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freeradius freeradius modular high performance free radius suite developed distributed gnu general public license version 2 free download use freeradius suite includes radius server bsd-licensed radius client library pam library apache module numerous additional radius related utilities development libraries cases word freeradius refers free open-source radius server suite freeradius popular open source radius server widely deployed radius server world supports common authentication protocols server comes php-based web user administration tool called dialupadmin basis many commercial radius products services embedded systems radius appliances support network access control wimax supplies aaa needs many fortune-500 companies telcos tier 1 isps also widely used academic community including eduroam server fast feature-rich modular scalable freeradius started august 1999 alan dekok miquel van smoorenburg miquel previously written cistron radius server gained widespread usage livingston server longer maintained freeradius started create new radius server using modular design would encourage active community involvement november 2014 freeradius project three core team members alan dekok project leader arran cudbard-bell principal architect matthew newton latest major release freeradius 3 freeradius 3 includes support radius tls including radsec completely rewritten rlm_ldap module hundreds minor consistency usability enhancements latest mature version maintained stability rather features previous major release v2.2.x entered final phase lifecycle receive security fixes survey 2006 showed user base totals 100 million people modules included server core support ldap mysql postgresql oracle many databases supports popular eap authentication types including peap eap-ttls 100 vendor dictionaries included ensuring compatibility wide range nas devices version 2.0.0 added support virtual hosting ipv6 vmps new policy language simplifies many complex configurations
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Computer security
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blacknurse blacknurse attack form denial service attack based icmp flooding attack special modest bandwidth 20mbit/s effective disrupting victim network attack consists sending destination unreachable packets destination works packets caused destination consume resources relatively high rate relative traffic attack first discovered researchers lenny hansson kenneth bjerregard jørgensen security operations center danish telecom operator tdc researchers goal protect customers telecom network ddos attacks cyber threats team noted release attack blacknurse attack attracted attention anti-ddos solution experienced even though traffic speed packets per second low attack could keep customers operations even applied customers large internet uplinks large enterprise firewalls place expected professional firewall equipment would able handle attack denial service typically accomplished flooding targeted machine resource superfluous requests attempt overload systems prevent legitimate requests fulfilled commonly attack done distributed manner many clients send requests given server sum client traffic often enough overwhelm destination cause service go offline become unavailable case blacknurse attack instead flooding remote system internet traffic superfluous traffic attack takes advantage imbalance resources required send traffic resources required process namely blacknurse attacks uses icmp type 3 code 3 packets packet meant sent destination port unreachable unlike previous attacks using icmp protocol -- smurf attack ping flood ping death -- blacknurse flood destination traffic instead researchers realized destination port unreachable packet causes high cpu usage firewall processes using relatively small bandwidth 15-18mbit/s attacker cause cpu usage spike target firewall causing firewall become unable process requests test device vulnerable send icmp packet network using following commands recommended run commands wan side firewall running test attempt use network normally watching cpu usage firewall history icmp attacks like smurf attack ping flood ping death many icmp packets commonly blocked firewalls however icmp packets necessary allow network work properly destination port unreachable one packets required typically however attack effective incoming traffic greater bandwidth victim machine case blacknurse however attack takes advantage processing logic many firewalls handling traffic attack important leverages necessary component internet traffic n't require use botnet execute attacks due low cost attack low bandwidth connections common attack used effectively original researchers soc tdc noted attack currently used clients network attack named blacknurse joke two principal researchers former blacksmith former nurse media picked name could changed
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Computer security
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semi-structured model semi-structured model database model separation data schema amount structure used depends purpose advantages model following primary trade-off made using semi-structured database model queries made efficiently constrained structure relational model typically records semi-structured database stored unique ids referenced pointers location disk makes navigational path-based queries quite efficient searches many records typical sql efficient seek around disk following pointers object exchange model oem one standard express semi-structured data another way xml
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Databases
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wakanda software wakanda javascript platform develop run web mobile apps based open standards technologies including angularjs ionic node.js typescript supported linux deployment microsoft windows macos studio development wakanda consists stack tools technologies starting 2008 server wakanda first presented ajax experience 2009 year jsconf.eu private developer preview made accessible 2010 first version wakanda studio including model designer gui designer wakanda came public attention june 2011 new developer preview second public developer preview announced wakanday js.everywhere boston october 2011 conference first beta december 15th wakanda available live release version since march 15 2012 june 28 2012 first version wakanda officially launched october 26 2012 demonstrated js.everywhere conference us france first involved commonjs working group since 2009 team created client server javascript apis w3c community group april 2012 joining w3c october 2012 company wakanda sas created december 2014 december 7 2015 wakanda digital app factory officially launched 2016 wakanda named cool vendor gartner wakanda server supports commonjs modules web workers web storage xmlhttprequest html5 file api blobs timers implements firebug crossfire debugger protocol well webkit remote debugging protocol wakandadb nosql engine accessed via http inspired odata rest api integrates connectors interact tiers databases mysql microsoft sql server odbc wakanda supports node.js modules including eventemitter socket tls wakanda includes open source projects part default packages wakanda server built javascriptcore icu openssl zlib
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Programming language topics
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comparison programming languages string functions string functions used computer programming languages manipulate string query information string programming languages string datatype string functions although may low-level ways within language handle strings directly object-oriented languages string functions often implemented properties methods string objects functional list-based languages string represented list character codes therefore list-manipulation procedures could considered string functions however languages may implement subset explicit string-specific functions well function manipulate strings modern object-oriented languages like c java immutable strings return copy newly allocated dynamic memory others like c manipulate original string unless programmer copies data new string see example concatenation basic example string function codice_1 function function returns length string literal languages may string functions similar exactly syntax parameters outcomes example many languages length function usually represented len string list common functions aims help limit confusion string functions common many languages listed including different names used list common functions aims help programmers find equivalent function language note string concatenation regular expressions handled separate pages statements guillemets « … » optional var begin // example c ya hello world 2 // l' substr hello world 1 1 e' hello world .substr 1 1 e' hello world 2 l' hello world -3 r' example visual basic mid hello world ,2,1 example visual basic .net hello world .chars 2 l c example smalltalk 'hello world 2 e //example rust hello world .chars .nth 2 // l' hello cmp world returns -1 hello cmp world returns less world cmp hello returns hello cmp hello returns cmp hello world returns -1 /** example rexx */ compare hello world /* returns index mismatch 1 */ use-modules srfi srfi-13 string-compare hello world values values values example erlang hello world returns false art gt painting returns false art lt painting returns true hello -gt world returns false string art painting returns nil string art painting returns non nil 'abc 'def // returns abcdef // example c abc def // returns abcdef example visual basic abc def returns abcdef abc def returns abcdef abc null returns abc abc null returns null // example abc def // returns abcdef concatenate 'string abc def ghi returns abc def ghi abc def returns abcdef perl 5 returns perl 5 abc def returns abcdef perl 6 returns perl 6 ¢ example algol 68 ¢ // example c hello mate .contains e // returns true word .contains z // returns false good morning .contains z returns false ¡buenos días .contains í returns true e hello mate returns true z word returns false example smalltalk 'hello mate includessubstring e returns true 'word includessubstring z returns false tests two strings equal see also compare compare note equality checks via generic compare integer result confusing programmer often significantly expensive operation especially true using c-strings // example c hello == world // returns false example visual basic hello world returns false 'hello eq 'world returns 0 'hello eq 'hello returns 1 'hello eq 'world returns false 'hello eq 'hello returns true hello -eq world returns false ⍝ example apl 'hello ≡ 'world ⍝ returns 0 search e hello mate returns 1 search z word returns nil // examples c hello mate .indexof e // returns 1 hello mate .indexof e 4 // returns 9 word .indexof z // returns -1 hello .index e returns 1 hello .index z returns nil use-modules srfi srfi-13 string-contains hello mate e returns 1 string-contains word z returns f examples visual basic instr hello mate e returns 2 instr 5 hello mate e returns 10 instr word z returns 0 examples smalltalk 'hello mate indexofsubcollection 'ate returns 8 'hello mate indexofsubcollection 'late returns 0 i'hello mate 'hello mate // examples c hello mate .indexof e // returns 1 word .indexof z // returns -1 position \e hello mate returns 1 position \z word returns nil // example c string.format 0 costs 1 c2 pen 19.99 // returns pen costs 19.99 // example object pascal delphi format 'my costs 2f 'pen 19.99 // returns pen costs 19.99 // example java string.format costs 2f pen 19.99 // returns pen costs 19.99 sprintf costs .2f pen 19.99 returns pen costs 19.99 1.fmt 04d returns 0001 costs .2f pen 19.99 returns pen costs 19.99 0 costs 1 .2f .format pen 19.99 returns pen costs 19.99 format ~a costs ~1,2f pen 19.99 returns pen costs 19.99 tests two strings equal see also equality // example c hello world // returns true example visual basic hello world returns true not= hello world ⇒ true 'hello ne 'world returns 1 'hello ne 'world returns true hello -ne world returns true see find see find see find see rfind languages languages without built-in trim function usually simple create custom function accomplishes task awk one use regular expressions trim standard trim function c c++ available string libraries c contain code implements trimming functions significantly ease efficient implementation function also often called eatwhitespace non-standard c libraries c programmers often combine ltrim rtrim implement trim void rtrim char *str void ltrim char *str void trim char *str open source c++ library boost several trim variants including standard one trimmed boost :algorithm :trim_copy string note boost function named simply codice_3 input sequence modified in-place return result another open source c++ library qt several trim variants including standard one trimmed s.trimmed linux kernel also includes strip function codice_4 since 2.6.18-rc1 trims string place since 2.6.33-rc1 kernel uses codice_5 instead codice_4 avoid false warnings trim algorithm haskell may interpreted follows f drops preceding whitespace reverses string f applied output note type signature second line optional trim algorithm j functional description filter codice_7 non-space characters codice_8 leading codice_9 codice_10 trailing codice_11 spaces built-in trim function javascript 1.8.1 firefox 3.5 later ecmascript 5 standard earlier versions added string object prototype follows string.prototype.trim function perl 5 built-in trim function however functionality commonly achieved using regular expressions example string =~ s/^\s+// remove leading whitespace string =~ s/\s+ // remove trailing whitespace string =~ s/^\s+|\s+ //g remove leading trailing whitespace examples modify value original variable codice_12 also available perl stripltspace codice_13 cpan however two functions commonly used strip whitespace end strings codice_14 codice_15 perl 6 upcoming major revision language strings codice_3 method example string string.trim remove leading trailing whitespace string .= trim thing tcl codice_19 command three relevant subcommands codice_3 codice_21 codice_22 commands additional argument may specified string represents set characters remove—the default whitespace space tab newline carriage return example trimming vowels set string onomatopoeia set trimmed string trim string aeiou result nomatop set r_trimmed string trimright string aeiou result onomatop set l_trimmed string trimleft string aeiou result nomatopoeia xslt includes function codice_23 strips leading trailing whitespace addition replacing whitespace sequence including line breaks single space example xsl variable name='trimmed /xsl variable xslt 2.0 includes regular expressions providing another mechanism perform string trimming another xslt technique trimming utilize xpath 2.0 codice_24 function
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Programming language topics
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simple features simple features officially simple feature access open geospatial consortium ogc international organization standardization iso standard iso 19125 specifies common storage access model mostly two-dimensional geometries point line polygon multi-point multi-line etc used geographic information systems iso 19125 standard comes two parts part one iso 19125-1 sfa-ca common architecture defines model two-dimensional simple features linear interpolation vertices data model defined sfa-ca hierarchy classes part also defines representation using well-known text binary part 2 standard iso 19125-2 sfa-sql defines implementation using sql opengis standard cover implementations corba ole/com well although lagged behind sql one standardized iso iso/iec 13249-3 sql/mm spatial extends simple features data model mainly circular interpolations e.g circular arcs adds features like coordinate transformations methods validating geometries well geography markup language support geometries also associated spatial reference systems standard also specifies attributes methods assertions geometries general 2d geometry simple contains self-intersection specification defines de-9im spatial predicates several spatial operators used generate new geometries existing geometries part 2 simple feature access implemented varying degrees gdal library implements simple features data model ogr component java-based deegree framework implements sfa part 1 various ogc standards geosparql ogc standard intended allow geospatially-linked data representation querying based rdf sparql defining ontology geospatial reasoning supporting small simple features well de-9im rcc8 rdfs/owl vocabulary gml wkt literals 2012 various nosql databases limited support anything complex bounding box proximity search
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Databases
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http file server http file server otherwise known hfs free web server specifically designed publishing sharing files complete feature set differs web servers lacks common features like cgi even ability run windows service includes example counting file downloads even advised using ordinary web server hfs small http file server aimed mostly sharing files download official documentation describes hfs hfs http file server file sharing software allows send receive files limit sharing friends open whole world hfs different classic file sharing network hfs web server uses web technology compatible today internet since actually web server friends download files downloading website using web browser internet explorer firefox users n't install new software hfs lets share files web servers used publish website hfs designed however free use way wish risk latest beta version 2.3 hfs includes proprietary scripting language known macros used expand functionality program scripts used variety methods including event handlers directly web pages macros even written bypass program account system custom one hfs used typical web-server however easy support requires variety unconventional programming methods version 2.3 due lack support php cgi development started august 2002 reached version 1.0 september year hfs multiple security issues past states website 2013 current known security bugs latest version hfs open source anyone able easily check security flaws many expert users although designed extremely robust hfs stable used months without restart used stunnel provide https ssl/tls
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Web technology
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playstation 3 models playstation 3 video game console produced various models life cycle launch playstation 3 available either 20 40 60 80 gb hard disk drive us japan priced us 499 us 599 either 40 60 80 gb hard disk drive europe priced £299 £425 since sony released two redesigned models slim super slim models total number consoles sold estimated 77 million several original playstation 3 hardware models commonly referred size included hard disk drive 20 40 60 80 160 gb although referred hdd size capabilities consoles vary region release date difference appearance first five models color trim number usb ports presence absence door covers flash card readers equipped models minor changes air vents retail packages include one two sixaxis controllers dualshock 3 controller beginning june 12 2008 one type-a mini-b usb cable connecting controller playstation portable system one composite video/stereo audio output cable one ethernet cable 20 60 cechexx 80 gb one power cable models support software emulation original playstation support playstation 2 backward compatibility diminished later compatible models last model integrated backward compatibility ntsc 80 gb ceche metal gear solid 4 bundle compatibility issues games systems detailed public database hosted manufacturer models excluding 20 gb model include 802.11 b/g wi-fi addition features 20 gb model 60 gb model internal ieee 802.11 b/g wi-fi multiple flash card readers sd/multimedia card compactflash type i/type ii microdrive memory stick/pro/duo chrome colored trim terms hardware 80 gb model ceche released south korea identical 60 gb model cechc released pal regions except difference hard drive size european 60gb model cechc south korean north american ceche 80gb model excludes playstation 2 emotion engine cpu chip replaced emulated version via cell broadband engine however retains graphics synthesizer gpu resulting hybrid hardware software emulation due elimination emotion engine replacement software-emulated version level playstation 2 compatibility slightly reduced 40 gb 80 gb cechl cechm cechk 160 gb models two usb ports instead four usb ports models include multiple flash card readers sacd support backward compatibility playstation 2 games due removal graphics synthesizer gpu stripped units playstation 2 based hardware official wi-fi flash memory card readers ever released sony 20 gb system although sony plans september 2009 sony placed emphasis proposed add-ons nevertheless model features four usb 2.0 ports wireless networking flash memory card support already obtained use widely available external usb adapters third-party ps3-specific media hubs rumored cell processors third-generation ps3s 40 gb 2008 80 gb cechl cechm cechk 160 gb would move 90 nm process newer 65 nm process scei ceo kaz hirai later confirmed later 45 nm change lowers power consumption console makes less expensive produce redesigned version playstation 3 commonly referred ps3 slim officially branded ps3 features upgradeable 120 gb 160 gb 250 gb 320 gb hard drive 33 smaller 36 lighter consumes 34 cech-20xx 45 cech-21xx less power previous model one third original ps3 model cell microprocessor moved 45 nm manufacturing process lets run cooler quieter previous models cooling system redesigned rsx moved 40 nm process latest revision ps3 slim also includes support cec commonly referred manufacturer brandings braviasync viera link easylink etc allows control console hdmi using tv remote control ps3 slim longer main power switch like previous ps3 models similar redesigned slimline playstation 2 support emulation play ps2 titles present slim version however shortly release ps3 slim sony announced new series ps2 remasters called classics hd ps2 psp titles remastered hd ps3 trophies sometimes playstation move compatibility added october 2011 ps2 classics available purchase playstation store ps3 slim officially released september 1 2009 north america europe september 3 2009 japan australia new zealand however retailers amazon.com best buy gamestop started sell ps3 slim august 25 2009 ps3 slim sold excess million units first 3 weeks sale 250 gb final fantasy xiii -themed ps3 slim white color pink designs officially announced september 24 2009 tokyo game show part bundle japan final fantasy xiii initially revealed u.s. federal communications commission fcc filings ps3 cech-2000b sony computer entertainment australia also announced later day would bringing 250 gb ps3 slim australia would bundled games feature final fantasy xiii theme although north american bundles announced 250 gb ps3 slim sold stand-alone console north america july 2010 sony announced two new sizes slim ps3 160 gb 320 gb 120 gb model discontinued japan launched july 29 2010 japan 160 gb version available classic white well standard charcoal black black 160 gb version also made available bundle japan-only dvr accessory torne later announced new sizes launched regions 160 gb model available august 2010 north america october 2010 europe 320 gb model available north america part bundle playstation move playstation eye copy sports champions europe playstation move playstation eye demo disc bundles released september 19 2010 september 15 2010 respectively coincide launch playstation move september 2012 sony announced new slimmer ps3 redesign cech-4000 due released late 2012 would available either 250 gb 500 gb hard drive pal regions 250 gb model available model 12 gb flash memory cech-4000a available place standalone 250 gb hard drive cech-zhd1 available upgrade model uk 500 gb model released september 28 2012 12 gb model made available october 12 2012 cech-4000b consoles hard drives weigh approximately cech-4000a weighs approximately roughly 25 smaller 20 lighter original ps3 slim version sliding disc cover rather slot-loading drive found previous playstation 3 consoles similar sony bravia kdl22px300 includes built playstation 2 cech-4200 model nearly identical hardware cech-4000 model introduced 2013 follow aacs rule inhibiting analog component composite output blu-ray disc content effective since 2014 previous 3000 4000 models output limit already set 480i meet jan 1st 2011 deadline agreement also aforementioned aacs vertical stand cech-zst1j also available models launched day consoles respective regions
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Computer architecture
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echolink echolink computer-based amateur radio system distributed free charge allows radio amateurs communicate amateur radio operators using voice ip voip technology internet least part path designed jonathan taylor radio amateur call sign k1rfd system allows reliable worldwide connections made radio amateurs greatly enhancing amateur radio communications capabilities essence voip applications skype unique addition ability link amateur radio station transceiver thus low-power handheld amateur radio transceiver contact local echolink node node active echolink station transceiver attached use internet connection station send transmission via voip active echolink node worldwide special hardware software required relay transmission via echolink node using system necessary prospective user callsign validated echolink system requires new user provide positive proof license identity callsign added list validated users cost service ensures system used licensed amateur radio operators software written run 32-bit 64-bit versions microsoft windows another edition software runs apple mobile devices iphone ipod touch ipad available apple app store android version available google play several android app repositories radio amateurs using echolink software operate one two modes radio amateurs without echolink software computer connected internet take advantage echolink network within radio range sysop mode echolink station also possible link sysop mode echolink station local repeater enhancing communication possibilities editions echolink also available two major smartphone platforms february 2010 edition echolink released apple iphone ipad ipod touch app store august 2010 edition echolink released android platform available google play store ios android editions created jonathan taylor k1rfd author original windows edition open source software packages largely compatible echolink available macintosh echomac echoham linux echolinux svxlink/qtel sysop mode required svxlink server linux good alternative features go beyond original software openness makes quite easy extend new functionality echoirlp software add irlp enables irlp node operate sysop mode echolink station echolink software designed run microsoft windows also known work several linux builds well loaded wine
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Internet protocols
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common vulnerability scoring system common vulnerability scoring system cvss free open industry standard assessing severity computer system security vulnerabilities cvss attempts assign severity scores vulnerabilities allowing responders prioritize responses resources according threat scores calculated based formula depends several metrics approximate ease exploit impact exploit scores range 0 10 10 severe many utilize cvss base score determining severity temporal environmental scores also exist factor availability mitigations widespread vulnerable systems within organization respectively current version cvss cvssv3.0 released june 2015 research national infrastructure advisory council niac 2003/2004 led launch cvss version 1 cvssv1 february 2005 goal designed provide open universally standard severity ratings software vulnerabilities initial draft subject peer review review organizations april 2005 niac selected forum incident response security teams first become custodian cvss future development feedback vendors utilizing cvssv1 production suggested significant issues initial draft cvss work cvss version 2 cvssv2 began april 2005 final specification launched june 2007 feedback resulted work beginning cvss version 3 2012 ending cvssv3.0 released june 2015 cvss assessment measures three areas concern numerical score generated metric groups vector string simply vector cvssv2 represents values metrics block text complete documentation cvssv2 available first summary provided access vector av shows vulnerability may exploited attack complexity ac metric describes easy difficult exploit discovered vulnerability authentication au metric describes number times attacker must authenticate target exploit include example authentication network order gain access locally exploitable vulnerabilities value set single multiple authentication required initial access confidentiality c metric describes impact confidentiality data processed system integrity metric describes impact integrity exploited system availability metric describes impact availability target system attacks consume network bandwidth processor cycles memory resources affect availability system six metrics used calculate exploitability impact sub-scores vulnerability sub-scores used calculate overall base score formula_1 formula_2 formula_3 formula_4 metrics concatenated produce cvss vector vulnerability buffer overflow vulnerability affects web server software allows remote user gain partial control system including ability cause shut would give exploitability sub-score 10 impact sub-score 8.5 giving overall base score 9.0 vector base score case would av n/ac l/au n/c p/i p/a c. score vector normally presented together allow recipient fully understand nature vulnerability calculate environmental score necessary value temporal metrics change lifetime vulnerability exploits developed disclosed automated mitigations fixes made available exploitability e metric describes current state exploitation techniques automated exploitation code remediation level rl vulnerability allows temporal score vulnerability decrease mitigations official fixes made available report confidence rc vulnerability measures level confidence existence vulnerability also credibility technical details vulnerability three metrics used conjunction base score already calculated produce temporal score vulnerability associated vector formula used calculate temporal score temporalscore round_to_1_decimal basescore*exploitability*remediationlevel*reportconfidence continue example vendor first informed vulnerability posting proof-of-concept code mailing list initial temporal score would calculated using values shown would give temporal score 7.3 temporal vector e p/rl u/rc uc full vector av n/ac l/au n/c p/i p/a c/e p/rl u/rc uc vendor confirms vulnerability score rises 8.1 temporal vector e p/rl u/rc c temporary fix vendor would reduce score back 7.3 e p/rl t/rc c official fix would reduce 7.0 e p/rl o/rc c possible confident every affected system fixed patched temporal score reduce certain level based vendor actions may increase automated exploit vulnerability developed environmental metrics use base current temporal score assess severity vulnerability context way vulnerable product software deployed measure calculated subjectively typically affected parties collateral damage potential cdp metric measures potential loss impact either physical assets equipment lives financial impact upon affected organisation vulnerability exploited target distribution td metric measures proportion vulnerable systems environment three metrics assess specific security requirements confidentiality cr integrity ir availability ar allowing environmental score fine-tuned according users environment five environmental metrics used conjunction previously assessed base temporal metrics calculate environmental score produce associated environmental vector adjustedimpact min 10,10.41* 1- 1-confimpact*confreq 1-integimpact*integreq 1-availimpact*availreq adjustedtemporal temporalscore recomputed basescores impact sub-equation replaced adjustedimpact equation environmentalscore round_to_1_decimal adjustedtemporal+ 10-adjustedtemporal *collateraldamagepotential *targetdistribution aforementioned vulnerable web server used bank provide online banking services temporary fix available vendor environmental score could assessed would give environmental score 8.2 environmental vector cdp mh/td h/cr h/ir h/ar l. score within range 7.0-10.0 therefore constitutes critical vulnerability context affected bank business several vendors organizations expressed dissatisfaction cvssv2 risk based security manages open sourced vulnerability database open security foundation jointly published public letter first regarding shortcomings failures cvssv2 authors cited lack granularity several metrics results cvss vectors scores properly distinguish vulnerabilities different type risk profiles cvss scoring system also noted requiring much knowledge exact impact vulnerability oracle introduced new metric value partial+ confidentiality integrity availability fill perceived gaps description partial complete official cvss specifications address criticisms development cvss version 3 started 2012 final specification named cvss v3.0 released june 2015 addition specification document user guide examples document also released several metrics changed added removed numerical formulas updated incorporate new metrics retaining existing scoring range 0-10 textual severity ratings none 0 low 0.1-3.9 medium 4.0-6.9 high 7.0-8.9 critical 9.0-10.0 defined similar categories nvd defined cvss v2 part standard base vector new metrics user interaction ui privileges required pr added help distinguish vulnerabilities required user interaction user administrator privileges exploited previously concepts part access vector metric cvssv2 base vector also saw introduction new scope metric designed make clear vulnerabilities may exploited used attack parts system network new metrics allow base vector clearly express type vulnerability evaluated confidentiality integrity availability c metrics updated scores consisting none low high rather none partial complete cvssv2 allows flexibility determining impact vulnerability cia metrics access complexity renamed attack complexity ac make clear access privileges moved separate metric metric describes repeatable exploit vulnerability may ac high attacker requires perfect timing circumstances user interaction also separate metric may easily duplicated future attempts attack vector av saw inclusion new metric value physical p describe vulnerabilities require physical access device system perform temporal metrics essentially unchanged cvssv2 environmental metrics cvssv2 completely removed replaced essentially second base score known modified vector modified base intended reflect differences within organization company compared world whole new metrics capture importance confidentiality integrity availability specific environment added blog post september 2015 cert coordination center discussed limitations cvssv2 cvssv3.0 use scoring vulnerabilities emerging technology systems internet things minor update cvss released june 17 2019 goal cvss version 3.1 clarify improve upon existing cvss version 3.0 standard without introducing new metrics metric values allowing frictionless adoption new standard scoring providers scoring consumers alike usability prime consideration making improvements cvss standard several changes made cvss v3.1 improve clarity concepts introduced cvss v3.0 thereby improve overall ease use standard first used input industry subject-matter experts continue enhance refine cvss applicable vulnerabilities products platforms developed past 15 years beyond primary goal cvss provide deterministic repeatable way score severity vulnerability across many different constituencies allowing consumers cvss use score input larger decision matrix risk remediation mitigation specific particular environment risk tolerance updates cvss version 3.1 specification include clarification definitions explanation existing base metrics attack vector privileges required scope security requirements new standard method extending cvss called cvss extensions framework also defined allowing scoring provider include additional metrics metric groups retaining official base temporal environmental metrics additional metrics allow industry sectors privacy safety automotive healthcare etc. score factors outside core cvss standard finally cvss glossary terms expanded refined cover terms used throughout cvss version 3.1 documentation cvssv2 base score adopted primary method quantifying severity vulnerabilities wide range organisations companies including nvd plans begin scoring vulnerabilities using cvssv3.0 addition cvssv2 sometime fall 2015
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Computer security
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moxie marlinspike matthew rosenfeld known moxie marlinspike american entrepreneur cryptographer computer security researcher marlinspike creator signal co-founder signal foundation currently serves ceo signal messenger also co-author signal protocol encryption used signal whatsapp facebook messenger skype allo responsible largest deployment consumer end-to-end encryption marlinspike former head security team twitter author proposed ssl authentication system replacement called convergence previously maintained cloud-based wpa cracking service targeted anonymity service called googlesharing originally state georgia marlinspike moved san francisco late 1990s worked several technology companies including enterprise infrastructure software maker bea systems inc 2004 marlinspike bought derelict sailboat along three friends refurbished sailed around bahamas making documentary journey called hold fast 2010 marlinspike chief technology officer co-founder whisper systems enterprise mobile security startup company may 2010 whisper systems launched textsecure redphone applications provided end-to-end encrypted sms messaging voice calling respectively company acquired social-media firm twitter undisclosed amount late 2011 acquisition done primarily mr. marlinspike could help then-startup improve security time head cybersecurity twitter firm made whisper systems apps open source marlinspike left twitter early 2013 founded open whisper systems collaborative open source project continued development textsecure redphone time marlinspike trevor perrin started developing signal protocol early version first introduced textsecure app february 2014 november 2015 open whisper systems unified textsecure redphone applications signal 2014 2016 marlinspike worked whatsapp facebook google integrate signal protocol messaging services february 21 2018 marlinspike whatsapp co-founder brian acton announced formation signal foundation 2009 paper marlinspike introduced concept ssl stripping man-in-the-middle attack network attacker could prevent web browser upgrading ssl connection subtle way would likely go unnoticed user also announced release tool codice_1 would automatically perform types man-in-the-middle attacks http strict transport security hsts specification subsequently developed combat attacks marlinspike discovered number different vulnerabilities popular ssl implementations notably marlinspike published 2002 paper exploiting ssl/tls implementations correctly verify x.509 v3 basicconstraints extension public key certificate chains allowed anyone valid ca-signed certificate domain name create appeared valid ca-signed certificates domain vulnerable ssl/tls implementations included microsoft cryptoapi making internet explorer windows software relied ssl/tls connections vulnerable man-in-the-middle attack 2011 vulnerability discovered remained present ssl/tls implementation apple inc. ios also notably marlinspike presented 2009 paper introduced concept null-prefix attack ssl certificates revealed major ssl implementations failed properly verify common name value certificate could tricked accepting forged certificates embedding null characters cn field 2011 marlinspike presented talk titled ssl future authenticity black hat security conference las vegas outlined many current problems certificate authorities announced release software project called convergence replace certificate authorities 2012 marlinspike trevor perrin submitted internet draft tack designed provide ssl certificate pinning help solve ca problem ietf 2012 marlinspike david hulton presented research makes possible reduce security ms-chapv2 handshakes single des encryption hulton built hardware capable cracking remaining des encryption less 24 hours two made hardware available anyone use internet service marlinspike says flying within united states unable print boarding pass required airline ticketing agents make phone call order issue one subjected secondary screening tsa security checkpoints entering united states via flight dominican republic 2010 marlinspike detained federal agents nearly five hours electronic devices confiscated first agents claimed would get back provided passwords could decrypt data marlinspike refused devices eventually returned though noted could longer trust saying could modified hardware installed new keyboard firmware
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Computer security
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document style semantics specification language document style semantics specification language dsssl international standard developed provide stylesheets sgml documents dsssl consists two parts tree transformation process used manipulate tree structure documents prior presentation formatting process associates elements source document specific nodes target representation—the flow object tree dsssl specifications device-independent pieces information interchanged different platforms dsssl standardize back-end formatters generate language output formatters may render output on-screen display write computer file specific format postscript rich text format based subset scheme programming language specified standard iso/iec 10179:1996 developed iso/iec jtc1/sc34 iso/iec joint technical committee 1 subcommittee 34 document description processing languages sgml contains information machine-readable human-readable format stylesheet used present information stored sgml pleasing accessible way dsssl convert wide range formats including rtf html latex dsssl compatible sgml-based document type used often docbook 1997 software engineer geir ove grønmo published syntax highlighting language definition kedit appearance xml alternative sgml xml associated stylesheet language xsl also widely rapidly adopted around 1999 although dsssl continued use within shrinking sgml field xsl soon use extensively coders dsssl ever achieved emphasised previous sgml strongholds docbook converted sgml xml also converted favoured stylesheet language dsssl xsl sometime 1994 opera software began drafting dsssl lite specification consideration world wide web consortium since dsssl thought complex world wide web
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Programming language topics
