012 eyeverify licensed technology developed patented derakhshani derakhshani serves chief science officer eyeverify
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Computer security
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browser exploit browser exploit form malicious code takes advantage flaw vulnerability operating system piece software intent breach browser security alter user browser settings without knowledge malicious code may exploit activex html images java javascript web technologies cause browser run arbitrary code users whose web browsers fallen victim successful browser exploit may find homepage search page and/or favorites changed signs include internet settings options within browser altered access blocked specific functions redirection incorrectly typed url prefixes multiple ways users protect web browsers falling victim browser exploit things include installing firewall software keeping software updated cautious downloading files opening email attachments unknown sources jailbreakme series browser based exploits used jailbreak apple ios mobile operating system uses exploit browser pdf parser execute unauthorised code gain access underlying operating system
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Computer security
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ranish partition manager ranish partition manager freeware hard disk partition editor disk cloning utility boot manager gives high level control creating multi-boot systems available freeware live cd systemrescuecd ultimate boot cd windows version runs ms-dos pc dos dr-dos freedos rpm create bit-identical partition clones see speed rpm runs instantly following aside tools run regularly used operating system rpm one fastest ways partition hard disk restore clone move operating system rpm updated many years unknown whether works dynamic disk large sector drive quirks display problems occur using drives much larger rpm written ranish partition manager used create manual backup primary partition table extended partition table using rpm possible convert logical drives primary partitions rpm done deleting logical drive moving beginning extended partition type 0x0f forward recreating primary partition location logical drive saving changes process reversed convert primary partition logical drive however conversions partition must deviate standard chs alignment logical drives usually start second head head 1 primary partitions usually start beginning cylinder modern operating systems probably would problems reading editing files converted drive software used re-sizing imaging partitions may decide silently correct partition moving beginning partition perhaps conform standard chs alignment conform 1-mib alignment re-sizing would prevent windows xp booting might prevent windows vista booting starting sector moved without updating vista boot files secondly user unaware partition moved may realize old backup partition table obsolete however another possible problem converting primary partitions logical drives unless primary partitions made purpose windows xp disk management known delete nonstandard extended partitions must least 63 sectors primary partition allocate ebr order make conversion reasons may preferable primary partition may converted extended partition start head 1 instead beginning cylinder space beginning cylinder head 1 free space previous partition end end last complete cylinder end earlier cylinder starting primary partitions head 1 instead head 0 another advantage allows bit-identical cloning primary partitions logical drives making completely normal usual logical drives ebrs logical drives beginning cylinder logical drive begins next head logical drive ends cylinder boundary however author tested installing booting operating systems primary partitions beginning head 1 first partition first partition usually begins head 1 cylinder begins master boot record like graphical partition editors gparted sector-precise meaning show numbers sectors cylinders partitions created however things rpm gparted resize partitions data ntfs fat etc format ntfs partitions although rpm able format fat partitions windows xp error partition formatted rpm ranish partition manager gnu parted parted display partitions one chs format sector precise parted show locations ebrs values contain linux information displayed using codice_1 format requires scrutinizing n't indicate errors/warnings color rpm unlike command line tools parted sfdisk rpms text user interface allows user move cursor anywhere partition table select values change parted riskier less efficient use saves every change soon made takes time update certain things rpm create partitions manually using wizard
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Computer file systems
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hero sparta hero sparta action-adventure game developed published spanish studio gameloft iberica ios nintendo ds android playstation portable hd version also released ios android symbian devices versions removed play store game available android devices gameloft official website game follows storyline set ancient greece wherein player controls protagonist throughout multiple landscapes fighting mythical beasts game moderately well received critics game consists eight levels five ds version player controls spartan king wielding sword fighting various mythical beasts player collect different-colored orbs defeating enemies color corresponding different effect green orbs restore health blue restore magical energy red orbs grant experience points used upgrade damage special powers weapons found throughout course game versions game upgrading weapons maximum capacities cause take ultimate form game features real-time events called focus kills occur certain enemies nearly defeated player prompted input series controls tap screen perform finishing blow enemy successful focus kills award player orbs cases player required perform focus kills defeat bosses story centers around spartan king argos awakens beach shortly entire fleet ships wiped violent storm exploring island spirit oracle apparently held captivity pleads argos rescue exchange oracle offers use power return argos homeland game directly compared god war franchise even called shameless god war rip-off sequel hero sparta ii released july 29 2010
