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7-zip 7-zip free open-source file archiver utility used place groups files within compressed containers known archives developed igor pavlov first released 1999 7-zip uses 7z archive format read write several archive formats program used command-line interface command p7zip graphical user interface also features shell integration 7-zip source code gnu lgpl license unrar code however gnu lgpl unrar restriction states developers permitted use code reverse-engineer rar compression algorithm default 7-zip creates 7z-format archives codice_1 file extension archive contain multiple directories files container format security size reduction achieved using stacked combination filters consist pre-processors compression algorithms encryption filters core 7z compression uses variety algorithms common bzip2 ppmd lzma2 lzma developed pavlov lzma relatively new system making debut part 7z format lzma uses lz-based sliding dictionary 4 gb size backed range coder native 7z file format open modular file names stored unicode 2011 toptenreviews found 7z compression least 17 better zip 7-zip site since 2002 reported compression ratio results dependent upon data used tests usually 7-zip compresses 7z format 30–70 better zip format 7-zip compresses zip format 2–10 better zip-compatible programs 7z file format specification distributed program source code doc subdirectory 7-zip supports number compression non-compression archive formats packing unpacking including zip gzip bzip2 xz tar wim utility also supports unpacking apm arj chm cpio deb flv jar lha/lzh lzma mslz office open xml onepkg rar rpm smzip swf xar z archives cramfs dmg fat hfs iso mbr ntfs squashfs udf vhd disk images 7-zip supports zipx format unpacking support since least version 9.20 released late 2010 7-zip open msi files allowing access meta-files within along main contents microsoft cab lzx compression nsis lzma installer formats opened similarly microsoft executable programs .exes self-extracting archives otherwise contain archived content e.g. setup files may opened archives compressing zip gzip files 7-zip uses deflate encoder may achieve higher compression lower speed common zlib deflate implementation 7-zip deflate encoder implementation available separately part advancecomp suite tools decompression engine rar archives developed using freely available source code unrar program licensing restriction creation rar compressor 7-zip v15.06 later support extraction files rar5 format backup systems use formats supported archiving programs 7-zip e.g. android backups codice_2 format extracted archivers 7-zip 7-zip comes file manager along standard archiver tools file manager toolbar options create archive extract archive test archive detect errors copy move delete files open file properties menu exclusive 7-zip file manager default displays hidden files follow windows explorer policies tabs show name modification time original compressed sizes attributes comments 4dos codice_3 format going one directory root drives removable internal appear going shows list four options 7-zip lzma sdk originally dual-licensed gnu lgpl common public license additional special exception linked binaries december 2 2008 sdk placed igor pavlov public domain two command-line versions provided 7z.exe using external libraries standalone executable 7za.exe containing built-in modules compression/decompression support limited 7z zip gzip bzip2 z tar formats 64-bit version available support large memory maps leading faster compression versions support multi-threading 7za.exe version 7-zip available unix-like operating systems including linux freebsd macos freedos openvms amigaos 4 morphos p7zip project 7-zip supports self-extracting archives including executable installer 7-zip vulnerable arbitrary code execution dll hijacking load run dll named uxtheme.dll folder executable file 7-zip 16.03 release notes say installer sfx modules added protection dll preloading attack versions 7-zip prior 18.05 contain arbitrary code execution vulnerability module extracting files rar archives cve-2018-10115 vulnerability fixed 30 april 2018 snapfiles.com 2012 rated 7-zip 4.5 stars 5 noting interface additional features fairly basic compression ratio outstanding techrepublic 2009 justin james found detailed settings windows file manager integration appreciated called compression-decompression benchmark utility neat though archive dialog settings confound users concluded 7-zip fits nice niche built-in windows capabilities features paid products able handle large variety file formats process 2002 2016 7-zip downloaded 410 million times sourceforge alone software received awards 2007 sourceforge.net granted community choice awards technical design best project 2013 7-zip received tom hardware elite award due superiority speed compression ratio
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Computer file systems
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de-perimeterisation information security de-perimeterisation removal boundary organisation outside world de-perimeterisation protecting organization systems data multiple levels using mixture encryption secure computer protocols secure computer systems data-level authentication rather reliance organization network boundary internet successful implementation de-perimeterised strategy within organization implies perimeter outer security boundary removed metaphorically de-perimeterisation similar historic dismantling city walls allow free flow goods information achieve shift city states nation states creation standing armies city boundaries extended surround multiple cities de-perimeterisation coined jon measham former employee uk ’ royal mail research paper subsequently used jericho forum royal mail founding member claims made removal border include freeing business-to-business transactions reduction cost ability company agile taken furthest extent organisation could operate securely directly internet operating without hardened border frees organizations collaborate utilizing solutions based collaboration oriented architecture framework recently term used context result entropy deliberate activities individuals within organizations usurp perimeters often well-intentioned reasons latest jericho forum paper named collaboration oriented architecture refers trend de-perimeterisation problem problem br traditional electronic boundary corporate ‘ private ’ network internet breaking trend called de-perimeterisation variations term used describe aspects de-perimeterisation
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Computer security
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sparcstation sparcstation sparcserver sparccenter product lines series sparc-based computer workstations servers desktop desk side pedestal rack-based form factor configurations developed sold sun microsystems first sparcstation sparcstation 1 also known sun 4/60 introduced 1989 series popular introduced sun-4c architecture variant sun-4 architecture previously introduced sun 4/260 thanks part delay development modern processors motorola sparcstation series successful across entire industry last model bearing sparcstation name sparcstation 20 workstation series replaced sun ultra series 1995 next sun server generation sun enterprise line introduced 1996 desktop deskside sparcstations sparcservers model number essentially identical systems difference systems designated servers usually headless configured without graphics card monitor sold server rather desktop os license example sparcstation 20 sparcserver 20 almost identical motherboard cpu case design hardware specifications desktop sparcstations sparcservers shipped either pizzabox lunchbox enclosures significant departure earlier sun competing systems time sparcstation 1 2 4 5 10 20 pizzabox machines sparcstation slc elc integrated sun monochrome monitor enclosures sparcstation ipc ipx sparcclassic sparcclassic x sparcstation lx lunchbox machines sparcserver models ending 30 70 housed deskside pedestal enclosures respectively 5-slot 12-slot vmebus chassis models ending 90 sparccenter 2000 came rackmount cabinet enclosures sparcserver 1000 design large rack-mountable desktop unit later versions sparcstation series sparcstation 10 20 could configured multiprocessor systems based mbus high-speed bus systems could accept one two single dual central processing units packaged mbus modules launch sparcserver 600mp series sparcstation/server models also assigned sun 4-series model numbers later models received s-prefix model numbers models listed within category approximately chronological order note configurations supported sun microsystems various third-party processor upgrades available sparcstation/server systems instance 80 mhz weitek power μp sparcstation 2 ipx ross hypersparc mbus modules rated clock speeds 200 mhz mentioned models listed sparcstations also available sparcserver configuration vice versa cs6400 developed outside group working cooperatively rather competitively sun microsystems result although sold cray research “ cray superserver 6400 ” components sun oem part numbers machine documented sun system handbook 1996 cray research bought silicon graphics cs6400 development group sold sun released 64-processor sun ultra enterprise 10000 “ starfire ” following year
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Computer architecture
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co-occurrence network co-occurrence networks generally used provide graphic visualization potential relationships people organizations concepts biological organisms like bacteria entities represented within written material generation visualization co-occurrence networks become practical advent electronically stored text compliant text mining way definition co-occurrence networks collective interconnection terms based paired presence within specified unit text networks generated connecting pairs terms using set criteria defining co-occurrence example terms b may said “ co-occur ” appear particular article another article may contain terms b c. linking b b c creates co-occurrence network three terms rules define co-occurrence within text corpus set according desired criteria example stringent criteria co-occurrence may require pair terms appear sentence co-occurrence networks created given list terms dictionary relation collection texts text corpus co-occurring pairs terms called “ neighbors ” often group “ neighborhoods ” based interconnections individual terms may several neighbors neighborhoods may connect one another least one individual term may remain unconnected individual terms within context text mining symbolically represented text strings real world entity identified term normally several symbolic representations therefore useful consider terms represented one primary symbol several synonymous alternative symbols occurrence individual term established searching known symbolic representations term process augmented nlp natural language processing algorithms interrogate segments text possible alternatives word order spacing hyphenation nlp also used identify sentence structure categorize text strings according grammar example categorizing string text noun based preceding string text known article graphic representation co-occurrence networks allow visualized inferences drawn regarding relationships entities domain represented dictionary terms applied text corpus meaningful visualization normally requires simplifications network example networks may drawn number neighbors connecting term limited criteria limiting neighbors might based absolute number co-occurrences subtle criteria “ probability ” co-occurrence presence intervening descriptive term quantitative aspects underlying structure co-occurrence network might also informative overall number connections entities clustering entities representing sub-domains detecting synonyms etc working applications co-occurrence approach available public internet pubgene example application addresses interests biomedical community presenting networks based co-occurrence genetics related terms appear medline records website namebase example human relationships inferred examining networks constructed co-occurrence personal names newspapers texts ozgur et al. networks information also used facilitate efforts organize focus publicly available information law enforcement intelligence purposes called open source intelligence osint related techniques include co-citation networks well analysis hyperlink content structure internet analysis web sites connected terrorism
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Computational linguistics
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f-1 spirit series top formula one racing game developed published konami released msx japan europe 1987 game engine similar konami road fighter also features konami custom sound chip called konami scc five-channel chip compliments three-channel psg chip msx computer system words sound custom chip brings five voices three voices psg sound chip system great msx1 graphics go one first rom msx sound feature together 3d spinoff f-1 spirit 3d special f-1 spirit way formula-1 extended racing game konami released msx third-person racing game features many different types cars everything starts stock cars moving rally cars formula 3 main goal finish first place formula 1 king class racing six types races stock race rally f3 race f3000 race endurance race finally f1 races 16 tracks initially player race stock rally f3 races player win races accumulate points allow play new races player finish race first place receive nine points gets eight points finishes second etc player finish 10th later score points 16 different tracks f1 cars player wins races able play tracks f1 car category complete game win 16 f1 tracks grand total 21 tracks first races easiest ones cars slow enemies drive well player classify new tracks difficulty increase f1 cars insanely fast need great agility win f1 tracks even though look impossible control first practice master formula 1 cars win races enough always show skills multi player mode difficulty level set race track selected number laps variable field includes ready made custom made cars player select engine tires suspension avoiding slower cars player come lap crucial race bump cars side boards obstacles damage car every track pit lane labeled letters pit fuel repair car top speed decrease engine damaged make lose time every lap pit stop hold key speed car repairs fuel intake slower though fuel consumption determined rpm meter real cars car consumes fuel accelerate f1 tracks first race unless ace driver win f1 race try memorize curve play race several times know brake accelerate unlicensed sega master system port released zemina year f1 스피리트 similar game chequered flag released arcades 1988 special version original f-1 spirit a1 spirit way formula-1 released pack-in panasonic joy handle game controller chief differences features futuristic vehicles instead racing cars different passwords e.g panasonic see ending demo bugfixes full successor game released 1988 msx2+ spec unlike original game uses scaling-based third-person graphics like pole position like focuses specifically f-1 racing addition free run grand prix modes two player battle mode difficulty level set free run number settings number laps variable cars custom made body color car engine tires suspension brakes gear wings modified released three floppy disks game konami ever developed msx2+ spec game featured special cable allowed two msx2+ computers linked via second joystick port cable sold separately name je700 multiplayer link cable also reverse-engineered enthusiasts use games another thing makes game special uses msx-music fm-pac yamaha ym2413 opll sound chip originally sold separately built various models msx2+ msx turbor computers game konami used particular sound chip konami games enhanced music use konami scc sound chip even games distributed floppy disk often accompanied scc rom cartridge like snatcher sd snatcher original music composed goro kin supposedly pseudonym similar product f-1 sensation released family computer 1993 contains many features though battle mode dropped based around 1992 formula one season released north america world circuit series europe spirit f-1 released game boy 1991 top-viewed racing game like original players compete formula 3 formula 3000 formula 1 25 different tracks around world featured playable according class rise class tracks become longer forcing pit stops racers become faster turns change simple low angle corners require slight trajectory elbow corners require skill turn without losing speed later re-released first volume konami gb collection japan europe although renamed konami racing versions collection 2004 unlicensed remake original f-1 spirit released brain games chiefly 2004 retro remakes competition context developed successor team road fighter remake remake retains much gameplay content original changed physics number sound graphical improvements latter make game resemble titles f-1 grand prix online leaderboards ported windows mac os x linux even arm devices binary versions windows os x provided .deb provided ubuntu debian linux flavors oses general source code game available well
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Computer architecture
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organisation-based access control computer security organization-based access control orbac access control model first presented 2003 current approaches access control rest three entities subject action object control access policy specifies subject permission realize action object orbac allows policy designer define security policy independently implementation chosen method fulfill goal introduction abstract level security policy defined organization thus specification security policy completely parameterized organization possible handle simultaneously several security policies associated different organizations model restricted permissions also includes possibility specify prohibitions obligations three abstract entities roles activities views abstract privileges defined abstract privileges concrete privileges derived orbac context sensitive policy could expressed dynamically furthermore orbac owns concepts hierarchy organization role activity view context separation constraints
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Computer security
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ixp1200 ixp1200 network processor fabricated intel corporation processor originally digital equipment corporation dec project development since late 1996 parts dec digital semiconductor business acquired intel 1998 part out-of-court settlement end lawsuits company launched patent infringement processor transferred intel dec design team retained design completed intel samples processor available intel partners since 1999 general sample availability late 1999 processor introduced early 2000 166 200 mhz 232 mhz version introduced later processor later succeeded ixp2000 xscale-based family developed entirely intel processor intended replace general-purpose embedded microprocessors specialized application-specific integrated circuit asic combinations used network routers.the ixp1200 designed mid-range high-end routers high-end models processor could combined others increase capability performance router ixp1200 integrates strongarm sa-1100-derived core six microengines risc microprocessors instruction set optimized network packet workloads strongarm core performed non-real-time functions microengines manipulated network packets processor also integrates static random access memory sram synchronous dynamic random access memory sdram controllers pci interface ix bus interface ixp1200 contains 6.5 million transistors measures 126 mm fabricated 0.28 µm complementary metal–oxide–semiconductor cmos process three levels interconnect packaged 432-ball enhanced ball grid array ebga ixp1200 fabricated dec former hudson massachusetts plant
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Computer architecture
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newtonscript newtonscript prototype-based programming language created write programs newton platform heavily influenced self programming language modified suited needs mobile embedded devices august 3 1993 apple unveiled apple newton messagepad device 640 kb ram 4 mb rom running 20 mhz acorn risc machine main intention behind newton project develop device capable replacing computer portable limited battery memory developers looking programming language capable meeting challenges developers looked c++ language realized lacked flexibility started focusing prototype based languages impressed smalltalk self concurrently apple developing another dynamic programming language called dylan strong candidate newton platform however self dylan dropped consideration nascent stage proper integration instead team headed walter r smith developed new language called newtonscript influenced dynamic language like smalltalk prototype model based like self although newtonscript heavily influenced self differences languages differences arose due three perceived problems self syntax also modified allow text-based programming style opposed self widespread use gui environment programming allowed newton programs developed computer running toolkit programs would compiled downloaded newton device running one advantages newtonscript prototype based inheritance reduced memory usage key consideration 128 kb newton prototype gui object could actually stored rom need copy default data functions working memory unlike class based languages creation object involves memory allocated attributes newtonscripts use prototype inheritance allowed allocated memory fields like _proto _parent instead creating whole new object _proto _parent signifies whether object using prototype parent inheritance example illustrate concept developer might create new button instance button uses default font accessing font slot i.e. property member variable return value actually stored rom button instance ram value font slot prototype inheritance chain followed value found developer changes button font setting font slot new value override prototype override value stored ram newtonscript differential inheritance therefore made efficient use newton expensive flash ram storing bulk default data code pda cheaper much larger rom views objects created newton view system created run-time render views template blueprint views created protos blueprint template view elements newtonscript code libraries frame slot frame dynamic collection slots one element fram called slot slot made name value value type worthwhile note objects newtonscript frames soup entry related collection frames/ data entry individual frame soup frame heap ram allocated dynamically newtonscript base view main view application consisting variables methods used application advantages disadvantages cancellation newton project apple 1998 mainstream developments newtonscript stopped however features used newtonscript would continue inspire programming models languages prototype-based object model self newtonscript used javascript popular visible language use concept far newtonscript also one conceptual ancestors together smalltalk self act1 lisp lua general-purpose programming language called io implements differential inheritance model used newtonscript conserve memory
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Programming language topics
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princh princh danish software company founded 2014 developing cloud printing solutions company headquartered city aarhus denmark based idea sharing economy princh building global network printers via smartphone web app users locate printer nearby get directions go print pay print job solution available native mobile apps android ios well web desktop solutions businesses libraries app connects network printer owners users around world princh supports types printable files company founded 2014 first months headquarters located navitas building harbor aarhus early 2015 company signed investment deal private investor allowing princh move bigger offices expand team company currently based southern part aarhus princh printing service officially launched june 23 2015 present princh solution consists printers multitude locations print shops libraries hotels universities conference centers princh popular printing solution among libraries found denmark sweden germany norway princh app users able locate nearest printer denmark currently around 500 printing locations user printer user chooses document printed opens ios shares android princh point document uploaded princh cloud user selects desired nearby printer entering printer id number scanning qr-code located top printer pays credit card preferred payment option print job carried printer owners get access personal control panel set print prices monitor princh activity business installing princh free printer owners princh gets small fee per print job
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Distributed computing architecture
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distributed object middleware distributed object middleware dom type infrastructure allows remote access remote objects transparently based remote procedure call rpc mechanism dom systems also enable objects different platforms interact example corba examples dom systems include microsoft distributed component object model dcom enterprise javabeans ejb sun microsystems oracle corporation
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Distributed computing architecture
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aegis secureconnect aegis secureconnect simply 'aegis former name network authentication system used ieee 802.1x networks developed meetinghouse data communications inc. system renamed cisco secure services client meetinghouse acquired cisco systems aegis protocol 802.1x supplicant i.e handles authentication wired wireless networks use wpa-psk wpa-radius certificate-based authentication commonly installed along network interface card nic vpn drivers
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Computer security
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arm architecture arm previously advanced risc machine originally acorn risc machine family reduced instruction set computing risc architectures computer processors configured various environments arm holdings develops architecture licenses companies design products implement one architecturesincluding systems-on-chips soc systems-on-modules som incorporate memory interfaces radios etc also designs cores implement instruction set licenses designs number companies incorporate core designs products processors risc architecture typically require fewer transistors complex instruction set computing cisc architecture x86 processors found personal computers improves cost power consumption heat dissipation characteristics desirable light portable battery-powered devicesincluding smartphones laptops tablet computers embedded systems supercomputers consume large amounts electricity arm could also power-efficient solution arm holdings periodically releases updates architecture architecture versions armv3 armv7 support 32-bit address space pre-armv3 chips made arm holdings formed used acorn archimedes 26-bit address space 32-bit arithmetic architectures 32-bit fixed-length instructions thumb version supports variable-length instruction set provides 32- 16-bit instructions improved code density older cores also provide hardware execution java bytecodes newer ones one instruction javascript released 2011 armv8-a architecture added support 64-bit address space 64-bit arithmetic new 32-bit fixed-length instruction set 100 billion arm processors produced arm widely used instruction set architecture instruction set architecture produced largest quantity currently widely used cortex cores older classic cores specialized securcore cores variants available include exclude optional capabilities british computer manufacturer acorn computers first developed acorn risc machine architecture arm 1980s use personal computers first arm-based products coprocessor modules bbc micro series computers successful bbc micro computer acorn computers considered move relatively simple mos technology 6502 processor address business markets like one soon dominated ibm pc launched 1981 acorn business computer abc plan required number second processors made work bbc micro platform processors motorola 68000 national semiconductor 32016 considered unsuitable 6502 powerful enough graphics-based user interface according sophie wilson processors tested time performed 4 mbit/second bandwidth testing available processors finding lacking acorn decided needed new architecture inspired papers berkeley risc project acorn considered designing processor visit western design center phoenix 6502 updated effectively single-person company showed acorn engineers steve furber sophie wilson need massive resources state-of-the-art research development facilities wilson developed instruction set writing simulation processor bbc basic ran bbc micro 6502 second processor convinced acorn engineers right track wilson approached acorn ceo hermann hauser requested resources hauser gave approval assembled small team implement wilson model hardware official acorn risc machine project started october 1983 chose vlsi technology silicon partner source roms custom chips acorn wilson furber led design implemented similar efficiency ethos 6502 key design goal achieving low-latency input/output interrupt handling like 6502 6502 memory access architecture let developers produce fast machines without costly direct memory access dma hardware first samples arm silicon worked properly first received tested 26 april 1985 first arm application second processor bbc micro helped developing simulation software finish development support chips vidc ioc memc sped cad software used arm2 development wilson subsequently rewrote bbc basic arm assembly language in-depth knowledge gained designing instruction set enabled code dense making arm bbc basic extremely good test arm emulator original aim principally arm-based computer achieved 1987 release acorn archimedes 1992 acorn queen award technology arm arm2 featured 32-bit data bus 26-bit address space 27 32-bit registers eight bits program counter register available purposes top six bits available 26-bit address space served status flags bottom two bits available program counter always word-aligned used setting modes address bus extended 32 bits arm6 program code still lie within first 64 mb memory 26-bit compatibility mode due reserved bits status flags arm2 transistor count 30,000 compared motorola six-year-older 68000 model around 40,000 much simplicity came lack microcode represents one-quarter one-third 68000 like cpus day including cache simplicity enabled low power consumption yet better performance intel 80286 successor arm3 produced 4 kb cache improved performance late 1980s apple computer vlsi technology started working acorn newer versions arm core 1990 acorn spun design team new company named advanced risc machines ltd. became arm ltd parent company arm holdings plc floated london stock exchange nasdaq 1998 new apple-arm work would eventually evolve arm6 first released early 1992 apple used arm6-based arm610 basis apple newton pda 1994 acorn used arm610 main central processing unit cpu riscpc computers dec licensed armv4 architecture produced strongarm 233 mhz cpu drew one watt newer versions draw far less work later passed intel part lawsuit settlement intel took opportunity supplement i960 line strongarm intel later developed high performance implementation named xscale since sold marvell transistor count arm core remained essentially throughout changes arm2 30,000 transistors arm6 grew 35,000 2005 98 mobile phones sold used least one arm processor 2010 producers chips based arm architectures reported shipments 6.1 billion arm-based processors representing 95 smartphones 35 digital televisions set-top boxes 10 mobile computers 2011 32-bit arm architecture widely used architecture mobile devices popular 32-bit one embedded systems 2013 10 billion produced arm-based chips found nearly 60 percent world ’ mobile devices arm holdings primary business selling ip cores licensees use create microcontrollers mcus cpus systems-on-chips based cores original design manufacturer combines arm core parts produce complete device typically one built existing semiconductor fabrication plants fabs low cost still deliver substantial performance successful implementation arm7tdmi hundreds millions sold atmel precursor design center arm7tdmi-based embedded system arm architectures used smartphones pdas mobile devices range armv5 armv7-a used low-end midrange devices armv8-a used current high-end devices 2009 manufacturers introduced netbooks based arm architecture cpus direct competition netbooks based intel atom according analyst firm ihs isuppli 2015 arm integrated circuits may 23 laptops arm holdings offers variety licensing terms varying cost deliverables arm holdings provides licensees integratable hardware description arm core well complete software development toolset compiler debugger software development kit right sell manufactured silicon containing arm cpu soc packages integrating arm core designs include nvidia tegra first three generations csr plc quatro family st-ericsson nova novathor silicon labs precision32 mcu texas instruments omap products samsung hummingbird exynos products apple a4 a5 a5x freescale i.mx fabless licensees wish integrate arm core chip design usually interested acquiring ready-to-manufacture verified semiconductor intellectual property core customers arm holdings delivers gate netlist description chosen arm core along abstracted simulation model test programs aid design integration verification ambitious customers including integrated device manufacturers idm foundry operators choose acquire processor ip synthesizable rtl verilog form synthesizable rtl customer ability perform architectural level optimisations extensions allows designer achieve exotic design goals otherwise possible unmodified netlist high clock speed low power consumption instruction set extensions etc. arm holdings grant licensee right resell arm architecture licensees may freely sell manufactured product chip devices evaluation boards complete systems merchant foundries special case allowed sell finished silicon containing arm cores generally hold right re-manufacture arm cores customers arm holdings prices ip based perceived value lower performing arm cores typically lower licence costs higher performing cores implementation terms synthesizable core costs hard macro blackbox core complicating price matters merchant foundry holds arm licence samsung fujitsu offer fab customers reduced licensing costs exchange acquiring arm core foundry in-house design services customer reduce eliminate payment arm upfront licence fee compared dedicated semiconductor foundries tsmc umc without in-house design services fujitsu/samsung charge two- three-times per manufactured wafer low mid volume applications design service foundry offers lower overall pricing subsidisation licence fee high volume mass-produced parts long term cost reduction achievable lower wafer pricing reduces impact arm nre non-recurring engineering costs making dedicated foundry better choice companies designed chips arm cores include amazon.com annapurna labs subsidiary analog devices apple appliedmicro macom technology solutions atmel broadcom cypress semiconductor freescale semiconductor nxp semiconductors huawei maxim integrated nvidia nxp qualcomm renesas samsung electronics st microelectronics texas instruments xilinx february 2016 arm announced built arm cortex technology licence often shortened built cortex boc licence licence allows companies partner arm make modifications arm cortex designs design modifications shared companies semi-custom core designs also brand freedom example kryo 280 companies current licensees built arm cortex technology include qualcomm companies also obtain arm architectural licence designing cpu cores using arm instruction sets cores must comply fully arm architecture companies designed cores implement arm architecture include apple appliedmicro broadcom cavium marvell nvidia qualcomm samsung electronics arm holdings provides list vendors implement arm cores design application specific standard products assp microprocessor microcontrollers arm cores used number products particularly pdas smartphones computing examples microsoft first generation surface surface 2 apple ipads asus eee pad transformer tablet computers several chromebook laptops others include apple iphone smartphone ipod portable media player canon powershot digital cameras nintendo switch hybrid 3ds handheld game consoles tomtom turn-by-turn navigation systems 2005 arm holdings took part development manchester university computer spinnaker used arm cores simulate human brain arm chips also used raspberry pi beagleboard beaglebone pandaboard single-board computers small inexpensive consume little power 32-bit arm architecture armv7-a implementing aarch32 see section armv8 widely used architecture mobile devices since 1995 arm architecture reference manual primary source documentation arm processor architecture instruction set distinguishing interfaces arm processors required support instruction semantics implementation details may vary architecture evolved time version seven architecture armv7 defines three architecture profiles although architecture profiles first defined armv7 arm subsequently defined armv6-m architecture used cortex m0/m0+/m1 subset armv7-m profile fewer instructions except m-profile 32-bit arm architecture specifies several cpu modes depending implemented architecture features moment time cpu one mode switch modes due external events interrupts programmatically original subsequent arm implementation hardwired without microcode like much simpler 8-bit 6502 processor used prior acorn microcomputers 32-bit arm architecture 64-bit architecture part includes following risc features compensate simpler design compared processors like intel 80286 motorola 68020 additional design features used arm includes integer arithmetic operations add subtract multiply versions architecture also support divide operations arm supports 32-bit × 32-bit multiplies either 32-bit result 64-bit result though cortex-m0 m0+ m1 cores n't support 64-bit results arm cores also support 16-bit × 16-bit 32-bit × 16-bit multiplies divide instructions included following arm architectures registers r0 r7 across cpu modes never banked registers r8 r12 across cpu modes except fiq mode fiq mode distinct r8 r12 registers r13 r14 banked across privileged cpu modes except system mode mode entered exception r13 r14 registers generally contain stack pointer return address function calls respectively aliases current program status register cpsr following 32 bits almost every arm instruction conditional execution feature called predication implemented 4-bit condition code selector predicate allow unconditional execution one four-bit codes causes instruction always executed cpu architectures condition codes branch instructions though predicate takes four 32 bits instruction code thus cuts significantly encoding bits available displacements memory access instructions avoids branch instructions generating code small codice_1 statements apart eliminating branch instructions preserves fetch/decode/execute pipeline cost one cycle per skipped instruction standard example conditional execution subtraction-based euclidean algorithm c programming language loop arm assembly loop effectively transformed coded avoids branches around codice_2 codice_3 clauses codice_4 codice_5 equal neither codice_6 instructions executed eliminating need conditional branch implement codice_7 check top loop example codice_8 less equal used one ways thumb code provides dense encoding remove four-bit selector non-branch instructions another feature instruction set ability fold shifts rotates data processing arithmetic logical register-register move instructions example c statement could rendered single-word single-cycle instruction results typical arm program denser expected fewer memory accesses thus pipeline used efficiently arm processor also features rarely seen risc architectures pc-relative addressing indeed 32-bit arm pc one 16 registers pre- post-increment addressing modes arm instruction set increased time early arm processors arm7tdmi example instruction store two-byte quantity arm7 earlier implementations three-stage pipeline stages fetch decode execute higher-performance designs arm9 deeper pipelines cortex-a8 thirteen stages additional implementation changes higher performance include faster adder extensive branch prediction logic difference arm7di arm7dmi cores example improved multiplier hence added arm architecture pre-armv8 provides non-intrusive way extending instruction set using coprocessors addressed using mcr mrc mrrc mcrr similar instructions coprocessor space divided logically 16 coprocessors numbers 0 15 coprocessor 15 cp15 reserved typical control functions like managing caches mmu operation processors one arm-based machines peripheral devices usually attached processor mapping physical registers arm memory space coprocessor space connecting another device bus turn attaches processor coprocessor accesses lower latency peripherals—for example xscale interrupt controller—are accessible ways memory coprocessors cases chip designers integrate hardware using coprocessor mechanism example image processing engine might small arm7tdmi core combined coprocessor specialised operations support specific set hdtv transcoding primitives modern arm processors include hardware debugging facilities allowing software debuggers perform operations halting stepping breakpointing code starting reset facilities built using jtag support though newer cores optionally support arm two-wire swd protocol arm7tdmi cores represented jtag debug support represented presence embeddedice debug module arm7 arm9 core generations embeddedice jtag de facto debug standard though architecturally guaranteed armv7 architecture defines basic debug facilities architectural level include breakpoints watchpoints instruction execution debug mode similar facilities also available embeddedice halt mode monitor mode debugging supported actual transport mechanism used access debug facilities architecturally specified implementations generally include jtag support separate arm coresight debug architecture architecturally required armv7 processors improve arm architecture digital signal processing multimedia applications dsp instructions added set signified e name armv5te armv5tej architectures e-variants also imply new instructions common digital signal processor dsp architectures include variations signed multiply–accumulate saturated add subtract count leading zeros introduced armv6 architecture precursor advanced simd also known neon jazelle dbx direct bytecode execution technique allows java bytecode executed directly arm architecture third execution state instruction set alongside existing arm thumb-mode support state signified j armv5tej architecture arm9ej-s arm7ej-s core names support state required starting armv6 except armv7-m profile though newer cores include trivial implementation provides hardware acceleration improve compiled code-density processors since arm7tdmi released 1994 featured thumb instruction set state tdmi indicates thumb feature state processor executes thumb instruction set compact 16-bit encoding subset arm instruction set thumb instructions directly mapped normal arm instructions space-saving comes making instruction operands implicit limiting number possibilities compared arm instructions executed arm instruction set state thumb 16-bit opcodes less functionality example branches conditional many opcodes restricted accessing half cpu general-purpose registers shorter opcodes give improved code density overall even though operations require extra instructions situations memory port bus width constrained less 32 bits shorter thumb opcodes allow increased performance compared 32-bit arm code less program code may need loaded processor constrained memory bandwidth unlike processor architectures variable length 16- 32-bit instructions cray-1 hitachi superh arm thumb instruction sets exist independently embedded hardware game boy advance typically small amount ram accessible full 32-bit datapath majority accessed via 16-bit narrower secondary datapath situation usually makes sense compile thumb code hand-optimise cpu-intensive sections using full 32-bit arm instructions placing wider instructions 32-bit bus accessible memory first processor thumb instruction decoder arm7tdmi arm9 later families including xscale included thumb instruction decoder includes instructions adopted hitachi superh 1992 licensed arm arm smallest processor families cortex m0 m1 implement 16-bit thumb instruction set maximum performance lowest cost applications thumb-2 technology introduced arm1156 core announced 2003 thumb-2 