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vmware vmware inc. publicly traded software company listed nyse stock ticker vmw dell technologies majority share holder vmware provides cloud computing virtualization software services one first commercially successful companies virtualize x86 architecture vmware desktop software runs microsoft windows linux macos enterprise software hypervisor servers vmware esxi bare-metal hypervisor runs directly server hardware without requiring additional underlying operating system 1998 vmware founded diane greene mendel rosenblum scott devine ellen wang edouard bugnion greene rosenblum married first met university california berkeley edouard bugnion remained chief architect cto vmware 2005 went found nuova systems part cisco first year vmware operated stealth mode roughly 20 employees end 1998 company launched officially early second year february 1999 demo conference organized chris shipley first product vmware workstation delivered may 1999 company entered server market 2001 vmware gsx server hosted vmware esx server hostless 2003 vmware launched vmware virtual center vmotion virtual smp technology 64-bit support introduced 2004 january 9 2004 terms definitive agreement announced december 15 2003 emc dell emc acquired company 625 million cash august 14 2007 emc sold 15 vmware public via initial public offering shares priced per share closed day july 8 2008 disappointing financial performance board directors fired vmware co-founder president ceo diane greene replaced paul maritz retired 14-year microsoft veteran heading emc cloud computing business unit greene ceo since company founding ten years earlier september 10 2008 mendel rosenblum company co-founder chief scientist husband diane greene resigned september 16 2008 vmware announced collaboration cisco systems one result cisco nexus 1000v distributed virtual software switch integrated option vmware infrastructure april 2011 emc transferred control mozy backup service vmware april 12 2011 vmware released open-source platform-as-a-service system called cloud foundry well hosted version service supported application deployment java ruby rails sinatra node.js scala well database support mysql mongodb redis postgres rabbitmq march 2013 vmware announced corporate spin-off pivotal software general electric making investment company vmware application- developer-oriented products including spring tc server cloud foundry rabbitmq gemfire sqlfire transferred organization may 2013 vmware launched iaas service vcloud hybrid service new palo alto headquarters vcloud hybrid service rebranded vcloud air subsequently sold cloud provider ovh announcing early access program las vegas data center service designed function extension customer existing vsphere installations full compatibility existing virtual machines virtualized vmware software tightly integrated networking service based vcloud director 5.1/vsphere 5.1 september 2013 vmworld san francisco vmware announced general availability vcloud hybrid service expansion sterling virginia santa clara california dallas texas service beta uk announced acquisition desktone october 2013 january 2016 anticipation dell acquisition emc vmware announced restructuring reduce 800 positions executives resigned entire development team behind vmware workstation fusion disbanded us developers immediately fired april 24 2016 maintenance release 12.1.1 released september 8 2016 vmware announced release workstation 12.5 fusion 8.5 free upgrade supporting windows 10 windows server 2016 april 2016 vmware president coo carl eschenbach left vmware join sequoia capital martin casado vmware general manager networking security business left join andreessen horowitz analysts commented cultures dell emc emc vmware different said heard impending corporate cultural collisions potentially radical product overlap pruning would cause many emc vmware personnel leave vmware ceo pat gelsinger following rumours categorically denied would leave august 2016 vmware introduced vmware cloud provider website new branch role funneling cloud related information central source cloud provider technology content thanks “ services first ” approach cloud providers find differentiated monetizable services deliver leveraging vmware ’ platform latest case studies demos blogs architecture toolkits vmware available one place mozy transferred dell 2016 merger dell emc april 2017 according glassdoor vmware ranked 3rd list highest paying companies united states q2 2017 vmware sold vcloud air french cloud service provider ovh march 2015 software freedom conservancy announced funding litigation christoph hellwig hamburg germany vmware alleged violation copyrights esxi product sfc claimed vmware using linux kernel busybox without respecting terms gpl copyright license vmware told journalists believed case without merit expressed disappointment conservancy resorted litigation lawsuit dismissed court july 2016 hellwig announced would file appeal appeal decided february 2019 dismissed german court basis meeting procedural requirements burden proof plaintiff vmware notable products hypervisors vmware became well known first type 2 hypervisor known gsx product since evolved two hypervisor products lines vmware type 1 hypervisors running directly hardware hosted type 2 hypervisors vmware software provides completely virtualized set hardware guest operating system vmware software virtualizes hardware video adapter network adapter hard disk adapters host provides pass-through drivers guest usb serial parallel devices way vmware virtual machines become highly portable computers every host looks nearly identical guest practice system administrator pause operations virtual machine guest move copy guest another physical computer resume execution exactly point suspension alternatively enterprise servers feature called vmotion allows migration operational guest virtual machines similar separate hardware hosts sharing storage vmotion storage separate storage used transitions completely transparent users virtual machine time migrated vmware workstation server esx take optimized path running target operating systems host emulators bochs simulate function cpu instruction target machine one-by-one dynamic recompilation compiles blocks machine-instructions first time execute uses translated code directly code runs subsequently microsoft virtual pc macos takes approach vmware software emulate instruction set different hardware physically present significantly boosts performance cause problems moving virtual machine guests hardware hosts using different instruction sets found 64-bit intel amd cpus hardware hosts differing number cpus software cpu agnostic usually survive transition unless agnostic forking startup case software guest os must stopped moving restarted move vmware products predate virtualization extensions x86 instruction set require virtualization-enabled processors newer processors hypervisor designed take advantage extensions however unlike many hypervisors vmware still supports older processors cases uses cpu run code directly whenever possible example running user-mode virtual 8086 mode code x86 direct execution operate kernel-level real-mode code vmware products use binary translation bt re-write code dynamically translated code gets stored spare memory typically end address space segmentation mechanisms protect make invisible reasons vmware operates dramatically faster emulators running 80 speed virtual guest operating system would run directly hardware one study vmware claims slowdown native ranging 0–6 percent vmware esx server vmware approach avoids difficulties virtualization x86-based platforms virtual machines may deal offending instructions replacing simply running kernel code user mode replacing instructions runs risk code may fail find expected content reads one protect code reading allowing normal execution replacing place becomes complicated running code unmodified user mode also fail instructions read machine state cause exception betray real state program certain instructions silently change behavior user mode one must always rewrite performing simulation current program counter original location necessary notably remapping hardware code breakpoints although vmware virtual machines run user mode vmware workstation requires installation various device drivers host operating system notably dynamically switch global descriptor table gdt interrupt descriptor table idt vmware product line also run different operating systems dual-boot system simultaneously booting one partition natively using guest within vmware workstation vmware esxi enterprise software product deliver greater performance freeware vmware server due lower system computational overhead vmware esxi bare-metal product runs directly server hardware allowing virtual servers also use hardware less directly addition vmware esxi integrates vmware vcenter offers extra services vmware workspace portal self-service app store workspace management vmware storage availability products composed two primary offerings vmware nsx vmware network virtualization product marketed using term software-defined data center sddc technology included acquired 2012 purchase nicira workspace one allows mobile users access apps data vix virtual infrastructure extension api allows automated scripted management computer virtualized using either vmware vsphere workstation player fusion products vix provides bindings programming languages c perl visual basic vbscript c
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Distributed computing architecture
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phpstorm jetbrains phpstorm commercial cross-platform ide integrated development environment php built jetbrains intellij idea platform phpstorm provides editor php html javascript on-the-fly code analysis error prevention automated refactorings php javascript code phpstorm code completion supports php 5.3 5.4 5.5 5.6 7.0 7.1 7.2 modern legacy projects including generators coroutines finally keyword list foreach namespaces closures traits short array syntax includes full-fledged sql editor editable query results phpstorm built intellij idea written java users extend ide installing plugins created intellij platform write plugins features available webstorm included phpstorm adds support php databases webstorm ships pre-installed javascript plugins node.js ultimate edition jetbrains polyglot ide intellij idea supports functionality phpstorm plugins november 2015 jetbrains switched licensing phpstorm subscription basis annual subscriptions monthly subscriptions maintained 12 consecutive months also receive perpetual fallback license major version available time purchase phpstorm available individual developers business organizations additional discounted complementary licenses available startups students teachers non-commercial open source projects complementary licenses require approval include perpetual fallback clause i.e expire
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Programming language topics
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ms/8 ms/8 rl monitor system discontinued operating system developed digital equipment corporation pdp-8 1966 richard f. lary submitted decus 1970 disk oriented system faster predecessor 4k disk monitor system tricks make run quickly dectape based systems ms/8 since replaced p s/8 cos-310
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Operating systems
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cockroach labs cockroach labs computer software company develops commercial database management systems best known cockroachdb compared google spanner cockroachdb project designed store copies data multiple locations order deliver speed access described scalable consistently-replicated transactional datastore cockroach labs founded 2015 ex-google employees spencer kimball peter mattis ben darnell prior cockroach labs kimball mattis key members google file system team darnell key member google reader team google three previously used bigtable acquainted successor spanner leaving google wanted design build something similar companies outside google june 2015 company nine cockroachdb engineers spencer kimball wrote first iteration design january 2014 began open-source project github february 2014 allowing outside access contributions attracted community experienced contributors co-founders actively supporting project conferences networking meet-ups collaborations github earned open source rookie year title awarded black duck software open-source projects june 2015 company closed 6.25 million funding benchmark sequoia google ventures firstmark capital benchmark general partner peter fenton named company board directors additional investors included hortonworks chief executive rob bearden coreos ceo alex polvi cloudera co-founder jeff hammerbacher june 2019 cockroach labs announced cockroachdb would change license free software license apache license 2.0 proprietary license cockroach labs raised 55 million series c round august 2019 led altimeter capital database scalable single instance scale single laptop thousands servers cockroachdb designed run cloud resilient failures result database described almost impossible take even multiple servers entire datacenter go offline cockroachdb would keep services online
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Databases
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wallace v. international business machines corp. wallace v. international business machines corp. 467 f.3d 1104 7th cir 2006 significant case development free software case decided court appeals seventh circuit united states law gnu general public license gpl contravene federal antitrust laws daniel wallace united states citizen sued free software foundation fsf price fixing later lawsuit unsuccessfully sued ibm novell red hat wallace claimed free linux prevented making profit selling operating system 2005 daniel wallace filed suit fsf u.s. district court southern district indiana stating gpl requiring copies computer software licensed made available freely possibly even cost tantamount price fixing november 2005 case dismissed without prejudice wallace filed multiple amended complaints effort satisfy requirements antitrust allegation fourth final amended complaint dismissed march 20 2006 judge john daniel tinder wallace ordered pay fsf costs decision grant motion dismiss court ruled wallace failed allege antitrust injury claim could based since wallace obligated claim injured also market court instead found court also noted prior cases established sherman act enacted assure customers benefits price competition emphasized act primary purpose protecting economic freedom participants relevant market decision thus supports right authors content creators offer creations free charge 2006 daniel wallace filed lawsuit software companies ibm novell red hat profit distribution open-source software specifically gnu/linux operating system wallace allegation software companies engaging anticompetitive price fixing may 16 2006 judge richard l. young dismissed case prejudice wallace later filed appeal seventh circuit appeal court case heard de novo front three-judge panel led frank easterbrook lost appeal judge citing number problems complaint
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Operating systems
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macpup macpup operating system based puppy linux puppy normal jwm window manager available also includes enlightenment wm users quickly switch window managers without rebooting macpup enlightenment interface installed features mac os x-like dockbar many enlightenment themes available macpup comes firefox web browser like parent macpup run ram live .iso uses 184mb ram
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Operating systems
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dynamic secrets dynamic secrets novel key management scheme secure communications proposed sheng xiao weibo gong towsley first academic publication nominated infocom 2010 best paper award later monograph published springer extend scheme framework dynamic secrets applied bi-directional communication systems single-directional communication systems improve communication security three main benefits 1. encryption authentication keys rapidly automatically updated pair communication devices 2. key update process binds communication process incurs negligible computing bandwidth cost 3 use cloned key either authentication encrypted communication guaranteed detected detection false alarms cost computing networking resources dynamic secrets automatically break secure communication clone key legitimate key co-exist however order find attacker takes actions consumes computing power network bandwidth
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Computer security
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assignment computer science computer programming assignment statement sets and/or re-sets value stored storage location denoted variable name words copies value variable imperative programming languages assignment statement expression fundamental construct today commonly used notation basic operation come codice_1 originally superplan 1949–51 popularized fortran 1957 c followed codice_2 originally algol 1958 popularised pascal although many notations use languages symbol used regarded operator meaning assignment statement whole returns value others define assignment statement meaning used expression assignments typically allow variable hold different values different times life-span scope however languages primarily strictly functional allow kind destructive reassignment might imply changes non-local state purpose enforce referential transparency i.e functions depend state variable produce results given set parametric inputs point time modern programs languages also often use similar strategies although less strict certain parts order reduce complexity normally conjunction complementing methodologies data structuring structured programming object orientation assignment operation process imperative programming different values associated particular variable name time passes program model operates changing state using successive assignment statements primitives imperative programming languages rely assignment iteration lowest level assignment implemented using machine operations codice_3 codice_4 variables containers values possible put value variable later replace new one assignment operation modifies current state executing program consequently assignment dependent concept variables assignment example assuming codice_7 numeric variable assignment codice_8 means content variable codice_7 doubled execution statement example segment c code sample variable codice_10 first declared int assigned value 10 notice declaration assignment occur statement second line codice_11 declared without assignment third line codice_10 reassigned value 23 finally codice_11 assigned value 32.4 assignment operation necessary value codice_5 well-defined valid rvalue codice_6 represents modifiable entity valid modifiable non-const lvalue languages typically dynamic ones necessary declare variable prior assigning value languages variable automatically declared first time assigned scope declared varying language assignment changes existing value e.g codice_16 disallowed purely functional languages functional programming assignment discouraged favor single assignment also called initialization single assignment example name binding differs assignment described article done usually variable created subsequent reassignment allowed evaluation expression side effect change observable state machine produces values input imperative assignment introduce side effects destroying making old value unavailable substituting new one referred destructive assignment reason lisp functional programming similar destructive updating single assignment form assignment available purely functional languages haskell variables sense imperative programming languages rather named constant values possibly compound nature elements progressively defined on-demand purely functional languages provide opportunity computation performed parallel avoiding von neumann bottleneck sequential one step time execution since values independent impure functional languages provide single assignment well true assignment though true assignment typically used less frequency imperative programming languages example scheme single assignment codice_17 true assignment codice_18 used variables specialized primitives provided destructive update inside lists vectors strings etc ocaml single assignment allowed variables via codice_19 syntax however destructive update used elements arrays strings separate codice_20 operator well fields records objects explicitly declared mutable meaning capable changed initial declaration programmer functional programming languages use single assignment include clojure data structures vars erlang accepts multiple assignment values equal contrast haskell f haskell lava ocaml oz dataflow variables cells racket data structures like lists symbols sasl scala vals sisal standard ml non-backtracking prolog code considered explicit single-assignment explicit sense named variables explicitly unassigned state set exactly haskell contrast unassigned variables every variable thought implicitly set value rather computational object produce value demand created programming languages assignment statement returns value others expression-oriented programming languages example c assignment statement returns assigned value allowing idioms codice_21 assignment statement codice_22 returns value codice_7 assigned codice_10 statement codice_25 return value function used control loop assigning value variable programming languages scheme example return value assignment undefined idioms invalid haskell variable assignment operations similar assignment like assigning field array field mutable data structure usually evaluate unit type represented codice_26 type one possible value therefore containing information typically type expression evaluated purely side effects certain use patterns common thus often special syntax support primarily syntactic sugar reduce redundancy source code also assists readers code understanding programmer intent provides compiler clue possible optimization case assigned value depends previous one common many imperative languages notably c majority descendants provide special operators called augmented assignment like codice_27 codice_28 instead written codice_29 beyond syntactic sugar assists task compiler making clear in-place modification variable codice_7 possible statement like codice_31 called chained assignment value codice_32 assigned multiple variables codice_33 codice_11 chained assignments often used initialize multiple variables codice_35 programming languages support chained assignment chained assignments equivalent sequence assignments evaluation strategy differs languages simple chained assignments like initializing multiple variables evaluation strategy matter targets l-values assignment connected way evaluation strategy affects result programming languages c example chained assignments supported assignments expressions values case chain assignment implemented right-associative assignment assignments happen right-to-left example codice_36 equivalent codice_37 c++ also available values class types declaring appropriate return type assignment operator python assignment statements expressions thus value instead chained assignments series statements multiple targets single expression assignments executed left-to-right codice_36 evaluates expression codice_39 assigns result leftmost target codice_40 assigns result next target codice_41 using new value codice_40 essentially equivalent codice_43 though actual variable produced temporary value programming languages apl common lisp go javascript since 1.7 php maple lua occam 2 perl python rebol ruby windows powershell allow several variables assigned parallel syntax like simultaneously assigns 0 codice_7 1 codice_45 often known parallel assignment introduced cpl 1963 name simultaneous assignment sometimes called multiple assignment though confusing used single assignment opposites right-hand side assignment single variable e.g array structure feature called unpacking destructuring assignment list unpacked 0 assigned codice_7 1 codice_45 furthermore swaps values codice_7 codice_45 languages without parallel assignment would written use temporary variable since codice_50 leaves codice_7 codice_45 original value codice_45 languages go python combine parallel assignment tuples automatic allow multiple return values single function python example provides alternative use output parameters returning multiple values function dates clu 1974 clu helped popularize parallel assignment generally c c++ comma operator similar parallel assignment allowing multiple assignments occur within single statement writing codice_54 instead codice_55 primarily used loops replaced parallel assignment languages go however c++ code ensure perfect simultaneity since right side following code codice_56 evaluated left side languages python codice_57 assign two variables concurrently using initial value compute new b use equals sign codice_58 assignment operator frequently criticized due conflict equals comparison equality results confusion novices writing code confusion even experienced programmers reading code use equals assignment dates back heinz rutishauser language superplan designed 1949 1951 particularly popularized fortran beginning programmers sometimes confuse assignment relational operator equality means equality mathematics used assignment many languages assignment alters value variable equality testing tests whether two expressions value languages basic single equals sign codice_59 used assignment operator equality relational operator context determining meant languages use different symbols two operators example similarity two symbols lead errors programmer forgets form codice_58 codice_67 codice_68 appropriate mistypes codice_58 codice_67 intended common programming problem languages c including one famous attempt backdoor linux kernel assignment operator also returns value assigned way function returns value validly nested inside expressions intention compare two values codice_71 statement instance assignment quite likely return value interpretable boolean true case codice_72 clause executed leading program behave unexpectedly language processors gcc detect situations warn programmer potential error two common representations copying assignment equals sign codice_58 colon-equals codice_68 forms may semantically denote either assignment statement assignment operator also value depending language and/or usage possibilities include left arrow keyword though rarer variants mathematical pseudo code assignments generally depicted left-arrow platforms put expression left variable right expression-oriented languages lisp tcl uniformly use prefix postfix syntax statements including assignment
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Programming language topics
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gremlin programming language gremlin graph traversal language virtual machine developed apache tinkerpop apache software foundation gremlin works oltp-based graph databases well olap-based graph processors gremlin automata functional language foundation enable gremlin naturally support imperative declarative querying host language agnosticism user-defined domain specific languages extensible compiler/optimizer single- multi-machine execution models hybrid depth- breadth-first evaluation well turing completeness explanatory analogy apache tinkerpop gremlin graph databases jdbc sql relational databases likewise gremlin traversal machine graph computing java virtual machine general purpose computing gremlin apache2-licensed graph traversal language used graph system vendors typically two types graph system vendors oltp graph databases olap graph processors table outlines graph vendors support gremlin following examples gremlin queries responses gremlin-groovy environment relative graph representation movielens dataset dataset includes users rate movies users one occupation movie one categories associated movielens graph schema detailed gremlin supports declarative graph pattern matching similar sparql instance following query uses gremlin match -step gremlin virtual machine composed instruction set well execution engine analogy drawn gremlin java following traversal gremlin traversal gremlin-java8 dialect gremlin language i.e fluent-style expressing graph traversal represented host language supports function composition function nesting due simple requirement exists various gremlin dialects including gremlin-groovy gremlin-scala gremlin-clojure etc gremlin-java8 traversal ultimately compiled step sequence called traversal string representation traversal provided steps primitives gremlin graph traversal machine parameterized instructions machine ultimately executes gremlin instruction set approximately 30 steps steps sufficient provide general purpose computing typically required express common motifs graph traversal query given gremlin language instruction set virtual machine possible design another traversal language compiles gremlin traversal machine analogous scala compiles jvm instance popular sparql graph pattern match language compiled execute gremlin machine following sparql query would compile gremlin-java8 sparql query would represented compile identical gremlin step sequence i.e traversal gremlin graph traversal machine execute single machine across multi-machine compute cluster execution agnosticism allows gremlin run graph databases oltp graph processors olap
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Distributed computing architecture
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computer security policy computer security policy defines goals elements organization computer systems definition highly formal informal security policies enforced organizational policies security mechanisms technical implementation defines whether computer system secure insecure formal policy models categorized core security principles confidentiality integrity availability example bell-la padula model confidentiality policy model whereas biba model integrity policy model system regarded finite-state automaton set transitions operations change system state security policy seen statement partitions states authorized unauthorized ones given simple definition one define secure system one starts authorized state never enter unauthorized state represent concrete policy especially automated enforcement language representation needed exist lot application specific languages closely coupled security mechanisms enforce policy application compared abstract policy languages e.g domain type enforcement-language independent concrete mechanism
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Computer security
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fx-87 fx-87 polymorphic typed functional language based system static program analysis every expression two static properties type effect study done mit fx-87 yields similar performance results functional languages programs contain side effects fibonacci factorial fx-87 yield great performance increase matching dna sequences kfx kernel language fx-87 described 'polymorphic effect systems j.m lucassen et al. proceedings 15th annual acm conference popl acm 1988 pp 47–57
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Programming language topics
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francis raven francis raven april 26 1914 december 1983 american cryptologist early employee national security agency helped crack many codes assist united states world war ii also helped nsa training program creating two cryptology courses graduated yale university 1934 joined united states navy reserve officer assigned naval security group commission reactivated 1940 rejoined nsg working japanese problems agnes driscoll brief period working german ciphers returned japanese issues part group systematically solved many low level codes starting 1942 important source cribs used working jn-25 fleet code also worked jade coral machines successfully cracked war stayed civilian employee nsg joining armed forces security agency 1946 moving nsa formation 1952 1956 held series executive posts within agency culminating appointment chief office nsa training program played major part development two cryptology courses efforts several civilian awards retirement established firm genealogical research active death 1983
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Computer security
