計(jì)算機(jī)專業(yè)英語(第二版)Chapter1

21世紀(jì)高職高專新概念教材計(jì)算機(jī)專業(yè)英語

（第二版）孫建忠主編白鳳仙程立副主編中國水利水電出版社ISBN7-5084-4148-6ComputerEnglishChapter1TheHistoryandFutureofComputersKeypoints:

usefultermsanddefinitionsofcomputers

Difficultpoints:

describingthefeaturesofcomputersofeachgenerationRequirements:1.Thetrendsofcomputerhardwareandsoftware2.Basiccharacteristicsofmoderncomputers3.Majorcharacteristicsofthefourgenerationsofmoderncomputers4.了解科技英語的特點(diǎn)，掌握科技英語翻譯要點(diǎn)

NewWords&Expressions:computerlikea.計(jì)算機(jī)似的 electromechanicala.機(jī)電的,電機(jī)的

vacuumtubes真空管

CensusBureau人口普查局

thousandsof成千上萬的 knownas通常所說的，以……著稱

1.1TheInventionoftheComputer

Abbreviations:ENIAC(ElectronicNumericalIntegratorandComputer)

電子數(shù)字積分計(jì)算機(jī)，ENIAC計(jì)算機(jī)

EDSAC(ElectronicDelayStorageAutomaticComputer)

延遲存儲(chǔ)電子自動(dòng)計(jì)算機(jī)

BINAC(BinaryAutomaticComputer)二進(jìn)制自動(dòng)計(jì)算機(jī)

UNIVAC(UniversalAutomaticComputer)通用自動(dòng)計(jì)算機(jī)

Itishardtosayexactlywhenthemoderncomputerwasinvented.Startinginthe1930sandthroughthe1940s,anumberofmachinesweredevelopedthatwerelikecomputers.Butmostofthesemachinesdidnothaveallthecharacteristicsthatweassociatewithcomputerstoday.Thesecharacteristicsarethatthemachineiselectronic,thatithasastoredprogram,andthatitisgeneralpurpose.很難確切地說現(xiàn)代計(jì)算機(jī)是什么時(shí)候發(fā)明的。從20世紀(jì)30年代到40年代，制造了許多類似計(jì)算機(jī)的機(jī)器。但是這些機(jī)器大部分沒有今天我們所說的計(jì)算機(jī)的所有特征。這些特性是：機(jī)器是電子的，具有儲(chǔ)存的程序,而且是通用的。1.1TheInventionoftheComputer1.1TheInventionoftheComputerOneofthefirstcomputerlikedeviceswasdevelopedinGermanybyKonrad

Zusein1941.CalledtheZ3,itwasgeneral-purpose,stored-programmachinewithmanyelectronicparts,butithadamechanicalmemory.AnotherelectromechanicalcomputingmachinewasdevelopedbyHowardAiken,withfinancialassistancefromIBM,atHarvardUniversityin1943.ItwascalledtheAutomaticSequenceControlCalculatorMarkI,orsimplytheHarvardMarkI.Neitherofthesemachineswasatruecomputer,however,becausetheywerenotentirelyelectronic.

