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quantum byzantine agreement byzantine fault tolerant protocols algorithms robust arbitrary types failures distributed algorithms advent popularity internet need develop algorithms require centralized control guarantee always working correctly byzantine agreement protocol essential part task article quantum version byzantine protocol works constant time described byzantine agreement protocol protocol distributed computing takes name problem formulated lamport shostak pease 1982 reference historical problem byzantine army divided divisions division led general following properties see proof impossibility result problem usually equivalently restated form commanding general loyal lieutenants general either loyal traitor lieutenants following properties failures algorithm protocol categorized three main types byzantine resilient byzantine fault tolerant protocol algorithm algorithm robust kinds failures mentioned example given space shuttle multiple redundant processors processors give incorrect data processors sets processors believed solution formulated byzantine fault tolerant protocol sketch asynchronous algorithm algorithm works two phases two types coin flipping protocols generate random coin assign integer range 0 n-1 player player allowed choose random id player formula_17 selects random number formula_18 every player formula_19 distributes using verifiable secret sharing scheme end phase players agree secrets properly shared secrets opened player formula_11 assigned value formula_21 requires private information channels replace random secrets superposition formula_22 state encoded using quantum verifiable secret sharing protocol qvss distribute state formula_23 since bad players collapse state prevent bad players encode state using quantum verifiable secret sharing qvss send player share secret verification requires byzantine agreement replacing agreement grade-cast protocol enough grade-cast protocol following properties using definitions informally graded broadcast protocol protocol designated player called “ dealer ” one broadcasts protocol p said achieve graded broadcast beginning protocol designated player called dealer holds value v end protocol every player formula_19 outputs pair formula_25 following properties hold formula_26 formula_38 verification stage qvss protocol guarantees good dealer correct state encoded possibly faulty dealer particular state recovered recovery stage note purpose byzantine quantum coin flip protocol recovery stage much simpler player measures share qvss sends classical value players verification stage guarantees high probability presence formula_38 faulty players good players recover classical value value would result direct measurement encoded state 2007 quantum protocol byzantine agreement demonstrated experimentally using four-photon polarization-entangled state shows quantum implementation classical byzantine agreement protocols indeed feasible
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Computer security
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keynote systems keynote systems u.s. based company specialized developing marketing software service technology measure test improve end user perspective performance websites online content applications services across browsers networks mobile devices keynote provided independent testing measurement monitoring mobile content applications services real devices across multiple mobile operator networks keynote systems merged dynatrace june 2015 headquartered san mateo california employing 300 people company went public nasdaq september 24 1999 company internet mobile monitoring products services ran proprietary software measured online business performance viewpoint geographically dispersed user base company claimed corporate customers including american express bp caterpillar disney ebay e*trade expedia microsoft sony ericsson sprint t-mobile verizon vodafone keynote systems founded founded 1995 launched ‘ keynote perspective ’ 1996 launched business 40 internet performance index 1997 globalized internet-performance metrics 1997 secured 4.7 million equity financing keynote releases first ever internet multi-page transactional measurement service 1999. launched streaming perspective product 2000 2001 keynote added google business 40 internet performance index 2002 keynote internetweek ’ ‘ best breed ’ award keynotes named 13th fastest growing north american tech company keynote acquires xaffire ’ insight service suite 2003 company offered buy back 7.5 million shares 33 percent 71.3 million 2004 keynote introduces performance authority email alerts warn public internet threats 2005 keynote zandan announce product-development marketing partnership 2007 keynote joined russell 3000 index keynote ’ voice perspective service named one top 25 innovations 2007 voip news 2008 keynote systems acquires french mobile company zandan keynote launched web site performance index 2008 olympics keynotes introduces kite keynote internet testing environment keynote launched mite mobile internet testing environment – desktop based mobile testing keynote systems gold mobile star award mobile application testing 2009 keynote systems introduces mobile application perspective 3.0 – real time operational monitoring text messaging keynote mite wons jolt product excellence award keynote systems earned ‘ fire ’ ratings forrester keynote releases transaction perspective 9.0 – support monitoring interactive flash silverlight web applications 2011 keynote systems acquired deviceanywhere august 2013 private equity firm thoma bravo acquired keynote systems 395 million june 2015 keynote systems merged dynatrace latter john van siclen acting ceo company acquired 14 companies
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Distributed computing architecture
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message maps message maps microsoft foundation class library message map facility microsoft windows implements polymorphism window classes using messaging facility due large number messages involved providing separate virtual function windows message results prohibitively large vtable mfc provides alternative switch statement used traditional windows programs handle messages sent window mapping messages member-functions may defined message handled window appropriate member function called automatically message-map facility designed similar virtual functions additional benefits possible c++ virtual functions message maps maps user action appropriate mfc class functions handle mfc class handle message member ccmdtarget i.e hierarchically derived ccmdtarget advantage message map action mapped one mfc class function similar handling messages sdk application using wndproc callback functions mfc help oops concepts
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Operating systems
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geos 8-bit operating system geos graphic environment operating system operating system berkeley softworks later geoworks originally designed commodore 64 version released 1986 enhanced versions geos later became available 1987 commodore 128 1988 apple ii family computers lesser-known version also released commodore plus/4 geos closely resembles early versions classic mac os includes graphical word processor geowrite paint program geopaint december 1987 survey commodore-dedicated magazine compute gazette found nearly half readers used geos many years commodore bundled geos redesigned cost-reduced c64 c64c peak geos third-most-popular microcomputer operating system world terms units shipped trailing ms-dos mac os besides original commodore 64 kernal geos-compatible software packages available berkeley softworks third parties including reasonably sophisticated desktop publishing application called geopublish spreadsheet called geocalc geopublish sophisticated aldus pagemaker geocalc sophisticated microsoft excel packages provide reasonable functionality berkeley softworks founder brian dougherty claimed company ran business using software commodore 8-bit computers several years written group programmers geos design team jim defrisco dave durran michael farr doug fults chris hawley clayton jung tony requist led dougherty cut teeth limited-resource video game machines atari 2600 geos revered could accomplish machines 64–128 kb ram memory 1–2 mhz 8-bit processing power unlike many pieces proprietary software c64 c128 geos takes full advantage many add-ons improvements available systems commodore 1351 mouse supported geos various ram expansion units geos 128 also fully supports c128 640×200 high-resolution vdc display mode compatible rgb monitor c64 version geos incorporates built-in fast loader called diskturbo significantly increases speed drive access slow 1541 geos first commodore software could use floppy disk swap space virtual memory geos 128 take advantage c128 enhanced burst mode conjunction 1571 1581 drives commodore version geos uses copy protection scheme renders users disks unbootable detects disk illegally duplicated via berkeley special geocable interface converter third-party interfaces connect standard rs-232 centronics printers commodore serial bus geos supports wide variety printers including hp pcl printers apple laserwriter ability print high-end printers major factor making geos desktop publishing platform apple ii version geos released freeware august 2003 commodore 64/128 versions followed february 2004 latest geos desktop suite ibm pc compatibles breadbox ensemble revivals seen omnigo handhelds brother geobook line laptop-appliances newdeal office package pcs related code found way earlier zoomer pdas creating unclear lineage palm inc. later work nokia used geos base operating system nokia communicator series switching epoc symbian august 19 2016 michael steil posted blog source code geos 2.0 commodore c64 fully reverse-engineered cc65 compiler suite reverse-engineered source code made available github dozens official third-party applications products produced geos among important popular following
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Operating systems
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firefox 2 mozilla firefox 2 version firefox web browser released october 24 2006 mozilla corporation firefox 2 uses version 1.8 gecko layout engine displaying web pages release contained many new features found firefox 1.5 including improved support scalable vector graphics svg javascript 1.7 well user interface changes march 22 2006 first alpha version firefox 2 bon echo alpha 1 released featured gecko 1.8.1 first time mozilla firefox 2.0.0.x final version officially supported windows nt 4.0 windows 98 windows although run windows 95 windows nt 3.51 using tweaks mac os x 10.5 support added october 18 2007 version 2.0.0.8 firefox 2.0 featured updates tabbed browsing environment extensions manager gui find search software update engines new session restore feature inline spell checking anti-phishing feature implemented google extension later merged program mozilla ended support firefox 2 december 18 2008 one article noted release firefox 2.0 october 2006 ie6 lion share browser market 77.22 internet explorer 7 climbed 3.18 firefox 2.0 0.69 softpedia article however noted july 2007 firefox 2.0 also expanding share constantly spite ie7 0.69 october 2006 firefox 2.0 accounting 11.07 market mozilla even sacrificed version 1.5 open source browser firefox 2.0 support cut end june firefox 1.5 dropped 2.85 firefox 2 began lose notable market share firefox 3 within 24 hours release firefox 3 usage rose 1 3 according net applications time period firefox 2 market share consistently dropped eventually surpassed firefox 3 2008 firefox 3.5 2009 general browser market firefox version greatest share early 2009 dropped 3 percent firefox 2.x end-of-lifed december 2008 roughly 26 months support firefox 3.6 supported longer gecko 1.8.1 browser core continued receive patches projects camino k-meleon seamonkey even official firefox releases ceased 2011 1.8.1 core become obsolete major websites dropped support employing newer technologies presentation complex scripting latter resource-intensive older core users stuck use noscript avoid problems scripts take long process cost losing site features beyond basic functionality services large user bases relegated browsers gecko 1.8.1 rendering engine using lightweight mobile versions sites alongside recommendations upgrade browser others recommend upgrade nevertheless still large number websites freely usable navigable firefox 2.0 equivalents alone many must still support older browsers like internet explorer 6 ie7
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Internet protocols
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sparrowiq sparrowiq packet-based traffic analysis network performance monitoring solution provides network managers near real-time traffic visibility network usage based conversations applications users class service product developed solana networks ottawa ontario canada allow smaller businesses gain access flow-based network traffic monitoring solutions normally complex unaffordable sparrowiq awarded best new product ascii group june 2015 strong value award enterprise management associates 2013 sparrowiq key features
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Computer security
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vaxeln vaxeln discontinued real-time operating system vax family computers produced digital equipment corporation dec maynard massachusetts rsx-11 vms dave cutler principal force behind development operating system cutler team developed product moving seattle washington area form decwest engineering group dec first engineering group outside new england initial target platforms vaxeln backplane interconnect computers model code-named scorpio time vax microcomputers vaxeln well way cutler spearheaded next project microvax -- first vax microcomputer although low-volume product compared new england-developed microvax ii microvax demonstrated set architectural decisions needed support single-board implementation vax computer family also provided platform embedded applications written vaxeln vaxeln team made decision first release use pascal language system programming language languages including c supported later releases system small focused development team built first product approximately 18 months vaxeln allowed developer write self-contained embedded system application would run vax later microvax hardware operating system present system debuted las vegas early 1980s variety amusing applications written development team ranging system composed played minuets robotic system played solved tower hanoi puzzle system originally supposed named elan executive local area network dec discovered last minute trademarked european country dec wished conduct business company holding trademark elan slovenian sports equipment manufacturer elan order avoid litigation dec quickly renamed vaxeln dropping much disgruntlement developers documentation marketing material already printed referring product elan samples posters prized many years members original team
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Operating systems
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soyombo linux soyombo project based mongolian republic aimed create mongolian language distribution linux full support writing mongolian cyrillic traditional scripts mongolian including soyombo script clear script classical mongolian script discontinued
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Operating systems
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mahdi malware mahdi computer malware initially discovered february 2012 reported july year according kaspersky lab seculert israeli security firm discovered malware software used targeted cyber espionage since december 2011 infecting least 800 computers iran middle eastern countries mahdi named files used malware refers muslim figure
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Computer security
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file system computing file system filesystem often abbreviated fs controls data stored retrieved without file system information placed storage medium would one large body data way tell one piece information stops next begins separating data pieces giving piece name information easily isolated identified taking name way paper-based information systems named group data called file structure logic rules used manage groups information names called file system many different kinds file systems one different structure logic properties speed flexibility security size file systems designed used specific applications example iso 9660 file system designed specifically optical discs file systems used numerous different types storage devices use different kinds media 2019 hard disk drives key storage devices projected remain foreseeable future kinds media used include ssds magnetic tapes optical discs cases tmpfs computer main memory random-access memory ram used create temporary file system short-term use file systems used local data storage devices others provide file access via network protocol example nfs smb 9p clients file systems virtual meaning supplied files called virtual files computed request procfs sysfs merely mapping different file system used backing store file system manages access content files metadata files responsible arranging storage space reliability efficiency tuning regard physical storage medium important design considerations advent computers term file system used describe method storing retrieving paper documents 1961 term applied computerized filing alongside original meaning 1964 general use file system consists two three layers sometimes layers explicitly separated sometimes functions combined logical file system responsible interaction user application provides application program interface api file operations — codice_1 codice_2 codice_3 etc. passes requested operation layer processing logical file system manage open file table entries per-process file descriptors layer provides file access directory operations security protection second optional layer virtual file system interface allows support multiple concurrent instances physical file systems called file system implementation third layer physical file system layer concerned physical operation storage device e.g disk processes physical blocks read written handles buffering memory management responsible physical placement blocks specific locations storage medium physical file system interacts device drivers channel drive storage device note applies file systems used storage devices file systems allocate space granular manner usually multiple physical units device file system responsible organizing files directories keeping track areas media belong file used example apple dos early 1980s 256-byte sectors 140 kilobyte floppy disk used track/sector map results unused space file exact multiple allocation unit sometimes referred slack space 512-byte allocation average unused space 256 bytes 64 kb clusters average unused space 32 kb size allocation unit chosen file system created choosing allocation size based average size files expected file system minimize amount unusable space frequently default allocation may provide reasonable usage choosing allocation size small results excessive overhead file system contain mostly large files file system fragmentation occurs unused space single files contiguous file system used files created modified deleted file created file system allocates space data file systems permit require specifying initial space allocation subsequent incremental allocations file grows files deleted space allocated eventually considered available use files creates alternating used unused areas various sizes free space fragmentation file created area contiguous space available initial allocation space must assigned fragments file modified becomes larger may exceed space initially allocated another allocation must assigned elsewhere file becomes fragmented operating systems system administrator may use disk quotas limit allocation disk space filename file name used identify storage location file system file systems restrictions length filenames file systems filenames case sensitive i.e. names codice_4 codice_5 refer file others filenames case sensitive i.e. names codice_4 codice_7 codice_5 refer three separate files modern file systems allow filenames contain wide range characters unicode character set however may restrictions use certain special characters disallowing within filenames characters might used indicate device device type directory prefix file path separator file type file systems typically directories also called folders allow user group files separate collections may implemented associating file name index table contents inode unix-like file system directory structures may flat i.e linear allow hierarchies directories may contain subdirectories first file system support arbitrary hierarchies directories used multics operating system native file systems unix-like systems also support arbitrary directory hierarchies example apple hierarchical file system successor hfs+ classic mac os fat file system ms-dos 2.0 later versions ms-dos microsoft windows ntfs file system windows nt family operating systems ods-2 on-disk structure-2 higher levels files-11 file system openvms bookkeeping information typically associated file within file system length data contained file may stored number blocks allocated file byte count time file last modified may stored file timestamp file systems might store file creation time time last accessed time file metadata changed time file last backed information include file device type e.g block character socket subdirectory etc owner user id group id access permissions file attributes e.g whether file read-only executable etc. file system stores metadata associated file—including file name length contents file location file folder hierarchy—separate contents file file systems store names files one directory one place—the directory table directory—which often stored like file many file systems put metadata file directory table rest metadata file completely separate structure inode file systems also store metadata associated one particular file metadata includes information unused regions—free space bitmap block availability map—and information bad sectors often information allocation group stored inside allocation group additional attributes associated file systems ntfs xfs ext2 ext3 versions ufs hfs+ using extended file attributes file systems provide user defined attributes author document character encoding document size image file systems allow different data collections associated one file name separate collections may referred streams forks apple long used forked file system macintosh microsoft supports streams ntfs file systems maintain multiple past revisions file single file name filename retrieves recent version prior saved version accessed using special naming convention filename 4 filename -4 access version four saves ago see comparison file systems metadata details file systems support kinds metadata cases file system may make use storage device used organize represent access data whether stored dynamically generated e.g procfs file systems include utilities initialize alter parameters remove instance file system include ability extend truncate space allocated file system directory utilities may used create rename delete directory entries also known dentries singular dentry alter metadata associated directory directory utilities may also include capabilities create additional links directory hard links unix rename parent links .. unix-like operating systems create bidirectional links files file utilities create list copy move delete files alter metadata may able truncate data truncate extend space allocation append move modify files in-place depending underlying structure file system may provide mechanism prepend truncate beginning file insert entries middle file delete entries file utilities free space deleted files file system provides undelete function also belong category file systems defer operations reorganization free space secure erasing free space rebuilding hierarchical structures providing utilities perform functions times minimal activity example file system defragmentation utilities important features file system utilities involve supervisory activities may involve bypassing ownership direct access underlying device include high-performance backup recovery data replication reorganization various data structures allocation tables within file system several mechanisms used file systems control access data usually intent prevent reading modifying files user group users another reason ensure data modified controlled way access may restricted specific program examples include passwords stored metadata file elsewhere file permissions form permission bits access control lists capabilities need file system utilities able access data media level reorganize structures provide efficient backup usually means effective polite users effective intruders methods encrypting file data sometimes included file system effective since need file system utilities know encryption seed effectively manage data risks relying encryption include fact attacker copy data use brute force decrypt data losing seed means losing data one significant responsibility file system ensure regardless actions programs accessing data structure remains consistent includes actions taken program modifying data terminates abnormally neglects inform file system completed activities may include updating metadata directory entry handling data buffered yet updated physical storage media failures file system must deal include media failures loss connection remote systems event operating system failure soft power failure special routines file system must invoked similar individual program fails file system must also able correct damaged structures may occur result operating system failure os unable notify file system power failure reset file system must also record events allow analysis systemic issues well problems specific files directories important purpose file system manage user data includes storing retrieving updating data file systems accept data storage stream bytes collected stored manner efficient media program retrieves data specifies size memory buffer file system transfers data media buffer runtime library routine may sometimes allow user program define record based library call specifying length user program reads data library retrieves data via file system returns record file systems allow specification fixed record length used writes reads facilitates locating n record well updating records identification record also known key makes sophisticated file system user program read write update records without regard location requires complicated management blocks media usually separating key blocks data blocks efficient algorithms developed pyramid structure locating records utilities language specific run-time libraries user programs use file system apis make requests file system include data transfer positioning updating metadata managing directories managing access specifications removal frequently retail systems configured single file system occupying entire storage device another approach partition disk several file systems different attributes used one file system use browser cache might configured small allocation size additional advantage keeping frantic activity creating deleting files typical browser activity narrow area disk interfering allocations files similar partition might created email another partition file system might created storage audio video files relatively large allocation one file systems may normally set read-only periodically set writable third approach mostly used cloud systems use disk images house additional file systems attributes within another host file system file common example virtualization one user run experimental linux distribution using ext4 file system virtual machine his/her production windows environment using ntfs ext4 file system resides disk image treated file multiple files depending hypervisor settings ntfs host file system multiple file systems single system additional benefit event corruption single partition remaining file systems frequently still intact includes virus destruction system partition even system boot file system utilities require dedicated access effectively completed piecemeal addition defragmentation may effective several system maintenance utilities virus scans backups also processed segments example necessary backup file system containing videos along files none added since last backup image files one easily spin differential images contain new data written master original image differential images used safety concerns disposable system quickly restored destroyed contaminated virus old image removed new image created matter seconds even without automated procedures quick virtual machine deployment since differential images quickly spawned using script batches file systems functional limit defines maximum storable data capacity within system functional limits best-guess effort designer based large storage systems right large storage systems likely become future disk storage continued increase near exponential rates see moore law years file systems kept reaching design limitations require computer users repeatedly move newer system ever-greater capacity file system complexity typically varies proportionally available storage capacity file systems early 1980s home computers 50 kb 512 kb storage would reasonable choice modern storage systems hundreds gigabytes capacity likewise modern file systems would reasonable choice early systems since complexity modern file system structures would quickly consume even exceed limited capacity early storage systems file system types classified disk/tape file systems network file systems special-purpose file systems disk file system takes advantages ability disk storage media randomly address data short amount time additional considerations include speed accessing data following initially requested anticipation following data may also requested permits multiple users processes access various data disk without regard sequential location data examples include fat fat12 fat16 fat32 exfat ntfs hfs hfs+ hpfs apfs ufs ext2 ext3 ext4 xfs btrfs iso 9660 files-11 veritas file system vmfs zfs reiserfs udf disk file systems journaling file systems versioning file systems iso 9660 universal disk format udf two common formats target compact discs dvds blu-ray discs mount rainier extension udf supported since 2.6 series linux kernel since windows vista facilitates rewriting dvds flash file system considers special abilities performance restrictions flash memory devices frequently disk file system use flash memory device underlying storage media much better use file system specifically designed flash device tape file system file system tape format designed store files tape self-describing form magnetic tapes sequential storage media significantly longer random data access times disks posing challenges creation efficient management general-purpose file system disk file system typically master file directory map used free data regions file additions changes removals require updating directory used/free maps random access data regions measured milliseconds system works well disks tape requires linear motion wind unwind potentially long reels media tape motion may take several seconds several minutes move read/write head one end tape consequently master file directory usage map extremely slow inefficient tape writing typically involves reading block usage map find free blocks writing updating usage map directory add data advancing tape write data correct spot additional file write requires updating map directory writing data may take several seconds occur file tape file systems instead typically allow file directory spread across tape intermixed data referred streaming time-consuming repeated tape motions required write new data however side effect design reading file directory tape usually requires scanning entire tape read scattered directory entries data archiving software works tape storage store local copy tape catalog disk file system adding files tape done quickly without rescan tape media local tape catalog copy usually discarded used specified period time point tape must re-scanned used future ibm developed file system tape called linear tape file system ibm implementation file system released open-source ibm linear tape file system — single drive edition ltfs-sde product linear tape file system uses separate partition tape record index meta-data thereby avoiding problems associated scattering directory entries across entire tape writing data tape erasing formatting tape often significantly time-consuming process take several hours large tapes many data tape technologies necessary format tape over-writing new data tape due inherently destructive nature overwriting data sequential media time take format tape typically tapes pre-formatted tape user need spend time preparing new tape use usually necessary write identifying media label tape use even automatically written software new tape used first time another concept file management idea database-based file system instead addition hierarchical structured management files identified characteristics like type file topic author similar rich metadata ibm db2 formerly known db2/400 db2 i5/os database file system part object based ibm operating system formerly known os/400 i5/os incorporating single level store running ibm power systems formerly known as/400 iseries designed frank g. soltis ibm former chief scientist ibm around 1978 1988 frank g. soltis team ibm rochester successfully designed applied technologies like database file system others like microsoft later failed accomplish technologies informally known 'fortress rochester basic aspects extended early mainframe technologies many ways advanced technological perspective projects n't pure database file systems use aspects database file system programs need either make multiple file system changes one changes fail reason make none changes example program installing updating software may write executables libraries and/or configuration files writing fails software left partially installed updated software may broken unusable incomplete update key system utility command shell may leave entire system unusable state transaction processing introduces atomicity guarantee ensuring operations inside transaction either committed transaction aborted system discards partial results means crash power failure recovery stored state consistent either software completely installed failed installation completely rolled back unusable partial install left system transactions also provide isolation guarantee meaning operations within transaction hidden threads system transaction commits interfering operations system properly serialized transaction windows beginning vista added transaction support ntfs feature called transactional ntfs use discouraged number research prototypes transactional file systems unix systems including valor file system amino lfs transactional ext3 file system txos kernel well transactional file systems targeting embedded systems tffs ensuring consistency across multiple file system operations difficult impossible without file system transactions file locking used concurrency control mechanism individual files typically protect directory structure file metadata instance file locking prevent tocttou race conditions symbolic links file locking also automatically roll back failed operation software upgrade requires atomicity journaling file systems one technique used introduce transaction-level consistency file system structures journal transactions exposed programs part os api used internally ensure consistency granularity single system call data backup systems typically provide support direct backup data stored transactional manner makes recovery reliable consistent data sets difficult backup software simply notes files changed since certain time regardless transactional state shared across multiple files overall dataset workaround database systems simply produce archived state file containing data point backup software backs interact directly active transactional databases recovery requires separate recreation database state file file restored backup software network file system file system acts client remote file access protocol providing access files server programs using local interfaces transparently create manage access hierarchical directories files remote network-connected computers examples network file systems include clients nfs afs smb protocols file-system-like clients ftp webdav shared disk file system one number machines usually servers access external disk subsystem usually san file system arbitrates access subsystem preventing write collisions examples include gfs2 red hat gpfs ibm sfs dataplow cxfs sgi stornext quantum corporation special file system presents non-file elements operating system files acted using file system apis commonly done unix-like operating systems devices given file names non-unix-like operating systems well device file system represents i/o devices pseudo-devices files called device files examples unix-like systems include devfs linux 2.6 systems udev non-unix-like systems tops-10 operating systems influenced full filename pathname file include device prefix devices containing file systems referred device prefix specifying device without anything following 1970s disk digital tape devices expensive early microcomputer users inexpensive basic data storage system devised used common audio cassette tape system needed write data user notified press record cassette recorder press return keyboard notify system cassette recorder recording system wrote sound provide time synchronization modulated sounds encoded prefix data checksum suffix system needed read data user instructed press play cassette recorder system would listen sounds tape waiting burst sound could recognized synchronization system would interpret subsequent sounds data data read complete system would notify user press stop cassette recorder primitive worked lot time data stored sequentially usually unnamed format although systems commodore pet series computers allow files named multiple sets data could written located fast-forwarding tape observing tape counter find approximate start next data region tape user might listen sounds find right spot begin playing next data region implementations even included audible sounds interspersed data flat file system subdirectories directory entries files stored single directory floppy disk media first available type file system adequate due relatively small amount data space available cp/m machines featured flat file system files could assigned one 16 user areas generic file operations narrowed work one instead defaulting work user areas special attributes associated files necessary define