USB接口外文翻譯文獻(xiàn)

PAGEUSB接口外文翻譯文獻(xiàn)PAGEPAGE1USB接口外文翻譯文獻(xiàn)(文檔含中英文對(duì)照即英文原文和中文翻譯)原文：USBUSBistheEnglishacronymforUniversalSerialBUS,Chinesemeaningis"UniversalSerialBus."Itisnotanewbusstandard,butinthePCfieldofapplicationinterfacetechnology.USBistheendof1994byIntel,Compaq,IBM,Microsoftandothercompaniesjointlyproposed.Butuntilrecently,ithasbeenwidelyusedbefore.FromNovember11,1994versionofUSBV0.7releasedlater,USBversionhasgonethroughyearsofdevelopment,uptonowhasbeendevelopedforthe2.0versionofthecurrentexpansionofthestandardcomputerinterface.Atpresent,themainmotherboardisUSB1.1andUSB2.0,theUSBversionoftheUSBplugwitha4-pinplugasstandard,theformcanbeusedtodaisychainalloftheperipheralsconnectupto127canbeconnectedtoexternalequipment,andnolossofbandwidth.USBneedsofthehosthardware,operatingsystemsandperipheralssupportthethreewillwork.ThecurrentmotherboardisgenerallyusedtosupporttheUSBfunctioncontrolchipsets,motherboardsarealsoequippedwithUSBinterfacesocket,thesocketandbackinadditionto,themotherboardalsohasUSBpinsisreserved,canbereceivedthroughtheconnectionboxUSBinterfaceasafrontinfrontoftheconvenienceoftheusers(notethatinconnectiontothemotherboardmanualtoreadandplanstoconnectmustnotbewrongthenthedamageofequipment).AndUSBinterfacecanalsobeconnectedthroughaspecialUSBdrivetoachievetwo-planeinterconnectionlineandcanbeextendedthroughtheHub'sinterfacemore.USBhasafastertransmissionspeed(USB1.1is12Mbps,USB2.0is480Mbps,USB3.0is5Gbps),easytouse,supporthot-swappable,connectflexible,independentpowersupply,etc.,youcanconnectamouse,keyboard,printer,scanners,camera,flashdisk,MP3machines,mobilephones,digitalcameras,mobileharddrive,externalfloppydrivelight,USBcard,ADSLModem,CableModem,etc.,almostalloftheexternalequipment.USBisanexternalbusstandardforthespecificationofcomputerandexternaldeviceconnectivityandcommunications.USBinterfacesupportequipmentfeaturesplug-and-playandhot-swappable.USBinterfacecanbeusedtoconnectasmanyas127kindsofperipherals,suchasmouse,modemandkeyboard.USBsincetheintroductionin1996,hasbeensuccessfullyalternativeserialandparallelport,andtodayalargenumberofpersonalcomputersandintelligentdeviceswillbeassignedoneoftheinterface.USBversionThefirstgeneration:USB1.0/1.1transferrateforthemaximum12Mbps.Launchedin1996.Thesecondgeneration:USB2.0transferrateuptothemaximum480Mbps.USB1.0/1.1andUSB2.0interfacesaremutuallycompatible.ThirdGeneration:USB3.0maximumtransferrateof5Gbps,downwardcompatiblewithUSB1.0/1.1/2.0USBapplications:Withtherapiddevelopmentofcomputerhardware,peripherals,moreandmorekeyboards,mice,modems,printers,scannersalreadyknowntoall,digitalcameras,MP3playersoneafteranother,somuchequipment,howtoaccessapersonalcomputer?USBisgeneratedbasedonthisobjective.USBisacomputerperipheraldeviceisconnectedsothatthestandardizationofasingleinterface,thespecificationsarefromIntel,NEC,Compaq,DEC,IBM,Microsoft,NorthernTelecomestablishedcontact.StandardUSB1.1interfacetransferrateof12Mbps,butaUSBdevicecanonlygetamaximumbandwidthof6Mbps.Thusifanexternaldrive,cantakeuptosix-speedCD-ROM,cannotbehigh.StandardUSB1.1interfacetransferrateof12Mbps,butaUSBdevicecanonlygetamaximumbandwidthof6Mbps.Thusifanexternaldrive,cantakeuptosix-speedCD-ROM,cannotbehigh.AUSBinterfacecantheoreticallysupport127devices,butisstillunabletoachievethisfigure.Infact,foracomputer,theperipheralsaroundthenextfewofthemorethan10,sothisfigureisenoughforustouse.USBalsohasasignificantadvantageisthatsupporthot-swappable,meaningthatinthecaseoftheboot,youcansafelyconnectordisconnectUSBdevices,trueplug-and-play.However,notalloftheWindowssystemsupportUSB.Atpresent,Windowssystem,therearemanydifferentversions,intheseversions,onlytheaboveversionsofWindows98systembetterUSBsupport,whiletheotherversionofWindowsdoesnotsupporttheintegrityoftheUSB.Forexample,theretailversionofWindows95doesnotsupportUSB,andonlylaterbundledwiththePCversionofWindows95supportUSB.Windows95versionsinordertosupportUSB.AlthoughUSBdevicesarecurrentlywidelyused,butitismorecommonUSB1.1interface,itisonlythetransmissionspeedof12Mbps.Forexample,whenyouuseUSB1.1scannerscanapictureofthesizeof40M,theneedforaslongas4minutes.Atsuchapace,sothatusersfinditveryinconvenient,ifthereareafewpicturestoscan,thenyoumusthaveverygoodpatiencetowaitanylonger.Userdemandisthedrivingforcepromotingthedevelopmentoftechnology,manufacturersarealsoawareofthebottleneck.Atthistime,COMPAQ,HewlettPackard,Intel,Lucent,Microsoft,NECandthesevenmanufacturersPHILIPSthisjointlydevelopedthestandardUSB2.0interface.USB2.0willtransferdatabetweendevicesincreasedthespeedof480Mbps,fasterthanUSB1.1standardtoabout40timesspeedimprovementfortheusersmeansthatthegreatestadvantageisthatuserscanusetomoreefficientexternalequipment,andhasawiderangeofspeedperipheralscanbeconnectedtotheUSB2.0line,butwithoutworryingaboutthedatatransmissionbottleneckeffectoccurred.So,ifyouuseUSB2.0scanner,onatotallydifferentpicture40MSojustahalfaminuteorso,ontheblinkofaneyelater,theefficiencygreatlyenhanced.Moreover,USB2.0canusetheoriginaldefinitionofthesamespecificationsUSBcable,connectorspecificationsarealsoidenticaltothepremisethatinthehigh-speedUSB1.1astomaintaintheoutstandingcharacteristics,and,USB2.0deviceswillnotUSB1.Xequipmentincommonusewhentheeventofanyconflict.USB2.0compatiblewithUSB1.1,thatistosayUSB1.1andUSB2.0devicescanbegeneral-purposeequipment,butatthistimeUSB2.0full-speeddevicecanonlyworkinthestate(12Mbit/s).USB2.0high-speed,full-speedandlow-speedthreespeed,high-speedis480Mbit/s,fullspeedis12Mbit/s,lowspeedis1.5Mbit/s.Whichisafull-speedandlow-speedUSB1.1andUSB1.0compatibleanddesignedtobuyUSBproductsthereforecannotjustlistentopropagandamerchantsUSB2.0,butalsotofigureoutisthehigh-speed,full-speedorlow-speeddevices.USBbusisaone-waybus,themaincontrollerinthePCmachine,USBdevicescannotinitiatecommunicationwiththePC.USBdeviceinteroperabilitytosolvecommunicationproblems,themanufacturersdevelopedtheUSBOTGstandard,allowingembeddedsystemcommunicatewitheachotherthroughtheUSBinterfaceinordertogetridofthePC.RenamethenewUSB2.0specificationoftheoriginalUSBstandardUSB1.1intoaUSB2.0FullSpeed(fullversion),atthesametime,theoriginalUSB2.0intoaUSB2.0High-Speed(speedversion)andatthesametimeannouncedanewlogo.Itgoeswithoutsayingthathigh-speedversionofthecoursemorethanthespeedofUSB2.0full-speedversionofUSB2.0.USBvsIEEE1394one,USBandIEEE1394mainlythesameaswhat?Bothareacommonexternaldeviceinterface.Bothofwhichcanquicklytransferlargeamountsofdata.Canconnecttwodifferentdevices.Bothsupporthot-swapping.Bothdonothaveexternalpowersupply.Second,USBandIEEE1394Whatarethedifferences?Transferratebetweenthetwodifferent.USBandIEEE1394transferrateupfasterthanareallypaleintoinsignificance.USBtransferrateisonly480Mbps,canonlyconnectkeyboard,mouse,andmicrophone,suchaslow-speeddevices,andIEEE1394canuse3.2Gbps,canbeusedtoconnectdigitalcameras,scannersandinformationappliancesthatrequirehigh-speeddevicesBetweenthetwodifferentstructures.USBconnectiontobeinatleastonecomputer,andmustcometotherealizationoftheneedforHUBinterconnection,theentirenetworkcanconnectupto127devices.IEEE1394donotneedacomputertocontrolalltheequipment,donotneedtoHUB,IEEE1394bridgecanbeusedtoconnectmultipleIEEE1394network,thatistosayintheuseofIEEE1394achievedafter63IEEE1394devicescanbeusedtobridgeotherIEEE1394networkconnectionuptounlimitedconnections.Intelligentdifferentbetweenthetwo.IEEE1394networkequipmentcanincreaseordecreaseinitsre-establishmentofthenetworkautomatically.HUBisUSBconnecteddevicetodeterminetheincreaseordecrease.Applicationoftwodifferentlevels.NowUSBhasbeenwidelyusedinallaspectsofalmosteveryPCmotherboardUSBinterfacesaresetup,USB2.0willfurtherincreasetherangeofUSBapplications.IEEE1394isnowonlyappliestoaudio,videoandothermultimedia.USBOn-The-GosupplementstandardUSBOn-The-GoSupplement1.0:2001releasedinDecember.USBOn-The-GoSupplement1.0a:2003wasreleased6years,thatis,thecurrentversion.USBOTGistheUSBOn-The-Goacronym,isarecentdevelopmentoftechnology,December18,2001publishedbytheUSBImplementersForum,mainlyusedinavarietyofequipmentortheconnectionbetweenmobiledevicesfordataexchange.Inparticular,PDA,mobilephones,consumerdevices.Changessuchasdigitalcameras,videocameras,printersandotherequipmentbetweenanumberofdifferentstandardconnectors,asmanyassevenkindsofmemorycardformatfordataexchangebetweentheinconvenience.USBtechnologyallowsPCandperipheralsthroughasimpleway,themanufacturingcostswillbemodestdatatransmissionrateofavarietyofdevicestoconnecttogether,wetalkabouttheapplicationoftheabove,topassthroughtheUSBbus,asaPCperipheral,intheunderthecontrolofPCdataexchange.However,thisconvenientwaytoexchange,onceleftthePC,thedevicescannotuseUSBporttooperate,becausethereisnoequipmenttoactasaPCfromthesameHost.On-The-Go,istorealizethattheOTGtechnologyHostintheabsenceofcircumstances,fromthedatatransferbetweendevices.SuchasdigitalcamerastoconnectdirectlytotheprinterthroughOTGtechnology,toconnecttwodevicesseetheUSBport,willproduceanimmediateprintoutthephotos;alsocanbethedataindigitalcameras,throughOTGissenttotheUSBinterfaceofthemobileharddisk,fieldoperationthereisnoneedtocarryexpensivememorycard,ortocarryaportablecomputer.InOTGproducts,addedsomenewfeatures:*newstandardforcompactdesignoftheconnectorsandcables;*inthetraditionalperipheraldevices,anincreaseofHostabilitytomeetthepoint-to-pointconnection;*Thistheabilityofthetwodevicescandynamicallyswitch;*Lowpowerconsumptiontoensurethatbattery-poweredUSBcanworkunderAftertheuseofOTG,doesnotaffecttheoriginalequipmentandPCconnections,butthemarkethasmademorethanonebilliondevicesUSBinterface,butalsothroughtheInternetOTG.AboutUSB3.0IntelCorporation(Intel)andindustry-leadingcompaniestogethertoformagrouptopromoteUSB3.0todevelop10timesfasterthantoday'sultra-high-performanceUSBinterconnecttechnology.ThistechnologyisbyIntel,andHewlett-Packard(HP),NEC,NXPSemiconductorsandTexasInstrumentsIncorporated(TexasInstruments)andotherco-developedapplications,includingpersonalcomputer,consumerandmobileproductsfastsynchronousreal-timetransmission.Withtheincreasingpopularityofdigitalmediaandtheincreasingtransmissionofdocuments-evenmorethan25GB,fastsynchronousreal-timetransmissionhasbecomethenecessaryperformancerequirements