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Operating systems
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nagare web framework nagare free open-source web framework developing web applications stackless python nagare uses component model inspired seaside like seaside nagare uses continuations provide framework http connectionless request response cycle n't break normal control flow application allows web applications developed much way desktop applications rapid application development however nagare written python rather smalltalk
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Operating systems
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advanced risc computing advanced risc computing arc specification promulgated defunct consortium computer manufacturers advanced computing environment project setting forth standard mips risc-based computer hardware firmware environment although ace went defunct computer ever manufactured fully complied arc standard arc system widespread legacy windows nt family operating systems use arc conventions naming boot devices sgi uses modified version arc firmware calls arcs systems sgi computers run irix 6.1 later indy octane boot arcs console uses drive naming conventions windows accordingly addition various risc-based computers designed run windows nt used versions arc boot console boot nt include following predicted intel ia-32-based computers would adopt arc console although sgi ever marketed machines arc firmware namely sgi visual workstation series launched 1999 products complying degree arc standard include
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Computer architecture
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presto sql query engine presto high performance distributed sql query engine big data architecture allows users query variety data sources hadoop aws s3 alluxio mysql cassandra kafka mongodb one even query data multiple data sources within single query presto community driven open-source software released apache license presto originally designed developed facebook data analysts run interactive queries large data warehouse apache hadoop presto data analysts facebook relied apache hive running sql analytics multi petabyte data warehouse hive inadequate facebook scale presto invented fill gap run fast queries original development started 2012 deployed facebook later year november 2013 facebook announced release open source 2013 2014 netflix disclosed used presto 10 petabytes data stored amazon simple storage service s3 january 2019 presto software foundation announced foundation not-for-profit organization dedicated advancement presto open source distributed sql query engine development presto continues independently prestodb maintained facebook prestosql maintained presto software foundation cross pollination code presto ’ architecture similar classic database management system using cluster computing mpp visualized one coordinator node working sync multiple worker nodes clients submit sql statements get parsed planned following parallel tasks scheduled workers workers jointly process rows data sources produce results returned client compared original apache hive execution model used hadoop mapreduce mechanism query presto write intermediate results disk resulting significant speed improvement presto written java programming language single presto query combine data multiple sources presto offers connectors data sources including files alluxio hadoop distributed file system amazon s3 mysql postgresql microsoft sql server amazon redshift apache kudu apache phoenix apache kafka apache cassandra apache accumulo mongodb redis unlike hadoop distribution-specific tools cloudera impala presto work flavor hadoop without presto supports separation compute storage may deployed premises cloud
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Distributed computing architecture
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multisite cloud multisite cloud cloud composed several single sites data centers different providers explicitly accessible cloud users multisite cloud environment tasks program workflow scheduled order achieve efficient processing
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Distributed computing architecture
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aloysius cheang aloysius cheang managing director apac cloud security alliance another role standards secretariat overseeing standardization efforts within csa cloud security alliance owning relationships sdos aloysius former member singapore government chief security officer roundtable founder sig^2 2001 also held senior executive positions various consulting companies telco worldwide remit sig^2 rose become de facto security community asia lead formalisation singapore government-backed association information security professionals aisp cheang pro tem chairman 2006–2007 also co-editor iso/iec 27032 guidelines cybersecurity represented singapore iso/iec/jtc 1 sc 27 wg4 previous contribution ss 507 “ business continuity/disaster recovery industry standard ” adopted iso/iec 24762 cheang sits singapore standards committee national infocomm competency framework security sub-committee cheang professional certifications include cisa cissp gcih first microsoft security mvp south asia member microsoft sea mvp hall fame views presented times asia cio asia zdnet computerworld new paper mypaper sin chew daily wen wei po straits times channelnewsasia independent source specialist opinion
