《计算机专业英语》课件第2章

TheEvolutionofComputers

1Modernelectroniccomputersdidn’tappearuntilthe1940’s.ResearchworkersinAmericaproducedaworkingcomputerin1946.Thefirstmodelswereverybulkybecausetheydependedonvacuumtubessimilartothoseyoumayhaveseeninoldradiosets.Latermachinesusedtransistorsandatpresentweuseintegratedcircuitswhichtakeupverylittle

space.

Now,let’sgetaclearerpictureofthedevelopmentofcomputers.

1.Firstgenerationcomputers

Thefirstgenerationofcomputerswereusedfrom1946to1959.TheywerecharacterizedbythemostprominentfeatureoftheENIACvacuumtubes,andwerelarge,costly,expensivetopowerandoftenunreliable.2Moreover,thevacuumtubeswerefairlylarge,andtheygeneratedsomuchheatthatspecialairconditioninghadtobeinstalledtocoolthem.

2.Secondgenerationcomputers

Thesecondgenerationofcomputersspannedtheyearsfrom1959to1964.Themostnotablechangewasthattransistorsreplacedvacuumtubes.3Thetransistorallowedthedevelopmentofmorepowerful,morereliableandlessexpensivecomputersthatwouldoccupylessspaceandgiveofflessheatthandidcomputersusingvacuumtubes.

Inaddition,thesecondgenerationcomputersweregivenauxiliarystorage,sometimescalledexternalorsecondarystorage.Datawerestoredoutsidethecomputeroneithermagnetictapesormagneticdisks.Usingmagnetictapesormagneticdisksforinputandoutputoperationsincreasedthespeedofthecomputer.

3.Third-generationcomputers

Thethird-generationcomputerslastedfrom1964to1971.4Thethird-generationismarkedchieflybythedevelopmentofintegratedcircuits,whichreplacedtransistors.Withintegratedcircuits,hundredsofelectricalcomponentscouldbeincludedononesiliconchiplessthanone-eighth-inchsquare.Therefore,thecomputersbecameevensmallerwhiletheirmemorycapacitiesbecamelarger.

Thethird-generationcomputersworkedsoquicklythattheyprovidedthecapabilitytorunmorethanoneprogramconcurrently(multiprogramming).Forexample,atanygiventimethecomputermightbeprintingpayrollchecks,acceptingorders,andtestingprograms.

4.Fourth-generationcomputers

From1971tothepresent,wehavethefourth-generationcomputers.Mostcomputervendorsclassifytheircomputersasbeingfourth-generationcomputers,andafewevencalltheirs“fifth-generation”.Thefirstthreegenerationswerecharacterizedbysignificanttechnologicalbreakthroughsinelectronicsfirsttheuseofvacuumtubes,thentransistors,andthenintegratedcircuits.

Chipcircuitryhasbecomeincreasinglyminiaturizedinfourthgenerationcomputers.Largescaleintegration(LSI)circuits,featuringthousandsofelectroniccomponentsonasinglesiliconchip,becamecommonduringthe1970s.

Microprocessorchipscanmanagethefunctionsofthecomputer,performcalculations,andcontrolotherdevicesjustlikelargecomputers.

5Themodernmicrocomputerconsistsofamicroprocessorandotherdenselypackedchipsusedforstorageandinput/outputoperations,allofwhicharemorepowerfulthanlargecomputersofearliergenerations.

Now,LSIhasalreadyprogressedintoVLSI(VeryLargeScaleIntegration),whichmeansevenmorecapabilitiesinevensmallerpackages.NewWords

bulkyadj.大的,容量大的,体积大的prominentadj.突出的;显著的,卓越的costly

adj.贵重的,昂贵的unreliableadj.不可靠的span

v.横越;n.跨度,跨距,范围generatevt.产生,发生componentn.成分;adj.组成的,构成的notable

adj.值得注意的,显著的,著名的concurrentlyadv.并发地,同时发生地payrollcheckn.工资单ordern.定单,次序,顺序,命令;vt.命令,订购,定制vendorn.销售商,卖主breakthroughn.突破largescaleadj.大规模的,大范围的,大批的integrationn.集成(化),整体化,综合denselyadv.密集地,浓密地,浓厚地miniaturizevt.使小型化PhrasesandExpressions

auxiliarystorage辅助存储器(或称外部存储器)magneticdisk磁盘memorycapacity存储器容量classify…as分成(为)……类vacuumtube真空管,电子管siliconchip硅片chipcircuitry芯片电路multiprogramming多道程序设计TheExplanationofDifficultStatements

1.Modernelectroniccomputersdidn’tappearuntilthe1940’s.

分析:not…until:直到……才……,比如下例:

Hedidn’tbegintodohishomeworkuntilhismotherreturned他直到他妈妈回来才开始做作业。

句意:现代的电子计算机直到20世纪40年代才问世。

2.Moreover,thevacuumtubeswerefairlylarge,andthey

generatedsomuchheatthatspecialair-conditioninghadtobe

installedtocoolthem.

分析:so…that…:如此……以致于……，that后面接结果状语从句。再如:

ThecaseissoheavythatIcan’tliftit.

这个箱子这么重,我拎不起来。

句意:此外,体积庞大的真空管产生很大的热量,必须安装特殊的空调来降温。

3.Thetransistorallowedthedevelopmentofmorepowerful,

morereliableandlessexpensivecomputersthatwould

occupylessspaceandgiveofflessheatthandidcomputers

usingvacuumtubes.

分析:句中hatwouldoccupylessspaceandgiveofflessheat

thandidcomputersusingvacuumtubes是computers的定语从句,进一步说明computers的性能。

句意:使用晶体管可以制造出功能更强、性能更可靠、价格更便宜的计算机,它与真空管计算机相比体积小,功耗也小。

4.Thethirdgenerationismarkedchieflybythe

developmentofintegratedcircuits,whichreplaced

transistors.