specific quota areas files could added groups long still free storage space disk early apple macintosh also featured flat file system macintosh file system unusual file management program macintosh finder created illusion partially hierarchical filing system top emfs structure required every file unique name even appeared separate folder ibm dos/360 os/360 store entries files disk pack volume directory pack called volume table contents vtoc simple flat file systems become awkward number files grows makes difficult organize data related groups files recent addition flat file system family amazon s3 remote storage service intentionally simplistic allow users ability customize data stored constructs buckets imagine disk drive unlimited size objects similar identical standard concept file advanced file management allowed able use nearly character including '/ object name ability select subsets bucket content based identical prefixes many operating systems include support one file system sometimes os file system tightly interwoven difficult separate file system functions needs interface provided operating system software user file system interface textual provided command line interface unix shell openvms dcl graphical provided graphical user interface file browsers graphical metaphor folder containing documents files nested folders often used see also directory folder unix-like operating systems create virtual file system makes files devices appear exist single hierarchy means systems one root directory every file existing system located somewhere unix-like systems use ram disk network shared resource root directory unix-like systems assign device name device files device accessed instead gain access files another device operating system must first informed directory tree files appear process called mounting file system example access files cd-rom one must tell operating system take file system cd-rom make appear such-and-such directory directory given operating system called mount point – might example /media /media directory exists many unix systems specified filesystem hierarchy standard intended specifically use mount point removable media cds dvds usb drives floppy disks may empty may contain subdirectories mounting individual devices generally administrator i.e root user may authorize mounting file systems unix-like operating systems often include software tools assist mounting process provide new functionality strategies coined auto-mounting reflection purpose linux supports numerous file systems common choices system disk block device include ext* family ext2 ext3 ext4 xfs jfs btrfs raw flash without flash translation layer ftl memory technology device mtd ubifs jffs2 yaffs among others squashfs common compressed read-only file system solaris earlier releases defaulted non-journaled non-logging ufs bootable supplementary file systems solaris defaulted supported extended ufs support file systems significant enhancements added time including veritas software corp. journaling vxfs sun microsystems clustering qfs sun microsystems journaling ufs sun microsystems open source poolable 128 bit compressible error-correcting zfs kernel extensions added solaris allow bootable veritas vxfs operation logging journaling added ufs sun solaris 7 releases solaris 10 solaris express opensolaris open source variants solaris operating system later supported bootable zfs logical volume management allows spanning file system across multiple devices purpose adding redundancy capacity and/or throughput legacy environments solaris may use solaris volume manager formerly known solstice disksuite multiple operating systems including solaris may use veritas volume manager modern solaris based operating systems eclipse need volume management leveraging virtual storage pools zfs macos formerly mac os x uses apple file system apfs recently replaced file system inherited classic mac os called hfs plus hfs+ apple also uses term mac os extended hfs+ hfs plus metadata-rich case-preserving usually case-insensitive file system due unix roots macos unix permissions added hfs plus later versions hfs plus added journaling prevent corruption file system structure introduced number optimizations allocation algorithms attempt defragment files automatically without requiring external defragmenter filenames 255 characters hfs plus uses unicode store filenames macos filetype come type code stored file metadata filename extension hfs plus three kinds links unix-style hard links unix-style symbolic links aliases aliases designed maintain link original file even moved renamed interpreted file system file manager code userland macos 10.13 high sierra announced june 5 2017 apple wwdc event uses apple file system solid-state drives macos also supported ufs file system derived bsd unix fast file system via nextstep however mac os x leopard macos could longer installed ufs volume pre-leopard system installed ufs volume upgraded leopard mac os x lion ufs support completely dropped newer versions macos capable reading writing legacy fat file systems 16 32 common windows also capable reading newer ntfs file systems windows order write ntfs file systems macos versions prior mac os x snow leopard third party software necessary mac os x 10.6 snow leopard later allow writing ntfs file systems non-trivial system setting change third party software exists automates finally macos supports reading writing exfat file system since mac os x snow leopard starting version 10.6.5 os/2 1.2 introduced high performance file system hpfs hpfs supports mixed case file names different code pages long file names 255 characters efficient use disk space architecture keeps related items close disk volume less fragmentation data extent-based space allocation b+ tree structure directories root directory located midpoint disk faster average access journaled filesystem jfs shipped 1999 pc-bsd desktop version freebsd inherits freebsd zfs support similarly freenas new graphical installer pc-bsd handle root zfs raid-z pool installs disk encryption using geli right start easy convenient gui way current pc-bsd 9.0+ 'isotope edition zfs filesystem version 5 zfs storage pool version 28 plan 9 bell labs treats everything file accesses objects file would accessed i.e. ioctl mmap networking graphics debugging authentication capabilities encryption services accessed via i/o operations file descriptors 9p protocol removes difference local remote files file systems plan 9 organized help private per-process namespaces allowing process different view many file systems provide resources distributed system inferno operating system shares concepts plan 9 windows makes use fat ntfs exfat live file system refs file systems last supported usable windows server 2012 windows server 2016 windows 8 windows 8.1 windows 10 windows boot windows uses drive letter abstraction user level distinguish one disk partition another example path c \windows represents directory windows partition represented letter c. drive c commonly used primary hard disk drive partition windows usually installed boots tradition become firmly ingrained bugs exist many applications make assumptions drive operating system installed c. use drive letters tradition using c drive letter primary hard disk drive partition traced ms-dos letters b reserved two floppy disk drives turn derived cp/m 1970s ultimately ibm cp/cms 1967 family fat file systems supported almost operating systems personal computers including versions windows ms-dos/pc dos os/2 dr-dos pc dos oem version ms-dos ms-dos originally based scp 86-dos dr-dos based digital research concurrent dos successor cp/m-86 fat file systems therefore well-suited universal exchange format computers devices type age fat file system traces roots back incompatible 8-bit fat precursor standalone disk basic short-lived mdos/midas project years file system expanded fat12 fat16 fat32 various features added file system including subdirectories codepage support extended attributes long filenames third parties digital research incorporated optional support deletion tracking volume/directory/file-based multi-user security schemes support file directory passwords permissions read/write/execute/delete access rights extensions supported windows fat12 fat16 file systems limit number entries root directory file system restrictions maximum size fat-formatted disks partitions fat32 addresses limitations fat12 fat16 except file size limit close 4 gb remains limited compared ntfs fat12 fat16 fat32 also limit eight characters file name three characters extension .exe commonly referred 8.3 filename limit vfat optional extension fat12 fat16 fat32 introduced windows 95 windows nt 3.5 allowed long file names lfn stored fat file system backwards compatible fashion ntfs introduced windows nt operating system 1993 allowed acl-based permission control features also supported ntfs include hard links multiple file streams attribute indexing quota tracking sparse files encryption compression reparse points directories working mount-points file systems symlinks junctions remote storage links exfat proprietary patent-protected file system certain advantages ntfs regard file system overhead exfat backward compatible fat file systems fat12 fat16 fat32 file system supported newer windows systems windows server 2003 windows vista windows 2008 windows 7 windows 8 recently support added windows xp exfat supported macos starting version 10.6.5 snow leopard support operating systems sparse since microsoft published specifications file system implementing support exfat requires license exfat file system fully supported macos windows hold files larger 4 gb prior introduction vsam os/360 systems implemented unusual hybrid file system system designed easily support removable disk packs information relating files one disk volume ibm terminology stored disk flat system file called volume table contents vtoc vtoc stores metadata file later hierarchical directory structure imposed introduction system catalog optionally catalog files datasets resident removable volumes catalog contains information relate dataset specific volume user requests access dataset offline volume suitable privileges system attempt mount required volume cataloged non-cataloged datasets still accessed using information vtoc bypassing catalog required volume id provided open request still later vtoc indexed speed access ibm conversational monitor system cms component vm/370 uses separate flat file system virtual disk minidisk file data control information scattered intermixed anchor record called master file directory mfd always located fourth block disk originally cms used fixed-length 800-byte blocks later versions used larger size blocks 4k access data record requires two levels indirection file directory entry called file status table fst entry points blocks containing list addresses individual records data as/400 successors consists system objects mapped system virtual address space single-level store many types as/400 objects defined including directories files found file systems file objects along types objects form basis as/400 support integrated relational database may advantageous necessary files different file system currently exist reasons include need increase space requirements beyond limits current file system depth path may need increased beyond restrictions file system may performance reliability considerations providing access another operating system support existing file system another reason cases conversion done in-place although migrating file system conservative involves creating copy data recommended windows fat fat32 file systems converted ntfs via convert.exe utility reverse linux ext2 converted ext3 converted back ext3 converted ext4 back ext3 ext4 converted btrfs converted back undo information deleted conversions possible due using format file data relocating metadata empty space cases using sparse file support migration disadvantage requiring additional space although may faster best case unused space media contain final file system example migrate fat32 file system ext2 file system first create new ext2 file system copy data file system delete fat32 file system alternative sufficient space retain original file system new one created use work area removable media takes longer backup data nice side effect hierarchical file systems files accessed means path branching list directories containing file different file systems different limits depth path file systems also limit length individual filename copying files long names located paths significant depth one file system another may cause undesirable results depends utility copying handles discrepancy
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Computer file systems
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quickschools.com maestro planning solutions early origins providing supply chain management software company founded early 2003 winning venture 2002 business plan writing competition competition organized mckinsey co supported malaysia largest venture capital company mavcap ministry finance malaysia publicity support garnered win company born 2006 maestro made exploratory move schools market via project premier malaysian private school kolej tuanku ja'afar maestro used optimalone platform injected supply chain ideas creation school management system project cross-fertilization ideas supply chain school management system recognized ktj different several school management systems evaluating time january 2008 maestro decided embark launching school administrative software online system subsequently branded quickschools.com fully online school management system small schools april 2009 maestro planning solutions raised 4.5 million malaysian ringgit venture capital funded dta growth capital malaysia financing support quickschool.com expansion us school market strengthen company r well sales marketing efforts also april 2009 maestro received grant 1.06 million malaysian ringgit spearhead r web 2.0 timetable scheduling software eventually part quickschools.com grant awarded mdec multimedia development corporation malaysia august 17 2009 quickschools released brand new version school management system based extensive feedback current user base approach software design decided upon best way forward focused improving user experience therefore attention give introducing simple user interface extensive feature hiding one key improvements allow users running minutes administrator simply registers his/her school website along custom domain school software automatically creates publishes fully functional school management system real time admin proceed 'invite teachers faculty test system another improvement involves 'livefeed feature creates notifications certain activities take place essential paradigm shift achieved way software reformats match user requirements features required specific school made available making software easy use makes barriers entry almost negligible quickschool long-term goal create software require technical support training release goes long way achieving system allows users log details inquiries parents guardians keep track contact details student applications also maintained along grades achieved entrance exams details picture subjects taken classes attended grades extra-curricular activities tracked student grading also done end term reports printed pdf parents track progress children daily basis makes hard student wants cut missing assignment plain tardy system sending parents e-mail notification soon teacher marks student late/absent schedules generated students teachers subjects classrooms flexible type information school wants track students foreign language character support arabic chinese currently available quickschools.com based maestro optimalone platform quickschools.com runs java ee backend front-end runs adobe flash previously macromedia flash use flash enables quickschools.com run many different browsers different operating systems also enables web2.0-style interface servers located 2 locations around world first location established malaysia january 2008 second location established seattle us august 2008
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Distributed computing architecture
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check point vpn-1 vpn-1 firewall vpn product developed check point software technologies ltd. vpn-1 stateful firewall also filters traffic inspecting application layer first commercially available software firewall use stateful inspection later 1997 check point registered u.s. patent 5,606,668 security technology among features included stateful inspection vpn-1 functionality currently bundled within check point perimeter security products product previously known firewall-1 sold integrated firewall vpn solution vpn-1 software installed separate operating system provides protocol stack file system process scheduling features needed product different commercial firewall products like cisco pix juniper firewalls firewall software part proprietary operating system although traditionally sold software vpn-1 also sold appliance form check point utm-1 starting 2006 power-1 appliances appliances run secureplatform operating system version r70 vpn-1 supports following operating systems previous versions check point firewall supported operating systems including solaris hp-ux aix see table version history section details vpn-1 running nokia platform ipso often called nokia firewall different product fact runs vpn-1 software platforms upon completing acquisition nokia security appliance business 2009 checkpoint started project named gaia aimed merging two different operating systems—secureplatform ipso—into one new os positioned finally replace existing operating systems point future april 17 2012 check point announced general availability gaia operating system part r75.40 release started pure firewall vpn product later features added licensed separately since began bundled default installations vpn-1 well smartdefense ips feature adds built-in stateful inspection inherent tcp/ip protocols checks normalization inspection common application protocols starting ngx r70 feature rebranded ips quality service floodgate-1 checkpoint implementation quality service qos supports bandwidth guaranteeing limiting per qos rule per connection also priority queuing done llq nevertheless rfc based qos implementation differentiated services ip precedence supported content inspection starting ngx r65 new feature introduced providing 2 services
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Computer security
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samsung sgh-i550w samsung sgh-i550w mobile phone samsung belongs infotainment class wi-fi 3.5g connectivity play various multimedia formats 3.2 megapixel camera runs s60 software 3rd edition feature pack 1
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Operating systems
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fujitsu cloud iaas trusted public s5 fujitsu cloud iaas trusted public s5 fujitsu cloud computing platform aims deliver standardized enterprise-class public cloud services globally offers infrastructure-as-a-service iaas fujitsu data centers provide computing resources employed on-demand suited customers needs service ensures high level reliability sufficient deployment mission-critical systems japan service offered on-demand virtual system service oviss launched globally fujitsu global cloud platform/s5 fgcp/s5 since july 2013 service called iaas trusted public s5 globally service operated fujitsu data centers located australia singapore united states united kingdom germany fujitsu also launched windows azure powered global cloud platform partnership microsoft platform-as-a-service paas offering known fgcp/a5 japan since renamed fujitsu cloud paas a5 windows azure operated fujitsu data center japan offers set application development frameworks microsoft .net java php data storage capabilities consistent windows azure platform provided microsoft basic service consists compute storage microsoft sql azure windows azure appfabric technologies service bus access control service options interoperating services covering implementation migration applications system building systems operation support 2015 fujitsu launched next generation cloud service k5 deployed globally october 2018 fujitsu announced discontinuing k5 regions except japan october 16 2018 company stated hire 10,000 employees train use microsoft azure order address see industry-wide shortage cloud related skills help clients address execution gap provision services support operational efficiency digital co-creation multi-cloud management. ” fujitsu launched global cloud strategy april 2010 provision services platform offered trial basis 200 companies japan following month fujitsu announced general availability iaas service japan name on-demand virtual system service oviss starting 1 october 2010 part service global rollout launched australia name fujitsu global cloud platform fgcp february 2011 followed launches march 2011 singapore may 2011 united kingdom germany united states america july 2012 fujitsu added center western japan bring total number seven july 2013 fujitsu announced fujitsu cloud initiative globally also announced new name fujitsu cloud iaas trusted public s5 october 2018 fujitsu announced discontinuing k5 regions except japan basic component iaas trusted public s5 called virtual system consists firewall one multiple network segments customers host virtual machines signed customers deploy multiple systems within environment much like virtual data center iaas trusted public s5 employs templates allow customers quickly deploy virtual systems template consists firewall network segment definitions virtual servers os/middleware installed set allows quick selection example system three network zones pre-installed web server dmz application server secure zone database another secure zone virtual system includes firewall control access network segments internet intranet intranet connection communication virtual servers customers existing servers hosted fujitsu data center virtual servers chosen list pre-defined images operating system installed also additional software servers different computational resources offered operating systems offered globally include windows server 2008 windows server 2012 red hat enterprise linux centos ubuntu fujitsu claimed licensing issue prevents delivery microsoft office cloud service web based devices manner similar google docs virtual server system disk pre-defined size additional disks sizes configurable 10 gb 10 tb attached server running customers provision global ip addresses assign virtual servers similar amazon elastic ip address feature users provision manage virtual systems self-service portal also used initiate vpn connection virtual zone operations offered service portal also offered cloud api api xml-rpc based using ssl encrypt messages certificates authentication operations also possible multi-cloud api apache deltacloud fujitsu submitted cloud api specification distributed management task force open cloud standards incubator promote open standards cloud interoperability contributed dmtf cloud infrastructure management interface cimi standard july 2013 fujitsu demonstrated client using cimi manage system iaas trusted public s5 management developers conference servers physically located fujitsu tier iii data centers japan australia singapore uk us germany
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Distributed computing architecture
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texas instruments ar7 texas instruments ar7 ti-ar7 fully integrated single-chip adsl cpe access router solution ar7 combines mips32 processor dsp-based digital transceiver adsl analog front end 2007 ti sold dsl business infineon 2009 infineon technologies spins wireline division lantiq november 6 2009 lantiq announced became standalone company
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Computer architecture
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statcounter statcounter web traffic analysis website started 1999 access basic services free advanced services cost us 119 month statcounter based dublin ireland statistics statcounter used compute web usage share example statcounter used 0.9 websites statcounter statistics directly derived hits—as opposed unique visitors—from 3 million sites use statcounter resulting total hits 15 billion per month artificial weightings used correct sampling bias thus numbers statistics considered representative samples company founded aodhán cullen age 16 cullen received internet hero award 2008 eircom golden spider awards also named 2007 businessweek young european entrepreneur year 2008 company surpassed two million members globally
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Web technology
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hookflash hookflash canadian company hookflash also name product family real-time communication people work together founders trent johnsen erik lagerway hookflash ipad first product ios app announced demo fall 2011 conference tested private release offers users hookflash-to-hookflash instant messaging voice calling conferencing video calling conferencing hookflash openpeer peer-to-peer network app also business telephony features like call transfer line hunting social network features like profiles activity data sources like linkedin sharing recorded conversations company announced ipad app free company operate freemium business model
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Internet protocols
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epic web browser epic privacy-centric web browser developed hidden reflex software product company founded alok bhardwaj based washington dc bangalore india chromium source code epic always private browsing mode exiting browser causes browsing data deleted even browsing little possible stored epic developers remove google tracking code binaries chromium source code compile clean executable blocks companies tracking users browser connection electronic privacy information center civil liberties group also known epic epic released august 29 2013 customized indian users browser integrated widgets social networking chat clients email facilities epic default configuration takes proactive approach ensuring session data cookies history cache removed upon exit browser includes proxy service enabled user discretion automatically enabled using search engine features preferring ssl connections always sending track header advance privacy however many implementations extension based part core browser code epic browser extension based feature implementation allow users extract import extensions chromium based browsers chrome extension developer mode ad user activity trackers blocked default epic browser prevents user tracking occur browser also blocks cryptocurrency miners running users system browsers fingerprinting protection blocks access image canvas font canvas audio context data webrtc ip address leaking blocked default well epic proxy service relay connections user 8 countries including united states united kingdom canada germany france netherlands india singapore company claims encrypted routes dns requests well supplementary services found chromium browser send data external servers address bar suggestion installation tracking removed epic reduce scope potential data leakage epic supports windows 7 later mac os x list web browsers
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Internet protocols
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potentially unwanted program potentially unwanted program pup potentially unwanted application pua software user may perceive unwanted used subjective tagging criterion security parental control products software may use implementation compromise privacy weaken computer security companies often bundle wanted program download wrapper application may offer install unwanted application cases without providing clear opt-out method antivirus companies define software bundled potentially unwanted programs include software displays intrusive advertising adware tracks user internet usage sell information advertisers spyware injects advertising web pages user looks uses premium sms services rack charges user practice widely considered unethical violates security interests users without informed consent unwanted software bundles install root certificate user device allows hackers intercept private data banking details without browser giving security warnings united states department homeland security advised removing insecure root certificate make computers vulnerable serious cyberattacks growing number open-source software projects expressed dismay third-party websites wrapping downloads unwanted bundles without project knowledge consent nearly every third-party free download site bundles downloads potentially unwanted software software developers security experts recommend people always download latest version official project website trusted package manager app store historically first big companies working potentially unwanted programs creating revenue came usa mid-2000s zango activities declined companies investigated cases indicted authorities invasive harmful installs major industry dedicated creating revenue foisting potentially unwanted programs grown among israeli software industry frequently referred download valley companies responsible large part download install tools place unwanted additional software users systems unwanted programs increased recent years one study 2014 classified unwanted programs comprising 24.77 total malware infections malware includes adware according google many programs include unwanted browser add-ons track websites user goes order sell information advertisers add advertising web pages five percent computer browser visits google-owned websites altered computer programs inject ads pages researchers identified 50,870 google chrome extensions 34,407 programs inject ads thirty-eight percent extensions 17 percent programs catalogued malicious software rest potentially unwanted adware-type applications google chrome extension developers sold extensions made third-party companies silently push unwanted updates incorporate previously non-existent adware extensions spyware programs install proxy server person computer monitors web traffic passing tracking user interests build profile sell profile advertisers superfish advertising injector creates root certificate computer operating system allowing tool inject advertising encrypted google search pages track history user search queries february 2015 united states department homeland security advised uninstalling superfish associated root certificate lenovo computers make computers vulnerable serious cyberattacks including interception passwords sensitive data transmitted browsers heise security revealed superfish certificate included bundled downloads number applications companies including say media lavasoft ad-aware web companion many companies use browser hijacking modify user home page search page force internet hits particular website make money advertisers companies steal cookies user browser hijacking connections websites logged performing actions using account without user knowledge consent like installing android apps users dial-up internet access use modems computer connect internet targeted fraudulent applications used security holes operating system dial premium numbers many android devices targeted malware use premium sms services rack charges users 2015 research emsisoft suggested free download providers bundled downloads potentially unwanted software download.com worst offender lowell heddings expressed dismay sadly even google top results open source freeware ads really terrible sites bundling crapware adware malware top installer december 2011 gordon lyon published strong dislike way download.com started bundling grayware installation managers concerns bundled software causing many people spread post social networks dozen media reports main problem confusion download.com-offered content software offered original authors accusations included deception well copyright trademark violation 2014 register us-cert warned via download.com foistware attacker may able download execute arbitrary code many open-source software developers expressed frustration dismay work packaged companies profit work using search advertising occupy first result search page increasingly pages offering bundled installers include unwanted software confuse users presenting bundled software official download page endorsed open source project early 2016 longer case ownership sourceforge transferred sourceforge media llc subsidiary bizx llc bizx sale removed devshare program means bundled installers longer available november 2013 gimp free image manipulation program removed download sourceforge citing misleading download buttons potentially confuse customers well sourceforge windows installer bundles third-party offers statement gimp called sourceforge useful trustworthy place develop host floss applications faces problem ads allow sites ... may 2015 gimp windows sourceforge project transferred ownership sourceforge editorial staff account adware downloads re-enabled happened developers nmap may 2015 sourceforge took control projects migrated hosting sites replaced project downloads adware-laden downloads gordon lyon lost control nmap sourceforge page sourceforge taking project page lyon stated far seem providing official nmap files long n't click fake download buttons n't caught trojaning nmap way gimp certainly n't trust one bit sourceforge pulling scheme cnet download.com tried back started circling drain videolan expressed dismay users searching product see search advertising websites offer bundled downloads include unwanted programs videolan lacks resources sue many companies abusing trademarks
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Computer security
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g.ho.st g.ho.st usually pronounced ghost trading name ghost inc. service name url company hosted computer operating system web desktop service name acronym global hosted operating system old url g.ho.st domain hack using são tomé príncipe .st country extension april 2010 ghost closed service due competition lack funding g.ho.st service provided web-based working environment mimicked classic desktop provided personal computer operating systems users able create save return working environment different physical computers mobile phones g.ho.st called virtual computer services considered operating systems traditional sense although sometimes referred web operating systems whilst include gui e.g desktop virtual file system application management security contain kernel interface physical hardware therefore use service operating system required supporting least web browser service run july 2009 software entered beta stage development remained stage beta launch near jerusalem attended quartet representative former uk prime minister tony blair company primary investor benchmark capital g.ho.st hosted amazon web services utilizing cloud computing backend delivering consumer version cloud computing according g.ho.st website longer accessible planned additionally offer commercial fully featured scalable private cloud file system ghost cloud file system cfs would run within customer amazon web services account business model would based surcharges ghost collected amazon company received growing press coverage relating technology israelis palestinians worked partners build company products time considered joint palestinian israeli technology startup company first company offer employee stock options palestinian territories march 3 2010 ghost.cc formed g.ho.st sent users following e-mail dear ghost user hope enjoying free ghost service regrettably changes marketplace mean longer economical us host ghost service closing service around march 15 instead focusing licensing selling technology larger companies advise migrate important folders files emails another secure place march 15 might like consider google docs microsoft skydrive files services gmail yahoo mail email instructions migrating data included really sorry inconvenience may cause grateful fantastic support community similar services
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Distributed computing architecture
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fire hawk thexder second contact fire hawk thexder second contact テグザー2 ファイアーホーク also known firehawk thexder 2 firehawk thexder ii video game developed published game arts msx2 ms-dos pc-8801 1989 sequel thexder japan ms-dos version later released sierra on-line one predicted furious arcade action high-resolution graphics 11 complete songs ... thexder ii looks set surpass success original game indeed well received upon release sold well japan usa
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Computer architecture
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project denver project denver codename microarchitecture designed nvidia implements armv8-a 64/32-bit instruction sets using combination simple hardware decoder software-based binary translation dynamic recompilation denver binary translation layer runs software lower level operating system stores commonly accessed already optimized code sequences 128 mb cache stored main memory denver wide in-order superscalar pipeline design makes suitable integration sips cores e.g gpu display controller dsp image processor etc one die constituting system chip soc project denver targeted mobile computers personal computers servers well supercomputers respective cores found integration tegra soc series nvidia initially denver cores available 28nm structure sizes tegra model t132 aka tegra k1 later updated denver 2 design worked 16nm structure sizes tegra model t186 aka tegra x2 2018 got published refined follow design codename carmel based armv8 64-bit variant arm-v8.2 10-way superscalar functional safety dual execution parity ecc got integrated tegra xavier soc offering total 8 cores 4 dual-core pairs carmel cpu core supports full advanced simd arm neon vfp vector floating point armv8.2-fp16 first published testings carmel cores integrated jetson agx development kit third party experts took place september 2018 indicated noticeably increased performance expected real world physical manifestation compared predecessors systems despite doubts used quickness test setup general particular implies carmel design found tegra model t194 tegra xavier designed 12 nm structure size dual-core denver cpu paired kepler-based gpu solution form tegra k1 dual-core 2.3 ghz denver-based k1 first used htc nexus 9 tablet released november 3 2014 note however quad-core tegra k1 using name n't based denver nvidia tegra x2 two denver2 armv8 64bit cores inside another four a57 armv8 64bit cores using coherent hmp heterogeneous multi-processor architecture approach pairs units parker-gpu tegra xavier pairing nvidia volta-gpu several special purpose accelerators 8 cpu cores carmel design design 4 carmel asic macro blocks 2 cores matched one crossbar 4 mib l3 memory existence project denver revealed 2011 consumer electronics show march 4 2011 q article ceo jen-hsun huang revealed project denver five-year 64-bit armv8-a architecture cpu development hundreds engineers already worked three half years also 32-bit arm instruction set armv7 backward compatibility project denver started stexar company colorado x86-compatible processor using binary translation similar projects transmeta stexar acquired nvidia 2006 according tom hardware engineers intel amd hp sun transmeta denver team extensive experience designing superscalar cpus out-of-order execution long instruction words vliw simultaneous multithreading smt according charlie demerjian project denver cpu may internally translate arm instructions internal instruction set using firmware cpu also according demerjian project denver originally intended support arm x86 code using code morphing technology transmeta changed armv8-a 64-bit instruction set nvidia could obtain license intel patents first consumer device shipping denver cpu cores google nexus 9 announced october 15 2014 tablet manufactured htc features dual-core tegra k1 soc nexus 9 also first 64-bit android device available consumers