extends limited 16-bit instruction set thumb additional 32-bit instructions give instruction set breadth thus producing variable-length instruction set stated aim thumb-2 achieve code density similar thumb performance similar arm instruction set 32-bit memory thumb-2 extends thumb instruction set bit-field manipulation table branches conditional execution time arm instruction set extended maintain equivalent functionality instruction sets new unified assembly language ual supports generation either thumb arm instructions source code versions thumb seen armv7 processors essentially capable arm code including ability write interrupt handlers requires bit care use new if-then instruction permits four successive instructions execute based tested condition inverse compiling arm code ignored compiling thumb generates actual instruction example armv7 chips support thumb instruction set chips cortex-a series cortex-r series arm11 series support arm instruction set state thumb instruction set state chips cortex-m series support thumb instruction set thumbee erroneously called thumb-2ee arm documentation marketed jazelle rct runtime compilation target announced 2005 first appearing cortex-a8 processor thumbee fourth instruction set state making small changes thumb-2 extended instruction set changes make instruction set particularly suited code generated runtime e.g jit compilation managed execution environments thumbee target languages java c perl python allows jit compilers output smaller compiled code without impacting performance new features provided thumbee include automatic null pointer checks every load store instruction instruction perform array bounds check special instructions call handler addition utilises thumb-2 technology thumbee provides access registers r8-r15 jazelle/dbx java vm state held handlers small sections frequently called code commonly used implement high level languages allocating memory new object changes come repurposing handful opcodes knowing core new thumbee state 23 november 2011 arm holdings deprecated use thumbee instruction set armv8 removes support thumbee vfp vector floating point technology fpu floating-point unit coprocessor extension arm architecture implemented differently armv8 – coprocessors defined provides low-cost single-precision double-precision floating-point computation fully compliant ansi/ieee std 754-1985 standard binary floating-point arithmetic vfp provides floating-point computation suitable wide spectrum applications pdas smartphones voice compression decompression three-dimensional graphics digital audio printers set-top boxes automotive applications vfp architecture intended support execution short vector mode instructions operated vector element sequentially thus offer performance true single instruction multiple data simd vector parallelism vector mode therefore removed shortly introduction replaced much powerful neon advanced simd unit devices arm cortex-a8 cut-down vfplite module instead full vfp module require roughly ten times clock cycles per float operation pre-armv8 architecture implemented floating-point/simd coprocessor interface floating-point and/or simd units found arm-based processors using coprocessor interface include fpa fpe iwmmxt implemented software trapping could implemented hardware provide functionality vfp opcode-compatible debian gnu/linux derivatives ubuntu armhf arm hard float refers armv7 architecture including additional vfp3-d16 floating-point hardware extension thumb-2 software packages cross-compiler tools use armhf vs. arm/armel suffixes differentiate advanced simd extension aka neon mpe media processing engine combined 64- 128-bit simd instruction set provides standardized acceleration media signal processing applications neon included cortex-a8 devices optional cortex-a9 devices neon execute mp3 audio decoding cpus running 10 mhz run gsm adaptive multi-rate amr speech codec 13 mhz features comprehensive instruction set separate register files independent execution hardware neon supports 8- 16- 32- 64-bit integer single-precision 32-bit floating-point data simd operations handling audio video processing well graphics gaming processing neon simd supports 16 operations time neon hardware shares floating-point registers used vfp devices arm cortex-a8 cortex-a9 support 128-bit vectors execute 64 bits time whereas newer cortex-a15 devices execute 128 bits time projectne10 arm first open-source project inception acquired older project known mbed tls ne10 library set common useful functions written neon c compatibility library created allow developers use neon optimisations without learning neon also serves set highly optimised neon intrinsic assembly code examples common dsp arithmetic image processing routines source code available github security extensions marketed trustzone technology armv6kz later application profile architectures provides low-cost alternative adding another dedicated security core soc providing two virtual processors backed hardware based access control lets application core switch two states referred worlds reduce confusion names capability domains order prevent information leaking trusted world less trusted world world switch generally orthogonal capabilities processor thus world operate independently using core memory peripherals made aware operating world core may use provide access control secrets code device typically rich operating system run less trusted world smaller security-specialized code trusted world aiming reduce attack surface typical applications include drm functionality controlling use media arm-based devices preventing unapproved use device practice since specific implementation details proprietary trustzone implementations publicly disclosed review unclear level assurance provided given threat model immune attack open virtualization open source implementation trusted world architecture trustzone amd licensed incorporated trustzone technology secure processor technology enabled products amd apus include cortex-a5 processor handling secure processing fact cortex-a5 trustzone core included earlier amd products enabled due time constraints samsung knox uses trustzone purposes detecting modifications kernel security extension marketed trustzone armv8-m technology introduced armv8-m architecture armv6 arm architecture supports no-execute page protection referred xn execute never large physical address extension lpae extends physical address size 32 bits 40 bits added armv7-a architecture 2011 physical address size larger 44 bits cortex-a75 cortex-a65ae armv8-r armv8-m sub-architectures announced armv8-a sub-architecture share features armv8-a n't include 64-bit aarch64 instructions announced october 2011 armv8-a often called armv8 armv8-r also available represents fundamental change arm architecture adds optional 64-bit architecture e.g cortex-a32 32-bit armv8-a cpu armv8-a cpus support 64-bit unlike armv8-r named aarch64 associated new a64 instruction set aarch64 provides user-space compatibility armv7-a 32-bit architecture therein referred aarch32 old 32-bit instruction set named a32 thumb instruction set referred t32 64-bit counterpart armv8-a allows 32-bit applications executed 64-bit os 32-bit os control 64-bit hypervisor arm announced cortex-a53 cortex-a57 cores 30 october 2012 apple first release armv8-a compatible core apple a7 consumer product iphone 5s appliedmicro using fpga first demo armv8-a first armv8-a soc samsung exynos 5433 used galaxy note 4 features two clusters four cortex-a57 cortex-a53 cores big.little configuration run aarch32 mode aarch32 aarch64 armv8-a makes vfpv3/v4 advanced simd neon standard also adds cryptography instructions supporting aes sha-1/sha-256 finite field arithmetic aarch64 introduced armv8-a included subsequent versions armv8-a aarch64 included armv8-r armv8-m 32-bit architectures december 2014 armv8.1-a update incremental benefits v8.0 announced enhancements fell two categories changes instruction set changes exception model memory translation instruction set enhancements included following enhancements exception model memory translation system included following january 2016 armv8.2-a announced enhancements fell four categories scalable vector extension sve new extension armv8 allowing implementation choices vector lengths scale 128 2048 bits complementary extension replace neon 512-bit variant already implemented supercomputer based arm cpu prototype sve variant aims world highest-performing supercomputer goal beginning full operations around 2021 see arm holdings supercomputers e.g crays fujitsus sve optional extension armv8.2-a architecture newer supported gcc 8 compiler october 2016 armv8.3-a announced enhancements fell six categories armv8.3-a architecture supported least gcc 7 compiler armv8.4-a adds e.g sha3 sha512 sm3 sm4 crypto extensions improved virtualization support memory partitioning monitoring mpam capabilities new secure el2 state activity monitors dot product sdot udot instructions armv8.5-a adds e.g memory tagging extension mte branch target indicators bti reduce ability attacker execute arbitrary code random number generator instructions – providing deterministic true random numbers conforming various national international standards august 2 2019 google announced android would adopt memory tagging extension mte 2019 arm announced scalable vector extension 2 sve2 transactional memory extension tme sve2 builds sve scalable vectorization increased fine-grain data level parallelism dlp allow work done per instruction sve2 aims bring benefits wider range software including dsp multimedia simd code currently use neon llvm/clang 9.0 gcc 10.0 development codes updated support sve2 tme brings support hardware transactional memory htm hardware lock elision tle tme aims bring scalable concurrency increase coarse-grain thread level parallelism tlp allow work done per thread llvm/clang 9.0 gcc 10.0 development codes updated support tme platform security architecture psa architecture-agnostic security framework evaluation scheme intended help secure internet things iot devices built system-on-a-chip soc processors introduced arm 2017 annual techcon event first used arm cortex-m processor cores intended microcontroller use psa includes freely available threat models security analyses demonstrate process deciding security features common iot products psa also provides freely downloadable application programming interface api packages architectural specifications open-source firmware implementations related test suites psa certified offers multi-level security evaluation scheme chip vendors os providers iot device makers first 32-bit arm-based personal computer acorn archimedes ran interim operating system called arthur evolved risc os used later arm-based systems acorn vendors acorn machines also unix port called risc ix neither confused risc/os contemporary unix variant mips architecture 32-bit arm architecture supported large number embedded real-time operating systems including 32-bit arm architecture primary hardware environment mobile device operating systems previously discontinued 32-bit arm architecture supported risc os multiple unix-like operating systems including windows applications recompiled arm linked winelib wine project run 32-bit 64-bit arm linux freebsd compatible enough operating systems x86 binaries e.g specially compiled arm demonstrated arm using qemu wine linux work full speed capability winelib
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Computer architecture
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free project free project formed 1999 group massachusetts institute technology students aim develop secure decentralized system data storage group work led collaboration united states naval research laboratory develop tor funded darpa project early work focused anonymous storage system free designed ensure privacy security readers publishers contrasts free anonymous publishing services emphasize persistence rather accessibility free distributed peer-to-peer system designed create servnet consisting servnet nodes hold fragments shares documents divided using rabin information dispersal algorithm publisher file contents determined one piece shares stored servnet along unique public key recover recreate file client broadcasts public key find fragments sent client along anonymous routes greater security free periodically moves location shares nodes function similar freenet greater focus persistence ensure unpopular files disappear mechanisms enable persistence however also cause problems inefficiency referral- recommendation-based metatrust reputation system built servnet attempts ensure reciprocity information value holding node operators accountable although nodes remain pseudonymous communication facilitated operators anonymous email tor developed us naval research laboratory free project secure government communications initial funding us office naval research darpa tor deployed 2003 third generation deployed onion routing designs 2005 electronic frontier foundation provided additional funding free project 2006 tor project incorporated non-profit organization
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Computer security
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multi-party authorization multi-party authorization mpa process protect telecommunications network data center industrial control system undesirable acts malicious insider inexperienced technician acting alone mpa requires second authorized user approve action allowed take place pro-actively protects data systems undesirable act existing methods protect data systems malicious insider include auditing job rotation separation duties auditing reactive method meant discover fact job rotation separation duties limiting techniques meant minimize prolonged access sensitive data systems order limit undesirable acts contrast mpa pro-active solution advantage mpa methods protect undesirable acts malicious insider inexperienced operator mpa pro-active prevents data systems compromise single entity acting alone mpa prevents initial undesirable act rather dealing breach compromise fact multi-party authorization technology secure vulnerable sensitive activities data sources attack compromised insider acting alone somewhat analogous weapons systems require two individuals turn two different keys order enable system one person alone another example consider access lock box bank access requires multiple parties one lock box owner another bank official individuals act together access lock box neither could alone mpa like manner ensures second set eyes reviews approves activity involving critical sensitive data systems action takes place multi-party authorization suitable wide variety applications mpa implemented protect type sensitive data electronic form activity within network infrastructure computerized control system electronic health record example data record could protected mpa multi-party authorization provides pro-active protection undesirable acts inexperienced technician malicious insider us patent 7,519,826 issued april 14 2009 near real time multi-party task authorization access control businessedge nov 25 2009 protecting malicious insider multi party authorization
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Computer security
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distributed social network distributed social network federated social network internet social networking service decentralized distributed across distinct providers something like email social networks fediverse consists multiple social websites users site communicate users involved sites societal perspective one may compare concept social media public utility social website participating distributed social network interoperable sites federation communication among social websites technically conducted social networking protocols software used distributed social networking generally portable easily adopted various website platforms distributed social networks contrast social network aggregation services used manage accounts activities across multiple discrete social networks social networking service providers used term broadly describe provider-specific services distributable across different websites typically added widgets plug-ins add-ons social network functionality implemented users websites distributed social network projects generally develop software protocols software generally free open source protocols generally open free open standards oauth authorization openid authentication ostatus federation activitypub federation protocol xrd metadata discovery portable contacts protocol wave federation protocol extensible messaging presence protocol xmpp aka jabber opensocial widget apis microformats like xfn hcard atom web feeds—increasingly referred together open stack—are often cited enabling technologies distributed social networking electronic frontier foundation eff u.s. legal defense organization advocacy group civil liberties internet endorses distributed social network model one plausibly return control choice hands internet user allow persons living restrictive regimes conduct activism social networking sites also choice services providers may better equipped protect security anonymity world wide web consortium w3c main international standards organization world wide web launched new social activity july 2014 develop standards social web application interoperability
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Distributed computing architecture
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evil twin wireless networks evil twin fraudulent wi-fi access point appears legitimate set eavesdrop wireless communications evil twin wireless lan equivalent phishing scam type attack may used steal passwords unsuspecting users either monitoring connections phishing involves setting fraudulent web site luring people attacker snoops internet traffic using bogus wireless access point unwitting web users may invited log attacker server prompting enter sensitive information usernames passwords often users unaware duped well incident occurred users log unsecured non-https bank e-mail accounts attacker intercepts transaction since sent equipment attacker also able connect networks associated users credentials fake access points set configuring wireless card act access point known hostap hard trace since shut instantly counterfeit access point may given ssid bssid nearby wi-fi network evil twin configured pass internet traffic legitimate access point monitoring victim connection simply say system temporarily unavailable obtaining username password
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Computer security
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daniel g. bobrow daniel gureasko bobrow 29 november 1935 – 20 march 2017 american computer scientist created oft-cited artificial intelligence program student earned phd. worked bbn technologies bbn research fellow intelligent systems laboratory palo alto research center born new york city earned bs rpi 1957 sm harvard 1958 phd mathematics mit supervision marvin minsky 1964 bbn developer tenex bobrow president american association artificial intelligence aaai chair cognitive science society editor-in-chief journal artificial intelligence shared 1992 acm software systems award work interlisp acm fellow aaai fellow
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Programming language topics
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chromebook chromebook laptop tablet running linux-based chrome os operating system devices primarily used perform variety tasks using google chrome browser applications data residing cloud rather machine chromebooks released since late 2017 also run android apps chromebooks run linux apps first chromebooks sale acer inc. samsung began shipping june 15 2011 addition laptop models desktop version called chromebox introduced may 2012 all-in-one device called chromebase introduced january 2014 lg electronics october 2012 simon phipps writing infoworld said chromebook line probably successful linux desktop/laptop computer 've seen date january november 2013 1.76 million chromebooks sold us business-to-business channels march 2018 chromebooks made 60 computers purchased schools usa april 2017 electronic frontier foundation accused google using chromebooks collect data mine school children personal information including internet searches without parents consent two years eff filed federal complaint company first chromebooks sale acer inc. samsung announced google i/o conference may 2011 began shipping june 15 2011 lenovo hewlett packard google entered market early 2013 december 2013 samsung launched samsung chromebook specifically indian market employed company exynos 5 dual core processor critical reaction device initially skeptical reviewers new york times technology columnist david pogue unfavorably comparing value proposition chromebooks fully featured laptops running microsoft windows operating system complaint dissipated later reviews machines acer samsung priced lower february 2013 google announced began shipping chromebook pixel higher-spec machine high-end price tag january 2015 acer announced first big screen chromebook acer chromebook 15 fhd 15.6-inch display besides laptops devices run chrome os well desktop version called chromebox introduced may 2012 samsung chromebase all-in-one device introduced january 2014 lg electronics march 2018 acer google announced first chromebook tablet chromebook tab 10 device expected compete lower-priced apple ipad tablet education market tab 10 display—9.7-inch 2048 x 1536 resolution—was ipad device included stylus neither device included keyboard may 2016 google announced would make android apps available chromebooks via google play application distribution platform time google play access scheduled asus chromebook flip acer chromebook r 11 recent chromebook pixel chromebooks slated time partnering google samsung released chromebook plus chromebook pro early 2017 first chromebooks come play store pre-installed february 2017 review verge reported plus arm processor handled android apps much better intel-based pro said android apps chrome os still beta much unfinished experience number chrome os systems supporting android apps either stable beta channel increasing may 2018 google announced would make linux desktop apps available chromebooks via virtual machine code-named crostini initial hardware partners chromebook development included acer adobe asus freescale hewlett-packard later hp inc. lenovo qualcomm texas instruments toshiba intel samsung dell chromebooks ship google chrome os operating system uses linux kernel google chrome web-browser integrated media-player enabling developer mode allows installation linux distributions chromebooks crouton script allows installation linux distributions chrome os running operating systems simultaneously chromebooks include seabios turned install boot linux distributions directly limited offline capability fast boot-time chromebooks primarily designed use connected internet signed google account instead installing traditional applications word processing instant messaging users add web apps chrome web store google claims multi-layer security architecture eliminates need anti-virus software support many usb devices cameras mice external keyboards flash drives included utilizing feature similar plug-and-play operating systems like prototype cr-48 chromebooks specialized keyboard complete buttons opening controlling multiple browser-windows well web search button replaces caps lock key caps lock activated pressing alt+search analysis samsung series 5 components ifixit june 2011 estimated total cost 334.32 representing us 322.12 materials us 12.20 labor initial retail price us 499.99 also pays retail margins shipping marketing research development profit margins chromebooks quite thin requiring large production run make profit chromebooks designed used connected internet users able access google applications gmail google calendar google keep google drive offline mode chromebooks also come built-in local music-player photo editor pdf- microsoft office document-viewer functional without internet access apps offline support include amazon cloud reader new york times app angry birds google play video content available offline using extension chrome browser chromebooks except first three boot help coreboot fast-booting bios integration android chrome announced 2016 anticipated drive design form factor future chromebooks including expected first chrome os tablet first two commercially available chromebooks samsung series 5 acer ac700 unveiled may 11 2011 google i/o developer conference begin selling online channels including amazon best buy united states united kingdom france germany netherlands italy spain starting june 15 2011 however acer ac700 available early july first machines sold 349 499 depending model 3g option google also offered monthly payment scheme business education customers 28 20 per user per month respectively three-year contract including replacements upgrades verizon offers models equipped 3g/4g lte connectivity 100–200 mb free wireless data per month two years google early marketing efforts relied primarily hands-on experience giving away samsung machines 10 cr-48 pilot program participants along title chromebook guru lending chromebooks passengers virgin america flights end september 2011 google launched chrome zone store within store inside currys pc world superstore london store google-style look feel splashes color around retail store front concept later changed broader in-store google shop expanded beyond pc world tottenham court road addition marketing strategies google chrome created several chromebook minis demonstrate ease use simplicity devices comical manner example question back chromebook asked implied refer data backup instead shows two hands pushing chromebook back end table followed statement n't back chromebook showing data stored web article published zdnet june 2011 entitled five chromebook concerns businesses steven j. vaughan-nichols faulted devices lack virtual private network capability supporting wi-fi security methods particular wi-fi protected access ii wpa2 enterprise extensible authentication protocol-transport layer security eap-tls cisco lightweight extensible authentication protocol leap also noted file manager work need use undocumented crosh shell accomplish basic tasks setting secure shell ssh network connection well serious deficiencies documentation one first customer reviews city orlando florida reported initial testing 600 chromebooks part broader study related accessing virtual desktops early indications show potential value reducing support costs end users indicated chromebook easy travel starts quickly one stated need stay connected emergencies take chrome traveling business would still take laptop orlando plan continue use chromebooks november 21 2011 google announced price reductions chromebooks since wi-fi-only samsung series 5 reduced 349 3g samsung series 5 reduced 449 acer ac700 reduced 299 updated series 5 550 chromebox first chrome os desktop machines released samsung may 2012 two lowest cost chromebooks emerged later fall 249 samsung series 3 199 acer c7 following february google introduced costly machine chromebook pixel starting price 1299 models released may 2012 include 100 gb–1.09 tb google drive cloud storage 12 gogo wifi passes january 2013 acer chromebook sales driven heavy internet users educational institutions platform represented 5-10 percent company us shipments according acer president jim wong called numbers sustainable contrasting low windows 8 sales blamed slump market wong said company would consider marketing chromebooks developed countries well corporations noted although chrome os free license hardware vendors required greater marketing expenditure windows offsetting licensing savings first 11 months 2013 1.76 million chromebooks sold united states representing 21 us commercial business-to-business laptop market period 2012 chromebooks sold 400,000 units negligible market share january 2015 silviu stahie noted softpedia chromebooks eating microsoft market share said microsoft engaged silent war actually losing fighting enemy insidious cunning actually hurting company anything else enemy called chromebooks using linux ... sign things slowing microsoft really needs win soon wants remain relevant 2015 chromebooks sales volume companies us second windows based devices android tablets overtaking apple devices 2014 chromebook sales u.s. b2b channels increased 43 percent first half 2015 helping keep overall b2b pc tablet sales falling .. sales google os-equipped android chrome devices saw 29 percent increase 2014 propelled chromebook sales apple devices declined 12 percent windows devices fell 8 percent education market chromebooks notable success competing low cost hardware software upkeep simplicity machines could drawback markets proven advantage school districts reducing training maintenance costs january 2012 even commercial sales flat google placed nearly 27,000 chromebooks schools across 41 states us including one-on-one programs allocate computer every student south carolina illinois iowa august 2012 500 school districts united states europe using device 2016 chromebooks represented 58 percent 2.6 million mobile devices purchased u.s. schools 64 percent market outside u.s. contrast sales apple tablets laptops u.s. schools dropped year 19 percent compared 52 percent 2012 helping spur chromebook sales google classroom app designed teachers 2014 serves hub classroom activities including attendance classroom discussions homework communication students parents however concerns privacy within context education market chromebooks school officials schools issuing chromebooks students affirmed students right privacy using school-issued chromebooks even home online offline activity monitored school using third-party software pre-installed laptops electronic frontier foundation complained google violating privacy students enabling synchronisation function within google chrome chrome sync default allowing web browsing histories data students including under-13 stored google servers potentially used purposes authorised educational purposes point contention fact users school-issued chromebooks change settings measure protect privacy administrator issued laptops change eff claims violates student privacy pledge already signed google 2014 eff staff attorney nate cardozo stated minors n't tracked used guinea pigs data treated profit center google wants use students data 'improve google products needs get express consent parents march 2018 chromebooks made 60 computers used schools cnet writer alfred ng cited superior security main reason level market adoption hardware generation linux kernel version products inferred code name corresponding video game series december 7 2010 press briefing google announced chrome os pilot program pilot experiment first chromebook cr-48 chrome notebook prototype test chrome os operating system modified hardware device minimal design black completely unbranded although made inventec rubberized coating device named chromium-48 unstable isotope metallic element chromium participants named cr-48 test pilots google distributed 60,000 cr-48 chrome notebooks december 2010 march 2011 free participants return asked feedback suggestions bug reports cr-48 intended testing retail sales cr-48 hardware design broke convention replacing certain keys shortcut keys function keys replacing caps lock key dedicated search key changed back caps lock os keyboard settings google addressed complaints operating system offers little functionality host device connected internet demonstrated offline version google docs announced 3g plan would give users 100 mb free data month additional paid plans available verizon device usb port capable supporting keyboard mouse ethernet adapter usb storage printer chrome os offers print stack adding hardware outside previously mentioned items likely cause problems operating system self knowing security model users instead encouraged use secure service called google cloud print print legacy printers connected desktop computers connect hp eprint kodak hero kodak esp epson connect printer google cloud print service cloud aware printer connection cr-48 prototype laptop gave reviewers first opportunity evaluate chrome os running device ryan paul ars technica wrote machine met basic requirements web surfing gaming personal productivity falls short intensive tasks praised google approach security wondered whether mainstream computer users would accept operating system whose application browser thought chrome os could appeal niche audiences people need browser companies rely google apps web applications operating system decidedly full-fledged alternative general purpose computing environments currently ship netbooks paul wrote chrome os advantages found software environments without sacrifice native applications reviewing cr-48 december 29 2010 kurt bakke conceivably tech wrote chromebook become frequently used family appliance household 15 second startup time dedicated google user accounts made go-to device quick searches email well youtube facebook activities device replace five notebooks house one gaming two kids two general use biggest complaint heard lack performance flash applications ongoing testing wolfgang gruener also writing conceivably tech said cloud computing cellular data speeds unacceptable lack offline ability turns cr-48 useless brick connected difficult use chromebook everyday device give used mac/windows pc surely enjoy dedicated cloud computing capabilities occasionally cr-48 features intel atom 455 single-core processor 512 kb cache hyperthreading enabled also features 2 gb removable ddr3 memory single so-dimm integrated chipset graphics 66 watt-hour battery found intel nm10 chipset get hot operation due lack proper heatsink fixed production chromebooks launched google february 2013 chromebook pixel high-end machine chromebook family laptop unusual 3:2 display aspect ratio touch screen featuring debut highest pixel density laptop faster cpu predecessors intel core i5 exterior design described wired austere rectangular block aluminum subtly rounded edges second pixel featuring lte wireless communication twice storage capacity shipped arrival april 12 2013 machine received much media attention many reviewers questioning pixel value proposition compared similarly priced windows machines macbook air 2017 google launched pixelbook replace chromebook pixel like chromebook pixel pixelbook 3:2 aspect ratio touchscreen high pixel density display.. unlike original chromebook pixel like second generation pixelbook excludes option lte instead implements google instant tethering automatically tethers pixelbook pixel phone mobile connection reviewing samsung series 5 specifications scott stein cnet unimpressed machine 12-inch screen 16 gb onboard storage chrome os might lighter windows xp 'd still prefer media storage space price could also get wi-fi amd e-350-powered ultraportable running windows 7 hand mg siegler techcrunch wrote largely favorable review praising improvements speed trackpad sensitivity cr-48 prototype well long battery life fact models priced ipad june 2011 ifixit dismantled samsung series 5 concluded essentially improved cr-48 rated 6/10 repairability predominantly case opened change battery ram chip soldered motherboard ifixit noted mostly-plastic construction felt little cheap plus side stated screen easy remove components including solid-state drive would easy replace ifixit kyle wiens wrote series 5 fixes major shortfalls cr-48 adds polish necessary strike lust heart broad consumer base sleek looks 8+ hours battery life optimized performance may 2012 samsung introduced chromebook series 5 550 wi-fi model expensive 3g model reviews generally questioned value proposition dana wollman engadget wrote chromebook keyboard put thousand-dollar ultrabooks shame offered better display quality many laptops selling twice much price seems exist vacuum—a place tablet apps n't growing sophisticated transformer-like win8 tablets n't way n't solid budget windows machines choose joe wilcox betanews wrote price performance compares choices chromebook crumbles many potential buyers noted new models sell predecessors price-performance ratio quite favorable compared macbook air specs plenty lower-cost options october 2012 series 3 chromebook introduced san francisco event samsung chromebook xe303 device cheaper thinner lighter chromebook 550 google marketed series 3 computer everyone due simple operating system chrome os affordable price target markets included students first-time computer users well households looking extra computer lower price proved watershed reviewers new york times technology columnist david pogue reversed earlier thumbs-down verdict chromebook writing 250 changes everything price half ipad even less ipad mini ipod touch ’ getting laptop wrote chromebook many things people use computers laptops playing flash videos opening microsoft office documents words google correct asserts chromebook perfect schools second computers homes businesses deploy hundreds machines cnet review series 3 chromebook even favorable saying machine largely delivered computer students additional computer household—especially users already using google web applications like google docs google drive gmail got workable standout hardware battery life good switches quickly 249 price tag means much commitment 550 samsung series 5 550 arrived may review subtracted points performance fine many tasks power users accustomed couple dozen browser tabs open steer clear chromebook 3 distinct distinguished similarly named samsung series 3 several respects newer released 2016 different architecture intel celeron n3050 instead exynos 5 dual arm cortex thinner 0.7 less expensive 100 less series 3 remaining full implementation chromeos hp first chromebook largest chromebook market time pavilion 14 chromebook launched february 3 2013 intel celeron 847 cpu either 2gb 4gb ram battery life long 4 hours larger form factor made friendly all-day use hp introduced chromebook 11 october 8 2013 us december 2013 google hp recalled 145,000 chargers due overheating sales halted resuming redesigned charger following month hp chromebook 14 announced september 11 2013 intel haswell celeron processor usb 3.0 ports 4g broadband updated version chromebook lineup announced september 3 2014 11-inch models included intel processor 14-inch models featured fanless design powered nvidia tegra k1 processor hp chromebooks available several colors two types desktop computers also run chrome os classed small form-factor pcs chromeboxes typically feature power switch set ports local area network usb dvi-d displayport audio chromebooks chromeboxes employ solid-state memory support web applications require external monitor keyboard pointing device chromebase all-in-one chrome os device first model released lg electronics integrated screen speakers 1.3-megapixel webcam microphone suggested retail price 350 company unveiled product january 2014 international ces las vegas chromebit dongle running google chrome os operating system placed hdmi port television monitor device turns display personal computer chromebit allows adding keyboard mouse bluetooth via usb port
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Distributed computing architecture
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uncomplicated firewall uncomplicated firewall ufw program managing netfilter firewall designed easy use uses command-line interface consisting small number simple commands uses iptables configuration ufw available default ubuntu installations 8.04 lts gufw intended easy intuitive graphical user interface managing uncomplicated firewall supports common tasks allowing blocking pre-configured common p2p individual ports gufw designed ubuntu also available debian-based distributions arch linux anywhere python gtk+ ufw available
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Computer security
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root directory computer file system primarily used unix unix-like operating systems root directory first top-most directory hierarchy likened trunk tree starting point branches originate root file system file system contained disk partition root directory located filesystem top file systems mounted system boots use example physical file cabinet separate drawers file cabinet represented highest level sub-directories file system system prompt room file cabinet may represented root directory directories may inside root directory go directories least file system operating systems files placed inside root directory well sub-directories one may envision placing paper files anywhere room file cabinet within room unix abstracts nature tree hierarchy entirely unix unix-like systems root directory denoted codice_1 slash sign though root directory conventionally referred codice_1 directory entry name name empty part initial directory separator character codice_1 filesystem entries including mounted filesystems branches root dos os/2 microsoft windows partition drive letter assignment labeled codice_4 particular partition c common root directory dos os/2 windows support abstract hierarchies partitions mountable within directory another drive though rarely seen possible dos command codice_5 since first added dos achieved windows versions well contexts also possible refer root directory containing mounted drives although contain files directly exist file system instance linking local file using file uri scheme syntax form codice_6 codice_7 standard prefix third 'codice_1 represents root local system unix-like operating systems process idea root directory processes system actual root directory changed calling chroot system call typically done create secluded environment run software requires legacy libraries sometimes simplify software installation debugging chroot meant used enhanced security processes inside break freebsd offers stronger jail system call enables operating-system-level virtualization also serves security purposes restrict files process may access subset file system hierarchy unix systems support directory root directory normally /.. points back inode however changed point super-root directory remote trees mounted example two workstations pcs2a pcs2b connected via connectnodes uunite startup script /../pcs2b could used access root directory pcs2b pcs2a
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Computer file systems
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linux/rk linux/rk implementation resource kernel based linux developed real-time multimedia systems laboratory carnegie mellon university linux/rk consists two major components linux kernel subsystem called portable resource kernel resource kernel provides timely guaranteed enforced access physical resources applications main function operating system kernel multiplex available system resources across multiple requests several applications traditional non-realtime kernel allocates time-multiplexed resource application based fairness metrics certain period resource kernel application request reservation certain amount resource kernel guarantee requested amount available application guarantee resource allocation gives application knowledge amount currently available resources qos manager application optimize system behavior computing best qos obtained available resources
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Operating systems