第一個(gè)類似計(jì)算機(jī)的裝置之一是1941年由德國的Konrad

Zuse研制的，叫做Z3,它是通用型儲(chǔ)存程序機(jī)器，具有許多電子部件，但是它的存儲(chǔ)器是機(jī)械的。另一臺(tái)機(jī)電式計(jì)算機(jī)器是由霍華德.艾坎在IBM的資助下于1943年在哈佛大學(xué)研制的。它被稱為自動(dòng)序列控制計(jì)算器MarkI,或簡(jiǎn)稱哈佛MarkI。然而，這些機(jī)器都不是真正的計(jì)算機(jī),因?yàn)樗鼈儾皇峭耆娮踊摹?.1.1TheENIACPerhapsthemostinfluentialoftheearlycomputerlikedeviceswastheElectronicNumericalIntegratorandComputer,orENIAC.ItwasdevelopedbyJ.PresperEckertandJohnMauchlyattheUniversityofPennsylvania.Theprojectbeganin1943andwascompletedin1946.Themachinewashuge;itweighed30tonsandcontainedover18,000vacuumtubes.也許早期最具影響力的類似計(jì)算機(jī)的裝置應(yīng)該是電子數(shù)字積分計(jì)算機(jī)，或簡(jiǎn)稱ENIAC。它是由賓夕凡尼亞大學(xué)的J.PresperEckert和JohnMauchly研制的。該工程于1943年開始，并于1946年完成。這臺(tái)機(jī)器極其龐大，重達(dá)30噸，而且包含18,000多個(gè)真空管。1.1TheInventionoftheComputer1.1.1TheENIACTheENIACwasamajoradvancementforitstime.Itwasthefirstgeneral-purpose,electroniccomputingmachineandwascapableofperformingthousandsofoperationspersecond.Itwascontrolled,however,byswitchesandplugsthathadtobemanuallyset.Thus,althoughitwasageneral-purposeelectronicdevice,itdidnothaveastoredprogram.Therefore,itdidnothaveallthecharacteristicsofacomputer.ENIAC是當(dāng)時(shí)重要的成就。它是第一臺(tái)通用型電子計(jì)算機(jī)器，并能夠執(zhí)行每秒數(shù)千次運(yùn)算。然而,它是由開關(guān)和繼電器控制的，必須手工設(shè)定。因此，雖然它是一個(gè)通用型電子裝置，但是它沒有儲(chǔ)存程序。因此,它不具備計(jì)算機(jī)的所有特征。1.1TheInventionoftheComputer1.1.1TheENIACWhileworkingontheENIAC,EckertandMauchlywerejoinedbyabrilliantmathematician,JohnvonNeuman.Together,theydevelopedtheideaofastoredprogramcomputer.Thismachine,calledtheElectronicDiscreteVariableAutomaticComputer,orEDVAC,wasthefirstmachinewhosedesignincludedallthecharacteristicsofacomputer.Itwasnotcompleted,however,until1951.在ENIAC的研制中，一個(gè)天才的數(shù)學(xué)家VonNeuman(馮.諾伊曼)加入到Eckert和Mauchly團(tuán)隊(duì),他們一起提出了儲(chǔ)存程序計(jì)算機(jī)的主意。這部機(jī)器被稱做電子離散變量自動(dòng)計(jì)算機(jī),或簡(jiǎn)稱EDVAC,是第一部包括了計(jì)算機(jī)所有特征的機(jī)器。然而,直到1951年，它一直沒有完成。