.USB3.0backwardcompatibilitywithstandardsandtechnology,bothtraditionalUSBplug-and-playeaseofuseandfunctionality.Thegoalistointroducetechnologytoconnectthanthecurrentlevelofmorethan10timesfasterproducts,usingtheUSBcablethesameframework.InadditiontoUSB3.0specificationisoptimizedtoachievelowerpowerconsumptionandhigherefficiencyoftheagreements,USB3.0portandcabletoachievebackwardscompatibility,aswellassupportforfutureopticaltransmission.IntelsetupagrouptopromoteUSB3.0onthehopethatatthebeginningofUSBDesignInstitute(USB-IF)specificationsforUSB3.0canbeusedastradeassociations.IntegrityoftheUSB3.0specificationisexpectedtolaunchin2008inthefirsthalf,USB3.0willbeusedinitiallyintheformofdiscretesilicon.PromotionSection,USB3.0,includingHewlett-Packard,Intel,NEC,NXPSemiconductorsandTexasInstruments,hasbeencommittedtoprotectingtheUSBdevicedriverinfrastructureandinvestment,USB,aswellastheappearanceofeasy-to-usefeatures,whilecontinuingtocarryforwardtheUSBfunctionalityofthisremarkabletechnology."SincethefirsttimesincetheinstallationofUSBcable,NEChasalwaysbeensupportersofUSBtechnology",NECElectronicsSoCSystemsDivision,saidKatsuhikoItagaki,generalmanager,"ItistimetofurtherdevelopthealreadysuccessfulinterfacetomeettheneedsoftheInternetmarketforlargedatatransmissionspeedhigherdemand,soastoshortenthewaitingtimeforusers.""Withthehigh-speedUSBinthepersonalcomputing,consumerelectronicsandmobilemarketsegmentssuchastheuniversal,weexpectwillsoonreplacetheUSB3.0portUSB2.0high-bandwidthapplicationsbecomethedefactostandard",TexasInstrumentsvicepresidentofWorldwideASICsaidGregHantak,"TIisexcitedabouttheexcellentperformanceoftheUSB3.0willfurtherexpandtheapplicationsandUSBforabetteruserexperience."USB3.0standardcompletedandpublishedByIntel,Microsoft,Hewlett-Packard,TexasInstruments,NEC,ST-NXPindustrygiantssuchasthecompositionoftheUSB3.0PromoterGrouptodayannouncedthattheorganizationresponsiblefordevelopinganewgenerationofUSB3.0standardhasbeenofficiallycompletedandpublished.NewspecificationprovidestentimesthetransmissionspeedofUSB2.0andhigherenergyefficiency,canbewidelyusedinPCperipheralsandconsumerelectronicproducts.CompletedthedevelopmentofUSB3.0standardhasbeentransferredtothenormsofmanagementorganizationsUSBImplementersForum(referredtoasUSB-IF).TheorganizationwillworkwithhardwarevendorstodevelopstandardstosupportthenewUSB3.0hardware,buthavetowaitfortheactualmarketforsometime.USB1.0isthefirsteditionin1996,appears,thespeedisonly1.5Mb/s;twoyearsaftertheupgradetoUSB1.1,alsogreatlyspeedsupto12Mb/s,sofarinsomeoftheoldequipmentcanalsoseethatthestandardinterface;inApril2000,iscurrentlywidelyusedintheintroductionofUSB2.0speedreacheda480Mb/s,fourUSB1.1istentimes;Noweightoverthefirstsixmonths,USB2.0speedhavebeenunabletomeettheapplicationneeds,USB3.0willcomeintobeing,thelargesttransmissionbandwidthupto5.0Gb/s,whichis625MB/s,atthesametimeintheuseofA-typeinterfaceWhenbackwardscompatibility.IEEEhasrecentlyapprovedthenewnormsofIEEE1394-2008,butthenewversionofthetransmissionspeedofFireWireisonly3.2Gb/s,theUSB3.0isequivalenttolittlemorethan60percent.ItisnowonderthatAppleandotherindustrymanufacturersgenerallylostinterestinthetechnology.USB2.0bus-basedsystemforhalf-duplexline,canonlyprovideaone-waydatastreaming,andUSB3.0usingthedualsimplexfour-wiredifferentialsignallines,theclubwouldsupporttheconcurrenttwo-waydatastreamtransmission,whichisthespeedofthenewrulesthatincreasethekeyreason.Inaddition,USB3.0alsointroducedanewmechanismforpowermanagement,supportstandby,suchasastateofhibernationandsuspension.MeasuringinstrumentmakerTektronix(Tektronix)lastmonthannouncedthefirstUSB3.0forthetesttoolsthatcanhelpdeveloperstoverifythenewhardwaredesignspecificationandthecompatibilitybetween.USB3.0devicesintheactualapplicationwillbereferredtoas"USBSuperSpeed",followthepreviousUSB1.1FullSpeedandUSB2.0HighSpeed.Isexpectedtosupportthenewcontrollerwillregulatethebusinessin2009inthesecondhalfofthelaunchofconsumerproductsareexpectedtobelistedin2010.譯文:USBUSB是英文UniversalSerialBUS的縮寫，中文含義是“通用串行總線”。它不是一種新的總線標(biāo)準(zhǔn)，而是應(yīng)用在PC領(lǐng)域的接口技術(shù)。USB是在1994年底由英特爾、康柏、IBM、Microsoft等多家公司聯(lián)合提出的。不過直到近期，它才得到廣泛地應(yīng)用。從1994年11月11日發(fā)表了USBV0.7版本以后，USB版本經(jīng)歷了多年的發(fā)展，到現(xiàn)在已經(jīng)發(fā)展為2.0版本，成為目前電腦中的標(biāo)準(zhǔn)擴(kuò)展接口。目前主板中主要是采用USB1.1和USB2.0，各USB版本間能很好的兼容。USB用一個(gè)4針插頭作為標(biāo)準(zhǔn)插頭，采用菊花鏈形式可以把所有的外設(shè)連接起來，最多可以連接127個(gè)外部設(shè)備，并且不會(huì)損失帶寬。USB需要主機(jī)硬件、操作系統(tǒng)和外設(shè)三個(gè)方面的支持才能工作。目前的主板一般都采用支持USB功能的控制芯片組，主板上也安裝有USB接口插座，而且除了背板的插座之外，主板上還預(yù)留有USB插針，可以通過連線接到機(jī)箱前面作為前置USB接口以方便使用（注意，在接線時(shí)要仔細(xì)閱讀主板說明書并按圖連接，千萬不可接錯(cuò)而使設(shè)備損壞）。而且USB接口還可以通過專門的USB連機(jī)線實(shí)現(xiàn)雙機(jī)互連，并可以通過Hub擴(kuò)展出更多的接口。USB具有傳輸速度快（USB1.1是12Mbps，USB2.0是480Mbps,USB3.0是5Gbps），使用方便，支持熱插拔，連接靈活，獨(dú)立供電等優(yōu)點(diǎn)，可以連接鼠標(biāo)、鍵盤、打印機(jī)、掃描儀、攝像頭、閃存盤、MP3機(jī)、手機(jī)、數(shù)碼相機(jī)、移動(dòng)硬盤、外置光軟驅(qū)、USB網(wǎng)卡、ADSLModem、CableModem等，幾乎所有的外部設(shè)備。USB是一個(gè)外部總線標(biāo)準(zhǔn)，用于規(guī)范電腦與外部設(shè)備的連接和通訊。USB接口支持設(shè)備的即插即用和熱插拔功能。USB接口可用于連接多達(dá)127種外設(shè)，如鼠標(biāo)、調(diào)制解調(diào)器和鍵盤等。