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service-oriented architecture implementation framework service-oriented architectures soa based notion software services high-level software components include web services implementation soa requires tools well run-time infrastructure software collectively referred service-oriented architecture implementation framework soaif soaif envisions comprehensive framework provides technology enterprise might need build run soa soaif includes design-time run-time capabilities well software functionality enterprise needs build operate soa including service-oriented vendors race provide possible solutions three different approaches emerging integrating disparate heterogeneous information systems enterprise implementation frameworks meet requirements loosely coupled coarse grained asynchronous services packaged enterprise applications perform well streamlining processes related standard tasks however performance rapidly deteriorates automating streamlining customized processes encompass multiple enterprise applications process difficult time-consuming expensive implement maintain soaif infrastructure addresses issue allowing definition process network topology spanning multiple enterprise boundaries accomplished via peer-to-peer messaging infrastructure distributed security mechanisms allow efficient data exchanges easy implementation enabling enterprise enforce security policies allows soaif increase operational efficiency across entire value chain soa works standard protocols existing packaged application integration solutions complex require significant implementation effort often including extensive manual coding deployment purposes soaif provides native support run time deployment services across network dramatically reduces overall costs application integration deployment automating time-consuming processes also allows extension integration across business boundaries traditional software development process translating requirements working distributed systems time-consuming difficult requiring several stages manual development deployment complex error-prone task effectively streamlined using higher-level component-based soaif soaif incorporates tools let processes developed using standards business process execution language bpel easily translated distributed high-level services easier develop manipulate debug services easily composed implementation-level data flows without user developer track complex middleware concepts topics queues implementation-level services run machine across network virtue built-in dynamic deployment support soaif provides combination service-oriented tools built-in support distributed debugging run-time tracing logging dynamic deployment allows soaif dramatically reduce time taken implement deliver working processes soaif general-purpose infrastructure platform lets developers business analysts create deploy manage change processes within across enterprise soaifs unique requirements tools infrastructure levels typically provided single current technology platform include addressing requirements soaif lets users quickly respond changes integrate operations efficiently regardless platform language database application enterprise processes usually distributed across multiple applications hardware/software systems processes also event-based sense subprocesses linked series events example depletion inventory manufacturer may lead event-trigger automatically generated propagated one suppliers replenish depleted inventory items current bpm solutions control processes centralized hub changes applications additions new applications require modifications centralized hub data exchanged applications needs traverse central hub type topology restriction inefficient inflexible leads bottlenecks overcome limitation framework tries integrate enterprise processes needs fully distributed across network within enterprise framework must also symmetric implies event-based infrastructure software tools need run machines within enterprise support data exchange messaging existing enterprise standards becomes essential soaif since content needs exchanged partners xml messages documents desired format since businesses want leverage existing infrastructures soaif needs easily support multiple standards soaif able offer high degree reliability platform support broad range processes span increasing number applications corporations partners eliminate single points failure maximize performance fully distributed architecture becomes essential soaif needs fully distributed maximum performance scalability distributed computing environment becomes necessary restrict scope interactions partners conduct corporate infrastructure becomes necessary allow customization interactions partner providing different security roles per-user per-service basis requires security model incorporates users web services general enterprise services ’ fully distributed fault-tolerant soaif infrastructure security model needs based existing standards tools support certificate authentication user services level soaif needs provide single dashboard visibility organization ’ entire distributed computing environment platform incorporate visual implementation-process-composition tools together infrastructure-level support instantly deploy modeled implementation-level processes across distributed enterprise network visual composition tools need service-oriented sense able directly manipulate higher-level coarse-grained implementation processes first-class objects also provide visual display programming constructs able map directly naturally deployable processes critical problem deploying distributed systems monitoring debugging concurrently running processes soaif provide native support tracing logging monitoring process service across distributed environment another challenge responding changing requirements soaif provide support incremental on-the-fly modification service-based flows implement processes among critical features expected soaif since lets analysts visually change instantly redeploy processes address dynamic requirements changes implemented within soaif abstracting concepts relating lower-level middleware tools applications levels users simply specify service replaced another running service often another machine soaif dynamically reroutes data new service setting new underlying middleware constructs topics queues example on-the-fly allows implementation changed without stopping current process much way hardware upgraded mainframe system without interruption operations essential elements soaif include design-time run-time infrastructure together service-oriented tools deploying distributed processes implementation flows core infrastructure soaif typically provided enterprise service bus esb addresses challenges composing deploying managing distributed service-based enterprise applications esb incorporates standards-based enterprise-class messaging backbone together enhanced systems connectivity using web services java ee .net framework standards one approach contributes optimal soa implementation use enterprise service bus esb provide infrastructural element distributed services network esb approach integration considers systems discrete distributed services connect via asynchronous message-oriented communications infrastructure message-oriented infrastructure allows loosely coupled document-oriented exchanges independent systems esbs provides critical infrastructure components simplify scale integration approaches esbs however provide required integration meet high-level business requirements esbs also provide guarantees loose coupling coarse granularity meet evolving service-oriented needs implementing esbs meet soa requirements require addition extra functionality compose fine-grained atomic services coarse-grained business services provide policy-driven managed secure service interactions esb links individual enterprises together extended process efficiency across supply chain allowing become flexible adaptable rapidly changing requirements esb lets enterprise leverage previous investments supporting deployment processes existing software hardware infrastructure core underlying infrastructure soaif esbs offer several unique business technical advantages business process management bpm considers systems assets activities tasks participate well-coordinated centrally orchestrated business processes traditionally challenge bpm possible construct processes achieve integration goals enterprises typically use bpm tools design time modeling processes used processes rarely processes actually environment bpm solutions craft orchestrated processes composed fine-grained services ’ contain runtime environment necessary loosely coupled asynchronous service interactions least bpm solution must used conjunction loosely coupled integration approach make business processes runtime activities coordinate integration thus bpm solutions sufficient meet soa requirements service-oriented integration soi approach uses architectural guiding principles services orientation construct ecosystem services business users dynamically combine compose higher-level processes meet continuously evolving changing business requirements soi approaches transcend brittle tightly coupled eai business-to-business integration approaches mandating separation consumer service producer service thus enforcing critical aspect loose coupling required allow integration scenario evolve automatically meet business requirements soi provides guidance build right services meet current business requirements provide means execute services effective scalable manner guarantee long-running interactions esbs implement standardized interfaces communication connectivity transformation security portability supported standards include modern esb implementations typically support development multiple languages combined inherently portable esb infrastructure makes esb true multi-language multiplatform enterprise backbone ideal foundation soaif several modern esbs implement symmetric distributed architecture peer-messaging servers run multiple nodes enterprise network providing highly scalable reliable distributed messaging platform single point failure modern esb architectures combine benefits centralized control distributed parallel data flow giving application developers ultimate flexibility defining network topology choice route data directly optimally services ensuring data flowing services always traverse central point network optimizes peer-to-peer network performance instance one process requires data exchanges new york boston well san francisco los angeles two flows data ’ necessarily traverse messaging hub located chicago often case enterprise cross-enterprise deployments instead efficiency dictates setting direct data flow connections peer nodes network service-oriented tools enable composition distributed applications one services web services general enterprise services typically runs separate process services may written language communicate via xml messages allows service-oriented tools within soaif compose flexible easy-to-modify systems service-oriented processes deployed soaif composed coarse-grained web services ideally suited easy change replacement abstracting details message routing service implementations service-oriented tools decouple enable running processes modified on-the-fly simple service replacement addition tools framework within soaif supports run-time deployment services allowing changed processes deployed instantly across network experience significantly reduces solution deployment costs compared traditional broker-based solutions esb defines comprehensive security system giving administrators full control services executed esbs provide ability set several security attributes service provide administrative tools configure security settings distributed esb infrastructure across network esbs include native service-level support run-time monitoring tracing logging services monitored instantly using visual tools within soaif trace levels dynamically changed within existing services running across network debug logs routed software tools node features greatly simplify development deployment debugging distributed applications running across soaif
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Web technology
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security account manager security account manager sam often security accounts manager database file windows xp windows vista windows 7 8.1 10 stores users passwords used authenticate local remote users beginning windows 2000 sp4 active directory authenticates remote users sam uses cryptographic measures prevent unauthenticated users accessing system user passwords stored hashed format registry hive either lm hash ntlm hash file found codice_1 mounted codice_2 attempt improve security sam database offline software cracking microsoft introduced syskey function windows nt 4.0 syskey enabled on-disk copy sam file partially encrypted password hash values local accounts stored sam encrypted key usually also referred syskey enabled running codice_3 program since hash function one-way provides measure security storage passwords case online attacks possible simply copy sam file another location sam file moved copied windows running since windows kernel obtains keeps exclusive filesystem lock sam file release lock operating system shut blue screen death exception thrown however in-memory copy contents sam dumped using various techniques including pwdump making password hashes available offline brute-force attack lm hash compromised protocol replaced ntlm hash versions windows configured disable creation storage valid lm hashes user changes password windows vista later versions windows disable lm hash default note enabling setting immediately clear lm hash values sam rather enables additional check password change operations instead store dummy value location sam database lm hash otherwise stored dummy value relationship user password value used user accounts windows nt 3.51 nt 4.0 2000 attack devised bypass local authentication system sam file deleted hard drive e.g mounting windows os volume alternate operating system attacker could log account password flaw corrected windows xp shows error message shuts computer however exist software utilities aforementioned methodology using either emulated virtual drive boot disk usually unix/linux another copy windows like windows preinstallation environment based environment mount local drive housing active ntfs partition using programmed software routines function calls within assigned memory stacks isolate sam file windows nt system installation directory structure default codice_1 depending particular software utility used removes password hashes stored user accounts entirety cases modify user account passwords directly environment software highly pragmatic beneficial use password clearing account recovering utility individuals lost forgotten windows account passwords well possible use malicious software security bypassing utility essentially granting user enough ability experience familiarity cracking utility software security routines windows nt kernel well offline immediate local access target computer capability entirely bypass remove windows account passwords potential target computer recently microsoft released utility called locksmith part msdart msdart freely available end-users however
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Operating systems
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ia-32 execution layer ia-32 execution layer ia-32 el software emulator form software driver improves performance 32-bit applications running 64-bit intel itanium-based systems particularly running linux windows server 2003 included windows 2003 sp1 later linux distributions itanium ia-32 el bypasses slow x86 hardware emulation available pre-montecito itanium models ia-32 el used two-phase later three-phase approach initially quickly translated every piece code basic block level adding certain instrumentation detecting hot code hot code dynamically optimized super-block level optimized translated code replaced cold code fly later interpretation engine added allowed avoid altogether translation code executed times cold non-optimized translation became thus second phase hot optimized translation became third phase ia-32 execution layer supported self-modified code could even optimize quite well part software lgpl part intel proprietary license
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Operating systems
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list abstractions computer science list contains abstractions used computer programming
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Programming language topics
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niso circulation interchange protocol niso circulation interchange protocol ncip protocol limited exchange messages among computer-based applications enable perform functions necessary lend borrow items provide controlled access electronic resources facilitate cooperative management functions released may 2001 approved october 17 2002 ansi/niso z39.83-2002 ncip niso draft standard trial use protocol defines repertoire messages associated rules syntax semantics use applications perform functions necessary lend items provide controlled access electronic resources facilitate co-operative management functions intended address conditions application applications initiate lending items control access must acquire transmit information user items and/or access essential successful conclusion function
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Internet protocols
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woody poco player controls old wooden figure named poco hero lived harmony humans many years poco journey find fairy teaches people get back friendly wooden dolls enemies encountered game strange creatures bothersome old men player attacks using fists players steal items store stealing player appearance changed resemble thief hotels pawn shops longer admit player remainder game theft taken place player equip one hand weapon passive tool lamp dark areas player buy gear sleep hotels gamble steal bribe non-player characters player needs eat prevent hunger recharging health based food level features in-game clock day/night cycles four seasons color changes reflect time day season
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Computer architecture
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keith b. alexander keith brian alexander born december 2 1951 retired four-star general united states army served director national security agency dirnsa chief central security service chcss commander united states cyber command previously served deputy chief staff g-2 united states army 2003 2005 assumed positions director national security agency chief central security service august 1 2005 additional duties commander united states cyber command may 21 2010 alexander announced retirement october 16 2013 retirement date march 28 2014 may 2014 alexander founded ironnet cybersecurity private-sector cybersecurity firm based fulton maryland alexander born december 2 1951 syracuse new york son charlotte l. colvin donald henry alexander raised onondaga hill new york suburb syracuse paperboy post-standard attended westhill senior high school ran track alexander attended united states military academy west point class three future four-star generals david petraeus martin dempsey walter l. sharp graduation april 1974 alexander married deborah lynn douglas classmate high school grew near family onondaga hill four daughters alexander entered active duty west point intending serve five years alexander military education includes armor officer basic course military intelligence officer advanced course united states army command general staff college national war college alexander worked signals intelligence number secret national security agency bases united states germany earned master science business administration 1978 boston university master science systems technology electronic warfare master science physics 1983 naval postgraduate school master science national security strategy national defense university rose quickly military ranks due expertise advanced technology competency administration alexander assignments include deputy chief staff dcs g-2 headquarters department army washington d.c. 2003 2005 commanding general united states army intelligence security command fort belvoir virginia 2001 2003 director intelligence j-2 united states central command macdill air force base florida 1998 2001 deputy director intelligence j-2 joint chiefs staff 1997 1998 alexander served variety command assignments germany united states include tours commander border field office 511th mi battalion 66th mi group 336th army security agency company 525th mi group 204th mi battalion 525th military intelligence brigade additionally alexander held key staff assignments deputy director operations officer executive officer 522nd mi battalion 2nd armored division g-2 1st armored division germany gulf war operation desert shield operation desert storm saudi arabia also served afghanistan peace keeping mission army deputy chief staff intelligence alexander headed army intelligence security command 2001 charge 10,700 spies eavesdroppers worldwide words james bamford wrote biography wired alexander rest american intelligence community suffered devastating defeat surprised attacks 9/11 alexander reaction order intercept operators begin monitor email phone calls american citizens unrelated terrorist threats including personal calls journalists 2003 alexander named deputy chief staff intelligence united states army 205th mi brigade involved abu ghraib torture prisoner abuse baghdad iraq part v corps us alexander command testifying senate armed services committee alexander called abuse totally reprehensible described perpetrators group undisciplined mp soldiers mary louise kelly interviewed later npr said outside chain command oversaw interrogations iraq alexander able survive reputation intact 2004 along alberto gonzales others george w. bush administration alexander presented memorandum sought justify treatment deemed unlawful enemy combatants june 2013 national security agency revealed whistle-blower edward snowden secretly spying american people fisa-approved surveillance programs prism xkeyscore october 16 2013 publicly announced alexander deputy chris inglis leaving nsa april 13 2016 president obama announced alexander member commission enhancing national cybersecurity alexander became three-star general 2005 donald rumsfeld secretary defense named director national security agency according bamford alexander deceived house intelligence committee agency involved nsa warrantless wiretapping also period alexander oversaw implementation real time regional gateway iraq nsa data collection program consisted gathering electronic communication storing searching otherwise analyzing former senior u.s. intelligence agent described alexander program rather look single needle haystack approach 'let collect whole haystack collect tag store ... whatever want go searching 2008 regional gateway effective providing information iraqi insurgents eluded less comprehensive techniques collect strategy introduced keith alexander believed glenn greenwald guardian model comprehensive world-wide mass archiving communications nsa become engaged 2013 according siobhan gorman wall street journal government official stated alexander offered resign 2013 global surveillance disclosures first broke june 2013 obama administration asked alexander confirmed united states senate appointment rank general may 7 2010 officially promoted rank ceremony may 21 2010 alexander assumed command united states cyber command ceremony made four-star general alexander delivered keynote address black hat usa july 2013 organizers describe alexander advocate battlefield visualization 'data fusion useful intelligence provided quote alexander gave comprehensive interview career spanned 17,000 words 8 may 2014 australian financial review journalist christopher joye subsequently cited edward snowden full transcript covers nsa operations snowden metadata debates encryption controversies chinese russian spying published online snowden alexander told joye suspect russian intelligence driving understand well 're going let things benefit russia stand help improve snowden credibility wired magazine said afr interview alexander showed defending stock-piling zero-days wall street journal media focused alexander claims snowden working russian intelligence july 2012 response question jeff moss founder def con hacker convention ... nsa really keep file everyone alexander replied n't absolutely anybody would tell 're keeping files dossiers american people knows true march 2012 response questions representative hank johnson united states congress hearing allegations made former nsa officials nsa engages collection voice digital information u.s. citizens alexander said despite allegations james bashford wired magazine nsa collect data july 9 2012 asked member press large data center utah used store data american citizens alexander stated ca n't go details utah data center n't hold data u.s citizens def con 2012 alexander keynote speaker question answers session response question nsa really keep file everyone see mine alexander replied job foreign intelligence would want weave story millions hundreds millions dossiers people absolutely false ... perspective absolute nonsense june 6 2013 day snowden revelations then-director national intelligence james clapper released statement admitting nsa collects telephony metadata millions americans telephone calls metadata information included originating terminating telephone number telephone calling card number imei number time duration phone calls andy greenberg forbes said nsa officials including alexander years 2012 2013 publicly denied—often carefully hedged words—participating kind snooping americans since become nearly undeniable september 2013 alexander asked senator mark udall goal nsa collect phone records americans alexander replied alexander announced retirement october 16 2013 retirement date march 28 2014 replacement u.s. navy vice admiral michael s. rogers may 2014 retirement nsa alexander founded ironnet cybersecurity ironnet provides cybersecurity coverage private-sector companies using irondefense program team cybersecurity analysts experts company headquartered fulton maryland offices frederick maryland mclean virginia new york city october 2015 ironnet received 32.5 million funding trident capital cybersecurity forgepoint capital kleiner perkins caufield byers series investment may 2018 ironnet raised additional 78 million round led c5 capital alongside existing investors forgepoint capital kleiner perkins caufield byers alexander maintains role ceo ironnet today alexander inducted nps hall fame 2013 fall 2014 alexander told public forum someone else claimed 9,000 irs refund name thieves used identity apply 20 credit cards
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Computer security
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win32 thread information block computing win32 thread information block tib data structure win32 x86 stores information currently running thread structure also known thread environment block teb tib officially undocumented windows 9x windows nt series ddk includes struct nt_tib winnt.h documents subsystem independent part wine includes header declarations extended subsystem-specific part tib yet many win32 programs use undocumented fields effectively part api first field particular directly referenced code produced microsoft compiler tib used get lot information process without calling win32 api examples include emulating getlasterror getversion pointer peb one obtain access import tables iat process startup arguments image name etc accessed fs segment register operating 32 bits gs 64 bits fs 32-bit gs 64-bit maps tib embedded data block known tdb thread data base tib contains thread-specific exception handling chain pointer tls thread local storage thread local storage c local storage tib current thread accessed offset segment register fs x86 gs x64 common access tib fields offset fs 0 rather first getting linear self-referencing pointer stored fs 0x18 pointer used pointer arithmetics cast struct pointer example c inlined-assembly 32-bit x86
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Operating systems
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bitflu bitflu open-source bittorrent client adrian ulrich available unix-like systems written perl bitflu received good reviews open-source software sites blogs praising lightweight feature-complete even bitflu seems largely unknown reportedly commanding 0.000025 total bittorrent traffic according one reviewer could due non-automated relatively elaborated install procedure could putting majority users ca n't anything complicated click-next-until-finish install
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Internet protocols
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polyinstantiation polyinstantiation computer science concept type class database row otherwise instantiated multiple independent instances objects copies may also indicate case database polyinstantiation two different instances name identifier primary key operating system security polyinstantiation concept creating user process specific view shared resource i.e process affect process b writing malicious code shared resource unix directory /tmp polyinstantiation shared resources similar goals process isolation application virtual memory processes assigned isolated virtual address space prevent process writing memory space process b databases polyinstantiation database-related sql structured query language terminology allows relation contain multiple rows primary key multiple instances distinguished security levels occurs mandatory policy depending security level established one record contains sensitive information one user see record information depending his/her level confidentiality previously dictated company policy consider following table primary key name λ x security level although useful security standpoint polyinstantiation raises several problems cryptography polyinstantiation existence cryptographic key one secure physical location
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Computer security
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spam reader spam reader free anti-spam add-on microsoft outlook produced shareware license program uses content filtering based bayesian spam filtering algorithm whitelist blacklist techniques additional spam signs like embedded images internet attached executed files junk text program supports pop3 imap http microsoft exchange microsoft exchange program works default mailbox also http mailboxes limited supported outlook program add-on automatically integrates outlook workspace white list program uses white list technology guarantees messages user regular correspondents blocked spam even contents look like spam white list may include names addresses entire domains list automatically created first program execution scanning user address book contacts folder saved sent messages program automatically updates white list adding information recipients outgoing messages black list program contains contacts email addresses receive spam unwanted messages spam reader consider message sender list spam black list items may names email addresses entire domains contain wildcards safe recipients list list contains email address user ca n't receive spam messages sent addresses always treated legitimate messages bayesian spam filter spam filtering based bayesian approach using algorithm program determines score corresponding probability particular message spam score used decide whether message spam regular updates self-training option make filtering algorithm flexible custom filter adjust filtering rules user personal needs possible define custom spam not-spam dictionaries message contains word phrase spam dictionary considered spam messages containing word phrases not-spam dictionary directed inbox without anti-spam filtering program uses special algorithm interaction microsoft outlook rules algorithm allows user set order executing outlook rules spam reader prevents chaotic movement spam messages spam folder destination folder outlook rule case spam messages match rule
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Computer security
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anti-spam smtp proxy anti-spam smtp proxy assp open-source perl based platform-independent transparent smtp proxy server assp features
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Computer security
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mms architecture mms architecture set standards used multimedia messaging service mobile networks standards prepared 3gpp standard consists number interfaces components found mobile network mm1 interface mobile station ms mmsc mm1 used following actions mm1 interface based wap protocol includes pap notifications transformed sms wap gateway notifications mm2 interface mms relay mms-r mms storage database two components mmsc platform mm3 interface mmsc external servers email server sms centers smsc interface typically uses tcp/ip based protocols e.g simple mail transfer protocol smtp generally responsibility mmsc transformation mms multi-part binary data mime format email direction mm3 used following actions mm4 interface used exchange messages two different mmscs mmscs generally located two distinct mobile networks interface also known mms interface wireless application protocol wap open mobile alliance oma standards mm5 interface mmsc network elements like hlr domain name server communication mm5 interface generally fetch routing information mm5 defined 3gpp ts 23.140 simple reference mobile application part mm7 interface mmsc value-added service provider vasp mm7 interface used send mms 3rd party providers e.g. bank sending statement advertiser sending publicity based soap attachments using http transport protocol http request shall post message mime encapsulates soap envelope encoded attachments soap envelope xml tags mm7 protocol data mm11 specified oma sti standard transcoding interface 1.0 mm11 designed ensure compatibility transcoders mmscs integration transcoder without using mm11 possible implementing transcoder proxy server placing transcoder mm1 interface user equipment mmsc messages transparently transcoded possible disadvantage implementation transcoders typically licensed transactions per second transactions sent transcoder rather marked allow adaptations
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Internet protocols
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david h. munro david herbert munro born april 29 1955 oakland california physicist lawrence livermore national laboratory llnl created programming language yorick well scientific graphics library gist munro earned b.s caltech 1976 ph.d. massachusetts institute technology 1980 joined llnl 1980 primarily focused research laser fusion received excellence plasma physics award american physical society 1995
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Programming language topics
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column-oriented dbms column-oriented dbms columnar database management system database management system dbms stores data tables column rather row practical use column store versus row store differs little relational dbms world columnar row databases use traditional database query languages like sql load data perform queries row columnar databases become backbone system serve data common extract transform load etl data visualization tools however storing data columns rather rows database precisely access data needs answer query rather scanning discarding unwanted data rows query performance increased certain workloads relational database management system provides data represents two-dimensional table columns rows example database might table simple table includes employee identifier empid name fields lastname firstname salary salary two-dimensional format abstraction actual implementation storage hardware requires data serialized one form another expensive operations involving hard disks seeks order improve overall performance related data stored fashion minimize number seeks known locality reference basic concept appears number different contexts hard disks organized series blocks fixed size typically enough store several rows table organizing table data rows fit within blocks grouping related rows onto sequential blocks number blocks need read sought minimized many cases along number seeks survey pinnecke et al covers techniques column-/row hybridization 2017 common method storing table serialize row data like data inserted table assigned internal id codice_1 used internally system refer data case records sequential codice_1s independent user-assigned codice_3 example dbms uses short integers store codice_1s practice larger numbers 64-bit 128-bit normally used row-based systems designed efficiently return data entire row record operations possible matches common use-case system attempting retrieve information particular object say contact information user rolodex system product information online shopping system storing record data single block disk along related records system quickly retrieve records minimum disk operations row-based systems efficient performing set-wide operations whole table opposed small number specific records instance order find records example table salaries 40,000 50,000 dbms would fully scan entire table looking matching records example table shown likely fit single disk block table even hundred rows would multiple disk operations would needed retrieve data examine improve performance sorts operations common generally point using dbms dbmss support use database indexes store values set columns along codice_1 pointers back original table index salary column would look something like store single pieces data rather entire rows indexes generally much smaller main table stores scanning smaller set data reduces number disk operations index heavily used dramatically reduce time common operations however maintaining indexes adds overhead system especially new data written database records need stored main table attached indexes updated well main reason indexes dramatically improve performance large datasets database indexes one columns typically sorted value makes range queries operations like find records salaries 40,000 50,000 example fast lower time-complexity number row-oriented databases designed fit entirely ram in-memory database systems depend disk operations equal-time access entire dataset reduces need indexes requires amount operations fully scan original data complete index typical aggregation purposes systems may therefore simpler smaller manage databases fit memory column-oriented database serializes values column together values next column example table data would stored fashion layout one columns closely matches structure index row-based system may cause confusion lead mistaken belief column-oriented store really row-store index every column however mapping data differs dramatically row-oriented indexed system primary key rowid mapped indexed data column-oriented system primary key data mapped rowids may seem subtle difference seen common modification store whether column-oriented system efficient operation depends heavily workload automated operations retrieve data given object entire row slower row-based system retrieve row single disk read whereas numerous disk operations collect data multiple columns required columnar database however whole-row operations generally rare majority cases limited subset data retrieved rolodex application instance collecting first last names many rows build list contacts far common reading data single address even true writing data database especially data tends sparse many optional columns reason column stores demonstrated excellent real-world performance spite many theoretical disadvantages partitioning indexing caching views olap cubes transactional systems write-ahead logging multiversion concurrency control dramatically affect physical organization either system said online transaction processing oltp -focused rdbms systems row-oriented online analytical processing olap -focused systems balance row-oriented column-oriented comparisons row-oriented column-oriented databases typically concerned efficiency hard-disk access given workload seek time incredibly long compared bottlenecks computers example typical serial ata sata hard drive average seek time 16 22 milliseconds dram access intel core i7 processor takes average 60 nanoseconds nearly 400,000 times fast clearly disk access major bottleneck handling big data columnar databases boost performance reducing amount data needs read disk efficiently compressing similar columnar data reading data necessary answer query practice columnar databases well-suited olap-like workloads e.g. data warehouses typically involve highly complex queries data possibly petabytes however work must done write data columnar database transactions inserts must separated columns compressed stored making less suited oltp workloads row-oriented databases well-suited oltp-like workloads heavily loaded interactive transactions example retrieving data single row efficient data located single location minimizing disk seeks row-oriented architectures however column-oriented systems developed hybrids capable oltp olap operations oltp constraints column-oriented systems face mediated using amongst qualities in-memory data storage column-oriented systems suitable olap oltp roles effectively reduce total data footprint removing need separate systems column data uniform type therefore opportunities storage size optimizations available column-oriented data available row-oriented data example many popular modern compression schemes lzw run-length encoding make use similarity adjacent data compress missing values repeated values common clinical data represented two-bit marker techniques may used row-oriented data typical implementation achieve less effective results improve compression sorting rows also help example using bitmap indexes sorting improve compression order magnitude maximize compression benefits lexicographical order respect run-length encoding best use low-cardinality columns first sort keys example given table columns sex age name would best sort first value sex cardinality two age cardinality 150 name columnar compression achieves reduction disk space expense efficiency retrieval greater adjacent compression achieved difficult random-access may become data might need uncompressed read therefore column-oriented architectures sometimes enriched additional mechanisms aimed minimizing need access compressed data column stores transposed files implemented early days dbms development taxir first application column-oriented database storage system focus information-retrieval biology 1969 clinical data patient records many attributes could analyzed processed 1975 time-oriented database system tods statistics canada implemented rapid system 1976 used processing retrieval canadian census population housing well several statistical applications rapid shared statistical organizations throughout world used widely 1980s continued used statistics canada 1990s another column-oriented database scss later column-oriented database packages included since 2004 additional open source commercial implementations monetdb released open-source license september 30 2004 followed closely defunct c-store c-store university project eventually team member michael stonebraker staying led vertica co-founded 2005 monetdb-related x100 project evolved vectorwise druid column-oriented data store open-sourced late 2012 used numerous organizations
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Databases
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sim.js sim.js event-based discrete-event simulation library based standard javascript library written order enable simulation within standard browsers utilizing web technology sim.js supports entities resources facility buffers stores communication via timers events messages statistics data series time series population statistics sim.js distribution contains tutorials in-depth documentation large number examples sim.js released open source software lgpl license first version released january 2011 several examples bundled library download trafficlight simulation standard simulation problem may simulated within example
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Programming language topics
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pure data pure data pd visual programming language developed miller puckette 1990s creating interactive computer music multimedia works puckette main author program pd open-source project large developer base working new extensions released license similar bsd license runs gnu/linux ios android windows ports exist freebsd irix pd similar scope design puckette original max program developed ircam degree interoperable max/msp commercial predecessor max language may collectively discussed members patcher family languages addition graphics environment multimedia gem external externals designed work like pure data packet pidip linux framestein windows gridflow n-dimensional matrix processing linux windows possible create manipulate video opengl graphics images etc. realtime extensive possibilities interactivity audio external sensors etc pd natively designed enable live collaboration across networks internet allowing musicians connected via lan even disparate parts globe create music together real time pd uses fudi networking protocol pure data max examples dataflow programming languages languages functions objects linked patched together graphical environment models flow control audio unlike original version max however pd always designed control-rate audio processing host central processing unit cpu rather offloading sound synthesis signal processing digital signal processor dsp board ariel ispw used max/fts pd code forms basis david zicarelli msp extensions max language software audio processing like max pd modular code base externals objects used building blocks programs written software makes program arbitrarily extensible public api encourages developers add control audio routines c programming language help externals python scheme lua tcl many others however pd also programming language modular reusable units code written natively pd called patches abstractions used standalone programs freely shared among pd user community programming skill required use pd effectively like max pd dataflow programming language dsp software two primary rates data passed sample audio rate usually 44,100 samples per second control rate 1 block per 64 samples control messages audio signals generally flow top screen bottom objects connected via inlets outlets pd supports four basic types text entities messages objects atoms comments atoms basic unit data pd consist either float symbol pointer data structure pd numbers stored 32-bit floats messages composed one atoms provide instructions objects special type message null content called bang used initiate events push data flow much like pushing button pd native objects range basic mathematical logical bitwise operators found every programming language general specialized audio-rate dsp functions designated tilde symbol wavetable oscillators fast fourier transform fft~ range standard filters data loaded file read audio board midi via open sound control osc firewire usb network connection generated fly stored tables read back used audio signals control data one key innovations pd predecessors introduction graphical data structures used large variety ways composing musical scores sequencing events creating visuals accompany pd patches even extending pd gui living pd name data structures enable pd users create arbitrarily complex static well dynamic animated graphical representations musical data much like c structs pd structs composed combination floats symbols array data used parameters describe visual appearance data structure conversely control messages audio signals pd patch puckette words though powerful language pd certain limitations implementation object-oriented concepts example difficult create massively parallel processes instantiating manipulating large lists objects spawning etc impossible due lack constructor function pd arrays entities susceptible namespace collisions passing patch instance id extra step sometimes difficult accomplish pure data used basis number projects prototyping language sound engine table interface called reactable abandoned iphone app rjdj embed pd sound engine pd used prototyping audio video games number audio designers example eapd internal version pd used electronic arts ea also embedded ea spore pd also used networked performance networked resources collaborative improvisation nrci library
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Programming language topics
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register window computer engineering register windows feature instruction set architectures improve performance procedure calls common operation register windows one main features berkeley risc design would later commercialized amd am29000 intel i960 sun microsystems sparc intel itanium cpu designs include small amount high-speed memory known registers registers used cpu order hold temporary values working longer strings instructions considerable performance added design registers however since registers visible piece cpu instruction set number typically changed design released registers almost universal solution performance drawback different parts computer program use temporary values therefore compete use registers since good understanding nature program flow runtime difficult easy way developer know advance many registers use many leave aside parts program general sorts considerations ignored developers likely compilers use attempt use registers visible case processors registers begin also reasonable course action register windows aim solve issue since every part program wants registers use several sets registers provided different parts program registers visible would registers compete i.e made invisible rendering registers invisible implemented efficiently cpu recognizes movement one part program another procedure call accomplished one small number instructions prologue ends one similarly small set epilogue berkeley design calls would cause new set registers swapped point marked dead reusable call ends berkeley risc design eight registers total 64 visible programs complete set registers known register file particular set eight window file allows eight procedure calls register sets long program call chains longer eight calls deep registers never spilled i.e saved main memory cache slow process compared register access comparison sun microsystems sparc architecture provides simultaneous visibility four sets eight registers three sets eight registers windowed eight registers i0 i7 form input registers current procedure level eight registers l0 l7 local current procedure level eight registers o0 o7 outputs current procedure level next level called procedure called register window shifts sixteen registers hiding old input registers old local registers making old output registers new input registers common registers old output registers new input registers used parameter passing finally eight registers g0 g7 globally visible procedure levels amd 29000 improved design allowing windows variable size helps utilization common case fewer eight registers needed call also separated registers global set 64 additional 128 windows similarly ia-64 itanium architecture used variable-sized windows 32 global registers 96 windows register windows also provide easy upgrade path since additional registers invisible programs additional windows added time instance use object-oriented programming often results greater number smaller calls accommodated increasing windows eight sixteen instance approach used sparc included register windows newer generations architecture end result fewer slow register window spill fill operations register windows overflow less often register windows way improve register performance group stanford university designing mips saw berkeley work decided problem shortage registers poor utilization existing ones instead invested time compiler register allocation making sure wisely used larger set available mips resulted reduced complexity chip one half total number registers offering potentially higher performance cases single procedure could make use larger visible register space end modern compilers mips makes better use register space even procedure calls
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Computer architecture
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dataflex dataflex formerly known visual dataflex visual tool developing windows web mobile software applications one framework-based platform dataflex produced data access worldwide located miami company founded 1976 called data access corporation product available least 1982 started relatively early example fully fledged commercially used fourth-generation programming language 4gl early forms dataflex available cp/m ms-dos turbodos novell netware os/2 unix vax/vms ibm aix operating systems dataflex lasted many years niche application development environment dataflex product supports many database environments oracle database microsoft sql server ibm db2 mysql postgresql pervasive psql well odbc database dataflex applications used around 3 million users july 2017 version 19.0 dataflex language differentiates programming languages following ways dataflex programming language used following development environments
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Programming language topics
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ti-89 series ti-89 ti-89 titanium graphing calculators developed texas instruments ti differentiated ti graphing calculators computer algebra system allows symbolic manipulation algebraic expressions—equations solved terms variables whereas ti-83/84 series give numeric result ti-89 graphing calculator developed texas instruments 1998 unit features 160×100 pixel resolution lcd screen large amount flash memory includes ti advanced mathematics software ti-89 one highest model lines ti calculator products along ti-nspire summer 2004 standard ti-89 replaced ti-89 titanium ti-89 runs 16-bit microprocessor motorola 68000 nominally runs 10 12 mhz depending calculator hardware version texas instruments allocated 256 total kb ram unit 190 kb available user 2 mb flash memory 700 kb available user ram flash rom used store expressions variables programs tables text files lists ti-89 essentially ti-92 plus limited keyboard smaller screen created partially response fact calculators allowed many standardized tests ti-92 considered computer due qwerty layout keyboard additionally people found ti-92 unwieldy overly large ti-89 significantly smaller—about size graphing calculators flash rom feature present ti-92 plus original ti-92 major advantage ti-89 lower-model ti calculators built-in computer algebra system cas calculator evaluate simplify algebraic expressions symbolically example entering codice_1 returns formula_1 answer prettyprinted default displayed would written hand e.g aforementioned formula_1 rather codice_1 ti-89 abilities include addition standard two-dimensional function plots also produce graphs parametric equations polar equations sequence plots differential equation fields three-dimensional two independent variable functions ti-89 directly programmable language called ti-basic ti derivative basic calculators use pc also possible develop complex programs motorola 68000 assembly language c translate machine language copy calculator two software development kits c programming available one ti flash studio official ti sdk tigcc third-party sdk based gcc since ti-89 release 1998 thousands programs math science entertainment developed many available games generic clones tetris minesweeper classic games programs advanced example zx spectrum emulator chess-playing program symbolic circuit simulator clone link awakening one popular well-known games phoenix many calculator games useful programs found ti-program sharing sites ticalc.org major one offers thousands calculator programs four hardware versions ti-89 versions normally referred hw1 hw2 hw3 hw4 released may 2006 entering key sequence f1 displays hardware version older os versions 2.00 n't display anything hardware version unless calculator hw2 later differences hardware versions well documented texas instruments hw1 hw2 correspond original ti-89 hw3 hw4 present ti-89 titanium significant difference hw1 hw2 way calculator handles display hw1 calculators video buffer stores information displayed screen every time screen refreshed calculator accesses buffer flushes display direct memory access hw2 later calculators region memory directly aliased display controller memory-mapped i/o allows slightly faster memory access hw1 dma controller used 10 bus bandwidth however interferes trick programs use implement grayscale graphics rapidly switching two displays page-flipping hw1 dma controller base address changed single write memory-mapped hardware register screen automatically use new section memory beginning next frame hw2 new page must written screen software effect cause increased flickering grayscale mode enough make 7-level grayscale supported hw1 unusable although 4-level grayscale works calculators hw2 calculators slightly faster ti increased nominal speed processor 10 mhz 12 mhz believed ti increased speed hw4 calculators 16 mhz though many users disagree finding another difference hw1 hw2 calculators assembly program size limitations size limitation hw2 calculators varied ams version calculator ams 2.09 limit 24k earlier versions limited assembly programs 8k earliest ams versions limit hw1 calculators hardware enforce limits easy bypass software unofficial patches kernels installed hw2 calculators remove limitations ti-89 titanium released summer 2004 largely replaced popular classic ti-89 ti-89 titanium referred hw3 uses corresponding ams 3.x 2006 new calculators upgraded hw4 supposed offer increases ram speeds 16 mhz benchmarks made users reported speeds 12.85–14.1 mhz touted advantages ti-89 titanium original ti-89 include two times flash memory three times much available user ti-89 titanium essentially voyage 200 except n't integrated keyboard ti-89 titanium also usb on-the-go port connectivity ti-89 titanium calculators computer store programs update operating system ti-89 titanium also features pre-loaded applications cellsheet spreadsheet program also offered ti calculators titanium slightly updated cas adds mathematical functions notably implicit differentiation titanium also slightly differing case design ti-89 titanium case design similar ti-84 plus minor compatibility issues c assembly programs developed original ti-89 recompiled work titanium due various small hardware changes though cases problems fixed using utility ghostbuster olivier armand kevin kofler option generally preferred requires knowledge program works without need program source code automated n't require additional computer software cases one character needs changed rom base ti-89 0x200000 whereas ti-89 titanium 0x800000 hand patcher problems caused mirror memory ghost space lack thereof joint council qualifications publish examination instructions behalf main examination boards england wales northern ireland instructions state calculator used examination must designed offer symbolic algebra manipulation symbolic differentiation integration precludes use ti-89 ti-89 titanium examinations may used part classroom study sqa give instructions examinations scotland united states ti-89 allowed college board calculator-permitted tests including sat sat subject tests ap calculus physics chemistry statistics exams however calculator banned use act plan classrooms ti-92 series otherwise comparable features qwerty keyboard results classified computer device rather calculator
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Computer architecture
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duel test drive ii duel test drive ii racing video game developed distinctive software published accolade amiga amstrad cpc apple iigs commodore 64 ms-dos msx zx spectrum atari st sega genesis snes like original test drive focus duel driving exotic cars dangerous highways evading traffic trying escape police pursuits first game series player simply racing time single scenario test drive ii improves upon predecessor introducing varied scenery giving player option racing clock competing computer-controlled opponent player initially given opportunity choose car drive level difficulty turn determines whether car use automatic manual transmission—the number difficulty options varies gaming platforms levels begin player car computer opponent selected idling roadway primarily two four lane public highways many turns level different include obstacles bridges cliffs tunnels addition cars already road level also one police cars along course goal level reach gas station end course least amount time stopping gas station mandatory one could drive past inattentive consequence stopping results running gas thus losing car life player begins game 5 lives one lost time player crashes something player completes level without crashing running gas awarded bonus life addition losing life crashing adds thirty seconds player time cars could crash traffic off-road obstacles trees could crash falling cliff one mountain levels could sustain much damage staying roadway long flatland levels players could also lose life using manual transmission redlining consequently blowing engine crashing police car instantly ends game regardless number lives player left police cars appear every level player driving faster speed limit encountering one police car follow pursuit point pursued police car able pass player car player forced pull receives ticket stating offense speed vehicle n't cost player life take away valuable time players avoid pursued police slowing encountering anticipating aid radar detector comes standard vehicles game standard version test drive ii player option using one two vehicles three 1992 console versions game vehicles presented beginning game technical specifications including top speed torque acceleration rates cars included porsche 959 ferrari f40 third car lamborghini diablo non-console versions accolade later released two data disks included playable cars released many platforms computer versions game provided one course referred game “ master scenery ” consisting several stages stage one three possible locations desert cacti along side road mountain sheer rock wall one side highway cliff occasionally tunnel mountain grassy area trees later two scenery disks released containing additional course four available courses snes version game varying length difficulty route public highway different part continental united states courses included three cars chosen version game technically stopped law point animated female police officer smiles character character smiles return apprehended law enforcement various infractions including evasion police course end sequence shows female police officer placing player arrest virtually impossible complete given course without police confrontation end game due fact must maintain high speeds evade police cars highways computer gaming world stated liked test drive would like version like predecessor steering system avoid compute favorably reviewed game realism especially joystick stated installation overly difficult frustrating
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Computer architecture
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qp framework qp quantum platform family lightweight open source software frameworks building responsive modular real-time embedded applications systems cooperating event-driven active objects actors qp family consists qp/c qp/c++ qp-nano frameworks quality controlled documented commercially licensable qp frameworks run bare-metal single-chip microcontrollers completely replacing traditional real-time operating system rtos ports ready-to-use examples provided major cpu families qp/c qp/c++ also work traditional os/rtos posix linux qnx windows vxworks threadx microc/os freertos etc behavior active objects actors specified qp means hierarchical state machines uml statecharts frameworks support manual coding uml state machines c c++ well fully automatic code generation means free graphical qm modeling tool qp frameworks qm modeling tool used medical devices defense aerospace robotics consumer electronics wired wireless telecommunication industrial automation transportation many active objects inherently support automatically enforce following best practices concurrent programming active objects dramatically improve ability reason concurrent software contrast using raw rtos tasks directly trouble number reasons particularly raw tasks let anything offer help automation best practices good patterns active objects raise level abstraction naked threads let express intent directly thus improving productivity active objects operate vacuum require software infrastructure framework provides minimum execution thread active object queuing events event-based timing services resource-constrained embedded systems biggest concern always scalability efficiency frameworks especially frameworks accompanying various modeling tools traditionally built top conventional rtos adds memory footprint cpu overhead final solution qp frameworks designed efficiency minimal footprint ground need rtos stand-alone configuration fact compared conventional rtoses qp frameworks provide smaller footprint especially ram data space also rom code space possible active objects n't need block blocking mechanisms e.g. semaphores conventional rtos needed characteristics make event-driven active objects perfect fit single-chip microcontrollers mcus get productivity boost working higher level abstraction raw rtos tasks get lower resource utilization better power efficiency event-driven systems use cpu processing events otherwise put chip low-power sleep mode qp consists universal uml-compliant event processor qep portable event-driven real-time framework qf tiny run-to-completion kernel qk software tracing system qs qep quantum event processor universal uml-compliant event processor enables direct coding uml state machines uml statecharts highly maintainable c c++ every state machine element mapped code precisely unambiguously exactly traceability qep fully supports hierarchical state nesting enables reusing behavior across many states instead repeating actions transitions qf quantum framework highly portable event-driven real-time application framework concurrent execution state machines specifically designed real-time embedded systems qk quantum kernel tiny preemptive non-blocking run-to-completion kernel designed specifically executing state machines run-to-completion rtc fashion qs quantum spy software tracing system enables live monitoring event-driven qp applications minimal target system resources without stopping significantly slowing code types qp frameworks qp/c qp/c++ qp-nano easily adapted various microprocessor architectures compilers adapting qp software called porting qp frameworks designed ground make porting easy currently bare-metal qp ports exist following processor architectures qp/c qp/c++ frameworks also work traditional operating systems rtoses currently qp ports exist following oses/rtoses qp framework types dual-licensed open source gplv2 traditional closed-source license users want distribute qp e.g embedded inside user upgradable devices retain proprietary status code fee several types commercial royalty-free closed-source licenses available
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Operating systems
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niklaus wirth niklaus emil wirth born 15 february 1934 swiss computer scientist designed several programming languages including pascal pioneered several classic topics software engineering 1984 turing award generally recognized highest distinction computer science developing sequence innovative computer languages wirth born winterthur switzerland 1934 1959 earned degree electronics engineering swiss federal institute technology zürich eth zürich 1960 earned m.sc université laval canada 1963 awarded ph.d. electrical engineering computer science eecs university california berkeley supervised computer designer pioneer harry huskey 1963 1967 served assistant professor computer science stanford university university zurich 1968 became professor informatics eth zürich taking two one-year sabbaticals xerox parc california 1976–1977 1984–1985 wirth retired 1999 2004 made fellow computer history museum seminal work programming languages algorithms including euler algol-w pascal modula oberon wirth chief designer programming languages euler algol w pascal modula modula-2 oberon oberon-2 oberon-07 also major part design implementation team lilith oberon operating systems lola digital hardware design simulation system received association computing machinery acm turing award development languages 1984 1994 inducted fellow acm book written jointly kathleen jensen pascal user manual report served basis many language implementation efforts 1970s 1980s united states across europe article program development stepwise refinement teaching programming considered classic text software engineering 1975 wrote book algorithms data structures programs gained wide recognition major revisions book new title algorithms data structures published 1985 2004 examples first edition written pascal replaced later editions examples written modula-2 oberon respectively textbook systematic programming introduction considered good source students wanted coding regarded challenging text work sought imperative reading interested numerical mathematics 1992 published together jürg gutknecht full documentation oberon os.. second book together martin reiser intended programmer guide 1995 popularized adage known wirth law states software getting slower rapidly hardware becomes faster 1995 paper plea lean software attributes martin reiser
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Programming language topics
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address windowing extensions address windowing extensions awe microsoft windows application programming interface allows 32-bit software application access physical memory virtual address space even excess 4 gb limit process mapping application virtual address space physical memory awe known windowing similar overlay concept environments awe beneficial certain data-intensive applications database management systems scientific engineering software need manipulate large data sets minimizing paging application reserves region window virtual address space allocates one regions physical memory using awe api application map virtual window one physical regions application reserve one virtual address space map allocated regions physical memory long number bytes reserved virtual address space matches physical memory region application must lock pages memory privilege use awe 32-bit systems awe depends physical address extension support reserving memory 4 gb awe first introduced windows 2000 new api superseding pse36 method windows nt 4.0 enterprise edition accessing 4 gb memory longer supported windows 2000 among first applications make use awe oracle 8.1.6 microsoft sql server 2000 /3gb boot flag used repartition 32-bit virtual address space 2 gb kernel 2 gb userland 3 gb userland awe limited accessing 16 gb physical memory limitation one gb reserved kernel n't enough memory page table entries map 16 gb memory additional restrictions maximum amount memory addressable thorough awe imposed windows licensing scheme example windows 2000 advanced server limited 8 gb windows 2000 data center server supported 64 gb article published dr. dobb journal 2004 noted memory allocated using address windowing extensions written pagefile suggested awe regions could therefore used way protecting sensitive application data encryption keys
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Operating systems
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xtext xtext open-source software framework developing programming languages domain-specific languages dsls unlike standard parser generators xtext generates parser also class model abstract syntax tree well providing fully featured customizable eclipse-based ide xtext developed eclipse project part eclipse modeling framework project licensed eclipse public license first version xtext published 2006 openarchitectureware project last version released oaw project version 4.3 since beginning 2008 xtext developed eclipse eclipse modeling project joining eclipse annual simultaneous release xtext released version 0.7.0 june 2009 1.0 june 2010 2.0 june 2011 2.3 june 2012 2.5 december 2013 2.6 may 2014 2.7 september 2014 framework mainly developed german company itemis specify language developer write grammar xtext grammar language grammar describes ecore model derived textual notation definition code generator derives antlr parser classes object model used independently eclipse xtext includes features integrate well eclipse-based ide xtext languages ide highly configurable language infrastructure ide wired using dependency injection guice default components easily replaced binding customized ones instead since version 2.0 xtext facilitated development domain-specific languages java virtual machine referring compiling java artifacts tight integration eclipse java development toolkit reusable expression languages library enables rich behavior within dsl code generator written xtend hooked language jvm languages enough map dsl concepts java artifacts get holistic java integration alternative interpreter also available time writing article xtext homepage listed around 40 commercial non-commercial projects several application domains using xtext general-purpose language xtend also built xtext
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Programming language topics
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scada strangelove scada strangelove independent group information security researchers founded 2012 focused security assessment industrial control systems ics scada main fields research include scada strangelove interests expand classic ics components covers various embedded systems however encompass smart home components solar panels wind turbines smartgrid well areas group members continue develop publish numerous open source tools scanning fingerprinting security evaluation password bruteforcing ics devices devices work industrial protocols modbus siemens s7 mms iso ec 60870 profinet 2014 shodan used published tools building map ics devices publicly available internet open source security assessment frameworks thc hydra metasploit digitalbond redpoint used shodan-developed tools techniques group published security-hardening guidelines industrial solutions based siemens simatic wincc wincc flexible guidelines contain detailed security configuration walk-throughs descriptions internal security features appropriate best practices among group ’ noticeable projects choo choo pwn ccp also named critical infrastructure attack cia interactive laboratory built upon ics software hardware used real world every system connected toy city infrastructure includes factories railroads facilities laboratory demonstrated various conferences including phdays power community 30c3 primarily laboratory used discovery new vulnerabilities evaluation security mechanisms however also used workshops educational activities positive hack days iv contestants found several 0-day vulnerabilities indusoft web studio 7.1 schneider electric specific ics hardware rtu pet-7000 ics vulnerability discovery challenge group supports secure open smartgrid scadasos project find fix vulnerabilities intellectual power grid components photovoltaic power station wind turbine power inverter 80 000 industrial devices discovered isolated internet 2015 group members frequently seen presenting conferences like ccc scada security scientific symposium positive hack days notable talks overview vulnerabilities discovered widely distributed siemens simatic wincc software tools implemented searching ics internet talk consisted overview vulnerabilities discovered various systems produced abb emerson honeywell siemens presented phdays iii phdays iv implications security research aimed realization various industrial network protocols profinet modbus dnp3 iec 61850-8-1 mms iec international electrotechnical commission 61870-5-101/104 fte fault tolerant ethernet siemens s7 presentations security research showing impact radio 3g/4g networks security mobile devices well industrial equipment analysis security architecture implementation wide spread platforms wind solar energy generation produce many gigawatts cybersecurity assessment railway signaling systems automatic train control atc computer-based interlocking cbi european train control system etcs greater china cyber threat landscape keynote sergey gordeychik overview vulnerabilities attacks cyber-security incidents greater china region presented talk hopeless relay protection substation automation kirill nesterov alexander tlyapov security analysis results key digital substation component relay protection terminals presented vulnerabilities including remote code execution siemens siprotec general electric line distance relay nari abb protective relays presented names catchwords graphical elements refer stanley kubrick ’ film dr. strangelove talks group members often refer cold war events caribbean crisis draw parallels nuclear arms race current escalation cyberwar group members follow approach “ responsible disclosure ” “ ready wait years vendor patching vulnerability ” public exploits discovered vulnerabilities published account longevity ics implication long process patching ics however conflicts still happen notably 2012 talk def con called due dispute persistent weaknesses siemens industrial software
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Computer security
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easyrec easyrec open-source program provides personalized recommendations using restful web services integrated web enabled applications distributed gnu general public license studio smart agent technologies hosted sourceforge written java uses mysql database comes administration tool development easyrec implementation adaptive personalization approach started course several research development projects conducted studio smart agent technologies close cooperation international companies year 2008 core functionality easyrec developed forming basis research prototypes focusing music domain e.g musicexplorer june 2009 beta version easyrec containing basic administration features integrated movie streaming portal evaluation purposes furthermore september 2009 easyrec awarded special recognition category “ award innovations – innovations economic upswing ” jury austrian state prize multimedia e-business comprehensive refactoring phase integration evaluation results easyrec published sourceforge 18 february 2010 course cebit tradeshow 2011 hanover easyrec awarded german “ innovationspreis-it 2011 ” following five primary goals guided development easyrec although easyrec domain-agnostic general purpose personalization system current web service api customized providing online shops item recommendations especially small medium enterprises easyrec provides low barrier entrance personalization major feature easyrec set usage statistics business relevant information presented via administration management interface furthermore easyrec administrator supported variety administration configuration functions including manual import adaptation business rules integrators developers benefit lightweight web service apis rest soap well guided installation wizard concerning personalization functionality easyrec providing following services additionally integration showcase mediawiki extension developed bundled application currently additional features like recommender algorithms plugin-system evaluated prepared integration easyrec system underlying architecture easyrec designed robust scalable—separating time-consuming computations task online assembling recommendations easyrec designed multi-layer system consisting moreover generator server contains different item association generators create business rules define relation two items examples web sites using easyrec recommender system
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Web technology
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natural language processing natural language processing nlp subfield linguistics computer science information engineering artificial intelligence concerned interactions computers human natural languages particular program computers process analyze large amounts natural language data challenges natural language processing frequently involve speech recognition natural language understanding natural language generation history natural language processing nlp generally started 1950s although work found earlier periods 1950 alan turing published article titled computing machinery intelligence proposed called turing test criterion intelligence georgetown experiment 1954 involved fully automatic translation sixty russian sentences english authors claimed within three five years machine translation would solved problem however real progress much slower alpac report 1966 found ten-year-long research failed fulfill expectations funding machine translation dramatically reduced little research machine translation conducted late 1980s first statistical machine translation systems developed notably successful natural language processing systems developed 1960s shrdlu natural language system working restricted blocks worlds restricted vocabularies eliza simulation rogerian psychotherapist written joseph weizenbaum 1964 1966 using almost information human thought emotion eliza sometimes provided startlingly human-like interaction patient exceeded small knowledge base eliza might provide generic response example responding head hurts say head hurts 1970s many programmers began write conceptual ontologies structured real-world information computer-understandable data examples margie schank 1975 sam cullingford 1978 pam wilensky 1978 talespin meehan 1976 qualm lehnert 1977 politics carbonell 1979 plot units lehnert 1981 time many chatterbots written including parry racter jabberwacky 1980s natural language processing systems based complex sets hand-written rules starting late 1980s however revolution natural language processing introduction machine learning algorithms language processing due steady increase computational power see moore law gradual lessening dominance chomskyan theories linguistics e.g transformational grammar whose theoretical underpinnings discouraged sort corpus linguistics underlies machine-learning approach language processing earliest-used machine learning algorithms decision trees produced systems hard if-then rules similar existing hand-written rules however part-of-speech tagging introduced use hidden markov models natural language processing increasingly research focused statistical models make soft probabilistic decisions based attaching real-valued weights features making input data cache language models upon many speech recognition systems rely examples statistical models models generally robust given unfamiliar input especially input contains errors common real-world data produce reliable results integrated larger system comprising multiple subtasks many notable early successes occurred field machine translation due especially work ibm research successively complicated statistical models developed systems able take advantage existing multilingual textual corpora produced parliament canada european union result laws calling translation governmental proceedings official languages corresponding systems government however systems depended corpora specifically developed tasks implemented systems often continues major limitation success systems result great deal research gone methods effectively learning limited amounts data recent research increasingly focused unsupervised semi-supervised learning algorithms algorithms able learn data hand-annotated desired answers using combination annotated non-annotated data generally task much difficult supervised learning typically produces less accurate results given amount input data however enormous amount non-annotated data available including among things entire content world wide web often make inferior results algorithm used low enough time complexity practical 2010s representation learning deep neural network-style machine learning methods became widespread natural language processing due part flurry results showing techniques achieve state-of-the-art results many natural language tasks example language modeling parsing many others popular techniques include use word embeddings capture semantic properties words increase end-to-end learning higher-level task e.g. question answering instead relying pipeline separate intermediate tasks e.g. part-of-speech tagging dependency parsing areas shift entailed substantial changes nlp systems designed deep neural network-based approaches may viewed new paradigm distinct statistical natural language processing instance term neural machine translation nmt emphasizes fact deep learning-based approaches machine translation directly learn sequence-to-sequence transformations obviating need intermediate steps word alignment language modeling used statistical machine translation smt early days many language-processing systems designed hand-coding set rules e.g writing grammars devising heuristic rules stemming however rarely robust natural language variation since so-called statistical revolution late 1980s mid 1990s much natural language processing research relied heavily machine learning machine-learning paradigm calls instead using statistical inference automatically learn rules analysis large corpora typical real-world examples corpus plural corpora set documents possibly human computer annotations many different classes machine-learning algorithms applied natural-language-processing tasks algorithms take input large set features generated input data earliest-used algorithms decision trees produced systems hard if-then rules similar systems hand-written rules common increasingly however research focused statistical models make soft probabilistic decisions based attaching real-valued weights input feature models advantage express relative certainty many different possible answers rather one producing reliable results model included component larger system systems based machine-learning algorithms many advantages hand-produced rules following list commonly researched tasks natural language processing tasks direct real-world applications others commonly serve subtasks used aid solving larger tasks though natural language processing tasks closely intertwined frequently subdivided categories convenience coarse division given first published work artificial intelligence published 2018 1 road marketed novel contains sixty million words