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powerbook 100 powerbook 100 portable subnotebook personal computer designed manufactured sony apple computer introduced october 21 1991 comdex computer expo las vegas nevada priced us 2,300 powerbook 100 low-end model first three simultaneously released powerbooks cpu overall speed closely resembled predecessor macintosh portable motorola 68000 16-megahertz mhz processor 2-8 megabytes mb memory monochrome backlit liquid crystal display lcd 640 × 400 pixel resolution system 7.0.1 operating system built-in floppy disk drive noted unique compact design placed trackball pointing device front keyboard ease use apple then-chief executive officer ceo john sculley started powerbook project 1990 allocating 1 million marketing despite small marketing budget new powerbook line success generating 1 billion revenue apple first year sony designed manufactured powerbook 100 collaboration apple industrial design group apple internal design team discontinued september 3 1992 superseded powerbook 145 powerbook duo series since praised several times design pc world named powerbook 100 tenth-greatest pc time 2006 us magazine mobile pc chose powerbook 100 greatest gadget time 2005 1990 john sculley ceo apple oversaw product development personally ensure apple released new computers market quickly new strategy increase market share lowering prices releasing hit products strategy contributed commercial success low-end macintosh classic macintosh lc desktop computers released apple 1990 sculley wanted replicate success products apple new powerbook line sculley began project 1990 wanted powerbook released within one year project three managers john medica managed engineering new laptop randy battat vice president product marketing neil selvin headed marketing effort 1991 two leaders laptop computer industry toshiba compaq introduced models weighing less medica battat selvin deliberately designed powerbook weigh less competitors sculley allocated 1 million marketing budget powerbook product line contrast 25 million used market macintosh classic medica battat selvin used money produce air television commercial viewers would remember advertising agency chiat/day filmed retired los angeles lakers basketball star kareem abdul-jabbar sitting uncomfortably small airline coach seat yet typing comfortably powerbook ad caption read least hands comfortable apple unveiled powerbook 100 october 21 1991 comdex computer expo las vegas alongside two models powerbook 140 powerbook 170 advertisement product successful apple projected us sales 200,000 powerbooks first year peak demand first three months release january 1992 apple sold 100,000 powerbooks time short supply apple soon solved supply problems proceeds powerbook sales reached 1 billion first year launch apple surpassed toshiba compaq market leader worldwide share portable computer shipments powerbook 100 140 170 contributed greatly apple financial success 1992 end financial year apple announced highest figures yet 7.1 billion revenues increase global market share 8 8.5 highest four years however initial popularity powerbook 100 last sales decreased december 1991 140 170 models become popular customers willing pay built-in floppy disk drive second serial port powerbook 100 lacked august 10 1992 apple quietly dropped powerbook 100 price list continued sell existing stock dealers alternative discount consumer-oriented stores price club stores 4mb ram/40mb hard drive configuration floppy drive sold less 1,000 1,500 less similar 2mb/20mb configuration original list price september 17 1992 apple recalled 60,000 powerbook 100s potential safety problem electrical short discovered could melt small hole casing occurred three 60,000 notebooks manufactured october 1991 march 1992 day recall apple shares closed 47 1.25 analysts discounted recall importance addition original power supplies problems insulation cracks could cause short fuse motherboard computer prone cracks power adapter socket motherboard required 400 replacement motherboard warranty expired powerbook 100 internal components based predecessor macintosh portable included motorola 68hc000 16 mhz processor 2 mb memory floppy disk drive cost approximately 2,300 external floppy disk drive available 279 dimensions powerbook 100 improvement portable deep wide high compared portable deep wide high another significant difference less expensive passive matrix display used instead sharper active matrix used portable 170 powerbook 100 included system 7.0.1 operating system standard support versions system 7.5.5 apple however released system 6.0.8l allowed powerbook 100 run system 6 could also used earlier system 6 versions although apple officially support powerbook 100 one external serial port designed use printer compatible rs-422 device first macintosh omit external modem port instead offering optional built-in 2400 baud modem communications result first time user could print directly access appletalk faster external modem simultaneously devices advanced midi interfaces could used required dedicated use ports third-party serial modem port could however installed internal modem slot consumers needed traditional functions computer use contents memory preserved long main lead-acid battery remained charged powerbook 100 power manager integrated circuit usually placed logic board powerbook responsible power management computer identical macintosh portable controlled display backlight hard drive spin-down sleep wake battery charging trackball control input/output i/o 100 add new feature 3.5 v batteries backed permanent expansion random access memory ram powerbook 100 battery replaced 100 otherwise temporarily removed power sources made perfect candidate use apple ram disk help increase battery life accessing hard disk less frequently since 100 powerbook maintained contents ram shutdown order reduce startup time powerbook 100 first powerbook incorporate scsi disk mode allowed used external hard disk desktop macintosh provided convenient method software installed onto powerbook transferred desktop without need 100 optional floppy disk drive specialized scsi cable unique connector required however use scsi device powerbook series second dedicated cable required scsi disk mode feature unique 100 apple introduced new powerbooks year later two versions powerbook 100 qwerty layout keyboard domestic us version 63 keys international iso version 64 keys caps lock key powerbook 100 locking position lighted indicator status compensate system 7 operating system software includes extension file causes icon international caps lock symbol ⇪ appear upper right-hand corner menu bar caps lock active internals powerbook 100 basis apple wizzy active lifestyle telephone prototype powerbook 140 170 designed 100 apple industrial design group march 1990-february 1991 100 styling based computers represents first improvements powerbook line apple benefited lessons learned developing powerful models enclosure 100 designed september december 1990 retained design elements variation snow white design language apple using since 1984 specifically raised ridges spaced apart intended tie existing product line apple approached sony late 1989 enough engineers handle number new products planned delivery 1991 using basic blueprint apple including list chips components portable architecture 100 miniaturized manufactured sony san diego california japan sony engineers little experience building personal computers nonetheless completed apple smallest lightest machine 13 months cancelling projects giving powerbook 100 top priority sony president norio ohga gave project manager kihey yamamoto permission recruit engineers sony division robert brunner apple head industrial design time led design team developed laptop including trackball granite color brunner said designed powerbook would easy use carry regular book dark granite grey color set apart notebook computers time also apple products traditionally beige platinum grey trackball another new design element placed middle computer allowing powerbook easily operated left- right-handed users designers trying create fashion statement overall design laptop felt made personal accessory like wallet briefcase brunner said says something identity person carrying crystal waters home office computing praised powerbook 100 unique effective design disappointed internal modem receive faxes 100 monitor port low-capacity 20 mb hard drive also criticized user core applications installed little room left optional programs documents waters concluded used 100 constantly past weeks know would n't feel cheated buying 40mb hard-disk drive option pc week benchmarked powerbook 100 measuring predecessor macintosh portable powerbook 100 took 5.3 seconds open microsoft word document 2.5 seconds save portable took 5.4 2.6 seconds respectively pc week tested battery life delivered 3 hours 47 minutes use byte magazine review concluded powerbook 100 recommended word processing communications tasks higher-end products offer enough power complex reports large spreadsheets professional graphics macweek described ideal writers others tight budget powerbook 100 continues receive recognition press pc world named powerbook 100 10th-greatest pc time 2006 2005 us magazine mobile pc chose powerbook 100 greatest gadget time ahead sony walkman atari 2600 powerbook 100 received multiple awards design including 1999 idsa silver design decade award form magazine 1993 designer design awards 1992 isda gold industrial design excellence award 1992 appliance manufacturer excellence design award industry forum design 10 best hannover fair award
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Computer architecture
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libreoffice base libreoffice base free open-source relational database management system part libreoffice office suite libreoffice base built fork openoffice.org first released version 3.4.0.1 october 4 2011 similarly packages libreoffice suite base supported across multiple platforms including microsoft windows macos linux base recognized cross-platform compatibility relative microsoft access developed exclusively windows libreoffice base designed allow users easily create access modify view databases data done providing users graphical user interface allows users work four main tools tables queries forms reports base includes software wizards assist users various aspects program base able work embedded external database files embedded databases stored single file using c++ based firebird java-based hsqldb storage engine connecting external databases base acts graphical user interface front-end facilitate interactions various database systems including microsoft access databases jet odbc/jdbc data sources mysql mariadb postgresql base described unusual project niche database management system software tends toward proprietary software designed enterprise users proprietary database management software costs described reason use base small businesses work ongoing transition embedded storage engine hsqldb firebird sql back-end firebird included libreoffice experimental option since libreoffice 4.2 august 2018 document foundation announced release libreoffice version 6.1 experimental mode used embedded firebird engine support fully available old hsqldb engine deprecated—although still available—and replaced firebird default option february 2019 document foundation released libreoffice version 6.2 embedded firebird engine support moved experimental mode operational firebird migration assistant create backup copy content xml document migration process
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Databases
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killer poke computer jargon killer poke method inducing physical hardware damage machine peripherals insertion invalid values via example basic poke command memory-mapped control register term typically used describe family fairly well known tricks overload analog electronics crt monitors computers lacking hardware sanity checking notable examples ibm portable commodore pet pet-specific killer poke connected architecture machine video rasterizer circuits early pets writing certain value memory address certain i/o register codice_1 made machine able display text screen much faster pet range revamped updated hardware discovered performing old trick new hardware led strange behavior new video chip could possibly damage pet integrated crt monitor commodore 64 optional external 5-1/4 floppy drive commodore 1541 contained 6502 microprocessor used run commodore dos also manage drive mechanism drives stored data 40 tracks 0–39 stepper motor could manually controlled basic print -ing memory-write commands drive correspond poke command basic write drive internal memory i/o registers computer drive either end range track 0 track 39 commanded continue moving software firmware method prevent drive damage continued knocking drive head stop would throw mechanism alignment problem exacerbated copy protection techniques used non-standard disk formats unusual track counts commodore 1571 optical head stop instead mechanical one trs-80 model iii ability switch 32-character-wide display 64-character display actuated relay video hardware accomplished writing specific memory-mapped control register programs repeatedly switched 32- 64-character modes high speed either purpose accidentally could permanently damage video hardware single killer poke demonstrates software failure mode could permanently damage hardware trs-80 color computer ibm pc ibm pcjr nascom msx amstrad cpc bbc micro acorn computers contained built-in relay controlling external tape recorder toggling motor control relay tight loop would reduce relay longevity floppy drive commodore amiga personal computer could made produce noises various pitches making drive heads move back forth program existed could play el cóndor pasa less correctly amiga floppy drive sounds relied head assembly hitting stop gradually sent head alignment certain models lg cd-rom drives specific firmware used abnormal command update firmware clear buffer command usually used cd-rw drives linux uses command tell difference cd-rom cd-rw drives cd-rom drives dependably return error unsupported cd-rw command faulty drives interpreted update firmware causing stop working casual parlance bricked systemd mounts variables used unified extensible firmware interface linux system sysfs writable root user system result possible root user system completely brick system non-conforming uefi implementation specifically msi laptops using codice_2 command delete codice_3 directory recursively delete root directory game boy lcd screen turned game software outside vertical blanking interval damage hardware
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Computer security
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wbem services specification jsr 48 java wbem api specification java specification request developed java community process specifies java language binding dmtf common information model/web-based enterprise management standards jsr 48 expert group completed public review 2006 way create technology compatibility kit order finalize standard api regarded stable jsr 48 requires java platform standard edition java se formerly j2se 7 higher ws jsr-48 api api composed 5 packages ws provides jsr-48 implementation part ws sdk pro ws also uses jsr-48 ws j wbem server wave wbem agent validation environment sblim cim client java adopted jsr 48 api stated openpegasus project use jsr 48 jmpi provider interface although status yet available
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Programming language topics
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zeroday emergency response team computer security zeroday emergency response team zert group volunteer security researchers produced emergency patches zero day attack vulnerabilities proprietary software came public notice late september 2006 patch month vector markup language vulnerability microsoft later producing patch older versions microsoft windows longer supported microsoft team included several members prominent antivirus network security work manifesto states zert members work together team release non-vendor patch so-called 0day zero-day exploit appears open poses serious risk public infrastructure internet purpose zert crack products rather uncrack averting security vulnerabilities widely exploited zert website updated since april 2007 group presumed inactive
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Computer security
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dirtbox cell phone dirtbox drt box cell site simulator phone device mimicking cell phone tower creates signal strong enough cause nearby dormant mobile phones switch mounted aircraft used united states marshals service locate collect information cell phones believed connected criminal activity also used jam phones device name comes company developed digital receiver technology inc. drt owned boeing company boeing describes device hybrid jamming managed access detection similar device smaller range controversial stingray phone tracker widely used u.s. federal entities including federal bureau investigation fbi known drt first manufactured dirtbox company publicly advertise stating web site due sensitive nature work unable publicly advertise many products wall street journal wrote u.s marshals service program utilizing device fully matured 2007 boeing bought drt 2008 similar devices harris corporation like stingray phone tracker sold around time since 2008 airborne mounting kit cell phone surveillance said cost 9,000 june 11 2010 boeing company asked national telecommunications information administration advise united states congress ... communications act 1934 modified allow prison officials state local law enforcement use appropriate cell phone management suggested special weapons tactics swat teams paramilitary tactical units could use devices control wireless communications raids chicago police department bought dirtboxes eavesdrop demonstrators 2012 nato summit used 2014 black lives matter demonstrations 2015 became known los angeles police department purchased devices device described size mimic cell phone tower utilizes imsi-catcher international mobile subscriber identity technology phone services use identify individual subscribers emits pilot signal made appear stronger nearest cell tower causing phones within range broadcast imsi numbers electronic serial numbers esn encryption prevent process devices retrieve phone encryption session keys less one second success rates 50–75 real world conditions aircraft-mounted device locate phone within 10 feet another source claims triangulating flights dirtbox pinpoint phone location two feet dirtbox hybrid detection managed access jamming technologies according wall street journal people knowledge program determine phones belong suspects non-suspects cell phones interest belonging prison personnel commercial users area returned local network also selectively interrupt prevent calls certain phones used block unauthorized phone use prison inmates also retrieve data phones according boeing technology unobtrusive legitimate wireless communications bypasses phone companies operations u.s marshals service technical operations group used device fixed manned airplanes track fugitives said deploy targets requested parts justice program devices operated least five u.s. airports covering u.s. population unclear whether u.s marshals service requests court orders use devices marshals service used dirtboxes mexican drug war tracking fugitives coordination mexico naval infantry force flights guatemala dirtboxes also used united states special operations command drug enforcement administration fbi u.s. customs border protection according procurement documents u.s. navy bought dirtboxes mount drones naval air weapons station china lake research development facility southern california pentagon washington headquarters services bought dirtboxes 2011 based references drtbox nsa boundless informant screenshots leaked edward snowden dirtboxes probably used nsa 2013 french newspaper lemonde wrote thanks drtbox 62.5 million phone data collected france united states naval special warfare development group group one bought digital receiver technology 1301b system april 2 2007 25,000 according united states government procurement web site national telecommunications information administration ntia known dirtboxes since least 2010 2014 united states department justice refused confirm deny government agencies used official said would utterly false conflate law-enforcement program collection bulk telephone records national security agency federal communications commission responsible licensing regulating cell-service providers aware dirtbox activity prior wall street journal exposé january 2015 us senate judiciary committee asked department justice department homeland security law enforcement agencies used drtboxes specify legal processes policies existed protect privacy whose information collected privacy advocates including u.s. rep. alan grayson d-florida criticized dirtbox use violation fourth amendment united states constitution brian owsley law professor indiana institute technology former united states magistrate said use devices legally think government would need obtain search warrant based probable cause consistent fourth amendment guardian quoted michael german professor new york university law school former fbi agent saying overriding problem excessive secrecy hides government ’ ever-expanding surveillance programs public accountability senator edward markey d-massachusetts former senator al franken d-minnesota warned americans privacy rights must assured
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Computer security
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internet explorer 10 internet explorer 10 ie10 tenth version internet explorer web browser released microsoft 2012 default browser windows 8 ie10 expands internet explorer 9 functionality regard css3 support hardware acceleration html5 support windows 8 divided two editions different user interfaces metro app support plug-ins traditional desktop application retains plug-in support 64-bit computers metro edition runs 64-bit mode default desktop edition run 64-bit mode enabling enhanced protected mode april 12 2011 microsoft released first ie10 platform preview runs windows 7 later second platform preview also available windows 7 later next four platform previews ran windows 8 first preview release came four weeks final release internet explorer 9 ie10 reached general availability september 4 2012 component windows server 2012 preview ie10 windows 7 made available download november 2012 february 26 2013 internet explorer 10 made available download windows 7 sp1 users january 12 2016 support ended ie10 windows operating systems capable running internet explorer 11 due new support policies dictating newest version ie available supported version windows supported ie10 supported windows server 2012 windows embedded 8 standard internet explorer 10 reach end support january 31 2020 ie 11 supported version internet explorer windows server 2012 windows embedded 8 standard ie 11 available piloting starting spring 2019 internet explorer 10 first announced april 12 2011 mix 11 conference las vegas conference microsoft showcased demo version internet explorer 10 along demo version windows 8 day platform preview internet explorer 10 released microsoft internet explorer test drive website supports windows 7 later platform previews support windows 8 internet explorer 10 platform preview 1 supports css3 grid layout css3 flexible box layout css3 multi-column layout css3 gradient full hardware acceleration reviewers responses release internet explorer 10 platform preview varied however noted soon 29 days release internet explorer 9 microsoft began talking next version reisinger eweek listed requested features next version michael muchmore pc magazine tested platform preview 1 performance html5 support microsoft third parties test suites test platform preview 1 performed better internet explorer 9 always better competing web browsers september 13 2011 microsoft released developer preview windows 8 general public came internet explorer developer preview first full browser incarnation internet explorer 10 although internet explorer last major web browser – among mozilla firefox google chrome opera safari – support spell checking first desktop browser windows support autocorrection internet explorer 10 released manufacturing along windows 8 windows server 2012 latter reached general availability september 4 2012 former reached general availability october 26 2012 preview internet explorer 10 windows 7 windows server 2008 r2 released november 13 2012 compatible previous versions windows windows 8 internet explorer 10 includes built-in adobe flash player microsoft adobe worked together ensure version adobe flash included internet explorer 10 drain battery impact performance negative ways metro version internet explorer features adobe flash included battery life performance security purposes features work well touch also removed metro version internet explorer however originally websites use adobe flash metro version internet explorer microsoft adobe maintain list approved websites reportedly video content games desktop version internet explorer 10 features adobe flash available march 12 2013 microsoft changed behavior allowing sites whitelist display flash content allowing sites display flash content except curated compatibility view cv list blacklist maintained microsoft desktop version internet explorer 10 available windows 7 windows 8 retains user interface ui internet explorer 9 minor refinements removing gradients metro version internet explorer 10 available windows 8 includes new ui hidden webpage viewed takes entire screen ui revealed right click mouse swipe top bottom edges touchscreen ui shown tabs listed top screen small preview webpage tab button add new tab placed top-right corner bottom screen address bar navigational buttons shown navigational buttons include back button navigate previous page refresh button reload active page pin button create new shortcut tile active page start screen wrench-shaped icon opens menu ie10 contains options view desktop opens current webpage desktop version internet explorer 10 find page find text string word phrase arbitrary set letters active page internet explorer 10 also introduces new feature called flip ahead works metro desktop versions internet explorer 10 allows users move articles span multiple pages well search results web pages next page similar button feature turned default user browsing history sent microsoft order provide feature according windows supersite microsoft said sites may need updated ensure work intended internet explorer 10 longer features supports following windows phone developer summit june 2012 joe belfiore announced windows phone 8 due towards end 2012 include mobile version internet explorer 10 offers four times faster javascript performance two times support html 5 features includes microsoft smartscreen supports touch html5 apps internet explorer 10 new user agent string following general format depending system different parts user string may change last token touch appears systems equipped touchscreen platform token may following
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Operating systems
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nettransformer nettransformer cross-platform network discovery program software created idea discovering set snmp queries ip networks state produce various data models use data models inputs transform network one state another per original phd author used nettransformer demonstrate network transformation isp network ipv4 ipv6 state transformation long lasting process typically driven strategy passes many states example initial state current state network services offered ipv4 long term goal network service ipv6 achieve isp pass many intermediate states depending transformation strategy network mapping perspective nettransformer generates 3 distinct data models software generating topology views network topology diff views network centric data model thus lot people use simply network mapping one important concepts network treated separate project since many kinds networks years appeared various kinds project types example free graph working kind graph using rest diff visualization capabilities software
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Computer security
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snail maze snail maze 1986 video game sega part sega master system instead released cartridge built system bios could played starting system without game cartridge inserted holding buttons 1 2 simultaneously later console models included minimal bios memory constraints snail maze removed systems instead included built alex kidd miracle world sonic hedgehog snail maze never released cartridge card format simple game snail maze involves navigating small orange snail yellow shell blue maze goal area clearly marked players must attempt reach within time limit despite relative simplicity compared games era snail maze could quite challenging subsequent levels reduce time available giving progressively lower margin error snail maze fans worked keep game becoming obscure footnote video game history example 2004 port snail maze made japanese msx computer platform port included enhanced graphics well new title screen version snail maze included coleco sonic handheld system created 2006 port snail maze released december 2015 ti-84 plus ce graphing calculator written ez80 assembly language james vernon
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Computer architecture
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manually annotated sub-corpus masc balanced subset 500k words written texts transcribed speech drawn primarily open american national corpus oanc oanc 15 million word growing corpus american english produced since 1990 public domain otherwise free usage redistribution restrictions masc includes manually validated annotations logical structure headings sections paragraphs etc sentence boundaries three different tokenizations associated part speech tags shallow parse noun verb chunks named entities person location organization date time penn treebank syntax additional manually produced validated annotations produced masc project portions sub-corpus including full-text annotation framenet frame elements 100k+ sentence corpus wordnet 3.1 sense tags one-tenth also annotated framenet frame elements annotations portions sub-corpus wide variety linguistic phenomena contributed projects including propbank timebank mpqa opinion several others co-reference annotations clause boundaries entire masc corpus scheduled released end 2016 wordnet sense annotations occurrences 114 words also included masc distribution well framenet annotations 50-100 occurrences 114 words sentences wordnet framenet annotations also distributed part masc sentence corpus unlike freely available corpora including wide variety linguistic annotations masc contains balanced selection texts broad range genres present masc includes seventeen different types linguistic annotation production ** currently available original format masc annotations whether contributed produced in-house transduced graph annotation format graf defined iso tc37 sc4 ’ linguistic annotation framework laf online tool anc2go transduce annotations parts masc several formats including conll iob format formats use uima general architecture text engineering masc open data resource used anyone purpose time collaborative community resource sustained community contributions annotations derived data freely downloadable masc download page linguistic data consortium masc also distributed part-of-speech-tagged form natural language toolkit
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Computational linguistics
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lga 771 lga 771 also known socket j cpu interface introduced intel 2006 used intel core microarchitecture netburst microarchitecture dempsey based dp-capable server processors dual-core xeon codenamed dempsey woodcrest wolfdale quad-core processors clovertown harpertown yorkfield-cl also used core 2 extreme qx9775 succeeded lga 1366 nehalem-based xeon processors name implies land grid array 771 contacts word socket instance misnomer processor interface pin holes instead 771 protruding lands touch contact points underside microprocessor j socket j refers now-canceled processor codenamed jayhawk expected debut alongside interface intended successor socket 604 takes much design lga 775 almost pin compatible lga 775 socket 771 cpus rotated 90 degrees two pins swapped small adapters developed chinese computer diy enthusiasts available allow lga 771 cpus installed lga 775 motherboards bios microcode supports also able add supportion microcode manually
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Computer architecture
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koding koding development environment automation platform owned koding inc. allows software developers define development environments definition file called stack script file calls various cloud providers provision defined development environment file visible entire team updated administrators account environments provisioned file shared web browser without needs downloading software development kits developers also able download command line tool called kd allows mount provisioned vms computers thus enabling development using developers local ides since platform able create linux vms supports multiple programming languages including c c++ go java node.js perl php python ruby name=ram 2009 kodingen predecessor koding launched included features koding today later application temporarily closed development resulted koding first version koding launched 16 january 2012 private beta public beta began 24 july 2012 final beta version single developer version released public 7 august 2013 march 2016 koding released teams version geared towards enterprises teams developers koding received 20m date khosla ventures series b matrix partners series rtp ventures greycroft partners seed funding koding via environment definition files able create resources cloud providers developers able write code created resources
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Distributed computing architecture
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xplico xplico network forensics analysis tool nfat software reconstructs contents acquisitions performed packet sniffer e.g wireshark tcpdump netsniff-ng unlike protocol analyzer whose main characteristic reconstruction data carried protocols xplico born expressly aim reconstruct protocol application data able recognize protocols technique named port independent protocol identification pipi name xplico refers latin verb explico significance xplico free open-source software subject requirements gnu general public license gpl version 2 clarify xplico imagine raw data ethernet ppp web navigation http protocol case xplico able extract reconstruct web pages contents images files cookies similarly xplico able reconstruct e-mail exchanged imap pop smtp protocols among protocols xplico identifies reconstructs voip msn irc http imap pop smtp ftp xplico software architecture provides output module xplico different user interfaces fact used command line web user interface called xplico interface protocol dissector modules decoding individual protocol protocol dissector reconstruct extract data protocol modules plug-in configuration file loaded execution program allows focus decoding want decode voip calls web traffic configure xplico load rtp sip modules excluding http module another feature xplico ability process reconstruct huge amounts data able manage pcap files multiple gigabytes even terabytes multiple capture probes simultaneously thanks use various types input modules pcap files uploaded many ways directly xplico web user interface sftp transmission channel called pcap-over-ip features xplico used contexts lawful interception network forensics xplico also specific version called pcap2wav able decode voip calls based rtp protocol sip h323 mgcp skinny supports decodidica audio codecs g711ulaw g711alaw g722 g729 g723 g726 msrta microsoft real-time audio examples assumed eth0 used network interface xplico -m rltm -i eth0 xplico -m pcap -f example.pcap xplico -m pcap -d /path/dir/ cases data decoded stored directory named xdecode parameter -m select input module type input module named rltm acquires data directly network interface vice versa input module named pcap acquires data form pcap files directory xplico installed default major distributions digital forensics penetration testing
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Computer security
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palm pixi palm pixi pixi plus multimedia smartphones developed palm purchased 2010 hp device viewed successor palm centro smartphone palm second webos device palm pre phones considered smallest smartphone market able browse internet access facebook social media sites well online banking original pixi announced september 8 2009 palm official blog released november 15 2009 sprint carrier network u.s pixi plus announced ces 2010 plus versions include wifi ability act 3g mobile hotspot sometimes known mifi phone released january 7 2010 verizon wireless carrier network subsequently mobility released may 28 2010 o2 united kingdom pixi touch screen capability qwerty keyboard access battery interior hardware phone metal faceplate sits plastic backing palm inc. detailed specifications palm pixi company product web page according information given pixi features 2.63-inch capacitive touchscreen 18-bit color 320x400 screen resolution sub-hvga display device weighs 92.5 grams 3.51 ounces 55.0 mm 2.17 inches width 111.0 mm 4.37 inches height 10.85 mm 0.43 inches thick board radios include gps dual-band cdma2000 3g evdo rev data networking e-mail supports microsoft exchange services direct push well pop3 imap yahoo mail gmail aol microsoft outlook messaging features include im sms mms features 2 megapixel camera led flash proximity sensor accelerometer bluetooth 2.1 a2dp stereo microusb connector 3.5 mm headphone jack 8 gigabytes flash memory roughly 7 gigabytes available user like palm pre pixi features webos includes over-the-air synergy synchronization pixi plus display pixi hardware specs include qualcomm msm7627 600mhz cpu adreno 200 graphics 8gb storage 256 mb ram 802.11 b/g wifi bluetooth 2.1 capable using hsdpa 3.6 mbit/s well gprs offers a-gps navigation location services battery changeable 1,150 mah unit 5.5h talk time 2g 350h standby according manufacturer camera 2 megapixel device rear led flash
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Operating systems