1.1TheInventionoftheComputer1.1.1TheENIACBeforetheEDVACwasfinished,severalothermachineswerebuiltthatincorporatedelementsoftheEDVACdesignofEckert,Mauchly,andvonNeuman.OnewastheElectronicDelayStorageAutomaticComputer,orEDSAC,whichwasdevelopedinCambridge,England.ItfirstoperatedinMayof1949andisprobablytheworld’sfirstelectronicstored-program,general-purposecomputertobecomeoperational.ThefirstcomputertooperateintheUnitedStateswastheBinaryAutomaticComputer,orBINAC,whichbecameoperationalinAugustof1949.在EDVAC完成之前，其他一些機(jī)器建成了，它們吸收了Eckert、Mauchly和Neuman設(shè)計(jì)的要素。其中一部是在英國劍橋研制的電子延遲存儲(chǔ)自動(dòng)計(jì)算機(jī),或簡(jiǎn)稱EDSAC，它在1949年5月首次運(yùn)行，它可能是世界的第一臺(tái)電子儲(chǔ)存程序、通用型計(jì)算機(jī)投入運(yùn)行。在美國運(yùn)行的第一部計(jì)算機(jī)是二進(jìn)制自動(dòng)計(jì)算機(jī),或簡(jiǎn)稱BINAC,它在1949年8月投入運(yùn)行。1.1TheInventionoftheComputer1.1TheInventionoftheComputer1.1.2TheUNIVACILikeothercomputingpioneersbeforethem,EckertandMauchlyformedacompanyin1947todevelopacommercialcomputer.ThecompanywascalledtheEckert-MauchlyComputerCorporation.TheirobjectivewastodesignandbuildtheUniversalAutomaticComputerorUNIVAC.Becauseofdifficultiesofgettingfinancialsupport,theyhadtosellthecompanytoRemingtonRandin1950.EckertandMauchlycontinuedtoworkontheUNIVACatRemingtonRandandcompleteditin1951.KnownastheUNIVACI,thismachinewasthefirstcommerciallyavailablecomputer.像他們之前的其他計(jì)算機(jī)先驅(qū)一樣,Eckert和Mauchly在1947年組成了一家公司開發(fā)商業(yè)計(jì)算機(jī)。公司名叫Eckert-Mauchly計(jì)算機(jī)公司。他們的目標(biāo)是設(shè)計(jì)并建造通用自動(dòng)計(jì)算機(jī)或UNIVAC。因?yàn)殡y以獲得財(cái)政支持，他們不得不在1950年把公司賣給了RemingtonRand公司。Eckert和Mauchly繼續(xù)在RemingtonRand公司從事UNIVAC的研制工作，并在1951年取得成功。眾所周知的UNIVACI機(jī)器是世界上第一部商業(yè)化計(jì)算機(jī)。1.1TheInventionoftheComputer1.1.2TheUNIVACIThefirstUNIVACIwasdeliveredtotheCensusBureauandusedforthe1950census.ThesecondUNIVACIwasusedtopredictthatDwightEisenhowerwouldwinthe1952presidentialelection,lessthananhourafterthepollsclosed.TheUNIVACIbeganthemodernofcomputeruse.