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Computer security
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oftp odette file transfer protocol oftp protocol created 1986 used edi electronic data interchange two communications business partners name comes odette organisation organization data exchange teletransmission europe odette file transfer protocol odette-ftp defined 1986 working group four organisation data exchange tele-transmission europe odette address electronic data interchange edi requirements european automotive industry designed spirit open system interconnection osi model utilising network service provided ccitt x.25 recommendation oftp 2 written 2007 data interchange specification secure transfer business documents internet isdn x.25 networks description oftp 1.3 found rfc 2204 whilst oftp 2 defined rfc 5024 oftp 2 work point-to-point indirectly via van value added network single oftp 2 entity make receive calls exchanging files directions means oftp 2 work push pull mode opposed as2 work push mode oftp 2 encrypt digitally sign message data request signed receipts also offers high levels data compression services available using oftp 2 tcp/ip x.25/isdn native x.25 used tcp/ip network internet additional session level security available using oftp 2 tls transport layer security
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Internet protocols
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valerie aurora valerie anita aurora software engineer feminist activist co-founder ada initiative non-profit organization sought increase women participation free culture movement open source technology open source culture aurora also known within linux community advocating new developments filesystems linux including chunkfs union file system birth name val henson changed shortly 2009 choosing middle name computer scientist anita borg 2012 aurora ada initiative co-founder mary gardiner named two influential people computer security sc magazine 2013 o'reilly open source award aurora raised new mexico home-schooled became involved computer programming attended def con 1995 studied computer science mathematics new mexico institute mining technology first became involved file systems worked zfs 2002 sun microsystems later moved ibm worked group theodore ts considered extensions ext2 ext3 linux file systems working intel implemented ext2 dirty bit relative atime along arjan van de ven came idea chunkfs simplifies file system checks dividing file system independent pieces also co-organized first linux file systems workshop order figure spread awareness raise funding file system development 2009 worked red hat file systems developer well part-time science writer linux consultant already activist women open source joined mary gardiner members geek feminism blog develop anti-harassment policies conferences noirin shirley sexually assaulted apachecon 2010 aurora quit job linux kernel developer red hat gardiner founded ada initiative february 2011 organization named ada lovelace worked charles babbage considered world first computer programmer two years later aurora founded double union hackerspace women amelia greenhall liz henry banned 2018 ada initiative shut october 2015 maintaining blog since 2007 aurora written extensively coding experiences women open source included descriptions def con harassment took place 2013 aurora provided comment verge electronic frontier foundation involvement legal defense andrew auernheimer prison hacking previously harassed kathy sierra aurora said another case 're saying 'the cases care ones white men interested ’ less interested protecting women web comment received negatively eff director international freedom expression jillian york another 2013 controversy received commentary aurora donglegate pycon attendee adria richards faced backlash reporting conversation overheard two men sitting near aurora condemned threats sent richards stated anonymous using large numbers computers distorting social pressure asked firing one males appropriate response said n't enough information know two years later aurora praised gender ratio pycon called guido van rossum python community biggest success story women open source interview approved culture website tumblr stated linus torvalds daughter patricia positive role-model
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Operating systems