USB自從1996年推出后，已成功替代串口和并口，并成為當(dāng)今個(gè)人電腦和大量智能設(shè)備的必配的接口之一。USB的版本:第一代：USB1.0/1.1的最大傳輸速率為12Mbps。1996年推出。第二代：USB2.0的最大傳輸速率高達(dá)480Mbps。USB1.0/1.1與USB2.0的接口是相互兼容的。第三代：USB3.0最大傳輸速率5Gbps,向下兼容USB1.0/1.1/2.0USB的應(yīng)用:隨著計(jì)算機(jī)硬件飛速發(fā)展，外圍設(shè)備日益增多，鍵盤、鼠標(biāo)、調(diào)制解調(diào)器、打印機(jī)、掃描儀早已為人所共知，數(shù)碼相機(jī)、MP3隨身聽接踵而至，這么多的設(shè)備，如何接入個(gè)人計(jì)算機(jī)？USB就是基于這個(gè)目的產(chǎn)生的。USB是一個(gè)使計(jì)算機(jī)周邊設(shè)備連接標(biāo)準(zhǔn)化、單一化的接口，其規(guī)格是由Intel、NEC、Compaq、DEC、IBM、Microsoft、NorthernTelecom聯(lián)系制定的。USB1.1標(biāo)準(zhǔn)接口傳輸速率為12Mbps，但是一個(gè)USB設(shè)備最多只可以得到6Mbps的傳輸頻寬。因此若要外接光驅(qū),至多能接六倍速光驅(qū)，無法再高。而若要即時(shí)播放MPEG-1的VCD影片,至少要1.5Mbps的傳輸頻寬,這點(diǎn)USB辦得到,但是要完成數(shù)據(jù)量大四倍的MPEG-2的DVD影片播放，USB可能就很吃力了，若再加上AC-3音頻數(shù)據(jù)，USB設(shè)備就很難實(shí)現(xiàn)即時(shí)播放了。一個(gè)USB接口理論上可以支持127個(gè)裝置，但是目前還無法達(dá)到這個(gè)數(shù)字。其實(shí)，對(duì)于一臺(tái)計(jì)算機(jī)，所接的周邊外設(shè)很少有超過10個(gè)的，因此這個(gè)數(shù)字是足夠我們使用的。USB還有一個(gè)顯著優(yōu)點(diǎn)就是支持熱插拔，也就是說在開機(jī)的情況下，你也可以安全地連接或斷開USB設(shè)備，達(dá)到真正的即插即用。不過，并非所有的Windows系統(tǒng)都支持USB。目前，Windows系統(tǒng)中有許多不同的版本，在這些版本中，只有Windows98以上版本的系統(tǒng)對(duì)USB的支持較好，而其他的Windows版本并不能完整支持USB。例如Windows95的零售版是不支持USB的，只有后來與PC捆綁銷售的Windows95版本才支持USB。目前USB設(shè)備雖已被廣泛應(yīng)用，但比較普遍的卻是USB1.1接口，它的傳輸速度僅為12Mbps。舉個(gè)例子說，當(dāng)你用USB1.1的掃描儀掃一張大小為40M的圖片，需要四分鐘之久。這樣的速度，讓用戶覺得非常不方便，如果有好幾張圖片要掃的話，就得要有很好的耐心來等待了。用戶的需求，是促進(jìn)科技發(fā)展的動(dòng)力，廠商也同樣認(rèn)識(shí)到了這個(gè)瓶頸。這時(shí)，COMPAQ、HewlettPackard、Intel、Lucent、Microsoft、NEC和PHILIPS這7家廠商聯(lián)合制定了USB2.0接口標(biāo)準(zhǔn)。USB2.0將設(shè)備之間的數(shù)據(jù)傳輸速度增加到了480Mbps，比USB1.1標(biāo)準(zhǔn)快40倍左右，速度的提高對(duì)于用戶的最大好處就是意味著用戶可以使用到更高效的外部設(shè)備，而且具有多種速度的周邊設(shè)備都可以被連接到USB2.0的線路上，而且無需擔(dān)心數(shù)據(jù)傳輸時(shí)發(fā)生瓶頸效應(yīng)。所以，如果你用USB2.0的掃描儀，就完全不同了，掃一張40M的圖片只需半分鐘左右的時(shí)間，一眨眼就過去了，效率大大提高。而且，USB2.0可以使用原來USB定義中同樣規(guī)格的電纜，接頭的規(guī)格也完全相同，在高速的前提下一樣保持了USB1.1的優(yōu)秀特色，并且，USB2.0的設(shè)備不會(huì)和USB1.X設(shè)備在共同使用的時(shí)候發(fā)生任何沖突。USB2.0兼容USB1.1，也就是說USB1.1設(shè)備可以和USB2.0設(shè)備通用，但是這時(shí)USB2.0設(shè)備只能工作在全速狀態(tài)下(12Mbit/s)。USB2.0有高速、全速和低速三種工作速度，高速是480Mbit/s，全速是12Mbit/s，低速是1.5Mbit/s。其中全速和低速是為兼容USB1.1和USB1.0而設(shè)計(jì)的，因此選購(gòu)USB產(chǎn)品時(shí)不能只聽商家宣傳USB2.0,還要搞清楚是高速、全速還是低速設(shè)備。USB總線是一種單向總線，主控制器在PC機(jī)上，USB設(shè)備不能主動(dòng)與PC機(jī)通信。為解決USB設(shè)備互通信問題，有關(guān)廠商又開發(fā)了USBOTG標(biāo)準(zhǔn)，允許嵌入式系統(tǒng)通過USB接口互相通信，從而甩掉了PC機(jī)。新USB2.0規(guī)范重新命名了USB標(biāo)準(zhǔn)將原先的USB1.1改成了USB2.0FullSpeed（全速版），同時(shí)將原有的USB2.0改成了USB2.0High-Speed（高速版），并同時(shí)公布了新的標(biāo)識(shí)。不言而喻，高速版的USB2.0速度當(dāng)然超過全速版的USB2.0。USBvsIEEE1394一、USB與IEEE1394的相同點(diǎn)主要有哪些？?jī)烧叨际且环N通用外接設(shè)備接口。