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catamount operating system catamount operating system supercomputers catamount lightweight kernel provides basic functionality aims efficiency roots catamount go back 1991 sunmos developed sandia national laboratories university new mexico lightweight operating system cray xt3 uses catamount compute nodes linux server nodes case study ieee assessed performance particle transport code awe cray xt3 8,000-core supercomputer running images catamount cray linux environment cle operating systems work demonstrated running number small benchmarks test machine possible speculate performance impact upgrading one operating system another system whole study findings allows researchers minimise system downtime exploring software-system upgrades results show benchmark tests run less 256 cores would suggest impact upgrading operating system cle less 10
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Operating systems
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linux kernel interfaces linux kernel provides several interfaces user-space applications used different purposes different properties design two types application programming interface api linux kernel confused kernel–user space api kernel internal api linux api kernel–user space api allows programs user space access system resources services linux kernel composed system call interface linux kernel subroutines gnu c library glibc focus development linux api provide usable features specifications defined posix way reasonably compatible robust performant provide additional useful features defined posix kernel–user space apis systems implementing posix api also provide additional features defined posix linux api choice kept stable decades never breaks stability guarantees portability source code time linux kernel developers historically conservative meticulous introducing new system calls much available free open-source software written posix api since much development flows linux kernel compared posix-compliant combinations kernel c standard library linux kernel api augmented additional features far additional features provide technical advantage programming linux api preferred posix-api well-known current examples udev systemd weston people lennart poettering openly advocate prefer linux api posix api offers advantages fosdem 2016 michael kerrisk explained perceived issues linux kernel user-space api describing contains multiple design errors non-extensible unmaintainable overly complex limited purpose violation standards inconsistent mistakes fixed would break abi kernel presents user space system call interface denomination entirety implemented available system calls kernel various subsystems e.g drm define system calls entirety called system call interface various issues organization linux kernel system calls publicly discussed issues pointed andy lutomirski michael kerrisk others gnu c library wrapper around system calls linux kernel combination linux kernel system call interface glibc builds linux api unix-like systems additional capabilities linux kernel exist part posix drm paramount development implementations well-defined performant free open-source graphics device drivers without rendering acceleration would available even worse 2d drivers would available x.org server drm developed linux since ported operating systems well term linux abi refers kernel–user space abi application binary interface refers compiled binaries machine code abi therefore bound instruction set defining useful abi keeping stable less responsibility linux kernel developers developers gnu c library task linux distributions independent software vendor isvs wish sell provide support proprietary software binaries single linux abi opposed supporting multiple linux abis abi defined every instruction set x86 x86-64 mips armv7-a 32-bit armv8-a 64-bit etc endianness supported able compile software different compilers definitions specified abi achieve full binary compatibility compilers free open-source software e.g gnu compiler collection llvm/clang end-users fact interested linux api windows api abis lot kernel-internal apis subsystems interface one another kept fairly stable guarantee stability case new research insights make change seem favorable api changed necessary rewrite testing done author linux kernel monolithic kernel hence device drivers kernel components ease burden companies maintaining proprietary device drivers out-of-tree stable apis device drivers repeatedly requested linux kernel developers repeatedly denied guaranteeing stable in-kernel apis device drivers guaranteeing would faltered development linux kernel past would still future due nature free open-source software necessary ergo choice linux kernel stable in-kernel api since stable in-kernel apis stable in-kernel abis several use cases linux api considered low-level higher abstraction apis used course still need work top low-level linux apis examples
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Computer architecture
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instruction unit instruction unit iu also called instruction fetch unit ifu instruction issue unit isu central processing unit cpu responsible organising program instructions fetched memory executed appropriate order part control unit turn part cpu simplest style computer architecture instruction cycle rigid runs exactly specified programmer instruction fetch part cycle value instruction pointer ip register address next instruction fetched value placed address bus sent memory unit memory unit returns instruction address latched instruction register ir value ip incremented over-written new value case jump branch instruction ready next instruction cycle becomes lot complicated though performance-enhancing features added instruction pipelining out-of-order execution even introduction simple instruction cache
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Computer architecture
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grammar-oriented programming grammar-oriented programming gop grammar-oriented object design good good designing creating domain-specific programming language dsl specific business domain good used drive execution application used embed declarative processing logic context-aware component cac context-aware service cas good method creating maintaining dynamically reconfigurable software architectures driven business-process architectures business compiler used capture business processes within real-time workshops various lines business create executable simulation processes used instead using one dsl entire programming activity good suggests combination defining domain-specific behavioral semantics conjunction use traditional general purpose programming languages
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Programming language topics
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powerbook 150 powerbook 150 laptop personal computer created apple computer inc. introduced july 13 1994 released july 18 1994 last member powerbook 100 series use original case design affordable series introduced priced 1,450 1,600 also last consumer model 8 mhz faster predecessor powerbook 145b lacked adb port used lower-quality passive matrix display contemporary offerings reduce price also lacked external monitor support like duos powerbook 100 150 single serial printer port however third party adapter available use optional modem slot though used 140 case design internals based powerbook duo 230 actually similar features powerbook 190 used powerbook 5300 case design notably new logicboard design allowed 100 series powerbook use 14 mb ram first time well first macintosh ever use less expensive larger ide drives formatting required unique software application limiting selection compatible drives also first 100 series include lithium-ion backup battery preserve ram contents battery replaced last powerbook model include trackball however like 145b replaced 150 could used scsi disk mode unlike duo 190 5300 hd target mode implemented
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Computer architecture
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race condition race condition race hazard behavior electronics software system system substantive behavior dependent sequence timing uncontrollable events becomes bug one possible behaviors undesirable term race condition already use 1954 example david a. huffman doctoral thesis synthesis sequential switching circuits race conditions occur especially logic circuits multithreaded distributed software programs typical example race condition may occur logic gate combines signals traveled along different paths source inputs gate change slightly different times response change source signal output may brief period change unwanted state settling back designed state certain systems tolerate glitches output functions clock signal systems contain memory example system rapidly depart designed behaviour effect temporary glitch becomes permanent glitch consider example two-input gate fed logic signal one input negation another input theory output never true however changes value take longer propagate second input first changes false true brief period ensue inputs true gate output also true design techniques karnaugh maps encourage designers recognize eliminate race conditions cause problems often logic redundancy added eliminate kinds races well problems logic elements enter metastable states create problems circuit designers critical race condition occurs order internal variables changed determines eventual state state machine end non-critical race condition occurs order internal variables changed determine eventual state state machine end static race condition occurs signal complement combined together dynamic race condition occurs results multiple transitions one intended due interaction gates eliminated using two levels gating essential race condition occurs input two transitions less total feedback propagation time sometimes cured using inductive delay line elements effectively increase time duration input signal race conditions arise software application depends sequence timing processes threads operate properly electronics critical race conditions result invalid execution bugs critical race conditions often happen processes threads depend shared state operations upon shared states critical sections must mutually exclusive failure obey rule opens possibility corrupting shared state concept called data race type race condition data races important parts various formal memory models notably memory model defined c11 c++11 standards specify c c++ program containing data race undefined behavior race conditions reputation difficult reproduce debug since end result nondeterministic depends relative timing interfering threads problems occurring production systems therefore disappear running debug mode additional logging added attaching debugger often referred heisenbug therefore better avoid race conditions careful software design rather attempting fix afterwards simple example let us assume two threads want increment value global integer variable one ideally following sequence operations would take place case shown final value 2 expected however two threads run simultaneously without locking synchronization outcome operation could wrong alternative sequence operations demonstrates scenario case final value 1 instead expected result 2 occurs increment operations mutually exclusive mutually exclusive operations interrupted accessing resource memory location regard data races subset race conditions precise definition data race specific formal concurrency model used typically refers situation memory operation one thread could potentially attempt access memory location time memory operation another thread writing memory location context dangerous implies data race different race condition possible nondeterminism due timing even program without data races example program memory accesses use atomic operations dangerous many platforms two threads write memory location time may possible memory location end holding value arbitrary meaningless combination bits representing values thread attempting write could result memory corruption resulting value one neither thread attempted write sometimes called 'torn write similarly one thread reads location another thread writing may possible read return value arbitrary meaningless combination bits representing value memory location held write bits representing value written many platforms special memory operations provided simultaneous access cases typically simultaneous access using special operations safe simultaneous access using memory operations dangerous sometimes special operations safe simultaneous access called atomic synchronization operations whereas ordinary operations unsafe simultaneous access called data operations probably term data race many platforms race condition involving synchronization operations race may nondeterministic otherwise safe data race could lead memory corruption undefined behavior precise definition data race differs across formal concurrency models matters concurrent behavior often non-intuitive formal reasoning sometimes applied c++ standard draft n4296 2014-11-19 defines data race follows section 1.10.23 page 14 two actions potentially concurrent execution program contains data race contains two potentially concurrent conflicting actions least one atomic neither happens except special case signal handlers described omitted data race results undefined behavior parts definition relating signal handlers idiosyncratic c++ typical definitions data race paper detecting data races weak memory systems provides different definition two memory operations conflict access location least one write operation ... two memory operations x sequentially consistent execution form race 〈x y〉 iff x conflict ordered hb1 relation execution race 〈x y〉 data race iff least one x data operation two memory operations accessing location one write hb1 relation defined elsewhere paper example typical happens-before relation intuitively prove situation one memory operation x guaranteed executed completion another memory operation begins say x happens-before neither x happens-before happens-before x say x ordered hb1 relation clause ... ordered hb1 relation execution intuitively translated ... x potentially simultaneous paper considers dangerous situations least one memory operations data operation parts paper paper also defines class synchronization operations safe potentially simultaneous use contrast data operations java language specification provides different definition two accesses reads writes variable said conflicting least one accesses write ... program contains two conflicting accesses §17.4.1 ordered happens-before relationship said contain data race ... data race cause incorrect behavior returning wrong length array critical difference c++ approach java approach c++ data race undefined behavior whereas java data race merely affects inter-thread actions means c++ attempt execute program containing data race could still adhering spec crash could exhibit insecure bizarre behavior whereas java attempt execute program containing data race may produce undesired concurrency behavior otherwise assuming implementation adheres spec safe important facet data races contexts program free data races guaranteed execute sequentially consistent manner greatly easing reasoning concurrent behavior program formal memory models provide guarantee said exhibit sc drf sequential consistency data race freedom property approach said achieved recent consensus presumably compared approaches guarantee sequential consistency cases approaches guarantee example java guarantee directly specified program correctly synchronized sequentially consistent executions free data races program correctly synchronized executions program appear sequentially consistent §17.4.3 extremely strong guarantee programmers programmers need reason reorderings determine code contains data races therefore need reason reorderings determining whether code correctly synchronized determination code correctly synchronized made programmer need worry reorderings affect code program must correctly synchronized avoid kinds counterintuitive behaviors observed code reordered use correct synchronization ensure overall behavior program correct however use allow programmer reason possible behaviors program simple way behavior correctly synchronized program much less dependent possible reorderings without correct synchronization strange confusing counterintuitive behaviors possible contrast draft c++ specification directly require sc drf property merely observes exists theorem providing note shown programs correctly use mutexes memory_order_seq_cst operations prevent data races use synchronization operations behave operations executed constituent threads simply interleaved value computation object taken last side effect object interleaving normally referred “ sequential consistency ” however applies data-race-free programs data-race-free programs observe program transformations change single-threaded program semantics fact single-threaded program transformations continue allowed since program behaves differently result must perform undefined operation.— end note note c++ draft specification admits possibility programs valid use synchronization operations memory_order memory_order_seq_cst case result may program correct guarantee sequentially consistency provided words c++ correct programs sequentially consistent approach thought give c++ programmers freedom choose faster program execution cost giving ease reasoning program various theorems often provided form memory models provide sc drf guarantees given various contexts premises theorems typically place constraints upon memory model therefore upon implementation also upon programmer say typically case programs meet premises theorem could guaranteed execute sequentially consistent manner drf1 memory model provides sc drf allows optimizations wo weak ordering rcsc release consistency sequentially consistent special operations vax memory model data-race-free-0 memory models plpc memory model provides sc drf allows optimizations tso total store order pso pc processor consistency rcpc release consistency processor consistency special operations models drfrlx provides sketch sc drf theorem presence relaxed atomics many software race conditions associated computer security implications race condition allows attacker access shared resource cause actors utilize resource malfunction resulting effects including denial service privilege escalation specific kind race condition involves checking predicate e.g authentication acting predicate state change time check time use kind bug exists security-sensitive code security vulnerability called time-of-check-to-time-of-use tocttou bug created race conditions also intentionally used create hardware random number generators physically unclonable functions pufs created designing circuit topologies identical paths node relying manufacturing variations randomly determine paths complete first measuring manufactured circuit specific set race condition outcomes profile collected circuit kept secret order later verify circuit identity two programs may collide attempts modify access file system result data corruption privilege escalation file locking provides commonly used solution cumbersome remedy involves organizing system way one unique process running daemon like exclusive access file processes need access data file via interprocess communication one process requires synchronization process level different form race condition exists file systems unrelated programs may affect suddenly using available resources disk space memory space processor cycles software carefully designed anticipate handle race situation may become unpredictable risk may overlooked long time system seems reliable eventually enough data may accumulate enough software may added critically destabilize many parts system example occurred near loss mars rover spirit long landing solution software request reserve resources need beginning task request fails task postponed avoiding many points failure could occurred alternatively points equipped error handling success entire task verified afterwards continuing common approach simply verify enough system resources available starting task however may adequate complex systems actions running programs unpredictable networking consider distributed chat network like irc user starts channel automatically acquires channel-operator privileges two users different servers different ends network try start same-named channel time user respective server grant channel-operator privileges user since neither server yet received server signal allocated channel problem largely solved various irc server implementations case race condition concept shared resource covers state network channels exist well users started therefore privileges server freely change long signals servers network changes update conception state network however latency across network makes possible kind race condition described case heading race conditions imposing form control access shared resource—say appointing one server control holds privileges—would mean turning distributed network centralized one least one part network operation race conditions also exist computer program written non-blocking sockets case performance program dependent speed network link software flaws life-critical systems disastrous race conditions among flaws therac-25 radiation therapy machine led death least three patients injuries several another example energy management system provided ge energy used ohio-based firstenergy corp among power facilities race condition existed alarm subsystem three sagging power lines tripped simultaneously condition prevented alerts raised monitoring technicians delaying awareness problem software flaw eventually led north american blackout 2003 ge energy later developed software patch correct previously undiscovered error neuroscience demonstrating race conditions occur mammal rat brains well many software tools exist help detect race conditions software largely categorized two groups static analysis tools dynamic analysis tools thread safety analysis static analysis tool annotation-based intra-procedural static analysis originally implemented branch gcc reimplemented clang supporting pthreads dynamic analysis tools include several benchmarks designed evaluate effectiveness data race detection tools
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Computer security
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sixa sixa inc. cloud-computing startup company lets users on-demand access personal virtual computer company founded september 2015 headquartered san francisco california company offers custom computers developers designers gamers relevant preinstalled software service allows users access powerful cloud computer device eliminates need buy new hardware computational power needed service available windows mac os x android operating systems sixa backed combinator join summer 2016 batch july 2016 raised 261,000 funding startupbootcamp istanbul ws investments combinator starting december 2016 sixa service publicly available usage part launch company raised 3.5 million seed investment round led tandem capital
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Distributed computing architecture
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ios 9 ios 9 ninth major release ios mobile operating system developed apple inc. successor ios 8 announced company worldwide developers conference june 8 2015 released september 16 2015 succeeded ios 10 september 13 2016. ios 9 incorporated many feature updates built-in apps notably notes received ability draw sketches different tools image insertion prominent visual appearance website links map locations advanced list formatting all-new apple news app aggregates articles different sources apple maps received mass transit support although limited number locations launch major new system updates include proactivity siri advanced search combined make operating system contextually aware information time location provide user information ahead time searching proactive intelligence display instant results widget-like format including weather sports news ios 9 also added multiple forms multitasking ipad ios 9.3 apple added night shift mode changes color device display warmer less blue light shade prevent potential negative screen effect users circadian rhythms additionally ios 9 brought new user experience functions including quick actions peek pop based touch-sensitive display technology iphone 6s quick actions shortcuts home screen app icons users preview peek content without moving away current screen enter pop previewed content full view reception ios 9 positive critics praised proactivity siri making notification center central location information potential future updates improve functionality new multitasking features ipad complimented drawing photo insertion notes app however apple news criticized low number decent-looking articles apple maps criticized limited geographical availability mass transit support five days release apple announced ios 9 installed 50 active ios devices apple described fastest adoption rate ever new operating system ios 9 introduced apple worldwide developers conference june 8 2015 first beta made available registered developers keynote public beta made available july marked first time general public able test new versions ios official release eddy cue apple senior vice president internet software services telling fast company public beta program started maps referring company apple maps launch significant issues early days ios 9 officially released september 16 2015. ios 9.0.1 released september 23 2015 first update ios 9 fixed playback issues alarms timers made setup assistant work properly resolved distortion paused frames video playback photos safari ios 9.0.2 released september 30 2015 fix multiple bugs including lock screen bypass issue ios 9.1 released october 21 2015 update included support ipad pro apple pencil 4th-generation apple tv also added support 150 new emoji part unicode 7.0 8.0 emoji standards live photos intelligently sense user raises lowers phone n't record movements bug fixes improvements security performance also included ios 9.2 released december 8 2015 update included arabic language support siri iphone support apple lightning-to-sd-card reader accessory lets users transfer photos videos sd card commonly used dslr cameras iphone without need computer ios 9.2 also included new visual download indicator apple music support wi-fi calling users along bug fixes stability improvements ios 9.2.1 released january 19 2016 bug fixes february 18 2016 second version ios 9.2.1 released fix bricking issue impacted iphones touch id sensors repaired third-party ios 9.3 released march 21 2016 new 3d touch quick actions several apple built-in apps night shift mode notes password protection touch id news better personalized recommendations support in-line video iphone landscape view health activity view carplay updates apple music apple maps new languages siri multi-user mode ipad education support pairing multiple apple watches one iphone wi-fi calling verizon users support playing videos encoded dolby digital plus audio streams select lightning-equipped ios devices well major bug fixes ios 9.3.1 released march 31 2016 fix issue caused apps become unresponsive crash tapping links ios 9.3.2 released may 16 2016 update made possible use night shift low power mode simultaneously previously possible also fixed bluetooth issue iphone se however ios 9.3.2 bricked 9.7-inch ipad pros preventing used apple pulled update ipad pro may 20 2016 re-released 9.3.2 device june 2 2016 fixing issue ios 9.3.3 released july 18 2016 bug fixes performance improvements ios 9.3.4 released august 4 2016 fix memory corruption issue could enable app execute arbitrary code kernel privileges update consequently patched ios jailbreaking method used chinese programming group pangu team ios 9.3.5 released august 25 2016 fix three critical security vulnerabilities user clicked malicious link jailbreak enabled device installed spyware pegasus intercept collect information device well activate microphone track device location spyware used strong encryption avoid detection ios 9.3.6 released july 22 2019 address issue could impact gps location performance could cause system date time incorrect update available iphone 4s cellular models ipad mini 1st generation ipad 2 ipad 3rd generation iphone 6s iphone 6s plus touch-sensitive display feature called 3d touch incorporated ios 9 similar force touch found trackpad apple macbook computers quick actions shortcuts added apps support 3d touch feature triggered pressing slightly harder app icon also introduces actions known peek pop lets users firmly hold preview peek kind content hovering window optionally apply pressure enter pop content full view taptic engine iphone 6s provides haptic feedback time users press screen harder ios 9 comes two important battery-saving updates phone placed face-down screen light upon receiving notifications apple also added low power mode modifies amount energy dedicated background services animations example background app refresh push email paused low power mode phone reaches 20 battery level users automatically prompted turn low power mode changes color battery icon top row status bar screen yellow battery goes higher 80 level low power mode automatically turns back san francisco new system font replaced helvetica neue system typeface ios ios 9 added new battery widget notification center displayed battery life charging status connected bluetooth device shift button inactive lowercase letters displayed keyboard instead all-caps representation previous ios versions ios 9 smaller update ios 8 requiring 1.3 gb space compared 4.58 gb ios 8 additionally ios 9 includes option temporarily delete apps allow update install update installed apps automatically restored ios 9 also features app thinning functionality whereby necessary assets needed run apps individual device downloaded rather entire app potentially saving space ios 9 adds number features ipad improve productivity include slide split screen picture picture enhanced multitasking similar experience found os x el capitan slide allows user pull second app swipe right edge display app takes 1/3 screen sticks right side screen interactivity within full-screen app disabled left inactive background feature allows users perform quick tasks dismiss app user taps handle next slide window extends window towards left screen user enters split screen allows interact two apps simultaneously side-by-side 50/50 split users also switch another app either slide mode split screen view pulling handle top either app selecting another app list replace existing one picture picture mode allows users minimize facetime calls supported videos smaller window continue watching tasks ipad split screen multitasking feature available ipad air 2 ipad mini 4 ipad pro slide picture picture features available ipad air ipad air 2 ipad mini 2 newer ipad pro banner notifications tapped causing another app open back button top-left corner screen added bringing user back previous app night shift display mode introduced ios 9.3 mode shifts colors device display warmer similar f.lux popular program microsoft windows apple macos computers enabled uses device clock geographic location determine turn feature optionally user set manual schedule schedule ease access new night shift toggle control center settings night shift located display brightness settings app top enabling feature setting schedule user also set warmth display despite introduced ios 9.3 march 2016 n't possible use night shift low power mode simultaneously release ios 9.3.2 two months later night shift requires 64-bit processor found apple a7 newer chips means older ios devices including iphone 4s iphone 5 iphone 5c ipad 2 ipad 3 ipad 4 first-generation ipad mini ipod touch 5 receive night shift mode ios 9 includes performance speed improvements thanks expanded use metal api metal introduced ios 8 previously limited game developers ios 9 use metal expanded let handle many core user interface elements graphics intelligence one main features ios 9 consisting newly integrated siri search previously known spotlight well proactivity throughout operating system ios aware contextual information time location proactively provides user may need advance save time effort typing search also improved display instant answers at-a-glance widget-like format similar provided siri interface search display current weather sports scores news search screen proactive suggestions accessed either pulling notifications window safari web browser search bar left home screen intelligence also extends apps instance mail events automatically added calendar details found message content likely additional recipients suggested message composition siri also aware currently screen engaged holding home button ios 9 introduces multiple security enhancements introduces 6-digit passcode default extra two digits previous 4-digit default well support two-factor authentication original ios 9 release september 2015 fixed security issue within previous ios versions flaw allowed anyone within range airdrop user install malware target device tweak ios settings exploit would still work victim rejected incoming airdrop file settings app ios 9 search bar makes easier find settings options user also options notifications grouped app came ability turn shake undo ipad two-finger drag keyboard moves cursor freely like traditional trackpad making positioning cursor selecting text easier keyboard-to-trackpad feature also extended iphone 6s 6s plus users 3d touch force press keyboard enable trackpad also ipad shortcut bar added cut copy paste undo redo functions folders display 16 apps per page 4-by-4 arrangement compared 9 iphone allowing increased total 240 apps single folder ios 9 introduced wi-fi assist feature default automatically switches phone cellular data wi-fi connection spotty whenever user presented flight information user click link view preview flight ios 9.3 pdfs saved ibooks application via safari itunes synced icloud ios 9 setting enables icloud drive app home screen icloud drive lets user save browse files folders icloud health app introduced ios 8 received landscape mode iphone also added support reproductive health uv exposure water intake sedentary state data types ios 9.3 also tracks sleep exercise weight apple watch messages app allows user search text text highlighted scrolled apple maps adds support transit directions baltimore berlin chicago london los angeles mexico city new york city paris philadelphia san francisco toronto washington d.c. along 300 locations china maps app also enhanced location details including nearby feature recommends shops restaurants places drink close proximity user places serving food users specify exactly type food want ios 9 includes new apple news app replacing newsstand app aggregates news different sources similar style flipboard app features mobile-formatted layout loads quickly informative animations full-bleed images additionally news supports rss feeds safari web browser launch news app available united states expanded united kingdom australia ios 9.1 update march 2016 apple opened news platform news agencies including independent bloggers notes app received number enhancements ios 9 including ability draw sketches number different tools including ruler straight lines images also added links websites map locations get prominent visual appearance added notes ipad iphone landscape mode notes range color options drawing well eraser advanced formatting options including checked bulleted dashed numbered lists app also supports icloud allows easy folder creation secure notes feature introduced ios 9.3 lets ios user protect notes either passcode touch id photos app ios 9 included improved scrubber bar photo viewer screenshots selfies albums ability hold select multiple photos easily without delete individually also allows user hide sensitive material new hide option app also allows user pinch-to-zoom playing video release ios 9 safari web browser allows third-party content blocking apps safari also allows users customize appearance reader mode options font background color days release ios 9 ad blocking software topped app store charts marco arment developer peace app saying web advertising behavioral tracking control ... 're unacceptably creepy bloated annoying insecure 're getting worse alarming pace passbook application renamed wallet ios 9 includes many new changes support store loyalty cards gift cards discover credit/debit cards apple pay uk wallet app also accessed lock screen ios 9.3 music api allows developers integrate apps apple music streaming service ios 9 received mostly positive reviews dan seifert verge praised improvements proactivity siri highlighting notification drop-down contains information user needs although pointed google google microsoft cortana personal assistants offer similar services sometimes better varied ways achieving results improvements ios lay foundation even capabilities future chris velazco engadget liked small thoughtful design changes impressed new multitasking features ipad referring split screen lovely little feature however criticize low number decent-looking articles apple news writing 'll notice discrepancy articles handled -- formatted text white background outlet logo top also noted limited number locations apple maps launch supported mass transit directions matt swider techradar wrote siri proactivity lists robust enjoyed notifications sorted chronologically rather app samuel gibbs guardian welcomed changes built-in apps drawing photo insertion notes unknown number identification emails phone siri automatically launching music app upon plugging headphones also praised updates keyboard calling much easier use apple facing 5 million lawsuit allegedly slowing iphone 4s ios 9 according lawsuit ios 9 update slowed iphone 4s point phone unusable performance sluggish apple knew fact planned obsolescence september 21 2015 apple announced ios 9 installed 50 active ios devices measured app store according apple fastest adoption rate ever new operating system february 2016 news outlets reported users updated ios 9 particular device components repaired third-party notably touch id fingerprint recognition sensor rendered phone bricked issue named error 53 according ifixit limited iphone 6 6 plus devices apple stated protect fingerprint data using secure enclave uniquely paired touch id sensor iphone serviced authorised apple service provider apple retail store changes affect touch id sensor pairing re-validated ... check ensures device ios features related touch id remain secure without unique pairing malicious touch id sensor could substituted thereby gaining access secure enclave ios detects pairing fails touch id including apple pay disabled device remains secure apple released new version ios 9.2.1 later february fix issue february 2016 bug discovered could permanently disable 64-bit devices bug setting time 1 january 1970 would cause device get stuck reboot process ios 9.3 released march 21 2016 fixed issue may 2016 apple released ios 9.3.2 update followed reports bricked 9.7-inch ipad pros connect itunes message error 56 message itunes could n't restore tablet apple temporarily stopped offering 9.3.2 update re-release version june 2016 fixed issue release ios 9.3.3 july 2016 followed reports ibooks store crashed however apple explained august timing coincidence ibooks app crash result server issue software update release ios 9.3.5 august 2016 fixed three critical security vulnerabilities vulnerabilities could exploited silently enable jailbreak allow malicious installation spyware called pegasus pegasus could intercept read text messages emails track calls trace phone location activate microphone gather information apps including limited imessage gmail viber facebook whatsapp telegram skype discovery vulnerabilities dated 10 days 9.3.5 update released arab human rights defender ahmed mansoor received suspicious text message link sent citizen lab investigation ensued collaboration lookout revealed mansoor clicked link would jailbroken phone implanted spyware citizen lab linked attack israeli surveillance company known nso group sells pegasus governments lawful interception regarding widespread issue lookout explained blog post believe spyware wild significant amount time based indicators within code pointed code shows signs kernel mapping table values way back ios 7 news spyware received significant media attention particularly called sophisticated smartphone attack ever first time iphone history remote jailbreak exploit detected july 2017 information critical wi-fi security vulnerability affecting one billion ios android devices published issue named broadpwn allows attacker remotely take control nearby vulnerable smartphones turn affected devices rogue access points spreading infection nearby devices apple released security patch issue part ios 10.3.3 update though older devices running ios 9 including ipad 2 iphone 4s left without available update causing concerns safety product schools release apple drop support ios devices devices supporting ios 8 also able run ios 9