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relational algebra relational algebra first created edgar f. codd ibm family algebras well-founded semantics used modelling data stored relational databases defining queries main application relational algebra providing theoretical foundation relational databases particularly query languages databases chief among sql relational algebra received little attention outside pure mathematics publication e.f. codd relational model data 1970 codd proposed algebra basis database query languages see section implementations five primitive operators codd algebra selection projection cartesian product also called cross product cross join set union set difference relational algebra uses set union set difference cartesian product set theory adds additional constraints operators set union set difference two relations involved must union-compatible —that two relations must set attributes set intersection defined terms set union set difference two relations involved set intersection must also union-compatible cartesian product defined two relations involved must disjoint headers—that must common attribute name addition cartesian product defined differently one set theory sense tuples considered shallow purposes operation cartesian product set n -tuples set -tuples yields set flattened -tuples whereas basic set theory would prescribed set 2-tuples containing n -tuple -tuple formally r × defined follows formula_1 cardinality cartesian product product cardinalities factors r × r × projection unary operation written formula_2 formula_3 set attribute names result projection defined set obtained tuples r restricted set formula_4 note implemented sql standard default projection returns multiset instead set projection obtained addition codice_1 keyword eliminate duplicate data generalized selection unary operation written formula_5 propositional formula consists atoms allowed normal selection logical operators negation selection selects tuples r holds obtain listing friends business associates address book selection might written formula_6 result would relation containing every attribute every unique record true true rename unary operation written formula_7 result identical r except b attribute tuples renamed attribute simply used rename attribute relation relation rename 'isfriend attribute 'isbusinesscontact relation formula_8 might used natural join ⋈ binary operator written r ⋈ r relations result natural join set combinations tuples r equal common attribute names example consider tables employee dept natural join also used define composition relations example composition employee dept join shown projected common attribute deptname category theory join precisely fiber product natural join arguably one important operators since relational counterpart logical note carefully variable appears two predicates connected variable stands thing appearances must always substituted value particular natural join allows combination relations associated foreign key example example foreign key probably holds employee deptname dept deptname natural join employee dept combines employees departments works foreign key holds attributes name case foreign key dept manager employee name rename columns take natural join join sometimes also referred equijoin see θ -join formally semantics natural join defined follows fun predicate true relation mathematical sense iff function usually required r must least one common attribute constraint omitted r common attributes natural join becomes exactly cartesian product natural join simulated codd primitives follows assume c ... c attribute names common r r ... r attribute names unique r ... attribute names unique furthermore assume attribute names x ... x neither r first step rename common attribute names take cartesian product select tuples joined finally take projection get rid renamed attributes consider tables car boat list models cars boats respective prices suppose customer wants buy car boat want spend money boat car θ -join ⋈ predicate carprice ≥ boatprice produces flattened pairs rows satisfy predicate using condition attributes equal example price condition may specified price price alternatively price want combine tuples two relations combination condition simply equality shared attributes convenient general form join operator θ -join theta-join θ -join binary operator written formula_9 formula_10 b attribute names θ binary relational operator set ≤ ≠ ≥ v value constant r relations result operation consists combinations tuples r satisfy θ result θ -join defined headers r disjoint contain common attribute simulation operation fundamental operations therefore follows case operator θ equality operator join also called equijoin note however computer language supports natural join selection operators need θ -join well achieved selection result natural join degenerates cartesian product shared attributes sql implementations joining predicate usually called inner join keyword allows one specify predicate used filter rows important note forming flattened cartesian product filtering rows conceptually correct implementation would use sophisticated data structures speed join query left semijoin joining similar natural join written r ⋉ r relations result set tuples r tuple equal common attribute names difference natural join columns appear example consider tables employee dept semijoin formally semantics semijoin defined follows fun r definition natural join semijoin simulated using natural join follows ... attribute names r since simulate natural join basic operators follows also holds semijoin codd 1970 paper semijoin called restriction antijoin written r ▷ r relations similar semijoin result antijoin tuples r tuple equal common attribute names example consider tables employee dept antijoin antijoin formally defined follows fun ∪ definition natural join antijoin also defined complement semijoin follows given antijoin sometimes called anti-semijoin antijoin operator sometimes written semijoin symbol bar instead ▷ division binary operation written r ÷ division implemented directly sql result consists restrictions tuples r attribute names unique r i.e. header r header holds combinations tuples present r example see tables completed dbproject division dbproject contains tasks database project result division contains exactly students completed tasks database project formally semantics division defined follows ... set attribute names unique r ... restriction set usually required attribute names header subset r otherwise result operation always empty simulation division basic operations follows assume ... attribute names unique r b ... b attribute names first step project r unique attribute names construct combinations tuples prior example would represent table every student student unique key attribute completed table combined every given task eugene instance would two rows eugene → database1 eugene → database2 t. relation u possible combinations could r n't restrictions tuples r combinations tuples present r remains done take projection r unique attribute names subtract v practice classical relational algebra described extended various operations outer joins aggregate functions even transitive closure whereas result join inner join consists tuples formed combining matching tuples two operands outer join contains tuples additionally tuples formed extending unmatched tuple one operands fill values attributes operand outer joins considered part classical relational algebra discussed far operators defined section assume existence null value ω define used fill values practice corresponds null sql order make subsequent selection operations resulting table meaningful semantic meaning needs assigned nulls codd approach propositional logic used selection extended three-valued logic although elide details article three outer join operators defined left outer join right outer join full outer join word outer sometimes omitted left outer join written r ⟕ r relations result left outer join set combinations tuples r equal common attribute names addition loosely speaking tuples r matching tuples example consider tables employee dept left outer join resulting relation tuples common values common attribute names tuples r take null value ω since tuples dept deptname finance executive ω occur resulting relation tuples employee deptname finance executive let r r ... r attributes relation r let ω ... ω singleton relation attributes unique relation attributes r left outer join described terms natural join hence using basic operators follows right outer join behaves almost identically left outer join roles tables switched right outer join relations r written r ⟖ result right outer join set combinations tuples r equal common attribute names addition tuples matching tuples r example consider tables employee dept right outer join resulting relation tuples r common values common attribute names tuples take null value ω since tuples employee deptname production ω occur name empid attributes resulting relation tuples dept deptname production let ... attributes relation let ω ... ω singleton relation attributes unique relation r attributes left outer join right outer join simulated using natural join follows ⟗the outer join full outer join effect combines results left right outer joins full outer join written r ⟗ r relations result full outer join set combinations tuples r equal common attribute names addition tuples matching tuples r tuples r matching tuples common attribute names example consider tables employee dept full outer join resulting relation tuples r common values common attribute names tuples take null value ω tuples common values common attribute names tuples r also take null value ω full outer join simulated using left right outer joins hence natural join set union follows nothing relational algebra introduced far would allow computations data domains evaluation propositional expressions involving equality example possible using algebra introduced far write expression would multiply numbers two columns e.g unit price quantity obtain total price practical query languages facilities e.g sql select allows arithmetic operations define new columns result similar facility provided explicitly tutorial codice_2 keyword database theory called extended projection furthermore computing various functions column like summing elements also possible using relational algebra introduced far five aggregate functions included relational database systems operations sum count average maximum minimum relational algebra aggregation operation schema ... written follows 1 ≤ j ≤ k one original attributes 1 ≤ ≤ n attributes preceding g grouping attributes function like group clause sql arbitrary number aggregation functions applied individual attributes operation applied arbitrary relation r grouping attributes optional supplied aggregation functions applied across entire relation operation applied let assume table named three columns namely wish find maximum balance branch accomplished g find highest balance accounts regardless branch could simply write g although relational algebra seems powerful enough practical purposes simple natural operators relations expressed relational algebra one transitive closure binary relation given domain let binary relation r subset × transitive closure r r smallest subset × contains r satisfies following condition relational algebra expression e r taking r variable argument produces r proved using fact given relational expression e claimed e r r r variable always find instance r r corresponding domain e r ≠ r. sql however officially supports fixpoint queries since 1999 vendor-specific extensions direction well queries represented tree primary goal transform expression trees equivalent expression trees average size relations yielded subexpressions tree smaller optimization secondary goal try form common subexpressions within single query one query evaluated time queries rationale behind second goal enough compute common subexpressions results used queries contain subexpression present set rules used transformations rules selection operators play important role query optimization selection operator effectively decreases number rows operand manage move selections expression tree towards leaves internal relations yielded subexpressions likely shrink selection idempotent multiple applications selection additional effect beyond first one commutative order selections applied effect eventual result selection whose condition conjunction simpler conditions equivalent sequence selections individual conditions selection whose condition disjunction equivalent union selections identities used merge selections fewer selections need evaluated split component selections may moved optimized separately cross product costliest operator evaluate input relations n rows result contain formula_19 rows therefore important best decrease size operands applying cross product operator effectively done cross product followed selection operator e.g formula_20 considering definition join likely case cross product followed selection operator try push selection higher levels expression tree using selection rules case break condition conditions b c using split rules complex selection conditions formula_21 b contains attributes r c contains attributes p contains part contains attributes r p note b c possibly empty following holds selection distributive set difference intersection union operators following three rules used push selection set operations expression tree set difference intersection operators possible apply selection operator one operands following transformation beneficial one operands small overhead evaluating selection operator outweighs benefits using smaller relation operand selection commutes projection fields referenced selection condition subset fields projection performing selection projection may useful operand cross product join cases selection condition relatively expensive compute moving selection outside projection may reduce number tuples must tested since projection may produce fewer tuples due elimination duplicates resulting omitted fields projection idempotent series valid projections equivalent outermost projection projection distributive set union projection distribute intersection set difference counterexamples given b assumed distinct successive renames variable collapsed single rename rename operations variables common arbitrarily reordered respect one another exploited make successive renames adjacent collapsed rename distributive set difference union intersection cartesian product distributive union first query language based codd algebra alpha developed dr. codd subsequently isbl created pioneering work acclaimed many authorities shown way make codd idea useful language business system 12 short-lived industry-strength relational dbms followed isbl example 1998 chris date hugh darwen proposed language called tutorial intended use teaching relational database theory query language also draws isbl ideas rel implementation tutorial d. even query language sql loosely based relational algebra though operands sql tables exactly relations several useful theorems relational algebra hold sql counterpart arguably detriment optimisers and/or users sql table model bag multiset rather set example expression formula_39 theorem relational algebra sets relational algebra bags treatment relational algebra bags see chapter 5 complete textbook garcia-molina ullman widom practically academic textbook databases detailed treatment classic relational algebra
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Databases
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tuple relational calculus tuple calculus calculus created introduced edgar f. codd part relational model order provide declarative database-query language data manipulation data model formed inspiration database-query languages quel sql latter although far less faithful original relational model calculus de facto standard database-query language dialect used nearly every relational-database-management system michel lacroix alain pirotte proposed domain calculus closer first-order logic together codd showed calculi well relational algebra equivalent expressive power subsequently query languages relational model called relationally complete could express least queries since calculus query language relational databases first define relational database basic relational building block domain somewhat similar equal data type tuple finite sequence attributes ordered pairs domains values relation set ordered pairs domains names relation serves header relation relation set compatible tuples although relational concepts mathematically defined definitions map loosely traditional database concepts table accepted visual representation relation tuple similar concept row first assume existence set c column names examples name author address etcetera define headers finite subsets c relational database schema defined tuple r h domain atomic values see relational model notions domain atomic value r finite set relation names function associates header relation name r note simplification full relational model one domain header set column names also maps column names domain given domain define tuple partial function maps column names atomic value example would name harry age 25 set tuples denoted subset c tuple defined called domain confused domain schema denoted dom finally define relational database given schema r h function maps relation names r finite subsets every relation name r r tuple db r holds latter requirement simply says tuples relation contain column names namely defined schema construction formulas assume infinite set v tuple variables formulas defined given database schema r h partial function type v ⇸ 2 called type assignment assigns headers tuple variables define set atomic formulas type following rules examples atoms formal semantics atoms defined given database db tuple variable binding val v → maps tuple variables tuples domain atoms combined formulas usual first-order logic logical operators ∧ ∨ ¬ use existential quantifier ∃ universal quantifier ∀ bind variables define set formulas f type inductively following rules examples formulas note last formula states books written c. j date subject relational model usual omit brackets causes ambiguity semantics formula assume quantifiers quantify universe tuples domain schema leads following formal semantics formulas given database db tuple variable binding val v finally define query expression looks like given schema r h v tuple variable h header f v formula f type type v h v free variable result query given database db set tuples dom h f true db val v examples query expressions semantics quantifiers quantify tuples domain schema query may return different result certain database another schema presumed example consider two schemas r h r h domains 1 1 2 relation names r r headers h r schemas common instance consider following query expression result db either 1 1 2 also clear take domain infinite set result query also infinite solve problems restrict attention queries domain independent i.e. queries return result database schemas interesting property queries assume tuple variables range tuples so-called active domain database subset domain occurs least one tuple database query expression semantics query expressions change fact many definitions tuple calculus semantics quantifiers defined makes queries definition domain independent order limit query expressions express domain-independent queries syntactical notion safe query usually introduced determine whether query expression safe derive two types information query first whether variable-column pair bound column relation constant second whether two variable-column pairs directly indirectly equated denoted v == w deriving boundedness introduce following reasoning rules deriving equatedness introduce following reasoning rules next usual reasoning rules equivalence relations reflexivity symmetry transitivity say query expression v h f v safe restriction safe query expressions limit expressiveness since domain-independent queries could expressed also expressed safe query expression proven showing schema r h given set k constants query expression tuple variable v header h construct safe formula every pair v h states value active domain example assume k 1,2 r r h r b corresponding safe formula v .b formula used rewrite unsafe query expression equivalent safe query expression adding formula every variable v column name type used expression effectively means let variables range active domain already explained change semantics expressed query domain independent
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Databases
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trusted computer system evaluation criteria trusted computer system evaluation criteria tcsec united states government department defense dod standard sets basic requirements assessing effectiveness computer security controls built computer system tcsec used evaluate classify select computer systems considered processing storage retrieval sensitive classified information tcsec frequently referred orange book centerpiece dod rainbow series publications initially issued 1983 national computer security center ncsc arm national security agency updated 1985 tcsec eventually replaced common criteria international standard originally published 2005 24 october 2002 orange book aka dodd 5200.28-std canceled dodd 8500.1 later reissued dodi 8500.02 14 march 2014 security policy must explicit well-defined enforced computer system three basic security policies specified individual accountability regardless policy must enforced secure means must exist ensure access authorized competent agent evaluate accountability information within reasonable amount time without undue difficulty accountability objective includes three requirements computer system must contain hardware/software mechanisms independently evaluated provide sufficient assurance system enforces requirements extension assurance must include guarantee trusted portion system works intended accomplish objectives two types assurance needed respective elements within class additional set documentation addresses development deployment management system rather capabilities documentation includes tcsec defines four divisions c b division highest security division represents significant difference trust individual organization place evaluated system additionally divisions c b broken series hierarchical subdivisions called classes c1 c2 b1 b2 b3 a1 division class expands modifies indicated requirements immediately prior division class publication entitled army regulation 380-19 example guide determining system class used given situation
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Computer security
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facetime facetime proprietary videotelephony product developed apple inc. facetime available supported ios mobile devices macintosh computers run later facetime supports ios device forward-facing camera macintosh computer equipped facetime camera facetime audio audio-only version available ios device supports ios 7 newer macintosh forward-facing camera running later facetime included free ios macos 10.7 onwards apple bought facetime name facetime communications changed name actiance inc. june 7 2010 apple announced facetime conjunction iphone 4 apple bought facetime name facetime communications changed name actiance january 2011 june 7 2010 apple announced facetime conjunction iphone 4 support fourth generation ipod touch first model ipod touch equipped cameras announced conjunction device release september 8 2010 facetime announced october 20 2010 march 2 2011 facetime support announced newly introduced ipad 2 forward- rear-facing cameras february 24 2011 facetime left beta listed mac app store us 0.99 apple claims intended provide application free charge however provision sarbanes–oxley act 2002 bars companies providing unadvertised new feature already-sold product without enduring onerous accounting measures us 0.99 beta still available download apple facetime included free macos 10.7 onwards ios allowed customers use facetime long tiered blocked application working customers unlimited data plans brought federal communications commission fcc net neutrality violations may 2011 found facetime would work seamlessly 3g iphone ipad ipod touch models supported even though facetime worked 3g time supports 4g lte calls networks world availability limited operators gsm plans june 2018 apple announced facetime would support group video audio calls 32 people ios 12 macos mojave facetime works establishing connection two supported devices apple devices iphones ipads macs introduced 2011 support facetime facetime currently incompatible non-apple devices video calling services mac models introduced 2011 high-definition video facetime devices use automatically ends facetime hd camera unlike mac os x ichat facetime currently support group conferencing support announced ios 12 application one-on-one video chat—only two people talk second user calls user answers video chat previous user ends new video session begins second caller iphone phone call pending user attempts answer video call ends phone call begins next user incoming notifications ios devices shown facetime call opened video temporarily paused user back facetime app iphone user activate facetime phone call pressing facetime button initiated facetime call history contacts application ios 7 newer also provide separate facetime app always apple non-telephony devices ipad ipod touch mac release ios 6 facetime required wifi connection work ios 6 onwards facetime iphone ipad supported facetime calls cellular networks 3g lte provided carrier enabled mid-2013 virtually carriers worldwide allowed facetime audio uses three megabytes data every five minutes conversation facetime video using significantly cellular talk time/minutes used switching voice call facetime call facetime calls placed supported devices phone number email address registered facetime service single email address registered multiple devices call placed address rings devices simultaneously facetime protocol based numerous open industry standards although interoperable videotelephony systems upon launch iphone 4 jobs stated apple would immediately start working standards bodies make facetime protocol open industry standard protocols open standards apple facetime service requires client-side certificate facetime calls protected end-to-end encryption sender receiver access apple decrypt data compared sip implementations facetime adds techniques enhance performance cost breaking interoperability port multiplexing sdp minimization sdp compression new audio-only version facetime named facetime audio announced annual apple worldwide developers conference wwdc keynote speech june 10 2013 released ios 7 september 18 2013 audio-only version facetime effectively makes protocol voice internet protocol voip competes mainstream providers field including skype microsoft based aac-ld audio protocol service provides high-quality audio ios 7 betas limited facetime audio calls placed wi-fi network original limitation video version facetime final release removed restriction allow work 3g lte data connections case carriers plans regard facetime video like video version facetime audio currently available apple devices feature available run ipod touch 4th generation device support ios 7 later facetime streaming cellular data unavailable iphone 4 ipad 2. facetime enabled devices bought united arab emirates possibly due regulations country restrict ip-based communications addition devices bought china facetime audio disabled facetime video available devices bought outside countries support video audio versions facetime although egypt jordan qatar kuwait originally disabled facetime iphone 4 later re-enabled feature carrier update existing phone owners made pre-enabled newly purchased iphone march 2018 facetime available iphones saudi arabia upon updating ios 11.3 august 2019 facetime available iphones pakistan upon updating ios 12.4 april 16 2014 facetime ceased working earlier versions ios previously supported ios 4 5 6 client-side certificate used authenticate genuine apple device facetime servers amongst uses expired date apple chose release update certificate devices newer major ios version new valid certificate available apple release minor update certificate os x versions could run facetime also earlier versions ios small number devices could run facetime could run newer major version ios 4th generation ipod touch result policy almost ios users update ios version devices wished continue using facetime limitation applied even users jailbroken devices since even legally jailbroken device would difficult also illegal extract install apple new certificate without apple permission order work around issue due proprietary nature facetime currently unavailable platforms including android windows january 28 2019 bug discovered facetime app allowed users eavesdrop users without knowledge exploit later discovered video feed could enabled without users acceptance apple said statement would release fix exploit shortly disabling group facetime time bug named facepalm security researchers affects ios devices running facetime ios 12.1 later macintosh computers running macos 10.14.1 mojave later although bug gained international attention january 28 2019 bug found 14-year old high school student arizona mother tried week warn apple problem facebook twitter discovering bug january 20th however pair found impossible reach anyone company short smoke signals trying every method someone could use get hold someone apple said ms. thompson january 25 2019 posted video youtube demonstrating bug news bug finally gained media coverage ms thompson wrote letters emails tweets msgs sent apple 10+ days reporting group facetime bug lets someone listen teenager discovered never heard back ”
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Operating systems
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comparison programming languages type system onlyinclude comparison programming languages type system compares features type systems type checking multiple programming languages brief definitions /onlyinclude
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Programming language topics
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dependency grammar dependency grammar dg class modern grammatical theories based dependency relation opposed relation phrase structure traced back primarily work lucien tesnière dependency notion linguistic units e.g words connected directed links finite verb taken structural center clause structure syntactic units words either directly indirectly connected verb terms directed links called dependencies dgs distinct phrase structure grammars since dgs lack phrasal nodes although acknowledge phrases structure determined relation word head dependents dependency structures flatter phrase structures part lack finite verb phrase constituent thus well suited analysis languages free word order czech slovak warlpiri notion dependencies grammatical units existed since earliest recorded grammars e.g pāṇini dependency concept therefore arguably predates phrase structure many centuries ibn maḍāʾ 12th-century linguist córdoba andalusia may first grammarian use term dependency grammatical sense use today early modern times dependency concept seems coexisted side side phrase structure latter entered latin french english grammars widespread study term logic antiquity dependency also concretely present works sámuel brassai 1800–1897 hungarian linguist 1830-1894 german philologist heimann hariton tiktin 1850–1936 romanian linguist modern dependency grammars however begin primarily work lucien tesnière tesnière frenchman polyglot professor linguistics universities strasbourg montpellier major work éléments de syntaxe structurale published posthumously 1959 – died 1954 basic approach syntax developed seems seized upon independently others 1960s number dependency-based grammars gained prominence since early works dg generated lot interest germany theoretical syntax language pedagogy recent years great development surrounding dependency-based theories come computational linguistics due part influential work david hays machine translation rand corporation 1950s 1960s dependency-based systems increasingly used parse natural language generate tree banks interest dependency grammar growing present international conferences dependency linguistics relatively recent development depling 2011 depling 2013 depling 2015 depling 2017 depling 2019 dependency one-to-one correspondence every element e.g word morph sentence exactly one node structure sentence corresponds element result one-to-one correspondence dependency grammars word morph grammars exist elements dependencies connect elements structure situation compared phrase structure phrase structure one-to-one-or-more correspondence means every element sentence one nodes structure correspond element result difference dependency structures minimal compared phrase structure counterparts since tend contain many fewer nodes trees illustrate two possible ways render dependency phrase structure relations see dependency tree ordered tree i.e reflects actual word order many dependency trees abstract away linear order focus hierarchical order means show actual word order constituency phrase structure tree follows conventions bare phrase structure bps whereby words employed node labels distinction dependency phrase structure grammars derives large part initial division clause phrase structure relation derives initial binary division whereby clause split subject noun phrase np predicate verb phrase vp division certainly present basic analysis clause find works instance leonard bloomfield noam chomsky tesnière however argued vehemently binary division preferring instead position verb root clause structure tesnière stance subject-predicate division stems term logic place linguistics importance distinction one acknowledges initial subject-predicate division syntax real one likely go path phrase structure grammar one rejects division one must consider verb root structure go path dependency grammar following frameworks dependency-based link grammar similar dependency grammar link grammar include directionality linked words thus describe head-dependent relationships hybrid dependency/phrase structure grammar uses dependencies words also includes dependencies phrasal nodes – see example quranic arabic dependency treebank derivation trees tree-adjoining grammar dependency structures although full trees tag rendered terms phrase structure regard clear whether tag viewed dependency phrase structure grammar major differences grammars listed regard dependency relation compatible major tenets theories grammar thus like phrase structure grammars dependency grammars mono- multistratal representational derivational construction- rule-based various conventions dgs employ represent dependencies following schemata addition tree trees illustrate conventions representations a–d trees whereby specific conventions employed tree vary solid lines dependency edges lightly dotted lines projection lines difference tree tree b tree employs category class label nodes whereas tree b employs words node labels tree c reduced tree insofar string words projection lines deemed unnecessary hence omitted tree abstracts away linear order reflects hierarchical order arrow arcs e alternative convention used show dependencies favored word grammar brackets f seldom used nevertheless quite capable reflecting dependency hierarchy dependents appear enclosed brackets heads finally indentations like g another convention sometimes employed indicate hierarchy words dependents placed underneath heads indented like tree indentations g abstract away linear order point conventions namely conventions influence basic commitment dependency relation grouping syntactic units dependency representations show syntactic dependencies indeed work dependency grammar focuses syntactic dependencies syntactic dependencies however one three four types dependencies meaning–text theory instance emphasizes role semantic morphological dependencies addition syntactic dependencies fourth type prosodic dependencies also acknowledged distinguishing types dependencies important part one fails likelihood semantic morphological and/or prosodic dependencies mistaken syntactic dependencies great following four subsections briefly sketch dependency types discussion existence syntactic dependencies taken granted used orientation point establishing nature three dependency types semantic dependencies understood terms predicates arguments arguments predicate semantically dependent predicate often semantic dependencies overlap point direction syntactic dependencies times however semantic dependencies point opposite direction syntactic dependencies entirely independent syntactic dependencies hierarchy words following examples show standard syntactic dependencies whereas arrows indicate semantic dependencies two arguments sam sally tree dependent predicate likes whereby arguments also syntactically dependent likes means semantic syntactic dependencies overlap point direction tree attributive adjectives however predicates take head noun argument hence big predicate tree b takes bones one argument semantic dependency points tree therefore runs counter syntactic dependency similar situation obtains c preposition predicate takes two arguments picture wall one semantic dependencies points syntactic hierarchy whereas points finally predicate help takes one argument jim directly connected jim syntactic hierarchy means semantic dependency entirely independent syntactic dependencies morphological dependencies obtain words parts words given word part word influences form another word latter morphologically dependent former agreement concord therefore manifestations morphological dependencies like semantic dependencies morphological dependencies overlap point direction syntactic dependencies overlap point opposite direction syntactic dependencies entirely independent syntactic dependencies arrows used indicate morphological dependencies plural houses demands plural demonstrative determiner hence appears means morphological dependency points hierarchy houses situation reversed b singular subject sam demands appearance agreement suffix -s finite verb works means morphological dependency pointing hierarchy sam works type determiner german examples c influences inflectional suffix appears adjective alt indefinite article ein used strong masculine ending -er appears adjective definite article der used contrast weak ending -e appears adjective thus since choice determiner impacts morphological form adjective morphological dependency pointing determiner adjective whereby morphological dependency entirely independent syntactic dependencies consider following french sentences masculine subject le chien demands masculine form predicative adjective blanc whereas feminine subject la maison demands feminine form adjective morphological dependency entirely independent syntactic dependencies therefore points across syntactic hierarchy morphological dependencies play important role typological studies languages classified mostly head-marking sam work-s mostly dependent-marking houses whereby languages contain least minor measure head dependent marking prosodic dependencies acknowledged order accommodate behavior clitics clitic syntactically autonomous element prosodically dependent host clitic therefore integrated prosody host meaning forms single word host prosodic dependencies exist entirely linear dimension horizontal dimension whereas standard syntactic dependencies exist hierarchical dimension vertical dimension classic examples clitics english reduced auxiliaries e.g -ll -s -ve possessive marker -s prosodic dependencies following examples indicated hyphen lack vertical projection line hyphens lack projection lines indicate prosodic dependencies hyphen appears left clitic indicates clitic prosodically dependent word immediately left 'll whereas hyphen appears right side clitic shown indicates clitic prosodically dependent word appears immediately right given clitic often prosodically dependent syntactic dependent 'll head would 've times depend prosodically word neither head immediate dependent florida syntactic dependencies focus work dg stated presence direction syntactic dependencies determined course often open debate regard must acknowledged validity syntactic dependencies trees throughout article taken granted however hierarchies many dgs largely support although certainly points disagreement basic question syntactic dependencies discerned proven difficult answer definitively one acknowledge area however basic task identifying discerning presence direction syntactic dependencies dgs easier harder determining constituent groupings phrase structure grammars variety heuristics employed end basic tests constituents useful tools syntactic dependencies assumed trees article grouping words together manner closely matches results standard permutation substitution ellipsis tests constituents etymological considerations also provide helpful clues direction dependencies promising principle upon base existence syntactic dependencies distribution one striving identify root given phrase word responsible determining distribution phrase whole root traditionally dgs different approach linear order word order phrase structure grammars dependency structures minimal compared phrase structure counterparts minimal structures allow one focus intently two ordering dimensions separating vertical dimension hierarchical order horizontal dimension linear order easily accomplished aspect dependency structures allowed dgs starting tesnière 1959 focus hierarchical order manner hardly possible phrase structure grammars tesnière linear order secondary hierarchical order insofar hierarchical order preceded linear order mind speaker stemmas trees tesnière produced reflected view abstracted away linear order focus almost entirely hierarchical order many dgs followed tesnière adopted practice produced tree structures reflect hierarchical order alone e.g traditional focus hierarchical order generated impression dgs little say linear order contributed view dgs particularly well-suited examine languages free word order negative result focus hierarchical order however dearth dg explorations particular word order phenomena standard discontinuities comprehensive dependency grammar accounts topicalization wh -fronting scrambling extraposition mostly absent many established dg frameworks situation contrasted phrase structure grammars devoted tremendous effort exploring phenomena nature dependency relation however prevent one focusing linear order dependency structures capable exploring word order phenomena phrase structures following trees illustrate point represent one way exploring discontinuities using dependency structures trees suggest manner common discontinuities addressed example german used illustrate scrambling discontinuity a-trees left show projectivity violations crossing lines b-trees right demonstrate one means addressing violations displaced constituent takes word head governor words red mark catena =chain words extends root displaced constituent governor constituent discontinuities explored terms catenae limitations topicalization wh -fronting scrambling extraposition explored identified examining nature catenae involved traditionally dgs treated syntactic functions grammatical functions grammatical relations primitive posit inventory functions e.g subject object oblique determiner attribute predicative etc. functions appear labels dependencies tree structures e.g syntactic functions tree shown green attr attribute comp-p complement preposition comp-to complement det determiner p-attr prepositional attribute pred predicative subj subject to-comp complement functions chosen abbreviations used tree merely representative general stance dgs toward syntactic functions actual inventory functions designations employed vary dg dg primitive theory status functions much different phrase structure grammars traditionally phrase structure grammars derive syntactic functions constellation instance object identified np appearing inside finite vp subject np appearing outside finite vp since dgs reject existence finite vp constituent never presented option view syntactic functions manner issue question comes first traditionally dgs take syntactic functions primitive derive constellation functions whereas phrase structure grammars traditionally take constellation primitive derive syntactic functions constellation question comes first functions constellation inflexible matter stances grammar types dependency phrase structure narrowly limited traditional views dependency phrase structure fully compatible approaches syntactic functions indeed monostratal systems based dependency phrase structure likely reject notion functions derived constellation constellation derived functions take primitive means neither derived