兩者都可以快速傳輸大量數(shù)據(jù)。兩者都能連接多個(gè)不同設(shè)備。兩者都支持熱插撥。兩者都可以不用外部電源。二、USB與IEEE1394的不同點(diǎn)有哪些？?jī)烧叩膫鬏斔俾什煌?。USB的傳輸速率與IEEE1394的速率比起來真是小巫見大巫了。USB的傳輸速率現(xiàn)在只有480Mbps，只能連接鍵盤、鼠標(biāo)與麥克風(fēng)等低速設(shè)備，而IEEE1394可以使用3.2Gbps，可以用來連接數(shù)碼相機(jī)、掃描儀和信息家電等需要高速率的設(shè)備。兩者的結(jié)構(gòu)不同。USB在連接時(shí)必須至少有一臺(tái)電腦，并且必須需要HUB來實(shí)現(xiàn)互連，整個(gè)網(wǎng)絡(luò)中最多可連接127臺(tái)設(shè)備。IEEE1394并不需要電腦來控制所有設(shè)備，也不需要HUB，IEEE1394可以用網(wǎng)橋連接多個(gè)IEEE1394網(wǎng)絡(luò)，也就是說在用IEEE1394實(shí)現(xiàn)了63臺(tái)IEEE1394設(shè)備之后也可以用網(wǎng)橋?qū)⑵渌腎EEE1394網(wǎng)絡(luò)連接起來，達(dá)到無限制連接。兩者的智能化不同。IEEE1394網(wǎng)絡(luò)可以在其設(shè)備進(jìn)行增減時(shí)自動(dòng)重設(shè)網(wǎng)絡(luò)。USB是以HUB來判斷連接設(shè)備的增減了。兩者的應(yīng)用程度不同?，F(xiàn)在USB已經(jīng)被廣泛應(yīng)用于各個(gè)方面，幾乎每臺(tái)PC主板都設(shè)置了USB接口，USB2.0也會(huì)進(jìn)一步加大USB應(yīng)用的范圍。IEEE1394現(xiàn)在只被應(yīng)用于音頻、視頻等多媒體方面。USBOn-The-Go補(bǔ)充標(biāo)準(zhǔn)USBOn-The-GoSupplement1.0：2001年12月發(fā)布。USBOn-The-GoSupplement1.0a：2003年6月發(fā)布，即當(dāng)前版本。USBOTG是USBOn-The-Go的縮寫，是近年發(fā)展起來的技術(shù)，2001年12月18日由USBImplementersForum公布，主要應(yīng)用于各種不同的設(shè)備或移動(dòng)設(shè)備間的聯(lián)接，進(jìn)行數(shù)據(jù)交換。特別是PDA、移動(dòng)電話、消費(fèi)類設(shè)備。改變?nèi)鐢?shù)碼照相機(jī)、攝像機(jī)、打印機(jī)等設(shè)備間多種不同制式連接器，多達(dá)7種制式的存儲(chǔ)卡間數(shù)據(jù)交換的不便。USB技術(shù)的發(fā)展，使得PC和周邊設(shè)備能夠通過簡(jiǎn)單方式、適度的制造成本將各種數(shù)據(jù)傳輸速度的設(shè)備連接在一起，上述我們提到應(yīng)用，都可以通過USB總線，作為PC的周邊，在PC的控制下進(jìn)行數(shù)據(jù)交換。但這種方便的交換方式，一旦離開了PC，各設(shè)備間無法利用USB口進(jìn)行操作，因?yàn)闆]有一個(gè)從設(shè)備能夠充當(dāng)PC一樣的Host。On-The-Go，即OTG技術(shù)就是實(shí)現(xiàn)在沒有Host的情況下，實(shí)現(xiàn)從設(shè)備間的數(shù)據(jù)傳送。例如數(shù)碼相機(jī)直接連接到打印機(jī)上，通過OTG技術(shù)，連接兩臺(tái)設(shè)備見的USB口，將拍出的相片立即打印出來；也可以將數(shù)碼照相機(jī)中的數(shù)據(jù)，通過OTG發(fā)送到USB接口的移動(dòng)硬盤上，野外操作就沒有必要攜帶價(jià)格昂貴的存儲(chǔ)卡，或者背一個(gè)便攜電腦。在OTG產(chǎn)品中，增加了一些新的特性：*新的標(biāo)準(zhǔn)，適用于設(shè)計(jì)小巧的連接器和電纜；*在傳統(tǒng)的周邊設(shè)備上，增加了Host能力，適應(yīng)點(diǎn)到點(diǎn)的連接；*這種能力可以在兩個(gè)設(shè)備間動(dòng)態(tài)地切換；*低的功耗，保證USB可以在電池供電情況下工作使用OTG后，不影響原設(shè)備和PC的連接，但使得在市場(chǎng)上已有超過10億個(gè)USB接口的設(shè)備，也能通過OTG互聯(lián)。USB3.0簡(jiǎn)介英特爾公司（Intel）和業(yè)界領(lǐng)先的公司一起攜手組建了USB3.0推廣組，旨在開發(fā)速度超過當(dāng)今10倍的超高效USB互聯(lián)技術(shù)。該技術(shù)是由英特爾，以及惠普（HP）、NEC、NXP半導(dǎo)體以及德州儀器（TexasInstruments）等公司共同開發(fā)的，應(yīng)用領(lǐng)域包括個(gè)人計(jì)算機(jī)、消費(fèi)及移動(dòng)類產(chǎn)品的快速同步即時(shí)傳輸。隨著數(shù)字媒體的日益普及以及傳輸文件的不斷增大——甚至超過25GB，快速同步即時(shí)傳輸已經(jīng)成為必要的性能需求。USB3.0具有后向兼容標(biāo)準(zhǔn)，并兼具傳統(tǒng)USB技術(shù)的易用性和即插即用功能。該技術(shù)的目標(biāo)是推出比目前連接水平快10倍以上的產(chǎn)品，采用與有線USB相同的架構(gòu)。除對(duì)USB3.0規(guī)格進(jìn)