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information content exchange information content exchange ice xml-based protocol used content syndication via internet using xml sender receiver agreed-upon language communicate using client–server architecture ice defines syndicate/subscribe model comparable binary publish/subscribe protocol standards used corba dcom however ice messages delivered xml typically http connection rather lower-level binary protocol first standard specifically web syndication ice proposed firefly networks vignette january 1998 two companies ceded control specification ice consortium consisted authoring group advisory council ice authoring group included microsoft adobe sun cnet national semiconductor tribune media services ziff davis reuters amongst others limited thirteen companies ice advisory council included nearly hundred members ice submitted world wide web consortium standards body october 26 1998 showcased press event day standard failed benefit open-source implementation w3c xml specifications often received version 1.1 protocol published july 1 2000 version 2.0 featured improved web service support released august 1 2004 versions appeared since vignette demo version ice-capable server named site-to-site february 1998 aiming show protocol could facilitate content exchange websites site-to-site initially scheduled release summer 1998 launched name vignette syndication server february 22 1999 syndication server vignette became primary ice vendor june 1999 vignette invested 14 million leading web syndicator isyndicate adopt vignette storyserver development isyndicate website part deal isydicate committed making content available ice protocol comparable xml specifications include wddx nitf xmlnews newsml prism well cdf rss atom open content syndication ocs twice java implementation ice 2.0 rice ruby implementation ice 1.1 twice rice developed maintained jim menard icecubes original java reference implementation ice 1.1 although actively maintained since december 2000
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Web technology
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gekko microprocessor gekko superscalar out-of-order 32-bit powerpc microprocessor custom-made ibm 2000 nintendo use cpu sixth generation game console nintendo gamecube later triforce arcade board gekko role game system facilitate game scripting artificial intelligence physics collision detection custom graphics lighting effects geometry smooth transformations moving graphics data system project announced 1999 ibm nintendo agreed one billion dollar contract cpu running approximately 400 mhz ibm chose modify existing powerpc 750cxe processor suit nintendo needs tight balanced operation alongside flipper graphics processor customization bus architecture dma compression floating point unit support special set simd instructions cpu made ground work custom lighting geometry effects could burst compressed data directly gpu gekko considered direct ancestor broadway processor also designed manufactured ibm powers wii console
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Computer architecture
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von neumann architecture von neumann architecture—also known von neumann model princeton architecture—is computer architecture based 1945 description mathematician physicist john von neumann others first draft report edvac document describes design architecture electronic digital computer components term von neumann architecture evolved mean stored-program computer instruction fetch data operation occur time share common bus referred von neumann bottleneck often limits performance system design von neumann architecture machine simpler harvard architecture machine—which also stored-program system one dedicated set address data buses reading writing memory another set address data buses fetch instructions stored-program digital computer keeps program instructions data read-write random-access memory ram stored-program computers advancement program-controlled computers 1940s colossus eniac programmed setting switches inserting patch cables route data control signals various functional units vast majority modern computers use memory data program instructions von neumann vs. harvard distinction applies cache architecture main memory split cache architecture earliest computing machines fixed programs simple computers still use design either simplicity training purposes example desk calculator principle fixed program computer basic mathematics run word processor games changing program fixed-program machine requires rewiring restructuring redesigning machine earliest computers much programmed designed particular task reprogramming —when possible all—was laborious process started flowcharts paper notes followed detailed engineering designs often-arduous process physically rewiring rebuilding machine could take three weeks set debug program eniac proposal stored-program computer changed stored-program computer includes design instruction set store memory set instructions program details computation stored-program design also allows self-modifying code one early motivation facility need program increment otherwise modify address portion instructions operators manually early designs became less important index registers indirect addressing became usual features machine architecture another use embed frequently used data instruction stream using immediate addressing self-modifying code largely fallen favor since usually hard understand debug well inefficient modern processor pipelining caching schemes large scale ability treat instructions data makes assemblers compilers linkers loaders automated programming tools possible makes programs write programs possible made sophisticated self-hosting computing ecosystem flourish around von neumann architecture machines high level languages leverage von neumann architecture providing abstract machine-independent way manipulate executable code runtime e.g. lisp using runtime information tune just-in-time compilation e.g languages hosted java virtual machine languages embedded web browsers smaller scale repetitive operations bitblt pixel vertex shaders accelerated general purpose processors just-in-time compilation techniques one use self-modifying code remained popular mathematician alan turing alerted problem mathematical logic lectures max newman