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elastic cloud storage elastic cloud cloud computing offering provides variable service levels based changing needs elasticity attribute applied cloud services states capacity performance given cloud service expand contract according customer requirements potentially changed automatically consequence software-driven event worst reconfigured quickly customer infrastructure management team elasticity described one five main principles cloud computing rosenburg mateos cloud service manning 2011 cloud computing first described gillet kapor 1996 however first practical implementation consequence strategy leverage amazon excess data center capacity amazon pioneers commercial use technology primarily interested providing “ public ” cloud service whereby could offer customers benefits using cloud particularly utility-based pricing model benefit suppliers followed suit range cloud-based models offering elasticity core component suppliers offering service element public cloud service due perceived weaknesses security least lack proven compliance many organizations particularly financial public sectors slow adopters cloud technologies wary organizations achieve benefits cloud computing adopting private cloud technologies obvious weaknesses two five main principles cloud computing abrogated elasticity utility-based payments alternative form elastic cloud offered vendors emc ibm whereby service based around enterprise infrastructure still retains elements elasticity potential bill consumption elasticity cloud computing ability organization adjust storage requirements terms capacity processing respect operational requirements following benefits operational benefits services acquired quickly meaning evolving requirements business addressed almost immediately giving organization potential agility advantage properly implemented elastic system provision/de-provision according application demands particular business activity spikes provision enabled match demand capacity re-allocated research development r projects r activities longer hindered requirement secure capex budget prior project starting capability simply provisioned cloud released end exercise testing deployment large-scale projects size test needs performed prior final rollout taking advantage elasticity cloud creating full-scale avatar proposed production system realistic data traffic volumes provisioned released needed expensive resources allocated normally apply context customer applying least servers part cloud infrastructure specifically business performance reasons decided invest solid-state storage opposed spinning platters instances due activity spikes less critical process may need moved high-performance resources traditional storage server specification customer elected own/lease hardware select specify servers specifically tuned meet likely needs operation i.e. directly controlling cost/benefit equation utility based payments course key cost driver process notion pay consume acceptable many organizations hardware capacity sourced internally organizations need over-provision applies much traditional outsourcing capex-related expenditure in-house servers cloud platform – heart cloud storage system ability manage hyperscale object storage hadoop distributed files system hdfs elastic storage capability particularly well suited hyperscale hadoop environments capability rapidly respond changing circumstances priorities essential
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Distributed computing architecture
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seymour papert seymour aubrey papert february 29 1928 – july 31 2016 south african-born american mathematician computer scientist educator spent career teaching researching mit one pioneers artificial intelligence constructionist movement education co-inventor wally feurzeig cynthia solomon logo programming language born jewish family papert attended university witwatersrand receiving bachelor arts degree philosophy 1949 followed phd mathematics 1952 went receive second doctorate also mathematics university cambridge 1959 supervised frank smithies papert worked researcher variety places including st. john college cambridge henri poincaré institute university paris university geneva national physical laboratory london becoming research associate mit 1963 held position 1967 became professor applied math made co-director mit artificial intelligence laboratory founding director professor marvin minsky 1981 also served cecil ida green professor education mit 1974 1981 papert worked learning theories known focusing impact new technologies learning general schools learning organizations particular mit papert went create epistemology learning research group mit architecture machine group later became mit media lab developer theory learning called constructionism built upon work jean piaget constructivist learning theories papert worked piaget university geneva 1958 1963 one piaget protégés piaget said one understands ideas well papert papert rethought schools work based theories learning papert used piaget work development logo programming language mit created logo tool improve way children think solve problems small mobile robot called logo turtle developed children shown use solve simple problems environment play main purpose logo foundation research group strengthen ability learn knowledge papert insisted simple language program children learn—like logo—can also advanced functionality expert users part work technology papert proponent knowledge machine one principals one laptop per child initiative manufacture distribute children machine developing nations papert also collaborated construction toy manufacturer lego logo-programmable lego mindstorms robotics kits named groundbreaking 1980 book became political activist opposition parents began anti-apartheid activity says father said know someone talented seymour would throw life away ‘ schwartzes ’ derogatory yiddish expression black people ” subsequently chose self exile leading figure revolutionary socialist circle around socialist review living london 1950s papert also prominent activist south african apartheid policies university education papert married dona strauss later androula christofides henriques papert third wife mit professor sherry turkle together wrote influential paper epistemological pluralism revaluation concrete final 24 years papert married suzanne massie russian scholar author pavlovsk life russian palace land firebird papert aged 78 received serious brain injury struck motor scooter 5 december 2006 crossing street colleague uri wilensky attending 17th international commission mathematical instruction icmi study conference hanoi vietnam underwent emergency surgery remove blood clot french hospital hanoi transferred complex operation swiss air ambulance bombardier challenger jet boston massachusetts moved hospital closer home january 2007 developed sepsis damaged heart valve later replaced 2008 returned home could think communicate clearly walk almost unaided still complicated speech problems receipt extensive rehabilitation support rehabilitation team used principles experiential hands-on learning pioneered papert died home blue hill maine july 31 2016 papert work used researchers fields education computer science influenced work uri wilensky design netlogo collaborated study knowledge restructurations well work andrea disessa development dynaturtles 1981 papert along several others logo group mit started logo computer systems inc. lcsi board chair 20 years working lcsi papert designed number award-winning programs including logowriter lego/logo marketed lego mindstorms also influenced research idit harel caperton coauthoring articles book constructionism chairing advisory board company mamamedia also influenced alan kay dynabook concept worked kay various projects papert guggenheim fellowship 1980 marconi international fellowship 1981 software publishers association lifetime achievement award 1994 smithsonian award computerworld 1997 papert called marvin minsky greatest living mathematics educator mit president l. rafael reif summarized papert lifetime accomplishments mind extraordinary range creativity seymour papert helped revolutionize least three fields study children make sense world development artificial intelligence rich intersection technology learning stamp left mit profound today mit continues expand reach deepen work digital learning particularly grateful seymour groundbreaking vision hope build ideas open doors learners ages around world
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Programming language topics
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visual instruction set visual instruction set vis simd instruction set extension sparc v9 microprocessors developed sun microsystems five versions vis vis 1 vis 2 vis 2+ vis 3 vis 4 vis 1 introduced 1994 first implemented sun ultrasparc microprocessor 1995 fujitsu sparc64 gp microprocessors 2000 vis 2 first implemented ultrasparc iii subsequent ultrasparc sparc64 microprocessors implement instruction set vis 3 first implemented sparc t4 microprocessor vis 4 first implemented sparc m7 microprocessor vis instruction toolkit like intel mmx sse mmx 8 registers shared fpu stack sparc processors 32 registers also aliased double-precision 64-bit floating point registers simd instruction set extensions risc processors vis strictly conforms main principle risc keep instruction set concise efficient design different comparable extensions cisc processors mmx sse sse2 sse3 sse4 3dnow sometimes programmers must use several vis instructions accomplish operation done one mmx sse instruction kept mind fewer instructions automatically result better performance vis re-uses existing sparc v9 64-bit floating point registers hold multiple 8 16 32-bit integer values respect vis similar design mmx simd architectures sse/sse2/altivec vis includes number operations primarily graphics support integers include 3d 2d conversion edge processing pixel distance four ways use vis code
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Computer architecture
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support programs os/360 successors article discusses support programs included available os/360 successors ibm categorizes programs utilities others service aids boundaries always consistent obvious many programs match types utility software following lists describe programs associated os/360 successors dos tpf vm utilities included many programs designed ibm users group share modified extended ibm versions originally written user programs usually invoked via job control language jcl tend use common jcl dd identifiers os z/os operating systems data sets idcams access method services generates modifies virtual storage access method vsam non-vsam datasets idcams introduced along vsam os/vs access method reference derives initial vsam replaces access methods mindset os/vs idcams probably functionality utility programs performing many functions vsam non-vsam files following example illustrates use idcams copy dataset disk dataset 80-byte records system choose block size output example sysin control cards coming in-stream file instead point sequential file pds member containing control cards temporary data-set wish example using sysin files would something like iebcompr compares records sequential partitioned data sets iebcompr utility used compare two sequential partitioned datasets data set comparison performed logical record level therefore iebcompr commonly used verify backup copy data set correct exact match original processing iebcompr compares record data set one one records unequal iebcompr lists following information sysout comparing sequential data sets iebcompr considers data sets equal following conditions met partitioned data sets iebcompr considers data sets equal following conditions met ten unequal comparisons encountered processing iecompr terminates appropriate message note iebcompr flexible user-friendly compare program ca n't restrict comparison certain columns ca n't ignore differences white space n't tell record difference occurs halts 10 differences hand fast present ibm mainframes useful exact match expected comparing load modules reblocked checking copy worked properly comparisons programs reports ispf superc isrsupc compare program often used instead iebcopy copies compresses merges partitioned data sets also select exclude specified members copy operation rename replace members tasks iebcopy perform include following iebcopy utility required job control statements copy follows mydd1 mydd2 dd statements names chosen user partitioned input output data sets respectively defaults sysut1 sysut2 use valid ddname two dd statements ddnames specified utility control statements tell iebcopy name input output data sets need one dd statement pds compressed iebdg 'data generator creates test datasets consisting patterned data control statements define fields records created including position length format initialization performed iebdg use existing dataset input change fields specified control statements example replacing name field random alphabetic text contents field may varied record example rotating characters alphanumeric field left right subsequent record example iebedit selectively copies portions jcl example iebedit program example data set xxxxx.yyyyy.zzzzz contain job include steps named step5 step10 step15 iebedit routine copies selected steps job onto sysut2 output file example internal reader syntax edit statement codice_1 specifies name input job edit statement applies edit statement must apply separate job start specified without type stepname job statement job steps specified job included output default start omitted one edit statement provided first job encountered input data set processed start omitted edit statement first statement processing continues next job statement found input data set codice_2 specifies contents output data set values coded codice_3 specifies output consist job statement job step specified stepname parameter steps follow job step job steps preceding specified step omitted operation position default codice_4 specifies output data set contain job statement job steps specified stepname parameter codice_5 specifies output data set contain job statement job steps belonging job except steps specified stepname parameter codice_6 specifies names job steps want process codice_7 single job step name list step names separated commas sequential range steps separated hyphen example stepa-stepe combination may used one namelist one step name specified entire namelist must enclosed parentheses coded type=position stepname specifies first job step placed output data set job steps preceding step copied output data set coded type=include type=exclude stepname specifies names job steps included excluded operation example stepname= stepa stepf-stepl stepz indicates job steps stepa stepf stepl stepz included excluded operation stepname omitted entire input job whose name specified edit statement copied job name specified first job encountered processed codice_8 specifies message data set include listing output data set default resultant output listed message data set see info iebgener copies records sequential dataset creates partitioned dataset tasks iebgener perform include following example iebgener program copy one dataset another straight copy tasks sort program often faster iebgener thus many mainframe shops make use option automatically routes tasks sort icegener program instead iebgener systems possible send email batch job directing output codice_9 external writer systems technique follows also possible attach files sending email mainframe iebimage manipulates several types definitions aka images ibm 3800 laser printing subsystem ibm 4248 printer common uses forms control buffers fcbs character arrangement tables character definitions images forms printed output along text company logos printed page print 'graybar pages alternating gray white horizontal backgrounds match previous greenbar paper utility many different forms logos could stored images printed needed using standard blank paper thus eliminating need stock many preprinted forms need operators stop printer change paper iebisam unloads loads copies prints isam datasets extracted ibm manual sc26-7414-08 z/os dfsmsdfp utilities iebisam program longer distributed starting z/os v1r7 isam data sets longer processed created opened copied dumped isam data sets still use must converted vsam key-sequenced data sets prior z/os v1r7 could use access method services allocate vsam key-sequenced data set copy isam data set iebptpch print punch prints punches records sequential partitioned dataset tasks iebptpch perform include following empty dataset check dataset checked empty rc=4 else 0 read records 2495 tape cartridge reader changes records sequential dataset member partitioned dataset replaced compatible iebupdte iebupdte update incorporates changes sequential partitioned datasets unix codice_10 utility similar program uses different input format markers e..g insert ... mvs becomes ... unix patch programmers pronounce i.e.b up-ditty iebupdte utility used maintain source libraries functions iebupdte perform include following iebupdte commonly used distribute source libraries tape dasd iebupdte uses job control statements required ieb-type utilities exceptions follow job control used ieupdte follows iefbr14 dummy program normally inserted jcl desired action allocation deletion datasets example iefbr14 step calling sequence os/360 contained return address register 14 branch register 14 would thus immediately exit program however executing program operating system would allocate deallocate datasets specified dd statements commonly used quick way set remove datasets consisted initially single instruction branch register 14 mnemonic used ibm assembler br hence name ief br 14 ief course prefix os/360 job management subsystem single instruction program error — n't set return code hence second instruction added clear return code would exit correct status additional error reported fixed ibm two instruction program error due iefbr14 program link-edited reenterable simultaneously usable one caller hackers taken iefbr14 changed br 14 instruction br 15 thereby creating shortest loop world register 15 contains address iefbr14 module br 15 instruction would simply re-invoke module forever utilities normally used systems programmers maintaining operation system rather programmers application work system ickdsf device support facility installs initializes maintains dasd either operating system standalone assign alternate tracks defective tracks iehdasdr “ direct access storage dump restore ” older program found current z/os manuals dumps datasets disk printer backup restores backups iehdasdr removed mvs/xa iehinitt initialize tape initializes tapes writing tape labels multiple tapes may labeled one run utility ibm standard ascii labels may written example iehinitt program example label 3 tapes 3490 magnetic tape unit tape receive ibm standard label volser incremented one tape labeled tape rewound unloaded labeled update ttr links type iv supervisor call svc routines sys1.svclib applicable os/vs2 later iehlist utility used list entries partitioned dataset pds directory list contents volume table contents vtoc iehlist utility used list entries contained one following example iehlist program job produce formatted listing pds directory pds named xxxx.yyyy.zzzz example iehlist program list vtoc similar iehmove moves copies collections data however dfsms system managed storage environments common ibm recommend using iehmove utility move differs copy following move original data set deleted scratched tasks iehmove perform include following surface iehmove may seen redundant iebgener iebcopy utilities however iehmove powerful main advantage using iehmove need specify space dcb information new data sets iehmove allocates information based existing data sets another advantage iehmove copy move groups data sets well entire volumes data ease moving groups data sets volumes iehmove utility generally favored systems programmers sample iehmove job dd statements iehmove sysprint sysin refer dasd magnetic tape volumes instead individual data sets however referencing volumes pose problem since specifying codice_11 gains exclusive access volume therefore iehmove job runs entire volume datasets unavailable users acceptable private volumes tape mountable dasd volumes unacceptable public volumes sysut1 dd statement specifies dasd volume three work data set required iehmove allocated must specify unit volume information dd statement iehmove one first systems developed pl/s example three sequential data sets seqset1 seqset2 seqset3 moved one disk volume three separate disk volumes three receiving volumes mounted required iehmove source data sets cataloged space allocated iehmove iehprogm builds maintains system control data also used renaming scratching deleting data set tasks iehprogm perform include following cataloging select format smf records tape errors programs run control operating system format direct access volumes assign alternate tracks dump restore direct access volumes assign alternate tracks recover replace data load forms control buffer fcb universal character set ucs buffer printer utility program ibm documents service aids diagnosis manuals original os/360 service aids names beginning ifc im* ibm changed naming convention hm* os/vs1 am* os/vs2 ibm change ifc convention initializes sys1.logrec data set summarizes prints records sys1.logrec error recording data set traces selected system events svc i/o interruptions generates jcl needed apply ptf and/or applies ptf functions program subsumed smp verifies and/or replaces instructions and/or data load module program object formats prints object modules load modules program objects csect identification records maps load modules functions program subsumed imblist stand-alone program format print system job queue applicable mvs format print system job queue applicable mvs formats prints dumps tso swap data set gtf trace data stand-alone program produce high-speed low-speed dump main storage sort/merge utility program sorts records file specified order merge pre-sorted files frequently used often commonly used application program mainframe shop modern sort/merge programs also select omit certain records summarize records remove duplicates reformat records produce simple reports sort/merge important enough multiple companies selling sort/merge package ibm mainframes ibm original os/360 sort/merge program 360s-sm-023 program name ierrco00 alias sort supported ibm first-generation direct-access storage devices dasd tapes 2400 support second-generation disk drives provided ibm program products 5734-sm1 later 5740-sm1 dfsort alias iceman also sort sort frequently executed stand-alone program normally reads input file identified dd codice_12 writes sorted output file identified dd codice_13 also often called another application via cobol codice_14 verb calls pl/i codice_15 routines may use either codice_12 codice_13 files passed records sorted caller and/or pass sorted records back caller one time operation sort directed control statements largely compatible among various ibm third-party sort programs codice_14 codice_19 statement defines sort keys — fields data sorted merged statement identifies position length data type key codice_20 statement describes format length records input file statements allow user specify records included excluded sort specify transformations performed data keys combination ebcdic ascii character data zoned packed-decimal signed unsigned fixed-point binary hexadecimal floating-point keys located anywhere record contiguous sorting specified combination ascending descending sequence key os/360 sort program ierrco00 operates dividing input data sections sorting section main memory writing sorted section intermediate datasets either direct-access storage devices dasd magnetic tape final merge phases merge sections produce sorted output sort uses one number techniques distributing sections among secondary storage devices usually sort choose optimal technique overridden user sort three techniques used intermediate storage tape two disk tape techniques disk techniques os/360 linkage editor available several configurations dfsmsdfp added binder alternatives load modules option program objects linkage editor creates replaces load modules partitioned data set combination control cards object modules load modules rename replace control section csect perform several miscellaneous functions originally available several configurations depending storage requirement e level linkage editor longer available f level linkage editor known simply linkage editor z/os linkage editor present compatibility binder performs functions linkage editor addition supports new format program object functional equivalent load module partitioned data set extended pdse many additional capabilities programming language used computer shop one associated compilers translate source program machine-language object module object module compiler must processed linkage editor iewl create executable load module igycrctl common example compiler compiler current ibm enterprise cobol z/os product several previous ibm cobol compilers years different names many compilers various programming languages assembler e intended os/360 running small machines assembler f intended normal os/360 installations assembler xf system assembler os/vs1 os/vs2 replacing assembler e f although fully compatible ibm soon made assembler xf system assembler dos vm well assembler h assembler h version 2 program product assemblers generally faster assemblers e f xf although fully compatible ibm high level assembler hlasm essentially new version assembler h version 2 assembler ibm supports z/os z/vm replaces older assemblers although fully compatible system modification program smp vehicle installing service os/360 successors replacing e.g. stand-alone assembly link edit imaptfle jobs originally optional facility mandatory mvs/sp later program product version smp/e included recent systems e.g. z/os
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Operating systems
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history risc os risc os computer operating system developed acorn computers arm-based acorn archimedes range originally released 1987 soon followed next version became completed made available april 1989 released earliest version a5000 1991 contained series new features 1996 risc os shipped 500,000 systems. released riscos ltd rol july 1999 based continued development rol march 1999 licensed rights risc os element 14 renamed acorn eventually new owner pace micro technology according company 6,400 copies rom sold production ceased mid-2005. launched may 2001 rol subscription scheme allowing users access latest os updates upgrades released soft-loadable rom images separate rom boot os stored loaded boot time shipped may 2002 following november 2002 final release june 2004 rol released rom based month dubbed play risc os gui convention calling three mouse buttons 'select 'menu 'adjust rol sold 500th adjust rom early 2006. released october 2002 castle technology acorn clone iyonix pc separate evolution based upon ncos work done pace set-top boxes october 2006 castle announced source sharing license plan elements shared source initiative ssi managed risc os open ltd rool risc os 5 since released fully free open source apache 2.0 license older longer maintained risc os 6 older not. also announced october 2006 rol next generation stream operating system first product launched name continuation select scheme beta-version available 2007 free download subscribers select scheme april 2009 final release shipped latest release risc os rol shipped december 2009 os designed united kingdom acorn 32-bit arm based acorn archimedes released first version 1987 arthur operating system first public release os arthur 1.20 june 1987 bundled desktop graphical user interface gui mostly comprises assembly language software modules desktop module written features colour-scheme typically described technicolour graphical desktop runs top command-line driven operating system owes much acorn earlier mos operating system bbc micro range 8-bit microcomputers arthur originally conceived intended deliver similar functionality operating system bbc master series computers mos reaction fact advanced operating system research project arx would ready time archimedes arthur project team led paul fellows given five months develop entirely ground up—with directive make like bbc micro intended stop-gap operating system acorn development arx could completed however latter delayed time eventually dropped became apparent arthur development could extended window manager full desktop environment also small enough run first 512k machines floppy disc whereas arx required 4 megabytes hard drive os development carried using prototype arm-based system connected bbc computer moving onto prototype acorn archimedes a500 arthur multitasking operating system offered support adding application-level cooperative multitasking version operating system released externally internally development desktop window management continued addition cooperative multitasking system invented neil raine used memory management hardware swap-out one task bring another call-and-return wimp-poll call applications obliged make get messages desktop transformed single-application-at-a-time system one could operate full multi-tasking desktop transformation took place version 1.6 though made public released name change arthur risc os version 2.0 software made arthur 1.2 run risc os 2 later underneath desktop original arthur os core api interfaces modular structures remain heart versions titles work however used undocumented features side effects cases apis became deprecated 2011 business insider listed arthur one ten operating systems time forgot next version became completed made available april 1989 risc os rapid development arthur 1.2 failure arx project first release called arthur 2 renamed risc os 2 first sold risc os 2.00 april 1989 operating system implements co-operative multitasking limitations multi-threaded uses adfs file system floppy hard disc access initially ran 512 kb set roms wimp interface offers standard features fixes many bugs hindered arthur lacks virtual memory extensive memory protection applications protected many functions implemented 'modules full access memory time release main advantage os rom booted quickly easy crash impossible permanently break os software high performance due much system written arm assembly language os designed users mind rather os designers organised relatively small kernel defines standard software interface extension modules required conform much system functionality implemented modules coded rom though supplanted evolved versions loaded ram among kernel facilities general mechanism named callback handler allows supervisor module perform process multiplexing facility used module forming part standard editor program provide terminal emulator window console applications approach made possible advanced users implement modules giving risc os ability pre-emptive multitasking slightly updated version risc os 2.01 released later support arm3 processor shipped acorn archimedes a540 acorn r225/r260 introduced number new features including multitasking filer operations applications fonts rom limit number open windows ability move windows screen safe shutdown pinboard arm3 support grouping icon bar icons 128 tasks ability read ms-dos format discs use named hard discs improved configuration also included way multiple windows change settings risc os 3.00 released earliest version a5000 1991 almost four times size risc os 2 runs 2 mb rom improves multitasking also places popular base applications rom risc os 3.00 several bugs replaced risc os 3.1 months later upgraded roms supplied cost postage risc os 3.1 released later sold built a3010 a3020 a4000 a4 later a5000 models also made available replacement roms a5000 earlier archimedes machines last risc os version suitable machines three variants released risc os 3.10 base version risc os 3.11 included slight update fixes serial port issues risc os 3.19 german translation risc os 3.50 sold 1994 first risc pcs due different hardware architecture risc pc including arm 6 processor 16- 24-bit colour different io chip iomd risc os 3.50 made available older archimedes series arm2 3 machines risc os 3.5 somewhat shoehorned 2 mb footprint moved rom applications risc os 3.1 onto hard drive proved unpopular later moved back rom version introduced issues backward compatibility particularly games risc os 3.60 followed 1995 os features much improved hard disk access networking enhanced include tcp/ip standard addition acorn existing proprietary econet system hardware support also improved risc pcs could use arm7 processors acorn a7000 machine arm7500 processor also supported risc os 3.6 twice size risc os 3.5 shipping 4 mb two rom chips risc os 3.70 released 1996 primary changes os support strongarm processor made available upgrade risc pc required extensive code changes due strongarm split data instruction cache harvard architecture 32-bit interrupt modes risc os 3.71 small update released support hardware acorn a7000+ arm7500fe processor fe offered hardware support floating point mathematics usually emulated one risc os software modules risc os 3.60 also formed foundation ncos shipped acorn netchannel ncs acorn officially halted work areas except set-top boxes january 1999 company renamed element 14 14th element periodic table silicon new goal become purely silicon design business like previous successful spin arm acorn 1990 risc os development halted development os 4.0 riscpc 2 phoebe 2100 whose completion also cancelled beta version os 3.8 ursula original riscpc previously released developers project code names phoebe hardware ursula software chandler graphics processor chip taken names characters tv series friends phoebe ursula twin sisters series led number rescue efforts try keep acorn desktop computer business alive acorn held discussions many interested parties eventually agreed exclusively licence risc os riscos ltd formed consortium dealers developers end-users pace purchased rights use develop ncos also number projects bring advantages risc operating system platforms creation rox desktop provide risc os-like interface unix linux systems separate work pace resulted code fork continued subsequent licensing agreement castle technology causing much community debate time debate remains ongoing 2011 march 1999 new company called riscos ltd founded licensed rights risc os element 14 eventually new owner pace micro technology continued development os 3.8 releasing risc os 4 july 1999 whilst hardware support phoebe needed core improvements risc os 3.80 could finished released included according company 6,400 copies risc os 4.02 rom sold production ceased mid-2005 1999 2000 riscos ltd also released versions risc os 4 support several additional hardware platforms microdigital mico microdigital omega riscstation r7500 castle kinetic riscpc 2003 version risc os 4 released support millipede graphics alphalock podule risc os 4 also available various hardware emulators operating systems september 2003 virtualacorn released commercial emulator virtualrpc included copy risc os 4.02 december 2008 riscos ltd made 4.02 available non-commercial emulators £5 product called virtually free may 2001 company launched risc os select subscription scheme allowing users access latest os updates upgrades released soft-loadable rom images separate rom boot os stored loaded boot time providing soft-loads physical rom costs eliminated updates able delivered accelerated speed frequency also allowed company subsidise retail price rom releases generally culmination last select upgrades extra minor changes may 2002 final release select 1 shipped included november 2002 final release select 2 shipped included june 2004 final release select 3 shipped included also june 2004 riscos ltd released rom based version 4.39 dubbed risc os adjust name play risc os gui convention calling three mouse buttons 'select 'menu 'adjust riscos ltd sold 500th adjust rom early 2006 features introduced 4.39 include user customization graphical user interface release select scheme made risc os six branding mentioned a9home released 2006 uses version 4.42 adjust 32 developed supports 32-bit addressing modes found later arm architectures october 2006 shortly castle technology announced shared source initiative riscos ltd announced risc os six next generation stream operating system first product launched risc os six name continuation select scheme select 4 beta-version risc os 6 preview 1 select 4i1 available 2007 free download subscribers select scheme present subscribers whose subscription renewed 30 may 2004 since lapsed risc os six brought portability stability internal structure improvements including full 26/32-bit neutrality highly modularised legacy hardware specific features abstracted code separated easier future maintenance development teletext support device interrupt handler software-based graphics operations real-time clock mouse pointer cmos ram support hardware timer support abstracted kernel separate modules legacy components like vidc driver obsolete functionality bbc micro abstracted aif transient utility executable checking introduced also protect rogue software graphics acceleration modules may provided sm501 graphics chip a9home viewfinder agp podule cards april 2008 final release select 4 shipped included select 4 releases initially compatible acorn risc pc a7000 machines riscstation r7500 microdigital omega mico computers officially supported company test machines available requires proprietary software code rights lack detailed technical information microdigital omega also cited another reason support hardware difficult april 2009 final release select 5 shipped included final release risc os riscos ltd select 6i1 shipped december 2009 includes risc os 5 separate evolution castle technology ltd based upon work done pace ncos based set top boxes risc os 5 written support castle iyonix pc acorn-compatible runs intel xscale arm processor although wealth software updated older applications run risc os 5 via emulator called aemulor since armv5 xscale processor support 26-bit addressing modes likewise risc os 5 ported run properly new cpu abstraction graphics hardware interfaces created allow example use standard graphics cards instead acorn vidc chip july 2003 castle technology ltd bought head licence risc os pace micro october 2006 castle technology ltd announced plan release elements risc os 5 source sharing license shared source initiative ssi joint venture castle risc os open limited rool newly formed software development company aims accelerate development encourage uptake os custom dual license released source freely available may modified redistributed without royalty non-commercial use commercial usage incur per-unit license fee castle ssi made phased releases source code starting may 2007 october 2008 enough source released build almost complete iyonix rom image late 2011 possible build complete rom images published sources full source code available tarballs cvs web interface cvs archive addition prebuilt images available stable releases development nightly builds rool maintains shared source tree builds international developer community non-profit basis support encourage development rool castle intend provide risc os consultancy clients requiring embedded arm solutions already major market os ports risc os 5 available a7000/a7000+ riscpc rpcemu omap3 beagleboard derivatives omap4 pandaboard pandaboard es am5728 titanium raspberry pi xscale iyonix october 2018 risc os 5 re-licensed apache 2.0 license
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Operating systems
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developer certificate origin developer certificate origin dco introduced 2004 linux foundation enhance submission process software used linux kernel shortly sco–linux disputes dcos often used alternative contributor license agreement cla instead signed legal contract dco affirmation source code submitted originated developer developer permission submit code proponents dco content reduces barriers entry introduced cla
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Operating systems
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arp cache arp cache collection address resolution protocol entries mostly dynamic created ip address resolved mac address computer effectively communicate ip address arp cache disadvantage potentially used hackers cyber attackers arp cache helps attackers hide behind fake ip address beyond fact arp caches may help attackers may also prevent attacks distinguish ing low level ip ip based vulnerabilities
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Internet protocols
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modernpascal modern pascal closed source cross-platform interpreter compiler runtime environment command line server-side networking applications modern pascal applications written pascal/object pascal run within modern pascal runtime microsoft windows linux os x freebsd solaris dos/32 operating systems work hosted supported 3f llc partner mp solutions llc modern pascal provides blocking i/o api technology commonly used operating system applications modern pascal coderunner contains built-in library allow applications act web server without software apache http server iis modern pascal invented 2000 ozz nixon also co-developing dxjavascript alexander baronovski ozz inspired kylix project 1999 met borland pascal team shared programming language modern pascal ozz ported commercial socket suite dxsock kylix started developing modern pascal run pascal scripts microsoft windows linux os x 2002 version 1.1 released modern pascal v1.1 capable running turbo pascal dos syntax last version using variants internally variable code instances version 1.1 introduced support built-in rtl units allowing developers extend language grammar support crt/display tcp/ip socket calls 2005 version 1.2 released modern pascal v1.2 available 64bit platforms native 64bit binaries internal support 64bit numbers memory addresses 2007 version 1.3 released modern pascal v1.3 added cross-platform support dynamic libraries .so .dylib .dll first version capable developing native windows gui applications along linux qt gui applications supporting external libraries language longer limited command line web server script engine role 2008 version 1.4 released modern pascal v1.4 fork internally called declan decisioning language use credit financial industry version 1.4 also introduced tdataset compatibility borland delphi compiler along ability connect databases via built-in odbc support allows modern pascal leverage almost sql database engines command line web solutions 2009 version 1.5 released modern pascal v1.5 redesign parser phase lexicon first version modern pascal started incorporate syntax popular languages like += -= *- /= c/javascript version 1.5 available native apache module windows linux os x 2010 version 1.6 released modern pascal v1.6 incorporates built-in rtl units ciphers compressions hashs version truly focused migrating applications web needed built support common ciphers hashes compression algorithms used restful applications 2011 version 1.7 released modern pascal v1.7 redesign apache module release forward modern pascal longer built apache module modern pascal celerity introduced inspired design coldfusion ntier back end web servers means future release fastcgi isapi even old cgi nsapi interfaces could deployed version 1.7 also introduced old pascal 3.0 feature called chaining slightly modern style 2013 version 1.8 released modern pascal v1.8 introduced support delphi-like classes smart records unions self instantiation version 1.8 first version modern pascal started truly become pascal dialect 2014 version 1.9 built released public modern pascal v1.9 used develop developip large scale public web site 2015 version 2.0 begun modern pascal 2.0 fork lape previous versions fast efficient fast enough larger customers current benchmarks show v2.0 processing 100 million instructions second roughly 8 times faster version 1.9 much faster alternative pascal script engines july 2015 modern pascal 2.0 enters final private beta cycle team actively porting code snippets old applications 2.0 publishing code github 2017 version 2.0 released public includes native dbase iii+ iv v vii clipper foxpro support past 24 months development 3f ported github source 17 bbses including quickbbs tpboard hermes binkp fidonet protocol multiple tossers adventure game studio 1984 custom micro solutions inc. accounting point sale software web ria applications 3f also introduced transparent support extended ascii ansi utf8 graphics modern pascal command line interface allows create run dos like applications using pascal decades free pascal source code implement run wide range business classes command utilities modern pascal celerity allows create similar solutions stand-alone middleware backend engine combined apache module celerity used create wide range web script solutions modern pascal coderunner allows create standalone networking tools including web servers email servers chat servers coderunner manages tcp communications code even tls/ssl developer simply focus happens connection established program game.loot.example uses math const maxprobability=1000 type function looter.choose loottype var begin end function looter.asstring l loottype string begin end procedure looter.free begin end // must listed implementation // procedure looter.init begin end var begin end output replaced original code sample something easier read/follow run turbo pascal syntax hello world program modernpascal coded normal pascal hello world program helloworld begin end modernpascal also supports brief pascal execute statements without formality writeln 'hello world pascal speak reusable collection methods referred unit languages often call modules libraries modern pascal built-in units handle display environment calls like file system i/o sockets networking tcp binary data buffers classes objects cryptography functions data streams regular expression collections logging configuration files using ini csv sdf similar csv formats databases odbc built-in dbase clipper foxpro core functions modern pascal operates without requiring third-party libraries modern pascal optionally require openssl achieve tls/ssl listeners clients modern pascal operates using single thread model using blocking i/o calls celerity coderunner self-threading engines allowing modern pascal support tens thousands concurrent connections design single thread instance code means used build highly reliable applications design goal modern pascal application skill level programmer able operate without fear memory leak variable collision threads etc approach allows scaling number cpu cores machine running negative approach increase thread switching contexts however modern pascal tested base dell laptop handling 50,000 concurrent connections/scripts