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Computational linguistics
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data anonymization data anonymization type information sanitization whose intent privacy protection process either encrypting removing personally identifiable information data sets people data describe remain anonymous european union new general data protection regulation demands stored data people eu undergo either anonymization pseudonymization process data anonymization defined process personal data irreversibly altered way data subject longer identified directly indirectly either data controller alone collaboration party data anonymization enables transfer information across boundary two departments within agency two agencies reducing risk unintended disclosure certain environments manner enables evaluation analytics post-anonymization context medical data anonymized data refers data patient identified recipient information name address full post code must removed together information conjunction data held disclosed recipient could identify patient.. de-anonymization reverse process anonymous data cross-referenced data sources re-identify anonymous data source generalization perturbation two popular anonymization approaches relational data.. process obscuring data ability re-identify later also called pseudonymization one way companies store data way hipaa compliant ordered alphabetically
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Computer security
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howard duck video game howard duck also known howard duck adventure volcano island action video game released 1986 activision zx spectrum commodore 64 apple ii game tie-in film howard duck came year game involves players controlling howard duck save best friends phil beverly parachuted volcano island howard needs find backpack proceed search game consists four levels last howard armed neutron gun finally face overlord game received fairly negative reviews computer gamer gave overall 55 stating beautifully presented well programmed rates one activision better recent releases deserves consideration outside unfortunate tie-in predicting however low longevity aktueller software markt described game fulfilling expectancies worth money
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Computer architecture
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bit manipulation instruction sets bit manipulation instructions sets bmi sets extensions x86 instruction set architecture microprocessors intel amd purpose instruction sets improve speed bit manipulation instructions sets non-simd operate general-purpose registers two sets published intel bmi referred bmi1 bmi2 introduced haswell microarchitecture another two sets published amd abm advanced bit manipulation also subset sse4a implemented intel part sse4.2 bmi1 tbm trailing bit manipulation extension introduced piledriver-based processors extension bmi1 dropped zen-based processors abm implemented single instruction set amd amd processors support instructions neither intel considers codice_1 part sse4.2 codice_2 part bmi1 codice_1 separate cpuid flag however intel uses amd codice_4 flag indicate codice_2 support since codice_2 completes abm codice_2 almost identical bit scan reverse codice_8 instruction sets zf result zero cf source zero flags rather produces defined result source operand size bits source operand zero instructions enabled codice_9 bit cpuid intel officially considers codice_2 part bmi advertises codice_2 support using codice_4 cpuid feature flag bmi1 available amd jaguar piledriver newer processors intel haswell newer processors intel introduced bmi2 together bmi1 line haswell processors amd produced processors supporting bmi1 without bmi2 bmi2 supported amds excavator architecture newer codice_13 codice_14 instructions new generalized bit-level compress expand instructions take two inputs one source selector selector bitmap selecting bits packed unpacked codice_14 copies selected bits source contiguous low-order bits destination higher-order destination bits cleared codice_13 opposite selected bits contiguous low-order bits copied selected bits destination destination bits cleared used extract bitfield input even lot bit-level shuffling previously would expensive instructions similar bit level gather-scatter simd instructions codice_13 codice_14 instructions like rest bmi instruction sets operate general-purpose registers 16-bit examples operations tbm consists instructions complementary instruction set started bmi1 complementary nature means necessarily need used directly generated optimizing compiler supported amd introduced tbm together bmi1 piledriver line processors amd jaguar zen-based processors support tbm
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Computer architecture
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java portlet specification java portlet specification defines contract portlet container portlets provides convenient programming model java portlet developers portlets pluggable user interface software components managed displayed web portal example enterprise portal web cms portlet aggregate integrate personalize content different sources within web page portlet responds requests web client generates dynamic content portlets produce fragments markup html xhtml wml aggregated portal typically following desktop metaphor portal page displayed collection non-overlapping portlet windows portlet window displays portlet hence portlet collection portlets resembles web-based application hosted portal examples portlet applications e-mail weather reports discussion forums news portlet managed portlet container portlet standards platform independent application programming interfaces intended enable software developers create portlets plugged portal supporting standards example java portlet specification java portlet resembles java servlet produces fragments rather complete documents bound url portlet container runs portlets provides required runtime environment portlet container contains portlets manages life cycles also provides persistent storage mechanisms portlet preferences portlet container receives requests portal execute requests portlets hosted portlet container responsible aggregating content produced portlets portal handles aggregation portal portlet container built together single component application suite two separate components portal application java portlet specification v1.0 developed java community process java specification request jsr 168 released final form october 2003 java portlet specification v1.0 introduces basic portlet programming model initially java portal vendors portlet development framework thus portlets confined specific portal servers could n't deployed rest java portals jsr 168 inception java portlets may deployed java portal servers adhering jsr 168 specifications portlets catalog set portlets ready-to-use components enterprise portals want adopt portals certainly need many variety portlets deploy run portlets catalog use jsr 168 portlets catalog makes sure portlets catalog may run standards–compliant java portal server types portlet solution vertical domains technology like collaboration social networking community content management utility calendaring hrm available catalogs many open source commercial portlets catalog available jsr 168 based solutions rare jsr 168 specifications offer suitability developers reuse code maintain set jsr 168 compliant portlets deployers easy keep single set solution deploy many jsr-286 java portlet specification v2.0 developed jcp created alignment updated version 2.0 wsrp released june 2008 developed improve short-comings version 1.0 specification jsr-168 major features include jsr-362 java portlet specification v3.0 released april 2017 major features include
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Programming language topics
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codelobster codelobster portable integrated development environment ide primarily php also supports html css javascript development plug-ins available drupal wordpress smarty joomla jquery facebook codeigniter yii cakephp free registration email required 30 days use program paid versions also lite professional additional features program missing help system latest version program features syntax highlighting auto-completion sql php html css javascript xml well automatic syntax checking html css inspector like firebug also includes drupal support plugins paid offer trial periods varying length
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Programming language topics
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zealot campaign malware zealot campaign cryptocurrency mining malware collected series stolen national security agency nsa exploits released shadow brokers group windows linux machines mine cryptocurrency specifically monero discovered december 2017 exploits appeared zealot suite include eternalblue eternalsynergy apache struts jakarta multipart parser attack exploit cve-2017-5638 notable exploit within zealot vulnerabilities includes vulnerability cve-2017-9822 known dotnetnuke dnn exploits content management system user install monero miner software estimated usd 8,500 monero mined single targeted computer campaign discovered studied extensively f5 networks december 2017 many zealot exploits leaked nsa malware suite widely described “ unusually high obfuscated payload ” meaning exploit works multiple levels attack vulnerable server systems causing large amounts damage term “ zealot ” derived starcraft series namely type warrior multi-layered attack begins two http requests used scan target vulnerable systems network similar attacks past targeted either windows linux-based systems yet zealot stands prepared version apache struts exploit along using dnn operating system os identified via java script malware loads os-specific exploit chains targeted system runs either linux os x struts payload install python agent post-exploitation stage checking target system see already infected downloads crypto-miner software often referred “ mule ” obfuscates embedded python code process different botnet malware zealot campaigns request command control c c server-specific user-agent cookie headers meaning anyone malware receive different response due zealot encrypting via rc4 cipher see network inspection security software able see malware network able scan targeted os windows struts payload downloads encoded powershell interpreter decoded two times program runs another obfuscated script turn leads device url download files file known powershell script “ scv.ps1 ” heavily obfuscated script allows attacker deploy mining software targeted device deployed software also use dynamic-link library dll mining malware deployed using reflective dll injection technique attach malware powershell processing remain undetected prior moving onto next stage program also checks see firewall active yes pipe embedded base64 embedded python code circumvent firewall another possible solution known “ little snitch ” possibly terminate firewall active post-exploitation stage program scans target system python 2.7 higher found system download following downloads python module probe.py propagate network script highly obfuscated base encryption base64 zipped 20 times downloaded zip file could named several iterations derived starcraft game files included listed files run successfully miner software introduced known commonly “ mule ” malware powershell script named “ minerd_n.ps2 ” within compressed files downloaded executed via eternalsynergy exploit software utilizes target system ’ hardware process mining cryptocurrency mining software reportedly stolen close 8,500 one victim yet total amounts mined monero still speculated among researchers initially utilized wannacry ransomware attack 2017 exploit specifically utilized mining software zealot campaign much known exploit used cooperation eternalblue along exploits zealot campaign others notably eternalsynergy involved equifax hack wannacry ransomware cryptocurrency mining campaigns asp.net based content management system dnn sends serialized object via vulnerable dnnpersonalization cookie http request stage using “ objectdataprovider ” “ objectstateformatter ” attacker embeds another object victim ’ shell system invoked shell system deliver script delivered apache struts exploit dnn acts secondary backup attackers apache struts exploit fail used deliver powershell script initiate attack exploit one two http requests sent initial stage infection among first discovered exploits zealot campaign jakarta parser exploit allowed hackers exploit “ zero-day ” flaw software hack financial firm equifax march 2017 particular exploit notable public exploits utilized largely public case still utilized december 2017 exploit patched bangladeshi-based group utilized spear-phishing method known commonly business email compromise bce steal cryptocurrency unsuspecting employees lazarus primarily targeted employees cryptocurrency financial organizations executed via word document claiming legitimate-appearing european company document opened embedded trojan virus would load onto system computer begin steal credentials malware specific malware still unknown ties zealot malware among several exploits involved march 2017 equifax data breach jakarta parser eternalblue eternalsynergy heavily involved attacking servers instead software utilized mine cryptocurrency used mine data 130 million equifax customers
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Computer security
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email injection email injection security vulnerability occur internet applications used send email messages email equivalent http header injection like sql injection attacks vulnerability one general class vulnerabilities occur one programming language embedded within another form added web page submits data web application malicious user may exploit mime format append additional information message sent new list recipients completely different message body mime format uses carriage return delimit information message raw message determines eventual destination adding carriage returns submitted form data allow simple guestbook used send thousands messages malicious spammer could use tactic send large numbers messages anonymously information topic including examples ways avoid vulnerability found securephp wiki however vulnerability limited php potentially affect application sends email messages based input arbitrary users
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Computer security
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socket s1 socket s1 cpu socket type used amd turion 64 athlon 64 mobile phenom ii mobile later sempron processors debuted dual-core turion 64 x2 cpus may 17 2006 socket s1 638 pin low profile zif 1.27mm pitch socket replaces existing socket 754 mobile computing segment e.g laptops socket s1 cpus include support dual-channel ddr2 sdram dual-core mobile cpus virtualization technology compete mobile intel core 2 processor series different generations processors used variant pinouts s1 socket processors necessarily compatible socket even fit mechanically
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Computer architecture
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coda file system coda distributed file system developed research project carnegie mellon university since 1987 direction mahadev satyanarayanan descended directly older version andrew file system afs-2 offers many similar features intermezzo file system inspired coda coda many features desirable network file systems several features found elsewhere coda uses local cache provide access server data network connection lost normal operation user reads writes file system normally client fetches hoards data user listed important event network disconnection network connection lost coda client local cache serves data cache logs updates operating state called disconnected operation upon network reconnection client moves reintegration state sends logged updates servers transitions back normal connected-mode operation also different afs coda data replication method afs uses pessimistic replication strategy files allowing one read/write server receive updates servers acting read-only replicas coda allows servers receive updates allowing greater availability server data event network partitions case afs handle unique features introduce possibility semantically diverging copies files directories known conflicts disconnected operation local updates potentially clash connected users updates objects preventing reintegration optimistic replication potentially cause concurrent updates different servers object preventing replication former case called local/global conflict latter case server/server conflict coda extensive repair tools manual automated handle repair types conflicts coda developed linux support appeared 2.1 linux kernel series also ported freebsd subsequently obsoleted efforts way bring back efforts made port coda microsoft windows windows 95/windows 98 era windows nt windows xp means open source projects like djgcc dos c compiler cygwin
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Computer file systems
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loader.io loader.io cloud-based load scalability testing service saas allows developers test web applications api thousands concurrent connections loader.io cloud-based load testing service developers test performance scalability web applications apis provides simple cloud-based load testing born sendgrid labs late 2012
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Distributed computing architecture
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defense.net defense.net privately held american information technology services company company business protect internet-facing infrastructures – e-commerce web sites – forms distributed denial service ddos attacks network defense.net operates constellation ddos mitigation sites around internet capable filtering removing ddos attacks real-time defense.net founded barrett lyon 2012 lyon also pioneer ddos mitigation industry founder prolexic first ddos mitigation company 2014 company named one 100 hottest private companies north america red herring acquired shortly f5 networks purportedly 50 100 million 2012 bessemer venture partners lead series round funding total 9.5 million
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Computer security
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rpath computing rpath designates run-time search path hard-coded executable file library dynamic linking loaders use rpath find required libraries specifically encodes path shared libraries header executable another shared library rpath header value named executable linkable format header standards may either override supplement system default dynamic linking search paths rpath executable shared library optional entry codice_1 section elf executable shared libraries type codice_2 called codice_2 attribute stored link time linker tools codice_4 codice_5 create modify entry later different dynamic linkers elf implement use codice_2 attribute different ways dynamic linker gnu c library searches shared libraries following locations notes gnu linker gnu ld implements feature calls new-dtags used insert rpath lower precedence codice_9 environment variable new-dtags feature enabled linker codice_28 gnu codice_29 besides setting codice_2 attribute also sets codice_8 attribute string run time dynamic linker finds codice_8 attribute ignores value codice_2 attribute effect codice_9 checked first paths codice_8 attribute searched afterwards ld dynamic linker search dt_runpath locations transitive dependencies unlike dt_rpath instead specifying codice_36 linker environment variable codice_37 set effect dynamic linker solaris specifically codice_38 sunos 5.8 similar systems looks libraries directories specified ld_library_path variable looking codice_2 attribute sun microsystems first introduce dynamic library loading sun later added rpath option ld used essential libraries added security feature gnu ld support sun-style dynamic libraries example gnu sun ld ld.so refuse load termcap program needing unless file termcap.so /lib/ named termcap.so.4 ignored /lib/termcap.so.4 removed remediate shell dies one load alternate termcap.so rescue disk needed also new termcap.so.4 rpath /lib ld.so refuse use load unless clobbered /lib/termcap.so.4 another issue n't safe copy libs /lib use restricting would-be lib tester furthermore vs. means programs needing basic termcap.so denied library deleted abi access basic support old linux/sun used allows user direct program use termcap.so specify found /usr/local/lib n using search rules ld.so.conf however gnu ld always uses /lib /usr/lib regardless first /lib/termcap.so moved /usr/local/lib mentioned ld.so.conf enables use moving libs ld.so.conf use use preferred practice use programs check version libs support use features available often skipped old releases due slow computing speed lack time code correctly said test kind thing thoroughly given platform deciding rely release administrators today guaranteed respect past guidelines documentation unix varieties link load completely different way rpath specific ld shipped particular distribution lastly said rpath security feature however mandatory access control mac techniques effective effective rpath control lib reading writing control rpath using today compilers often nearly impossible given lengthy convoluted make 1 scripting worse build scripts ignore -- disable-rpath even though present option would time-consuming frustrating probably unfeasible fix build scripting every odd program compile simple sh 1 wrapper call real ld named ld.bin wrapper filter in/out option invoking ld however note builds incorrectly use rpath instead rpath-link locate intermediate products stay build directory thus backwardly demand rpath final product new issue concerning rpath
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Operating systems
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mary gardiner mary gardiner australian linux programmer director operations ada initiative described non-profit organization dedicated increasing participation women open technology culture council member linux australia september 2011 2012 gardiner ada initiative co-founder valerie aurora named two influential people computer security sc magazine gardiner co-founder aussiechix later became oceania women open tech former coordinator linuxchix speaks social norms beliefs minority contributors interested women colleagues believe women capability successfully contribute gardiner involved drafting adopting anti-harassment policies technology conferences gardiner winner 2011 rusty wrench award given linux australia service linux programmers australia commended work improve gender diversity oppose sexual harassment open-source software community keynote speaker wikimania 2012 held 12–15 july 2012 washington dc 2012 gardiner listed one 10 women tech give back datamation one influential people computer security sc magazine
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Operating systems
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disk encryption disk encryption technology protects information converting unreadable code deciphered easily unauthorized people disk encryption uses disk encryption software hardware encrypt every bit data goes disk disk volume used prevent unauthorized access data storage expressions full disk encryption fde whole disk encryption signify everything disk encrypted master boot record mbr similar area bootable disk code starts operating system loading sequence encrypted hardware-based full disk encryption systems truly encrypt entire boot disk including mbr transparent encryption also known real-time encryption on-the-fly encryption otfe method used disk encryption software transparent refers fact data automatically encrypted decrypted loaded saved transparent encryption files accessible immediately key provided entire volume typically mounted physical drive making files accessible unencrypted ones data stored encrypted volume read decrypted without using correct password/keyfile correct encryption keys entire file system within volume encrypted including file names folder names file contents meta-data transparent end user transparent encryption usually requires use device drivers enable encryption process although administrator access rights normally required install drivers encrypted volumes typically used normal users without rights general every method data seamlessly encrypted write decrypted read way user and/or application software remains unaware process called transparent encryption disk encryption replace file encryption situations disk encryption sometimes used conjunction filesystem-level encryption intention providing secure implementation since disk encryption generally uses key encrypting whole drive data decryptable system runs however disk encryption solutions use multiple keys encrypting different volumes attacker gains access computer run-time attacker access files conventional file folder encryption instead allows different keys different portions disk thus attacker extract information still-encrypted files folders unlike disk encryption filesystem-level encryption typically encrypt filesystem metadata directory structure file names modification timestamps sizes trusted platform module tpm secure cryptoprocessor embedded motherboard used authenticate hardware device since tpm chip unique particular device capable performing platform authentication used verify system seeking access expected system limited number disk encryption solutions support tpm implementations wrap decryption key using tpm thus tying hard disk drive hdd particular device hdd removed particular device placed another decryption process fail recovery possible decryption password token although advantage disk removed device might create single point failure encryption example something happens tpm motherboard user would able access data connecting hard drive another computer unless user separate recovery key multiple tools available market allow disk encryption however vary greatly features security divided three main categories software-based hardware-based within storage device hardware-based elsewhere cpu host bus adaptor hardware-based full disk encryption within storage device called self-encrypting drives impact performance whatsoever furthermore media-encryption key never leaves device therefore available virus operating system trusted computing group opal storage specification provides industry accepted standardization self-encrypting drives external hardware considerably faster software-based solutions although cpu versions may still performance impact media encryption keys well protected solutions boot drive require pre-boot authentication component available types solutions number vendors important cases authentication credentials usually major potential weakness since symmetric cryptography usually strong secure safe recovery mechanisms essential large-scale deployment disk encryption solutions enterprise solution must provide easy secure way recover passwords importantly data case user leaves company without notice forgets password challenge–response password recovery mechanism allows password recovered secure manner offered limited number disk encryption solutions benefits challenge–response password recovery emergency recovery information eri file provides alternative recovery challenge–response mechanism unfeasible due cost helpdesk operatives small companies implementation challenges benefits eri-file recovery full disk encryption schemes vulnerable cold boot attack whereby encryption keys stolen cold-booting machine already running operating system dumping contents memory data disappears attack relies data remanence property computer memory whereby data bits take several minutes degrade power removed even trusted platform module tpm effective attack operating system needs hold decryption keys memory order access disk full disk encryption also vulnerable computer stolen suspended wake-up involve bios boot sequence typically ask fde password hibernation contrast goes via bios boot sequence safe software-based encryption systems vulnerable various side channel attacks acoustic cryptanalysis hardware keyloggers contrast self-encrypting drives vulnerable attacks since hardware encryption key never leaves disk controller also full disk encryption schemes n't protect data tampering silent data corruption i.e bitrot means provide privacy integrity block cipher-based encryption modes used full disk encryption authenticated encryption concerns storage overhead needed authentication tags thus tampering would done data disk data would decrypted garbled random data read hopefully errors may indicated depending data tampered case os metadata – file system case file data – corresponding program would process file one ways mitigate concerns use file systems full data integrity checks via checksums like btrfs zfs top full disk encryption however cryptsetup started experimentally support authenticated encryption full disk encryption several benefits compared regular file folder encryption encrypted vaults following benefits disk encryption one issue address full disk encryption blocks operating system stored must decrypted os boot meaning key available user interface ask password full disk encryption solutions utilize pre-boot authentication loading small highly secure operating system strictly locked hashed versus system variables check integrity pre-boot kernel implementations bitlocker drive encryption make use hardware trusted platform module ensure integrity boot environment thereby frustrate attacks target boot loader replacing modified version ensures authentication take place controlled environment without possibility bootkit used subvert pre-boot decryption pre-boot authentication environment key used encrypt data decrypted external key input system solutions storing external key include possibilities varying degrees security however better unencrypted disk
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Computer file systems
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abort retry fail abort retry fail abort retry ignore error message found dos operating systems prompts end-user course action follow message cited example poor usability computer user interfaces cp/m attempting read floppy disk drive door open would hang disk inserted disk drive door closed early disk hardware send kind signal disk spinning timeout detect lack signal required much code tiny systems many users cp/m became accustomed method managing multiple disks opening disk drive stop program reading writing file correct disk could inserted primary design consideration pc dos software written cp/m portable dos without changes even first ibm pc hardware told operating system disk drive door open returning error software trying read disk would break ability manage disks way without changes still desirable improve experience particular giving user way get hang without find disk insert drive prompt invented reason missing disk disk drive door opened defined dos critical error would call critical error handler default critical error handler part command.com printed abort retry ... prompt waited user input problems particular checksum error reading data disk also defined critical error thus causing prompt appear reasons missing disk opened disk drive users could press key indicate wanted happen available options included program could install critical error handler running many sophisticated programs particular full screen programs order avoid messages disturbing display programs faked missing fail response dos 2.0 jumping back calling program skipping return stack dos risky hack relied stack layout skipped cleanup operations operating system error messages described example poor user interface design users message appeared choice hit r'—which repeated message—or hit another letter caused program crash work lost one scholar described way hard disks larger removable media zip drives made need manage multiple disks obsolete thus made prompt useless gradually replaced code acted like fail immediately dos 3.3 command.com provided startup option codice_1 order force default critical error handler return fail errors starting version 4.0 alternative command line processors 4dos ndos supported codice_1 corresponding codice_3 directive codice_4/codice_5 well option also supported command.com pts-dos 6.51 s/dos 1.0 well dr-dos 7.02 higher opendos 7.01 command.com provides similar feature codice_6 described install critical error handler still supported newer versions operating systems linux always act like fail cases humorous variations edgar allen poe raven using abort retry ignore place nevermore written 1980s 1990s quite popular distributed bulletin board email original best known version credited cleveland poet marcus bales adapted numerous times attributed anonymous lucy blades rob collins others 1993 neil howe published 13th gen abort retry ignore fail sympathetic book culture generation x 1996 white town released ep entitled abort retry fail pc magazine used term title column highlighting humorous computer-related errors
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Operating systems
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windows insider windows insider open software testing program microsoft allows users valid license windows 10 windows server 2016 register pre-release builds operating system previously accessible software developers microsoft launched windows insider developers enterprise testers technically able test new developer features pre-release software builds given publicly released gather low level diagnostics feedback order identify investigate mitigate improve windows 10 os help support guidance insider program participants direct communication microsoft engineers via proprietary communication diagnostic channel announced september 30 2014 along windows 10 september 2015 7 million people took part windows insider program february 12 2015 microsoft started test previews windows 10 mobile microsoft announced windows insider program would continue beyond official release windows 10 future updates gabriel aul previous head charge windows insider program current head windows insider program dona sarkar similar windows insider program microsoft office bing xbox visual studio code teams set insider programs microsoft originally launched windows insider enterprise testers technically able test new developer features gather feedback improve features built windows 10 time official launch windows 10 pcs total 5 million volunteers registered windows 10 windows 10 mobile also among first people receive official update windows 10 release windows 10 windows insider app merged settings app made ability install windows insider preview builds optional feature could accessed directly within windows 10 may 2017 microsoft announced program would extend windows server 2016 first insider build operating system released 13 july 2017 windows 10 insider preview updates delivered testers different rings logical categories windows insiders fast ring receive updates prior windows insiders slow ring might experience bugs issues february 2016 microsoft introduced new rings windows insider preview july 17 2017 reports began come windows 10 creators update refused install pcs tablets sporting intel atom clover trail processors first appeared though might temporary block microsoft hardware partners work fix issues preventing operating system run well however microsoft later confirmed devices running clover trail intel atom processors would receiving creators update processors longer supported intel appropriate firmware properly run versions windows 10 newer anniversary update following processors longer supported remain windows 10 anniversary update pcs unsupported processors could receive new features updates microsoft agreed extend support pcs bug fixes security updates latest compatible version windows 10 versions windows 10 released microprocessor released also supported installations operating systems may actively blocked example windows 10 version 1507 ltsb install kaby lake processors microsoft initially launched windows 10 technical preview certain third-generation x30 series phones lumia family subsequently released second-generation x20 series devices throughout testing phase hacked non-lumia phones supported time download preview builds microsoft responded blocking unsupported models roll back installed technical preview back windows phone 8.1 microsoft launched windows device recovery tool removes windows 10 recovers latest officially released software firmware preview build 10080 released may 14 2015 first support non-lumia device htc one m8 windows followed xiaomi partnership microsoft released rom port windows 10 flagship mi 4 handset june 1 2015 time limited certain registered users china build 10080 follow-up build 10166 also added support fourth-generation lumia x40 series devices result compatible windows phone 8 later lumia phones support preview august 2015 microsoft stated windows phone devices including microsoft new hardware partners announced previous year would receive final version windows 10 mobile would receive preview builds insider program however company provide information time whether new devices would added preview program microsoft instead focused promoting new devices come windows 10 mobile including lumia 950 lumia 950 xl flagships low-cost lumia 550 lumia 650 since release new windows 10 devices became eligible receive future updates advance via insider program beginning build 10586 december 4 2015 windows-based lg lancet also received version upgraded since february 19 2016 microsoft released first windows 10 mobile redstone preview build 14267 starting build future preview versions became exclusively available devices already running non-insider preview os except mi4 rom version followed build 14291 released existing windows 10 devices march 17 2016 conjunction official rtm release windows 10 mobile third fourth-generation lumias following week became available newly upgraded older lumias addition several devices already windows 10 mobile time supported devices subsequently received insider preview builds far build 15063 creators update released march 20 2017 included official release build 14393 anniversary update august 2 2016 however announced april 2017 many devices including third-generation lumias would receive rtm version creators update redstone development builds following feedback users devices remain supported nearly except lumia 640 xl variant originally come windows 10 mobile instead windows phone 8.1
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Operating systems
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mark iv software mark iv fourth-generation programming language created informatics inc. 1960s informatics took advantage ibm decision mark iv first software product cumulative sales 10 million mark iv developed ibm systems 360 370 rca spectra 70 main benefit allowing faster application development order 6 10 times faster system using 3gl cobol mark iv early 4gl allowed user development systems related business 1971 ad informatics several quotes customers mark iv went sterling software 1985 part company acquisition informatics general vision builder part product suite computer associates
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Programming language topics
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reverse deception reverse deception organized cyber threat counter-exploitation textbook investigates two topics first provides methods criteria rectify advanced persistent threats secondly covers cyber deception ieee review noted masterful presentation deception details identity apts prioritize actions applying skilled field-tested private- government- sector processes methods often involves cyber deception identified richard austin ieee review masterful presentation deception clear work interest different governments several currently involved considering future actions weaponizing cyber capabilities appears recommended reading lists notable u.s. military institutions including u.s. navy war college counterintelligence cyber threat section joint special operations university site military organizations made efforts similar manner people republic china prc considered active apt market special military effort undertaken translate simplified chinese prc national defense university press authors introduce first theory model classifying threat opportunistic-apt continuum either persistent non-persistent widely used industry built evaluation following criteria apt criteria additional content includes beer p. d. basie s. v. 2013 case cyber counterintelligence 2013 international conference adaptive science technology doi:10.1109/icastech.2013.6707493 carli l. d. sommer r. jha s. 2014 beyond pattern matching proceedings 2014 acm sigsac conference computer communications security ccs 14. doi:10.1145/2660267.2660361 csanádi g. 2015 cyber war poor man weapon mass destruction new whip hands rich defence review central journal hungarian defence forces,143 2015th ser. 154-174 chung k. kamhoua c. a. kwiat k. a. kalbarczyk z. t. iyer r. k. 2016 game theory learning cyber security monitoring 2016 ieee 17th international symposium high assurance systems engineering hase doi:10.1109/hase.2016.48 conti g. weigand m. skoudis e. raymond d. cook t. t. a. ragsdale d. 2014 towards cyber leader course weak faint hearted 3rd ed. vol 1337 rep. west point ny army cyber institute department electrical engineering computer science united states military academy gardner b 2018 social engineering non-linear warfare journal applied digital evidence 1 1 heckman k. e. stech f. j. thomas r. k. schmoker b. tsow a. w. 2015 cyber denial deception counter deception framework supporting active cyber defense heginbotham e. nixon m. morgan f. e. heim j. l. hagen j. li s. morris l. j 2015 u.s.-china military scorecard forces geography evolving balance power 1996 2017 santa monica ca rand henderson b. t. 2018 honeypot spies understanding internet-based data theft unpublished master thesis naval postgraduate school holguín j. m. moreno m. merino b 2013 detección de apts p. 9 rep. jajodia s. subrahmanian v. s. swarup v. wang c. 2016 cyber deception building scientific foundation lucas e. 2017 cyberphobia identity trust security internet bloomsbury maozhi y. ziwei l. 2015 mission scale chinese communist party strategic support force 中共戰略支援部隊的任務與規模 y. lin trans. pavlíková m. 2016 cyber operations russia ukraine ukrainian conflict obrana strategie defence strategy ,16 1 77-94. doi:10.3849/1802-7199.16.2016.1.077-094 rowe n. c. rrushi j 2018 introduction cyberdeception springer saadawi t. n. jordan l. boudreau v. colwell j 2011 cyber infrastructure protection carlisle pa strategic studies institute u.s. army war college sowa 2019 it-revision bei betrugsaufdeckung investigation und prüfung doloser handlungen it-revision it-audit und it-compliance,95-121 doi:10.1007/978-3-658-23765-3_4 wrightson t. 2015 advanced persistent threat hacking art science hacking organization ny ny mcgraw-hill education
