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realtek remote control protocol realtek remote control protocol rrcp developed realtek application layer protocol running directly ethernet frames main idea behind protocol allow direct access ethernet switch controller internal register ethernet network approach allows avoid cost including processor ram flash memory etc managed ethernet switch instead intelligence targeted reside nearby computer running special rrcp-aware ethernet switch management software packets transmitted ethernet frames ethertype 0x8899 details rrcp protocol listed datasheets chipsets rrcp support rtl8324bp rtl8326 used initiate scan rrcp-capable switches network segment fetch parameters sent rrcp-capable switch response valid hello packet contains parameters ids mac addresses used fetch value internal switch controller register sent rrcp-capable switch response valid get packet contains requested register number value read used set internal switch controller register certain value contains register number value written register acknowledgment generated switch part rrcp protocol closely associated underlying mechanism simplified spanning tree protocol substitute rrcp-capable switch controllers part rrcp protocol closely associated underlying mechanism layer-2 analog icmp echo request type 8 message rrcp-capable switch controllers part rrcp protocol closely associated underlying mechanism layer-2 analog icmp echo reply type 0 message rrcp-capable switch controllers currently rrcp protocol officially working realtek rtl8316bp rtl8318p rtl8324p switch controller chips unofficially also found working rtl8316b rtl8324 rtl8326 rtl8326s
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Internet protocols
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routing remote access service routing remote access service rras microsoft api server software makes possible create applications administer routing remote access service capabilities operating system function network router developers also use rras implement routing protocols rras server functionality follows builds upon remote access service ras windows nt 4.0 rras introduced windows 2000 offered download windows nt 4.0 routing services remote access services used work separately point-to-point protocol ppp protocol suite commonly used negotiate point-to-point connections allowed combined rras used create client applications applications display ras common dialog boxes manage remote access connections devices manipulate phone-book entries routing remote access service management pack helps network administrator monitor status availability computers running windows server 2008 r2
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Operating systems
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australian national shipwreck database australian national shipwreck database online searchable database 7,000 known shipwrecks located around coast australia within inland waters originally developed australasian institute maritime archaeology maintained department environment
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Databases
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alan sherman alan theodore sherman born february 26 1957 full professor computer science umbc director umbc center information security assurance cisa director umbc chess program sherman editor cryptologia member phi beta kappa sigma xi sherman earned bachelor degree mathematics brown university 1978 master degree electrical engineering computer science mit 1981 ph.d. degree computer science mit 1987 professor sherman research interests include security voting systems cryptology information assurance discrete algorithms sherman faculty advisor umbc chess club since 1991 playing student vs. faculty match recruits chess players worldwide academic scholarships umbc ranked among best college teams winning pan american intercollegiate team chess championship 1996 1998 1999 2000 2001 2002 2005 2008 2009 2012 1997 received meritorious service award uscf contributions college chess
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Computer security
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v-key v-key software-based digital security solutions provider headquartered singapore provides back-end front-end solutions financial institutions mobile payment providers governments implement cloud-based payments authentication mobile banking secured mobile applications user access data protection v-key founded 2011 entrepreneur eddie chau benjamin mah joseph gan.eddie chau also formed digital agency brandtology acquired isentia 2014 started v-key primarily secure mobile devices applications patented technology benjamin mah co-founder chief executive officer v-key general manager e-cop acquired wholly owned subsidiary temasek holdings regional director encentuate acquired ibm co-founded v-key concurrently venture partner venture craft chairman jumpstart asia mentor uob finlabs joseph gan third co-founder v-key joining v-key centre strategic infocomm technologies csit head cryptography lab oversaw research development cryptographic solutions ministry defence singapore companies funded v-key ipv capital ant financial services runs alipay mobile wallet app v-key provides security solutions businesses support cloud-based payments digital identity authentication mobile banking well secured mobile applications via core technology—v-os v-os virtual secure element globally patented certified industry bodies including info-communications media development authority singapore imda national institute standards technology fips 140-2 validation united states technology provides secure data transmission solution used encrypted communications mobile soft token replace hardware tokens well mobile authentication solutions v-key partners financial institutions governments mobile payment providers various markets technology used v-key received following awards
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Computer security
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pastperfect museum software pastperfect museum software application collections archiving designed museums may used various institutions including libraries archives natural history collections pastperfect allows database storage artifacts documents photographs library books pastperfect utilized 9000 museums nationwide pastperfect introduced 1998 primary product pastime software company inc released version 2 later year updated version three 2001 version four 2004 updated version five 2010 remains current edition program pastime software company eventually changed name pastperfect software inc. 2007 pastperfect operates four basic catalogs sorting collections material archive catalog storing documents photograph catalog storing photos tintypes paintings etc objects catalog storing three-dimensional artifacts library catalog storing books would included institution library images uploaded catalog multiple photos per record also stores donor information automatically generates deed gift forms thank letters upon completing certain steps accessioning process certain extensions allow inclusion oral history records transcripts additional online function allows institutions digitize collections make free browse internet pastperfect also contains contact list function storing donors members employee contact information similar catalog format rest program
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Databases
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windows easy transfer windows easy transfer specialized file transfer program developed microsoft allows users windows operating system transfer personal files settings computer running earlier version windows computer running newer version windows easy transfer introduced windows vista included windows 7 windows 8 windows 8.1 operating systems replaces files settings transfer wizard included windows xp offers limited migration services computers running windows 2000 service pack 4 windows xp service pack 2 transfer applications files settings windows easy transfer discontinued windows 10 microsoft partnered laplink provide free version pcmover express alternative limited time. ref name= laplink/microsoft /ref end users also ability upgrade pcmover professional paid version allows transfer applications well windows 2000 microsoft developed user state migration tool command line utility allowed users windows 95 windows 98 windows nt 4.0 migrate data settings newer operating system command-line tool provide graphical user interface additional migration tool titled files settings transfer wizard developed windows xp fstw designed assist users operating system migrating data settings windows 98 windows fstw could launched windows xp cd-rom presented options transfer data settings via direct cable connection 3.5-inch floppy zip disk network connection moreover option create wizard disk available could used initiate migration process earlier system preliminary version windows easy transfer demonstrated windows hardware engineering conference jim allchin 2004 successor files settings transfer wizard scheduled next client version windows operating system windows vista known windows longhorn final release version application intended optionally use specialized usb cable transfer data personal computers supported versions windows easy transfer transfer transferring windows versions later windows 2000 windows 8.1 easy transfer longer export data another computer still open files created earlier version windows windows easy transfer support transferring installed applications transferring certain supported applications windows xp windows vista microsoft planned release supplementary windows easy transfer companion application application remained perpetual beta development final version never released several transfer methods used windows easy transfer support migration 64-bit 32-bit system since windows vista windows support incoming connections serial parallel irda port operating system support incoming connections ethernet wireless lan hpna windows 8.1 windows easy transfer import settings windows 7 windows 8 windows rt another windows 8.1 computer windows vista transfer method supported windows 8.1 saved archive usb drive method transfers easy transfer cable network connection supported
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Operating systems
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mvaas mvaas acronym managed video service refers systems architecture used companies provide enable video monitoring services allow customers easily manage large numbers digital video recorders dvrs network video recorders nvrs scalable video monitoring architecture information customer ’ physical locations video recorders cameras locations customer ’ users must stored central database traditional architecture customer responsible hosting database mvaas architecture database managed video monitoring provider customer customer interacts database video recorders using website also managed video monitoring provider customer freed details hosting database web site information sometimes said “ cloud ” indeed term mvaas intentionally similar common term saas software service term managed video refers fact architecture customer ’ video remains video recorders customer premises stored central database central database holds information mediates access video important maintaining configuring video recorders contain video ensures customer always ultimate control video frees customer video monitoring company continuously consume bandwidth transfer video video recorders central database mvaas architecture additional information may stored central database besides information video recorders users example video monitoring company may store observations comments camera log camera monitored alternative mvaas hosted video service hvaas architecture like mvaas except customer ’ video physically stored central database customers prefer allows simplify video recorders premises
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Distributed computing architecture
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flask flux advanced security kernel flask operating system security architecture provides flexible support security policies joint venture national security agency university utah secure computing corporation project designed provide framework secure operating system development implementation started mach microkernel since shifted focus linux operating system flask core framework security-focused operating systems nsa security-enhanced linux selinux opensolaris fmac trustedbsd means selinux thought implementation flask
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Operating systems
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ipad air 2 ipad air 2 second-generation ipad air tablet computer designed developed marketed apple inc announced october 16 2014 alongside ipad mini 3 released october 22 2014 ipad air 2 thinner faster predecessor ipad air features touch id height screen size ipad air ipad air 2 discontinued march 21 2017 successor 2019 ipad air released march 18 2019 ipad air 2 announced keynote october 16 2014 first ipad feature touch id theme keynote way long air 2 began arriving retail stores october 22 2014 slogan device change air release new ipad pro slogan device changed light heavyweight ipad air 2 ships ios 10 formerly ios 8 later ios 9 operating system pre-installed includes version apple pay in-store nfc functionality removed included touch id sensor allows user pay items online without needing enter user card details ios 10 comes several built-in applications camera photos messages facetime mail music safari maps siri calendar itunes store app store notes contacts ibooks home reminders clock videos news photo booth podcasts apple app store digital application distribution platform ios allows users browse download applications made various developers itunes store additional apps made apple available free download imovie garageband itunes u find iphone find friends apple store trailers remote iwork apps pages keynote numbers like ios devices ipad air 2 also sync content data mac pc using itunes although tablet designed make phone calls cellular network place receive phone calls iphone cellular connection using apple continuity feature supported ios 8 later versions ios os x yosemite later versions macos using voip application skype june 8 2015 announced wwdc ipad air 2 would support ios 9 new features released q3 2015 air 2 users ios 9 able use slide picture picture split view slide allows user slide second app side screen smaller window display information alongside initial app picture picture allows user watch video small resizable moveable window remaining another app split view allows user run two apps simultaneously 50/50 view ipad air 2 inherits hardware similar iphone 6 iphone 6 plus major change processor apple a8x high-end 3-core variant apple a8 ipad air 2 2 gb ram making ipad air 2 first ios device 1 gb ram powervr gpu 8 cores also uses apple m8 motion co-processor barometer first generation ipad inherit fingerprint touch id sensor iphone addition compared ipad air includes improved 8-megapixel 3264×2448 rear-facing camera 10 fps burst mode slow motion video 120 fps similar iphone 5s camera capabilities front-facing facetime hd camera also improved larger ƒ/2.2 aperture allows 81 light image apple added gold option existing silver space gray color choices ipad air 2 previous existing colors used preceding ipad air unlike ipad predecessors mute/orientation lock switch removed accommodate reduced depth instead user must use control center access functions slightly smaller battery compared ipad air although apple claims 10-hour battery life ipad air 2 available 16 32 64 128 gb storage options storage expansion options apple released camera connection kit sd card reader used transfer photos videos ipad verge called air 2 best tablet ever made giving score 9.3 10 noting offered iterative improvement missed opportunities design
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Operating systems
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disk ng disk ng series two namco video game compilations msx released japan compilations five ports namco arcade games exclusive game released march 9 1990 released april 26 1990
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Computer architecture
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regin malware regin also known prax qwerty sophisticated malware hacking toolkit used united states national security agency nsa british counterpart government communications headquarters gchq first publicly revealed kaspersky lab symantec intercept november 2014 malware targets specific users microsoft windows-based computers linked us intelligence gathering agency nsa british counterpart gchq intercept provided samples regin download including malware discovered belgian telecommunications provider belgacom kaspersky lab says first became aware regin spring 2012 earliest samples date 2003 name regin first found virustotal website 9 march 2011 among computers infected worldwide regin 28 percent russia 24 percent saudi arabia 9 percent mexico ireland 5 percent india afghanistan iran belgium austria pakistan kaspersky lab recently discovered multiple attack vectors used usb bios modification allows bulk malware injected ports 1,2,3 5 many extra services processes visible victim 'back room creators finds collisions sha2 message digests suggesting lot cpu time taken virus-software updates slightly altered updates per user e.g 256 bytes random data collisions every user would carried kaspersky said malware main victims private individuals small businesses telecom companies regin compared stuxnet thought developed well-resourced teams developers possibly western government targeted multi-purpose data collection tool according die welt security experts microsoft gave name regin 2011 cunning norse dwarf regin regin uses modular approach allowing load features exactly fit target enabling customized spying design makes highly suited persistent long-term mass surveillance operations targets regin stealthy store multiple files infected system instead uses encrypted virtual file system evfs entirely contained within looks like single file innocuous name host within files identified numeric code name evfs employs variant encryption rarely used rc5 cipher regin communicates internet using icmp/ping commands embedded http cookies custom tcp udp protocols command control server control operations upload additional payloads etc symantec says kaspersky identified malware backdoor.regin antivirus programs including kaspersky october 2015 identify sample regin released intercept malware 9 march 2011 microsoft added related entries malware encyclopedia later two variants regin.b regin.c added microsoft appears call 64-bit variants regin prax.a prax.b microsoft entries technical information kaspersky symantec published white papers information learned malware german news magazine der spiegel reported june 2013 us intelligence national security agency nsa conducted online surveillance european union eu citizens eu institutions information derives secret documents obtained former nsa worker edward snowden der spiegel intercept quote secret 2010 nsa document stating made cyberattacks year without specifying malware used eu diplomatic representations washington d.c. representations united nations signs identifying software used regin found investigators infected machines intercept reported 2013 uk gchq attacked belgacom belgium largest telecommunications company attacks may led regin coming attention security companies based analysis done security firm fox der spiegel reported november 2014 regin tool uk usa intelligence agencies fox found regin computers one customers according analysis parts regin mentioned nsa ant catalog names straitbizarre unitedrake fox name customer der spiegel mentioned among customers fox belgacom cited head fox ronald prins stated allowed speak found belgacom network december 2014 german newspaper bild reported regin found usb flash drive used staff member chancellor angela merkel checks high-security laptops german chancellery revealed additional infections regin used october november 2018 hack research development unit yandex
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Computer security
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macintosh quadra 605 macintosh quadra 605 also sold macintosh lc 475 macintosh performa 475 personal computer designed manufactured sold apple computer inc. october 1993 july 1996 model names reflect decision made apple 1993 follow emerging industry trend naming product families target customers quadra business lc education performa home accordingly performa 475 476 sold department stores electronics stores circuit city whereas quadra purchased authorized apple reseller introduced quadra 605 least expensive new computer apple lineup performa 410 introduced time price 1,000 usd included monitor based much older macintosh lc ii 16 mhz 68030 processor quadra 605 reuses macintosh lc iii pizza box form factor minor modifications quadra 605 discontinued october 1994 lc 475 variant continued sold schools july 1996 apple offered direct replacement machines making final macintosh use lc lightweight slim-line form factor apple would release another desktop computer mac mini nearly ten years later models come standard 68lc040 cpu running 25 mhz 4 mb ram board 512 kb vram expandable 1 mb 1 lc iii-style processor direct slot 1 adb 2 serial ports external scsi port manual-inject floppy drive introduced october 18 1993 introduced october 21 1993 central processing unit 25 mhz mc68lc040 32-bit bus 8 kb on-chip l1 cache divided 4 kb data 4 kb instruction cache caches although l2 cache possible via lc pds card 68lc040 replaced 68040 includes onboard floating point unit approximately triple speed floating point operations random access memory 4 mb motherboard one 72-pin simm socket 80 ns faster simms official supported maximum ram 36 mb one 32 mb 72-pin simm plus 4 mb motherboard larger simms work—up 128 mb may used limits ram type physical limits might apply side simm facing cpu thicker chips clips simm socket close around automatically possible manually push clips enough hold simm place djmemc memory controller used quadra 605 predecessors quadra/centris 610 quadra/centris 650 quadra 800 recognize simms 32 mb newer memcjr used quadra 605 recognizes larger sizes video video provided one da15f connector compatible vga monitors use adaptor two internal video ram slots take either two 256 kb 80 ns 68-pin vram simms two 512 kb simms installing one 512 kb one 256 kb vram simm garbles display resolutions colors available two vram configurations shown table audio recording possible 11,000 22,000 samples/second filters applied 3.5 khz 7 khz respectively recording floppy drive 1.4 mb superdrive manual-inject hard drive 80 mb 160 mb 230 mb scsi hard drive depending model battery quadra 605s take lithium half-aa cell 3.6 v battery battery drained video start start quadra 605 flat missing battery turned seconds turned second leaves enough charge system capacitors video start power supply 30 watts standard many second-hand machines come replacement psus either third-party apple replacement stripped earlier lc models go 45 watts quadra 605 registered energy star-compliant product weight 8.8 lb 4 kg standard quadra 605 support monitor 35 lb 15.9 kg dimensions 2.9 high x 12.2 wide x 15.3 deep 7.4 cm high x 31 cm wide x 38.8 cm deep quadra 605 contains one lc iii-style 68030-compatible lc processor direct slot mechanically compatible previous models lc pds take 96-pin 114-pin lc pds slot cards true lc pds emulates previous machine 68030 slot due success lc pds earlier macs many expansion options already manufactured apple kept slot type 68040 machines quadra 605 lc pds mostly 68030-compatible expansion cards made specifically '030 processors 68881 68882 fpus work addition utilize apple iie card allows 605 emulate apple iie quadra 605 one scsi bus 50-pin internal connector space one low-profile 3.5 scsi device one 25-pin db25f external connector scsi provided ncr 53c96 controller achieve 6 mb/s internally fast enough drive 4 mb/s externally two serial ports provided quadra 605 one 8-pin mini-din printer port one 9-pin mini-din modem port similar printer port extra pin supply +5 v power adb power supply apple recommends 100 drawn pin quadra 605 like macintoshes manufactured 1999 includes apple desktop bus port use keyboard mouse low-speed low-power peripherals earlier models also contain rom simm socket located left vram simms made slot boards contain solder pads indicating position roms used production machines two surface mount chips located directly behind cpu quadra 605s use 1024 kb rom version 7c quadra 605 compatible apple macintosh processor upgrade card provided 50 mhz powerpc 601 cpu daystar digital sonnet manufactured 100 mhz versions card could also used quadra 605 upgrade cards fitted lc pds expansion slot making slot unavailable expansion cards quadra 605s cuda reset switch used manually reset pram located towards rear motherboard front audio port labeled s1 others include switch instead two solder pads within silkscreened square keyboard power-on key start quadra 605 soft power-on rocker switch back turn quadra 605 pressing power-on key booted selecting shut command finder quadra 605 completed shutdown process prompt operator manually turn quadra 605s reset button programmer button key combinations perform functions reset users hold command control power keys programmer button click users hold command power keys hard crash situations even enough restore system case power switch recourse modified quadra 605 motherboard used basis early apple interactive television box prototypes later prototypes used board design still retained resemblance 605 standard gestalt id 25 mhz quadra 605 94 id logic board quadra 605 shares lc/performa models depends two things jumper j18 located behind hard drive identify computer quadra 605 id 94 25 mhz lc475/performa 47x id 89 25 mhz over-clocking under-clocking motherboard also changes gestalt id list gestalt ids returned various logic board modifications speed reported newer technology clockometer follows standard quadra 605 capable running classic mac os versions 7.1 7.1.1 pro 7.5 7.5.1 7.5.3 7.5.5 7.6 7.6.1 8.0 8.1 powerpc upgrade installed run 8.5 8.5.1 8.6 9.0 9.0.1 9.0.2 9.0.3 9.0.4 9.1 versions system software 7.5 require use system enabler 065 quadra 605 running version system 7.1 over-clocking standard 25 mhz 33 mhz change gestalt id enabler recognize new id under-clocking 20 mhz however change gestalt id one enabler n't recognize compatible system wo n't boot system 7.5 later affected issue
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Computer architecture
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network intelligence network intelligence ni technology builds concepts capabilities deep packet inspection dpi packet capture business intelligence bi examines real time ip data packets cross communications networks identifying protocols used extracting packet content metadata rapid analysis data relationships communications patterns also sometimes referred network acceleration piracy ni used middleware capture feed information network operator applications bandwidth management traffic shaping policy management charging billing including usage-based content billing service assurance revenue assurance market research mega panel analytics lawful interception cyber security currently incorporated wide range applications vendors provide technology solutions communications service providers csps governments large enterprises ni extends network controls business capabilities security functions data mining new products services needed since emergence web 2.0 wireless 3g 4g technologies evolution growth internet wireless technologies offer possibilities new types products services well opportunities hackers criminal organizations exploit weaknesses perpetrate cyber crime network optimization security solutions therefore need address exponential increases ip traffic methods access types activity volume content generated traditional dpi tools established vendors historically addressed specific network infrastructure applications bandwidth management performance optimization quality service qos dpi focuses recognizing different types ip traffic part csp ’ infrastructure ni provides granular analysis enables vendors create information layer metadata ip traffic feed multiple applications detailed expansive visibility network-based activity ni technology goes beyond traditional dpi since recognizes protocols also extracts wide range valuable metadata ni ’ value-add solutions traditionally based dpi attracted attention industry analysts specialize dpi market research example heavy reading includes ni companies deep packet inspection semi-annual market tracker much way bi technology synthesizes business application data variety sources business visibility better decision-making ni technology correlates network traffic data variety data communication vehicles network visibility enabling better cyber security ip services ongoing changes communications networks information exchanged people longer linked exclusively physical subscriber lines person communicate multiple ways – ftp webmail voip instant messaging online chat blogs social networks – different access points via desktops laptops mobile devices ni provides means quickly identify examine correlate interactions involving internet users applications protocols whether protocols tunneled follow osi model technology enables global understanding network traffic applications need correlate information contacts accesses database information viewed combined traditional bi tools examine service quality customer care ni creates powerful nexus subscriber network data telcos internet service providers isps mobile network operators mnos increasing competitive pressures move smart pipe business models cost savings revenue opportunities driving smart pipe strategies also apply network equipment providers software vendors systems integrators serve industry ni captures detailed information hundreds ip applications cross mobile networks provides required visibility analysis user demand create deliver differentiating services well manage usage deployed customer metrics especially important telecom companies understand consumer behaviors create personalized ip services ni enables faster sophisticated audience measurement user behavior analysis customer segmentation personalized services real-time network metrics equally important companies deliver manage services ni classifies protocols applications layers 2 7 generates metadata communication sessions correlates activity layers applicable bandwidth resource optimization quality service qos content-based billing quality experience qoe voip fraud monitoring regulatory compliance economics deployment speed cloud computing fueling rapid adoption companies government agencies among concerns however risks information security e-discovery regulatory compliance auditing ni mitigates risks providing infrastructure service iaas platform service paas software service saas vendors real-time situational awareness network activity critical transparency allay fears potential customers vendor demonstrate hardened network security prevent data leakage data theft irrefutable audit trail network transaction – communication content – related customer ’ account assuming compliance regulation standards ni extracts correlates information contacts providing situational awareness lawful interception cyber security real-time data capture extraction analysis allow security specialists take preventive measures protect network assets real time complement post-mortem analysis attack ni combines real-time network monitoring ip metadata extraction enhances effectiveness applications database security database auditing network protection network visibility afforded ni also used build enhancements next-generation solutions network performance management wan optimization customer experience management content filtering internal billing networked applications
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Computer security
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national cybersecurity communications integration center national cybersecurity communications integration center nccic part office cybersecurity communications u.s. department homeland security acts coordinate various aspects u.s. federal government cybersecurity cyberattack mitigation efforts cooperation civilian agencies infrastructure operators state local governments international partners also responsible coordinating national response significant cyber incidents accordance national cyber incident response plan ncirp nccic consists four branches
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Computer security
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check point check point multinational provider software combined hardware software products security including network security endpoint security cloud security mobile security data security security management check point established ramat-gan israel 1993 gil shwed ceo marius nacht chairman shlomo kramer left check point 2003 shwed initial idea company core technology known stateful inspection became foundation company first product firewall-1 soon afterwards also developed one world first vpn products vpn-1 shwed developed idea serving unit 8200 israel defense forces worked securing classified networks initial funding us 400,000 provided venture capital fund brm group 1994 check point signed oem agreement sun microsystems followed distribution agreement hp 1995 year u.s. head office established redwood city california february 1996 company named worldwide firewall market leader idc market share 40 percent june 1996 check point raised 67 million initial public offering nasdaq 1998 check point established partnership nokia bundled check point software nokia computer network security appliances 2003 class action lawsuit filed check point violation securities exchange act failing disclose major financial information first decade 21st century check point started acquiring security companies including nokia network security business unit 2009 2019 researchers check point found security breach xiaomi phone apps security flaw reported preinstalled check point presently focused calls fifth generation cyber security “ gen v. ” identifies fifth generation focused large-scale fast moving attacks across mobile cloud on-premise networks easily bypass conventional static detection-based defenses used organizations today years many employees worked check point left start software companies include shlomo kremer started imperva nir zuk founded palo alto networks ruvi kitov reuven harrison tufin yonadav leitersdorf founded indeni check point offers following primary products 2005 check point tried acquire intrusion prevention system developers sourcefire 225 million later withdrew offer became clear us authorities specifically committee foreign investment united states would try block acquisition sofaware technologies founded 1999 cooperation check point sofaware founders adi ruppin etay bogner purpose extending check point enterprise market small business consumer branch office market sofaware co-founder adi ruppin said company wanted make technology simple use affordable lift burden security management end users adding features 2001 sofaware began selling firewall appliances sofaware s-box brand 2002 company started selling safe office safe home line security appliances check point brand fourth quarter 2002 sales sofaware safe office firewall/vpn appliances increased greatly sofaware held 1 revenue position worldwide firewall/vpn sub- 490 appliance market 38 revenue market share relations check point sofaware founders went sour company acquisition 2002 2004 etay bogner co-founder sofaware sought court approval file shareholder derivative suit claiming check point transferring funds sofaware required use sofaware products technology derivative suit ultimately successful check point ordered pay sofaware 13 million shekels breach contract 2006 tel aviv district court judge ruled bogner sofaware could sue check point proxy 5.1 million alleged damage sofaware bogner claimed check point owned 60 sofaware behaved belligerently withheld monies due use sofaware technology products check point appealed ruling lost 2009 israeli supreme court ruled group founders sofaware includes bogner veto power decision sofaware court ruled three founders could exercise veto power group majority rule 2011 check point settled litigation relating sofaware part settlement acquired sofaware shares held bogner ruppin began process acquiring remaining shares resulting sofaware becoming wholly owned subsidiary
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Computer security
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generic stream encapsulation gse provides additional features beyond pure carriage ip datagrams increase protocol flexibility applicability key gse functions/characteristics protocol specification published etsi ts 102 606 accompanying implementation guidelines document published etsi ts 102 771 ip datagrams ethernet frames network layer packets encapsulated one gse packets encapsulation process adds control information network protocol type address label provides overall integrity check needed payload frame may encapsulated single gse packet sliced fragments encapsulated several gse packets gse packets general variable length order match input ip traffic minimum overhead gse packets may sent different base band frames necessarily consecutive transmission parameters modulation format coding rate constraint gse packet position within base band frame assumed however gse packets may reordered encapsulator de-encapsulator general base band frame contain single gse packet base band frames may fixed variable length gse provide mechanism integrity check single gse packet crc-32 appended last fragment fragmented payload verify correctness reassembly operation gse relies physical layer able ensure required error detection and/or correction probability gse packet header highly dynamic provides many options minimum header two bytes comprising three flags fields 12-bit payload length field diagram shows possible fields basic mechanism gse payload fragmentation uses start end flags start flag indicates beginning payload frame end flag indicates end shown diagram dvb-s2 dvb-t2 dvb-c2 acm/vcm modes may cause base band frames vary size depending transmission conditions hence may situations first fragments payload frame sent encapsulator forced set aside current payload frame start working new one may e.g occur large fragments prepared transmission conditions fine suddenly conditions deteriorate small base band frames available fragment id field becomes important short-term identification payload frame whenever encapsulator needs move next payload frame without finished transmitting previous one uses next available fragment id way 256 payload frames kept open time decapsulator uses fragment id pick reassembly buffer store fragment label type lt bits determine gse packet address encoded according following table gse packet containing last fragment payload frame carries crc-32 checksum payload frame checksum used detect loss intermediate fragments checksum 32 bit value calculated according generator polynomial represented 0x104c11db7 formula_1 last fragment payload frame lost decapsulator directly detect fact never sees gse frame end flag set containing crc-32 situation decapsulator must choose suitable time-out based data-rate application since gse packets directly inserted base-band frames modulation scheme gse products come form gse routers gse modems outside act much like dsl router dsl modem used consumers generically devices also referred gse encapsulators products standard ip network interface often ethernet similar lan interface collect ip traffic forwarded uni-directional link end optimise packaging base-band frames devices typically generate complete base-band frames gse packets payload transferred dvb-s2 dvb-t2 dvb-c2 modulator second interface likely incomplete list gse en- decapsulators many ip-over-satellite service offerings including instance astra2connect ses tooway eutelsat little detail however known protocols used since receivers provided part service operators little technical detail disclosed