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Operating systems
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vmebus vmebus versa module europa versa module eurocard bus computer bus standard originally developed motorola 68000 line cpus later widely used many applications standardized iec ansi/ieee 1014-1987 physically based eurocard sizes mechanicals connectors din 41612 uses signalling system eurocard define first developed 1981 continues see widespread use today 1979 development motorola 68000 cpu one engineers jack kister decided set creating standardized bus system 68000-based systems motorola team brainstormed days select name versabus versabus cards large used edge connectors products adopted including ibm system 9000 instrument controller automatix robot machine vision systems kister later joined john black refined specifications created versamodule product concept young engineer working black julie keahey designed first versamodule card versabus adaptor module used run existing cards new versabus sven rau max loesel motorola-europe added mechanical specification system basing eurocard standard late standardization process result first known versabus-e later renamed vmebus versamodule eurocard bus although refer versa module europa point number companies involved 68000 ecosystem agreed use standard including signetics philips thomson mostek soon officially standardized iec iec 821 vmebus ansi ieee ansi/ieee 1014-1987 original standard 16-bit bus designed fit within existing eurocard din connectors however several updates system allow wider bus widths current vme64 includes full 64-bit bus 6u-sized cards 32-bit 3u cards vme64 protocol typical performance 40 mb/s associated standards added hot-swapping plug-and-play vme64x smaller 'ip cards plug single vmebus card various interconnect standards linking vme systems together late 1990s synchronous protocols proved favourable research project called vme320 vita standards organization called new standard unmodified vme32/64 backplanes new 2esst protocol approved ansi/vita 1.5 1999 years many extensions added vme interface providing 'sideband channels communication parallel vme examples ip module raceway interlink scsa gigabit ethernet vme64x backplanes pci express rapidio starfabric infiniband vmebus also used develop closely related standards vxibus vpx vmebus strong influence many later computer buses stebus architectural concepts vmebus based versabus developed late 1970s motorola motorola european microsystems group munich west germany proposed development versabus-like product line based eurocard mechanical standard demonstrate concept max loesel sven rau developed three prototype boards 1 68000 cpu board 2 dynamic memory board 3 static memory board named new bus versabus-e later renamed vme short versa module european lyman lym hevle vp motorola microsystems operation later founder vme marketing group subsequently renamed vme international trade association vita early 1981 motorola mostek signetics agreed jointly develop support new bus architecture companies early supporters 68000 microprocessor family john black motorola craig mackenna mostek cecil kaplinsky signetics developed first draft vmebus specification october 1981 system '81 trade show munich west germany motorola mostek signetics/philips thomson csf announced joint support vmebus also placed revision specification public domain august 1982 revision b vmebus specification published newly formed vmebus manufacturers group vita new revision refined electrical specifications signal line drivers receivers brought mechanical specification line developing iec 297 standard formal specification eurocard mechanical formats latter 1982 french delegation international electrotechnical commission iec proposed revision b vmebus international standard iec sc47b subcommittee nominated mira pauker philips france chairperson editorial committee thus formally starting international standardization vmebus march 1983 ieee microprocessor standards committee msc requested authorization establish working group could standardize vmebus us request approved ieee standards board p1014 working group established wayne fischer appointed first chairman working group john black served chairman p1014 technical subcommittee iec ieee vmebus manufacturers group vita distributed copies revision b comment received resulting requests changes document comments made clear time go past revision b december 1983 meeting held included john black mira pauker wayne fischer craig mackenna agreed revision c created take consideration comments received three organizations john black shlomo pri-tal motorola incorporated changes sources common document vmebus manufacturers group labelled document revision c.1 placed public domain ieee labelled p1014 draft 1.2 iec labelled iec 821 bus subsequent ballots ieee p1014 working group msc resulted comments required ieee p1014 draft updated resulted ansi/ieee 1014-1987 specification 1985 aitech developed contract us tacom first conduction-cooled 6u vmebus board although electrically providing compliant vmebus protocol interface mechanically board interchangeable use air-cooled lab vmebus development chassis late 1987 technical committee formed vita direction ieee create first military conduction-cooled 6u x 160mm fully electrically mechanically compatible vmebus board co-chaired dale young dy4 systems doug patterson plessey microsystems radstone technology ansi/ieee-1101.2-1992 later ratified released 1992 remains place conduction-cooled international standard 6u vmebus products 1989 john peters performance technologies inc. developed initial concept vme64 multiplexing address data lines a64/d64 vmebus concept demonstrated year placed vita technical committee 1990 performance enhancement vmebus specification 1991 par project authorization request p1014r revisions vmebus specification granted ieee ray alderman technical director vita co-chaired activity kim clohessy dy-4 systems end 1992 additional enhancements vmebus a40/d32 locked cycles rescinding dtack* autoslot-id auto system controller enhanced din connector mechanicals required work complete document vita technical committee suspended work ieee sought accreditation standards developer organization sdo american national standards institute ansi original ieee par p1014r subsequently withdrawn ieee vita technical committee returned using public domain vmebus c.1 specification base-level document added new enhancements enhancement work undertaken entirely vita technical committee resulted ansi/vita 1-1994 tremendous undertaking document editing accomplished kim clohessy dy-4 systems technical co-chair activity great help frank hom created mechanical drawings exceptional contributions chapter editor additional enhancements proposed vme64 subcommittee placed vme64 extensions document two activities began late 1992 blli vmebus board-level live insertion specifications vsli vmebus system-level live insertion fault tolerance 1993 new activities began base-vme architecture involving implementation high-speed serial parallel sub-buses use i/o interconnections data mover subsystems architectures used message switches routers small multiprocessor parallel architectures vita application recognition accredited standards developer organization ansi granted june 1993 numerous documents including mezzanine p2 serial bus standards placed vita public domain administrator technologies detailed timeline vmebus history found vita website many ways vmebus equivalent analogous pins 68000 run onto backplane however one key features 68000 flat 32-bit memory model free memory segmentation anti-features result vme 68000-like 68000 generic enough make issue cases like 68000 vme uses separate 32-bit data address buses 68000 address bus actually 24-bit data bus 16-bit although 32/32 internally designers already looking towards full 32-bit implementation order allow bus widths vme uses two different eurocard connectors p1 p2 p1 contains three rows 32 pins implementing first 24 address bits 16 data bits control signals p2 contains one row includes remaining 8 address bits 16 data bits bus controlled set nine lines known arbitration bus communications controlled card slot one eurocard chassis known arbiter module two arbitration modes supported round robin prioritized regardless arbitration mode card attempt become bus master holding one four bus request lines low round robin arbitration arbiter cycles amongst bus request lines br0-br3 determine potentially simultaneous requesters granted bus priority arbitration br0-br3 use fixed priority scheme br0 lowest br3 highest arbiter grant bus highest priority requestor arbiter determined bus requests grant asserts corresponding bus grant line bg0 bg3 level bus mastership two masters simultaneously request bus using br line bus grant daisy-chain effectively breaks tie granting bus module closest arbiter master granted bus indicate bus use asserting bus busy bbsy* point master gained access bus write data card drives address address modifier data onto bus drives address strobe line two data strobe lines low indicate data ready drives write pin indicate transfer direction two data strobes *lword line cards indicate data width 8 16 32 bits 64 vme64 card bus address reads data pulls data transfer acknowledge low line transfer complete transfer complete pull bus error line low reading data essentially controlling card drives address bus leaves data bus tri-stated drives read pin slave card drives read data onto data bus drives data strobe pins low data ready signalling scheme asynchronous meaning transfer tied timing bus clock pin unlike synchronous buses pci block transfer protocol allows several bus transfers occur single address cycle block transfer mode first transfer includes address cycle subsequent transfers require data cycles slave responsible ensuring transfers use successive addresses bus masters release bus two ways release done rwd master releases bus completes transfer must re-arbitrate bus every subsequent transfer release request ror master retains bus continuing assert bbsy* transfers ror allows master retain control bus bus clear bclr* asserted another master wishes arbitrate bus thus master generates bursts traffic optimize performance arbitrating bus first transfer burst decrease transfer latency comes cost somewhat higher transfer latency masters address modifiers used divide vme bus address space several distinct sub-spaces address modifier 6 bit wide set signals backplane address modifiers specify number significant address bits privilege mode allow processors distinguish bus accesses user level system level software whether transfer block transfer incomplete table address modifiers vme also decodes seven 68000 interrupt levels onto 7-pin interrupt bus interrupt scheme one prioritized vectored interrupts interrupt request lines irq1 irq7 prioritize interrupts interrupting module asserts one interrupt request lines module bus may potentially handle interrupt interrupt handling module recognizes interrupt request priority handles arbitrates bus usual fashion described performs read interrupt vector driving binary version irq line handles e.g irq5 handled binary 101 onto address bus also asserts iack line along appropriate data transfer strobes width status/id read lword* ds0* ds1* allow status/id read cycles 8 16 32 bit wide transfers existing hardware interrupters use 8 bit status/ids interrupter responds transferring status/id data bus describe interrupt interrupt handling module usually cpu usually use status/id number identify run appropriate software interrupt service routine vme bus transfers dma every card master slave bus standards considerable amount complexity added order support various transfer types master/slave selection instance isa bus features added alongside existing channels model whereby communications handled host cpu makes vme considerably simpler conceptual level powerful though requires complex controllers card developing and/or troubleshooting vme bus examination hardware signals important logic analyzers bus analyzers tools collect analyze decode store signals people view high-speed waveforms leisure vita offers comprehensive faq assist front end design development vme systems computers using vmebus include
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Computer architecture
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matita matita experimental proof assistant development computer science department university bologna tool aiding development formal proofs man-machine collaboration providing programming environment formal specifications executable algorithms automatically verifiable correctness certificates naturally coexist matita based dependent type system known calculus co inductive constructions derivative calculus constructions compatible extent coq word matita means pencil italian simple widespread editing tool reasonably small simple application whose architectural software complexity meant mastered students providing tool particularly suited testing innovative ideas solutions matita adopts tactic-based editing mode xml-encoded proof objects produced storage exchange existential variables native matita allowing simpler management dependent goals matita implements bidirectional type inference algorithm exploiting inferred expected types power type inference system refiner augmented mechanism hints helps synthetizing unifiers particular situations specified user matita supports sophisticated disambiguation strategy based dialog parser typechecker interactive level system implements small step execution structured tactics allowing much better management proof development naturally leading structured readable scripts matita employed cerco certified complexity fp7 european project focused development formally verified complexity preserving compiler large subset c assembler mcs-51 microprocessor matita tutorial provides pragmatic introduction main functionalities matita interactive theorem prover offering guided tour set trivial examples field software specification verification
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Programming language topics
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vsftpd vsftpd secure ftp daemon ftp server unix-like systems including linux licensed gnu general public license supports ipv6 ssl vsftpd supports explicit since 2.0.0 implicit since 2.1.0 ftps vsftpd default ftp server ubuntu centos fedora nimblex slackware rhel linux distributions july 2011 discovered vsftpd version 2.3.4 downloadable master site compromised users logging compromised vsftpd-2.3.4 server may issue smileyface username gain command shell port 6200 issue security hole vsftpd instead unknown attacker uploaded different version vsftpd contained backdoor since site moved google app engine
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Internet protocols
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sqlbits sqlbits largest community-led sql server microsoft data platform conference europe founded 2007 group individuals passionate microsoft sql server azure product suite volunteers include committee members speakers helpers industry sponsors come together provide microsoft sql server education sqlbits held year sessions recorded hosted sqlbits website freely available everyone download one key principles sqlbits community led conference located one specific area uk instead conference reaches sql server community moving event around uk 16 sqlbits conferences date key dates locations listed
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Databases
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dataviva dataviva information visualization engine created strategic priorities office government minas gerais dataviva makes official data exports industries locations occupations available entirety brazil eight apps 100 million possible visualizations first set datum – also available aliceweb – provided mdic ministry development industry foreign trade secex secretariat foreign trade official institution government brazil shows foreign trade statistics exporting municipalities country database provided ministério trabalho e emprego mte – ministry labor employment shows information industries occupations brazil rais – annual social information report platform consists eight core applications allows different ways visualizing data available applications descriptive showing data aggregated various levels simple comparative way treemapping others prescriptive using calculations allow analytic visualization data based theories product space applications generated using d3plus open source javascript library built top d3.js alexander simoes dave landry inspired observatory economic complexity dataviva open data open-source free use tool developed partnership datawheel co-founded mit media lab professor césar hidalgo maintained government minas gerais
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Programming language topics
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socket socket mpga478mt cpu interface introduced intel 2006 intel core line mobile processors socket used intel core products well core-derived dual-core xeon codenamed sossaman also used first generation mobile version intel core 2 duo specifically t5x00 t7x00 merom lines referred napa refresh though line switched socket p santa rosa 2007 typically uses intel 945pm/945gm chipsets support 667 mhz fsb intel pm965/gm965 allows 800 mhz fsb support though socket pm965/gm965 combination less common sossaman xeons use e7520 chipset socket pin-compatible desktop socket mpga478a electrically compatible socket pin-compatible older desktop socket 478 mpga478b newer mobile socket p mpga478mn location one pin also incompatible versions older mobile socket 479 pentium iii-m processors designed first version socket 479 physically fit socket electrically incompatible although conflicting information published 45 nm penryn processors released socket
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Computer architecture
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rohit khare rohit khare computer science entrepreneur active many aspects development world wide web founder ångströ co-founder knownow former director commercenet labs key player microformats community holds ph.d. university california irvine bachelors caltech computer science previously worked internet security w3c also active representational state transfer rest community august 2007 authored arrested paper syndication-oriented architecture variant service-oriented architecture
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Computer security
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event flag event flag process synchronization primitive openvms operating system two possible states set cleared following basic primitive operations provided additional synchronization operations event flags either local per-process common accessible one process process set 64 local flags numbered 0-63 also possible associate process 2 sets common event flags come sets 32 process assign numbers 64-95 96-127 come existence first process associates disappear last process removes association every potentially time-consuming asynchronous system call qio among others includes argument specifying number event flag set completion compare semaphore
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Operating systems
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australian information security association nationally recognised not-for-profit organisation charity australian information security association aisa champions development robust information security sector building capacity professionals australia advancing cyber security safety australian public well businesses governments australia established 1999 aisa become recognised authority information security australia membership 3000 individuals across country aisa caters domains information security industry particular focus sharing expertise field meetings focus groups networking opportunities around australia aisa vision world people businesses governments educated risks dangers cyber attack data theft enable take reasonable precautions protect independent non-profit association created provide leadership development promotion improvement profession strategic plan calls continued work areas advocacy diversity education organisational excellence aisa hosts australia largest independent not-for-profit cyber security conference australian cyber conference https //cyberconference.com.au/ guidelines provide direction post-nominals represented indicate aisa membership status post-nominals letters placed following person ’ last name indicate aisa membership status encourage members use maisa aaisa faisa applicable post-nominals every opportunity including email sign-offs official letters tender documents etc helps raise profile professional status membership aisa post-nominals listed following order
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Computer security
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lot lot player controls one arrow move pellets resemble pachinko balls upper cells four-second delay lower ones without confront evil crab grab player pellets try prevent player scoring cutting elastic crab forced leave board pellets find
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Computer architecture
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1chipmsx one chip msx 1chipmsx d4 enterprise distributional name ese msx system 3 re-implementation msx-2 home computer uses single fpga implement electronics except ram msx-2 including msx-music scc+ audio extensions system housed transparent blue plastic box used standard monitor tv pc keyboard original msx cartridges inserted well sd mmc memory cards external storage medium even though lacks 3.5 disk drive disks supported emulation memory card including support booting msx-dos due vhdl programmable hardware possible give device new hardware extensions simply running reconfiguration program msx-dos one chip-msx equipped two usb connectors used adding supporting vhdl code ese msx system 3 designed ese artists factory distributed 1chipmsx d4 enterprise supposed distributed outside japan bazix however due rohs regulations europe claimed could distributed europe original form european market wait adapted version would produced bazix distributed europe bazix however violation rohs ever proven identifiable components pcb power supply rohs-compliant bazix stopped representative msx association thus bring 1chipmsx western market end msx association dissolved due dispute parties involved resulting shift intellectual property rights concerning msx msx licensing corporation bazix also dissolved dispute made end efforts ambitions bring 1chipmsx western market along projects also dependent japanese partners included also default specifications implemented msx system
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Computer architecture
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romfs computing romfs rom filesystem extremely simple file system lacking many features intended burning important files onto eeprom available linux possibly unix-like systems useful initial rom holding kernel modules loaded later needed small code wise description filesystem layout available lxr -- romfs.txt bo brantén created romfs file system driver windows nt/2k/xp nikolay aleksandrov written romfs image extraction manipulation tool called romfser primarily targeted bsd family operating systems lack support romfs
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Computer file systems
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proven company proven hiring tool content hub small businesses across united states proven software allowed managers post jobs 100 job sites including simply hired craigslist indeed proven proven also offered tools allow users sort evaluate message onboard applicants job seekers could apply directly jobs proven mobile apps proven website proven job board partners proven based san francisco california austin texas used 1,000 small businesses throughout united states proven co-founded pablo fuentes sean falconer joe mellin 2009 company privately held seed investment andreessen horowitz greylock partners kapor capital 500 startups founder collective morado ventures angels august 2012 proven launched free proven job search app ios december 2012 proven job search android launched proven job search allows users search apply jobs directly ios android device users also import resume create one directly within app 2013 proven pivoted become hiring tool job board specifically restaurant hospitality industries proven app remains active tool applicants apply jobs early 2015 proven also rolled onboarding feature stores documents allows applicants sign electronically fall 2015 proven expanded hiring tool job board small businesses industries nationwide august 2019 proven announced acquired upward.net job site headquartered newark california
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Distributed computing architecture
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walkme walkme owned walkme inc. software-as-a-service saas company helps users navigate features web-based services walkme digital adoption platform dap works overlaying information tip-balloons browser window balloons break online processes step-by-step instructions according company dap collects data users behaviors action patterns platforms helps users complete online tasks without leaving screen watch video tutorials read manuals faq pages also allows users automatically get specific guidance according preference language walkme inc. founded 2011 dan adika raphael sweary eyal cohen yuval shalom ozanna april 2012 launched product walkme headquarters san francisco california january 2017 walkme acquired abbi startup specializes mobile a/b testing app engagement walkme retired abbi brand integrated services walkme ’ platform process also migrated abbi ’ existing customers april year walkme acquired jaco
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Web technology
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kyoto common lisp kyoto common lisp kcl implementation common lisp taichi yuasa masami hagiya written c run unix-like operating systems kcl compiled ansi c. conforms common lisp described 1984 first edition guy steele book common lisp language available licence agreement kcl notable implemented scratch outside standard committee solely basis specification one first common lisp implementations ever exposed number holes mistakes specification gone unnoticed
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Programming language topics
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global ideas bank global ideas bank origins lie institute social inventions set 1985 nicholas albery social inventor visionary small beginnings network inventors quarterly newsletter institute grew full-fledged organisation leadership producing annual compendium running social inventions workshops promoting creative solutions around world part first european social innovations exchange 2001 institute awarded margaret mead special recognition award community creativity new century 1995 global ideas bank originally suggested american correspondent gregory wright first established online since become name entire project work work several volunteer programmers technical wizards especially flemming funch new civilization network new features added online submission voting systems categorisation message board
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Databases
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zilog encore 32 zilog encore 32 arm9-based microcontroller zilog inc company second attempt produce arm-based controllers system-on-a-chip includes integrated memory controller interfaces universal serial bus usb liquid crystal display lcd serial peripheral interface bus spi variants include version supporting magnetic stripe reader smart card reader toolkit also includes linux support
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Computer architecture
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shell control box shell control box scb network security appliance controls privileged access remote systems records activities replayable audit trails prevents malicious actions example records system administrator updates file server third-party network operator configures router recorded audit trails replayed like movie review events occurred content audit trails indexed make searching events automatic reporting possible scb linux-based device developed balabit application level proxy gateway 2017 balabit changed name product privileged session management psm repositioned core module privileged access management solution balabit ’ privileged session management psm shell control box scb device controls monitors audits remote administrative access servers network devices tool oversee system administrators controlling encrypted connections used administration psm scb full control ssh rdp telnet tn3270 tn5250 citrix ica vnc connections providing framework solid boundaries work administrators psm scb acts authentication gateway enforcing strong authentication users access assets psm also integrate user directories example microsoft active directory resolve group memberships users access protected servers credentials accessing server retrieved transparently psm ’ credential store third-party password management system psm impersonating authenticated user automatic password retrieval protects confidentiality passwords users never access psm controls audits privileged access wide-spread protocols ssh rdp http detailed access management helps control access servers also possible control advanced features protocols like type channels permitted example unneeded channels like file transfer file sharing disabled reducing security risk server psm policies privileged access enforced one single system avoid accidental misconfiguration human errors psm supports 4-eyes authorization principle achieved requiring authorizer allow administrators access server authorizer also possibility monitor – terminate session administrator real-time watching screen psm monitor network traffic real time execute various actions certain pattern example suspicious command window title text appears screen psm also detect specific patterns credit card numbers case detecting suspicious user action psm send e-mail alert immediately terminate connection example psm block connection destructive administrator command „ rm ” comes effect psm makes user activities traceable recording tamper-proof confidential audit trails records selected sessions encrypted timestamped digitally signed audit trails audit trails browsed online followed real-time monitor activities users psm replays recorded sessions like movie – actions users seen exactly appeared monitor balabit desktop player enables fast forwarding replays searching events example typed commands pressing enter texts seen user case problems database manipulation unexpected shutdown etc circumstances event readily available trails thus cause incident identified addition recording audit trails transferred files also recorded extracted analysis