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Computer security
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comparison t-carrier e-carrier systems ds designations used connection north american hierarchy strictly speaking ds1 data carried t1 circuit likewise ds3 t3 practice terms used interchangeably data rates use e.g. military systems operate six eight times ds1 rate least one manufacturer commercial system operates 90 mbit/s twice ds3 rate new systems take advantage high data rates offered optical communications links also deployed development higher data rates often achieved using synchronous optical networking sonet synchronous digital hierarchy sdh ds3 delivered native copper trunk ds3 may converted optical fiber run needing longer distances termination points ds3 delivered fiber still analog type trunk connection termination points delivering data oc3 greater sonet used ds3 transported sonet encapsulated sts-1 sonet channel oc-3 sonet link contains three sts-1s therefore may carry three ds3s likewise oc-12 oc-48 oc-192 may carry 12 48 192 ds3s respectively
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Internet protocols
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link contract link contract approach data control distributed data sharing network link contracts key feature xdi specifications development oasis xdi link contract machine-readable xdi document governs sharing xdi data unlike conventional web link essentially one-dimensional string pulls linked document browser link contract graph metadata typically json actively control flow data publisher subscriber either push pull flow controlled terms contract flexible extensible real-world contracts i.e. link contracts govern like real-world contracts link contracts also refer link contracts using design vast majority link contracts simple referring small number complex link contracts carefully designed reflect requirements common data exchange scenarios e.g. business cards mailing lists e-commerce transactions website registrations etc link contracts proposed key element digital trust frameworks published non-profit open identity exchange
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Web technology
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namco system 11 namco system 11 arcade system board released namco 1994 actual hardware based sony playstation home console thus many games ported console major difference two system 11 used surface-mounted rom chips store game data whereas playstation used cd-rom meant system 11 games unique particular system board could swapped another game system 11 succeeded system 12 design although system 11 technically inferior sega model 2 arcade board lower price made attractive prospect smaller arcades according june 1995 issue edge psx based
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Computer architecture
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scalability scalability property system handle growing amount work adding resources system economic context scalable business model implies company increase sales given increased resources example package delivery system scalable packages delivered adding delivery vehicles however packages first pass single warehouse sorting system would scalable one warehouse handle limited number packages computing scalability characteristic computers networks algorithms networking protocols programs applications example search engine must support increasing numbers users number topics indexes incident command system ics emergency management system used across emergency response agencies united states ics scale resource coordination single-engine roadside brushfire interstate wildfire first resource scene establishes command authority order resources delegate responsibility managing five seven officers delegate seven incident grows incident expands senior officers assume command scalability measured multiple dimensions resources fall two broad categories horizontal vertical scaling horizontally out/in means adding nodes removing nodes system adding new computer distributed software application example might involve scaling one web server three high-performance computing applications seismic analysis biotechnology workloads scaled horizontally support tasks would required expensive supercomputers workloads large social networks exceed capacity largest supercomputer handled scalable systems exploiting scalability requires software efficient resource management maintenance scaling vertically up/down means adding resources removing resources single node typically involving addition cpus memory storage single computer larger numbers elements increases management complexity sophisticated programming allocate tasks among resources handle issues throughput latency across nodes applications scale horizontally note network function virtualization defines terms differently scaling out/in ability scale add/remove resource instances e.g virtual machine whereas scaling up/down ability scale changing allocated resources e.g memory/cpu/storage capacity scalability databases requires database system able perform additional work given greater hardware resources additional servers processors memory storage workloads continued grow demands databases followed suit algorithmic innovations include row-level locking table index partitioning architectural innovations include shared nothing shared everything architectures managing multi-server configurations context scale-out data storage scalability defined maximum storage cluster size guarantees full data consistency meaning ever one valid version stored data whole cluster independently number redundant physical data copies clusters provide lazy redundancy updating copies asynchronous fashion called 'eventually consistent type scale-out design suitable availability responsiveness rated higher consistency true many web file hosting services web caches want latest version wait seconds propagate classical transaction-oriented applications design avoided many open source even commercial scale-out storage clusters especially built top standard pc hardware networks provide eventual consistency idem nosql databases like couchdb others mentioned write operations invalidate copies often n't wait acknowledgements read operations typically n't check every redundant copy prior answering potentially missing preceding write operation large amount metadata signal traffic would require specialized hardware short distances handled acceptable performance i.e act like non-clustered storage device database whenever strong data consistency expected look indicators indicators eventually consistent designs suitable transactional applications often advised focus system design hardware scalability rather capacity typically cheaper add new node system order achieve improved performance partake performance tuning improve capacity node handle approach diminishing returns discussed performance engineering example suppose 70 program sped parallelized run multiple cpus instead one formula_1 fraction calculation sequential formula_2 fraction parallelized maximum speedup achieved using p processors given according amdahl law substituting value example using 4 processors get double compute power 8 processors get doubling processing power improved speedup roughly one-fifth whole problem parallelizable speed would also double therefore throwing hardware necessarily optimal approach context high performance computing two common notions scalability
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Computer architecture
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krypton programming language krypton styled krypton frame-based computer programming language
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Programming language topics
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privilege computing computing privilege defined delegation authority perform security-relevant functions computer system privilege allows user perform action security consequences examples various privileges include ability create new user install software change kernel functions users delegated extra levels control called privileged users lack privileges defined unprivileged regular normal users privileges either automatic granted applied automatic privilege exists requirement permission perform action example systems people required log system use logging require privilege systems implement file protection ms-dos essentially give unlimited privilege perform action file granted privilege exists result presenting credential privilege granting authority usually accomplished logging system username password username password supplied correct user granted additional privileges privilege applied either executed program issuing request advanced privileges running program apply additional privileges example user applying additional privileges provided sudo command run command root user kerberos authentication system modern processor architectures multiple cpu modes allows os run different privilege levels processors two levels user supervisor i386+ processors four levels 0 3 least privileges tasks tagged privilege level resources segments pages ports etc privileged instructions tagged demanded privilege level task tries use resource execute privileged instruction processor determines whether permission protection fault interrupt generated prevents user tasks damaging os computer programming exceptions related privileged instruction violations may caused array accessed bounds invalid pointer dereferenced invalid memory location referenced privileged location one controlling device input/output particularly likely occur programming languages c use pointer arithmetic check array bounds automatically unix-like systems superuser commonly known 'root owns privileges ordinary users granted enough permissions accomplish common tasks unix systems built-in security features users set new user account administrative procedures user “ root ” special user something called super-user anything system high degree power necessary fully administer unix system also allows user make mistake cause system problems unprivileged users usually windows nt-based systems privileges delegated varying degrees delegations defined using local security policy manager secpol.msc following abbreviated list default assignments windows defines number administrative privileges assigned individually users and/or groups account user holds privileges granted either directly indirectly group memberships upon installation number groups accounts created privileges granted however grants changed later time though group policy unlike linux privileges implicitly permanently granted specific account administrative privileges e.g taking ownership restoring arbitrary files powerful used malicious intent could allow entire system compromised user account control default since windows vista windows strip user token privileges login thus user logs account broad system privileges he/she still running system privileges whenever user wants perform administrative actions requiring system privileges he/she elevated process launching elevated process user made aware his/her administrative privileges asserted prompt requiring his/her consent holding privileges actually required keeping principle least privilege elevated processes run full privileges user full privileges system even privileges user may still required particular process thus completely least privilege dos-based windows windows 98 windows 95 previous versions non-nt windows operated fat filesystem support filesystem permissions. therefore privileges effectively defeated windows nt-based systems use ntfs file system names used windows source code end either privilege logonright led confusion full set rights privileges called microsoft currently uses term user rights past terms also used microsoft privilege rights logon user rights nt-rights
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Operating systems
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s-expression computing s-expressions sexprs sexps symbolic expression notation nested list tree-structured data invented popularized programming language lisp uses source code well data usual parenthesized syntax lisp s-expression classically defined second recursive part definition represents ordered pair means s-expressions binary trees definition atom varies per context original definition john mccarthy assumed existed infinite set distinguishable atomic symbols represented strings capital latin letters digits single embedded blanks i.e. character string numeric literals modern sexpr notations addition use abbreviated notation represent lists s-expressions stands codice_4 special end-of-list object alternatively written codice_5 representation scheme lisp family programming languages s-expressions used represent source code data uses s-expressions lisp-derived languages dsssl mark-up communications protocols like imap john mccarthy cbcl details syntax supported data types vary different languages common feature among languages use s-expressions prefix notation many variants s-expression format supporting variety different syntaxes different datatypes widely supported character codice_15 often used prefix extensions syntax e.g codice_16 hexadecimal integers codice_17 characters representing source code lisp first element s-expression commonly operator function name remaining elements treated arguments called prefix notation polish notation example boolean expression written codice_18 c represented codice_19 lisp s-expr-based prefix notation noted precise definition atom varies across lisp-like languages quoted string typically contain anything quote unquoted identifier atom typically contain anything quote whitespace characters parenthesis brackets braces backslash semicolon either case prohibited character typically included escaping preceding backslash unicode support varies recursive case s-expr definition traditionally implemented using cons cells s-expressions originally intended data manipulated m-expressions first implementation lisp interpreter s-expression encodings m-expressions lisp programmers soon became accustomed using s-expressions code data means lisp homoiconic primary representation programs also data structure primitive type language nested lists written s-expressions codice_20 two-element s-expression whose elements also two-element s-expressions whitespace-separated notation used lisp article typical line breaks newline characters usually qualify separators simple context-free grammar tiny subset english written s-expression gazdar/melish natural language processing lisp s=sentence np=noun phrase vp=verb phrase v=verb program code written s-expressions usually using prefix notation example common lisp s-expressions read lisp using function read read reads textual representation s-expression returns lisp data function print used output s-expression output read function read printed data objects readable representation lisp readable representations numbers strings symbols lists many data types program code formatted pretty printed s-expressions using function pprint note two ps short pretty -print lisp programs valid s-expressions s-expressions valid lisp programs codice_21 valid s-expression valid lisp program since lisp uses prefix notation floating point number 1.0 valid operation first element expression s-expression preceded single quotation mark codice_22 syntactic sugar quoted s-expression case codice_23 s-expressions often compared xml key difference s-expressions far simpler syntax therefore much easier parse standards lisp-derived programming languages include specification s-expression syntax include common lisp ansi standard document ansi incits 226-1994 r2004 scheme r5rs r6rs islisp may 1997 ron rivest submitted internet-draft considered publication rfc draft defined syntax based lisp s-expressions intended general-purpose data storage exchange similar xml rather specifically programming never approved rfc since cited used rfcs e.g rfc 2693 several publications originally intended use spki rivest format defines s-expression either octet-string series bytes finite list s-expressions describes three interchange formats expressing structure one advanced transport flexible terms formatting syntactically similar lisp-style expressions identical advanced transport example allows octet-strings represented verbatim string length followed colon entire raw string quoted form allowing escape characters hexadecimal base64 placed directly token meets certain conditions rivest tokens differ lisp tokens former convenience aesthetics treated exactly like strings latter specific syntactical meaning rivest draft defines canonical representation digital signature purposes intended compact easier parse unique abstract s-expression allows verbatim strings prohibits whitespace formatting outside strings finally basic transport representation either canonical form encoded base64 surrounded braces latter intended safely transport canonically encoded s-expression system might change spacing e.g email system 80-character-wide lines wraps anything longer format widely adapted use outside spki users gnupg libgcrypt nettle gnu lsh rivest s-expressions web page provides c source code parser generator available mit license could adapted embedded programs addition restrictions independently implementing format
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Programming language topics
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next next inc. later next computer inc. next software inc. american computer software company founded 1985 apple computer co-founder steve jobs name usually pronounced next based redwood city california company developed manufactured series computer workstations intended higher education business markets next founded jobs fired apple along several co-workers next introduced first next computer 1988 smaller nextstation 1990 next computers experienced relatively limited sales estimates 50,000 units shipped total nevertheless innovative object-oriented nextstep operating system development environment interface builder highly influential first major outside investment ross perot invested seeing segment next entrepreneurs 1987 invested 20 million exchange 16 percent next stock subsequently joined board directors 1988 next later released much nextstep system programming environment standard called openstep next withdrew hardware business 1993 concentrate marketing openstep mach openstep implementation several original equipment manufacturers oems next also developed webobjects one first enterprise web application frameworks webobjects never became popular initial high price 50,000 remains prominent early example web server based dynamic page generation rather static content apple purchased next 1997 429 million equivalent million 1.5 million shares apple stock part agreement steve jobs chairman ceo next software returned apple company co-founded 1976 founder promised merge software next apple hardware platforms eventually resulting macos ios watchos tvos operating systems completely based upon nextstep openstep foundation 1985 apple co-founder steve jobs led apple supermicro division responsible development macintosh lisa personal computers macintosh successful university campuses partly apple university consortium allowed students institutions buy computers discount consortium earned 50 million computers february 1984 chairman jobs visited university departments faculty members sell macintosh jobs met paul berg nobel laureate chemistry luncheon held silicon valley honor françois mitterrand president france berg frustrated expense teaching students recombinant dna textbooks instead wet laboratories used testing analysis chemicals drugs materials biological matter wet labs prohibitively expensive lower-level courses complex simulated personal computers time berg suggested jobs use influence apple create 3m computer workstation higher education featuring least one megabyte random-access memory ram megapixel display megaflops performance hence name 3m jobs intrigued berg concept workstation contemplated starting higher education computer company fall 1985 amidst increasing turmoil apple jobs division release upgraded versions macintosh much macintosh office system result sales plummeted apple forced write millions dollars unsold inventory apple chief executive officer ceo john sculley ousted jobs day-to-day role apple replacing jean-louis gassée 1985 later year jobs began power struggle regain control company board directors sided sculley jobs took business visit western europe soviet union behalf apple several months sidelined jobs resigned apple september 13 1985 told board leaving set new computer company would taking several apple employees supermicro division also told board new company would compete apple might even consider licensing designs back market macintosh brand jobs named new company next inc. number former apple employees followed next including joanna hoffman bud tribble george crow rich page susan barnes susan kare dan l lewin consulting major educational buyers around country including follow-up meeting paul berg tentative specification workstation drawn designed powerful enough run wet lab simulations cheap enough college students use dormitory rooms specifications finished however apple sued next nefarious schemes take advantage cofounders insider information jobs remarked hard think 2 billion company 4,300-plus people could n't compete six people blue jeans suit eventually dismissed trial 1986 jobs recruited famous graphic designer paul rand create brand identity costing 100,000 jobs recalled asked would come options said 'no solve problem pay ’ use solution want options go talk people rand created 20-page brochure detailing brand including precise angle used logo 28° new company name spelling next next changed business plan mid-1986 company decided develop computer hardware software instead low-end workstation team led avie tevanian joined company working one mach kernel engineers carnegie mellon university develop nextstep operating system hardware division led rich page — one cofounders previously led apple lisa team — designed developed hardware next first factory completed fremont california 1987 capable producing 150,000 machines per year next first workstation officially named next computer although widely termed cube distinctive case 1 ft magnesium cube designed apple iic case designer frogdesign accordance edict jobs original design team anticipated releasing computer us 3,000 spring 1987 ready sale summer year next computer received standing ovations revealed lavish invitation-only gala event next introduction — introduction next generation computers education louise m. davies symphony hall san francisco california wednesday october 12 1988 following day selected educators software developers invited 100 registration fee attend first public technical overview next computer event called next day held san francisco hilton event gave developers interested developing next software insight software architecture object-oriented programming developing next computer luncheon speaker steve jobs first machines tested 1989 next started selling limited numbers universities beta version nextstep operating system installed initially next computer targeted u.s. higher education establishments base price 6,500 machine widely reviewed magazines generally concentrating hardware asked upset computer debut delayed several months jobs responded late computer five years ahead time next computer based new 25 mhz motorola 68030 central processing unit cpu motorola 88000 risc chip originally considered available sufficient quantities included 8 64 mb random-access memory ram 256 mb magneto-optical mo drive 40 mb swap-only 330 mb 660 mb hard disk drive 10base2 ethernet nubus 17-inch megapixel grayscale display measuring 1120 832 pixels 1989 typical new pc macintosh amiga computer included megabytes ram 640×480 16-color 320x240 4000-color display 10 20 megabyte hard drive networking capabilities also first computer ship general-purpose dsp chip motorola 56001 motherboard used support sophisticated music sound processing including music kit software magneto-optical drive manufactured canon inc. used primary mass storage device drives relatively new market next first computer use cheaper hard drives blank media especially though cost 150 canon jobs negotiations saw canon agree retail 50 apiece slower average seek time 96 ms design made impossible move files computers without network since next computer one mo drive disk could removed without shutting system storage options proved challenging first next computers magneto-optical media relatively expensive performance reliability problems despite faster floppy drive drive sufficient run primary medium running nextstep operating system terms speed capacity 1989 next struck deal former compaq reseller businessland sell next computers select markets nationwide selling retailer major change next original business model selling directly students educational institutions businessland founder david norman predicted sales next computer would surpass sales compaq computers 12 months 1989 canon invested us 100 million next giving 16.67 percent stake making next worth almost 600 million canon invested next condition would able use nextstep environment workstations would mean greatly expanded market software next exited hardware business canon produced line pcs called object.station including models 31 41 50 52 specifically designed run nextstep/intel canon also served next distributor japan next computers first released retail market 1990 9,999 next original investor ross perot resigned board directors june 1991 dedicate time perot systems plano texas-based systems integrator next released second generation workstations 1990 new range included revised next computer renamed nextcube nextstation nicknamed slab pizza box case form-factor jobs explicit ensuring next staff use latter terminology lest next machines compared competing sun workstations already nickname magneto-optical drive replaced 2.88 mb floppy drive 2.88 mb floppy disks expensive technology supplant 1.44 mb floppy realizing next utilized cd-rom drive eventually became industry standard storage color graphics available nextstation color nextdimension graphics processor hardware nextcube new computers cheaper faster predecessors new motorola 68040 processor 1992 next launched turbo variants nextcube nextstation 33 mhz 68040 processor maximum ram capacity increased 128 mb next sold 20,000 computers 1992 next counted upgraded motherboards back order system sales — small number compared competitors however company reported sales 140 million year encouraging canon invest 30 million keep company afloat total 50,000 next machines sold including thousands super secret national reconnaissance office located chantilly virginia next long-term aim migrate risc reduced instruction set computing architecture processor design strategy intended increase performance project known next risc workstation nrw initially nrw based motorola 88110 processor due lack confidence motorola commitment 88000-series architecture later redesigned around dual powerpc 601s next produced motherboards enclosures exited hardware business full production next computers delivered mathematica pre-installed several developers used next platform write pioneering programs tim berners-lee used next computer 1990 create first web browser web server accordingly next instrumental development world wide web next used professors scientific engineering applications developing finished newspaper layouts using news george mason university early 1990s set next workstations publishing well silicon graphics cad/gl mathematica astrophysics games doom quake developed id software next machines games based doom engine heretic raven software well strife rogue entertainment also developed next hardware using id tools commercial programs released next computers including altsys virtuoso vector drawing program page-layout features ported mac os microsoft windows aldus freehand v4 lotus improv spreadsheet program systems bundled number smaller built-in applications merriam-webster collegiate dictionary oxford quotations complete works william shakespeare digital librarian search engine access next started porting nextstep operating system ibm pc compatible computers using intel 80486 processor late 1991 change business strategy withdraw hardware business entirely demonstration port displayed nextworld expo january 1992 mid-1993 product complete version 3.1 also known nextstep 486 released prior release chrysler planned buy 3,000 copies 1992 nextstep 3.x later ported pa-risc sparc-based platforms total four versions nextstep/next next 68k black boxes nextstep/intel nextstep/pa-risc nextstep/sparc although ports widely used nextstep gained popularity institutions first chicago nbd swiss bank corporation o'connor company organizations owing programming model used many american federal agencies united states naval research laboratory national security agency advanced research projects agency central intelligence agency national reconnaissance office ibm pc clone vendors offered somewhat customized hardware solutions delivered running nextstep intel elonex nextstation canon object.station 41 next withdrew hardware business 1993 company renamed next software inc consequently 300 540 staff employees laid next negotiated sell hardware business including fremont factory canon later pulled deal work powerpc machines stopped along hardware production ceo sun microsystems scott mcnealy announced plans invest 10 million 1993 use next software future sun systems next partnered sun create openstep nextstep application layer hosted third party operating system exiting hardware business next focused operating systems effect returning original business plan new products based openstep released including openstep enterprise version microsoft windows nt company launched webobjects platform building large-scale dynamic web applications many large businesses including dell disney worldcom bbc used webobjects short time eventually webobjects used solely power apple itunes store corporate website discontinuing apple computer announced intention acquire next december 20 1996 apple paid 429 million cash went initial investors 1.5 million apple shares went steve jobs deliberately given cash part deal main purpose acquisition use nextstep foundation replace dated classic mac os instead beos in-development copland deal finalized february 7 1997 bringing jobs back apple consultant later appointed interim ceo 2000 jobs took ceo position permanent assignment holding position resignation august 24 2011 jobs died six weeks later october 5 2011 complications relapsed pancreatic neuroendocrine tumor several next executives replaced apple counterparts steve jobs restructured company board directors next five years nextstep operating system ported powerpc architecture time intel port openstep enterprise toolkit windows produced operating system code named rhapsody toolkit development platforms called yellow box backwards compatibility apple added blue box rhapsody allowing existing mac applications run self-contained cooperative multitasking environment server version new operating system released mac os x server 1.0 1999 first consumer version mac os x 10.0 2001 openstep developer toolkit renamed cocoa rhapsody blue box renamed classic environment changed run applications full-screen without requiring separate window apple included updated version original macintosh toolbox called carbon gave existing mac applications access environment without constraints blue box nextstep interface features used mac os x including dock services menu finder column view cocoa text system nextstep processor-independent capabilities retained mac os x leading powerpc intel x86 versions although powerpc versions publicly available 2006 apple moved intel processors august 2006 jobs created different corporate culture next terms facilities salaries benefits jobs experimented structural changes apple next abandoned conventional corporate structures instead making community members instead employees two different salaries next early 1990s team members joined 1986 paid 75,000 joined afterwards paid 50,000 caused awkward situations managers paid less employees employees given performance reviews raises every six months spartan salary plans foster openness employees full access payrolls although employees ever took advantage privilege next health insurance plan offered benefits married couples unmarried couples same-sex couples although latter privilege later withdrawn due insurance complications payroll schedule also different companies silicon valley time instead getting paid twice month arrears end pay period employees would get paid month advance beginning words jobs found office space palo alto california 3475 deer creek road occupying glass concrete building featured staircase designed architect i. m. pei first floor used hardwood flooring large worktables workstations would assembled avoid inventory errors next used just-in-time jit inventory strategy company contracted major components mainboards cases finished components shipped first floor assembly second floor office space open floor plan enclosed rooms jobs office conference rooms next expanded office space needed company rented office 800 900 chesapeake drive redwood city also designed pei architectural centerpiece floating staircase visible supports open floor plan retained although furnishings became luxurious 5,000 chairs 10,000 sofas ansel adams prints next first campus palo alto subsequently occupied sap ag second campus redwood city occupied apnicure oncomed pharmaceuticals inc first issue nextworld magazine printed 1991 published san francisco integrated media edited michael miley later dan ruby mainstream periodical discuss next computers operating system next software publication discontinued 1994 four volumes nextworld expo followed developer conference held 1991 1992 san francisco civic center 1993 1994 moscone center san francisco steve jobs keynote speaker though profitable company wide-ranging impact computer industry object-oriented programming graphical user interfaces became common 1988 release nextcube nextstep technologically successful platform often held trendsetter companies started emulate success next object-oriented system widely seen response next microsoft announced cairo project 1991 cairo specification included similar object-oriented user interface features coming consumer version windows nt although cairo ultimately abandoned elements integrated projects 1994 microsoft next collaborating windows nt port openstep never released 1993 taligent considered press competitor objects operating systems even without product release next main point comparison first years taligent theoretical newness often compared next older mature commercially established platform taligent debut release 1995 called little late especially compared next webobjects failed achieve wide popularity partly initial high price us 50,000 remains first prominent early example web application server enabled dynamic page generation based user interactions opposed static content webobjects bundled macos server xcode
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Operating systems
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seeks seeks free open-source project licensed affero general public license version 3 agplv3 exists create alternative current market-leading search engines driven user concerns rather corporate interests original manifesto created emmanuel benazera sylvio drouin published october 2006 project active development april 2014 stable releases engine revisions source code available public use september 2011 seeks innovation award open world forum innovation awards seeks source code updated since april 28 2014 seeks nodes usable since february 6 2016 seeks aims give control ranking results users search algorithms often less accurate humans relies distributed collaborative filter let users personalize share preferred results search also openness source code users verify modify collaborative filter fit needs currently seeks used three main forms
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Distributed computing architecture
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greg morrisett john gregory greg morrisett dean faculty computing information science cornell university morrisett allen b cutting professor computer science harvard school engineering applied sciences prior position cornell group cornell university created cyclone programming language current research interests applications programming language technology building secure reliable systems particular interested applications advanced type systems model checkers certifying compilers proof-carrying code inlined reference monitors building efficient provably secure systems also interested design application high-level languages new emerging domains sensor networks received phd jeannette wing robert harper carnegie mellon university 1995 2013 became fellow association computing machinery
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Programming language topics