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Computer architecture
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péter szőr péter szőr 17 july 1970 – 12 november 2013 hungarian computer virus security researcher entrepreneur author born balatonfüred veszprém county szőr began interest computer viruses 1990 university pannonia graduate authored several virus-related books renowned work 2009 death worked mcafee antivirus firm working new solution stop viruses early 2004 péter szőr son daniel szőr spouse natalia nemeth may 2014 virus bulletin introduced péter szőr award given annually recognition best piece technical security research done year péter szőr died 12 november 2013 aged 43
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Computer security
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doors extension language doors extension language dxl scripting language used extend functionality ibm rational doors programming language somewhat similar c c++ language specific doors syntax declaration forum discuss development addition specific reference manuals dxl scripts utilized help users doors much native doors gui written dxl dxl used client-server based doors classic used newer web-based doors next generation several ways use dxl rational doors dxl scripts usually stored extension dxl however use library files extension .inc print hello world following code used print hello world sodius dxl editor built top eclipse one tool provides option edit browse compile execute debug dxl scripts many open source free editors like notepad++ jedit support dxl custom properties
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Programming language topics
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input/output base address x86 architecture input/output base address first address range consecutive read/write addresses device uses x86 io bus base address sometimes called i/o port
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Computer architecture
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andy hertzfeld andy hertzfeld born april 6 1953 american computer scientist inventor member original apple macintosh development team 1980s buying apple ii january 1978 went work apple computer august 1979 march 1984 designer macintosh system software since leaving apple co-founded three companies radius 1986 general magic 1990 eazel 1999 2002 helped mitch kapor promote open source software open source applications foundation hertzfeld worked google 2005 2013 2011 key designer circles user interface google+ graduating brown university computer science degree 1975 hertzfeld attended graduate school university california berkeley 1978 bought apple ii computer soon began developing software hired apple computer systems programmer 1979 developed apple silentype printer firmware wrote firmware sup r'terminal first 80-column card apple ii early 1980s invited high school friend artist susan kare join apple order help design would become standard macintosh icons first macintosh hertzfeld wrote icon editor font editor susan kare could design symbols used operating system hertzfeld member apple macintosh design team shakeup apple ii team hertzfeld request apple co-founder steve jobs added nearly two-year-old macintosh team february 1981 working bud tribble alongside bill atkinson burrell smith hertzfeld became primary software architect macintosh operating system considered revolutionary use graphical user interface gui jef raskin also made contributions hertzfeld business card apple listed title software wizard wrote large portions macintosh original system software including much rom code user interface toolbox number innovative components standard many graphic user interfaces like control panel scrapbook hertzfeld book revolution valley insanely great story mac made chronicles development macintosh launch since leaving apple 1984 hertzfeld co-founded three new companies – radius 1986 general magic 1990 eazel 1999 eazel helped create nautilus file manager linux gnome desktop volunteered open source applications foundation 2002 2003 writing early prototypes chandler information manager 1996 hertzfeld interviewed robert cringely television documentary triumph nerds interviewed cringely nerdtv 2005 early 2004 started folklore.org web site devoted collective storytelling contains dozens anecdotes development original macintosh stories collected o'reilly book revolution valley published december 2004 august 2005 hertzfeld joined google june 28 2011 google announced google+ latest attempt social networking hertzfeld key designer google+ circles component user interface entire project mistakenly claimed also worked picasa gmail profile image selector retired google july 2013 october 2018 investor startup spatial hertzfeld portrayed elden henson 2013 film jobs michael stuhlbarg 2015 film steve jobs steve jobs film herztfeld stated almost nothing like really happened ultimately said film n't aiming realism hertzfeld wife live palo alto california
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Operating systems
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internet 0 internet 0 low-speed physical layer designed route 'ip anything developed mit center bits atoms neil gershenfeld raffi krikorian danny cohen invented number proposals labelled internet 2 name chosen emphasize designed slow inexpensive internetworking system forestall high-performance comparison questions fast effectively would enable platform pervasive computing -- everything building could network share data gathering actuation light switch could turn light bulb sending packet linked together user internet 0 originally minor expedient bit engineering support mit projects intended network buildings improve efficiency gather data control hvac systems heating ventilation air conditioning protocol works pretty well wide variety media wide utility multiple media protocol interested network theorists awakened burst academic papers started commercial interest simple inexpensive implementation still appeals hobbyists students new implementations found 2011 modern implementations mostly software small microcontrollers usually transistor transmit capacitors isolate transmitter receiver connector literally becomes major expense communication system simple inexpensive system embedded many devices allow data retrieval control via internet -- small devices used form internet things current largest deployment internet 0 venice biennale architecture exhibition year 2008 group led institute advanced architecture catalonia directed architect vicente guallart idea behind internet 0 provide general-purpose physical layer operates well many media similar morse code general-purpose layer 1 internet logically recursive application internet principle ubiquitous protocol layer 1 network pulse-position modulation internet 0 operates best segregated wire works many media tested radio frequency rf infrared ir ultrasonics optical dc ac power wiring even physical representations printed bar codes engraving key one main advantages approach routers become simple sensor pulse reshaper transmitter coupling reusable physical layer internet protocols enables network inexpensive nodes also addressable global internet design intent provide simple inexpensive system transmit data slowly many types media yet still connect devices internet connecting internet crucial part design much value networked device provided easy wide access higher layers internet 0 network usually serial line internet protocol slip internet protocol ip usually user datagram protocol udp rarely transmission control protocol tcp protocol layers chosen need minimum code keep expense computer low internet 0 implemented small avr microcontrollers existing implementations layers distinct small code important elegant design small translation device normally attaches local network internet 0 devices serial port pc acts gateway firewall internet devices talk directly without requiring server distributed architecture ensures central point failure address assignment cryptographic key initialization sometimes performed closing contact device master controller broadcast assignment message security via simplified encryption system internet 0 similar serial port running 9600 baud except sends data pulse-position modulation accepts 30 timing deviations medium broadcast half duplex software receiving devices examines ip address packet rejecting unwanted packets zero bit one-microsecond pulse center first half bit time one pulse second half bit time data sent 8 bit bytes byte preceded bit time two pulses 1 0 times ends bit time another two pulses variations stop bit-time optional dual-pulse bit times treated byte separators dual-pulse start stop bit times permit receiver synchronize beginnings bytes also measure baud rate sender synchronizing 8-bit bytes permits 9600 baud internet-0 connection easily translate standard low-speed 19,200 baud tcp/ip serial port baud rate measurement permits senders receivers use inexpensive low-precision oscillators ceramic resonators resistor-capacitor oscillators common interface uses power supply wiring device circuit small surface mounted capacitor ac mains wire dc power wire single digital pin small microcontroller switches high-power transistor briefly pulses normally generated software toggle digital i/o pin microcontroller received another capacitor microcontroller pin configured interrupt hardware timer gate internet 0 works many media given transmission medium usually competing preexisting physical layers reliable higher speed lower power usually flexible rarely inexpensive less surprising early exploration concept sun microsystems cisco systems schneider electric interested commercial deployment schneider eventually decided deploy zigbee low-powered radio protocol
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Internet protocols
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scripting language scripting script language programming language special run-time environment automates execution tasks tasks could alternatively executed one-by-one human operator scripting languages often interpreted rather compiled primitives usually elementary tasks api calls language allows combined programs environments automated scripting include software applications web pages within web browser usage shells operating systems os embedded systems well numerous games scripting language viewed domain-specific language particular environment case scripting application also known extension language scripting languages also sometimes referred high-level programming languages operate high level abstraction control languages particularly job control languages mainframes term scripting language also used loosely refer dynamic high-level general-purpose languages perl powershell python tcl term script often used small programs thousand lines code languages domain-specific languages text-processing languages sed awk languages originally developed use within particular environment later developed portable domain-specific general-purpose languages conversely many general-purpose languages dialects used scripting languages article discusses scripting languages narrow sense languages specific environment spectrum scripting languages ranges small highly domain-specific languages general-purpose programming languages used scripting standard examples scripting languages specific environments include bash unix unix-like operating systems ecmascript javascript web browsers visual basic applications microsoft office applications lua language designed widely used extension language python general-purpose language also commonly used extension language ecmascript still primarily scripting language web browsers also used general-purpose language emacs lisp dialect lisp emacs editor visual basic applications dialect visual basic examples scripting language dialects general-purpose languages game systems notably second life virtual world trainz franchise railroad simulators extensively extended functionality scripting extensions linden scripting language trainzscript games like wesnoth variety actual games played players scripts written users typical scripting languages intended fast learn write either short source code files interactively read–eval–print loop repl language shell generally implies relatively simple syntax semantics typically script code written scripting language executed start finish script explicit entry point example uncommon characterise java scripting language lengthy syntax rules classes exist files directly possible execute java interactively source files contain definitions must invoked externally host application application launcher public class helloworld piece code intended print hello world nothing main declared helloworld class contrast python allows definition functions single file avoid functions altogether use imperative programming style even use interactively codice_1 one line python code prints hello world declarative statement like main required scripting language usually interpreted source code bytecode contrast software environment scripts written typically written compiled language distributed machine code form scripting languages may designed use end users program—end-user development—or may internal use developers write portions program scripting language scripting languages typically use abstraction form information hiding spare users details internal variable types data storage memory management scripts often created modified person executing also often distributed large portions games written scripting language early mainframe computers 1950s non-interactive instead using batch processing ibm job control language jcl archetype languages used control batch processing first interactive shells developed 1960s enable remote operation first time-sharing systems used shell scripts controlled running computer programs within computer program shell calvin mooers trac language generally credited inventing command substitution ability embed commands scripts interpreted insert character string script multics calls active functions louis pouzin wrote early processor command scripts called runcom ctss around 1964 stuart madnick mit wrote scripting language ibm cp/cms 1966 originally called processor command later named exec multics included offshoot ctss runcom also called runcom exec eventually replaced exec 2 rexx languages tcl lua specifically designed general-purpose scripting languages could embedded application languages visual basic applications vba provided strong integration automation facilities underlying system embedding general-purpose scripting languages instead developing new language application also obvious benefits relieving application developer need code language translator scratch allowing user apply skills learned elsewhere software incorporates several different scripting languages modern web browsers typically provide language writing extensions browser several standard embedded languages controlling browser including javascript dialect ecmascript xul scripting often contrasted system programming ousterhout dichotomy programming large programming small view scripting particularly glue code connecting software components language specialized purpose glue language pipelines shell scripting archetypal examples glue languages perl initially developed fill role web development considered use glue languages interfacing database web server substantial amount logic written script better characterized simply another software component glue glue languages especially useful writing maintaining glue language examples macro languages exposed operating system application components serve glue languages include visual basic applications wordbasic lotusscript corelscript hummingbird basic quickscript saxbasic winwrap basic tools like awk also considered glue languages language implemented windows script host engine vbscript jscript vba default windows third-party engines including implementations rexx perl tcl python xslt ruby modern pascal delphi c majority applications access use operating system components via object models functions devices like programmable calculators may also glue languages operating systems pdas windows ce may available native third-party macro tools glue applications together addition implementations common glue languages—including windows nt ms-dos unix shells rexx modern pascal php perl depending upon os version wsh default script engines vbscript jscript available programmable calculators programmed glue languages three ways example texas instruments ti-92 factory default programmed command script language inclusion scripting glue language lua ti-nspire series calculators could seen successor primary on-board high-level programming languages graphing calculators often basic variants sometimes lisp derivatives uncommonly c derivatives many cases glue together calculator functions—such graphs lists matrices etc third-party implementations comprehensive basic version may closer variants listed glue languages article available—and attempts implement perl rexx various operating system shells ti hp graphing calculators also mentioned pc-based c cross-compilers ti hp machines used conjunction tools convert c perl rexx awk well shell scripts perl modern pascal vbscript perl make possible write program glue language eventual implementation compiled program calculator major class scripting languages grown automation job control relates starting controlling behavior system programs sense one might think shells descendants ibm jcl job control language used exactly purpose many languages interpreters double command-line interpreters unix shell ms-dos codice_2 others applescript offer use english-like commands build scripts advent graphical user interfaces specialized kind scripting language emerged controlling computer languages interact graphic windows menus buttons human user would simulating actions user languages typically used automate user actions languages also called macros control simulated key presses mouse clicks well tapping pressing touch-activated screen languages could principle used control gui application practice use limited use needs support application operating system exceptions limitation gui scripting languages based recognizing graphical objects display screen pixels gui scripting languages depend support operating system application application specific languages split many different categories i.e standalone based app languages executable internal application specific languages postscript xml gscript widely distributed scripts respectively implemented adobe ms google among others include idiomatic scripting language tailored needs application user likewise many computer game systems use custom scripting language express programmed actions non-player characters game environment languages sort designed single application may superficially resemble specific general-purpose language e.g quakec modeled c custom features distinguish emacs lisp fully formed capable dialect lisp contains many special features make useful extending editing functions emacs application-specific scripting language viewed domain-specific programming language specialized single application number languages designed purpose replacing application-specific scripting languages embeddable application programs application programmer working c another systems language includes hooks scripting language control application languages may technically equivalent application-specific extension language application embeds common language user gets advantage able transfer skills application application generic alternative simply provide library often c library general-purpose language use control application without modifying language specific domain javascript began primarily still language scripting inside web browsers however standardisation language ecmascript made popular general-purpose embeddable language particular mozilla implementation spidermonkey embedded several environments yahoo widget engine applications embedding ecmascript implementations include adobe products adobe flash actionscript adobe acrobat scripting pdf files tcl created extension language come used frequently general-purpose language roles similar python perl ruby hand rexx originally created job control language widely used extension language well general-purpose language perl general-purpose language oraperl 1990 dialect consisting perl 4 binary oracle call interface compiled however since replaced library perl module dbd :oracle complex task-oriented applications may incorporate expose embedded programming language allow users control give functionality available user interface matter sophisticated example autodesk maya 3d authoring tools embed mel scripting language blender uses python fill role types applications need faster feature addition tweak-and-run cycles e.g game engines also use embedded language development allows prototype features faster tweak freely without need user intimate knowledge inner workings application rebuild tweak take significant amount time scripting languages used purpose range common famous lua python lesser-known ones angelscript squirrel ch another c compatible scripting option industry embed c/c++ application programs
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Programming language topics
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retina-x studios retina-x studios software manufacturer company develops computer cell phone monitoring applications focused computers smartphones tablets networks company founded 1997 based jacksonville florida united states company founded july 1997 primarily web consulting design company 2003 period developing monitoring products outside companies company began creating monitoring software products using brand name first software product named acespy released april 28 2003 may 2007 company developed released first monitoring software mobile phones named mobile-spy particularly windows mobile target audiences retina-x studios parents employers parents employers use legal monitoring software check teens staff internet use legal since juveniles responsibility parents company markets products spy applications parents review child messages call details without child knowledge cases ethical issues arise employees made aware monitoring tools personal emails intentionally accessed managers involved directly evaluating contents logging activities be/become biased towards person whose email reviewed using cell phones spying also increased due multiplication smart phones compromising one information possible spy apps people stalk easily company software need onetime access gadget software would run invisibly wrong use software overlooked hackers access online information parsed customer account lead privacy issues
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Computer security
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database scalability database scalability ability database handle changing demands adding/removing resources databases adopted host techniques cope initial history database scalability provide service ever smaller computers first database management systems ims ran mainframe computers second generation including ingres informix sybase rdb oracle emerged minicomputers third generation including dbase oracle ran personal computers period attention turned handling data demanding workloads one key software innovation late 1980s reduce update locking granularity tables disk blocks individual rows eliminated critical scalability bottleneck coarser locks could delay access rows even though directly involved transaction earlier systems completely insensitive increasing resources software limitations addressed attention turned hardware innovation occurred many areas first support multiprocessor computers involved allowing multiple processors handle database requests simultaneously without blocking evolved support multi-core processors much significant change involved allowing distributed transactions affect data stored separate computers using two-phase commit protocol establishing shared-nothing architecture still later oracle introduced shared-everything architecture provided full functionality multi-server clusters another innovation storing copies tables multiple computers database replication improved availability processing could continue copy even main system unavailable scalability particularly query/analysis requests could routed copy primary reached capacity early twenty-first century nosql systems gained favor relational databases workloads motivations included still greater scalability support documents non-relational data types often sacrificed strict acid consistency protocols guaranteed perfect consistency times favor eventual consistency ensured nodes would eventually return latest data even allowed transactions occasionally lost long system could handle sufficiently many requests prominent early system google bigtable/mapreduce developed 2004 achieved near-linear scalability across multiple server farms cost features multi-row transactions joins 2007 first newsql system h-store developed newsql systems attempt combine nosql scalability acid transactions sql interfaces database scalability three basic dimensions amount data volume requests size requests requests come many sizes transactions generally affect small amounts data may approach thousands per second analytic queries generally fewer may access data related concept elasticity ability system transparently add subtract capacity meet changing workloads vertical database scaling implies database system fully exploit maximally configured systems including typically multiprocessors large memories vast storage capacity systems relatively simple administer may offer reduced availability however single computer maximum configuration workloads expand beyond limit choices either migrate different still larger system rearchitect system achieve horizontal scalability horizontal database scaling involves adding servers work single workload horizontally scalable systems come functionality compromises application requires functionality migration vertically scaled system may preferable databases run individual hardware ranging capacity smartwatches supercomputers multiple transparently reconfigurable server farms databases also scaled vertically run 64-bit microprocessors multi-core cpus large smp multiprocessors using multi-threaded implementations fully exploiting hardware configuration requires variety locking techniques ranging locking entire database entire tables disk blocks individual table rows appropriate lock granularity depends workload smaller object locked less chance database requests blocking hardware idles typically row locks necessary support high volume transaction processing applications cost processing overhead manage larger number locks systems ensure query sees time-consistent view database locking data query examining prevent update modifying stalling work alternatively databases use multi-version read consistency avoid blocking read locks still providing consistent query results another potential bottleneck occur systems many requests attempt access data time example oltp systems many transactions may attempt insert data table time shared nothing system given moment inserts processed single server manages partition shard table possibly overwhelming rest system little many tables use sequence number primary key increases new inserted row index key also experience contention overheat processes inserts one solution reverse digits primary key spreads inserts table key across multiple parts database basic technique split large tables multiple partitions based ranges values key field example data year could held separate disk drive separate computer partitioning removes limits sizes single table replicated databases maintain copies tables databases multiple computers scaling technique particularly convenient seldom never-updated data transaction history tax tables variety approaches used scale beyond limits single computer hp enterprise nonstop sql uses shared nothing architecture neither data memory shared across server boundaries coordinator routes database requests correct server architecture provides near-linear scalability widely supported x/open xa standard employs global transaction monitor coordinate distributed transactions among semi-autonomous xa-compliant transaction resources oracle rac uses different model achieve scalability based shared-everything architecture approach incorporates shared disk approach allows multiple computers access disk cluster network-attached storage nas storage area networks sans coupled local area networks fibre channel technology enable configurations approach includes shared logical cache data cached memory server made available servers without requiring read data disk page moved server server satisfy requests updates generally happen quickly popular page updated multiple transactions little delay approach claimed support clusters containing 100 servers researchers question inherent limitations relational database management systems gigaspaces example contends space-based architecture required achieve performance scalability base one makes case extreme scalability within mainstream relational database technology
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Databases
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comparison audio synthesis environments software audio synthesis environments typically consist audio programming language may graphical user environment design/run language although many environments comparable abilities produce high-quality audio differences specialties draw users particular platform article compares noteworthy audio synthesis environments enumerates basic issues associated use audio synthesis environments comprise wide varying range software hardware configurations even different versions environment differ dramatically broad variability certain aspects different systems directly compared moreover levels comparison either difficult objectively quantify depend purely personal preference commonly considered subjective attributes comparison include attributes vary strongly depending tasks used evaluation common comparisons include audio software often slightly different sound compared others different ways implement basic building blocks sinewaves pink noise fft result slightly different aural characteristics although people course prefer one system sound another perhaps best output determined using sophisticated audio analyzers combination listener ears idea would arrive would agree pure sound possible interface audio system often significant influence creative flow user possible stable/mature systems listed fully featured enough able achieve enormous range sonic/compositional objectives made easy made difficult difficult boil brief comparative statement one issue may interface metaphors used e.g boxes-and-wires documents flow graphs hardware mixing desks interfaces language environment software hardware user interfaces
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Programming language topics
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tvos tvos operating system developed apple inc. 4th generation later apple tv digital media player tvos announced september 9 2015 apple september 2015 event alongside 4th generation apple tv october 29 2015 4th generation apple tv pre-orders began shipments began following week tvos initially based ios whereas system software 2nd 3rd generation apple tv based stripped-down versions ios 4th generation apple tv support third-party software via app store rumored prior apple september 2015 event held september 9 2015 october 30 2015 4th generation apple tv became available shipped tvos 9.0 november 9 2015 tvos 9.0.1 released primarily update address minor issues tvos 9.1 released december 8 2015 along os x 10.11.2 ios 9.2 watchos 2.1 along updates apple also updated remote apps ios watchos allowing basic remote functionality 4th generation apple tv previously said app worked past versions apple tv november 25 2015 facebook debuted sdk tvos allowing applications log facebook share facebook use facebook analytics way ios applications december 2 2015 twitter debuted login authentication service tvos – digits – allowing users log apps services simple unique code available online march 11 2016 pangu team announced twitter would creating new jailbreak tool apple tv 4 running tvos 9.0–9.0.1 would released following week june 13 2016 wwdc 2016 apple svp internet services eddy cue announced next major version tvos tvos 10. tvos 10 brings new functionality siri search enhancements single sign cable subscriptions dark mode new remote application controlling apple tv tvos 9 shipped several new features fourth generation apple tv one major features ability move interface new touchpad remote using multi-touch gestures introduced new app store users download install new applications apps games made available developers develop applications apple tv tvos tvos 9 adds support siri lets users multitude things cross-application search movie/tv show rewind fast forward name actor/director current movie skip back 15 seconds tvos added support application switcher apple tv application customization options cinematic screensavers control tv using included siri remote built-in support hdmi-cec tvos addition tvos allows user control apple tv many different ways include using included siri remote pairing third-party universal remote pairing mfi gamepad control games using remote app ios pairing bluetooth keyboard aid typing experience user tvos designed based ios tvos inherited many accessibility features ios macos tvos includes apple technologies voiceover zoom siri help blind impaired vision voiceover apple screen reader available 30 languages enables visually impaired users know visual display input responses on-screen prompts voiceover uses gestures similar apple products flicks taps rotor like apple products iphone three click sequence home button activate accessibility features apple tv tvos user activate voiceover without installation process one needs triple-click menu button siri remote apple tv guide user complete initial setup task non-trivial visually impaired comparable products market another accessibility feature increase contrast screen acts reducing transparency background elements movie tv show pages menu tabs parts operating system high-contrast also turned cursor better delineate focused content user also opt turn reduce motion screen actions moving app icons home screen launching apps visually simpler benefit reduce strain eyes tvos enables users watch movies audio descriptions shown screen movies audio descriptions displayed ad audio description icon itunes store tvos itunes macintosh windows pc pairing bluetooth keyboard tvos apple tv enables another accessibility feature also incorporation voiceover typing voiceover mirrors audio voice character pressed keyboard repeated entered apple tv designed work apple wireless keyboard apple magic keyboard work however almost brand bluetooth keyboard apple tv without tvos supports closed captioning deaf hard hearing experience tv episodes feature-length movies compatible episodes movies denoted cc closed captioning sdh subtitles deaf hard-of-hearing icon itunes store either apple tv itunes viewer customize captions episodes movies styles fonts conducive hearing and/or visual impairment touch surface siri remote customizable tracking set fast adjusts thumb movements made amplify distance relation far thumb moved glass touchpad conversely tracking set slow larger movements thumb touchpad tune distance traversed screen help people disabilities apple remote app ios devices allows control apple tv iphone ipad ipod touch ios remote app increases accessibility apple tv enabling switch control switch control unique apple technology enables navigation sequentially onscreen items perform specific actions selecting tapping dragging typing using third party bluetooth-enabled switch hardware made handicaps tvos ships all-new development tools developers tvos adds support all-new sdk developers build apps tv including apis included ios 9 metal also adds tvos app store allows users browse download install wide variety applications addition developers use interface inside application rather able use apple interface since tvos based ios easy port existing ios apps apple tv xcode making refinements app better suit larger screen apple provides xcode free charge registered apple developers develop new apple tv necessary make parallax image application icon order apple provides parallax exporter previewer development tools apple tv information new updates apple tv 2nd generation onwards published apple knowledge base ios 4.1 first version ios available apple tv 2nd generation included apple tv software 4.0 october 23 2011 apple tv 2nd generation received ios 5.0 software photo stream airplay mirroring iphone 4s ipad 2 nhl wall street journal slideshow themes netflix subtitles contrary rumors code found ios 5 release bring support bluetooth apps apple tv 2nd generation september 24 2012 apple tv 2nd generation onwards received ios 6.0 software update shared photo streams itunes account switching better airplay functionality trailers searching among smaller improvements september 20 2013 apple tv second generation onwards received ios 7.0 software update itunes radio airplay icloud september 18 2014 third generation apple tv received ios 8.0 software update redesigned ui family sharing peer-to-peer airplay tvos 9 operating system 95 based ios 9 adaptations made television interface announced september 9 2015 alongside new ipad pro iphone 6s tim cook took stage introduced tvos saying time apple tv gain modern os support apps future tv available apple tv 4th generation released october 2015 adds native sdk develop apps app store distribute support siri universal search across multiple apps operating systems developed apple inc