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Internet protocols
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diameter protocol diameter authentication authorization accounting protocol computer networks evolved earlier radius protocol belongs application layer protocols internet protocol suite diameter applications extend base protocol adding new commands and/or attributes use extensible authentication protocol eap name play words derived radius protocol predecessor diameter twice radius diameter directly backwards compatible provides upgrade path radius main features provided diameter lacking radius also like radius intended work local roaming aaa situations uses tcp sctp unlike radius uses udp unlike radius includes encryption protected transport level security ipsec tls base size av identifier 32 bit unlike radius uses 8 bit base av identifier size like radius supports stateless well stateful modes like radius supports application layer acknowledgment defines failover diameter used many different interfaces defined 3gpp standards interface typically defining new commands attributes diameter application software application protocol based diameter base protocol defined rfc 6733 rfc 7075 obsoletes rfc 3588 application defined application identifier add new command codes and/or new mandatory avps attribute-value pair adding new optional avp require new application examples diameter applications generic bootstrapping architecture bootstrapping server function diameter protocol initially developed pat r. calhoun glen zorn ping pan 1998 provide framework authentication authorization accounting aaa could overcome limitations radius radius issues reliability scalability security flexibility radius deal effectively remote access ip mobility policy control diameter protocol defines policy protocol used clients perform policy aaa resource control allows single server handle policies many services like radius diameter provides aaa functionality uses tcp sctp instead udp therefore delegating detection handling communication problems protocols diameter protocol enhanced development 3rd generation partnership project 3gpp ip multimedia subsystem ims cx dh dx rf ro sh zh interfaces supported diameter applications use extensions protocol designed extensible support proxies brokers strong security mobile ip network-access servers nasreq accounting resource management diameter base protocol defined rfc 6733 obsoletes rfc 3588 defines minimum requirements aaa protocol diameter applications extend base protocol adding new commands attributes diameter security provided ipsec tls iana assigned tcp sctp port number 3868 diameter packet consists diameter header variable number attribute-value pairs avps encapsulating information relevant diameter message field indicates version diameter base protocol 2014 value supported 1 message length field indicates length diameter message bytes including header fields padded avps r request bit – set message request cleared message answer p proxiable bit – set message may proxied relayed redirected cleared message must locally processed e error bit – set message contains protocol error message conform ccf described command messages e bit set commonly referred error messages bit must set request messages potentially re-transmitted message bit – flag set link failover procedure aid removal duplicate requests set resending requests yet acknowledged indication possible duplicate due link failure command request/answer pair assigned command code whether request answer identified via ’ r ’ bit command flags field header values 0-255 reserved radius backward compatibility values 256-16777213 permanent standard commands allocated iana values 16777214 16777215 hex 0xfffffe 0xffffff reserved experimental testing purposes command code used determine action taken particular message common diameter commands defined protocol base applications application-id used identify diameter application message applicable application authentication application accounting application vendor-specific application diameter agents conforming certain diameter extension publicize support including specific value auth-application-id attribute capabilities-exchange-request cer capabilities-exchange-answer cea command value application-id field header relevant application-id avps contained message instance value application-id auth-application-id attribute credit-control-request ccr credit-control-answer cca command diameter credit-control application 4 hop-by-hop identifier unsigned 32-bit integer field network byte order used match requests answers value request used response diameter protocol requires relaying proxying agents maintain transaction state used failover purposes transaction state implies upon forwarding request hop-by-hop identifier saved field replaced locally unique identifier restored original value corresponding answer received request ’ state released upon receipt answer received answers match known hop-by-hop identifier ignored diameter agent case redirecting agents hop-by-hop identifier maintained header diameter agent responds answer message end-to-end identifier unsigned 32-bit integer field network byte order used detect duplicate messages along combination origin-host avp creating request end-to-end identifier set locally unique value end-to-end identifier modified diameter agents kind value corresponding request used answer simplicity v bit means vendor specific bit means mandatory p bit means protected v bit known vendor-specific bit indicates whether optional vendor-id field present avp header set avp code belongs specific vendor code address space bit known mandatory bit indicates whether support avp required avp bit set received diameter client server proxy translation agent either avp value unrecognized message must rejected diameter relay redirect agents must reject messages unrecognized avps p bit indicates need encryption end-to-end security rfc 3588 defines core state machine maintaining connections peers processing messages part basic protocol functionality stacks support abstract connectivity related operations additionally application specific state machines introduced either later higher abstraction layer rfc 3588 defines authorization accounting state machine communication two diameter peers starts establishment transport connection tcp sctp initiator sends capabilities-exchange-request cer peer responds capabilities-exchange-answer cea rfc3588 compliant peers tls transport layer security may optionally negotiated rfc6733 compliant peers tls negotiation may optionally happen cer/cea connection ready exchanging application messages messages exchanged time either side may send device-watchdog-request dwr peer must respond device-watchdog-answer either side may terminate communication sending disconnect-peer-request dpr peer must respond disconnect-peer-answer transport connection disconnected diameter protocol currently defined following ietf rfcs obsolete rfcs indicated strikethrough text
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Internet protocols
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usenix usenix association supports operating system research founded 1975 name unix users group focusing primarily study development unix similar systems june 1977 lawyer corporation informed group could use word unix trademark western electric manufacturing arm 1995 led change name usenix since grown respected organization among practitioners developers researchers computer operating systems generally since founding published technical journal entitled usenix started technical organization commercial interest grew number separate groups started parallel notably software tools users group stug technical adjunct unix-like tools interface non-unix operating systems /usr/group commercially oriented user group sponsors several conferences workshops year notably usenix symposium operating systems design implementation osdi usenix symposium networked systems design implementation nsdi usenix annual technical conference usenix security symposium usenix conference file storage technologies fast lisa formerly sage large installation system administration conference lisa usenix founding president lou katz usenix became first computing association provide open access conference workshop papers 2008. remains one done since 2011 included audio video recordings paper presentations open-access materials award also called flame award presented since 1993
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Operating systems
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foreign ship registry act foreign ship registry act federal legislation provided admission foreign-built ships american registry provided admission foreign-built ships american registry foreign trade making easier legally hoist american flag bill provided survey measurement inspection ships though require american ownership majority stock corporations applying american registry clear violation international custom international law theoretically germany could get american registration hoist u.s. flag merchant vessels avoid british blockade possibility provoked much british protest however german owners vessels american harbors dared risk losing property take advantage act september 7 1917 president woodrow wilson issued executive order 2696 suspending united states statute period two years
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Databases
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thomas bushnell thomas bushnell bsg formerly known michael bushnell born december 13 1967 software developer gregorian friar founder principal architect gnu official kernel project gnu hurd bushnell also hurd official maintainer instigation november 2003 posted gnu project discussion mailing list saying dismissed richard stallman criticizing gnu free documentation license stallman said dismissal bushnell inactive since 2001 n't responding mail bushnell currently maintains debian packages employed google llc member saint mark episcopal church glendale ca
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Operating systems
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public-key cryptography public-key cryptography asymmetric cryptography cryptographic system uses pairs keys public keys may disseminated widely private keys known owner generation keys depends cryptographic algorithms based mathematical problems produce one-way functions effective security requires keeping private key private public key openly distributed without compromising security system person encrypt message using receiver public key encrypted message decrypted receiver private key robust authentication also possible sender combine message private key create short digital signature message anyone corresponding public key combine message putative digital signature known public key verify whether signature valid i.e made owner corresponding private key public key algorithms fundamental security ingredients modern cryptosystems applications protocols assuring confidentiality authenticity non-repudiability electronic communications data storage underpin various internet standards transport layer security tls s/mime pgp gpg public key algorithms provide key distribution secrecy e.g. diffie–hellman key exchange provide digital signatures e.g. digital signature algorithm provide e.g. rsa mid-1970s cipher systems using symmetric key algorithms cryptographic key used underlying algorithm sender recipient must keep secret necessity key every system exchanged communicating parties secure way prior use system – secure channel requirement never trivial rapidly becomes unmanageable number participants increases secure channels n't available key exchange sensible cryptographic practice keys frequently changed particular messages meant secure users separate key required possible pair users contrast public key system public keys disseminated widely openly private key needs kept secure owner two best-known uses public key cryptography one important issue confidence/proof particular public key authentic i.e correct belongs person entity claimed tampered replaced malicious third party several possible approaches including public key infrastructure pki one third parties – known certificate authorities – certify ownership key pairs tls relies upon web trust decentralizes authentication using individual endorsements link user public key pgp uses approach well lookup domain name system dns dkim system digitally signing emails also uses approach obvious application public key encryption system encrypting communication provide confidentiality – message sender encrypts using recipient public key decrypted recipient paired private key another application public key cryptography digital signature digital signature schemes used sender authentication non-repudiation system use digital signatures ensure one party successfully dispute authorship document communication applications built foundation include digital cash password-authenticated key agreement time-stamping services non-repudiation protocols etc asymmetric key algorithms nearly always much computationally intensive symmetric ones many cases common exchange key using key-exchange algorithm transmit data using key symmetric key algorithm pgp ssh ssl/tls family schemes use procedure thus called hybrid cryptosystems like security-related systems important identify potential weaknesses public key schemes theory susceptible brute-force key search attack attacks however impractical amount computation needed succeed – termed work factor claude shannon – reach potential attackers many cases work factor increased simply choosing longer key algorithms may much lower work factors making resistance brute-force attack irrelevant special specific algorithms developed aid attacking public key encryption algorithms – rsa elgamal encryption known attacks much faster brute-force approach major weaknesses found several formerly promising asymmetric key algorithms knapsack packing algorithm found insecure development new attack recently attacks based careful measurements exact amount time takes known hardware encrypt plain text used simplify search likely decryption keys side-channel attack great deal active research currently underway discover protect new attack algorithms another potential security vulnerability using asymmetric keys possibility man-in-the-middle attack communication public keys intercepted third party man middle modified provide different public keys instead encrypted messages responses must also intercepted decrypted re-encrypted attacker using correct public keys different communication segments instances avoid suspicion attack may seem difficult implement practice impossible using insecure media e.g. public networks internet wireless forms communications – example malicious staff member internet service provider isp might find quite easy carry one approach prevent attacks involves use public key infrastructure pki set roles policies procedures needed create manage distribute use store revoke digital certificates manage public-key encryption however turn potential weaknesses example certificate authority issuing certificate must trusted properly checked identity key-holder must ensure correctness public key issues certificate must secure computer piracy must made arrangements participants check certificates protected communications begin web browsers instance supplied long list self-signed identity certificates pki providers – used check bona fides certificate authority second step certificates potential communicators attacker could subvert single one certificate authorities issuing certificate bogus public key could mount man-in-the-middle attack easily certificate scheme used alternate scenario rarely discussed attacker penetrated authority servers obtained store certificates keys public private would able spoof masquerade decrypt forge transactions without limit despite theoretical potential problems approach widely used examples include tls predecessor ssl commonly used provide security web browser transactions example securely send credit card details online store aside resistance attack particular key pair security certification hierarchy must considered deploying public key systems certificate authority – usually purpose-built program running server computer – vouches identities assigned specific private keys producing digital certificate public key digital certificates typically valid several years time associated private keys must held securely time private key used certificate creation higher pki server hierarchy compromised accidentally disclosed man-in-the-middle attack possible making subordinate certificate wholly insecure examples well-regarded asymmetric key techniques varied purposes include examples asymmetric key algorithms widely adopted include examples notable – yet insecure – asymmetric key algorithms include examples protocols using asymmetric key algorithms include early history cryptography two parties would rely upon key would exchange means secure non-cryptographic method face-to-face meeting trusted courier key parties kept absolutely secret could used exchange encrypted messages number significant practical difficulties arise approach distributing keys 1874 book principles science william stanley jevons wrote reader say two numbers multiplied together produce number 8616460799 think unlikely anyone ever know described relationship one-way functions cryptography went discuss specifically factorization problem used create trapdoor function july 1996 mathematician solomon w. golomb said jevons anticipated key feature rsa algorithm public key cryptography although certainly invent concept public key cryptography 1970 james h. ellis british cryptographer uk government communications headquarters gchq conceived possibility non-secret encryption called public key cryptography could see way implement 1973 colleague clifford cocks implemented become known rsa encryption algorithm giving practical method non-secret encryption 1974 another gchq mathematician cryptographer malcolm j. williamson developed known diffie–hellman key exchange scheme also passed usa national security agency military focus low computing power power public key cryptography unrealised organisations judged important military use ... share key rapidly electronically major advantage opponent end evolution berners-lee designing open internet architecture cern adaptation adoption arpanet ... public key cryptography realise full potential —ralph benjamin discovery publicly acknowledged 27 years research declassified british government 1997 1976 asymmetric key cryptosystem published whitfield diffie martin hellman influenced ralph merkle work public key distribution disclosed method public key agreement method key exchange uses exponentiation finite field came known diffie–hellman key exchange first published practical method establishing shared secret-key authenticated confidential communications channel without using prior shared secret merkle public key-agreement technique became known merkle puzzles invented 1974 published 1978 1977 generalization cocks scheme independently invented ron rivest adi shamir leonard adleman mit latter authors published work 1978 algorithm came known rsa initials rsa uses exponentiation modulo product two large primes encrypt decrypt performing public key encryption public key digital signature security connected extreme difficulty factoring large integers problem known efficient general technique since 1970s large number variety encryption digital signature key agreement techniques developed field public key cryptography including rabin cryptosystem elgamal encryption dsa elliptic curve cryptography
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Computer security
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stand-alone shell stand-alone shell codice_1 unix shell designed use recovering certain types system failures built-in commands sash libraries linked statically unlike shells linux standard unix commands rely external libraries example copy command cp requires libc.so ld-linux.so built gnu core utilities linux libraries get corrupted coreutils cp command would work however sash built-in command cp would unaffected earlier times critical commands including shells /sbin even /bin statically linked purpose whereas /usr/sbin /usr/bin would find feature-rich versions dynamically linked common anymore statically linked shells built-in commands become important sash following built-in commands sash shell also ported work androidin terminal-interface sash-plus-patches collection patches sash key features codice_32 codice_33 codice_19 commands however functions available newer versions sash functions provide interfaces respective linux system calls especially useful sash used initial ramdisk initrd environment addition simple shell variable expansion support added e.g. variable var replaced content environment variable var linux distributions debian slackware via slackbuilds.org available
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Operating systems
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initial ramdisk computing specifically regards linux computing codice_1 initial ramdisk scheme loading temporary root file system memory may used part linux startup process codice_1 codice_3 refer two different methods achieving commonly used make preparations real root file system mounted many linux distributions ship single generic linux kernel image one distribution developers create specifically boot wide variety hardware device drivers generic kernel image included loadable kernel modules statically compiling many drivers one kernel causes kernel image much larger perhaps large boot computers limited memory raises problem detecting loading modules necessary mount root file system boot time matter deducing root file system complicate matters root file system may software raid volume lvm nfs diskless workstations encrypted partition require special preparations mount another complication kernel support hibernation suspends computer disk dumping image entire contents memory swap partition regular file powering next boot image made accessible loaded back memory avoid hardcode handling many special cases kernel initial boot stage temporary root file-system — dubbed early user space — used root file-system contain user-space helpers hardware detection module loading device discovery necessary get real root file-system mounted image initial root file system along kernel image must stored somewhere accessible linux bootloader boot firmware computer root file system boot image optical disc small partition local disk boot partition usually using ext2 fat file systems tftp server systems boot ethernet bootloader load kernel initial root file system image memory start kernel passing memory address image end boot sequence kernel tries determine format image first blocks data lead either initrd initramfs scheme initrd scheme image may file system image optionally compressed made available special block device mounted initial root file system driver file system must compiled statically kernel many distributions originally used compressed ext2 file system images others including debian 3.1 used cramfs order boot memory-limited systems since cramfs image mounted in-place without requiring extra space decompression initial root file system kernel executes first process exits kernel assumes real root file system mounted executes begin normal user-space boot process initramfs scheme available since linux kernel 2.6.13 image may cpio archive optionally compressed archive unpacked kernel special instance tmpfs becomes initial root file system scheme advantage requiring intermediate file system block drivers compiled kernel systems use dracut package create initramfs image initramfs scheme kernel executes first process expected exit.. applications initramfs use casper utility create writable environment using unionfs overlay persistence layer read-only root filesystem image example overlay data stored usb flash drive compressed squashfs read-only image stored live cd acts root filesystem depending algorithms compiled statically kernel unpack initrd/initramfs images compressed gzip bzip2 lzma xz lzo lz4 linux distributions debian generate customized initrd image contains whatever necessary boot particular computer ata scsi filesystem kernel modules typically embed location type root file system linux distributions fedora ubuntu generate generic initrd image start device name root file system uuid must discover everything else boot time case software must perform complex cascade tasks get root file system mounted distributions use event-driven hotplug agent udev invokes helper programs hardware devices disk partitions storage volumes matching certain rules come online allows discovery run parallel progressively cascade arbitrary nestings lvm raid encryption get root file system root file system finally becomes visible maintenance tasks run mounted root file system done root file system mounted read-only processes must continue running splash screen helper command fifo hoisted newly mounted root file system final root file system simply mounted since would make scripts tools initial root file system inaccessible final cleanup tasks initial root file systems implement shell script thus include minimal shell usually /bin/ash along essential user-space utilities usually busybox toolkit save space shell utilities supporting libraries typically compiled space optimizations enabled gcc -os flag linked klibc minimal version c library written specifically purpose installers linux distributions typically run entirely initramfs must able host installer interface supporting tools persistent storage set tiny core linux puppy linux run entirely initrd since windows vista windows boot wim disk image file file format officially published rather similar zip format except supports hard links uses chunk-by-chunk compression support deduplicated chunks case whole wim initially loaded ram followed kernel initialisation next loaded wim available systemroot assigned drive letter windows installer uses boots boot.wim uses install.wim collection windows files installed also windows preinstallation environment windows pe uses base separate-boot versions antivirus backup/disaster recovery software also possible install windows always boot wim vhd file placed physical drive however rarely used since windows boot loader capable loading .sys files boot-time kernel modules task requires initrd linux
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Computer architecture
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ragel ragel finite-state machine compiler parser generator initially ragel supported output c c++ assembly source code although subsequently extended support several languages said objective c go ruby java support languages withdrawn supports generation table control flow driven state machines regular expressions and/or state charts also build lexical analysers via longest-match method ragel specifically targets text parsing input validation ragel supports generation table control flow driven state machines regular expressions and/or state charts also build lexical analysers via longest-match method unique feature ragel user actions associated arbitrary state machine transitions using operators integrated regular expressions ragel also supports visualization generated machine via graphviz graph represents state-machine takes user input series bytes representing ascii characters control codes 48..57 equivalent regular expression 0-9 i.e digit sequences beginning digit recognised 10 line feed encountered 're done 46 decimal point 43 45 positive negative signs '+ '- 69/101 uppercase/lowercase e indicate number scientific format recognize following properly
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Programming language topics
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asset disposal information security alliance asset disposal information security alliance adisa organization recommends standards safely disposing information technology equipment minimizing risk exposure misuse sensitive data stored equipment adisa standards cover phases asset disposal including collection transportation storage erasure destruction components containing data recycling waste disposal certification includes periodic audits founded 2010 adisa publishes separate versions standard asia/pacific european union north america united kingdom adisa asset disposal security standard recognized industry standard merit uk defence infosec product co-operation group dipcog
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Computer security
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entropy-supplying system calls entropy-supplying system calls system calls unix-like operating system kernels processes obtain entropic random data first codice_1 introduced openbsd operating system release 5.6 november 2014 refactoring sysctl 3 kern_arnd approach used since 1997 linux offers similar system call codice_2 based codice_1 first available linux 3.17 released october 2014 july 2015 solaris introduced slightly modified versions codice_1 codice_2 august 2015 freebsd introduced codice_6 system call obtaining random data kernel system calls allow processes access quality random data without opening reading randomness pseudo-devices microsoft windows codice_7 apple ios codice_8 api similar however implemented system calls traditionally unix-like operating systems supply random data two pseudo-devices codice_9 codice_10 however safely reliably reading random data devices difficult complicated example attacker could interfere process access pseudo-devices opening available file descriptors similar form resource exhaustion attack use devices also interferes privilege revocation unprivileged processes often denied ability open read files devices randomness devices even visible chrooted processes difficulty using randomness pseudo-devices often leads developers use standard library functions instead c programming language codice_11 codice_12 codice_13 unsafe used cryptography similar applications algorithms actually deterministic intentionally crippled satisfy seed-reuse requirements interfaces codice_14 codice_15 codice_16 significant difference exists calls codice_17 guarantees random numbers returned immediately without blocking requires operating support guarantees random data stream initialization earliest opportunity encourage operating systems follow model getentropy indicate errors application calls described may return errors instead block indeterminately blocking semantics implicated significant problems security becomes widespread priority software development quality randomness used often contexts providing quality randomness increasingly considered core responsibility kernel system calls traditional interface process uses core kernel services kernels therefore supporting accessing randomness system calls faster adds another layer entropy mixing usually suggested processes use syscalls data userspace cryptographically secure pseudorandom number generator csprng rather assigning retrieved data directly variables purpose openbsd c standard library includes function codice_18 programs expected call need random data like codice_1 codice_18 also may block return error approach allows program fetch less entropy kernel without reducing strength random data codice_1 system call designed based assumption supplying 256 bytes per call
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Computer architecture
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intrinsic function computer software compiler theory intrinsic function builtin function function subroutine available use given programming language whose implementation handled specially compiler typically may substitute sequence automatically generated instructions original function call similar inline function unlike inline function compiler intimate knowledge intrinsic function thus better integrate optimize given situation compilers implement intrinsic functions generally enable program requests optimization otherwise falling back default implementation provided language runtime system environment intrinsic functions often used explicitly implement vectorization parallelization languages address constructs application programming interfaces api example altivec openmp use intrinsic functions declare respectively vectorizable multiprocessing-aware operations compiling compiler parses intrinsic functions converts vector math multiprocessing object code appropriate target platform compilers c c++ microsoft intel gnu compiler collection gcc implement intrinsics map directly x86 single instruction multiple data simd instructions mmx streaming simd extensions sse sse2 sse3 ssse3 sse4 microsoft visual c++ compiler microsoft visual studio support inline assembly x86-64 compensate new intrinsics added map standard assembly instructions normally accessible c/c++ e.g. bit scan c c++ compilers provide non-portable platform-specific intrinsics intrinsics gnu built-ins slightly abstracted approximating abilities several contemporary platforms portable fall back implementations platforms appropriate instructions common c++ libraries glm sony vector maths libraries achieve portability via conditional compilation based platform specific compiler flags providing fully portable high-level primitives e.g. four-element floating-point vector type mapped onto appropriate low level programming language implementations still benefiting c++ type system inlining hence advantage linking hand-written assembly object files using c application binary interface abi hotspot java virtual machine jvm just-in-time compiler also intrinsics specific java apis hotspot intrinsics standard java apis may one optimized implementation platforms
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Programming language topics
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pando networks founded 2004 new york city pando networks managed peer-to-peer p2p media distribution company backed intel capital brm capital wheatley partners company specialized cloud distribution games video software publishers media distributors also operated freemium consumer business sending large files pando network technology based bittorrent modifications hybrid p2p- server-based network included central control file distribution intelligent throttling peers servers reporting/analytics security spring 2006 company publicly launched pando small application let consumers bypass email attachment limits send large files 1gb regardless email service provider late may 2009 30 million people installed pando application late 2007 along verizon communications pando networks co-founded p4p “ proactive network provider participation p2p ” working group serve p2p companies internet service providers isps seeing much 70 percent bandwidth go p2p traffic p4p working group includes mix 50 p2p companies isps including telefónica comcast yale computer science research team developed p4p technical protocol believed could speed p2p content delivery lowering isp network utilization collaboration yale p4p working group pando networks adopted technology laird popkin coordinated test summer 2008 showing promising results company released first commercial service may 2008 media distributors could plug pando networks peer cloud existing content delivery networks cdns combination peer cloud plus cdn allows files high demand quickly cost effectively delivered peers long tail content reliably served cdn nbc universal incorporated pando networks ’ technology later year deliver high-definition tv episodes consumers ’ pcs game industry pando networks ’ largest customer segment installation files particularly massively multiplayer online games mmos reach well 1gb pando networks game customers included nexon turbine riot games gala-net levelup may 2010 pando networks surpassed 30 million game downloads pando networks acquired microsoft march 2013
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Distributed computing architecture