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kaspersky lab kaspersky lab russian лаборатория касперского laboratoriya kasperskogo multinational cybersecurity anti-virus provider headquartered moscow russia operated holding company united kingdom founded 1997 eugene kaspersky natalya kaspersky alexey de-monderik eugene kaspersky currently ceo kaspersky lab develops sells antivirus internet security password management endpoint security cybersecurity products services kaspersky expanded abroad 2005–2010 grew 698 million annual revenues 2017 8 2016 though annual revenues 8 north america due u.s. government security concerns 2016 software 400 million users largest market-share cybersecurity software vendors europe kaspersky lab ranks fourth global ranking antivirus vendors revenue first russian company included rating world leading software companies called software top 100 79th list 6/29/2012 kaspersky lab ranked 4th endpoint security segment according idc data 2010 according gartner kaspersky lab currently third largest vendor consumer security software worldwide fifth largest vendor enterprise endpoint protection kaspersky lab named leader gartner magic quadrant endpoint protection platforms kaspersky global research analysis team great led discovery sophisticated espionage platforms conducted nations equation group stuxnet worm various covert government-sponsored cyber-espionage efforts uncovered research kaspersky also publishes annual global security risks survey 2014 kaspersky research hubs analyze 350,000 malware samples per day kaspersky faced controversy allegations engaged russian federal security service fsb —ties company actively denied u.s. department homeland security banned kaspersky products government departments 13 september 2017 october 2017 subsequent reports alleged hackers working russian government stole confidential data home computer american national security agency contractor via kaspersky antivirus software kaspersky denied allegations reporting software detected equation group malware samples uploaded servers analysis normal course operation company since announced commitments increased accountability soliciting independent reviews verification software source code announcing would migrate core infrastructure foreign customers russia switzerland first version kaspersky lab antivirus software developed eugene kaspersky 1989 response cascade virus early versions 40 virus definitions mostly distributed friends family members eugene continued developing software kami resulting antiviral toolkit pro avp product released 1992 popularized 1994 competitive analysis hamburg university gave eugene software first place 1997 eugene kaspersky wife natalya kaspersky alexey de-monderik left kami form kaspersky lab continue developing antivirus product called avp product renamed kaspersky anti-virus american company registered avp trademark us 1998 taiwanese student released virus called cih first three weeks outbreak kaspersky lab avp software time able remove increased demand led deals antivirus companies japan finland germany integrate avp software according wired kaspersky software advanced time example first software monitor viruses isolated quarantine company revenue grew 280 percent 1998 2000 60 percent revenue coming foreign sales natalya worked broker deals abroad localize software opened offices uk poland holland china later expanded germany france us japan 2000 company 65 employees sales 40 countries kaspersky opened new offices south east asia middle east 2008 south africa 2009 also expanded india middle east africa 2010 2009 retail sales kaspersky lab antivirus products reached almost 4.5 million copies per year 2011 general atlantic bought 20 percent share kaspersky lab 200 million expectation helping company go public months later decision made keep firm private kaspersky re-purchased shares general atlantic followed numerous executive departures 2011 2014 regarding disputes going public eugene management style january 1 2012 kaspersky lab officially left business software alliance bsa sopa bsa supported controversial anti-piracy bill kaspersky lab support stating believe measures used contrary modern advances technology needs consumers show disapproval announced intent leave december 5 2011 2013 company unaudited 667 million annual revenues 2014 kaspersky lab signed distribution deal ingram micro significantly expanded reseller program august 2015 two former kaspersky employees alleged company introduced modified files virustotal antivirus database trick software kaspersky competitors triggering false positives virus malware scans possible motive eugene allegedly furious competitors perceived unfairly free-riding kaspersky malware discoveries via open-source virustotal database company denied allegations personal blog eugene kaspersky compared accusations unsubstantiated conspiracy theories reuters followed publishing leaked emails allegedly kaspersky alluding falsies rubbing foreign competitors kaspersky lab stated emails may legitimate obtained anonymous sources hidden agenda 2016 kaspersky executive ruslan stoyanov arrested russian authorities charges predating work kaspersky 2019 convicted treason kaspersky lab develops markets antivirus internet security password management endpoint security cybersecurity products services fourth fifth largest endpoint security vendor third largest consumer security software company sixth largest overall security company revenues 15 percent russian companies domestically one-third european organizations one-fourth u.s. organizations software 400 million users kaspersky consumer software include antivirus internet security total security products antivirus software includes malware protection monitors pc suspicious program behavior warns users potentially dangerous websites internet security software adds privacy features parental controls anti-phishing tools total security adds parental controls adult website filters diagnostic tools password manager application features kaspersky software available macs pcs android ios windows mobile blackberry symbian businesses company markets kaspersky endpoint security business suite includes centralized user interface management application called kaspersky security center cybersecurity software called kaspersky security network kaspersky administration kitsecurity center manages configuration installation remote use business suite also quarantine reporting features software product businesses 25 staff less called kaspersky small office security ksos within suite products specifically virtualization security mobile security fraud protection among others kaspersky also develops free tool helps businesses gain access windows devices infected ransomware kaspersky anti-virus engine also powers products solutions security vendors check point bluecoat juniper networks microsoft forefront netintelligence clearswift frontbridge netasq wedge networks others altogether 120 companies licensing technology kaspersky lab kaspersky lab also number partnerships various technology companies international multilateral partnership cyber threats datuk mohd noor amin acts chairman announced appointment harry cheung – managing director kaspersky lab apac – goodwill ambassador greater china kaspersky lab runs several global sponsorships example scuderia ferrari racing team geographical expeditions according pc magazine kaspersky antivirus competitor bitdefender consistently ranked top independent competitive tests pc magazine malware phishing tests similar results praised software bonus security tools cons magazine said took longer-than-expected complete scan magazine said kaspersky total security product impressive feature list praised extra features total security product like password management encryption parental controls pc magazine said product scored highly lab tests antivirus antiphishing features so-so scores antimalware tests n't able catch spam kaspersky 2013 endpoint security windows product top-ranked enterprise antivirus software competitive test dennis technology labs followed symantec endpoint protection av-comparatives awarded kaspersky product year 2015 based number high scores gotten throughout year wide range tests pc magazine praised software features said lacked policy management deployment options kaspersky parental controls software reviewed pc magazine reviewer said well-rounded affordable parental control monitoring praised software content filtering child profiles social media monitoring features criticize features available ios android anti-virus software testing group av-comparatives gave windows xp version kaspersky av advanced+ rating highest february 2008 on-demand detection test fourth highest detection rate among 16 products tested however retrospective/proactive test may 2008 kaspersky received standard rating detecting 21 new malware 1-month old signatures receiving substantial amount false positives firewall included kaspersky internet security 7.0 got good rating matousec firewall challenge result 85 kaspersky anti-virus 7.0 achieved 6.5 result 8 anti malware labs rootkit detection test also achieved 31 33 detection polymorphic viruses 97 result self-protection test 2007 kaspersky internet security 7 received award british magazine pc pro also place list kaspersky passed virus bulletin comparative tests since august 2003 2005 according pc world magazine kaspersky anti-virus software provided fastest updates new virus security threats industry pc world magazine march 2010 comparison consumer security suites kaspersky internet security 2010 scored 4.5/5 stars rated second overall december 2011 version av-comparatives annual reports kaspersky lab software achieved highest overall ranking earned av comparatives product year award 1 february 2012 kaspersky internet security earned av-test award best repair 2011 award field home user products av-test institute 28 january 2013 kaspersky endpoint security earned av-test award best protection 2012 av-test award best repair 2012 awards field corporate products av-test institute later 2013 kaspersky earned product year award av-comparatives highest score among enterprise solutions dennis technology labs report kaspersky also received certification products oesis ok certification program verifies applications interoperable third-party technology solutions like nac ssl vpn products cisco systems juniper networks f5 networks others kaspersky lab global research analysis team great established 2008 investigates cybersecurity threats work malware operations security companies often evaluated ability uncover previously unknown viruses vulnerabilities kaspersky reputation investigating cyber-security threats influential gaining sales prestige beginning around 2010 kaspersky exposed series government-sponsored cyber-espionage sabotage efforts include stuxnet duqu flame gauss regin equation group according wired many seemingly launched us uk israeli allies kaspersky especially well-known work uncovering stuxnet flame 2010 kaspersky lab worked microsoft counter-act stuxnet worm infected 14 industrial locations iran using four zero-day vulnerabilities microsoft windows according ieee spectrum circumstances strongly suggest worm developed united states israel damage centrifuges iran nuclear-enrichment program first discovery major government-sponsored cyber-attack may 2012 kaspersky lab identified malware flame researcher described potentially sophisticated cyber weapon yet unleashed according researchers kaspersky lab malware infected estimated 1,000 5,000 machines worldwide asked united nations international telecommunications union investigate reports virus affecting iranian oil ministry computers kaspersky lab investigated discovered md5 hash filename appeared customer machines middle eastern nations discovering pieces researchers dubbed program flame name one modules flame earlier variant stuxnet kaspersky never verified source software suspected developed national security agency nsa transmit keystrokes skype calls data kaspersky created algorithms find similar malware found gauss july collected transmitted data devices infected bluetooth usb drives january 2013 kaspersky discovered red october malware used widespread cyber-espionage five years targeted political targets like embassies nuclear sites mostly europe switzerland north america malware likely written russian-speaking hackers exploits chinese hackers june kaspersky discovered nettraveler said obtaining data emerging technology government targets oil companies kaspersky identify behind similar cyber-espionage coming beijing china later year kaspersky discovered hacker group called icefog investigating cybersecurity attack japanese television company kaspersky said hacker group possibly china unique targeted specific files seemed know planting malware extract february 2014 kaspersky identified malware mask infected 380 organizations 31 countries many organizations affected morocco files spanish group believed nation-state conducting espionage kaspersky speculate country may developed november 2014 symantec kaspersky authored papers contained first disclosure malicious software named regin according kaspersky regin similar qwerty malware program discovered next year regin used take remote control computer believed originated five eyes alliance month kaspersky reported darkhotel attack targeted users wireless networks hotels asia asked users update software downloaded malware gave passwords 2015 kaspersky identified highly sophisticated threat actor called equation group group incorporated sophisticated spying software firmware hard drives banks government agencies nuclear researchers military facilities countries frequent targets us intelligence efforts suspected developed national security agency nsa included many unique technical achievements better avoid detection day kaspersky announced discovery hacker group called carbanak targeting banks moving millions dollars fake accounts carbanak discovered one bank asked kaspersky investigate suspicious behavior atms similar malware using techniques carbanak discovered 2016 dubbed carbanak 2.0 june 2015 kaspersky reported network infiltrated government-sponsored malware evidence suggested malware created developers duqu stuxnet order get intelligence would help better avoid detection kaspersky future kaspersky called duqu 2.0 malicious software resided memory avoid detection hack believed done group duqu 2011 used exploits microsoft installer files june 2015 kaspersky lab citizen lab independently discovered software developed hacking team used 60 governments around world covertly record data mobile phones citizens software gave police enforcement menu features access emails text messages keystrokes call history data kaspersky also identified 37,000 attacks banking companies used modifications malware called asacub took control android devices asacub targeted mostly banking customers u.s. russia ukraine using sms message baited users installing trojan 2016 kaspersky discovered zero day vulnerability microsoft silverlight kaspersky identified string code often used exploits created suspected author used yara rules network kaspersky software users find string code uncover rest exploit afterwards microsoft issued critical software patch protect software vulnerability 2016 kaspersky uncovered poseidon group would infiltrate corporations malware using phishing emails get hired company security firm correct problem hired poseidon would install additional malware backdoors june 2016 kaspersky helped uncover russian hacking group leading 50 arrests since 2015 kaspersky alleged close ties russian government various western media outlets finally us government 2017 president trump signed legislation ban software kaspersky government computers us government institutions prohibited buying installing kaspersky software computers devices
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Computer security
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ntfsresize ntfsresize free unix utility non-destructively resizes ntfs filesystem used windows nt 4.0 2000 xp 2003 vista 7 8 10 typically hard-disk partition ntfs versions used 32-bit 64-bit windows supported defragmentation required prior resizing since version 1.11.2. ntfsresize included ntfsprogs package developed linux-ntfs project n't unix system installed still possible run ntfsresize using one many linux live cds
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Computer file systems
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inap inap stands intelligent network application protocol intelligent network application part signalling protocol used intelligent networking part signalling system 7 ss7 protocol suite typically layered top transaction capabilities application part tcap also termed logic controlling telecommunication services migrated traditional switching points computer based service independent platform international telecommunication union itu defines several capability levels protocol starting capability set 1 cs-1 typical application number translation service example united kingdom 0800 numbers freephone numbers translated geographic number using platform telephone exchanges decode 0800 numbers trigger exchange connects telephone exchange uses transaction capabilities application part tcap signaling connection control part sccp inap terms service switching point ssp sends inap initial detection point idp message service control point scp scp returns inap connect message contains geographic number forward call inap messages defined using asn.1 encoding sccp used routing extended form inap customised applications mobile networks enhanced logic camel tcap used separate transactions discrete units
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Internet protocols
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linux range use linux kernel-based operating systems widely adopted wide range uses advantages benefits free open-source software apply linux kernel rest system software common human interface devices hids available desktop computers laptops similar devices determine design graphical human-computer interface implemented software software packages choose among building accordingly designed graphical user interface generic input driver linux kernel evdev several input methods implemented middleware i.e. atop part linux kernel adoption proving linux kernel suitable gaming platform course added software needed either augment typical desktop installation suitable gaming platform create linux-based operating system dedicated gaming platform abundance server software cf client–server model supporting various communications protocols http web server smtp mail transfer agents pop3 imap e-mail server lightweight directory access protocol ldap server message block smb-cifs samba simple network management protocol snmp system network monitoring session initiation protocol sip various routing protocols run partly exclusively linux kernel software bundles also called solution stacks widely adopted acronyms become well known examples include dynamic web pages cloud computing three types virtualization hardware-based software-based paravirtualization implemented projects run linux linux-exclusive linux kernel customized adapted hardened various scenarios especially operation bastion host already mainlined developed maintained out-of-tree linux kernel-based operating systems still employed routing servers server computers commodity hardware cases professional routing equipment cisco catalyst either overkill costly components linux kernel netfilter linux network scheduler along available free open-source routing daemons bird internet routing daemon bird b.a.t.m.a.n. quagga xorp fulfill task well low-cost low-performance routing performed wireless routers running openwrt anonymity routing solution tor cross-platform exclusive linux components linux kernel logical volume manager lvm well suited support computer clusters also software managing clusters e.g. pacemaker linux-ha drbd ovirt openqrm ganeti eucalyptus appscale opennebula single system image multi system image clusters least linuxpmi openssi open-sharedroot diskless shared-root cluster kerrighed available three solutions operating-system-level virtualization linux-vserver lxc openvz offer similarities freebsd jails solaris containers linux operating systems runs virtualized xen micro-kernel-type hypervisor published license linux kernel gnu gpl 2.0 kvm possible turn linux kernel hypervisor managing libvirt libguestfs several utilities building programs openstack controller nodes run exclusively linux compute nodes cross-platform software projects serving similar use-case openstack nimbus ganeti appscale opennebula eucalyptus openqrm one best known linux-based operating systems mobile devices smartphones android operating system android employs modified linux kernel combines libbionic instead glibc surfaceflinger display server replacements specifically written purpose many mobile devices touchscreen sole human interface device hid gui partly middleware operating system adapted enable software designers create according human-computer interface linux kernel gained wide use operating systems used embedded systems real-time non-real-time variants patches exist transform linux kernel real-time kernel termed real-time operating system rtos several actively maintained minimally operating system includes less modified linux kernel uclibc busybox non-rtos variants exist openwrt also linux distribution use customer-premises equipment cpe devices like wireless routers rockbox based μclinux operating system portable media players fastest supercomputers decade since earth simulator used linux linux also ran first teraflops supercomputer asci red 1997 ibm roadrunner 2008 first petascale computer 500 100 world fastest supercomputers run operating system based linux kernel world ’ fastest supercomputer china ’ sunway taihulight powered colossal 650,000+ cpus runs customised version linux called ‘ sunway raiseos ’ processing speed 93 petaflops
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Operating systems
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suricata software suricata open source-based intrusion detection system ids intrusion prevention system ips developed open information security foundation oisf beta version released december 2009 first standard release following july 2010 third-party tools available snort compatible suricata like following
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Computer security
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kernel preemption kernel preemption method used mainly monolithic hybrid kernels device drivers run kernel space whereby scheduler permitted forcibly perform context switch i.e preemptively schedule behalf runnable higher priority process driver part kernel execution rather co-operatively waiting driver kernel function system call complete execution return control processor scheduler two main benefits method monolithic hybrid kernels answer one main criticisms monolithic kernels microkernel advocates
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Computer architecture
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inverse multiplexing atm inverse multiplexing atm ima standardized technology used transport atm traffic bundle t1 e1 lines called ima group allows gradual increase data link capacity implementing higher capacity solution like t3/e3 sonet/sdh deemed feasible maximum number lines ima group 32 bringing total data rate roughly 64 mbit/s standard specification initially approved atm forum july 1997 later updated version 1.1 march 1999 atm cell insertion happens round robin fashion transparent terminal equipment ends link ima inverse multiplexing functionality requires overhead icp ima control protocol cells typically one icp cell every ima frame—commonly 128 cells length—and ctc common transmit clock mode icp stuff cell must inserted every 2048 cells ima sublayer physical layer
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Internet protocols
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bigtable bigtable compressed high performance proprietary data storage system built google file system chubby lock service sstable log-structured storage like leveldb google technologies may 6 2015 public version bigtable made available service bigtable also underlies google cloud datastore available part google cloud platform bigtable development began 2004 used number google applications web indexing mapreduce often used generating modifying data stored bigtable google maps google book search search history google earth blogger.com google code hosting youtube gmail google reasons developing database include scalability better control performance characteristics google spanner rdbms layered implementation bigtable paxos group two-phase commits table google f1 built using spanner replace implementation based mysql bigtable one prototypical examples wide column store maps two arbitrary string values row key column key timestamp hence three-dimensional mapping associated arbitrary byte array relational database better defined sparse distributed multi-dimensional sorted map bigtable designed scale petabyte range across hundreds thousands machines make easy add machines system automatically start taking advantage resources without reconfiguration example google copy web stored bigtable row key domain-reversed url columns describe various properties web page one particular column holding page page column several timestamped versions describing different copies web page timestamped fetched cell bigtable zero timestamped versions data another function timestamp allow versioning garbage collection expired data tables split multiple tablets – segments table split certain row keys tablet hundred megabytes gigabytes size bigtable somewhat like mapreduce worker pool thousands hundreds thousands tablet shards may served hundreds thousands bigtable servers table size threaten grow beyond specified limit tablets may compressed using algorithm bmdiff zippy compression algorithm publicly known open-sourced snappy less space-optimal variation lz77 efficient terms computing time locations gfs tablets recorded database entries multiple special tablets called meta1 tablets meta1 tablets found querying single meta0 tablet typically resides server since often queried clients location meta1 tablet answer question actual data located like gfs master server meta0 server generally bottleneck since processor time bandwidth necessary discover transmit meta1 locations minimal clients aggressively cache locations minimize queries
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Databases
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path mtu discovery path mtu discovery pmtud standardized technique computer networking determining maximum transmission unit mtu size network path two internet protocol ip hosts usually goal avoiding ip fragmentation pmtud originally intended routers internet protocol version 4 ipv4 however modern operating systems use endpoints ipv6 function explicitly delegated end points communications session pmtud standardized ipv4 rfc 1191 ipv6 rfc 8201 obsoleted rfc 1981 previous ipv6 pmtud standard rfc 4821 describes extension techniques works without support internet control message protocol ipv4 packets path mtu discovery works setting n't fragment df flag bit ip headers outgoing packets device along path whose mtu smaller packet drop send back internet control message protocol icmp fragmentation needed type 3 code 4 message containing mtu allowing source host reduce path mtu appropriately process repeated mtu small enough traverse entire path without fragmentation ipv6 routers support fragmentation consequently n't support n't fragment option ipv6 path mtu discovery works initially assuming path mtu mtu link layer interface traffic originates similar ipv4 device along path whose mtu smaller packet drop packet send back icmpv6 packet big type 2 message containing mtu allowing source host reduce path mtu appropriately process repeated mtu small enough traverse entire path without fragmentation path mtu changes connection set lower previously determined path mtu first large packet cause icmp error new lower path mtu found conversely pmtud finds path allows larger mtu possible lower link os periodically reprobe see path changed allows larger packets linux windows timer set default ten minutes many network security devices block icmp messages perceived security benefits including errors necessary proper operation pmtud result connections complete tcp three-way handshake correctly hang data transferred state referred black hole connection implementations pmtud attempt prevent problem inferring large payload packets dropped due mtu rather link congestion however order transmission control protocol tcp operate efficiently icmp unreachable messages type 3 permitted robust method pmtud relies tcp another protocol probe path progressively larger packets standardized rfc 4821 workaround used routers change maximum segment size mss tcp connections passing links mtu lower ethernet default 1500 known mss clamping
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Internet protocols
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flash file system flash file system file system designed storing files flash memory–based storage devices flash file systems closely related file systems general optimized nature characteristics flash memory avoid write amplification use particular operating systems block device layer emulate disk drive general-purpose file system used flash-based storage device suboptimal several reasons log-structured file systems desirable properties flash file system file systems include jffs2 yaffs particular characteristics flash memory best used either controller perform wear leveling error correction specifically designed flash file systems spread writes media deal long erase times nand flash blocks basic concept behind flash file systems flash store updated file system write new copy changed data fresh block remap file pointers erase old block later time practice flash file systems used memory technology devices mtds embedded flash memories controller removable flash memory cards usb flash drives built-in controllers manage mtd dedicated algorithms like wear leveling bad block recovery power loss recovery garbage collection error correction use flash file system limited benefit flash-based memory devices becoming prevalent number mobile devices increasing cost per memory size decreases capacity flash memory chips increases earliest flash file system managing array flash freely writable disk trueffs m-systems israel presented software product pc-card expo santa clara california july 1992 patented 1993 one earliest flash file systems microsoft ffs2 use ms-dos released autumn 1992 ffs2 preceded earlier product called ffs however fell short flash file system managing flash array write read many worm space rather freely writable disk around 1994 pcmcia industry group approved flash translation layer ftl specification based design m-systems trueffs specification authored jointly proposed m-systems scm microsystems also provided first working implementations ftl endorsed intel ftl became popular flash file system design non-pcmcia media well overlayfs unionfs aufs union filesystems allow multiple filesystems combined presented user single tree allows system designer place parts operating system nominally read-only different media normal read-write areas openwrt usually installed raw flash chips without ftl uses overlayfs combine compressed read-only squashfs jffs2
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Computer file systems
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electronic circuit simulation electronic circuit simulation uses mathematical models replicate behavior actual electronic device circuit simulation software allows modeling circuit operation invaluable analysis tool due highly accurate modeling capability many colleges universities use type software teaching electronics technician electronics engineering programs electronics simulation software engages user integrating learning experience kinds interactions actively engage learners analyze synthesize organize evaluate content result learners constructing knowledge simulating circuit ’ behavior actually building greatly improve design efficiency making faulty designs known providing insight behavior electronics circuit designs particular integrated circuits tooling photomasks expensive breadboards impractical probing behavior internal signals extremely difficult therefore almost ic design relies heavily simulation well known analog simulator spice probably best known digital simulators based verilog vhdl electronics simulators integrate schematic editor simulation engine on-screen waveform display see figure 1 allowing designers rapidly modify simulated circuit see effect changes output also typically contain extensive model device libraries models typically include ic specific transistor models bsim generic components resistors capacitors inductors transformers user defined models controlled current voltage sources models verilog-a vhdl-ams printed circuit board pcb design requires specific models well transmission lines traces ibis models driving receiving electronics strictly analog electronics circuit simulators popular simulators often include analog event-driven digital simulation capabilities known mixed-mode simulators means simulation may contain components analog event driven digital sampled-data combination entire mixed signal analysis driven one integrated schematic digital models mixed-mode simulators provide accurate specification propagation time rise/fall time delays event driven algorithm provided mixed-mode simulators general purpose supports non-digital types data example elements use real integer values simulate dsp functions sampled data filters event driven algorithm faster standard spice matrix solution simulation time greatly reduced circuits use event driven models place analog models mixed-mode simulation handled three levels primitive digital elements use timing models built-in 12 16 state digital logic simulator b subcircuit models use actual transistor topology integrated circuit finally c in-line boolean logic expressions exact representations used mainly analysis transmission line signal integrity problems close inspection ic ’ i/o characteristics needed boolean logic expressions delay-less functions used provide efficient logic signal processing analog environment two modeling techniques use spice solve problem third method digital primitives use mixed mode capability methods merits target applications fact many simulations particularly use a/d technology call combination three approaches one approach alone sufficient another type simulation used mainly power electronics represent piecewise linear algorithms algorithms use analog linear simulation power electronic switch changes state time new analog model calculated used next simulation period methodology enhances simulation speed stability significantly process variations occur design fabricated circuit simulators often take variations account variations small taken together change output chip significantly temperature variation also modeled simulate circuit performance temperature ranges
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Programming language topics
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analog devices analog devices inc. adi also known simply analog american multinational semiconductor company specializing data conversion signal processing power management technology headquartered norwood massachusetts 2012 analog devices led worldwide data converter market 48.5 share according analyst firm databeans company manufactures analog mixed-signal digital signal processing dsp integrated circuits ics used electronic equipment technologies used convert condition process real-world phenomena light sound temperature motion pressure electrical signals analog devices approximately 100,000 customers following industries communications computer instrumentation military/aerospace automotive consumer electronics applications company founded two mit graduates ray stata matthew lorber 1965 year company released first product model 101 op amp hockey-puck sized module used test measurement equipment 1967 company published first issue technical magazine analog dialogue 1969 analog devices filed initial public offering became publicly traded company ten years later company listed new york stock exchange 1973 company first launch laser trim wafers first cmos digital-to-analog converter 1996 company reported 1 billion company revenue year jerald fishman named president ceo position held death 2013 see 2000 analog devices sales grew 75 2.578 billion company acquired five companies including bco technologies plc manufacturer thick film semiconductors 150 million january 2008 semiconductor completed acquisition cpu voltage pc thermal monitoring business analog devices. 184 million 2004 analog devices customer base 60,000 portfolio included 10,000 products july 2016 analog linear technology agreed analog would acquire linear approximately 14.8 billion cash stock deal analog devices headquartered norwood massachusetts regional headquarters located shanghai china munich germany limerick ireland tokyo japan analog devices fabrication plants located united states ireland company testing facility located philippines design centers located australia canada china egypt england germany india israel japan scotland spain taiwan turkey raymond stata founder analog devices responsible business strategy product roadmap founding company 1965 stata served company chairman board directors since 1973 executive officer since 1996 ceo 1973 1996 president 1971 1991 addition stata also trustee massachusetts institute technology alma mater awarded ieee founders medal 2003 stata received ee times lifetime achievement award 2008 stata served chairman semiconductor industry association year 2011 vincent roche became president ceo analog devices may 2013 first joined company 1988 marketing director limerick ireland barrie gilbert named first technology fellow analog devices 1979 addition gilbert ieee life fellow holds 65 patents gilbert best known gilbert cell – electronic multiplying mixer analog devices gilbert started company northwest labs design center oregon continued work rf products crafted high-speed nonlinear circuit techniques paul brokaw expert integrated circuit design spent career analog devices holds position analog fellow brokaw inventor many analog ic circuits including brokaw bandgap reference holds 100 patents also ieee life fellow robert adams technical fellow manager audio development analog devices inc. adams holds many patents related audio electronic field member ieee fellow audio engineering society adams received finalist ranking edn innovation innovator year award 1995 jerald g. fishman ceo president analog devices 1996 death march 2013 2004 fishman named ceo year electronic business 35-year veteran analog devices also served board directors analog devices cognex corporation xilinx analog devices products include analog signal processing digital signal processing technologies technologies include data converters amplifiers radio frequency rf technologies embedded processors digital signal processing dsp ics power management interface products data converters include analog-to-digital converters adcs digital-to-analog converters dacs convert electrical signal representations real-world analog phenomena light sound waveforms temperature motion pressure digital signals data back analog devices adc dac ics used medical systems scientific instrumentation wireless wired communications radar industrial process control audio video equipment digital-processing-based systems accurate signal conversion critical data converters account 50 adi revenue adi companion amplifier ics provide accurate high-speed precise signals driving data converters key applications digital audio current sensing precision instrumentation company data converter chips used national instruments high-precision measurement instrumentation systems data converters amplifiers also used scientists researchers project icecube – underground telescope uses digital optical modules doms detect subatomic particles south pole power management products customers industrial wireless infrastructure digital camera markets support signal chain design requirements dynamic range transient performance reliability interface products include broad range interface ic products offered company product categories controller area network digital isolators level translators lvds mobile i/o expander keyboard controller usb rs-232 amplifiers includes precision operational amplifiers instrumentation current sense differential amplifiers audio amplifiers video amplifiers/buffers/filters variable gain amplifiers comparators voltage specialty amplifiers products special linear functions radio frequency integrated circuits rfics address rf signal chain simplify rf system development company rf portfolio includes trupwr rms power detectors logarithmic amplifiers pll dds synthesizers rf prescalers variable gain amplifiers adc drivers gain blocks lnas rf amplifiers processors dsp programmable signal processing integrated circuits execute specialized software programs algorithms associated processing digitized real-time data analog devices processors dsps blackfin sharc sigmadsp tigersharc adsp-21xx precision analog microcontrollers make company embedded processing dsp portfolio multi-dsp signal processing analog devices line micro-electromechanical systems mems microphones sold business invensense 2013 analog devices mems microphones found smart phones tablet pcs security systems medical applications adi mems accelerometers designed game pad controllers microsoft logitech pellican analog devices sells linear mixed-signal mems digital signal processing technologies medical imaging patient monitoring medical instrumentation home healthcare company precision signal-processing components blackfin digital signal processors included karmelsonix wholter overnight pulmonary monitor wheezometer personal asthmatic assessment device accelerometers produced analog devices included zoll medical pocketcpr measures depth chest compressions provides audible visual feedback rescuer allow adjustment proper depth correct rate compression analog devices develops components safety systems stability control systems driver assistance systems infotainment interior applications powertrain systems hybrid electric vehicles use high-precision data conversion products battery monitoring control systems analog devices industrial market includes process control systems help drive productivity energy efficiency reliability analog devices technology consumer electronics includes signal processing circuits image processing auto focus image stabilization digital still cameras camcorders audio video processors home theater systems dvd recorders high-definition televisions advanced touch screen controllers portable media devices 2009 databeans published report top semiconductor analog suppliers analog devices named number two suppliers including texas instruments national semiconductor acquired texas instruments 2011 maxim integrated products linear technology collaborating analog devices since march 2017 competitors include infineon technologies stmicroelectronics intersil corporation 2011 analog devices third ranked analog semiconductor supplier 1967 analog devices first published analog dialogue dan sheingold took position editor two years later held four decades current editor scott wayne currently longest-running in-house publication electronics industry analog dialogue forum exchange circuits systems software real-world signal processing technical magazine published analog devices discusses products applications technology techniques analog digital mixed-signal processing analog dialogue published monthly web featured technical articles also compiled quarterly print editions 2009 analog devices announced engineerzone online technical support community engineerzone launched design engineering community customers prospects partners employees students ask questions share knowledge search answers questions open forum analog devices circuits lab reference circuits engineered tested quick system integration help solve design challenges ranging common complex reference circuits smaller modular designs broadly applicable application-specific reference designs reference circuit documented test data theory operation component selection decision criteria addition reference circuits tailored meet real-world system integration needs may also include board layout schematics cad tools models device drivers evaluation hardware
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Computer architecture
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ip virtual server ipvs ip virtual server implements transport-layer load balancing usually called layer 4 lan switching part linux kernel configured via user-space utility tool ipvs incorporated linux virtual server lvs runs host acts load balancer front cluster real servers ipvs direct requests tcp- udp-based services real servers make services real servers appear virtual services single ip address ipvs built top netfilter ipvs merged versions 2.4.x newer linux kernel mainline
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Computer architecture
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internet os internet operating system internet os type operating system designed run applications services internet client generally web browser advantages os would would run thin client allowing cheaper easily manageable computer systems would require applications designed cross-platform open standards would tie user applications documents preferences single computer rather place internet cloud internet os also promoted perfect type platform software service talk internet os began surface 1995 browser war started heating microsoft netscape response limited capabilities html time microsoft began developing online content authoring platform would based distributed ole object linking embedding codenamed blackbird using ole applications put web would contain processing logic would act similar applications typical desktop environment immediately concerns would tie web proprietary microsoft technology would n't guaranteed run across different systems challenge marc andreessen netscape announced set new products would help transform browser called internet os would provide tools programming interfaces new generation internet-based applications so-called internet os would still run top regular os – based around netscape navigator – dismissed desktop operating systems like windows simply bag drivers reiterating goal would turn windows mundane collection entirely debugged device drivers andreessen explained newest versions navigator web browsers suites internet applications including programs mail ftp news would come viewers variety document types like adobe acrobat apple quicktime sun java applets would give programming interfaces publishing tools developers netscape also would continue sell server software java applets would run cross-platform clients servers scripting language form javascript would also provide facilities backend transaction processing elaborating client/server model navigating clients application servers database servers pointed – broad capabilities gave browser – difference technically netscape navigator traditional operating system navigator n't include device drivers technical problems blackbird growth web saw competitive statements netscape soon led microsoft rethink strategy began position ole primary tool within netscape proposed ecosystem ole would embeddable web pages using activex plug-in would easily integrated server side using asp active server pages development opposition industry microsoft began grow concept internet os led formation alliance around developing java alternative windows – chief partners netscape sun oracle ibm companies informally referred industry press gang four novell later joined alliance leading called gang five may 1997 group published position paper discussed integration software component models within corba – commonly used architecture allowing computer applications different vendors running different systems work together networks issued several rfps request proposals object management group omg standards body responsible managing corba meant help integrate different aspects java proposals included support javabeans – serialized component architecture java – javascript called java-tization corba group positioning java distributed object architecture similar microsoft intended ole blackbird ole would exist second-class technology would interface corba using javabeans group also promoted idea javaos – minimal java-based operating system – would turn run netscape web browser browser run javabeans components would front new ecosystem based open standards first html web browser second java hoped would become widely adopted corba javaos would hosted network computer nc concept long advocated oracle nc would thin client designed internet use leaving access applications documents stored entirely online oracle saw role providing tools server layer network-hosted applications would provided network application server turn would make use oracle7 relationship database management system oracle web server oracle also outlined referred network computing architecture nca would separate presentation application data access logic java applets nca cartridges microsoft intel response challenge put forward standard competing model called netpc diskless pc would primarily adapted web browser use would run simplified version windows 95 codenamed pegasus later road idea evolved netbook microsoft publicly criticized idea internet os instead argued traditional desktop os internet-enabled beginning idea active platform internet strategy culminated later release windows 98 strategy involved tightly bundling internet explorer windows became center united states anti-trust suit microsoft gang five – netscape sun ibm oracle novell – involved lobbying anti-trust action microsoft 1998 java alliance started fall apart oracle continued developing server-side java databases given idea network computer netscape given java browser efforts instead aiming position internet portal pressure investors given blame google revived idea internet os 2009 development chrome os linux-based operating system designed work exclusively ajax-based web applications operating system designed look operate like chrome web browser sold laptops developed partners called chromebooks also promoted g suite suite web applications alternative traditional desktop software microsoft office google tried address standard criticisms internet os concept development projects google native client allows browser run intel x86 native code sandbox complex programs could run fully take advantage system hardware google gears also created allow offline access online applications although deprecated favor web storage model process standardization world wide web consortium w3c