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Operating systems
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plant dna c-values database plant dna c-values database comprehensive catalogue c-value nuclear dna content diploids genome size data land plants algae database created prof. michael d. bennett dr. ilia j. leitch royal botanic gardens kew uk database originally launched angiosperm dna c-values database april 1997 essentially online version collected data lists published prof. bennett colleagues since 1970s release 1.0 inclusive plant dna c-values database launched 2001 subsequent releases 2.0 january 2003 3.0 december 2004 addition angiosperm dataset made available 1997 database expanded taxonomically several times includes data pteridophytes since 2000 gymnosperms since 2001 bryophytes since 2001 algae since 2004 see 1 update history note subset databases cited individually may contain different sets authors recent release database release 7.1 went live april 2019 contains data 12,273 species plants comprising 10,770 angiosperms 421 gymnosperms 303 pteridophytes 246 ferns fern allies 57 lycophytes 334 bryophytes 445 algae similar animal genome size database created 2001 dr. t. ryan gregory university guelph canada
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Databases
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embrace extend extinguish embrace extend extinguish eee also known embrace extend exterminate phrase u.s. department justice found used internally microsoft describe strategy entering product categories involving widely used standards extending standards proprietary capabilities using differences strongly disadvantage competitors strategy phrase embrace extend first described outside microsoft 1996 article new york times titled tomorrow world wide web microsoft pc king wants reign internet writer john markoff said rather merely embrace extend internet company critics fear microsoft intends engulf phrase embrace extend also appears facetious motivational song anonymous microsoft employee interview steve ballmer new york times variation embrace extend extinguish first introduced united states v. microsoft antitrust trial vice president intel steven mcgeady used phrase explain microsoft vice president paul maritz statement 1995 meeting intel described microsoft strategy kill html extending strategy three phases microsoft claims original strategy anti-competitive rather exercise discretion implement features believes customers want older variant phrase embrace extend innovate j allard 1994 memo windows next killer application internet paul maritz executives microsoft memo starts background internet general proposes strategy turn windows next killer app internet browser wars companies besides microsoft introduced proprietary non–standards-compliant extensions example 1995 netscape implemented font tag among html extensions without seeking review standards body rise internet explorer two companies became locked dead heat out-implement non–standards-compliant features 2004 prevent repeat browser wars resulting morass conflicting standards browser vendors apple inc. safari mozilla foundation firefox google inc. google chrome opera software opera browser formed web hypertext application technology working group whatwg create open standards complement world wide web consortium microsoft refused join citing group lack patent policy reason
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Computer architecture
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praat praat talk free computer software package speech analysis phonetics designed continues developed paul boersma david weenink university amsterdam run wide range operating systems including various versions unix linux mac microsoft windows 2000 xp vista 7 8 10 program supports speech synthesis including articulatory synthesis
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Computational linguistics
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approximate computing approximate computing computation technique returns possibly inaccurate result rather guaranteed accurate result used applications approximate result sufficient purpose one example situation search engine exact answer may exist certain search query hence many answers may acceptable similarly occasional dropping frames video application go undetected due perceptual limitations humans approximate computing based observation many scenarios although performing exact computation requires large amount resources allowing bounded approximation provide disproportionate gains performance energy still achieving acceptable result accuracy example k -means clustering algorithm allowing 5 loss classification accuracy provide 50 times energy saving compared fully accurate classification key requirement approximate computing approximation introduced non-critical data since approximating critical data e.g. control operations lead disastrous consequences program crash erroneous output several strategies used performing approximate computing approximate computing used variety domains applications error-tolerant multimedia processing machine learning signal processing scientific computing etc google using approach tensor processing units tpu custom asic main issue approximate computing identification section application approximated case large scale applications common find people holding expertise approximate computing techniques enough expertise application domain vice versa order solve problem programming paradigms proposed common clear role separation application programmer application domain expert approaches allow spread common optimizations approximate computing techniques
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Computer architecture
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sqoop sqoop command-line interface application transferring data relational databases hadoop sqoop supports incremental loads single table free form sql query well saved jobs run multiple times import updates made database since last import imports also used populate tables hive hbase exports used put data hadoop relational database sqoop got name sql-to-hadoop sqoop became top-level apache project march 2012 informatica provides sqoop-based connector version 10.1 pentaho provides open-source sqoop based connector steps sqoop import sqoop export etl suite pentaho data integration since version 4.5 software microsoft uses sqoop-based connector help transfer data microsoft sql server databases hadoop couchbase inc. also provides couchbase server-hadoop connector means sqoop
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Distributed computing architecture
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envoy wordperfect computing envoy proprietary portable document file format marketed wordperfect corporation created competitor acrobat pro introduced tumbleweed communications corporation 1993 shipped wordperfect office march 1994 envoy file could created use special printer driver wordperfect resulting document could viewed separate viewer application envoy distributable viewer also worked web browser plugin unlike adobe pdf file format publicly documented envoy failed make headway pdf largely unused reported success reading envoy documents printing postscript envoy distributable viewer converting postscript file pdf postscript file also viewed directly using viewer ghostscript
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Programming language topics
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rootkit rootkit collection computer software typically malicious designed enable access computer area software otherwise allowed example unauthorized user often masks existence existence software term rootkit concatenation root traditional name privileged account unix-like operating systems word kit refers software components implement tool term rootkit negative connotations association malware rootkit installation automated attacker install obtained root administrator access obtaining access result direct attack system i.e exploiting known vulnerability privilege escalation password obtained cracking social engineering tactics like phishing installed becomes possible hide intrusion well maintain privileged access key root administrator access full control system means existing software modified including software might otherwise used detect circumvent rootkit detection difficult rootkit may able subvert software intended find detection methods include using alternative trusted operating system behavioral-based methods signature scanning difference scanning memory dump analysis removal complicated practically impossible especially cases rootkit resides kernel reinstallation operating system may available solution problem dealing firmware rootkits removal may require hardware replacement specialized equipment term rootkit root kit originally referred maliciously modified set administrative tools unix-like operating system granted root access intruder could replace standard administrative tools system rootkit intruder could obtain root access system whilst simultaneously concealing activities legitimate system administrator first-generation rootkits trivial detect using tools tripwire compromised access information lane davis steven dake wrote earliest known rootkit 1990 sun microsystems sunos unix operating system lecture gave upon receiving turing award 1983 ken thompson bell labs one creators unix theorized subverting c compiler unix distribution discussed exploit modified compiler would detect attempts compile unix codice_1 command generate altered code would accept user correct password additional backdoor password known attacker additionally compiler would detect attempts compile new version compiler would insert exploits new compiler review source code codice_1 command updated compiler would reveal malicious code exploit equivalent rootkit first documented computer virus target personal computer discovered 1986 used cloaking techniques hide brain virus intercepted attempts read boot sector redirected elsewhere disk copy original boot sector kept time dos-virus cloaking methods became sophisticated advanced techniques including hooking low-level disk int 13h bios interrupt calls hide unauthorized modifications files first malicious rootkit windows nt operating system appeared 1999 trojan called ntrootkit created greg hoglund followed hackerdefender 2003 first rootkit targeting mac os x appeared 2009 stuxnet worm first target programmable logic controllers plc 2005 sony bmg published cds copy protection digital rights management software called extended copy protection created software company first 4 internet software included music player silently installed rootkit limited user ability access cd software engineer mark russinovich created rootkit detection tool rootkitrevealer discovered rootkit one computers ensuing scandal raised public awareness rootkits cloak rootkit hid user file starting sys soon russinovich report malware appeared took advantage vulnerability affected systems one bbc analyst called public relations nightmare sony bmg released patches uninstall rootkit exposed users even serious vulnerability company eventually recalled cds united states class-action lawsuit brought sony bmg greek wiretapping case 2004-05 also referred greek watergate involved illegal telephone tapping 100 mobile phones vodafone greece network belonging mostly members greek government top-ranking civil servants taps began sometime near beginning august 2004 removed march 2005 without discovering identity perpetrators intruders installed rootkit targeting ericsson axe telephone exchange according ieee spectrum first time rootkit observed special-purpose system case ericsson telephone switch rootkit designed patch memory exchange running enable wiretapping disabling audit logs patch commands list active processes active data blocks modify data block checksum verification command backdoor allowed operator sysadmin status deactivate exchange transaction log alarms access commands related surveillance capability rootkit discovered intruders installed faulty update caused sms texts undelivered leading automated failure report generated ericsson engineers called investigate fault discovered hidden data blocks containing list phone numbers monitored along rootkit illicit monitoring software modern rootkits elevate access rather used make another software payload undetectable adding stealth capabilities rootkits classified malware payloads bundled malicious example payload might covertly steal user passwords credit card information computing resources conduct unauthorized activities small number rootkits may considered utility applications users example rootkit might cloak cd-rom-emulation driver allowing video game users defeat anti-piracy measures require insertion original installation media physical optical drive verify software legitimately purchased rootkits payloads many uses instances rootkits provide desired functionality may installed intentionally behalf computer user least five types rootkit ranging lowest level firmware highest privileges least privileged user-based variants operate ring 3 hybrid combinations may occur spanning example user mode kernel mode user-mode rootkits run ring 3 along applications user rather low-level system processes number possible installation vectors intercept modify standard behavior application programming interfaces apis inject dynamically linked library .dll file windows .dylib file mac os x processes thereby able execute inside target process spoof others sufficient privileges simply overwrite memory target application injection mechanisms include kernel-mode rootkits run highest operating system privileges ring 0 adding code replacing portions core operating system including kernel associated device drivers operating systems support kernel-mode device drivers execute privileges operating system many kernel-mode rootkits developed device drivers loadable modules loadable kernel modules linux device drivers microsoft windows class rootkit unrestricted security access difficult write complexity makes bugs common bugs code operating kernel level may seriously impact system stability leading discovery rootkit one first widely known kernel rootkits developed windows nt 4.0 released phrack magazine 1999 greg hoglund kernel rootkits especially difficult detect remove operate security level operating system thus able intercept subvert trusted operating system operations software antivirus software running compromised system equally vulnerable situation part system trusted rootkit modify data structures windows kernel using method known direct kernel object manipulation dkom method used hide processes kernel mode rootkit also hook system service descriptor table ssdt modify gates user mode kernel mode order cloak similarly linux operating system rootkit modify system call table subvert kernel functionality common rootkit creates hidden encrypted filesystem hide malware original copies files infected operating systems evolving counter threat kernel-mode rootkits example 64-bit editions microsoft windows implement mandatory signing kernel-level drivers order make difficult untrusted code execute highest privileges system kernel-mode rootkit variant called bootkit infect startup code like master boot record mbr volume boot record vbr boot sector way used attack full disk encryption systems example attack disk encryption evil maid attack attacker installs bootkit unattended computer envisioned scenario maid sneaking hotel room victims left hardware bootkit replaces legitimate boot loader one control typically malware loader persists transition protected mode kernel loaded thus able subvert kernel example stoned bootkit subverts system using compromised boot loader intercept encryption keys passwords recently alureon rootkit successfully subverted requirement 64-bit kernel-mode driver signing windows 7 modifying master boot record although malware sense something user n't want certain vista loader windows loader software work similar way injecting acpi slic system licensed internal code table ram-cached version bios boot order defeat windows vista windows 7 activation process vector attack rendered useless non-server versions windows 8 use unique machine-specific key system used one machine many antivirus companies provide free utilities programs remove bootkits rootkits created type ii hypervisors academia proofs concept exploiting hardware virtualization features intel vt amd-v type rootkit runs ring -1 hosts target operating system virtual machine thereby enabling rootkit intercept hardware calls made original operating system unlike normal hypervisors load operating system load operating system promoting virtual machine hypervisor rootkit make modifications kernel target subvert however mean detected guest operating system example timing differences may detectable cpu instructions subvirt laboratory rootkit developed jointly microsoft university michigan researchers academic example virtual machine–based rootkit vmbr blue pill software another 2009 researchers microsoft north carolina state university demonstrated hypervisor-layer anti-rootkit called hooksafe provides generic protection kernel-mode rootkits windows 10 introduced new feature called device guard takes advantage virtualization provide independent external protection operating system rootkit-type malware firmware rootkit uses device platform firmware create persistent malware image hardware router network card hard drive system bios rootkit hides firmware firmware usually inspected code integrity john heasman demonstrated viability firmware rootkits acpi firmware routines pci expansion card rom october 2008 criminals tampered european credit card-reading machines installed devices intercepted transmitted credit card details via mobile phone network march 2009 researchers alfredo ortega anibal sacco published details bios-level windows rootkit able survive disk replacement operating system re-installation months later learned laptops sold legitimate rootkit known absolute computrace absolute lojack laptops preinstalled many bios images anti-theft technology system researchers showed turned malicious purposes intel active management technology part intel vpro implements out-of-band management giving administrators remote administration remote management remote control pcs involvement host processor bios even system powered remote administration includes remote power-up power-down remote reset redirected boot console redirection pre-boot access bios settings programmable filtering inbound outbound network traffic agent presence checking out-of-band policy-based alerting access system information hardware asset information persistent event logs information stored dedicated memory hard drive accessible even os pc powered functions require deepest level rootkit second non-removable spy computer built around main computer sandy bridge future chipsets ability remotely kill restore lost stolen pc via 3g hardware rootkits built chipset help recover stolen computers remove data render useless also present privacy security concerns undetectable spying redirection management hackers might gain control rootkits employ variety techniques gain control system type rootkit influences choice attack vector common technique leverages security vulnerabilities achieve surreptitious privilege escalation another approach use trojan horse deceiving computer user trusting rootkit installation program benign—in case social engineering convinces user rootkit beneficial installation task made easier principle least privilege applied since rootkit explicitly request elevated administrator-level privileges classes rootkits installed someone physical access target system rootkits may also installed intentionally owner system somebody authorized owner e.g purpose employee monitoring rendering subversive techniques unnecessary malicious rootkit installations commercially driven pay-per-install ppi compensation method typical distribution installed rootkit takes active measures obscure presence within host system subversion evasion standard operating system security tools application programming interface apis used diagnosis scanning monitoring rootkits achieve modifying behavior core parts operating system loading code processes installation modification drivers kernel modules obfuscation techniques include concealing running processes system-monitoring mechanisms hiding system files configuration data uncommon rootkit disable event logging capacity operating system attempt hide evidence attack rootkits theory subvert operating system activities perfect rootkit thought similar perfect crime one nobody realizes taken place rootkits also take number measures ensure survival detection cleaning antivirus software addition commonly installing ring 0 kernel-mode complete access system include polymorphism changing signature hard detect stealth techniques regeneration disabling turning anti-malware software installing virtual machines may easier researchers discover analyze fundamental problem rootkit detection operating system subverted particularly kernel-level rootkit trusted find unauthorized modifications components actions requesting list running processes list files directory trusted behave expected words rootkit detectors work running infected systems effective rootkits defect camouflage run lower user-mode privileges detection software kernel computer viruses detection elimination rootkits ongoing struggle sides conflict detection take number different approaches including looking virus signatures e.g antivirus software integrity checking e.g digital signatures difference-based detection comparison expected vs. actual results behavioral detection e.g monitoring cpu usage network traffic kernel-mode rootkits detection considerably complex requiring careful scrutiny system call table look hooked functions malware may subverting system behavior well forensic scanning memory patterns indicate hidden processes unix rootkit detection offerings include zeppoo chkrootkit rkhunter ossec windows detection tools include microsoft sysinternals rootkitrevealer avast antivirus sophos anti-rootkit f-secure radix gmer windowsscope rootkit detectors prove effective ultimately contribute ineffectiveness malware authors adapt test code escape detection well-used tools detection examining storage suspect operating system operational miss rootkits recognised checking software rootkit active suspicious behavior suppressed conventional anti-malware software running rootkit operational may fail rootkit hides effectively best reliable method operating-system-level rootkit detection shut computer suspected infection check storage booting alternative trusted medium e.g rescue cd-rom usb flash drive technique effective rootkit actively hide presence running behavioral-based approach detecting rootkits attempts infer presence rootkit looking rootkit-like behavior example profiling system differences timing frequency api calls overall cpu utilization attributed rootkit method complex hampered high incidence false positives defective rootkits sometimes introduce obvious changes system alureon rootkit crashed windows systems security update exposed design flaw code logs packet analyzer firewall intrusion prevention system may present evidence rootkit behaviour networked environment antivirus products rarely catch viruses public tests depending used extent even though security software vendors incorporate rootkit detection products rootkit attempt hide antivirus scan stealth detector may notice rootkit attempts temporarily unload system signature detection fingerprinting still find combined approach forces attackers implement counterattack mechanisms retro routines attempt terminate antivirus programs signature-based detection methods effective well-published rootkits less specially crafted custom-root rootkits another method detect rootkits compares trusted raw data tainted content returned api example binaries present disk compared copies within operating memory operating systems in-memory image identical on-disk image results returned file system windows registry apis checked raw structures underlying physical disks—however case former valid differences introduced operating system mechanisms like memory relocation shimming rootkit may detect presence difference-based scanner virtual machine latter commonly used perform forensic analysis adjust behaviour differences detected difference-based detection used russinovich rootkitrevealer tool find sony drm rootkit code signing uses public-key infrastructure check file modified since digitally signed publisher alternatively system owner administrator use cryptographic hash function compute fingerprint installation time help detect subsequent unauthorized changes on-disk code libraries however unsophisticated schemes check whether code modified since installation time subversion prior time detectable fingerprint must re-established time changes made system example installing security updates service pack hash function creates message digest relatively short code calculated bit file using algorithm creates large changes message digest even smaller changes original file recalculating comparing message digest installed files regular intervals trusted list message digests changes system detected monitored—as long original baseline created malware added more-sophisticated rootkits able subvert verification process presenting unmodified copy file inspection making code modifications memory reconfiguration registers later compared white list expected values code performs hash compare extend operations must also protected—in context notion immutable root-of-trust holds first code measure security properties system must trusted ensure rootkit bootkit compromise system fundamental level forcing complete dump virtual memory capture active rootkit kernel dump case kernel-mode rootkit allowing offline forensic analysis performed debugger resulting dump file without rootkit able take measures cloak technique highly specialized may require access non-public source code debugging symbols memory dumps initiated operating system always used detect hypervisor-based rootkit able intercept subvert lowest-level attempts read memory—a hardware device one implements non-maskable interrupt may required dump memory scenario virtual machines also make easier analyze memory compromised machine underlying hypervisor rootkits avoid infecting virtual machines reason manual removal rootkit often difficult typical computer user number security-software vendors offer tools automatically detect remove rootkits typically part antivirus suite microsoft monthly windows malicious software removal tool able detect remove classes rootkits also windows defender offline remove rootkits runs trusted environment operating system starts antivirus scanners bypass file system apis vulnerable manipulation rootkit instead access raw file system structures directly use information validate results system apis identify differences may caused rootkit experts believe reliable way remove re-install operating system trusted media antivirus malware removal tools running untrusted system may ineffective well-written kernel-mode rootkits booting alternative operating system trusted media allow infected system volume mounted potentially safely cleaned critical data copied off—or alternatively forensic examination performed lightweight operating systems windows pe windows recovery console windows recovery environment bartpe live distros used purpose allowing system cleaned even type nature rootkit known manual repair may impractical re-installing operating system applications safer simpler quicker like much malware used attackers many rootkit implementations shared easily available internet uncommon see compromised system sophisticated publicly available rootkit hides presence unsophisticated worms attack tools apparently written inexperienced programmers rootkits available internet originated exploits academic proofs concept demonstrate varying methods hiding things within computer system taking unauthorized control often fully optimized stealth rootkits sometimes leave unintended evidence presence even rootkits used attack often effective rootkits keylogging features gameguard installed part online commercial games system hardening represents one first layers defence rootkit prevent able install applying security patches implementing principle least privilege reducing attack surface installing antivirus software standard security best practices effective classes malware new secure boot specifications like unified extensible firmware interface designed address threat bootkits even vulnerable security features offer utilized server systems remote server attestation using technologies intel trusted execution technology txt provide way verifying servers remain known good state example microsoft bitlocker encryption data-at-rest verifies servers known good state bootup privatecore vcage software offering secures data-in-use memory avoid bootkits rootkits verifying servers known good state bootup privatecore implementation works concert intel txt locks server system interfaces avoid potential bootkits rootkits
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Computer security
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sparse binary polynomial hashing sparse binary polynomial hashing sbph generalization bayesian spam filtering match mutating phrases well single words sbph way generating large number features incoming text automatically using statistics determine weights features terms predictive values spam/nonspam evaluation
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Computer security
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c-ran c-ran cloud-ran sometimes referred centralized-ran architecture cellular networks first introduced china mobile research institute april 2010 beijing china 9 years disclosed patent applications filed u.s. companies simply speaking c-ran centralized cloud computing-based architecture radio access networks supports 2g 3g 4g future wireless communication standards name comes four c main characteristics c-ran system clean centralized processing collaborative radio real-time cloud radio access network traditional cellular radio access networks ran consist many stand-alone base stations bts bts covers small area whereas group bts provides coverage continuous area bts processes transmits signal mobile terminal forwards data payload mobile terminal core network via backhaul bts cooling back haul transportation backup battery monitoring system limited spectral resources network operators 'reuse frequency among different base stations cause interference neighbouring cells several limitations traditional cellular architecture first bts costly build operate moore law helps reduce size power electrical system supporting facilities bts improved quite well second bts added system improve capacity interference among bts severe bts closer using frequency third users mobile traffic bts fluctuates called 'tide effect result average utilization rate individual bts pretty low however processing resources shared bts therefore bts designed handle maximum traffic average traffic resulting waste processing resources power idle times 1g 2g cellular networks base stations all-in-one architecture analog digital power functions housed single cabinet large refrigerator usually base station cabinet placed dedicated room along necessary supporting facilitates power backup battery air conditioning environment surveillance backhaul transmission equipment rf signal generated base station rf unit propagates pairs rf cables antennas top base station tower mounting points all-in-one architecture mostly found macro cell deployments 3g distributed base station architecture introduced ericsson nokia huawei leading telecom equipment vendors architecture radio function unit also known remote radio head rrh separated digital function unit baseband unit bbu fiber digital baseband signals carried fiber using open base station architecture initiative obsai common public radio interface cpri standard rrh installed top tower close antenna reducing loss compared traditional base station rf signal travel long cable base station cabinet antenna top tower fiber link rrh bbu also allows flexibility network planning deployment placed hundreds meters kilometres away modern base stations use decoupled architecture c-ran may viewed architectural evolution distributed base station system takes advantage many technological advances wireless optical communications systems example uses latest cpri standard low cost coarse dense wavelength division multiplexing cwdm/ dwdm technology mmwave allow transmission baseband signal long distance thus achieving large scale centralised base station deployment applies recent data centre network technology allow low cost high reliability low latency high bandwidth interconnect network bbu pool utilises open platforms real-time virtualisation technology rooted cloud computing achieve dynamic shared resource allocation support multi-vendor multi-technology environments c-ran architecture following characteristics distinct cellular architectures kt telecom operator republic korea introduced cloud computing center ccc system 3g wcdma/hspa 4g lte/lte-a network 2011 2012 concept ccc basically c-ran sk telecom also deployed smart cloud access network scan advanced-scan 4g lte/lte-a network korea later 2012 2014 airvana commscope introduced onecell c-ran-based small cell system designed enterprises public spaces one major alternative solution addressing similar challenges ran small size all-in-one outdoor bts thanks achievements semiconductor industry functionality bts including rf baseband processing mac processing package level processing implemented volume 50 litres makes system small weatherproof reduces difficulty bts site choice construction eliminates air conditioning requirement thus reduces operational costs however bts still working readily make use collaboration algorithms reduce interference neighboring btss also relatively hard upgrade repair all-in-one bts units usually mounted near antenna processing units less-protected environments also implies higher failure rate compared c-ran rru deployed outdoors advantage cloud ran lies ability implement lte-advanced features coordinated multipoint comp low latency multiple radio heads however economic benefit improvements comp negated higher backhaul costs operators main competition small cell c-ran occurs two deployment scenarios outdoor hotspot coverage indoor coverage one promising evolution paths future cellular network architecture c-ran attracted high academic research interest meanwhile native support cooperative radio capability built c-ran architecture also enables many advanced algorithms hard implement cellular networks including cooperative multi-point transmission/receiving network coding etc october 2011 wireless world research forum 27 hosted germany china mobile invited give c-ran presentation august 2012 ieee c-ran 2012 workshop hosted kunming china crc press published book green communications theoretical fundamentals algorithms applications 11th chapter c-ran green ran framework december 2012 ieee globalcom 2012 conference international workshop cloud based-stations large-scale cooperative communications hosted california usa european committee frame project 7 sponsors currently addressing many problems related cellular network architecture evolution many projects taken c-ran one future cellular network architectures like mobile cloud network project
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Distributed computing architecture
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volatile computer programming computer programming particularly c c++ c java programming languages volatile keyword indicates value may change different accesses even appear modified keyword prevents optimizing compiler optimizing away subsequent reads writes thus incorrectly reusing stale value omitting writes volatile values primarily arise hardware access memory-mapped i/o reading writing memory used communicate peripheral devices threading different thread may modified value despite common keyword behavior codice_1 differs significantly programming languages easily misunderstood c c++ type qualifier like codice_2 property type furthermore c c++ work threading scenarios use discouraged java c property variable indicates object variable bound may mutate specifically intended threading programming language separate keyword codice_3 threading usage codice_1 keyword exists c consequently c++ codice_1 keyword intended operations codice_1 variables atomic establish proper happens-before relationship threading specified relevant standards c c++ posix win32 volatile variables threadsafe vast majority current implementations thus usage codice_1 keyword portable synchronization mechanism discouraged many c/c++ groups example code sets value stored codice_11 codice_12 starts poll value repeatedly changes codice_13 static int foo void bar void optimizing compiler notice code possibly change value stored codice_11 assume remain equal codice_12 times compiler therefore replace function body infinite loop similar void bar_optimized void however codice_11 might represent location changed elements computer system time hardware register device connected cpu code would never detect change without codice_1 keyword compiler assumes current program part system could change value far common situation prevent compiler optimizing code codice_1 keyword used static volatile int foo void bar void modification loop condition optimized away system detect change occurs generally memory barrier operations available platforms exposed c++11 preferred instead volatile allow compiler perform better optimization importantly guarantee correct behaviour multi-threaded scenarios neither c specification c11 c++ specification c++11 specifies multi-threaded memory model volatile may behave deterministically across oses/compilers/cpus following c programs accompanying assemblies demonstrate codice_1 keyword affects compiler output compiler case gcc observing assembly code clearly visible code generated codice_1 objects verbose making longer nature codice_1 objects fulfilled codice_1 keyword prevents compiler performing optimization code involving volatile objects thus ensuring volatile variable assignment read corresponding memory access without codice_1 keyword compiler knows variable need reread memory use writes memory location thread process according c++11 iso standard volatile keyword meant use hardware access use inter-thread communication inter-thread communication standard library provides codice_24 templates java programming language also codice_1 keyword used somewhat different purpose applied field java qualifier codice_1 provides following guarantees using codice_1 may faster lock work situations range situations volatile effective expanded java 5 particular double-checked locking works correctly c codice_1 ensures code accessing field subject thread-unsafe optimizations may performed compiler clr hardware following types marked volatile reference types single boolean byte sbyte int16 uint16 int32 uint32 char enumerated types underlying type byte sbyte int16 uint16 int32 uint32 excludes value structs well primitive types double int64 uint64 decimal basically codice_1 shorthand calling codice_30 codice_31 methods special effect methods disable optimizations usually performed c compiler jit compiler cpu methods work follows codice_35 part fortran 2003 standard although earlier version supported extension making variables codice_1 function also useful finding aliasing related bugs integer volatile defined volatile following two lines code identical write i**2 loads variable memory multiplies value times write i*i loads variable twice memory multiplies values always drilling memory volatile fortran compiler precluded reordering reads writes volatiles makes visible threads actions done thread vice versa use volatile reduces even prevent optimization