第一臺(tái)UNIVACI被交付人口普查局用于1950年的人口普查。在投票點(diǎn)關(guān)閉后1小時(shí)之內(nèi)，第二臺(tái)UNIVACI被用于預(yù)測(cè)D.艾森豪威爾會(huì)贏得1952年總統(tǒng)大選。UNIVACI開始了現(xiàn)代計(jì)算機(jī)的應(yīng)用。

NewWords&Expressions:resultin導(dǎo)致,造成……結(jié)果

airconditioning空氣調(diào)節(jié)takedeliveryof正式接過… Navylieutenant海軍上尉high-levellanguage高級(jí)語言

mainframen.主機(jī),大型機(jī)

moreandmore越來越多的

rangefrom…to…從…到…multiprogrammingn.多道程序設(shè)計(jì) time-sharen.分時(shí)，時(shí)間共享virtualmemory虛擬內(nèi)存

fromscratch從頭開始compatiblea.兼容的； outnumbervt.數(shù)目超過，比…多markwith以……為標(biāo)志（商標(biāo)）

startoffv.出發(fā),開始proliferatev.增生,擴(kuò)散

1.2ComputerGenerationsAbbreviations:VLSI(VeryLargeScaleIntegratedCircuit)超大規(guī)模集成電路LSI(LargeScaleIntegratedCircuit)大規(guī)模集成電路DEC(DigitalEquipmentCorporation)美國數(shù)字設(shè)備公司COBOL(CommonBusiness-OrientedLanguage)面向商業(yè)的通用語言1.2ComputerGenerations1.2.1First-GenerationComputers:1951～1958First-generationcomputerswerecharacterizedbytheuseofvacuumtubesastheirprincipalelectroniccomponent.Vacuumtubesarebulkyandproducealotofheat,sofirst-generationcomputerswerelargeandrequiredextensiveairconditioningtokeepthemcool.Inaddition,becausevacuumtubesdonotoperateveryfast,thesecomputerswererelativelyslow.第一代計(jì)算機(jī)的特色是使用真空管為其主要電子器件。真空管體積大且發(fā)熱嚴(yán)重,因此第一代計(jì)算機(jī)體積龐大，并且需要大量的空調(diào)設(shè)備保持冷卻。此外,因?yàn)檎婵展苓\(yùn)行不是很快，這些計(jì)算機(jī)運(yùn)行速度相對(duì)較慢。TheUNIVACIwasthefirstcommercialcomputerinthisgeneration.Asnotedearlier,itwasusedintheCensusBureauin1951.Itwasalsothefirstcomputertobeusedinabusinessapplication.In1954,GeneralElectrictookdeliveryofaUNIVACIanduseditforsomeofitsbusinessdataprocessing.UNIVACI是第一代中最早的商業(yè)化計(jì)算機(jī)。如前所述，它在1951年被用于人口普查局。它還是第一部用于商業(yè)應(yīng)用的計(jì)算機(jī)。在1954年,通用電氣接收了UNIVACI,并用它進(jìn)行一些商業(yè)數(shù)據(jù)處理。

1.2ComputerGenerations1.2.1First-GenerationComputers:1951～1958TheUNIVACIwasnotthemostpopularfirst-generationcomputer,however.ThishonorgoestotheIBM650.Itwasfirstdeliveredin1955beforeRemingtonRandcouldcomeoutwithasuccessortotheUNIVACI.WiththeIBM650,IBMcapturedthemajorityofthecomputermarket,apositionitstillholdstoday.然而，UNIVACI并不是最流行的第一代計(jì)算機(jī)。這一榮譽(yù)屬于IBM650。它在RemingtonRand能夠造出UNIVACI的后續(xù)產(chǎn)品之前的1955年首次交付使用。憑借IBM650,IBM占有了大半計(jì)算機(jī)市場(chǎng)，它在今天仍然保持這一位置。1.2ComputerGenerations1.2.1First-GenerationComputers:1951～1958Atthesametimethathardwarewasevolving,softwarewasdeveloping.Thefirstcomputerswereprogrammedinmachinelanguage,butduringthefirstcomputergeneration,theideaofprogramminglanguagetranslationandhigh-levellanguagesoccurred.MuchofthecreditfortheseideasgoestoGraceHopper,who,asaNavylieutenantin1945,learnedtoprogramtheHarvardMarkI.In1952,shedevelopedthefirstprogramminglanguagetranslator,followedbyothersinlateryears.ShealsodevelopedalanguagecalledFlow-maticin1957,whichformedthebasisforCOBOL,themostcommonlyusedbusinessprogramminglanguagetoday.同時(shí)，硬件在進(jìn)化,軟件也在發(fā)展。第一部計(jì)算機(jī)用機(jī)器語言編程，但是在第一代計(jì)算機(jī)期間，程序語言翻譯的概念和高級(jí)語言出現(xiàn)了。這些主意大部分歸功于GraceHopper,她在1954年是一名海軍上尉，學(xué)習(xí)為哈佛MarkI計(jì)算機(jī)編程。在1952年，她開發(fā)了第一種編程語言翻譯器,在稍后的數(shù)年內(nèi)為其他人所效仿。她還在1957年開發(fā)了一種稱為Flow-matic的語言,為COBOL——今天最廣泛應(yīng)用的商業(yè)編程語言——奠定了基礎(chǔ)。1.2ComputerGenerations1.2.1First-GenerationComputers:1951～1958OthersoftwaredevelopmentsduringthefirstcomputergenerationincludethedesignoftheFORTRANprogramminglanguagein1957.Thislanguagebecamethefirstwidelyusedhigh-levellanguage.Also,thefirstsimpleoperatingsystemsbecameavailablewithfirst-generationcomputers.在第一代計(jì)算機(jī)期間,軟件方面的其他的進(jìn)展包括1957年FORTRAN語言的設(shè)計(jì)。這種語言成為第一種廣泛使用的高級(jí)語言。同時(shí),第一個(gè)簡(jiǎn)單的操作系統(tǒng)隨著第一代計(jì)算機(jī)而出現(xiàn)。1.2ComputerGenerations1.2.2Second-GenerationComputers:1959～1963Inthesecondgenerationofcomputers,transistorsreplacedvacuumtubes.Althoughinventedin1948,thefirstall-transistorcomputerdidnotbecomeavailableuntil1959.Transistorsaresmallerandlessexpensivethanvacuumtubes,andtheyoperatefasterandproducelessheat.Hence,withsecond-generationcomputers,thesizeandcostofcomputersdecreased,theirspeedincreased,andtheirair-conditioningneedswerereduced.在第二代計(jì)算機(jī)中，晶體管取代了真空管。雖然發(fā)明于1948年,但第一臺(tái)全晶體管計(jì)算機(jī)直到1959年才成為現(xiàn)實(shí)。晶體管比真空管體積小、價(jià)格低，而且運(yùn)行快而發(fā)熱少。因此，隨著第二代計(jì)算機(jī)的出現(xiàn)，計(jì)算機(jī)的體積和成本降低、速度提高，且它們對(duì)空調(diào)的需要減少。Manycompaniesthathadnotpreviouslysoldcomputerenteredtheindustrywiththesecondgeneration.OneofthesecompaniesthatstillmakescomputersisControlDataCorporation(CDC).Theywerenotedformakinghigh-speedcomputersforscientificwork.許多先前不經(jīng)銷計(jì)算機(jī)的公司隨著第二代計(jì)算機(jī)的出現(xiàn)進(jìn)入計(jì)算機(jī)行業(yè)，其中今天仍然制造計(jì)算機(jī)的公司之一是控制數(shù)據(jù)公司(CDC),他們以制造用于科學(xué)工作的高速計(jì)算機(jī)而著名。1.2ComputerGenerations1.2.2Second-GenerationComputers:1959～1963RemintongRand,nowcalledSperr-RandCorporation,madeseveralsecond-generationUNIVACcomputers.IBM,however,continuedtodominatetheindustry.Oneofthemostpopularsecond-generationcomputerswastheIBM1401,whichwasamedium-sizedcomputerusedbymanybusinesses.RemintongRand,現(xiàn)在叫做Sperr-Rand公司,制造了一些第二代UNIVAC計(jì)算機(jī)。然而，IBM繼續(xù)稱霸計(jì)算機(jī)行業(yè)。最流行的第二代計(jì)算機(jī)之一是IBM1401,這是一部許多企業(yè)使用的中型計(jì)算機(jī)。Allcomputersatthistimeweremainframecomputerscostingoveramilliondollars.Thefirstminicomputerbecameavailablein1960andcostabout$120,000.ThiswasthePDP-1,manufacturedbyDigitalEquipmentCorporation(DEC).當(dāng)時(shí)所有的計(jì)算機(jī)都是價(jià)值百萬元以上的大型計(jì)算機(jī)。第一臺(tái)小型計(jì)算機(jī)產(chǎn)生于1960年，價(jià)值12萬美元，它就是由數(shù)據(jù)設(shè)備公司(DEC)制造的PDP-1。

