微机发展简史外文翻译.docx
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微机发展简史外文翻译
附录A:
英文资料
ProgressinComputers
Thefirststoredprogramcomputersbegantoworkaround1950.TheonewebuiltinCambridge,theEDSACwasfirstusedinthesummerof1949.
Theseearlyexperimentalcomputerswerebuiltbypeoplelikemyselfwithvaryingbackgrounds.Weallhadextensiveexperienceinelectronicengineeringandwereconfidentthatthatexperiencewouldstandusingoodstead.Thisprovedtrue,althoughwehadsomenewthingstolearn.Themostimportantofthesewasthattransientsmustbetreatedcorrectly;whatwouldcauseaharmlessflashonthescreenofatelevisionsetcouldleadtoaseriouserrorinacomputer.
Asfarascomputingcircuitswereconcerned,wefoundourselveswithanembarassderichess.Forexample,wecouldusevacuumtubediodesforgatesaswedidintheEDSACorpentodeswithcontrolsignalsonbothgrids,asystemwidelyusedelsewhere.Thissortofchoicepersistedandthetermfamiliesoflogiccameintouse.ThosewhohaveworkedinthecomputerfieldwillrememberTTL,ECLandCMOS.Ofthese,CMOShasnowbecomedominant.
Inthoseearlyyears,theIEEwasstilldominatedbypowerengineeringandwehadtofightanumberofmajorbattlesinordertogetradioengineeringalongwiththerapidlydevelopingsubjectofelectronics.dubbedintheIEElightcurrentelectricalengineering.properlyrecognisedasanactivityinitsownright.Irememberthatwehadsomedifficultyinorganisingaconferencebecausethepowerengineers’waysofdoingthingswerenotourways.AminorsourceofirritationwasthatallIEEpublishedpaperswereexpectedtostartwithalengthystatementofearlierpractice,somethingdifficulttodowhentherewasnoearlierpractice
Consolidationinthe1960s
Bythelate50sorearly1960s,theheroicpioneeringstagewasoverandthecomputerfieldwasstartingupinrealearnest.Thenumberofcomputersintheworldhadincreasedandtheyweremuchmorereliablethantheveryearlyones.Tothoseyearswecanascribethefirststepsinhighlevellanguagesandthefirstoperatingsystems.Experimentaltime-sharingwasbeginning,andultimatelycomputergraphicswastocomealong.
Aboveall,transistorsbegantoreplacevacuumtubes.Thischangepresentedaformidablechallengetotheengineersoftheday.Theyhadtoforgetwhattheyknewaboutcircuitsandstartagain.Itcanonlybesaidthattheymeasuredupsuperblywelltothechallengeandthatthechangecouldnothavegonemoresmoothly.
Soonitwasfoundpossibletoputmorethanonetransistoronthesamebitofsilicon,andthiswasthebeginningofintegratedcircuits.Astimewenton,asufficientlevelofintegrationwasreachedforonechiptoaccommodateenoughtransistorsforasmallnumberofgatesorflipflops.Thisledtoarangeofchipsknownasthe7400series.Thegatesandflipflopswereindependentofoneanotherandeachhaditsownpins.Theycouldbeconnectedbyoff-chipwiringtomakeacomputeroranythingelse.
Thesechipsmadeanewkindofcomputerpossible.Itwascalledaminicomputer.Itwassomethinglessthatamainframe,butstillverypowerful,andmuchmoreaffordable.Insteadofhavingoneexpensivemainframeforthewholeorganisation,abusinessorauniversitywasabletohaveaminicomputerforeachmajordepartment.
Beforelongminicomputersbegantospreadandbecomemorepowerful.Theworldwashungryforcomputingpowerandithadbeenveryfrustratingforindustrynottobeabletosupplyitonthescalerequiredandatareasonablecost.Minicomputerstransformedthesituation.
Thefallinthecostofcomputingdidnotstartwiththeminicomputer;ithadalwaysbeenthatway.ThiswaswhatImeantwhenIreferredinmyabstracttoinflationinthecomputerindustry‘goingtheotherway’.Astimegoesonpeoplegetmorefortheirmoney,notless.
ResearchinComputerHardware.
ThetimethatIamdescribingwasawonderfuloneforresearchincomputerhardware.Theuserofthe7400seriescouldworkatthegateandflip-floplevelandyettheoveralllevelofintegrationwassufficienttogiveadegreeofreliabilityfarabovethatofdiscreettransistors.Theresearcher,inauniversityorelsewhere,couldbuildanydigitaldevicethatafertileimaginationcouldconjureup.IntheComputerLaboratorywebuilttheCambridgeCAP,afull-scaleminicomputerwithfancycapabilitylogic.
The7400serieswasstillgoingstronginthemid1970sandwasusedfortheCambridgeRing,apioneeringwide-bandlocalareanetwork.PublicationofthedesignstudyfortheRingcamejustbeforetheannouncementoftheEthernet.Untilthesetwosystemsappeared,usershadmostlybeencontentwithteletype-basedlocalareanetworks.
Ringsneedhighreliabilitybecause,asthepulsesgorepeatedlyroundthering,theymustbecontinuallyamplifiedandregenerated.Itwasthehighreliabilityprovidedbythe7400series