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x window system protocols architecture computing x window system commonly x11 x network-transparent windowing system bitmap displays article details protocols technical structure x11 x uses client–server model x server program runs computer graphical display communicates various client programs x server acts go-between user client programs accepting requests tcp port 6000 graphical output windows client programs displaying user display receiving user input keyboard mouse transmitting client programs x server runs user computer clients may run remote machines terminology reverses common notion client–server systems client normally runs user local computer server runs remote computer x window terminology takes perspective x window program centre activity i.e x window program accepts responds requests applications user mouse keyboard input therefore applications remote computers viewed clients x window server program communication protocol server client runs network-transparently client server may run machine different ones possibly different architectures operating systems client server communicate securely internet tunneling connection encrypted connection bob scheifler jim gettys set early principles x follows listed scheifler/gettys 1996 first principle modified design x11 add new functionality unless know real application require x largely kept principles since x.org foundation develops reference implementation view extension improvement implementation whilst keeping almost entirely compatible original 1987 protocol communication server clients done exchanging packets network channel client establishes connection sending first packet server answers sending back packet stating acceptance refusal connection request authentication connection accepted acceptance packet contains data client use subsequent interaction server connection established client server exchange four different types packets channel x server provides set basic services client programs realize complex functionalities interacting server graphical user interfaces usually call window top-level window x window system term window also used windows lie within another window subwindows parent window graphical elements buttons menus icons etc realized using windows window created subwindow parent window causes windows arranged hierarchically tree x server automatically creates root tree called root window top-level windows exactly direct subwindows root window visibly root window large screen lies behind windows x server stores data windows fonts etc client knows identifiers objects – integers use names interacting server example client wishes window created requests server create one case success gets return identifier server associated newly created window identifier later used client request example string drawn window identifiers unique server client example two windows identifier even created two different clients client access object given identifier even another client created object every window predefined set attributes set properties stored x server accessible clients via appropriate requests attributes data window size position background color etc properties pieces data attached window unlike attributes properties meaning level x window core protocol client store arbitrary data property window property characterized name type value properties resemble variables imperative programming languages application create new property given name given type store value properties associated windows two properties name exist two different windows different types values properties mostly used inter-client communication example property named codice_1 stores name window window managers typically read property display name window top codice_2 program display properties window particular codice_3 shows properties root window include x resources parameters programs events packets sent server client communicate something happened may interest client client request server send event another client used communication clients example client requests text currently selected event sent client currently handling window holds selection content window may destroyed conditions example window covered whenever area destroyed content made visible server generates codice_4 event notify client part window drawn events serve notify clients keyboard mouse input creation new windows etc kinds events always sent client kinds event sent client previously stated interest clients may interested kind events example client may interested keyboard-related event mouse-related events way x window system handles colors sometimes confuse users historically several different modes supported modern applications use truecolor 24-bit color 8 bits red green blue old specialist applications may require different color mode many commercial specialist applications use pseudocolor x11 protocol actually uses single 32-bit unsigned integer called pixelvalue representing single color graphic operations transferring intensity primary colors 16 bit integer used colour component following representations colors exist may supported specific device client programs communicate server via xlib client library beside xlib xcb library operates closely x protocol particular clients use libraries xaw motif gtk+ qt turn use xlib interacting server qt switched xlib xcb 5.0 release client programs almost entirely unaffected change x window core protocol provides mechanisms communication clients window properties events particular client-to-client message events however specify protocol interactions instead separate set inter-client communication conventions governs protocols inter-client communication conventions manual specifies protocol exchange data via selections interaction applications window manager considered specification difficult confusing consistency application look feel communication typically addressed programming given desktop environment inter-client exchange protocol ice specifies framework building protocols interaction clients programmers build specific protocol top particular x session management protocol xsmp protocol based ice governs interaction applications session manager program takes care storing status desktop end interactive session recovering another session user started freedesktop specifications include newer conventions including drag-and-drop convention xdnd used transferring data selecting dragging another window embedded application convention xembed details application run subwindow another application mechanisms selections cut buffers drag-and-drop x window system allow user transfer data one window another selections cut buffer used typically user selects text data window pastes different window drag-and-drop used user selects something window clicks selection drags another window since two different applications may handle two windows data transfer requires different clients connected x server interact x window core protocol includes types requests events specific selection exchange transfer mainly done using general client-to-client event sending window properties specific selection transfer users transfer data different types clients usually text also pixmap number list objects etc selections drag-and-drop active mechanisms user selects data window client handling window must actively support protocol transferring data application requesting cut buffers contrast provide passive mechanism user selects text content transferred cut buffer remains even application handling window terminates window destroyed window manager program controls general appearance windows graphical elements graphical user interface differences look x window system different installations stem mainly use different window managers different configurations window manager window manager takes care deciding position windows placing decorative border around handling icons handling mouse clicks outside windows “ background ” handling certain keystrokes etc point view x server window manager operates client like client initial position decorative borders around windows handled window manager using following requests window manager uses first request intercept request mapping top-level windows children root window whenever another application requests mapping top-level window server sends event window manager instead window managers reparent window create larger top-level window called frame window reparent original window child graphically corresponds placing original window inside frame window space frame window taken original window used decorative frame around window “ border ” “ title bar ” window manager manages mouse clicks frame window allows example user move resize window clicking dragging border title bar window manager also handles icons related visual elements graphical user interface icons exist level x window core protocol implemented window manager example whenever window “ iconified ” fvwm window manager unmaps window creates window icon name possibly another window icon image meaning handling icons therefore completely decided window manager window managers wm2 implement icons roughly state session “ state desktop ” given time set windows current content precisely set applications managing windows information allow applications restore condition managed windows required program known x session manager saves restores state sessions recognizably using session manager permits user log interactive session find exactly windows state logging work session manager program stores names running applications logout starts login order state applications restored well needed restore content windows applications must able save state execution upon request session manager load back start x window system includes default session manager called codice_5 developers written session managers specific desktop systems example codice_6 default session manager kde program known x display manager shows graphical login prompt x window system generally display manager runs one x servers local computer accepts incoming connections x servers running remote computers local servers started display manager connects present user login screen remote servers started independently display manager connect situation display manager works like graphical telnet server x server connect display manager starts session applications utilize session run computer display manager input output computer x server runs may computer front user remote one x window system ships xdm basic supplied display manager display managers include gdm gnome kdm kde wdm using wings widget set used window maker entrance using architecture used enlightenment v.17 early widget toolkits x included xaw athena widget set 1983 olit open look intrinsics toolkit 1988 xview 1988 motif 1980s tk olit xview function base toolkits sun legacy openwindows desktop environment motif provides base toolkit common desktop environment cde desktop environment used commercial unix systems solaris aix hp-ux solaris 10 includes cde gnome latter preferred desktop environment toolkits developed recently include qt 1991- used kde gtk+ 1997- used gnome wxwidgets 1992- fltk 1998- fox 1997- fpgui 2005-current scheifler gettys designed x server simple extensible much functionality resides extensions protocol protocol level every extension assigned new request/event/error packet types extension features accessed client applications extension libraries adding extensions current x server implementations reportedly difficult due lack modularity server design long-term goal xcb project automate generating client server sides extensions xml protocol descriptions following table provides partial catalog extensions developed sorted roughly recency introduction
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Internet protocols
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mariadb mariadb community-developed commercially supported fork mysql relational database management system rdbms intended remain free open-source software gnu general public license development led original developers mysql forked due concerns acquisition oracle corporation mariadb intends maintain high compatibility mysql ensuring drop-in replacement capability library binary parity exact matching mysql apis commands includes new storage engine aria alternative myisam intends default transactional non-transactional engine initially used xtradb default storage engine switched back innodb since version 10.2 lead developer michael monty widenius one founders mysql ab founder monty program ab 16 january 2008 mysql ab announced agreed acquired sun microsystems approximately 1 billion acquisition completed 26 february 2008 mariadb named monty younger daughter maria similar mysql named daughter mariadb version numbers follow mysql numbering scheme version 5.5 thus mariadb 5.5 offers mysql 5.5 features exists gap mysql versions 5.1 5.5 mariadb issued 5.2 5.3 point releases since specific new features developed mariadb developers decided major version number change necessary mariadb supported amazon rds service since october 2015 mariadb supported database microsoft azure mariadb api protocol compatible used mysql plus features support native non-blocking operations progress reporting means connectors libraries applications work mysql also work mariadb—whether support native features basis fedora developers replaced mysql mariadb fedora 19 concerns oracle making mysql closed software project openbsd likewise april 2013 dropped mysql mariadb 5.5 december 2012 michael widenius david axmark allan larsson announced formation foundation would oversee development mariadb april 2013 foundation announced appointed simon phipps secretary interim chief executive officer rasmus johansson chairman board andrew katz jeremy zawodny michael widenius board members noting wished create governance model similar used eclipse foundation board appointed eclipse foundation executive director mike milinkovich advisor lead transition skysql corporation ab company formed ex-mysql executives investors oracle bought mysql announced april 2013 merging company monty program ab joining mariadb foundation mariadb foundation appointed widenius cto simon phipps quit 2014 sale mariadb trademark skysql later said quit soon obvious company going allow independent foundation 1 october 2014 skysql corporation ab changed name mariadb corporation ab reflect role main driving force behind development mariadb server biggest support-provider mariadb registered trademark mariadb corporation ab used license mariadb foundation january 2015 september 2018 otto kekäläinen ceo mariadb foundation stepped effectively 1 october year arjen lentz appointed ceo foundation october 2018 resigned december 2018 kaj arnö joined ceo 1 february 2019 eric herman current chairman board mariadb used servicenow dbs bank google mozilla since 2013 wikimedia foundation several linux bsd distributions include mariadb like ubuntu 14.04 lts default mariadb arch linux manjaro debian debian 9 fedora fedora 19 red hat enterprise linux rhel 7 june 2014 centos centos 7 mageia mageia 2 opensuse opensuse 12.3 dartmouth suse linux enterprise server sles 12 openbsd 5.7 freebsd 2013 google tasked one engineers work mariadb foundation group investment companies led intel invested 20 million skysql european investment bank funded mariadb €25 million 2017
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Databases
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goldmont plus goldmont plus microarchitecture low-power atom celeron pentium silver branded processors used systems chip socs made intel gemini lake platform 14 nm goldmont plus core officially launched december 11 2017 goldmont plus enhanced 2nd generation out-of-order low-power atom microarchitecture designed entry level desktop notebook computers goldmont plus built 14 nm manufacturing process supports four cores consumer devices includes intel gen9 graphics architecture improvements introduced kaby lake microarchitecture goldmont plus microarchitecture builds success goldmont microarchitecture provides following enhancements list desktop processors follows list mobile processors follows
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Computer architecture
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galago software galago desktop presence information framework designed transmit presence information programs gives linux desktop ability combine numerous sources information people combine novel ways area rapid progress desktop computing simple example possibilities framework unified 'friends list could conceivably include twitter facebook nearby computers wired wireless network e-mail contacts voip contacts im contacts increasingly internet services sip voice ip allow optional publication presence means wide number channels communication person become possible galago allow choice available one place galago desktop-neutral contains set widgets gtk+ bindings several scripting languages test programs qt widgets planned
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Internet protocols
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intratext intratext digital library offers interface meeting formal requirements texts displayed hypertextual way based tablet pc interface linking words text provides concordances word lists statistics links cited works content available creative commons license also offers publishing services enable similar advantages intratext interface applies cognitive ergonomics model based lexical hypertext tablet pc touch screen interface uses set tools methods based hlt human language technologies intratext reading reference search tool used read work browse text hypertext search words phrases simple click pen mouse tablet pc interface allows browse search without keyboard using mouse computer pen touch screen tablet pc ease use accessibility intratext appreciated features intratext structured create make available high quality electronic editions particularly editorial philological linguistics aspects intratext editions published internet intranets distributed cd-rom several ways intratext allows reproduce faithfully scholarly editions complete footnotes even structured several apparatuses philological annotations references one different editions differences author lexicon lexicon authors several languages text finally intratext supports intra- extra-textual links citations extra-textual citations automatically linked cited work made available intratext edition intratext allows create text collections whole hypertext example collected works author corpora etc intratext collection creates browsing system preserves identity collected text author title structure criteria concordance reference unifies concordances intratext collection table contents two levels index works work toc system generates intratext checks text several issues according schema conceived improve content quality representation quality particular
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Computational linguistics
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edos edos operating system based upon ibm original mainframe dos confused unrelated better known dos ibm pc name stood extended enhanced disk operating system 1970 ibm announced ibm/370 product line along new peripherals software products operating systems including dos/vs supplanted dos although ibm rightly focused new products computing world dominated ibm/360 line left lot users nervous investment although couple projects emulating ibm/370 ibm/360 e.g. cfs inc. couple companies took different approach extending then-current limited dos computer software company tcsc took latter approach starting 1972 developed edos extended disk operating system extended number fixed program space partitions 3 6 added support new hardware included features ibm offered separately first version edos released 1972 response announcement ibm dos release 26 last dos release supported system 360 future dos releases would support system 370 machines also made available third party enhancements spooler docs cfs inc. tcsc enhanced edos become edos/vs announced 1977 delivered beta test sites 1978 may 1977 tcsc announced would release edos/vs response ibm release dos/vs release 34 advanced functions-dos/vs edos/vs based ibm dos/vs release 34 provided equivalent functionality ibm advanced functions-dos/vs product unlike ibm offerings edos/vs would run system 360 machines system 370 machines lacking virtual storage hardware non-vs machines whereas ibm offerings supported latest system 370 models vs hardware included tcsc identified parts ibm dos/vs release 34 operating system relied upon system/370-only machine instructions rewrote use instructions supported system/360 tcsc legally able reuse ibm dos/vs release 34 code since ibm intentionally published code without copyright notice made public domain us copyright law time 1981 ncsc announced plans release edos/vse 2.0 based ibm dos/vse release 35 suitable ibm 4300 machines tcsc founded jerry enfield tom steel responsible development marketing respectively company headquarters richmond virginia tcsc expanded canada australia europe 1980 company acquired nixdorf became ncsc products tcsc included extended console econ system enabled display system console using crt terminal ibm 3270 econ available ibm dos dos/vs tcsc edos edos/vs operating systems tcsc licensed datacom/db applied data research adr run edos edos/vs operating systems 1980 nixdorf bought tcsc nixdorf sought continue licensing arrangement adr ncsc went court dispute whether licensing arrangement terminated acquisition adr nixdorf settled court 1981 agreement nixdorf could continue resell adr products 1973 tcsc released remote job entry rje option edos 1975 tcsc released tape management system edos known tms 1983 ncsc announced unix compatibility subsystem ibm mainframes running ibm dos/vs e nixdorf edos/vs edos/vse operating systems known programmer work station/vse-advanced functions pws/vse-af short pws/vse-af based coherent unix clone developed mark williams company
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Operating systems
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mobile translation mobile translation refers electronic device software application provides audio translation includes handheld electronic device specifically designed audio translation also includes machine translation service software application hand-held devices including mobile telephones pocket pcs pdas mobile translation provides hand-held device users advantage instantaneous non-mediated translation one human language another usually service fee nevertheless significantly smaller human translator charges mobile translation part new range services offered mobile communication users including location positioning gps service e-wallet mobile banking business card/bar-code/text scanning etc relies computer programming sphere computational linguistics device communication means internet connection sms work translation system allowing japanese exchange conversations foreign nationals mobile phones first developed 1999 advanced telecommunications research institute international-interpreting telecommunications research laboratories based kansai science city japan words spoken mobile device translated target language sent voice user mobile phone machine translation software handheld devices featuring translation capabilities user-input text sms email commercially released 2004 transclick patent issued transclick sms email im translation 2006 november 2005 another japanese company nec corporation announced development translation system could loaded mobile phones mobile translation system could recognize 50,000 japanese words 30,000 english words could used simple translations travelling however january 2009 nec corporation officially demonstrated product technological advances within miniaturization computing communication devices made possible usage mobile telephones language learning among early projects spanish study programs included vocabulary practice quizzes word phrase translations soon projects developed using mobile phones teach english japanese university 2005 shifted focus providing vocabulary instruction sms similar program created learning italian australia vocabulary phrases quizzes short sentences sent via sms google translate one highly-utilized translation services see also infoscope handheld device composed digital camera wireless internet access developed ibm almaden research center ili handheld device provide instantaneous audio translation one language another provides translation english japanese chinese one2one prototype rely internet connectivity order function provide audio translation eight languages pixel buds device produced google provide real-time audio translation 40 languages order support machine translation service mobile device needs able communicate external computers servers receive user-input text/speech translate send back user usually done via internet connection wap gprs edge umts wi-fi earlier applications used sms communicate translation server mobile translation confused user-editable talking dictionaries phrase books already widespread available many hand-held devices normally require internet connectivity mobile device mobile translation may include number useful features auxiliary text translation forms basis service user input text using device keyboard also use pre-existing text form email sms messages received user device email/sms translation also possible send translated message optionally containing source text well translation mobile translation applications also offer additional services facilitate translated communication process may transformed human speech computer renders voice native speaker target language record speech send translation server convert text translating device camera printed text road sign restaurant menu page book etc application send translation server apply optical character recognition ocr technology extract text return user editing necessary translate chosen language combination get connected automatically live interpreter recently notable increase number language pairs offered automatic translation mobile devices japanese service providers traditionally offer cross-translation japanese chinese english korean others may offer translation 20 languages 200 language pairs including latin languages speech generation however limited smaller portion including english spanish italian french chinese etc image translation depends ocr languages available portable real-time automated translation one disposal number practical uses advantages advances mobile technology machine translation services helped reduce even eliminate disadvantages mobile translation reduced screen size mobile device one-finger keyboarding many new hand-held devices come equipped qwerty keyboard and/or touch-sensitive screen well handwriting recognition significantly increases typing speed 2006 new mobile phones devices began featuring large screens greater resolutions 640 x 480 px 854 x 480 px even 1024 x 480 px gives user enough visible space read/write large texts 2011 so-called hybrid translation technology introduced mylanguage mobile app vocre relies large part crowd-sourced language data however important challenge facing mobile translation industry linguistic communicative quality translations although providers claim achieved accuracy high 95 boasting proprietary technology capable “ understanding ” idioms slang language machine translation still distinctly lower quality human translation used care matters translated require correctness disadvantage needs mentioning requirement stable internet connection user mobile device since sms method communicating translation server proved less efficient sending packets data – message length limit 160 characters higher cost sms compared internet traffic charges – internet connectivity mobile devices must coverage non-urban areas still unstable
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Computational linguistics
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web sql database web sql database web page api storing data databases queried using variant sql api supported google chrome opera safari android browser w3c web applications working group ceased working specification november 2010 citing lack independent implementations i.e use database system sqlite backend reason specification could move forward become w3c recommendation mozilla corporation one major voices behind break-up negotiations deprecation standard time main proponents behind 'alternative storage standard indexeddb
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Databases
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progeny linux systems progeny linux systems company provided linux platform technology platform services technology supported debian rpm-based distributions linux platforms progeny linux systems based indianapolis ian murdock founder debian founder chairman board cto john h. hartman bruce byfield marketing communications director progeny created operating system called progeny componentized linux progeny eventually announced via post mailing lists 1 may 2007 ceasing operations progeny componentized linux usually called progeny debian defunct free operating system progeny announced post various mailing lists 1 may 2007 ceasing operations shut website progeny debian alternative debian 3.1 furthermore based upon linux standard base lsb 3.0 adopting technology anaconda installer ported red hat advanced packaging tool discover progeny debian aimed model developing component-based linux
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Operating systems
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tornado web server tornado scalable non-blocking web server web application framework written python developed use friendfeed company acquired facebook 2009 tornado open-sourced soon tornado noted high performance tries solve c10k problem affecting servers
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Web technology
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ping networking utility ping computer network administration software utility used test reachability host internet protocol ip network available virtually operating systems networking capability including embedded network administration software ping measures round-trip time messages sent originating host destination computer echoed back source name comes active sonar terminology sends pulse sound listens echo detect objects water ping operates sending internet control message protocol icmp echo request packets target host waiting icmp echo reply program reports errors packet loss statistical summary results typically including minimum maximum mean round-trip times standard deviation mean command-line options ping utility output vary numerous implementations options may include size payload count tests limits number network hops ttl probes traverse interval requests many systems provide companion utility ping6 testing internet protocol version 6 ipv6 networks implement icmpv6 ping utility written mike muuss december 1983 employment ballistic research laboratory us army research laboratory created tool troubleshoot problems ip network mike muuss inspired remark david mills using icmp echo packets ip network diagnosis measurements author named sound sonar makes since methodology analogous sonar echo location first released version public domain software subsequent versions licensed bsd license ping first included 4.3bsd freedos version developed erick engelke licensed gpl tim crawford developed reactos version licensed mit license rfc 1122 prescribes host must process icmp echo requests issue echo replies return following output running ping linux sending five probes target host www.example.com output lists probe message results obtained finally lists statistics entire test example shortest round trip time 9.674 ms average 10.968 ms maximum value 11.726 ms measurement standard deviation 0.748 ms cases response target host implementations display either nothing periodically print notifications timing possible ping results indicating problem include following case error target host intermediate router sends back icmp error message example host unreachable ttl exceeded transit addition messages include first eight bytes original message case header icmp echo request including quench value ping utility match responses originating queries generic composition icmp packet echo request ping icmp/icmp6 message identifier sequence number used client match reply request caused reply practice linux systems use unique identifier every ping process sequence number increasing number within process windows uses fixed identifier varies windows versions sequence number reset boot time echo reply icmp message generated response echo request mandatory hosts must include exact payload received request payload packet generally filled ascii characters output tcpdump utility shows last 32 bytes following example eight-byte icmp header starting payload may include timestamp indicating time transmission sequence number found example allows ping compute round trip time stateless manner without needing record time transmission packet payload may also include magic packet wake-on-lan protocol minimum payload case longer shown echo request typically receive reply host sleeping hibernation state host still wakes sleep state interface configured accept wakeup requests host already active configured allow replies incoming icmp echo request packets returned reply include payload may used detect remote host effectively woken repeating new request delay allow host resume network services host sleeping low power active state single request wakes host enough allow echo reply service reply instantly service enabled host need completely wake devices may return low power mode short delay configuration may used avoid host enter hibernation state much longer wake delay time passed low power active mode conduct denial-of-service attack attacker may send ping requests fast possible possibly overwhelming victim icmp echo requests technique called ping flood ping requests multiple addresses ping sweeps may used obtain list hosts network
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Computer security
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conway law conway law adage named computer programmer melvin conway introduced idea 1967 states law based reasoning order software module function multiple authors must communicate frequently therefore software interface structure system reflect social boundaries organization produced across communication difficult conway law intended valid sociological observation although sometimes used humorous context dubbed conway law participants 1968 national symposium modular programming eric s. raymond open-source advocate restated conway law new hacker dictionary reference work based jargon file organization software organization software team congruent said summarizing example conway paper raymond wrote four groups working compiler 'll get 4-pass compiler james o. coplien neil b. harrison stated one also see impact conway law design corporate websites nigel bevan usability expert stated 1998 organisations often produce web sites content structure mirrors internal concerns organisation rather needs users site similar effect may found websites undergo design committee evidence support conway law published team massachusetts institute technology mit harvard business school researchers using mirroring hypothesis equivalent term conway law found strong evidence support mirroring hypothesis significant differences product modularity consistent view distributed teams tend develop modular products additional likewise supportive case studies conway law conducted nagappan murphy basili university maryland collaboration microsoft syeed hammouda tampere university technology finland
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Computer architecture
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replay attack replay attack also known playback attack form network attack valid data transmission maliciously fraudulently repeated delayed carried either originator adversary intercepts data re-transmits possibly part masquerade attack ip packet substitution one lower tier versions man-in-the-middle attack another way describing attack attack security protocol using replay messages different context intended original expected context thereby fooling honest participant thinking successfully completed protocol run suppose alice wants prove identity bob bob requests password proof identity alice dutifully provides possibly transformation like hash function meanwhile eve eavesdropping conversation keeps password hash interchange eve posing alice connects bob asked proof identity eve sends alice password hash read last session bob accepts thus granting eve access replay attacks prevented tagging encrypted component session id component number using combination solutions use anything interdependent one another interdependency fewer vulnerabilities works unique random session id created run program thus previous run becomes difficult replicate case attacker would unable perform replay new run session id would changed session ids also known session tokens one mechanism used help avoid replay attacks way generating session id works follows session tokens chosen random process usually pseudorandom processes used otherwise eve may able pose bob presenting predicted future token convince alice use token transformation eve replay reply later time previously predicted token actually presented bob bob accept authentication one-time passwords similar session tokens password expires used short amount time used authenticate individual transactions addition sessions also used authentication process help establish trust two parties communicating bob also send nonces include message authentication code mac alice check timestamping another way preventing replay attack synchronization achieved using secure protocol example bob periodically broadcasts time clock together mac alice wants send bob message includes best estimate time clock message also authenticated bob accepts messages timestamp within reasonable tolerance advantages scheme bob need generate pseudo- random numbers alice n't need ask bob random number networks unidirectional near unidirectional advantage trade-off replay attacks performed quickly enough i.e within 'reasonable limit could succeed kerberos authentication protocol includes countermeasures classical case replay attack message captured adversary replayed later date order produce effect example banking scheme vulnerable attack message results transfer funds could replayed transfer funds originally intended however kerberos protocol implemented many versions ldap microsoft windows active directory includes use scheme involving time stamps severely limit effectiveness replay attacks messages past time live ttl considered old discarded improvements proposed including using triple password scheme three passwords used authentication server ticket granting server tgs servers use passwords encrypt messages secret keys different servers encryption provided three keys help aid preventing replay attacks wireless ad hoc networks also susceptible replay attacks case authentication system improved made stronger extending aodv protocol method improving security ad hoc networks increases security network small amount overhead extensive overhead network would run risk becoming slower performance would decrease keeping relatively low overhead network maintain better performance still improving security authentication sign-on clients using point-to-point protocol ppp susceptible reply attacks using password authentication protocol pap validate identity authenticating client sends username password clear authenticating server sends acknowledgement response intercepting client therefore free read transmitted data impersonate client server well able store client credentials later impersonation server challenge-handshake authentication protocol chap secures sort replay attack authentication phase instead using challenge message authenticator client responds hash-computed value based shared secret e.g client password authenticator compares calculation challenge shared secret authenticate client relying shared secret transmitted well features authenticator-controlled repetition challenges changing identifier challenge values chap provides limited protection replay attacks several real world examples replay attacks used issues detected fixed order prevent attacks many vehicles road use remote keyless system key fob convenience user modern systems hardened simple replay attacks vulnerable buffered replay attacks attack performed placing device receive transmit radio waves within range target vehicle transmitter attempt jam rf vehicle unlock signal sent placing buffer later use upon attempts unlock vehicle transmitter jam new signal cache play back old one creating rolling buffer one step ahead vehicle later time attacker may use buffered code unlock vehicle various devices use speaker recognition verify identity speaker text-dependent systems attacker record target individual ’ speech correctly verified system play recording verified system counter-measure devised using spectral bitmaps stored speech verified users replayed speech different pattern scenario rejected system
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Computer security
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philip s. abrams philip s. abrams computer science researcher co-authored first implementation programming language apl 1962 kenneth e. iverson published book programming language describing mathematical notation describing array operations mathematics 1965 abrams lawrence m. breed produced compiler translated expressions iverson apl notation ibm 7090 machine code 1970s vice president development scientific time sharing corporation stsc inc
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Programming language topics