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Computational linguistics
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openbsd security features openbsd operating system focuses security development security features according author michael w. lucas openbsd widely regarded secure operating system available anywhere licensing terms bugs security flaws often caused programmer error common source error misuse codice_1 codice_2 string functions c programming language two common alternatives codice_3 codice_4 difficult understand easy misuse openbsd developers todd c. miller theo de raadt designed codice_5 codice_6 functions functions intended make harder programmers accidentally leave buffers unterminated allow overflowed adopted netbsd freebsd projects gnu c library openbsd linker changed issue warning unsafe string manipulation functions codice_1 codice_2 codice_9 found occurrences functions openbsd source tree replaced addition static bounds checker included openbsd attempt find common programming mistakes compile time security-related apis developed openbsd project include codice_10 codice_11 june 2017 email theo de raadt stated problem stable systems could running months time although considerable randomization within kernel key addresses remains project progress modifies linker every boot kernel relinked well randomizations differs kernel aslr email states result every new kernel unique relative offsets functions data unique ... current change scaffolding ensure boot newly-linked kernel upon every reboot ... new random kernel linked together ... fast machine takes less second ... reboot runs new kernel yet another kernel built next boot internal deltas functions inside kernel attacker expects 'll need better info leaks openbsd integrates several technologies help protect operating system attacks buffer overflows integer overflows developed hiroaki etoh propolice gcc extension designed protect applications stack-smashing attacks number operations local stack variables reordered place buffers pointers protecting corruption case buffer overflow pointers function arguments also placed local buffers canary value placed local buffers function exits sometimes used detect buffer overflows propolice chooses whether protect buffer based automatic heuristics judge vulnerable reducing performance overhead protection integrated openbsd version gcc december 2002 first made available openbsd 3.3 applied kernel release 3.4 extension works cpu architectures supported openbsd enabled default c code compiled protected without user intervention may 2004 openbsd sparc platform received stack protection form stackghost makes use features sparc architecture help prevent exploitation buffer overflows support sparc64 added march 2005 openbsd 3.4 introduced w^x memory management scheme ensure memory either writable executable never provides another layer protection buffer overflows relatively easy implement platform like x86-64 hardware support nx bit openbsd one oses support generic i386 platform lacks built per-page execute controls development cycle 3.8 release changes made codice_12 memory management functions traditional unix operating systems codice_12 allocates memory extending unix data segment practice made difficult implement strong protection security problems codice_12 implementation openbsd makes use codice_15 system call modified returns random memory addresses ensures different areas mapped next addition allocation small blocks shared areas randomized codice_16 function changed return memory kernel immediately rather leaving mapped process number additional optional checks also added aid development features make program bugs easier detect harder exploit instead memory corrupted invalid access ignored often result segmentation fault abortion process brought light several issues software running openbsd 3.8 particularly programs reading beyond start end buffer type bug would previously detected directly cause error abilities took three years implement without considerable performance loss one goals openbsd project integration facilities software strong cryptography core operating system end number low-level features provided including source strong pseudo random numbers built-in cryptographic hash functions transforms support cryptographic hardware openbsd cryptographic framework abilities used throughout openbsd including bcrypt password-hashing algorithm derived bruce schneier blowfish block cipher takes advantage cpu-intensive blowfish key schedule making brute-force attacks less practical protect sensitive information passwords leaking disk persist many years openbsd supports encryption swap partition swap space split many small regions assigned encryption key soon data region longer required openbsd securely deletes discarding encryption key feature enabled default openbsd 3.9 later network stack also makes heavy use randomization increase security reduce predictability various values may use attacker including tcp initial sequence numbers timestamps ephemeral source ports number features increase network resilience availability including countermeasures problems icmp software redundancy carp pfsync also included project first disable plain-text telnet daemon favor encrypted ssh daemon 1999 features integrated cryptographic software ipsec telnet daemon completely removed openbsd 2005 release openbsd version 3.8 parts x11 openbsd running user except x server split privilege-stripped x process run root x process run _x11 user x11 openbsd neither x server x clients normally escalated direct memory hardware privileges driving x intel 4 radeon 4 drivers normally interact underlying hardware via direct rendering management 4 kernel interface lowlevel memory/hardware access handled solely kernel drivers wsfb follow similar pattern reason x11 openbsd open lowlevel memory hardware access user/root programs done systems done past needed user escalate machdep.allowaperture setting default zero setting unsecure setting openbsd version x window system named xenocara security modifications server default applications patched make use privilege separation openbsd provides aperture driver limit x access memory however work x security flaws loïc duflot theo de raadt commented aperture driver merely best x violates security models hear university class went castigate x developers taking time solving 10-year-old problem november 29 2006 vesa kernel driver developed permitted x run albeit slowly without use aperture driver february 15 2014 x modified allow run without root privileges discovery security vulnerability x openbsd n't support running x root user supports running x via display manager dedicated codice_17 user privilege separation privilege revocation chrooting randomized loading libraries also play role increasing security system many applied openbsd versions common programs tcpdump apache bsd authentication system openbsd history providing users full disclosure relation various bugs security breaches detected openbsd team exemplified project slogan two remote holes default install heck long time openbsd 5.3 support full disk encryption introduced openbsd 5.8 introduced codice_18 system call restricting process capabilities minimal subset required correct operation process compromised attempts perform unintended behavior terminated kernel since introduction applications ports changed support codice_18 including chromium web browser
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Operating systems
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web mining web mining application data mining techniques discover patterns world wide web name proposes information gathered mining web makes utilization automated apparatuses reveal extricate data servers web2 reports permits organizations get organized unstructured information browser activities server logs website link structure page content different sources goal web structure mining generate structural summary web site web page technically web content mining mainly focuses structure inner-document web structure mining tries discover link structure hyperlinks inter-document level based topology hyperlinks web structure mining categorize web pages generate information similarity relationship different web sites web structure mining also another direction -- discovering structure web document type structure mining used reveal structure schema web pages would good navigation purpose make possible compare/integrate web page schemes type structure mining facilitate introducing database techniques accessing information web pages providing reference schema web mining divided three different types – web usage mining web content mining web structure mining web usage mining application data mining techniques discover interesting usage patterns web data order understand better serve needs web-based applications usage data captures identity origin web users along browsing behavior web site web usage mining classified depending kind usage data considered studies related work concerned two areas constraint-based data mining algorithms applied web usage mining developed software tools systems costa seco demonstrated web log mining used extract semantic information hyponymy relationships particular user given community web usage mining essentially many advantages makes technology attractive corporations including government agencies technology enabled e-commerce personalized marketing eventually results higher trade volumes government agencies using technology classify threats fight terrorism predicting capability mining applications benefit society identifying criminal activities companies establish better customer relationship understanding needs customer better reacting customer needs faster companies find attract retain customers save production costs utilizing acquired insight customer requirements increase profitability target pricing based profiles created even find customers might default competitor company try retain customer providing promotional offers specific customer thus reducing risk losing customer customers benefits web usage mining particularly area personalization outlined specific frameworks probabilistic latent semantic analysis model offer additional features user behavior access pattern process provides user relevant content collaborative recommendation models also demonstrate capability web usage mining technology address problems associated traditional techniques biases questions regarding validity since data patterns obtained subjective degrade time also elements unique web usage mining show technology benefits include way semantic knowledge applied interpreting analyzing reasoning usage patterns mining phase web usage mining create issues technology used data personal nature might cause concerns criticized ethical issue involving web usage mining invasion privacy privacy considered lost information concerning individual obtained used disseminated especially occurs without knowledge consent obtained data analyzed clustered form profiles data made anonymous clustering personal profiles thus applications de-individualize users judging mouse clicks de-individualization defined tendency judging treating people basis group characteristics instead individual characteristics merits another important concern companies collecting data specific purpose might use data totally different purposes essentially violates user ’ interests growing trend selling personal data commodity encourages website owners trade personal data obtained site trend increased amount data captured traded increasing likeliness one ’ privacy invaded companies buy data obliged make anonymous companies considered authors specific release mining patterns legally responsible contents release inaccuracies release result serious lawsuits law preventing trading data mining algorithms might use controversial attributes like sex race religion sexual orientation categorize individuals practices might anti-discrimination legislation applications make hard identify use controversial attributes strong rule usage algorithms attributes process could result denial service privilege individual based race religion sexual orientation right situation avoided high ethical standards maintained data mining company collected data made anonymous obtained data obtained patterns traced back individual might look poses threat one ’ privacy however additional information inferred application combining two separate unscrupulous data user web structure mining uses graph theory analyze node connection structure web site according type web structural data web structure mining divided two kinds web structure mining terminology techniques web structure mining web content mining mining extraction integration useful data information knowledge web page content heterogeneity lack structure permits much ever-expanding information sources world wide web hypertext documents makes automated discovery organization search indexing tools internet world wide web lycos alta vista webcrawler aliweb metacrawler others provide comfort users generally provide structural information categorize filter interpret documents factors prompted researchers develop intelligent tools information retrieval intelligent web agents well extend database data mining techniques provide higher level organization semi-structured data available web agent-based approach web mining involves development sophisticated ai systems act autonomously semi-autonomously behalf particular user discover organize web-based information web content mining differentiated two different points view information retrieval view database view summarized research works done unstructured data semi-structured data information retrieval view shows researches use bag words based statistics single words isolation represent unstructured text take single word found training corpus features semi-structured data works utilize html structures inside documents utilized hyperlink structure documents document representation database view order better information management querying web mining always tries infer structure web site transform web site become database several ways represent documents vector space model typically used documents constitute whole vector space representation realize importance words document resolve tf-idf term frequency times inverse document frequency introduced multi-scanning document implement feature selection condition category result rarely affected extraction feature subset needed general algorithm construct evaluating function evaluate features feature set information gain cross entropy mutual information odds ratio usually used classifier pattern analysis methods text data mining similar traditional data mining techniques usual evaluative merits classification accuracy precision recall information score web mining important component content pipeline web portals used data confirmation validity verification data integrity building taxonomies content management content generation opinion mining language code chinese words complicated compared english gb big5 hz code common chinese word codes web documents text mining one needs identify code standard html documents transform inner code use data mining techniques find useful knowledge useful patterns
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Web technology
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kylin operating system kylin operating system developed academics national university defense technology people republic china since 2001 named mythical beast qilin first versions based freebsd intended use chinese military government organizations version 3.0 kylin became linux-based version called neokylin announced 2010 separate project using ubuntu linux operating system announced 2013 first version ubuntu kylin released april 2013 development kylin began 2001 national university defense technology assigned mission developing operating system 863 program intended make china independent foreign technology aim support several kinds server platforms achieve high performance high availability high security well conforming international standards unix linux operating systems created using hierarchy model including basic kernel layer similar mach system service layer similar bsd desktop environment similar windows designed comply unix standards compatible linux applications february 2006 china military online website sponsored pla daily chinese people liberation army reported successful development kylin server operating system said first 64-bit operating system high security level b2 class also first operating system without linux kernel obtained linux global standard authentification international free standards group april 2006 said kylin operating system largely copied freebsd 5.3 anonymous chinese student australia used pseudonym dancefire carried kernel similarity analysis showed similarities two operating systems reached 99.45 percent one kylin developers confirmed kylin based freebsd speech international conference eurobsdcon 2006 2009 report presented us-china economic security review commission stated purpose kylin make chinese computers impenetrable competing countries cyberwarfare arena washington post reported china developed secure operating software tens millions computers already installing government military systems hoping make beijing ’ networks impenetrable u.s. military intelligence agencies deployment kylin said hardened key chinese servers advent version 3.0 kylin used linux kernel december 2010 announced china standard software national university defense technology signed strategic partnership launch version called neokylin china standard software maker neoshine linux desktop series neokylin intended use government offices national defense energy sectors chinese economy 2014 bloomberg news reported northeastern city siping migrated computers microsoft windows neokylin part government effort shift computer technology chinese suppliers september 2015 us computer maker dell reported 42 personal computers sold china running neokylin operating system tianhe-1 supercomputer 64-bit kylin linux oriented high-performance parallel computing optimization supports power management high-performance virtual computing newer tianhe-2 also uses kylin linux 2013 canonical reached agreement ministry industry information technology people republic china release ubuntu-based linux os features targeted chinese market ubuntu kylin described loose continuation china kylin os intended desktop laptop computers first official release ubuntu kylin 13.04 25 april 2013
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Operating systems
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windows server 2003 windows server 2003 server operating system produced microsoft released april 24 2003 successor windows 2000 server predecessor windows server 2008 updated version windows server 2003 r2 released manufacturing december 6 2005 windows server 2003 kernel later adopted development windows vista windows server 2003 follow-up windows 2000 server incorporating compatibility features windows xp unlike windows 2000 server windows server 2003 default installation none server components enabled reduce attack surface new machines windows server 2003 includes compatibility modes allow older applications run greater stability made compatible windows nt 4.0 domain-based networking windows server 2003 brought enhanced active directory compatibility better deployment support ease transition windows nt 4.0 windows server 2003 windows xp professional product went several name changes course development first announced 2000 known codename whistler server named windows 2002 server brief time mid-2001 followed windows .net server windows .net server 2003 microsoft chose focus .net branding .net framework os finally released windows server 2003 windows server 2003 first microsoft windows version thoroughly subjected semi-automated testing bugs software system called prefast developed computer scientist amitabh srivastava microsoft research automated bug checking system first tested windows 2000 thoroughly amitabh srivastava prefast found 12 windows server 2003 bugs remaining 88 found human computer programmers microsoft employs 4,700 programmers work windows 60 software testers whose job find bugs windows source code microsoft co-founder bill gates stated windows server 2003 microsoft rigorously tested software date microsoft later used windows server 2003 kernel development windows vista following features new windows server 2003 ability create rescue disk removed favor automated system recovery asr windows server 2003 comes number editions targeted towards particular size type business general variants windows server 2003 ability share files printers act application server host message queues provide email services authenticate users act x.509 certificate server provide ldap directory services serve streaming media perform server-oriented functions windows server 2003 web meant building hosting web applications web pages xml web services designed used primarily iis web server provides platform developing deploying xml web services applications use asp.net technology domain controller terminal services functionality included web edition however remote desktop administration available 10 concurrent file-sharing connections allowed moment possible install microsoft sql server microsoft exchange software edition without installing service pack 1 despite supporting xml web services asp.net uddi deployed windows server 2003 web .net framework version 2.0 included windows server 2003 web installed separate update windows update windows server 2003 web supports maximum 2 physical processors maximum 2 gb ram edition windows server 2003 require client access license cal used internet facing server front-end internet information services windows server update services using storage back-end another remote server front-end cals may still required microsoft windows server 2003 standard aimed towards small medium-sized businesses standard edition supports file printer sharing offers secure internet connectivity allows centralized desktop application deployment specialized version x64 architecture released april 2005 ia-32 version supports four physical processors 4 gb ram x64 version capable addressing 32 gb ram also supports non-uniform memory access windows server 2003 enterprise aimed towards medium large businesses full-function server operating system supports 8 physical processors provides enterprise-class features eight-node clustering using microsoft cluster server mscs software support 64 gb ram pae enterprise edition also comes specialized versions x64 itanium architectures service pack 2 installed x64 itanium versions capable addressing 1 tb 2 tb ram respectively edition also supports non-uniform memory access numa also provides ability hot-add supported hardware windows server 2003 enterprise also required edition issue custom certificate templates windows server 2003 datacenter designed infrastructures demanding high security reliability windows server 2003 available ia-32 itanium x64 processors supports maximum 32 physical processors ia-32 platform 64 physical processors x64 ia-64 hardware ia-32 versions edition support 64 gb ram service pack 2 installed x64 versions support 1 tb ia-64 versions support 2 tb ram windows server 2003 datacenter also allows limiting processor memory usage per-application basis edition better support storage area networks sans features service uses windows sockets emulate tcp/ip communication native san service providers thereby allowing san accessed tcp/ip channel application communicate tcp/ip use san without modification application datacenter edition like enterprise edition supports 8-node clustering clustering increases availability fault tolerance server installations distributing replicating service among many servers edition supports clustering cluster dedicated storage cluster nodes connected common san windows compute cluster server 2003 ccs released june 2006 designed high-end applications require high performance computing clusters designed deployed numerous computers clustered together achieve supercomputing speeds compute cluster server network comprises least one controlling head node subordinate processing nodes carry work compute cluster server uses microsoft messaging passing interface v2 ms-mpi communicate processing nodes cluster network ties nodes together powerful inter-process communication mechanism complex communications hundreds even thousands processors working parallel application programming interface consists 160 functions job launcher enables users execute jobs executed computing cluster ms mpi designed compatible reference open source mpi2 specification widely used high-performance computing hpc exceptions security considerations ms mpi covers complete set mpi2 functionality implemented mpich2 except planned future features dynamic process spawn publishing windows storage server 2003 part windows server 2003 series specialized server operating system network-attached storage nas launched 2003 storage decisions chicago optimized use file print sharing also storage area network san scenarios available original equipment manufacturers oems unlike windows server 2003 editions provide file printer sharing functionality windows storage server 2003 require cal windows storage server 2003 nas equipment headless means without monitors keyboards mice administered remotely devices plugged existing ip network storage capacity available users windows storage server 2003 use raid arrays provide data redundancy fault-tolerance high performance multiple nas servers clustered appear single device allows responsibility serving clients shared way one server fails servers take often termed failover also improves fault-tolerance windows storage server 2003 also used create storage area network data transferred terms chunks rather files thus providing granularity data transferred provides higher performance database transaction processing applications windows storage server 2003 also allows nas devices connected san windows storage server 2003 r2 follow-up windows storage server 2003 adds file-server performance optimization single instance storage sis index-based search single instance storage sis scans storage volumes duplicate files moves duplicate files common sis store file volume replaced link file substitution reduces amount storage space required much 70 windows storage server 2003 r2 provides index-based full-text search based indexing engine already built windows server updated search engine speeds indexed searches network shares edition also provides filters searching many standard file formats .zip autocad xml mp3 .pdf microsoft office file formats windows storage server 2003 r2 includes built support windows sharepoint services microsoft sharepoint portal server adds storage management snap-in microsoft management console used manage storage volumes centrally including dfs shares servers running windows storage server r2 windows storage server 2003 r2 used iscsi target standard enterprise editions windows storage server 2003 r2 incorporating wintarget iscsi technology microsoft acquired 2006 stringbean software add-on feature available purchase oem partners iscsi feature pack included versions wss configured oems windows storage server 2003 promoted function domain controller however edition licensed run directory services joined existing domain member server windows storage server 2003 r2 available following editions windows unified data storage server version windows storage server 2003 r2 iscsi target support standard available standard enterprise editions windows small business server sbs software suite includes windows server additional technologies aimed providing small business complete technology solution standard edition sbs includes microsoft remote web workplace windows sharepoint services microsoft exchange server fax server active directory basic firewall dhcp server network address translation capabilities premium edition sbs adds microsoft sql server 2000 microsoft isa server 2004 sbs type cal different costs slightly cals editions windows server 2003 however sbs cal encompasses user cals windows server exchange server sql server isa server hence less expensive buying cals individually sbs following design limitations mainly affecting active directory remove limitations instance sbs upgrade regular windows server exchange server sql isa server windows small business server 2003 r2 transition pack windows home server operating system microsoft based windows small business server 2003 sp2 seen directory listings installation dvd windows home server announced january 7 2007 consumer electronics show bill gates intended solution homes multiple connected pcs offer file sharing automated backups remote access windows home server began shipment oems september 15 2007 windows server 2003 embedded systems replaced windows 2000 server embedded systems intended use building firewall vpn caching servers similar appliances versions available server appliance software microsoft internet security acceleration server availability original version ended may 28 2003 availability r2 ended march 5 2006 end support scheduled july 14 2015 r2 original end licence scheduled may 28 2018 r2 original end support date indicates supported service pack dated july 14 2005 end licence date last date oem may distribute systems using version versions continue receive critical security updates end support microsoft announced extended support dates windows server 2003 embedded systems release 2 embedded systems available 32 64 bit versions standard 1-4 cpu enterprise 1-8 cpu march 30 2005 microsoft released service pack 1 windows server 2003 among improvements many updates provided windows xp users service pack 2 features added service pack 1 include full list updates available microsoft knowledge base service pack 2 windows server 2003 released march 13 2007 release date originally scheduled first half 2006 june 13 2006 microsoft made initial test version service pack 2 available microsoft connect users build number 2721 followed build 2805 known beta 2 refresh final build 3790 microsoft described service pack 2 standard service pack release containing previously released security updates hotfixes reliability performance improvements addition service pack 2 contains microsoft management console 3.0 windows deployment services replaces remote installation services support wpa2 improvements ipsec msconfig service pack 2 also adds windows server 2003 scalable networking pack snp allows hardware acceleration processing network packets thereby enabling faster throughput snp previously available out-of-band update windows server 2003 service pack 1 windows server 2003 r2 title complementary offering microsoft consists copy windows server 2003 sp1 one cd host optionally installed new features reminiscent microsoft plus another released manufacturing december 6 2005 ia-32 x64 platforms ia-64 succeeded windows server 2008 new features windows server 2003 r2 include july 13 2010 windows server 2003 mainstream support expired extended support phase began extended support phase microsoft continued provide security updates however free technical support warranty claims design changes longer offered extended support lasted july 14 2015 although windows server 2003 unsupported microsoft released emergency security patch may 2017 os well unsupported versions windows including windows xp windows 8 rtm address vulnerability leveraged wannacry ransomware attack
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Computer architecture
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process isolation process isolation set different hardware software technologies designed protect process processes operating system preventing process writing process b process isolation implemented virtual address space process address space different process b address space – preventing writing onto b security easier enforce disallowing inter-process memory access contrast less secure architectures dos process write memory process system process isolation limited controlled interaction processes may still allowed inter-process communication ipc channels shared memory local sockets internet sockets scheme process memory isolated processes except process allowing input collaborating processes system policies may disallow ipc circumstances example mandatory access control systems subjects different sensitivity levels may allowed communicate notable operating systems support process isolation internet explorer 4 used process isolation order allow separate windowed instances browser processes however height browser wars dropped subsequent versions compete netscape navigator sought concentrate upon one process entire internet suite idea process-per-instance would revisited decade afterwards tabbed browsing became commonplace google chrome multi-process architecture internet explorer 8 loosely coupled ie lcie tabs containing webpages contained within semi-separate os-level processes isolated core process browser prevent crash one tab/page crashing entire browser method known popularly multiprocess process-per-tab meant manage memory processing allowing offending tabs crash separately browser tabs manage security
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Operating systems
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demos demos dialogovaya edinaya mobilnaya operatsionnaya sistema unix-like operating system developed soviet union derived bsd development initiated kurchatov institute atomic energy moscow 1982 development continued cooperation institutes commercialized demos co-operative employed key contributors demos earlier alternative mnos clone unix version 6 mnos demos version 1.x gradually merged 1986 1990 leaving joint os demos version 2.x support different cyrillic charsets koi-8 u-code used demos 1 mnos respectively initially developed sm-4 pdp-11/40 clone sm-1600 later ported elektronika-1082 besm es evm clones vax-11 sm-1700 number platforms including pc/xt elektronika-85 clone dec professional number motorola 68020-based microcomputers development demos effectively ceased 1991 second project demos team relcom took priority originally suggested name унас unas volapukish word play unix у них u nih russian means also у нас u nas means also serious management dismissed idea favor traditional alphabet soup
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Operating systems
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masters universe movie masters universe movie action-adventure game developed gremlin graphics published 1987 based american film masters universe 1987 directed gary goddard film game part masters universe media franchise promotional photo dolph lundgren he-man frank langella skeletor illustrates video game packaging msx version game titled masters universe two masters universe video games published year
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Computer architecture
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slot computer architecture slot comprises operation issue data paths machinery surrounding collection one functional units fus share resources term slot common purpose vliw world relationship operation instruction pipeline execute explicit dynamically scheduled machines concept commonly called execute pipeline modern conventional cpus several compute pipelines say two alu one fpu one sse/mmx one branch issue one instruction per basic cycle several flight correspond slots pipelines may several fus adder multiplier say one fu pipeline issued particular cycle fu population pipeline/slot design option cpu
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Computer architecture
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asci blue mountain asci blue mountain supercomputer installed los alamos national laboratory los alamos new mexico designed run simulations united states national nuclear security administration advanced simulation computing program computer collaboration silicon graphics corporation los alamos national laboratory installed 1998 cluster ccnuma sgi origin 2000 systems contains 6,144 mips r10000 microprocessors theoretical top performance 3.072 teraflops built stage accelerated strategic computing initiative asci started u.s. department energy national nuclear security administration build simulator replace live nuclear weapons testing following moratorium testing started president george h. w. bush 1992 extended bill clinton 1993 unveiled commissioned 1998 june 1999 world second fastest computer remained among world ten fastest computers november 2001 according los alamos national laboratory website supercomputer set world record may 2000 equivalent 17.8 years normal computer processing within 72 hours including 15,000 engineering simulations requiring 10 hours first commissioned november 1998 blue mountain decommissioned monday november 8 2004 8 replaced asci q lightning qsc supercomputers
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Computer architecture
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wirelurker wirelurker family malware targeting macos ios systems malware designed target users china use apple mobile desktop devices malware suspected infecting thousands chinese mobile devices security firm palo alto networks credited uncovering malware wirelurker monitors ios device connected via usb infected macos computer installs downloaded third-party applications automatically generated malicious applications onto device wirelurker infect device regardless whether jailbroken wirelurker complex form malware utilizes techniques file hiding code obfuscation encryption wirelurker capable stealing variety information mobile devices infects regularly requests updates attackers command control server three individuals china arrested suspicion creating distributing wirelurker malware suspects identified surnames wang lee chen taken custody thursday november 13 2014 chinese authorities believe suspects created malware financial gains several steps taken order protect wirelurker malware
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Computer security
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united states computer emergency readiness team united states computer emergency readiness team us-cert organization within department homeland security ’ dhs national protection programs directorate nppd specifically us-cert branch office cybersecurity communications cs c national cybersecurity communications integration center nccic us-cert responsible analyzing reducing cyber threats vulnerabilities disseminating cyber threat warning information coordinating incident response activities division brings advanced network digital media analysis expertise bear malicious activity targeting networks within united states abroad dhs cyber security division created us-cert september 2003 protect internet infrastructure united states coordinating defense responding cyber-attacks 24-hour operational arm nccic accepts triages collaboratively responds incidents provides technical assistance information system operators disseminates timely notifications regarding current potential security threats exploits vulnerabilities public via national cyber awareness system ncas us-cert operates side-by-side industrial control systems computer emergency response team ics-cert deals security related industrial control systems entities operate together within nccic provide single source support critical infrastructure stakeholders five operational aspects enable us-cert meet objectives improving nation ’ cybersecurity posture coordinate cyber information sharing proactively manage cyber risks protecting constitutional rights americans feature involved reviewing researching vetting documenting computer network defense cnd attributes available us-cert classified unclassified helps promote improved mitigation resources federal departments agencies across einstein network requesting deployment countermeasures response credible cyber threats feature conducts technical analysis data provided partners constituents monitoring systems understand nature attacks threats vulnerabilities well develop tips indicators warnings actionable information us-cert ’ cnd mission feature conducts digital forensic examinations malware artifact analysis reverse engineering determine attack vectors mitigation techniques identifies possible threats based analysis malicious code digital media provides indicators mitigate prevent future intrusions feature informs cnd community potential threats allows hardening cyber defenses well develops near real-time/rapid response community products e.g. reports white papers critical event occurs detected operations create tailored product describing event recommended course action mitigation techniques applicable ensure constituents made aware protect organization appropriately feature supports nccic information sharing development web presence responsible establishing maintaining assured communications developing disseminating information products supporting development maintenance collaboration tools feature partners foreign governments entities enhance global cybersecurity defense posture supports bilateral engagements cert-to-cert information sharing/trust building activities improvements related global collaboration agreements data sharing standards january 2015 report senator tom coburn ranking member committee homeland security governmental affairs expressed concern us-cert always provide information nearly quickly alternative private sector threat analysis companies
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Computer security