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Programming language topics
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hp-gl hp-gl short hewlett-packard graphics language often written hpgl printer control language created hewlett-packard hp hp-gl primary printer control language used hp plotters introduced plotter hp-8972 1977 became standard almost plotters hewlett-packard printers also usually support hp-gl/2 addition pcl language formed series two letter codes mnemonics followed optional parameters instance arc drawn page sending string codice_1 means arc absolute parameters place center arc absolute coordinates 100,100 page starting angle 50 degrees measured counter-clockwise fourth optional parameter used specifies far arc continues defaults 5 degrees first introduced hp-gl contained following commands formats typical hp-gl files start setup commands followed long string graphics commands file ascii text file format instance coordinate system based smallest units one hp plotters could support set 25 µm i.e 40 units per millimeter 1016 per inch coordinate space positive negative floating point numbers specifically ±2 original hp-gl language support definition line width parameter determined pens loaded plotter advent first inkjet plotters line width pens specified within hp-gl files set printer would know line width print pen cumbersome error-prone process hewlett-packard graphics language/2 aka hp-gl/2 definition line width introduced language allowed elimination step also among improvements binary file format defined allowed smaller files shorter file transfer times minimal resolution reduced.. hp-gl related agl graphics language extension basic programming language agl implemented hewlett-packard minicomputers simplify controlling plotter agl commands describe desired graphics plotting function computer relays several hp-gl instructions plotter
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Programming language topics
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semantic parsing semantic parsing task converting natural language utterance logical form machine-understandable representation meaning semantic parsing thus understood extracting precise meaning utterance applications semantic parsing include machine translation question answering code generation phrase first used 1970 yorick wilks basis machine translation programs working semantic representations shallow semantic parsing concerned identifying entities utterance labelling roles play shallow semantic parsing sometimes known slot-filling frame semantic parsing since theoretical basis comes frame semantics wherein word evokes frame related concepts roles slot-filling systems widely used virtual assistants conjunction intent classifiers seen mechanisms identifying frame evoked utterance popular architectures slot-filling largely variants encoder-decoder model wherein two recurrent neural networks rnns trained jointly encode utterance vector decode vector sequence slot labels type model used amazon alexa spoken language understanding system deep semantic parsing also known compositional semantic parsing concerned producing precise meaning representations utterances contain significant compositionality shallow semantic parsers parse utterances like show flights boston dallas classifying intent list flights filling slots source destination boston dallas respectively however shallow semantic parsing parse arbitrary compositional utterances like show flights boston anywhere flights juneau deep semantic parsing attempts parse utterances typically converting formal meaning representation language early semantic parsers used highly domain-specific meaning representation languages later systems using extensible languages like prolog lambda calculus lambda dependency-based compositional semantics λ-dcs sql python java alexa meaning representation language abstract meaning representation amr work used exotic meaning representations like query graphs semantic graphs vector representations modern deep semantic parsing models either based defining formal grammar chart parser utilizing rnns directly translate natural language meaning representation language examples systems built formal grammars cornell semantic parsing framework stanford university semantic parsing execution sempre word alignment-based semantic parser wasp datasets used training statistical semantic parsing models divided two main classes based application used question answering via knowledge base queries used code generation standard dataset question answering via semantic parsing air travel information system atis dataset contains questions commands upcoming flights well corresponding sql another benchmark dataset geoquery dataset contains questions geography u.s. paired corresponding prolog overnight dataset used test well semantic parsers adapt across multiple domains contains natural language queries 8 different domains paired corresponding λ-dcs expressions popular datasets code generation include two trading card datasets link text appears cards code precisely represents cards one constructed linking card texts java snippets linking hearthstone card texts python snippets ifttt dataset uses specialized domain-specific language short conditional commands django dataset pairs python snippets english japanese pseudocode describing robocup dataset pairs english rules representations domain-specific language understood virtual soccer-playing robots
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Computational linguistics
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distributed manufacturing distributed manufacturing also known distributed production cloud producing local manufacturing form decentralized manufacturing practiced enterprises using network geographically dispersed manufacturing facilities coordinated using information technology also refer local manufacture via historic cottage industry model manufacturing takes place homes consumers within maker movement diy culture small scale production consumers often using peer peer resources referred distributed manufacturing consumers download digital designs open design repository website like youmagine thingiverse produce product low costs distributed network 3d printing services 3d hubs home open-source 3-d printer reprap primary attribute distributed manufacturing ability create value geographically dispersed locations via manufacturing example shipping costs could minimized products built geographically close intended markets also products manufactured number small facilities distributed wide area customized details adapted individual regional tastes manufacturing components different physical locations managing supply chain bring together final assembly product also considered form distributed manufacturing digital networks combined additive manufacturing allow companies decentralized geographically independent distributed production cloud manufacturing call attention conjunction commons-based peer production distributed manufacturing techniques self-reinforced fantasy system eternal growth overcome development economies scope civil society play important role contributing raising whole productive structure higher plateau sustainable customised productivity true many issues problems threats rise due large democratization means production especially regarding physical ones instance recyclability advanced nanomaterials still questioned weapons manufacturing could become easier mention implications counterfeiting intellectual property might maintained contrast industrial paradigm whose competitive dynamics economies scale commons-based peer production distributed manufacturing could develop economies scope advantages scale rest cheap global transportation economies scope share infrastructure costs intangible tangible productive resources taking advantage capabilities fabrication tools following neil gershenfeld “ least developed parts world need advanced technologies ” commons-based peer production distributed manufacturing may offer necessary tools thinking globally act locally response certain problems needs well supporting individual personal manufacturing social economic benefits expected result development local production economies particular humanitarian development sector becoming increasingly interested distributed manufacturing overcome supply chain challenges last mile distribution
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Distributed computing architecture
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julius software julius speech recognition engine specifically high-performance two-pass large vocabulary continuous speech recognition lvcsr decoder software speech-related researchers developers perform almost real-time computing rtc decoding current personal computers pcs 60k word dictation task using word trigram 3-gram context-dependent hidden markov model hmm major search methods fully incorporated also modularized carefully independent model structures various hmm types supported shared-state triphones tied-mixture models number mixtures states phones standard formats adopted cope free modeling toolkit main platform linux unix workstations works windows julius free open-source software released revised bsd style software license julius developed part free software toolkit japanese lvcsr research since 1997 work continued continuous speech recognition consortium csrc japan 2000 2003 rev.3.4 grammar-based recognition parser named julian integrated julius julian modified version julius uses hand-designed type finite-state machine fsm termed deterministic finite automaton dfa grammar language model used build kind voice command system small vocabulary various spoken dialog system tasks run julius recognizer needs language model acoustic model language julius adopts acoustic models hidden markov model toolkit htk ascii format pronunciation dictionary htk-like format word 3-gram language models arpa standard format forward 2-gram reverse 3-gram trained speech corpus reversed word order although julius distributed japanese models voxforge project working create english acoustic models use julius speech recognition engine recently april 2018 thanks effort mozilla foundation 350 hours spoken english audio corpus made available new english envr-v5.4 open source speech model released alongside polish plpl-v7.1 models available sourceforge
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Computational linguistics
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sound blaster x-fi sound blaster x-fi lineup sound cards creative technology sound blaster series series launched august 2005 lineup pci sound cards served introduction x-fi audio processing chip models ranging xtrememusic lower end platinum fatal1ty fps elite pro top range top-end elite pro model aimed musicians bundled x-fi external i/o box offering phono preamp inputs turntables high-impedance input guitars inch mic input headphone output line-in full size midi i/o well optical rca coaxial digital inputs outputs remote control platinum fatal1ty fps models offer front-panel drive-bay control unit remote control base model supplied without accessories top model claimed 109 db signal-to-noise ratio elite pro model uses higher-end dac 116 db claimed bottom two models feature 2 mb onboard x-ram top models offer 64 mb x-ram designed use games store sound samples improved gaming performance launch reviews support creative claims higher performance however even top-end 64 mb equipped model falling slightly behind older audigy cards october 2006 saw minor rebranding x-fi xtrememusic edition fact highly capable gaming card offers hardware decoding eax support replaced xtremegamer model revised model featured half-width pcb non-gold-plated connectors optical instead digital digital i/o module jack lacked connector users wishing purchase separate x-fi i/o box functionality otherwise market segment occupied xtrememusic moved downwards introduction cheaper 'xtreme audio 'xtreme audio notebook products despite x-fi label products x-fi line using emu20k1 chip ca20k1 older chip similar audigy se sb live cards ca0106-wbtlf thus lacking hardware acceleration 3d sound eax sound effects gaming content creation features i/o extensibility x-fi models new product introduced x-fi 'xtremegamer fatal1ty pro identical function fatal1ty fps made affordable unbundling i/o panel remote control 2007 creative technology unveiled pci express x1 expresscard/34 versions sound blaster x-fi xtreme audio consumer electronics show creative yet release pcie versions emu-based x-fi cards adapting ca20k1 chip pcie proved troublesome company reporting design difficulties latency problems delays 2008 x-fi titanium series announced using revised ca20k2 chip featured integraded risc processor safeguarding pcie-induced latencies ddr sdram interface place sdram integrated high definition audio architecture uaa component products included fatal1ty cards 64 mb x-ram optional i/o drive bay regular titanium 16 mb x-ram 109 db snr spec former unlike pci cards cards use software-based dolby digital live 5.1 encoding 2010 titanium hd added lineup featuring new dac 122 db snr rca audio outputs dropping support windows xp addition pci pcie internal sound cards creative also released external usb-based solution named x-mod november 2006 x-mod listed category rest x-fi lineup stereo device marketed improve music playing laptop computers lower specifications internal offerings external products use x-fi name include usb-based sound blaster x-fi hd sound blaster x-fi surround 5.1 pro sound blaster x-fi go pro internal hardware components different various usages needs gaming surround audiophile standards audio processor x-fi powerful time release offering extremely robust sample rate conversion src engine addition enhanced internal sound channel routing options greater 3d audio enhancement capabilities significant portion audio processing unit devoted resampling engine src engine far capable previous creative sound card offerings limitation major thorn creative side digital audio sampled 44.1 khz standard doubt related cd-da sound cards often designed process audio 48 khz 44.1 khz audio must resampled 48 khz creative previous cards dsps operated 48 khz audio dsp able process affect poor resampling implementation introduces artifacts audio heard measured higher intermodulation distortion within higher frequencies generally 16 khz x-fi resampling engine produces near-lossless-quality result far exceeding known audio card dsp available time release functionality used simple audio playback several features card technology claims improve clarity digital music digital analysis supported x-fi models including xtreme audio x-mod sound blaster x-fi presents following features usually implemented aid x-fi dsp software xtreme audio model since release x-fi caused several unsolved problems sound glitches various motherboards creative labs states primary function restore portions sound lost compression compression meant digital file-size reduction achieved digital audio data compression technologies like example mp3 rather idea reverse effects dynamic range compression analog technique used production 1990s newer audio cds exception classical music recordings make sound louder volume level setting found subjectively louder cds get airplay sell better achieve loudness without introducing strong distortion points signal volume reaches maximum compressed means case reduced volume whole signal multiplied factor maximum volume reached music whole louder maximum volume points mostly transients pronounced since whole process done final audio cd recorded effect equally present uncompressed audio files created cd lossless compressed audio made cd well lossy compressed audio cd transients typically found percussive sounds plosive consonants voice recordings first milliseconds so-called attack phase non-percussive instrument sounds tend somewhat muffled dynamic range compression undo effect uses multiband compander compressor/expander dynamically adjusted compression/expansion main function detect transients increase relative volume level consequence enabling signal altered whether result improves upon input audio purely matter perception depend type audio played cmss-3d recreates realistic surround sound audio source puts right center action whether using multichannel speakers headphones cmss-3d dsp feature provides audio enhancement requires creative proprietary drivers supported linux os depending equipment used cmss-3d 3 variants enabling setting apply special filtering algorithms order improve localization sound sources located close listener enabling setting apply special filtering algorithms order improve localization sound sources located listener environmental audio extensions designed enabled game developers within game enhance simulated-reality user experiencing example ringing game-world swords sound differently depending whether protagonist currently game-world temple vault game-world open field also 8 built-in eax effects enabled user smart volume management compressor evens dynamic range given source quieter sounds louder loud sounds quiet best used circumstances noise disturbance might issue late night instance otherwise generally preferable disabled render sound less dynamic instance lessening impact loud parts movies also making music sound less lively function divides music ten frequency bands adjusted using sliders multiple volume adjustments different inputs outputs system master volume affects settings default recommended value 50 sources actually equates 0 db amplification none 100 value causes 16 db amplification many creative previous sound cards x-fi supports soundfonts additionally audio creation mode card allows use eax midi playback via use controllers setting controls dd sound encoder setting dolby digital bitstream dts sound instead although creative slow embrace 64-bit drivers x-fi lineup x86-64 architecture based operating systems supported microsoft windows 7 includes basic driver support many x-fi series cards many x-fi features however require software applications provided creative order utilize full capabilities hardware september 24 2007 creative labs released closed source unsupported beta driver providing linux 64-bit os support following sound blaster x-fi series sound cards open-source driver available oss v4 build 1013 datasheets provided creative enable alsa driver development november 6 2008 creative finally released driver gpl license supports x86 well x86-64 architectures listed support area may 15 2009 communications creative suse developer takashi iwai finally got mergeable version x-fi driver august 31 2009 driver snd-ctxfi included release alsa 1.0.21 support creative sound blaster x-fi titanium hd added january 25 2012 alsa v1.0.25 release driver support i/o front panel ir documentation part missing xtreme audio different chipset stayed unsupported longer time currently supported advanced linux alsa driver modules might require installation additional packages alternative repositories x-fi mb pure software solution windows system requirement thus provide linux support entry-level model x-fi series sound blaster x-fi xtreme audio actually emu20k1 chip re-branded audigy se using family chips ca0106-wbtlf even drivers thus x-fi–related processing performed software also lacks basic hardware acceleration like sb live 24-bit audigy se budget soundblaster models x-fi xtreme audio use drivers rest x-fi family lacks asio games recognize x-fi capable hardware device hardware profile resembles older live audigy cards x-fi mb software solution enables basic x-fi features computers integrated audio x-fi device requires degree driver support audio hardware manufacturer x-fi mb commonly bundled motherboards computer systems comparable x-fi xtremeaudio bundled asus asrock motherboards x-fi mb sold x-fi supreme fx actually standard analog devices integrated hd audio codec paired x-fi mb x-fi features implemented entirely software hardware vendors sell x-fi mb solution simply sound blaster x-fi integrated sound x-fi mb available different versions e.g x-fi mb x-fi mb2 x-fi mb3 x-fi mb5 current version available select laptops desktops x-fi mb5 non-oem version x-fi mb3 sold creative labs works compatible motherboard sound chips realtek x-fi mb3 provides effective software version full x-fi card also provided version alchemy works non-creative sound cards restore legacy eax effects
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Computer architecture
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gingermaster gingermaster malware affects android operating system version 2.3 first detected august 2011 gingermaster android malware contains root exploit packaged within infected app application launched android device acquires root privileges device accesses sensitive data gingermaster steals data
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Computer security
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cloud-based quantum computing cloud-based quantum computing invocation quantum emulators simulators processors cloud increasingly cloud services looked method providing access quantum processing quantum computers achieve massive computing power initiating quantum physics processing power users allowed access quantum-powered computers internet known quantum computing within cloud ibm connected small quantum computer cloud allows simple programs built executed cloud many people academic researchers professors schoolkids already built programs run many different quantum algorithms using program tools consumers hoped use fast computing model financial markets build advanced ai systems use methods allow people outside professional lab institution experience learn phenomena technology cloud-based quantum computing used several contexts
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Distributed computing architecture
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backup software backup backup utility made apple mac os x available apple mobileme formerly .mac collection internet services backup used connection either user online mobileme idisk macintosh cd-rw dvd-r drive make safe archival copies critical files folders release icloud backup longer available release macos sierra longer works initial versions backup regarded feature-sparse frequently unstable however november 5 2003 apple released backup 2.0 added new features offered greater reliability predecessors backup 2 allowed creation archive copies important data overall basic feature set backup software apple introduced backup 3 paris expo september 20 2005 along upgrades .mac version offered backup settings ability back mail databases 2006 worldwide developers conference apple announced development time machine new backup application included mac os x v10.5 leopard time machine complete backup solution thus ability completely replace backup general backup solution mac users mobileme released july 11 2008 .mac discontinued backup continued available mobileme users software re-branded mobileme backup version 3.2 release
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Computer security
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wipersoft wipersoft anti-spyware program developed wiper software designed help users protect computers threats adware browser hijackers worms potentially unwanted programs pups currently available microsoft windows wipersoft launched 2015 available free program home users users able use scan removal functions without buy subscription 2016 re-released new modern design improved detection removal functionalities user-friendly interface year wipersoft also became paid program wipersoft saw big increase downloads sales 2017 reportedly used 1 million users 120 different countries tested softpedia 2017 rated 100 clean wipersoft primarily anti-spyware program comes two versions free wipersoft offers users scan computers spyware paid wipersoft features include spyware detection removal help desk services custom fix according wiper software program detect remove threats like potentially unwanted programs adware browser hijackers questionable toolbars browser add-ons detected potential threats automatically deleted users option keeping installed program also undo changes made detected threats change homepage default search engine program currently available microsoft windows users popular browsers google chrome mozilla firefox internet explorer opera supported program also available 10 languages
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Operating systems
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algol 58 algol 58 originally known ial one family algol computer programming languages early compromise design soon superseded algol 60 according john backus zurich acm-gamm conference two principal motives proposing ial provide means communicating numerical methods procedures people b provide means realizing stated process variety machines ... algol 58 introduced fundamental notion compound statement restricted control flow tied identifier scope way algol 60 blocks bauer attributes name bottenbruch coined term algorithmic language algorithmische sprache 1957 least germany proposals universal language association computing machinery acm also german gesellschaft für angewandte mathematik und mechanik society applied mathematics mechanics gamm decided organize joint meeting combine meeting took place may 27 june 2 1958 eth zurich attended following people language originally proposed called ial international algebraic language according perlis rejected 'unspeakable pompous acronym algol suggested instead though officially adopted year later publication following meeting still used name ial end 1958 zmmd-group built working algol 58 compiler z22 computer zmmd abbreviation zürich rutishauser worked münchen workplace bauer samelson mainz location z22 computer darmstadt workplace bottenbruch algol 58 saw implementation effort ibm effort competition fortran soon abandoned also implemented dartmouth college lgp-30 implementation soon evolved algol 60 implementation burroughs 220 called balgol evolved along lines well retained much algol 58 original character algol 58 primary contribution later languages used basis jovial mad neliac algo also used 1959 publish algorithms cacm beginning trend using algol notation publication continued many years
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Programming language topics
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digital transaction management digital transaction management dtm category cloud services designed digitally manage document-based transactions dtm removes friction inherent transactions involve people documents data create faster easier convenient secure processes dtm goes beyond content document management include e-signatures authentication non-repudiation enabling co-browsing customer business document transfer certification secure archiving goes beyond records management variety meta-processes around managing electronic transactions documents associated dtm standards proposed managed xdtm standard association aragon research estimated ye 2016 70 large enterprises dtm initiative underway fully implemented
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Distributed computing architecture
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software appliance software appliance software application combined enough operating system jeos run optimally industry-standard hardware typically server virtual machine software distribution firmware implements computer appliance virtual appliances subset software appliances main distinction packaging format specificity target platform virtual appliance virtual machine image designed run specific virtualization platform software appliance often packaged generally applicable image format e.g. live cd supports installations physical machines multiple types virtual machines installing software appliance virtual machine packaging image creates virtual appliance software appliances several benefits traditional software applications installed top operating system software appliance packaged virtual machine format virtual appliance allowing run within virtual machine container virtual appliance could built using either standard virtual machine format open virtualization format ovf format specific particular virtual machine container example vmware virtualbox amazon ec2 software appliance packaged live cd image allowing run real hardware addition types virtual machines allows developers avoid complexities involved supporting multiple incompatible virtual machine image formats focus lowest common denominator instead i.e. iso images supported virtual machine platforms commercial software appliances typically sold subscription service pay-as-you-go alternative approach software service customers receive service maintenance application vendor eliminating requirement manage multiple maintenance streams licenses service contracts cases application vendor may install software appliance piece hardware prior delivery customer thereby creating computer appliance cases primary value customer remains simplicity purchase deployment maintenance
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Operating systems
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billix billix live usb live cd supports multiple linux distributions including several special purpose distributions billix designed toolkit unix linux system administrators configured supports several distributions also following programs included
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Operating systems
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active scripting active scripting formerly known activex scripting technology used windows implement component-based scripting support based ole automation part com allows installation additional scripting engines form com modules active scripting technologies first released 1996 release microsoft internet explorer 3.0 august 1996 internet information services 3.0 products december 1996 usual applications active scripting include active server pages asp server scripts internet explorer windows script host wsh scripts automating routine tasks including use login scripts registry manipulation like administrative uses include windows management instrumentation active directory service interfaces active scripting also used general-purpose scripting database programming text-processing rapid prototyping application macro/scripting programming applications use active scripting main automation method others macro facility components available use via api one may opt add language and/or tool available default like programming microsoft excel perl rexx rather visual basic applications vba transferring data terminal emulator word processor way spreadsheet dissimilar macro tools none many uses active scripting addition windows similar functionality unix shell scripts well incremental improvement upon batch files command.com windows nt style shell scripts cmd.exe way vbscript replacement qbasic last available supplementary disc windows 95 majority languages used active scripting mentioned glue languages perl commonly used third-party script engine interfaces active scripting engines public developer create applications programmable active scripting languages well engines additional languages active scripting engines available several languages popular include windows cscript.exe command line wscript.exe running gui main means implementation installed active script languages clicking icon running command line script run dialogue etc default run plain text file containing code windows script file .wsf xml file contain one script one language addition elements executed windows script host third-party shell take command version 10 configured direct interoperability script host installed engines wsh engine based take command language reportedly development software securecrt use wsh functionality allow automation means installed scripting engine script host related components engines able integrated called windows applications like component active scripting regarded complete longer active development microsoft however technology still supported microsoft sustaining engineering team responsible bug fixes security enhancements furthermore scripting engines continue shipped future releases microsoft windows iis originally .net framework scripting technology separate scripting ide called visual studio applications vsa interfaces technology also available via active scripting allowing even .net-unaware applications scripted using .net languages vsa also meant replace visual basic applications however entire technology deprecated version 2.0 .net framework leaving clear upgrade path applications desiring active scripting support although scripts created c vbscript visual basic .net .net languages compiled executed run-time via libraries installed part standard .net runtime microsoft also introduced windows powershell expose applications via powershell cmdlets powershell providers
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Programming language topics
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wap billing wap billing mechanism consumers buy content wireless application protocol wap sites charged directly mobile phone bill alternative payment mechanism debit credit cards premium sms billing using wap billing consumers buy mobile content without registering service entering username password user clicks link agrees make purchase download content wap billing particularly associated downloading mobile entertainment content like ringtones mobile games wallpapers commentators suggested could compete premium sms leading payment channel mobile content wap billing works wap-enabled mobile phones gprs 3g wireless connection customer initiates wap session content service provider browsing wap page example wap site hoster obtains visitor ’ msisdn without visitor register specific wap gateway service information provided integration operator msisdn lookup service consumers confirm purchase clicking ‘ confirm purchase ’ link mobile phone wap billing platform informs wap application completed purchase transaction consumers redirected content purchased purchases recorded billed directly via mobile phone bill using msisdn attempts made create single cross-operator wap billing platform support purchase products mobile network markets like ireland wap billing available across o2 vodafone mobile operators via msidsn forwarding wap billing available mobile aggregators operating irish market case case business model basis unlike uk market benefits cited wap billing include ability sell minors lack credit card bank account improved customer experience including ‘ single click ’ purchases transactions completed without consumers send receive text message remember shortcodes claimed wap billing also reduces possibility fraud paying mobile content another benefit cited wap billing assertion users experience ‘ browse buy ’ experience used via pc internet wap billing lacks transparency customer act signing contract handing money human reading understanding writing least typing something thus also indirectly proving legitimate customer reduced single touch even child pet occasionally touches screen may trigger purchase often customer n't notice 've actually paid something bought subscription look phone bill afterwards silently start billing single click inviting malicious apps malicious embedded ads misuse wap billing form clickjacking triggered hard stop cancel payment normally three entities involved claim money thus service indirectly paid phone bill makes complicated deny payment claim money back 2013 federal trade commission settled jesta digital llc concerning unauthorized wap billing charges
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Computer security
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rebel code rebel code linux open source revolution technology book glyn moody published 2001 describes evolution significance free software open source movements many interviews notable hackers review guardian stephen poole wrote open source movement might effect reducing price people willing pay products also highlighted inconsistency free cost open source price publishers asking book chris douce wrote book important addition genre writing undoubtedly become termed 'pop-computing also wrote book raised interesting questions regarding relationship technology culture lot early design decisions linux kernel determined microprocessors sean jewett wrote rebel code despite flaws must read using linux helps put perspective decisions made early sheds light revolution come
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Operating systems
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ibm basic programming support ibm basic programming support/360 bps originally called special support set standalone programs system/360 mainframes minimum 8 kib memory bps developed ibm general products division endicott new york package included assemblers iocs compilers sorts utilities governing control program bps components introduced series product announcements 1964 1965 bps came two versions — strictly card system tape based system contrary stated goals kept small supervisor permanently resident programming languages available assembler rpg fortran iv subset tape fortran required 16 kib memory also two versions bps assembler tape version enhanced capabilities bps also disk counterpart called bos also required 8 kib memory supported disks ibm 2311 group responsible bps/bos went develop dos/360 tos/360 supposed interim solution became evident os/360 would large run 16 kib systems
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Operating systems
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list xbox live games windows 10 list xbox live enabled games windows 10 currently planned released windows 10 operating systems windows store application first wave windows 10 xbox games announced xbox wire march 2015 xbox live enabled games windows 10 made available windows store order released windows 10 xbox live enabled game developer needs member id xbox xbox live enabled titles identifiable marketplace green banner running across top game page icon reads xbox live