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procera networks procera networks networking equipment company based fremont california united states designs sells network intelligence solutions based deep packet inspection dpi technology procera sells solutions telecom operators governments enterprises network equipment vendors areas analytics traffic management policy charging control service provider compliance procera incorporated 2002 california company initially created deliver intelligent ethernet network switches company changed product line merged netintact company based varberg sweden offered bandwidth management products scandinavian network operators packetlogic brand merger announced may closed june 2006 procera shifted company product strategy netintact product lines 2006 2008 procera sold inexpensive less 2 gbit/s traffic management products small operators enterprises operators like com hem sweden september 2007 procera networks became listed american stock exchange stock symbol pkt beginning 2008 procera began focusing larger carriers mobile operators several customers reported use procera technology yoigo genband resells procera products p-series products procera named one fastest growing network companies deloitte 2010 2011 part deloitte fast 500 study june 24 2011 procera networks joined russell 3000 index december 2011 procera moved nasdaq stock exchange using symbol pkt 2013 procera bought vineyard networks canadian dpi company c 28 million vineyard product sold market network application visibility library navl network equipment vendors 2015 procera acquired francisco partners private equity firm based san francisco procera operates private company longer listed nasdaq 2017 francisco partners acquired sandvine merged procera procera offers network intelligence solutions based version deep packet inspection dpi called datastream recognition definition language drdl drdl uses properties applications identification purposes allows operators manage subscriber traffic based application similar many dpi products procera offers 100 use cases analytics traffic management policy enforcement service provider compliance october 2016 alleged procera sold dpi software government turkey via telecoms company turk telecom order reveal usernames passwords people visiting unencrypted websites according forbes significant internal opposition technologists working procera sale current former employees said told forbes 'turk telekom requested feed subscribers ’ usernames passwords unencrypted websites also ip addresses sites ’ visited
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Computer security
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terminal mode terminal mode one set possible states terminal pseudo terminal character device unix-like systems determines characters written terminal interpreted cooked mode data preprocessed given program raw mode passes data as-is program without interpreting special characters system intercepts special characters cooked mode interprets special meaning backspace delete control-d typically used enable line-editing input running programs control characters control-c control-z used job control associated signals precise definition constitutes cooked mode operating system-specific example “ abc backspace ” given input program terminal character device cooked mode program gets “ abd ” terminal raw mode program gets characters “ abc ” followed backspace character followed “ ” cooked mode terminal line discipline processes characters “ abc backspace ” presents result “ abd ” program technically term “ cooked mode ” associated streams terminal line discipline generally applied system amount preprocessing cbreak mode sometimes called rare mode mode raw mode cooked mode unlike cooked mode works single characters time rather forcing wait whole line feeding line unlike raw mode keystrokes like abort usually control-c still processed terminal interrupt process
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Operating systems
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honor 8x honor 8x smartphone made huawei honor sub-brand successor huawei honor 8x within huawei honor series honor 8x 6.5-inch fhd+ display screen resolution 1,080 x 2,340 pixels 396 ppi pixel density 19.5:9 aspect ratio together deliver satisfying visual experience phone 20mp 2mp dual primary cameras pdaf dual flash click sharp life-like pictures pleasant colour reproductions front camera 16mp takes detailed selfies honor 8x carries rather average 64gb internal storage expanded 400gb device powered huawei hisilicon kirin 710 chipset two quad-core cortex a53 processors achieve 2.2ghz clock speed mali-t830 mp2 gpu 4gb ram phone delivers fluid performance apps games also rear-mounted fingerprint scanner improved security honor 8x uses a3,750mah li-polymer cell powers phone throughout day ease 4g volte compatible smartphone dual nano-sim slots second slot hybrid networks work without issue additional networking features include wifi bluetooth location support a-gps glonass assisted standard micro usb charging port 3.5 mm audio jack wired headphones.the phone comes 64 128 gigabytes storage 4 6 gb ram depending region display pixel resolution 1920x1080 pixel density 397 ppi honor 8x 16 mp front-facing camera dual rear camera setup consists 12 mp rgb lens 20-megapixel monochrome lens record video 1080p electronic image stabilization 1080p video honor 8x launched android oreo version 8.1 huawei emui 8.0. upgradable android 9.0 pie emui 9.0
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Operating systems
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cookiemonster attack cookiemonster attack man-in-the-middle exploit third party gain https cookie data encrypted sessions property properly set could allow access sites sensitive personal financial information python based tool developed security researcher mike perry perry originally announced vulnerability exploited cookiemonster bugtraq 2007 year later demonstrated cookiemonster proof concept tool defcon 16 users world wide web reduce exposure cookiemonster attacks avoiding websites unprotected attacks certain web browsers make possible user establish sites example users firefox browser go privacy tab preferences window click 'show cookies given site inspecting individual cookies top level name site subdomain names reveal 'send encrypted connections set user test site vulnerability cookiemonster attacks deleting cookies visiting site site still allows user site vulnerable cookiemonster attacks websites allegedly affected cookiemonster included
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Computer security
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powerpc powerpc backronym performance optimization enhanced risc – performance computing sometimes abbreviated ppc reduced instruction set computer risc instruction set architecture isa created 1991 apple–ibm–motorola alliance known aim powerpc evolving instruction set since 2006 named power isa old name lives trademark implementations power architecture-based processors powerpc cornerstone aim prep common hardware reference platform initiatives 1990s originally intended personal computers architecture well known used apple power macintosh powerbook imac ibook xserve lines 1994 2006 apple migrated intel x86 since become niche personal computers remains popular embedded high-performance processors use 7th generation video game consoles embedded applications provided array uses addition powerpc cpus still used amigaone third party amigaos 4 personal computers powerpc largely based ibm earlier power instruction set architecture retains high level compatibility architectures remained close enough programs operating systems run care taken preparation newer chips power series use power isa history risc began ibm 801 research project john cocke lead developer developed concepts risc 1975–78 801-based microprocessors used number ibm embedded products eventually becoming 16-register ibm romp processor used ibm rt pc rt pc rapid design implementing risc architecture years 1982–1984 ibm started project build fastest microprocessor market new 32-bit architecture became referred america project throughout development cycle lasted approximately 5–6 years result power instruction set architecture introduced risc system/6000 early 1990 original power microprocessor one first superscalar risc implementations high performance multi-chip design ibm soon realized single-chip microprocessor needed order scale rs/6000 line lower-end high-end machines work began one-chip power microprocessor designated rsc risc single chip early 1991 ibm realized design could potentially become high-volume microprocessor used across industry apple already realized limitations risks dependency upon single cpu vendor time motorola falling behind delivering 68040 cpu furthermore apple conducted research made experimental quad-core cpu design called aquarius convinced company technology leadership future computing risc methodology ibm approached apple goal collaborating development family single-chip microprocessors based power architecture soon apple one motorola largest customers desktop-class microprocessors asked motorola join discussions due long relationship motorola extensive experience manufacturing high-volume microprocessors ibm form second source microprocessors three-way collaboration apple ibm motorola became known aim alliance 1991 powerpc one facet larger alliance among three companies time personal computer industry shipping systems based intel 80386 80486 chips complex instruction set computer cisc architecture development pentium processor well underway powerpc chip one several joint ventures involving three alliance members efforts counter growing microsoft-intel dominance personal computing motorola power looked like unbelievable deal allowed company sell widely tested powerful risc cpu little design cash part also maintained ties important customer apple seemed offer possibility adding ibm might buy smaller versions motorola instead making point motorola already risc design form 88000 poorly market motorola well 68000 family majority funding focused 88000 effort somewhat starved resources 88000 already production however data general shipping 88000 machines apple already 88000 prototype machines running 88000 also achieved number embedded design wins telecom applications new power one-chip version could made bus-compatible hardware level 88000 would allow apple motorola bring machines market far faster since would redesign board architecture result various requirements powerpc performance computing specification differences earlier power instruction set powerpc outlined appendix e manual powerpc isa v.2.02 since 1991 ibm long-standing desire unifying operating system would simultaneously host existing operating systems personalities upon one microkernel 1991 1995 company designed aggressively evangelized would become workplace os primarily targeting powerpc first powerpc products reached market met enthusiasm addition apple ibm motorola computer group offered systems built around processors microsoft released windows nt 3.51 architecture used motorola powerpc servers sun microsystems offered version solaris os ibm ported aix unix workplace os featured new port os/2 intel emulation application compatibility pending successful launch powerpc 620 throughout mid-1990s powerpc processors achieved benchmark test scores matched exceeded fastest x86 cpus ultimately demand new architecture desktop never truly materialized windows os/2 sun customers faced lack application software powerpc almost universally ignored chip ibm workplace os platform thus os/2 powerpc summarily canceled upon first developers release december 1995 due simultaneous buggy launch powerpc 620 powerpc versions solaris windows discontinued brief period market macintosh due apple persistence powerpc gain traction apple performance powerpc bright spot face increased competition windows 95 windows nt-based pcs cancellation workplace os general powerpc platform especially aim common hardware reference platform instead seen hardware-only compromise run many operating systems one time upon single unifying vendor-neutral hardware platform parallel alliance ibm motorola companies development efforts underway internally powerquicc line result work inside motorola 4xx series embedded processors underway inside ibm ibm embedded processor business grew nearly us 100 million revenue attracted hundreds customers toward close decade manufacturing issues began plaguing aim alliance much way motorola consistently pushed back deployments new processors apple vendors first motorola 1990s powerpc 7xx 74xx processors ibm 64-bit powerpc 970 processor 2003 2004 motorola exited chip manufacturing business spinning semiconductor business independent company called freescale semiconductor around time ibm exited 32-bit embedded processor market selling line powerpc products applied micro circuits corporation amcc focusing 64-bit chip designs maintaining commitment powerpc cpus toward game console makers nintendo gamecube wii sony playstation 3 microsoft xbox 360 latter two use 64-bit processors 2005 apple announced would longer use powerpc processors apple macintosh computers favoring intel-produced processors instead citing performance limitations chip future personal computer hardware specifically related heat generation energy usage well inability ibm move 970 processor 3 ghz range ibm-freescale alliance replaced open standards body called power.org power.org operates governance ieee ibm continuing use evolve powerpc processor game consoles freescale semiconductor focusing solely embedded devices ibm continues develop powerpc microprocessor cores use application-specific integrated circuit asic offerings many high volume applications embed powerpc cores powerpc specification handled power.org ibm freescale amcc members powerpc cell power processors jointly marketed power architecture power.org released unified isa combining power powerpc isas new power isa v.2.03 specification new reference platform servers called papr power architecture platform reference ibm power microprocessors implement power isa used ibm ibm power systems running ibm aix linux many powerpc designs named labeled apparent technology generation began g3 internal project name inside aim development would become powerpc 750 family apple popularized term g3 introduced power mac g3 powerbook g3 event 10 november 1997 motorola apple liked moniker used term g4 7400 family introduced 1998 power mac g4 1999 time g4 launched motorola categorized powerpc models former current future according generation adhered even renaming older 603e core g2 motorola g5 project never came fruition name stuck apple reused 970 family launched 2003 even designed built ibm powerpc designed along risc principles allows superscalar implementation versions design exist 32-bit 64-bit implementations starting basic power specification powerpc added instructions present power instruction set deemed complex removed powerpc architecture removed instructions could emulated operating system necessary removed instructions powerpc chips switch endianness via bit msr machine state register second bit provided allow os run different endianness accesses inverted page table hash table functions tlb off-chip storage always done big-endian mode processor starts big-endian mode little-endian mode three lowest-order bits effective address exclusive-ored three bit value selected length operand enough appear fully little-endian normal software operating system see warped view world accesses external chips video network hardware fixing warped view requires motherboard perform unconditional 64-bit byte swap data entering leaving processor endianness thus becomes property motherboard os operates little-endian mode big-endian motherboard must swap bytes undo exclusive-or accessing little-endian chips altivec operations despite 128-bit treated 64-bit allows compatibility little-endian motherboards designed prior altivec interesting side effect implementation program store 64-bit value longest operand format memory one endian mode switch modes read back 64-bit value without seeing change byte order case motherboard switched time mercury systems matrox ran powerpc little-endian mode done powerpc devices serving co-processors pci boards could share data structures host computers based x86 pci x86 little-endian os/2 windows nt powerpc ran processor little-endian mode solaris aix linux ran big endian ibm embedded powerpc chips use per-page endianness bit none previous applies first implementation architecture powerpc 601 released 1992 based rsc implementing hybrid power1 powerpc instructions allowed chip used ibm existing power1-based platforms although also meant slight pain switching 2nd generation pure powerpc designs apple continued work new line macintosh computers based chip eventually released 601-based power macintosh march 14 1994 ibm also full line powerpc based desktops built ready ship unfortunately operating system ibm intended run desktops—microsoft windows nt—was complete early 1993 machines ready marketing accordingly ibm developed animosity toward microsoft ibm decided port os/2 powerpc form workplace os new software platform spent three years 1992 1995 development canceled december 1995 developer release disappointing launch powerpc 620 reason ibm powerpc desktops ship although reference design codenamed sandalbow based powerpc 601 cpu released rs/6000 model byte april 1994 issue included extensive article apple ibm powerpc desktops apple also lacked powerpc based os took different route utilizing portability platform yielded secret star trek project company ported essential pieces mac os operating system powerpc architecture wrote 68k emulator could run 68k based applications parts os rewritten second generation pure includes low end powerpc 603 high end powerpc 604 603 notable due low cost power consumption deliberate design goal motorola part used 603 project build basic core future generations ppc chips apple tried use 603 new laptop design unable due small 8 kib level 1 cache 68000 emulator mac os could fit 8 kib thus slowed computer drastically 603e solved problem 16 kib l1 cache allowed emulator run efficiently 1993 developers ibm essex junction burlington vermont facility started work version powerpc would support intel x86 instruction set directly cpu one several concurrent power architecture projects ibm working chip began known inside ibm media powerpc 615 profitability concerns rumors performance issues switching x86 native powerpc instruction sets resulted project canceled 1995 limited number chips produced in-house testing aside rumors switching process took 5 cycles amount time needed processor empty instruction pipeline microsoft also aided processor demise refusing support powerpc mode first 64-bit implementation powerpc 620 appears seen little use apple n't want buy large die area costly embedded market later slower promised ibm used power3 design instead offering 64-bit small version late-2002 introduction powerpc 970 970 64-bit processor derived power4 server processor create power4 core modified backward-compatible 32-bit powerpc processors vector unit similar altivec extensions motorola 74xx series added ibm rs64 processors family chips implementing amazon variant powerpc architecture processors used rs/6000 as/400 computer families amazon architecture includes proprietary extensions used as/400 power4 later power processors implement amazon architecture replaced rs64 chips rs/6000 as/400 families ibm developed separate product line called 4xx line focused embedded market designs included 401 403 405 440 460 2004 ibm sold 4xx product line applied micro circuits corporation amcc amcc continues develop new high performance products partly based ibm technology along technology developed within amcc products focus variety applications including networking wireless storage printing/imaging industrial automation numerically powerpc mostly found controllers cars automotive market freescale semiconductor initially offered many variations called mpc5xx family mpc555 built variation 601 core called 8xx designed israel msil motorola silicon israel limited 601 core single issue meaning issue one instruction clock cycle add various bits custom hardware allow i/o one chip 2004 next-generation four-digit 55xx devices launched automotive market use newer e200 series powerpc cores networking another area embedded powerpc processors found large numbers msil took quicc engine mc68302 made powerquicc mpc860 famous processor used many cisco edge routers late 1990s variants powerquicc include mpc850 mpc823/mpc823e variants include separate risc microengine called cpm offloads communications processing tasks central processor functions dma follow-on chip family mpc8260 603e-based core different cpm honda also uses powerpc processors asimo 2003 bae systems platform solutions delivered vehicle-management computer f-35 fighter jet platform consists dual powerpcs made freescale triple redundant setup operating systems work powerpc architecture generally divided oriented toward general-purpose powerpc systems oriented toward embedded powerpc systems companies licensed 64-bit power 32-bit powerpc ibm include powerpc processors used number now-discontinued video game consoles power architecture currently used following desktop computers power architecture currently used following embedded applications
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Computer architecture
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menlo typeface menlo monospaced sans-serif typeface designed jim lyles face first shipped mac os x snow leopard menlo based upon open source font bitstream vera public domain font deja vu menlo replaced system monospaced font mac os 10.11 new apple-made monospaced font called sf mono monospaced variant san francisco family fonts apple created part corporate identity installed user-accessible typeface default although included used xcode even installed user sf mono license agreement extraordinarily restrictive limits use font solely conjunction apple-branded applications allowed embedded anywhere use typeface requires written consent apple mac os 10.12.4 user still install use sf mono unless copied resources folder apple however begun use apple developer website version used slightly newer one ships mac os
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Operating systems
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drmaa drmaa distributed resource management application api high-level open grid forum api specification submission control jobs distributed resource management drm system cluster grid computing infrastructure scope api covers high level functionality required applications submit control monitor jobs execution resources drm system 2007 drmaa one first two one gridrpc specifications reached full recommendation status open grid forum 2012 second version drmaa standard drmaa2 published abstract interface definition language idl defining semantic functions gfd 194 drmaa2 specifies twice many calls drmaa covers cluster monitoring notion queues machines introduces multi job-session concept single applications better job workflow management later 2012 c api specified first language binding gf 198 development api done global grid forum model ietf standard development originally co-authored specification first proposed global grid forum 3 ggf3 frascati italy gained momentum global grid forum 4 toronto ontario development specification first proposed objective facilitate direct interfacing applications existing drm systems application builders portal builders independent software vendors isvs api co-authored participants wide-selection companies included participants industries education development resulted open standard received relatively good reception wide audience quickly without drmaa standard model existed submit jobs component regions grid assuming region running local drmss first version drmaa api implemented sun grid engine also university wisconsin–madison program condor furthermore c java idl binding documents made available language bindings generated easily swig first used perl binding number software solutions use drmaa interface different resource management systems
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Distributed computing architecture
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webroot internet security complete webroot internet security complete computer security software program microsoft windows users combine saas cloud protection traditional antivirus antispyware desktop technologies built suite two-way firewall 10gb online backup file sharing capabilities registry cleaner email antispam secure browsing anti-phishing password management service suite initially released july 26 2010 2011 version product product received many positive comments reviewers intuitive easy-to-use interface initial reviews product praised program solid core feature set including real-time protection shields firewall automatically filters network traffic according pre-selected profiles browsing protection provides ratings links search results reviews also praise extensive features set identity privacy protection updated easy-to-use user interface additional reviews commended ‘ sync share ’ features namely file synchronization sharing abilities well added benefit integrated password management tools product said reviewers “ noisy firewall ” regular pop-ups requiring user ’ action criticisms also include comments limited capacity antispam component compatibility microsoft outlook outlook express limits number consumers utilize feature program heavily criticized including parental controls feature set commonly included security suites type competitors webroot internet security complete comes feature set webroot internet security essentials additional personal privacy protection features including password management tool 8gb additional online storage space credit card monitoring/ identity theft prevention service us based customers password management tool licensed lastpass designed store login information usernames passwords well personal information used common forms name birth date user name address email address phone number credit card details bank account information secure encrypted online portal master password used gain access stored information access gained using webroot toolbar visiting saved site logging webroot account user ’ using another password-management application import data application webroot software using either webroot portal webroot toolbar additional identity features us customers include identity theft protection monitoring services trustedid comes fraud alerts free annual credit reports also 1,000,000 service warranty covers lost wages out-of-pocket expenses legal defense fees occur result identity theft pc magazine tests product ’ malware detection rates found blocked 90 undeniable spam blocked .8 legitimate emails suite overall malware detection rate 83 giving total score 7.0 10 detected 100 rootkits 93 keyloggers 89 scareware suite overall malware blocking rate 91 overall score 9.0 10 detected 100 commercial keyloggers rootkits 89 blocking rate scareware secure browsing feature software blocked total 84 harmful urls webroot mistakenly flagged core windows system files malicious even started temporarily removing legit files trashing user computers around world software installed tests pc mag found 18 increase total system boot time 19 increase load time web pages antispam component turned load time email retrieval slowed 2.7 times br copying moving large collection files disks webroot added 1 total task time task zipping unzipping large group files took 24 longer webroot installed without installing uninstalling number large windows installer packages increased task time adding 35 webroot software installed another review system impact measured based two components using pcmark first overall system performance measured reported ad less 3 overall impact performance well time took perform full system scan reported taking one hour scan hard drive containing 140gb data software received international computer security association certification desktop/server anti-virus detection anti-virus cleaning windows 32 64 bit webroot internet security complete received virus bulletin december 2010 antivirus certification windows 7 uk review site awarded product “ reviews recommended ” award reviewing product feature set price received 2011 bronze award software review site toptenreviews computeractive gave “ buy ” rating 5 5 star review
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Computer security
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burton smith burton j. smith march 21 1941 – april 2 2018 american computer architect technical fellow microsoft smith graduated cate school carpinteria california 1958 established gifted math science student taking special interest chemistry placed third statewide competition senior smith went pomona college claremont california study physics transferred pomona university new mexico following freshman year still unhappy education subsequently dropped college entirely join navy smith spent four years military returning university new mexico changing studies physics electrical engineering graduating summa cum laude b.s.e.e degree 1967 smith turned acceptances berkeley stanford attend massachusetts institute technology pursue doctorate citing financial aid package reasoning behind decision part aid package work-study asking smith help build database university computer science department one smith first formative experiences computers earned sc.d mit 1972 1970 1979 taught massachusetts institute technology university colorado smith spent six years denelcor inc. colorado serving vice president research development primary architect denelcor heterogeneous element processor hep 1985 1988 smith fellow institute defense analyses supercomputing research center smith co-founded tera computer company 1988 2005 served chief scientist member board directors also company chairman 1988 1999 2000 tera acquired cray research business unit silicon graphics renamed cray inc.. december 2005 smith hired microsoft technical fellow working various groups within company define expand efforts areas parallel high-performance computing smith received 1991 eckert-mauchly award institute electrical electronics engineers ieee association computing machinery 2003 received seymour cray computer science engineering award ieee computer society elected national academy engineering received ieee computer society charles babbage award elected fellow american academy arts sciences 2010 smith died april 2 2018 regional hospital highline medical center burien washington survived two daughters julia katherine ray granddaughter erin brother david burton ’ wife dorothy preceded death dennis shasha minds springer new york 1998. interview burton smith
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Computer architecture
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probabilistic latent semantic analysis probabilistic latent semantic analysis plsa also known probabilistic latent semantic indexing plsi especially information retrieval circles statistical technique analysis two-mode co-occurrence data effect one derive low-dimensional representation observed variables terms affinity certain hidden variables latent semantic analysis plsa evolved compared standard latent semantic analysis stems linear algebra downsizes occurrence tables usually via singular value decomposition probabilistic latent semantic analysis based mixture decomposition derived latent class model considering observations form co-occurrences formula_1 words documents plsa models probability co-occurrence mixture conditionally independent multinomial distributions c words topic note number topics hyperparameter must chosen advance estimated data first formulation symmetric formulation formula_3 formula_4 generated latent class formula_5 similar ways using conditional probabilities formula_6 formula_7 whereas second formulation asymmetric formulation document formula_4 latent class chosen conditionally document according formula_9 word generated class according formula_7 although used words documents example co-occurrence couple discrete variables may modelled exactly way number parameters equal formula_11 number parameters grows linearly number documents addition although plsa generative model documents collection estimated generative model new documents parameters learned using em algorithm plsa may used discriminative setting via fisher kernels plsa applications information retrieval filtering natural language processing machine learning text related areas reported aspect model used probabilistic latent semantic analysis severe overfitting problems example latent class model see references therein related non-negative matrix factorization present terminology coined 1999 thomas hofmann
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Computational linguistics
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mimblewimble mimblewimble blockchain protocol created improve privacy fungibility scalability blockchains published july 19 2016 pseudonym tom elvis jedusor french name voldemort harry potter mimblewimble protocol cleverly uses blinding factors balancing inputs outputs commitment scheme private keys sender receiver must interact construct joint signature authorize transfer funds blocks mimblewimble constituent transactions aggregated one giant transaction erasing original transaction boundaries initial block download benefits cut-through spent outputs cancel corresponding inputs erasing blockchain history provable security analysis mimblewimble provided georg fuchsbauer et al protocol powers several decentralized privacy-oriented cryptocurrencies
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Internet protocols
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hardcard hardcard genericized trademark hard disk drive disk controller host adapter expansion card personal computer typically hard disk drive hdd installs drive bay cables connect drive host adapter power source personal computer lacks available bus compatible host adapter one may install adapter expansion slot hardcard supplies host adapter n't require empty drive bay plus development subsidiary quantum corporation developed first isa hardcard released october 1985 june 1986 28 plus development competitors producing similar products term used generically refer hard disk card quantum corporation formed plus development subsidiary 1983 plus development invested efforts developing hard disk drive average computer owner could install easily without much technical knowledge 1985 plus development engineered first hardcard 10 megabyte mb capacity suggested retail price 1,095 mid-1980s hard drives small 1.6 inches tall order fit single isa pc card expansion slot custom one-inch thick hard drive designed spent 15 million project plus development started shipping hardcard october 1985 trademarked hardcard brand 1988 hardcard provided computer industry first one-inch-thick hdd interface form factor compatible full length card slot isa bus first introduced ibm pc thicker head disk assembly subsequently introduced 1-inch high standard form factor 3½-inch hdds sources inside company launch hardcard claim first hdd controller integrated drive printed circuit board xebec hdd controller manufacturer early 1980s already done owl product around august 1984 complete 5.25 inch half-height hdd integrated controller drive electronics printed circuit board sasi interface introduction hardcard plus development continued working higher capacity hard drives form factor first hardcard brand name became widely known name continued follow products hardcard ii hardcard ii xl advertised effective access times result disk cache hardcard ii listed times hardcard ii xl listed effective access time hardcard ez line returned listing access times without benefit cache hardcard products including hardcard ii xl produced plus development name hardcard ez released quantum name quantum absorbed wholly owned subsidiary plus development within one year plus development introduction hardcard 28 companies released similar products time products using standard hard drive 1.6-inch height forcing card hang adjacent pc slot hard drive located opposite side away connector sometimes enabling short half-length expansion card installed adjacent slot hard drive cards usually described occupying 1.5 expansion slots companies product names similar product plus hardcard 1985 tandy introduced tandy 1000 tandy offered proprietary 20 megabyte hard card 799 8-bit isa slot required accommodate hard card preserving drive bays disk drives cd-roms 8-bit slots electronically compatible computer could hold card 10 1/2 inches long result many hard cards offered plus development 13 inches long hence compatible hard cards certified tandy compatible meaning fit tandy 1000 model sx tx sl tl series possible use plus development hard card tandy 1000 completely removing plastic case cutting metal frame allow fit hard card must 10 inches long use 8-bit isa interface work tandy 1000 computer usually card must installed slot 1 due overhang tandy 1000 60 watt power supply n't sufficient run hard cards power-efficient card preferable
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Computer architecture
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point coordination function point coordination function pcf media access control mac technique used ieee 802.11 based wlans including wi-fi resides point coordinator also known access point ap coordinate communication within network ap waits pifs duration rather difs duration grasp channel pifs less difs duration hence point coordinator always priority access channel pcf located directly distributed coordination function dcf ieee 802.11 mac architecture channel access pcf mode centralized hence point coordinator sends cf-poll frame pcf capable station permit transmit frame case polled station frames send must transmit null frame due priority pcf dcf stations use dcf might gain access medium prevent repetition interval designed cover contention free pcf contention based dcf traffic repetition interval repeated continuously starts special control frame called beacon frame stations hear beacon frame start network allocation vector duration contention free period repetition period since aps logical bus topologies shared circuits one message processed one time contention based system thus media access control technique required wireless networks may suffer hidden node problem regular nodes communicate ap see nodes extreme edge geographical radius network wireless signal attenuates reach far thus ap middle allows distance halved allowing nodes see ap consequentially halving maximum distance two nodes extreme edges circle-star topology pcf seems implemented hardware devices part wi-fi alliance interoperability standard pcf interframe space pifs one interframe space used ieee 802.11 based wireless lans pcf enabled access point wait pifs duration rather difs occupy wireless medium pifs duration less difs greater sifs difs pifs sifs hence ap always priority access medium pifs duration calculated follows pifs sifs slot time
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Internet protocols
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legend kage player armed kodachi shortsword unlimited number shuriken main gameplay revolves around killing enemy ninja blue red enemy fire-breathing monks five stages home versions grabbing crystal ball causes player clothes change next level color thereby attain certain powers bigger shuriken faster speed kage hit home version green orange clothes die reverts normal red clothes player takes role young iga ninja named kage shadow mission rescue princess kiri hime shogun daughter villainous warlord yoshi ro kuyigusa fellow evil samurai yuki nosuke riko kage must fight way forest along secret passageway fortress wall castle ... rescuing twice three times fc/nes version order win game time princess rescued seasons change summer fall winter back summer famicom/nes version re-released wii virtual console japan december 19 2006 united states february 19 2007 also released 3ds virtual console wii u virtual console japan arcade version also appears compilation title taito legends 2 revised legend kage included taito nostalgia 1 release along original game features two new playable characters ayame ganin ayame ninja throw bombs similar red ninja game unlimited supply throwing knives ganin dog breathe fire similar monks game perform spin attack much range leaves invulnerable instant kills enemy touches also new final boss characters face giant green cobra slithers ground back forth screen end second run levels enemy jump air 3d graphics remake arcade game along original arcade version included 2006 compilation taito legends power playstation portable game still side-scrolling follow-up game developed lancarse nintendo ds published taito 2008 taito parent company square enix published north american localization game later year