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Distributed computing architecture
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is-dos is-dos disk operating system russian zx spectrum clones is-dos developed 1990 1991 iskra soft leningrad ussr handles floppy disks double sided double density hard disks cd-rom maximum is-dos partition size hard disk 16 mib unlike tr-dos is-dos ram-based operating system reduces amount memory user programs is-dos chic version developed nemo kay provides memory user programs tasis modern version developed nedopc atm turbo 2+ 2006 supports text mode high memory machine based is-dos chic
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Operating systems
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macintosh iivx macintosh iivx personal computer designed manufactured sold apple computer inc. october 1992 october 1993 last macintosh ii family macintosh computers iivx introduced time macintosh iivi performa 600 performa 600cd four models using new metal case design like performa 600cd iivx could equipped internal double-speed cd-rom drive iivx shares model designation macintosh ii computers apple considers iivx first computer macintosh centris line according apple lawyers unable complete trademark check centris name time iivx release machines bearing centris name introduced months later iivx described macworld magazine review best price-to-performance ratio computer apple ever built list price machine hard drive main memory video memory 2,949 usd adding cd-rom upgrading main memory video memory increased price 3,219 usd deemed best cd-rom drive bargain ever offered macworld much-more-powerful macintosh centris 650 released four months iivx 250 less immediately rendering iivx obsolete iivx base price slashed third increasing competition dell pc manufacturers prices iivx continued fall quickly end june 1993 price 5/80 cd-rom configuration dropped 1,799 half original price afterwards people bought expensive mac quickly became outdated said iivx-ed mac iivx began life development proof-of-concept see internal cd-rom drive could added mac apple ceo john sculley gave speech macworld tokyo promised mac cd-rom drive iivx rushed production several shortcuts taken design notably 32 mhz processor crippled 16 mhz bus making slightly slower popular aging macintosh iici serial port limited 57.6 kbit/s could cause problems serial connections midi hardware macintosh iivi slower version iivx 16 mhz processor introduced time markets though united states discontinued four months later high-end member original performa family performa 600 also based architecture iivx macintosh ii model 32k l2 cache iivx sold hard drives ranging 40 three nubus slots processor direct slot macintosh iivx uses case macintosh performa 600 reused centris 650 later known quadra 650 upgraded machine swapping logic board iivx case also used power macintosh 7100
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Computer architecture
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keysight vee keysight vee graphical dataflow programming software development environment keysight technologies automated test measurement data analysis reporting vee originally stood visual engineering environment developed hp designated hp vee since officially renamed keysight vee keysight vee widely used various industries serving entire stage product lifecycle design validation manufacturing optimized instrument control automation test measurement devices data acquisition instruments like digital voltmeters oscilloscopes source devices like signal generators programmable power supplies detailed list features version found references section vee program consists multiple connected vee objects sometimes called devices vee object consists different types pins namely data pins sequence pins execute pins xeq control pins error pins data pins govern data flow propagation sequence pins determine object execution order pins left side object called input pins whereas pins right output pins two objects b connected output pin object connected object b ’ input pin several connection lines emanate single output pin one connection line attached input pin data input pins execute pins must connected whereas control pins output pins left unconnected keysight vee dataflow programming language within vee program multiple connections objects data flows objects left right sequence flows top bottom object ’ execution order determined object connections data dependency rule general object unconnected data input sequence input pin operate first object sequence input pin connected execute soon data present data inputs hand sequence input pin connected although data present data input pins object hold execution sequence input pin pinged may applicable non-primitive objects like junction collector objects example object ’ sequence output pin connected fire object executed execution possible objects descended data output pins error pin object examples taken referred explanation keysight vee connect control variety keysight non-keysight instrumentation via multiple interfaces keysight vee supports following interfaces keysight vee interact programming languages using built-in activex automation server software development programs visual basic c/c++ visual c .net compliant languages call keysight vee userfunctions keysight vee also integrated microsoft .net framework common language runtime framework class libraries provides multitude functions controls used enhance program adding email capability accessing databases access 2500 matlab analysis visualization functions made possible built-in matlab signal processing toolbox built-in microsoft excel library provides direct access save retrieve generate reports spreadsheets keysight vee notable capability deploy unlimited number runtime programs time limitations extra cost runtime programs could contain gui panel allows interaction users presumably operators execute control program test execution
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Programming language topics
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gated community modern form gated community walled community form residential community housing estate containing strictly controlled entrances pedestrians bicycles automobiles often characterized closed perimeter walls fences similar walls gates separated quarters cities centuries gated communities usually consist small residential streets include various shared amenities smaller communities amenities may include park common area larger communities may possible residents stay within community daily activities gated communities type common interest development distinct intentional communities given gated communities spatially type enclave setha m. low anthropologist argued negative effect net social capital broader community outside gated community gated communities usually called guard-gated communities staffed private security guards often home high-value properties and/or set retirement villages gated communities secure enough resemble fortresses intended besides services gatekeepers many gated communities provide amenities may depend number factors including geographical location demographic composition community structure community fees collected subassociations belong master associations master association may provide many amenities general larger association amenities provided amenities also depend type housing example single-family-home communities may common-area swimming pool since individual home-owners ability construct private pools condominium hand may offer community pool since individual units option private pool installation typical amenities offered include one brazil widespread form gated community called condomínio fechado closed housing estate object desire upper classes place small town infrastructure reserve power supply sanitation security guards purpose community protect residents exterior violence philosophy seen closed buildings shopping centres many accessed inside parking lot garage pakistan gated communities located big well small cities considered standard high quality living defence housing authority bahria town major private gated community developers administrators one largest world assets bahria town worth 30 billion gated communities pakistan public parks schools hospitals shopping malls gymnasiums country clubs argentina called barrios privados literal translation private neighborhoods countries often seen symbol wealth however gated communities enjoy dubious social prestige many members middle upper middle class regard gated community dwellers nouveaux riches snobs gated communities houses bigger ones nordelta hospital school shopping mall post-segregation south africa gated communities mushroomed response high levels violent crime commonly referred complexes also broadly classified security villages large-scale privately developed areas enclosed neighborhoods newest neighborhoods developed almost entirely composed security villages malls essential services hospitals part property developers adopted response counter squatting local residents fear due associated crime often results protracted eviction process popular southern china namely pearl river delta region famous clifford estates saudi arabia gated communities existed since discovery oil mainly accommodate families europe north america threat levels increased since late 1990s foreigners general u.s. citizens particular gates become armed sometimes heavily vehicles inspected marksmen saudi arabian national guard armored vehicles appeared certain times markedly recent terrorist attacks areas near-by targeting people european north american countries gated communities rare continental europe japan proponents gated communities lesser degree cul-de-sac maintain reduction exclusion people would passing generally non-local people makes stranger much recognisable closed local environment thus reduces crime danger since small proportion non-local people passing area potential criminals increased traffic increase rather decrease safety people around whose presence could deter criminal behaviour could provide assistance incident another criticism gated communities offer false sense security studies indicate safety gated communities may illusion reality gated communities suburban areas united states less crime similar non-gated neighborhoods commentary new york times specifically blames gated communities shooting death trayvon martin columnist states gated communities churn vicious cycle attracting like-minded residents seek shelter outsiders whose physical seclusion worsens paranoid groupthink outsiders influential paper vanessa watson includes gated communities within class african urban fantasies attempts remake african cities vein dubai singapore watson analysis kind urban planning prizes exclusionary self-contained spaces limit opportunities interaction different classes worsening marginalization urban poor closed cities russia different gated communities limited number gated communities long established foreigners various regions world many gated communities argentina especially greater buenos aires suburb pilar 60 km n buenos aires city suburban areas nordelta tortugas country club first gated community developed argentina dating 1930s/1940s date 1990s liberal reforms consolidated since buenos aires traditionally regarded socially integrated city gated communities subject research sociologists gated communities important way middle upper-class people cope high levels violent criminal activity greater buenos aires although gated communities rare australia since 1980s built well-known hope island particular sanctuary cove gold coast queensland similar projects built area victoria first development sanctuary lakes local government area wyndham 16 km south west melbourne new south wales macquarie links gated community well southgate estate gated community many australian gated communities built within private golf courses act example uriarra village based around community horse paddocks dwellings jointly managed strata title brazil also many gated communities particularly metropolitan regions rio de janeiro são paulo example one são paulo suburbs least 6 compounds known tamboré 1 2 3 consists generously spaced detached houses little separate front gardens one first big-scale gated community projects são paulo city region barueri alphaville planned constructed 1970s military dictatorship big cities brazil faced steep increases car ownership middle higher-classes rural exodus poverty crime urban sprawl downtown decay neighbourhoods physical explicit gating security checkpoints patrols extremely rare absent even canada richest neighbourhoods bridle path toronto furthermore municipal planning laws many canadian provinces ban locked gates public roads public health issue since deny emergency vehicles quick access noted exception canada arbutus ridge age-restricted community constructed 1988 1992 southeastern coast vancouver island common canadian neighbourhoods especially largest cities implicit symbolic gating effectively partitions private infrastructure amenities communities surrounding neighbourhoods classic example affluent montreal suburb mount royal long fence running along side l'acadie boulevard intents purposes separates community working-class neighbourhood park extension also many newer suburban subdivisions employ decorative gates give impression exclusivity seclusion china compounds like gated communities around world target rich also many foreigners live gated communities beijing often foreign companies choose locations foreign employees live cases pay rent associated costs e.g management fees garden work similar communities exist shanghai another major chinese city shanghai links exclusive expatriate community enclosing golf course shanghai american school example notable gated communities shanghai include seasons villas development hutchinson whampoa thomson golf villas green villas gated communities china daxing district beijing enclose homes rural migrants intended reduce crime increase public order safety communist party china-run people daily claims 73 system controversial segregates migrants poor claiming true purpose keep track migrants scheduled implementation changping district also guayaquil quito ecuador many gated communities coastal city guayaquil mostly located samborondón quito valleys surrounding city home mostly wealthiest people trend specially guayaquil houses gated communities moderate prices well greater cairo example dreamland mountain view egypt alexandria el maamoura india many gated neighborhoods also called colonies new delhi big cities upper middle-class upper-class people live new delhi mumbai chennai bangalore like gated communities sometimes communities separated wealth also ethnicity members particular ethnicity tend feel comfortable living among owing reasons related common festivals language cuisine examples common new delhi strong punjabi community many gated neighborhoods predominantly punjabi cases discrimination members ethnic backgrounds living communities likewise also exist bengali south indian muslim gujarati neighborhoods nowadays many modern gated communities developed like aamby valley city lavasa city maharashtra occupying 100 square kilometers area gated communities built chennai hyderabad bangalore lot real estate developers bangalore 3 locations community living bannerghatta hebbal villas devanahalli neighboring countries target housing societies seem upper-middle upper class citizens caste religious discrimination prevalent real estate industry several people denied homes based caste religion regardless factor non-residential indians interested gated housing indonesia gated communities luxurious lots 740 square metres 8000 sq ft affordable lots ranging 40 120 square metres 2000 new residential area build private developer gated community examples include bumi serpong damai south tangerang telaga golf sawangan pesona khayangan depok sentul city bogor regency gated communities indonesia still allow outsiders use facilities inside community regulation social facilities residential development handed local government used public two examples gated community italy olgiata rome village roccamare castiglione della pescaia tuscany malaysia known gated guarded communities seeing steady increase popularity currently according town country planning department four types gated communities malaysia namely gated community concept emerged response rise safety security issues offers advantages terms calm environment enhanced safety ideal family development gated communities mexico result huge income gap existing country 2008 study found average income urban area mexico 26,654 rate higher advanced regions like spain greece average income rural areas sometimes short distance away 8,403 close proximity wealth poverty created large security risk mexico middle class gated communities found virtually every medium large sized city mexico largest found major cities monterrey mexico city guadalajara luxury status gated communities popular middle high income residents mexico gated luxury communities mexico considerably cheaper countries united states retaining houses similar size quality due commonness communities lower cost build priced lower attract middle class residents many gated communities mexico fully independent self-contained infrastructure schools water power facilities security fire forces medical facilities larger gated communities even retain school districts police departments interlomas area mexico city contains hundreds gated communities largest concentration gated communities world stretching surrounding areas santa fe bosques-lomas interlomas-bosque real also made predominantly gated communities span 30 greater mexico city many smaller gated communities mexico officially classified separate gated communities many municipal rules prohibit closed roads small neighborhoods cater lower middle income residents offer close perimeter check points similar authentic gated community situation tolerated sometimes even promoted city governments due lack capacity provide reliable trusted security forces new zealand gated communities developed suburban areas main cities since 1980s 1990s pakistan large number gated communities target middle class pakistanis largest bahria town also largest asia communities major cities defence housing authority also major developer gated communities others include wapda town gulberg islamabad schon properties emaar properties also maintains several gated communities country targeting primarily upper class people gated communities pakistan mostly immune problems law enforcement lack energy faced majority housing societies short time property prices communities greatly increased – 2007 20-square-meter house bahria town lahore cost around four million rupees 40,000 similar property 2012 costed nine million rupees houses priced around 100-300 million rupees lima peru several gated communities especially wealthy districts la molina santiago de surco home many prominent peruvians philippines sizable number gated communities known philippine english subdivisions villages regardless names communities may either form part larger barangay village constitute single barangay aerobus live complex de facto first gated community moscow business center complex outside residential area ozero cooperative formed around vladimir putin dacha priozersky district leningrad oblast saudi arabia many expatriate workers required live company-provided housing 2003 attack al hambra jadawel siyanco vinell militant saudi dissidents government established tight military security compounds large western populations many western individuals also reside many gated compounds non-gated villas apartments cities work saudi aramco provides compound dhahran one largest kind within saudi arabia gated communities also popular many saudis accounts limited availability open villas communities premium rent paid housing compounds found many saudi arabia cities including limited abha dhahran riyadh taif south africa increasing number gated communities often wealthy enclosed live close proximity urban poor yet little contact two many housing estates thailand take form gated communities targeted upper middle classes may managed development company resident committees gated communities often referred mubans thailand turkey several gated communities especially istanbul ankara called site turkish mostly located around edge city united arab emirates gated communities exploded popularity particularly dubai 2002 decision allow foreigners freehold properties resulted construction numerous communities built along various themes examples include lakes springs meadows arabian ranches united kingdom gated communities relatively rare 2004 estimated 1,000 communities england i.e including scotland wales northern ireland usually small scale gated street 60 100 houses single block 500 700 flats found london example docklands new caledonian wharf kings queen wharf pan peninsula east london bow quarter bow london gated communities us unincorporated like indiana briar ridge may even span one incorporated municipality however numerous incorporated gated cities southern california namely bradbury canyon lake hidden hills laguna woods rolling hills meet legal requirements city halls municipal facilities public private corporations parks facilities within gates 1997 estimated 20,000 gated communities built across country approximately 40 new homes california behind walls 1997 estimates number people gated communities ranged 4 million 30,000 communities around 8 million million california alone one reason difficult determine many gated communities united states privately developed incorporated gated communities outside california including lake quivira kansas sea ranch lakes florida anderson creek north carolina north oaks minnesota hot springs village arkansas largest gated community united states 26,000 heavily wooded acres hot springs village governed hot springs village property owners association poa short private tax-exempt home owners association bay harbor michigan largest gated community midwestern united states village rosemont illinois outside chicago maintains security checkpoint entrance main residential section naval square first city philadelphia pennsylvania neighborhood gives suburban feel otherwise urban environment downtown miami florida neighborhood brickell key gated island community high-rise residential towers although anyone walk onto island come via public bus authorized automobiles may enter brickell key expensive apartments miami 2012 gated community retreat twin lakes made famous shooting trayvon martin george zimmerman national spotlight well year 2013 acquittal zimmerman
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Computer security
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data diddling data diddling type cybercrime data altered entered computer system often data entry clerk computer virus computerized processing altered data results fraudulent benefit cases altered data changed back processing conceal activity results huge might include adjusting financial figures marginally could complex make entire system unusable
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Computer security
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sniffing attack sniffing attack sniffer attack context network security corresponds theft interception data capturing network traffic using sniffer application aimed capturing network packets data transmitted across networks data packets encrypted data within network packet read using sniffer using sniffer application attacker analyze network gain information eventually cause network crash become corrupted read communications happening across network sniffing attacks compared tapping phone wires get know conversation reason also referred wiretapping applied computer networks using sniffing tools attackers sniff sensitive information network including email traffic smtp pop imap traffic web traffic http ftp traffic telnet authentication ftp passwords smb nfs many packet sniffer utility usually sniffs network data without making modifications network packets packet sniffers watch display log traffic information accessed attacker prevent networks sniffing attacks organizations individual users keep away applications using insecure protocols like basic http authentication file transfer protocol ftp telnet instead secure protocols https secure file transfer protocol sftp secure shell ssh preferred case necessity using insecure protocol application data transmission encrypted required vpn virtual private networks used provide secure access users
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Computer security
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electric grid security electric grid security refers activities utilities regulators stakeholders play securing national electricity grid american electrical grid going one largest changes history move smart grid technology smart grid allows energy customers energy providers efficiently manage generate electricity similar new technologies smart grid also introduces new concerns security utility owners operators whether investor-owned municipal cooperative typically responsible implementing system improvements regards cybersecurity executives utilities industry beginning recognize business impact cybersecurity electric utility industry u.s. leads number initiatives help protect national electric grid threats industry partners federal government particularly national institute standards technology north american electric reliability corporation federal intelligence law enforcement agencies electric grids targets military terrorist activity american military leaders created first air war plan axis 1941 germany electric grid top target list north american electrical power grid highly connected system ongoing modernization grid generally referred smart grid reliability efficiency two key drivers development smart grid another example ability electrical system incorporate renewable energy sources wind power geothermal power one key issues electric grid security ongoing improvements modernizations created risk system example one risk specifically comes integration digital communications computer infrastructure existing physical infrastructure power grid according academic journal ieee security privacy magazine smart grid uses intelligent transmission distribution networks deliver electricity approach aims improve electric system reliability security efficiency two-way communication consumption data dynamic optimization electric-system operations maintenance planning u.s. federal energy regulatory commission ferc charge cybersecurity standards bulk power system system includes systems necessary operating interconnected grid investor-owned utilities operate different authority state public utility commissions falls outside ferc jurisdiction 2018 two evolutions taking place power economic sector evolutions could make harder utilities defend cyber threat first hackers become sophisticated attempts disrupt electric grids attacks targeted including spear phishing efforts aimed individuals shifting corporate networks include industrial control systems second grid becoming distributed connected growing internet things world could make every device could potential vulnerability 2006 200,000 miles transmission lines 230 kv higher existed united states main problem impossible secure whole system terrorist attacks scenario terrorist attack however would minimal would disrupt small portion overall grid example attack destroys regional transmission tower would temporary impact modern-day electric grid system capable restoring equipment damaged natural disasters tornadoes hurricanes ice storms earthquakes generally short period time due resiliency national grid events would difficult even well-organized large group terrorists cause physical damage small- moderate-scale tornado 2016 members russian hacker organization grizzly steppe infiltrated computer system vermont utility company burlington electric exposing vulnerability nation electric grid attacks hackers disrupt state electric grid however burlington electric discovered malware code computer system connected grid today utility industry advancing cybersecurity series initiatives partnering federal agencies goal improve sector-wide resilience physical cyber threats industry also working national institute standards technology north american electric reliability corporation federal intelligence law enforcement agencies 2017 electric companies spent 57.2 billion grid security september 2018 brien sheahan chairman ceo illinois commerce commission member u.s. department energy doe nuclear energy advisory committee robert powelson former federal energy regulatory commission ferc commissioner wrote published piece utility dive cyberthreats national power system require stronger national standards collaboration levels government recent article u.s. department homeland security confirmed russian hackers targeted control room american public utilities electric distribution system become networked together interconnected critical public services depend system water delivery financial institutions hospitals public safety prevent disruption network sheahan powelson recommended national standards collaboration federal state energy regulators utility companies cybersecurity-specific practices teams baltimore gas electric conducts regular drills employees also shares cyber-threat related information industry government partners duke energy put together corporate incident response team devoted cybersecurity 24 hours day unit works closely government emergency management law enforcement states cybersecurity procedures practices december 2018 u.s senators cory gardner michael bennet introduced legislation intended improve grid security nation-wide bills would create 90 million fund would distributed states develop energy security plans legislation would also require u.s. energy department identify vulnerabilities cyberattacks nation ’ electrical power grid electricity subsector coordinating council escc main liaison organization federal government electric power industry mission coordinate efforts prepare respond national-level disasters threats critical infrastructure escc composed electric company ceos trade association leaders segments industry federal government counterparts include senior administration officials white house relevant cabinet agencies federal law enforcement national security organizations
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Computer security
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macintosh iix macintosh iix personal computer designed manufactured sold apple computer inc. september 1988 october 1990 model introduced update original macintosh ii replacing 16 mhz motorola 68020 cpu 68881 fpu 68030 cpu 68882 fpu running clock speed initial price iix version 40 mb hard drive 800 kb floppy drive replaced 1.44 mb superdrive iix first macintosh include standard mac iix included 0.25 kib l1 instruction cpu cache 0.25 kib l1 data cache 16 mhz bus 1:1 cpu speed supported system 7.5.5 iix second three macintosh models use case allowing dual floppy drives 6 nubus slots last model macintosh iifx apple nomenclature time used x indicate presence '030 cpu used macintosh iicx iivx support spare parts iix discontinued august 31 1998
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Computer architecture
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media contacts database media contacts database media database specific people media commonly journalists media contacts database consists mainly list journalists reporters editors publishers contributors freelance journalists tv show anchors radio show hosts djs etc media-type work media contacts database usually contains following information information available may less based research methods media research company creates database media contacts database pr tool used pr professionals pitch stories particular topic product company specific group journalists journalists would write speak particular topic relevant issue episode shows media contacts database allows pr professional gain easy access hundreds journalists within short span time media contacts database created sold many media research companies offer pr software professionals
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Databases
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road fighter game later released msx home computer system 1985 nintendo entertainment system japan 1985 europe 1992 followed format original game included konami arcade classics 1999 nintendo ds arcade game released i-mode phones japan 2005 road fighter made available microsoft game room service xbox 360 console windows-based pcs march 24 2010 first second levels contain 4 courses ranging grassy plains water bridge seashore mountains finally forest area arcade version 6 stages contained pressing b button raises player speed around 196 km/h pressing button skyrockets speed 400 player limited amount fuel earn touching special multi-colored cars player collides car slips occasionally appearing patches oil car begin spin corrected may crash side barriers causing loss 5-6 fuel units nes famicom version total 6 types cars 1 yellow red three blue one truck yellow cars travel along straight line occur large numbers red cars little less likely appear change lane travelling get way player blue cars vary way change lane trucks go straight way colliding causes player crash konami man make cameo appearance flying side road player progresses certain point level without crashing included course 2 nes famicom versions midnight run road fighter 2 sequel road fighter released arcades march 1996 playstation 1997 arcade version released worldwide playstation version released japan europe europe playstation version titled midnight run removing road fighter connection main selling point allows player shift back forth manual automatic transmission races although different 2-d road fighter scenery similar racing games set japan initial arcade stage wangan midnight except cars licensed player also unique selection normal cars tuned cars reviewing arcade version next generation praised support four players challenging ai multiple tracks ability switch manual automatic mid-race tight controls powerslides car selection generally fast-paced racing nonetheless concluded game slightly average scored three five stars winding heat sequel road fighter midnight run released arcades 1996 first appeared arcades september though arcades receive units later improved version midnight run road fighter 2 though normal tuned cars rules remain unlike midnight run takes place touge roads cabinet came two configurations sitdown version 50 inch monitor upright version 25 inch monitor cabinets linked support four players road fighters japan-only sequel original road fighter released arcades 2010 game features 3d-enhanced graphics mounted pair goggles used view effect tracks set real-life locations based race courses previous konami racing titles including enthusia professional racing gti club series game includes numerous licensed vehicles saved using konami e-amusement pass containing tuning customization data game konami answer sega initial arcade stage 4 namco wangan midnight maximum tune terms card-based games taito chase h.q 2 terms rebooted sequels opening theme take higher composed together system music sota fujimori included beatmania iidx 18 resort anthem playable song addition game includes music beatmania iidx dance dance revolution series form promote another konami arcade games
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Computer architecture
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arm cortex-a15 arm cortex-a15 mpcore 32-bit processor core licensed arm holdings implementing armv7-a architecture multicore processor out-of-order superscalar pipeline running 2.5 ghz arm claimed cortex-a15 core 40 percent powerful cortex-a9 core number cores speed first a15 designs came autumn 2011 products based chip reach market 2012 key features cortex-a15 core first implementation came samsung 2012 exynos 5 dual shipped october 2012 samsung chromebook series 3 arm version followed november google nexus 10 press announcements current implementations licensees lg expected produce a15 based design point
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Computer architecture