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Programming language topics
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masterseek masterseek corp. b2b business-to-business search engine founded denmark 1999 masterseek encompasses 175 million business profiles 346 million websites 450 million contacts 216 million linkedin members thus making masterseek largest commercial database world masterseek founded denmark rasmus refer 1999 denmark headquarters located bredgade 29 dk-1260 kbh k also current headquarters new york city 82 wall street according executives masterseek utilizes business model based annual business subscription fee usd 149 return subscribers receive full editing control corporate profile content advertising control widgets embedded video among factors june 2008 accountancy firm horwart international approximated raw market value masterseek company 150 million company remains privately owned also june 2008 sold 10 authorized stocks range foreign investors company announced january 31 2009 company offering limited number shares sale order raise 4–6 million order gain listing swedish marketplace aktietorget founder refer also announced plans ipo october 2009 signed swedish-based company thenberg kinde fondkommission ab financing july 11 2016 masterseek announced company planning getting listed nasdaq listing nasdaq provide capital expansion rapidly growing markets latin america africa asia doney law firm assisting listing nasdaq capital market june 2008 company stated 50 million company profiles 75 countries handled 90,000 b2b searches daily company stated 82 million profiles march 21 2011 average 300,000 new profiles added monthly 2017 company stated 178 million company profiles october 30 2008 announced masterseek acquired b2b search engine accoona search engine fairly successful united states china exclusive partnership china daily august 3 2006 time dubbed accoona one 50 best websites illustrating search engine used artificial intelligence understand meaning keyword queries accoona run difficulties gone defunct early october 2008 withdrawing ipo making possible masterseek acquire data technology masterseek bought remaining search engine codes domain name assets accoona integrated masterseek re-launched usa china launched europe january 2009 accoona information also integrated masterseek search engine masterseek search engine relies web crawlers automatically collect sort company details internet searches look company profiles contact information descriptions products services searches global national regional involved local markets hits listed relevance according search terms different search options including specific product search company searches people searches results displayed languages search engine also offers masterrank point system ranking corporate websites july 5 2007 masterseek announced cosponsors team csc denmark cycling team beginning team involvement tour de france masterseek name began displayed team apparel week tour start london global investor alerts issued public warning alerting masterseek corp. cold-calling potential customers offering unauthorised illegal financial services also multiple reports masterseek engine crawling profiles individuals illegally violating privacy fair use policies services like linkedin create publicly publish profiles individuals without consent providing control editing profiles owners profiles thus violating civil criminal laws multiple jurisdictions around world
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Web technology
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norton 360 norton 360 developed symantec “ all-in-one ” security suite combined online protection performance tuning thing distinguished suite norton internet security inclusion optimization problem-solving tools norton 360 distributed boxed copy download preinstalled computers oem software norton 360 discontinued cut overhauled norton line mid-2014 features carried successor norton security symantec announced project genesis february 7 2006 genesis would differ symantec consumer security products incorporating file backup performance optimization tools antivirus capabilities firewall phishing protection real-time heuristics also planned windows vista compatibility major aspect genesis genesis slated release september may 2005 microsoft announced windows live onecare security suite similar functionalities slated release 2006 genesis renamed norton 360 may 31 2006 feature set confirmed—it would functionalities norton internet security—with file backup performance tools phishing protection real-time heuristics public beta test planned summer 2006 final release date set end 2006 day mcafee announced falcon security suite similar functionalities norton 360 onecare however dates delayed onecare launched summer 2006 falcon entered public beta testing viewed norton 360 response microsoft antivirus software onecare however release onecare saw symantec lagging behind rivals mark bregman symantec vice president claimed upcoming norton 360 intended compete onecare stating somehow left wrong impression market place windows live onecare microsoft falcon mcafee nothing symantec first public beta delivered november 2006 compatible windows xp second beta subsequently released december 20 2006 adding compatibility windows vista build 6000 100,000 people tested software symantec began distribution retailers february 2007 version 1.0 released february 26 2007 version first symantec product use sonar detect zero-day viruses monitors applications malicious behavior taking action needed backup restore functionality allowed users back files online hard drive cd dvd performance optimization tools allowed users clear web browser history temporary files disk defragmenter bundled part optimization tools phishing protection integrates internet explorer warning users fraudulent sites windows xp 300 megahertz processor 256 megabytes ram 300 mb hard disk space required vista 800 mhz processor 512 mb ram 300 mb hard disk space required reviews cited norton 360 low resource usage relative norton internet security 2007 phishing protection pc magazine found phishing protection feature effective blocking access fraudulent sites internet explorer 7 firefox 2 however reviewers highlighted lack manual control advanced users cnet noted lack phishing protection browsers internet explorer mozilla firefox cnet also highlighted lack wireless network tools notifying users someone uninvited joins network help encrypting wireless signals pc magazine criticized antispam filter version 1.0 finding blocked half spam mail five percent false positive rate version 2.0 released march 3 2008 backup feature inscribe data blu-ray hd dvd discs multiple installations norton 360 also managed centralized location backing files online user control amount bandwidth norton uses registry cleaner bundled performance tools allowing user remove invalid entries phishing protection firefox added supplementing phishing protection norton identity safe stores login credentials websites network map allows users view status norton installations networked computers view basic information computer system requirements remain version 1.0 pc magazine found spam filter inaccurate 25 percent false positive rate cnet encountered problems installing version 2.0 legacy machines version 3.0 released march 4 2009 version uses codebase norton internet security 2009 earlier versions symantec rewrote code specifically norton 360 version 3.0 incorporates norton safe web offered standalone service earlier safe web integrates firefox internet explorer toolbar blocking access fraudulent malware hosting sites toolbar also includes search box routing search queries typed box ask.com search engine toolbar share code ask.com toolbar classified spyware mcafee trend micro antivirus vendors due criticism search functionality symantec announced ask.com search box would hidden future releases version 3.0 capability back files flash drive introduced release files stored flash drive copied another computer without norton 360 installed norton also creates virtual drive windows explorer allowing users browse backup files stored locally online users restore individual files using drag-and-drop technique version 3.0 retain previous versions files skips files open another program startup application manager included release allowing users control programs start login complement application manager norton measure impact programs login time pc magazine highlighted version 3.0 inaccurate spam filter misfiling half valid mail spam pc magazine also noted support session symantec technician used shareware application malwarebytes anti-malware remove malware computer referring online norton program controversy raised fact technician misleadingly referred program symantec product version 4.0 released february 17 2010 version adds many new security features found norton internet security 2010 version 4 also features gui change prominent colors match gold black sunburst norton internet security widely criticized antispam replaced far effective brightmail according symantec gives 20 better results require training version 5.0 released february 2011 offers improved performance virus detection also provides updated versions sonar version 3 system insight download insight supports internet explorer firefox browsers also supports following clients qq chat msn messenger chat limewire p2p msn explorer browser e-mail chat opera browser outlook e-mail thunderbird e-mail windows mail e-mail chrome browser bittorrent p2p aol browser yahoo messenger chat safari browser filezilla file manager outlook express e-mail features new enhanced interface realistic icons animations also includes norton widgets platform integrates symantec online services directly ui also new version reputation scan gives user clear insight loaded applications files safeweb facebook scans links wall verify safety links norton recovery tools added scanner interface start menu folder help restoring highly infected system backup restore functionality also improved passmark performance test 011 rated norton 360 5.0 fastest lightest all-in-one suite featured metered broadband modes easily remembers logins personal info protecting online identity theft version norton released september 5 2012 together newest norton antivirus norton internet security products described version-less symantec press release alluding automatic updates always keep software latest version specific version reference anywhere description software software compatible windows 8 version norton 360 features enhancements social networking protection anti-scam capabilities stronger networking defenses norton also introduced extra tune disk optimizer version 21 norton security suite released september 4 2013 together newest norton antivirus norton internet security products norton 360 antivirus solution developed sonar technology claims able detect threat block remove thanks three five layers shields threat monitoring threat removal network defense last one dealing online threats actually reach user ’ computer protection also granted analyzing behavior known menaces another important aspect derives stealth capabilities five shields work silently background performing scans updates back-ups automatically need whatsoever care important files browser protection download insight keen eye dangerous applications warning user eventual threats running computer version 22 released september 22 2014 release marketed norton security 2015 however norton 360 users able update v22 even norton retiring norton 360 brand appearance software identical norton security 2015 except product name top-left corner april 2019 symantec released new norton 360 emphasis new old legacy norton 360 remains retired product new norton 360 step norton security basically got replaced new product main change reflects besides security protection norton 360 provides secure vpn online privacy dark web monitoring powered lifelock safecam help block pc webcam takeovers new norton 360 comes several editions two standalone three bundle lifelock options norton 360 available norton 360 standard norton 360 premier edition norton 360 multi-device premier edition functions standard edition difference comes 25 gb online storage versus 2 gb included standard edition norton 360 multi-device actually three products one subscription norton 360 premier edition norton internet security mac® norton mobile security comparison norton 360 editions norton one shows features os coverage norton 360- gold edition credit card type 5 unique sets alpha-numeric key data reverse sold instructions go online install installation page norton 360 software sold purchased subscription stated period e.g one year software e.g firewall antivirus automatically disabled end subscription period unless new subscription purchased special edition norton 360 premier edition branded norton security suite available free pc customers comcast xfinity internet service difference norton 360 premier edition norton security suite latter include online storage feature norton internet security mac also available free comcast xfinity customers major version updates norton security suite typically occur 1 month norton 360 windows 8 consumer preview released february 29 2012 symantec announced norton antivirus internet security well newest norton 360 version 6 compatible windows 8 symantec compliance fbi whitelisted magic lantern keylogger developed fbi purpose magic lantern obtain passwords encrypted e-mail part criminal investigation magic lantern first reported media bob sullivan msnbc november 20 2001 ted bridis associated press magic lantern deployed e-mail attachment attachment opened trojan horse installed suspect computer trojan horse activated suspect uses pgp encryption often used increase security sent e-mail messages activated trojan horse log pgp password allows fbi decrypt user communications symantec major antivirus vendors whitelisted magic lantern rendering antivirus products including norton internet security incapable detecting magic lantern concerns include uncertainties magic lantern full potential whether hackers could subvert purposes outside jurisdiction law graham cluley technology consultant sophos said way knowing written fbi even ’ know whether used fbi commandeered third party another reaction came marc maiffret chief technical officer cofounder eeye digital security customers paying us service protect forms malicious code us law enforcement job make exceptions law enforcement malware tools fbi spokesman paul bresson response magic lantern needed court order deploy like technology projects tools deployed fbi would used pursuant appropriate legal process proponents magic lantern argue technology would allow law enforcement efficiently quickly decrypt messages protected encryption schemes implementing magic lantern require physical access suspect computer unlike carnivore predecessor magic lantern since physical access computer would require court order norton internet security windows versions criticized uninstalling completely leaving unnecessary files registry entries versions prior 3.0 also installed separate liveupdate program updates norton-branded software user must uninstall norton internet security liveupdate component manually liveupdate component purposely left behind update norton-branded products present symantec developed norton removal tool remove registry keys values along files folders uninstaller must run twice initially computer restart requiring second restart uninstallation remove subscription data preserved prevent users installing multiple trial copies norton 360 version 2.0 installed users encountered incompatibilities upgrading windows xp service pack 3 windows vista service pack 1 users report numerous invalid windows registry keys added tool named fixcss.exe resulting empty device manager missing devices wireless network adapters symantec initially blamed microsoft incompatibilities since accepted partial responsibility dave cole senior director product management acknowledged users running norton products experiencing problems said numbers small cole also said symantec done extensive testing products windows xp sp3 issue encountered cole blamed microsoft related xp sp3 microsoft recommended users contact windows customer support resolve problem symantec issued fix intended users upgrading symantec also recommends disabling tamper protection component 2008 release dubbed symprotect tool remove added registry entries available symantec sarah hicks symantec vice president consumer product management voiced concern windows vista 64-bit patchguard feature patchguard designed microsoft ensure integrity kernel part operating system interacts hardware rootkits may hide operating system kernel complicating removal mike dalton european president mcafee said decision build wall around kernel assumption ca n't breached ridiculous claiming microsoft preventing security vendors effectively protecting kernel promoting security product windows live onecare hicks said symantec mind competition onecare symantec later published white paper detailing patchguard instructions obtain patchguard exploit negotiations investigations antitrust regulators microsoft decided allow security vendors access kernel creating special api instructions norton 360 comes one-year subscription activated upon installation valid three home computers expiration subscription blocks access program updates shuts antivirus firewall well tools bundled password manager user saved passwords also inaccessible users often understand completely exposed pcs become infected viruses
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Computer security
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gridpp gridpp collaboration particle physicists computer scientists united kingdom cern manage maintain distributed computing grid across uk primary aim providing resources particle physicists working large hadron collider experiments cern funded uk science technology facilities council collaboration oversees major computing facility called tier1 rutherford appleton laboratory ral along four tier 2 organisations scotgrid northgrid southgrid londongrid formerly lt2 tier 2s geographically distributed composed computing clusters multiple institutes 2012 gridpp infrastructure spans 18 uk institutions major partner uk national grid initiative part european grid infrastructure original gridpp plan drawn late 2000 provide uk contribution lhc computing grid europeandatagrid project european grid infrastructure drive behind projects provide researchers working lhc experiments suitable computing resources extend use technology communities first gridpp proposal accepted pparc time uk funding council responsible funding particle physics related projects collaboration officially began 1 september 2001 £17m funding first phase gridpp 2001 2004 collaboration built uk testbed working prototype grid linked similar systems around world preparation use production infrastructure analysed real data wide variety experiments run around world different institutions 2004 extended till september 2007 bring proposed lhc switch date 2007 gridpp fully functioning production service lhc switch still year away september 2007 received extension stfc receiving £30m funding march 2011 gridpp fourth phase 2011–2014 received funding science technology facilities council stfc support lhc experiments users late 2011 project providing 29,000 cpus 25,000tb storage worldwide grid infrastructure uk universities institutions researchers working lhc members 2011 list follows scotgrid based across 3 main sites primarily supports on-going research within field particle physics entire environment monitored maintained developed dedicated teams site ensure fully operational system available end user communities londongrid joint collaboration 5 institutes london region provide high performance computing resources high energy physics community gridpp supports many disciplines projects list different experiments projects actively use gridpp resources gridpp originally created support experiments based cern using lhc 4 main experiments supported alongside experiments lhc gridpp also supports international high energy physics experiments include gridpp european grid infrastructure efforts supports many non-physics research disciplines
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Distributed computing architecture
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ncr vrx vrx acronym virtual resource executive proprietary operating system ncr criterion series later v-8000 series mainframe computers manufactured ncr corporation 1970s 1980s replaced b3 operating system originally distributed century series inherited many features b4 operating system high-end ncr century series computers vrx upgraded late 1980s 1990s become vrx/e use ncr 9800 series computers edward d. scott managed development team 150 software engineers developed vrx tom tang director engineering ncr responsible development entire criterion family computers product line achieved 1b revenue 300m profits ncr
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Operating systems
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gnumail gnumail free open-source cross-platform e-mail client based gnustep cocoa official mail client gnustep also used étoilé inspired nextmail next mail.app predecessor apple mail gnumail based mail handling framework pantomime furthermore gnumail demonstrates possible develop cross platform programs gnustep cocoa
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Internet protocols
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spdy spdy pronounced speedy deprecated open-specification networking protocol developed primarily google transporting web content spdy manipulates http traffic particular goals reducing web page load latency improving web security spdy achieves reduced latency compression multiplexing prioritization although depends combination network website deployment conditions name spdy trademark google acronym throughout process core developers spdy involved development http/2 including mike belshe roberto peon february 2015 google announced following recent final ratification http/2 standard support spdy would deprecated support spdy would withdrawn google removed spdy support google chrome 51 mozilla removed firefox 50 apple deprecated technology macos 10.14.4 ios 12.2. group developing spdy stated publicly working toward standardisation available internet draft first draft http/2 used spdy working base specification draft editing implementations spdy exist chromium mozilla firefox opera amazon silk internet explorer safari implementations chromium firefox open source software february 2015 google announced plans remove support spdy favor http/2 http/2 first discussed became apparent spdy gaining traction implementers like mozilla nginx showing significant improvements http/1.x call proposals selection process spdy chosen basis http/2 since number changes based discussion working group feedback implementers february 11 2016 google announced chrome would longer support spdy npn may 15 2016 anniversary rfc 7540 january 25 2019 apple announced spdy would deprecated favor http/2 would removed future releases goal spdy reduce web page load time achieved prioritizing multiplexing transfer web page subresources one connection per client required tls encryption nearly ubiquitous spdy implementations transmission headers gzip- deflate-compressed design contrast http headers sent human-readable text moreover servers may hint even push content instead awaiting individual requests resource web page spdy requires use ssl/tls tls extension alpn security also supports operation plain tcp requirement ssl security avoid incompatibility communication across proxy spdy replace http modifies way http requests responses sent wire means existing server-side applications used without modification spdy-compatible translation layer put place spdy effectively tunnel http https protocols sent spdy http requests processed tokenized simplified compressed example spdy endpoint keeps track headers sent past requests avoid resending headers changed must sent compressed ietf working group httpbis released draft http/2 spdy draft-mbelshe-httpbis-spdy-00 chosen starting point use within https spdy needs tls extension next protocol negotiation npn thus browser server support depends https library openssl 1.0.1 greater introduces npn patches add npn support also written nss tlslite spdy scheduled switch npn application-layer protocol negotiation alpn end 2014 security support provider interface sspi microsoft implemented npn extension tls implementation prevented spdy inclusion latest .net framework versions since spdy specification refined http/2 expected include spdy implementation one could expect microsoft release support http/2 finalized spdy versioned protocol control frames 15 dedicated bits indicate version session protocol approximately 7.1 websites support spdy fielded versions two popular web servers nginx apache major providers spdy traffic although latest version nginx removed spdy support compares adoption rate 8.1 newer http/2 protocol overtaken adoption spdy google services e.g google search gmail ssl-enabled services use spdy available google ads also served spdy-enabled servers brief history spdy support amongst major web players according w3techs spdy-enabled websites use nginx litespeed web server coming second
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Internet protocols
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java ee connector architecture java ee connector architecture jca java-based tool connecting application servers enterprise information systems eis part enterprise application integration eai solutions jdbc specifically used connect java ee applications databases jca generic architecture connection legacy systems jca developed java community process jsr 16 jca 1.0 jsr 112 jca 1.5 jsr 322 jca 1.6 j2ee version 1.3 requires application servers support jca version 1.0 j2ee version 1.4 requires application servers support jca version 1.5 java ee version 6 requires application servers support jca version 1.6 java ee connector architecture defines standard connecting compliant application server eis defines standard set system-level contracts java ee application server resource adapter system contracts defined version 1.0 java ee connector architecture described specification follows jca version 1.5 adds system contracts specification follows jca adapters built integrate various enterprise information system siebel systems sap ag great plains systems oracle applications etc siebel provides api integrate various platforms like java c++ .net visual basic etc java provides interface called 'java data bean jdb siebel adaptor provides data access via jdb api great plains systems provides interface called econnect integrate platforms sap provides interface java called sap java connector sap jco
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Programming language topics
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mocana mocana founded 2002 san francisco-based company focuses embedded system security industrial control systems internet things iot one main products iot security platform high-performance ultra-optimized os-independent high-assurance security solution device class decoupling security implementation rest application development allows easier development software devices comprising internet things numerous independent networked devices communicate various ways mocana originally launched embedded systems security company recently company shifted focus protecting mobile devices apps data mocana introduced products 2004 focus embedded systems security year company launched embedded security suite software product secure communications networked devices february 2005 based menlo park california company joined freescale semiconductor developers alliance program delivered group first security software 2008 mocana cited example independent company could provide security smartphones mocana ceo adrian turner published article san jose mercury news risks associated non-pc networked devices new york times reported mocana researchers discovered could hack best-selling internet-ready hdtv model unsettling ease highlighted opportunity criminals intercept information like credit card billing details media outlets across u.s. cited point coverage risks associated advances technology mocana sponsored 7th workshop rfid security privacy university massachusetts 2011 launched mobile application protection platform 2011 support android apps added ios app support 2012 following series funding round 2012 total investment mocana 47 million new ceo james isaacs replaced turner september 2013 interim ceo peter graham replaced isaacs april 2016 april 2016 mocana spun mobile security business blue cedar networks william diotte replaced graham ceo may 2016 mocana iot security platform security software solution embedded systems software provides cryptographic controls e.g authentication confidentiality encryption device data integrity verification embedded devices applications company also offers customizable user agreements optional fips 140-2 validated crypto engines access application source code required product design based assumption many assurances security device operating system may compromised obviates necessity infallible systemwide security policies addition mocana offers consulting services evaluating advising security threats networked devices mocana security technology used airplane in-flight entertainment systems medical devices battlefield communications automobile firmware cell phone carrier networks mocana senior analyst robert vamosi cited 2011 piece bloomberg businessweek comparing tech companies approaches security mocana investors include trident capital 2012 intel capital 2011 shasta ventures southern cross venture partners symantec 2010 august 2012 series total 47 million raised official web site mocana.com
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Computer security
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mushroom networks mushroom networks inc. privately held company san diego california mushroom networks founded 2004 electrical computer engineer rene l. cruz cahit akin rajesh mishra spin-off university california san diego ucsd got support von liebig center mushroom networks also received initial funding support itu ventures los angeles investment firm company solely focuses networking products utilizing broadband bonding technology various configurations products provide end-user appearance larger bandwidth aggregating multiple network services load balancing and/or channel bonding mushroom networks developed broadband bonding extensive research development
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Computer security
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chippewa operating system chippewa operating system often called cos discontinued operating system cdc 6600 supercomputer generally considered first super computer world chippewa initially developed experimental system also deployed cdc 6000 machines chippewa rather simple job control oriented system derived earlier cdc 3000 later influenced kronos scope name system based chippewa falls research development center cdc wisconsin operating system control data corporation distinct preceded cray operating system also called cos cray
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Operating systems
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parallel line internet protocol parallel line internet protocol plip computer networking protocol direct computer-to-computer communications using parallel port normally used connections printer parallel line internet protocol provides link layer services internet protocol protocol used forming small local area networks large computer networks internet enabling computers without standard dedicated networking hardware ethernet older parallel port devices communicate internet protocol suite standards-based networking model software specification forming small large computer networks local area networks global communication systems internet usually implemented software hardware features use ethernet network interface cards cabling networking switches hubs early personal computers ethernet hardware included design bus adapters initially expensive solution use time standard parallel port typically used connection printer similar output device ports two computers connected so-called null-printer cable sometimes called laplink cable laplink cable connects five output pins parallel port five input pins opposing port direction due lack internal timing parallel ports synchronization implemented via software handshaking four five pins used data transfer one used synchronization logical values pins read written directly software via input output instruction method connect bidirectional data lines two devices order avoid lines active time status lines error slct papout ack busy one device connected data pins d0 d4 respectively transmission byte accomplished dividing two nibbles four bits nibble transmitted setting four data lines according four nibble bits toggling acknowledge line toggle indicates receiving host nibble ready read receiving host read nibble toggles synchronization line tell transmitter nibble read new one may sent hosts use toggle acknowledge lines indicate read write operation performed result host wait toggle host proceeding new operation example transfer nibble 0010 proceeds follows transmitter detects toggle procedure repeated next nibble internet protocol packets sent line encapsulating plip packets transmission line encapsulated packet following structure length checksum calculated second third field actual total length packet three length reported first two bytes packet analogous feature serial communications ports serial line internet protocol slip using null-modem cables allows transfer four bits time rather one generally works higher bitrates method based crynwr standard devised russ nelson ethernet may also used direct computer-to-computer communications method using ethernet crossover cable point-to-point connections usb host-to-host bridges cables also used transfer files two computers network necessary available
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Internet protocols
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robert bernecky robert bob bernecky canadian computer scientist notable designer implementer apl apl career started i.p sharp associates ipsa 1971 bernecky first published apl work concerned speeding iota epsilon index-of membership primitives functions orders magnitude ipsa colleague roger hui dick lathwell eugene mcdonnell roger moore arthur whitney apl inventor ken iverson continued ipsa acquired reuters 1987-04-01 left reuters 1990 found snake island research works apl compiler parallel-processing technology day bernecky holds master science degree university toronto
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Programming language topics
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database system concepts database system concepts abraham silberschatz hank korth s. sudarshan best-selling textbook database systems often called sailboat book cover sailboats since first edition first edition cover number sailboats labelled names various database models boats sailing desert island towards tropical island wind pushes away prevents arrival book currently 7th edition released march 2019 copyright year 2020 previous editions released 2010 6th edition 2005 5th edition 2001 4th edition 1997 3rd edition 1991 2nd edition 1986 1st edition 1st 2nd editions book authored hank korth abraham silberschatz s. sudarshan co-author since third edition various editions book translated numerous languages including chinese korean portuguese spanish official website book db-book.com
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Databases
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skytap skytap inc. private company based seattle washington offering public service cloud computing skytap cloud provides self-service access environments learning developing testing training running enterprise applications company founded illumita 2006 renamed 2008 skytap also product ibm offers public product enables enterprises migrate modernize core business applications ibm product also available la region countries ·argentina ·peru ·chile ·colombia illumita founded brian bershad hank levy steve gribble trio university washington professors done research virtualization cloud computing graduate student david richardson illumita changed name skytap 2008 launched first product skytap virtual lab april year skytap received early funding washington research foundation 2011 organization funded insight venture partners madrona venture group ignition partners bezos expeditions openview venture partners skytap virtual lab expanded scope renamed skytap cloud 2008 2011 skytap best vmworld award public/hybrid cloud computing technologies category skytap cloud company named annual top cloud computing provider lists deloitte geekwire seattle business magazine puget sound business journal march 2018 skytap added john ludeman leadership team svp engineering ludeman joined skytap 30 years engineering experience microsoft skytap cloud enterprise service purpose-built development testing complex applications users import existing virtualized applications build new applications cloud environments accessed modern web browser rest-based application programming interface api command-line interface cli application lifecycle management tool jenkins visual studio tfs etc skytap cloud uses browser-based interface system management hosts library pre-configured virtual machine images using either images imported vms users create sharable configurations one machines securely connect active machines via proprietary html5-based browser client
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Distributed computing architecture
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netwide assembler netwide assembler nasm assembler disassembler intel x86 architecture used write 16-bit 32-bit ia-32 64-bit x86-64 programs nasm considered one popular assemblers linux nasm originally written simon tatham assistance julian hall maintained small team led h. peter anvin open-source software released terms simplified 2-clause bsd license nasm output several binary formats including coff omf a.out executable linkable format elf mach-o binary file .bin binary disk image used compile operating systems though position-independent code supported elf object files nasm also binary format called rdoff variety output formats allows retargeting programs virtually x86 operating system os also nasm create flat binary files usable write boot loaders read-only memory rom images various facets os development nasm run non-x86 platforms cross assembler powerpc sparc though generate programs usable machines nasm uses variant intel assembly syntax instead syntax also avoids features automatic generation segment overrides related assume directive used masm compatible assemblers hello world program dos operating system equivalent program linux example similar program microsoft windows 64-bit program apple os x inputs keystroke shows screen nasm principally outputs object files generally executable exception flat binaries e.g. .com inherently limited modern use translate object files executable programs appropriate linker must used visual studio link utility windows ld unix-like systems first release version 0.90 released october 1996 28 november 2007 version 2.00 released adding support x86-64 extensions development versions uploaded sourceforge.net instead checked project git repository binary snapshots available project web page search engine nasm documentation also available july 2009 version 2.07 nasm released simplified 2-clause bsd license previously nasm licensed lgpl led development yasm complete rewrite nasm new bsd license yasm offered support x86-64 earlier nasm also added support gnu assembler syntax relocatable dynamic object file format rdoff used developers test integrity nasm object file output abilities based heavily internal structure nasm essentially consisting header containing serialization output driver function calls followed array sections containing executable code data tools using format including linker loader included nasm distribution version 0.90 released october 1996 nasm supported output flat-format executable files e.g. dos com files version 0.90 simon tatham added support object-file output interface dos .obj files 16-bit code nasm thus lacked 32-bit object format address lack exercise learn object-file interface developer julian hall put together first version rdoff released nasm version 0.91 since initial version one major update rdoff format added record-length indicator header record allowing programs skip records whose format recognise support multiple segments rdoff1 supported three segments text data bss containing uninitialized data
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Operating systems
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scriptbasic scriptbasic scripting language variant basic source interpreter available c program lgpl license scriptbasic generates intermediary code interpreted runtime environment scriptbasic available windows unix mac os x may embedded programs well create standalone executable files runtime library linked executable available precompiled binaries setup.exe windows uninstall also supported dpkg rpm linux source code form language interpreter fully documented users guide available text html html help tex texi pdf formats scriptbasic developed since 1999 reached fairly matured state terms functions stability precompiled version available windows linux includes command line version standalone web server basic choice developers seek basic variant runs unix well windows mac os x intel basic embeddable option compile applications small footprint executable scriptbasic open interface module developers several external modules developed developer scriptbasic well developers include data base connection handling various database systems mysql postgresql odbc berkeley db others binding library curl png graphics gtk+ graphical user interface sockets regular expressions thread support data compression cgi scriptbasic also open interface preprocessor developers modules may act run-time also compile time thus making possible alter language currently single preprocessor delivers debugger functionality lets basic programmer run basic program line line examine variable contents set break points usual debugging features debugger supports command line version also web server implementation allowing full interactive debugging cgi applications basic architecture interpreter internally object oriented provides clean well documented interface embed interpreter application written c c++ whole source code extensively documented commented outstanding feature compared embeddable script language implementations slides html format english narration realaudio format also available get jump start learning architecture module preprocessor embedding developments scriptbasic supported forum
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Programming language topics
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spectravideo spectravideo international svi american computer manufacturer software house originally called spectravision company founded harry fox 1981 company produced video games software vic-20 home computer atari 2600 home video game console computemate peripheral computers compatible microsoft msx ibm pc company ceased operations 1988 spectravision founded 1981 harry fox alex weiss distributor computer games contracting external developers write software main products gaming cartridges atari 2600 vcs colecovision commodore vic-20 also made world first ergonomic joystick quickshot late 1982 company renamed spectravideo due naming conflict oncommand hotel tv system called spectravision early 1980s company developed 11 games atari 2600 including several titles rarity chase chuckwagon mangia bumper bash titles available columbia house music club company first attempt computer add-on atari 2600 called spectravideo compumate membrane keyboard simple programmability spectravideo first real computers sv-318 sv-328 released 1983 powered z80 3.6 mhz differed amount ram sv-318 32kb sv-328 80kb total 16kb reserved video keyboard style main operating system residing rom version microsoft extended basic computer equipped floppy drive user option boot cp/m instead two computers precedent msx fully compatible standard though changes made design create msx minor system wide range optional hardware example adapter making possible run colecovision games svi may 1983 spectravideo went public sale 1 million shares stock 6.25 per share initial public offering underwritten brokerage d. h. blair co however spectravideo quickly ran trouble december 1983 stock fallen 75 cents per share march 1984 company agreed sell 60 stake hong kong-based bondwell holding deal would also required resignation president harry fox vice-president alex weiss deal set aside spectravideo unable restructure 2.6 million worth debt another deal fanon courier u.s.a. inc. would purchased 80 company struck july fanon courier deal similarly fell fox resigned president september bondwell holding purchasing half company stock installing bondwell vice-president christopher chan new president later computer spectravideo svi-728 made msx compatible svi-738 also msx compatible came built-in 360 kb 3.5 floppy drive last computer produced spectravideo svi-838 also known spectravideo x'press 16 pc msx2 device today spectravideo name used uk-based company called spectravideo plc formerly known ash newman company founded 1977 bought spectravideo brand name bondwell svi owner 1988 sell range logic3 branded products connection old spectravideo products