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Computer architecture
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symon bootmanager symon bootmanager light-weighted partitions bootmanager developed wholly assembler code thus needs little space installation software makes possible create 36 partitions one single hard drive 20 operating systems organized partitions despite small size bootmanager pseudo graphical interface equipped many powerful features features make unique among bootmanagers utility developed vladimir dashevsky free current version r3.23.02
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Computer file systems
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r4600 r4600 code-named orion microprocessor developed quantum effect design qed implemented mips iii instruction set architecture isa qed design firm fabricate sell designs r4600 first licensed integrated device technology idt later toshiba nkk companies fabricated microprocessor marketed r4600 designed low-end workstation high-end embedded microprocessor users included silicon graphics inc. sgi indy workstation deskstation technology windows nt workstations r4600 instrumental making indy successful providing good integer performance competitive price embedded systems prominent users included cisco systems network routers canon printers idt first company fabricate ship r4600 idt produced first silicon august 1993 first part 100 mhz part announced october 1993 march 1994 cebit idt announced 133 mhz part fabricated 0.65 μm cmos process required 5 v power supply nkk announced version r4600 nr4600 middle 1994 first nr4600 100 mhz part fabricated 0.5 μm process used 3.3 v power supply r4600 simple design scalar processor issuing one instruction per cycle integer pipeline floating-point unit fpu integer instructions single cycle latency throughput except multiplies divides multiplies 32-bit 64-bit eight-cycle latency six-cycle throughput divides 32-cycle latency throughput 32-bit integers 61-cycle latency throughput 64-bit integers fpu pipelined save die area thus cost characteristic severely restricted r4600 floating-point performance impede success low-end computers embedded applications integer performance important single double precision adds four-cycle latency throughput single double precision multiplies partially pipelined eight-cycle latency six-cycle throughput single precision divides 32-cycle latency throughput whereas double precision division 61-cycle latency throughput square roots latency throughput one cycle less comparative divide instructions r4600 uses floating-point unit perform floating-point multiply divide also integer multiply divide r4600 16 kb two-way set-associative caches instructions data supported l2 cache on-die hardware control requiring external logic whether custom application specific integrated circuit asic chipset cache cache resided sysad bus shared external interface sysad bus 64 bits wide operate clock rates 50 mhz peak bandwidth 400 mb/s r4600 external interface support multiprocessing r4600 needs supplied three clock signals generate various clocks r4650 derivative r4600 announced 19 october 1994 custom instructions improving performance fixed-point digital signal processing dsp applications lower cost version r4650 r4640 announced 27 november 1995 32-bit instead 64-bit external interface 16 september 1997 150 180 mhz versions microprocessors introduced quantities 10,000 150 180 mhz r4640s priced 30 39 respectively 150 180 mhz r4650s priced 60 74 respectively r4650 also available 133 167 mhz speeds used arcade games produced namco example time crisis 2 running namco system 23 hardware r4640 used webtv networks webtv plus thin client r4700 also code-named orion derivative r4600 ported 0.5 µm cmos process r4700 available 100 133 150 175 200 mhz versions
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Computer architecture
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binary recompiler binary recompiler compiler takes executable binary files input analyzes structure applies transformations optimizations outputs new optimized executable binaries binary recompilation introduced gary kildall 1980s
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Programming language topics
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pts-dos pts-dos aka pts/dos disk operating system dos clone developed russia phystechsoft paragon technology systems phystechsoft formed 1991 moscow russia graduates members mipt informally known phystech end 1993 phystechsoft released first commercially available pts-dos pts-dos v6.4 version numbering followed ms-dos version numbers microsoft released ms-dos 6.2 november 1993 1995 programmers left phystechsoft founded paragon technology systems took source code released version named pts/dos 6.51cd well s/dos 1.0 source dos stripped open-source version according official phystechsoft announcements programmers violated copyright laws russian military laws pts-dos developed close relationship russia military thus may subject military secrets law phystechsoft continued development released pts-dos v6.6 somewhere presented pts-dos v6.65 cebit exhibition 1997 next version phystechsoft formally pts/dos extended version 6.70 labeled pts-dos 2000 still distributed last 16-bit pts-dos system paragon continued pts-dos line released paragon dos pro 2000 also known labeled places pts/dos pro 2000 according paragon last version development since ceased moreover release contained bundled source code older pts-dos v6.51 later phystechsoft continued developing pts-dos finally released pts-dos 32 formally known pts-dos v7.0 added support fat32 file system pts-dos certified russian ministry defense following list commands supported pts-dos 2000 pro
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Operating systems
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continua health alliance continua health alliance international non-profit open industry group nearly 240 healthcare providers communications medical fitness device companies continua health alliance members aim develop system deliver personal individual healthcare continua founding member personal connected health alliance launched february 2014 founding members mhealth summit himss continua health alliance international not-for-profit industry organization enabling end-to-end plug-and-play connectivity devices services personal health management healthcare delivery mission empower information-driven health management facilitate incorporation health wellness day-to-day lives consumers continua pioneer establishing industry standards security connected health technologies smart phones gateways remote monitoring devices activities include certification brand support program events collaborations support technology clinical innovation well outreach employers payers governments care providers nearly 220 member companies reaching across globe continua comprises technology medical device healthcare industry leaders service providers dedicated making personal connected health reality continua health alliance working toward establishing systems interoperable telehealth devices services three major categories chronic disease management aging independently health physical fitness continua health alliance version 1 design guidelines based proven connectivity technical standards include bluetooth wireless usb wired device connection group released guidelines public june 2009 group establishing product certification program using recognizable logo continua certified logo program signifying product interoperable continua-certified products products made continua health alliance guidelines provide consumers increased assurance interoperability devices enabling easily share information caregivers service providers collaborations government agencies regulatory bodies continua works provide guidelines effective management diverse products services global network vendors continua health alliance products make use iso/ieee 11073 personal health data phd standards continua design guidelines available public without signing non-disclosure agreement continua guidelines help technology developers build end-to-end plug-and-play systems efficiently cost effectively continua health alliance founded june 6 2006 continua health alliance performed first public demonstration interoperability october 27 2008 partners center connected health 5th annual connected health symposium boston continua health alliance certified first product nonin 2500 palmsat handheld pulse oximeter usb january 26 2009 end december 2014 100 certified products continua selected bluetooth low energy zigbee wireless protocols wireless standards version 2 design guidelines released bluetooth low energy used low-power mobile devices zigbee used networked low-power sensors enabling independent living beginning 2012 continua invites non-members request copy design guidelines signing non-disclosure agreement continua working groups operations u.s. eu japan india china continua health alliance currently nearly 220 member companies continua board directors currently composed following companies organisation primarily staffed volunteers member organisations organised working groups address goals alliance board directors sit following main working groups continua alliance website contains full listing member organisations directory qualified products clear statement mission
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Computer architecture
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illegal opcode illegal opcode also called undocumented instruction instruction cpu mentioned official documentation released cpu designer manufacturer nevertheless effect illegal opcodes common older cpus designed 1970s mos technology 6502 intel 8086 zilog z80 older processors many exist side effect wiring transistors cpu usually combine functions cpu intended combined old modern processors also instructions intentionally included processor manufacturer documented official specification accidental illegal instructions useless even highly undesirable effects crashing computer might accident something useful certain situations instructions sometimes exploited computer games 1970s 1980s speed certain time-critical sections another common use ongoing battle copy protection implementations cracking form security obscurity secrecy usually last long danger associated use illegal instructions given fact manufacturer guarantee existence function might disappear behave differently change cpu internals new revision cpu rendering programs use incompatible newer revisions example number older apple ii games work correctly newer apple iic latter uses newer cpu revision 65c02 away illegal opcodes recent cpus 80186 80286 68000 descendants powerpc processor illegal opcodes widely known/used manufacturers guarantee cpu behave well-defined way finds unknown opcode instruction stream usually means triggering certain exception fault condition operating system exception fault handler usually terminate application caused fault another less common way handling illegal instructions defining nothing except taking time space equivalent cpu official nop instruction method used tms9900 65c02 processor among others spite manufacturer guarantee instructions research uncovered vast number undocumented instructions modern x86 processors instructions shared across processor manufacturers indicating intel amd aware instruction purpose despite appearing official specification instructions specific manufacturers specific product lines purpose majority x86 undocumented instructions unknown today details instructions mainly interest exact emulation older systems
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Computer architecture
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indirect branch indirect branch also known computed jump indirect jump register-indirect jump type program control instruction present machine language instruction sets rather specifying address next instruction execute direct branch argument specifies address located example 'jump indirect r1 register means next instruction executed address register r1 address jumped known instruction executed indirect branches also depend value memory location indirect branch useful make conditional branch especially multiway branch instance based program input value could looked jump table pointers code handling various cases implied data value data value could added address table result stored register indirect jump could made based value register efficiently dispatching program control code appropriate input similar manner subroutine call instructions indirect address subroutine called specified memory function pointers typically implemented indirect subroutine calls gcc-8.1 appear following new options codice_1
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Computer architecture
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semantic interoperability semantic interoperability ability computer systems exchange data unambiguous shared meaning semantic interoperability requirement enable machine computable logic inferencing knowledge discovery data federation information systems semantic interoperability therefore concerned packaging data syntax simultaneous transmission meaning data semantics accomplished adding data data metadata linking data element controlled shared vocabulary meaning data transmitted data one self-describing information package independent information system shared vocabulary associated links ontology provides foundation capability machine interpretation inference logic syntactic interoperability prerequisite semantic interoperability syntactic interoperability refers packaging transmission mechanisms data healthcare hl7 use thirty years predates internet web technology uses pipe character data delimiter current internet standard document markup xml uses data delimiter data delimiters convey meaning data structure data without data dictionary translate contents delimiters data remains meaningless many attempts creating data dictionaries information models associate data packaging mechanisms none practical implement perpetuated ongoing babelization data inability exchange data meaning since introduction semantic web concept tim berners-lee 1999 growing interest application w3c world wide web consortium w3c standards provide web-scale semantic data exchange federation inferencing capabilities syntactic interoperability provided instance xml sql standards pre-requisite semantic involves common data format common protocol structure data manner processing information interpretable structure also allows detection syntactic errors thus allowing receiving systems request resending message appears garbled incomplete semantic communication possible syntax garbled unable represent data however information represented one syntax may cases accurately translated different syntax accurate translation syntaxes possible systems using different syntaxes may also interoperate accurately cases ability accurately translate information among systems using different syntaxes may limited one direction formalisms used different levels expressivity ability express information single ontology containing representations every term used every application generally considered impossible rapid creation new terms assignments new meanings old terms however though impossible anticipate every concept user may wish represent computer possibility finding finite set primitive concept representations combined create specific concepts users may need given set applications ontologies foundation ontology also called upper ontology contains primitive elements would provide sound basis general semantic interoperability allow users define new terms need using basic inventory ontology elements still newly defined terms properly interpreted computer system interpret basic foundation ontology whether number primitive concept representations fact finite expand indefinitely question active investigation finite stable foundation ontology suitable support accurate general semantic interoperability evolve initial foundation ontology tested used wide variety users present time foundation ontology adopted wide community stable foundation ontology still future one persistent misunderstanding recurs discussion semantics confusion words meanings meanings words change sometimes rapidly formal language used ontology encode meanings semantics concepts form change order determine meaning particular word term database example necessary label fixed concept representation ontology word term may refer concept multiple words refer fixed concept language called synonymy one word used refer one concept called ambiguity ambiguity synonymy among factors make computer understanding language difficult use words refer concepts meanings words used sensitive context purpose use many human-readable terms use ontologies supporting semantic interoperability provide fixed set concepts whose meanings relations stable agreed users task determining terms contexts database different context separated task creating ontology must taken designer database designer form data entry developer program language understanding word used interoperability context changes meaning preserve interoperability necessary change pointer ontology element specifies meaning word knowledge representation language may sufficiently expressive describe nuances meaning well understood fields least five levels complexity general semi-structured data one may use general purpose language xml languages full power first-order predicate logic may required many tasks human languages highly expressive considered ambiguous allow accurate interpretation desired given current level human language technology semantic interoperability may distinguished forms interoperability considering whether information transferred communicated form meaning required receiving system interpret correctly even algorithms used receiving system unknown sending system consider sending one number number intended sum money owed one company another implies action lack action part send receive may correctly interpreted sent response specific request received time form expected correct interpretation depend number could represent almost millions types quantitative measurement rather depends strictly circumstances transmission interpretation depends systems expecting algorithms system use number exactly sense depends entire envelope transmissions preceded actual transmission bare number contrast transmitting system know information used systems necessary shared agreement information specific meaning many possible meanings appear communication particular task one solution standardize form request payment request would encode standardized fashion information needed evaluate agent owing money agent owed money nature action giving rise debt agents goods services participants action time action amount owed currency debt reckoned time allowed payment form payment demanded information two systems agreed interpret information request achieve semantic interoperability specific type transaction semantic interoperability generally necessary provide standardized ways describe meanings many things commercial transactions number concepts whose representation needs agreed upon minimum several thousand achieve semantic interoperability restricted scenarios currently matter research discussion problem general semantic interoperability form foundation ontology 'upper ontology required sufficiently comprehensive provide defining concepts specialized ontologies multiple domains past decade ten foundation ontologies developed none yet adopted wide user base need single comprehensive all-inclusive ontology support semantic interoperability avoided designing common foundation ontology set basic primitive concepts combined create logical descriptions meanings terms used local domain ontologies local databases tactic based principle therefore tactic limits need prior agreement meanings ontology elements common foundation ontology fo based several considerations likely fewer 10,000 elements types relations practice together fo focused representations primitive concepts set domain extension ontologies fo elements specified using fo elements likely also used pre-existing extensions ease cost creating domain ontologies providing existing elements intended meaning reduce chance error using elements already tested domain extension ontologies may logically inconsistent needs determined different domain extensions used communication whether use single foundation ontology avoided sophisticated mapping techniques among independently developed ontologies also investigation practical significance semantic interoperability measured several studies estimate cost lost efficiency due lack semantic interoperability one study focusing lost efficiency communication healthcare information estimated us 77.8 billion per year could saved implementing effective interoperability standard area studies construction industry automobile manufacturing supply chain estimate costs us 10 billion per year due lack semantic interoperability industries total numbers extrapolated indicate well us 100 billion per year lost lack widely used semantic interoperability standard us alone yet study policy field might offer big cost savings applying semantic interoperability standards see policy fields capable profiting semantic interoperability see 'interoperability general policy fields egovernment health security many eu also set semantic interoperability centre europe june 2007
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Computer architecture
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frontera web crawling frontera open-source web crawling framework implementing crawl frontier component providing scalability primitives web crawler applications content structure world wide web changes rapidly frontera designed able adapt quickly changes large scale web crawlers operate batch mode sequential phases injection fetching parsing deduplication scheduling leads delay updating crawl web changes design mostly motivated relatively low random access performance hard disks compared sequential access frontera instead relies modern key value storage systems using efficient data structures powerful hardware crawling parsing schedule indexing new links concurrently open-source project designed fit various use cases high flexibility configurability large-scale web crawls frontera purpose flexibility allows crawls moderate size single machine cores leveraging single process distributed spiders run modes frontera written mainly python data transport formats well abstracted out-of-box implementations include support messagepack json kafka zeromq although frontera n't web crawler requires streaming crawling architecture rather batch crawling approach stormcrawler another stream-oriented crawler built top apache storm whilst using components apache nutch ecosystem scrapy cluster designed istresearch precise monitoring management queue mind systems provide fetching and/or queueing mechanisms link database content processing scrapinghub ltd. crawler processing 1600 requests per second peak built using primarily frontera using kafka message bus hbase storage link states link database crawler operates cycles cycle takes 1.5 months results 1.7b downloaded pages crawl spanish internet resulted 46.5m pages 1.5 months aws cluster 2 spider machines first version frontera operated single process part custom scheduler scrapy using on-disk sqlite database store link states queue able crawl days getting noticeable volume links started spend time select queries making crawl inefficient time frontera developed darpa memex program included catalog open source projects 2015 subsequent versions frontera used hbase storing link database queue application distributed two parts backend fetcher backend responsible communicating hbase means kafka fetcher reading kafka topic urls crawl producing crawl results another topic consumed backend thus creating closed cycle first priority queue prototype suitable web scale crawling implemented time queue producing batches limits number hosts requests per host next significant milestone frontera development introduction crawling strategy strategy worker along abstraction message bus became possible code custom crawling strategy without dealing low-level backend code operating queue easy way say links scheduled priority made frontera truly crawl frontier framework kafka quite heavy requirement small crawlers message bus abstraction allowed integrate almost messaging system frontera
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Web technology
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google pixel google pixel brand consumer electronic devices developed google run either chrome os android operating system pixel brand introduced february 2013 first-generation chromebook pixel pixel line includes laptops tablets smartphones well several accessories google announced first generation pixel smartphones pixel pixel xl october 4 2016 madebygoogle event google emphasized camera two phones ranked best smartphone camera dxomarkmobile 90 points htc released u11 also scored 90 points largely due software optimizations hdr+ pixel phones also include unlimited cloud storage pictures google photos devices purchased directly google unlockable bootloader google announced pixel 2 series consisting pixel 2 pixel 2 xl october 4 2017 google announced pixel 3 pixel 3 xl event october 9 2018 alongside several products devices run android 9 pie may 7 i/o 2019 google announced pixel 3a pixel 3a xl budget alternatives original two pixel 3 devices pixel c announced google event september 29 2015 alongside nexus 5x nexus 6p phones among products pixel c includes usb-c port 3.5 mm headphone jack device shipped android 6.0.1 marshmallow later received android 7.x nougat android 8.x oreo google stopped selling pixel c december 2017 pixel slate 2-in-1 tablet laptop announced google new york city october 9 2018 alongside pixel 3 3 xl pixel slate includes two usb-c ports omits headphone jack device runs chrome os intel kaby lake processors options ranging celeron low end i7 high end june 2019 google announced develop product line cancelled two models development google announced first generation chromebook pixel blog post february 21 2013 laptop includes sd/multi-card reader mini displayport combination headphone/microphone jack two usb 2.0 ports device features include backlit keyboard fully clickable etched glass trackpad integrated stereo speakers two built-in microphones march 11 2015 google announced second generation chromebook pixel blog post laptop includes two usb-c ports two usb 3.0 ports sd card slot combination headphone/microphone jack device also backlit keyboard multi-touch clickable glass trackpad built-in stereo speakers two built-in microphones among features google discontinued 2015 chromebook pixel august 29 2016 october 4 2017 google launched third generation chromebook pixel named google pixelbook made google 2017 event google october 2017 hardware event set wireless earbuds unveiled alongside pixel 2 smartphones earbuds designed phones running android marshmallow higher work google assistant addition audio playback answering calls earbuds support translation 40 languages google translate earbuds able auto pair pixel 2 help google assistant nearby pixel buds available colors black clearly white kinda blue earbuds battery capacity 120 mah charging case comes pixel buds battery capacity 620 mah earbuds priced 159 alongside launch pixelbook october 2017 google announced pixelbook pen stylus used pixelbook pressure sensitivity well support google assistant pen powered replaceable aaaa battery priced us 99 october 2018 google announced pixel stand alongside pixel 3 smartphones addition standard 5 watt qi wireless charging pixel stand wireless 10 watt charging using proprietary technology google also enables software mode pixel 3 allows act smart display similar google home hub
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Operating systems
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list arm cortex-m development tools list development tools 32-bit arm cortex-m-based microcontrollers consists cortex-m0 cortex-m0+ cortex-m1 cortex-m3 cortex-m4 cortex-m7 cortex-m23 cortex-m33 cores ide compiler linker debugger flashing alphabetical order notes jtag and/or swd debug interface host adapters alphabetical order debugging tools and/or debugging plug-ins alphabetical order commonly referred rtos following free c/c++ libraries
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Computer architecture
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fsevents fsevents api macos allows applications register notifications changes given directory tree whenever filesystem changed kernel passes notifications via special device file codice_1 userspace process called codice_2 process combines multiple changes single directory tree occur within short period time notifies applications registered changes affected directory mac os x 10.7 fsevents watch filesystem linux inotify api provided notifications changes individual files application able register receive changes given directory determine file files changed mac os x 10.7 lion added ability register file modification notifications
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Operating systems
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strict function function f said strict applied non-terminating expression also fails terminate strict function denotational semantics programming languages function f formula_1 entity formula_2 called bottom denotes expression return normal value either loops endlessly aborts due error division zero function strict called non-strict strict programming language one user-defined functions always strict intuitively non-strict functions correspond control structures operationally strict function one always evaluates argument non-strict function one may evaluate arguments functions one parameter may strict non-strict parameter independently well jointly strict several parameters simultaneously example if-then-else expression many programming languages may thought function three parameters function strict first parameter since function must know whether first argument evaluates true false return non-strict second parameter example false formula_2,1 1 well non-strict third parameter example true,2 formula_2 2 however jointly strict second third parameters since true formula_2 formula_2 formula_2 false formula_2 formula_2 formula_2 non-strict functional programming language strictness analysis refers algorithm used prove strictness function respect one arguments functions compiled efficient calling convention call value without changing meaning enclosing program
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Programming language topics
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mentor routing algorithm mentor routing algorithm algorithm use routing mesh networks specifically pertaining initial topology developed 1991 aaron kershenbaum parviz kermani george a. grove published ieee empirical observation shown complexity class algorithm n² quadratic represents significant improvement currently used algorithms still yielding solutions quality competitive much slower procedures algorithm assumes three things conducive low- cost minimal distance travelled time destinations topology paths tend direct circuitous links high utilization —that used nearly maximum operating capacity long high-capacity links used whenever possible overall plan send traffic direct route source destination whenever magnitude requirement sufficiently large send via path within tree cases former case satisfying three goals -- using direct path high utilization high capacity latter case satisfying least last two objectives aggregating traffic much possible minimum spanning tree traffic flows latter case heuristically defined dijkstra algorithm prim algorithm
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Distributed computing architecture
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webroot internet security essentials webroot internet security essentials antivirus antispyware personal firewall security software back-up utility program additional personal pc security features originally launched october 21 2008 webroot internet security essentials first consumer security suite webroot webroot internet security essentials discontinued october 4 2011 webroot announced release secureanywhere™ line products time existing essentials licenses transitioned webroot secureanywhere essentials october 15 2012 product updated webroot secureanywhere® internet security plus latest version webroot secureanywhere internet security plus includes antivirus antispyware anti-phishing personal firewall password identity protection microsoft windows macos computers well protection android ios mobile devices reviews commented lack parental controls included security suite well difficulty configuring firewall
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Computer security
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comparison bsd operating systems number unix-like operating systems based descended berkeley software distribution bsd series unix variant options three notable descendants current use freebsd openbsd netbsd derived 386bsd 4.4bsd-lite various routes netbsd freebsd started life 1993 initially derived 386bsd 1994 migrating 4.4bsd-lite code base openbsd forked netbsd 1995 notable derivatives include dragonfly bsd forked freebsd 4.8 apple inc. ios macos darwin base including large amount code derived freebsd current bsd operating systems open source available download free charge bsd license notable exceptions macos ios also generally use monolithic kernel architecture apart macos ios dragonfly bsd feature hybrid kernels various open source bsd projects generally develop kernel userland programs libraries together source code managed using single central source repository past bsd also used basis several proprietary versions unix sun sunos sequent dynix next nextstep dec ultrix osf/1 axp became discontinued tru64 unix parts next software became foundation macos together ios among commercially successful bsd variants general market dragonfly bsd aims inherently easy understand develop multi-processor infrastructures main goal project forked freebsd 4.8 radically change kernel architecture introducing microkernel-like message passing enhance scaling reliability symmetric multiprocessing smp platforms also applicable numa clustered systems long-term goal provide transparent single system image clustered environments dragonfly bsd originally supported ia-32 x86-64 platforms however support ia-32 dropped version 4.0 matthew dillon founder dragonfly bsd believes supporting fewer platforms makes easier project proper ground-up smp implementation freebsd aims make operating system usable purpose intended run wide variety applications easy use contain cutting edge features highly scalable high load network servers freebsd free software project prefers freebsd license however sometimes accept non-disclosure agreements ndas include limited number nonfree hardware abstraction layer hal modules specific device drivers source tree support hardware companies provide purely libre drivers hals program software-defined radios vendors share nonfree algorithms maintain high level quality provide good support production quality commercial off-the-shelf cots workstation server high-end embedded systems freebsd focuses narrow set architectures significant focus development since 2000 fine-grained locking smp scalability 2007 kernel fine-locked scaling improvements started seen recent work includes common criteria security functionality mandatory access control security event audit support derivatives netbsd aims provide freely redistributable operating system professionals hobbyists researchers use manner wish main focus portability use clear distinctions machine-dependent machine-independent code runs wide variety 32-bit 64-bit processor architectures hardware platforms intended interoperate well operating systems netbsd places emphasis correct design well-written code stability efficiency practical close compliance open api protocol standards also aimed june 2008 netbsd foundation moved two-clause bsd license citing changes ucb industry applicability npf project spawned netbsd openbsd security-focused bsd known developers insistence extensive ongoing code auditing security correct functionality secure default philosophy good documentation adherence strictly open source licensing system incorporates numerous security features absent optional versions bsd openbsd policy openness extends hardware documentation drivers since without trust correct operation kernel security vendor software bugs would hard resolve openbsd emphasizes high standards areas security policies include disabling non-essential services sane initial settings integrated cryptography originally made easier due relaxed canadian export laws relative united states full public disclosure security flaws discovered thoroughly auditing code bugs security issues various security features including w^x page protection technology heavy use randomization mitigate attacks coding approaches include emphasis searching similar issues throughout code base code issue identified concerning software freedom openbsd prefers bsd isc license gpl acceptable existing software impractical replace gnu compiler collection ndas never considered acceptable common parent netbsd openbsd strives run wide variety hardware licenses conflict openbsd philosophy openbsd team re-implemented major pieces software scratch often become standard used within versions bsd examples include pf packet filter new privilege separation techniques used safeguard tools tcpdump tmux much openssh codebase replacing gpl licensed tools diff grep pkg-config isc bsd licensed equivalents openbsd prominently notes success security approach website home page two vulnerabilities ever found default install openssh vulnerability found 2002 remote network vulnerability found 2007 period almost 22 years according openbsd expert michael w. lucas openbsd widely regarded secure operating system available anywhere licensing terms openbsd spawned numerous child projects openssh openntpd openbgpd opensmtpd pf carp libressl many designed replace restricted alternatives derivatives september 2005 bsd certification group advertising number mailing lists surveyed 4,330 bsd users 3,958 took survey english assess relative popularity various bsd operating systems 77 respondents used freebsd 33 used openbsd 16 used netbsd 2.6 used dragonfly 6.6 used potentially non-bsd systems languages offered brazilian european portuguese german italian polish note control group pre-screening survey takers checked asked specify operating system survey takers permitted select one answer percentages shown graph number survey participants add greater 100 survey taker filled one choice still counted one vote chart another attempt profile worldwide bsd usage *bsdstats project whose primary goal demonstrate hardware vendors penetration bsd viability hardware drivers operating system project collects data monthly bsd system administrators willing participate currently records bsd market share participating freebsd openbsd netbsd dragonflybsd debian gnu/kfreebsd trueos mirbsd systems distrowatch well known linux community often used rough guide free operating system popularity publishes page hits linux distributions operating systems covers 4 september 2016 using data span last six months placed freebsd 21st place 479 hits per day trueos 46th place 244 hits per day ghostbsd 47th place 242 hits openbsd 75th place 163 hits per day midnightbsd 118th place 89 hits per day netbsd 142nd place 66 hits per day names freebsd openbsd references software freedom cost open source netbsd name tribute internet brought original developers together first bsd mascot bsd daemon named common type unix software program daemon freebsd still uses image red cartoon daemon named beastie wielding pitchfork mascot today 2005 competition stylized version beastie head designed drawn anton gural chosen freebsd logo freebsd slogan power serve netbsd flag designed 2004 grant bisset inspired original netbsd logo designed 1994 shawn mueller portraying number bsd daemons raising flag top mound computer equipment based world war ii photograph raising flag iwo jima board directors netbsd foundation believed complicated hard reproduce negative cultural ramifications thus suitable image netbsd corporate world new simpler flag design replaced netbsd slogan course runs netbsd referring operating system portability originally openbsd used bsd daemon mascot sometimes added halo distinguishing mark openbsd later replaced bsd daemon puffy although puffy usually referred pufferfish spikes cartoon images give closer likeness porcupinefish logo reference fish defensive capabilities blowfish cryptography algorithm used openssh openbsd also number slogans including secure default used first openbsd song e-railed free functional secure openbsd released least one original song every release since 3.0 dragonfly bsd logo designed joe angrisano dragonfly named fred number unofficial logos various authors also show dragonfly stylized versions dragonfly bsd considers logical continuation freebsd 4.x series fireflybsd similar logo firefly showing close relationship dragonfly bsd fact fireflybsd website states proceeds sales go development dragonfly bsd suggesting two may fact closely related picobsd slogan little bsd us logo includes version freebsd beastie child showing close connection freebsd minimal amount code needed run live cd number bsd oses use stylized version respective names logos includes macos trueos ghostbsd desktopbsd closedbsd microbsd trueos slogan personal computing served bsd style ghostbsd simple secure bsd served desktop desktopbsd step towards bsd desktop microbsd slogan small secure unix like os miros site collects variety bsd mascots tux linux mascot together illustrating project aim supporting bsd linux kernels miros slogan wonderful operating system world peace