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Operating systems
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dynamic data exchange computing dynamic data exchange dde technology interprocess communication used early versions microsoft windows os/2 dde allowed programs manipulate objects provided programs example cell embedded microsoft excel spreadsheet respond user actions affecting objects internally dde implemented terms windows message-passing architecture left vulnerable malformed third-party programs dde partially superseded object linking embedding ole currently maintained windows systems sake backwards compatibility dynamic data exchange first introduced 1987 release windows 2.0 method interprocess communication one program could communicate control another program somewhat like sun rpc remote procedure call time method communication operating system client applications windows messaging layer dde extended protocol allow peer-to-peer communication among client applications via message broadcasts dde runs via message broadcasts vulnerable window-management code pump messages problem considered design dde dde predates pre-emptive multitasking moreover code managing window handle respond dde broadcast initiator dde must distinguish expected unexpected responses dde interlocutors usually express information seek terms hierarchical string keys example cell microsoft excel known dde application name application could organize information groups known topic topic could serve individual pieces data item example user wanted pull value microsoft excel contained spreadsheet called book1.xls cell first row first column application would excel topic book1.xls item r1c1 internal changes cell due excel actions would signaled reverse calling application via additional message broadcasts common use dde custom-developed applications control off-the-shelf software example custom in-house application might use dde open microsoft excel spreadsheet fill data opening dde conversation excel sending dde commands feature mainly superseded component object model suite technologies microsoft used dde internally since release windows 95 example excel exposes extensive ole automation object model recommended method communicating excel technique however still use particularly distribution financial data dde also primary method interprocess communication internals sas programming language dde require operating system components conventional windows gui program also little-used alternative programs seeking minimize dependencies wonderware developed extension dde called netdde could used initiate maintain network connections needed dde conversations dde-aware applications running different computers network transparently exchange data dde conversation interaction client server applications netdde could used along dde dde management library ddeml applications codice_1 netdde library files microsoft licensed basic netbios frames protocol version product inclusion various versions windows windows workgroups windows xp addition wonderware also sold enhanced version netdde customers included support tcp/ip technology extensively used scada field basic windows applications using netdde clipbook viewer winchat microsoft hearts netdde still included windows server 2003 windows xp service pack 2 although disabled default removed entirely windows vista however prevent existing versions netdde installed functioning later versions windows
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Operating systems
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sdsf system display search facility sdsf component ibm mainframe operating system z/os interactive user interface allows users administrators view control various aspects mainframe operation system resources information displayed sdsf includes batch job output unix processes scheduling environments status external devices printers network lines sdsf primarily used access batch system log files dumps field-developed program offering sdsf known spool display search facility word spool changed system became program product late 1980s z/os release 9 sdsf supports rexx interface allowing batch programs use sdsf facilities support includes stem variables containing sdsf-originated information prior z/os release 10 sdsf supported use jes2 jes3 although isv products phoenix software international tone software available similar functionality jes3 beyond z/os release 10 sdsf fully supports jes3 including new commands jds ods display data/sets job output jes3 jobs release z/os v1r13 sdsf came packed interesting features like cursor sensitive sort point shoot sort extensive support oper logs rexx java programmed environments sdsf organized collection panels panel displays information specific aspect mainframe operations panels currently provided st panel sdsf supports following commands batch job commands translated jes2 jes3 command performs desired function
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Operating systems
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armitage computing armitage graphical cyber attack management tool metasploit project visualizes targets recommends exploits free open source network security tool notable contributions red team collaboration allowing shared sessions data communication single metasploit instance armitage written supported raphael mudge armitage gui front-end metasploit framework developed raphael mudge goal helping security professionals better understand hacking help realize power metasploit originally made cyber defense exercises since expanded user base penetration testers armitage scriptable red team collaboration tool built top metasploit framework armitage user may launch scans exploits get exploit recommendations use advanced features metasploit framework meterpreter
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Computer security
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metamath metamath formal language associated computer program proof checker archiving verifying studying mathematical proofs several databases proved theorems developed using metamath covering standard results logic set theory number theory algebra topology analysis among others july 2019 set proved theorems using metamath one largest bodies formalized mathematics containing particular proofs 71 100 theorems formalizing 100 theorems challenge making third hol light isabelle coq mizar proofpower lean nqthm acl2 nuprl least 17 proof verifiers databases use metamath format metamath language metalanguage suitable developing wide variety formal systems metamath language specific logic embedded instead simply regarded way prove inference rules asserted axioms proven later applied largest database proved theorems follows conventional zfc set theory classic logic databases exist others created metamath language design focused simplicity language employed state definitions axioms inference rules theorems composed handful keywords proofs checked using one simple algorithm based substitution variables optional provisos variables must remain distinct substitution made set symbols used constructing formulas declared using codice_1 codice_2 variable symbols statements example grammar formulas specified using combination codice_3 floating variable-type hypotheses codice_4 axiomatic assertion statements example axioms rules inference specified codice_4 statements along codice_6 codice_7 block scoping optional codice_8 essential hypotheses statements example using one construct codice_4 statements capture syntactic rules axiom schemas rules inference intended provide level flexibility similar higher order logical frameworks without dependency complex type system theorems derived rules inference written codice_10 statements example note inclusion proof codice_10 statement abbreviates following detailed proof essential form proof elides syntactic details leaving conventional presentation metamath proof steps use single substitution rule simple replacement variable expression proper substitution described works predicate calculus proper substitution metamath databases support derived construct instead one built metamath language substitution rule makes assumption logic system use requires substitutions variables correctly done detailed example algorithm works steps 1 2 theorem codice_12 metamath proof explorer set.mm depicted left let explain metamath uses substitution algorithm check step 2 logical consequence step 1 use theorem codice_13 step 2 states conclusion theorem codice_13 theorem codice_13 states theorem would never appear cryptic form textbook literate formulation banal two quantities equal one replace one operation check proof metamath attempts unify one way unifying metamath uses premise codice_13 premise states consequence previous computation metamath knows substituted premise becomes thus step 1 therefore generated turn step 1 unified codice_17 codice_17 definition number codice_19 states codice_20 unification simply matter constants straightforward problem variables substitute verification finished two steps proof codice_12 correct metamath unifies check syntactical rules respected fact type codice_22 thus metamath check also typed codice_22 metamath program original program created manipulate databases written using metamath language text command line interface written c. read metamath database memory verify proofs database modify database particular adding proofs write back storage prove command enables users enter proof along mechanisms search existing proofs metamath program convert statements html tex notation example output modus ponens axiom set.mm many programs process metamath databases particular least 17 proof verifiers databases use metamath format metamath website hosts several databases store theorems derived various axiomatic systems databases .mm files associated interface called explorer allows one navigate statements proofs interactively website user-friendly way databases use hilbert system formal deduction though requirement metamath proof explorer recorded set.mm main far largest database 23,000 proofs main part july 2019 based classical first-order logic zfc set theory addition tarski-grothendieck set theory needed example category theory database maintained twenty years first proofs set.mm dated august 1993 mainly work norman megill also proofs made contributors database contains developments among fields set theory ordinals cardinals recursion equivalents axiom choice continuum hypothesis ... construction real complex number systems order theory graph theory abstract algebra linear algebra general topology real complex analysis hilbert spaces number theory elementary geometry metamath proof explorer references many text books used conjunction metamath thus people interested studying mathematics use metamath connection books verify proved assertions match literature database develops mathematics constructive point view starting axioms intuitionistic logic continuing axioms constructive set theory database develops mathematics quine new foundations set theory database starts higher-order logic derives equivalents axioms first-order logic zfc set theory metamath website hosts databases associated explorers nonetheless noteworthy database peano.mm written robert solovay formalizes peano arithmetic database nat.mm formalizes natural deduction database miu.mm formalizes mu puzzle based formal system miu presented gödel escher bach metamath website also hosts older databases maintained anymore hilbert space explorer presents theorems pertaining hilbert space theory merged metamath proof explorer quantum logic explorer develops quantum logic starting theory orthomodular lattices metamath generic concept proof namely tree formulas connected inference rules specific logic embedded software metamath used species logic different hilbert-style logics sequents-based logics even lambda calculus however metamath provides direct support natural deduction systems noted earlier database nat.mm formalizes natural deduction metamath proof explorer database set.mm instead use set conventions allow use natural deduction approaches within hilbert-style logic using design ideas implemented metamath raph levien implemented small proof checker mmverify.py 500 lines python code ghilbert similar though elaborate language based mmverify.py levien would like implement system several people could collaborate work emphasizing modularity connection small theories using levien seminal works many implementations metamath design principles implemented broad variety languages juha arpiainen implemented proof checker common lisp called bourbaki marnix klooster coded proof checker haskell called hmm although use overall metamath approach formal system checker coding also implement new concepts mel o'cat designed system called mmj2 provides graphic user interface proof entry initial aim mel o'cat allow user enter proofs simply typing formulas letting mmj2 find appropriate inference rules connect metamath contrary may enter theorems names may enter formulas directly mmj2 also possibility enter proof forward backward metamath allows enter proof backward moreover mmj2 real grammar parser unlike metamath technical difference brings comfort user particular metamath sometimes hesitates several formulas analyzes meaningless asks user choose mmj2 limitation longer exists also project william hale add graphical user interface metamath called mmide paul chapman turn working new proof browser highlighting allows see referenced theorem substitution made
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Programming language topics
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secure computing corporation secure computing corporation scc public company developed sold computer security appliances hosted services protect users data mcafee acquired company 2008 company also developed filtering systems used governments iran saudi arabia blocks citizens accessing information internet 1984 research group called secure computing technology center sctc formed honeywell minneapolis minnesota centerpiece sctc work security-evaluated operating systems nsa work included secure ada target sat logical coprocessing kernel lock designed meet stringent a1 level trusted computer systems evaluation criteria tcsec next several years secure computing morphed small defense contractor commercial product vendor largely investment community much less interested purchasing security goods defense contractors commercial product vendors especially vendors growing internet space secure computing became publicly traded company 1995 following pattern internet-related startups stock price tripled first day opened 16 share closed 48 price peaked around 64 next several weeks collapsed following year ranged roughly 3 20 afterward company purchased mcafee company headquarters moved san jose california 1998 though bulk workforce remained twin cities roseville employees completed move st. paul minnesota february 2006 several sites exist largely result mergers secure computing consisted several merged units one oldest enigma logic inc. started around 1982 bob bosen founder claims created first security token provide challenge-response authentication bosen published computer game trs-80 home computer 1979 called 80 space raiders used simple challenge response mechanism copy protection people used mechanism encouraged repackage remote authentication bosen started enigma logic filed patents 1982–83 patent issued united kingdom 1986 ultimately challenge portion challenge response eliminated produce one-time password token similar securid product enigma logic merged secure computing corporation 1996 secure computing acquired smartfilter product line purchasing webster network strategies producer webtrack product 1996 acquisition included domain name webster.com eventually sold publishers webster dictionary shortly acquiring webster/smartfilter product secure computing merged border network technologies canadian company selling borderware firewall border network technologies boasted excellent product highly developed set sales channels said sales channels major inducement merger although plan completely merge borderware product sidewinder offer single product existing users products never quite succeeded 1998 borderware business unit sold new company borderware technologies inc. formed one original borderware founders time mergers yielded highly distributed company offices minnesota florida california two three ontario proved unwieldy company scaled back offices minnesota california 2002 company took gauntlet firewall product network associates 2003 secure computing acquired n2h2 makers bess web filtering package consolidation bess smartfilter bess referred smartfilter bess edition company literature acquisition cyberguard announced august 2005 approved january 2006 year earlier cyberguard attempted acquire secure computing proposal rejected largest merger secure computing time resulted addition several product lines including three classes firewalls content protocol filtering systems enterprise-wide management system controlling products several offices also added including cyberguard main facility deerfield beach florida well webwasher development office paderborn germany snapgear development office brisbane australia 2006 company merged atlanta-based ciphertrust developer email security solutions merger announced july 2006 completed august 2006 july 30 2008 secure computing announced intention sell safeword authentication product line aladdin knowledge systems leaving company business focused web/mail security firewalls sale concluded later year september 22 2008 mcafee announced intention acquire secure computing acquisition completed long afterwards combined company formed world largest dedicated security company time trustedsource reputation system secure computing obtained part ciphertrust acquisition key technology company enabling product lines global intelligence capability based behavioral analysis traffic patterns company email web firewall devices hosted services well numerous oem partners trustedsource derived real-time reputation scores ips urls domains mail/web content based variety data mining/analysis techniques support vector machine random forest term-frequency inverse-document frequency tfidf classifiers company flagship web security product line secure web appliance formerly known webwasher provided anti-malware protection trustedsource reputation-enabled url filtering controls content caching ssl scanning capabilities june 2008 secure computing launched secure web protection service in-the-cloud hosted web security service provided similar set features secure web appliance without requiring on-premises equipment software company flagship email security product line secure mail appliance formerly known ironmail provided trustedsource reputation-enabled anti-spam data-leakage protection dlp encryption anti-malware capabilities company flagship firewall product formerly known sidewinder renamed mcafee firewall enterprise mcafee sold sidewinder forcepoint january 2016 years secure computing antecedent organizations offered following major lines firewall products sidewinder firewall incorporated technical features high-assurance lock system including type enforcement technology later applied selinux however interaction secure computing open source community spotty due company ownership patents related type enforcement sidewinder never really tried achieve a1 tcsec rating earn eal-4+ common criteria rating along sidewinder gauntlet one earliest application layer firewalls developed large customer base united states department defense gauntlet originally developed trusted information systems tis commercial version tis firewall toolkit early open source firewall package developed darpa contract opennet initiative studied filtering software used governments block access citizens found secure computing smartfilter program heavily used iranian saudi governments according secure computing use software iran without consent—u.s sanctions prohibit american companies dealings iran—and 2005 company said actively working stop illegal use response company jonathan zittrain co-director harvard law school berkman center internet society stated fact remains software use extended period time 've seen secure computing software turn iran 've seen saudi arabia well 2001 new york times reported secure computing one ten companies competing saudi government contract software block citizens access websites deemed offensive company already deal saudis due expire 2003 defense secure computing always stated control customers use product sold according opennet initiative 2007 report saudi government censorship extensively covers religious social content though sites relating opposition groups regional political human rights issues also targeted governments united arab emirates oman sudan tunisia also actively use smartfilter tunisian government goes far redirect blocked pages fake error 404 page hide fact blocking software used tunisian government generally recognized poor record comes right free expression
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Computer security
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cvent cvent inc. privately held software-as-a-service saas company specializes market-leading meetings events hospitality management technology company offers web-based software meeting site selection online event registration event management email marketing web surveys company owned private equity firm vista equity partners cvent founded september 1999 reggie aggarwal year received 17 million venture capital grew staff 125 employees following dot-com bubble burst september 11 attacks cvent faced near-bankruptcy forced cut 80 staff company became profitable 2003 2011 cvent growing 50 year received 136 million funding new enterprise associates july 2011 time largest investment u.s. software company since 2007 june 13 2012 cvent announced acquisition austin-based startup crowdtorch previously known seed labs 4.2 million seven days later announced acquisition portland-based application developer crowdcompass 10 million cvent filed s-1 u.s. securities exchange commission july 8 2013 proposing initial public offering 5.6 million shares went public new york stock exchange august 9 2013 initial price 21 company raised 117.6 million received market capitalization billion dollars ipo referenced regards use jobs act enabled company quickly offer ipo 2016 company acquired venture capital company vista equity partners usd 1.65 billion ashok trivedi co-founder mastech digital igate early investor company june 5 2018 cvent announced acquired kapow online booking platform venues experiences june 10 2019 cvent announced acquired mobile event technology provider doubledutch july 2000 cvent introduced first saas product web-based tool event planners manage invitations collect registration fees 2006 introduced product conducting online surveys followed introduction cvent supplier network two years later supplier network free online marketing place connects meeting planners venues services 2009 company began offering professional services app development tool crowdtorch launched 2009 cvent also produces destination guide free online 8,000-page travel guide designed meeting planners information 800 different destinations strategic meetings management helps users manage budgets
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Distributed computing architecture
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special folder microsoft windows special folder folder presented user interface abstract concept instead absolute folder path synonymous term shell folder sometimes used instead special folders make possible application ask operating system appropriate location certain kinds files found independently version user language windows used windows server 2003 earlier folder like start menu different name non-english versions windows example german versions windows xp startmenü however starting windows vista versions windows use english named folders display different names windows explorer windows 10 user switch another display language names special folders change windows uses concept special folders present contents storage devices connected computer fairly consistent way frees user deal absolute file paths often change operating system versions even individual installations idea evolved time new special folders added every version windows post introduction windows 95 microsoft compatible windows software logo requires application make use special folders locations locate appropriate folders documents application settings stored special folder either reference physical file system directory reference virtual folder former case analogous environment variables — fact many environment variables set user session defined special folders set point virtual folders actually exist file system instead presented windows explorer tree folders user navigate known shell namespace windows xp systems root namespace desktop virtual folder contains documents computer network places network neighborhood windows 95 98 recycle bin virtual folders virtual folders like desktop accompanying special folder reference directory physical file system windows explorer displays combined contents virtual folder associated file system folder user seen figure 1 shows folder view windows xp explorer desktop virtual folder four standard virtual folders seen well additional folder folder desktop real folder located desktop directory user profile third-party programs add virtual folders windows explorer following tables list file system virtual folders available windows vista os version special folder introduced given well items like userprofile windir windows environment variables notes notes
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Computer file systems
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blis/cobol blis/cobol discontinued operating system unusually written cobol system gain reasonably wide acceptance optimised compile business applications written cobol blis available range data general nova data general eclipse 16-bit minicomputers marketed information processing inc. ipi regularly exhibited product national computer conference 1970s 80s priced us 830 10,000 depending number supported users features 1977 ipi boasted 100 operational installations system worldwide 1985 version ibm pc existed called pc-blis originally operating systems written assembly language particular processor family processors non-assembler operating systems comparatively slow easier revision repair one reasons c programming language low-level features resemble assembly language ways early intent use writing operating systems similar goals led ibm development pl/s high-level nature cobol created problems operating system development partially addressed blis since deliberately optimized cobol
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Operating systems
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sisne plus sisne plus ms-dos clone created itautec scopus tecnologia brazil prior end market reserve 1991 time forbid importation electronic equipment software general use widespread use ms-dos importations allowed sisne plus os discontinued
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Computer architecture
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terrorpods terrorpods 1987 shooting game simple business simulation psygnosis originally developed amiga atari st later ported commodore 64 zx spectrum amstrad cpc msx casts player industrial spy science fiction future assigned halt evil empire production fearsome war machines called terrorpods win game player must manage colonies specialised industries produce terrorpod fighting enemy forces like traditional shooting game appearance terrorpods conceived rejected design psygnosis cover artist roger dean martian fighters jeff wayne musical version war worlds player views action terrorpods cockpit dsv defence strategy vehicle consumes fuel travels around game world world ten colonies player must defend trade minerals enemy forces comprise destructible terrorpods spoilers roaming world indestructible mothership hovers overhead periodically shoots player player prime objective set resource trading ten colonies building mineral resources build one-tenth terrorpod five minerals fuel detonite quanza zenite aluma former four used fuel weapons latter required build terrorpod parts colonies tend specialise exportation single mineral player buy cheap profit player must sell cheaply bought resources another colony contact colony trading player must dispatch trading drover vehicle drive dsv drover useful unlike dsv consume fuel travelling spoilers steal minerals colonies shot phaser cannon consumes little fuel terrorpods attack colonies repelled destroyed phaser destroy terrorpods player must use missiles require precious detonite work player taken aim terrorpod lines making crosshair shift around seconds player must realign successful hit colony destroyed terrorpod player repair mineral-consuming energy beam game ends player gathered parts build terrorpod terrorpods originally released amiga atari st included inside game box foldout poster drawn tim white depicting three terrorpods excavating minerals icy surface colian game later released commodore 64 zx spectrum amstrad cpc msx versions removed resource management aspects original turning game straight-up shooter terrorpods earned positive reviews atari st user called superb praising high fidelity graphics sound tense strategic gameplay terrorpods review lazy game reviews
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Computer architecture
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web information system web-based information displays many benefits multimedia technology using today fast broadband connection possible stream sophisticated content computer anywhere world advantage many people information received read wherever whenever convenient crucial factor busy executive significant amount interactive multimedia content delivered via internet web information system web-based information system information system uses internet web technologies deliver information services users information systems/applications software system whose main purpose publish maintain data using hypertext-based principles web information system usually consists one web applications specific functionality-oriented components together information components non-web components web browser typically used front-end whereas database back-end
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Web technology
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tarpit networking tarpit also known teergrube german word tarpit service computer system usually server purposely delays incoming connections technique developed defense computer worm idea network abuses spamming broad scanning less effective therefore less attractive take long concept analogous tar pit animals get bogged slowly sink surface like swamp tom liston developed original tarpitting program labrea protect entire network tarpit run single machine machine listens address resolution protocol requests go unanswered indicating unused addresses replies requests receives initial syn packet scanner sends syn/ack response open socket prepare connection fact forget connection sending syn/ack however remote site sends ack gets ignored believes 3-way-handshake complete starts send data never reaches destination connection time since system believes dealing live established connection conservative timing instead try retransmit back-off retransmit etc quite later versions labrea also added functionality reply incoming data using raw ip packets sockets resources tarpit server bogus packets request sending site slow keep connection established waste even time scanner one possible avenues considered battle bulk-spam one time mandate small fee every submitted mail introducing artificial cost negligible impact legitimate use long fee small enough automated mass-scale spam would instantly become unattractive tarpitting could seen similar technically much less complex approach cost spammer would measured terms time efficiency rather money authentication procedures increase response times users attempt invalid passwords smtp authentication exception however server-to-server smtp transfers spam injected require authentication various methods discussed implemented smtp tarpits systems plug mail transfer agent mta i.e mail server software sit front proxy one method increases transfer time mails seconds delaying initial greeting message greet delay idea matter legitimate mail takes little longer deliver due high volume make difference spammers downside mailing lists legitimate mass-mailings explicitly whitelisted suffer email systems sendmail 8.13+ implement stronger form greet delay form pauses connection first established listens traffic detects traffic prior greeting violation rfc 2821 closes connection since many spammers write smtp implementations specification reduce number incoming spam messages another method delay known spammers e.g using blacklist see spamming dnsbl openbsd integrated method core system since openbsd 3.3 special-purpose daemon spamd functionality firewall pf redirect known spammers tarpit ms exchange tarpit senders send invalid address exchange smtp connector connected authentication system subtle idea greylisting simple terms rejects first connection attempt previously-unseen ip address assumption spammers make one connection attempt attempts short period time send message whereas legitimate mail delivery systems keep retrying longer period retry eventually allowed without impediments finally elaborate method tries glue tarpits filtering software together filtering e-mail realtime transmitted adding delays communication response filter spam likeliness indicator example spam filter would make guess line every x bytes received likely message going spam likely mta delay transmission smtp consists requests mostly four-letter words mail replies minimally three-digit numbers last line reply number followed space preceding lines followed hyphen thus determining message attempted send spam mail server reply tarpit waits fifteen seconds lines long delays allowed smtp humans sometimes send mail manually test mail servers ties smtp sending process spammer computer limit amount spam send linux kernel patched allow tarpitting incoming connections instead usual dropping packets implemented iptables addition tarpit target packet inspection matching features applied tarpit targets applied targets server determine given mail message spam e.g addressed spam trap trusted users reports server may decide ip address responsible submitting message deserves tarpitting cross-checking available dnsbls help avoid including innocent forwarders tarpit database daemon exploiting linux libipq check remote address incoming smtp connections database spamcannibal gpl software designed around idea stockade similar project implemented using freebsd ipfirewall one advantage tarpitting ip level regular tcp connections handled mta stateful although mta n't use much cpu sleeps still uses amount memory required hold state connection opposite labrea-style tarpitting stateless thus gaining advantage reduced cost spammer box however noted making use botnets spammers externalize computer-resource costs known tarpitted connection may generate significant amount traffic towards receiver sender considers connection established tries send retransmit actual data practice given current average computer botnet size reasonable solution drop suspicious traffic completely without tarpitting way tcp syn segments retransmitted whole http https requests well ms exchange two successful commercial implementations tar pit idea first developed turntide philadelphia-based startup company acquired symantec 2004 28 million cash turntide anti spam router contains modified linux kernel allows play various tricks tcp traffic varying tcp window size grouping various email senders different traffic classes limiting bandwidth class amount abusive traffic reduced particularly abusive traffic coming single sources easily identified high traffic volume symantec acquisition canadian startup company called mailchannels released traffic control software uses slightly different approach achieve similar results traffic control semi-realtime smtp proxy unlike turntide appliance applies traffic shaping network layer traffic control applies traffic shaping individual senders application layer approach results somewhat effective handling spam traffic originating botnets allows software slow traffic individual spam zombies rather requiring zombie traffic aggregated class
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Computer security
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charles brenner mathematician charles hallam brenner american mathematician originator forensic mathematics father joel lee brenner professor mathematics mother frances hallam brenner city councilor briefly mayor palo alto california uncle charles brenner md psychiatrist brenner received b.s stanford university 1967 ph.d. university california los angeles ucla 1984 brenner participated implementation apl\360 apl\1130 implemented transpose rotate primitive functions recently brenner specializes use mathematics dna analysis principal areas interest achievement mathematics forensic dna kinship rare haplotype matching dna mixtures couple haplotype papers recently showed haplotypes must much rarer much rarer sample frequency reference population sample brenner ’ symbolic kinship program example assess identification evidence based dna profiles anonymous body arbitrary set presumed relatives widely used mass victim identification projects including identifying 1/3 identified world trade center bodies brenner played key role resolution larry hillblom inheritance case resulting four amerasian children receiving 50 million
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Programming language topics