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Computer architecture
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scott forstall scott forstall born 1969 american software engineer best known leading original software development team iphone ipad broadway producer best known co-producing tony award-winning fun home eclipsed wife spent career first next apple senior vice president svp ios software apple inc. 2007 october 2012 forstall grew middle-class family kitsap county washington second-born three boys registered-nurse mother jeanne engineer father tom forstall older brother bruce also senior software design engineer microsoft gifted student skills programming came easily difficult others forstall qualified advanced-placement science math class junior high school gained experience programming apple iie computers skipped forward year entering olympic high school bremerton washington early classmates recall immersion competitive chess history general knowledge occasion competing state level achieved 4.0 gpa earned position valedictorian position shared classmate molly brown would later become wife established goal designer high-tech electronics equipment proclaimed interview local newspaper enrolling stanford university graduated 1991 degree symbolic systems next year received master degree computer science also stanford time stanford forstall member phi kappa psi fraternity forstall joined steve jobs next 1992 stayed purchased apple 1997 forstall placed charge designing user interfaces reinvigorated macintosh line 2000 forstall became leading designer mac new aqua user interface known water-themed visual cues translucent icons reflections making rising star company promoted svp january 2003 period supervised creation safari web browser melton senior developer safari team credited forstall willing trust instincts team respecting ability develop browser secret 2005 jobs began planning iphone choice either shrink mac would epic feat engineering enlarge ipod jobs favored former approach pitted macintosh ipod team led forstall tony fadell respectively internal competition forstall fierce competition create ios decision enabled success iphone platform third-party developers using well-known desktop operating system basis allowed many third-party mac developers write software iphone minimal retraining forstall also responsible creating software developer kit programmers build iphone apps well app store within itunes 2006 forstall became responsible mac os x releases avie tevanian stepped company chief software technology officer named svp iphone software forstall received credit ran ios mobile software team like clockwork widely respected ability perform pressure spoken publicly apple worldwide developers conferences including talks mac os x leopard 2006 iphone software development 2008 later release iphone os 2.0 iphone 3g january 27 2010 apple 2010 ipad keynote wwdc 2011 forstall introduced ios 5 forstall also appears ios 5 video narrating three-quarters clip almost every major apple ios special event let talk iphone event launching iphone 4s took stage demonstrate phone siri voice recognition technology originally developed sri international aftermath release ios 6 september 19 2012 proved troubled period apple newly introduced maps application completely designed in-house apple criticized underdeveloped buggy lacking detail addition clock app used design based trademarked swiss railway clock apple failed license forcing apple pay swiss railways reported 21 million compensation october apple reported third-quarter results revenues profits grew less predicted second quarter row company missed analysts expectations october 29 2012 apple announced press release scott forstall leaving apple 2013 serve advisor ceo tim cook interim forstall duties divided among four apple executives design svp jonathan ive assumed leadership apple human interface team craig federighi became new head ios software engineering services chief eddy cue took responsibilities maps siri bob mansfield previously svp hardware engineering unretired oversee new technology group day john browett svp retail dismissed immediately six months job neither forstall apple executive commented publicly departure beyond initial press statement generally presumed forstall left position involuntarily information reasons departure therefore come anonymous sources cook aim since becoming ceo reported building culture harmony meant weeding people disagreeable personalities—people jobs tolerated even held close like forstall although former apple senior engineer michael lopp believes apple ability innovate came tension disagreement steve jobs referred decider final say products features ceo reportedly keeping strong personalities apple check always casting winning vote last word jobs death many executive conflicts became public forstall poor relationship ive mansfield could meeting unless cook mediated reportedly forstall ive cooperate level forced choose two cook reportedly chose retain ive since forstall collaborative forstall close referred mini-steve jobs jobs death left forstall without protector forstall also referred ceo-in-waiting fortune magazine book inside apple written adam lashinsky profile made unpopular apple forstall said responsible departure jean-marie hullot cto applications 2005 tony fadell svp hardware engineering 2008 fadell remarked interview bbc forstall firing justified got deserved jon rubinstein fadell predecessor svp hardware also strained relationship forstall jobs death 2011 reported forstall trying gather power challenge cook siri intelligent personal voice assistant forstall introduced september 2011 received mixed reception observers regarding flop forstall vigorously criticized new maps app introduced ios 6 received criticism inaccuracies apple standards according adam lashinsky fortune apple issued formal apology errors maps forstall refused sign long-standing practice apple forstall directly responsible individual maps refusal sign apology convinced cook forstall go forstall skeuomorphic design style strongly advocated former ceo steve jobs reported also controversial divided apple design team 2012 interview ive head hardware design refused comment ios user interface terms elements 're talking 'm really connected forstall make public appearances departure apple number years report december 2013 said concentrating travel advising charities providing informal advice small companies april 17 2015 forstall made first tweet revealed co-producer broadway version musical fun home first public appearance since departing apple 2012 june 7 2015 forstall-produced musical five awards tonys forstall reportedly working advisor snap inc. june 20 2017 forstall gave first public interview leaving apple interviewed computer history museum john markoff creation iphone 10th anniversary sales launch
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Operating systems
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puffs netbsd pass-to-userspace framework file system puffs netbsd kernel subsystem developed running filesystems userspace added netbsd 5.0 release ported dragonfly bsd 3.2 release netbsd 5.0 puffs includes refuse reimplementation libfuse high-level interface filesystems use low-level libfuse interface kernel fuse interface supported refuse netbsd 6.0 addresses limitation perfuse new compatibility layer emulates fuse kernel interface
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Operating systems
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intime intime pronounced time real time operation system rtos family based 32 bit rtos conceived run time-critical operations cycle-times low 50μs intime rtos runs single-core hyper-threaded multi-core x86 pc platform intel amd supports two binary compatible usage configurations intime windows intime rtos runs alongside microsoft® windows® intime distributed rtos intime runs stand-alone rtos like irmx predecessors intime real-time operating system like dosrmx irmx windows runs concurrently general-purpose operating system single hardware platform intime 1.0 originally introduced 1997 conjunction windows nt operating system since upgraded include support subsequent protected-mode microsoft windows platforms windows xp windows 10 intime also used stand-alone rtos intime binaries able run unchanged running stand-alone node intime rtos unlike windows intime run intel 80386 equivalent processor current versions windows operating system generally require least pentium level processor order boot execute spinning radisys 2000 development work intime continued tenasys corporation 2003 tenasys released version 2.2 intime notable features version 2.2 include
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Operating systems
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spanish data protection agency spanish data protection agency aepd agency government spain aepd established royal decree 428/1993 26 march amended organic law 15/1999 protection personal data amendment implemented directive 95/46/ec agency created context spanish constitution 1978 article 18.4 stating law shall restrict use informatics order protect honour personal family privacy spanish citizens well full exercise rights elaborated organic law 5/1992 aepd public law authority enjoying absolute independence public administration responsible response latter point aepd advocated aepd conducting anti-spam investigations since 2004 collaborating foreign agencies united states federal trade commission aepd come conflict google information gathered wi-fi networks google street view images taken asserting verified data location wifi networks identification owners personal data diverse nature communications names surnames messages associated accounts message services user codes passwords collected also demanded removal approximately 90 names search results claiming right forgotten google contesting actions
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Computer security
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duqu 2.0 duqu 2.0 version malware reported 2015 infected computers hotels austria switzerland sites international negotiations iran nuclear program economic sanctions malware infected kaspersky lab months without knowledge believed work unit 8200 kaspersky discovered malware symantec confirmed findings malware variant duqu duqu variant stuxnet software linked israel according guardian software used three zero-day exploits would required funding organization consistent government intelligence agency according kaspersky philosophy way thinking “ duqu 2.0 ” group generation ahead anything seen advanced persistent threats world
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Computer security
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variant object variant objects context http objects served origin content server type transmitted data variation i.e uncompressed compressed different languages etc. http/1.1 1997–1999 introduces content/accept headers used http requests responses state variant data presented client server
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Internet protocols
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link layer computer networking link layer lowest layer internet protocol suite networking architecture internet described rfc 1122 rfc 1123 link layer group methods communications protocols operate link host physically connected link physical logical network component used interconnect hosts nodes network link protocol suite methods standards operate adjacent network nodes local area network segment wide area network connection despite different semantics layering tcp/ip osi link layer sometimes described combination data link layer layer 2 physical layer layer 1 osi model however layers tcp/ip descriptions operating scopes application host-to-host network link detailed prescriptions operating procedures data semantics networking technologies rfc 1122 exemplifies local area network protocols ethernet ieee 802 framing protocols point-to-point protocol ppp belong link layer local area networking standards ethernet ieee 802 specifications use terminology seven-layer osi model rather tcp/ip model tcp/ip model general consider physical specifications rather assumes working network infrastructure deliver media level frames link therefore rfc 1122 rfc 1123 definition tcp/ip model discuss hardware issues physical data transmission set standards aspects textbook authors supported interpretation physical data transmission aspects part link layer others assumed physical data transmission standards considered communication protocols part tcp/ip model authors assume hardware layer physical layer link layer several adopt osi term data link layer instead link layer modified description layering predecessor tcp/ip model arpanet reference model rfc 908 1982 aspects link layer referred several poorly defined terms network-access layer network-access protocol well network layer next higher layer called internetwork layer modern text books network-interface layer host-to-network layer network-access layer occur synonyms either link layer data link layer often including physical layer link layer tcp/ip model descriptive realm networking protocols operate local network segment link host connected protocol packets routed networks link layer includes protocols define communication local on-link network nodes fulfill purpose maintaining link states local nodes local network topology usually use protocols based framing packets specific link types core protocols specified internet engineering task force ietf layer address resolution protocol arp reverse address resolution protocol rarp neighbor discovery protocol ndp facility delivering similar functionality arp ipv6 since advent ipv6 open shortest path first ospf considered operate link level well although ipv4 version protocol considered internet layer is-is rfc 1142 another link-state routing protocol fits layer considering tcp/ip model however developed within osi reference stack layer 2 protocol internet standard link layer tcp/ip model often compared directly combination data link layer physical layer open systems interconnection osi protocol stack although congruent degree technical coverage protocols identical link layer tcp/ip still wider scope principle different concept terminology classification may observed certain protocols address resolution protocol arp confined link layer tcp/ip model often said fit osi data link layer network layer general direct strict comparisons avoided layering tcp/ip principal design criterion general considered harmful rfc 3439 another term sometimes encountered network access layer tries suggest closeness layer physical network however use misleading non-standard since link layer implies functions wider scope network access important link layer protocols used probe topology local network discover routers neighboring hosts i.e functions go well beyond network access
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Internet protocols
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firefox monitor firefox monitor online service developed mozilla launched september 25 2018 informs users email address passwords used leaked data breaches using database provided pwned
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Computer security
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symobi symobi system mobile applications proprietary modern mobile real-time operating system developed german company miray software since 2002 partly cooperation research team prof. dr. uwe baumgarten technical university munich graphical operating system designed area embedded mobile systems also often used pcs end users field industry basis symobi message-oriented operating system µnos part based real-time microkernel sphere µnos offers communication message passing processes basic operating system service processes application processes using integrated process manager lowest level responsibility sphere microkernel implement enforce security mechanisms resource management real-time symobi additionally offers complete graphical operating system environment system services consistent graphical user interface well standard programs drivers symobi combines features different fields application one operating system modern operating system offers separated isolated processes light-weight threads dynamic libraries like windows linux unix example area mobile embedded operating systems low resource requirement support mobile devices resembles systems like windows ce symbianos palm os conventional real-time operating systems like qnx vxworks shares real-time ability support different processor architectures development sphere µnos symobi based ideas work konrad foikis michael haunreiter founders company miray software initiated schooldays even started studying computer science basic concept combine useful necessary features like real-time portability modern characteristics like microkernel inter-process communication etc form stable reliable operating system originally supposed serve basis different application programs developed foikis haunreiter studies 2000 konrad foikis michael haunreiter founded company miray software realised µnos suited far use cooperation tu munich already evolved two years later 2006 first official version symobi completed autumn year introduced professional circles systems exhibition single-core multi-core symobi suited hand-held products portable communicators internet appliances well consumer appliances set-top boxes home gateways games consoles furthermore used areas automotive control infotainment systems industrial control systems motion control process control point sale cashier systems ticket machines information terminals operating system stands real-time microkernel multi-processor ability furthermore portable therefore bound specific hardware platforms symobi inter-process communication guarantees security flexibility modern architecture runs low resource requirements processor system memory system offers java-vm area standard appliances operating system yet widely spread rudimentary posix support restricted hardware support drivers addition symobi open source operating system present offer office applications email functions web browser
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Operating systems
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george necula george ciprian necula romanian computer scientist engineer google former professor university california berkeley research area programming languages software engineering particular focus software verification formal methods best known ph.d. thesis work first describing proof-carrying code work received 2007 sigplan influential popl paper award originally baia mare romania necula attended polytechnic university bucharest coming carnegie mellon university united states complete ph.d. programming languages researcher peter lee ph.d. thesis first describing proof-carrying code influential mechanism allow untrusted machine code run safely without performance overhead joined faculty university california berkeley 1998 recently necula work focused open-source analysis verification transformation tools c including c intermediate language cil ccured deputy c intermediate language cil simplified subset c programming language well set tools transforming c programs language several tools use cil way access c abstract syntax tree programs frama-c framework analyze c programs compcert c compiler proven coq necula fellow okawa foundation alfred p. sloan foundation see sloan fellowship received grace murray hopper award 2001 national science foundation career award 1999 acm sigops hall fame award 2006
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Programming language topics
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android eclair android eclair codename android mobile operating system developed google fifth operating system android longer supported versions 2.0 2.1 unveiled october 26 2009 android 2.1 builds upon significant changes made android 1.6 donut default home screen eclair displays persistent google search bar across top screen camera app also redesigned numerous new camera features including flash support digital zoom scene mode white balance color effect macro focus photo gallery app also contains basic photo editing tools version also included addition live wallpapers allowing animation home-screen background images show movement speech-to-text first introduced replacing comma key android eclair inherits platform additions donut release ability search saved sms mms messages improved google maps 3.1.2 exchange support email app operating system also provides improved typing speed virtual keyboard along new accessibility calendar virtual private network apis internet browsing android eclair also adds support html5 refreshed browser ui bookmark thumbnails double-tap zoom
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Operating systems
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bomberman 1983 video game nes/famicom release eponymous character bomberman robot must find way maze avoiding enemies doors leading maze rooms found rocks bomberman must destroy bombs items help improve bomberman bombs fire ability improves blast range bombs bomberman turn human escapes reaches surface game 50 levels total original home computer games basic different rules bomberman written 1980 purely serve tech demo hudson soft basic compiler basic version game given small-scale release japanese pcs 1983 european pcs following year bomberman known nes/famicom version released japan december 19 1985 north america 1987 hudson soft director research development shinichi nakamoto commented 1995 interview personally believe famicom version bomberman one version game version ported back msx following year bomberman special bomberman appearance game hudson soft re-used enemy graphic taken 1984 nes/famicom port broderbund lode runner early version bomberman famous design robotic anime-like character pink antenna game also released game boy game b mode game atomic punk 2004 version bomberman re-released game boy advance part famicom mini series japan classic nes series north america europe released year n-gage remake/update also released sony playstation entitled bomberman japan europe renamed bomberman party edition us version features port original version single-player game well revised updated version pre-rendered 3d graphics contemporary audio updated graphics audio also used multiplayer aspect game
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Computer architecture
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name binding programming languages name binding association entities data and/or code identifiers identifier bound object said reference object machine languages built-in notion identifiers name-object bindings service notation programmer implemented programming languages binding intimately connected scoping scope determines names bind objects – locations program code lexically one possible execution paths temporally use identifier codice_1 context establishes binding codice_1 called binding defining occurrence occurrences e.g. expressions assignments subprogram calls identifier stands bound occurrences called applied occurrences example static binding direct c function call function referenced identifier change runtime example dynamic binding dynamic dispatch c++ virtual method call since specific type polymorphic object known runtime general executed function dynamically bound take example following java code codice_3 interface codice_4 must refer subtype reference codice_5 codice_6 subtype codice_3 actual method referenced codice_8 known runtime c instance dynamic binding may call function pointed variable expression function pointer type whose value unknown actually gets evaluated run-time rebinding confused mutation consider following java code identifier codice_4 initially references nothing uninitialized rebound reference object linked list strings linked list referenced codice_4 mutated adding string list lastly codice_4 rebound codice_12 late static binding variant binding somewhere static dynamic binding consider following php example example php interpreter binds keyword codice_13 inside codice_14 class codice_15 call codice_16 produces string hello semantics codice_17 based late static binding result would bye beginning php version 5.3 late static binding supported specifically codice_17 changed codice_19 shown following block keyword codice_20 would bound runtime result call codice_16 would bye
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Programming language topics
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gnu guile gnu ubiquitous intelligent language extensions gnu guile preferred extension language system gnu project features implementation programming language scheme first version released 1993 addition large parts scheme standards guile scheme includes modularized extensions many different programming tasks extending programs guile offers libguile allows language embedded programs integrated closely c language application programming interface api similarly new data types subroutines defined c api made available extensions guile guile used programs gnucash lilypond gnu guix guix system distribution guixsd gnu debugger guile scheme general-purpose high-level programming language whose flexibility allows expressing concepts fewer lines code would possible languages c. example hygienic macro system allows adding domain specific syntax-elements without modifying guile guile implements scheme standard r5rs r6rs several scheme requests implementation srfi many extensions core idea guile scheme developer implements critical algorithms data structures c c++ exports functions types use interpreted code application becomes library primitives orchestrated interpreter combining efficiency compiled code flexibility interpretation thus guile scheme languages implemented guile extended new data types subroutines implemented c api standard distribution offers modules portable operating system interface posix system calls scheduling foreign function interface s-expression based xml processing sxml sxpath sxslt http world wide web apis delimited continuations array programming functionality guile programs use facilities slib portable scheme library using continuations call/cc requirement scheme standard guile copies execution stack heap back foreign code may pointers scheme objects guile uses conservative boehm–demers–weiser bdw garbage collector guile manual gives details inception early history language brief summary follows success emacs free software community highly extensible customizable application via extension partly implementation language emacs lisp community began consider design strategy could apply rest gnu system tom lord initially began work embeddable language runtime named gnu extension language gel based aubrey jaffer scheme implementation scm turn based george carrette siod lord convinced richard stallman make gel official extension language gnu project based argument scheme cleaner lisp dialect emacs lisp gel could evolve implement languages runtime namely emacs lisp lord discovered gel naming conflict another programming language solicited suggestions new name several contributions several usenet newsgroups lord controversially chose guile suggestion lee thomas development guile gel public release extension language tcl gaining popularity pushed universal extension language stallman saw tcl underpowered extension language posted criticism comp.lang.tcl newsgroup initiated flamewar known tcl war since public announcement guile project coincided tcl debate become common misconception guile began reaction initial release guile development languished many years 2009–2010 saw major improvements guile 2.0 released 2011 new compiler infrastructure virtual machine implementation switch boehm–demers–weiser garbage collector many improvements guile scheme language major changes one goals guile allow languages used alongside scheme guile would effectively language-neutral runtime environment various attempts made past versions dialect scheme essentially differing c-like syntax translation emacs lisp tcl converter motivated tkwww something roughly resembling language logo version 2.0 project successfully transitioned compiler tower approach allowing definition compilers one language another typically higher-level one lower-level intermediate representation eventually virtual machine bytecode native machine code several past unfinished attempts replace supplement emacs emacs lisp elisp extension language guile parallel efforts supporting languages guile version 2.0 guile new attempt implementing elisp guile compiler tower replacing emacs elisp implementation libguile begun made significant progress google summer code projects guile-based emacs could offer better execution performance emacs lisp support new emacs lisp language features easily make guile libraries written programming languages available emacs lisp code allow writing emacs extensions programming languages supported guile remaining fully backward compatible existing emacs lisp code bases implementation reached stage guile emacs able reliably run emacs lisp code remaining problems possible problems involve different internal representation emacs lisp strings scheme strings difference emacs lisp scheme treat boolean false empty list objects emacs lisp macros integrating scheme emacs lisp designed concurrency portability guile platforms supported emacs concerns raised emacs community include relative sizes emacs guile communities whether would cause splitting community emacs extensible programming languages emacs lisp
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Programming language topics
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compile time computer science compile time refers either operations performed compiler compile-time operations programming language requirements must met source code successfully compiled compile-time requirements properties program reasoned compilation compile time refers time duration statements written programming language checked errors operations performed compile time usually include syntax analysis various kinds semantic analysis e.g. type checks instantiation template code generation programming language definitions usually specify compile time requirements source code must meet successfully compiled example languages may stipulate amount storage required types variables deduced properties program reasoned compile time include range-checks e.g. proving array index exceed array bounds deadlock freedom concurrent languages timings e.g. proving sequence code takes allocated amount time compile time occurs link time output one compiled files joined together runtime program executed programming languages may necessary compilation linking occur runtime trade-off compile-time link-time many compile time operations deferred link-time without incurring extra run-time compile time also refer amount time required compilation
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Programming language topics
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data processing iran co. data processing iran company dpi computer technology consulting corporation headquartered tehran iran dpi currently largest technology provider iran dpi manufactures sells computer hardware software focus latter offers infrastructure services hosting services consulting services areas ranging mainframe computers nanotechnology company also offers series internet-related services namely dedicated servers colocation services web hosting services shared hosting shared mail dns recording domain registration services managed services including network services security solutions managed application services storage backup solutions monitoring reporting professional services dpi established 1959 regional branch ibm corporation company operated subsidiary 1981 ibm operations iran ceded iranian government 2001 dpi became private company listed tehran stock exchange company history dpi signed numerous technology-sharing agreements software companies including mindscape dataproducts hypercom current members board directors dpi
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Distributed computing architecture
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social jacking social jacking malicious technique tricking users clicking vulnerable buttons compromise showing false appearing pages mixture click jacking technique breach browser security social engineering may also referred user interface disguising method variant click jacking method original page vulnerable page loaded using iframe tag unnecessary contents webpage displayed iframe removed placing white background div tag elements using absolute positioning property using css thus unnecessary information displayed vulnerable page removed buttons links alone made visible user additional social engineering messages like click button get access get reward displayed iframe tag user made click visible button without knowing happens clicks button prevention methods quite tough user identifying analyzing webpages click anonymous links buttons social jacking easily implemented using google web toolkit design webpage using wysiwyg gui builder drag white background colored panel iframe window thus hiding unnecessary information revealing vulnerable buttons alone
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Computer security
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user space modern computer operating system usually segregates virtual memory kernel space user space primarily separation serves provide memory protection hardware protection malicious errant software behaviour kernel space strictly reserved running privileged operating system kernel kernel extensions device drivers contrast user space memory area application software drivers execute term userland user space refers code runs outside operating system kernel userland usually refers various programs libraries operating system uses interact kernel software performs input/output manipulates file system objects application software etc user space process normally runs virtual memory space unless explicitly allowed access memory processes basis memory protection today mainstream operating systems building block privilege separation separate user mode also used build efficient virtual machines – see popek goldberg virtualization requirements enough privileges processes request kernel map part another process memory space case debuggers programs also request shared memory regions processes although techniques also available allow inter-process communication common way implementing user mode separate kernel mode involves operating system protection rings another approach taken experimental operating systems single address space software rely programming language semantics make sure arbitrary memory accessed – applications simply acquire references objects allowed access approach implemented jxos unununium well microsoft singularity research project
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Operating systems
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korea internet amp security agency korea internet security agency 한국인터넷진흥원 kisa ministry science ict sub-organization dealing allocation maintenance south korea ipv4/ipv6 address space related whois information autonomous system numbers .kr country code top-level domain cctld also responsible cybersecurity internet within south korea runs korea computer emergency response team coordination center a.k.a krcert/cc private sector country roles include limited promotion safe internet usage internet culture detecting analyzing malware/virus web privacy protection operating root ca education internet cybersecurity various cybersecurity issues organization created july 2009 three different agencies merged one organization korea information security agency kisa national internet development agency nida korean international cooperation agency kiica kisa internet information security promotion organization korea aim improve global competitiveness korea ’ internet industry kisa set ‘ internet promotion ’ future ‘ information security ’ safety primary tasks focusing enhancing information security capacity korea ’ ict industry expanding global cooperative partnership based k-ict security development strategy krcert/cc internal division kisa csirt national responsibility focal point contact korea international cybersecurity incident handling cooperates interacts locally national cyber security center national intelligence service korea relevant stakeholders including local internet service providers cybersecurity vendors also interacts national csirts global cybersecurity vendors krcert/cc memberships asia pacific computer emergency response team apcert forum incident response security teams first kisa also 4 regional offices overseas located oman middle east region indonesia southeast asia costa rica latin america caribbean tanzania africa roles facilitate inter-governmental cooperation including b2b/b2g/g2b introduce talented korean cybersecurity enterprises global market
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Computer security
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fs-a1wsx panasonic fs-a1wsx last msx2+ made panasonic successor fs-a1wx incorporated changes like s-video output tape support color printer support improved a1 internal cockpit software kanji color word processor contrary msx2+ systems panasonic fs-a1 used z-80 compatible msx-engine t9769x could switched via software 6 mhz model supported 256 kb ram little soldering 512 kb also possible complicated modification
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Computer architecture
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lga 1151 lga 1151 also known socket h4 intel microprocessor compatible socket comes two distinct versions first revision supports intel skylake kaby lake cpus second revision supports coffee lake cpus exclusively lga 1151 designed replacement lga 1150 known socket h3 lga 1151 1151 protruding pins make contact pads processor fully integrated voltage regulator i.e voltage regulator integrated cpu die introduced haswell broadwell moved motherboard motherboards first revision socket support solely ddr4 memory lesser number support ddr3 l memory least number slots ddr4 ddr3 l one memory type installed unidimm support enabling either type memory placed dimm rather separate ddr3 ddr4 dimms second revision socket motherboards support ddr4 memory skylake kaby lake coffee lake chipsets support vt-d intel rapid storage technology intel clear video technology intel wireless display technology appropriate cpu required motherboards lga 1151 socket support varying video outputs dvi hdmi 1.4 displayport 1.2 – depending model vga output optional since intel dropped support video interface starting skylake hdmi 2.0 4k 60 hz supported motherboards equipped intel ’ alpine ridge thunderbolt controller skylake kaby lake coffee lake chipsets support legacy conventional pci interface however motherboard vendors may implement using external chips 4 holes fastening heatsink motherboard placed square lateral length 75 mm intel sockets lga 1156 lga 1155 lga 1150 lga 1151 cooling solutions therefore interchangeable intel officially states skylake kaby lake integrated memory controllers imc support ddr3l memory modules rated 1.35 v ddr4 1.2 v led speculation higher voltages ddr3 modules could damage destroy imc processor meanwhile asrock gigabyte asus guarantee skylake kaby lake ddr3 motherboards support ddr3 modules rated 1.5 1.65v equivalent kaby lake chipset analogous h110 chipset four additional pch pci-e lanes kaby lake chipsets reserved implementing m.2 slot support intel optane memory otherwise corresponding kaby lake skylake chipsets practically light blue indicates difference comparable skylake kaby lake chipsets lga 1151 socket revised coffee lake generation cpus comes along intel 300-series chipsets physical dimensions remain unchanged updated socket re-assigns reserved pins adding power ground lines support requirements 6-core 8-core cpus new socket also relocates processor detection pin breaking compatibility earlier processors motherboards result desktop coffee lake cpus officially compatible 100 original skylake 200 kaby lake series chipsets similarly 300 series chipsets officially support coffee lake compatible skylake kaby lake cpus socket 1151 rev 2 sometimes also referred 1151-2 like kaby lake chipsets four additional pch pci-e lanes coffee lake chipsets reserved implementing m.2 slot support intel optane memory 22nm version h310 chipset h310c sold china motherboards based chipset support ddr3 memory well nowiki /nowiki yes however motherboards require bios update order support 9th gen coffee lake cpus nowiki ** /nowiki depends oem implementation
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Computer architecture
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web service term web service ws either web service web technology http — originally designed human-to-machine communication — used transferring machine-readable file formats xml json practice web service commonly provides object-oriented web-based interface database server utilized example another web server mobile app provides user interface end user many organizations provide data formatted html pages also provide data server xml json often web service allow syndication example wikipedia another application offered end user may mashup web server consumes several web services different machines compiles content one user interface asynchronous javascript xml ajax dominant technology web services developing combination http servers javascript clients plain old xml distinct soap w3c web services frequently used json well instead xml representational state transfer rest architecture well-behaved web services function internet scale 2004 document w3c sets following rest key distinguishing feature web services number web services use markup languages web api development web services emphasis moving simpler representational state transfer rest based communications restful apis require xml-based web service protocols soap wsdl support interfaces relation w3c web services w3c defined web service w3c web services may use soap http protocol allowing less costly efficient interactions internet via proprietary solutions like edi/b2b besides soap http web services also implemented reliable transport mechanisms like ftp 2002 document web services architecture working group defined web services architecture requiring standardized implementation web service term web service describes standardized way integrating web-based applications using xml soap wsdl uddi open standards internet protocol backbone xml data format used contain data provide metadata around soap used transfer data wsdl used describing services available uddi lists services available web service method communication two electronic devices network software function provided network address web service always concept utility computing many organizations use multiple software systems management different software systems often need exchange data web service method communication allows two software systems exchange data internet software system requests data called service requester whereas software system would process request provide data called service provider different software may use different programming languages hence need method data exchange n't depend upon particular programming language types software however interpret xml tags thus web services use xml files data exchange rules communication different systems need defined rules communication defined file called wsdl web services description language codice_1 extension proposals autonomous web services aws seek develop flexible web services rely strict rules directory called uddi universal description discovery integration defines software system contacted type data one software system needs one particular report/data would go uddi find systems contact receiving data software system finds systems contact would contact system using special protocol called soap simple object access protocol service provider system would first validate data request referring wsdl file process request send data soap protocol automated tools aid creation web service services using wsdl possible either automatically generate wsdl existing classes bottom-up model generate class skeleton given existing wsdl top-down model critics non-restful web services often complain complex based upon large software vendors integrators rather typical open source implementations also concerns performance due web services use xml message format soap/http enveloping transporting functional non-functional testing web services done help wsdl parsing regression testing performed identifying changes made upgrade software web service regression testing needs categorized three different ways namely changes wsdl changes code selective re-testing operations capture three needs three intermediate forms subset wsdl namely difference wsdl dwsdl unit wsdl uwsdl reduced wsdl rwsdl respectively three subset wsdls combined form combined wsdl cwsdl used regression testing web service help automated web service change management awscm performing selection relevant test cases construct reduced test suite old test suite web services testing also automated using several test automation tools like soap ui oracle application testing suite oats unified functional testing selenium etc work related capture visualization changes made web service visualization computation changes done form intermediate artifacts subset wsdl insight computation change impact helpful testing top-down development reduce regression testing awscm tool identify subset operations wsdl file construct subset wsdl