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Computer security
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transmux transmux transcode-multiplexing signaling format change telecommunications signaling synchronous optical network signals sonet asynchronous ds3 signals ds3 signal multiplexed 28 individual ds1 signals bit-interleaved fashion framing overhead determined intervals sonet differs approach using byte-interleaved synchronous multiplexing technique several variations payload types sonet payload carry multiplexed lower rate streams ds1 e1 ds3 etc well octet-based format tcp/ip atm frame relay ethernet etc cross-connect capability maintained vt1.5 level individual ds1 signals extracted parent ds3 electrical t1 transmuxed individually vt1.5 complete ds3 signal delivered sonet drop entire ds3 transmuxed intact sts container subsequent cross-connect capability exists sonet payload vt1.5 level white rock networks description product transmux support applications conversion ds3 vt1.5 mapped sts-1s required transmux allows ds3 embedded within sts-1 circuit adapted vt1.5 mapped sts-1 without physically terminating circuit ds3 ec-1
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Internet protocols
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patch-through access patch-through access refers security clearance used various applications according application may regarded high low level security clearance
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Computer security
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comparison real-time operating systems list real-time operating systems rtos operating system time taken process input stimulus less time lapsed next input stimulus type
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Operating systems
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chatbot chatbot piece software conducts conversation via auditory textual methods programs often designed convincingly simulate human would behave conversational partner although 2019 far short able pass turing test chatbots typically used dialog systems various practical purposes including customer service information acquisition chatbots use sophisticated natural language processing systems many simpler ones scan keywords within input pull reply matching keywords similar wording pattern database term chatterbot originally coined michael mauldin creator first verbot julia 1994 describe conversational programs today chatbots accessed via virtual assistants google assistant amazon alexa via messaging apps facebook messenger wechat via individual organizations apps websites chatbots classified usage categories conversational commerce e-commerce via chat analytics communication customer support design developer tools education entertainment finance food games health hr marketing news personal productivity shopping social sports travel utilities beyond chatbots conversational ai refers use messaging apps speech-based assistants chatbots automate communication create personalized customer experiences scale 1950 alan turing famous article computing machinery intelligence published proposed called turing test criterion intelligence criterion depends ability computer program impersonate human real-time written conversation human judge sufficiently well judge unable distinguish reliably—on basis conversational content alone—between program real human notoriety turing proposed test stimulated great interest joseph weizenbaum program eliza published 1966 seemed able fool users believing conversing real human however weizenbaum claim eliza genuinely intelligent introduction paper presented debunking exercise artificial intelligence ... machines made behave wondrous ways often sufficient dazzle even experienced observer particular program unmasked inner workings explained ... magic crumbles away stands revealed mere collection procedures ... observer says could written thought moves program question shelf marked intelligent reserved curios ... object paper cause re-evaluation program explained programs ever needed eliza key method operation copied chatbot designers ever since involves recognition clue words phrases input output corresponding pre-prepared pre-programmed responses move conversation forward apparently meaningful way e.g responding input contains word 'mother 'tell family thus illusion understanding generated even though processing involved merely superficial eliza showed illusion surprisingly easy generate human judges ready give benefit doubt conversational responses capable interpreted intelligent interface designers come appreciate humans readiness interpret computer output genuinely conversational—even actually based rather simple pattern-matching—can exploited useful purposes people prefer engage programs human-like gives chatbot-style techniques potentially useful role interactive systems need elicit information users long information relatively straightforward falls predictable categories thus example online help systems usefully employ chatbot techniques identify area help users require potentially providing friendlier interface formal search menu system sort usage holds prospect moving chatbot technology weizenbaum shelf ... reserved curios marked genuinely useful computational methods classic historic early chatbots eliza 1966 parry 1972 recent notable programs include a.l.i.c.e. jabberwacky d.u.d.e agence nationale de la recherche cnrs 2006 eliza parry used exclusively simulate typed conversation many chatbots include functional features games web searching abilities 1984 book called policeman beard half constructed published allegedly written chatbot racter though program released would capable one pertinent field ai research natural language processing usually weak ai fields employ specialized software programming languages created specifically narrow function required example a.l.i.c.e uses markup language called aiml specific function conversational agent since adopted various developers called alicebots nevertheless a.l.i.c.e still purely based pattern matching techniques without reasoning capabilities technique eliza using back 1966 strong ai would require sapience logical reasoning abilities jabberwacky learns new responses context based real-time user interactions rather driven static database recent chatbots also combine real-time learning evolutionary algorithms optimise ability communicate based conversation held still currently general purpose conversational artificial intelligence software developers focus practical aspect information retrieval chatbot competitions focus turing test specific goals two annual contests loebner prize chatterbox challenge latter offline since 2015 however materials still found web archives chatbots used diverse fashion across verticals many different types channel e.g websites social messaging etc business application accelerated rapidly 2019 leading van baker research vice president gartner predict “ 2020 50 medium large enterprises deployed product chatbots many companies chatbots run messaging apps simply via sms used b2c customer service sales marketing 2016 facebook messenger allowed developers place chatbots platform 30,000 bots created messenger first six months rising 100,000 september 2017 since september 2017 also part pilot program whatsapp airlines klm aeroméxico announced participation testing airlines previously launched customer services facebook messenger platform bots usually appear one user contacts sometimes act participants group chat many banks insurers media companies e-commerce companies airlines hotel chains retailers health care providers government entities restaurant chains used chatbots answer simple questions increase customer engagement promotion offer additional ways order 2017 study showed 4 companies used chatbots according 2016 study 80 businesses said intended one 2020 previous generations chatbots present company websites e.g ask jenn alaska airlines debuted 2008 expedia virtual customer service agent launched 2011 newer generation chatbots includes ibm watson-powered rocky introduced february 2017 new york city-based e-commerce company rare carat provide information prospective diamond buyers used marketers script sequences messages similar autoresponder sequence sequences triggered user opt-in use keywords within user interactions trigger occurs sequence messages delivered next anticipated user response user response used decision tree help chatbot navigate response sequnces deliver correct response message companies explore ways use chatbots internally example customer support human resources even internet-of-things iot projects overstock.com one reportedly launched chatbot named mila automate certain simple yet time-consuming processes requesting sick leave large companies lloyds banking group royal bank scotland renault citroën using automated online assistants instead call centres humans provide first point contact saas chatbot business ecosystem steadily growing since f8 conference facebook mark zuckerberg unveiled messenger would allow chatbots app large companies like hospitals aviation organizations architects designing reference architectures intelligent chatbots used unlock share knowledge experience organization efficiently reduce errors answers expert service desks significantly intelligent chatbots make use kinds artificial intelligence like image moderation natural language understanding nlu natural language generation nlg machine learning deep learning nowadays high majority high-tech banking organizations looking integration automated ai-based solutions chatbots customer service order provide faster cheaper assistance clients becoming increasingly technodexterous particularly chatbots efficiently conduct dialogue usually substituting communication tools email phone sms banking area major application related quick customer service answering common requests transactional support several studies accomplished analytics agencies juniper gartner report significant reduction cost customer services leading billions dollars economy next 10 years gartner predicts integration 2020 chatbots least 85 client applications customer service juniper study announces impressive amount 8 billion retained annually 2022 due use chatbots since 2016 facebook allows businesses deliver automated customer support e-commerce guidance content interactive experiences chatbots large variety chatbots facebook messenger platform developed 2016 russia-based tochka bank launched world first facebook bot range financial services particularly including possibility making payments july 2016 barclays africa also launched facebook chatbot making first bank africa france third largest bank total assets société générale launched chatbot called sobot march 2018 80 users sobot express satisfaction tested il never remplace expertise provided human advisor according sg deputy director bertrand cozzarolo several potential advantages using chatbots interaction customer banking chatbots also incorporated devices primarily meant computing toys hello barbie internet-connected version doll uses chatbot provided company toytalk previously used chatbot range smartphone-based characters children characters behaviors constrained set rules effect emulate particular character produce storyline ibm watson computer used basis chatbot-based educational toys companies cognitoys intended interact children educational purposes process building testing deploying chatbots done cloud-based chatbot development platforms offered cloud platform service paas providers oracle cloud platform snatchbot ibm watson cloud platforms provide natural language processing artificial intelligence mobile backend service chatbot development api companies like microsoft azure aarc currently providing bot engines chatbot platforms software developed malicious chatbots frequently used fill chat rooms spam advertisements mimicking human behavior conversations entice people revealing personal information bank account numbers commonly found yahoo messenger windows live messenger aol instant messenger instant messaging protocols also published report chatbot used fake personal ad dating service website tay ai chatbot learns previous interaction caused major controversy due targeted internet trolls twitter bot exploited 16 hours began send extremely offensive tweets users suggests although bot learnt effectively experience adequate protection put place prevent misuse text-sending algorithm pass human instead chatbot message would credible therefore human-seeming chatbots well-crafted online identities could start scattering fake news seem plausible instance making false claims presidential election enough chatbots might even possible achieve artificial social proof creation implementation chatbots still developing area heavily related artificial intelligence machine learning provided solutions possessing obvious advantages important limitations terms functionalities use cases however changing time common ones listed chatbots increasingly present businesses often used automate tasks require skill-based talents customer service taking place via messaging apps well phone calls growing numbers use-cases chatbot deployment gives organisations clear return investment call centre workers may particularly risk ai-driven chatbots study forrester june 2017 predicts 25 today jobs likely impacted ai technologies 2019
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Computational linguistics
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dns rebinding dns rebinding form computer attack attack malicious web page causes visitors run client-side script attacks machines elsewhere network theory same-origin policy prevents happening client-side scripts allowed access content host served script comparing domain names essential part enforcing policy dns rebinding circumvents protection abusing domain name system dns attack used breach private network causing victim web browser access computers private ip addresses return results attacker also employed use victim machine spamming distributed denial-of-service attacks malicious activities attacker registers domain attacker.com delegates dns server attacker control server configured respond short time live ttl record preventing dns response cached victim browses malicious domain attacker dns server first responds ip address server hosting malicious client-side code instance could point victim browser website contains malicious javascript flash scripts intended execute victim computer malicious client-side code makes additional accesses original domain name attacker.com permitted same-origin policy however victim browser runs script makes new dns request domain attacker replies new ip address instance could reply internal ip address ip address target somewhere else internet following techniques attempt prevent dns rebinding attacks
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Computer security
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shadow ram acorn shadow ram acorn bbc microcomputer master-series microcomputer special framebuffer implementation free main memory permit double-buffered graphics bbc micro master-series machines used 8-bit 6502 65c102 processors 16-bit address space address space split 32 kb ram 0x0000 0x7fff 16 kb sideways paged address space 0x8000 0xbfff 16 kb operating system space 0xc000 0xffff video memory allocated 0x7fff downwards necessary 1 kb teletext mode 7 20 kb modes 0-2 32 kb ram available video memory could eat sizable amount memory shadow ram 20 kb block ram sits outside real address space accessed via operating system calls framebuffer running shadow ram memory normally used video free program use shadow ram activated setting most-significant bit memory mode number example use mode 1 shadow ram enabled request mode 129 128 1 switching main shadow memory alternate frames double-buffered video could used acorn provided demonstration program basic showing scrolling cloud animation without double buffering video game firetrack would also use double buffering shadow ram present shadow ram fitted standard model b+ bbc micro bbc master series optional third-party extra feature model model b bbc micro systems
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Operating systems
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federal information security modernization act 2014 federal information security modernization act 2014 pub.l 113-283 s. 2521 commonly referred fisma reform signed federal law president barack obama december 18 2014 passed response increasing amount cyber attacks federal government amended existing laws enable federal government better respond cyber attacks departments agencies earlier version legislation proposed house oversight government reform chairman darrell issa co-sponsored committee ranking member elijah cummins h.r.1163 federal information security amendments act 2013 bill passed u.s. house representatives vote 416-0 final version legislation introduced united states senate committee homeland security governmental affairs thomas carper d–de june 24 2014 passed december 8 2014 senate december 10 2014 house
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Computer security
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coloros coloros operating system created oppo electronics based google operating system android presently oppo launched 6th version major difference google stock android oppo coloros latter additional features features include customizable gestures screen screen communication phone manager lock screen magazines options long screen shot eye protection changing warmer color temperature ftp server others coloros respects looks similar ios made apple coloros removes many settings well ability restrict app background data usage removed data settings entry users may set alarms mobile data reaches certain limit opposed stock android also automatically turn mobile data moreover coloros manages ram peculiarly allows apps games run background forever apps n't force stopped apps individual settings list coloros releases 3.^ https //c.realme.com/in/board/detail/1057096670929485824
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Operating systems
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linux console linux console system console internal linux kernel system console device receives kernel messages warnings allows logins single user mode linux console provides way kernel processes send text output user receive text input user user typically enters text computer keyboard reads output text computer monitor linux kernel supports virtual consoles consoles logically separate access physical keyboard display linux console linux virtual consoles implemented vt subsystem linux kernel rely user space software contrast terminal emulator user space process emulates terminal typically used graphical display environment linux console one first features kernel originally written linus torvalds 1991 see history linux two main implementations framebuffer text mode framebuffer implementation default modern linux distributions together kernel mode setting provides kernel-level support display hardware features showing graphics system booting legacy text mode implementation used pc-compatible systems cga ega mda vga graphics cards non-x86 architectures used framebuffer mode graphics cards implement text mode linux console uses fixed-size bitmap monospace fonts usually defaulting 8x16 pixels per character linux console optional kernel feature embedded linux systems enable systems typically provide alternative user interface e.g web based boot immediately graphical user interface use primary means interacting user implementations linux console include braille console support refreshable braille displays serial port console linux console provides way kernel processes output text-based messages user receive text-based input user linux several devices used system console virtual terminal serial port usb serial port vga text-mode framebuffer modern linux-based systems deprecated kernel based text-mode input output instead show graphical logo progress bar system booting followed immediate start graphical user interface e.g x.org server desktop distributions surfaceflinger android kernel boot console commonly used display boot log kernel boot log includes information detected hardware updates status boot procedure point time kernel software running hence logging via user-space e.g syslog possible console provides convenient place output information kernel finished booting runs init process also sending output console handles booting rest system including starting background daemons init boot process complete console used multiplex multiple virtual terminals accessible pressing ctrl-alt-f1 ctrl-alt-f2 etc. ctrl-alt-leftarrow ctrl-alt-rightarrow using chvt virtual terminal getty process run turn runs /bin/login authenticate user authentication command shell run virtual terminals like console supported linux kernel level linux console implements terminal type linux escape sequences uses console_codes man page virtual consoles allow storage multiple text buffers enabling different console programs run simultaneously interact user different contexts user point view creates illusion several independent consoles virtual console character set keyboard layout linux 2.6 introduced ability load different font virtual console kernel versions predating 2.6 change font demand text mode implementation used pc-based systems legacy cga/ega/mda/vga video card implements text-based video modes text mode kernel sends 2d array characters video card video card converts characters pixels display text buffer part vga memory describes content text screen terms code points character attributes code points text buffer font generally encoding used text terminal semantics put characters screen set glyphs screen determined current font text screen handled console.c consolemap.c drivers utility altering fonts terminal encodings called consolechars linux kernel keyboard.c driver almost complete support keyboard input keyboard layouts remains bit inconsistent interacts badly different character sets layouts loaded loadkeys utility two utilities corresponding data files packed linux console tools http //lct.sourceforge.net/ shipped many linux distributions efforts internationalization linux kernel level started early 1994 markus kuhn andries brouwer linux console capable supporting vga-style text mode kernel limited means set modes svgatextmode helps enable complex text modes standard ega vga modes fully compatible console tools conflicts dosemu svgalib display servers currently support different modes different virtual consoles microsoft windows version fully functional support console comparable feature application software win32 console linux framebuffer fbdev graphic hardware-independent abstraction layer originally implemented allow linux kernel emulate text console systems apple macintosh text-mode display offers kernel space text mode emulation platform advantage currently unmaintained svgatextmode reliance better hardware compatibility also permits overpass technical restrictions vga text modes linux framebuffer console differs vga one ways drawing characters processing keyboard events virtual consoles ’ support exactly linux serial console console implementation via serial port enabled option config_serial_console kernel configuration may used embedded systems servers direct interaction operator expected serial console allows mode access system usually slower speed due small bandwidth rs-232 serial console often used development software embedded systems sometimes left accessible via debug port console responds number control characters press escape key console also supports extended escape sequences ansi csi mode sequences dec private mode sequences extended sequences control colors visual effects like blinking underline intensity inverse video bell tone frequency duration vesa screen blanking interval aside textual blanking known way place vga adapter standby kmscon projects aims create modern user-space replacement linux console development priorities include support multi-monitor setups unicode font rendering pango xkb keyboard handling gpu opengl acceleration complaints current kernel implementation include user-interface kernel-space code poorly maintained handles keyboards badly produces bad font rendering misses mode-setting multi-head support contains multi-seat awareness limited hot-plugging handling limited vt102 compliance
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Computer architecture
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gateway load balancing protocol gateway load balancing protocol glbp cisco proprietary protocol attempts overcome limitations existing redundant router protocols adding basic load balancing functionality addition able set priorities different gateway routers glbp allows weighting parameter set based weighting compared others virtual router group arp requests answered mac addresses pointing different routers thus default load balancing based traffic load rather number hosts use gateway router default glbp load balances round-robin fashion glbp elects one avg active virtual gateway group group members act backup case avg failure case two members second best avg placed standby state members placed listening state monitored using hello holdtime timers 3 10 seconds default elected avg assigns virtual mac address member glbp group including thus enabling avfs active virtual forwarders avf assumes responsibility forwarding packets sent virtual mac address could four avfs time default glbp routers use local multicast address 224.0.0.102 send hello packets peers every 3 seconds udp 3222 source destination cisco implemented ipv6 support glbp ios release 12.2 33 sxi
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Internet protocols
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state space enumeration computer science state space enumeration methods consider reachable program state determine whether program satisfies given property programs increase size complexity state space grows exponentially state space used methods reduced maintaining parts state space relevant analysis however use state memory reduction techniques makes runtime major limiting factor
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Programming language topics
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mirrorlink mirrorlink device interoperability standard offers integration smartphone car infotainment system mirrorlink transforms smartphones automotive application platforms apps hosted run smartphone drivers passengers interact steering wheel controls dashboard buttons touch screens car in-vehicle infotainment ivi system mirrorlink utilizes set well-established non-proprietary technologies ip usb wi-fi bluetooth real-time protocol rtp audio universal plug play upnp addition mirrorlink uses virtual network computing vnc baseline protocol display user interface smartphone applications infotainment system screens communicate user input back mobile device mirrorlink started research project researcher jörg brakensiek nokia research center palo alto us took results nobounds project—invented researcher bernd steinke nokia research center bochum germany—and applied automotive domain initial approach applied bernd steinke contained three specialised sub-protocols optimal power efficiency 2d 3d media support 2d graphics composition via x11 mirroring needed requirements chosen source device nokia n800 mobile linux device desire speed demo availability show mirroring use cases opengl es used fast 3d graphics alpha based porter-duff compositing shine-through 2d effects make future relevant approach available limited n800 mesa 3d used local playback high definition media streaming implemented via openmax rtp timed sideband control allow synchronous displayed streaming original video file without transcoding initial implementations remoted gui games media content nokia n800 later n810 mobile linux device demonstration time expected capabilities mobile devices widely reported parallel member ce4a company seen initial results contacted nokia collaboration nokia ce4a started first ideas published demonstrated using nokia n810 internet tablet ieee ccnc 2009 conference together two researchers raja bose keun-young park nokia research center palo alto close collaboration consumer electronics automotive ce4a group german car manufacturer original terminal mode concept created name terminal mode originated name expert group within ce4a created positioning paper nokia together magneti marelli publicly demonstrated first terminal mode concept navteq connection event conjunction frankfurt international auto show iaa september 2009 first car integration shown geneva auto show march 2010 using nokia n97 prototype implementation terminal mode integrated valmet concept car draft 0.9 specification version released march 2010 july 2010 terminal mode presented integrated vw passat mobilebeat 2010 first real live demonstration seen september 2010 shortly terminal mode specification became public 6 october 2010 early adopters included continental alpine clarion collaboration nokia ce4a terminal mode led formation car connectivity consortium car connectivity consortium brought together major players automotive mobile device industries including large number tier-i suppliers even network providers 12 september 2011 terminal mode renamed mirrorlink became commercial trademark owned car connectivity consortium may 2012 car connectivity consortium 56 members included almost major automobile mobile device manufacturers world car connectivity consortium made various auto electronic manufacturers joined together establish industry standard certifying apps devices safe useful drivers called mirrorlink joint effort car manufacturers phone makers aimed developing open standards define operations smartphones linked cars unique element mirrorlink ability show smartphone interface variety mobile os platforms audio head-unit display mirrorlink currently works symbian phones nokia belle phones s60v5 phones many manufacturers samsung galaxy series android lollipop 5.0 sony xperia z series android phones sony audio launched two audio head units 2012 q2 mirrorlink compliant phone maker motorola audio head unit maker alpine also members group supporting mirrorlink alpine offer mirrorlink based aftermarket systems us 2013 vw offer mirrorlink based infotainment systems starting 2nd generation mib infotainment hardware starting 2014 new polo india maruti suzuki ciaz scross ertiga baleno hatchback vitara brezza car models also infotainment system mirrorlink feature
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Computer architecture
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emergent payments emergent payments online payments company focusing offering local payment methods global markets digital companies company based palo alto california previously company named live gamer june 2015 changed name emergent payments indicate shift gaming e-commerce broader market digital payments company also sold microtransactions engine elements focus fully online payments firm originated 2008 live gamer new york pay+ emergent payments saas-based payments platform service offers 200 payment methods 180 countries
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Distributed computing architecture
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tunis tunis toronto university system unix-like operating system developed university toronto early 1980s tunis portable operating system compatible unix v7 completely redesigned kernel written concurrent euclid programs ran unix v7 could run tunis modification tunis designed teaching intended provide model design well-structured highly portable easily understood unix-like operating systems made extensive use concurrent euclid modules isolate machine dependencies provide clean internal structure information hiding concurrent euclid built-in processes synchronization features make easy understand maintain tunis targeted pdp-11 motorola 6809 68000 national semiconductor 32016 architectures supported distribution across multiple cpus using concurrent euclid synchronization features
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Operating systems
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prepared statement database management systems dbms prepared statement parameterized statement feature used execute similar database statements repeatedly high efficiency typically used sql statements queries updates prepared statement takes form template certain constant values substituted execution typical workflow using prepared statement follows compared executing statements directly prepared statements offer two main advantages hand query executed server-side prepared statements slower additional round-trip server implementation limitations may also lead performance penalties example versions mysql cache results prepared queries stored procedure also precompiled stored server later execution similar advantages unlike stored procedure prepared statement normally written procedural language use modify variables use control flow structures relying instead declarative database query language due simplicity client-side emulation prepared statements portable across vendors major dbmss including mysql oracle db2 microsoft sql server postgresql widely support prepared statements prepared statements normally executed non-sql binary protocol efficiency protection sql injection dbmss mysql prepared statements also available using sql syntax debugging purposes number programming languages support prepared statements standard libraries emulate client side even underlying dbms support including java jdbc perl dbi php pdo python db-api client-side emulation faster queries executed reducing number round trips server usually slower queries executed many times resists sql injection attacks equally effectively many types sql injection attacks eliminated disabling literals effectively requiring use prepared statements h2 supports feature example uses java jdbc java codice_1 provides setters codice_2 etc major built-in data types example uses php pdo example uses perl dbi example uses c ado.net ado.net codice_3 accept type codice_4 parameter codice_5 type conversion occurs automatically note use named parameters i.e codice_6 rather codice_7—this allows use parameter multiple times arbitrary order within query command text however addwithvalue method used variable length data types like varchar nvarchar .net assumes length parameter length given value rather getting actual length database via reflection consequence different query plan compiled stored different length general maximum number duplicate plans product lengths variable length columns specified database reason important use standard add method variable length columns paramlength length specified database since standard add method needs used variable length data types good habit use parameter types example uses python db-api example uses direct sql fourth generation language like edeveloper unipaas magic xpa magic software enterprises purebasic since v5.40 lts manage 7 types link following commands setdatabaseblob setdatabasedouble setdatabasefloat setdatabaselong setdatabasenull setdatabasequad setdatabasestring 2 different methods depending type database sqlite odbc mariadb/mysql use postgresql use 1 2 3 ...