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1942 video game 1942 vertically scrolling shooter made capcom released arcade 1984 first game 19xx series followed 1942 set pacific theater world war ii despite game created japanese developers goal reach tokyo destroy entire japanese air fleet player pilots lockheed p-38 lightning dubbed super ace player shoot enemy planes avoid enemy fire player perform roll vertical loop game player may collect series power-ups one allowing plane escorted two smaller fighters tip tow formation enemies kawasaki ki-61s mitsubishi a6m zeros kawasaki ki-48s boss plane nakajima g8n game ported famicom 1985 japan north america 1986 developed micronics msx nec pc-8801 game boy color ported european games publisher elite systems amstrad cpc zx spectrum commodore 64 music commodore 64 version based main verse ron goodwin 633 squadron movie score arrangement mark cooksey 1942 capcom breakaway hit eclipsing popularity company preceding three titles vulgus sonson pirate ship higemaru 1987 number-one euromax uk arcade chart followed wonder boy number-two 1942 first capcom title spawn successful series sequels five titles 19xx line released 1987 2000 many capcom vertical shooters featured similar gameplay re-released playstation saturn consoles featured capcom classics collection playstation 2 xbox well playstation portable arcade version added wii virtual console japan december 21 2010 pal north american regions january 2011 also re-released windows mobile professional. released xbox live arcade playstation network 2008 1942 first strike released ios 2010 game series sold total 1.4 million units worldwide december 31 2018 stands capcom 18th best-selling franchise
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Computer architecture
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european cybercrime centre european cybercrime centre ec3 ec³ body police office europol european union eu headquartered hague coordinates cross-border law enforcement activities computer crime acts centre technical expertise matter officially launched 11 january 2013 european cybercrime centre expected fully operational 2015 began staff 30 plans expand 40 end 2013 began operations budget 3.6 million euros head ec3 reports directly head europol first person head department former head danish domestic intelligence left interpol january 2015 become barclays chief intelligence security officer.. ec3 tasked assisting member states efforts dismantle disrupt cybercrime networks developing tools providing training ec3 works european union intelligence situation centre intcen united nations office drugs crime undcp world customs organization wco european border coast guard agency ebcg also known frontex european anti-fraud office olaf press releases 2015 also revealed ec3 works american security services federal bureau investigation fbi overlap responsibilities european union agency network information security enisa press conference 10 february 2014 asked massive identity theft uncovered german federal office information security head ec3 troels oerting said unit responsible combatting politically motivated hacking and/or espionage eu institutions february 2014 troels oerting reported successes unit 2013 included catching internet extortioners 13 arrests also involved fighting malware attacks banks using botnets – cooperation microsoft experts german federal criminal police office – taking zeroaccess botnet 2014 details revealed operation onymous took number darknet sites including pandora cloud 9 hydra blue sky topix flugsvamp cannabis road black market silk road 2.0 2015 american media reported coordinated fbi operation assistance ec3 take dark0de largest english -language communication trading platform cybercriminals well eu member states cooperation number states including australia canada republic macedonia norway switzerland monaco bosnia herzegovina colombia moldova russia turkey republic serbia montenegro ukraine united states
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Computer security
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traversal using relays around nat traversal using relays around nat turn protocol assists traversal network address translators nat firewalls multimedia applications may used transmission control protocol tcp user datagram protocol udp useful clients networks masqueraded symmetric nat devices turn aid running servers well known ports private network nat supports connection user behind nat single peer telephony example turn specified rfc 5766 update turn ipv6 specified rfc 6156 turn uri scheme documented rfc 7065 nats providing many benefits also come many drawbacks troublesome drawbacks fact break many existing ip applications make difficult deploy new ones guidelines developed describe build nat friendly protocols many protocols simply constructed according guidelines examples protocols include multimedia applications file sharing session traversal utilities nat stun provides one way application traverse nat stun allows client obtain transport address ip address port may useful receiving packets peer however addresses obtained stun may usable peers addresses work depending topological conditions network therefore stun provide complete solution nat traversal complete solution requires means client obtain transport address receive media peer send packets public internet accomplished relaying data server resides public internet traversal using relay nat turn protocol allows client obtain ip addresses ports relay although turn almost always provides connectivity client resource intensive provider turn server therefore desirable use turn last resort preferring mechanisms stun direct connectivity possible accomplish interactive connectivity establishment ice methodology used discover optimal means connectivity process begins client computer wants contact peer computer data transaction due client peer behind respective nats stun option one nats symmetric nat type nat known non-stun compatible turn must used first client contacts turn server allocate request allocate request asks turn server allocate resources client may contact peer allocation possible server allocates address client use relay sends client allocation successful response contains allocated relayed transport address located turn server second client sends createpermissions request turn server create permissions check system peer-server communications words peer finally contacted sends information back turn server relayed client turn server uses permissions verify peer-to-turn server communication valid permissions created client two choices sending actual data 1 use send mechanism 2 reserve channel using channelbind request send mechanism straightforward contains larger header 36 bytes substantially increase bandwidth turn relayed conversation contrast channelbind method lighter header 4 bytes requires channel reserved needs periodically refreshed among considerations using either method send channel binding turn server receives data client relays peer using udp datagrams contain source address allocated relayed transport address peer receives data responds using udp datagram transport protocol sending udp datagram relay address turn server turn server receives peer udp datagram checks permissions valid forwards client process gets around even symmetric nats client peer least talk turn server allocated relay ip address communication turn robust stun assist traversal types nats turn communication relays entire communication server requiring far server bandwidth stun protocol typically resolves public facing ip address relays information client peer use direct communication reason ice protocol mandates stun usage first resort turn usage dealing symmetric nats situations stun used
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Internet protocols
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ettercap software ettercap free open source network security tool man-in-the-middle attacks lan used computer network protocol analysis security auditing runs various unix-like operating systems including linux mac os x bsd solaris microsoft windows capable intercepting traffic network segment capturing passwords conducting active eavesdropping number common protocols original developers later founded hacking team ettercap works putting network interface promiscuous mode arp poisoning target machines thereby act 'man middle unleash various attacks victims ettercap plugin support features extended adding new plugins ettercap supports active passive dissection many protocols including ciphered ones provides many features network host analysis ettercap offers four modes operation addition software also offers following features ettercap also ability actively passively find poisoners lan
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Computer security
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turbine us government project turbine codename automated system essence enables automated management control large network implants form remotely transmitted malware selected individual computer devices bulk tens thousands devices nsa built infrastructure enables covertly hack computers mass scale using automated systems reduce level human oversight process quoted intercept turbine designed allow current implant network scale large size millions implants creating system automated control implants groups instead individually nsa shared many files use implants counterparts so-called five eyes surveillance alliance – united kingdom canada new zealand australia among things due turbine control implants nsa capable turbine implants linked relies upon large network clandestine surveillance sensors nsa installed locations across world including agency headquarters maryland fort george g. meade eavesdropping bases used agency misawa japan misawa air base menwith hill england raf menwith hill codenamed turmoil sensors operate sort high-tech surveillance dragnet monitoring packets data sent across internet turbine implants exfiltrate data infected computer systems turmoil sensors automatically identify data return nsa analysis targets communicating turmoil system used send alerts tips turbine enabling initiation malware attack identify surveillance targets nsa uses series data selectors flow across internet cables selectors include email addresses ip addresses unique cookies containing username identifying information sent user computer websites google facebook hotmail yahoo twitter unique google advertising cookies track browsing habits unique encryption key fingerprints traced specific user computer ids sent across internet windows computer crashes updates
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Computer security
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arxan technologies arxan technologies american technology company specializing application attack prevention self-protection solution iot mobile applications company reports applications secured running 500 million devices arxan solutions used protect applications across range industries including mobile payments banking automotive iot healthcare iot gaming high-tech arxan security products used protect confidentiality applications breached reverse-engineering code analysis means integrity applications compromised code modification malware insertion types attacks arxan privately held private equity-backed fall 2013 ta associates private equity firm completed majority investment arxan technologies previously company received series b funding 2003 followed 13 million series c funding 2007 series funding 4 million 2009 early investors included trident capital edf ventures legend ventures paladin capital dunrath capital tdf fund solstice capital arxan founded 2001 eric davis purdue university researchers mikhail atallah tim korb john rice hoi chang first funding came richard early dunrath capital rich early subsequently became arxan first ceo company early intellectual property licensed purdue university company initial focus defense anti-tamper applications following sale defense technology unit arxan defense systems microsemi 2010 arxan focused commercial applications arxan offers number anti-tamper software products application cryptographic key protection include may 2012 company announced comprehensive support android application protection hardening tampering piracy june 2014 arxan announced mobile application protection offerings sold ibm part ibm portfolio security products arxan products based patented security techniques code hardening tamper-proofing key security node locking core technology consists multi-layered interconnected network guards perform specific security function embedded application binaries make programs tamper-aware tamper-resistant self-healing company claims three-layer protection paradigm defend detect react differentiating approach detecting attack attempted responding detected attacks alerts repairs protection helps secure software hacking attacks threats
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Computer security
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activevos activevos business process management suite business processes designed using graphical bpmn 2.0 notation process engine implements ws-bpel 2.0 standard well bpel4people processes require people perform tasks task list
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Distributed computing architecture
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xz utils xz utils previously lzma utils set free command-line lossless data compressors including lzma xz unix-like operating systems version 5.0 onwards microsoft windows xz utils consists two major components various command shortcuts exist lzma xz -- format=lzma unxz xz -- decompress analogous gunzip xzcat unxz -- stdout analogous zcat xz utils compress decompress xz lzma file formats since lzma format legacy xz utils compresses default xz behavior software well properties file format designed work similarly popular unix compressing tools gzip bzip2 consists unix port igor pavlov lzma-sdk adapted fit seamlessly unix environments usual structure behavior like gzip bzip xz lzma compress single files data streams input bundle multiple files single archive – archiving program used first tar compressing archive decompressing archive version 1.22 greater gnu implementation tar transparent support tarballs compressed lzma xz using switches codice_1 codice_2 xz compression codice_3 lzma compression creating archive compressing decompressing archive extracting contents development xz utils took place within tukaani project led mike kezner small group developers maintained linux distribution based slackware source code xz utils released public domain rest subject different free software licenses specifically core parts public domain software parts bulk system gnu lgpl v2.1 parts build system gnu gpl v2 gnu gpl v3 resulting software binary therefore gpl binaries available freebsd linux systems microsoft windows freedos number linux distributions including fedora slackware ubuntu debian arch linux use xz compressing software packages gnu ftp archive also uses xz
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Computer file systems
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fly-by-wire fly-by-wire fbw system replaces conventional manual flight controls aircraft electronic interface movements flight controls converted electronic signals transmitted wires hence fly-by-wire term flight control computers determine move actuators control surface provide ordered response use mechanical flight control backup systems boeing 777 use fully fly-by-wire controls improved fully fly-by-wire systems interpret pilot control inputs desired outcome calculate control surface positions required achieve outcome results various combinations rudder elevator aileron flaps engine controls different situations using closed feedback loop pilot may fully aware control outputs acting effect outcome aircraft reacting expected fly-by-wire computers act stabilise aircraft adjust flying characteristics without pilot involvement prevent pilot operating outside aircraft safe performance envelope mechanical hydro-mechanical flight control systems relatively heavy require careful routing flight control cables aircraft systems pulleys cranks tension cables hydraulic pipes systems often require redundant backup deal failures increases weight limited ability compensate changing aerodynamic conditions dangerous characteristics stalling spinning pilot-induced oscillation pio depend mainly stability structure aircraft concerned rather control system depending pilot action term fly-by-wire implies purely electrically signaled control system used general sense computer-configured controls computer system interposed operator final control actuators surfaces modifies manual inputs pilot accordance control parameters side-sticks centre sticks conventional flight control yokes used fly fbw aircraft fbw aircraft lighter similar design conventional controls partly due lower overall weight system components partly natural stability aircraft relaxed slightly transport aircraft maneuverable fighter means stability surfaces part aircraft structure therefore made smaller include vertical horizontal stabilizers fin tailplane normally rear fuselage structures reduced size airframe weight reduced advantages fbw controls first exploited military commercial airline market airbus series airliners used full-authority fbw controls beginning a320 series see a320 flight control though limited fbw functions existed a310 boeing followed 777 later designs pilot commands flight control computer make aircraft perform certain action pitch aircraft roll one side moving control column sidestick flight control computer calculates control surface movements cause plane perform action issues commands electronic controllers surface controllers surface receive commands move actuators attached control surface moved flight control computer commanded controllers measure position flight control surface sensors lvdts fly-by-wire control systems allow aircraft computers perform tasks without pilot input automatic stability systems operate way gyroscopes fitted sensors mounted aircraft sense rotation pitch roll yaw axes movement straight level flight example results signals computer automatically move control actuators stabilize aircraft traditional mechanical hydraulic control systems usually fail gradually loss flight control computers immediately renders aircraft uncontrollable reason fly-by-wire systems incorporate either redundant computers triplex quadruplex etc kind mechanical hydraulic backup combination mixed control system mechanical backup feedbacks rudder elevation directly pilot therefore makes closed loop feedback systems senseless aircraft systems may quadruplexed four independent channels prevent loss signals case failure one even two channels high performance aircraft fly-by-wire controls also called ccvs control-configured vehicles may deliberately designed low even negative stability flight regimes rapid-reacting ccv controls electronically stabilize lack natural stability pre-flight safety checks fly-by-wire system often performed using built-in test equipment bite number control movement steps automatically performed reducing workload pilot groundcrew speeding flight-checks aircraft panavia tornado example retain basic hydro-mechanical backup system limited flight control capability losing electrical power case tornado allows rudimentary control stabilators pitch roll axis movements servo-electrically operated control surfaces first tested 1930s soviet tupolev ant-20 long runs mechanical hydraulic connections replaced wires electric servos first pure electronic fly-by-wire aircraft mechanical hydraulic backup apollo lunar landing training vehicle lltv first flown 1968 first non-experimental aircraft designed flown 1958 fly-by-wire flight control system avro canada cf-105 arrow feat repeated production aircraft concorde 1969 system also included solid-state components system redundancy designed integrated computerised navigation automatic search track radar flyable ground control data uplink downlink provided artificial feel feedback pilot uk two seater avro 707b flown fairey system mechanical backup early mid-60s program curtailed air-frame ran flight time 1972 first digital fly-by-wire fixed-wing aircraft without mechanical backup take air f-8 crusader modified electronically nasa united states test aircraft f-8 used apollo 11 guidance navigation control hardware preceded 1964 llrv pioneered fly-by-wire flight mechanical backup control digital computer three analog redundant channels ussr sukhoi t-4 also flew time united kingdom trainer variant british hawker hunter fighter modified british royal aircraft establishment fly-by-wire flight controls right-seat pilot fly-by-wire flight control systems eliminate complexity fragility weight mechanical circuit hydromechanical electromechanical flight control systems—each replaced electronic circuits control mechanisms cockpit operate signal transducers turn generate appropriate electronic commands next processed electronic controller—either analog one modernly digital one aircraft spacecraft autopilots part electronic controller hydraulic circuits similar except mechanical servo valves replaced electrically controlled servo valves operated electronic controller simplest earliest configuration analog fly-by-wire flight control system configuration flight control systems must simulate feel electronic controller controls electrical feel devices provide appropriate feel forces manual controls used concorde first production fly-by-wire airliner sophisticated versions analog computers replaced electronic controller canceled 1950s canadian supersonic interceptor avro canada cf-105 arrow employed type system analog computers also allowed customization flight control characteristics including relaxed stability exploited early versions f-16 giving impressive maneuverability digital fly-by-wire flight control system extended analog counterpart digital signal processing receive interpret input multiple sensors simultaneously altimeters pitot tubes adjust controls real time computers sense position force inputs pilot controls aircraft sensors solve differential equations related aircraft equations motion determine appropriate command signals flight controls execute intentions pilot programming digital computers enable flight envelope protection protections tailored aircraft handling characteristics stay within aerodynamic structural limitations aircraft example computer flight envelope protection mode try prevent aircraft handled dangerously preventing pilots exceeding preset limits aircraft flight-control envelope prevent stalls spins limit airspeeds g forces airplane software also included stabilize flight-control inputs avoid pilot-induced oscillations since flight-control computers continuously feedback environment pilot workloads reduced also military naval applications possible fly military aircraft relaxed stability primary benefit aircraft maneuverability combat training flights so-called carefree handling stalling spinning undesirable performances prevented automatically computers digital flight control systems enable inherently unstable combat aircraft lockheed f-117 nighthawk northrop grumman b-2 spirit flying wing fly usable safe manners federal aviation administration faa united states adopted rtca/do-178c titled software considerations airborne systems equipment certification certification standard aviation software safety-critical component digital fly-by-wire system including applications laws aeronautics computer operating systems need certified do-178c level b depending class aircraft applicable preventing potential catastrophic failures nevertheless top concern computerized digital fly-by-wire systems reliability even analog electronic control systems digital computers running software often control path pilot aircraft flight control surfaces computer software crashes reason pilot may unable control aircraft hence virtually fly-by-wire flight control systems either triply quadruply redundant computers electronics three four flight-control computers operating parallel three four separate data buses connecting control surface multiple redundant flight control computers continuously monitor output one computer begins give aberrant results reason potentially including software hardware failures flawed input data combined system designed exclude results computer deciding appropriate actions flight controls depending specific system details may potential reboot aberrant flight control computer reincorporate inputs return agreement complex logic exists deal multiple failures may prompt system revert simpler back-up modes addition early digital fly-by-wire aircraft also analog electrical mechanical hydraulic back-up flight control system space shuttle addition redundant set four digital computers running primary flight-control software fifth back-up computer running separately developed reduced-function software flight-control system – one commanded take event fault ever affects computers four back-up system serves reduce risk total flight-control-system failure ever happening general-purpose flight software fault escaped notice four computers airliners flight-control redundancy improves safety fly-by-wire control systems physically lighter lower maintenance demands conventional controls also improve economy terms cost ownership in-flight economy certain designs limited relaxed stability pitch axis example boeing 777 flight control system may allow aircraft fly aerodynamically efficient angle attack conventionally stable design modern airliners also commonly feature computerized full-authority digital engine control systems fadecs control jet engines air inlets fuel storage distribution system similar fashion way fbw controls flight control surfaces allows engine output continually varied efficient usage possible second generation embraer e-jet family gained 1.5 efficiency improvement first generation fly-by-wire system enabled reduction 280 ft.² 250 ft.² horizontal stabilizer e190/195 variants airbus boeing differ approaches implementing fly-by-wire systems commercial aircraft since airbus a320 airbus flight-envelope control systems always retain ultimate flight control flying normal law permit pilots violate aircraft performance limits unless choose fly alternate law strategy continued subsequent airbus airliners however event multiple failures redundant computers a320 mechanical back-up system pitch trim rudder airbus a340 purely electrical electronic back-up rudder control system beginning a380 flight-control systems back-up systems purely electrical use three-axis backup control module bcm boeing airliners boeing 777 allow pilots completely override computerised flight-control system permitting aircraft flown outside usual flight-control envelope decide necessary advent fadec full authority digital engine control engines permits operation flight control systems autothrottles engines fully integrated modern military aircraft systems autostabilization navigation radar weapons system integrated flight control systems fadec allows maximum performance extracted aircraft without fear engine misoperation aircraft damage high pilot workloads civil field integration increases flight safety economy airbus a320 fly-by-wire brethren protected dangerous situations low-speed stall overstressing flight envelope protection result conditions flight control systems commands engines increase thrust without pilot intervention economy cruise modes flight control systems adjust throttles fuel tank selections precisely skillful pilots fadec reduces rudder drag needed compensate sideways flight unbalanced engine thrust a330/a340 family fuel transferred main wing center fuselage tanks fuel tank horizontal stabilizer optimize aircraft center gravity cruise flight fuel management controls keep aircraft center gravity accurately trimmed fuel weight rather drag-inducing aerodynamic trims elevators fly-by-optics sometimes used instead fly-by-wire offers higher data transfer rate immunity electromagnetic interference lighter weight cases cables changed electrical optical fiber cables sometimes referred fly-by-light due use fiber optics data generated software interpreted controller remain fly-by-light effect decreasing electro-magnetic disturbances sensors comparison common fly-by-wire control systems kawasaki p-1 first production aircraft world equipped flight control system eliminated mechanical transmission circuits fly-by-wire flight control systems next step eliminate bulky heavy hydraulic circuits hydraulic circuit replaced electrical power circuit power circuits power electrical self-contained electrohydraulic actuators controlled digital flight control computers benefits digital fly-by-wire retained biggest benefits weight savings possibility redundant power circuits tighter integration aircraft flight control systems avionics systems absence hydraulics greatly reduces maintenance costs system used lockheed martin f-35 lightning ii airbus a380 backup flight controls boeing 787 airbus a350 also incorporate electrically powered backup flight controls remain operational even event total loss hydraulic power wiring adds considerable amount weight aircraft therefore researchers exploring implementing fly-by-wireless solutions fly-by-wireless systems similar fly-by-wire systems however instead using wired protocol physical layer wireless protocol employed addition reducing weight implementing wireless solution potential reduce costs throughout aircraft life cycle example many key failure points associated wire connectors eliminated thus hours spent troubleshooting wires connectors reduced furthermore engineering costs could potentially decrease less time would spent designing wiring installations late changes aircraft design would easier manage etc newer flight control system called intelligent flight control system ifcs extension modern digital fly-by-wire flight control systems aim intelligently compensate aircraft damage failure flight automatically using engine thrust avionics compensate severe failures loss hydraulics loss rudder loss ailerons loss engine etc several demonstrations made flight simulator cessna-trained small-aircraft pilot successfully landed heavily damaged full-size concept jet without prior experience large-body jet aircraft development spearheaded nasa dryden flight research center reported enhancements mostly software upgrades existing fully computerized digital fly-by-wire flight control systems dassault falcon 7x embraer legacy 500 business jets flight computers partially compensate engine-out scenarios adjusting thrust levels control inputs still require pilots respond appropriately
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Computer security
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virtual organization grid computing grid computing virtual organization vo refers dynamic set individuals institutions defined around set resource-sharing rules conditions virtual organizations share commonality among including common concerns requirements may vary size scope duration sociology structure collaborations involved grid computing early 2000s lead emergence multiple organizations function one unit use shared competencies resources purpose one identified goals virtual organization characteristics formal organization one comprises complex network smaller organizations contribute part production process boundaries organizations fuzzy control generally market forces reinforced certainty long- term contracts xtreemos project promised support virtual organizations
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Distributed computing architecture
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language technologies institute language technologies institute lti research institute carnegie mellon university pittsburgh pennsylvania united states focuses area language technologies main scholarly research institute machine translation speech recognition speech synthesis information retrieval parsing information extraction 1996 institute existed center machine translation established 1986 subsequently 1996 onwards started awarding degrees name changed language technologies institute current director institute professor jaime carbonell
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Computational linguistics
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predator video game predator 1987 side-scrolling action game based film title player starts weapons must collect game progresses predator received mixed largely positive reviews across platforms including accolades cu screen star commodore user commodore 64 version c+vg hit computer video games zx spectrum version rachael smith sinclair gave latter version game score 7/10 opining great graphics tough get grips sudden death sneaks every opportunity germany predator put index bundesprüfstelle für jugendgefährdende medien bpjm made illegal sell make game available minors germany well making illegal advertise game form
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Computer architecture
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last mission video game last mission computer game released 1987 spanish company opera soft sinclair spectrum amstrad cpc msx also ported ibm pc platform 2d flip-screen side-view game following robot rebellion humans fled earth planet nova sent robot or-cabe-3 back earth obtain secret defense plans enemy robot base player takes control or-cabe-3 attempts escape enemy base plans board spacecraft nova player role robot or-cabe-3 attempts escape enemy base leave earth starting deepest level base robot stolen defense plans must evade hostile robots travel surface escape ship awaits robot or-cabe-3 resembles tank rotating gun mounted caterpillar-track base gun section capable flight may detached base kill enemies solve problems though loses energy state runs energy game ends life lost gun section destroyed base section destroyed respawned starting location lives lost
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Computer architecture
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quic quic pronounced 'quick general-purpose transport layer network protocol initially designed jim roskind google implemented deployed 2012 announced publicly 2013 experimentation broadened described ietf still internet draft quic used half connections chrome web browser google servers web browsers support protocol although name initially proposed acronym quick udp internet connections ietf use word quic acronym simply name protocol among applications quic improves performance connection-oriented web applications currently using tcp establishing number multiplexed connections two endpoints user datagram protocol udp works hand-in-hand http/2 multiplexed connections allowing multiple streams data reach endpoints independently hence independent packet losses involving streams contrast http/2 hosted transmission control protocol tcp suffer head-of-line-blocking delays multiplexed streams tcp packets delayed lost quic secondary goals include reduced connection transport latency bandwidth estimation direction avoid congestion also moves congestion control algorithms user space endpoints rather kernel space claimed allow algorithms improve rapidly additionally protocol extended forward error correction fec improve performance errors expected seen next step protocol evolution june 2015 internet draft specification quic submitted ietf standardization quic working group established 2016 october 2018 ietf http quic working groups jointly decided call http mapping quic http/3 advance making worldwide standard transmission control protocol tcp aims provide interface sending streams data two endpoints data handed tcp system ensures data makes end exactly form connection indicate error condition exists tcp breaks data network packets adds small amounts data packet additional data includes sequence number used detect packets lost transmitted order checksum allows errors within packet data detected either problem occurs tcp uses automatic repeat request arq tell sender re-send lost damaged packet implementations tcp see error connection blocking operation stopping transfers error resolved connection considered failed single connection used send multiple streams data case http/2 protocol streams blocked although one might problem instance single error occurs downloading gif image used favicon entire rest page wait problem resolved tcp system designed look like data pipe stream deliberately contains little understanding data transmits data additional requirements like encryption using tls must set systems running top tcp using tcp communicate similar software end connection sorts setup tasks requires handshake process often requires several round-trips requests responses connection established due inherent latency long-distance communications add significant overhead overall transmission quic aims nearly equivalent tcp connection much-reduced latency primarily two changes rely understanding behaviour http traffic first change greatly reduce overhead connection setup http connections demand tls quic makes exchange setup keys supported protocols part initial handshake process client opens connection response packet includes data needed future packets use encryption eliminates need set tcp connection negotiate security protocol via additional packets protocols serviced way combining together multiple steps single request-response data used following requests initial setup well future requests would otherwise negotiated separate connections quic uses udp basis include loss recovery instead quic stream separately flow controlled lost data retransmitted level quic udp means error occurs one stream like favicon example protocol stack continue servicing streams independently useful improving performance error-prone links cases considerable additional data may received tcp notices packet missing broken data blocked even flushed error corrected quic data free processed single multiplexed stream repaired quic includes number mundane changes also improve overall latency throughput instance packets encrypted individually result encrypted data waiting partial packets generally possible tcp encryption records bytestream protocol stack unaware higher-layer boundaries within stream negotiated layers running top quic aims single handshake process another goal quic system improve performance network-switch events like happens user mobile device moves local wifi hotspot mobile network occurs tcp lengthy process starts every existing connection times one-by-one re-established demand solve problem quic includes connection identifier uniquely identifies connection server regardless source allows connection re-established simply sending packet always contains id original connection id still valid even user ip address changes quic implemented application-space opposed operating system kernel generally invokes additional overhead due context switches data moved applications however case quic protocol stack intended used single application application using quic connections hosted udp ultimately difference could small much overall http/2 stack already applications libraries commonly placing remaining parts libraries essentially error correction little effect http/2 stack size overall complexity organization allows future changes made easily require changes kernel updates one quic longer-term goals add new systems forward error correction fec improved congestion control one concern move tcp udp tcp widely adopted many middle-boxes internet infrastructure tuned tcp rate-limit even block udp google carried number exploratory experiments characterize found small number connections blocked manner led use rapid fallback-to-tcp system chromium network stack opens quic traditional tcp connection time allows fallback zero latency protocol created google taken ietf name quic already 2012 around quic version 20 quite different quic continued evolve refined within ietf original google quic designed general purpose protocol though initially deployed protocol support http chromium current evolution ietf protocol quic general purpose transport protocol chromium developers continued track evolution ietf quic standardization efforts adopt fully comply recent internet standards quic chromium quic code experimentally developed google chrome starting 2012 announced part chromium version 29 released august 20 2013 chrome currently enabled default chromium chrome browser experimental quic support enabled chrome //flags also browser extension indicate pages served quic similarly introduced opera 16 turned opera //flags/ enable-quic opera //flags/ enable-quic-https active sessions seen opera //net-internals/ quic firefox yet support quic 2019-07 cronet library quic protocols available android applications module loadable via google play services 2017 three actively maintained implementations google servers support quic google published prototype server go implementation called quic-go also available powers experimental quic support caddy server july 11 2017 litespeed technologies officially began supporting quic load balancer webadc litespeed web server products july 2019 55.9 quic websites used litespeed 43.7 used nginx although first google servers supported http-over-quic connections facebook also launched technology 2018 cloudflare offering quic support beta basis since 2018 july 2019 3.2 websites use quic addition several stale community projects libquic created extracting chromium implementation quic modifying minimize dependency requirements goquic provides go bindings libquic finally quic-reverse-proxy docker image acts reverse proxy server translating quic requests plain http understood origin server following implementations quic gquic available source form
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Internet protocols
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urchin software urchin web statistics analysis program developed urchin software corporation urchin analyzed web server log file content displayed traffic information website based upon log data sales urchin products ended march 28 2012 urchin software could run two different data collection modes log file analyzer hybrid log file analyzer urchin processed web server log files variety log file formats custom file formats could also defined hybrid urchin combined page tags log file data eradicate limitations data collection method isolation result accurate web visitor data urchin became one popular solutions website traffic analysis particularly isps web hosting providers largely due scalability performance pricing model urchin software corp. acquired google april 2005 forming google analytics april 2008 google released urchin 6 february 2009 google released urchin 6.5 integrating adwords urchin 7 released september 2010 included 64-bit support new ui event tracking among features
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Web technology
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bernard greenberg bernard s. greenberg programmer computer scientist known work multics lisp machine 1978 greenberg implemented multics emacs using multics maclisp success effort influenced choice lisp basis later versions emacs greenberg involved design new error system symbolics turn influenced condition system adopted ansi common lisp working symbolics greenberg implemented lisp machine file system lmfs 1987 greenberg sonya keene authored rfc 1037 nfile file access protocol 1994 nycsubway.org released greenberg nxsys – design environment simulator control signals used new york city transit authority ’ signaling control networks current version nxsys microsoft windows application makes use opengl api provide interactive 3d view perspective new york city subway motorman according online documentation nxsys “ relay language ” subset lisp describes subway track systems control signal pathways subway simulation actually run lisp program compiled nxsys relay language source together thomas milo greenberg author basis technology arabic editor handles among others improved version dmg deutsche morgenländische gesellschaft transcription method supports reversible transcription semi-reversible transliteration arabic text