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Operating systems
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tailored access operations office tailored access operations tao computer network operations structured s32 cyber-warfare intelligence-gathering unit national security agency nsa active since least circa 1998 tao identifies monitors infiltrates gathers intelligence computer systems used entities foreign united states tao reportedly largest arguably important component nsa huge signals intelligence directorate sid sigint consisting 1,000 military civilian computer hackers intelligence analysts targeting specialists computer hardware software designers electrical engineers snowden leak document leaked former nsa contractor edward snowden describing unit work says tao software templates allowing break commonly used hardware including routers switches firewalls multiple product vendor lines tao engineers prefer tap networks rather isolated computers typically many devices single network tao headquarters termed remote operations center roc based nsa headquarters fort meade maryland tao also expanded nsa hawaii wahiawa oahu nsa georgia fort gordon georgia nsa texas san antonio texas nsa colorado buckley air force base denver details program titled quantumsquirrel indicate nsa ability masquerade routable ipv4 ipv6 host enables nsa computer generate false geographical location personal identification credentials accessing internet utilizing quantumsquirrel nsa ant catalog 50-page classified document listing technology available united states national security agency nsa tailored access operations tao advanced network technology ant division aid cyber surveillance devices described already operational available us nationals members five eyes alliance according der spiegel released catalog public december 30 2013 list reads like mail-order catalog one nsa employees order technologies ant division tapping targets data document created 2008 security researcher jacob appelbaum gave speech chaos communications congress hamburg germany detailed techniques simultaneously published der spiegel article coauthored disclosed catalog tao developed attack suite call quantum relies compromised router duplicates internet traffic typically http requests go intended target nsa site indirectly nsa site runs foxacid software sends back exploits load background target web browser intended destination chance respond unclear compromised router facilitates race return trip prior development technology foxacid software made spear-phishing attacks nsa referred spam browser exploitable permanent implants rootkits etc deployed target computer e.g olympusfire windows give complete remote access infected machine type attack part man-in-the-middle attack family though specifically called man-on-the-side attack difficult pull without controlling internet backbone numerous services foxacid exploit way names foxacid modules given collaboration british government communications headquarters gchq muscular google services could attacked including gmail finding machines exploitable worth attacking done using analytic databases xkeyscore specific method finding vulnerable machines interception windows error reporting traffic logged xkeyscore quantum attacks launched nsa sites slow combinations targets services essentially try exploit race condition i.e nsa server trying beat legitimate server response mid-2011 nsa prototyping capability codenamed qfire involved embedding exploit-dispensing servers virtual machines running vmware esx hosted closer target so-called special collection sites scs network worldwide goal qfire lower latency spoofed response thus increasing probability success commendeer used commandeer i.e compromise untargeted computer systems software used part quantumnation also includes software vulnerability scanner validator tool first described 2014 chaos communication congress jacob appelbaum characterized tyrannical quantumcookie complex form attack used tor users according 2013 article foreign policy tao become increasingly accomplished mission thanks part high-level cooperation secretly receives 'big three american telecom companies verizon sprint large us-based internet service providers many top computer security software manufacturers consulting companies 2012 tao budget document claims companies tao behest insert vulnerabilities commercial encryption systems systems networks endpoint communications devices used targets number us companies including cisco dell subsequently made public statements denying insert back doors products microsoft provides advance warning nsa vulnerabilities knows fixes information vulnerabilities available public enables tao execute so-called zero-day attacks microsoft official declined identified press confirmed indeed case said microsoft held responsible nsa uses advance information since 2013 head tao rob joyce 25-plus year employee previously worked nsa information assurance directorate iad january 2016 joyce rare public appearance gave presentation usenix ’ enigma conference
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Computer security
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gnulinex gnulinex linex debian-based operating system uses gnome desktop initiative regional government extremadura spain gnulinex intended used schools extremadura well official institutions actively promoted business home use well gnulinex compatible computers based i386 architecture aim project promotion technologically literate information-based society order improve citizens quality life extremadura changed names many programs installed default distribution caused confusion amongst users see virtue helping remember favorite applications spanish instead english names 2004 version includes possibility choosing original icons names applications included gnulinex school linex gnulinex variant oriented toward teachers consists three user profiles profile personalised particular student content software pupil
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Computer architecture
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arc programming language arc programming language dialect language lisp developed paul graham robert morris free open-source software released artistic license 2.0 2001 paul graham announced working new dialect lisp named arc years since written several essays describing features goals language internal projects graham startup business incubator named combinator written arc notably hacker news web forum news aggregator program arc written racket essay popular graham describes goals language many goals general arc hackable good libraries give specifics example believes important language terse also stated better language implement small number axioms even means language may features large organizations want object-orientation oo graham thinks oo useful methods patterns good design views language features used implement oo partly mistaken arc introduction 2008 graham stated one benefits brevity controversy among lisp programmers whether much s-expressions language complemented forms syntax graham thinks added syntax used situations pure s-expressions would overly verbose saying n't think religiously opposed introducing syntax lisp graham also thinks efficiency problems solved giving programmer good profiler released 2008 arc generated mixed reactions calling simply extension lisp scheme programming language right others applauded arc stripping lisp bare essentials shortly release arc ported javascript supported schemescript integrated development environment ide based eclipse hello world arc illustrate arc terseness graham uses brief program produces form one field url /said form submitted leads page link says click leads page value original input field first publicly released version arc made available 29 january 2008 implemented racket named plt-scheme release comes form .tar archive containing racket source code arc tutorial discussion forum also available forum uses program hacker news written arc due lack updates official arc branch members arc community started repositories unofficial modifications extensions libraries one version anarki permitted anyone submit changes project community managed wiki rainbow implementation arc java arcadia implementation arc c
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Programming language topics
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del command computing codice_1 codice_2 command command-line interpreters shells codice_3 codice_4 4dos ndos 4os2 4nt windows powershell used delete one files directories file system command available various operating systems including dos microware os-9 ibm os/2 microsoft windows reactos analogous unix codice_5 command stratus openvos codice_6 codice_7commands dec rt-11 rsx-11 os/8 openvms also provide codice_8 command contracted codice_1 amigados tsc flex provide codice_8 command well ms-dos command available versions 1 later also available open-source ms-dos emulator dosbox dr-dos supports codice_1 codice_2 well also supports shorthand form codice_13 derived cp/m addition dr-dos command processor also supports codice_14/codice_15 shorthand forms codice_1/codice_13/codice_2 command assumed codice_19 parameter 'query given well theos/oasis flexos provide codice_2 command powershell codice_1 codice_2 predefined command aliases codice_23 cmdlet basically serves purpose
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Computer file systems
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btx form factor btx balanced technology extended form factor motherboards originally intended replacement aging atx motherboard form factor late 2004 early 2005 designed alleviate issues arose using newer technologies often demand power create heat motherboards compliant circa 1996 atx specification atx btx standards proposed intel however future development btx retail products intel canceled september 2006 following intel decision refocus low-power cpus suffering scaling thermal issues pentium 4 first company implement btx gateway inc followed dell mpc first generation apple mac pro used elements btx design system well btx-compliant instead using proprietary form factor pico btx motherboard form factor meant miniaturize btx standard pico btx motherboards measure smaller many current micro -sized motherboards hence name pico motherboards share common top half sizes btx line support one two expansion slots designed half-height riser card applications smaller btx sizes include micro btx nano btx heat sink attached cpu called thermal module throughout official specification longer attached solely motherboard casing inertial load mass mechanical shock event longer damage motherboard structural interface heat sink chassis defined 4 mounting holes distances 4.4 × 2.275 55.79 × 111.76 mm one another since attachment means also required certain stiffness called support retention module srm specification first months production atx btx motherboards similar moving btx motherboard atx case possible vice versa possible first btx motherboards atx motherboards turned upside except component location really btx positioning later btx form factor big change turning mirror image atx standard since new motherboard design standards incompatible basically btx motherboards 'leftside-right compared atx upside-down i.e mounted opposite side case computer cases cooler master series stackers released support varying range motherboard standards atx btx mini-atx forth ease motherboard upgrade without buying new case however connector slot standards identical including pci e cards processors ram hard drives etc btx power supply units exchanged newer atx12v units older atx power supplies n't extra 4-pin 12v connector introduced atx12v standard btx form factor widely adopted despite improvements atx related standards result availability variety btx-compatible components limited one reason failure btx gain traction key markets rise energy-efficient components cpus chipsets gpus require less power produce less waste heat eliminating two primary intended benefits btx another reason lack oem adopters initially gateway dell offered computers new format later hp fujitsu-siemens fujitsu also offered btx-based computers manufacturers stayed atx standard even handful manufacturers adopt btx products continued produce bulk machines atx form factor
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Computer architecture
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client puzzle protocol client puzzle protocol cpp computer algorithm use internet communication whose goal make abuse server resources infeasible implementation proof-of-work system pow idea cpp require clients connecting server correctly solve mathematical puzzle establishing connection server attack solving puzzle client would return solution server server would quickly verify reject drop connection puzzle made simple easily solvable requires least minimal amount computation client side legitimate users would experience negligible computational cost abuse would deterred clients try simultaneously establish large number connections would unable computational cost time delay method holds promise fighting types spam well attacks like denial-of-service
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Computer security
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pdp-8 pdp-8 12-bit minicomputer produced digital equipment corporation dec first commercially successful minicomputer 50,000 examples sold model lifetime basic design follows pioneering linc smaller instruction set expanded version pdp-5 instruction set similar machines dec pdp-12 modernized version pdp-8 linc concepts pdp-14 industrial controller system earliest pdp-8 model informally known straight-8 introduced 22 march 1965 priced 18,500 used diode–transistor logic packaged flip chip cards machine size small household refrigerator first computer sold 20,000 making best-selling computer history time straight-8 supplanted 1966 pdp-8/s available desktop rack-mount models using one-bit serial arithmetic logic unit alu allowed pdp-8/s smaller less expensive although slower original pdp-8 basic 8/s sold 10,000 first machine reach milestone later systems pdp-8/i /l pdp-8/e /f /m pdp-8/a returned faster fully parallel implementation use much less costly transistor–transistor logic ttl msi logic surviving pdp-8s era pdp-8/e common well-regarded many types i/o devices available last commercial pdp-8 models introduced 1979 called cmos-8s based cmos microprocessors priced competitively offering failed intersil sold integrated circuits commercially 1982 intersil 6100 family virtue cmos technology low power requirements used embedded military systems chief engineer designed initial version pdp-8 edson de castro later founded data general pdp-8 combines low cost simplicity expandability careful engineering value greatest historical significance pdp-8 low cost high volume made computer available many new customers many new uses continuing significance historical example value-engineered computer design low complexity brought costs made programming cumbersome seen examples article discussion pages fields much one code performed required mechanics opposed setting algorithm example subtracting number involves computing two complement adding writing conditional jump involves writing conditional skip around jump skip coding condition negative one desired ambitious programming projects failed fit memory developed design defects could solved example noted inadvertent recursion subroutine produces defects difficult trace subroutine question design advances reduced costs logic memory programmer time became relatively important subsequent computer designs emphasized ease programming typically using larger intuitive instruction sets eventually machine code generated compilers report generators reduced instruction set computer returned full-circle pdp-8 emphasis simple instruction set achieving multiple actions single instruction cycle order maximize execution speed although newer computers much longer instruction words pdp-8 used ideas several 12-bit predecessors notably linc designed w.a clark c.e molnar inspired seymour cray cdc 160 minicomputer pdp-8 uses 12 bits word size arithmetic unsigned integers 0 4095 signed integers -2048 +2047 however software multiple-precision arithmetic interpreter available floating point operations example used 36-bit floating point representation two-word 24-bit mantissa one-word exponent subject speed memory limitations pdp-8 perform calculations similar expensive contemporary electronic computers ibm 1130 various models ibm system/360 easier interface external devices memory address space also 12 bits pdp-8 basic configuration main memory 4,096 2 twelve-bit words optional memory-expansion unit switch banks memories using iot instruction memory magnetic-core memory cycle time 1.5 microseconds 0.667 mhz typical two-cycle fetch execute memory-reference instruction runs speed 0.333 mips 1974 pocket reference card pdp-8/e gives basic instruction time 1.2 microseconds 2.6 microseconds instructions reference memory pdp-8 designed part handle contemporary telecommunications text six-bit character codes widespread use time pdp-8 twelve-bit words efficiently store two characters addition six-bit teleprinter code called teletypesetting tts code widespread use news wire services early application pdp-8 typesetting using code later 7-bit ascii 8-bit utf-8 character codes developed part response limitations five- six-bit character codes pdp-8 instructions 3-bit opcode eight instructions assembler provides instruction mnemonics programmer translating i/o operate-mode instructions combinations op-codes instruction fields also three programmer-visible registers 12-bit accumulator ac program counter pc carry flag called link register l input output pdp-8 single interrupt shared devices i/o bus accessed i/o instructions direct memory access dma channel programmed i/o bus typically runs low medium-speed peripherals printers teletypes paper tape punches readers dma used cathode ray tube screens light pen analog-to-digital converters digital-to-analog converters tape drives disk drives save money design used inexpensive main memory many purposes served expensive flip-flop registers computers auxiliary counters subroutine linkage basic models use software multiplication division faster math extended arithmetic element eae provides multiply divide instructions additional register multiplier/quotient mq register eae option original pdp-8 8/i 8/e integral part intersil 6100 microprocessor pdp-8 optimized simplicity design compared complex machines unnecessary features removed logic shared possible instructions use autoincrement autoclear indirect access increase software speed reduce memory use substitute inexpensive memory expensive registers electronics basic pdp-8 cpu four 12-bit registers accumulator program counter memory-buffer register memory-address register save money served multiple purposes different points operating cycle example memory buffer register provides arithmetic operands part instruction register stores data rewrite core memory restores core data destroyed read simplicity early pdp-8 models less expensive commercially available computers however used costly production methods often used prototypes used thousands small standardized logic-modules gold connectors integrated costly complex wire-wrapped backplane large cabinet later 8/s model two different logic voltages increased fan-out inexpensive diode–transistor logic 8/s also reduced number logic gates using serial single-bit-wide data path arithmetic cpu pdp-8/s 519 logic gates comparison small microcontrollers 2008 usually 15,000 reductions electronics permitted much smaller case size bread-box even later pdp-8/e larger capable computer reengineered better value employs faster transistor–transistor logic integrated circuits core memory redesigned allows expansion less expense uses omnibus place wire-wrapped backplane earlier models personal account development pdp-8/e read engineering technology history wiki total sales figure pdp-8 family estimated 300,000 machines following models manufactured pdp-8 readily emulated instruction set much simpler modern architectures enthusiasts created entire pdp-8s using single fpga devices several software simulations pdp-8 available internet well open-source hardware re-implementations best correctly execute dec operating systems diagnostic software software simulations often simulate late-model pdp-8s possible peripherals even use tiny fraction capacity modern personal computer i/o systems underwent huge changes pdp-8 era early pdp-8 models use front panel interface paper-tape reader teletype printer optional paper-tape punch time i/o systems magnetic tape rs-232 current loop dumb terminals punched card readers fixed-head disks added toward end pdp-8 era floppy disks moving-head cartridge disk drives popular i/o devices modern enthusiasts created standard pc style ide hard disk adapters real simulated pdp-8 computers several types i/o supported simplified inexpensive form dma called three-cycle data break supported requires assistance processor data break method moves common logic needed implement dma i/o i/o device one common copy logic within processor data break places processor charge maintaining dma address word count registers three successive memory cycles processor updates word count updates transfer address stores retrieves actual i/o data word one-cycle data break effectively triples dma transfer rate target data needed transferred core memory however i/o devices need electronic logic manage word count transfer address registers time pdp-8/e introduced electronic logic become less expensive one-cycle data break became popular early pdp-8 systems operating system front panel run halt switches software development systems pdp-8 series began basic front-panel entry raw binary machine code booting entry middle era various paper tape operating systems developed many utility programs became available paper tape pal-8 assembly language source code often stored paper tape read memory saved paper tape pal assembled paper tape memory paper tape versions number programming languages available including dec focal interpreter 4k fortran compiler runtime toward end pdp-8 era operating systems os/8 cos-310 allowed traditional line mode editor command-line compiler development system using languages pal-iii assembly language fortran basic dibol fairly modern advanced real-time operating system rtos preemptive multitasking multi-user systems available real-time system rts-8 available multiuser commercial systems cos-300 cos-310 dedicated single-user word-processing system wps-8 time-sharing system tss-8 also available tss-8 allows multiple users log system via 110-baud terminals edit compile debug programs languages include special version basic fortran subset similar fortran-1 user-written subroutines functions algol subset focal assembler called pal-d. fair amount user-donated software pdp-8 available decus digital equipment corporation user society often came full source listings documentation three high-order bits 12-bit instruction word labelled bits 0 2 operation code six operations refer memory bits 5 11 provide 7-bit address bit 4 set says complete address using 5 high-order bits program counter pc register meaning addressed location within 128 words instruction bit 4 clear zeroes used addressed location within first 128 words memory bit 3 specifies indirection set address obtained described far points 12-bit value memory gives actual effective address instruction allows operands anywhere memory expense additional word jmp instruction operate memory word except indirection specified bit fields use instruction word divides 4,096-word memory 128-word pages bit 4 instruction selects either current page page 0 addresses 0000–0177 octal memory page 0 premium since variables placed addressed directly page moreover address 0000 interrupt service routine must start addresses 0010–0017 special property auto-incrementing preceding indirect reference standard assembler places constant values arithmetic current page likewise cross-page jumps subroutine calls use indirect address current page important write routines fit within 128-word pages arrange routines minimize page transitions references jumps outside current page require extra word consequently much time spent cleverly conserving one several words programmers deliberately placed code end page achieve free transition next page pc incremented pdp-8 processor defined iot instructions simply provided framework iot instructions defined individual i/o devices bits 3 8 iot instruction select i/o device device addresses standardized convention instructions device 0 affect processor whole example ion 6001 enables interrupt processing ioff 6002 disables bits 9 11 iot instruction select function device performs simple devices paper tape reader punch console keyboard printer use bits standard ways operations take place well-defined order gives useful results one bit set complicated devices disk drives use 3 bits device-specific fashions typically device decodes 3 bits give 8 possible function codes many operations achieved using opr including conditionals opr address memory location conditional execution achieved conditionally skipping one instruction typically jmp opr instruction said microcoded mean word means today lower-level program fetched interpreted opr instruction meant bit instruction word specifies certain action programmer could achieve several actions single instruction cycle setting multiple bits use programmer write several instruction mnemonics alongside one another assembler combines devise actual instruction word many i/o devices support microcoded iot instructions microcoded actions take place well-defined sequence designed maximize utility many combinations opr instructions come groups bits 3 8 11 identify group opr instruction impossible combine microcoded actions different groups cases operations sequenced combined useful ways example combining cla clear accumulator cll clear link iac increment accumulator first clears ac link increments accumulator leaving set 1 adding ral mix cla cll iac ral causes accumulator cleared incremented rotated left leaving set 2 way small integer constants placed accumulator single instruction combination cma iac assembler lets abbreviate cia produces arithmetic inverse ac twos-complement negation since subtraction instruction twos-complement add tad computing difference two operands requires first negating subtrahend group 1 opr instruction none microprogrammed bits set performs action programmer write nop operation assemble instruction bit 8 clear skip performed specified conditions true example sma sza opcode 7540 skips ac ≤ 0 group 2 opr instruction none microprogrammed bits set another no-op instruction bit 8 set group 2 skip condition inverted via de morgan laws skip performed group 2 conditions true meaning specified skip conditions must true example spa sna opcode 7550 skips ac 0 none bits 5–7 set skip unconditional unused bit combinations opr defined third group microprogrammed actions mostly affecting mq multiplier/quotient register typically cla mqa combined transfer mq ac another useful combination mqa mql exchange two registers three bits specified multiply/divide instruction perform 12-bit word 4,096 different values maximum number words original pdp-8 address indirectly word pointer programs became complex price memory fell became desirable expand limit maintain compatibility pre-existing programs new hardware outside original design added high-order bits effective addresses generated program memory extension controller expands addressable memory factor 8 total 32,768 words expansion thought sufficient core memory costing 50 cents word full 32k memory would equal cost cpu 4k memory called field memory extension controller contains two three-bit registers df data field instruction field registers specify field memory reference cpu allowing total 15 bits address register specifies field instruction fetches direct memory references df register specifies field indirect data accesses program running one field reference data field direct addressing reference data another field indirect addressing set i/o instructions range 6200 6277 handled memory extension controller give access df registers 62x1 instruction cdf change data field set data field x similarly 62x2 cif set instruction field 62x3 set pre-existing programs would never execute cif cdf df registers would point field single field programs limited effect cif instruction deferred coincide next jmp jms instruction executing cif would cause jump complicated multiple-field programs deal field boundaries df registers would could simply generate 15-bit addresses design provided backward compatibility consistent 12-bit architecture used throughout pdp-8 compare later intel 8086 whose 16-bit memory addresses expanded 20 bits combining contents specified implied segment register extended memory scheme let existing programs handle increased memory minimal changes example 4k focal normally 3k code 1k left user program data patches focal could use second 4k field user program data moreover additional 4k fields could allocated separate users turning 4k focal multi-user timesharing system pdp-8/e later models memory extension controller enhanced enable machine virtualization program written use pdp-8 entire resources coexist programs pdp-8 control virtual machine manager manager make i/o instructions including operated memory extension controller cause trap interrupt handled manager way manager map memory references map data instruction fields redirect i/o different devices original program complete access virtual machine provided manager new i/o instructions memory extension controller retrieve current value data instruction fields letting software save restore machine state across trap however program sense whether cpu process deferring effect cif instruction whether executed cif yet executed matching jump instruction manager include complete pdp-8 emulator difficult 8-instruction machine whenever cif instruction traps manager emulate instructions next jump fortunately jump usually next instruction cif emulation slow programs much large workaround seemingly small design deficiency time pdp-8/a memory prices fallen enough memory exceeding 32k desirable 8/a added new set instructions handling eight fields memory field number could placed ac rather hard-coded instruction however time pdp-8 decline little standard software modified use new features following examples show code pdp-8 assembly language one might write pal-iii assembler following piece code shows needed compare two numbers shown much text typical pdp-8 program focuses author intended algorithm low-level mechanics additional readability problem conditional jumps one shown conditional instruction skips around jmp highlights opposite condition interest complete pdp-8 assembly language program outputs hello world teleprinter pdp-8 processor implement stack upon store registers context subroutine called interrupt occurs stack implemented software demonstrated next section instead jms instruction simply stores updated pc pointing past jms return address effective address jumps effective address plus one subroutine returned caller using indirect jmp instruction addresses subroutine first word example hello world re-written use subroutine jms instruction jumps subroutine modifies 0 coded location out1 fact jms instruction uses word code subroutine deposit return address prevents reentrancy recursion without additional work programmer also makes difficult use rom pdp-8 read-write return-address storage commingled read-only code storage address space programs intended placed roms approach problem several ways use jms instruction makes debugging difficult programmer makes mistake subroutine call directly intermediate subroutine return address outer call destroyed return address subsequent call leading infinite loop one module coded incorrect obsolete address subroutine would fail execute entire code sequence subroutine might modify word subroutine code depositing return address processor might interpret instruction subsequent correct call subroutine types error might become evident execution code written correctly though pdp-8 hardware stack stacks implemented software example push pop subroutines simplified omit issues testing stack overflow underflow hello world stack implemented subroutine another possible subroutine pdp-8 linked list single interrupt line pdp-8 i/o bus processor handles interrupt disabling interrupts executing codice_1 location 0000 difficult write reentrant subroutines difficult nest interrupts usually done interrupt runs completion re-enables interrupts executing codice_2 instruction returns interrupt single interrupt line i/o bus occurrence interrupt inform processor source interrupt instead interrupt service routine serially poll active i/o device see source code called skip chain consists series pdp-8 test skip flag set i/o instructions unheard-of skip chain reach end without finding device need service relative interrupt priority i/o devices determined position skip chain several devices interrupt device tested earlier skip chain serviced first engineering textbook popular 1980s art digital design david winkel franklin prosser contains example problem spanning several chapters authors demonstrate process designing computer compatible pdp-8/i function every component explained although production design uses modern ssi msi components exercise provides detailed description computer operation
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Computer architecture
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hewlett-packard raster transfer language hewlett-packard raster transfer language hp rtl subset printer command language pcl language used embed true raster images bitmaps plotter files modern plotters like hp designjets raster devices need raster-based language backward compatibility also support hp-gl/2 formerly hp-gl vector language hp rtl language designed mixing hp-gl/2 language
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Programming language topics
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dolev–yao model dolev–yao model formal model used prove properties interactive cryptographic protocols network represented set abstract machines exchange messages messages consist formal terms terms reveal internal structure messages parts hopefully remain opaque adversary adversary model overhear intercept synthesize message limited constraints cryptographic methods used words attacker carries message omnipotence difficult model many threat models simplify example attacker ubiquitous computing cryptographic primitives modeled abstract operators example asymmetric encryption user formula_1 represented encryption function formula_2 decryption function formula_3 main properties composition identity function formula_4 encrypted message formula_5 reveals nothing formula_6 unlike real world adversary neither manipulate encryption bit representation guess key attacker may however re-use messages sent therefore become known attacker encrypt decrypt keys knows forge subsequent messages protocol modeled set sequential runs alternating queries sending message network responses obtaining message network symbolic nature dolev–yao model makes manageable computational models accessible algebraic methods potentially less realistic however kinds models cryptographic protocols related also symbolic models well suited show protocol broken rather secure given assumptions attackers capabilities
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Computer security