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Databases
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reliance authentication reliance authentication part trust-based identity attribution process whereby second entity relies upon authentication processes put place first entity second entity creates element unique specific purpose retrieved accessed authentication processes first entity first met reliance authentication achieved one tokens random characteristics transmitted secure area controlled first entity secure area accessible person authorised use account secure area may online banking portal telephone banking system mobile banking application token often form single plural debit credits financial account numerical values debit credits form token whose numeric value confirmed account holder token retrieved cardholder accessing secure area first entity secure area protected accessible satisfying first entity authentication means case financial services authentication access secure area normally includes multi-factor sepa would likely involve strong authentication transmission requirement retrieve token adds challenge response factor overall authentication process considered point view second party generates transmits token token may generated second party dynamically thus act one-time password reliance authentication method particular application financial instruments credit cards e-mandate direct debit transactions whereby person may instigate transaction financial instrument however financial instrument verified belonging person person confirms value token reliance method often incorporates out-of-band response means tokens retrieved secure area reliance authentication uses multi-step inputs ensure user fraud everyone uses even aware examples include introduction strong customer authentication online payment transactions within european union links verified person account person identified accordance statutory requirements prior account opened reliance authentication makes use pre-existing accounts piggyback services upon accounts providing original source 'reliable concept reliability legal one derived various anti money laundering aml counter-terrorism funding ctf legislation usa eu28 australia singapore new zealand second parties may place reliance customer due diligence process first party first party say financial institution australian legislation 'reliance based upon section 38 anti-money laundering counter-terrorism financing act 2006 cth european commission proposal directive european parliament council prevention use financial system purpose money laundering terrorist financing reliance based upon article 11 1 reliance uk specific meaning relates process regulation 17 money laundering regulations 2007 reliance purpose aml reliance authentication although use similar concepts federal financial institutions examination council united states america ffiec issued authentication internet banking environment dated october 2005 reliance authentication outlined per final paragraph page 14 advantages reliance authentication methods disadvantages reliance authentication methods
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Computer security
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virtual memory compression virtual memory compression also referred ram compression memory compression memory management technique utilizes data compression reduce size number paging requests auxiliary storage virtual memory compression system paging requests compressed stored physical memory usually random-access memory ram sent compressed auxiliary storage hard disk drive hdd solid-state drive ssd cases virtual memory range whose contents compressed paging request marked inaccessible attempts access compressed pages trigger page faults reversal process retrieval auxiliary storage decompression footprint data paged reduced compression process first instance freed ram returned available physical memory pool compressed portion kept ram second instance compressed data sent auxiliary storage resulting i/o operation smaller therefore takes less time implementations including zswap zram helix software company ’ hurricane entire process implemented software systems ibm mxt compression process occurs dedicated processor handles transfers local cache ram virtual memory compression distinct garbage collection gc systems remove unused memory blocks cases consolidate used memory regions reducing fragmentation improving efficiency virtual memory compression also distinct context switching systems connectix ram doubler though also online compression apple os 7.1 inactive processes suspended compressed whole reducing i/o activity caused paging requests virtual memory compression produce overall performance improvements degree performance improvement depends variety factors including availability compression co-processors spare bandwidth cpu speed i/o channel speed physical memory compressibility physical memory contents multi-core multithreaded cpus benchmarks show performance improvements 50 situations embedded devices auxiliary storage limited non-existent cases virtual memory compression allow virtual memory system operate otherwise virtual memory would disabled allows system run certain software would otherwise unable operate environment virtual memory flash memory certain endurance limitations maximum number erase cycles undergo low 100 erase cycles systems flash memory used auxiliary storage system implementing virtual memory compression reduce total quantity data written auxiliary storage improving system reliability one primary issues degree contents physical memory compressed real-world loads program code much data held physical memory often highly compressible since efficient programming techniques data architectures designed automatically eliminate redundancy data sets various studies show typical data compression ratios ranging 2:1 2.5:1 program data similar typically achieval compression ratios disk compression order virtual memory compression provide measurable performance improvements throughput virtual memory system must improved compared uncompressed equivalent thus additional amount processing introduced compression must increase overall latency however i/o-bound systems applications highly compressible data sets gains substantial physical memory used compression system reduces amount physical memory available processes system runs may result increased paging activity reduced overall effectiveness virtual memory compression relationship paging activity available physical memory roughly exponential meaning reducing amount physical memory available system processes results exponential increase paging activity circumstances amount free physical memory low paging fairly prevalent performance gains provided compression system compared paging directly auxiliary storage may offset increased page fault rate leads thrashing degraded system performance opposite state enough physical memory available paging activity low compression may impact performance enough noticeable middle ground two circumstanceslow ram high paging activity plenty ram low paging activityis virtual memory compression may useful however compressible program data pronounced performance improvements less physical memory needed hold compressed data example order maximize use compressed pages cache helix software company hurricane 2.0 provides user-configurable compression rejection threshold compressing first 256 512 bytes 4 kib page virtual memory compression system determines whether configured compression level threshold achieved particular page achievable rest page would compressed retained compressed cache otherwise page would sent auxiliary storage normal paging system default setting threshold 8:1 compression ratio hardware implementations technology also relies price differentials various components system example difference cost ram cost processor dedicated compression relative price/performance differences various components tend vary time example addition compression co-processor may minimal impact cost cpu typical virtual memory implementation paging happens least recently used basis potentially causing compression algorithm use cpu cycles dealing lowest priority data furthermore program code usually read-only therefore never paged-out instead code simply discarded re-loaded program ’ auxiliary storage file needed case bar compression higher since i/o cycle attempting eliminate much shorter particularly flash memory devices virtual memory compression gone favor technology price speed ram external storage plummeted due moore law improved ram interfaces ddr3 thus reducing need virtual memory compression multi-core processors server farms mobile technology together advent flash based systems make virtual memory compression attractive paul r. wilson proposed compressed caching virtual memory pages 1990 paper circulated acm oopsla/ecoop '90 workshop garbage collection issues strategies heap management memory hierarchies appearing acm sigplan notices january 1991 helix software company pioneered virtual memory compression 1992 filing patent application process october year 1994 1995 helix refined process using test-compression secondary memory caches video cards devices however helix release product incorporating virtual memory compression july 1996 release hurricane 2.0 used stac electronics lempel–ziv–stac compression algorithm also used off-screen video ram compression buffer gain performance benefits 1995 ram cost nearly 50 per megabyte microsoft windows 95 listed minimum requirement 4 mb ram due high ram requirement several programs released claimed use compression technology gain “ memory ” notorious softram program syncronys softcorp softram revealed “ placebo software ” include compression technology products including hurricane magnaram included virtual memory compression implemented run-length encoding poor results giving technology negative reputation 8 april 1997 issue pc magazine published comprehensive test performance enhancement claims several software virtual memory compression tools testing pc magazine found minimal 5 overall performance improvement use hurricane none packages however tests run intel pentium systems single core single threaded thus compression directly impacted system activity 1996 ibm began experimenting compression 2000 ibm announced memory expansion technology mxt mxt stand-alone chip acted cpu cache cpu memory controller mxt integrated compression engine compressed data heading to/from physical memory subsequent testing technology intel showed 5–20 overall system performance improvement similar results obtained pc magazine hurricane
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Operating systems
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onespan onespan formerly vasco data security international inc. publicly traded cybersecurity technology company based chicago illinois offices montreal brussels zurich company offers cloud-based open architected anti-fraud platform historically known multi-factor authentication electronic signature software founded t. kendall hunt 1991 held initial public offering ipo january 2000 onespan member fido alliance board 1984 t. kendall hunt founded vasco corp. consulting software services company corporate governmental agencies company acquired thumbscan inc. claimed first fingerprint reader device computer 1991 renamed vasco data security international inc. 1993 expanded offerings include data security vasco incorporated 1997 held initial public offering january 2000 vasco started developing digipass technology early 2000s company marketed technology internationally belgium 2009 vasco announced digipass two-factor authentication available app store iphone ipod touch forbes recognized vasco list america fastest-growing tech companies year january 2011 vasco acquired diginotar dutch certificate authority june 2011 diginotar hacked started issuing false security certificates news broke confidence shattered issued certificates cancelled company went bankrupt company established international headquarters dubai silicon oasis 2012 vasco announced would lower emea channel entry vars time became member fast identity online fido alliance june 2014 later recognized gartner magic quadrant user authentication october 2015 vasco acquired silanis technology inc. canadian document e-signature company 113 million early 2016 company cloud electronic signature software esignlive updated include integration salesforce vasco announced face recognition authentification feature digipass may 2016 company partnerships financial institutions including hsbc bank usa fedict rabobank arab bank riyadh bank may 30 2018 vasco changed name onespan trades ticker symbol ospn may 2018 company acquired dealflo uk canada-based financial agreement automation software company gbp 41 million solutions delivered onespan open cloud-based trusted identity tid platform
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Computer security
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trigram trigrams special case n -gram n 3 often used natural language processing performing statistical analysis texts cryptography control use ciphers codes context important varying analysis rankings percentages easily derived drawing different sample sizes different authors different document types poetry science-fiction technology documentation writing levels stories children versus adults military orders recipes typical cryptanalytic frequency analysis finds 16 common character-level trigrams english encrypted messages sent telegraph often omit punctuation spaces cryptographic frequency analysis messages includes trigrams straddle word boundaries causes trigrams edt occur frequently even though may never occur one word messages sentence quick red fox jumps lazy brown dog following word level trigrams word-level trigram quick red following character-level trigrams underscore marks space
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Computational linguistics
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federal desktop core configuration federal desktop core configuration list security settings recommended national institute standards technology general-purpose microcomputers connected directly network united states government agency fdcc list agreed upon microsoft windows operating system common core system functions applications files services changed configuration around framework secure security-reliable ms windows operating system created standards made mandatory every federal government computer effective feb 1 2008 wanted connect federal office computer network system meet exceed fdcc standard denied access fdcc applied windows xp vista desktop laptop computers replaced united states government configuration baseline usgcb included settings windows 7 red hat enterprise linux 5 windows 7 nist changed naming convention us government computer baseline usgcb ver 2.0 addition un-classifying general windows settings guide nist also publishes guides specifically windows firewall internet explorer guide vista-energy example created capture settings adhere energy conservation policies 20 march 2007 office management budget issued memorandum instructing united states government agencies develop plans using microsoft windows xp vista security configurations united states air force common security configurations windows xp proposed early model standards could developed fdcc baseline developed maintained national institute standards technology collaboration omb dhs doi disa nsa usaf microsoft input public comment applies windows xp professional vista systems only—these security policies tested according nist work windows 9 x /me/nt/2000 windows server 2003 major version 1.1 released 31 october 2008 new changed settings expanded scap reporting options previous versions standard applicable general-purpose workstations laptops end users windows xp vista systems use servers exempt standard also exempt embedded computers special purpose systems defined specialized scientific medical process control experimental systems though still recommends fdcc security configuration considered feasible appropriate fdcc settings generally speaking block open connections operating systems disables functions disables rarely used applications soho environment disables unnecessary services changes permissions items changes way log files collected recorded affects group policy object gpo settings alters entries windows system registry infoweek introduced fdcc mostly administrators engineers article titled ‘ feds ’ allow ’ written kelly jackson higgins darkreading.com published february 4 2008 due complexity guidelines response initially slow implementation took time settings internally researched government enterprise implementation techs nist nsa published guidelines hundreds-of-page texts introduced called scap files applications see wikipedia scap page windows platform built easy interoperability networking therefore left opportunities within operating systems types auto- semi-automatic connections computers ’ flaws programming mistakes purposefully built way example found looking windows remote connection program enabled default typical windows operating system installation fdcc/usgcb configuration instance reverses setting manually re-enable allow remote connections organizations required document fdcc compliance using scap tools 600+ settings average fdcc/usgcb document – usable average small home office soho computer instance released 20 june 2008 fdcc major version 1.0 specifies 674 settings example wireless interfaces disabled recognition recommended settings practical every system exceptions authorized enterprise wireless networks made documented fdcc deviation report strict implementation recommended settings known cause usability issues nist publishes list known issues found nowiki https //usgcb.nist.gov/usgcb/microsoft_content.html /nowiki third-party software vendors emerged claim tested settings soho environment however time general public still remains relatively unaware fdcc usgcb security settings developed put forward nist
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Computer security
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text database dictionary classic mayan project text database dictionary classic mayan abbr twkm promotes research writing language pre-hispanic maya culture housed faculty arts university bonn established funding north rhine-westphalian academy sciences humanities arts project projected run-time fifteen years directed nikolai grube department anthropology americas university bonn goal project conduct computer-based studies extant maya hieroglyphic texts epigraphic cultural-historical standpoint produce publish database comprehensive dictionary classic mayan language text database well dictionary compiled conclusion project assembled based known texts pre-hispanic maya culture texts produced used approximately third century b.c a.d. 1500 region today includes parts countries mexico guatemala belize honduras thousands hieroglyphic inscriptions monuments ceramics daily objects survived present offer insight language ’ vocabulary structure project ’ database dictionary digitally represent original spellings using logo-syllabic maya hieroglyphs well transcription transliteration roman alphabet data additionally annotated various epigraphic analyses translations object-specific information twkm employ digital technologies order compile make available data metadata well publish project ’ research results project thereby methodologically positions field digital humanities project conducted cooperation project partners research association ehumanities textgrid well university regional library bonn ulb working environment currently construction data metadata compiled annotated realized thetextgrid laboratory software virtual research environment component software textgrid repository make data authorized publication freely available online ensure long-term storage tools data compilation annotation attained modularly constructed extended textgrid lab thereby provide necessary materials facilitating research team ’ typical epigraphic workflow workflow usually begins documenting texts objects preserved compiling descriptive data continues various levels epigraphic linguistic analysis concludes best case scenario translation analyzed inscription corresponding publication cooperation ulb selected data additionally made available project ’ virtual inscription archive present online digital collections ulb hieroglyphic inscriptions selected published data repository including image brief information texts objects written epigraphic analysis translation one project ’ goals produce dictionary classic mayan digital print form towards end project run-time additionally database corpus inscriptions including translations epigraphic analyses made freely available online database furthermore provide ontology-like link contextual object data inscriptions thereby allowing cultural-historical arrangement contents within periods pre-hispanic maya culture contents database additionally linked citations relevant literature result database also make freely available scientific community interested parties bibliography representing research history base knowledge concerning ancient maya culture script addition classic maya script temporally defined stages language development gathered documented comprehensive language corpus aid information gathered project collaboration project participants corpus data used together aid various comparable analyses also computational linguistic methods inference-based methods confirm readings hieroglyphs currently partially confirmed eventually completely decipher classic maya script
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Databases
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keyrus keyrus dos-based tsr device driver keyboard display written donetsk student hacker 1989 widely distributed ussr outside country free charge last version keyrus released 1994 long gurtyak suddenly died keyrus distributed primarily via electronic bulletin boards nikolai bezroukov softpanorama electronic magazine loaded fonts ega/vga supported changes keyboard layout initially could change russian latin keyboard layouts later became configurable distribution included layout font editors later versions keyrus utilized original font compression technique bitmaps stored memory packed unpacked loading graphics adapter allowed keyrus occupy minimum limited dos memory space
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Operating systems
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apt-rpm apt-rpm version advanced packaging tool modified work rpm package manager originally ported rpm alfredo kojima developed improved gustavo niemeyer working conectiva linux distribution time march 2005 maintainer program gustavo niemeyer announced would continue developing would instead focus smart package manager planned successor apt-rpm march 2006 development picked panu matilainen red hat new home introducing basic multilib functionality support common repository metadata distributions using apt-rpm package management
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Operating systems
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parasail programming language parallel specification implementation language parasail object-oriented parallel programming language design ongoing implementation described blog official website parasail uses pointer-free programming model objects grow shrink value semantics used assignment global garbage collected heap instead region-based memory management used throughout types recursive long recursive components declared optional global variables parameter aliasing subexpressions expression evaluated parallel assertions preconditions postconditions class invariants etc. part standard syntax using hoare-like notation possible race conditions detected compile time initial design parasail began september 2009 s. tucker taft interpreter using parasail virtual machine llvm-based parasail compiler available work stealing used scheduling parasail light-weight threads latest version downloaded parasail website parasail goals syntax parasail similar modula class-and-interface-based object-oriented programming model similar java c recently parallel constructs parasail adapted syntaxes produce java-like python-like ada-like parallel languages dubbed respectively javallel parython sparkel named ada subset spark based compilers interpreters languages included parasail implementation following hello world program parasail func hello_world var io end func hello_world following interface basic map module interface bmap key_type ordered element_type assignable » end interface bmap possible implementation map module using binary tree class bmap end class bmap simple test program bmap module import psl :core :random import bmap func test_bmap num univ_integer seed univ_integer end func test_bmap articles parasail appeared various forums
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Programming language topics
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whois++ whois++ protocol distributed directory system originally designed provide white pages search mechanism find humans could actually used arbitrary information retrieval tasks developed early 1990s bunyip information systems documented ietf whois++ devised extension pre-existing whois system whois early networked directory service originally maintained sri international defense data network whois protocol still widely used allow domain ownership records internet easily queried whois++ attempted address short comings original whois protocol become apparent years supported multiple languages character sets help i18n issues advanced query syntax ability generate forward knowledge form 'centroid data structures could used route queries one server another protocol designed backward compatible older whois standard whois++ clients could still extract meaningful information already deployed whois servers whilst whois++ white pages directory service never really took compared competitors x.500 gain notable amount use united kingdom underlying search retrieval protocol number subject based gateways funded part jisc electronic library programme achieved using software called roads provided whois++ base index servers cgi based web interfaces whois++ clients use centroids provide forward knowledge query routing allowed subject gateway provide resources academic users database also point jisc funded subject gateways might useful information whois++ protocol designated ietf historic protocol longer deployed new systems developed
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Internet protocols
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european committee interoperable systems european committee interoperable systems ecis international non-profit association founded 1989 order promote interoperability market conditions information communications technology ict sector allowing vigorous competition merits diversity consumer choice ecis represented members many issues related interoperability competition european national international bodies including european union institutions world intellectual property organization wipo ecis members include large smaller information communications technology hardware software providers adobe systems corel corporation ibm linspire nokia opera software oracle corporation realnetworks red hat sun microsystems past years ecis actively involved european commission ’ antitrust condemnation microsoft upheld european court first instance september 2007 ziff-davis eweek comments complaints microsoft include
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Computer architecture
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seamonkey seamonkey free open-source internet suite continuation former mozilla application suite based source code grew netscape communicator formed base netscape 6 netscape 7 seamonkey created 2005 mozilla foundation decided focus standalone projects firefox thunderbird development seamonkey community-driven contrast mozilla application suite last released version 1.7.13 governed mozilla foundation new project-leading group called seamonkey council compared firefox seamonkey web browser keeps traditional-looking interface netscape mozilla suite many xul-based firefox thunderbird add-ons modified compatibility seamonkey although add-ons built webextensions architecture used newer firefox versions yet compatible seamonkey consists web browser descendant netscape family e-mail news client program seamonkey mail newsgroups shares code mozilla thunderbird html editor seamonkey composer software suite supports skins comes two skins default installation modern classic recent versions include irc client chatzilla installed extension seamonkey mail traditional e-mail client includes support multiple accounts junk mail detection message filters html message support address books among features shares code mozilla thunderbird thunderbird seamonkey built mozilla comm-central source tree seamonkey composer wysiwyg html editor main user interface features four tabs normal wysiwyg html tags html code browser preview generated code html 4.01 transitional seamonkey composer longer actively maintained underlying editor code shared mail component seamonkey project releases official builds linux macos windows also releases “ unofficial ” x86-64 builds linux avoid confusing organizations still want use original mozilla suite new product needed new name initial speculation members community july 2 2005 announcement confirmed seamonkey would officially become name internet suite superseding mozilla suite seamonkey lowercase refers brine shrimp used netscape mozilla foundation code name never-released netscape communicator 5 later mozilla suite originally name seamonkey derived netscape management replace buttmonkey developers chosen following internal contest codename.. seamonkey council trademarked name help mozilla foundation project uses separate numbering scheme first release called seamonkey 1.0 despite different name version number seamonkey 1.0 based code mozilla suite 1.7 trademark copyright reasons debian rebranded seamonkey distributed iceape 2013 march 10 2005 mozilla foundation announced would release official versions mozilla application suite beyond 1.7.x since focused standalone applications firefox thunderbird however foundation emphasized would still provide infrastructure community members wished continue development effect meant suite would still continue developed seamonkey council instead mozilla foundation seamonkey first released september 15 2005 seamonkey 1 released january 30 2006 core mozilla project source code licensed disjunctive tri-license changing mpl 2.0 gave choice one three following sets licensing terms mozilla public license version 1.1 later gnu general public license version 2.0 later gnu lesser general public license version 2.1 later seamonkey council team responsible project release management currently consists philip chee karsten düsterloh jens hatlak robert kaiser ian neal neil rashbrook justin wood parts table based seamonkey release notes roadmap meeting notes
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Internet protocols
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network enclave network enclave section internal network subdivided rest network purpose network enclave limit internal access portion network necessary set resources differs general network surroundings typically network enclaves publicly accessible internal accessibility restricted use internal firewalls vlans network admissions control vpns network enclaves consist standalone assets interact information systems networks major difference dmz demilitarized zone network enclave dmz allows inbound outbound traffic access firewall boundaries traversed enclave firewall boundaries traversed enclave protection tools used provide protection within specific security domains mechanisms installed part intranet connect networks similar security requirements dmz established within enclave host publicly accessible systems ideal design build dmz separate network interface enclave perimeter firewall dmz traffic would routed firewall processing dmz would still kept separate rest protected network
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Computer security
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amigaos 4 version history new version amigaos released december 24 2006 five years development hyperion entertainment belgium license amiga inc. amigaone registered users five years development users amigaone machines could download hyperion repository pre-release versions amigaos 4.0 long made available witnessed many users amiga discussion forum sites versions stable reliable despite fact technically labeled pre-releases last stable version amigaos 4.0 amigaone computers july 2007 update released download 18 july 2007 registered users amigaone machines amigaos 4 classic released commercially older amiga computers cyberstormppc blizzardppc accelerator cards november 2007 previously available developers beta-testers new version powerpc-native finally abandoning motorola 68k processor amigaos 4.0 run powerpc hardware currently includes a1200 a3000 a4000 powerpc accelerator boards amigaone motherboards amiga inc. distribution policies amigaos 4.0 later versions require third-party hardware os must bundled sole exception amigas phase 5 powerpc accelerator boards os sold separately amigaos 4.0 final introduced new memory system based slab allocator features among others developer pre-release version snapshot amigaos 4.0 amigaone contained html installation guide english german french italian amigaos 4.0 sdk amigaos 4.0 sdk allowed creation new software migration existing amigaos versions 3.x source code os 4.0 amigaos 4.0 developer pre-release update came form full iso image 33 mb needed burned cd-r w user intended replace original amigaos 4.0 developer pre-release cd installation rescue purposes release date 10 october 2004 among features amigaos 4.0 developer pre-release update came form free download registered users update featured usb stack update i.e mass storage support numerous bug fixes enhancements core components system release date 27 december 2004 release date 14 june 2005 following non-exhaustive list features update 3 prominent features fourth amigaos 4.0 developer pre-release update return screen dragging ability petunia just-in-time 68k emulator release date 8 february 2006 new features pre-release include 24 december 2006 final update released came iso image ≈45 mb burned onto cd cd bootable may used standalone installation cd amigaos 4.0 final update introduced new memory system based slab allocator features amigaos 4.0 among others release date 18 july 2007 improvements amigaos 4.0 july 2007 update amigaos 4.0 amiga 1200 amiga 3000 amiga 4000 series computers equipped phase5 powerup powerpc accelerator cards put sale november 2007 feature set equal july 2007 update drivers amiga expansion cards devices minor improvements e.g amigainput update amigaos 4.0 classic amiga computers addressed issues compatibility problems release date 23 february 2008 amigaos 4.1 presented public july 11 2008 put sale september 2008 new version simple update features among others amigaos 4.1 presented public 11 july 2008 put sale september 2008 new version simple update features among others 21 june 2009 hyperion entertainment announced immediate availability quick fix package amigaone sam/sam flex pegasos ii features include 14 january 2010 hyperion entertainment announced immediate availability amigaos 4.1 update 1 first full update amigaos 4.1 features include upgrades following 30 april 2010 hyperion entertainment announced immediate availability update 2 amigaos 4.1 amigaone sam440ep pegasos ii registered users features 17 may 2011 amigaos 4.1 commodore amigas powerup accelerators released august 29 2011 hyperion entertainment made available update 3 amigaos 4.1 amigaone sam440ep sam 460 classic amigas ppc cards pegasos ii registered users final bugfixes updates amigaos 4.1 new features reserved os 4.2 december 22 2011 hyperion entertainment released minor update correct many bugfixes third update amigaos 4.1 introduces something new update 5 first public release amigaone x1000 28 january 2012 later 16 august 2012 update 5 released platforms update 6 released november 30 2012 rather unusual update regard included bug fixes except new ide xena kicklayout files amigaone x1000 update consisted mainly new efficient way delivering bug fixes new update software ... menu item workbench launch amiupdate handles future amigaos 4 software updates amigaos 4.1 final edition released 18 december 2014 new functionality amigaos 4.1 final edition includes
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Computer architecture