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Programming language topics
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emotion engine emotion engine central processing unit developed manufactured sony computer entertainment toshiba use playstation 2 video game console also used early playstation 3 models sold japan north america model numbers cechaxx cechbxx provide playstation 2 game support mass production emotion engine began 1999 ended late 2012 discontinuation playstation 2 emotion engine consists eight separate units performing specific task integrated onto die units cpu core two vector processing units vpu 10-channel dma unit memory controller image processing unit ipu three interfaces input output interface i/o processor graphics interface gif graphics synthesizer memory interface system memory cpu core tightly coupled first vpu vpu together responsible executing game code high-level modeling computations second vpu vpu dedicated geometry-transformations lighting operates independently parallel cpu core controlled microcode vpu utilized also used geometry-transformations display lists generated cpu/vpu0 vpu1 sent gif prioritizes dispatching graphics synthesizer rendering cpu core two-way superscalar in-order risc processor based mips r5900 implements mips-iii instruction set architecture isa much mips-iv addition custom instruction set developed sony operated 128-bit wide groups either 32-bit 16-bit 8-bit integers single instruction multiple data simd fashion i.e four 32-bit integers could added four others using single instruction instructions defined include add subtract multiply divide min/max shift logical leading-zero count 128-bit load/store 256-bit 128-bit funnel shift addition described sony competitive reasons contrary misconceptions simd capabilities amount processor 128-bit neither memory addresses integers 128-bit shared simd/integer registers comparison 128-bit wide registers simd instructions present 32-bit x86 architecture since 1999 introduction sse however internal data paths 128bit wide processors capable operating 4x32bit quantities parallel single registers processor mips-based modified instruction set main vu0 core superscalar in-order 2-issue design 6 stage long integer pipelines 15 stage long floating point pipeline assortment registers consists 32 128 bit vliw simd registers naming/renaming one 64 bit accumulator two 64 bit general data registers 8 16 bit fix function registers 16 8 bit controller registers processor also two 64 bit integer alus 128bit load-store unit lsu branch execution unit bxu 32 bit vu1 fpu coprocessor acted sync controller vpu0/vpu1 containing mips base processor core 32 64-bit fp registers 15 32-bit integer registers alus 64-bit 32-bit fpu n't ieee 754 compliant custom instruction set 107 mmi multimedia extensions implemented grouping two 64-bit integer alus integer floating-point pipelines six stages long feed execution units instructions data 16 kb two-way set associative instruction cache 8 kb two-way set associative non blocking data cache 16 kb scratchpad ram instruction data caches virtually indexed physically tagged scratchpad ram exists separate memory space combined 48 double entry instruction data translation lookaside buffer provided translating virtual addresses branch prediction achieved 64-entry branch target address cache branch history table integrated instruction cache branch mispredict penalty three cycles due short six stage pipeline majority emotion engine floating point performance provided two vector processing units vpu designated vpu0 vpu1 essentially dsps tailored 3d math forerunner hardware vertex shader pipelines vpu features 32 128-bit vector simd registers holding 4d vector data 16 16-bit fixed-point registers four fmac floating point multiply-accumulate units fdiv floating point divide unit local data memory data memory vpu0 4 kb size vpu1 features 16 kb data memory achieve high bandwidth vpu data memory connected directly gif data memories read directly dma unit single vector instruction consists four 32-bit single-precision floating-point values distributed four single-precision 32-bit fmac units processing scheme similar ssex extensions intel fmac units take four cycles execute one instruction units six-stage pipeline throughput one instruction per cycle fdiv unit nine-stage pipeline execute one instruction every seven cycles ipu allowed mpeg-2 compressed image decoding allowing playback dvds game fmv also allowed vector quantization 2d graphics data memory management unit rdram controller dma controller handle memory access within system communications mips core two vpus gif memory controller units handled 128-bit wide internal data bus running half clock frequency emotion engine offer greater bandwidth also 128-bit dedicated path cpu vpu0 128-bit dedicated path vpu1 gif 150 mhz internal data bus provides maximum theoretical bandwidth 2.4 gb/s communication emotion engine ram occurs two channels drdram direct rambus dynamic random access memory memory controller interfaces internal data bus channel 16 bits wide operates 400 mhz ddr double data rate combined two channels drdram maximum theoretical bandwidth 25.6 gbit/s 3.2 gb/s 33 bandwidth internal data bus memory controller buffers data sent drdram channels extra bandwidth utilised cpu emotion engine interfaces directly graphics synthesizer via gif dedicated 64-bit 150 mhz bus maximum theoretical bandwidth 1.2 gb/s provide communications emotion engine input output processor iop input output interface interfaces 32-bit wide 37.5 mhz input output bus maximum theoretical bandwidth 150 mb/s internal data bus interface provides enough bandwidth pcmcia extension connector used network adapter built-in p-ata interface faster data access online functionality advantage high bandwidth could easily used introduce hardware extensions like network adapter built-in ide hdd support extensions extend functionality product lifecycle seen competitive advantage newer variants like slim edition interface would however offer vastly bandwidth required playstation input output devices hdd support removed pcmcia connector design abandoned favor slimmer design emotion engine contained 13.5 million transistors die measuring 240 mm fabricated sony toshiba 0.25 µm 0.18 µm effective l complementary metal–oxide–semiconductor cmos process four levels interconnect emotion engine packaged 540-contact plastic ball grid array pbga primary use emotion engine serve playstation 2 cpu first skus playstation 3 also featured emotion engine motherboard achieve backwards compatibility playstation 2 games however second revision playstation 3 lacked physical emotion engine order lower costs performing functions using software emulation performed cell broadband processor coupled hardware graphics synthesizer still present achieve playstation 2 backwards compatibility subsequent revisions graphics synthesizer removed however playstation 2 software emulator available later system software revisions use sony ps2 classics titles available purchase sony entertainment network
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Computer architecture
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air force cyber command provisional air force cyber command provisional afcyber p proposed united states air force major command existed provisional status 6 october 2008 air force announced command would brought permanent activation cyber mission would transferred standup twenty-fourth air force air force space command development afcyber announced secretary air force 2 november 2006 originally designated stand around summer 2007 pushed back late 2008 afcyber planned draw upon personnel resources 67th network warfare wing well resources eighth air force planned placed command major general william t. lord former secretary air force michael wynne summarized mission afcyber aim develop major command stands alongside air force space command air combat command provider forces president combatant commanders american people rely preserving freedom access commerce air space cyberspace 14 august 2008 air force made statement pause standing afcyber command set 1 october 2008 air force remains committed providing full-spectrum cyber capabilities include global command control electronic warfare network defense secretary chief staff air force considered delaying currently planned actions air force cyber command allow ample time comprehensive assessment afcyber requirements synchronize afcyber mission key air force initiatives new air force leaders continue make fresh assessment efforts provide nation joint force full spectrum air space cyberspace capabilities 8 october 2008 air force followed previous findings decided place afcyber numbered air force within air force space command wednesday 19 august 2009 24th air force stood following environmental impact analysis required law final list air force bases competition host cyber command headquarters listed alphabetically state 14 may 2009 air force announced lackland afb san antonio texas selected headquarters 24th air force air force downgraded version provisional cyber command however also reported continued separate armed services cyber operations exist cloud uncertainty ... light recent reports secretary defense robert gates considering creation multi-service cyber command based fort meade md tbd united states cyber command
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Computer security
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drivesentry drivesentry antivirus program developed drivesentry inc protect microsoft windows users malware available free personal non commercial use though restricted functionality drivesentry provides realtime demand virus scanner uses following methods determine application contains virus allowing run drivesentry partners offensive computing frame4 security services collect analyze malware samples database list partnering way ensures database fed multiple sources therefore offers redundancy although drivesentry basic features available free advanced features automatically updating white blacklists paid via one-off payment articles computing publications discussing new malware protection technologies – whitelisting – claim traditional antivirus technologies increasingly hard time keeping latest virus trojans malicious threats popularity internet ease data spread allows threats propagate faster requiring traditional antivirus products play catch-up new zero day threats techniques using white/blacklisting community feedback may offer greater security however functionality come cost – specifically whitelisting allows pre-vetted software executed prevents software running even harmless drivesentry avoids issue allowing user prompted programs n't appear black whitelist forces responsibility end user determine good bad drivesentry attempts help user monitoring action program calculating displaying threat rating furthermore malicious software included whitelist still executed
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Computer security
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cons computer programming fundamental function dialects lisp programming language cons 'tructs memory objects hold two values pointers values objects referred cons cells conses non-atomic s-expressions natses cons pairs lisp jargon expression cons x onto means construct new object codice_1 resulting pair left half referred first element content address register right half second element content decrement register referred loosely related object-oriented notion constructor creates new object given arguments closely related constructor function algebraic data type system word cons expressions like cons onto also part general functional programming jargon sometimes operators similar purpose especially context list processing pronounced cons good example operator ml scala f elm operator haskell adds element beginning list although cons cells used hold ordered pairs data commonly used construct complex compound data structures notably lists binary trees example lisp expression constructs cell holding 1 left half so-called field 2 right half field lisp notation value looks like note dot 1 2 indicates s-expression dotted pair so-called cons pair rather list lisp lists implemented top cons pairs specifically list structure lisp either forms basis simple singly linked list structure whose contents manipulated note list also cons pair example consider list whose elements 1 2 3 list created three steps equivalent single expression shorthand resulting value list i.e generally abbreviated thus used add one element front existing linked list example x list defined produce list another useful list procedure concatenates two existing lists i.e combines two lists single list binary trees store data leaves also easily constructed example code results tree i.e technically list 1 2 3 previous example also binary tree one happens particularly unbalanced see simply rearrange diagram following equivalent cons refer general process memory allocation opposed using destructive operations kind would used imperative programming language example sped code bit putting side effects instead cons ridiculously since lisp first-class functions data structures including cons cells implemented using functions example scheme technique known church encoding re-implements cons car cdr operations using function cons cell church encoding usual way defining data structures pure lambda calculus abstract theoretical model computation closely related scheme implementation academically interesting impractical renders cons cells indistinguishable scheme procedure well introducing unnecessary computational inefficiencies however kind encoding used complex algebraic data types variants may even turn efficient kinds encoding encoding also advantage implementable statically typed language n't variants java using interfaces instead lambdas
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Programming language topics
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pentagram video game pentagram zx spectrum msx video game released ultimate play game 1986 fourth sabreman series following adventures sabre wulf underwurlde knight lore similarly knight lore uses isometric filmation engine game written either tim chris stamper u.s. gold programming team see main article reason confusion typically ultimate release inlay card provides little actual instruction playing game includes cryptic short story introduction ultimate way describing object game recover lost pentagram artifact magical power firstly sabreman must locate one wells located maze screens shoot several times spell take resultant bucket water one broken obelisks dropped water heal stone must done four obelisks make titular pentagram appear one rooms done five magic runestones must found placed pentagram though objective pentagram complex obscure simple find fetch gameplay two previous filmation games knight lore alien 8 gameplay similar two titles main differences final revision filmation engine new ability shoot enemies projectile magic spell ability enemies respawn directional control system previous games also removed spectrum single joystick button needed fire sabreman spell could longer used jump instead joystick used jump basic gameplay sabreman previous outing knight lore without game day/night shapeshifting cycle wanders mazelike system screens filled enemies pieces movable scenery often forming obstacles puzzles exits one walls sometimes high difficult reach pentagram features larger numbers enemies either knight lore alien 8 due sabreman newfound ability kill include new flying creatures ghosts lice n't kill sabreman get way idea reprised sabreman second adventure underwurlde may even jumped onto harmless frequently annoying foes gravitate toward sabreman hover around disrupting movement sometimes even nudging platforms destroyed others witches zombies lethal touch may destroyed head straight sabreman wander straight lines meeting obstruction point change direction behaviour true wood spiders though dangerous killed wulfsheads either static move set pattern also killed enemy destroyed use sabreman new magic fireball spell another drop top screen replace short happening much faster game player progresses maximum two enemies per screen one time excluding indestructible ones already place room entered due limitations hardware previous filmation games slows crawl four moving objects screen previous two filmation games enemies may interact scenery basic way shoving movable objects logs tables along bump sabreman may also push one objects though pentagram may even move distance blast magic terms gameplay features pentagram advanced filmation titles sections gaming press becoming tired concept accused ultimate unoriginality ultimate third filmation title fifth filmation ii games nightshade gunfright counted time publishers also releasing isometric filmation-inspired games confusion also factor sinclair lamenting pentagram nowiki /nowiki instructions shrouded ultimate rather confusing 'poetry sinclair user admitted could work objective something various wishing wells dotted game even crash rated pentagram highly n't quite worked game objective time review review scores ranged 3/5 awarded sinclair user described lazy criticised perceived lack imagination setting design 93 crash smash awarded ever ultimate-friendly crash magazine cited graphics re-spawning enemies atmosphere high points
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Computer architecture
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frosmo frosmo software service company founded 2008 company holds headquarters helsinki finland additional offices also poland united kingdom singapore spain sweden company actively develops offers javascript-based conversion rate optimization solution bypass limitations current cms ecommerce platforms founded mobile gaming company dodreams earlier mikael gummerus learned gap gaming market intelligent personalization software late 2008 frosmo launched gaming platform could analyze gamers ’ behavior personalize service accordingly roughly half year later frosmo secured angel round highly distinguished investors individuals risto siilasmaa actual size investment round n't disclosed speculated relatively large although gaming platform peaked 750,000 monthly active users company quickly realized technology could well implemented outside industry 2010 frosmo developed launched social optimizer first product aimed website personalization one first tools make use facebook like button plug-in released april year plug-in acts gateway detailed visitor data venturebeat explains data collection analyzing capabilities company software got positive feedback ui deemed poor design example part solution called social optimizer tool responsible displaying personalized messages used pop-ups ugly click 2014 company estimated gained deals worth 1 million euros world travel market travel tech trade show alone
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Web technology
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squidnt squidnt port squid proxy server microsoft windows nt-based operating systems squidnt effort since merged main squid project september 2006 maintained guido serassio one core developers squid name squidnt still often used referring squid running windows official name official name squid regardless platform compile source code minimalist gnu windows microsoft visual studio windows support still largely missing squid windows may installed run command line may also installed windows service graphical user interface squid windows run following windows operating systems
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Internet protocols
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markovian discrimination markovian discrimination spam filtering method used crm114 spam filters model statistical behaviors spam nonspam accurately simple bayesian methods simple bayesian model written text contains dictionary legal words relative probabilities markovian model adds relative transition probabilities given one word predict next word based theory markov chains andrey markov hence name essence bayesian filter works single words alone markovian filter works phrases entire sentences two types markov models visible markov model hidden markov model hmm difference visible markov model current word considered contain entire state language model hidden markov model hides state presumes current word probabilistically related actual internal state language example visible markov model word predict accuracy following word hidden markov model entire prior text implies actual state predicts following words actually guarantee state prediction since latter case encountered spam filtering hidden markov models almost always used particular storage limitations specific type hidden markov model called markov random field particularly applicable usually clique size four six tokens
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Computer security
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frontbase frontbase relational database management system written ansi c. frontbase uses unicode character encoding frontbase complies sql 92 fully compliant unicode unicode 2.0 tcp/ip uses sockets frontbase available following platforms drivers adaptors include apple webobjects php3 php4 perl odbc jdbc omnis studio realbasic tcl eof fbaccess fbcaccess data types supported include integer decimal timestamp blob varchar
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Databases
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service-oriented architecture service-oriented architecture soa style software design services provided components application components communication protocol network basic principles service-oriented architecture independent vendors products technologies service discrete unit functionality accessed remotely acted upon updated independently retrieving credit card statement online service four properties according one many definitions soa different services used conjunction provide functionality large software application principle soa shares modular programming service-oriented architecture integrates distributed separately-maintained -deployed software components enabled technologies standards facilitate components communication cooperation network especially ip network soa services use protocols describe pass parse messages using description metadata metadata describes functional characteristics service quality-of-service characteristics service-oriented architecture aims allow users combine large chunks functionality form applications built purely existing services combining ad hoc manner service presents simple interface requester abstracts away underlying complexity acting black box users also access independent services without knowledge internal implementation related buzzword service-orientation promotes loose coupling services soa separates functions distinct units services developers make accessible network order allow users combine reuse production applications services corresponding consumers communicate passing data well-defined shared format coordinating activity two services manifesto published service-oriented architecture october 2009 came six core values listed follows soa seen part continuum ranges older concept distributed computing modular programming soa current practices mashups saas cloud computing see offspring soa industry standards relating exact composition service-oriented architecture although many industry sources published principles include following soa building block play three roles service consumer–provider relationship governed standardized service contract business part functional part technical part service composition patterns two broad high-level architectural styles choreography orchestration lower level enterprise integration patterns bound particular architectural style continue relevant eligible soa design service-oriented architecture implemented web services done make functional building-blocks accessible standard internet protocols independent platforms programming languages services represent either new applications wrappers around existing legacy systems make network-enabled implementers commonly build soas using web services standards one example soap gained broad industry acceptance recommendation version 1.2 w3c world wide web consortium 2003 standards also referred web service specifications also provide greater interoperability protection lock-in proprietary vendor software one however also implement soa using service-based technology jini corba rest architectures operate independently specific technologies therefore implemented using wide range technologies including implementations use one protocols example might use file-system mechanism communicate data following defined interface specification processes conforming soa concept key independent services defined interfaces called perform tasks standard way without service foreknowledge calling application without application needing knowledge service actually performs tasks soa enables development applications built combining loosely coupled interoperable services services inter-operate based formal definition contract e.g. wsdl independent underlying platform programming language interface definition hides implementation language-specific service soa-based systems therefore function independently development technologies platforms java .net etc. services written c running .net platforms services written java running java ee platforms example consumed common composite application client applications running either platform also consume services running web services facilitate reuse managed environments also wrap cobol legacy systems present software services high-level programming languages bpel specifications ws-cdl ws-coordination extend service concept providing method defining supporting orchestration fine-grained services coarse-grained business services architects turn incorporate workflows business processes implemented composite applications portals service-oriented modeling soa framework identifies various disciplines guide soa practitioners conceptualize analyze design architect service-oriented assets service-oriented modeling framework somf offers modeling language work structure map depicting various components contribute successful service-oriented modeling approach illustrates major elements identify aspects service development scheme model enables practitioners craft project plan identify milestones service-oriented initiative somf also provides common modeling notation address alignment business organizations enterprise architects believe soa help businesses respond quickly cost-effectively changing market conditions style architecture promotes reuse macro service level rather micro classes level also simplify interconnection to—and usage of—existing legacy assets soa idea organization look problem holistically business overall control theoretically would mass developers using whatever tool sets might please rather would coding standard set within business also develop enterprise-wide soa encapsulates business-oriented infrastructure soa also illustrated highway system providing efficiency car drivers point everyone car highway anywhere things would limited disorganized attempt get anywhere quickly efficiently ibm vice president web services michael liebow says soa builds highways respects soa could regarded architectural evolution rather revolution captures many best practices previous software architectures communications systems example little development solutions use truly static bindings talk equipment network taken place embracing soa approach systems position stress importance well-defined highly inter-operable interfaces predecessors soa include component-based software engineering object-oriented analysis design ooad remote objects instance corba service comprises stand-alone unit functionality available via formally defined interface services kind nano-enterprises easy produce improve also services mega-corporations constructed coordinated work subordinate services mature rollout soa effectively defines api organization reasons treating implementation services separate projects larger projects include soa promises simplify testing indirectly services autonomous stateless fully documented interfaces separate cross-cutting concerns implementation organization possesses appropriately defined test data corresponding stub built reacts test data service built full set regression tests scripts data responses also captured service service tested 'black box using existing stubs corresponding services calls test environments constructed primitive out-of-scope services stubs remainder mesh test deployments full services interface fully documented full set regression test documentation becomes simple identify problems test services testing evolves merely validate test service operates according documentation finds gaps documentation test cases services within environment managing data state idempotent services complexity examples may prove useful aid documenting service level becomes useful documentation apis within java community process provide good examples exhaustive staff would typically use important subsets 'ossjsa.pdf file within jsr-89 exemplifies file soa conflated web services however web services one option implement patterns comprise soa style absence native binary forms remote procedure call rpc applications could run slowly require processing power increasing costs implementations incur overheads soa implemented using technologies example java business integration jbi windows communication foundation wcf data distribution service dds depend remote procedure calls translation xml time emerging open-source xml parsing technologies vtd-xml various xml-compatible binary formats promise significantly improve soa performance services implemented using json instead xml suffer performance concern stateful services require consumer provider share consumer-specific context either included referenced messages exchanged provider consumer constraint drawback could reduce overall scalability service provider service-provider needs retain shared context consumer also increases coupling service provider consumer makes switching service providers difficult ultimately critics feel soa services still constrained applications represent primary challenge faced service-oriented architecture managing metadata environments based soa include many services communicate among perform tasks due fact design may involve multiple services working conjunction application may generate millions messages services may belong different organizations even competing firms creating huge trust issue thus soa governance comes scheme things another major problem faced soa lack uniform testing framework tools provide required features testing services service-oriented architecture major causes difficulty see drops.dagstuhl.de additional challenges partial solutions research roadmap input regarding software service engineering tim o'reilly coined term web 2.0 describe perceived quickly growing set web-based applications topic experienced extensive coverage involves relationship web 2.0 service-oriented architectures soa philosophy encapsulating application logic services uniformly defined interface making publicly available via discovery mechanisms notion complexity-hiding reuse also concept loosely coupling services inspired researchers elaborate similarities two philosophies soa web 2.0 respective applications argue web 2.0 soa significantly different elements thus regarded parallel philosophies whereas others consider two concepts complementary regard web 2.0 global soa philosophies web 2.0 soa serve different user needs thus expose differences respect design also technologies used real-world applications however use-cases demonstrated potential combining technologies principles web 2.0 soa microservices modern interpretation service-oriented architectures used build distributed software systems services microservice architecture processes communicate network order fulfill goal services use technology agnostic protocols aid encapsulating choice language frameworks making choice concern internal service microservices new realisation implementation approach soa become popular since 2014 introduction devops also emphasize continuous deployment agile practices single commonly agreed definition microservices following characteristics principles found literature
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Web technology
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whiskey lake microarchitecture whiskey lake intel codename third 14 nm skylake process-refinement following kaby lake refresh coffee lake intel announced low power mobile whiskey lake cpus availability august 28 2018 yet advertised whether cpu architecture contains hardware mitigations meltdown/spectre class vulnerabilities—various sources contain conflicting information unofficially announced whiskey lake hardware mitigations meltdown l1tf spectre v2 requires software mitigations well microcode/firmware update tdp cpus 15 w configurable core i5-8365u i7-8665u support intel vpro technology pentium gold celeron cpus lack avx2 support
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Computer architecture
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chuckie egg chuckie egg home computer video game released f software 1983 initially zx spectrum bbc micro dragon subsequent popularity saw released following years wide variety computers including commodore 64 acorn electron msx tatung einstein amstrad cpc atari 8-bit family later updated released amiga atari st ibm pc game written nigel alderton 16 17 years old month two development nigel took pre-release version spectrum code two-year-old software company f co-founded doug anderson mike fitzgerald f respectively doug took simultaneous development bbc micro version whilst mike webb f employee completed dragon port chuckie egg went sell million copies remained steady earner f company went administration late 1980s versions fall broadly two groups — realistic physics e.g bbc micro amstrad cpc versions without e.g zx spectrum version although substantial difference play two levels remain largely 8-bit versions cited classics hen-house harry player must collect twelve eggs positioned level countdown timer reaches zero addition piles seed may collected increase points stop countdown timer otherwise eaten hens patrol level causing pause player touches hen falls gap bottom level loses life level made solid platforms ladders occasionally lift platforms constantly move upwards upon leaving top screen reappear bottom hitting top screen one lifts however also cause player lose life eight levels defined played initially watch giant caged duck upon completion eight levels played without hens harry pursued freed duck flying around screen homing second completion eight levels yields third play hens duck fourth pass introduces additional hens finally fifth pass duck additional hens moving greater speed player completes forty levels advance 'level 41 fact exactly level 33 player starts five lives extra life awarded every 10,000 points zx spectrum version rated number 13 sinclair official top 100 games time chuckie egg also followed two years first release sequel entitled chuckie egg 2 available much smaller subset platforms release changed genre quite radically involved player harry working factory attempting create easter eggs complete toy jet set willy-style graphic adventure whilst first game level one single screen new version levels covering multiple screens although sequel gained small number admirers never received attention original 2017 remake super chuckie egg released onto mobile devices official apparently f approved chuckie egg upgrade bbc electron machines called chukee published small company called bit twiddlers gave player ability start level also introduced extended jump feature instituted holding key whilst jumping one earliest available 'hacks 8-bit computer 2009 organ grinder monkey produced unofficial upgrade original chuckie egg bbc electron includes full level editor set eight new levels
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Computer architecture
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oh mummy oh mummy computer game amstrad cpc models home computer developed gem software published amsoft 1984 often included free bundles software came computer gameplay similar 1981 arcade game amidar object game unveil treasure within level pyramid game whilst avoiding mummies level consists two-dimensional board contrast pac-man player character walks around footprints left behind surrounding area maze footprints content revealed either scroll mummy key tomb nothing order complete level necessary unveil key tombstone scroll enables player kill/eat one mummy level mummy unveiled follows player next level difficulty speed game increases player progresses levels game primarily one player limited multiplayer mode players alternate taking turn play level whilst even time considered simple terms gameplay graphics sound many people one better addictive early offerings amstrad music played gameplay based children song streets cairo poor little country maid game also released msx zx spectrum amstrad cpc 464 tatung einstein zx spectrum version given away one several introductory software packs computer particular pack also including crazy golf alien destroyer punchy treasure island disco dan
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Computer architecture
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quartz composer quartz composer node-based visual programming language provided part xcode development environment macos processing rendering graphical data quartz composer uses opengl including glsl opencl mac os x 10.6 later core image core video javascript technologies create api developer tool around simple visual programming paradigm apple embedded quartz technologies deeply operating system compositions created quartz composer played standalone quicktime-aware application although mac os x 10.4 later system screen saver itunes visualizer inside quartz composer application embedded cocoa carbon application via supplied user interface widgets quartz composer included iphone sdk way running quartz compositions ios devices quartz programming quartz composer works implementing connecting patches similar routines traditional programming languages patches base processing units execute produce result better performance patch execution follows lazy evaluation approach meaning patches executed output needed three types patches consumers processors external input patches receive output mouse clicks scrolls movements midi audio keyboard movements collection patches melded one called macro macros nested subroutines also edited control order rendering renderer assigned layer indicated upper-right corner layers rendered sequentially lowest highest renderers enabled disabled essentially turning particular layer turning unused layers often results better performance since fewer upstream patches need evaluated patches subpatches allows global parameter changes included subpatches useful lighting 3d transformation glsl shaders among things subpatch support indicated square corners patch rather typical rounded corners version 3.0 became possible turn compositions virtual patches allow user reuse functionality without store duplicate copies composition quartz composer editor allows user save flattened copy virtual patches fully expanded inside easy distribution version 4.0 extended functionality even automatically includes flattened copies virtual patches use fallback desired virtual patch n't installed host system greatly simplifies composition distribution network functionality greatly improved release leopard became possible transmit data synchronize network interface also added support open sound control transmission reception also new version 3.0 possibility write custom patch plugins using xcode template notion safe mode plugins unsafe patches fail load prevents malicious compositions performing dangerous insecure operations custom patches using apple xcode template always considered unsafe possible develop custom patch plugins version 2.0 api undocumented private never supported apple eventually templates released simplify procedure quartz composer editor holding option key selecting preferences ... menu adds 3 additional tabs options user configure options include system settings editor settings quicktime integration settings notable options include expanded tooltips software rendering uncapped framerate rendering multisample antialiasing msaa added hidden option version 4.0 allowing antialiasing inside qc editor though works gpu support msaa data inside qc one following types two additional types introduced version 4.0 data usually converted types transparently quartz composer 3.0 connections patches change color indicate conversions taking place yellow connections mean conversion taking place orange indicates possible loss data conversion number index red indicates severe conversion image boolean example quartz composer documents called compositions compositions binary property lists though xml versions also supported filename extension .qtz com.apple.quartz-composer-composition uti patches connections input port states saved composition file images stored inside composition well making self-contained compositions embedded graphics dragging movie file quartz composer editor reference movie file created providing changing image connected renderer compositions also store metadata composition author copyright description user also add arbitrary metadata items desired many image formats supported including jpeg jpeg2000 gif png tiff tga openexr bmp ico pdf pict icns raw digital camera types images maintained native form long possible rasterizing display means quartz composer keep vector images vectors cropping scaling rotating translating allows work large logical image dimensions without consuming large amounts memory processing time functionality apparent working text-based images pdfs version 3.0 added ability add annotations areas composition called notes notes parallel comments programming languages notes yellow red green blue gray overlap notes version 3.0 concept composition protocols introduced protocols provide template required optional inputs outputs qualify conforming compositions various purposes following protocols available default additional protocol apple uses private api one new protocol added version 4.0 officially supported way add additional protocols quartz composer however undocumented methods may make possible future addition protocols compositions also conform different runtimes quartz composer available leopard runtimes tiger 32-bit well 32-bit 64-bit versions leopard quartz composer runtime editor also indicate used patches unsafe unavailable tiger aid making compatible compositions system-wide composition repository available version 3.0 allows applications share make use common compositions effects processing also possible applications query repository compositions match certain criteria protocol conformance repository spread across 3 file system locations adding compositions repository simple adding composition file one locations became possible compare compositions quartz composer 3.0 feature allows user compare inputs rendered output graph appearance two compositions developer tool called quartz composer visualizer released quartz composer 3.0 allows compositions rendered across multiple screens single machine even spanned across several machines displays support automator actions added release leopard pierre-olivier latour originally developed predecessor quartz composer name pixelshox studio