university cambridge wrote paper 1936 entitled computable numbers application entscheidungsproblem published proceedings london mathematical society described hypothetical machine called universal computing machine known universal turing machine hypothetical machine infinite store memory today terminology contained instructions data john von neumann became acquainted turing visiting professor cambridge 1935 also turing phd year institute advanced study princeton new jersey 1936 – 1937 whether knew turing paper 1936 time clear 1936 konrad zuse also anticipated two patent applications machine instructions could stored storage used data independently j. presper eckert john mauchly developing eniac moore school electrical engineering university pennsylvania wrote stored-program concept december 1943 von neumann involved manhattan project los alamos national laboratory required huge amounts calculation drew eniac project summer 1944 joined ongoing discussions design stored-program computer edvac part group wrote description titled first draft report edvac based work eckert mauchly unfinished colleague herman goldstine circulated von neumann name consternation eckert mauchly paper read dozens von neumann colleagues america europe influenced next round computer designs jack copeland considers historically inappropriate refer electronic stored-program digital computers 'von neumann machines los alamos colleague stan frankel said von neumann regard turing ideas time first draft report circulated turing producing report entitled proposed electronic calculator described engineering programming detail idea machine called automatic computing engine ace presented executive committee british national physical laboratory february 19 1946 although turing knew wartime experience bletchley park proposed feasible secrecy surrounding colossus subsequently maintained several decades prevented saying various successful implementations ace design produced von neumann turing papers described stored-program computers von neumann earlier paper achieved greater circulation computer architecture outlined became known von neumann architecture 1953 publication faster thought symposium digital computing machines edited b. v. bowden section chapter computers america reads follows machine institute advanced studies princeton 1945 professor j. von neumann working moore school engineering philadelphia e.n.i.a.c built issued behalf group co-workers report logical design digital computers report contained detailed proposal design machine since become known e.d.v.a.c electronic discrete variable automatic computer machine recently completed america von neumann report inspired construction e.d.s.a.c electronic delay-storage automatic calculator cambridge see page 130 1947 burks goldstine von neumann published another report outlined design another type machine parallel machine time would exceedingly fast capable perhaps 20,000 operations per second pointed outstanding problem constructing machine development suitable memory instantaneously accessible contents first suggested using special vacuum tube—called selectron —which princeton laboratories rca invented tubes expensive difficult make von neumann subsequently decided build machine based williams memory machine—completed june 1952 princeton—has become popularly known maniac design machine inspired least half dozen machines built america known affectionately johniacs book first two paragraphs chapter ace read follows automatic computation national physical laboratory one modern digital computers embodies developments improvements technique automatic electronic computing recently demonstrated national physical laboratory teddington designed built small team mathematicians electronics research engineers staff laboratory assisted number production engineers english electric company limited equipment far erected laboratory pilot model much larger installation known automatic computing engine although comparatively small bulk containing 800 thermionic valves judged plates xii xiii xiv extremely rapid versatile calculating machine basic concepts abstract principles computation machine formulated dr. a. m. turing f.r.s. paper read london mathematical society 1936 work machines britain delayed war 1945 however examination problems made national physical laboratory mr. j. r. womersley superintendent mathematics division laboratory joined dr. turing small staff specialists 1947 preliminary planning sufficiently advanced warrant establishment special group already mentioned april 1948 latter became electronics section laboratory charge mr. f. m. colebrook first draft described design used many universities corporations construct computers among various computers illiac ordvac compatible instruction sets date information following chronology difficult put proper order dates first running test program dates first time computer demonstrated completed dates first delivery installation decades 1960s 1970s computers generally became smaller faster led evolutions architecture example memory-mapped i/o lets input output devices treated memory single system bus could used provide modular system lower cost sometimes called streamlining architecture subsequent decades simple microcontrollers would sometimes omit features model lower cost size larger computers added features higher performance shared bus program memory data memory leads von neumann bottleneck limited throughput data transfer rate central processing unit cpu memory compared amount memory single bus access one two classes memory time throughput lower rate cpu work seriously limits effective processing speed cpu required perform minimal processing