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yahoo yahoo american web services provider headquartered sunnyvale california owned verizon media original yahoo company founded jerry yang david filo january 1994 incorporated march 2 1995 yahoo one pioneers early internet era 1990s provides provided web portal search engine yahoo search related services including yahoo directory yahoo mail yahoo news yahoo finance yahoo groups yahoo answers advertising online mapping video sharing fantasy sports social media website height one popular sites united states according third-party web analytics providers alexa similarweb yahoo widely read news media website – 7 billion views per month – ranking sixth-most-visited website globally 2016 one largest internet companies yahoo slowly declined starting late 2000s 2017 verizon communications acquired yahoo internet business 4.48 billion ref name= yahoo -inc-jun-2017-sc-to-i/a /ref excluding stakes alibaba group yahoo japan transferred yahoo successor company altaba despite decline prominence yahoo domain websites still one popular ranking 8th world according alexa rankings january 2019 january 1994 yang filo electrical engineering graduate students stanford university created website named jerry david guide world wide web site directory websites organized hierarchy opposed searchable index pages march 1994 jerry david guide world wide web renamed yahoo human-edited yahoo directory provided users surf internet became first product company original purpose yahoo.com domain created january 18 1995 word yahoo backronym yet another hierarchically organized oracle yet another hierarchical officious oracle term hierarchical described yahoo database arranged layers subcategories term oracle intended mean source truth wisdom term officious rather related word normal meaning described many office workers would use yahoo database surfing work however filo yang insist mainly selected name liked slang definition yahoo used college students david filo native louisiana late 1980s early 1990s refer unsophisticated rural southerner rude unsophisticated uncouth meaning derives yahoo race fictional beings gulliver travels yahoo grew rapidly throughout 1990s yahoo went public april 1996 stock price rose 600 percent within two years like many search engines web directories yahoo added web portal putting competition services like excite lycos america online 1998 yahoo popular starting point web users human-edited yahoo directory popular search engine receiving 95 million page views per day triple number compared rival excite also made many high-profile acquisitions yahoo began offering free e-mail october 1997 acquisition rocketmail renamed yahoo mail 1998 yahoo decided replace altavista crawler-based search engine underlying directory inktomi yahoo two biggest acquisitions made 1999 – geocities 3.6 billion broadcast.com 5.7 billion stock price skyrocketed dot-com bubble yahoo stocks closing all-time high 118.75 share january 3 2000 however dot-com bubble burst reached post-bubble low 8.11 september 26 2001 yahoo began using google search 2000 next four years developed search technologies began using 2004 partly using technology 280 million acquisition inktomi 2002 response google gmail yahoo began offer unlimited email storage 2007 company struggled 2008 several large layoffs february 2008 microsoft corporation made unsolicited bid acquire yahoo 44.6 billion yahoo formally rejected bid claiming substantially undervalues company interest shareholders three years later yahoo market capitalization 22.24 billion carol bartz replaced yang ceo january 2009 september 2011 removed position yahoo company chairman roy bostock cfo tim morse named interim ceo company early 2012 appointment scott thompson ceo rumors began spread looming layoffs several key executives left including chief product officer blake irving. ref name= yahoo -inc-apr-2012-10-k/a /ref april 4 2012 yahoo announced cut 2,000 jobs 14 percent 14,100 workers cut expected save around 375 million annually layoffs completed end 2012 email sent employees april 2012 thompson reiterated view customers come first yahoo also completely reorganized company may 13 2012 yahoo issued press release stating thompson longer company would immediately replaced interim basis ross levinsohn recently appointed head yahoo new media group thompson total compensation 130-day tenure yahoo least 7.3 million july 15 2012 marissa mayer appointed president ceo yahoo effective july 17 2012 may 19 2013 yahoo board approved 1.1 billion purchase blogging site tumblr tumblr ceo founder david karp would remain large shareholder announcement reportedly signified changing trend technology industry large corporations like yahoo facebook google acquired start-up internet companies generated low amounts revenue way connect sizeable fast-growing online communities wall street journal stated purchase tumblr would satisfy yahoo need thriving social-networking communications hub may 20 company announced acquisition tumblr officially transaction completed one month company also announced plans open san francisco office july 2013 august 2 2013 yahoo acquired rockmelt staff retained existing products terminated data collated comscore july 2013 revealed people u.s. visited yahoo websites month google occasion first time yahoo outperformed google since 2011 data count mobile usage tumblr december 12 2014 yahoo completed acquisition video advertising provider brightroll 583 million november 21 2014 announced yahoo acquired cooliris fourth quarter 2013 company share price doubled since marissa mayer took president july 2012 however share price peaked 35 november 2013 go 36.04 mid-afternoon december 2 2015 perhaps news board directors meeting decide future mayer whether sell struggling internet business whether continue spinoff stake china alibaba e-commerce site gone well mayer tenure including 1.1 billion acquisition tumblr yet prove beneficial forays original video content led 42 million write-down sydney finkelstein professor dartmouth college tuck school business told washington post sometimes single best thing ... sell company closing price yahoo inc. december 7 2015 34.68 wall street journal douglas macmillan reported february 2 2016 yahoo ceo marissa mayer expected cut 15 workforce july 25 2016 verizon communications announced agreed purchase yahoo core internet business 4.83 billion following conclusion purchase assets merged aol form new entity known oath inc. june 13 2017 yahoo aol huffington post continue operate names oath inc. umbrella deal excludes yahoo 15 stake alibaba group 35.5 stake yahoo japan following completion acquisition assets retained name altaba new executive team september 22 2016 yahoo disclosed data breach occurred late 2014 information associated least 500 million user accounts one largest breaches reported date united states indicted four men including two employees russia federal security service fsb involvement hack december 14 2016 company revealed another separate data breach occurred 2014 hackers obtaining sensitive account information including security questions least one billion accounts company stated hackers utilized stolen internal software forge http cookies response breaches bloomberg news reported verizon attempting re-negotiate deal reduce purchase price 250 million causing 2 increase yahoo stock prices february 21 2017 verizon agreed lower purchase price yahoo 350 million share liabilities regarding investigation data breaches june 8 2017 yahoo shareholders approved company sale internet assets verizon 4.48 billion deal officially closed june 13 2017 press release october 3 2017 oath inc. subsidiary verizon stated yahoo user accounts 3 billion affected august 2013 theft june 16 2017 parts original yahoo inc purchased verizon communications renamed altaba inc. united states securities exchange commission website listed new company non-diversified closed-end management investment company former yahoo inc. ticker symbol yhoo retired favor aaba took place monday june 19 2017 yahoo operated portal provides latest news entertainment sports information portal also gave users access yahoo services like yahoo search yahoo mail yahoo maps yahoo finance yahoo groups yahoo messenger yahoo provided internet communication services yahoo messenger yahoo mail may 2007 e-mail service would offer unlimited storage yahoo provided social networking services user-generated content including products web yahoo personals yahoo 360° delicious flickr yahoo buzz yahoo closed yahoo buzz mybloglog numerous products april 21 2011 yahoo photos closed september 20 2007 favor flickr october 16 2007 yahoo announced would discontinue yahoo 360° including bug repairs company explained 2008 would instead establish universal profile similar yahoo mash experimental system yahoo partners numerous content providers products yahoo sports yahoo finance yahoo music yahoo movies yahoo weather yahoo news yahoo answers yahoo games provide news related content yahoo provides personalization service yahoo enables users combine favorite yahoo features content feeds information onto single page march 31 2008 yahoo launched shine site tailored women seeking online information advice ages 25 54 yahoo developed partnerships broadband providers inc. via prodigy bellsouth sbc verizon communications rogers communications british telecom offering range free premium yahoo content services subscribers yahoo mobile offers services email instant messaging mobile blogging well information services searches alerts services camera phone include entertainment ring tones yahoo introduced internet search system called onesearch mobile phones march 20 2007 results include news headlines images flickr business listings local weather links sites instead showing example popular movies critical reviews onesearch lists local theaters moment playing movie along user ratings news headlines regarding movie zip code city name required onesearch start delivering local search results results web search listed single page prioritized categories 2012 yahoo used novarra mobile content transcoding service onesearch october 8 2010 yahoo announced plans bring video chat mobile phones via yahoo messenger yahoo offers shopping services yahoo shopping yahoo autos yahoo real estate yahoo travel enables users gather relevant information make commercial transactions purchases online yahoo auctions discontinued 2007 except asia yahoo shopping price comparison service uses kelkoo price comparison service acquired april 2004 yahoo search marketing provides services sponsored search local advertising product/travel/directory submit let different businesses advertise products services yahoo network following closure beta version april 30 2010 yahoo publisher network relaunched advertising tool allows online publishers monetize websites use site-relevant advertisements yahoo launched new internet advertisement sales system fourth quarter 2006 called panama allows advertisers bid search terms trigger ads search results pages system considers bids ad quality clickthrough rates factors ranking ads panama yahoo aims provide relevant search results users better overall experience increase monetization april 7 2008 yahoo announced apt yahoo originally called amp yahoo online advertising management platform platform simplifies advertising sales unifying buyer seller markets service launched september 2008 july 2009 yahoo agrees use microsoft exclusive technology provider search services microsoft provide contextual advertising yahoo non-exclusive basis yahoo exclusive worldwide relationship sales force yahoo microsoft premium search advertisers september 2011 yahoo formed ad selling strategic partnership 2 top competitors aol microsoft 2013 found underperforming market share revenue microsoft simply skimmed four percent search market yahoo without growing combined share yahoo next incubation ground future yahoo technologies currently undergoing testing contained forums yahoo users give feedback assist development future yahoo technologies yahoo search boss service allows developers build search applications based yahoo search technology early partners program include hakia me.dium delver daylife yebol early 2011 program switched paid model using cost-per-query model 0.40 0.75 cpm cost per 1000 boss queries price yahoo explained depends whether query web image news information became defunct 2016 replaced yahoo partner ads yahoo meme beta social service similar popular social networking sites twitter jaiku connect enables individuals leave comments online publication boards using yahoo id instead register individual publications wall street journal reported yahoo plans mimic strategy used rival facebook inc. help drive traffic site yahoo invested resources increase improve access internet disabled community yahoo accessibility lab yahoo axis desktop web browser extension mobile browser ios devices created developed yahoo extension made public debut may 23 2012 retired june 28 2013 copy private key used sign official yahoo browser extensions google chrome accidentally leaked first public release chrome extension yahoo searchmonkey often misspelled search monkey yahoo service allowed developers site owners use structured data make yahoo search results useful visually appealing drive relevant traffic sites service shut october 2010 along yahoo services part microsoft yahoo search deal name searchmonkey homage greasemonkey officially product name space two capital letters yahoo searchmonkey selected one top 10 semantic web products 2008 geocities popular web hosting service founded 1995 one first services offer web pages public one point third-most-browsed site world wide web yahoo purchased geocities 1999 ten years later web host closed deleting seven million web pages great deal information lost many sites pages mirrored internet archive oocities.com databases yahoo go java-based phone application access yahoo services closed january 12 2010 yahoo 360° blogging/social networking beta service launched march 2005 yahoo closed july 13 2009 yahoo mash beta another social service closed one year operation prior leaving beta status yahoo photos shut september 20 2007 favor integration flickr yahoo tech website provided product information setup advice users yahoo launched website may 2006 march 11 2010 yahoo closed service redirected users yahoo technology news section discontinued services include farechase web audio search pets live kickstart briefcase yahoo teachers hotjobs acquired merged monster.com yahoo koprol indonesian geo-tagging website allowed users share information locations without use gps device koprol acquired yahoo year following inception 2011 1.5 million people utilizing website users also based singapore philippines vietnam however eighty percent users indonesian yahoo officially discontinued koprol august 28 2012 meaningfully drive revenue engagement yahoo mail classic announced shut april 2013 yahoo made notice starting june 2013 mail classic old versions yahoo mail shut users mail classic expected switch new yahoo mail use imap switch another email service addition april 2013 brought closure upcoming yahoo deals yahoo sms alerts yahoo kids yahoo mail messenger feature phone j2me early july 2013 yahoo announced scheduled closure task management service astrid yahoo acquired company may 2013 discontinue service august 5 2013 team astrid supplied customers data export tool recommended former competitors wunderlist sandglaz december 15 2010 one day yahoo announced layoffs 4 workers across portfolio mybloglog founder eric marcoullier posted slide yahoo employee twitter slide visible employee-only strategy webcast indicating changes yahoo offerings following services column sunset yahoo picks altavista mym alltheweb yahoo bookmarks yahoo buzz del.icio.us mybloglog merge column upcoming foxytunes yahoo events yahoo people search sideline fireeagle 11 properties listed yahoo interested developing feature sites within portal take place sunset merge vacancies including prior feature services new yahoo mail launched yahoo address book calendar notepad despite notepad listed feature service instead sunset merge 2010 yahoo since taken steps de-emphasize notepad example january 2013 notepad longer linked within new yahoo mail service although continued linked older classic version also starting mid- late january 2013 notepad longer searchable blog del.icio.us website released post chris yeh slide leaked yeh stated sunset n't necessarily mean yahoo closing site yeh explained possibilities—including del.icio.us leaving yahoo sale spinoff —were still considered imagine upsetting news coverage past 24 hours many speaking team disappointed way appeared press april 27 2011 yahoo sale del.icio.us avos announced yahoo buzz closed april 21 2011 without official announcement yahoo mybloglog discontinued yahoo may 24 2011 september 2013 yahoo transparency report said company received 29 thousand requests information users governments first six months 2013 12 thousand requests came united states october 2013 washington post reported u.s. national security agency intercepted communications yahoo data centers part program named muscular late january 2014 yahoo announced company blog detected coordinated effort hack possibly millions yahoo mail accounts company prompted users reset passwords elaborate scope possible breach citing ongoing federal investigation august 2015 researchers malwarebytes notified yahoo users getting hacked vulnerabilities flash according vulnerability could allow attackers install ransomware users computers lock files till customers pay criminals working comscore new york times found yahoo able collect far data users competitors web sites advertising network one measure average yahoo potential december 2007 build profile 2,500 records per month visitors yahoo retains search requests period 13 months however response european regulators yahoo obfuscates ip address users three months deleting last eight bits march 29 2012 yahoo announced would introduce track feature summer allowing users opt web-visit tracking customized advertisements however april 30 2014 yahoo announced would longer support track browser setting according 2008 article computerworld yahoo 2-petabyte specially built data warehouse uses analyze behavior half-billion web visitors per month processing 24 billion daily events contrast united states internal revenue service irs database united states taxpayers 150 terabytes september 2016 reported data least 500 million yahoo accounts stolen 2014 october 2016 reuters reported 2015 yahoo created software search customers e-mail request nsa fbi 2000 yahoo taken court france parties seeking prevent french citizens purchasing memorabilia relating nazi party march 2004 yahoo launched paid inclusion program whereby commercial websites guaranteed listings yahoo search engine yahoo discontinued program end 2009 yahoo criticized providing ads via yahoo ad network companies display spyware adware yahoo well search engines cooperated chinese government censoring search results april 2005 dissident shi tao sentenced 10 years prison providing state secrets foreign entities result identified ip address yahoo human rights organizations company general counsel disputed extent yahoo foreknowledge shi fate human rights groups also accuse yahoo aiding authorities arrest dissidents li zhi jiang lijun april 2017 yahoo sued failing uphold settlement agreements case yahoo pledged give support families arrested create relief fund persecuted expressing views online yahoo human rights trust 17.3 million allotted fund 13 million used townhouse washington dc purchases september 2003 dissident wang xiaoning convicted charges incitement subvert state power sentenced ten years prison yahoo hong kong connected wang group specific yahoo e-mail address xiaoning wife world organization human rights sued yahoo human rights laws behalf wang shi result media scrutiny relating internet child predators lack significant ad revenues yahoo user created chatrooms closed june 2005 may 25 2006 yahoo image search criticized bringing sexually explicit images even safesearch active august 2015 yahoo purchased 40 23 september 2013 owner alibaba group subject controversy allowing sale shark-derived products company banned sale shark fin products e-commerce platforms effective january 1 2009 november 30 2009 yahoo criticized electronic frontier foundation sending dmca notice whistle-blower website cryptome publicly posting details prices procedures obtaining private information pertaining yahoo subscribers concerns censorship private emails regarding website affiliated occupy wall street protests raised yahoo responded apology explained accident following media reports prism nsa massive electronic surveillance program june 2013 several technology companies identified participants including yahoo yahoo listed paradise papers set confidential electronic documents relating offshore investment leaked german newspaper süddeutsche zeitung scott ard prominent editorial director fired yahoo 2015 filed lawsuit accusing mayer leading sexist campaign purge male employees ard male employee stated mayer encouraged fostered use employee performance-rating system accommodate management subjective biases personal opinions detriment yahoo male employees suit ard claimed prior firing received fully satisfactory performance reviews since starting company 2011 head editorial programming yahoo home page however relieved role given woman recently hired megan lieberman editor-in-chief yahoo news lawsuit states liberman stated terminating ard received requested breakdown duties ard already provided information requested however reminded liberman done liberman excuse terminating ard pretext second sexual discrimination lawsuit filed separately gregory anderson fired 2014 alleging company performance management system arbitrary unfair making second sexism lawsuit yahoo mayer faced 2016 former chief operating officer henrique de castro departed company january 2014 mayer initially hired appointment ceo dismissed de castro previously worked google mckinsey company employed revive yahoo advertising business yahoo offers multi-lingual interface site available 20 languages official directory yahoo international sites world.yahoo.com company international sites wholly owned yahoo exception japan china sites yahoo holds 34.75 minority stake yahoo japan softbank holds 35.45 yahoo xtra new zealand yahoo 7 51 49 belongs telecom new zealand yahoo 7 australia 50–50 agreement yahoo seven network historically yahoo entered joint venture agreements softbank major european sites uk france germany well south korea japan november 2005 yahoo purchased minority interests softbank owned europe korea yahoo used hold 40 stake 35 voting power alibaba manages web portal china using yahoo brand name yahoo china yahoo usa direct control alibaba operates completely independent company september 18 2012 following years negotiations yahoo agreed sell 20 stake back alibaba 7.6 billion march 8 2011 yahoo launched romania local service years delay due financial crisis yahoo officially entered mena region acquired maktoob pan-regional arabic-language hosting social services online portal august 25 2009 since service pan-regional yahoo officially became yahoo maktoob region december 31 2012 yahoo korea shut services left country previous domain saying korean starting december 31 2012 yahoo korea ended go original yahoo yahoo information sooner message also disappear leaving abandoned empty search bar powered bing september 2 2013 yahoo china shut redirected taobao.com redirected yahoo singapore search page yahoo got first logo establishment 1994—it consists yahoo wordmark coloured black using times new roman font later changed march 1995 company changed name yahoo introduced another logo briefly changed elaborate text includes exclamation point end short-lived 5 months later august 1995 year yahoo changed logo became stylized yellow jumping figurine blue circle yahoo wordmark written logo also short-lived 4 months december 1995 january 1 1996 yahoo introduced much tweaking refining new logo quickly simplified text exclamation mark slight shadow behind text although gets coloured red also containing three icons side well becomes simple wordmark without graphics therefore create familiar logo existence since eventually logo used yahoo home page formerly consists red color black outline shadow june 2002 later becoming slightly changed new black shadows text replaces older gray color except gets introduced yahoo japan within following year gets still used today slight moderation 2013 see may 2009 yahoo overhauled theme redesign makes logo become recoloured purple without outline shadow purple logo first appeared headquarters yahoo messenger 1995 although get full effect november 12 2009 site received revamp entirely remove old red color 1996 change would apply several international yahoo home pages countries notably yahoo 7 australia still using red logo 2014 time purple logo comes new slogan ou used time occasion would time abbreviated august 7 2013 around midnight edt yahoo announced final version new logo would revealed september 5 2013 4:00 a.m. utc period leading unveiling new logo 30 days change campaign introduced whereby variation logo published every day 30 days following announcement new logo eventually launched accompanying video showed digital construction mayer published personalized description design process tumblr page mayer explains one weekend summer rolled sleeves dove trenches logo design team ... spent majority saturday sunday designing logo start finish ton fun weighing every minute detail knew wanted logo reflected yahoo – whimsical yet sophisticated modern fresh nod history human touch personal proud september 19 2013 yahoo launched new version yahoo personalized homepage redesign allows users tailor homepage widgets access features email accounts calendars flickr yahoo content internet content users also select theme packs represent artists polly apfelbaum alec monopoly bands empire sun mayer explained conference late september 2013 logo change result feedback external parties employees
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Web technology
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insteon insteon home automation domotics technology enables light switches lights thermostats leak sensors remote controls motion sensors electrically powered devices interoperate power lines radio frequency rf communications employs dual-mesh networking topology devices peers device independently transmits receives repeats messages like home automation systems associated internet things insteon-based products launched 2005 smartlabs company holds trademark insteon smartlabs subsidiary also named insteon created market technology according press release june 13 2017 smartlabs insteon technology acquired richmond capital partners rob lilleness universal electronics assuming role chairman ceo every message received insteon compatible device undergoes error detection correction retransmitted improve reliability devices retransmit message simultaneously message transmissions synchronous powerline frequency thus preserving integrity message strengthening signal powerline erasing rf dead zones insteon powerline messaging uses phase-shift keying insteon rf messaging uses frequency-shift keying message contains two-bit hops field initialized 3 originating node decremented time node network repeats message individual insteon messages also carry 14 bytes arbitrary user data custom applications insteon integrated dual-mesh formerly referred dual-band network combines wireless radio frequency rf building existing electrical wiring electrical wiring becomes backup transmission medium event rf/wireless interference conversely rf/wireless becomes backup transmission medium event powerline interference peer-to-peer network devices require network supervision thus allowing optional operation without central controllers routing tables insteon devices function without central controller additionally may managed central controller implement functions control via smartphones tablets control scheduling event handling problem reporting via email text messaging computer used central controller connecting insteon usb/serial powerlinc modem serves communication bridge computer insteon device network insteon network security maintained via linking control ensure users create links would allow control neighbors ’ insteon devices via encryption within extended insteon messages applications door locks security applications applications choose implement encryption insteon enforces linking control requiring users physical possession devices knowledge unique insteon ids order create links firmware insteon devices prohibits identifying devices unless user either physically presses button device installation process explicitly addresses device via central controller linking device sending insteon messages e.g. central controller requires knowledge address target insteon device addresses unique device assigned factory displayed printed label attached device users must physical access device read device address label manually enter prompted installation security insteon rf devices criticized def con presentation 2015 insteon devices configured applying sequence taps button presses pushbutton device establish direct device-to-device links alternatively central controller may used configure devices insteon device unique identifier code similar mac address technology allows directly linked devices manage identifiers older insteon chip sets manufactured smartlabs transmit receive respond repeat x10 power line messages thus enabling x10 networks interoperate insteon 2014 insteon released home automation system compatible touch-enabled metro interface devices appearing live tiles later added voice control via microsoft cortana 2015 voice control added via compatibility amazon echo year logitech announced harmony hub-based remote would support insteon devices deployed insteon hub also 2015 insteon announced initiative integrate google-owned nest learning thermostat insteon hub insteon one two launch partners apple homekit platform homekit-enabled insteon hub pro 2015 insteon announced support apple watch allowing watch owners control home insteon hub insteon second generation i2/rf replaces first generation i1/rf wireless insteon communications i1/rf i2/rf uses different frequencies operate independently currently one legacy product implements i1/rf signalinc rf signal enhances introduced may 2005 specifications i2/rf
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Distributed computing architecture
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mainframe sort merge sort/merge utility mainframe program sort records file specified order merge pre-sorted files sorted file copy selected records internally utilities use one standard sorting algorithms often proprietary fine-tuned code mainframes originally supplied limited main memory today standards amount data sorted frequently large unlike recent sort programs early sort/merge programs placed great emphasis efficient techniques sorting data secondary storage typically tape disk 1968 os/360 sort/merge program provided five different sequence distribution techniques could used depending number type devices available 1990 ibm introduced new merge algorithm called blockset dfsort successor os/360 sort/merge historical note blockset algorithm invented ibm systems engineer 1963 discovered ibm archives implemented 1990 sort/merge frequently used often commonly used application program mainframe shop generally consuming twenty percent processing power shop modern sort/merge programs also copy files select omit certain records summarize records remove duplicates reformat records append new data produce reports indeed sort/merge applications use wide range additional processing capabilities rather purely sorting merging records sort/merge product fast way performing input output functions quite number user exits supported may load modules i.e. member library object decks i.e. output assembler sort/merge application loading load modules linking object decks termed dynamic link editing dfsort exit specified required working storage datasets i.e. sortwk01 ... sortwknn may disk tape although blockset algorithm restricted disk working storage working storage datasets generally improves performance sort/merge important enough multiple companies selling sort/merge package ibm mainframes z/os z/vm z/vse operating systems major sort/merge packages companies also sell versions platforms unix linux windows historically alias sort used refer ibm sort/merge third party sort/merge programs i.e. syncsort casort also adopted sort alias product dfsort often referred program name iceman component ice original os/360 sort/merge program name ierrco00 component ier also alias sort
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Operating systems
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strict programming language strict programming language programming language employs strict programming paradigm allowing strict functions functions whose parameters must evaluated completely may called defined user non-strict programming language allows user define non-strict functions hence may allow lazy evaluation nearly programming languages common use today strict examples include c java prior java 8 perl version 5 python ruby common lisp ml examples non-strict languages haskell miranda clean languages whose ordinary functions strict provide macro system build non-strict functions include c c++ scheme non-strict languages non-strictness extends data constructors allows conceptually infinite data structures list prime numbers manipulated way ordinary finite data structures also allows use large finite data structures complete game tree chess non-strictness several disadvantages prevented widespread adoption strict programming languages often associated eager evaluation non-strict languages lazy evaluation evaluation strategies possible case terms eager programming language lazy programming language often used synonyms strict programming language non-strict programming language respectively many strict languages advantages non-strict functions obtained use macros thunks
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Programming language topics
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model-glue model-glue oo web framework based mvc design pattern goal simplify development oo coldfusion applications released apache software license 2.0 asl2.0 model-glue
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Programming language topics
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calendar windows calendar personal calendar application made microsoft microsoft windows offers synchronization calendars using microsoft exchange server outlook.com apple icloud calendar service google calendar supports popular icalendar format microsoft first included calendar application shortened app windows 1.0 included windows 3.1 replaced schedule+ windows workgroups windows nt 3.1 schedule+ later moved windows microsoft office suite windows include another calendar application windows calendar windows vista calendar created beta 2 windows vista version supports sharing subscribing publishing calendars webdav-enabled web servers network shares always supported .ics files subscription feature enables syncing google calendar interface matches windows vista mail two apps connected operating system default calendar renamed new version calendar text-heavy added windows 8 one many apps written run full-screen snapped part microsoft metro design language philosophy one three apps windows originate microsoft outlook two mail people apps structurally three apps one installed uninstalled user interface calendar windows 8 originally supported outlook.com exchange google calendar facebook calendars api changes facebook google calendars longer directly synced windows 8 like many microsoft apps introduced windows 8 many features hidden charms menu bottom screen triggered right clicking different calendars labeled different colors user microsoft account adds calendar account one computer windows 8 calendar account automatically added windows 8 computers user logged .ics files supported version mail preset server configurations outlook.com exchange google calendar icloud calendar users set use system theme choose custom accent color background image light/dark preference windows 10 calendar multi-window support viewing editing events different calendars labeled different colors events rearranged dragging dropping default interface month view users also use day week year views print views windows 10 app also uses flyout settings panel mini ribbon interface viewing pane day year calendar events show live tile like vista version important controls readily visible use icons match system accounts grouped relabeled folders edited within app .ics support added version time windows 10 anniversary update
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Operating systems
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high frequency internet protocol high frequency internet protocol hfip hf-ip usually associated automatic link establishment hf radio data communications hfip provides protocol layers enabling internet file transfer chat web email hfip commonly uses ionospheric propagation radio waves form wide area network span thousands kilometers hf transceivers hfip service typically run 20 150 watts portable mobile units approximately 2000 watts transmitter output high power base stations hfip servers stanag 5066 common hfip standard amateur radio hfip network called hflink uses automatic link establishment initiating data communications arq 8fsk frequency-shift keying psk phase-shift keying signals
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Internet protocols