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susan kare susan kare born february 5 1954 artist graphic designer created many interface elements typefaces apple macintosh 1980s also creative director one original employees next company formed steve jobs left apple 1985 worked microsoft ibm pinterest facebook kare born ithaca new york sister aerospace engineer jordin kare.in high school worked museum designer harry loucks introduced typography graphic design graduated harriton high school 1971 graduated summa cum laude b.a art mount holyoke college 1975 received ph.d. new york university 1978 next moved san francisco worked fine arts museums kare joined apple computer receiving call high school friend andy hertzfeld early 1980s member original apple macintosh design team worked apple starting 1982 badge 3978 kare originally hired macintosh software group design user interface graphics fonts business cards read hi macintosh artist later creative director apple creative services working director organization tom suiter designer many typefaces icons original marketing material original macintosh operating system descendants groundbreaking work still seen many computer graphics tools accessories especially icons lasso grabber paint bucket designs created first visual language apple new point-and-click computing presentation layers design conference san francisco revealed command icon apple keyboards originally symbol used denote notable interesting features swedish campgrounds kare early pioneer pixel art recognizable works time apple chicago typeface prominent user-interface typeface seen classic mac os interfaces system 1 1984 mac os 9 1999 well typeface used first four generations apple ipod interface geneva typeface original monospace monaco typeface clarus dogcow happy mac icon smiling computer welcomed mac users starting machines command key symbol apple keyboards icons drew many sources art history wacky gadgets forgotten hieroglyphics mac concept command symbol taken saint hannes cross symbol place interest leaving apple kare joined next designer working clients microsoft ibm projects microsoft included card deck windows 3.0 solitaire game well numerous icons design elements windows 3.0 many icons notepad various control panels remained essentially unchanged microsoft windows xp ibm produced icons design elements os/2 eazel contributed iconography nautilus file manager 2003 became member advisory board glam media mode media 2006 2010 produced icons gifts feature facebook initially profits gift sales donated susan g. komen cure foundation valentine day 2007 gift selection modified include new limited edition gifts necessarily pertain valentine day one gift icons titled big kiss also featured versions mac os x user account picture 2007 designed identity icons website chumby industries inc. well interface internet-enabled alarm clock since 2008 museum modern art store new york city carried stationery notebooks featuring designs 2015 moma also acquired notebooks sketches led early mac icons august 2012 called expert witness apple company patent-infringement trial industry competitor samsung see apple inc. v. samsung electronics co. 2015 kare hired pinterest product design lead heads digital design practice san francisco sells limited-edition signed fine-art prints currently uses adobe photoshop adobe illustrator make designs logos recognition design work kare awarded american institute graphic arts medal april 2018 married three sons
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Operating systems
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fabian pascal fabian pascal consultant large software vendors ibm oracle corporation borland better known author seminar speaker born romania pascal lives san francisco ca area us works association christopher j date pascal known sharp criticisms data management industry trade press current state higher education western culture alleged media bias pascal advocates strict adherence principles relational model argues departing model name pragmatism responsible serious data management troubles criticism pascal advocacy often centers around polemical style perceive overly confrontational unprofessional political commentary postwest blog decline western education civilization middle east issues
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Databases
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poorman poorman simple light-weight web server bundled beos haiku operating system poorman lets users create run websites also knows serve html pages graphics web-based information minimal set hassle ideal small personal servers prototyping web sites use poorman users must set website folder poorman serve pages html format 1 launch poorman desktop alert pop-up let specify folder want use choose default /boot/home/public_html 2 dismiss web site alert poorman main window appears menu bar status line tell web server running stopped 3.to toggle status use server command controls run server command notice poorman starts web server automatically default
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Web technology
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daylife daylife offers on-demand features media apps served cloud provides digital media management tools content feeds publishers brand marketers developers daylife founded 2006 raised 15m investment date recently strategic investor getty images company headquartered downtown new york city daylife products include daylife publisher suite range apis set hosted solutions including smart topics smart galleries smart sections hosted solutions launched partnership getty images allow publishers source manage compose sites media components pages complete sections content daylife technology analyzes 100,000 curated content feeds allows publishers curate automate media enhance proprietary content clients include usa today bloomberg businessweek npr mashable sky news forbes thomson reuters 80 others daylife publisher suite allows publishers marketers deploy on-demand media features apps cloud onto digital channel clicks features apps managed simple browser-based dashboard smartgalleries suite tools allow publishers create image galleries customizable widgets full-page formats publishers hand-select images automatically fill galleries based keywords daylife getty images launched smartgalleries september 2009 conjunction investment announcement smarttopics tools publishers create media-rich pages specific topics linking proprietary content related media videos images links tweets selected publisher smartsections tools allow publishers compose launch full content sections verticals like travel basketball featuring real-time media proprietary outside sources selected editor daylife developer apis programming platform media highly flexible scalable serving 1.5 billion calls per month july 2011 apis let developers source combine synthesize news media content applications apis ingest parse analyze media content exposing hundreds ways query deliver scale free paid access available example semantic web daylife analyzes continuous stream media content maps connections news topics enables dynamic news navigation topic country journalist medium timeline geography daylife founded 2006 chief executive officer upendra shardanand company released apis 2008 2009 daylife named one top 50 tech startups businessweek top 50 real-time web companies readwriteweb daylife funded balderton capital arts alliance new york times getty images angel investors include michael arrington john borthwick andrew rasiej dave winer jeff jarvis partner daylife 2012 daylife acquired newscred
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Web technology
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sha1sum computer program calculates verifies sha-1 hashes commonly used verify integrity files variant installed default unix-like operating systems variants include permits sha-1 sha-512 hash functions selected manually use specific sha-2 hash function permits sha-3 sha3-512 shake rawshake keccak functions selected manually versions microsoft windows also exist activeperl distribution includes perl implementation shasum freebsd openbsd utilities called md5 sha1 sha256 sha512 versions offer slightly different options features additionally freebsd offers skein family message digests sha-1 variants proven vulnerable collision attacks users use example sha-2 variant sha256sum instead prevent tampering adversary included gnu core utilities busybox toybox create file sha1 hash one provided distributing one file .sha1 may appended filename e.g output contains one line per file form codice_1 note well hash digest creation performed text mode instead binary mode two space characters instead single space character asterisk example verify file downloaded correctly sha1sum create checksums one multiple files inside directory directory tree i.e subdirectories sub-subdirectories etc files contain possible using sha1sum combination commands find xargs optionally sort files sorted checksum file sha1deep create checksums directory tree also use sha1sum exec
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Computer security
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intuitionistic type theory intuitionistic type theory also known constructive type theory martin-löf type theory type theory alternative foundation mathematics intuitionistic type theory created per martin-löf swedish mathematician philosopher first published 1972 multiple versions type theory martin-löf proposed intensional extensional variants theory early impredicative versions shown inconsistent girard paradox gave way predicative versions however versions keep core design constructive logic using dependent types martin-löf designed type theory principles mathematical constructivism constructivism requires existence proof contain witness proof exists prime greater 1000 must identify specific number prime greater 1000 intuitionistic type theory accomplished design goal internalizing bhk interpretation interesting consequence proofs become mathematical objects examined compared manipulated intuitionistic type theory type constructors built follow one-to-one correspondence logical connectives example logical connective called implication formula_1 corresponds type function formula_2 correspondence called curry–howard isomorphism previous type theories also followed isomorphism martin-löf first extend predicate logic introducing dependent types intuitionistic type theory 3 finite types composed using 5 different type constructors unlike set theories type theories built top logic like frege feature type theory double duty feature math logic unfamiliar type theory know set theory quick summary types contain terms like sets contain elements terms belong one one type terms like formula_3 formula_4 compute reduce canonical terms like 4 see article type theory 3 finite types 0 type contains 0 terms 1 type contains 1 canonical term 2 type contains 2 canonical terms 0 type contains 0 terms also called empty type used represent anything exist also written formula_5 represents anything unprovable proof exist result negation defined function formula_6 likewise 1 type contains 1 canonical term represents existence also called unit type often represents propositions proven therefore sometimes written formula_7 finally 2 type contains 2 canonical terms represents definite choice two values used boolean values propositions propositions considered 1 type may proven never proof 0 type may proven either way law excluded middle hold propositions intuitionistic type theory σ-types contain ordered pairs typical ordered pair 2-tuple types σ-type describe cartesian product formula_8 two types formula_9 formula_10 logically ordered pair would hold proof formula_9 proof formula_10 one may see type written formula_13 σ-types powerful typical ordered pair types dependent typing ordered pair type second term depend value first term example first term pair might natural number second term type might vector length equal first term type would written using set-theory terminology similar indexed disjoint unions sets case usual ordered pairs type second term depend value first term thus type describing cartesian product formula_15 written important note value first term formula_17 depended type second term formula_18 obviously σ-types used build longer dependently-typed tuples used mathematics records structs used programming languages example dependently-typed 3-tuple two integers proof first integer smaller second integer described type dependent typing allows σ-types serve role existential quantifier statement exists formula_17 type formula_21 formula_22 proven becomes type ordered pairs first item value formula_17 type formula_21 second item proof formula_22 notice type second item proofs formula_22 depends value first part ordered pair formula_17 type would π-types contain functions typical function types consist input type output type powerful typical function types however return type depend input value functions type theory different set theory set theory look argument value set ordered pairs type theory argument substituted term computation reduction applied term example type function given natural number formula_17 returns vector containing formula_17 real numbers written output type depend input value function type often simply written formula_32 thus formula_33 type functions natural numbers real numbers π-types correspond logical implication logical proposition formula_1 corresponds type formula_2 containing functions take proofs-of-a return proofs-of-b type could written consistently π-types also used logic universal quantification statement every formula_17 type formula_21 formula_22 proven becomes function formula_17 type formula_21 proofs formula_22 thus given value formula_17 function generates proof formula_44 holds value type would =-types created two terms given two terms like formula_3 formula_47 create new type formula_48 terms new type represent proofs pair reduce canonical term thus since formula_3 formula_4 compute canonical term formula_51 term type formula_48 intuitionistic type theory single way make terms =-types reflexivity possible create =-types formula_54 terms reduce canonical term unable create terms new type fact able create term formula_54 could create term formula_5 putting function would generating function type formula_57 since formula_58 intuitionistic type theory defines negation would formula_59 finally formula_60 equality proofs area active research proof theory led development homotopy type theory type theories inductive types allow creation complex self-referential types example linked list natural numbers either empty list pair natural number another linked list inductive types used define unbounded mathematical structures like trees graphs etc.. fact natural numbers type may defined inductive type either formula_61 successor another natural number inductive types define new constants zero formula_62 successor function formula_63 since formula_64 definition evaluated using substitution terms like formula_65 formula_66 become canonical terms natural numbers proofs inductive types made possible induction new inductive type comes inductive rule prove predicate formula_44 every natural number use following rule inductive types intuitionistic type theory defined terms w-types type well-founded trees later work type theory generated coinductive types induction-recursion induction-induction working types obscure kinds self-referentiality higher inductive types allow equality defined terms universe types allow proofs written types created type constructors every term universe type formula_69 mapped type created combination formula_70 inductive type constructor however avoid paradoxes term formula_69 maps formula_69 write proofs small types formula_69 must use formula_74 contain term formula_69 formula_74 similarly formula_77 predicative hierarchy universes quantify proof fixed constant formula_78 universes use formula_79 universe types tricky feature type theories martin-löf original type theory changed account girard paradox later research covered topics super universes mahlo universes impredicative universes formal definition intuitionistic type theory written using judgements example statement formula_9 type formula_10 type formula_82 type judgements type ... ... expression formula_82 judgement type defined second level type theory confusing particularly comes equality judgement term equality might say formula_84 statement two terms reduce canonical term also judgement type equality say formula_85 means every element formula_9 element type formula_10 vice versa type level type formula_84 contains terms proof formula_51 formula_3 reduce value obviously terms type generated using term-equality judgement lastly english-language level equality use word four symbol formula_51 refer canonical term formula_92 synonyms like called definitionally equal martin-löf description judgements based discussion nordström petersson smith formal theory works types objects type declared object exists type objects equal types equal type depends object another type declared removed substitution object depends object another type done two ways object abstracted written removed substitution object-depending-on-object also declared constant part recursive type example recursive type formula_64 constant object-depending-on-object associated abstraction constants like formula_64 removed defining equality relationship addition defined using equality using pattern matching handle recursive aspect formula_64 formula_64 manipulated opaque constant internal structure substitution objects types relations used express formulae theory following styles judgements used create new objects types relations existing ones convention type represents types called formula_114 formula_115 since formula_114 type member objects dependent type formula_117 maps object corresponding type texts formula_117 never written context statement reader almost always tell whether formula_9 refers type whether refers object formula_114 corresponds type complete foundation theory everything else derived implement logic proposition given type objects types represent different possible ways prove proposition obviously proof proposition type objects operators like work propositions introduce new types new objects formula_121 type depends type formula_9 type formula_10 objects dependent type defined exist every pair objects formula_9 formula_10 obviously formula_9 formula_10 proof empty type new type representing formula_128 also empty done types booleans natural numbers etc operators using language category theory r. a. g. seely introduced notion locally cartesian closed category lccc basic model type theory refined hofmann dybjer categories families categories attributes based earlier work cartmell category families category c contexts objects contexts context morphisms substitutions together functor c → fam set fam set category families sets objects pairs index set function b x → morphisms pairs functions f → g x → x b g f b words f maps b b functor assigns context g set types set terms axioms functor require play harmoniously substitution substitution usually written form af af type term f substitution g category c must contain terminal object empty context final object form product called comprehension context extension right element type context left element g context object final among contexts mappings p → g q tm ap logical framework martin-löf takes form closure conditions context dependent sets types terms type called set set type types closed forms dependent sum product forth theory predicative set theory expresses closure conditions types sets elements closed operations reflect dependent sum product various forms inductive definition fundamental distinction extensional vs intensional type theory extensional type theory definitional i.e. computational equality distinguished propositional equality requires proof consequence type checking becomes undecidable extensional type theory programs theory might terminate example theory allows one give type y-combinator detailed example found nordstöm petersson programming martin-löf type theory however n't prevent extensional type theory basis practical tool example nuprl based extensional type theory practical standpoint difference program n't terminate program takes million years terminate contrast intensional type theory type checking decidable representation standard mathematical concepts somewhat cumbersome since intensional reasoning requires using setoids similar constructions many common mathematical objects hard work ca n't represented without example integer numbers rational numbers real numbers integers rational numbers represented without setoids representation n't easy work cauchy real numbers ca n't represented without homotopy type theory works resolving problem allows one define higher inductive types define first order constructors values points higher order constructors i.e equalities elements paths equalities equalities homotopies ad infinitum different forms type theory implemented formal systems underlying number proof assistants many based per martin-löf ideas many added features axioms different philosophical background instance nuprl system based computational type theory coq based calculus co inductive constructions dependent types also feature design programming languages ats cayenne epigram agda idris per martin-löf constructed several type theories published various times much later preprints description became accessible specialists among others jean-yves girard giovanni sambin list attempts list theories described printed form sketch key features distinguished theories dependent products dependent sums disjoint unions finite types natural numbers theories reduction rules include η-reduction either dependent products dependent sums except mltt79 η-reduction dependent products added mltt71 first type theories created per martin-löf appeared preprint 1971 one universe universe name i.e type theory called today type type jean-yves girard shown system inconsistent preprint never published mltt72 presented 1972 preprint published theory one universe v identity types universe predicative sense dependent product family objects v object v example v assumed v. universe à la russell i.e. one would write directly t∈v t∈t martin-löf uses sign ∈ instead modern without additional constructor el mltt73 first definition type theory per martin-löf published presented logic colloquium 73 published 1975 identity types calls propositions since real distinction propositions rest types introduced meaning unclear later acquires name j-eliminator yet without name see pp 94–95 theory infinite sequence universes v ... v ... universes predicative a-la russell non-cumulative fact corollary 3.10 p. 115 says a∈v b∈v b convertible m=n means example would difficult formulate univalence theory—there contractible types v unclear declare equal since identity types connecting v v i≠j mltt79 presented 1979 published 1982 paper martin-löf introduced four basic types judgement dependent type theory since became fundamental study meta-theory systems also introduced contexts separate concept see p. 161 identity types j-eliminator already appeared mltt73 name also rule makes theory extensional p. 169 w-types infinite sequence predicative universes cumulative bibliopolis discussion type theory bibliopolis book 1984 somewhat open-ended seem represent particular set choices specific type theory associated
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Programming language topics
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scsi pass-through direct scsi pass direct sptd proprietary device driver application programming interface api developed duplex secure ltd. provides new method access scsi storage devices sptd api open public sptd used daemon tools alcohol 120 also utilized powerarchiver pro 2010 v11.60+ however configurable option available disable known incompatible kernel-mode debugging including windbg microsoft command line debuggers well softice certain versions freeware optical media burning software imgburn issue warning sptd detrimental effect drive performance application detects sptd active installed conexware inc. maker powerarchiver claims internal testing sptd improved optical drive performance 20 percent comparison old school scsi pass interface
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Operating systems
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christopher boyd security christopher boyd also known online pseudonym paperghost computer security researcher boyd director malware research security company facetime becoming senior threat researcher sunbelt software later known gfi software december 2013 malwarebytes announced boyd joined malware intelligence team research new threats july 2004 boyd launched vitalsecurity.org website bringing public attention issues privacy spyware november 2004 modular hacking technique employed compromise windows end-users hacking apache servers hacked servers would redirect user server websites leading set ever-changing infection pages pages employed recoded viruses trojans malware spyware technique used heavily today groups behind spyware coolwebsearch cws idea alternative browsers opera firefox could somehow enhance end-user security cut march 2005 discovery java applet agreed would install large varied adware bundle onto end-user pc found rogue site user blocklists security tools would nothing install bypassing tactics completely end-user clicked yes updated firefox .xpi installer infected internet explorer also deployed installs june 2005 discovered adware makers turning alternative sources installs end-users become aware common install tactics reliance crude social engineering p2p systems previously clean rise boyd discovered bittorrent forums file-sharing sites used major source distribution aurora program produced direct revenue number major adware programs wrapped bundles produced metrix marketing group mmg company lost control network potentially copyright infringing files illegal pornography incorrect absent disclosure exposed scale cause companies involved direct revenue 180solutions others publicly declare discontinuation methods story caused uproar numerous media pundits weighed cases made delicate situation worse article john c. dvorak pc magazine alleged boyd part grand microsoft conspiracy bad-mouth bittorrent benefit planned p2p tool avalanche furious p2p users familiar backstory investigation even went far say boyd league riaa create problems file-sharers bringing bundles light however dvorak piece caused something approaching outrage side fence leading fellow ziff davis media publication go head head dvorak dave methvin pc pitstop followed investigation findings alleges films distributed contained potentially illegal underage pornography long mmg went offline adware companies pulled particular distribution october 2005 boyd discovered fake google toolbar distributed via instant messaging toolbar allowed user store credit card details also opened fake google search page boyd also tracked toolbar back 2003 three different versions one exploiting vulnerabilities windows operating system october november 2005 boyd discovered considered first known instance rootkit distributed via instant messaging hidden inside large payload adware spyware period months group behind attacks distributed numerous inventive payloads forced install bittorrent spread movie files eventually traced back middle-east boyd notoriously fierce critic adware companies famously causing 180solutions label fanatic weblog bad feeling evidence sides day regularly referenced leading antispyware sites sunbelt blog suzi turner zdnet blog ben edelman home page 2006 boyd continued make significant discoveries field security including
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Computer security
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xpl xpl programming language based pl/i portable one-pass compiler written language parser generator tool easily implementing similar compilers languages xpl designed 1967 way teach compiler design principles starting point students build compilers languages xpl designed implemented william m. mckeeman david b. wortman university california santa cruz james j. horning others stanford university xpl first announced 1968 fall joint computer conference methods compiler described detail 1971 textbook compiler generator called combined work 'compiler generator implies little language- target-specific programming required build compiler new language new target better label xpl translator writing system helps write compiler less new changed programming code xpl language simple small efficient dialect pl/i intended mainly task writing compilers xpl language also used purposes available xpl compiled easily modern machines simple compiler compiler internals written easily xpl code easy read pl/i language designed ibm committee 1964 comprehensive language replacing fortran cobol algol meeting customer internal needs ambitious goals made pl/i complex hard implement efficiently sometimes surprising used xpl small dialect full language xpl one added feature found pl/i string datatype dynamic lengths string values live separate text-only heap memory space automatic garbage collection stale values much simple compiler manipulating input text output byte streams feature helps simplify xpl-based compilers xpl compiler called xcom one-pass compiler using table-driven parser simple code generation techniques versions xcom exist different machine architectures using different hand-written code generation modules targets original target ibm system/360 proper subset ibm system/370 ibm system/390 ibm system z. xcom compiles xpl source code since xcom written xpl compile – self-compiling compiler reliant compilers several famous languages self-compiling compilers including burroughs b5000 algol pl/i c lisp java creating compilers chicken-and-egg conundrum language first implemented temporary compiler written language even interpreter often interpreter intermediate code bcpl intcode o-code xcom began algol program running burroughs machines translating xpl source code system/360 machine code xpl team manually turned algol source code xpl source code xpl version xcom compiled burroughs creating self-compiling xcom system/360 machines algol version thrown away improvements happened xpl version called bootstrapping compiler authors xpl invented tombstone diagram t-diagram document bootstrapping process retargeting compiler new machine architecture similar exercise except code generation modules need changed xcom one-pass compiler emitted code fix-up process forward branches loops defined situations emits machine code statement grammar rule within statement recognized rather waiting parsed entire procedure entire program parse trees required intermediate program forms loop-wide procedure-wide optimizations xcom however perform peephole optimization code generation response grammar rule attached rule immediate approach result inefficient code inefficient use machine registers offset efficiency implementation namely use dynamic strings mentioned earlier processing text compilation substring operations frequently performed fast assignment integer actual substring moved short quick easy teach short course fits modest-sized memories easy change different languages different target machines xcom compiler hand-written lexical scanner mechanically-generated parser syntax compiler input language case xpl described simplified bnf grammar xpl grammar analyzer tool analyzer xa turns set large data tables describing legal combinations syntax rules discern table generation step re-done language changed compiler runs data tables used small language-independent parsing algorithm parse respond input language style table-driven parser generally easier write entirely hand-written recursive descent parser xcom uses bottom-up parsing method compiler delay decision syntax rule encountered seen rightmost end phrase handles wider range programming languages top-down methods compiler must guess commit specific syntax rule early seen left end phrase xpl includes minimal runtime support library allocating garbage-collecting xpl string values source code library must included every program written xpl last piece xpl compiler writing system example compiler named skeleton xcom parse tables example toy grammar instead xpl full grammar starting point building compiler new language language differs much xpl xpl run control monitor xmon operating system-specific part system acts loader xcom programs developed using xcom also provides three auxiliary storage devices xcom use directly accessed block number originally published xmon optimized ibm 2311 disk drives ca 1964 efficient drives xmon 50 percent efficient ibm 2314 disk drives ca 1965 significantly less efficient subsequently introduced disk drives ibm 3330 ca 1970 3330-11 ca 1973 3350 ca 1975 dramatically less efficient devices much larger track capacities ibm 3390 ca 1989 converting xmon primitive use note point read/write disk operations precisely one block per track entire remainder track erased hence wasted space excp xdap n blocks per track n computed target device physical characteristics significantly greater 1 wasted space yields dramatic increase disk utilization efficiency corresponding reduction operating system overhead although originally developed os/360 xmon either original note point read/write implementation excp xdap enhancement run subsequently released ibm oses including os/370 xa os/390 z/os generally without changes xcom originally used now-obsolete bottom-up parse table method called mixed strategy precedence invented xpl team although officially released version retains msp parser include later-released peephole optimizations additional data types developed outside original implementation team msp generalization simple precedence parser method invented niklaus wirth pl360 simple precedence generalization trivially simple operator precedence methods work nicely expressions like a+b* c+d -e. msp tables include list expected triplets language symbols list grows larger cube grammar size becomes quite large typical full programming languages xpl-derived compilers difficult fit onto minicomputers 1970s limited memories msp also powerful enough handle likely grammars applicable language designer tweak language definition fit msp restrictions language widely used university toronto subsequently changed xcom xa instead use variant donald knuth lr parser bottom-up method xcom variant called simple lr slr handles grammars msp quite many grammars lalr full lr 1 differences lr 1 mostly table generator algorithms compile-time parser method xcom xa predate widespread availability unix yacc parser generator tool xa yacc similar purposes xpl open source system/360 version xpl distributed ibm share users organization groups ported xpl onto many larger machines 1970s various groups extended xpl used xpl implement moderate-sized languages xpl used develop number compilers various languages systems xpl continues ported current computers x86/freebsd port done 2000 x86/linux port 2015 xpl c translator 2017
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Programming language topics
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fsn file manager file system navigator fsn pronounced fusion experimental application view file system 3d made sgi irix systems even though never developed fully functional file manager gained fame appearing movie jurassic park 1993 scene film character lex murphy played ariana richards finds computer displaying interface exclaims unix system know proceeds restart building access control system locking control room doors release film perceived visualization example media misrepresentation computers citing computer game-like display unrealistic hollywood mockup
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Computer file systems
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clip os clip os linux-based operating system created anssi national cybersecurity agency france aim produce hardened operating system secure sensitive information meets needs french administration clip os development since 2008 september 2018 anssi released two version clip os public stable version 4 in-development version 5 clip os based hardened gentoo variant gentoo linux developers noted whilst similar aims qubes os environment isolation mechanism different administrators clip os system able access user data unlike qubes-based system
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Operating systems
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mysql federated mysql federated storage engine mysql relational database management system storage engine allows user create table local representation foreign remote table utilizes mysql client library api data transport treating remote data source way storage engines treat local data sources whether myd files myisam memory cluster heap tablespace innodb federated table defined one .frm data definition file containing information url data source actual data exist local remote mysql instance create federated table one specify url connection string connection url format upon creation federated table user must ensure remote data source indeed exist error issued mysql federated storage engine authored patrick galbraith brian aker currently maintained patrick galbraith antony curtis introduced 2005 mysql 5.0