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Operating systems
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dynamic recompilation computer science dynamic recompilation sometimes abbreviated dynarec pseudo-acronym drc feature emulators virtual machines system may recompile part program execution compiling execution system tailor generated code reflect program run-time environment potentially produce efficient code exploiting information available traditional static compiler dynamic recompilers used convert machine code architectures runtime task often needed emulation legacy gaming platforms cases system may employ dynamic recompilation part adaptive optimization strategy execute portable program representation java .net common language runtime bytecodes full-speed debuggers also utilize dynamic recompilation reduce space overhead incurred deoptimization techniques features dynamic thread migration main tasks dynamic recompiler perform dynamic recompiler may also perform auxiliary tasks suppose program run emulator needs copy null-terminated string program compiled originally simple processor processor copy byte time must first reading source string register writing register destination string original program might look something like emulator might running processor similar extremely good copying strings emulator knows take advantage might recognize string copy sequence instructions decide rewrite efficiently execution speed emulation say instruction new processor called movs specifically designed copy strings efficiently theoretical movs instruction copies 16 bytes time without load register c stop copies 0 byte marks end string set zero flag also knows addresses strings registers b increments b 16 every time executes ready next copy new recompiled code might look something like immediate speed benefit simply processor n't load many instructions task also movs instruction likely optimized processor designer efficient sequence used first example example may make better use parallel execution processor increment b still copying bytes
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Programming language topics
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kateos kateos linux distribution originally based slackware designed intermediate users package management system used called tgzex .tgz packages unlike slackware packages support dependency tracking optional internationalized descriptions designed ease update two native tools package management pkg updateos last version released kateos iii 3.6 including live cd 2007 kateos project founded end 2003 damian rakowski kate linux 1.0 rabbit series first version system published 2004-10-09 system based slackware 9.0 unlike slackware used pam authentication mechanism possessed enriched package set due problems main server worked infrequently hardly anyone learned existence kate 1.0 move another server project begun gradually acquire users time kate 1.0.1 fix release including updatepack 1 live version published kate linux 2.0 zyklon series ii version 2.0 published 2005-04-09 longer based slackware long-term edition base development also first edition using linux 2.6 2005-05-06 name project changed kateos 2005-05-22 version 2.0.1 published providing tool managing remote updating tgzex packages tool called updateos written piotr korzuszek 2005-06-23 version 2.1 published updateos could install packages remotely 12 august 2005 first live edition series ii published distinctive graphical design used squashfs technology 2 gb data packed one cd unionfs detected hardware configured x server automatically 2005-10-13 last version series ii published 2.3 updateos gained new possibilities system better hardware autodetection discover tool kateos 3.0 virgen series iii 12 april 2006 first snapshot kateos 3.0 published 2006-07-09 version 3.0 published packaging system completely rewritten resulting pkg updateos2 tools libupdateos libsmarttools libraries functionality tgzex packages widened time include dependency tracking descriptions many languages installation process simplified allow full install 15 minutes system used udev d-bus hal detect hardware mount devices automatically 4 august 2006 first 'live edition series iii published aimed demonstrate possibilities kateos 3.0 used data rescue system cd contained 2gb data including xfce desktop environment many office multimedia applications detected configured hardware automatically 7 october 2006 version 3.1 published contained fixes updated gnome desktop environment first edition gnome adjusted especially kateos system also included update-notifier daemon system trace icon changed blinked new updates discovered let user choose packages updated update based libupdateos library supported kateos packages repositories 21 december 2006 version 3.2 published apart fixes updates included new tool katepkg katepkg graphical package manager written php php-gtk library making kateos first system include library default distribution designed allow users easily install update remove packages system supports number repositories including local ones located user hard drive also libsmarttools library optimized resulting 60 speed boost applications using updateos2 version kateos switched bootloader lilo grub make kernel updates easier 17 september 2007 version 3.6 released eight months development version brought several new updated features kateos software driven suspend mode improved internalization support addition several new programs katelan realm help make configuring system user friendly live cd version 3.6 first kateos provide disc installer called install agent allowing user directly install hard disk trying system live new kateos releases planned supported around two years users encouraged update via updateos command newer versions distribution although major version updates series updates e.g ii -- iii recommended damian rakowski 'project initiator leader 1st developer stated project named friend name kate simple nice everybody knows
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Operating systems
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apple lisa lisa desktop computer developed apple released january 19 1983 one first personal computers offer graphical user interface gui machine aimed individual business users development lisa began 1978 underwent many changes development period shipping us 9,995 five-megabyte hard drive lisa challenged high price insufficient performance insufficient software library crash-prone operating system unreliable apple fileware twiggy floppy disks immediate release cheaper faster macintosh — yielding lifelong sales 10,000 units two years 1982 steve jobs forced lisa project appropriated existing macintosh project jef raskin conceived 1979 led develop text-based appliance computer jobs immediately redefined macintosh cheaper usable version graphical lisa macintosh launched january 1984 quickly surpassing lisa sales assimilating increasing numbers lisa staff newer lisa models introduced addressed faults lowered price considerably platform failed achieve favorable sales compared much less expensive mac final model lisa 2/10 modified high end macintosh series macintosh xl considered commercial failure technical acclaim lisa introduced number advanced features would reappear macintosh many years include operating system protected memory document-oriented workflow hardware overall advanced macintosh hard drive support 2 megabytes mb random-access memory ram expansion slots larger higher-resolution display main exception 68000 processor macintosh clocked 7.89 megahertz mhz lisa 5 mhz complexity lisa operating system associated programs overtaxes slower processor enough users perceive sluggish workstation-tier price lack technical application library made unviable technical workstation market though documentation shipped original lisa refers lisa apple officially stated name acronym locally integrated software architecture lisa steve jobs first daughter named lisa nicole brennan born 1978 normally inferred name also personal association perhaps acronym backronym invented later fit name andy hertzfeld states acronym reverse engineered name lisa late 1982 apple marketing team hired marketing consultancy firm come names replace lisa macintosh time considered jef raskin merely internal project codenames rejected suggestions privately hertzfeld software developers used lisa invented stupid acronym recursive backronym computer industry pundits coined term let invent acronym fit lisa name decades later jobs would tell biographer walter isaacson obviously named daughter project began 1978 effort create modern version then-conventional design epitomized apple ii ten-person team occupied first dedicated office nicknamed good earth building located 20863 stevens creek boulevard next restaurant named good earth initial team leader ken rothmuller soon replaced john couch whose direction project evolved window-and-mouse-driven form eventual release trip hawkins jef raskin contributed change design apple cofounder steve jobs involved concept xerox palo alto research center research already underway several years create new humanized way organize computer screen today known desktop metaphor steve jobs visited xerox parc 1979 absorbed excited revolutionary mouse-driven gui xerox alto late 1979 jobs successfully negotiated payment apple stock xerox exchange lisa team receive two demonstrations ongoing research projects xerox parc apple team saw demonstration alto computer able see action basic elements constituted workable gui lisa team put great deal work making graphical interface mainstream commercial product lisa major project apple reportedly spent 50 million development 90 people participated design plus sales marketing effort launch machine byte credited wayne rosing important person development computer hardware machine went production point became technical lead entire lisa project hardware development team headed robert paratore industrial design product design mechanical packaging headed bill dresselhaus principal product designer lisa team internal product designers contract product designers firm eventually became ideo bruce daniels charge applications development larry tesler charge system software user interface designed six month period hardware operating system applications created parallel 1982 steve jobs forced lisa project appropriated existing macintosh project jef raskin conceived 1979 led develop text-based appliance computer jobs redefined macintosh cheaper usable lisa leading project parallel secret substantially motivated compete lisa team september 1981 announcement ibm pc infoworld reported lisa mcintosh another apple computer secretly development ready release within year described lisa 68000 128kb ram designed compete new xerox star considerably lower price may 1982 magazine reported apple yet-to-be-announced lisa 68000 network work station also widely rumored mouse lisa low sales quickly surpassed january 1984 launch macintosh newer versions lisa introduced addressed faults lowered price considerably failed achieve favorable sales compared much less expensive mac macintosh project assimilated lot lisa staff final revision lisa lisa 2/10 modified sold macintosh xl high cost delays release date contributed lisa discontinuation although repackaged sold 4,995 lisa 2 1986 entire lisa platform discontinued 1987 sun remarketing purchased 5,000 macintosh xls upgraded leftover lisa computers spare parts available recently cherokee data purchased sun remarketing went business 1989 help sun remarketing apple disposed approximately 2,700 unsold lisas guarded landfill logan utah order receive tax write-off unsold inventory lisa first introduced january 19 1983 one first personal computer systems graphical user interface gui sold commercially uses motorola 68000 cpu clocked 5 mhz 1 mb ram lisa computer real-time clock uses 4-bit integer base year defined 1980 software wo n't accept value 1981 valid range 1981–1995 thus 1995 problem real-time clock depended 4 x aa-cell nicd pack batteries lasted hours main power present often causing packs burst open leak corrosive alkaline electrolyte could ruin circuit boards original lisa lisa 1 two apple fileware 5.25-inch double-sided floppy disk drives commonly known apple internal code name drive twiggy capacity approximately 871 kb proved unreliable required special diskettes macintosh intended implement single twiggy drive partway development revised use sony 400 kb microfloppy drive optional external 5 mb later 10 mb apple profile hard drive originally designed apple iii available introduction lisa 2/10 optional 10 mb internal proprietary hard disk manufactured apple known widget also offered first hardware revision lisa 2 released january 1984 priced 3,495 5,495 us much less expensive original model dropped twiggy floppy drives favor single 400k sony microfloppy lisa 2 little 512 kb ram lisa 2/5 consists lisa 2 bundled external 5- 10-megabyte hard drive 1984 time macintosh officially announced apple offered free upgrades lisa 2/5 lisa 1 owners swapping pair twiggy drives single 3.5-inch drive updating boot rom i/o rom addition lisa 2 new front faceplate included accommodate reconfigured floppy disk drive change lisa 2 notable distinction introducing new inlaid apple logo well first snow white design language features lisa 2/10 features 10mb internal hard drive external parallel port standard configuration 1mb ram developing early macintosh software required lisa 2 relatively third-party hardware offerings lisa compared earlier apple ii ast offered 1.5 mb memory board – combined standard apple 512 kb memory board – expands lisa total 2 mb memory maximum amount mmu address late product life lisa third-party hard disk drives scsi controllers double-sided 3.5-inch floppy-disk upgrades unlike original macintosh lisa features expansion slots conversely like apple ii open system lisa 2 motherboard basic backplane virtually electronic components plenty edge connector sockets slots two ram slots one cpu upgrade slot one i/o slot parallel placement end three lisa slots parallel january 1985 following macintosh lisa 2/10 integrated 10 mb hard drive rebranded macintosh xl given hardware software kit enabling reboot macintosh mode positioning apple high-end macintosh price lowered yet 4,000 sales tripled ceo john sculley said apple would lost money increasing production meet new demand apple discontinued macintosh xl leaving eight-month void apple high-end product line macintosh plus introduced 1986 lisa operating system features protected memory enabled crude hardware circuit compared sun-1 workstation c. 1982 features full memory management unit based part elements failed apple iii sos operating system released three years earlier lisa disk operating system also organizes files hierarchical directories unix workstations time main competition lisa terms price hardware filesystem directories correspond gui folders previous xerox parc computers lisa borrowed heavily conceptually lisa resembles xerox star sense envisioned office computing system consequently lisa two main user modes lisa office system workshop lisa office system gui environment end users workshop program development environment almost entirely text-based though uses gui text editor lisa office system eventually renamed 7/7 reference seven supplied application programs lisawrite lisacalc lisadraw lisagraph lisaproject lisalist lisaterminal operating system – rather applications – incapable supporting demands advanced users prone crash restart heavy load large complex spreadsheets graphs produced apple warranty said software works precisely stated apple refunded unspecified number users full systems operating system frailties costly recalls combined high price point led failure lisa marketplace within months lisa introduction us fully translated versions software documentation commercially available british french west german italian spanish markets followed several scandinavian versions shortly thereafter user interface os seven applications lisaguide lisa diagnostics rom fully translated without programming required using resource files translation kit keyboard identify native language layout entire user experience language including hardware diagnostic messages although several non-english keyboard layouts available dvorak keyboard layout never ported lisa though porting available apple iii iie iic later done macintosh keyboard-mapping lisa complex requires building new os kernels contain images layouts due serious memory constraints keyboard layouts stored differences set standard layouts thus bytes needed accommodate additional layouts exception dvorak layout moves every key thus requires hundreds extra bytes precious kernel storage regardless whether needed localized version built globalized core requires grammatical linguistic cultural adaptations throughout user interface including formats dates numbers times currencies sorting even word phrase order alerts dialog boxes kit provided translation work done native-speaking apple marketing staff country localization effort resulted many lisa unit sales outside us inside us product lifespan setting new standards future localized software products global project co-ordination april 1984 following release macintosh apple introduced macworks software emulation environment allows lisa run macintosh system software applications macworks helped make lisa attractive potential customers although enable macintosh emulation access hard disk september january 1985 re-branded macworks xl became primary system application designed turn lisa macintosh xl significant impediment third-party software lisa fact first launched lisa office system could used write programs separate development os called lisa workshop required development process engineers would alternate two oses startup writing compiling code one os testing later lisa workshop used develop software macintosh years macintosh-native development system developed lifetime lisa never went beyond original seven applications apple deemed enough everything although unipress software offer unix system iii 495 byte wrote february 1983 previewing lisa important development computers last five years easily outpacing ibm pc acknowledged 9,995 price high concluded apple ... unaware people would incredibly interested similar less expensive machine 'll see happens apple lisa commercial failure apple largest since failure apple iii 1980 apple sold approximately 10,000 lisa machines price generating total sales 100 million development cost 150 million corporate target market reluctant machine poor price-performance ratio high price put lisa price realm technical workstations without much technical application library lisa implementation requisite graphical interface paradigm novel costly sapping much computer resources away high end usage make business sense time largest lisa customer nasa used lisaproject project management lisa largely unable compete less expensive ibm pc dominating business desktop computing part due x86 platform backward compatibility cp/m operating system many existing business software applications originally written cp/m basic 1984 release macintosh half price better performance end lisa viability lisa 2 mac rom-enabled sibling macintosh xl final two releases lisa line discontinued april 1985 macintosh xl hardware software conversion kit effectively reboot lisa macintosh mode 1986 apple offered lisa xl owners opportunity return computer additional payment us 1,498 exchange macintosh plus hard disk 20 reportedly 2,700 working unsold lisa computers buried landfill macintosh project led apple cofounder steve jobs borrowed heavily lisa gui paradigm directly took many staff create apple ultimate flagship platform next several decades progenitor iphone apple culture object-oriented programming lisa contributed 1988 conception pink first attempt rearchitect operating system macintosh
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Computer architecture
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war video game war video game published 1989 dinamic software player controls character post-apocalyptic city probably nuclear war released unreleased artworks luis royo alfonso azpiri reveals city post-nuclear version new york city game consisted two separate parts second half game made accessible successfully completing part one whereupon player given password 94656981 first part localized streets city sequence fights minor enemies big bosses target find entry city underground transport opposed part map second part localized railways stations city underground transport enemies bigger first load complex design character movements slightly different parts common movements move left right jump duck first part way fighting using fists legs second part gives character ability use kind futuristic gun loads featured parts two levels 16-bit versions featured digitized voices ports featured tricky graphical effects e.g. amstrad cpc version included mode 0 mode 1 graphics time war featured two classical fx brands dinamic fx double load consisting two separate parts get advantage computer memory fx giant sprites made use big sprites even ¾ total play area height note fx brands simply commercial names dinamic used name features games giant sprites trick sprites composed set small parts allowed reusing parts different characters e.g. lot enemies share trousers leg movements ports problem vertical sync monitor lets player easily see trick sometimes characters got rendered divided two clearly different slices computer magazines published notes coin-op version game never released outside spain although coin-op game could played many years ago parque de atracciones de madrid graphically identical 16-bit computers counterpart cover artwork war created artist luis royo time development began spanish comic book author alfonso azpiri collaborator dinamic creation box art games azpiri whose brother jorge contributed graphics amstrad cpc version war drew initial version intended cover artwork game however due protracted development schedule time game completed azpiri ended collaboration dinamic work software company topo soft war released new cover art commissioned royo 2011 nearly two decades since dissolution dinamic founding members acquired rights distribute windows game collapse spain italy new software company fx interactive game rebranded war marketed belonging fictional universe original 1989 game
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Computer architecture
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fuzzy logix fuzzy logix develops high -performance analytics solutions big data fuzzy logix offers in-database gpu-based analytics solutions built comprehensive growing libraries 600 mathematical statistical simulation data mining time series financial models fuzzy logix formed 2007 partha sen mike upchurch met working bank america shared goal making analytics pervasive 2008 fuzzy logix released db lytix first complete commercially available library in-database analytics fin lytix released 2010 first comprehensive library in-database financial models 2010 aperity oem ’ fuzzy logix models run analytics cpg software saas solutions 2011 quest dell released toad data analyst data point included fuzzy logix ’ models running mysql company started charlotte nc usa headquarters located today fuzzy logix offices richmond va cupertino ca uk india reseller partners mexico sweden japan china fuzzy logix offers four software products db lytix fin lytix comprehensive libraries in-database analytic models libraries leverage user defined function udf capability available database platforms software available multiple database platforms since data movement database minimized database platforms growing increasingly powerful in-database models run 5x 100x faster models use multi-tiered analytics platforms fuzzy logix released first comprehensive library in-database models db lytix 2008 library development since 1998 library includes mathematical statistical data mining simulation classification models fuzzy logix released first comprehensive financial library fin lytix 2010 library contains models equity fixed income foreign exchange interest rate time series models used financial services industry risk management pricing portfolio optimization aster data informix netezza ibm puredata systems mysql paraccel sql server sybase iq teradata fuzzy logix solutions effective optimizing business process performance utilizing mathematical modeling based risk management industries like marketing healthcare insurance digital media services financial services investment retail banking brokerage houses stock exchanges hedge fund management examples techniques superior performance potentially utilized much broadly solving complex problems industries organization government programs educational institutions research need running analytics big data using complex models solutions derived predictive modeling behavior assessing risk modeling optimal system
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Databases
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full disclosure computer security field computer security independent researchers often discover flaws software abused cause unintended behaviour flaws called vulnerabilities process analysis vulnerabilities shared third parties subject much debate referred researcher disclosure policy full disclosure practice publishing analysis software vulnerabilities early possible making data accessible everyone without restriction primary purpose widely disseminating information vulnerabilities potential victims knowledgeable attack essay topic bruce schneier stated full disclosure – practice making details security vulnerabilities public – damned good idea public scrutiny reliable way improve security secrecy makes us less secure leonard rose co-creator electronic mailing list superseded bugtraq become de facto forum disseminating advisories explains n't believe security obscurity far know full disclosure way ensure everyone insiders access information need controversy around public disclosure sensitive information new issue full disclosure first raised context locksmithing 19th-century controversy regarding whether weaknesses lock systems kept secret locksmithing community revealed public today three major disclosure policies others categorized non disclosure coordinated disclosure full disclosure major stakeholders vulnerability research disclosure policies shaped various motivations uncommon observe campaigning marketing lobbying preferred policy adopted chastising dissent many prominent security researchers favor full disclosure whereas vendors prefer coordinated disclosure non disclosure generally favoured commercial exploit vendors blackhat hackers proponents coordinated disclosure believe software vendors right control vulnerability information concerning products primary tenet coordinated disclosure nobody informed vulnerability software vendor gives permission often exceptions variations policy distribution must initially limited vendors given privileged access nonpublic research advocates coordinated disclosure often prefer weighted less-descriptive term “ responsible disclosure ” coined microsoft security manager scott culp essay “ time end information anarchy ” referring full disclosure microsoft later asked term phased favour “ coordinated disclosure ” although reasoning varies many practitioners argue end-users benefit access vulnerability information without guidance patches vendor risks sharing research malicious actors great little benefit microsoft explain coordinated disclosure serves everyone best interests ensuring customers receive comprehensive high-quality updates security vulnerabilities exposed malicious attacks update developed full disclosure policy publishing information vulnerabilities without restriction early possible making information accessible general public without restriction general proponents full disclosure believe benefits freely available vulnerability research outweigh risks whereas opponents prefer limit distribution free availability vulnerability information allows users administrators understand react vulnerabilities systems allows customers pressure vendors fix vulnerabilities vendors may otherwise feel incentive solve fundamental problems coordinated disclosure full disclosure resolve discovery specific flaw vulnerability mutually exclusive event multiple researchers differing motivations discover flaws independently standard way make vulnerability information available public researchers often use mailing lists dedicated topic academic papers industry conferences non disclosure principle vulnerability information shared shared non-disclosure agreement either contractually informally common proponents non-disclosure include commercial exploit vendors researchers intend exploit flaws find proponents security obscurity researchers favour coordinated disclosure believe users make use advanced knowledge vulnerabilities without guidance vendor majority best served limiting distribution vulnerability information advocates argue low-skilled attackers use information perform sophisticated attacks would otherwise beyond ability potential benefit outweigh potential harm caused malevolent actors vendor prepared guidance even unsophisticated users digest information made public argument presupposes vulnerability discovery mutually exclusive event one person discover vulnerability many examples vulnerabilities discovered simultaneously often exploited secrecy discovery researchers may exist users benefit vulnerability information full disclosure advocates believe demonstrates contempt intelligence end users true users benefit vulnerability information 're concerned security networks position hire expert assist would hire mechanic help car non disclosure typically used researcher intends use knowledge vulnerability attack computer systems operated enemies trade knowledge vulnerability third party profit typically use attack enemies researchers practicing non disclosure generally concerned improving security protecting networks however proponents argue simply want assist vendors claim intent harm others full coordinated disclosure advocates declare similar goals motivations simply disagreeing best achieve non disclosure entirely incompatible
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Computer security
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martin mitchell defection martin mitchell defection occurred september 1960 two u.s. national security agency nsa cryptologists william hamilton martin bernon f. mitchell defected soviet union secret 1963 nsa study said beyond doubt event likely future greater impact agency security program martin mitchell met serving u.s. navy japan early 1950s joined nsa day 1957 defected together soviet union 1960 moscow press conference revealed denounced various u.s. policies especially provocative incursions air space nations spying america allies underscoring apprehension nuclear war said would attempt crawl moon thought would lessen threat atomic war within days citing trusted source congressman francis e. walter chairman house un-american activities committee huac said martin mitchell sex deviates prompting sensational press coverage u.s. officials national security council privately shared assumption two part traitorous homosexual network classified nsa investigations hand determined pair greatly inflated opinions concerning intellectual attainments talents defected satisfy social aspirations house un-american activities committee publicly intimated interpretation relationship martin mitchell homosexual reading guided pentagon discussion defection decades william hamilton martin may 27 1931 – january 17 1987 born columbus georgia family soon moved washington state father president ellensburg chamber commerce graduated ellensburg high school two years studies central washington college education central washington university earned degree mathematics university washington seattle 1947 enlisted united states navy served 1951 1954 working cryptologist naval security group japan martin played chess collected japanese sword handles tsuka bernon f. mitchell march 11 1929 – november 12 2001 born raised eureka california enlisted us navy one year college gained experience cryptologist tour duty navy 1951 1954 serving japan naval security group kami seya stayed japan another year working army security agency following navy service earned bachelor degree stanford university martin mitchell became friends navy service naval communications intercept facility kami seya japan kept touch returned school navy service encountered one another recruited national security agency nsa 1957 years nsa uneventful martin gained enough recognition twice awarded scholarships study towards master degree mitchell martin became disturbed learned american incursions foreign airspace realized congress unaware nsa-sponsored flights february 1959 violation nsa rules tried report knew congressman expressed frustration information receiving nsa ohio democrat wayne hays december 1959 pair visited cuba without notifying superiors required nsa procedures june 25 1960 mitchell martin left u.s. mexico traveled havana sailed russian freighter soviet union august 5 pentagon announced returned vacation said likelihood gone behind iron curtain september 6 1960 appeared joint news conference house journalists moscow announced requested asylum soviet citizenship new york times described long-time bachelor friends reported smiled described social advantages anticipated soviet union prepared statement said talents women encouraged utilized much greater extent soviet union united states feel enriches soviet society makes soviet women desirable mates conference defectors made public first time mission activities nsa prepared statement written said without consulting government soviet union said united states government unscrupulous accused soviet government also said particularly attacked views general thomas s. power recently told congressional committee u.s. needed maintain nuclear first-strike capability senator barry goldwater opposition banning nuclear tests negotiating disarmament treaty contrast said would attempt crawl moon thought would lessen threat atomic war u.s. recently admitted sending reconnaissance flights foreign countries recent years martin mitchell said knew navy service flights occurred early 1952–1954 detailed u.s. c-130 flight soviet armenia soviets brought contended designed gain understanding soviet defenses therefore represented american interest attacking soviets rather defending also complained restrictions freedom u.s. government confiscation mail particularly freedom theists whose political convictions unpopular response american government called mitchell martin charges completely false department defense called turncoats tools soviet propaganda one mentally sick obviously confused also characterized positions nsa junior mathematicians issue pair sexuality raised dismissed report representative francis e. walter democrat pennsylvania chairman house un-american activities committee denied made allegation reported news agency one men described homosexual report federal bureau investigation pentagon spokesman told reporters nothing mitchell martin personnel records suggest homosexuality sexual perversion next day congressman walter explicitly stated source trusted told two defectors known acquaintances 'sex deviates charge promptly picked press resulted immediately stories homosexuals recruiting sexual deviates jobs federal government hearst newspapers referred martin mitchell two defecting blackmailed homosexual specialists love team time reported review security checks turned mitchell visit psychiatrist presumably concern homosexual tendencies interview soviet news agency tass december 1960 expressed belief american espionage russia u.s. allies neutral nations would continue unchanged despite inauguration new american president january 1961 according later government report martin—who fluent russian—studied leningrad university saint petersburg state university used name vladimir sokolodsky married soviet citizen divorced 1963 later told russian newspaper defection foolhardy also expressed disappointment russians trust important work occasionally sought help american visitors arranging repatriation including donald duffy vice president kaiser foundation bandleader benny goodman another occasion told american defecting believed vision russia presented propaganda publications like ussr soviet life 1975 source told u.s. government martin totally skids 1979 inquired american consulate repatriation result case examined stripped american citizenship next denied permission immigrate u.s. denied tourist visa martin eventually left soviet union died cancer mexico january 17 1987 tijuana hospital del mar buried u.s. less known mitchell renounced u.s. citizenship remained soviet union rest life married galina vladimirovna yakovleva member piano department faculty leningrad conservatory became alcoholic regretted decision mitchell died november 2001 buried st. petersburg defections another life inside u.s. intelligence community meeting national security council october 1960 officials considered response martin-mitchell affair attorney general william p. rogers believed soviets list homosexuals use recruiting blackmail efforts martin mitchell part organized group several meeting thought polygraph tests would help prevent hiring homosexuals president eisenhower wanted central authority coordinate government lists homosexuals order prevent another occurrence nsa needed understand motivated defectors initial investigation turned little interest notes psychological counseling sessions 1940s described martin brilliant emotionally immature offered diagnosis beginning character neurosis schizoid tendencies mentioned likely sadistic mitchell told nsa questioned long starting work agency experimented sexually teenager dogs chickens immediate nsa response focused sexual issues july 1961 agency announced purged 26 employees identified sexual deviates though added qualification homosexuals yet series nsa investigations gave little credit role sexuality mitchell martin defection 1961 nsa report called close friends somewhat anti-social egotistical arrogant insecure young men whose place society much lower believed deserved greatly inflated opinions concerning intellectual attainments talents 1963 another nsa report found clear motive recruited foreigners termed defection impulsive nsa files obtained journalists seattle weekly 2007 cited definitive testimony part women acquaintances attested heterosexuality perversions recorded martin all-controlling sadomasochism occasionally watched women sex sex multiple female partners 1962 congressman walters house un-american activities committee huac concluded 13-month investigation issued report defections mitchell told psychiatrist affairs men women troubled sexual identity report referred homosexual problems report never identified rationale mitchell martin defections focused inadequacy investigations granted security clearances despite evidence homosexuality sexual abnormality atheism communist sympathies part one men report made series recommendations respect nsa hiring practices security investigations promptly adopted agency later government analyses went beyond characterizations huac account unaware nsa unpublished analysis despite contrary evidence 1991 study pentagon defense security service—still use 2007—called martin mitchell publicly known homosexuals
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Computer security
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network security policy network security policy nsp generic document outlines rules computer network access determines policies enforced lays basic architecture company security/ network security environment document usually several pages long written committee security policy goes far beyond simple idea keep bad guys complex document meant govern data access web-browsing habits use passwords encryption email attachments specifies rules individuals groups individuals throughout company security policy keep malicious users also exert control potential risky users within organization first step creating policy understand information services available users potential damage whether protection already place prevent misuse addition security policy dictate hierarchy access permissions grant users access necessary completion work writing security document major undertaking good start achieved using template national institute standards technology provides security-policy guideline policies could expressed set instructions could understood special purpose network hardware dedicated securing network
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Computer security
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joost joost internet tv service created niklas zennström janus friis founders skype kazaa 2007–2008 joost used peer-to-peer tv p2ptv technology distribute content mozilla-based desktop player late 2008 migrated use flash-based web player instead joost began development 2006 working code name venice project zennström friis assembled teams 150 software developers six cities around world including new york city london leiden toulouse according zennström 25 july 2007 press conference skype held tallinn estonia joost signed million beta testers launch scheduled end 2007 team signed warner music indianapolis motor speedway productions indianapolis 500 indycar series production company endemol beta february 2007 viacom entered deal company distribute content media properties including mtv networks black entertainment television bet film studio paramount pictures company went restructuring several times sold assets 2009 suspended operations 2012 program based p2ptv technology expected deliver relaying near-tv resolution images turned pc instant on-demand tv need additional set-up box news updates discussion forums show ratings multi-user chat sessions often linked active stream/channel made possible use semi-transparent widget overlays initial version software based xulrunner audio management re-used zap media kit peer peer layer on-demand video came joltid company also provided peer peer layer skype peer peer layer live video developed scratch first trial run broadcasting march madness 2008 video playback used corecodec coreavc h.264 video decoder joost soft launched widget api august 29 2007 non-copyleft open source license encouraged third party developers create tools tv 2.0 platform 2009 joost released special website playstation 3 internet browser took advantage browser full screen x button capabilities holding x button could choose various video options using d-pad opposed streaming technology clients get feed server p2p tv technology differs sense servers serve handful clients clients turn propagate stream downstream clients moves distribution costs channel owner user co-owners skype friis zennström received part 2.6 billion cash payment ebay acquired skype 2005 easily covered development marketing cost joost venture week launching service founders announced raised additional 45 million sequoia capital backed yahoo google youtube index ventures early investor skype li ka-shing hong kong tycoon cbs us media group taken “ small minority ” stakes start-up viacom also understood among partners although nature backing disclosed joost service ad-supported advertising analogous shown traditional tv according former ceo fredrik de wahl joost 40 advertisers including sony pictures bmw sprite aside injected video-advertisements served additional interactive advertisements via overlays short pop-ups clickable viacom inc. joost entered content provider agreement joost platform february 20 2007 agreement divisions viacom including mtv networks bet networks paramount pictures license television theatrical programming joost came shortly viacom requested 100,000 potentially infringing videos removed youtube.com showed preference viacom joost platform youtube joost licensing agreements place ministry sound tv aardman animation warner music production company endemol fremantle media rdf media diversion media cbs centerstaging rehearsals.com may 1 2007 joost signed deal distribute nhl content including full game replays stanley cup finals vintage games bollywood distributor eros international also announced deal joost 2007 majority content joost restricted users united states america due lack international licensing arrangements company first ceo frederick de wahl succeeded mike volpi june 2007 volpi stepped july 2009 amidst round job cuts succeeded matt zelesko volpi blamed content companies sidelining joost december 17 2008 joost sent email customers explaining project moving website-only model joost application would stop working friday december 19 joost uk subsidiary liquidated 2009 november 24 2009 adconion media group announced would purchasing company assets undisclosed amount companies index ventures major investor 30 april 2012 joost.com website announced without explanation re-evaluating joost.com purpose services near-term decided suspend site allow full re-evaluation may 2012 adconion rebranded folded joost media smartclip another company previously acquired zennstrom written post-mortem analysis company 2016 book founders fail