large amounts data cpu continually forced wait needed data move memory since cpu speed memory size increased much faster throughput bottleneck become problem problem whose severity increases every new generation cpu von neumann bottleneck described john backus 1977 acm turing award lecture according backus surely must less primitive way making big changes store pushing vast numbers words back forth von neumann bottleneck tube literal bottleneck data traffic problem importantly intellectual bottleneck kept us tied word-at-a-time thinking instead encouraging us think terms larger conceptual units task hand thus programming basically planning detailing enormous traffic words von neumann bottleneck much traffic concerns significant data find several known methods mitigating von neumann performance bottleneck example following improve performance problem also sidestepped somewhat using parallel computing using example non-uniform memory access numa architecture—this approach commonly employed supercomputers less clear whether intellectual bottleneck backus criticized changed much since 1977 backus proposed solution major influence modern functional programming object-oriented programming much less geared towards pushing vast numbers words back forth earlier languages like fortran internally still computers spend much time even highly parallel supercomputers 1996 database benchmark study found three four cpu cycles spent waiting memory researchers expect increasing number simultaneous instruction streams multithreading single-chip multiprocessing make bottleneck even worse context multi-core processors additional overhead required maintain cache coherence processors threads aside von neumann bottleneck program modifications quite harmful either accident design simple stored-program computer designs malfunctioning program damage programs operating system possibly leading computer crash memory protection forms access control usually protect accidental malicious program modification
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Computer architecture
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webrtc gateway webrtc gateway connects webrtc established voip technology sip webrtc web real-time communication api definition drafted world wide web consortium w3c supports browser-to-browser applications voice calling video chat messaging without need either internal external plugins enable browsers using different application providers communicate e.g user logged application providers x wants call someone logged application provider so-called webrtc trapezoid used case two providers use widely used voip signalling protocol sip federate however respective browser-based clients signals server using proprietary application protocols built top http websocket component mediates webrtc sip referred webrtc gateway beside connecting different webrtc applications webrtc gateway also enables communication webrtc phone voip even pstn phone thereby webrtc gateway extends scope webrtc applications enables much wider reach usage scenarios usual process webrtc user downloads webrtc javascript application application used communicate another user webrtc gateway would usually contain server user would download webrtc javascript application receiving call user webrtc gateway needs decide whether callee reachable webrtc call translated sip example translate call sip gateway map different layers already number open source commercial solutions available providing webrtc gateway functionality lot required functionality webrtc gateway media handling signalling mapping supported sbc function webrtc gateway often integrated sbcs provided sbc vendors
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Internet protocols
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variable rules analysis linguistics variable rules analysis set statistical analysis methods commonly used sociolinguistics historical linguistics describe patterns variation alternative forms language use also sometimes known varbrul analysis name software package dedicated carrying relevant statistical computations varbrul variable rule method goes back theoretical approach developed sociolinguist william labov late 1960s early 1970s mathematical implementation developed henrietta cedergren david sankoff 1974 variable rules analysis designed provide quantitative model situation speakers alternate different forms meaning stand free variation way probability choice either one form conditioned variety context factors social characteristics situation variation entirely random rule-governed also known structured variation variable rules analysis computes multivariate statistical model basis observed token counts determining factor assigned numerical factor weight describes influences probabilities choice either form done means stepwise logistic regression using maximum likelihood algorithm although necessary computations required variable rules analysis carried help mainstream general-purpose statistics software packages spss often done means specialised software dedicated needs linguists called varbrul originally written david sankoff currently exists freeware implementations mac os microsoft windows title goldvarb x also versions implemented statistical language r therefore available platforms include r-varb rbrul variable rules approaches commonly employed analysis data sociolinguistic research especially studies aim investigate reflexes linguistic change time appear shape structured variation patterns within speech community
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Computational linguistics
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