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type type ii errors statistical hypothesis testing type error rejection true null hypothesis also known false positive finding conclusion type ii error non-rejection false null hypothesis also known false negative finding conclusion much statistical theory revolves around minimization one errors though complete elimination either treated statistical impossibility statistics null hypothesis statement one seeks nullify conclude incorrect evidence contrary commonly presented statement phenomenon studied produces effect makes difference example null hypothesis might statement diet low carbohydrates effect people weight experimenter usually frames null hypothesis intent rejecting intending run experiment produces data shows phenomenon study indeed make difference case diet low carbohydrates specific time frame fact tend lower body weight people adhere cases specific alternative hypothesis opposed null hypothesis cases alternative hypothesis explicitly stated simply null hypothesis false — either event binary judgment interpretation differs matter significant dispute statistics terms false positives false negatives positive result corresponds rejecting null hypothesis negative result corresponds failing reject null hypothesis false means conclusion drawn incorrect thus type error false positive type ii error false negative comparing two means concluding means different reality different type error concluding means different reality different type ii error various extensions suggested type iii errors though none wide use statistical hypothesis tests probability making type type ii errors example blood tests disease falsely detect disease proportion people fail detect disease proportion people test probability making type error denoted α test probability making type ii error denoted β error rates traded given sample set effort reduce one type error generally results increasing type error given test way reduce error rates increase sample size may feasible test statistic robust type error rate controlled terms also used general way social scientists others refer flaws reasoning statistical test theory notion statistical error integral part hypothesis testing test requires unambiguous statement null hypothesis usually corresponds default state nature example person healthy accused guilty product broken alternative hypothesis negation null hypothesis example person healthy accused guilty product broken result test may negative relative null hypothesis healthy guilty broken positive healthy guilty broken result test corresponds reality correct decision made however result test correspond reality error occurred due statistical nature test result never except rare cases free error two types error distinguished type error type ii error type error occurs null hypothesis h true rejected asserting something absent false hit type error often referred false positive result indicates given condition present actually present terms folk tales investigator may see wolf none raising false alarm null hypothesis h comprises statement wolf type error rate significance level probability rejecting null hypothesis given true denoted greek letter α alpha also called alpha level often significance level set 0.05 5 implying acceptable 5 probability incorrectly rejecting null hypothesis type ii error occurs null hypothesis false erroneously fails rejected failing assert present miss type ii error often called false negative actual hit disregarded test seen miss test checking single condition definitive result true false type ii error committed true alternative hypothesis believed terms folk tales investigator may fail detect wolf fact wolf present therefore fail raise alarm h null hypothesis comprises statement wolf wolf indeed present type ii error part investigator wolf either exists exist within given context— question correctly detected either failing detect present detecting present rate type ii error denoted greek letter β beta related power test equals 1−β tabularised relations truth/falseness null hypothesis outcomes test hypothesis adding water toothpaste protects cavities null hypothesis h adding water make toothpaste effective fighting cavities null hypothesis tested experimental data view nullifying evidence contrary type error occurs detecting effect adding water toothpaste protects cavities present null hypothesis true i.e. true adding water toothpaste make effective protecting cavities null hypothesis rejected based bad experimental data extreme outcome chance alone hypothesis adding fluoride toothpaste protects cavities null hypothesis h adding fluoride toothpaste effect cavities null hypothesis tested experimental data view nullifying evidence contrary type ii error occurs failing detect effect adding fluoride toothpaste protects cavities present null hypothesis false i.e. adding fluoride actually effective cavities data given experiment null hypothesis rejected hypothesis evidence produced court proves man guilty null hypothesis h man innocent type error occurs convicting innocent person miscarriage justice type ii error occurs letting guilty person go free error impunity positive correct outcome occurs convicting guilty person negative correct outcome occurs letting innocent person go free hypothesis patient symptoms improve treatment rapidly placebo treatment null hypothesis h patient symptoms treatment indistinguishable placebo type error would falsely indicate treatment effective placebo whereas type ii error would failure demonstrate treatment effective placebo even though actually effective 1928 jerzy neyman 1894–1981 egon pearson 1895–1980 eminent statisticians discussed problems associated deciding whether particular sample may judged likely randomly drawn certain population florence nightingale david remarked necessary remember adjective 'random term 'random sample apply method drawing sample sample identified two sources error namely 1930 elaborated two sources error remarking 1933 observed problems rarely presented form discriminate certainty true false hypothesis p. 187 also noted deciding whether fail reject reject particular hypothesis amongst set alternative hypotheses p. 201 h h easy make error papers co-written neyman pearson expression h always signifies hypothesis tested paper call two sources error errors type errors type ii respectively standard practice statisticians conduct tests order determine whether speculative hypothesis concerning observed phenomena world inhabitants supported results testing determine whether particular set results agrees reasonably agree speculated hypothesis basis always assumed statistical convention speculated hypothesis wrong so-called null hypothesis observed phenomena simply occur chance consequence speculated agent effect – test determine whether hypothesis right wrong hypothesis test often called null hypothesis likely coined fisher 1935 p. 19 hypothesis either nullified nullified test null hypothesis nullified possible conclude data support alternative hypothesis original speculated one consistent application statisticians neyman pearson convention representing hypothesis tested hypothesis nullified expression h led circumstances many understand term null hypothesis meaning nil hypothesis – statement results question arisen chance necessarily case – key restriction per fisher 1966 null hypothesis must exact free vagueness ambiguity must supply basis 'problem distribution test significance solution consequence experimental science null hypothesis generally statement particular treatment effect observational science difference value particular measured variable experimental prediction probability obtaining result extreme one obtained supposing null hypothesis true lower pre-specified cut-off probability example 5 result said statistically significant null hypothesis rejected british statistician sir ronald aylmer fisher 1890–1962 stressed null hypothesis statistical tests always involve trade-off threshold value varied make test restrictive sensitive restrictive tests increasing risk rejecting true positives sensitive tests increasing risk accepting false positives automated inventory control system rejects high-quality goods consignment commits type error system accepts low-quality goods commits type ii error notions false positives false negatives wide currency realm computers computer applications follows security vulnerabilities important consideration task keeping computer data safe maintaining access data appropriate users context authentication reject positive outcome may counterintuitive experts fields put another way null hypothesis user authorized moulton 1983 stresses importance false positive occurs spam filtering spam blocking techniques wrongly classify legitimate email message spam result interferes delivery anti-spam tactics block filter high percentage unwanted emails without creating significant false-positive results much demanding task false negative occurs spam email detected spam classified non-spam low number false negatives indicator efficiency spam filtering term false positive also used antivirus software wrongly classifies harmless file virus incorrect detection may due heuristics incorrect virus signature database similar problems occur antitrojan antispyware software detection algorithms kinds often create false positives optical character recognition ocr software may detect dots appear algorithm used false positives routinely found every day airport security screening ultimately visual inspection systems installed security alarms intended prevent weapons brought onto aircraft yet often set high sensitivity alarm many times day minor items keys belt buckles loose change mobile phones tacks shoes ratio false positives identifying innocent traveller terrorist true positives detecting would-be terrorist therefore high almost every alarm false positive positive predictive value screening tests low relative cost false results determines likelihood test creators allow events occur cost false negative scenario extremely high detecting bomb brought onto plane could result hundreds deaths whilst cost false positive relatively low reasonably simple inspection appropriate test one low statistical specificity high statistical sensitivity one allows high rate false positives return minimal false negatives biometric matching fingerprint recognition facial recognition iris recognition susceptible type type ii errors null hypothesis input identify someone searched list people system designed rarely match suspects probability type ii errors called false alarm rate hand system used validation acceptance norm far measure system security frr measures user inconvenience level practice medicine significant difference applications screening testing example states usa require newborns screened phenylketonuria hypothyroidism among congenital disorders although display high rate false positives screening tests considered valuable greatly increase likelihood detecting disorders far earlier stage simple blood tests used screen possible blood donors hiv hepatitis significant rate false positives however physicians use much expensive far precise tests determine whether person actually infected either viruses perhaps widely discussed false positives medical screening come breast cancer screening procedure mammography us rate false positive mammograms 15 highest world one consequence high false positive rate us 10-year period half american women screened receive false positive mammogram false positive mammograms costly 100 million spent annually u.s. follow-up testing treatment also cause women unneeded anxiety result high false positive rate us many 90–95 women get positive mammogram condition lowest rate world netherlands 1 lowest rates generally northern europe mammography films read twice high threshold additional testing set high threshold decreases power test ideal population screening test would cheap easy administer produce zero false-negatives possible tests usually produce false-positives subsequently sorted sophisticated expensive testing false negatives false positives significant issues medical testing false negatives may provide falsely reassuring message patients physicians disease absent actually present sometimes leads inappropriate inadequate treatment patient disease common example relying cardiac stress tests detect coronary atherosclerosis even though cardiac stress tests known detect limitations coronary artery blood flow due advanced stenosis false negatives produce serious counter-intuitive problems especially condition searched common test false negative rate 10 used test population true occurrence rate 70 many negatives detected test false false positives also produce serious counter-intuitive problems condition searched rare screening test false positive rate one ten thousand one million samples people true positive positives detected test false probability observed positive result false positive may calculated using bayes theorem
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Computer security
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android one android one near-stock version android operating system released google android one altered companies make phones runs certain smartphones android one brand promises regular security updates three years android os updates two years android one started google 2014 focusing entry-level devices emerging markets though evolved including mid-range high-end smartphones android one runs 100 phones jon gold head android one partnerships google described program evolution including higher-end devices continuation google nexus program phones vetted google included software allowing years quick updates made companies android one started sundar pichai former product chief current ceo google android one often took least year latest android update arrived non-google devices project targeted indian market low-tier devices pichai said initial set devices shared common hardware based reference platform increasing range devices launched future security system updates handled google first set android one devices featured mediatek quad-core mt6582 mobile system-on-chip mobile soc 2014 android one phones initially rolled india pakistan bangladesh nepal indonesia philippines sri lanka myanmar south asian countries first android one smartphones indian brands micromax spice karbonn september 2014 second generation android one smartphones indonesia brands mito impact evercoss one x nexian journey february 2015 first android one preinstalled android 5.0 lollipop manufacturers including qmobile launched android one device named qmobile a1 july 6 2015 pakistan android one launched nigeria august 2015 infinix hot 2 x510 1 2 gb ram version became first android one africa infinix hot 2 x510 also exported african countries egypt ghana ivory coast morocco kenya cameroon uganda also asian countries united arab emirates pakistan indonesia 2 gb ram version manufactures follow gradually 2016 softbank announced would first carrier japan introduce android one phone country namely sharp 507sh released late july 2016 netherlands italy developed countries android one available market retailer media markt sells turkish smartphone brand general mobile 4g android one devices two countries well turkey since 2017 may 25 2017 turkish smartphone brand general mobile released next addition fully committed portfolio android one phones gm 6 softbank soon followed introducing sharp x1 japan subsidiary telecommunications company mobile june 30 september 5 2017 android one xiaomi jointly announced xiaomi mi a1 first android one device evolved program charter bring users smartphones running unmodified android operating system latest google technology easy use interface regular security os upgrades mi a1 first android one device released globally thirty-six markets sold various online offline distributors including xiaomi ’ mi homes device sales concentrated india indonesia russia taiwan september 2017 mvno google fi introduced first android one device available u.s. android one moto x4 november android one entered german market htc u11 life end november 2017 softbank announced addition four new devices android one lineup mobile x2 htc x3 kyocera s3 sharp s4 kyocera february 2018 hmd global maker nokia smartphones announced joined android one program devices approved google original equipment manufacturers oems agree requirements android one features concerning android operating system os security updates official android one entry page says fine print end confirm exact duration support phones territory smartphone manufacturer monthly security updates supported least three years initial phone release february 22 2018 google blog article says faster access android os updates two years including latest ai innovations google amongst secure devices ecosystem regular security updates three years google play protect built google confirms promise provide 2 years updates android one devices still stands website design impact promise program android one continues expand line smartphones geographic availability oem carrier partnerships countries release likely expand beyond initial countries regions listed snapdragon 410 devices rebrands longcheer l8150 based qualcomm seed reference design explaining similarities direct competitor based fully custom pcb design wileyfox swift available worldwide officially supported wileyfox recent android versions community supported lineageos roms
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Operating systems
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unit control block ibm mainframe operating systems os/360 successors line unit control block ucb memory structure control block describes single input/output peripheral device unit exposure alias operating system certain data within ucb also instructs input/output supervisor ios use certain closed subroutines addition normal ios processing additional physical device control operating systems similar structures initial program load ipl current mvs systems nucleus initialization program nip reads necessary information i/o definition file iodf uses build ucbs ucbs stored system-owned memory extended system queue area esqa ipl completes ucbs owned input/output support information stored ucb device type disk tape printer terminal etc address device 1002 subchannel identifier device number channel path id chpid defines path device devices volume serial number volser large amount information including os job management data contents ucb changed mvs evolved concept representation channel command processor external device inside every ucb representation subchannel information block used ssch assembler instruction put irb input put orb output start chain channel commands known ccws ccws queued onto ucb startio macro interface although reference discuss startio macro macro instruction ibm-supported interface withstanding fact interface remained least past three decades startio interface either start operation immediately channel queue empty queue request channel queue deferred execution deferred execution initiated immediately request head queue device becomes available even another program control instant basic design input/output supervisor ios ucb evolved anchor hold information states device ucb currently five areas used external interface device class extension ucb common extension ucb prefix stub ucb common segment ucb device dependent segment areas internal use information read used determine information device earliest implementations os ucbs foundations extensions assembled sysgen located within first 64 kb system area i/o device lookup table consisted 16-bit q-type i.e relocatable addresses subsequent enhancements allowed extensions 64-kilobyte 65,536 bytes line thereby saving space additional ucb foundations 64-kilobyte line also thereby preserving architecture ucb lookup table converting cuu ucb foundation address ucbs introduced 1960s os/360 device addressed ucb typically moving head hard disk drive tape drive internal cache without device usually grossly outperformed mainframe channel processor hence reason execute multiple input/output operations time would impossible device physically handle 1968 ibm introduced 2305-1 2305-2 fixed-head disks 8 exposures alias addresses per disk os/360 support provided ucb per exposure order permit multiple concurrent channel programs similarly later systems derived os/360 required additional ucb allocated virtual volume 3850 mass storage system mss exposure 3880-11 3880-13 successors originally implemented operating system real way determine waiting i/o less important waiting i/os i/os device handled first first workload manager wlm introduced mvs/esa 5.1 os/390 added smart i/o queuing allowed operating system using information provided wlm systems programmer determine waiting i/os less important waiting i/os wlm would sense move waiting i/o queue device longer busy important waiting i/o would get device next wlm improved i/o response device important work processed however still limit single i/o single ucb/device one time since one set channel commands i/o could run one time fine 1960s cpus slow i/o could processed fast cpus could process systems matured cpu speed greatly surpassed i/o input capacity access device serialized ucb level became serious bottleneck parallel access volume pav allow ucbs clone allow multiple i/o run simultaneously appropriate support dasd hardware pav provides support one i/o single device time maintain backward compatibility operations still serialized ucb level pav allows definition additional ucbs logical device using additional alias address example dasd device base address 1000 could alias addresses 1001 1002 1003 alias addresses would ucb since four ucbs single device four concurrent i/os possible writes extent area disk assigned one contiguous area file still serialized reads writes occur simultaneously first version pav disk controller assigns pav ucb second version pav processing work load manager wlm reassigns pav new ucbs time time third version pav processing ds8000 controller series i/o uses available pav ucb needs net effect pavs decrease iosq time component disk response time often zero restrictions pav number alias addresses 255 per base address overall number devices per logical control unit 256 counting base plus aliases two types pav alias addresses static dynamic static alias address defined dasd hardware z/os refer specific single base address dynamic means number alias addresses assigned specific base address fluctuates based need management dynamic aliases left wlm running goal mode always case supported levels z/os systems implement pav usually mixture pav types one perhaps two static aliases defined base ucb bunch dynamic aliases defined wlm manage sees fit wlm watches i/o activity system wlm determines high-importance workload delayed due high contention specific pav-enabled device specifically disk device base alias ucbs must insufficient eliminate ios queue time high contention wlm estimates would help workload achieve goals readily try move aliases another base address device another problem may certain performance goals met specified wlm service classes wlm look alias ucbs processing work less important tasks service class appropriate wlm re-associate aliases base addresses associated important work wlm actions moving aliases one disk device another take seconds effects seen many situations fast enough hyperpavs much responsive acquire ucb pool duration single i/o operation returning pool delay waiting wlm react hyperpav ucb acquired duration single i/o smaller number ucbs required service workload compared dynamic pavs large z/os images ucbs scarce resource hyperpavs provide relief regard similar concept unix-like systems kernel codice_1 structure addressed combination major minor number device node digital vms operating system uses identically named structure ucb similar purposes ucb created i/o device data ucb includes device unit number part device name listhead pending i/o requests may queued ucb may device-driver defined extension driver keep driver-defined data instantiated device device object i/o subsystem windows nt-family operating systems another similar structure
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Operating systems
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discoverability discoverability degree something especially piece content information found search file database information system discoverability concern library information science many aspects digital media software web development marketing since something e.g. website product service etc used people find understand used metadata information information book title product description website keywords affects discoverable something database online 2010s adding metadata product available online make easier end users find product example song file made available online making title name band genre year release pertinent information available connection song file make easier users find song file organizing information putting alphabetical order including search engine example improve discoverability discoverability related different accessibility usability qualities affect usefulness piece information concept discoverability information science online context loose borrowing concept similar name legal profession law discovery pre-trial procedure lawsuit party law civil procedure obtain evidence party parties means discovery devices request answers interrogatories request production documents request admissions depositions discovery obtained non-parties using subpoenas discovery request objected requesting party may seek assistance court filing motion compel discovery usability piece information directly relates discoverable either walled garden database open internet quality information available database internet depends upon quality meta-information item product service case service emphasis placed service reusability opportunities exist reuse service however reuse possible information discoverable first place make items products services discoverable following set activities need performed regarding number 2 storing information searchable repository technically human-searchable repository printed paper list would qualify 2010s searchable repository usually taken mean computer-searchable repository database human user search using type search engine find feature number 3 supports analysis number 2 reading printed paper list hand might feasible theoretical sense time cost-efficient comparison computer-based searching apart increasing reuse potential services discoverability also required avoid development solution logic already contained existing service design services discoverable also provide interpretable information capabilities service discoverability principle provides guidelines could applied service-oriented analysis phase service delivery process relation audiovisual content according meaning given canadian radio-television telecommunications commission crtc purpose 2016 discoverability summit discoverability summed intrinsic ability given content stand lot position easily found discovered piece audiovisual content movie tv series music book ebook audio book podcast audiovisual content digital file tv show movie song made available online content tagged identifying information names key artists e.g. actors directors screenwriters tv shows movies singers musicians record producers songs genres e.g. movies genres action drama comedy songs genres heavy metal music hip hop music etc makes easier end users find content interested 2010s users interact online content algorithms typically determine types content user interested computer program suggests like content user may interested different websites systems different algorithms one approach used amazon online store indicate user user searches looks content/product x users purchased x also purchased following items example oriented around online purchasing behaviour algorithm could also programmed provide suggestions based factors e.g. searching viewing etc. 2010s discoverability typically referred connection search engines highly discoverable piece content e.g. certain movie would movie appears top near top user search results related concept role recommendation engines computer programs give user recommendations based his/her online activity 2010s discoverabilty applies desktop laptop computers increasingly widening range devices access internet including various console video game systems mobile devices tablets smartphones organizations make effort promote certain content e.g. tv show film song video game use traditional marketing billboards tv ads radio ads digital ads pop-up ads pre-roll ads etc mix traditional digital marketing even user ’ intervention searching certain content type content discoverability prime factor contributes whether piece audiovisual content likely found various digital modes content consumption 2017 modes searching include looking netflix movies spotify music audible audio books etc. although concept also generally applied content found twitter tumblr instagram websites involves content ’ mere presence given platform involve associating content keywords tags search algorithms positioning within different categories metadata etc thus discoverability enables much promotes audiovisual content broadcast streamed digital media using internet discoverability includes underlying concepts information science programming architecture foundation search specific product information content within specific webpage software application app discoverability feature content link depends range factors including size colour highlighting features position within page colour used communicate importance feature link designers typically use elements well shadows bolding individuals see certain colours traditional paper printing created physical locations stood fold newspaper versus fold web page app screenview may certain locations give features additional visibility users right bottom web page screen positional advantages disadvantages various locations depend different cultures languages e.g. left right vs. right left locations become established toolbars top screen webpage designers argued commonly used features e.g. print button much visually prominent rarely used features features seen convention user places mouse cursor certain area toolbar function option become visible general smaller screen mobile devices controls often placed right centre screen user views content text organizations try increase discoverability certain feature adding animation moving click icon 2017 addition motion sensors geotracking mobile devices made webpage design discoverability complex smartphones tablets typically capable many inputs user 1980s era desktop including swiping touchscreen touching images screen tilting device one challenges webpage app design degree sophistication experience users navigating webpage app environment varies great deal individuals new using applications one extreme experienced computer users items searched online goal discoverability near top search results organizations may make efforts make likely content webpages top close top search results approaches often collectively called search engine optimization seo note organization takes action increase seo website normally involve changes search engine rather involves adding metadata tags original content among strategies increase visibility website search engine algorithms service delivery context application principle requires collecting information service service analysis phase phase maximum information available service ’ functional context capabilities service stage domain knowledge business experts could also enlisted document meta-data service service-oriented design phase already gathered meta-data could made part service contract oasis soa-rm standard specifies service description artifact represents service meta-data make service meta-data accessible interested parties must centrally accessible could either done publishing service-meta dedicated 'service registry simply placing information 'shared directory case 'service registry repository also used include qos sla current state service basic type meta-information expresses functional context service details product content service ’ capabilities application standardized service contract principle helps create basic functional meta-data consistent manner standardization applied meta-information outside technical contract service e.g publishing information service registry general items data might used categorize may include services know service behavior limitations user service experience information needs documented within service registry way potential consumers use meta-information comparing performance requirements effective application design principle requires meta-information recorded service needs consistent meaningful possible organization-wide standards exist enforce service developers record required meta-data consistent way information recorded meta-data service needs presented way technical non-technical experts understand purpose capabilities service evaluation service may required business people service authorized used principle best applied service-oriented analysis phase time details service ’ purpose functionality available although service design principles support positive manner however case service abstraction service discoverability principle exists inversely proportional relationship details service hidden away service consumers less discoverable information available discovering service could addressed carefully recording service meta-information inner workings service documented within meta-information online economy sophisticated computer programs called algorithms analyse ways end users search access use different content products online thus metadata created regarding content product e.g. author genre e-book also data generated specific human users interaction content organization social media website user profile given person indicating demographic information e.g. age gender location residence employment status education etc social media website collect analyse information tendencies given user given subcategory users social media websites collecting data human users online activities preferences may raise potential privacy concerns algorithms called “ black boxes ” factors used leading websites algorithms typically proprietary information released public number search engine optimization seo firms offer services attempting increase ranking client ’ web content website seo firms typically know exact algorithms used google facebook ghosh et al found algorithm web crawler access 26 new online content ... recrawling constant fraction entire web 2010s one concern raised increasing role algorithms search engines databases specific person indicates preference certain type content product computer algorithm may increasingly focus making recommendations type content give practical example person searches comedy movies online search engine algorithm may start mainly recommending comedies user showing range films e.g. drama documentary etc. positive side person likes comedy films restricted filter reduce information load scanning vast numbers films however various cultural stakeholders raised concerns filter algorithms may restrict diversity material discoverable users concerns dangers filter bubbles raised regards online news services provide types news news sources topics user based his/her previous online activities thus person previously searched fox tv content mainly shown fox tv content person previously searched pbs content shown pbs search results could lead news readers becoming aware certain news source viewpoints search behaviour video content viewers changed great deal since widespread popularity video sharing websites video streaming whereas typical tv show consumer 1980s would read print edition tv guide find shows click channel channel channel surfing see shows appealed 2010s video content consumers increasingly watching screens either smart tvs tablet computer screens smartphones computerized search function often automated algorithm-created suggestions viewer search function user enter name tv show producer actor screenwriter genre help find content interest user searching search engine device laptop tablet computer smartphone device may transmit information user preferences previous online searches website continuing 1980s 2010s comparison 1980s type brand television user watching affect his/her viewing habits however person searching tv shows 2010s different brands computerized smart tvs probably get different search results search term organizations trying get maximal user uptake product content service online discoverability become important goal however achieving discovery automatically translate market success example hypothetical online game xyz easily discoverable function mobile devices video game perform well mobile game market despite top search results well even product functions runs plays properly well users may like product case user like certain online product service discoverability repeatable user find product service subsequent search may longer look product/service instead shift substitute easily reliably findable enough make online product service discoverable short period unless goal create “ viral ” content part short-term marketing campaign
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Web technology
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application request routing application request routing arr extension internet information server iis enables iis server function load balancer arr iis server configured route incoming requests one multiple web servers using one several routing algorithms load balancing requests high availability web servers achieved without incurring typically-high costs dedicated load balancing products arr currently available version 3.0 released july 26 2013 current version supported x86 x64 installed iis 7.0 later windows 2008 later arr available download microsoft download center via microsoft web platform installer webpi arr requires url rewrite extension function uses routing requests arr configured redirect traffic based server variables urls cookies performs full layer 7 load balancing arr functionality described load balancing reverse proxy although advanced dedicated reverse proxy products microsoft uag dedicated load balancing solutions arr 3.0 supports following features
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Web technology
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machine-readable dictionary machine-readable dictionary mrd dictionary stored machine computer data instead printed paper electronic dictionary lexical database machine-readable dictionary dictionary electronic form loaded database queried via application software may single language explanatory dictionary multi-language dictionary support translations two languages combination translation software multiple languages usually apply bidirectional dictionaries mrd may dictionary proprietary structure queried dedicated software example online via internet dictionary open structure available loading computer databases thus used via various software applications conventional dictionaries contain lemma various descriptions machine-readable dictionary may additional capabilities therefore sometimes called smart dictionary example smart dictionary open source gellish english dictionary term dictionary also used refer electronic vocabulary lexicon used example spelling checkers dictionaries arranged subtype-supertype hierarchy concepts terms called taxonomy also contains relations concepts called ontology search engines may use either vocabulary taxonomy ontology optimise search results specialised electronic dictionaries morphological dictionaries syntactic dictionaries term mrd often contrasted nlp dictionary sense mrd electronic form dictionary printed paper although used programs contrast term nlp dictionary preferred dictionary built scratch nlp mind iso standard mrd nlp able represent structures called lexical markup framework first widely distributed mrds merriam-webster seventh collegiate w7 merriam-webster new pocket dictionary mpd produced government-funded project system development corporation direction john olney manually keyboarded typesetting tapes either book available originally distributed multiple reels magnetic tape card images separate word definition separate punch card numerous special codes indicating details usage printed dictionary olney outlined grand plan analysis definitions dictionary project expired analysis could carried robert amsler university texas austin resumed analysis completed taxonomic description pocket dictionary national science foundation funding however project expired taxonomic data could distributed roy byrd et al ibm yorktown heights resumed analysis webster seventh collegiate following amsler work finally 1980s starting initial support bellcore later funded various u.s. federal agencies including nsf arda darpa dto reflex george armitage miller christiane fellbaum princeton university completed creation wide distribution dictionary taxonomy wordnet project today stands widely distributed computational lexicology resource
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Computational linguistics
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winbuilder winbuilder free application designed build customize boot disks live cds based microsoft windows winpe scripts building blocks live cd compiled winbuilder used build core components live cd adding applications configuration specific project scripts consist human-readable text file .script extension contain winbuilder scripting commands scripts graphical user interface sometimes encoded applications extracted needed project collection winbuilder scripts maintained building complete live cd project contains multiple scripts responsible adding features applications build users may build projects scratch use one many projects actively developed boot-land community projects downloaded directly using winbuilder built-in download manager used as-is customized meet individual needs projects developed distributed freely aim provide alternative popular live cd distributions based linux knoppix slax damn small linux known use rescue administrative actions pcs use software build various customized boot disks covered articles pc quest german edition pc world also offers customized scripts building disk images including additional utilities branded pcwvistape pcwwin7pe russian edition chip terabyte unlimited cnet editor review found winbuilder one easy-to-use boot disk creation tools genre praised novice-friendly interface time warned program expects experienced users part boot disk applications experts built-in download center remarked simplifies procuring boot disk applications features praised small size fair memory overhead simple instructions robust application installation wizards
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Operating systems
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spanner database spanner google newsql database spanner globally distributed database service gives developers production-ready storage solution provides key features global transactions strongly consistent reads automatic multi-site replication failover spanner stores large amounts mutable structured data spanner allows users perform arbitrary queries using sql relational data maintaining strong consistency high availability data synchronous replication key features spanner spanner joined google platform february 2017 available part google cloud platform spanner uses paxos algorithm part operation shard partition data across hundreds servers makes heavy use hardware-assisted clock synchronization using gps clocks atomic clocks ensure global consistency google f1 sql database management system dbms built top spanner replacing google custom mysql variant
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Databases
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macintosh quadra macintosh quadra family personal computers designed manufactured sold apple computer inc. october 1991 october 1995 quadra named motorola 68040 central processing unit replaced macintosh ii family high-end macintosh model first models quadra 700 quadra 900 introduced october 1991 quadra 800 840av 605 added 1993 macintosh centris line merged quadra october 1993 adding 610 650 660av range introduction power macintosh line early 1994 apple continued produce sell new quadra models 950 continued sold october 1995 product manager quadra family frank casanova also product manager macintosh iifx first computers bearing macintosh quadra name quadra 700 quadra 900 introduced 1991 central processing unit cpu speed 25 mhz 700 compact model using case dimensions macintosh iici processor direct slot pds expansion slot latter newly designed tower case five nubus expansion slots one pds slot 900 replaced 1992 quadra 950 cpu speed 33 mhz line joined number 800-series machines new minitower case design starting quadra 800 600-series pizza box desktop cases quadra 610 1993 quadra 840av 660av introduced 40 mhz 25 mhz respectively included digital signal processor s-video composite video input/output ports well cd-quality microphone audio output ports av models also introduced plaintalk consisting text-to-speech software macintalk pro speech control although dictation however features poorly supported software dsp installed later av macs based more-powerful powerpc 601 cpu powerful enough handle coprocessor duties apple hired marketing firm lexicon branding come name lexicon chose name quadra hoping appeal engineers evoking technical terms like quadrant quadriceps quadra name also used successors centris models briefly existed 1993 610 650 660av centris mid-range line systems quadra high end lc low end later decided many product lines name dropped machines era including quadra 605 also sold performas last use name quadra 630 variation lc 630 using full motorola 68040 instead lc 68lc040 introduced together 1994 630 first mac use ide based drive bus internal hard disk drive whereas earlier models used scsi first three apple workgroup server models wgs 60 wgs 80 wgs 95 mostly called aws 95 apple workgroup server based centris 610 quadra 800 quadra 950 respectively transition motorola 68040 smooth previous transitions motorola 68020 motorola 68030 due motorola 68040 split instruction data caches quadra compatibility problems self-modifying code including relocating code common macintosh memory model apple partially fixed basic mac os memory copy call flush caches solved vast majority stability problems negated much motorola 68040 performance improvements apple also introduced variant memory copy call flush cache new trap defined way calling older version mac os would simply call previous memory copy routine net effect many complex applications initially slow prone crashing 68040 although developers quickly adapted new architecture relying apple memory copy routines rather flushing cache using memory copy flush cache appropriate time
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Computer architecture
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real-time adaptive security real-time adaptive security network security model necessary accommodate emergence multiple perimeters moving parts network increasingly advanced threats targeting enterprises adaptive security watch network malicious traffic behavioral anomalies ferret end point vulnerabilities identify real-time changes systems automatically enforce end point protections access rules block malicious traffic follow compliance dashboard providing audit data among key features adaptive security infrastructure security platforms share correlate information rather point solutions heuristics system could communicate suspicions firewall features include finer-grained controls automation addition human intervention on-demand security services security service integration security management data rather adding security custom applications go operational security models would created design phase app major change model real-time adaptive security shifting authorization management policy on-demand service contains details policy enforcement matches compliance adapt user situation trying access application instance
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Computer security