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Internet protocols
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g-code g-code also rs-274 many variants common name widely used numerical control nc programming language used mainly computer-aided manufacturing control automated machine tools g-code language people tell computerized machine tools make something defined g-code instructions provided machine controller industrial computer tells motors move fast move path follow two common situations within machine tool lathe mill cutting tool moved according instructions toolpath cutting away material leave finished workpiece and/or unfinished workpiece precisely positioned 9 axes around 3 dimensions relative toolpath either move relative concept also extends noncutting tools forming burnishing tools photoplotting additive methods 3d printing measuring instruments first implementation numerical control programming language developed mit servomechanisms laboratory late 1950s decades since many implementations developed many commercial noncommercial organizations g-code often used implementations main standardized version used united states settled electronic industries alliance early 1960s final revision approved february 1980 rs-274-d countries standard iso 6983 often used many european countries use standards example din 66025 used germany pn-73m-55256 pn-93/m-55251 formerly used poland extensions variations added independently control manufacturers machine tool manufacturers operators specific controller must aware differences manufacturer product one standardized version g-code known bcl binary cutter language used machines developed mit bcl developed control cnc machines terms straight lines arcs 1970s 1990s many cnc machine tool builders attempted overcome compatibility difficulties standardizing machine tool controllers built fanuc siemens another market dominator cnc controls especially europe 2010s controller differences incompatibility troublesome machining operations developed cad/cam applications output appropriate g-code called post specific machine tool cnc machines use conversational programming wizard-like programming mode either hides g-code completely bypasses use g-code popular examples okuma advanced one touch aot southwestern industries prototrak mazak mazatrol hurco ultimax winmax haas intuitive programming system ips mori seiki caps conversational software g-code began limited language lacked constructs loops conditional operators programmer-declared variables natural-word-including names expressions use unable encode logic way connect dots programmer figured many dots locations longhand latest implementations g-code include macro language capabilities somewhat closer high-level programming language additionally primary manufacturers e.g. fanuc siemens heidenhain provide access plc data axis positioning data tool data via variables used nc programs constructs make easier develop automation applications g-codes also called preparatory codes word cnc program begins letter g. generally code telling machine tool type action perform codes type codes thought like registers computer pointed years term g-code imprecise g one many letter addresses complete language comes literal sense term referring one letter address specific codes formed example g00 g01 g28 every letter english alphabet used somewhere language nevertheless g-code metonymically established common name language letter addresses used milling turning used bold letters seen frequently throughout program sources smid 2008 smid 2010 green et al 1996 sources smid 2008 smid 2010 green et al 1996 sources smid 2008 smid 2010 green et al 1996 older controls require codes separate blocks line generic program demonstrates use g-code turn part 1 diameter 1 long assume bar material machine bar slightly oversized length diameter bar protrudes 1 face chuck caution generic might work real machine pay particular attention point 5 several points note g-code programming environments evolved parallel general programming—from earliest environments e.g. writing program pencil typing tape puncher latest environments combine cad computer-aided design cam computer-aided manufacturing richly featured g-code editors g-code editors analogous xml editors using colors indents semantically plus features aid user ways basic text editors ca n't cam packages analogous ides general programming two high-level paradigm shifts 1 abandoning manual programming nothing pencil text editor human mind systems generate g-code automatically via postprocessors analogous development visual techniques general programming 2 abandoning hardcoded constructs parametric ones analogous difference general programming hardcoding constant equation versus declaring variable assigning new values object-oriented approach general macro parametric cnc programming uses human-friendly variable names relational operators loop structures much general programming capture information logic machine-readable semantics whereas older manual cnc programming could describe particular instances parts numeric form macro programming describes abstractions easily apply wide variety instances difference many analogues computing era advent 1 creating text bitmaps versus using character encoding glyphs 2 abstraction level tabulated engineering drawings many part dash numbers parametrically defined one drawing parameter table 3 way html passed phase using content markup presentation purposes matured toward css model cases higher layer abstraction introduced missing semantically step-nc reflects theme viewed yet another step along path started development machine tools jigs fixtures numerical control sought build skill tool recent developments g-code step-nc aim build information semantics tool idea new beginning numerical control concept end-to-end cad/cam environment goal early technologies dac-1 apt efforts fine huge corporations like gm boeing however small medium enterprises went era simpler implementations nc relatively primitive connect-the-dots g-code manual programming cad/cam improved disseminated throughout industry machine tool great number axes spindles tool stations difficult program well manually done years easily challenge existed decades cnc screw machine rotary transfer programming also arises today newer machining centers called turn-mills mill-turns multitasking machines multifunction machines cad/cam systems widely used cnc programming g-code requires cad/cam opposed manual programming practical competitive market segments classes machines serve smid says combine axes additional features amount knowledge required succeed quite overwhelming say least time however programmers still must thoroughly understand principles manual programming must think critically second-guess aspects software decisions since mid-2000s seems death manual programming writing lines g-code without cad/cam assistance may approaching however currently contexts manual programming obsolete plenty cam programming takes place nowadays among people rusty incapable manual programming—but true cnc programming done done well efficiently without knowing g-code tailoring refining cnc program machine area practice easier efficient edit g-code directly rather editing cam toolpaths re-post-processing program making living cutting parts computer-controlled machines made easier harder cad/cam software efficiently written g-code challenge cam software ideally cnc machinist know manual cam programming well benefits brute-force cam elegant hand programming used needed many older machines built limited computer memory time memory expensive 32k considered plenty room manual programs whereas modern cam software post gigabytes code cam excels getting program quick may take machine memory take longer run often makes quite valuable machining low quantity parts balance must struck time takes create program time program takes machine part become easier faster make parts newer machines lots memory taken toll hand programmers manual machinists given natural turnover retirement realistic expect maintain large pool operators highly skilled manual programming commercial environment mostly longer provide countless hours deep experience took build skill yet loss experience base appreciated times pool sorely missed cnc runs still optimized without skill list selection except key terms mostly avoids duplicating many abbreviations listed engineering drawing abbreviations symbols see
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Programming language topics
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macintosh common lisp macintosh common lisp mcl implementation ide common lisp programming language various versions mcl run classic mac os m68k ppc mac os x versions mcl including 5.1 proprietary version 5.2 open sourced 2009 new different version mcl open sourced rmcl rmcl based mcl 5.1 run rosetta intel-based macs mcl famous integration macintosh toolbox later apple carbon allowed direct access mac os functionality directly lisp achieved low-level interface allowed direct manipulation native mac os data structures lisp together high-level interface convenient use 2001 article dr. dobb journal peter norvig wrote mcl favorite ide macintosh platform language serious rival platforms development mcl began 1984 history mcl known different names running 68k-based apple macintosh computers running powerpc-based apple macintosh computers also spawned least one separately maintained fork
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Programming language topics
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dcc alliance dcc alliance dcca industry association designed promote common subset debian gnu/linux operating system multiple companies within consortium could distribute founded ian murdock 2005 wound 2007 main force behind dcc alliance ian murdock original founder debian project dcc alliance formed whilst murdock ceo progeny linux systems remained key spokesperson consortium visible existence founding dcc alliance announced linuxworld san francisco 9 august 2005 following number pre-announcements stated intention assemble standards-based core debian provide predictable release cycle linux standards base compliance dcc alliance shipped first code 6 months original pre-announcements providing linux standards base lsb 3.0 compliant set program packages based available debian alliance primary goals two classes membership dcc alliance membership remained open additional organizations interest debian-based solutions visible absent involvement ubuntu distribution declined join alliance ubuntu founder mark shuttleworth stated 2006 believe dcc alliance future one founding members mepis later left dcca citing creative differences mepis transitioned simplymepis linux distribution debian unstable/dcca-provided core ubuntu-based one 2006 ian murdock left dcc alliance chair linux standard base workgroup later moved employment sun microsystems 2007 progeny original driver behind consortium wound 2006 xandros still claiming xandros leads engineering team dcca originally formed names given media debian core consortium debian common core following trademark notification debian project name withdrawn replaced—without formal announcement—by dcc alliance ian murdock explained longer treated abbreviation debian dcc —becoming recursive acronym dcc common core notably debian trademark denied mr. murdock dcc alliance originates combination -ian part mr. murdock given name concatenated wife name debra murdock decision infringement trademark fell branden robinson debian project leader dpl employee progeny linux systems mr. murdock time decision made mr. robinson stated would represent conflict interest
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Operating systems
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ingenic semiconductor ingenic semiconductor chinese fabless semiconductor company based beijing china founded 2005 purchased licenses mips architecture instruction sets 2009 design cpu-microarchitectures based also design system chip products including cpus licensed semiconductor intellectual property blocks third parties vivante corporation commission fabrication integrated circuits semiconductor fabrication plants sell xburst cpu microarchitecture based upon mips32 revision 1 respectively mips32 revision 2 instruction set implements 8-stage pipeline xburst cpu technology consists 2 parts ingenic semiconductor purchased mips64 instruction set license designed microarchitecture based xburst2 xburst2 dual-issue/dual-threaded cpu design development basically completed first half 2014 announced summer 2013 socs incorporating xburst microarchitecture xburst1-based socs commonly used tablet computers portable media players digital photo frames gps devices jz4730 cpu used skytone alpha-400 variants jz4720 utilized copyleft hardware project ben nanonote another popular device dingoo gaming handheld uses jz4732 de facto jz4740 game gadget using jz4750 velocity micro t103 cruz t301 cruz 7-inch android 2.0 tablets used jz4760 jz4770 soc used several ainol novo 7 android tablets 3q tablet pc qoo ic0707a/4a40 jz4770 soc also used dedicated handheld neogeo-x open source handheld gcw zero running opendingux jz4780 used imgtec mips based single-board computer sbc creator ci20
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Computer architecture
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ian cullimore ian h. s. cullimore english-born mathematician computer scientist influential pocket pc arena cullimore degree mathematics king college london phd cognitive computer science university sussex original founder 1985 main inventor pocket pc became atari portfolio originally known dip pocket pc 1989 dip research ltd. acquired phoenix technologies 1994 1988 cullimore also one founders vice president software poqet computer corporation silicon valley developed poqet pc interest pdas sparked early times psion working first organiser products also original instigator pc card formerly pcmcia card movement came decision use then-emerging credit card memories design atari portfolio founding poqet major investment fujitsu decision made use 68-pin jeida card successfully persuaded board poqet set industry standards organization pcmcia promote standard cullimore wrote parts pcmcia driver stack netware palmdos 1.0 variant digital research dr dos tailored specifically battery powered mobile pcs 1992
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Computer architecture
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keepvault keepvault online backup service perform online local backups windows-based personal computers servers keepvault uses storage-based pricing model allows offer unlimited users devices one account keepvault technology uses end-to-end encryption files accessed computers via web keepvault first created proxure 2006 january 2012 proxure acquired authentec inc following authentec inc. ’ acquisition apple inc. keepvault acquired group original developers became independent company keepvault offers windows desktop application windows server add-in two plan types home professional well free local backup 2007 keepvault early oem vendor backup microsoft launched windows home server keepvault shipped hp data vault hp mediasmart servers starting 2013 keepvault dashboard add-in preinstalled western digital sentinel server series joint business community effort keepvault launched backup awareness week may 2014 “ backup week ” designed educate public risks data loss ways protect data 2008 bloggers complained end unlimited data plans since keepvault taken position unlimited plans unsustainable
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Computer security
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cambria typeface cambria transitional serif typeface commissioned microsoft distributed windows office designed dutch typeface designer jelle bosma 2004 input steve matteson robin nicholas intended serif font suitable body text readable printed small displayed low-resolution screen even spacing proportions part cleartype font collection suite fonts various designers released windows vista start letter c reflect designed work well microsoft cleartype text rendering system text rendering engine designed make text clearer read lcd monitors fonts group calibri candara consolas constantia corbel diagonal vertical hairlines serifs relatively strong horizontal serifs small intend emphasize stroke endings rather stand principle noticeable italics lowercase characters subdued style somewhat condensed average font kind profile bosma monotype website commented one defining features typeface contrast heavy vertical serifs hairlines – keep font sturdy ensures design preserved small sizes – relatively thin horizontals ensure typeface remains crisp used larger sizes bosma describes transitional slab-serif hybrid many aspects design somewhat blocky render well screen full stops square rather round designers recommended avoiding using printed text designer matthew butterick described monotonous attractive paper bosna compared optical sizes fonts designed printed small design bit like old metal type font days sizes drawing small sizes wider lower contrast compared large fonts design optical correction sense cambria like small size font except may also used large sizes cleartype fonts lining figures text figures offered lining figures default shown sample image variant designed mathematical scientific texts replacement times new roman cambria math first font implement opentype math extension inspired tex led jelle bosma agfa monotype ross mills tiro typeworks project planned development cambria started cambria math developed three stages cambria distributed windows versions since windows vista microsoft office versions since microsoft office 2007 windows microsoft office 2008 mac microsoft office 2007 viewers converters cambria regular cambria math packaged together truetype collection ttc file microsoft office 2008 mac include cambria math omml supported therefore macintosh version cambria packaged individual truetype font ttf files rather single ttc file font along calibri candara consolas corbel constantia also distributed microsoft excel viewer microsoft powerpoint viewer microsoft office compatibility pack microsoft windows open xml file format converter mac use operating systems gnu/linux cross-platform use web use available freeware typeface licensed ascender corporation use end users consumer electronics device manufacturers typeface also licensed monotype imaging printer manufacturers part vista 8 font set package 2013 part chrome google released freely-licensed font called caladea metric-compatible cambria i.e replace document without changing layout based cambo font developed argentine type foundry huerta tipográfica despite metric-compatible caladea covers much smaller language range e.g n't support cyrillic greek advanced typographic features like ligatures old style numerals fractions cambria math used presentation office mathml equations microsoft office 2007 later free typesetting systems xetex luatex make direct use cambria math alternative traditional tex mathematical fonts cambria available use google google drive suite web applications
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Operating systems
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differential fault analysis differential fault analysis dfa type side channel attack field cryptography specifically cryptanalysis principle induce faults —unexpected environmental conditions—into cryptographic implementations reveal internal states example smartcard containing embedded processor might subjected high temperature unsupported supply voltage current excessively high overclocking strong electric magnetic fields even ionizing radiation influence operation processor processor may begin output incorrect results due physical data corruption may help cryptanalyst deduce instructions processor running internal data state des triple des 200 single-flipped bits necessary obtain secret key dfa also applied successfully aes cipher many countermeasures proposed defend kind attacks based error detection schemes
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Computer security
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commwarrior commwarrior symbian bluetooth worm first spread via multimedia messaging service mms bluetooth worm affects nokia series 60 software platform commwarrior particularly effective via mms vector used infect phones appeared though sent source known victim leading even security-conscious users open infected message actually message sent random contact sender address book message opened virus attempts install phone via sis file runs worm executed every time phone switched secondary method infection create malicious .sis file compromised phone per minute thereafter worm attempts send file phone bluetooth enabled according sophos installation program one six chance displaying following text commwarrior v1.0 c 2005 e10d0r
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Computer security
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calibri calibri sans-serif typeface family designed luc de groot 2002–2004 released general public 2007 microsoft office 2007 windows vista office 2007 replaced times new roman default typeface word replaced arial default powerpoint excel outlook wordpad de groot described subtly rounded design warm soft character calibri part cleartype font collection suite fonts various designers released windows vista start letter c reflect designed work well microsoft cleartype text rendering system text rendering engine designed make text clearer read liquid-crystal display monitors fonts group cambria candara consolas constantia corbel calibri features subtly rounded stems corners visible larger sizes sloped form true italic handwriting influences common modern sans-serif typefaces typeface includes characters latin latin extended greek cyrillic scripts calibri makes extensive use sophisticated opentype formatting features range ligatures well lining text figures indices numbers enclosed circles 20 alternate f g accessible enabling fourth fifth stylistic sets features calibri remain unsupported office including true small caps all-caps spacing superscript subscript glyphs ability create arbitrary fractions may accessed using programs adobe indesign one potential source confusion calibri visible homoglyph pair easily confused characters lowercase letter l uppercase letter l latin script effectively indistinguishable true many common fonts however design clear similarities de groot famous much extensive commercial family thesans although straight ends rather rounding calibri default typeface microsoft office much microsoft software joe friend program manager word office 2007 release explained decision switch calibri caused desire make default font one optimised towards onscreen display believed documents would never printed would solely consumed digital device achieve modern look long development windows vista calibri development – 2002 2004 – occurred several years release os first presented 2004 beta windows vista codenamed longhorn first became available use beta 2 version office 2007 released may 23 2006 calibri rest cleartype font collection finally released general public january 30 2007 since released microsoft software environments calibri also distributed microsoft excel viewer microsoft powerpoint viewer microsoft office compatibility pack microsoft windows open xml file format converter mac use operating systems cross-platform web use calibri licensed ascender corporation parent company monotype imaging font calibri light introduced microsoft windows 8 added windows 7 server 2008 part software update microsoft word 2013 onwards calibri calibri light default fonts body text headings respectively calibri light also default font headings powerpoint 2013 due calibri widespread use microsoft office documents google released freely-licensed font called carlito metric-compatible calibri part chromeos carlito font metrics calibri chromeos users correctly display print document designed calibri without disrupting layout carlito based prior open-source typeface lato without de groot involvement calibri tdc2 2005 award type directors club type system category calibri position default font office many cases reported documents shown forged thanks purported creation date calibri available general public 2017 font came public attention evidence pakistani government-related panama papers case also known fontgate document supposedly signed february 2006 found typed calibri. ref name= thenextweb/11july2017 /ref de groot said really zero chance document genuine
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Operating systems
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jun'ichi tsujii tsujii received bachelor engineering master engineering ph.d degrees electrical engineering kyoto university 1971 1973 1978 respectively assistant professor associate professor kyoto university accepting position professor computational linguistics university manchester institute science technology umist 1988 president association computational linguistics acl 2006 permanent member international committee computational linguistics iccl since 1992 since may 2015 tsujii director artificial intelligence research center national institute advanced industrial science technology japan tsujii previously principal researcher microsoft research asia msra joining msra professor university tokyo belonged school inter-faculty initiative informatics graduate school information science technology tsujii also visiting professor scientific advisor national centre text mining nactem university manchester united kingdom 14 may 2010 tsujii awarded medals honor purple ribbon one japan highest awards presented influential contributors fields art academics sports september 2014 tsujii awarded funai achievement award forum information technology fit took place university tsukuba award presented distinguished individuals engaged research related business activities field information technology produced excellent achievements field still active leading positions strong impact young students researchers december 2014 tsujii named acl fellow recognition significant contributions mt parsing unification-based grammar text mining biology
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Computational linguistics
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nokia 5250 nokia 5250 budget nokia resistive touchscreen smartphone running symbian v9.4 operating system s60 5th edition user interface price tax subsidies €115 announced august 2010 available china eurasia europe india latin america middle east south east asia pacific region small compact comes preloaded guitar hero mobile series 5 cnet asia praised resolution budget price criticized lack 3g capabilities relying gsm edge
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Operating systems
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operation payback operation payback coordinated decentralized group attacks high-profile opponents internet piracy internet activists using anonymous moniker operation payback started retaliation distributed denial service ddos attacks torrent sites piracy proponents decided launch ddos attacks piracy opponents initial reaction snowballed wave attacks major pro-copyright anti-piracy organizations law firms individuals following united states diplomatic cables leak december 2010 organizers commenced ddos attacks websites banks withdrawn banking facilities wikileaks 2010 several bollywood companies hired aiplex software launch ddos attacks websites respond takedown notices piracy activists created operation payback september 2010 retaliation original plan attack aiplex software directly upon finding hours planned ddos another individual taken firm website operation payback moved launching attacks websites copyright stringent organisations motion picture association america mpaa international federation phonographic industry giving two websites combined total downtime 30 hours following two days operation payback attacked multitude sites affiliated mpaa recording industry association america riaa british phonographic industry law firms davenport lyons dunlap grubb weaver us copyright group also attacked september 21 2010 website united kingdom law firm subjected ddos attack part operation payback asked attacks andrew crossley owner acs law said hours far concern fact train turning 10 minutes late queue coffee wasting time sort rubbish site came back online 350mb file backup site visible anyone short period time backup included copies emails sent firm downloaded made available various peer-to-peer networks websites including pirate bay emails contained unencrypted excel spreadsheets listing names addresses people acs law accused illegally sharing media one contained 5,300 sky broadband customers accused illegally sharing pornography another contained details 8,000 sky customers 400 plusnet customers accused infringing copyright music sharing peer-to-peer networks alleged breach data protection act become part ongoing investigation acs law information commissioner office september 30 leesburg virginia office dunlap grubb weaver law firm – also business u.s copyright group – evacuated police emailed bomb threat received believed event could connected anonymous non-related copyright law firms sites websheriff.com also attacked attacks originally organized internet relay chat channel attacks also became popular topic twitter september 27 2010 ddos attack australian federation copyright theft afact unintentionally brought 8,000 small websites hosted server september 2010 attempt ensure portuguese citizens ca n't access thepiratebay.org associação comércio audiovisual de portugal acapor filed complaint pirate bay complaint filed general inspection cultural activities part portuguese ministry culture according movie rental association pirate bay directly responsible 15 million illegal downloads portugal every year installing pirate bay block isps acapor hoped decrease financial damage claims pirate bay causes october 18 2010 acapor website defaced presenting text operation payback redirect pirate bay seconds addition defacing website copy email database acapor uploaded pirate bay leaked e-mails far revealed acapor methods denunciation dissatisfaction portuguese government justice system perception copyright debate war antagonism isps acapor claimed business isps illegal downloading october 4 2010 operation payback launched attack ministry sound website gallant macmillan website october 7 2010 attacked website spanish copyright society sgae.es october 7 2010 total downtime websites attacked operation payback 537.55 hours october 15 2010 copyprotected.com sql injected defaced three days later operation payback launched ddos attack uk intellectual property office production companies satelfilm.at wega-film.at hit drive-by ddoses october 21 2010 response efforts gain court injunction isp refused block movie-streaming website operation payback knocked porn website hustler.com offline following day 2010 mipcom convention gene simmons kiss stated response simmons comments members operation payback switched attentions two websites simmonsrecords.com genesimmons.com taking offline total 38 hours point course ddos genesimmons.com hacked redirected thepiratebay.org response attack simmons wrote led additional attacks subsequently downtime websites later simmons message removed website one year later december 2011 person supposedly known nickname spydr101 arrested relation attack genesimmons.com charged conspiracy unauthorized impairment protected computer october 26 2010 limewire ordered disable searching downloading uploading file trading and/or file distribution functionality losing court battle riaa claims copyright infringement satisfied injunction riaa announced intention continue arista records llc v. lime group llc trial recover damages caused program retaliation members operation payback announced would attack riaa website october 29 despite fact group typically hit target twice october 29 riaa.org indeed taken offline via denial-of-service attack attack riaa.com riaa.org sites inaccessible europe operation payback main site attacked later day subsequently moved website tieve.tk anonops.net damages phase limewire trial riaa attempted switch seeking statutory damages per-work seeking per-infringement quote total damage amount method calculating number infringements judge case rejected proposal holding case law supported statutory damages per-work basis large-scale infringement thus capping potential award 1.5 billion march 15 2011 four days ruling report appeared law.com highlighting judge remark per-infringement award sought record companies might total trillions report estimated 75 trillion attention-grabbing headline usa nominal gdp 2012-2013 16–17 trillion figure repeated pc magazine march 23 operation payback call-to-arms followed citing 75 trillion figure still actively sought riaa ddos attack riaa website commenced march 25 around october 28 2010 group set new website intention coordinating protests around world raise awareness cause date protest activities november 5 intended day gunpowder plot anonymous heavily affiliates use guy fawkes masks protest activity included attack united states copyright office fbi launched investigation later arrested one person accused taking part attack paypal november 9 2010 operation payback temporarily ceased attacking websites hiatus lasted four months ending early march 2011 attack temporarily took website bmi prominent collection society operating behalf music publishers followed aforementioned second attack riaa website december 8 2010 u.s politician sarah palin announced website personal credit card information compromised palin team believed attack executed anonymous though anonymous never commented palin possible target attack interview rt anonymous member said n't really care sarah palin much honest n't really know trying accomplish attention trying gain personally n't care sarah palin palin technical team posted screenshot server log file showing wikileaks.org url visa attacks denial service attacks credit card data compromised unknown whether palin card compromised part broad attack visa specific attack palins palin email previously hacked campaigning 2008 u.s. presidential election december 2010 wikileaks came intense pressure stop publishing secret u.s. diplomatic cables corporations amazon paypal bankamerica swiss bank postfinance mastercard visa either stopped working froze customers donations wikileaks due political pressures response behind operation payback directed activities companies operation payback launched ddos attacks paypal postfinance swedish prosecution authority december 8 2010 coordinated ddos attack operation payback brought mastercard visa websites december 9 2010 prior sustained ddos attack paypal website caused minor slowdown service paypal announced blog would release frozen funds account wau holland foundation raising funds wikileaks would reactivate account regarding attacks wikileaks spokesman kristinn hrafnsson denied relation group said neither condemn applaud attacks believe reflection public opinion actions targets day 16-year-old boy arrested hague netherlands connection distributed denial-of-service attacks mastercard paypal boy irc operator nickname jeroenz0r december 10 2010 daily telegraph reported anonymous threatened disrupt british government websites assange extradited sweden anonymous issued press release attempt clarify issue electronic frontier foundation co-founder john perry barlow described attacks shot heard round world—this lexington following list sites domains known targeted operation payback attempt take amazon.com aborted failed recruit enough users botnet cnn noted massive amazon website almost impossible crash late december fbi began raid suspected participants operation payback beginning 2011 operation payback brought zimbabwean government websites zimbabwean president wife sued newspaper 15 million publishing wikileaks cable linked alleged trade illicit diamonds january 27 2011 five males aged 15 26 arrested early morning raids u.k. suspicion involvement fbi executed 40 search warrants day united kingdom intellectual property office said site attacked responsible depriving citizens access information democratic right access critics claimed attacks restricted gene simmons right free speech spokesman mpaa said troubling groups seem concerned rights steal copy films music books creative resources rights american workers producing products also criticism pirate party uk united states pirate party joint public statement urged group immediately cease distributed denial-of-service ddos attacks instead seek legal method express frustration disquiet copyright industry perversions copyright law personal gain acknowledging ddos attacks credit card banking web sites serve political protests cyber experts said operation payback done long-term damage sites back online attacks penetrated brought entire banking systems used conduct transactions people still continuing use credit cards make payments like noisy political demonstration like mob surrounding bank refusing let anyone said one cyber expert operation payback members used modified version low orbit ion cannon loic execute ddos attacks september 2010 hive mind mode added loic hive mind mode loic connects irc controlled remotely allows computers loic installed behave part botnet utilising tool coordinators operation payback able quickly take websites belonging anti-piracy groups botnets sizes also used members operation payback reportedly used irc channel communicate targets select instructions attacking targets produced posted various imageboards 4chan/7chan/711chan/420chan/808chan media twitter facebook also utilized coordination december 8 2010 operation payback facebook page removed official twitter account suspended additionally federal court order forced encyclopedia dramatica delete operation payback article featured detailed history operation including personal information individuals associated companies attacked october 2013 13 members operation payback indicted federal court alexandria virginia co-conspirators violation 18 u.s.c § 731 18 u.s.c § 1030 2014 members received plea deal reducing felony charges single misdemeanor
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Computer security
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lennart augustsson lennart augustsson swedish computer scientist previously lecturer computing science department chalmers university technology research field functional programming implementations functional languages augustsson worked carlstedt research technology sandburst credit suisse standard chartered bank facebook currently employed x company augustsson author also co-developer thomas johnsson lazy ml functional programming language developed early 1980s prior miranda haskell lml strongly typed statically scoped implementation ml lazy evaluation key innovation lml demonstrate compile lazy functional language lazy languages implemented via interpreted graph reduction lml compiled g-machine code augustsson intimately involved early lpmud development lpmud driver cd mudlib mud community pseudonym marvin augustsson written three winning entries international obfuscated c code contest
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Programming language topics
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tabular data stream tabular data stream tds application layer protocol used transfer data database server client initially designed developed sybase inc. sybase sql server relational database engine 1984 later microsoft microsoft sql server early development sybase sql server developers sybase perceived lack commonly accepted application-level protocol transfer data database server client order encourage use products sybase promoted use flexible pair libraries called codice_1 codice_2 implement standard sql library included order implement bulk copy called blk codice_1 job ferry data two computers underlying network protocol codice_2 provides api client program communicates server via codice_1 codice_2 sends server structured stream bytes meant tables data hence tabular data stream codice_7 provides like codice_2 api client programs communicates server via codice_1 1990 sybase entered technology-sharing agreement microsoft resulted microsoft marketing sql server — microsoft sql server — based sybase code microsoft kept codice_2 api added odbc microsoft since added additional apis time sybase introduced powerful successor codice_2 called codice_12 called pair open client codice_2 though officially deprecated remains widespread use tds protocol comes several varieties openly documented regarded proprietary technology exception tds 5.0 used exclusively sybase documentation available sybase situation changed microsoft published tds specification 2008 part open specification promise freetds team developed free native-library implementation tds protocol licensed lgpl license wireshark protocol decoder tds oracle corporation provides oracle net software analogous tds
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Internet protocols