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Web technology
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mesh networking mesh network simply meshnet local network topology infrastructure nodes i.e bridges switches infrastructure devices connect directly dynamically non-hierarchically many nodes possible cooperate one another efficiently route data from/to clients lack dependency one node allows every node participate relay information mesh networks dynamically self-organize self-configure reduce installation overhead ability self-configure enables dynamic distribution workloads particularly event nodes fail turn contributes fault-tolerance reduced maintenance costs mesh topology may contrasted conventional star/tree local network topologies bridges/switches directly linked small subset bridges/switches links infrastructure neighbours hierarchical star-and-tree topologies well established highly standardized vendor-neutral vendors mesh network devices yet agreed common standards interoperability devices different vendors yet assured mesh networks relay messages using either flooding technique routing technique routing message propagated along path hopping node node reaches destination ensure paths available network must allow continuous connections must reconfigure around broken paths using self-healing algorithms shortest path bridging self-healing allows routing-based network operate node breaks connection becomes unreliable result network typically quite reliable often one path source destination network although mostly used wireless situations concept also apply wired networks software interaction mesh network whose nodes connected fully connected network fully connected wired networks advantages security reliability problems cable affect two nodes attached however networks number cables therefore cost goes rapidly number nodes increases shortest path bridging allows ethernet switches connected mesh topology allows paths active wireless mesh radio networks originally developed military applications every node could dynamically serve router every node way even event failure nodes remaining nodes could continue communicate necessary serve uplinks nodes early wireless mesh network nodes single half-duplex radio one instant could either transmit receive time accompanied development shared mesh networks subsequently superseded complex radio hardware could receive packets upstream node transmit packets downstream node simultaneously different frequency different cdma channel allowed development switched mesh networks size cost power requirements radios declined nodes could cost-effectively equipped multiple radios turn permitted radio handle different function instance one radio client access another backhaul services work field aided use game theory methods analyze strategies allocation resources routing packets
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Distributed computing architecture
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biolinux biolinux term used variety projects involved making access bioinformatics software linux platform easier using one following methods various projects similar aims linux systems unices selection given also overview canadian bioinformatics helpdesk newsletter details linux-based projects package repositories generally specific distribution linux bioinformatician using number linux variants prevalent bioinformatics work fedora freely-distributed version commercial red hat system red hat widely used corporate world offer commercial support training packages fedora core community supported derivative red hat popular amongst like red hat system n't require commercial support many users bioinformatics applications produced rpms red hat package format designed work fedora potentially also install red hat enterprise linux systems distributions mandriva suse use rpms packages may also work distributions debian another popular linux distribution use many academic institutions bioinformaticians made software packages available distribution deb format slackware one less used linux distributions popular better knowledge linux operating system prefer command line various guis available packages tgz tgx format widely known live distribution based slackware slax used base many bioinformatics distributions many linux packages compatible mac os x several projects attempt make easy install selected linux packages including bioinformatics software computer running mac os x source live dvds cds ideal way provide bioinformatics computing run cd/dvd drive means slower traditional hard disk installation limited ability configured however suitable providing ad hoc solutions linux access available may even used basis linux installation general linux distributions wide range official packages available usually include much way scientific support exceptions detailed gentoo linux provides 156 bioinformatics applications see gentoo sci-biology herd main tree form ebuilds build applications source code additional 315 packages gentoo science overlay testing although flexible system excellent community support requirement install source means gentoo systems often slow install require considerable maintenance possible reduce compilation time using central server generate binary packages hand fine tune run highest speed utilizing best processor example actually use sse avx avx2 cpu instructions binary-based distro usually provide binaries using i686 even i386 instruction sets freebsd linux distribution version unix similar ports like gentoo ebuilds caveats apply however also pre-complied binary packages available 60 biological sciences applications 're listed fresh ports site hundred bioinformatics packages provided part standard debian installation nebc bio-linux packages also installed standard debian system long bio-linux-base package also installed creates /usr/local/bioinf directory packages install software debian packages may also work ubuntu linux debian-derived installations providing support documentation important part biolinux project scientists specialists may quickly find answers specific problems support forums mailing lists also useful disseminate knowledge within research community resources linked
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Operating systems
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iphone 7 iphone 7 iphone 7 plus smartphones designed developed marketed apple inc tenth generation iphone announced september 7 2016 bill graham civic auditorium san francisco apple ceo tim cook released september 16 2016 succeeding iphone 6s iphone 6s plus flagship devices iphone series apple also released iphone 7 iphone 7 plus numerous countries worldwide throughout september october 2016 succeeded flagship devices iphone 8 iphone 8 plus september 22 2017 iphone x november 3 2017 iphone 7 overall design similar iphone 6s iphone 6 changes introduced included new color options matte black jet black water dust resistance new capacitive static home button revised antenna bands removal 3.5 mm headphone jack device internal hardware received upgrades including heterogeneous quad-core system-on-chip improved system graphics performance upgraded 12 megapixel rear-facing cameras optical image stabilization models additional telephoto lens exclusive iphone 7 plus provide enhanced 2x optical zoom capabilities reception iphone 7 mixed although reviewers noted improvements camera especially dual rear camera plus model also stated iphone 7 make significant changes display build quality competing flagship smartphones surpassed quality iphone 7 many reviews highlighted controversial removal 3.5 mm headphone jack critics argued change meant bolster licensing proprietary lightning connector sales apple wireless headphone products questioned effects change audio quality apple also mocked critics phil schiller statement drastic change required courage. ” iphone 7 subject several reported issues notably hissing noise heavy usage phones significant differences performance device variants apple released sales numbers iphone 7 multiple u.s. carriers reported high demand launch subsequent reports end 2016 stated apple reduced production models due sluggish sales decreasing demand though sales research first quarter 2017 placed devices best-selling smartphones world prior official announcement multiple aspects iphone 7 heavily rumored apple plans remove 3.5 mm headphone jack received significant media attention rumors included flush camera stereo speakers 256 gigabyte storage option larger 3,100 mah battery august 29 2016 invitations press event bill graham civic auditorium san francisco california september 7 2016 sent members media prompting immediate speculation iphone 7 upcoming announcement iphone 7 officially announced event pre-orders beginning september 9 general availability september 16 iphone 7 launched 30 new countries later september international rollouts throughout october november 2016 indonesia last country release iphone 7 7 plus availability starting march 31 2017 following apple research development investment country march 21 2017 apple announced iphone 7 red color finish white front part partnership product red highlight aids fundraising campaign launched march 24 2017 later discontinued announcement iphone 8 iphone 8 plus iphone x september 2017 september 2017 apple announced iphone 8 iphone 8 plus direct successors iphone 7 7 plus alongside iphone x iphone 7 exterior similar shape volume iphone 6 iphone 6s alongside existing silver gold rose gold colors device offered new colors matte black glossy jet black limited time red jet black color dark shade high-gloss black finish created multi-step process beginning anodization phase make surface casing porous aluminum oxide using machine sweep casing powdered compound absorbed aluminum oxide process concluded ultrafine particle bath additional finishing entire process takes less hour iphone 7 rated ip67 water dust resistant although tests resulted malfunctions specifically distorted speakers water exposure warranty cover water damage phone iphone 7 home button uses capacitive mechanism input rather physical push-button previous models meaning direct skin contact capacitive glove required operate device physical feedback provided via taptic engine vibrator button also pressure-sensitive iphone 7 retains 3d touch display system introduced iphone 6s providing pressure-sensitive touchscreen input iphone 7 feature 3.5 mm headphone jack replaced second speaker grille serves vent internal barometer lightning-to-3.5-mm-connector adapter well in-ear headphones use lightning connector bundled device adapter also sold separately accessory adapter also compatible iphone ipad ipod touch devices running ios 10 newer iphone 7 uses apple a10 fusion 64-bit system-on-chip consists two low-power cores two high-power cores two cores used point time a10 chip also features hexa-core graphics chip capable console-level gaming prior models iphone 7 available two sizes one 4.7-inch screen plus variant 5.5-inch screen displays identical sizes resolutions iphone 6s wider color gamut increased brightness screen-to-body ratio ~66 ~68 7 7 plus respectively device variants also contain new iteration apple motion coprocessor m10 unlike previous iphone models internal storage options iphone 7 begin 32 gb instead 16 gb max 256 gb iphone 7 plus offers 3 gb ram previous iphone 4.7-inch iphone 7 2 gb iphone 7 includes 12-megapixel rear-facing camera quad-led true tone flash aperture widened f/1.8 standard-size phone model adds optical image stabilization feature previously exclusive plus models iphone 7 plus includes second 12-megapixel telephoto lens used achieve 2× optical zoom 10× digital zoom front-facing camera upgraded 7-megapixel sensor automatic image stabilization iphone 7 originally shipped ios 10 pre-installed iphone 7 plus received exclusive portrait camera mode ios 10.1 software update camera mode capable producing bokeh effect using depth field analysis second camera dual-lens back iphone 7 plus iphone 7 originally came lightning-to-3.5-mm adapter although omitted starting september 12 2018 apple sells adapter independently well apple also unveiled several bluetooth wireless headphones ostensibly intended use iphone 7 including airpods wireless in-ear headphones three new beats headphone products four products utilize in-house wireless chip known apple w1 designed provide low-power bluetooth operation integration ios macos devices though still compatible bluetooth-supported devices reception iphone 7 mixed gordon kelly forbes noted rival smartphones samsung galaxy s7 increased battery life added water resistance predecessor retaining headphone jack iphone 7 camera photo quality improved still lagging behind phones already market including galaxy s7 nexus 6p kelly praised apple able extract improved brightness accurate color reproduction lcd display panel noting old technology also well behind rivals already moved sharper 1080p even 2k screens iphone 7 exterior reuses aging design iphone 6 iphone 6s criticized especially size device thick top/bottom bezels kelly writing iphone 7 plus simply far big smartphone 5.5-inch display nilay patel verge described devices full aggressive breaks convention despite design continuity previous models going far dubbing prototype next year rumored drastic iphone redesign disguised iphone 6 citing headphone jack removal felt attempt encourage use wireless headphones heterogeneous cpu home button redesign display quality considered improvement previous models albeit insane quad hd displays competing phones taptic engine considered first really valuable new ui concept 've seen phones years opposed gimmick 3d touch patel felt cameras devices step 6s terms performance praised dual-lens camera 7 plus enhancing phone camera functionality however panned lack editing features made use regards enhanced bluetooth audio support provided devices containing w1 chip argued apple took away established open standard favor new technologies instead making experience using new technologies better across board made every third-party wireless audio product second-class citizen apple ecosystem giving iphone 7 9 10 concluded devices legitimately among interesting opinionated powerful phones apple ever shipped confident expressions company vision long time ios 10 excellent cameras better performance phenomenal batteries last longer john mccann techradar wrote first time phablet-sized iphone 7 plus markedly better smaller model highlighted improved battery life praised camera calling plus dual cameras excellent point-and-shoot much improved low-light performance mccann wrote lack headphone jack initially frustrating noted positive step forward mobile industry despite short-term effects ... making noise criticism iphone 7 centered around removal headphone jack including inability use wired headphones included adapter charge device simultaneously particularly scathing article nilay patel verge wrote removing headphone jack ditching deeply established standard would user-hostile stupid goes list reasons removing port negative concluding one asking vote dollars gordon kelly forbes noted wireless audio technology immature moment bluetooth audio quality inferior lightning audio reliability still question removal headphone jack meant ’ pushed era pay decent headphones due need integrated dac and/or lightning licensing pointed company profit situation apple charging licensing fees millions headphone companies particular apple vice president phil schiller announced change mocked extensively online stating removing headphone jack took 'courage online petition created consumer group sumofus accuses apple planned obsolescence causing substantial electronic waste removing headphone jack reached 300,000 signatures users reported strange hissing noise heavy usage phone cnet reports faint buzzes hums coming backside daily telegraph speculates iphone 7 new a10 fusion processor source noise linking tweets compare phone hissing sound hearing fans spin loudly whenever mac ’ cpu gets used actual potential issue referred hissgate guardian reported october 2016 storage tests unbox therapy gsmarena showed 32 gb iphone 7 significantly slower 128 256 gb versions measuring data write speeds 341 mb/s 128 gb iphone 7 model versus 42 mb/s 32 gb model october 2016 network tests cellular insights showed models a1660 a1661 qualcomm modems significant performance edge models a1778 a1784 intel modems inspection modems also found qualcomm version ability use ultra hd voice turned likely level playing field qualcomm intel variants report concluded statement sure main reason behind apple decision source two different modem suppliers newest iphone bloomberg reported november 2016 tests researchers twin prime cellular insights shown two modems perform similarly u.s. cellular networks despite one modems technically capable faster connectivity apple spokeswoman trudy muller told publication every iphone 7 iphone 7 plus meets exceeds apple ’ wireless performance standards quality metrics reliability testing ... rigorous lab tests based wireless industry standards thousands hours real-world field testing extensive carrier partner testing data shows discernible difference wireless performance models bloomberg quoted analysts technology advisers stated apple ’ want one version get reputation better may impact fanboys may make consumers think twice buying apple phone especially think might purchasing sub-standard product similar manner now-discontinued samsung galaxy note 7 reports iphone 7 exploding emitting smoke september 2016 one device reportedly exploded transit another one malfunction caused battery blow internally another report iphone 7 emitting smoke melting published october 2016 iphone 7 7 slogan misunderstood translated certain languages phone slogan mainland china 7 hong kong slogan iphone 7 cantonese local language hong kong slogan could mistakenly interpreted penis tsat common slang term erect penis seven varies tone often used euphemism iphone 7 apple added software lock prevents individuals attempting replace home button users required go apple store repairs done recalibration button necessary step apple went iphone 5s 6 6s touch id functionality would get disabled return-to-home functionality still worked iphone 7 devices model numbers a1660 a1779 a1780 suffer problem show service message even cellular reception available apple repair devices free within two years first retail sale unit apple deliberately withheld pre-order sales numbers citing longer representative metric investors customers without releasing specific numbers t-mobile us stated iphone 7 broken carrier all-time record first-day pre-order sales following weekend t-mobile us stated iphone 7 biggest iphone launch ever nearly 4x compared next popular iphone september 14 2016 two days iphone 7 went sale apple announced due high demand sold jet black iphone 7 colors iphone 7 plus caused issues customers iphone upgrade program unable reserve new phones customer complaints class action lawsuit apple made changes ensure members program could get new phones soon possible may 2017 analytics research company strategy analytics announced iphone 7 iphone 7 plus best-selling smartphones worldwide first quarter 2017 selling 21.5 million 17.4 million units respectively initial u.s. sales iphone 7 four major wireless carriers announced trade-in deals deals monthly installment plan cost iphone 7 negated monthly credit consumers bill consumers cancel service carrier pay phone prior installment contract completion receive credits remaining months jacob kastrenakes verge noted deals effectively constituted return two-year phone contracts deals essentially lock carrier two years wake deals verizon announced seen increase sales release previous year iphone 6s said sales exceeded expectations t-mobile sprint announced huge increases sales t-mobile seeing demand roughly four times higher 7 6 december 2016 digitimes reported apple reduced production iphone 7 decreasing demand product initial surge interest waned reason cited consumers suppliers turning attention next year iphone model new report nikkei end december included details sales production iphone 7 report based data suppliers stated apple would trim production iphone 7 10 first quarter 2017 following sluggish sales nikkei reported apple previously trimmed production iphone 7 20 due accumulated inventory previous model new models sold sluggishly expected additionally report notes iphone 7 plus features two cameras back face remains popular shortage camera sensors curbed apple ability meet demand phones
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Operating systems
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distributed component object model distributed component object model dcom proprietary microsoft technology communication software components networked computers dcom originally called network ole extends microsoft com provides communication substrate microsoft com+ application server infrastructure addition com due extensive use dce/rpc distributed computing environment/remote procedure calls – specifically microsoft enhanced version known msrpc terms extensions added com dcom solve problems one key factors solving problems use dce/rpc underlying rpc mechanism behind dcom dce/rpc strictly defined rules regarding marshalling responsible freeing memory dcom major competitor corba proponents technologies saw one day becoming model code service-reuse internet however difficulties involved getting either technologies work internet firewalls unknown insecure machines meant normal http requests combination web browsers microsoft one point attempted failed head adding extra http transport dce/rpc called ncacn_http network computing architecture connection-oriented protocol later resurrected support microsoft exchange 2003 connection http dcom supported natively windows nt 4.0 windows 2000 windows xp windows server 2003 well windows 7 windows 8 windows 10 windows server 2008 windows server 2008 r2 windows server 2012 windows server 2012 r2 windows server 2016 part initiative began microsoft part secure development lifecycle re-architect insecure code dcom saw significant security-focused changes windows xp service pack 2 comsource source code available along full complete documentation sufficient use also implement interoperable version dcom according documentation comsource comes directly windows nt 4.0 source code even includes source code windows nt registry service wine team also implementing dcom binary interoperability purposes currently interested networking side dcom provided msrpc restricted implementing ndr network data representation microsoft api committed making compatible possible msrpc tangramcom separate project wine focusing implementing dcom linux-based smartphones samba team also implementing dcom over-the-wire interoperability purposes unlike wine team currently interested binary-interoperability samba msrpc implementation far binary-interoperable microsoft msrpc
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Distributed computing architecture
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ncdu ncdu ncurses disk usage disk utility unix systems name refers similar purpose du utility ncdu uses text-based user interface n curses programming library users navigate list using arrow keys delete files taking much space pressing 'd key version 1.09 later export file listing json format ncdu developed yoran heling learn c serve disk usage analyzer remote systems ssh
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Computer file systems
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activex activex software framework created microsoft adapts earlier component object model com object linking embedding ole technologies content downloaded network particularly world wide web microsoft introduced activex 1996 principle activex dependent microsoft windows operating systems practice activex controls run windows also require client running x86-based computer activex controls contain compiled code activex still supported windows 10 internet explorer 11 activex supported default web browser microsoft edge different incompatible extension system compatible new chromium-based microsoft edge using ie mode activex one major technologies used component-based software engineering compared javabeans activex supports programming languages javabeans supports platforms activex supported many rapid application development technologies active template library delphi javabeans microsoft foundation class library qt visual basic windows forms wxwidgets enable application developers embed activex controls products many microsoft windows applications—including many microsoft internet explorer microsoft office microsoft visual studio windows media player—use activex controls build feature-set also encapsulate functionality activex controls embedded applications internet explorer also allows embedding activex controls web pages faced complexity ole 2.0 poor support com mfc microsoft simplified specification rebranded technology activex 1996 even simplification users still required controls implement six core interfaces response complexity microsoft produced wizards atl base classes macros c++ language extensions make simpler write controls starting internet explorer 3.0 1996 microsoft added support host activex controls within html content browser encountered page specifying activex control via codice_1 tag would automatically download install control little user intervention made web richer provoked objections since controls practice ran windows separate controls required supported platform one windows 3.1/windows nt 3.51 one windows nt/95 one macintosh f68k/powerpc security risks especially given lack user intervention microsoft subsequently introduced security measures make browsing including activex safer example activex controversial start microsoft claimed programming ease good performance compared java applets marketing materials critics activex quick point security issues lack portability making impractical use outside protected intranets activex security model relied almost entirely identifying trusted component developers using code signing technology called authenticode developers register verisign us 20 per year individuals 400 corporations sign contract promising develop malware identified code would run inside web browser full permissions meaning bug code potential security issue contrasts sandboxing already used java time october 1996 microsoft released beta version activex software development kit sdk macintosh including plug-in netscape navigator mac announced plan support activex solaris later year six months two beta releases later yet commercially available macintosh activex plugins 1997 ncompass labs cooperation microsoft released plug-in netscape navigator support activex documentation activex core technology resides open group may downloaded free despite microsoft previous efforts make activex cross-platform activex controls work platforms using activex controls implement essential functionality web page restricts usefulness south korea started remove technology public websites order make web site accessible platforms microsoft made significant effort push cross-platform aspect activex way publishing api ultimately cross-platform effort failed due activex controls written c c++ compiled intel x86 assembly language making executable windows machines call standard win32 apis microsoft dropped activex support windows store edition internet explorer 10 windows 8 2015 microsoft released microsoft edge replacement internet explorer support activex marked end technology microsoft web browser development may always possible use internet explorer execute activex content e.g. wine installation may user want microsoft developed large number products software platforms using activex objects still used e.g. websites still use asp
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Operating systems
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powerarchiver powerarchiver proprietary file archiver microsoft windows developed conexware inc supports full read-write access several different archive formats including zip 7z tar additionally read-only decompression support includes rar ace various disk image formats evaluation version program remains functional 40 days personal licenses currently permitted free lifetime updates future versions software business license valid two major versions powerarchiver first public release made march 1999 advertised free archiving solution written borland delphi turned shareware june 2001 version 7 prior powerarchiver software known easyzip command line version microsoft outlook plugin also provided powerarchiver user interface translated 15 languages latest release powerarchiver fully supports windows 7 provides user option use ribbon gui featured microsoft office 2007 windows 7 users revert old-style toolbar wish 2011 softpedia gave five stars praising wide support various compressed file types ftp backup feature pointing lack complete support vhd files later 2013 download.com gave five stars
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Computer file systems
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geliyoo geliyoo bilişim turkish multinational corporation specializing internet-related services products include search cloud computing software online advertising technologies geliyoo founded hakan atabaş graduated odtü fatih arslan m.s students texas tech university enhance search technologies turkey goal geliyoo developed team turkish engineers also geliyoo wants gain love turkish people leading field incorporated geliyoo privately held company april 5 2012 mission statement organize secure world information make globally accessible useful unofficial motto new technology geliyoo known €741,000 spent developed geliyoo without income ads till 2012 first award given two categories e-innovation e-telecommunication informatics association turkey geliyoo search web search engine company popular service geliyoo developed search engine crawler geliyoo spider geliyoobot/1.0 developed geliyoo first turkish search engine bot geliyoobot/1.0 builds searchable index geliyoo search engine webmaster wishes restrict information site available geliyoobot another well-behaved spider appropriate directives robots.txt file adding meta tag codice_1 web page geliyoo spider requests web servers identifiable user-agent string containing geliyoobot host address containing geliyoo.com geliyoo directory project gmoz gmoz.geliyoo.com original domain name multilingual open content directory world wide web links owned geliyoo constructed maintained community volunteer editors gmoz uses hierarchical ontology scheme organizing site listings listings similar topic grouped categories include smaller categories gmoz helps geliyoo search results geliyoo news free news aggregator provided operated geliyoo selecting up-to-date information thousands publications automatic aggregation algorithm service covers news articles appearing within past 30 days various news websites geliyoo maps web mapping service application technology provided geliyoo powers many map-based services including geliyoo maps website includes traffic offers street maps route planner traveling car geliyoo maps uses tom tom base maps geliyoo also develops first turkish web browser called geliyoo browser offers powerful browsing together built-in media downloading sharing features geliyoo browser based chromium technology platform supports torrent files tells geliyoo browser combines oracle java semantic web web 3.0 technologies
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Web technology
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object linking embedding object linking embedding ole proprietary technology developed microsoft allows embedding linking documents objects developers brought ole control extension ocx way develop use custom user interface elements technical level ole object object implements codice_1 interface possibly along wide range interfaces depending object needs ole allows editing application export part document another editing application import additional content example desktop publishing system might send text word processor picture bitmap editor using ole main benefit ole add different kinds data document different applications like text editor image editor creates compound file binary format document master file document makes reference changes data master file immediately affect document references called linking instead embedding ole also used transferring data different applications using drag drop clipboard operations ole 1.0 released 1990 evolution original dynamic data exchange dde concept microsoft developed earlier versions windows dde limited transferring limited amounts data two running applications ole capable maintaining active links two documents even embedding one type document within another ole servers clients communicate system libraries using virtual function tables vtbls vtbl consists structure function pointers system library use communicate server client server client libraries olesvr.dll olecli.dll originally designed communicate using wm_dde_execute message ole 1.0 later evolved become architecture software components known component object model com later dcom ole object placed clipboard embedded document visual representation native windows formats bitmap metafile stored well underlying data format allows applications display object without loading application used create object also allowing object edited appropriate application installed object packager component ole shipping windows 3.1 windows xp allows non-ole object packaged embedded ole client ole 2.0 next evolution ole sharing many goals version 1.0 re-implemented top com instead using vtbls directly new features ole automation drag-and-drop in-place activation structured storage monikers evolved ole 1 object names provided hierarchical object resource naming system similar urls uris independently invented windows merged two technologies supporting url moniker type moniker url scheme ole custom controls introduced 1994 replacement deprecated visual basic extension controls instead upgrading new architecture based ole particular container supported ole 2.0 could already embed ole custom controls although controls react events unless container supports ole custom controls usually shipped form dynamic link library .ocx extension 1996 interfaces controls except iunknown made optional keep file size controls would download faster called activex controls ole objects containers implemented top component object model objects implement interfaces export functionality ioleobject interface compulsory interfaces may also need implemented functionality exported interfaces required ease understanding follows terminology explained view status object whether object transparent opaque opaque solid background whether supports drawing specified aspect site object object representing location object container container supports site object every object contained follows list interfaces grouped object usually needs implement interfaces usually implemented ole object usually called ole container vice versa note following list indentation indicates interface inheritance non-indented interfaces derive iunknown opendoc technology tried compete ole microsoft competitors considered opendoc robust easier use however opendoc known problems opendoc allowed users view edit information across applications directly competition microsoft proprietary ole standard 1993 microsoft competitors established consortium called component integration laboratories cil develop opendoc open standard cross-platform linking embedding microsoft required ole compatibility condition microsoft certification application compatibility windows 95 microsoft initially announced applications using opendoc would deemed compatible ole would receive certification windows 95 microsoft later reversed decision said applications using opendoc might receive certification microsoft withheld specifications debugged versions ole released competing applications use microsoft object linking embedding ole objects limits interoperability objects widely supported programs viewing editing files e.g embedding files inside file tables charts spreadsheet application text document presentation file software understands ole object available object usually replaced picture bitmap representation object displayed
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Operating systems
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tron project tron acronym real-time operating system nucleus open architecture real-time operating system kernel design project started prof. dr. ken sakamura university tokyo 1984 project goal create ideal computer architecture network provide society needs industrial tron itron derivative one world used operating systems 2003 present billions electronic devices mobile phones appliances even cars although mainly used japanese companies garnered interest worldwide however dearth quality english documentation said hinder broader adoption tron project integrated t-engine forum 2010 today supported popular ssl/tls libraries wolfssl tron specify source code kernel instead set interfaces design guidelines creating kernel allows different companies create versions tron based specifications suited different microprocessors specification tron publicly available implementations proprietary discretion implementer tron framework defines complete architecture different computing units 1984 tron project officially launched 1985 nec announced first itron implementation based itron/86 specification 1986 tron kyogikai unincorporated tron association established hitachi announced itron implementation based itron/68k specification first tron project symposium held 1987 fujitsu announced itron implementation based itron/mmu specification mitsubishi electric announced itron implementation based itron/32 specification hitachi introduced gmicro/200 32bit microprocessor based tron vlsi cpu specification 2004 governor tokyo shintaro ishihara mentioned tron killed former minister international trade industry hashimoto time pressure united states story supported article website dedicated tron project citing microsoft lobbying result threat super-301 complete stop import based section 301 omnibus trade competitiveness act 1988 everything related tron led many companies dropping tron fear lose possibility export united states tron project administered tron association integrated t-engine forum 2010 tron project activities taken continued t-engine forum t-engine forum non-profit organization develops open specifications itron t-kernel ubiquitous id architecture chair t-engine forum dr. ken sakamura july 2011 266 members t-engine forum executive committee members includes top japanese giants like fujitsu hitachi ntt docomo denso a-level members involved design development specifications t-engine t-kernel ubiquitous id technology include companies esol nec yamaha corporation b-level members involved development product using t-engine specification t-kernel include companies like arm freescale mips technologies mitsubishi robert bosch gmbh sony corporation toshiba xilinx supporting members academic members involved forum include many universities university tokyo japan dalian maritime university china microscript programming language graphically-oriented high-level programming language created personal media corporation tron similar apple computer hypertalk intended mainly end users little programming experience yet also used development tool professional btron programmers port software tron variants easily quickly write device drivers hardware devices microscript based makes extensive use tron basic text editor basic figure editor
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Operating systems
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programming computable functions computer science programming computable functions pcf typed functional language introduced gordon plotkin 1977 based previous unpublished material dana scott considered extended version typed lambda calculus simplified version modern typed functional languages ml haskell fully abstract model pcf first given milner 1977 however since milner model essentially based syntax pcf considered less satisfactory ong 1995 first two fully abstract models employing syntax formulated 1990s models based game semantics hyland ong 2000 abramsky jagadeesan malacaria 2000 kripke logical relations o'hearn riecke 1995 time felt neither models completely satisfactory since effectively presentable however ralph loader demonstrated effectively presentable fully abstract model could exist since question program equivalence finitary fragment pcf decidable types pcf inductively defined context list pairs x σ x variable name σ type variable name duplicated one defines typing judgments terms-in-context usual way following syntactical constructs relatively straightforward semantics language scott model model model fully abstract pcf fully abstract language obtained adding parallel operator pcf p. 293 hyland ong 2000 reference
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Programming language topics
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sparkleshare sparkleshare open-source cloud storage file synchronization client app default uses git storage backend sparkleshare comparable dropbox cloud storage provided user server hosted solution github advantage self-hosting user retains absolute control data simplest case self-hosting requires ssh git sparkleshare support android ios devices hold due lack developer resources
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Distributed computing architecture
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curl curl pronounced 'curl computer software project providing library libcurl command-line tool curl transferring data using various protocols first released 1997 name stands client url original author lead developer swedish developer daniel stenberg libcurl free client-side url transfer library supporting cookies dict ftp ftps gopher http/1 http/2 support http post http put http proxy tunneling https imap kerberos ldap pop3 rtsp scp smtp library supports file uri scheme sftp telnet tftp file transfer resume ftp uploading http form-based upload https certificates ldaps proxies user-plus-password authentication libcurl library portable builds works identically many platforms including aix amigaos android beos blackberry tablet os blackberry 10 openvms darwin dos freebsd hp-ux hurd ios irix linux macos netbsd netware openbsd os/2 qnx neutrino risc os solaris symbian tru64 ultrix unixware microsoft windows libcurl library free thread-safe ipv6 compatible bindings available 40 languages including c/c++ java php python libcurl library support axtls gnutls mbed tls nss qsossl ibm schannel windows secure transport macos ios ssl/tls openssl wolfssl curl command-line tool getting sending data including files using url syntax since curl uses libcurl supports range common network protocols currently including http https ftp ftps scp sftp tftp ldap dap dict telnet file imap pop3 smtp rtsp last four versions newer 7.20.0 9 february 2010 curl supports https performs ssl certificate verification default secure protocol specified https curl connects remote server via https obtain remote server certificate check ca certificate store validity remote server ensure remote server one claims curl packages bundled ca certificate store file several options specify ca certificate -- cacert -- capath -- cacert option used specify location ca certificate store file windows platform ca certificate file specified curl look ca certificate file name “ curl-ca-bundle.crt ” following order curl return error message remote server using self-signed certificate remote server certificate signed ca listed ca cert file -k -- insecure option used skip certificate verification alternatively remote server trusted remote server ca certificate added ca certificate store file basic use curl involves simply typing curl command line followed url output retrieve curl defaults displaying output retrieves standard output specified system usually terminal window running command would systems display www.example.com source-code terminal window -o flag used store output file instead options change tool behavior available