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macintosh iivi macintosh iivi also sold macintosh performa 600 personal computer designed manufactured sold apple computer inc. september 1992 february 1993 iivi introduced alongside macintosh iivx using slower processor 16 mhz vs. 32 mhz floating point unit performa 600 models meanwhile iivi iivx 32 mhz cpu iivi benchmarks faster iivx model macintosh ii family branded performa short-lived macintosh model discontinued four months introduction centris 650 introduced similar price point performa 600 featured 1994 disney movie blank check models include three nubus slots pds performa 600 models formally introduced september 14 shipments delayed october coincide introduction iivi iivx introduced september 14 1992 introduced october 19 1992
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Computer architecture
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black lab linux black lab linux free software linux distribution x86 x86-64 hardware first released november 2013 pc/opensystems llc black lab linux based ubuntu linux tailored general desktop use technical user commercially made available pc/opensystems llc business desktops education facilities well parallel computing formerly known os/4 product renamed roberto j. dohnert software team black lab linux uspto denied trademark application os/4 pc/opensystems llc acquired rights name black lab linux 2008 acquisition terrasoft solutions fixstars current incarnation black lab linux share code platform similarities terrasoft solutions product called black lab linux terrasoft solutions release powerpc processor fixstars linux products yellow dog linux y-hpc currently developed yellow dog linux brand
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Computer architecture
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efx factory efx factory architectural-guidance software factory pioneering architectural guidance software factory microsoft one first implementations software factory built ‘ efx factory ’ implements .net distributed architecture service-oriented applications services factory based upon architectural application framework called enterprise framework describes physical microsoft .net architecture leveraging microsoft enterprise library service-oriented patterns microsoft patterns practices efx factory designed built development consultants within microsoft consulting services response customer demand implementation .net architecture best practices .net development guidance best use enterprise library number application blocks freely available microsoft initially circa 2003 .net framework 1.0-1.1 visual studio 2002–2003 ‘ enterprise framework ’ efx built meet growing customer demand implementation .net architecture framework based upon implementation patterns harvested several enterprise solution implementations various customers framework implemented layered .net architecture leveraged extended enterprise library provide complete framework authoring applications services .net platform application framework evolved along changes .net platform emerging microsoft technologies changes industry service orientation patterns framework delivered set class libraries containing base implementations architectural layers prescribing certain technologies asmx ‘ infrastructural services ’ developers used address cross-cutting concerns architectural layers exception handling authentication authorization logging etc framework extended enterprise library implemented several real-world security providers necessary many customers time heterogeneous technology environments addition many best practice patterns specifically concerning exception handling built upon enterprise library solve requirements enterprise context framework also provided blocks packaged enterprise library validation block provided useful abstractions enterprise library specific solution domain offered simplified apis framework unified api typing string parameters framework delivered source form set framework assemblies packaged enterprise library framework included suggested set solutions reference implementation ri documentation developers created client-side applications server-side asp.net web services development application service required developer create new solution implement set assemblies one layer referenced framework assemblies deployed executable application web service primary challenge developers learning patterns framework hand crafting applications services blank solutions without availability time code templates resulted prolific cut pasting code reference implementation code highly vulnerable manual error circa 2005 several technologies emerged microsoft enabled use templates automation modeling types applications services including visual studio 2005 visual studio modeling distributed application system designers guidance automation toolkit gat domain-specific language toolkit dsl using new technologies framework able evolve systematically implementation software factory process many constraints framework lifted enable flexibility products factory could assemble primarily removal prescription technology architectural layers ability deal effectively change development applications services factory introduced domain modeling several new abstractions utilized automation previously possible factory one first factories combine dsl diagrams gat recipes well extending distributed application system designers visual studio gat recipes factory makes extensive use recipes automating changes solution structure property changes structure providing wizards configure models factory provides generating project templates work products automating menial tasks factory user 2007 development efx factory ceased many concepts pioneered absorbed future software factory platform microsoft adopted software factories patterns practices web service software factory following list exemplifies features factory others period factory one first factories designed factory 'product model part factory schema factory provides logical architectural view supporting runtime creating/modifying work products factory developer logical model separates logical design factory product ‘ product explorer ’ physical implementation normally viewed modified ‘ solution explorer ’ visual studio way physical structure solution artifacts could separated logical architectural structure work products product factory user could focus upon architecture product author using models abstractions whilst factory manages creation placement source artifacts factory integrates extends distributed application system designers installed visual studio team edition software architects visual studio provided diagrams application designer system designers provide means define high-level application services enterprise compose black box systems composed larger systems factory extends designers add number new shapes representing implementation applications services new shapes implemented provide specific projects solution templates represent physical structure factory product templates added new set diagram files represent internal component parts application service layers diagrams define specification application service layers give user navigation path drill-down high-level applications inner implementation details factory models using dsl ’ internal implementation applications services based upon logical technology-independent architecture soa patterns architecture composed several layers extended implemented pluggable ‘ artefact generators ’ ‘ technology providers ’ technology providers provide technology specific implementation view layer example layer would ‘ service contract ’ layer web service containing service interfaces service operations data contracts factory first factory provide extensibility mechanism 3rd parties global si isv community domain experts would provide technology tailored implementations various layers technology providers would take form external factories factorettes would integrate efx factory enhance expose technology specific views architectural models ultimately transform source artefacts technology separation capability allowed 'variant factory packaged deployed include technology-independent core factory models several ‘ artefact generators ’ providing technology implementations factory enabled composability variant factories could build solutions suit multitude real-world heterogeneous technology environments
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Operating systems
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environment variable environment variable dynamic-named value affect way running processes behave computer part environment process runs example running process query value temp environment variable discover suitable location store temporary files home userprofile variable find directory structure owned user running process introduced modern form 1979 version 7 unix included unix operating system flavors variants point onward including linux macos pc dos 2.0 1982 succeeding microsoft operating systems including microsoft windows os/2 also included feature although somewhat different syntax usage standard variable names unix unix-like systems process separate set environment variables default process created inherits duplicate environment parent process except explicit changes made parent creates child api level changes must done running codice_1 codice_2 alternatively command shells bash user change environment variables particular command invocation indirectly invoking via codice_3 using codice_4 notation running program access values environment variables configuration purposes shell scripts batch files use environment variables communicate data preferences child processes also used store temporary values reference later shell script however unix variables usually used unix environment variable changed script compiled program affect process possibly child processes parent process unrelated processes affected similarly changing removing variable value inside dos batch file change variable duration codice_5 existence unix environment variables normally initialized system startup system init scripts hence inherited processes system users often augment profile script command shell using microsoft windows environment variable default value stored windows registry set codice_6 file unix setuid program given environment chosen caller runs different authority caller dynamic linker usually load code locations specified environment variables codice_7 codice_8 run process authority setuid program would insecure caller could get run arbitrary code hence misuse authority reason libc unsets environment variables startup setuid process setuid programs usually unset unknown environment variables check others set reasonable values variables used scripts command line usually referenced putting special symbols front around variable name instance display user home directory scripting environments user type dos os/2 windows command-line interpreters codice_5 codice_10 user type windows powershell user type commands codice_3 codice_12 codice_13 display environment variables values codice_13 also used print single variable giving variable name sole argument command commands codice_3 codice_12 also used set environment variables often incorporated directly shell unix following commands also used often dependent certain shell simple principles govern environment variables achieve effect environment variables local process set two shell processes spawned value environment variable changed one change seen child process created inherits environment variables values parent process usually program calls another program first creates child process forking child adjusts environment needed lastly child replaces program called procedure gives calling program control environment called program unix unix-like systems names environment variables case-sensitive unix shells variables may assigned without codice_17 keyword variables defined way displayed codice_12 command true environment variables stored shell recognized kernel codice_13 command display child processes inherit however used front program run variables added program environment persistence environment variable session-wide system-wide unset builtin command implemented bourne shell family sh ksh bash etc c shell family csh tcsh etc unix command line shells unsets shell variable removing memory shell exported environment implemented shell builtin directly manipulates internals shell read-only shell variables unset one tries unset read-only variable unset command print error message return non-zero exit code dos os/2 windows command-line interpreters codice_5 codice_10 codice_22 command used assign environment variables values using following arguments codice_22 command without arguments displays environment variables along values examples environment variables include dos master environment provided primary command processor inherits pre-environment defined codice_64 first loaded size configured codice_65 parameter 160 32767 bytes local environment segments inherited child processes typically reduced size contents hold command-line processors like 4dos allow define minimum amount free environment space available launching secondary shells content environment variables remains unchanged upon storage names without codice_66 always converted uppercase exception pre-environment variables defined via codice_64 directive codice_22 dr dos 6.0 higher codice_69 allow lowercase names dr-dos 7.02 higher principle ms-dos 7.0 higher also supports lowercase variable names codice_70 provides means user define environment variable names containing lowercase letters stored environment like normal environment variables remain invisible dos software since written expect uppercase variables command processors limit maximum length variable name 80 characters principally limited size environment segment dos 16-bit windows programs expect contents environment variables exceed 128 characters dr-dos codice_5 supports environment variables 255 4dos even 512 characters since codice_5 configured via codice_73 support command lines 1024 characters internally ms-dos 7.0 higher environment variables expected contain least 1024 characters well versions dr-dos environment passed drivers often need environment installation shrunken relocated codice_74 codice_75/codice_76 options codice_77 zero environment codice_78 substitute drive e.g codice_79 codice_80 relocate environment program order minimize driver effectively resulting resident memory footprint batch mode non-existent environment variables replaced zero-length string standard environment variables reserved environment variables include dr-dos family supports number additional standard environment variables including datalight rom-dos supports number additional standard environment variables well including codice_364 codice_365 codice_366 codice_367 codice_368 codice_369 also used rom-dos system path variables refer locations critical operating system resources generally user-dependent user management variables store information related resources settings owned various user profiles within system general rule variables refer critical system resources locations necessary os run optional system variables explicitly specified default used modify default behavior certain built-in console commands variables also need explicitly specified command line arguments following tables shows typical default values certain environment variables english versions windows retrieved codice_427 list environment variable refers location user documents directory standard method setting program home directory documents directory besides true environment variables statically stored environment changed deleted number pseudo-environment variables exist batch processing so-called replacement parameters replaceable parameters microsoft ibm terminology aka replacement variables digital research novell caldera terminology batch file parameters jp software terminology codice_432..codice_433 codice_434 used retrieve calling parameters batchjob see codice_435 batchjobs retrieved like environment variables actually stored environment command-line processors like dr-dos codice_5 multiuser dos codice_437/codice_438 terminal message process jp software 4dos 4os2 4nt take command windows cmd.exe support type pseudo-environment variables named system information variables novell caldera terminology internal variables jp software terminology used retrieve various possibly dynamic read-only information running system batch jobs returned values represent status system moment variables queried reading multiple times row may return different values even within command querying direct effect system since stored environment listed set exist external programs retrieve true environment variable name defined takes precedence corresponding variable environment variable deleted case-sensitive almost variables prefixed underscore codice_439 4dos etc convention f.e codice_440 dr-dos codice_5 f.e codice_260 addition 4dos 4os2 4nt take command also support called variable functions including user-definable ones work like internal variables take optional parameters f.e codice_443 may even change system status depending function system information variables supported dr-dos codice_5 system information variables supported dr-dos codice_5 networking loaded dynamic environment variables also named internal variables system information variables dos pseudo-environment variables supported codice_427 command-line extensions enabled expand various discrete values whenever queried values change queried multiple times even within command used batch jobs prompt stored environment consequently neither listed codice_22 exist external programs read case-sensitive indirectly also supported windows codice_5 modified internally call codice_602 execute commands
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Operating systems
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amdahl uts uts discontinued implementation unix operating system ibm mainframe compatible computers amdahl created first versions uts released may 1981 uts global acquiring rights product 2002 uts global since gone business uts release 4.5 supports following s/390 model processors successors uts project origins work started princeton university 1975 port unix ibm vm/370 system team members tom lyon joseph skudlarek peter eichenberger eric schmidt tom lyon joined amdahl 1978 1979 full version 6 unix system amdahl 470 used internally design automation engineering late 1979 updated commonly ported version 7 1980 amdahl announced support unix system 470 five years later ibm announced mainframe unix ix/370 competitive response amdahl commercial versions uts based unix system iii unix system v. 1986 amdahl announced first version run natively ibm/370-compatible hardware uts/580 amdahl 580 series machines previous unix ports always ran guests ibm vm hypervisor version 4.5 based unix system v release 4 svr4
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Operating systems
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graphics environment manager gem graphics environment manager operating environment created digital research dri use dos operating system intel 8088 motorola 68000 microprocessors gem known primarily graphical user interface gui atari st series computers also supplied series ibm pc-compatible computers amstrad also available standard ibm pc time 6 mhz ibm pc concept gui brand new core small number dos programs notable ventura publisher ported number computers previously lacked graphical interfaces never gained popularity platforms dri also produced x/gem flexos real-time operating system adaptations os/2 presentation manager x window system preparation well gem started life dri general-purpose graphics library known gsx graphics system extension written team led heiskell lee lorenzen graphic software systems inc. recently left xerox parc birthplace modern gui wrote much code gsx essentially dri-specific implementation gks graphics standard proposed late 1970s gsx intended allow dri write graphics programs charting etc platforms cp/m-80 cp/m-86 ms-dos nec apc-iii would run task would otherwise require considerable effort port due large differences graphics hardware concepts various systems era gsx consisted two parts selection routines common drawing operations device drivers responsible handling actual output former known gdos latter gios play division cp/m machine-independent bdos machine-specific bios gdos selection routines handled gks drawing gios actually used underlying hardware produce output driver binary may operate cp/m-86 dos gsx evolved one part would later known gem effort build full gui system using earlier gsx work basis originally known crystal play ibm project called glass name later changed gem gem gsx became gem vdi virtual device interface responsible basic graphics drawing vdi also added ability work multiple fonts added selection raster drawing commands formerly vector-only gks-based drawing commands vdi also added multiple viewports key addition use windows new module gem aes application environment services provided window management ui elements gem desktop used libraries combination provide gui 8086 version entire system first demoed 1984 comdex shipped gem/1 28 february 1985 gem desktop 1.0 released 28 february 1985 gem desktop 1.1 released april 1985 support cga ega displays version apricot computers f-series supporting 640×200 8 colors also available gem desktop 1.2 dri originally designed gem dos would check run ibm computers pc compatibles like compaq company hoped receive license fees compatible makers developers reacted byte described small explosion reported dri-hosted seminar february 1985 half attendees agreed gem incompatibility compaq serious limitation later month company removed restriction applications supported gem included lifetree software gem write point apple computer sued dri would turn long dispute look feel gem/1 system almost direct copy macintosh elements bearing closer resemblance earlier lisa available since january 1983 eventually led dri forced change several basic features system see also apple v. digital research apple would later go sue companies similar issues including copyright lawsuit microsoft hp addition printers system also contained drivers unusual devices polaroid palette dri responded lawsuit-friendly gem desktop 2.0 released march 1986 support vga displays allowed display two fixed windows desktop though programs could wished changed trash icon removed animations things like opening closing windows otherwise similar gem/1 also included number bug fixes cosmetic improvements 1988 stewart alsop ii said gem among several guis already knocked market apple ibm/microsoft others gem xm gem desktop 3.0 updated version gem/2 1986/1987 dos including dos plus allowed task-switching ability run ten gem dos programs swapping expanded memory xm ems/eems disk including ram disks thereby also allowing use extended memory data could copied pasted applications clipboard filter function feature later also found taskmax dr dos 6.0 digital research planned offer gem xm option gem draw plus users oem channels gem xm source code freely available terms gnu general public license last retail release gem/3 desktop released november 1988 speed improvements shipped number basic applications commercial sales gem ended gem/3 source code subsequently made available number dri leading customers gem/4 released 1990 included ability work bézier curves feature still commonly found outside postscript world version produced specifically artline drawing program german company ccp development gmbh system also included changes font management system made incompatible likes timeworks publisher another version gem called gem/5 produced gst timeworks publisher 2.1 contained updated look 3d buttons along features on-the-fly font scaling came complete standard 3.1 tools version produced gem 3.13 bézier handling taken gem/4 gem desktop spun 1990 product known viewmax used solely file management shell dr dos form system could run gem programs led situation number applications including viewmax could exist statically linked copy gem system scenario actually rare native gem programs published 1991 viewmax 2 released forms gem survived dri purchased novell june 1991 gem development cancelled throughout time dri also working making gem system capable multitasking started x/gem based gem/1 required use one multitasking cp/m-based operating systems dri also produced x/gem flexos real-time operating system adaptations os/2 presentation manager x window system preparation well lee lorenzen left soon release gem/1 became clear dri strong interest application development joined two former dri employees heiskell john meyer start ventura software developed ventura publisher later marketed xerox eventually corel would go popular desktop publishing program time development production 68000 version gem began september 1984 atari sent team called monterey group digital research begin work porting gem originally plan run gem top cp/m-68k ostensibly ported motorola 68000 dri prior st design created fact ports unusable would require considerable development digital research also offered gemdos originally written gem dos dos-like operating system aimed port gem different hardware platforms available 8086 68000 processors adapted apple lisa 2/5 motorola vme/10 development system already atari eventually decided give existing cp/m-68k code instead port gemdos atari st platform referring tos atari provided development 68000 version given full rights continued developments without needing reverse-license back dri result apple-dri lawsuit apply atari versions gem allowed keep mac-like ui next seven years 1985 1992 new versions tos released new generation st line updates included support colors higher resolutions raster-side system remained generally similar original terms gks support 1992 atari released tos 4 multitos along final computer system falcon030 combination mint tos 4 allowed full multitasking support gem caldera bought remaining digital research assets novell 23 july 1996 initial plans revive gem viewmax technologies low-footprint user interface opendos mobile applications caldera view plans abandoned caldera uk favour dr-webspyder grow caldera thin clients later known lineo released source gem gem xm terms gnu general public license gpl april 1999 development gem pc continued freegem opengem atari st platform original dri sources ported used free open source tos clone emutos new implementations aes portions gem implemented scratch form xaaes myaes fully re-entrant support multitasking top freemint multitasking extensions tos full gem system consisted three main parts gem vdi core graphics system overall gem engine responsible low level drawing form draw line vdi included resolution coordinate independent set vector drawing instructions called applications fairly simple interface tvdi also included environment information state context current color line thickness output device etc commands examined gdos whose task send commands proper driver actual rendering instance particular gem vdi environment connected screen vdi instructions routed screen driver drawing simply changing environment point printer needed theory print dramatically reducing developer workload formerly printing hand applications gdos also responsible loading drivers requested fonts gem first loaded one major advantage vdi provided macintosh way multiple devices contexts handled mac information stored memory inside application resulted serious problems attempting make mac handle pre-emptive multitasking drawing layer quickdraw needed direct memory access programs gem vdi however information stored device gdos creating virtual devices every context – window instance gem aes provided window system window manager ui style gui elements widgets performance reasons many gui widgets actually drawn using character graphics compared macintosh aes provided rather spartan look system shipped single monospaced font aes performs operations calling vdi general sense two parts gem often completely separated applications applications typically called aes commands set new window rest application using vdi calls actually draw window gem desktop application program used aes provide file manager launcher traditional desktop environment users come expect macintosh unlike macintosh gem desktop based top dos ms-dos dos plus dr dos pc gemdos atari result actual display cluttered computer-like items including path names wildcards general gem much geeky mac simply running usable shell dos huge achievement otherwise gem advantages mac os proportional sliders
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Operating systems
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hostap hostap one popular ieee 802.11 device drivers linux since november 2016 officially obsolete linux kernel works cards using conexant formerly intersil prism 2/2.5/3 chipset support host ap mode allows wlan card perform functions wireless access point driver code written jouni malinen hired atheros 2008 included main kernel tree linux 2.6.14
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Operating systems
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polymorphic code computer terminology polymorphic code code uses polymorphic engine mutate keeping original algorithm intact code changes time runs function code semantics change example 1+3 6-2 achieve result using different values operations technique sometimes used computer viruses shellcodes computer worms hide presence encryption common method hide code encryption main body code also called payload encrypted appear meaningless code function decryption function added code code executed function reads payload decrypts executing turn encryption alone polymorphism gain polymorphic behavior encryptor/decryptor pair mutated copy code allows different versions code function anti-virus software intrusion detection systems ids attempt locate malicious code searching computer files data packets sent computer network security software finds patterns correspond known computer viruses worms takes appropriate steps neutralize threat polymorphic algorithms make difficult software recognize offending code constantly mutates malicious programmers sought protect encrypted code virus-scanning strategy rewriting unencrypted decryption engine resulting encrypted payload time virus worm propagated anti-virus software uses sophisticated pattern analysis find underlying patterns within different mutations decryption engine hopes reliably detecting malware emulation may used defeat polymorphic obfuscation letting malware demangle virtual environment utilising methods traditional signature scanning virtual environment sometimes called sandbox polymorphism protect virus emulation decrypted payload remains regardless variation decryption algorithm metamorphic code techniques may used complicate detection virus may execute without ever identifiable code blocks memory remain constant infection infection first known polymorphic virus written mark washburn virus called 1260 written 1990 better-known polymorphic virus created 1992 hacker dark avenger pseudonym means avoiding pattern recognition antivirus software common virulent polymorphic virus file infecter virut example really polymorphic code serve introduction world encryption via xor operator example algorithm using variables b variable c could large amount code changes c would effect algorithm allowing changed endlessly without heed final product encrypted code payload make different versions code copy garbage lines manipulate c change code inside encrypted lots encrypted code search code decryption_code cryptokey algorithm new code thing usually coder uses zero key example xor 0 first generation virus making easier coder key code encrypted coder implements incremental key algorithm random one polymorphic code also used generate encryption algorithm code generated online service stringencrypt takes string file content encrypts random encryption commands generates polymorphic decryption code one many supported programming languages see c++ example string encrypted character stored encrypted form using unicode widechar format different encryption commands used like bitwise xor addition subtraction bit rotations everything randomized encryption keys bit rotation counters encryption commands order well output code generated c/c++ c java javascript python ruby haskell masm fasm autoit thanks randomization generated algorithm different every time possible write generic decryption tools compiled code polymorphic encryption code analyzed time re-encrypted
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Computer security
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classic risc pipeline history computer hardware early reduced instruction set computer central processing units risc cpus used similar architectural solution called classic risc pipeline cpus mips sparc motorola 88000 later notional cpu dlx invented education classic scalar risc designs fetched tried execute one instruction per cycle main common concept design five-stage execution instruction pipeline operation pipeline stage worked one instruction time stages consisted initial set flip-flops combinational logic operated outputs flip-flops instruction cache machines latency one cycle meaning instruction cache would ready next clock cycle instruction fetch stage 32-bit instruction fetched cache program counter pc register holds address current instruction feeds pc predictor sends program counter pc instruction cache read current instruction time pc predictor predicts address next instruction incrementing pc 4 instructions 4 bytes long prediction always wrong case taken branch jump exception see delayed branches later machines would use complicated accurate algorithms branch prediction branch target prediction guess next instruction address unlike earlier microcoded machines first risc machines microcode fetched instruction cache instruction bits shifted pipeline simple combinational logic pipeline stage could produce control signals datapath directly instruction bits result little decoding done stage traditionally called decode stage consequence lack decoding meant however instruction bits used specifying instruction also leaves fewer bits things like register indices mips sparc dlx instructions two register inputs decode stage two register names identified within instruction two registers named read register file mips design register file 32 entries time register file read instruction issue logic stage determined pipeline ready execute instruction stage issue logic would cause instruction fetch stage decode stage stall stall cycle stages would prevent initial flip-flops accepting new bits instruction decoded branch jump target address branch jump computed parallel reading register file branch condition computed register file read branch taken instruction jump pc predictor first stage assigned branch target rather incremented pc computed architectures made use alu execute stage cost slightly decreased instruction throughput decode stage ended quite lot hardware mips possibility branching two registers equal 32-bit-wide tree ran series register file read making long critical path stage also branch target computation generally required 16 bit add 14 bit incrementer resolving branch decode stage made possible single-cycle branch mispredict penalty since branches often taken thus mispredicted important keep penalty low execute stage actual computation occurs typically stage consists arithmetic logic unit also bit shifter may also include multiple cycle multiplier divider arithmetic logic unit responsible performing boolean operations nand xor xnor also performing integer addition subtraction besides result alu typically provides status bits whether result 0 overflow occurred bit shifter responsible shift rotations instructions simple risc machines divided three latency classes according type operation data memory needs accessed done stage stage single cycle latency instructions simply results forwarded next stage forwarding ensures one two cycle instructions always write results stage pipeline one write port register file used always available direct mapped virtually tagged data caching simplest far numerous data cache organizations two srams used one storing data storing tags stage single cycle two cycle instructions write results register file hennessy patterson coined term hazard situations instructions pipeline would produce wrong answers structural hazards occur two instructions might attempt use resources time classic risc pipelines avoided hazards replicating hardware particular branch instructions could used alu compute target address branch alu used decode stage purpose alu instruction followed branch would seen instructions attempt use alu simultaneously simple resolve conflict designing specialized branch target adder decode stage data hazards occur instruction scheduled blindly would attempt use data data available register file classic risc pipeline data hazards avoided one two ways bypassing also known operand forwarding suppose cpu executing following piece code instruction fetch decode stages send second instruction one cycle first flow pipeline shown diagram naive pipeline without hazard consideration data hazard progresses follows cycle 3 codice_1 instruction calculates new value codice_2 cycle codice_3 operation decoded value codice_2 fetched register file however codice_1 instruction yet written result codice_2 write-back normally occurs cycle 5 green box therefore value read register file passed alu execute stage codice_3 operation red box incorrect instead must pass data computed codice_1 back execute stage i.e red circle diagram codice_3 operation normally written-back solution problem pair bypass multiplexers multiplexers sit end decode stage flopped outputs inputs alu multiplexer selects decode stage logic compares registers written instructions execute access stages pipeline registers read instruction decode stage cause multiplexers select recent data bypass multiplexers make possible pipeline execute simple instructions latency alu multiplexer flip-flop without multiplexers latency writing reading register file would included latency instructions note data passed forward time data bypassed back earlier stage processed yet case data passed forward time codice_3 ready register alu codice_1 already computed however consider following instructions data read address codice_13 n't present data cache memory access stage codice_14 instruction time codice_3 instruction already alu resolve would require data memory passed backwards time input alu possible solution delay codice_3 instruction one cycle data hazard detected decode stage fetch decode stages stalled prevented flopping inputs stay state cycle execute access write-back stages downstream see extra no-operation instruction nop inserted codice_14 codice_3 instructions nop termed pipeline bubble since floats pipeline like air bubble occupying resources producing useful results hardware detect data hazard stall pipeline hazard cleared called pipeline interlock pipeline interlock used data forwarding however first example codice_1 followed codice_3 second example codice_14 followed codice_3 solved stalling first stage three cycles write-back achieved data register file correct causing correct register value fetched codice_3 decode stage causes quite performance hit processor spends lot time processing nothing clock speeds increased less forwarding logic wait data hazard detected quite easily program machine code written compiler stanford mips machine relied compiler add nop instructions case rather circuitry detect taxingly stall first two pipeline stages hence name mips microprocessor without interlocked pipeline stages turned extra nop instructions added compiler expanded program binaries enough instruction cache hit rate reduced stall hardware although expensive put back later designs improve instruction cache hit rate point acronym longer made sense control hazards caused conditional unconditional branching classic risc pipeline resolves branches decode stage means branch resolution recurrence two cycles long three implications four schemes solve performance problem branches delayed branches controversial first semantics complicated delayed branch specifies jump new location happens next instruction next instruction one unavoidably loaded instruction cache branch delayed branches criticized poor short-term choice isa design suppose 32-bit risc processes add instruction adds two large numbers result fit 32 bits happens simplest solution provided architectures wrapping arithmetic numbers greater maximum possible encoded value significant bits chopped fit usual integer number system 3000000000+3000000000=6000000000 unsigned 32 bit wrapping arithmetic 3000000000+3000000000=1705032704 6000000000 mod 2^32 may seem terribly useful largest benefit wrapping arithmetic every operation well defined result programmer especially programming language supporting large integers e.g lisp scheme may want wrapping arithmetic architectures e.g mips define special addition operations branch special locations overflow rather wrapping result software target location responsible fixing problem special branch called exception exceptions differ regular branches target address specified instruction branch decision dependent outcome instruction common kind software-visible exception one classic risc machines tlb miss see virtual memory exceptions different branches jumps control flow changes resolved decode stage exceptions resolved writeback stage exception detected following instructions earlier pipeline marked invalid flow end pipe results discarded program counter set address special exception handler special registers written exception location cause make easy fast software fix problem restart program cpu must take precise exception precise exception means instructions excepting instruction executed excepting instruction everything afterwards executed take precise exceptions cpu must commit changes software visible state program order in-order commit happens naturally classic risc pipeline instructions write results register file writeback stage writes automatically happen program order store instructions however write results store data queue access stage store instruction takes exception store data queue entry invalidated written cache data sram later occasionally either data instruction cache n't contain required datum instruction cases cpu must suspend operation cache filled necessary data must resume execution problem filling cache required data potentially writing back memory evicted cache line specific pipeline organization discussed two strategies handle suspend/resume problem first global stall signal signal activated prevents instructions advancing pipeline generally gating clock flip-flops start stage disadvantage strategy large number flip flops global stall signal takes long time propagate since machine generally stall cycle identifies condition requiring stall stall signal becomes speed-limiting critical path another strategy handle suspend/resume reuse exception logic machine takes exception offending instruction instructions invalidated cache filled necessary data instruction caused cache miss restarts expedite data cache miss handling instruction restarted access cycle happens one cycle data cache filled
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Computer architecture
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