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family basic family basic famicom basic consumer product programming nintendo family computer video game console japan family basic launched june 21 1984 consumers japan nintendo cooperation hudson soft sharp corporation second version titled family basic v3 released february 21 1985 greater memory new features first edition family basic application cartridge bundled computer style keyboard instructional textbook requires cassette tape recorder save user-generated basic programs programs saved using cassette tape drive famicom data recorder family basic designed compatible floppy disk storage famicom disk system disk system ram adapter requires use famicom cartridge slot prevents using slot family basic cartridge family basic includes dialect basic programming language enhanced game development microsoft basic-derived command set extended support sprites animation backgrounds musical sequences gamepads several visual components seen nintendo games backgrounds characters mario donkey kong series games made available family basic development componentry appear premade family basic games family basic normally used nes consoles console lacks famicom 15-pin expansion port circumvented use custom i/o adapter hooks otherwise unused nes expansion port bottom console 1990 manufacturer shenzhen named nedc developed sold clone famicom family basic china first model called fcs-90 combines famicom chipset cartridge slot pair controllers rf output making complete console used program play famicom video games nedc also translated built-in software english fcs-90 revised model fcs-92 instruction manual section programming japanese popular music family basic developed koji kondo second nintendo product tenure kondo previously initiated computer audio interests programming sounds basic home computer satoshi tajiri creator pokémon initially used family basic gateway build understanding internal operation famicom inspired create handmade famicom game development hardware make game freak debut game quinty later released mendel palace 1990
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Programming language topics
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object-oriented user interface computing object-oriented user interface ooui type user interface based object-oriented programming metaphor ooui user interacts explicitly objects represent entities domain application concerned many vector drawing applications example ooui – objects lines circles canvases user may explicitly select object alter properties size colour invoke actions upon move copy re-align business application ooui user may selecting and/or invoking actions objects representing entities business domain customers products orders jakob nielsen defines ooui contrast function-oriented interfaces object-oriented interfaces sometimes described turning application inside-out compared function-oriented interfaces main focus interaction changes become users data information objects typically represented graphically screen icons windows dave collins defines ooui demonstrating three characteristics jef raskin suggests important characteristic ooui adopts 'noun-verb rather 'verb-noun style interaction several advantages terms usability great deal potential synergy ooui concept important ideas user interface design including many futuristic imaginings user interfaces rely heavily ooui especially oogui concepts however many examples user interfaces implement one ideas fact oouis though often wrongly labelled oouis conversely examples oouis neither graphical employ direct manipulation techniques employ strong metaphors example earliest versions smalltalk programming language command line interface nonetheless also clearly ooui though subsequently became better known pioneering role development guis direct manipulation visual metaphors although many conceptual parallels oouis object-oriented programming follow ooui implemented using object-oriented programming language guidelines ibm common user access cua possibly comprehensive attempt defining standard ooui design stated 'while object-oriented programming facilitate development object-oriented user interface pre-requisite object-oriented user interface developed traditional programming languages tools however strong synergies larry tesler left xerox parc 1980 join apple underlined relationship also obvious synergy concept ooui idea constructing software domain objects however follow objects user sees interacts within ooui correspond domain objects application built cua guidelines stated 'in object-oriented user interface objects user works necessarily correspond objects modules code programmer used create product basic design methods described cua refined ovid method used uml model interface mark van harmelen states 'object-oriented user interface design require designers take object-oriented view problem beginning project furthermore even designers take object-oriented perspective throughout benefit focusing separately object model object-oriented user interface design contrast naked objects pattern approach design applications least naive form enforces direct correspondence objects represented ooui underlying domain objects auto-generating former latter
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Operating systems
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candara candara humanist sans-serif typeface designed gary munch commissioned microsoft part cleartype font collection suite fonts various designers released windows vista starting letter c reflect designed work well microsoft cleartype text rendering system others calibri cambria consolas corbel constantia candara ’ verticals show entasis ekstasis opposite sides stems high-branching arcades lowercase large apertures open forms unique ogee curves diagonals italic includes many calligraphic serif font influences common modern sans-serif typefaces calibri corbel family similar designs spacing family supports wgl4 character set opentype features include automatic ligature sets numerals tabular proportional oldstyle lining numerator denominator scientific inferior subscripts small caps also distributed microsoft excel viewer microsoft powerpoint viewer microsoft office compatibility pack microsoft windows open xml file format converter mac available freeware use operating systems gnu/linux cross-platform use web use
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Operating systems
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apple a5 apple a5 32-bit system-on-a-chip designed apple inc. manufactured samsung successor apple a4 a5 commercially debuted release apple ipad 2 tablet also powers iphone 4s ipod touch fifth generation apple tv third generation ipad mini first generation consistent apple debuted a4 chip first original ipad followed iphone 4 ipod touch fourth generation apple claims compared predecessor a4 a5 cpu twice work gpu nine times graphics performance software updates devices using chip ceased 2016 release ios 10 a5 consists dual-core arm cortex-a9 cpu neon simd accelerator dual core powervr sgx543mp2 gpu apple lists a5 clocked 1 ghz ipad 2 technical specifications page though dynamically adjust frequency save battery life unit used iphone 4s clocked approximately 800 mhz apple also included image signal processor unit isp advanced image post-processing face detection white balance automatic image stabilization earsmart unit audience noise canceling a5 first released estimated time cost 75 previous generation difference expected diminish production increased a5 manufactured samsung austin texas factory samsung invested 3.6 billion austin facility produce chips processors nearly facility output dedicated apple components samsung invested 4.2 billion austin facility order transition 28 nm fabrication process second half 2013 a5 part model numbers s5l8940 45 nm version s5l8942 32 nm version s5l8947 32 nm single core version version a5 wider memory subsystem four graphic cores called apple a5x found third generation ipad apple uses first version a5 chip iphone 4s ipad 2 a5 manufacturing process 45 nm 122.2 mm die area manufactured package package pop together 512 mb dual-channel lp-ddr2 dram apple used second version a5 chip third generation apple tv announced march 7 2012 well ipod touch fifth generation ipad mini 32 nm revision ipad 2 chip manufactured 32 nm fabrication process id code s5l8942 one core disabled apple tv new a5 measures nearly 41 smaller first-generation a5 coming 69.6 mm manufactured package package pop together 512 mb lpddr2 dram march 2013 apple released updated version third generation apple tv appletv3,2 containing smaller single cpu core single gpu core version a5 processor unlike a5 variants version a5 package-on-package pop stacked ram chip small 37.8 mm decrease size due decrease feature size still 32 nm fabrication process indicates a5 revision new design markings tell named apl7498 software chip called s5l8947 images illustrations approximately scale
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Computer architecture
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john ripper john ripper free password cracking software tool initially developed unix operating system runs fifteen different platforms eleven architecture-specific versions unix dos win32 beos openvms one popular password testing breaking programs combines number password crackers one package autodetects password hash types includes customizable cracker run various encrypted password formats including several crypt password hash types commonly found various unix versions based des md5 blowfish kerberos afs windows nt/2000/xp/2003 lm hash additional modules extended ability include md4-based password hashes passwords stored ldap mysql others sample output debian environment first line command expand data stored file codice_1 next line contents file i.e user codice_2 hash associated user codice_3 third line command running john ripper utilizing codice_4 flag codice_5 name text file full words program use hash codice_1 makes another appearance file want john work see output john working loaded 1 password hash — one saw cat command — type hash john thinks traditional des also see attempt required one guess time 0 100 guess rate one modes john use dictionary attack takes text string samples usually file called wordlist containing words found dictionary real passwords cracked encrypting format password examined including encryption algorithm key comparing output encrypted string also perform variety alterations dictionary words try many alterations also used john single attack mode modifies associated plaintext username encrypted password checks variations hashes john also offers brute force mode type attack program goes possible plaintexts hashing one comparing input hash john uses character frequency tables try plaintexts containing frequently used characters first method useful cracking passwords appear dictionary wordlists takes long time run
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Computer security
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consolas consolas monospaced typeface designed luc de groot part suite fonts take advantage microsoft cleartype font rendering technology included windows since windows vista microsoft office 2007 microsoft visual studio 2010 available download microsoft standard windows vista font slash zero character consolas supports following opentype layout features stylistic alternates localized forms uppercase-sensitive forms oldstyle figures lining figures arbitrary fractions superscript subscript although consolas designed replacement courier new 713 glyphs initially available compared courier new 2.90 1318 glyphs version 5.22 included windows 7 support greek extended combining diacritical marks symbols number forms arrows box drawing geometric shapes added version 5.32 total number supported glyphs 2735 font along calibri cambria candara corbel constantia also distributed microsoft excel viewer microsoft powerpoint viewer microsoft office compatibility pack microsoft windows open xml file format converter mac consolas also available licensing ascender corporation bare bones software licensed font ascender use text editor bbedit inconsolata open source alternative available google fonts
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Operating systems
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tradegecko tradegecko singapore based software-as-a-service company develops online inventory order management software targeted smes company recognised one innovative business-to-business software providers red herring asia 100 tradegecko launched 2013 carl thompson brothers cameron bradley priest three new zealanders thompson ran label crowded elevator saw need solution managing inventory administration made decision create one “ running clothing label exciting enjoyed lot grew fast amount administration quickly overwhelmed us ’ find solution pull together spreadsheets manual data processing turned absolute nightmare said trio went jfdi.asia accelerate program going raise round financing singapore-based investors april 2015 tradegecko raised 6.5 million series round led nsi ventures jungle ventures tradegecko provides inventory management platform targeted wholesalers online retailers system also integrates cloud based software shopify e-commerce woocommerce e-commerce xero accounting software designed help businesses manage sales supply chains inventory control customer supplier tracking intelligence reports customers able generate sales purchase orders create reports track inventory multiple warehouses tradegecko also released mobile tablet apps system
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Distributed computing architecture
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capicom capicom discontinued activex control created microsoft help expose select set microsoft cryptographic application programming interface cryptoapi functions microsoft component object model com intended enable every environment supports activex use microsoft cryptographic technologies including web pages opened microsoft internet explorer web browser supports activex capicom used digitally sign data inspect verify display digital signature digital certificate add remove certificates certificate stores finally encrypt decrypt data capicom version 2.1.0.3 latest last version capicom officially supported windows vista however microsoft announced capicom discontinued longer developed microsoft suggests replacing capicom .net framework x509 cryptographic classes number alternatives capicom included windows 7 linked microsoft article goes detail
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Operating systems
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berkeley risc berkeley risc one two seminal research projects risc-based microprocessor design taking place arpa vlsi project risc led david patterson coined term risc university california berkeley 1980 1984 project took place short drive away stanford university mips effort starting 1981 running 1984 berkeley project successful became name similar designs follow even mips would become known risc processor berkeley risc design later commercialized sun microsystems sparc architecture inspired arm architecture risc mips developed realization vast majority programs use vast majority processor instructions one calculation found entire unix system compiled used 30 available instructions motorola 68000 much circuitry cpu dedicated decoding instructions never used risc idea include instructions really used using space used removed circuitry circuits would speed system instead risc concentrated adding many registers small bits memory holding temporary values accessed negligible cost contrasts normal main memory might take several cycles access providing registers making sure compilers actually used programs run much faster additionally speed processor would closely defined clock speed less time would spent waiting memory accesses transistor transistor risc design would outperform conventional cpu hopefully lot downside instructions removed generally performing several sub-instructions instance codice_1 instruction traditional design would generally come several flavours one added numbers two registers placed third another added numbers found main memory put result register etc risc designs hand included single flavour particular instruction codice_1 instance would always use registers operands forced programmer write additional instructions load values memory needed making risc program less dense era expensive memory real concern notably memory also much slower cpu since risc design codice_1 would actually require four instructions two loads add save machine would much memory access read extra instructions potentially slowing considerably offset degree fact new designs used large instruction word 32-bits allowing small constants folded directly instruction instead loaded separately additionally results one operation often used soon another skipping write memory storing result register program end much larger could theory run much faster instance string instructions carrying series mathematical operations might require loads memory majority numbers used would either constants instructions intermediate values registers sense technique registers used shadow memory locations registers used proxies memory locations final values group instructions determined casual observer clear risc concept would improve performance might even make worse way sure actually simulate done results definite test test every simulation showed enormous overall benefit performance design two projects risc mips differed handling registers mips simply added lots left compilers assembly-language programmers make use risc hand added circuitry cpu help compiler risc used concept register windows entire register file broken blocks allowing compiler see one block global variables another local variables idea make one particularly common instruction procedure call extremely easy implement compilers almost computer languages use system known activation record stack frame procedure—a modular unit execution—that contains address procedure called data parameters passed space result values need returned vast majority cases frames small typically three fewer inputs one outputs sometimes input reused output berkeley design register window set several registers enough entire procedure stack frame would likely fit entirely within register window case call return procedure simple extremely fast single instruction called set new block registers—a new register window—and operands passed procedure low end new window program jumps procedure return results placed window end procedure exits register windows set overlap ends results call simply appear window caller data copied thus common procedure call interact main memory greatly accelerating downside approach means procedures large numbers local variables problematic ones fewer lead registers—an expensive resource—being wasted finite number register windows design e.g eight procedures nested many levels deep register windowing mechanism reaches limit last window reached new window set another nested call procedures nested levels deep registers windows deepest call nesting level never accessed completely wasted stanford work compilers led ignore register window concept believing efficient compiler could make better use registers fixed system hardware reasoning would apply smart assembly-language programmer first attempt implement risc concept originally known gold work design started 1980 part vlsi design course then-complicated design crashed almost existing design tools team spend considerable amounts time improving re-writing tools even new tools took hour extract design vax-11/780 final design known risc published acm isca 1981 44,500 transistors implementing 31 instructions register file containing 78 32-bit registers allowed six register windows containing 14 registers additional 18 globals control instruction decode section occupied 6 die whereas typical design era used 50 role register file took space risc also featured two-stage instruction pipeline additional speed without complex instruction re-ordering modern designs makes conditional branches problem compiler fill instruction following conditional branch so-called branch delay slot something selected safe i.e. dependent outcome conditional sometimes suitable instruction case codice_4 notable number later risc-style designs still require consideration branch delay month validation debugging design sent innovative mosis service production june 22 1981 using 2 μm 2,000 nm process variety delays forced abandon masks four separate times wafers working examples arrive back berkeley may 1982 first working risc computer actually checkout board ran june 11 testing chips proved lesser performance expected general instruction would take 2 μs complete original design allotted .4 µs five times fast precise reasons problem never fully explained however throughout testing clear certain instructions run expected speed suggesting problem physical logical design worked full speed performance would excellent simulations using variety small programs compared 4 mhz risc 5 mhz 32-bit vax 11/780 5 mhz 16-bit zilog z8000 showed clearly program size 30 larger vax close z8000 validating argument higher code density cisc designs actually impressive reality terms overall performance risc twice fast vax four times z8000 programs ended performing overall amount memory access large register file dramatically improved odds needed operand already on-chip important put performance context even though risc design run slower vax made difference importance design risc allowed production true 32-bit processor real chip die using already older fab traditional designs simply could much chip surface dedicated decoder logic true 32-bit design like motorola 68020 required newer fabs becoming practical using fabs risc could largely outperformed competition february 12 2015 ieee installed plaque uc berkeley commemorate contribution risc-i plaque reads risc design ran delays work berkeley already turned new blue design work blue progressed slower gold due lack pressing need gold going fab well changeovers classes students staffing effort pace also allowed add several new features would end improving design considerably key difference simpler cache circuitry eliminated one line per bit three two dramatically shrinking register file size change also required much tighter bus timing small price pay order meet needs several parts design sped well savings due new design tremendous whereas gold contained total 78 registers 6 windows blue contained 138 registers broken 8 windows 16 registers another 10 globals expansion register file increases chance given procedure fit local storage registers well increasing nesting depth nevertheless larger register file required fewer transistors final blue design fabbed risc ii implemented risc instruction set 39,000 transistors major change include instruction-format expander invisibly up-converted 16-bit instructions 32-bit format allowed smaller instructions typically things one operands like codice_4 stored memory smaller 16-bit format two instructions packed single machine word instructions would invisibly expanded back 32-bit versions reached alu meaning changes needed core logic simple technique yielded surprising 30 improvement code density making otherwise identical program blue run faster gold due decreased number memory accesses risc ii proved much successful silicon testing outperformed almost minicomputers almost tasks instance performance ranged 85 vax speed 256 variety loads risc ii also benched famous motorola 68000 considered best commercial chip implementation outperformed 140 420 work original risc designs ended risc ii concept lived berkeley basic core re-used soar 1984 basically risc converted run smalltalk way could claimed risc ran c later similar vlsi-bam ran prolog instead smalltalk another effort spur full set chips needed build complete 32-bit workstation risc less famous influential basis commercial sparc processor design sun microsystems sparc first clearly demonstrated power risc concept shipped first sun-4s outperformed anything market led virtually every unix vendor hurrying risc design leading designs like dec alpha pa-risc sgi purchased mips computer systems 1986 large chip vendors followed working efforts like motorola 88000 fairchild clipper amd 29000 powerpc february 13 2015 ieee installed plaque oracle corporation santa clara reads techniques developed alongside idea reduced instruction set also adopted successively powerful implementations extensions traditional complex x86 architecture much modern microprocessor transistor count devoted large caches many pipeline stages superscalar instruction dispatch branch prediction modern techniques applicable regardless instruction architecture amount silicon dedicated instruction decoding modern x86 implementation proportionately quite small distinction complex risc processor implementations become blurred
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Computer architecture
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suse studio imagewriter suse studio imagewriter official tool designed create live usbs suse opensuse part suse kiwi image creation system designed ease creation liveusb system suse studio however used standard opensuse livecd iso files
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Operating systems
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constantia typeface constantia serif typeface designed john hudson commissioned microsoft transitional serif design influenced eric gill ’ perpetua design development typeface began 2003 released 2006 constantia part cleartype font collection suite fonts various designers released windows vista start letter c reflect designed work well microsoft ’ cleartype text rendering system text rendering engine designed make text clearer read lcd monitors fonts suite calibri cambria candara consolas corbel constantia designed either print on-screen uses numerals text figures default seen sample image font also includes lining figures alternate style reviewing website typographica raph levien described likely “ everyone ’ favourite face suite ... highly readable roman font departing slightly classical model still manages fresh new takes inspiration perpetua ... triangular serifs bring mind chisel font enough calligraphic flavor recall palatino. ” among features design includes small capitals alternative spacing punctuation caps text numbers enclosed circles superscript subscript glyphs transitional serif design design features moderate contrast thick thin strokes nearly-vertical axis render well cleartype letters q slightly squared-off distributed microsoft excel viewer microsoft powerpoint viewer microsoft office compatibility pack microsoft windows open xml file format converter mac use operating systems gnu/linux cross-platform use web use available freeware explaining name hudson wrote “ ’ remember possible names came ended rejected international trademark searches ... ’ singing psalms vespers noticed word constantia hey thought starts c ” writing 2011 hudson commented “ actually ’ like name constantia much every time see sea birds dock ’ waiting ferry wish ’ thought call cormorant ”
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Operating systems
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boxee box boxee box d-link officially d-link boxee box dsm-380 linux-based set-top device media extender first began shipping 33 countries worldwide 10 november 2010 designed easily bring internet television video television via boxee software comes pre-installed boxee media center software hardware based intel ce4110 system-on-a-chip platform intel atom cpu powervr sgx535 integrated graphics processor ram nand flash memory dm-380 features hdmi port version 1.3 optical digital audio s/pdif rca connector analog stereo audio two usb ports sd card slot wired 100base-t ethernet built-in 2.4 ghz 802.11n wifi live tv dongle started shipping february 2012 enables users watch digital ota clear qam cable television channels epg boxee box also ships small two-sided rf remote control four-way d-pad navigation full qwerty keypad standard remote also sold separately usb receiver d-link boxee box remote dsm-22 used boxee installed computer one use remote without owning d-link boxee box look case remote prototypes boxee box designed san francisco-based astro studios designer xbox 360 microsoft zune 16 october 2012 boxee team announced intend discontinue distribution releasing additional major updates
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Operating systems
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corbel typeface corbel humanist sans-serif typeface designed jeremy tankard microsoft released 2005 part cleartype font collection suite fonts various designers released windows vista start letter c reflect designed work well microsoft cleartype text rendering system text rendering engine designed make text clearer read lcd monitors fonts group calibri cambria candara consolas constantia blurb use corbel described designed give uncluttered clean appearance screen letter forms open soft flowing curves legible clear small sizes larger sizes detailing style shapes apparent italic style true italic influences serif fonts calligraphy many letters gaining tail pointing right many aspects design similar calibri candara also humanist sans-serif designs like slightly condensed average font designer raph levien reviewing typographica described similar frutiger tankard described aims family design “ wanted move away round i-dot sans fonts 've seen lot recently less cuddly assertive wanted italic expressive sloped roman corbel default renders numbers text figures old style lowercase numerals preferred integrating figures running text uncommon choice sans-serif faces especially designed display screen several cleartype fonts also make default option lining figures suggested using opentype stylistic alternates menu text figures also found microsoft serif georgia typeface distributed microsoft excel viewer microsoft powerpoint viewer microsoft office compatibility pack microsoft windows open xml file format converter mac use operating systems gnu/linux cross-platform use web use available freeware licensed sold ascender
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Operating systems
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list cluster management software list software cluster management
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Distributed computing architecture
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z-dos z-dos discontinued oem version microsoft ms-dos specifically adapted run hardware zenith z-100 personal computer z-100 used 8086-family microprocessor intel 8088 otherwise completely different internal architecture ibm pc time microsoft ms-dos n't specifically geared specific hardware platform could tailored run system long used 8086-compatible microprocessor situation completely like popular cp/m systems time typically used 8080-compatible 8080 8085 z80 among others microprocessor order achieve ms-dos like cp/m relied platform-specific dos- bios written target machine hardware-independent dos kernel could run beside ibm oem version ms-dos released pc dos dozens oem versions ms-dos geared specific non-ibm-compatible oem hardware—among zenith z-dos later almost 100 ibm-compatible clones became norm ms-dos became generic version could run generic version ms-dos however could run older non-ibm-compatible machines like z-100
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Operating systems
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george operating system george name given series operating systems released international computers tabulators ict 1960s ict 1900 series computers included george 1 george 2 george 3 george 4 initially 1900 series machines like ferranti-packard 6000 based ran simple operating system known executive allowed system operator load run programs teletype model 33 asr based system console december 1964 ict set operating systems branch develop new operating system 1906/7 branch initially staffed people released end work omp operating system ferranti orion initial design new system named george george e. felton head basic programming division based ideas orion spooling system atlas computer public claimed george stood general organisational environment contemporary sources say backronym july 1965 team ict present seminar npl describing ctss operating system developed mit project mac decided ict would need provide multi-access facilities known ict mop multiple online processing november 1965 h. p. goodman head operating systems branch attended fall joint computer conference las vegas plans multics initially described multics features discussed influenced future development george notably tree structured filestore towards end 1965 ict marketing requested simpler operating system made available quickly especially smaller members range decided two smaller systems known george 1 george 2 released rapidly larger operating system renamed george 3 george 1 simple batch processing system job descriptions read cards paper tape controlled loading running programs either loaded cards paper tape magnetic tape job control language allowed definition peripherals files used handling exception conditions job description would checked errors job run george used trusted program facilities provided executive run user programs george 2 added concept line peripheral handling spooling several different modules running parallel allowed overlapping input processing output operations installation large enough multiple copies central module could run allowing multiple jobs processed parallel george 2 job control language allowed use stored macros conditional facilities george 2 provided file system system user programs relied facilities provided executive files disk accessed unique 12 character names security erase bit provided minimop could run simultaneously george 2 machine provide on-line time-sharing facilities somewhat artificial example batch george 2 real application job would probably use stored macro much simpler example written longhand effort show features jcl george 3 main version operating system series larger machines 1900 series initially released 1906/7 eventually made available models 1902t contrast george 1 2 ran user-mode programs executive george 3 full operating system leaving low-level peripheral interrupt handling cut-down version executive george 3 implemented small memory-resident part collection chapters overlays loaded removed memory needed chapters strictly location-independent allowing best use memory internally george used cooperative multitasking context switches could take place chapter change call one chapter another specified places code user-level code run using preemptive multitasking context switches forced i/o operations clock ticks george written special assembler gin george input richer conditional compilation macro facilities standard plan assembler macros heavily used code reduce effort programming large system assembly language later versions macro features gin used add structured programming features code writing system estimated taken 75 programmer-years effort george 3 mixed batch online system jobs could run cards tape manner george 2 interactively mop multiple online processing terminals either simple teletype model 33 asr terminals block mode vdu terminals job control language terminals batch jobs included conditional operations macro operations contrast unix systems job control language part operating system rather user level shell process job could one program loaded memory time one job could start jobs run concurrently system resources site policy would permit system would swap user programs memory waiting input output activities required memory run george 3 provided tree structured file store inspired part multics every user system home directory many sub directories needed users home directory could accessed directly example directory user john could referred john full path example john computer science department home directory might manager.users.compsci.john access control lists used security user could permit deny user group users access files directories file data storage two-level files could either currently disk system low disk space could automatically relegated magnetic tape attempt made access currently line file job would suspended operators requested load appropriate tape tape made available file would brought back disk job resumed starting 1904a paging unit available larger 1900 processors george 4 written take advantage george 4 remained compatible george 3 common alternate george 3 4 machine filestore running george 3 day small interactive workloads george 4 night large memory intensive jobs george 4 introduced concept sparse program program addressing space larger allocated memory read-only pure data code regions new versions consolidator linker compilers provided use facilities source code george 3 4 conditional compilation facilities gin assembler used select version system compiled 1900 paging feature emulated 2900 series machines used later george installations george 4 fell use george 3 simple examples george use job modelled george 2 job like job somewhat artificial real use work would done pre-stored macro command job would read card paper tape reader minor changes removal first jb command could stored file run interactive mop terminal user input shown lower case output george upper case george distributed form allowed site modify large parts system compilation system started interrupted end dumped magnetic tape gin compiler allowed compilation continued point user site possibly modifying code already compiled versions george 3 release 8 provided binary form modifications needed system made binary patches simplify process george chapters included empty mend area end starting release 8 source george distributed binary magnetic tape microfiche system source level patches known mendits used modify system existing chapter could completely replaced new modified chapter george user group set mend exchange scheme share interesting modifications george modifications distributed freely others available fee icl produced new version george would sometimes include modifications produced users last released version 8.67 patches mend exchange scheme included standard george source switched conditional compilation turned part standard process tailoring george site george well documented internally series looseleaf folders distributed initial version plus amendments eventually original pages replaced new copy manuals consisted box empty looseleaf folders pile amendments first amendment list contributors technical reason amendment described keep everyone happy modified version george 3 supplied university manchester regional computer centre umrcc linked george 3 cdc cyber machine george supplied offline i/o job queueing functions online support supplied icl cyber hardware software cyber support team worked office name cybermen door release icl new range 2900 series vme operating system george became obsolete however due legacy investment software george icl released options run 1900 series software including george 2900 series machines initially direct machine environment dme later concurrent machine environment cme allowed simultaneous running 1900 2900 code system new versions george 3 continued released 2900 last version 8.67 released 1983 2005 least one site russia still running george 3 dme november 2014 george 3 run reconditioned icl 2966 national museum computing david holdsworth delwyn holroyd obtained copies george 3 issue tapes last live site uk british steel corporation decommissioned wrote emulator 1900 hardware executive allows running george microsoft windows linux part project computer conservation society emulator includes emulation executive java emulation icl7903 communications processor making possible run mop sessions telnetting case port 2023 tests emulator show george 3 y2k compliant
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Operating systems
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klax video game klax 1990 puzzle video game designed dave akers mark stephen pierce object line colored blocks rows similar colors make disappear object columns similar atari games originally released coin-op follow-up tetris tangled legal dispute time released summer 1990 also known last game released atari 2600 console discontinued early 1992 klax features conveyor belt top screen constantly rolls toward playing area delivering steady supply blocks player controls small device sits interface conveyor belt playing area moved left right catch blocks deposit either playing area hold 25 blocks 5x5 arrangement push back conveyor belt device hold five blocks uncaught block considered drop flashing block used wildcard colour playing area blocks eliminated arranging three color continuous line known klax line may horizontal vertical diagonal multiple grouping e.g. one vertical horizontal counts multiple klaxes klaxes four same-colored blocks two klaxes five same-colored blocks three klaxes goal reached bonus points awarded remaining blocks conveyor belt device empty spaces bin also levels certain point total required points excess required amount counted scoring bonus points klax consists 100 levels grouped blocks five beginning game fifth level levels divisible five except levels 95 100 player choose skip five ten levels skipping levels gives bonus points higher drop allowance game ends player either exhausts drop allowance fills playing area finishes level 100 akers programmed klax weeks using amigabasic ported line-by-line c. 1990 interview said wanted produce something playable compact relatively quick develop influences tetris tic-tac-toe chose name sound tiles make rolling across screen atari games released klax february 1990 soon called major arcade hit quickly released several home versions tengen brand akers created nintendo entertainment system genesis editions 16-bit conversions featured improved graphics klax received parents choice foundation seal approval 1990 best mind game 1991 european computer leisure awards dennis lynch chicago tribune named klax best cartridge 1990 midway games gained rights klax upon purchasing atari games 1996 title re-released retro compilations modern consoles 1999 press release called midway tic-tac tile puzzle game mike mika working game boy color version game placed hidden wedding proposal inside took girlfriend three years uncover proposal mike mika also placed hidden snake-like game well mini-adventure game within game easter eggs arcade version klax saw ports contemporary home computers video game systems 1990s including atari lynx amstrad gx4000 even atari 2600 final official atari-licensed release exclusively europe klax first game versions three 1990s leading consoles nintendo entertainment system genesis turbografx-16 klax included arcade party pak playstation game also reissued midway arcade treasures 2003 compilation nintendo gamecube playstation 2 xbox pc also appeared lego dimensions release famicom tsūshin awarded pc engine version game 30 40 game ranked 26th best game time amiga power 1991 2012 author named kieren hawken described klax one coveted video games time capsule review lynx version start clayton walnum commented start playing klax maniac uzi wo n't able tear away graphics clean vivid music darn near good enough dance digitized sound effects speech astonishing small unit julian rignall reviewed atari lynx version cvg magazine january 1991 quoting game simple addictive giving rating 93 100
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Computer architecture
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