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Web technology
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domain based security domain based security abbreviated dbsy model-based approach help analyse information security risks business context provide clear direct mapping risks security controls needed manage variant approach used uk government hmg infosec standard no.1 technical risk-assessment method dbsy registered trade mark qinetiq ltd. dbsy developed late 1990s defence evaluation research agency dera model-based approach information assurance describes requirements security organisation taking account business needs supported model based around concept security domain represents logical place people work information using computer system connections security domains necessary support business activity hence focus information needs protection people work people exchange information model also describe physical environments people work system boundaries major system security measures placed systematic method applied model identify describe risks valuable information assets exposed specify security measures effective managing risks dbsy origins late 1990s developed defence evaluation research agency dera ministry defence mod initially called domain based approach developed alongside purple penelope support mod increasing need interconnections systems operating different security levels recognised risks associated connections directly related nature information exchange needed effective model understanding managing risks would need take account business needs information sharing also recognised controlled release information system handling secret information sometimes referred time 'down grading 'sanitisation adequately described existing models information security notably bell-lapadula biba associated information flow models information flow models found unhelpful understanding risks information shared people systems entirely trusted effective model understanding managing risks would need take account business needs exchanging information within outside organisation modelling technique applied major projects mod result experience graphical modelling techniques revised rigorous risk assessment method based concepts compromise paths developed approach security documentation project lifecycle also created domain based security conferences held qinetiq malvern june 2005 june 2006 promoting discussion could widely used defence commercial systems variant dbsy method subsequently developed incorporated uk government hmg infosec standard no.1 technical risk assessment method standard method used security risk assessments government information technology systems dbsy approach uses simple models represent requirements security organisation using two different related viewpoints infosec business model represents security aspects business infosec infrastructure model represents logical provision strong boundaries enforce separation combined make infosec architecture model model forms basis conducting systematic rigorous risk assessment infosec business model defines security domains connections model specifies limits information processed exchanged security domains forms set security requirements business particular connections explicitly modelled permitted required occur security domain characterised set information assets may valuable organisation well people work information applications services act behalf connections domains characterised nature interaction required interpersonal messages shared access database sensitivity integrity requirements information exchange model also represent kinds physical environment domain accessed infosec infrastructure model defines islands computing infrastructure required logically separate information exchanged except identifiable manageable points connection referred causeways island characterised strength separation islands people manage computing infrastructure infosec architecture model combines business infrastructure views showing security domains supported islands infrastructure connections security domains hosted different islands connections must supported appropriate causeway dbsy method uses rational risk framework describing risks information assets exposed similar kinds assets grouped together focus interest risk assessment process applied focus interest turn key factors determining risk particular focus interest risk framework applied systematic fashion organisation-specific infosec architecture model representing security-relevant features organisation business systems process set compromise paths systematically described relative effectiveness different countermeasures assessed dbsy differs risk management methods primary focus people business drivers organisation way business works rather technical security measures analyst required systematically define groups people pose threat ways might cause harm providing rigorous business-oriented framework concepts threat vulnerability aim understand analyse information security risks faced organisation especially risks appear conflict needs business efficiency across organisation dealings customers business partners
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Computer security
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venturi transport protocol venturi transport protocol vtp patented proprietary transport layer protocol designed transparently replace tcp order overcome inefficiencies design tcp related wireless data transport owned venturi wireless protocol employed various wireless broadband internet service providers verizon wireless unwired unwired calls venturi client application provides transparent vtp connectivity unwired optimizer order speed network overcome latency issues
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Internet protocols
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system integrity protection system integrity protection sip sometimes referred rootless security feature apple macos operating system introduced os x el capitan comprises number mechanisms enforced kernel centerpiece protection system-owned files directories modifications processes without specific entitlement even executed root user user root privileges sudo apple says root user significant risk factor system security especially systems single user account user also administrator system integrity protection enabled default disabled apple says system integrity protection necessary step ensure high level security one wwdc developer sessions apple engineer pierre-olivier martel described unrestricted root access one remaining weaknesses system saying piece malware one password vulnerability away taking full control device stated installations macos one user account necessarily carries administrative credentials means users grant root access program asks whenever user system prompted enters account password – martel says often weak non-existent – security entire system potentially compromised restricting power root unprecedented macos instance versions macos prior mac os x leopard enforce securelevel security feature originates bsd derivatives upon macos partially based system integrity protection comprises following mechanisms system integrity protection protects system files directories flagged protection happens either adding extended file attribute file directory adding file directory among protected directories symbolic links also protected although target directories protected preinstalled apple applications protected well kernel stops processes without specific entitlements modifying permissions contents flagged files directories also prevents code injection runtime attachment dtrace respect protected executables since os x yosemite kernel extensions drivers code-signed particular apple entitlement developers request developer id entitlement apple kernel refuses boot unsigned extensions present showing user prohibition sign instead mechanism called kext signing integrated system integrity protection system integrity protection disabled either wholly partly outside system partition end apple provides command-line utility executed terminal window within recovery system bootable macos installation disk adds boot argument device nvram applies setting installations el capitan macos sierra device upon installation macos installer moves unknown components within flagged system directories preventing write access system directories system file directory permissions maintained automatically apple software updates result permissions repair available disk utility corresponding operation reception system integrity protection mixed macworld expressed concern apple could take full control away users developers future releases move security policy macos slowly toward apple mobile operating system ios whereupon installation many utilities modifications requires jailbreaking applications drivers work full extent operated unless feature disabled either temporarily permanently ars technica suggested could affect smaller developers disproportionately larger ones may able work apple directly however also remarked far users including power users reason turn feature saying almost downsides
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Operating systems
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apus group apus group commonly termed apus founded june 2014 tao li chinese technology company specializing android development information services company main product apus user system also known apus launcher drawn 1 billion users globally 2016 along apus series products including apus user system apus booster+ apus browser apus message center apus flashlight etc covering 200 countries six continents according tao li ceo apus 90 percent users countries beyond china one world top 10 developers mobile applications name apus short perfect user system also refers bird species apodidae swift highly aerial bird family fastest fliers animal kingdom maximum speed june 2014 tao li founded apus group beijing month apus netted 100 million rmb series funding july 2 2014 apus launcher released google play 28 days later apus user group reached 10 million october 22 2014 apus announced 50 million user globally december 1 2014 apus published first apus global mobile application analysis report january 2015 apus picked 100 million usd series b funding become youngest unicorn companies market values usd 1 billion world january 2015 apus user group reached 100 million march 2015 apus user group reached 150 million named fifth developer world app annie may 2015 apus user group reached 300 million may 2015 apus browser released september 2015 apus announced ’ netted 250 million users globally apus user system apus launcher 510 million apus user system apus launcher apus series products time market value reached usd 1.5 billion september 2015 apus announced long-term partnership inmobi decision entry india market october 2015 apus announced entry japanese korean market december 2015 apus announced usd 45 million rs 300 crore indian mobile web companies march 2016 apus announced acquired 920 million downloads apus series products including apus user system apus booster apus browser apus browser turbo apus flashlight etc october 2016 forbes reported leading position apus group google play store praised apus group advanced business model successful monetization november 2016 apus announced fresh investment us 44 million india new research development center sales business development office gurgaon startup incubator
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Operating systems
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ieee cloud computing ieee cloud computing global initiative launched ieee promote cloud computing big data related technologies provide expertise resources individuals enterprises involved cloud computing 2010 institute electrical electronics engineers ieee sponsored two cloud computing–specific conferences ieee cloud ieee cloudcom success two conferences ieee senior member ieee computer society past president steve diamond began urging organization take active role development cloud computing standards april 2011 support ieee future directions committee funding ieee new initiatives committee ieee cloud computing launched initiative designed follow multi-year plan includes focus across multiple tracks conferences education publications standards intercloud testbed web portal marketing public relations part initiative launch two new cloud computing standards development projects approved ieee p2301 draft guide cloud portability interoperability profile ieee p2302 draft standard intercloud interoperability federation siif growing need greater cloud computing interoperability federation ieee cloud computing focused development activities resources behind ieee p2302 standard ieee cloud computing continues pursue efforts provide cloud computing standards advancement cloud computing technologies educate users benefits cloud computing part ongoing effort offers variety activities products services including ieee cloud computing portal conferences events continuing education courses publications standards ieee intercloud testbed platform testing cloud computing interoperability ieee cloud computing portal serves online hub cloud computing resources site includes news information form ieee press releases well articles taken ieee third-party publications portal provides dedicated sections conferences events education careers publications standards ieee intercloud testbed innovations part mandate ieee cloud computing process developing global cloud computing standards april 2011 began working first ieee cloud computing standards ieee p2301 ieee p2302 ieee p2301 draft guide cloud portability interoperability profile ieee p2302 draft standard intercloud interoperability federation address cloud interoperability portability fragmentation ieee p2301 guide cloud portability interoperability profiles cpip working group formed february 24 2014 mandate develop guide cloud portability interoperability profiles completed guide advise cloud computing ecosystem participants cloud vendors service providers end users available standards-based choices areas like application portability management interoperability interfaces file formats operation conventions guide group choices multiple logical profiles organized address different cloud personalities john messina senior member national institute standards technology nist cloud computing program chair ieee p2301 guide cloud portability interoperability profiles working group april 4 2011 ieee p2302 draft standard intercloud interoperability federation working group formed finalized approved ieee p2302 define topology protocols functionality governance cloud-to-cloud interoperability federated operations ieee cloud computing also formed new ieee adaptive management cloud computing amcc study group december 16 2013 group purpose investigate management environments needed support dynamic nature cloud computing environments services provide customers consume services providers offering services also explore potential application adaptive policy-based management cloud based environments including adaptive management architectures environments adaptive security management auto-generation management policies business specifications auto-generation data support management functionality co-generation application management functionality joel fleck senior standards architect hp labs study group chair ieee cloud computing sponsors participates cloud computing-focused conferences events around world designed promote knowledge-sharing cloud computing events typically range one day week attract global audience conference event programs generally offer multiple educational tracks keynote speeches panel discussions roundtables led industry notables researchers engineers academics policymakers key stakeholders early january 2012 ieee cloud computing began partnering established conference develop matrix events targeted specific geographic regions ieee globecom 2013 held atlanta georgia co-located north america cloud congress initiative organizing additional cloud congresses european asia pacific latin america regions encourage greater focus cloud computing via existing well-established conference ieee signature conference computers software applications compsac ieee international conference cloud computing technology science ieee cloudcom ieee global communications conference exhibition industry forum globecom create new cloud computing-related events specific geographic regions ieee cloud computing offers continuing education courses e-learning modules videos conference section chapter talks participating societies organizations active ieee cloud computing include
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Distributed computing architecture
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windows hardware error architecture windows hardware error architecture whea operating system hardware error handling mechanism introduced windows vista windows server 2008 successor machine check architecture mca previous versions windows architecture consists several software components interact hardware firmware given platform handle notify regarding hardware error conditions collectively components provide generic means discovering errors common error report format errors way preserving error records error event model based event tracing windows etw whea builds pci express advanced reporting provide detailed information system errors common reporting structure whea allows third-party software interact operating system react certain hardware events example new cpu added running system—a windows server feature known dynamic hardware partitioning—the hardware error component stack notified new processor installed unknown hardware errors windows 10 solved reverse engineering running scf scan
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Operating systems
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history ibm mainframe operating systems history operating systems running ibm mainframes notable chapter history mainframe operating systems ibm long-standing position world largest hardware supplier mainframe computers arguably operating systems ibm supplied customers use early mainframes seldom innovative except virtual machine systems beginning cp-67 company well-known reputation preferring proven technology generally given potential users confidence adopt new ibm systems fairly quickly ibm current mainframe operating systems z/os z/vm z/vse z/tpf backward compatible successors operating systems introduced 1960s although course improved many ways ibm-supplied operating systems supplied others discussed notably used ibm mainframes ibm slow introduce operating systems general motors produced general motors os 1955 gm-naa i/o 1956 use ibm computers 1962 burroughs corporation released mcp general electric introduced gecos cases use customers fact first operating systems ibm computers written ibm customers wish expensive machines us 2m mid-1950s sitting idle operators set jobs manually wanted mechanism maintaining queue jobs operating systems described ran processor models suitable scientific engineering calculations users ibm computers applications manage without operating systems one ibm smaller computers ibm 650 introduced feature later became part os/360 processing interrupted random processing error hardware glitch machine could automatically resume last checkpoint instead requiring operators restart job manually beginning general motors research division produced gm-naa i/o ibm 701 1956 prototype gm operating system developed 1955 updated 701 successor 1960 ibm user association share took produced updated version share operating system finally ibm took project supplied enhanced version called ibsys ibm 7090 ibm 7094 computers ibsys required 8 tape drives fewer system one disk drives main components card-based job control language main user interface compilers fortran cobol assembler various utilities including sort program 1958 university michigan executive system adapted gm-naa i/o produce umes better-suited large number small jobs created students umes used 1967 replaced mts timesharing system bell labs produced besys sometimes referred bellmon used mid-1960s bell also made available others without charge formal technical support ibsys ibm produced ibm 709 7090 7094 computers tape-based operating system whose sole purpose compile fortran programs—in fact fms fortran compiler tape mit fernando corbató produced first experimental time-sharing systems ctss 1957 early 1960s using slightly modified ibm 704 ibm 7090 mainframes systems based proposal john mccarthy 1960s ibm laboratories created experimental time-sharing systems using standard mainframes hardware microcode modifications support virtual memory ibm m44/44x early 1960s cp-40 1964 1967 cp-67 1967 1972 company even released cp-67 without warranty technical support several large customers 1968 1972 cp-40 cp-67 used modified system/360 cpus m44/44x based ibm 7044 earlier generation cpu different internally experimental systems late incorporated system/360 series ibm announced 1964 encouraged company add virtual memory virtual machine capabilities system/370 mainframes operating systems 1972 1968 consulting firm called computer software systems used released version cp-67 set commercial time-sharing service company technical team included 2 recruits mit see ctss dick orenstein harold feinleib grew company renamed national css modified software increase number paying users could support system sufficiently different warranted new name vp/css vp/css delivery mechanism national css services early 1980s switched ibm vm/370 see universities produced three s/360 time-sharing operating systems late 1960s early 1960s ibm low-end high-end systems incompatible programs could easily transferred one another systems often used completely different peripherals e.g disk drives ibm concluded factors increasing design production costs hardware software level unsustainable reducing sales deterring customers upgrading 1964 company announced system/360 new range computers used peripherals could run programs ibm originally intended system/360 one batch-oriented operating system os/360 least two accounts ibm later decided also produce simpler batch-oriented operating system dos/360 system/360 operating systems complex previous ibm operating systems several reasons including made development os/360 system/360 software one largest software projects anyone attempted ibm soon ran trouble huge time cost overruns large numbers bugs problems magnified develop test system/360 operating systems real hardware ibm first develop basic programming support bps bps used develop tools needed develop dos/360 os/360 well first versions tools would supply operating systems compilers fortran cobol utilities including sort assembler needed build software ibm competitors took advantage delays os/360 system/360 announce systems aimed thought vulnerable parts ibm market prevent sales system/360 collapsing ibm released four stop-gap operating systems ibm announced s/360-67 also announced timesharing operating system tss/360 would use new virtual memory capabilities 360/67 tss/360 late unreliable ibm canceled time alternative operating system cp-67 developed ibm cambridge scientific center running well enough ibm offer without warranty timesharing facility large customers cp-67 would go become vm/370 eventually z/vm traumas producing system/360 operating systems gave boost emerging discipline software engineering attempt apply scientific principles development software management software projects frederick p. brooks senior project manager whole system/360 project given specific responsibility os/360 already long overdue wrote acclaimed book mythical man-month based problems encountered lessons learned project two os/360 preferred operating system higher-end system/360 machines dos/360 usual operating system less powerful machines provided set utility programs macro assembler compilers fortran cobol support rpg came later eventually pl/i subset supported useful range file organizations access methods help using sequential isam files could store either fixed-length variable-length records types could occupy one disk volume dos/360 also offered btam data communications facility primitive hard use today standards btam could communicate almost type terminal big advantage time hardly standardization communications protocols dos/360 significant limitations compared os/360 used control larger system/360 machines ibm expected dos/360 users would soon upgrade os/360 despite limitations dos/360 became world widely used operating system dos/360 ran well system/360 processors medium-sized organizations could afford better operating systems customers result descendant z/vse still widely used today 2005 os/360 included multiple levels support single api much shared code pcp stop-gap version could run one program time mft multiprogramming fixed number tasks mvt multiprogramming variable number tasks used least late 1970s good five years successors launched unclear whether divisions among pcp mft mvt arose mvt required much memory usable mid-range machines ibm needed release multiprogramming version os mft soon possible pcp mft mvt different approaches managing memory see provided similar facilities experience indicated advisable install os/360 systems less 256 kb memory common limitation 1960s installing mft customers would specify five partitions areas memory fixed boundaries application programs could run simultaneously mft version ii mft-ii raised limit 52 mvt considerably larger complex mft therefore used powerful system/360 cpus treated memory used operating system single pool contiguous regions could allocated required indefinite number simultaneous application programs scheme flexible mft principle used memory efficiently liable fragmentation one could find although enough spare memory total run program divided separate chunks none large enough 1971 time sharing option tso use mvt added tso became widely used program development provided editor ability submit batch jobs notified completion view results without waiting printed reports debuggers programming languages used system/360 tso communicated terminals using tcam telecommunications access method eventually replaced earlier queued telecommunications access method qtam tcam name suggests ibm hoped would become standard access method data communications fact tcam used almost entirely tso largely superseded vtam late 1970s onwards system/360 hardware operating systems designed processing batch jobs extreme cases might run hours result unsuitable transaction processing thousands units work per day takes 30 seconds minutes 1968 ibm released ims handle transaction processing 1969 released cics simpler transaction processing system group ibm staff developed customer ims available os/360 successors cics also available dos/360 successors many years type product known tp teleprocessing monitor strictly speaking tp monitors operating system components application programs managed application programs 1970s 1980s several third-party tp monitors competed cics notably taskmaster shadow intercomm ibm gradually improved cics point customers abandoned alternatives 1950s airlines expanding rapidly growth held back difficulty handling thousands bookings manually using card files 1957 ibm signed development contract american airlines development computerized reservations system became known sabre first experimental system went live 1960 system took booking functions 1964 cases using ibm 7090 mainframes early 1960s ibm undertook similar projects airlines soon decided produce single standard booking system pars run system/360 computers sabre early versions pars separation application operating system components software 1968 ibm divided pars application acp operating system later versions acp named acp tpf tpf transaction processing facility non-airline businesses adopted operating system handling large volumes online transactions latest version z/tpf ibm developed acp successors mid-1960s ibm standard operating systems dos/360 os/360 batch-oriented could handle large numbers short transactions quickly enough even transaction monitors ims cics run control standard general-purpose operating systems fast enough handling reservations hundreds flights thousands travel agents last public domain version acp hence last free version acp 9.2 distributed single mini-reel accompanying manual set two dozen manuals occupied perhaps 48 lineal inches shelf space could restored ibm 3340 disk drives would thereby provide fully functional acp system acp 9.2 intended primarily bank card mastercard et al financial applications could also utilized airlines reservation systems time acp become general-purpose os indeed acp incorporated hypervisor module chyr supported virtual os ... usually vs1 possibly also vs2 ... guest program development file maintenance could accomplished concurrently on-line functions instances production work run vs2 hypervisor including possibly ims db model 20 labeled part system/360 range could connected peripherals 16-bit machine entirely program-compatible members system/360 range three operating systems developed ibm labs germany different 360/20 configurations dps—with disks minimum memory required 12 kb tps—no disk tapes minimum memory required 8 kb cps—punched-card-based minimum memory required 4 kb direct successors since ibm introduced system/3 range small business computers 1969 system/3 different internal design 360/20 different peripherals ibm mainframes another processor used system/360 peripherals different internal design 360/44 designed scientific computation using floating point numbers geological meteorological analyses internal differences specialized type work designed 360/44 operating system ps/44 emulator missing system/360 instructions allowed model 44 run os/360 360/44 ps/44 direct successors system/370 announced 1970 offered essentially facilities system/360 4 times processor speeds similarly-priced system/360 cpus 1972 ibm announced system/370 advanced functions main item future sales system/370 would include virtual memory capability could also retro-fitted existing system/370 cpus hence ibm also committed delivering enhanced operating systems could support use virtual memory new operating systems distinguished predecessors presence /vs names vs stands virtual storage ibm avoided term virtual memory allegedly word memory might interpreted imply ibm computers could forget things today ibm mainframe operating systems except z/tpf descendants included system/370 advanced functions announcement z/tpf descendant acp system ibm initially developed support high-volume airline reservations applications dos/vs successor dos/360 addition virtual memory dos/vs provided enhancements dos/vs followed significant upgrades dos/vse vse/sp 1980s vse/esa 1991 z/vse 2005 os/vs1 successor mft offered similar facilities addition virtual memory ibm released fairly minor enhancements os/vs1 1983 1984 announced would os/vs1 tss/370 ibm system/370 operating systems modern descendants special real time operating system srtos programming rpq z06751 variant os/vs1 extended support real-time computing targeted industries electric utility energy management oil refinery applications os/vs2 release 1 svs replacement mvt virtual memory many changes retained overall structure 1974 ibm released described os/vs2 release 2 major rewrite upwards-compatible earlier os/vs2 svs new system noticeable feature supported multiple virtual address spaces different applications thought using range virtual addresses new system virtual memory facilities mapped different ranges real memory addresses result new system rapidly became known mvs multiple virtual storages original os/vs2 became known svs single virtual storage ibm accepted terminology labelled mvs successors mvs/ ... distinctive features mvs main catalog vsam catalog supported tightly-coupled multiprocessing 2 cpus share memory copy operating system included system resources manager renamed workload manager later versions allowed users load additional work system without reducing performance high-priority jobs ibm released several mvs upgrades mvs/se mvs/sp version 1 mvs/xa 1981 mvs/esa 1985 os/390 1996 currently z/os 2001 vm/370 combined virtual machine facility single-user system called conversational monitor system cms combination provided time-sharing allowing user run copy cms virtual machine combination direct descendant cp/cms virtual machine facility often used testing new software normal production work continued another virtual machine cms timesharing system widely used program development vm/370 followed series upgrades vm/sepp systems extensions program product vm/bsepp basic systems extensions program product vm/sp system product vm/sp hpo high performance option vm/xa extended architecture migration aid vm/xa sf extended architecture system facility vm/xa sp extended architecture system product vm/esa enterprise systems architecture z/vm ibm also produced optional microcode assists vm successors speed hypervisor emulation privileged instructions operating systems use behalf guest operating systems part 370/extended architecture ibm added start interpretive execution sie instruction allow speedup cp hypervisor time-sharing timesharing based idea computers much faster humans one human user reading computer displayed screen computer useful work another user large time-sharing systems hundreds even thousands simultaneous users memory required programs data generally adds much physical memory attached computer time-sharing systems solve problem various combinations virtual memory memory management technique programs made work memory available actually attached computer running programs code data may scattered several areas physical memory even placed disk needed main components ibm virtual memory system functioning properly virtual memory system keeps active pages real memory inactive ones disk allows efficient execution systems workload virtual machine techniques enable several operating systems guest operating systems software run computer thinks whole computer simulated whole computers called virtual machine operating system really controls computer usually called hypervisor two major components hypervisor
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Operating systems
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diskxtender emc diskxtender also known dx automated policy-based file system-centric product migrating inactive data higher-cost storage lower-cost disk tape optical devices hierarchical storage management diskxtender produced emc corporation supported windows linux unix environments windows version dx implements file-system filter driver intercepts user mode i/o requests intercepted requests processed dx components necessary files fetched secondary storage media passed back calling applications otherwise processing necessary filter driver nothing simply passes request stack lower level drivers applications implement similar architecture terms file system filters include anti-virus file system replication software 2003 diskxtender one three information lifecycle management offerings emc emc acquired legato system remaining products emailxtender databasextender archive email databases correspondingly diskxtender intercepting i/o operating system capable detecting inactive data migrating data secondary and/or tertiary storage lower cost/gbs still maintaining transparency applications end users applications end users full visibility migrated data access requested migrated data either redirected users applications copied back production system various times rumors end life diskxtender related products
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Computer file systems
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action language computer science action language language specifying state transition systems commonly used create formal models effects actions world action languages commonly used artificial intelligence robotics domains describe actions affect states systems time may used automated planning action languages fall two classes action description languages action query languages examples former include strips pddl language generalization strips propositional part pednault adl language b extension adding indirect effects distinguishing static dynamic laws language c adds indirect effects also assume every fluent automatically inertial also action query languages p q r. several different algorithms exist converting action languages particular action language c answer set programs since modern answer-set solvers make use boolean sat algorithms rapidly ascertain satisfiability implies action languages also enjoy progress made domain boolean sat solving action languages supplement definition state transition system set f fluents set v values fluents may take function mapping × f v set states state transition system
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Programming language topics
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evaluation strategy evaluation strategies used programming languages determine evaluate argument function call function also read operation method relation kind value pass function example call value/call reference specifies function application evaluates argument proceeds evaluation function body passes two capabilities function namely ability look current value argument modify via assignment statement notion reduction strategy lambda calculus similar distinct practical terms many modern programming languages converged call-by-value/call-by-reference evaluation strategy function calls c java languages especially lower-level languages c++ combine several notions parameter passing historically call value call name date back algol 60 language designed late 1950s call reference used pl/i fortran systems purely functional languages like haskell well non-purely functional languages like r use call need evaluation strategy specified programming language definition function specific implementation strict evaluation arguments function always evaluated completely function applied church encoding eager evaluation operators maps strict evaluation functions reason strict evaluation sometimes called eager existing programming languages use strict evaluation functions applicative order leftmost innermost evaluation refers evaluation strategy arguments function evaluated left right post-order traversal reducible expressions es applicative order call-by-value evaluation call value also referred pass value common evaluation strategy used languages different c scheme call value argument expression evaluated resulting value bound corresponding variable function frequently copying value new memory region function procedure able assign values parameters local variable assigned—that anything passed function call unchanged caller scope function returns call value single evaluation strategy rather family evaluation strategies function argument evaluated passed function many programming languages common lisp eiffel java use call value evaluate function arguments left-to-right evaluate functions arguments right-to-left others scheme ocaml c leave order unspecified cases term call value problematic value passed value variable understood ordinary meaning value implementation-specific reference value effect syntactically looks like call value may end rather behaving like call reference call sharing often depending subtle aspects language semantics reason passing reference often language technically provide value representation complicated data instead represents data structure preserving semblance value appearance source code exactly boundary drawn proper values data structures masquerading often hard predict c array strings special cases data structure name array treated value reference first element array struct variable name refers value even fields vectors maple vector special case table therefore data structure list gets rendered indexed exactly way value tcl values dual-ported value representation used script level language manages corresponding data structure one required modifications made via data structure reflected back value representation vice versa description call value value reference common understood call reference another term call sharing thus behaviour call value java visual basic call value c pascal significantly different c pascal calling function large structure argument cause entire structure copied except actually reference structure potentially causing serious performance degradation mutations structure invisible caller however java visual basic reference structure copied fast mutations structure visible caller call reference also referred pass reference evaluation strategy function receives implicit reference variable used argument rather copy value typically means function modify i.e assign variable used argument—something seen caller call reference therefore used provide additional channel communication called function calling function call-by-reference language makes difficult programmer track effects function call may introduce subtle bugs simple litmus test whether language supports call-by-reference semantics possible write traditional codice_1 function language many languages support call reference form another comparatively use default fortran ii early example call-by-reference language languages c++ php visual basic .net c realbasic default call value offer special syntax call-by-reference parameters c++ additionally offers call reference const call reference simulated languages use call value n't exactly support call reference making use references objects refer objects pointers objects representing memory addresses objects languages c ml rust use technique separate evaluation strategy—the language calls value—but sometimes referred call address also referred pass address ml references type- memory- safe like rust similar effect achieved call sharing passing object mutated used languages like java python ruby purely functional languages typically semantic difference two strategies since data structures immutable possibility function modify arguments typically described call value even though implementations frequently use call reference internally efficiency benefits following example demonstrates call reference e following example call address simulates call reference c void modify int p int* q int* r int main call sharing also referred call object call object-sharing evaluation strategy first named barbara liskov et al language clu 1974 used languages python iota java object references ruby javascript scheme ocaml applescript many others however term call sharing common use terminology inconsistent across different sources example java community say java call value call sharing implies values language based objects rather primitive types i.e values boxed said pass copy reference primitives boxed passing unboxed called function semantics call sharing differ call reference particular call value mutations arguments performed called routine visible caller call reference access given variables caller merely certain objects e.g variable passed possible simulate assignment variable callee scope however since function access object caller copy made mutations objects objects mutable within function visible caller may appear differ call value semantics mutations mutable object within function visible caller object copied cloned — shared example python lists mutable def f list f print outputs codice_2 codice_3 method modifies object called assignments within function noticeable caller languages passing variable means passing access actual object referred variable access original caller variable since rebound variable exists within scope function counterpart caller retains original binding compare python mutation code binds formal argument new object def f list f print outputs codice_4 statement codice_5 reassigns new list variable rather location references immutable objects real difference call sharing call value except object identity visible language use call sharing mutable objects alternative input/output parameters parameter assigned argument overwritten object identity changed object argument mutated although term widespread usage python community identical semantics languages java visual basic often described call value value implied reference object call copy-restore also referred copy-in copy-out call value result call value return —as termed fortran community special case call reference provided reference unique caller variant gained attention multiprocessing contexts remote procedure call parameter function call reference might accessible another thread execution contents may copied new reference function call returns updated contents new reference copied back original reference restored semantics call copy-restore also differ call reference two function arguments alias one another point variable caller environment call reference writing one affect call copy-restore avoids giving function distinct copies leaves result caller environment undefined depending aliased arguments copied back first—will copies made left-to-right order entry return reference passed callee uninitialized evaluation strategy may called call result partial evaluation evaluation may continue body function applied sub-expressions contain unbound variables evaluated function applications whose argument values known may reduced presence side-effects complete partial evaluation may produce unintended results reason systems support partial evaluation tend pure expressions expressions without side-effects within functions non-strict evaluation arguments function evaluated unless actually used evaluation function body church encoding lazy evaluation operators maps non-strict evaluation functions reason non-strict evaluation often referred lazy boolean expressions many languages use form non-strict evaluation called short-circuit evaluation evaluation returns soon determined unambiguous boolean result—for example disjunctive expression true encountered conjunctive expression false encountered forth conditional expressions also usually use lazy evaluation evaluation returns soon unambiguous branch result normal-order leftmost outermost evaluation evaluation strategy outermost redex always reduced applying functions evaluating function arguments contrast call name evaluate inside body unapplied function call name evaluation strategy arguments function evaluated function called—rather substituted directly function body using capture-avoiding substitution left evaluated whenever appear function argument used function body argument never evaluated used several times re-evaluated time appears see jensen device call-by-name evaluation occasionally preferable call-by-value evaluation function argument used function call name save time evaluating argument whereas call value evaluate regardless argument non-terminating computation advantage enormous however function argument used call name often slower requiring mechanism thunk early use algol 60 today .net languages simulate call name using delegates expression parameters latter results abstract syntax tree given function eiffel provides agents represent operation evaluated needed seed7 provides call name function parameters java programs accomplish similar lazy evaluation using lambda expressions codice_6 interface call need memoized variant call name function argument evaluated value stored subsequent uses argument side-effect free produces results call name saving cost recomputing argument haskell well-known language uses call-by-need evaluation evaluation expressions may happen arbitrarily far computation haskell supports side-effects mutation via use monads eliminates unexpected behavior variables whose values change prior delayed evaluation r arguments passed call-by-need r allows arbitrary side-effects call-by-need arguments lazy evaluation commonly used implementation strategy call-by-need semantics variations exist—for instance optimistic evaluation .net languages implement call need using type codice_7 call macro expansion similar call name uses textual substitution rather capture-avoiding substitution uncautious use macro substitution may result variable capture lead undesired behavior hygienic macros avoid problem checking replacing shadowed variables parameters full β-reduction function application may reduced substituting function argument function using capture-avoiding substitution time may done even within body unapplied function call future also referred parallel call name concurrent evaluation strategy value future expression computed concurrently flow rest program one promises value future needed main program blocks future value promise one promises finishes computing already completed strategy non-deterministic evaluation occur time creation future i.e expression given use future value similar call need value computed computation may deferred value needed may started value future needed local variable function returns computation may terminated part-way implemented processes threads creating future spawn one new processes threads promises accessing value synchronize main thread terminating computation future corresponds killing promises computing value implemented coroutine .net async/await creating future calls coroutine async function may yield caller turn yielded back value used cooperatively multitasking optimistic evaluation another variant call need function argument partially evaluated amount time may adjusted runtime evaluation aborted function applied using call need approach avoids runtime expense call need still retaining desired termination characteristics
