(ERPMRP管理)外文翻譯computerprogram英文

ComputerProgramIntroductionComputerProgram,setofinstructionsthatdirectsacomputertoperformsomeprocessingfunctionorcombinationoffunctions.Fortheinstructionstobecarriedout,acomputermustexecuteaprogram,thatis,thecomputerreadstheprogram,andthenfollowthestepsencodedintheprograminapreciseorderuntilcompletion.Aprogramcanbeexecutedmanydifferenttimes,witheachexecutionyieldingapotentiallydifferentresultdependingupontheoptionsanddatathattheusergivesthecomputer.Programsfallintotwomajorclasses:applicationprogramsandoperatingsystems.Anapplicationprogramisonethatcarriesoutsomefunctiondirectlyforauser,suchaswordprocessingorgame-playing.Anoperatingsystemisaprogramthatmanagesthecomputerandthevariousresourcesanddevicesconnectedtoit,suchasRAM,harddrives,monitors,keyboards,printers,andmodems,sothattheymaybeusedbyotherprograms.ExamplesofoperatingsystemsareDOS,Windows95,OS\2,andUNIX.ProgramDevelopmentSoftwaredesignerscreatenewprogramsbyusingspecialapplicationsprograms,oftencalledutilityprogramsdevelopmentprograms.Aprogrammerusesanothertypeofprogramcalledatexteditortowritethenewprograminaspecialnotationcalledaprogramminglanguage.Withthetexteditor,theprogrammercreatesatextfile,whichisanorderedlistofinstructions,alsocalledtheprogramsourcefile.Theindividualinstructionsthatmakeuptheprogramsourcefilearecalledsourcecode.Atthispoint,aspecialapplicationsprogramtranslatesthesourcecodeintomachinelanguage,orobjectcode—aformatthattheoperatingsystemwillrecognizeasaproperprogramandbeabletoexecute.Threetypesofapplicationsprogramstranslatefromsourcecodetoobjectcode:compilers,interpreters,andassemblers.threeoperatedifferentlyandondifferenttypesofprogramminglanguages,buttheyservethesamepurposeoftranslatingfromaprogramminglanguageintomachinelanguage.Acompilertranslatestextfileswritteninahigh-levelprogramminglanguage--suchasFORTRAN,C,orPascal—fromthesourcecodetotheobjectcodeallatonce.ThisdifferstheapproachtakenbyinterpretedlanguagessuchasBASIC,APLandLISP,inwhichaprogramistranslatedintoobjectcodestatementbystatementaseachinstructionisexecuted.Theadvantagetointerpretedlanguagesisthattheycanbeginexecutingtheprogramimmediatelyinsteadofhavingtowaitforallofthesourcecodetobecompiled.Changescanalsobemadetotheprogramfairlyquicklywithouthavingtowaitforittobecompiledagain.Thedisadvantageofinterpretedlanguagesisthattheyareslowtoexecute,sincetheentireprogrammustbetranslatedoneinstructionatatime,eachtimetheprogramisrun.Ontheotherhand,compiledlanguagesarecompiledonlyonceandthuscanbeexecutedbythecomputermuchmorequicklythaninterpretedlanguages.Forthisreason,compiledlanguagesaremorecommonandarealmostalwaysusedinprofessionalandscientificapplications.Anothertypeoftranslatoristheassembler,whichisusedforprogramsorpartsofprogramswritteninassemblylanguage.Assemblylanguageisanotherprogramminglanguage,butitismuchmoresimilartomachinelanguagethanothertypesofhigh-levellanguages.Inassemblylanguage,asinglestatementcanusuallybetranslatedintoasingleinstructionofmachinelanguage.Today,assemblylanguageisrarelyusedtowriteentireprogram,butisinsteadmostoftenusedwhentheprogrammerneedstodirectlycontrolsomeaspectofthecomputer’sfunction.Programsareoftenwrittenasasetofsmallerpieces,witheachpiecerepresentingsomeaspectoftheoverallapplicationprogram.Aftereachpiecehasbeencompiledseparately,aprogramcalledalinkercombinesallofthetranslatedpiecesintoasingleexecutableprogram.Programsseldomworkcorrectlythefirsttime,soaprogramcalledadebuggerisoftenusedtohelpfindproblemscalledbugs.Debuggingprogramsusuallydetectaneventintheexecutingprogramandpointtheprogrammerbacktotheoriginoftheeventintheprogramcode.Recentprogrammingsystems,suchasJava,useacombinationofapproachestocreateandexecuteprograms.AcompilertakesJavasourceprogramandtranslatesitintoanintermediateform.SuchintermediateprogramsarethentransferredovertheInternetintocomputerswhereaninterpreterprogramthenexecutestheintermediateformasanapplicationprogram.ProgramElementsMostprogramsarebuiltfromjustafewkindsofstepsthatarerepeatedmanytimesindifferentcontextsandindifferentcombinationsthroughouttheprogram.Themostcommonstepperformssomecomputation,andthenproceedstothenextintheprogram,intheorderspecifiedbytheprogrammer.Programsoftenneedtorepeatashortseriesofstepsmanytimes,forinstanceinlookingthroughalistofgamescoresandfindingthehighestscore.Suchrepetitivesequencesofcodearecalledloops.Oneofthecapabilitiesthatmakescomputersousefulistheirabilitytomakeconditionaldecisionsandperformdifferentinstructionsbasedonthevaluesofdatabeingprocessed.If-then-elsestatementsimplementthisfunctionbytestingsomepieceofdataandthenselectingoneoftwosequencesinstructionsonthebasisoftheresult.Oneoftheinstructionsinthesealternativesmaybeagotostatementthatdirectsthecomputertoselectitsnextinstructionfromadifferentoftheprogram.Forexample,aprogrammightcomparetwonumbersandbranchtoadifferentpartoftheprogramdependingontheresultofthecomparison:IfxisgreaterthanyThenGotoinstruction#10ElsecontinueProgramoftenuseaspecificsequenceofstepsmorethanonce.Suchasequenceofstepscanbegroupedtogetherintoasubroutine,whichcanthenbecalled,oraccessed,asneededindifferentpartsofthemainprogram.Eachtimeasubroutineiscalled,thecomputerrememberswhereitwasintheprogramwhenthecallwasmade,sothatitcanreturnthereuponcompletionofthesubroutine,allowingaverygeneralpieceofcodetobewrittenonceandusedinmultipleways.Mostprogramsuseseveralvarietiesofsubroutines.Themostcommonofthesearefunctions,procedures,libraryroutines,systemroutines,anddevicedrivers.Functionsareshortsubroutinesthatcomputesomevalue,suchascomputationsofangles,whichthecomputercannotcomputewithasingleinstruction.Proceduresperformcomplexfunction,suchassortingasetofnames.Libraryroutinesaresubroutinesthatarewrittenforusebymanydifferentprograms.Systemroutinesaresimilartolibraryroutinesbutareactuallyfoundinoperatingsystem.Theyprovidesomeservicefortheapplicationprograms,suchasprintingalineoftext.Devicedriverssystemroutinesthatareaddedtoanoperatingsystemtoallowthecomputertocommunicatewithanewdevice,suchasascanner,modem,orprinter.Devicedriversoftenhavefeaturesthatcanbeexecuteddirectlyasapplicationsprograms.Thisallowstheusertodirectlycontrolthedevice,whichisusefulif,forinstance,acolorprinterneedstoberealignedtoattainbestprintingqualityafterchanginganinkcartridge.ProgramFunctionModerncomputersusuallystoreprogramsonsomeformofmagneticstoragemediathatcanbeaccessedrandomlybythecomputer,suchastheharddrivediskpermanentlylocatedinthecomputer,oraportablefloppydisk.Additionalinformationonsuchdisks,calleddirectories,indicatethenamesofthevariousprogrambeginsonthediskmedia.Whenauserdirectsthecomputertoexecuteaparticularapplicationprogram,operatingsystemlooksthroughthesedirectories,locatestheprogram,andreadsacopyintoRAM.TheoperatingsystemdirectstheCPUtostartexecutingtheinstructionsatthebeginningoftheprogram.InstructionsatthebeginningoftheprogrampreparethecomputertoprocessinformationbylocatingfreememorylocationsinRAMtoholdworkingdata,retrievingcopiesofthestandardoptionsanddefaultstheuserhasindicatedfromadisk,anddrawinginitialdisplaysonthemonitor.Theapplicationprogramrequestscopyofanyinformationuserentersbymakingacalltoasystemroutine.Theoperatingsystemconvertsanydatasoenteredintoastandardinternalform.Theapplicationthenusesthisinformationtodecidewhattodonextforexample,performsomedesiredprocessingfunctionsuchasreformattingapageoftext,orobtainsomeadditionalinformationfromanotherfileonadisk.Ineithercase,callstoothersystemroutinesareusedtoactuallycarryoutthedisplayoftheresultsortheaccessingofthefilefromthedisk.Whentheapplicationreachescompletionorispromptedtoquit,itmakesfurthersystemcallstomakesurethatalldatathatneedstobesavedhasbeenwrittenbacktodisk.Itthenmakesafinalsystemcalltotheoperatingsystemindicatingthatitisfinished.TheoperatingsystemthenfreesuptheRAMandanydevicethattheapplicationwasusingandawaitsacommandfromtheusertostartanotherprogram.HistoryPeoplehavebeenstoringsequencesofinstructionsintheformofaprogramforseveralcenturies.Musicboxesofthe18thcenturyandplayerpianosofthelate19th andearly20thcenturiesplayedmusicalprogramsstoredasseriesifmetalpins,orholesinpaper,witheachlinerepresentingwhenanotewastobeplayed,andthepinorholeindicatingwhatnotewastobeplayedatthattime.Moreelaboratecontrolofphysicaldevicesbecamecommonintheearly1800swithFrenchinventorJosephMarieJacquard’sinventionofthepunch-cardcontrolledweavingloom.Intheprocessofweavingaparticularpattern,variouspartsoftheloomhadtobemechanicallypositioned.Toautomatethisprocess,Jacquardusedasinglepapercardtorepresenteachpositioningoftheloom,withholeinthecardtoindicatewhichloomactionsshouldbedone.entiretapestrycouldbeencodedontoadeckofsuchcards,withthesamedeckyieldingthesametapestrydesigneachtimeitwasused.Programsofover24,000cardweredevelopedandused.The world’s first programmable machine wasdesignedalthoughneverfullybuiltbytheEnglishmathematicianandinventor,CharlesBabbage.Thismachine,calledtheAnalyticalEngine,usedpunchcardssimilartothoseusedintheJacquardloomtoselectthespecificarithmeticoperationtoapplyateachstep.Insertingadifferentsetcardschangedthecomputationsthemachineperformed.Thismachinehadcounterpartsforalmosteverythingfoundinmoderncomputers,althoughitwasmechanicalratherthanelectrical.ConstructionoftheAnalyticalEnginewasnevercompletedbecausethetechnologyrequiredtobuilditdidnotexistatthetime.ThefirstcarddeckprogramsfortheAnalyticalEngineweredevelopedbyBritishmathematicianCountessAugustaLovelace,daughterofthepoetLordByron.Forthisreasonisrecognizedasthefirstprogrammer.ThemodernconceptofaninternallystoredcomputerprogramwasfirstproposedbyHungarian-AmericanmathematicianJohnvonNeumannin1945.VonNeumann’sideawastousethecomputer’smemorytostoretheprogramaswellasthedata.Inthisway,programscanbeviewedasdataandcanbeprocessedlikebyotherprograms.Thisideagreatlysimplifiestheroleofprogramstorageandexecutionincomputers.TheFutureThefieldofcomputersciencehasgrownrapidlysincethe1950sduetotheincreaseintheiruse.Computerprogramshaveundergonemanychangesduringthistimeinresponsetouserneedandadvancesintechnology.Newerideasincomputingsuchparallelcomputing,distributedcomputing,andartificialintelligence,haveradicallyalteredthetraditionalconceptsthatoncedeterminedprogramformandfunction.Computerscientistsworkinginthefieldofparallelcomputing,inwhichmultipleCPUscooperateonthesameproblematthetime,haveintroducedanumberofnewprogrammodels.Inparallelcomputingpartsofaproblemareworkedonsimultaneouslybydifferentprocessors,andthisspeedsupthesolutionoftheproblem.Manychallengesfacescientistsandengineerswhodesignprogramsforparallelprocessingcomputers,becauseoftheextremecomplexityofthesystemsandthedifficultyinvolvedinmakingthemoperateaseffectivelyaspossible.AnothertypeofparallelcomputingcalleddistributedcomputingusesCPUsfrommanyinterconnectedcomputerstosolveproblems.OftenthecomputersusedtoprocessinformationinadistributedcomputingapplicationareconnectedovertheInternet.Internetapplicationsarebecomingaparticularlyusefulformofdistributedcomputing,especiallywithprogramminglanguagessuchasJava.Insuchapplications,auserlogsontoawebsiteanddownloadsaJavaprogramontotheircomputer.WhentheJavaprogramisrun,itcommunicate