分析:句中whichreplacedtransistors为integratedcircuits的定语从句。

句意:第三代计算机以集成电路取代晶体管为主要标志。

5.Themodernmicrocomputerconsistsofamicroprocessor

andotherdenselypackedchipsusedforstorageand

input/outputoperations,allofwhicharemorepowerfulthan

largecomputersofearliergenerations.

分析:consistsof:由……组成。句中usedforstorageandinput/outputoperations是denselypackedchips的定语。而句中allofwhicharemorepowerfulthanlargecomputersofearliergenerations是Themodernmicrocomputer的定语从句。句意:微处理器和其它用于存储和输入/输出操作的集成芯片相结合,构成了现代微型计算机。微型计算机比前几代大型计算机的功能更为强大。ExercisesⅠ.Choosethebestanswers:(1)Thefourthgenerationofcomputers______________.

A.usetransistors

B.useLSI-circuits

C.arecharacterizedbysignificanttechnological

breakthroughsinartificialintelligence

D.usevacuumtubes(2)Mostmicrocomputertodayarebasedonadesigndevelopedby_____________.

A.Apple

B.NEC

C.IBM

D.Compaq(3)Whetheracomputerispowerfuldependsonits______________.

A.applicationsoftwareB.memorycapacity

C.operationalsoftwareD.CPU’sclockspeed(4)Aseriesofinstructionswrittenforacomputertoperformspecifictasksiscalled______________.

A.softwareB.aprogram

C.afileD.thedataⅡ.TranslatethefollowingwordsandexpressionsintoEnglish:(1)电子管(2)晶体管(3)磁带机(4)磁盘机(5)微处理器(6)大规模集成电路Ⅲ.TranslatethefollowingsentencesintoEnglish,using“anadjectiveclause”ineachsentence:(1)这是我祖父经常晒太阳的花园。(2)这家汽车旅馆不是我们在找的那类旅馆。(3)我们需要一种仪器,它的型号一定要小。(4)我看了好几座房子,大多不很合适。(5)此事正在调查,调查结果不久就会公布。ReadingMaterials

Memory(Ⅰ)

Themicrocomputer’smemoryconsistsofmainmemoryandsecondarystorage.

MainMemory

Themainmemoryofmostcomputersiscomposedofrandomaccessmemory(RAM).Theprogrammer(throughaprogram,ofcourse)canreadtoorwritefromtheRAM.InputdatacanbestoredinRAM,overwritinganddestroyinggtheexistingcontentsoftheselectedbytesorwords.Oncethedataarein,theycanbereadandmanipulatedbytheprocessor,andresultscanbewrittentoothermemorylocations.Finally,thecontentscanbesenttoanoutputdevice.Whenaprogramisfinished,anewprogramcanbecopiedintotheRAM,againoverwritingtheoldoneintheprocess.ThecontentsofRAMareeasytochange.

Usually,RAM’sflexibilityisanadvantage,butoccasionallyitcanbeaproblem.Consider,forexample,theautomatictellerterminalusedinmanybanks.Theyarecontrolledbysmallcomputerwhich,inturn,arecontrolledbyprograms.Acleverprogrammermightbeabletomodifyoneofthoseprogramstogivefreeaccesstocertainaccounts.Needlesstosay,thebankcouldnottoleratesuchchanges.Thebankneedsaprogramthatcanbereadbytheprocessor,butnotmodified.Suchprogramsarestoredinreadonlymemory(ROM).AnothergoodexampleofaROMbasedprogramistheBIOSprogramfoundinmanymicrocomputers.Asthenameimplied,ROMis“permanent”memorythatcanberead,butnotwritten.NewWordsandExpressions

consistof与“becomposedof”意思相似,由……组成word

n.字overwritev.覆盖automatictellerterminal自动终端(出纳)机flexibilityadj.灵活性toleratev.准许ExercisesChoosethebestanswer:(1)Asmallsectionofthemainmemory,whichisusedforholding

permanentlystoreddataandonlyallowsreadaccessbythe

CPUiscalled______________.

A.RAMB.ROM

C.DOSD.Diskette(2)ROMandRAMaretheacronymsfor______________

respectively.

A.randomaccessmemoryandreadonlymemory

B.readonlymemoryandrandomaccessmemory

C.registerandreadonlymemory

D.registerandrandomaccessmemory

(3)______________doesn’tloseitscontentswhenyouturn

offthecomputer.

A.RAM

B.ROM

C.TheCPU

D.Cache(4)Eachbasicphysicalstorageunitinmainmemoryisassigneda

unique______________,calleditsaddress.

A.number

B.byte

C.capacity

D.bitMemory(Ⅱ)

SecondaryStorage

Mainmemoryonthecomputerisusedtostoreinstructionsanddatatemporarilywhiletheinstructionsarebeingexecutedanddataarebeingprocessed.Inmostapplications,however,theseinstructionsanddatamustbestoredelsewherewhentheyarenotbeingusedbecausemainmemoryisnotlargeenoughtostoretheinstructionsanddataforallapplicationsatonetime.Secondarystorageunitsareusedinmainmemoryofthecomputer.

Oneadvantageofacomputeristhatoncedatahavebeenentered,theycanbestoredonthemachineandaccessedrepeatedly.Generatingaddresslabelsforamagazineisagoodexample.Insteadofretypingallthelabelinformationforeachedition,subscriberdataneedonlybeinputonce,stored,andthenaccessedfromstoragewhenevernecessary.Programsprovideanotherexample.Likethesubscriberdata,theyarestoredonthecomputerandaccessedasneede