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database activity monitoring database activity monitoring dam a.k.a enterprise database auditing real-time protection database security technology monitoring analyzing database activity operates independently database management system dbms rely form native dbms-resident auditing native logs trace transaction logs dam typically performed continuously real-time database activity monitoring prevention damp extension dam goes beyond monitoring alerting also block unauthorized activities dam helps businesses address regulatory compliance mandates like payment card industry data security standard pci dss health insurance portability accountability act hipaa sarbanes-oxley act sox u.s. government regulations nist 800-53 eu regulations dam also important technology protecting sensitive databases external attacks cybercriminals according 2009 verizon business ’ data breach investigations report—based data analyzed verizon business ’ caseload 90 confirmed breaches involving 285 million compromised records 2008—75 percent breached records came compromised database servers according gartner “ dam provides privileged user application access monitoring independent native database logging audit functions function compensating control privileged user separation-of-duties issues monitoring administrator activity technology also improves database security detecting unusual database read update activity application layer database event aggregation correlation reporting provide database audit capability without need enable native database audit functions become resource-intensive level auditing increased ” according survey independent oracle user group ioug “ organizations mechanisms place prevent database administrators privileged database users reading tampering sensitive information financial hr business applications still unable even detect breaches incidents. ” forrester refers category “ database auditing real-time protection ” privileged user monitoring monitoring privileged users superusers database administrators dbas systems administrators sysadmins developers help desk outsourced personnel – typically unfettered access corporate databases – essential protecting external internal threats privileged user monitoring includes auditing activities transactions identifying anomalous activities viewing sensitive data creating new accounts superuser privileges reconciling observed activities adding deleting tables authorized change requests since organizations already protected perimeter level indeed major concern lies need monitor protect privileged users high correlation therefore database security need protect insider threat complex task privileged users capable using sophisticated techniques attack database stored procedures triggers views obfuscated traffic attacks may difficult detect using traditional methods addition since targeted attacks frequently result attackers gaining privileged user credentials monitoring privileged activities also effective way identify compromised systems result auditors demanding monitoring privileged users security best practices well wide range regulations privileged user monitoring helps ensure • data privacy authorized applications users viewing sensitive data • data governance critical database structures values changed outside corporate change control procedures application activity monitoring primary purpose application activity monitoring provide greater level end-user accountability detect fraud abuses legitimate access occurs via enterprise applications rather via direct access database multi-tier enterprise applications oracle ebs peoplesoft jd edwards sap siebel systems business intelligence custom applications built standard middle-tier servers ibm websphere oracle weblogic server mask identity end-users database transaction level done optimization mechanism known “ connection pooling. ” using pooled connections application aggregates user traffic within database connections identified generic service account name application activity monitoring allows organizations associate specific database transactions particular application end-users order identify unauthorized suspicious activities end-user accountability often required data governance requirements sarbanes–oxley act new auditor guidance public company accounting oversight board sox compliance also increased emphasis anti-fraud controls cyberattack protection sql injection type attack used exploit bad coding practices applications use relational databases attacker uses application send sql statement composed application statement concatenated additional statement attacker introduces many application developers compose sql statements concatenating strings use prepared statement case application susceptible sql injection attack technique transforms application sql statement innocent sql call malicious call cause unauthorized access deletion data theft information one way dam prevent sql injection monitoring application activity generating baseline “ normal behavior ” identifying attack based divergence normal sql structures normal sequences alternative approaches monitor memory database database execution plan context sql statements visible based policy provide granular protection object level defined gartner “ dam tools use several data collection mechanisms server-based agent software in-line out-of-band network collectors aggregate data central location analysis report based behaviors violate security policies and/or signatures indicate behavioral anomalies dam demand driven primarily need privileged user monitoring address compliance-related audit findings threat-management requirements monitor database access enterprise dam requirements beginning broaden extending beyond basic functions capability detect malicious activity inappropriate unapproved database administrator dba access. ” advanced dam functions include enterprises also seeking functions including interception-based modern dam systems collect database able “ see ” communications database client database server dam systems find places view communication stream get requests responses without requiring participation database interception done multiple points database memory e.g sga network using network tap span port communication encrypted operating system level level database libraries unencrypted network traffic packet sniffing used advantage processing done host however main disadvantage local traffic sophisticated intra-database attacks detected capture local access network based vendors deploy probe runs host probe intercepts local access also intercept networked access case want use network gear case database communications encrypted however since agent processing — instead relays data dam appliance processing occurs — may impact network performance local traffic real-time session termination may slow interrupt unauthorized queries memory-based dam systems lightweight sensor attaches protected databases continuously polls system global area sga collect sql statements performed similar architecture previously used performance optimization products also used sga shared data structures latest versions technology lightweight sensor runs host attaches process os level inspect private data structures advantages approach significant log-based dam systems analyze extract information transaction logs e.g. redo logs systems use fact much data stored within redo logs scrape logs unfortunately information required redo logs example select statements systems augment data gather redo logs data collect native audit trails shown figure 3 systems hybrid true dam system fully independent dbms siem relies data generated database architectures usually imply overhead database server
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Databases
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disclosure barring service disclosure barring service dbs non-departmental public body home office united kingdom dbs enables organisations public private voluntary sectors make safer recruitment decisions identifying candidates may unsuitable certain work especially involving children vulnerable adults provides wider access criminal record information disclosure service england wales dbs formed 2012 merging functions criminal records bureau crb independent safeguarding authority isa protection freedoms act 2012 dbs started operating 1 december 2012 operates liverpool royal wootton bassett equivalent agencies disclosure scotland scotland access northern ireland northern ireland legal requirement uk regulated activity employers notify dbs person leaves changes job relation harmed someone offence person barred dbs work apply work group children adults barred also offence employer knowingly employ barred person regulated activity group barred organisation entitled ask exempted questions rehabilitation offenders act 1974 must register dbs registered dbs umbrella body request dbs check applicant applicant applies dbs application countersigned dbs registered organisation umbrella body applicant criminal record accessed police national computer pnc well checked appropriate lists people considered unsuitable work children vulnerable people maintained dbs formerly maintained independent safeguarding authority copy completed certificate sent applicant home address individual organisation safeguarding concerns regarding member staff make safeguarding referral dbs work multiple agencies assess whether individual barred working regulated activity children and/or vulnerable groups criminal records bureau established part v police act 1997 launched march 2002 following public concern safety children young people vulnerable adults found british police forces adequate capability resources routinely process fulfil large number criminal record checks requested timely fashion dedicated agency set administer function employers temporary staff agencies bemoaned time takes worker cleared dbs effort cut waiting times government allowed establishment adult first may 2002 department education began maintaining list individuals suitable work children list originally named list 99 later named isa children barred list maintained independent safeguarding authority finally dbs children barred list maintained disclosure barring service care standards act 2000 department health introduced adult version list 99 named 'pova first 26 july 2004 later renamed 'isa adult first finally 'dbs adult first adult first list 99 services allow registered bodies eligible check whether applicant appears dbs adults children barred list online checking system takes around two working days turn around check clean organisation may provisionally employ applicant subject increased level supervision return post full disclosure 17 june 2013 dbs update service launched intended improve ease applying criminal record checks create significant savings 1 february 2018 national audit office published investigation report highly critical dbs 2009 home office launched programme increase efficiency safeguarding services key aims programme reduce cost running disclosure service customers using new cheaper update service rather continuing use existing types disclosure certificates home office expected 2.8 million paying users using new update service 2017–18 market tested actual number users around one million according national audit office investigation modernisation programme running three half years late expected costs increased £229 million dbs currently negotiating contractor tata consultancy services delays modernisation programme update service expected increase ease frequency people checked thereby improving safeguarding home office dbs know many people prevented working children vulnerable adults use information process dbs provides criminal record data called dbs certificate dbs check previously crb check four levels dbs checks basic standard enhanced enhanced barred list checks basic disclosures see disclosure scotland dbs checks obtained members public directly available organisations professions offices employments work occupations listed exceptions order 1975 rehabilitation offenders act 1974 amended protection freedoms act 2012 17 june 2013 dbs update service launched intended improve ease applying criminal record checks create significant savings fee £13 year applicants may use certificate within sector disclosure level workforce details barring list checks volunteer status employer consent run dbs update check check existing certificate date check applicant identity certificate authenticity january 2018 basic dbs checks introduced disclose details cautions convictions deemend unspent rehabilitation offenders act 1974 basic dbs check disclose cautions reprimands warnings convictions deemed unspent according rehabilitation offenders act 1974 service provided dbs england wales disclosure scotland applicants scotland applications also done online employer reference dbs check could taken requirement standard enhanced check meant disclosure cautions convictions even spent however introduction basic check employers specify check required advertising job aim service reduce need unnecessary ineligible standard enhanced checks apply one responsible organisations list organisations websites apply check standard dbs check primarily positions high responsibility example accountancy security standard certificates reveal details convictions cautions reprimands warnings applicant received qualify filtering standard check may applied applicant job role specified police act 1997 amended protection freedoms act 2012 enhanced dbs checks positions involving certain activities teaching children treating adults also obtained certain professions example judicial appointments rspca officers enhanced check may applied applicant job role specified rehabilitation offenders act 1974 exception order 1975 police act 1997 addition information provided standard certificate enhanced certificate involves additional check police check information held file may relevant instance information led criminal conviction may indicate danger vulnerable groups police decide additional information added certificate using quality assurance framework involvement local police forces mean enhanced check may take significantly longer standard check completed includes enhanced certificate plus check appropriate dbs barred list two dbs barred lists one adults one children lists contain information whether applicant barred working either two groups individual may checked one barred lists job role classified regulated activity children and/or adults safeguarding vulnerable groups act 2006 roles might barred include work within outside people homes areas postal work would access personal documents dbs began filter certain criminal information dbs certificate met guidelines laid rehabilitation offenders act 1974 exceptions order 1975 amendment england wales order 2013 dbs work number standards criminal record checking service barring case accuracy performance service standards also agreed dbs police disclosure units crb due partner isa administering newly created vetting barring scheme 2009 suspended 2010 pending review following 2010 general election review published february 2011 making recommendations merger criminal records bureau independent safeguarding authority one new non-departmental public body disclosure barring service responsible barring individuals completing criminal record checks protection freedoms act 2012 dbs require registration details retained database procedures crb tightened following soham murders trial ian huntley former caretaker found guilty murdering two girls cambridgeshire primary school 2002 huntley suspected string offences including rape indecent assault burglary conviction murders riding uninsured unlicensed motorcycle burglary charge remained file january 2006 following controversies resulting cases staff hired schools full crb check carried department education skills stated employers obtain crb enhanced disclosure respect teachers recruit person placed school huntley hired november 2001 crb came force sociologist frank furedi stated crb checks provide cast-iron guarantee children safe particular adult use created atmosphere suspicion poisoning relationships generations many ordinary parents finding regarded potential child abusers restrictions imposed crb check process contributed shortage adult volunteers organizations girlguiding uk 2009 crb enhanced disclosure criticised including details minor contact individual police even formal action taken
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Databases
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egress software egress software technologies ltd uk-based software company provides range data security services designed protect shared information throughout lifecycle offering on-demand security organisations individuals sharing confidential information electronically egress develops security software including email encryption secure online collaboration document email classification email file archiving egress founded 2007 tony pepper neil larkins john goodyear major use egress switch software secure transfer emails documents non-secure email addresses october 2013 egress switch certified cesg desktop gateway email encryption security characteristics part commercial product assurance program makes switch suitable sharing il2 low-threat il3 data guidelines official official sensitive 2014 uk government security classifications policy certification lies national cyber security centre ncsc currently extended 20 december 2019 may 2014 egress switch encryption services became available procure via g-cloud 5 framework uk government program committed adoption cloud services across public sector g-cloud framework public sector organizations able procure following egress switch services switch secure email switch secure file transfer switch secure web form via number egress value added resellers also may 2014 egress switch secure email listed nato information assurance product catalogue provides 28 nato nations well civil military bodies directory information assurance products protection profiles packages use available procurement meet operational requirements
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Computer security
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google web server google web server gws proprietary web server software google uses web infrastructure gws used exclusively inside google ecosystem website hosting 2008 gws team lead bharat mediratta sometimes gws described one guarded component google infrastructure 2010 gws reported serving 13 web sites world may 2015 gws ranked fourth popular web server internet apache nginx microsoft iis powering estimated 7.95 active websites web page requests google pages provide gws without version number http header indication web server software used information regarding gws scarce blog post google chicago office 2011 google provided details gws
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Web technology
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key-recovery attack key-recovery attack adversary attempt recover cryptographic key encryption scheme historically cryptanalysis block ciphers focused key-recovery security sorts attacks weak guarantee since may necessary recover key obtain partial information message decrypt message entirely modern cryptography uses robust notions security recently indistinguishability adaptive chosen-ciphertext attack ind-cca2 security become golden standard security obvious key-recovery attack exhaustive key-search attack modern ciphers often key space size formula_1 greater making attacks infeasible current technology
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Computer security
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naive bayes spam filtering naive bayes classifiers popular statistical technique e-mail filtering typically use bag words features identify spam e-mail approach commonly used text classification naive bayes classifiers work correlating use tokens typically words sometimes things spam non-spam e-mails using bayes theorem calculate probability email spam naive bayes spam filtering baseline technique dealing spam tailor email needs individual users give low false positive spam detection rates generally acceptable users one oldest ways spam filtering roots 1990s bayesian algorithms used sort filter email 1996 although naive bayesian filters become popular later multiple programs released 1998 address growing problem unwanted email first scholarly publication bayesian spam filtering sahami et al 1998 work soon thereafter deployed commercial spam filters however 2002 paul graham greatly decreased false positive rate could used single spam filter variants basic technique implemented number research works commercial software products many modern mail clients implement bayesian spam filtering users also install separate email filtering programs server-side email filters dspam spamassassin spambayes bogofilter assp make use bayesian spam filtering techniques functionality sometimes embedded within mail server software crm114 oft cited bayesian filter intended use bayes filter production includes ″unigram″ feature reference particular words particular probabilities occurring spam email legitimate email instance email users frequently encounter word viagra spam email seldom see email filter n't know probabilities advance must first trained build train filter user must manually indicate whether new email spam words training email filter adjust probabilities word appear spam legitimate email database instance bayesian spam filters typically learned high spam probability words viagra refinance low spam probability words seen legitimate email names friends family members training word probabilities also known likelihood functions used compute probability email particular set words belongs either category word email contributes email spam probability interesting words contribution called posterior probability computed using bayes theorem email spam probability computed words email total exceeds certain threshold say 95 filter mark email spam spam filtering technique email marked spam automatically moved junk email folder even deleted outright software implement quarantine mechanisms define time frame user allowed review software decision initial training usually refined wrong judgements software identified false positives false negatives allows software dynamically adapt ever-evolving nature spam spam filters combine results bayesian spam filtering heuristics pre-defined rules contents looking message envelope etc resulting even higher filtering accuracy sometimes cost adaptiveness bayesian email filters utilize bayes theorem bayes theorem used several times context spam let suppose suspected message contains word replica people used receiving e-mail know message likely spam precisely proposal sell counterfeit copies well-known brands watches spam detection software however know facts compute probabilities formula used software determine derived bayes theorem statistics show current probability message spam 80 least however bayesian spam detection software makes assumption priori reason incoming message spam rather ham considers cases equal probabilities 50 filters use hypothesis said biased meaning prejudice regarding incoming email assumption permits simplifying general formula functionally equivalent asking percentage occurrences word replica appear spam messages quantity called spamicity spaminess word replica computed number formula_4 used formula approximated frequency messages containing replica messages identified spam learning phase similarly formula_6 approximated frequency messages containing replica messages identified ham learning phase approximations make sense set learned messages needs big representative enough also advisable learned set messages conforms 50 hypothesis repartition spam ham i.e datasets spam ham size course determining whether message spam ham based presence word replica error-prone bayesian spam software tries consider several words combine spamicities determine message overall probability spam bayesian spam filtering algorithms based formulas strictly valid probabilistic standpoint words present message independent events condition generally satisfied example natural languages like english probability finding adjective affected probability noun useful idealization especially since statistical correlations individual words usually known basis one derive following formula bayes theorem formula referenced paul graham 2002 article early commentators stated graham pulled formulas thin air graham actually referenced source included detailed explanation formula idealizations based spam filtering software based formula sometimes referred naive bayes classifier naive refers strong independence assumptions features result p typically compared given threshold decide whether message spam p lower threshold message considered likely ham otherwise considered likely spam usually p directly computed using formula due floating-point underflow instead p computed log domain rewriting original equation follows taking logs sides let formula_22 therefore hence alternate formula computing combined probability case word never met learning phase numerator denominator equal zero general formula spamicity formula software decide discard words information available generally words encountered times learning phase cause problem would error trust blindly information provide simple solution simply avoid taking unreliable words account well applying bayes theorem assuming classification spam ham emails containing given word replica random variable beta distribution programs decide use corrected probability corrected probability used instead spamicity combining formula formula_3 taken equal 0.5 avoid suspicious incoming email 3 good value meaning learned corpus must contain 3 messages word put confidence spamicity value default value formula extended case n equal zero spamicity defined evaluates case formula_32 neutral words like english equivalents languages ignored generally bayesian filtering filters simply ignore words spamicity next 0.5 contribute little good decision words taken consideration whose spamicity next 0.0 distinctive signs legitimate messages next 1.0 distinctive signs spam method example keep ten words examined message greatest absolute value |0.5 − pi software products take account fact given word appears several times examined message others n't software products use patterns sequences words instead isolated natural languages words example context window four words compute spamicity viagra good instead computing spamicities viagra good method gives sensitivity context eliminates bayesian noise better expense bigger database ways combining individual probabilities different words using naive approach methods differ assumptions make statistical properties input data different hypotheses result radically different formulas combining individual probabilities example assuming individual probabilities follow chi-squared distribution 2 n degrees freedom one could use formula c inverse chi-squared function individual probabilities combined techniques markovian discrimination one main advantages bayesian spam filtering trained per-user basis spam user receives often related online user activities example user may subscribed online newsletter user considers spam online newsletter likely contain words common newsletters name newsletter originating email address bayesian spam filter eventually assign higher probability based user specific patterns legitimate e-mails user receives tend different example corporate environment company name names clients customers mentioned often filter assign lower spam probability emails containing names word probabilities unique user evolve time corrective training whenever filter incorrectly classifies email result bayesian spam filtering accuracy training often superior pre-defined rules perform particularly well avoiding false positives legitimate email incorrectly classified spam example email contains word nigeria frequently used advance fee fraud spam pre-defined rules filter might reject outright bayesian filter would mark word nigeria probable spam word would take account important words usually indicate legitimate e-mail example name spouse may strongly indicate e-mail spam could overcome use word nigeria depending implementation bayesian spam filtering may susceptible bayesian poisoning technique used spammers attempt degrade effectiveness spam filters rely bayesian filtering spammer practicing bayesian poisoning send emails large amounts legitimate text gathered legitimate news literary sources spammer tactics include insertion random innocuous words normally associated spam thereby decreasing email spam score making likely slip past bayesian spam filter however example paul graham scheme significant probabilities used padding text non-spam-related words affect detection probability significantly words normally appear large quantities spam may also transformed spammers example « viagra » would replaced « viaagra » « v agra » spam message recipient message still read changed words words met rarely bayesian filter hinders learning process general rule spamming technique work well derived words end recognized filter like normal ones another technique used try defeat bayesian spam filters replace text pictures either directly included linked whole text message part replaced picture text drawn spam filter usually unable analyze picture would contain sensitive words like « viagra » however since many mail clients disable display linked pictures security reasons spammer sending links distant pictures might reach fewer targets also picture size bytes bigger equivalent text size spammer needs bandwidth send messages directly including pictures filters inclined decide message spam mostly graphical contents solution used google gmail email system perform ocr optical character recognition every mid large size image analyzing text inside bayesian filtering used widely identify spam email technique classify cluster almost sort data uses science medicine engineering one example general purpose classification program called autoclass originally used classify stars according spectral characteristics otherwise subtle notice
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Computer security
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rouge metric rouge recall-oriented understudy gisting evaluation set metrics software package used evaluating automatic summarization machine translation software natural language processing metrics compare automatically produced summary translation reference set references human-produced summary translation following five evaluation metrics available
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Computational linguistics
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novius os novius os content management system cms open source affero general public license v3 designed multi-channel internet create publish everywhere published novius company since 2011 novius os project launched company novius december 2011 publishing company since 2004 proprietary cms publi-nova decided embark open-source create new cms designed multi-channel internet novius os distributed gnu agpl v3 license uses latest web technologies based framework fuelphp side interface uses html5 jquery ui wijmo tinymce plugins like android versions named dessert major novius os versions listed alphabetical order named city first stable version os novius launched september 2012 version 0.1 renamed amsterdam posteriori version included expected standard elements cms publishing pages blog entries creating users managing permissions first notable features novius os specific business applications library multi-language system tabbed browsing makes multitasking cms version 0.2 launched february 2013 also known posteriori berlin version brings new cms applications forms management slide application create app allows developers easily quickly create novius os application database ui etc.. also notes emergence multi-context managing multiple sites multiple languages – single back office chiba version launched april 2013 tribute work done japanese community fully reflects novius os japanese version advanced rights system implemented planning publications cache cms also improved novius os contest bar camp exhibiting www2012 international gathering around future challenges web originally created robert cailliau co-founder tim berners-lee web week novius os presented several personalities giving first echo project novius os also present cms day 2012 2013 european rally around open source cms novius os available github runs lamp stack written php 5.3 mvc architecture uses framework fuelphp interfaces using html5 jquery ui wijmo library novius os built application system image object-oriented programming application may extended others customized extended additional features application different components launchers enhancers templates data catchers allow flow data applications also outside addition native applications provided novius os e.g collections web pages possible create specific business applications using wizard create app wizard allows quickly easily generate basis new application models fields group fields app desk launchers enhancers url etc..
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Programming language topics
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perry fellwock perry fellwock born 1947 former national security agency nsa analyst whistleblower revealed existence nsa worldwide covert surveillance network interview using pseudonym winslow peck ramparts 1971 time fellwock blew whistle echelon nsa nearly unknown organization among secretive us intelligence agencies fellwock revealed significantly larger budget central intelligence agency cia fellwock motivated daniel ellsberg release pentagon papers today fellwock acknowledged first nsa whistleblower echelon name popularly given signals intelligence sigint collection analysis network operated behalf five signatory states called five eyes fvey ukusa security agreement according information european parliament document existence global system interception private commercial communications echelon interception system echelon ostensibly created monitor military diplomatic communications soviet union eastern bloc allies cold war early 1960s fellwock revelations u.s. senate united states senate select committee study governmental operations respect intelligence activities church committee chaired frank church introduced successful legislation 1973 stop nsa spying american citizens speaking echelon frank church said ... hat capability time could turned around american people american would privacy left capability monitor everything telephone conversations telegrams n't matter would place hide government ever became tyranny dictator ever took charge country technological capacity intelligence community given government could enable impose total tyranny would way fight back careful effort combine together resistance government matter privately done within reach government know capability technology ... n't want see country ever go across bridge know capacity make tyranny total america must see agency agencies possess technology operate within law proper supervision never cross abyss abyss return church committee hearings congressional hearings abuses nixon administration committee chaired sam ervin helped lead passage foreign intelligence surveillance act fisa 1978 fisa prescribes procedures physical electronic surveillance collection foreign intelligence information foreign powers agents foreign powers may include american citizens permanent residents suspected espionage terrorism 1978 september 11 attacks law amended enabling president george w. bush expand warrantless surveillance american citizens
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Computer security
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middleware distributed applications middleware context distributed applications software provides services beyond provided operating system enable various components distributed system communicate manage data middleware supports simplifies complex distributed applications includes web servers application servers messaging similar tools support application development delivery middleware especially integral modern information technology based xml soap web services service-oriented architecture middleware often enables interoperability applications run different operating systems supplying services application exchange data standards-based way middleware sits middle application software may working different operating systems similar middle layer three-tier single system architecture except stretched across multiple systems applications examples include eai software telecommunications software transaction monitors messaging-and-queueing software distinction operating system middleware functionality extent arbitrary core kernel functionality provided operating system functionality previously provided separately sold middleware integrated operating systems typical example tcp/ip stack telecommunications nowadays included virtually every operating system software provides link separate software applications middleware sometimes called plumbing connects two applications passes data middleware allows data contained one database accessed another definition would fit enterprise application integration data integration software objectweb defines middleware software layer lies operating system applications side distributed computing system network middleware relatively new addition computing landscape gained popularity 1980s solution problem link newer applications older legacy systems although term use since 1968 also facilitated distributed processing connection multiple applications create larger application usually network middleware services provide functional set application programming interfaces allow application compared operating system network services middleware offers unique technological advantages business industry example traditional database systems usually deployed closed environments users access system via restricted network intranet e.g. enterprise ’ internal network phenomenal growth world wide web users access virtually database proper access rights anywhere world middleware addresses problem varying levels interoperability among different database structures middleware facilitates transparent access legacy database management systems dbmss applications via web server without regard database-specific characteristics businesses frequently use middleware applications link information departmental databases payroll sales accounting databases housed multiple geographic locations highly competitive healthcare community laboratories make extensive use middleware applications data mining laboratory information system lis backup combine systems hospital mergers middleware helps bridge gap separate liss newly formed healthcare network following hospital buyout middleware help software developers avoid write application programming interfaces api every control program serving independent programming interface applications future internet network operation traffic monitoring multi-domain scenarios using mediator tools middleware powerful help since allow operators searchers service providers supervise quality service analyse eventual failures telecommunication services finally e-commerce uses middleware assist handling rapid secure transactions many different types computer environments short middleware become critical element across broad range industries thanks ability bring together resources across dissimilar networks computing platforms 2004 members european broadcasting union ebu carried study middleware respect system integration broadcast environments involved system design engineering experts 10 major european broadcasters working 12-month period understand effect predominantly software-based products media production broadcasting system design techniques resulting reports tech 3300 tech 3300s published freely available ebu web site message-oriented middleware mom middleware transactions event notifications delivered disparate systems components way messages often via enterprise messaging system mom messages sent client collected stored acted upon client continues processing intelligent middleware imw provides real-time intelligence event management intelligent agents imw manages real-time processing high volume sensor signals turns signals intelligent actionable business information actionable information delivered end-user power dashboards individual users pushed systems within outside enterprise able support various heterogeneous types hardware software provides api interfacing external systems highly scalable distributed architecture embeds intelligence throughout network transform raw data systematically actionable relevant knowledge also packaged tools view manage operations build advanced network applications effectively content-centric middleware offers simple provider-consumer abstraction applications issue requests uniquely identified content without worrying obtained juno one example allows applications generate content requests associated high-level delivery requirements middleware adapts underlying delivery access content sources best suited matching requirements therefore similar publish/subscribe middleware well content-centric networking paradigm sources include additional classifications ibm red hat oracle corporation microsoft vendors provide middleware software vendors axway sap tibco informatica objective interface systems pervasive scaleout software webmethods specifically founded provide niche middleware solutions groups apache software foundation opensaf objectweb consortium ow2 oasis amqp encourage development open source middleware microsoft .net framework architecture essentially middleware typical middleware functions distributed various products inter-computer interaction industry standards open apis rand software licence solace provides middleware purpose-built hardware implementations may experience scale stormmq provides message oriented middleware service
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Distributed computing architecture
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national cyber security alliance national cyber security alliance ncsa 501c 3 non-profit founded 2001 public private partnership working department homeland security dhs private sector sponsors founding sponsors included symantec cisco systems microsoft saic emc mcafee nonprofit collaborators promote cyber security awareness home users small medium size businesses primary secondary education national cyber security awareness month project ncsa us government stop think connect campaign broader public cyber security awareness anti-phishing working group department homeland security also involved facebook became member ncsa 2011 cisco systems joined ncsa board directors 2016 cisco represented anthony grieco leads company trust strategy office
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Computer security
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