1.2ComputerGenerations1.2.2Second-GenerationComputers:1959～1963Softwarealsocontinuedtodevelopduringthistime.Manynewprogramminglanguagesweredesigned,includingCOBOLin1960.Moreandmorebusinessesandorganizationswerebeginningtousecomputersfortheirdataprocessingneeds.在此期間軟件也在繼續(xù)發(fā)展。許多新的編程語言被發(fā)明,包括1960年發(fā)明的COBOL。越來越多的企業(yè)和組織開始使用計(jì)算機(jī)以滿足他們的數(shù)據(jù)處理需要。1.2ComputerGenerations1.2.3Third-GenerationComputers:1964～1970ThetechnicaldevelopmentthatmarksthethirdgenerationofcomputersistheuseofintegratedcircuitsorICsincomputers.Anintegratedcircuitisapieceofsilicon(achip)containingnumeroustransistors.OneICreplacesmanytransistorsinacomputer;resultinacontinuationofthetrendsbeguninthesecondgeneration.Thesetrendsincludereducedsize,reducedcost,increasedspeed,andreducedneedforairconditioning.作為第三代計(jì)算機(jī)標(biāo)志的技術(shù)發(fā)展是在計(jì)算機(jī)中使用集成電路或簡(jiǎn)稱IC。一個(gè)集成電路就是包含許多晶體管的一個(gè)硅片(芯片)。一個(gè)集成電路代替了計(jì)算機(jī)中的許多晶體管，導(dǎo)致了始于第二代的一些趨勢(shì)的繼續(xù)。這些趨勢(shì)包括計(jì)算機(jī)體積減小、成本降低、速度提高和對(duì)空調(diào)的需要減少。

1.2ComputerGenerations1.2.3Third-GenerationComputers:1964～1970Althoughintegratedcircuitswereinventedin1958,thefirstcomputerstomakeextensiveuseofthemwerenotavailableuntil1964.Inthatyear,IBMintroducedalineofmainframecomputerscalledtheSystem/360.Thecomputersinthislinebecamethemostwidelyusedthird-generationmachines.ThereweremanymodelsintheSystem/360line,rangingfromsmall,relativelyslow,andinexpensiveones,tolarge,veryfast,andcostlymodels.Allmodels,however,werecompatiblesothatprogramswrittenforonemodelcouldbeusedonanother.Thisfeatureofcompatibilityacrossmanycomputersinalinewasadoptedbyothermanufacturersofthird-generationcomputers.雖然集成電路發(fā)明于1958年,但是直到1964年才出現(xiàn)了第一臺(tái)廣泛使用IC的計(jì)算機(jī)。那一年，IBM推出了稱為System/360的大型計(jì)算機(jī)系列。這一系列的計(jì)算機(jī)成為使用最廣泛的第三代計(jì)算機(jī)。在System/360系列中有許多機(jī)型,從小型的、相對(duì)較慢的且價(jià)格低廉的機(jī)型，到大型的、非?？斓那覂r(jià)格昂貴的機(jī)型。然而,所有的機(jī)型都是兼容的，以便在一個(gè)機(jī)型上編寫的程序可以用于另一個(gè)機(jī)型。這個(gè)在許多計(jì)算機(jī)系列間兼容的特征被其他第三代計(jì)算機(jī)制造商所采用。