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Programming language topics
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overhead code overhead code additional excess object code generated compiler provide machine code executed specific cpu code includes translations generic instructions listed cross-platform code tailored execution specific platform architecture example overhead code would code generated handle reference counting source code written high level language example cross-platform code coverage area standalone house space taken enclosures similarly overhead code part program listed source code however needed software operate properly
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Programming language topics
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android donut android donut fourth version open source android mobile operating system developed google longer supported among prominent features introduced update added support cdma smartphones additional screen sizes battery usage indicator text-to-speech engine public release donut—its official dessert-themed code name convention employed google designate major android versions—carriers quick follow roll customers form over-the-air ota update compatible smartphones
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Operating systems
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associated signature containers associated signature containers asic specifies use container structures bind together one signed objects either advanced electronic signatures timestamp tokens one single digital container eidas-regulation associated signature container asic eidas data container used hold group file objects digital signatures and/or time assertions associated objects data stored asic zip format european commission implementing decision 2015/1506 8 september 2015 laid specifications relating formats advanced electronic signatures advanced seals recognised public sector bodies pursuant articles 27 37 eidas-regulation eu member states requiring advanced electronic signature advanced electronic signature based qualified certificate shall recognise xml cms pdf advanced electronic signature conformance level b lt level using associated signature container signatures comply following technical specifications technical specification asics updated standardized since april 2016 european telecommunications standards institute standard associated signature containers asic etsi en 319 162-1 v1.1.1 2016-04 updated standard required european commission implementing decision internal structure asic includes two folders electronic signature file would contain single cades object one xades signatures time assertion file would either contain one timestamp token conform ietf rfc 3161 whereas single evidence record would conform ietf rfc 4998 ietf rfc6283 one purposes electronic signature secure data attached modified done creating dataset combines signature signed data store detached signature separate resource utilize external process re-associate signature data advantageous use detached signatures prevents unauthorized modifications original data objects however risk detached signature become separated associated data happen association would lost therefore data would become inaccessible one widespread deployments asic standard estonian digital signature system use multiplatform windows linux macos osx software called digidoc using correct tool job always important using correct type asic container job hand also important container single file object associated signature time assertion file “ mimetype ” file specifies media type might also included container mimetype file included required first file asic container container type allow additional signatures added future used sign stored file objects long-term time-stamp tokens used asic archive manifest files used protect long-term time-stamp tokens tampering type container hold one signature time assertion files asic-e xades deals signature files asic-e cades deals time assertions files within asic containers apply file object sets file object might additional metadata information associated also protected signature asic-e container could designed prevent modification allow inclusion without causing damage previous signatures asic containers capable maintaining long-term availability integrity storing xades cades signatures use time-stamp tokens evidence record manifest files contained within containers asic containers must comply zip specification limitations applied zip container operates baseline requirements asic simple asic-s container also provides additional time assertion requirements additional elements may within meta-inf folder requires use “ signeddata ” variable include certificate revocation information container baselines asic-e container additional restrictions container complies asic-e baseline requirements along additional requirements restrictions use asic reduces risk electronic signature becoming separated data combining signature signed data container elements secured within asic easier distribute signature guarantee correct signature metadata used validation process also used associating time assertions including evidence records time-stamp tokens associated data
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Computer security
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joseph henry wegstein joseph henry wegstein april 7 1922 washburn illinois august 16 1985 american computer scientist wegstein attended university illinois graduated master degree physics 1948 worked national bureau standards nist specialized standards automatic data processing particular technology fingerprint recognition participated conferences zurich 1958 paris 1960 developed programming languages algol 58 algol 60 respectively member codasyl committee involved development cobol language
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Programming language topics
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acid computer science acid atomicity consistency isolation durability set properties database transactions intended guarantee validity even event errors power failures etc context databases sequence database operations satisfies acid properties perceived single logical operation data called transaction example transfer funds one bank account another even involving multiple changes debiting one account crediting another single transaction 1983 andreas reuter theo härder coined acronym acid shorthand atomicity consistency isolation durability building earlier work jim gray enumerated atomicity consistency durability left isolation characterizing transaction concept four properties describe major guarantees transaction paradigm influenced many aspects development database systems according gray reuter ims supported acid transactions early 1973 although term acid came later characteristics four properties defined reuter härder follows transactions often composed multiple statements atomicity guarantees transaction treated single unit either succeeds completely fails completely statements constituting transaction fails complete entire transaction fails database left unchanged atomic system must guarantee atomicity every situation including power failures errors crashes consistency ensures transaction bring database one valid state another maintaining database invariants data written database must valid according defined rules including constraints cascades triggers combination thereof prevents database corruption illegal transaction guarantee transaction correct referential integrity guarantees primary key foreign key relationship transactions often executed concurrently e.g. multiple transactions reading writing table time isolation ensures concurrent execution transactions leaves database state would obtained transactions executed sequentially isolation main goal concurrency control depending method used effects incomplete transaction might even visible transactions durability guarantees transaction committed remain committed even case system failure e.g. power outage crash usually means completed transactions effects recorded non-volatile memory following examples illustrate acid properties examples database table two columns b integrity constraint requires value value b must sum 100 following sql code creates table described create table acidtest integer b integer check b 100 series database operations atomic transaction either occur none occur series operations separated executed makes series operations indivisible guarantee atomicity prevents updates database occurring partially cause greater problems rejecting whole series outright words atomicity means indivisibility irreducibility alternatively may say logical transaction may made composed one several physical transactions unless component physical transactions executed logical transaction occurred – effects database say logical transaction consists transferring funds account account b logical transaction may composed several physical transactions consisting first removing amount account first physical transaction second transaction depositing said amount account b would want see amount removed account sure transferred account b unless transactions happened amount transferred account b transfer effects database occurred consistency general term demands data must meet validation rules previous example validation requirement b 100 validation rules must checked ensure consistency assume transaction attempts subtract 10 without altering b consistency checked transaction known b 100 transaction begins transaction removes 10 successfully atomicity achieved however validation check show b 90 inconsistent rules database entire transaction must cancelled affected rows rolled back pre-transaction state constraints triggers cascades every single change operation would checked way transaction committed similar issues may arise constraints may required data types b integers enter say value 13.5 transaction cancelled system may give rise alert form trigger if/when trigger written effect another example would integrity constraints would allow us delete row one table whose primary key referred least one foreign key tables demonstrate isolation assume two transactions execute time attempting modify data one two must wait completes order maintain isolation consider two transactions transfers 10 b. transfers 20 b combined four actions operations performed order isolation maintained although must wait consider happens fails halfway database eliminates effects sees valid data interleaving transactions actual order actions might consider happens fails modifying b step 4 time fails already modified restored value without leaving invalid database known write-write failure two transactions attempted write data field typical system problem would resolved reverting last known good state canceling failed transaction restarting interrupted transaction good state consider transaction transfers 10 b first removes 10 adds 10 b point user told transaction success however changes still queued disk buffer waiting committed disk power fails changes lost user assumes understandably changes persist processing transaction often requires sequence operations subject failure number reasons instance system may room left disk drives may used allocated cpu time two popular families techniques write-ahead logging shadow paging cases locks must acquired information updated depending level isolation possibly data may read well write ahead logging atomicity guaranteed copying original unchanged data log changing database allows database return consistent state event crash shadowing updates applied partial copy database new copy activated transaction commits many databases rely upon locking provide acid capabilities locking means transaction marks data accesses dbms knows allow transactions modify first transaction succeeds fails lock must always acquired processing data including data read modified non-trivial transactions typically require large number locks resulting substantial overhead well blocking transactions example user running transaction read row data user b wants modify user b must wait user transaction completes two phase locking often applied guarantee full isolation alternative locking multiversion concurrency control database provides reading transaction prior unmodified version data modified another active transaction allows readers operate without acquiring locks i.e. writing transactions block reading transactions readers block writers going back example user transaction requests data user b modifying database provides version data existed user b started transaction user gets consistent view database even users changing data one implementation namely snapshot isolation relaxes isolation property guaranteeing acid properties distributed transaction across distributed database single node responsible data affecting transaction presents additional complications network connections might fail one node might successfully complete part transaction required roll back changes failure another node two-phase commit protocol confused two-phase locking provides atomicity distributed transactions ensure participant transaction agrees whether transaction committed briefly first phase one node coordinator interrogates nodes participants reply prepared coordinator second phase formalize transaction
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Databases
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robin milner arthur john robin gorell milner 13 january 1934 – 20 march 2010 known robin milner a. j. r. g. milner british computer scientist turing award winner milner born yealmpton near plymouth england military family awarded scholarship eton college 1947 subsequently served royal engineers attaining rank second lieutenant enrolled king college cambridge graduating 1957 milner first worked schoolteacher programmer ferranti entering academia city university london swansea university stanford university 1973 university edinburgh co-founder laboratory foundations computer science lfcs returned cambridge head computer laboratory 1995 eventually stepped although still laboratory 2009 milner sicsa advanced research fellow held part-time chair computer science university edinburgh milner died heart attack 20 march 2010 cambridge wife lucy died shortly milner generally regarded made three major contributions computer science developed lcf one first tools automated theorem proving language developed lcf ml first language polymorphic type inference type-safe exception handling different area milner also developed theoretical framework analyzing concurrent systems calculus communicating systems ccs successor pi-calculus time death working bigraphs formalism ubiquitous computing subsuming ccs pi-calculus also credited rediscovering hindley–milner type system made fellow royal society distinguished fellow british computer society 1988 milner received acm turing award 1991 1994 inducted fellow acm 2004 royal society edinburgh awarded milner royal medal bringing public benefits global scale 2008 elected foreign associate national academy engineering fundamental contributions computer science including development lcf ml ccs pi-calculus see also publications robin milner dblp
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Programming language topics
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data protection officer data protection officer dpo ensures independent manner organization applies laws protecting individuals ’ personal data designation position tasks dpo within organization described articles 37 38 39 eu general data protection regulation gdpr according gdpr data protection officer shall directly report highest management level ’ mean dpo line managed level must direct access give advice senior managers making decisions personal data processing core responsibilities dpo include ensuring his/her organization aware trained relevant gdpr obligations conducting audits ensure compliance address potential issues proactively acting liaison his/her organization public regarding data privacy matters germany since 2001 dpo additional protections laid avoid companies discharge dpo simply job since may 2018 gdpr introduced similar protections across eu gdpr article 38
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Computer security
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silicon graphics silicon graphics inc. later rebranded sgi historically known silicon graphics computer systems sgcs american high-performance computing manufacturer producing computer hardware software founded mountain view california november 1981 jim clark initial market 3d graphics computer workstations products strategies market positions developed significantly time early systems based geometry engine clark marc hannah developed stanford university derived clark broader background computer graphics geometry engine first very-large-scale integration vlsi implementation geometry pipeline specialized hardware accelerated inner-loop geometric computations needed display three-dimensional images much history company focused 3d imaging major supplier hardware software market silicon graphics reincorporated delaware corporation january 1990 mid late-1990s rapidly improving performance commodity wintel machines began erode sgi stronghold 3d market porting maya platforms major event process sgi made several attempts address including disastrous move existing mips platforms intel itanium well introducing linux-based intel ia-32 based workstations servers failed market mid-2000s company repositioned supercomputer vendor move also failed april 1 2009 sgi filed chapter 11 bankruptcy protection announced would sell substantially assets rackable systems deal finalized may 11 2009 rackable assuming name silicon graphics international remains silicon graphics inc. became graphics properties holdings inc. james h. clark left position electrical engineering associate professor stanford university found sgi 1982 along group seven graduate students research staff stanford kurt akeley david j brown tom davis rocky rhodes marc hannah herb kuta mark grossman along abbey silverstone others ed mccracken ceo silicon graphics 1984 1997 years sgi grew annual revenues 5.4 million 3.7 billion addition 3d graphic capabilities pcs ability clusters linux- bsd-based pcs take many tasks larger sgi servers ate sgi core markets porting maya linux mac os x microsoft windows eroded low end sgi product line response challenges faced marketplace falling share price ed mccracken fired sgi brought richard belluzzo replace belluzzo leadership number initiatives taken considered accelerated corporate decline one initiative trying sell workstations running windows nt called visual workstations instead ones ran irix company version unix put company even direct competition likes dell making difficult justify price premium product line unsuccessful abandoned years later sgi premature announcement migration mips itanium abortive ventures ia-32 architecture systems visual workstation line ex-intergraph zx10 range sgi 1000-series linux servers damaged sgi credibility market 1999 attempt clarify current market position graphics company silicon graphics inc. changed corporate identity sgi although legal name unchanged time sgi announced new logo consisting letters sgi proprietary font called sgi created branding design consulting firm landor associates collaboration designer joe stitzlein sgi continued use silicon graphics name workstation product line later re-adopted cube logo workstation models november 2005 sgi announced delisted new york stock exchange common stock fallen minimum share price listing exchange sgi market capitalization dwindled peak seven billion dollars 1995 120 million time delisting february 2006 sgi noted could run cash end year mid-2005 sgi hired alix partners advise returning profitability received new line credit sgi announced postponing scheduled annual december stockholders meeting march 2006 proposed reverse stock split deal de-listing new york stock exchange january 2006 sgi hired dennis mckenna new ceo chairman board directors mr. mckenna succeeded robert bishop remained vice chairman board directors may 8 2006 sgi announced filed chapter 11 bankruptcy protection u.s. subsidiaries part plan reduce debt 250 million two days later u.s. bankruptcy court approved first day motions use 70 million financing facility provided group bondholders foreign subsidiaries unaffected september 6 2006 sgi announced end development mips/irix line irix operating system production would end december 29 last orders would fulfilled march 2007 support products would end december 2013 sgi emerged bankruptcy protection october 17 2006 stock symbol point sgid.pk canceled new stock issued nasdaq exchange symbol sgic new stock distributed company creditors sgid common stockholders left worthless shares end year company moved headquarters mountain view sunnyvale earlier north shoreline headquarters occupied computer history museum newer amphitheater parkway headquarters sold google locations award-winning designs studios architecture april 2008 sgi re-entered visualization market sgi virtu range visualization servers workstations re-badged systems boxx technologies based intel xeon amd opteron processors nvidia quadro graphics chipsets running red hat enterprise linux suse linux enterprise server windows compute cluster server december 2008 sgi received delisting notification nasdaq market value minimum 35 million requirement 10 consecutive trading days also meet nasdaq alternative requirements minimum stockholders equity 2.5 million annual net income continuing operations 500,000 april 1 2009 sgi filed chapter 11 announced would sell substantially assets rackable systems 25 million sale ultimately 42.5 million finalized may 11 2009 time rackable announced adoption silicon graphics international global name brand bankruptcy court scheduled continuing proceedings hearings june 3 24 2009 july 22 2009 rackable acquisition vizworld magazine published series six articles chronicle downfall sgi hewlett packard enterprise acquired sgi november 2016 allowed hpe place top500 nasa ames research center pleiades sgi ice supercomputer portfolio sgi continuous presence high performance compute silicon graphics inc. second bankruptcy phase renamed graphics properties holdings inc. gphi june 2009 2010 gphi announced significant favorable ruling litigation ati technologies amd june 2010 following patent lawsuit originally filed silicon graphics inc. era following 2008 appeal ati validity '327 silicon graphics inc voluntary dismissal '376 patent lawsuit federal circuit upheld jury verdict validity gphi u.s. patent 6,650,327 furthermore found amd lost right challenge patent validity future proceedings january 31 2011 district court entered order permits amd pursue invalidity affirmative defense trial permit sgi accuse amd radeon r700 series graphics products infringement case april 18 2011 gphi amd entered confidential settlement license agreement resolved litigation matter immaterial amount provides immunity gphi patents alleged infringement amd products including components software designs april 26 2011 court entered order granting parties agreed motion dismissal final judgment 2011-11 gphi filed another patent infringement lawsuit apple inc. delaware involving patents original patent infringement case apple last november alleged violation u.s. patents 6,650,327 '327 '145 '881 2012 gphi filed lawsuit apple sony htc corp lg electronics inc. samsung electronics co. research motion ltd. allegedly violating patent relating computer graphics process turns text images pixels displayed screens affected devices include apple iphone htc evo4g lg thrill research motion torch samsung galaxy galaxy ii sony xperia play smartphones sgi first generation products starting iris integrated raster imaging system 1000 series high-performance graphics terminals based motorola 68000 family microprocessors later iris 2000 3000 models developed full unix workstations first entries 1000 series models 1000 1200 introduced 1984 graphics terminals peripherals connected general-purpose computer digital equipment corporation vax provide graphical raster display abilities used 8 mhz motorola 68000 cpus ram disk drives booted network via excelan exos/101 ethernet card controlling computer used pm1 cpu board variant board used stanford university sun workstation later sun-1 workstation sun microsystems graphics system composed gf1 frame buffer uc3 update controller dc3 display controller bp2 bitplane 1000-series machines designed around multibus standard later 1000-series machines 1400 1500 ran 10 mhz 1.5 mb ram 1400 73 mb st-506 disk drive 1500 474 mb smd-based disk drive xylogics 450 disk controller may used pm2 cpu pm2m1 ram board 2000 series usual monitor 1000 series ran 30 hz interlaced six beta-test units 1400 workstation produced first production unit sgi first commercial computer shipped carnegie-mellon university electronic imaging laboratory 1984 sgi rapidly developed machines workstations second product line — iris 2000 series first released august 1985 sgi began using unix system v operating system five models two product ranges 2000/2200/2300/2400/2500 range used 68010 cpus pm2 cpu module later turbo systems 2300t 2400t 2500t 68020s ip2 cpu module used excelan exos/201 ethernet card graphics hardware gf2 frame buffer uc4 update controller dc4 display controller bp3 bitplane main differences cpu ram weitek floating point accelerator boards disk controllers disk drives st-506 smd available could upgraded example 2400 2400t 2500 2500t larger chassis standard 6 19 eia rack space bottom two smd disk drives weighing approximately non-turbo models used multibus cpu communicate floating point accelerator turbos added ribbon cable dedicated 60 hz monitors used 2000 series height machines using motorola cpus reached iris 3000 series models 3010/3020/3030 3110/3115/3120/3130 30s full-size rack machines used graphics subsystem ethernet 2000s could also use 12 geometry engines first widespread use hardware graphics accelerators standard monitor 19 60 hz non-interlaced unit tilt/swivel base 19 30 hz interlaced 15 60 hz non-interlaced tilt/swivel base also available iris 3130 smaller siblings impressive time complete unix workstations 3130 powerful enough support complete 3d animation rendering package without mainframe support large capacity hard drives standards day two 300 mb drives streaming tape ethernet could centerpiece animation operation line formally discontinued november 1989 3500 systems shipped 2000 3000 models combined introduction iris 4d series sgi switched mips microprocessors machines powerful came powerful on-board floating-point capability 3d graphics became popular television film time systems responsible establishing much sgi reputation sgi produced broad range mips-based workstations servers 1990s running sgi version unix system v called irix included massive onyx visualization systems size refrigerators capable supporting 64 processors managing three streams high resolution fully realized 3d graphics october 1991 mips announced first commercially available 64-bit microprocessor r4000 sgi used r4000 crimson workstation irix 6.2 first fully 64-bit irix release including 64-bit pointers secure supply future generations mips microprocessors 64-bit r4000 sgi acquired company 1992 333 million renamed mips technologies inc. wholly owned subsidiary sgi 1993 silicon graphics sgi signed deal nintendo develop reality coprocessor rcp gpu used nintendo 64 n64 video game console deal signed early 1993 later made public august year console later released 1996 rcp developed sgi nintendo operations department led engineer dr. wei yen 1997 twenty sgi employees led yen left sgi founded artx later acquired ati technologies 2000 1998 sgi relinquished ownership mips technologies inc re-ipo fully divested 2000 late 1990s much industry expected itanium replace cisc risc architectures non-embedded computers sgi announced intent phase mips systems development new mips microprocessors stopped existing r12000 design extended multiple times 2003 provide existing customers time migrate itanium august 2006 sgi announced end production mips/irix systems end year mips/irix products longer generally available sgi second generation onyx reality engine machines sgi offered access high performance 3d graphics subsystems proprietary api known iris graphics language iris gl features added years iris gl became harder maintain cumbersome use 1992 sgi decided clean reform iris gl made bold move allowing resulting opengl api cheaply licensed sgi competitors set industry-wide consortium maintain opengl standard opengl architecture review board meant first time fast efficient cross-platform graphics programs could written day opengl remains real-time 3d graphics standard portable across variety operating systems opengl-es even runs many types cell phones main competitor direct3d microsoft runs microsoft windows-based machines consoles sgi part advanced computing environment initiative formed early 1990s 20 companies including compaq digital equipment corporation mips computer systems groupe bull siemens nec netpower microsoft santa cruz operation intent introduce workstations based mips architecture able run windows nt sco unix group produced advanced risc computing arc specification began unravel little year formation sgi crimson system fsn three-dimensional file system navigator appeared 1993 movie jurassic park movie twister protagonists seen using sgi laptop computer however unit shown actual working computer rather fake laptop shell built around sgi corona lcd flat screen display 1995 film congo also features sgi laptop computer used dr. ross laura linney communicate via satellite travicom hq purple lowercased sgi logo seen beginning opening credits hbo series silicon valley taken replaced google logo intro graphics progress google leased former sgi buildings 2003 headquarters mountain view ca purchased buildings outright 2006 eight consecutive years 1995–2002 films nominated academy award distinguished achievement visual effects created silicon graphics computer systems inexpensive pcs began graphics performance close expensive specialized graphical workstations sgi core business sgi shifted focus high performance servers digital video web many sgi graphics engineers left work computer graphics companies ati nvidia contributing pc 3d graphics revolution 1995 film toy story used silicon graphics indigo2 computers create scenes movie sgi promoter free software supporting several projects linux samba opening previously proprietary code xfs filesystem open64 compiler 1995 sgi purchased alias research kroyer films wavefront technologies deal totaling approximately 500 million merged companies alias|wavefront june 2004 sgi sold business later renamed alias/wavefront private equity investment firm accel-kkr 57.1 million october 2005 autodesk announced signed definitive agreement acquire alias 182 million cash february 1996 sgi purchased well-known supercomputer manufacturer cray research 740 million began use marketing names craylink sgi-developed technology integrated sgi server line three months later sold cray business systems division responsible cs6400 sparc/solaris server sun microsystems undisclosed amount acknowledged later sun executive significantly less 100 million many cray t3e engineers designed developed sgi altix numalink technology sgi sold cray brand product lines tera computer company march 31 2000 35 million plus one million shares sgi also distributed remaining interest mips technologies spin-off effective june 20 2000 september 2000 sgi acquired zx10 series windows workstations servers intergraph computer systems rumored 100 million rebadged sgi systems product line discontinued june 2001 another attempt sgi late 1990s introduce family intel-based workstations running windows nt red hat linux see also sgi visual workstation proved financial disaster shook customer confidence sgi ’ commitment mips-based line 1998 sgi announced future generations machines would based mips processors upcoming super-chip intel code-named merced later called itanium funding high-end processors reduced planned r10000 would last mips mainstream processor mips technologies would focus entirely embedded market success sgi would longer fund development cpu since failure arc found use machines plan quickly went awry early 1999 clear itanium going delivered late would nowhere near performance originally expected production delays increased mips existing r10000-based machines grew increasingly uncompetitive eventually forced introduce faster mips processors r12000 r14000 r16000 used series models 2002 2006 sgi first itanium-based system short-lived sgi 750 workstation launched 2001 sgi mips-based systems superseded launch itanium 2-based altix servers prism workstations time later unlike mips systems ran irix itanium systems used suse linux enterprise server sgi enhancements operating system sgi used transitive corporation quicktransit software allow old mips/irix applications run emulation new itanium/linux platform server market itanium 2-based altix eventually replaced mips-based origin product line workstation market switch itanium completed sgi exited market altix powerful computer world 2006 assuming computer defined collection hardware running single instance operating system altix 512 itanium processors running single instance linux cluster 20 machines eighth-fastest supercomputer faster supercomputers clusters none many flops per machine however recent supercomputers large clusters machines individually less capable sgi acknowledged 2007 moved away massive numa model clusters although sgi continued market itanium-based machines recent machines based intel xeon processor first altix xe systems relatively low-end machines december 2006 xe systems capable itanium machines measures e.g. power consumption flops/w density flops/m cost/flops xe1200 xe1300 servers used cluster architecture departure pure numa architectures earlier itanium mips servers june 2007 sgi announced altix ice 8200 blade-based xeon system 512 xeon cores per rack altix ice 8200 installed new mexico computing applications center 14336 processors ranked number 3 top500 list november 2007 conventional wisdom holds sgi core market traditionally hollywood visual effects studios fact sgi largest revenue always generated government defense applications energy scientific technical computing one case silicon graphics largest single sale ever united states postal services usps sgi servers powered artificial intelligence ai program mechanically read tag sort mail hand-written block number usps key mail centers rise cheap yet powerful commodity workstations running linux windows mac os x availability diverse professional software effectively pushed sgi visual effects industry niche markets sgi continued enhance line servers including supercomputers based sn architecture sn scalable node technology developed sgi mid-1990s uses cache-coherent non-uniform memory access cc-numa sn system processors memory bus- memory-controller coupled together entity called node usually single circuit board nodes connected high-speed interconnect called numalink originally marketed craylink internal bus instead access processors memory i/o devices done switched fabric links routers thanks cache coherence distributed shared memory sn systems scale along several axes cpu count increases memory capacity i/o capacity system bisection bandwidth allows combined memory nodes accessed single os image using standard shared-memory synchronization methods makes sn system far easier program able achieve higher sustained-to-peak performance non-cache-coherent systems like conventional clusters massively parallel computers require applications code written re-written explicit message-passing communication nodes first sn system known sn-0 released 1996 product name origin 2000 based mips r10000 processor scaled 2 128 processors smaller version origin 200 sn-00 scaled 1 4 later enhancements enabled systems large 512 processors second generation system originally called sn-1 later sn-mips released july 2000 origin 3000 scaled 4 512 processors 1,024-processor configurations delivered special order customers smaller less scalable implementation followed called origin 300 november 2002 sgi announced repackaging sn system name origin 3900 quadrupled processor area density sn-mips system 32 128 processors per rack moving fat tree interconnect topology january 2003 sgi announced variant sn platform called altix 3000 internally called sn-ia used intel itanium 2 processors ran linux operating system kernel time released world scalable linux-based computer supporting 64 processors single system node nodes could connected using numalink technology form sgi predictably termed superclusters february 2004 sgi announced general support 128 processor nodes followed 256 512 processor versions year april 2004 sgi announced sale alias software business approximately 57 million october 2004 sgi built supercomputer columbia broke world record computer speed nasa ames research center cluster 20 altix supercomputers 512 intel itanium 2 processors running linux achieved sustained speed 42.7 trillion floating-point operations per second teraflops easily topping japan famed earth simulator record 35.86 teraflops week later ibm upgraded blue gene/l clocked 70.7 teraflops july 2006 sgi announced sgi altix 4700 system 1,024 processors 4 tb memory running single linux system image 68k mips-based models also rebadged vendors including cdc tandem computers prime computer siemens-nixdorf sgi onyx sgi indy series systems used game development nintendo 64
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Computer architecture
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apple gs/os gs/os operating system developed apple computer apple ii personal computer uses prodos filing system provides facilities accessing file system controlling input/output devices loading running program files system allowing programs handle interrupts signals gs/os included component apple ii system software versions 4.0 6.0.1 gs/os unlike predecessor written entirely 16-bit code first true 16-bit operating system ii gs/os includes facility known file system translators fsts allows support multiple on-disk file systems manner transparent application programs feature found prodos microcomputer operating systems time usually used prodos file system one could booted gs/os also supports variety file systems including hierarchical file system used mac os file system translators addition prodos hfs include ms-dos high sierra/iso-9660 apple dos 3.3 pascal albeit read-only full read/write support planned never completed another advantage gs/os prodos 16 written 16-bit code 65816 processor used ii rather primarily 8-bit 6502 machine code take advantage ii unique features also extends prodos file system provide resource forks files similar used apple macintosh allows programs written flexible way big change previous versions prodos gs/os incorporates many features macintosh system 5 particular gs/os finder loadable fonts plug-in device drivers modem printer etc. command-line development environment called apw apple programmer workshop available much like macintosh programmer workshop
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Operating systems
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