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Databases
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mailchannels mailchannels privately held anti-spam technology company based vancouver british columbia mailchannels specializes software services detect block sending spam phishing abusive email unlike anti-spam technology providers mailchannels positions leader blocking abusive email source installing software services within sending networks services isps web hosting providers combat outgoing spam mailchannels offers customers either cloud-based smtp relay service software installed customer within network mailchannels software derives open-source web proxy software nginx company makes claim software extremely scalable robust mailchannels customers include large web hosting companies internet service providers mailbox providers email service providers endurance international group sendgrid sherweb locaweb company founded 2004 former engineers activestate acquired sophos created one first commercial spam filters company first product smtp proxy provides tar-pitting transparent smtp proxy functionality inbound email filtering 2007 mit spam conference company founder ken simpson awarded best paper award 2007 mailchannels joined maawg closed series round led current former microsoft employees 2010 company launched outbound email filtering software claims capable filtering 30 millions messages per hour transparently network outbound email filtering involves scanning email traffic exits network identifying compromised accounts reducing risk ip addresses blocked receiving networks 2013 company launched outbound spam filtering service 2016 company launched reseller program 2018 company launch inbound spam filtering service
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Computer security
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r10000 r10000 code-named t5 risc microprocessor implementation mips iv instruction set architecture isa developed mips technologies inc. mti division silicon graphics inc. sgi chief designers chris rowen kenneth c. yeager r10000 microarchitecture known andes abbreviation architecture non-sequential dynamic execution scheduling r10000 largely replaces r8000 high-end r4400 elsewhere mti fabless semiconductor company r10000 fabricated nec toshiba previous fabricators mips microprocessors integrated device technology idt three others fabricate r10000 expensive r4000 r4400 r10000 introduced january 1996 clock frequencies 175 mhz 195 mhz 150 mhz version introduced o2 product line 1997 discontinued shortly due customer preference 175 mhz version r10000 available large volumes later year due fabrication problems mips foundries 195 mhz version short supply throughout 1996 priced us 3,000 result 25 september 1996 sgi announced r10000s fabricated nec march end july year faulty drawing much current causing systems shut operation sgi recalled 10,000 r10000s shipped systems result impacted company earnings 1997 version r10000 fabricated 0.25 µm process enabled microprocessor reach 250 mhz users r10000 include r10000 four-way superscalar design implements register renaming executes instructions out-of-order design departure previous mti microprocessors r4000 much simpler scalar in-order design relies largely high clock rates performance r10000 fetches four instructions every cycle instruction cache instructions decoded placed integer floating-point load/store instruction queues depending type instruction decode unit assisted pre-decoded instructions instruction cache append five bits every instruction enable unit quickly identify execution unit instruction executed rearrange format instruction optimize decode process instruction queues accept four instructions decoder avoiding bottlenecks instruction queues issue instructions execution units dynamically depending availability operands resources queues except load/store queue issue two instructions every cycle execution units load/store queue issue one instruction r10000 thus issue five instructions every cycle integer unit consists integer register file three pipelines two integer one load store integer register file 64 bits wide contains 64 entries 32 architectural registers 32 rename registers implement register renaming register file seven read ports three write ports integer pipelines adder logic unit however first pipeline barrel shifter hardware confirming prediction conditional branches second pipeline used access multiplier divider multiplies pipelined six-cycle latency 32-bit integers ten 64-bit integers division pipelined divider uses non-restoring algorithm produces one bit per cycle latencies 32-bit 64-bit divides 35 67 cycles respectively floating-point unit fpu consists four functional units adder multiplier divide unit square root unit adder multiplier pipelined divide square root units adds multiplies latency three cycles adder multiplier accept new instruction every cycle divide unit 12- 19-cycle latency depending whether divide single precision double precision respectively square root unit executes square root reciprocal square root instructions square root instructions 18- 33-cycle latency single precision double precision respectively new square root instruction issued divide unit every 20 35 cycles single precision double precision respectively reciprocal square roots longer latencies 30 52 cycles single precision 32-bit double precision 64-bit respectively floating-point register file contains sixty-four 64-bit registers thirty-two architectural remaining rename registers adder dedicated read write ports whereas multiplier shares divider square root unit divide square root units use srt algorithm mips iv isa multiply–add instruction instruction implemented r10000 bypass — result multiply bypass register file delivered add pipeline operand thus fused multiply–add four-cycle latency r10000 two comparatively large on-chip caches 32 kb instruction cache 32 kb data cache instruction cache two-way set-associative 128-byte line size instructions partially decoded appending four bits instruction length 32 bits placed cache 32 kb data cache dual-ported two-way interleaving consists two 16 kb banks bank two-way set-associative cache 64-byte lines uses write-back protocol virtually indexed physically tagged enable cache indexed clock cycle maintain coherency secondary cache external secondary unified cache supported capacities 512 kb 16 mb implemented commodity synchronous static random access memorys ssrams cache accessed via 128-bit bus protected 9-bits error correcting code ecc cache bus operate clock rate r10000 whose maximum frequency 200 mhz 200 mhz bus yielded peak bandwidth 3.2 gb/s cache two-way set associative avoid high pin count r10000 predicts way accessed mips iv 64-bit architecture reduce cost r10000 implement entire physical virtual address instead 40-bit physical address 44-bit virtual address thus capable addressing 1 tb physical memory 16 tb virtual memory r10000 uses avalanche bus 64-bit bus operates frequencies 100 mhz avalanche multiplexed address data bus 100 mhz yields maximum theoretical bandwidth 800 mb/s peak bandwidth 640 mb/s requires cycles transmit addresses system interface controller supports glue-less symmetrical multiprocessing smp four microprocessors systems using r10000 external logic scale hundreds processors example system origin 2000 r10000 consists approximately 6.8 million transistors approximately 4.4 million contained primary caches die measures 16.640 17.934 mm die area 298.422 mm fabricated 0.35 µm process packaged 599-pad ceramic land grid array lga r10000 introduced microprocessor report covering 1994 microprocessor forum reported packaged 527-pin ceramic pin grid array cpga vendors also investigated possibility using 339-pin multi-chip module mcm containing microprocessor die 1 mb cache r10000 extended multiple successive derivatives derivatives r12000 clock frequency kept low possible maintain power dissipation 15 20 w range densely packaged sgi high performance computing hpc systems r12000 derivative r10000 started mips completed sgi fabricated nec toshiba version fabricated nec called vr12000 microprocessor introduced november 1998 available 270 300 360 mhz r12000 developed stop-gap solution following cancellation beast project intended deliver successor r10000 r12000 users include nec siemens-nixdorf sgi tandem computers later compaq acquisition tandem r12000 improves upon r10000 microarchitecture inserting extra pipeline stage improve clock frequency resolving critical path increasing number entries branch history table improving prediction modifying instruction queues take account age queued instruction enabling older instructions executed newer ones possible r12000 fabricated nec toshiba 0.25 µm cmos process four levels aluminum interconnect new use new process mean r12000 simple die shrink tweaked microarchitecture layout die optimized take advantage 0.25 µm process nec fabricated vr12000 contained 7.15 million transistors measured 15.7 14.6 mm 229.22 mm r12000a derivative r12000 developed sgi introduced july 2000 operates 400 mhz fabricated nec 0.18 µm process aluminum interconnects r14000 development r12000 announced july 2001 r14000 operates 500 mhz enabled 0.13 µm cmos process five levels copper interconnect fabricated features improvements microarchitecture r12000 supporting double data rate ddr ssrams secondary cache 200 mhz system bus r14000a development r14000 announced february 2002 operates 600 mhz dissipates approximately 17 w fabricated nec corporation 0.13 µm cmos process seven levels copper interconnect r16000 code-named n0 last derivative r10000 developed sgi fabricated nec 0.11 µm process eight levels copper interconnect microprocessor introduced 9 january 2003 debuting 700 mhz fuel also used onyx4 ultimate vision april 2003 600 mhz version introduced origin 350 improvements 64 kb instruction data caches r16000a refers r16000 microprocessors clock rates higher 700 mhz first r16000a 800 mhz version introduced 4 february 2004 later 900 mhz version introduced version time fastest publicly known r16000a—sgi later revealed 1.0 ghz r16000s shipped selected customers r16000 users include hp sgi sgi uses microprocessor fuel tezro workstations origin 3000 servers supercomputers hp uses r16000a nonstop himalaya s-series fault-tolerant servers inherited tandem via compaq r18000 canceled development r10000 microarchitecture featured major improvements silicon graphics inc. described hot chips symposium 2001 r18000 designed specifically sgi ccnuma servers supercomputers node would two r18000s connected via multiplexed bus system controller would interface microprocessors local memory rest system via hypercube network r18000 improved floating-point instruction queues revised floating-point unit feature two multiply–add units quadrupling peak flops count division square-root would performed separate non-pipelined units parallel multiply–add units system interface memory hierarchy also significantly reworked would 52-bit virtual address 48-bit physical address bidirectional multiplexed address data system bus earlier models would replaced two unidirectional ddr links 64-bit multiplexed address write path 128-bit read path paths could shared another r18000 multiplexing bus could also configured sysad avalanche configuration backwards compatibility r10000 systems r18000 would 1 mb four-way set-associative secondary cache included on-die supplemented optional tertiary cache built single data rate sdr double data rate ddr ssram ddr sdram capacities 2 64 mb l3 cache would cache tags equivalent 400 kb located on-die reduce latency l3 cache would accessed via 144-bit bus 128 bits data 16 bits ecc l3 cache clock rate would programmable r18000 fabricated nec ux5 process 0.13 µm cmos process nine levels copper interconnect would used 1.2 v power supply dissipated less heat contemporary server microprocessors order densely packed systems
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Computer architecture
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michigan terminal system michigan terminal system mts one first time-sharing computer operating systems developed 1967 university michigan use ibm s/360-67 s/370 compatible mainframe computers developed used consortium eight universities united states canada united kingdom period 33 years 1967 1999 university michigan multiprogramming supervisor ummps developed staff academic computing center university michigan operation ibm s/360-67 s/370 compatible computers software may described multiprogramming multiprocessing virtual memory time-sharing supervisor runs multiple resident reentrant programs among programs michigan terminal system mts command interpretation execution control file management accounting end-users interact computing resources mts using terminal batch server oriented facilities name mts refers mts used production basis 13 sites united states canada united kingdom brazil possibly yugoslavia several sites trial benchmarking basis mts developed maintained core group eight universities included mts consortium university michigan announced 1988 reliable mts service provided long users requiring ... mts may phased alternatives able meet users computing requirements ceased operating mts end-users june 30 1996 time services moved client/server-based computing systems typically unix servers various mac pc unix flavors clients university michigan shut mts system last time may 30 1997 rensselaer polytechnic institute rpi believed last site use mts production environment rpi retired mts june 1999 today mts still runs using ibm s/370 emulators hercules sim390 flex-es mid-1960s university michigan providing batch processing services ibm 7090 hardware control university michigan executive system umes interested offering interactive services using time-sharing time work computers could perform limited small real memory capacity ibm introduced system/360 family computers mid-1960s provide solution limitation within ibm conflicting views importance need support time-sharing paper titled program addressing structure time-sharing environment bruce arden bernard galler frank westervelt associate directors um academic computing center tom o'brian building upon basic ideas developed massachusetts institute technology mit published january 1966 paper outlined virtual memory architecture using dynamic address translation dat could used implement time-sharing year negotiations design studies ibm agreed make one-of-a-kind version s/360-65 mainframe computer dynamic address translation dat features would support virtual memory accommodate um desire support time-sharing computer dubbed model s/360-65m stood michigan ibm initially decided supply time-sharing operating system machine meanwhile number institutions heard project including general motors massachusetts institute technology mit lincoln laboratory princeton university carnegie institute technology later carnegie mellon university intrigued time-sharing idea expressed interest ordering modified ibm s/360 series machines demonstrated interest ibm changed computer model number s/360-67 made supported product requests 100 new model s/360-67s ibm realized market time-sharing agreed develop new time-sharing operating system called tss/360 tss stood time-sharing system delivery roughly time first model s/360-67 waiting model 65m arrive um computing center personnel able perform early time-sharing experiments using ibm system/360 model 50 funded arpa concomp conversational use computers project time-sharing experiment began half-page code written kitchen table combined small multi-programming system llmps mit lincoln laboratory modified became um multi-programming supervisor ummps turn ran mts job program earliest incarnation mts intended throw-away system used gain experience new ibm s/360 hardware would discarded ibm tss/360 operating system became available development tss took longer anticipated delivery date delayed yet available s/360-67 serial number 2 arrived computing center january 1967 time um decide whether return model 67 select another mainframe develop mts interim system use tss ready decision continue development mts staff moved initial development work model 50 model 67 tss development eventually canceled ibm reinstated canceled time um liked system developed longer considered interim mts would used um sites 33 years mts developed maintained used consortium eight universities us canada united kingdom several sites ran one mts system numac ran two first newcastle later durham michigan ran three mid-1980s um maize ub blue hg human genetics ubc ran three four different times mts-g mts-l mts-a mts-i general library administration instruction mts sites made contributions development mts sometimes taking lead design implementation new feature times refining enhancing critiquing work done elsewhere many mts components work multiple people multiple sites early days collaboration mts sites accomplished combination face-to-face site visits phone calls exchange documents magnetic tapes snail mail informal get-togethers share meetings later e-mail computer conferencing using confer *forum network file transfer e-mail attachments supplemented eventually largely replaced earlier methods members mts consortium produced series 82 mts newsletters 1971 1982 help coordinate mts development starting ubc 1974 mts consortium held annual mts workshops one member sites workshops informal included papers submitted advance proceedings published after-the-fact included session summaries mid-1980s several western workshops held participation subset mts sites ubc sfu uqv um possibly rpi annual workshops continued even mts development work began taper called simply community workshop continued mid-1990s share expertise common experiences providing computing services even though mts longer primary source computing campuses stopped running mts entirely addition eight mts consortium sites involved development mts run number sites including copy mts also sent university sarajevo yugoslavia though whether ever installed known inria french national institute research computer science control grenoble france ran mts trial basis university waterloo ontario canada southern illinois university naval postgraduate school amdahl corporation st systems mcgill university hospitals stanford university university illinois united states sites theory mts run ibm s/360-67 ibm s/370 series successors mts run following computers production benchmarking trial configurations university michigan installed ran mts first ibm s/360-67 outside ibm serial number 2 1967 second amdahl 470v/6 serial number 2 1975 first amdahl 5860 serial number 1 1982 first factory shipped ibm 3090-400 1986 numac ran mts first s/360-67 uk likely first europe university british columbia ubc took lead converting mts run ibm s/370 series ibm s/370-168 1974 university alberta installed first amdahl 470v/6 canada serial number p5 1975 1978 numac university newcastle upon tyne university durham moved main mts activity ibm s/370 series ibm s/370-168 mts designed support four processors ibm s/360-67 although ibm produced one simplex half-duplex two duplex processor configurations model 67 1984 rpi updated mts support 32 processors ibm s/370-xa extended addressing hardware series although 6 processors likely largest configuration actually used mts supports ibm vector facility available option ibm 3090 es/9000 systems early 1967 running single processor ibm s/360-67 um without virtual memory support mts typically supporting 5 simultaneous terminal sessions one batch job november 1967 virtual memory support added mts running ibm s/360-67 simultaneously supporting 50 terminal sessions 5 batch jobs august 1968 dual processor ibm s/360-67 replaced single processor system supporting roughly 70 terminal 8 batch jobs late 1991 mts um running ibm es/9000-720 supporting 600 simultaneous terminal sessions 3 8 batch jobs mts ipl-ed vm/370 mts sites ran mts native hardware without using virtual machine notable features mts include following notable programs developed mts following notable programs ported mts systems mts supports rich set programming languages developed mts others ported systems ummps supervisor complete control hardware manages collection job programs one job programs mts job program users interact mts operates collection command language subsystems clss one clss allows execution user programs mts provides collection system subroutines available clss user programs mts among things system subroutines provide standard access device support routines dsrs components perform device dependent input/output lists follow quite university michigan centric mts sites used material also produced manuals memos reports newsletters tailored needs site manual series mts michigan terminal system published 1967 1991 volumes 1 23 updated reissued irregularly initial releases volumes always occur numeric order volumes occasionally changed names updated republished general higher number specialized volume earliest versions mts volume ii different organization content mts volumes followed included internal well end user documentation second edition december 1967 covered following mts volumes published university michigan computing center available pdfs various aspects mts university michigan documented series computing center memos ccmemos published irregularly 1967 1987 numbered 2 924 though necessarily chronological order numbers 2 599 general memos various software hardware 600 series consultant notes series—short memos beginning intermediate users 800 series covers issues relating xerox 9700 printer text processing typesetting 900 series covers microcomputers 700 series 1989 series continued reference memos less focus mts long run newsletters targeted end-users university michigan titles computing center news computing center newsletter u-m computing news information technology digest published starting 1971 also introductory material presented user guide mts user guide tutorial series including following materials widely distributed included mts distributions university michigan released mts magnetic tape irregular basis full partial distributions full distributions d1.0 d2.0 ... included mts components partial distributions d1.1 d1.2 d2.1 d2.2 ... included components changed since last full partial distribution distributions 1.0 3.1 supported ibm s/360 model 67 distribution 3.2 supported ibm s/360-67 ibm s/370 architecture distributions d4.0 d6.0 supported ibm s/370 architecture extensions mts distributions included updates needed run licensed program products proprietary software mts base proprietary software obtained separately owners except ibm assembler h none licensed programs required run mts last mts distribution d6.0 released april 1988 consisted 10,003 files six 6250 bpi magnetic tapes 1988 distribution mts components done ad hoc fashion using network file transfer allow new sites get started scratch two additional magnetic tapes made available iplable boot tape contained minimalist version mts plus dasdi diskcopy utilities could used initialize restore one disk pack starter version mts second magnetic tape earliest days mts standalone tss dasdi dump/restore utilities rather mts used create one-disk starter system also less formal redistributions individual sites would send magnetic tapes containing new updated work coordinating site site would copy material common magnetic tape rd1 rd2 ... send copies tape sites contents redistribution tapes seem lost today complete materials six full ten partial mts distributions well two redistributions created 1968 1988 available bitsavers software archive university michigan deep blue digital archive working d6.0 distribution materials possible create iplable version mts new d6.0a distribution mts makes easier d6.0a based d6.0 version mts 1988 various fixes updates make operation hercules 2012 smoother future iplable version mts made available based upon version mts use university michigan 1996 shortly mts shut december 22 2011 mts distribution materials freely available terms creative commons attribution 3.0 unported license cc 3.0 earliest days mts made available free without need license sites interested running mts seemed knowledgeable staff required support mid-1980s licensing arrangements formalized university michigan acting agent granting licenses behalf mts consortium mts licenses available academic organizations annual fee 5,000 non-profit organizations 10,000 commercial organizations 25,000 license restricted mts used provide commercial computing services licensees received copy full set mts distribution tapes incremental distributions prepared year written installation instructions two copies current user documentation limited amount assistance organizations licensed mts several licensed mts order run single program confer fees collected used offset common expenses mts consortium
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Operating systems
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modelling general systems mgs general model simulation domain-specific language used specification simulation dynamical systems dynamical structure developed ibisc computer science integrative biology complex systems université d'évry val-d'essonne university évry mgs particularly aimed modelling biological systems mgs computational model generalisation cellular automata lindenmayer systems paun systems computational formalisms inspired chemistry biology manipulates collections sets positions filled values lattice user-defined topology
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Programming language topics
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r3000 r3000 32-bit risc microprocessor chipset developed mips computer systems implemented mips instruction set architecture isa introduced june 1988 second mips implementation succeeding r2000 flagship mips microprocessor operated 20 25 33.33 mhz mips 1 instruction set small compared contemporary 80x86 680x0 architectures encoding commonly-used operations supporting addressing modes combined fixed instruction length three different types instruction formats simplified instruction decoding processing employed 5-stage instruction pipeline enabling execution rate approaching one instruction per cycle unusual time mips generation supports four co-processors addition cpu core r3000 microprocessor includes control processor cp contains translation lookaside buffer memory management unit cp works coprocessor besides cp r3000 also support external r3010 numeric coprocessor two external coprocessors r3000 cpu include level 1 cache instead on-chip cache controller operates external data instruction caches 256 kb access caches clock cycle r3000 found much success used many companies workstations servers users included r3000 also used embedded microprocessor advances technology rendered obsolete high-performance systems found continued use lower-cost designs companies lsi logic developed derivatives r3000 specifically embedded systems r3000 development r2000 minor improvements including larger tlb faster bus external caches r3000 die contained 115,000 transistors measured 75,000 square mils 48 mm mips fabless semiconductor company r3000 fabricated mips partners including integrated device technology idt lsi logic nec corporation performance semiconductor others fabricated 1.2 µm complementary metal–oxide–semiconductor cmos process two levels aluminium interconnect derivatives r3000 non-embedded applications include derivatives r3000 embedded applications include
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Computer architecture
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talking moose talking moose animated talking utility apple macintosh created 1986 canadian programmer steven halls first animated talking agent personal computer featured moose would appear periodic intervals joke witticism moose would also comment system events user actions could speak user typed using moose proof desk accessory according halls original purpose moose make use mac macintalk text-to-speech engine novel manner doonesbury strip characters commented talking computer provided inspiration halls found moose head antlers recognizable even low-resolution computer screens moose first facially animated talking agent lip synchronization became seed idea future talking agents clippy paperclip microsoft windows bonzi buddy prody parrot creative soundblaster talking moose used apple macintalk software first version famously made original never trust computer ca n't lift speech macintosh launch 1984 apple development macintalk petered granted halls permission use continue refining software free halls improve fluidity speech reliability interpretation gave moose library comedic observations wisecracks gave distinctive character around 1990 version talking moose software commercially published baseline publishing commercial release talking moose included color graphics additional software allowed users create edit phrases spoken stripped-down version baseline release talking moose distributed bob levitus book stupid mac tricks 1989 1990s moose rewritten uli kusterer name uli moose later obtained steve halls blessing moose included bob levitus imac ibook book n't know could version 1.0 talking moose released 1986 steve halls version 2.0 released 1987 ran macintosh systems 6.0.4 7.1 macintalk voice used moose 'fred around 1990 baseline publishing commercially published talking moose released version 4 introducing new characters cartoon carnival supposedly run titular ungulate uli kusterer next author moose got rid cartoon carnival worked spirit original moose releasing new versions starting 1.0 supported mac os 7.1 9.2 released initially compuserve later internet also developed first os x native version v 3.0 latest macintosh version moose v3.5.7 works versions os x 10.3 10.7 includes universal binaries january 8 2009 talking moose posting periodic comments twitter account
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Operating systems
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r4000 r4000 microprocessor developed mips computer systems implements mips iii instruction set architecture isa officially announced 1 october 1991 one first 64-bit microprocessors first mips iii implementation early 1990s risc microprocessors expected replace cisc microprocessors intel i486 r4000 selected microprocessor advanced computing environment ace industry standard intended define common risc platform ace ultimately failed number reasons r4000 found success workstation server markets three configurations r4000 r4000pc entry-level model support secondary cache r4000sc model secondary cache multiprocessor capability r4000mc model secondary cache support cache coherency protocols required multiprocessor systems r4000 scalar superpipelined microprocessor eight-stage integer pipeline first stage virtual address instruction generated instruction translation lookaside buffer tlb begins translation address physical address second stage translation completed instruction fetched internal 8 kb instruction cache instruction cache direct-mapped virtually indexed physically tagged 16- 32-byte line size architecturally could expanded 32 kb third stage rf instruction decoded register file read mips iii defines two register files one integer unit floating-point register file 64 bits wide contained 32 entries integer register file two read ports one write port floating-point register file two read ports two write ports execution begins stage four ex integer floating-point instructions written back register files completed stage eight wb results may bypassed possible r4000 arithmetic logic unit alu shifter multiplier divider load aligner executing integer instructions alu consists 64-bit carry-select adder logic unit pipelined shifter 32-bit barrel shifter performs 64-bit shifts two cycles stalling pipeline result design chosen save die area multiplier divider pipelined significant latencies multiplies 10- 20-cycle latency 32-bit 64-bit integers respectively whereas divides 69- 133-cycle latency 32-bit 64-bit integers respectively instructions single cycle latency alu adder also used calculating virtual addresses loads stores branches load store instructions executed integer pipeline access on-chip 8 kb data cache r4000 on-die ieee 754-1985-compliant floating-point unit fpu referred r4010 fpu coprocessor designated cp1 mips isa defined four coprocessors designated cp0 cp3 fpu operate two modes 32- 64-bit selected setting bit fr bit cpu status register 32-bit mode 32 floating-point registers become 32 bits wide used hold single-precision floating-point numbers used hold double-precision numbers 16 floating-point registers registers paired fpu operate parallel alu unless data resource dependency causes stall contains three sub-units adder multiplier divider multiplier divider execute instruction parallel adder use adder final stages execution thus imposing limits overlapping execution thus certain conditions execute three instructions time one unit fpu capable retiring one instruction per cycle adder multiplier pipelined multiplier four-stage multiplier pipeline clocked twice clock frequency microprocessor adequate performance uses dynamic logic achieve high clock frequency division 23- 36-cycle latency single- double-precision operations square-root 54- 112-cycle latency division square-root uses srt algorithm memory management unit mmu uses 48-entry translation lookaside buffer translate virtual addresses r4000 uses 64-bit virtual address implements 40 64-bits 1 tb virtual memory remaining bits checked ensure contain zero r4000 uses 36-bit physical address thus able address 64 gb physical memory r4000 sc mc configurations supports external secondary cache capacity 128 kb 4 mb cache accessed via dedicated 128-bit data bus secondary cache configured either unified cache split instruction data cache latter configuration cache capacity 128 kb 2 mb secondary cache physically indexed physically tagged programmable line size 128 256 512 1,024 bytes cache controller on-die cache built standard static random access memory sram data tag buses ecc-protected r4000 uses 64-bit system bus called sysad bus sysad bus address data multiplexed bus used set wires transfer data addresses reduces bandwidth also less expensive providing separate address bus requires pins increases complexity system sysad bus configured operate half third quarter internal clock frequency sysad bus generates clock signal dividing operating frequency r4000 contains 1.2 million transistors designed 1.0 µm two-layer metal complementary metal–oxide–semiconductor cmos process mips fabless company r4000 fabricated partners processes 0.8 µm minimum feature size r4000 generates various clock signals master clock signal generated externally operating frequency r4000 multiplies master clock signal two use on-die phase-locked loop pll r4000pc packaged 179-pin ceramic pin grid array cpga r4000sc r4000mc packaged 447-pin ceramic staggered pin grid array spga pin r4000mc different r4000sc pins unused r4000sc used signals implement cache coherency r4000mc pin-out r4000pc similar pga-packaged r4200 r4600 microprocessors characteristic enables properly designed system use three microprocessors r4400 development r4000 announced early november 1992 samples microprocessor shipped selected customers general availability january 1993 r4400 operates higher clock frequencies 100 133 150 200 250 mhz major improvement r4000 larger primary caches doubled capacity 16 kb 8 kb contained 2.3 million transistors r4400 licensed integrated device technology idt lsi logic nec performance semiconductor siemens ag toshiba idt nec siemens toshiba fabricated marketed microprocessor lsi logic used r4400 custom products performance semiconductor sold logic division cypress semiconductor mips microprocessor products discontinued nec marketed version vr4400 first version 150 mhz part announced november 1992 early versions fabricated 0.6 µm process mid-1995 250 mhz part began sampling fabricated 0.35 µm four-layer-metal process nec also produced mr4401 ceramic multi-chip module mcm contained vr4400sc ten 1 mbit sram chips implemented 1 mb secondary cache mcm pin-compatible r4x00pc first version 150 mhz part announced 1994 1995 200 mhz part announced toshiba marketed version tc86r4400 200 mhz part containing 2.3 million transistors measuring 134 mm fabricated 0.3 µm process introduced mid-1994 r4400pc priced 1,600 r4400sc 1,950 r4400mc 2,150 quantities 10,000 r4400 used r4000 r4400 require external core logic interface system commercially available proprietary core logic developed microprocessors proprietary designs developed system vendors sgi use systems commercial chipsets developed acer mips microprocessors fabricators nec toshiba acer developed pica chipset toshiba developed tiger shark chipset adapted sysad bus i486-compatible system bus
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Computer architecture
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