1.2.3Third-GenerationComputers:1964～1970Thethirdcomputergenerationwasalsothetimewhenminicomputersbecamewidespread.ThemostpopularmodelwasthePDP-8,manufacturedbyDEC.Othercompanies,includingDataGeneralCorporationandHewlett-PackardCompany,introducedminicomputersduringthethirdgeneration.計(jì)算機(jī)的第三代也是小型計(jì)算機(jī)普及的時(shí)代。最流行的小型機(jī)是由DEC制造的PDP-8。其他公司,包括數(shù)據(jù)通用公司和惠普(Hewlett-Packard)公司,在第三代期間開發(fā)了小型計(jì)算機(jī)。1.2ComputerGenerations1.2.3Third-GenerationComputers:1964～1970Theprincipalsoftwaredevelopmentduringthethirdcomputergenerationwastheincreasedsophisticationofoperatingsystems.Althoughsimpleoperatingsystemsweredevelopedforfirst-andsecond-generationcomputers,manyofthefeaturesofmodernoperatingsystemsfirstappearedduringthethirdgeneration.Theseincludemultiprogramming,virtualmemory,andtime-sharing.Thefirstoperatingsystemsweremainlybatchsystems,butduringthethirdgeneration,interactivesystems,especiallyonminicomputers,becamecommon.TheBASICprogramminglanguagewasdesignedin1964andbecamepopularduringthethirdcomputergenerationbecauseofitsinteractivenature.在第三代計(jì)算機(jī)期間，軟件的主要發(fā)展是操作系統(tǒng)的復(fù)雜化程度提高。雖然為第一代和第二代計(jì)算機(jī)開發(fā)了簡(jiǎn)單的操作系統(tǒng),許多現(xiàn)代操作系統(tǒng)的特征首先在第三代期間出現(xiàn)。這些特征包括多道程序設(shè)計(jì)、虛擬存儲(chǔ)和分時(shí)技術(shù)。第一代操作系統(tǒng)主要是批處理系統(tǒng),但是在第三代期間，交互式系統(tǒng)開始普及，尤其是在小型計(jì)算機(jī)上。BASIC語言發(fā)明于1964年，并由于其交互式特征而在第三代計(jì)算機(jī)期間大為流行。1.2ComputerGenerations1.2.4Fourth-GenerationComputers:1971～?Thefourthgenerationofcomputersismoredifficulttodefinethantheotherthreegenerations.Thisgenerationischaracterizedbymoreandmoretransistorsbeingcontainedonasiliconchip.FirsttherewasLargeScaleIntegration(LSI),withhundredsandthousandsoftransistorsperchip,thencameVeryLargeScaleIntegration(VLSI),withtensofthousandsandhundredsofthousandsoftransistors.Thetrendcontinuestoday.第四代計(jì)算機(jī)比其他三代更難以定義。這一代計(jì)算機(jī)的特征是一個(gè)芯片上包含越來越多的晶體管。首先，出現(xiàn)了一個(gè)芯片上具有數(shù)百和數(shù)千個(gè)晶體管的大規(guī)模集成電路(LSI)，接著出現(xiàn)了一個(gè)芯片上具有數(shù)萬和數(shù)十萬個(gè)晶體管的超大規(guī)模集成電路(VLSI)。這個(gè)趨勢(shì)在今天仍在持續(xù)。1.2ComputerGenerations1.2.4Fourth-GenerationComputers:1971～?Althoughnoteveryoneagreesthatthereisafourthcomputergeneration,thosethatdofeelthatitbeganin1971,whenIBMintroduceditssuccessorstotheSystem/360lineofcomputers.ThesemainframecomputerswerecalledtheSystem/370,andcurrent-modelIBMcomputers,althoughnotcalledSystem/370s,evolveddirectlyfromthesecomputers.雖然并不是每個(gè)人都同意存在一個(gè)第四代,那些認(rèn)為存在的覺得它開始于1971年，其時(shí)IBM開發(fā)了System/360系列計(jì)算機(jī)的下一系列產(chǎn)品。這些大型計(jì)算機(jī)稱為System/370,當(dāng)前的IBM計(jì)算機(jī)雖然不叫做System/370，但都是從這些計(jì)算機(jī)直接發(fā)展而來的。Minicomputersalsoproliferatedduringthefourthcomputergeneration.ThemostpopularlinesweretheDECPDP-11modelsandtheDECVAX,bothofwhichareavailableinvariousmodelstoday.小型計(jì)算機(jī)也在第四代期間迅速增長。最流行的系列是DEC公司的PDP-11機(jī)和DEC的VAX機(jī),二者在今天的各種機(jī)型中仍然有效。

1.2ComputerGenerations1.2ComputerGenerations1.2.4Fourth-GenerationComputers:1971～?Supercomputersfirstbecameprominentinthefourthgeneration.Althoughmanycompanies,includingIBMandCDC,developedhigh-speedcomputersforscientificwork,itwasnotuntilCrayResearch,Inc.,introducedtheCray1in1975thatsupercomputersbecamesignificant.Today,supercomputersareanimportantcomputerclassification.

超級(jí)計(jì)算機(jī)首先在第四代中突起。雖然包括IBM和CDC(控制數(shù)據(jù)公司)在內(nèi)的許多公司都為科學(xué)工作開發(fā)了高速計(jì)算機(jī),但是直到1975年Cray研究有限公司推出了Cray1，超級(jí)計(jì)算機(jī)才變得有意義。今天，超級(jí)計(jì)算機(jī)是重要的計(jì)算機(jī)分類。1.2ComputerGenerations1.2.4Fourth-GenerationComputers:1971～?Perhapsthemostimportanttrendthatbeganinthefourthgenerationistheproliferationofmicrocomputers.Asmoreandmoretransistorswereputonsiliconchips,iteventuallybecamepossibletoputanentirecomputerprocessor,calledamicroprocessor,onachip.Thefirstcomputertousemicroprocessorsbecameavailableinthemid-1970s.ThefirstmicrocomputerdesignedforpersonalusewastheAltair,whichwassoldin1975.ThefirstApplecomputer,marketedwiththeIBMPCin1981.Today,microcomputersfaroutnumberallothertypesofcomputerscombined.也許在第四代計(jì)算機(jī)開始的最重要趨勢(shì)是微型計(jì)算機(jī)的增長。隨著越來越多的晶體管被集成到硅芯片上,將一整個(gè)計(jì)算機(jī)處理器（稱為微處理器）放在一個(gè)芯片上終于成為可能。使用微處理器的第一部計(jì)算機(jī)出現(xiàn)于1970年代。第一部專為個(gè)人使用設(shè)計(jì)的微型計(jì)算機(jī)是Altair,它于1975進(jìn)入市場(chǎng)。第一部蘋果計(jì)算機(jī)在1981年與IBM個(gè)人計(jì)算機(jī)一起在市場(chǎng)上銷售。今天，微型計(jì)算機(jī)數(shù)目遠(yuǎn)遠(yuǎn)超過其他所有類型計(jì)算機(jī)的總和。1.2ComputerGenerations1.2.4Fourth-GenerationComputers:1971～?Softwaredevelopmentduringthefourthcomputergenerationstartedoffwithlittlechangefromthethirdgeneration.Operatingsystemsweregraduallyimproved,andnewlanguagesweredesigned.Databasesoftwarebecamewidelyusedduringthistime.Themostimportanttrend,however,resultedfromthemicrocomputerrevolution.Packagedsoftwarebecamewidelyavailableformicrocomputerssothattodaymostsoftwareispurchased,notdevelopedfromscratch.在計(jì)算機(jī)的第四代期間，軟件的發(fā)展開始與第三代有所不同。操作系統(tǒng)在逐漸地改進(jìn)，而新的語言被發(fā)明。期間數(shù)據(jù)庫軟件被廣泛使用。然而，最重要的趨勢(shì)起因于微型計(jì)算機(jī)革命。用于微型計(jì)算機(jī)的軟件包隨處可得，因此今天大多數(shù)的軟件可以購得,而不需從頭開始開發(fā)。1.2.5GenerationlessComputersWemayhavedefinedourlastgenerationofcomputersandbeguntheeraofgenerationlesscomputers.Eventhoughcomputermanufacturerstalkof“fifth”and“sixth”-generationcomputers,thistalkismoreamarketingplaythanareflectionofreality.我們可能已經(jīng)定義了我們最新一代計(jì)算機(jī)而且開始了計(jì)算機(jī)的無代時(shí)代。即使計(jì)算機(jī)制造商談到“第五”和“第六”代計(jì)算機(jī),這些說法更多是市場(chǎng)行為，而不是真實(shí)的反映。Advocatesoftheconceptofgenerationl