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ipod touch 6th generation sixth-generation ipod touch stylized marketed ipod touch colloquially known ipod touch 6g ipod touch 6 ipod touch 2015 ipod 6 multipurpose handheld device designed marketed apple inc. touchscreen-based user interface successor ipod touch 5th generation becoming first major update ipod lineup two half years released online apple store july 15 2015 along minor upgrades ipod nano ipod shuffle ipod touch 6th generation officially discontinued apple may 28 2019 release successor ipod touch 7th generation support end 6th generation long discontinuation incompatible ios 13 sixth-generation ipod touch features ios apple mobile operating system user interface ios based concept direct manipulation using multi-touch gestures interface control elements consist sliders switches buttons interaction os includes gestures swipe tap pinch reverse pinch specific definitions within context ios operating system multi-touch interface internal accelerometers used applications respond shaking device one common result undo command rotating vertically one common result switching portrait landscape mode sixth-generation ipod touch ships ios 8.4 released june 30 2015 along apple music play music movies television shows audiobooks podcasts sort media library songs artists albums videos playlists genres composers podcasts audiobooks compilations scrolling achieved swiping finger across screen alternatively headset controls used pause play skip repeat tracks however earpods come sixth-generation ipod touch include remote microphone voice control feature also used identify track play songs playlist specific artist create genius playlist sixth-generation ipod touch supports ios 9 released september 2015 ios 10 released september 2016 ios 11 released september 2017 ios 12 released september 2018 sixth-generation ipod touch support ios 12 made first ipod touch model support five major versions ios far ios 8 ios 12 sixth-generation ipod touch supported latest version apple mobile operating system ios 13 sixth-generation ipod touch features apple a8 apple m8 motion co-processor chipset 64-bit architecture chip ipad mini 4 apple tv 4th gen iphone 6 homepod slightly underclocked 1.1 ghz iphone 6 6 plus clocked 1.4 ghz ipad mini 4 clocked 1.5 ghz due small battery 1gb lpddr3 ram twice amount previous generation ipod touch apple metal graphics technology also compatible ipod touch 6th generation ipod touch features 8mp rear isight camera video record 1080p 30fps 120fps slow-motion mode records 720p camera also supports burst mode led flash unlike 5th-generation version rear camera 6th-generation ipod touch lacks sapphire crystal lens front camera unchanged previous generation 1.2mp sensor record video 720p first ipod touch available 128 gb storage partially filling void left behind ipod classic offered 160 gb storage time discontinued exterior design sixth-generation ipod touch largely identical predecessor exception ipod touch loop button removed available silver gold space gray pink blue product red version available apple stores apple online store although color shade slightly different previous generation sixth-generation ipod touch comes lightning charging cable model also comes earpods without remote mic ipod touch compatible apple airpods wireless headphones announced september 7th 2016 apple special event along iphone 7 released late december 2016 also compatible earpods lightning connector came time iphone 7 remote functions active nate ralph cnet praised device camera quality noted ipod touch exceptional performance criticized middling battery life small display stated considered largely redundant due smartphones tablets sascha segan pcmag also noted poor battery life stated ipod touch still best option anyone would prefer handheld media player n't require intimate relationship cellular carrier
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Operating systems
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graphics layout engine graphics layout engine gle graphics scripting language designed creating publication quality graphs plots diagrams figures slides gle supports various graph types function plots histograms bar graphs scatter plots contour lines color maps surface plots simple flexible set graphing commands complex output created relying gle scripting language full featured subroutines variables logic control gle relies latex text output supports mathematical formula graphs figures gle output formats include eps ps pdf jpeg png gle software dates back early 90 still active development currently gle development hosted sourceforge gle available major operating systems including microsoft windows mac os x unix included gnu/linux distributions debian fedora suse gle licensed bsd license qgle gle user interface licensed gpl license
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Programming language topics
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document-oriented database document-oriented database document store computer program designed storing retrieving managing document-oriented information also known semi-structured data document-oriented databases one main categories nosql databases popularity term document-oriented database grown use term nosql xml databases subclass document-oriented databases optimized work xml documents graph databases similar add another layer relationship allows link documents rapid traversal document-oriented databases inherently subclass key-value store another nosql database concept difference lies way data processed key-value store data considered inherently opaque database whereas document-oriented system relies internal structure document order extract metadata database engine uses optimization although difference often moot due tools systems conceptually document-store designed offer richer experience modern programming techniques document databases contrast strongly traditional relational database rdb relational databases generally store data separate tables defined programmer single object may spread across several tables document databases store information given object single instance database every stored object different every eliminates need object-relational mapping loading data database central concept document-oriented database notion document document-oriented database implementation differs details definition general assume documents encapsulate encode data information standard format encoding encodings use include xml yaml json bson well binary forms like pdf microsoft office documents ms word excel documents document store roughly equivalent programming concept object required adhere standard schema sections slots parts keys generally programs using objects many different types objects objects often many optional fields every object even class look different document stores similar allow different types documents single store allow fields within optional often allow encoded using different encoding systems example following document encoded json second document might encoded xml two documents share structural elements one another also unique elements structure text data inside document usually referred document content may referenced via retrieval editing methods see unlike relational database every record contains fields leaving unused fields empty empty 'fields either document record example approach allows new information added records without requiring every record database share structure document databases typically provide additional metadata associated stored along document content metadata may related facilities datastore provides organizing documents providing security implementation specific features core operations document-oriented database supports documents similar databases terminology perfectly standardized practitioners recognize crud documents addressed database via unique key represents document key simple identifier id typically string uri path key used retrieve document database typically database retains index key speed document retrieval cases key required create insert document database another defining characteristic document-oriented database beyond simple key-to-document lookup used retrieve document database offers api query language allows user retrieve documents based content metadata example may want query retrieves documents certain field set certain value set query apis query language features available well expected performance queries varies significantly one implementation another likewise specific set indexing options configuration available vary greatly implementation document store varies key-value store theory values key-value store opaque store essentially black boxes may offer search systems similar document store may less understanding organization content document stores use metadata document classify content allowing instance understand one series digits phone number another postal code allows search types data instance phone numbers containing 555 would ignore zip code 55555 document databases typically provide mechanism updating editing content metadata document either allowing replacement entire document individual structural pieces document document database implementations offer variety ways organizing documents including notions sometimes organizational notions vary much logical vs physical e.g disk memory representations document-oriented database specialized key-value store another nosql database category simple key-value store document content opaque document-oriented database provides apis query/update language exposes ability query update based internal structure document difference may moot users need richer query retrieval editing apis typically provided document databases modern key-value stores often include features working metadata blurring lines document stores search engines aka information retrieval systems like elasticsearch provide enough core operations documents fit definition document-oriented database relational database data first categorized number predefined types tables created hold individual entries records type tables define data within record fields meaning every record table overall form administrator also defines relationships tables selects certain fields believe commonly used searching defines indexes key concept relational design data may repeated normally placed table instances related column selected group together foreign key design known database normalization example address book application generally need store contact name optional image one phone numbers one mailing addresses one email addresses canonical relational database tables would created rows predefined fields bit data contact table might include first_name last_name image columns phone_number table might include country_code area_code phone_number type home work etc. phone_number table also contains foreign key column contact_id holds unique id number assigned contact created order recreate original contact database engine uses foreign keys look related items across group tables reconstruct original data contrast document-oriented database may internal structure maps directly onto concept table fields relationships generally n't exist predefined concepts instead data object placed single document stored database single entry address book example document would contain contact name image contact info single record entry accessed key allows database retrieve return document application additional work needed retrieve related data returned single object key difference document-oriented relational models data formats predefined document case cases sort document stored database documents change type form time one wishes add country_flag contact field added new documents inserted effect database existing documents already stored aid retrieval information database document-oriented systems generally allow administrator provide hints database look certain types information work similar fashion indexes relational case also offer ability add additional metadata outside content document instance tagging entries part address book allows programmer retrieve related types information like address book entries provides functionality similar table separates concept categories data physical implementation tables classic normalized relational model objects database represented separate rows data inherent structure beyond given retrieved leads problems trying translate programming objects associated database rows problem known object-relational impedance mismatch document stores closely cases directly map programming objects store often marketed using term nosql xml databases document-oriented databases
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Databases
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tss operating system ibm time sharing system tss/360 discontinued early time-sharing operating system designed exclusively special model system/360 line mainframes model 67 made available trial basis limited set customers 1967 never officially released supported product ibm tss pioneered number novel features later appeared popular systems mvs tss migrated system/370 303x systems despite many advances novel capabilities tss failed meet expectations eventually canceled tss/370 used basis port unix ibm mainframe tss/360 also inspired development tss-8 operating system tss/360 one first implementations tightly-coupled symmetric multiprocessing pair model 67 mainframes shared common physical memory space ran single copy kernel application code i/o operation launched one processor could end cause interrupt model 67 used standard 360 instruction called test set implement locks code critical sections also implemented virtual memory virtual machines using position-independent code tss/360 included early implementation table driven scheduler user-configured table whose columns parameters current priority working set size number timeslices used date kernel would refer table calculating new priority thread later appeared systems diverse honeywell cp-v ibm z/os standard operating system software time tss/360 customers general motors research laboratories given full access entire source operating system code development tools user-developed improvements patches frequently incorporated official source code tss/360 suffered performance reliability problems lack compatibility os/360 although issues eventually addressed ibm attempted develop tss aggressive schedule large staff programmers compete multics 1967 become evident tss/360 suffering kinds delays os/360 february 1968 time share 30 eighteen s/360-67 sites attempting run tss conference ibm announced via blue letter tss/360 decommitted great blow time-sharing community decision temporarily reversed tss/360 officially canceled 1971 however tss/360 continued quietly available time existing tss/360 customers interim measure tss/360 canceled ibm put primary efforts time sharing option tso time-sharing monitor os/360 several groups developed less ambitious successful time sharing systems s/360-67 notably cp-67 ibm cambridge scientific center early virtual machine monitor evolved vm/370 mts university michigan orvyl stanford university ibm also provided tss/370 prpq migration path existing tss/360 customers went multiple releases tss provides users command-line interface users interact command system command format consists codice_1 command name one eight characters without imbedded blanks operands optional depending command must separated command name least one blank multiple operands separated tab characters commas command lines continued typing hyphen end line continued typing continuation beginning next line multiple commands written line separating semicolons comments allowed command lines separated command semicolon included single quotes operands either positional keyword format keyword=value system commands divided seven categories tss provided early implementation position-independent code ability different processes run single copy executable possibly mapped different virtual addresses process system/360 programs typically contain modifiable data working storage address constants adcons fields containing addresses code data tss virtual addresses differ process running program tss language processors place adcons working storage separate section code called prototype control section psect program loaded dynamic loader makes copy psect relocates adcons reflect virtual addresses assigned within current process therefore user program unique copy psect called program executed general register 13 contains address psect current process address used references variable data addresses
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Operating systems
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racter racter artificial intelligence computer program generates english language prose random racter short raconteur written william chamberlain thomas etter existence program revealed 1983 book called policeman beard half constructed described composed entirely program according chamberlain introduction book program apparently ran cp/m machine written compiled basic z80 micro 64k ram version program allegedly wrote book released general public sophistication claimed program likely exaggerated could seen investigation template system text generation however 1984 mindscape inc. released interactive version racter developed inrac corporation dos amiga apple ii computers published racter similar chatterbot basic program released mindscape far less sophisticated anything could written fairly sophisticated prose policeman beard commercial version racter could likened computerized version mad libs game fill blanks advance plug text template produce surrealistic tale commercial program attempted parse text inputs identifying significant nouns verbs would regurgitate create conversations plugging input user phrase templates combined along modules conjugated english verbs contrast text policeman beard apart edited large amount output would product chamberlain specialized templates modules included commercial release program pc magazine described policeman beard scenes surprising frankness reflective concluded book whimsical wise sometimes fun computer gaming world described racter diversion another dimension might best seen paying price ticket try buy
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Computational linguistics
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lejos lejos firmware replacement lego mindstorms programmable bricks different variants software support original robotics invention system nxt ev3 includes java virtual machine allows lego mindstorms robots programmed java programming language includes also icommand.jar allows communicate via bluetooth original firmware mindstorm often used teaching java first-year computer science students lejos-based robot jitter flew around international space station december 2001 according official website name lejos conceived josé solórzano based acronym java operating system jos name another operating system rcx legos spanish word lejos lejos originally conceived tinyvm developed josé solórzano late 1999 started hobby open source project later forked known today lejos many contributors joined project provided important enhancements among brian bagnall jürgen stuber paul andrews later took project josé essentially retired august 20 2006 original lejos rcx discontinued 3.0 release soon afterwards icommand library control nxt bluetooth-enabled computer via lcp released library made use standard lego firmware library later superseded lejos nxj 0.8 january 2007 full port new lego mindstorms nxt released firmware replacement far faster x15 rcx version memory available menu system bluetooth support using bluecove library allows access many nxt features 2008 versions 0.5 0.6 0.7 released addition numerous improvements core classes eclipse plugin released along new version tutorial 2009 2 major releases 0.8 0.85 may 2011 0.9 released broadly speaking releases concentrated improvements navigation algorithms well support numerous 3rd party sensors eclipse plug-in 2013 development began port lego mindstorms ev3 brick 2014 0.5 0.6 alpha versions released 2015 beta versions 0.9 0.9.1 released since november 2014 lejos used slightly adapted version also open-source project open roberta lejos nxj provides support access robot i²c ports allows access standard sensors motors ultrasonic distance sensor touch sensor sound sensor light sensor companies mindsensors hitechnic extended basic set providing advanced sensors actuators multiplexers lejos nxj includes java apis products taking advantage object-oriented structure java developers lejos nxj able hide implementation details sensors actuators behind multiple interfaces allows robotics developer work high-level abstractions without worry details like hexadecimal addresses hardware components project includes implementations commonly used feedback controller pid controller kalman filter noise reduction algorithm lejos nxj also provides libraries support abstract functions navigation mapping behavior based robotics simple lejos program since first alpha release lejos nxj 2007 project consistently active following core development team relatively small group contributions accepted members community several interfaces third party sensors actuators contributed members outside core team platform used university robotics courses undergraduate research projects platform robotics research lejos nxj java project builds wealth functionality inherent java platform lejos nxj plugins two leading java ides eclipse netbeans robotics developers take advantage standard functionality ide code completion refactoring testing frameworks well point-and-click implementation nxj functions compiling linking uploading wealth java open source projects apache math likewise available nxj robotics developer
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Programming language topics
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trojan.win32.firehooker trojan.win32.firehooker trojan win32/firehooker definition kaspersky labs trojan downloader trojan dropper trojan spy created windows platform first known detection goes back september 2015 according avv trend micro malware requires main component successfully perform intended routine .dll-file name xul.dll file-size 5120 bytes file dropped dns blocking installer additional installers bundled dnsblockers xul.dll known mozilla firefox dll loads order come action following apis dll-file
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Computer security
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cyber security task force cyber security task force organized department public safety emergency preparedness canada jane billings assistant deputy minister current cyber security task force secretariat
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Computer security
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websocket websocket computer communications protocol providing full-duplex communication channels single tcp connection websocket protocol standardized ietf rfc 6455 2011 websocket api web idl standardized w3c websocket distinct http protocols located layer 7 osi model depend tcp layer 4 although different rfc 6455 states websocket designed work http ports 80 443 well support http proxies intermediaries thus making compatible http protocol achieve compatibility websocket handshake uses http upgrade header change http protocol websocket protocol websocket protocol enables interaction web browser client application web server lower overhead half-duplex alternatives http polling facilitating real-time data transfer server made possible providing standardized way server send content client without first requested client allowing messages passed back forth keeping connection open way two-way ongoing conversation take place client server communications done tcp port number 80 443 case tls-encrypted connections benefit environments block non-web internet connections using firewall similar two-way browser-server communications achieved non-standardized ways using stopgap technologies comet browsers support protocol including google chrome microsoft edge internet explorer firefox safari opera unlike http websocket provides full-duplex communication additionally websocket enables streams messages top tcp tcp alone deals streams bytes inherent concept message websocket port 80 full-duplex communication attainable using comet channels however comet implementation nontrivial due tcp handshake http header overhead inefficient small messages websocket protocol aims solve problems without compromising security assumptions web websocket protocol specification defines codice_1 websocket codice_2 websocket secure two new uniform resource identifier uri schemes used unencrypted encrypted connections respectively apart scheme name fragment codice_3 supported rest uri components defined use uri generic syntax using browser developer tools developers inspect websocket handshake well websocket frames websocket first referenced tcpconnection html5 specification placeholder tcp-based socket api june 2008 series discussions led michael carter resulted first version protocol known websocket name websocket coined ian hickson michael carter shortly thereafter collaboration whatwg irc chat room subsequently authored inclusion html5 specification ian hickson announced cometdaily blog michael carter december 2009 google chrome 4 first browser ship full support standard websocket enabled default development websocket protocol subsequently moved w3c whatwg group ietf february 2010 authored two revisions ian hickson protocol shipped enabled default multiple browsers rfc finalized ian fette december 2011 secure version websocket protocol implemented firefox 6 safari 6 google chrome 14 opera 12.10 internet explorer 10 detailed protocol test suite report lists conformance browsers specific protocol aspects older less secure version protocol implemented opera 11 safari 5 well mobile version safari ios 4.2 blackberry browser os7 implements websockets vulnerabilities disabled firefox 4 5 opera 11 establish websocket connection client sends websocket handshake request server returns websocket handshake response shown example client request like http line ends codice_4 must extra blank line end server response handshake starts http request/response allowing servers handle http connections well websocket connections port connection established communication switches bidirectional binary protocol conform http protocol addition codice_5 headers client sends codice_6 header containing base64-encoded random bytes server replies hash key codice_7 header intended prevent caching proxy re-sending previous websocket conversation provide authentication privacy integrity hashing function appends fixed string codice_8 guid value codice_6 header decoded base64 applies sha-1 hashing function encodes result using base64 connection established client server send websocket data text frames back forth full-duplex mode data minimally framed small header followed payload websocket transmissions described messages single message optionally split across several data frames allow sending messages initial data available complete length message unknown sends one data frame another end reached marked fin bit extensions protocol also used multiplexing several streams simultaneously instance avoid monopolizing use socket single large payload important security perspective validate origin header connection establishment process server side expected origins avoid cross-site websocket hijacking attacks might possible connection authenticated cookies http authentication better use tokens similar protection mechanisms authenticate websocket connection sensitive private data transferred websocket websocket protocol client implementations try detect user agent configured use proxy connecting destination host port uses http connect method set persistent tunnel websocket protocol unaware proxy servers firewalls features http-compatible handshake thus allowing http servers share default http https ports 80 443 websocket gateway server websocket protocol defines ws // wss // prefix indicate websocket websocket secure connection respectively schemes use http upgrade mechanism upgrade websocket protocol proxy servers transparent work fine websocket others prevent websocket working correctly causing connection fail cases additional proxy server configuration may required certain proxy servers may need upgraded support websocket unencrypted websocket traffic flows explicit transparent proxy server without websockets support connection likely fail encrypted websocket connection used use transport layer security tls websocket secure connection ensures http connect command issued browser configured use explicit proxy server sets tunnel provides low-level end-to-end tcp communication http proxy websocket secure client websocket server case transparent proxy servers browser unaware proxy server http connect sent however since wire traffic encrypted intermediate transparent proxy servers may simply allow encrypted traffic much better chance websocket connection succeed websocket secure used using encryption free resource cost often provides highest success rate since would travelling secure tunnel mid-2010 draft version hixie-76 broke compatibility reverse proxies gateways including eight bytes key data headers advertising data codice_10 header data forwarded intermediates could lead protocol failure recent drafts e.g. hybi-09 put key data codice_6 header solving problem
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Internet protocols
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os4000 os4000 proprietary operating system introduced gec computers limited 1977 successor gec dos range gec 4000 series 16-bit later 32-bit minicomputers os4000 developed late 1990s support-only mode since first operating systems gec 4000 series cos core operating system dos disk operating system basically single-user multi-tasking operating systems designed developing running process control type applications os4000 first released around 1977 reused many parts dos added multi-user access os4000 jcl command-line interpreter batch processing os4000 hierarchical filesystem although on-disk format similar non-hierarchical dos filesystem os4000 jcl based cambridge university phoenix command interpreter os4000 rel 3 arrived around 1980 included linked-os — support linked os4000 operating systems enable multi-node systems constructed main customer central computing service university college london euclid multi-node system consisting hub file server multiple rim multi-access compute server systems provided service 100 simultaneous users linked-os also used construct fail-over process control systems higher resilience os4000 rel 4 arrived around 1983 upped maximum number user modules 150 mainly university college london euclid system together enhanced batch processing system also included support gec 4090 processor introduced 32-bit addressing mode os4000 rel 5 introduced modified version os4000 filesystem called cfsx order allow easier use larger disks initial rel 5 supported cfsx filesystem support original cfs1 filesystem reintroduced well quite quickly os4000 rel 6 introduced support dual processor systems gec 4190d os4000 developed uk gec computers borehamwood offices elstree way gec computers dunstable development centre woodside estate dunstable architecture os4000 heavily based around architecture platform runs gec 4000 series minicomputers rather unusual platform includes feature called nucleus combination hardware firmware based kernel altered program control means many features typically found operating system kernels need included os4000 underlying platform performs functions instead operating system consequently provision running privileged mode code platform—all os4000 operating system code runs processes nucleus supports 256 processes schedules automatically using fixed priority scheme os4000 lives entirely within processes set system tables used configure nucleus access system tables granted processes need alter configuration nucleus e.g load new programs processes adjust nucleus scheduling time-shared processes etc system tables tell nucleus processes permitted communicate updated processes created destroyed e.g users login logout i/o performed directly processes system tables identify processes access peripherals handle peripheral interrupts example device driver disk controller process responsible issuing commands nucleus disk controller handling interrupts passed back disk controller via nucleus system tables explicitly state process access disk controller system tables grant device driver access peripherals event process stopping crashing nucleus looks owner process system tables informs owner process take decision let system continue running without process take system like unix panic take action reload and/or restart process functions filesystems store allocation terminal drivers timing services etc also exist separate processes nucleus implements segmented memory system processes access memory segments defined system tables maintained os4000 os4000 provides memory system handles store-resident memory virtual memory backed disk known overlay overlaying performed segment level os4000 also inherited grouped segments dos group segments overlaid retrieved single group feature little used os4000 process may use mixture resident overlayable segments although process performing real-time tasks would normally designed use resident segments os4000 supports fully mixed set process scheduling within system hard real-time processes soft real-time time-shared background given os4000 also includes full program development test/debug facilities made os4000 ideal developing deploying real-time applications process control high speed time data communications within one system os4000 uses proprietary filesystem filesystem extent based variable block size — different files created different blocksizes ranging 256 bytes 16,384 bytes 256-byte multiples filesystem hierarchical components limited 8 characters codice_1 period used component separator os4000 jcl limits characters file path components upper case letters numbers file path starts context pointer name refers position filesystem followed zero catalogues equivalent unix directories ending filename disk system contains separate independent filesystem volume name disk name top level catalogue master catalogue must one disk mounted volume name codice_2 contains specific files required os4000 larger systems usually additional disks containing user files data files etc although coexist codice_2 disk space permitting users given set initial context pointers point catalogue filesystem users see filesystem hierarchies initial context pointers systems usually configured unprivileged users see users files system files except system executables held codice_4 convention area called codice_5 available users enables transfer/sharing files files os4000 filesystem typed means filesystem hold several different types file understands contents structured common logical files contain record structure split sequential random files random files records length enable seeking record numbers finally text binary files distinguished mainly prevent applications expect textual data accidentally using binary file results set logical file types identified three letters e.g logical sequential text lst logical file types lst lsb lrt lrb converse logical files physical files accessed block time known physical random binary prb files file types pst psb prt also exist theory capabilities prb generally used additionally logical indexed sequential lis filetype isam file always appears sorted key field byte stream byt filetype added rel 6.5 better support os4000 nfs server filetype cat used hold catalogues —it actually lsb file modified filesystem addition files catalogues 3 types symbolic links references ref created point another file catalogue creator ref see initial context pointer either filesystem another filesystem disk pointers odp similar references created point file catalogue seen initial context pointers creating odp privileged operation available system manager support unix style symlinks arbitrary text stored catalogue added rel 6.5 better support os4000 nfs server symlinks created visible nfs clients os4000 also provides non-hierarchical temporary filesystem supports exactly types file permanent filesystems except cat ref odp symlinks file contents stored dedicated temporary filing disk regions file metadata stored memory logged user private temporary filing name space seen logged user even another logged user username user temporary files deleted user logs implicitly system rebooted temporary filenames start percent codice_6 ampersand codice_7 limited 8 characters following shows short multi-access login session case user codice_8 logged issued codice_9 command session left timeout inactivity user logs os4000 jcl command interpreter codice_10 loaded user codice_11 process started reads commands terminal number system commands built codice_10 case command n't built executable binary files loaded codice_13 process run text jcl files opened processed directly codice_10 user normally also gets codice_15 process privileged used load trusted debugging programs real-time process control accounts half os4000 systems deployed systems steel production accounts significant proportion earlier real-time process control systems upgraded dos os4000 x.25 packet switches account significant proportion systems although earlier gec x.25 packet switches ran special operating system called nos cut operating system halfway dos os4000 civil command control systems e.g fire service control systems interfacing emergency telephone operator fire stations prestel uk public videotex systems used many countries many private viewdata systems multi-user minicomputers used many education research establishments os4000 ported gec series 63 minicomputer known os6000 required addition software nucleus emulation feature gec series 63 hardware gec computers dropped os6000 source code given daresbury laboratory main user continued keep step os4000 releases lifetime two gec series 63 systems
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Operating systems
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openafs openafs open-source implementation andrew distributed file system afs afs originally developed carnegie mellon university developed commercial product transarc corporation subsequently acquired ibm linuxworld 15 august 2000 ibm announced plans release version commercial afs product ibm public license became openafs today openafs actively developed wide range operating system families including aix mac os x darwin hp-ux irix solaris linux microsoft windows freebsd netbsd openbsd openafs foundation established may 20 2013 non-profit organization dedicated fostering stability growth openafs governance project split board elders consider issues strategic direction gatekeepers control source repository although legal entity owns openafs source code copyright many files attributed ibm source covered ipl however several files tree covered university vanity licenses applicable licenses listed file source repository called openafs/doc/license contributors last five years made significant improvements implementation afs3 protocol without breaking interoperability ibm/transarc releases since announcement written several large development projects integrated 64-bit ms-windows support ms-windows 7 support apple-mac os x v10.4-v10.9 support demand attach fileserver many development projects various stages completion following several prominent examples existing user base includes small single server cells well large multinational deployments spanning academia private research laboratories government commercial entities small snapshot deployed afs cells found reviewing contents cellservdb file distributed openafs
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Computer file systems
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metadatabase metadatabase database model 1 metadata management 2 global query independent databases 3 distributed data processing word metadatabase addition dictionary originally metadata common term referring simply data data tags keywords markup headers however technology concept metadata extended also include data knowledge representation information models e.g. relations entities-relationships objects application logic e.g. production rules analytic models e.g. simulation optimization mathematical algorithms case analytic models also referred modelbase classes metadata integrated modeling ontology give rise stable set meta-relations tables metadata individual models interpreted metadata entered tables models inserted retrieved updated deleted manner ordinary data ordinary relational database users also formulate global queries requests processing local databases metadatabase using globally integrated metadata metadatabase structure implemented open technology relational databases metadatabase technology developed rensselaer polytechnic institute troy new york group faculty students see references end article starting late 1980s main contribution includes extension concept metadata metadata management original approach designing database metadata applications conceptual results continue motivate new research new applications level particular design openness scalability tied particular ontology proposed requires reverse-representation application models order save meta-relations theory ontology neutral proven industrial applications however needs development establish field open technology requirement reverse-representation common global information integration technology way facilitate metadatabase approach distribute core portion local site allow peer-to-peer translation fly
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Databases
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ibm system management facilities ibm system management facility smf component ibm z/os mainframe computers providing standardised method writing records activity file data set use z/os term smf provides full instrumentation baseline activities running ibm mainframe operating system including i/o network activity software usage error conditions processor utilization etc one prominent components z/os uses smf ibm resource measurement facility rmf rmf provides performance usage instrumentation resources processor memory disk cache workload virtual storage xcf coupling facility rmf technically priced extra cost feature z/os bmc sells competing alternative cmf smf forms basis many monitoring automation utilities smf record numbered type e.g smf 120 smf 89 installations great control much little smf data collect records written software ibm products generally record type 128 higher record types subtypes example type 70 subtype 1 records written rmf record cpu activity list common smf record types major record types especially created rmf continue evolve rapid pace release z/os brings new fields different processor families coupling facility levels also change data model smf record data two ways two ways declared use one used time order fallback alternative data periodically dumped sequential files example tape drives using ifasmfdp smf dump utility ifasmfdl using log streams ifasmfdp also used split existing smf sequential files copy files two dump programs produce output involve changes smf records elaboration chain changing jcl call new dump utility
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Operating systems
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windows subsystem linux windows subsystem linux wsl compatibility layer running linux binary executables elf format natively windows 10 windows server 2019 may 2019 wsl 2 announced introducing important changes real linux kernel subset hyper-v features since june 2019 wsl 2 available windows 10 customers windows insider program including home edition first release wsl provides linux-compatible kernel interface developed microsoft containing linux kernel code run gnu user space top ubuntu opensuse suse linux enterprise server debian kali linux user space might contain bash shell command language native gnu/linux command-line tools sed awk etc programming language interpreters ruby python etc even graphical applications using x11 server host side architecture redesigned wsl 2 linux kernel running lightweight virtual machine environment introduced anniversary update august 2 2016 ubuntu image available fall creators update released october 17 2017 moved installation process linux distributions windows store introduced suse images wsl available 64 bit versions windows 10 version 1607 also available windows server 2019 microsoft announced wsl 2 may 6th 2019 features completely new vm-based backend based subset hyper-v features lieu prior system call adaptation layer planned release windows insider program june 2019 microsoft first foray achieving unix-like compatibility windows began microsoft posix subsystem superseded windows services unix via mks/interix eventually deprecated release windows 8.1 technology behind windows subsystem linux originated unreleased project astoria enabled android applications run windows 10 mobile first made available windows 10 insider preview build 14316 whereas microsoft previous projects third-party cygwin focused creating unique unix-like environments based posix standard wsl aims native linux compatibility instead wrapping non-native functionality win32 system calls prior systems utilized wsl initial design wsl 1 leveraged nt kernel executive serve linux programs special isolated minimal processes known pico processes attached kernel mode pico providers dedicated system call exception handlers distinct vanilla nt process opting reutilize existing nt implementations wherever possible though wsl via initial design much faster arguably much popular brethren unix-on-windows projects windows kernel engineers found difficulty trying increase wsl performance syscall compatibility trying reshape existing nt kernel recognize operate correctly linux api microsoft ignite conference 2018 microsoft engineers gave high-level overview new lightweight hyper-v vm technology containerization virtualized kernel could make direct use nt primitives host 2019 microsoft announced completely redesigned wsl architecture wsl 2 using lightweight vm technology hosting actual customized linux kernel images claiming full syscall compatibility microsoft envisages wsl primarily tool developers – especially web developers work open source projects wsl uses fewer resources typical virtual machine prior wsl direct way run linux software windows environment also allowing users use windows apps linux tools set files lxss manager service service charge interacting subsystem drivers way bash.exe confused shells provided linux distributions launches linux processes well handling linux system calls binary locks execution linux processes invoked particular user go linux instance usually first invoked process init applications closed instance closed codice_1 command used manage distributions windows subsystem linux command-line list available distributions set default distribution uninstall distributions command also used run linux binaries windows command prompt windows powershell codice_1 replaces codice_3 deprecated windows 10 1803 later run codice_4 command wsl using powershell example using codice_5 command command prompt wsl 1 design featured hardware emulation virtualization unlike projects colinux makes direct use host file system parts hardware network web servers example accessed interfaces ip addresses configured host shares restrictions use ports require administrative permissions ports already occupied applications guarantees interoperability certain locations system folders configurations whose access/modification restricted even running root sudo shell instance elevated privileges must launched order get sudo give real root privileges allow access wsl 1 capable running linux software 32-bit binaries require specific linux kernel services implemented wsl due lack real linux kernel wsl 1 kernel modules device drivers ca n't run wsl 2 however makes use live virtualized linux kernel instances possible run graphical gui applications mozilla firefox installing x11 server within windows host environment vcxsrv xming although without caveats lack audio support hardware acceleration resulting poor graphics performance support opencl cuda also implemented currently although planned future releases microsoft stated wsl 1 oriented development applications desktop environment production servers recommending use virtual machines hyper-v kubernetes azure purposes benchmarks wsl 1 performance often near native linux ubuntu debian intel clear linux linux distributions i/o tests bottleneck wsl redesigned wsl 2 backend claimed microsoft offer twenty-fold increases speed certain operations compared wsl 1 version 2 introduces changes architecture microsoft opted virtualization highly optimized subset hyper-v features order run provided kernel underlying distributions promising performance equivalent wsl 1 backwards compatibility mind developers n't need change anything published distributions even version exists new wsl global configuration way 1 ini file named codice_6 located user folder distribution installation resides inside ext4-formatted filesystem inside virtual disk host file system transparently accessible 9p protocol users microsoft promised 20 times read/write performance wsl 1
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Operating systems
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8.3 filename 8.3 filename also called short filename sfn filename convention used old versions dos versions microsoft windows prior windows 95 windows nt 3.5 also used modern microsoft operating systems alternate filename long filename compatibility legacy programs filename convention limited fat file system similar 8.3 file naming schemes also existed earlier cp/m trs-80 atari data general digital equipment corporation minicomputer operating systems 8.3 filenames limited eight characters directory specifier followed optionally filename extension consisting period codice_1 three characters systems support 8.3 filenames excess characters ignored file name extension codice_1 present significance codice_3 codice_4 equivalent furthermore systems file directory names uppercase although systems use 8.3 standard usually case-insensitive hence codice_5 equivalent name codice_6 however non-8.3 operating systems almost modern operating systems accessing 8.3 file systems including dos-formatted diskettes also including modern memory cards networked file systems underlying system may alter filenames internally preserve case avoid truncating letters names example case vfat vfat variant fat extended directory format introduced windows 95 windows nt 3.5 allowed mixed-case unicode long filenames lfns addition classic 8.3 names using multiple 32-byte directory entry records long filenames way one recognised old 8.3 system software valid directory entry maintain backward-compatibility legacy applications dos windows 3.1 fat vfat filesystems 8.3 filename automatically generated every lfn file still renamed deleted opened although generated name e.g codice_7 may show little similarity original ntfs filesystems generation 8.3 filenames turned 8.3 filename obtained using kernel32.dll function getshortpathname although compulsory algorithm creating 8.3 name lfn windows uses following convention ntfs file system used windows nt family supports lfns natively 8.3 names still available legacy applications optionally disabled improve performance situations large numbers similarly named files exist folder iso 9660 file system mainly used compact discs similar limitations basic level 1 additional restriction directory names contain extensions characters notably hyphens allowed filenames level 2 allows filenames 31 characters compatible classic amigaos classic mac os filenames 2001 microsoft antitrust case names micros~1 micros~2 humorously used refer companies might exist proposed split microsoft legacy technology used wide range products devices standard interchanging information compact flash cards used cameras vfat lfn long filenames introduced windows 95/98/me retained compatibility vfat lfn used nt-based systems windows nt/2k/xp uses modified 8.3 shortname filename contains lowercase letters combination lowercase basename uppercase extension vice versa special characters fits within 8.3 limits vfat entry created windows nt later versions xp instead two bits byte 0x0c directory entry used indicate filename considered entirely partially lowercase specifically bit 4 means lowercase extension bit 3 lowercase basename allows combinations codice_33 codice_34 codice_35 operating systems support creates backward-compatibility filename mangling problem older windows versions 95 98 see all-uppercase filenames extension used therefore change capitalization file transported usb flash drive cause problems operating systems exhibit case-insensitive filename behavior dos windows current 2.6 versions linux recognize extension reading mount option shortname determines whether feature used writing directory table special type file represents directory file directory stored within represented 32-byte entry table entry records name extension attributes archive directory hidden read-only system volume date time creation address first cluster file/directory data finally size file/directory legal characters dos filenames include following excludes following ascii characters dos filenames oem character set code 0xe5 first byte see makes troubles extra-ascii characters used directory entries root directory region subdirectories following format sometimes may desirable convert long filename short filename example working command prompt simple rules followed attain correct 8.3 filename find sure sfn 8.3 names files directory use codice_49 shows short names one long names codice_50 shows short names original dir listing format windows nt-based operating systems command prompt codice_51 applets accept long filenames wildcard characters question mark asterisk '* long filenames spaces need escaped i.e enclosed single double quotes starting windows vista console commands powershell applets perform limited pattern matching allowing wildcards filename subdirectory file path silently substituting first matching directory entry example codice_52 change current directory codice_53
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Operating systems
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rich web application rich web application originally called rich internet application ria installable internet application web application many characteristics desktop application software concept closely related single-page application may allow user interactive features drag drop background menu wysiwyg editing etc html5 current standard delivering rich web applications supported major browsers adobe flash manipulates vector raster graphics provide animation text drawings still images supports bidirectional streaming audio video capture user input via mouse keyboard microphone camera flash contains object-oriented language called actionscript supports automation via javascript flash language jsfl flash content may displayed various computer systems devices using adobe flash player available free charge common web browsers mobile phones electronic devices using flash lite apache flex formerly adobe flex software development kit sdk development deployment cross-platform rias based adobe flash platform initially developed macromedia acquired adobe systems flex donated adobe apache software foundation 2011 java applets used create interactive visualizations present video three dimensional objects media java applets appropriate complex visualizations require significant programming effort high level language communications applet originating server javafx software platform creating delivering rias run across wide variety connected devices current release javafx 11 sept 2018 enables building applications desktop browser mobile phones comes 3d support tv set-top boxes gaming consoles blu-ray players platforms planned java fx runs plug-in java applet via webstart silverlight proposed microsoft another proprietary alternative technology widely accepted instance lacks support many mobile devices examples application video streaming events including 2008 summer olympics beijing 2010 winter olympics vancouver 2008 conventions major political parties united states silverlight also used netflix instant video streaming service silverlight longer active development supported microsoft edge microsoft recent browser rias could use xforms enhance functionality using xml xslt along xhtml css javascript also used generate richer client side ui components like data tables resorted locally client without going back server mozilla internet explorer browsers support terms rich client rich internet application introduced white paper march 2002 macromedia adobe though concept existed number years earlier names including remote scripting microsoft april 1999 x internet forrester research october 2000 rich web application rias present indexing challenges web search engines adobe flash content least partially indexable security improve application software example use sandboxes automatic updates extensions remain subject vulnerabilities access often much greater native web applications security purposes rias run client portions within special isolated area client desktop called sandbox sandbox limits visibility access file-system operating system client application server side connection approach allows client system handle local activities reformatting forth thereby lowering amount frequency client-server traffic especially versus client-server implementations built around so-called thin clients november 2011 number announcements demonstrated decline demand rich internet application architectures based plug-ins order favor html5 alternatives adobe announced flash would longer produced mobile tv refocusing efforts adobe air pundits questioned continued relevance even desktop described beginning end research motion rim announced would continue develop flash playbook decision questioned commentators rumors state microsoft abandon silverlight version 5 released combination announcements proclaiming end line browser plug-ins
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Distributed computing architecture
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attic backup software attic deduplicating backup software various unix-like operating systems attic development began 2010 accepted debian august 2013 attic available pip notably part debian ubuntu arch slackware attic offers efficient deduplicated compressed optionally encrypted authenticated backups backup includes metadata like owner/group permissions posix acls extended file attributes handles special files also like hardlinks symlinks devices files etc internally represents files archive stream metadata similar tar unlike tools git borg project created extensive documentation internal workings attic uses rolling hash implement global data deduplication compression defaults zlib encryption aes via openssl authenticated hmac 2015 attic forked borg support open faster paced development according developers many issues attic fixed fork backward compatibility original program lost non-reversible upgrade process exists borg 1.0.0 released 5 march 2016 borg 1.1.0 released 7 october 2017 2018 borg active development many contributors attic developed stable releases available various linux distributions debian ubuntu fedora opensuse others ports collection various bsd derivatives project provides pre-built binaries linux freebsd macos
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Computer security
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elinks elinks free text-based console web browser unix-like operating systems began late 2001 experimental fork petr baudiš links web browser hence e name since e come stand enhanced extended 1 september 2004 baudiš handed maintainership project danish developer jonas fonseca citing lack time interest desire spend time coding rather reviewing organising releases 17 march 2017 openbsd removed elinks ports tree citing concerns security issues lack responsiveness developers
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Internet protocols
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freenas freenas free open-source network-attached storage nas software based freebsd openzfs file system licensed terms bsd license runs commodity x86-64 hardware freenas supports windows macos unix clients various virtualization hosts xenserver vmware using smb afp nfs iscsi ssh rsync ftp/tftp protocols advanced freenas features include full-disk encryption plug-in architecture third-party software freenas supports openzfs filesystem provides data integrity checking prevent data corruption enable point time snapshotting replication several levels redundancy including striping mirroring striped mirrors raid 1+0 three levels raidz freenas managed comprehensive web interface supplemented minimal shell console handles essential administrative functions web interface supports storage pool configuration user management sharing configuration system maintenance embedded system appliance freenas boots usb flash device sata dom image configured using usb flash/cd-rom bootable installer freenas operating system fully independent storage disks allowing configuration database encryption keys backed restored fresh installation os separation also allows freenas system upgrades performed web interface freenas project started october 2005 olivier cochard-labbé based m0n0wall embedded firewall freebsd 6.0 volker theile joined project july 2006 became project lead april 2008 september 2009 development team concluded project release .7 due complete rewrite order accommodate modern features plug-in architecture volker theile decided project best reimplemented using debian linux shifted development efforts interim corenas project eventually openmediavault continues project lead cochard-labbé responded community objections debian version freenas resumed activity project oversaw transfer freenas user ixsystems developers daisuke aoyama michael zoon continued developing freenas 7 nas4free project meanwhile ixsystems rewrote freenas new architecture based freebsd 8.1 releasing freenas 8 beta november 2010 plug-in architecture arrived freenas 8.2 freenas versioning synchronized freebsd clarity freenas 8.3 introduced full-disk encryption freebsd 9.1-based freenas 9.1 brought updated plug-in architecture compatible trueos warden jail management framework freenas 9.1 also first version freenas use community-supported openzfs v5000 feature flags freenas 9.2 based freebsd 9.2 included performance improvements introduced rest api remote system administration freenas 9.3 based freebsd 9.3 introduced zfs-based boot device initial setup wizard high-performance in-kernel iscsi server freenas 9.10 based freebsd 10.3-rc3 brought end freenas/freebsd synchronized naming introduced graphite monitoring support experimental support bhyve hypervisor october 2015 ten years original freenas release freenas 10 alpha released providing preview would become freenas corral ga march 15 2017 freenas corral introduced new graphical user interface command-line interface underlying middleware container management system virtual machine management system freenas corral departs freenas providing nas functionality also hyper-converged functionality thanks integrated virtual machine support however april 12 2017 ixsystems announced freenas corral would instead relegated 'technology preview citing issues general instability lack feature parity 9.10 jails iscsi etc users experiencing lower performance expected departure project lead instead decision made revert existing 9.10 code bring corral features 9.10.3 may 2017 ix systems announced freenas 11 would imminently released based 9.10 included features update freebsd operating system virtual machine management updates jails new beta user interface along lines corral based angular js 8.0 reimplementation freenas moved project m0n0bsd/m0n0wall/php-based architecture one based freebsd nanobsd embedded build system python programming language django web application framework dōjō toolkit javascript library also used lighttpd web server replaced nginx freenas 8.2 terminated successor 9.10.2 known freenas corral retained nginx web server zfs-based boot device freenas replaces django/dōjō web application framework original one freenas 11 implemented new interface using angular js features plugins shown 11.0 branch
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Operating systems
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david j. farber david j. farber born april 17 1934 professor computer science noted major contributions programming languages computer networking currently distinguished professor co-director cyber civilization research center keio university japan farber graduated stevens institute technology 1956 began 11-year career bell laboratories helped design first electronic switching system ess-1 snobol programming languages subsequently held industry positions rand corporation scientific data systems followed academic positions university california irvine university delaware irvine research work focused creating world first operational distributed computer system member electrical engineering department university delaware helped conceive organize major american research networks csnet nsfnet national research education network nren helped create nsf/darpa-funded gigabit network test bed initiative served chairman gigabit test bed coordinating committee farber subsequently appointed alfred fitler moore professor telecommunication systems university pennsylvania also held appointments professor business public policy wharton school business faculty associate annenberg school communication served chief technologist us federal communications commission 2000–2001 leave university farber founding editor icannwatch serves board advisers context relevant liquid information company farber aaas fellow ieee fellow acm fellow recipient 1995 sigcomm award lifelong contributions computer communications served board directors electronic frontier foundation electronic privacy information center advisory board board trustees internet society member presidential advisory committee high performance computing communications information technology next generation internet runs large 25,000+ readership mailing list called interesting-people 2012 memory son established joseph m. farber prize stevens institute technology recognizes graduating senior majoring one disciplines college arts letters displays keen interest concern civil liberties importance preserving protecting human rights august 3 2013 farber inducted pioneers circle internet hall fame elected aaas fellow council american association advancement science 2018
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Programming language topics
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reference monitor operating systems architecture reference monitor concept defines set design requirements reference validation mechanism enforces access control policy subjects e.g. processes users ability perform operations e.g. read write objects e.g. files sockets system properties reference monitor captured acronym neat means example windows 3.x 9x operating systems built reference monitor whereas windows nt line also includes windows 2000 windows xp designed contain reference monitor although clear properties tamperproof etc ever independently verified level computer security intended provide claim reference validation mechanism satisfies reference monitor concept correctly enforce system access control policy must invoked mediate security-sensitive operations must tampered undergone complete analysis testing verify correctness abstract model reference monitor widely applied type system needs enforce access control considered express necessary sufficient properties system making security claim according ross anderson reference monitor concept introduced james anderson influential 1972 paper peter denning 2013 oral history stated james anderson credited concept paper scott graham presented 1972 conference systems evaluated b3 trusted computer system evaluation criteria tcsec must enforce reference monitor concept
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Operating systems
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phpsqliteadmin phpsqliteadmin name two independent web applications written php managing sqlite databases phpsqliteadmin web-based client leverages php scripting sqlite file-database system provide simple way users create databases create tables query data using non-industry-standard sqlite syntax
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Databases
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boopsi boopsi basic object oriented programming system intuition object-oriented programming system amigaos extends amigaos windowing environment intuition object-oriented subsystem allowing hierarchy object classes every class defines single gui widget interface event boopsi made easier developers create system widgets create standardized graphical user interfaces magic user interface reaction examples complete widget toolkits built boopsi toolkits become popular amiga software programmers generate maintain graphical user interfaces object-oriented design brings advantages straightforward coupling objects objects example programmer may link numerical input field sliding control user adjusts sliding control numerical value input field changes automatically boopsi officially introduced amigaos 2.0 extended later releases
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Operating systems
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king kong 2 yomigaeru densetsu game unofficially re-released english south korean company zemina 1987 킹콩ii king kong ii
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Computer architecture
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tanium tanium privately held endpoint security systems management company based emeryville california founded 2007 father son david hindawi orion hindawi co-founders management company bigfix orion named ceo february 2016 david serves executive chairman
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Computer security
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loongson loongson family general-purpose mips64 cpus developed institute computing technology ict chinese academy sciences cas china chief architect professor formerly called godson loongson result public–private partnership blx ic design corporation founded 2002 ict jiangsu zhongyi group based beijing blx focuses designing 64-bit loongson general-purpose embedded processors together developing software tools reference platforms stmicroelectronics fabricates markets loongson chips blx fabless current loongson instruction set mips64 internal microarchitecture independently developed ict early implementations family lacked four instructions patented mips technologies avoid legal issues 2007 deal reached mips technologies ict stmicroelectronics bought mips license loongson thus processor promoted mips-based mips-compatible instead mips-like june 2009 ict licensed mips32 mips64 architectures directly mips technologies august 2011 loongson technology corp. ltd. licensed mips32 mips64 architectures mips technologies inc. continued development mips-based loongson cpu cores first revision loongson architecture loongson1 godson-232 core pure 32-bit cpu running clock speed 266 mhz fabricated 0.18 micron cmos process 8 kb data cache 8 kb instruction cache 64-bit floating-point unit capable 200 double-precision mflops intended embedded applications point sale pos systems high performance 64-bit architecture needed loongson 2 adds 64-bit ability loongson architecture initially running 500 mhz later revisions godson 2e produced run 1 ghz godson 2f released market early 2008 ran 1.2 ghz 65 nm loongson 3 godson-3 able run clock speed near 1 ghz 4 cpu cores ~15 w first 8 cores later 40 w april 2010 loongson 3a released ddr2/3 dram support 2017 loongson released latest version 3a cpu 3a3000 one domestic cpu china loongson 3a3000 commercialized recently exhibition nanjing 2017 based loongson 3a3000 motherboard developers computer quietly debut 3a3000 loongson latest cpu model 2017 using loongisa instruction set designed quad-core 64-bit clocked 1.5 ghz power consumption 30w performance frequency 1.5ghz 3a3000 single-threaded performance significantly behind intel amd products 3a3000 one-third intel i5 4460 3.2g two versions loongson-3b godson-3b first featuring 32 nm 6-core processor second version 28 nm 8-core processor version clocked 1.2 ghz 1.5 ghz loongson-3b exceptional energy efficiency terms performance per watt executing 192 gflops using 40 watts cpu core 64 kb l1 cache 128 kb l2 cache cores share common 8 mb l3 cache helps reduce cache miss rate ict launched loongson-3b-based six-core desktop solution technical specifications desktop solution uses optimized version fedora 13 lot software ported available kingsoft wps office suite manufacturer states user experience desktop solution significantly improved loongson-3a based predecessor results benchmark test conducted april 2014 available loongson 3 adds 200 new instructions loongson 2 addition specific benefit speeding intel x86 cpu emulation cost 5 total die area new instructions help emulation performance example qemu known example new instructions reduce impact executing x86/cisc-style instructions mips pipeline added improvements qemu ict loongson-3 achieves average 70 performance executing native binaries running x86 binaries nine benchmarks unlike processors intel advanced micro devices via technologies loongson directly support x86 instruction set processor main operating system linux theory os mips support also work example windows ce ported loongson-based system minimal effort 2010 lemote ported android distribution loongson platform many operating systems work loongson gnu compiler collection gcc main compiler software development loongson platform ict also ported open64 loongson ii platform open source applications linux platform ported little effort common open-source applications including openoffice.org mozilla firefox pidgin mplayer applications written java platform supported .net applications unofficial port mono common language runtime available online march 2006 €100 loongson ii computer design called longmeng dragon dream announced lemote june 2006 computex'2006 yellowsheepriver announced municator ysr-639 small form factor computer based 400 mhz loongson 2 currently loongson boxes come 667 mhz godson 2e processor 800 mhz godson 2f processor sold china cny 1599 us 200 cny 1800 respectively without monitor mouse keyboard two manufacturers announced loongson 2f products sale outside china loongson insiders revealed new model based loongson 3a quad-core laptop developed expected launch august 2011 similar design macbook pro apple inc. carry linux operating system default september 2011 lemote announced yeeloong-8133 13.3 laptop featuring 900 mhz quad-core loongson-3a/2gq cpu 26 december 2007 china revealed first loongson based supercomputer performance 1 tflops peak performance 350 gflops measured linpack hefei designated kd-50-i supercomputer designed joint team led chen guoliang computer science technology department university science technology china ict secondary contractor kd-50-i first chinese built supercomputer utilize domestic chinese cpus total 336 loongson-2f cpus nodes interconnected ethernet size computer roughly equivalent household refrigerator cost less rmb800,000 approximately 120,000 80,000 20 april 2010 ustc announced successful development loongson 3a based kd-60-1 new supercomputer cluster standard blade servers total 80 quad-core loongson processors providing theoretical peak performance 1 tflops reduces power consumption 56 compared kd-50-i system similar performance 26 december 2012 ustc announced successful development loongson 3b based kd-90-1 new supercomputer cluster standard blade servers total 10 octo-core loongson processors providing theoretical peak performance 1 tflops reduces power consumption 62 compared kd-60 system similar performance high-performance dawning 6000 projected speed one quadrillion operations per second incorporate loongson processor core dawning 6000 currently jointly developed institute computing technology chinese academy sciences dawning information industry company li guojie chairman dawning information industry company director academician institute computing technology said research development dawning 6000 expected completed two years topstar also released pair mini-atx based motherboards teb-6040m teb-5040 development first loongson chip started 2001 25 june 2008 hu weiwu chief designer loongson processors gave keynote speech isca 2008 held beijing topic speech research development godson processors 2010 january jiangsu province plans buy 1.5 million loongson pcs
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Computer architecture
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disc spanning disc spanning feature cd dvd burning software automatically spreads large amount data across many data discs data set size exceeds storage capacity individual blank disc advantage user need split files directories two blank disc sized pieces hand software may may support slicing single large file order span disc spanners divide numerous files smaller one blank disc capacity across many discs disc spanning works well cd media many applications spanning dvd media fails often lack reliable dvd data disc spanning odd disc spanning used extensively older 3.5 5.25 floppy discs users assume every operating system perform disc spanning media built function incorrect disc spanning schemes include small program reassemble data set structure source machine program could written first disc every disc set use disc spanning cases make files unreadable file-system therefore bounded use program later restore data many users n't want bound solutions use simple disc spanning instead simple disc spanning solution groups files media grouped based size one drawback system files bigger target media burnt drive simple powerful simple calculation would many cd/dvd/bd/hd dvds bunch files need simple grouping displayed like disc1 -- 99 4,479mib br directory br -- dir1 br -- file1 br br disc2 -- 98 4,468mib br directory br -- dir2 br -- file2 br br disc3 -- 45 2,130mib br -- dir3 br etc ... br
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Computer file systems
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