外文翻译--工程中的单片机.doc

徐州工程学院毕业设计论文1附录附录1英文翻译MicroprocessorsinEngineersThedevelopmentofthemicroprocessorduringthe1970sbroughtaboutarevolutioninengineeringdesign.Theindustrialrevolutionattheturnofthenineteenthcenturyheraldedthedevelopmentofthemachineswhichcouldreplacephysicaldrudgerybymechanicalmeans.Apartfromafewexceptions,however,thesemachinesrequiredmanualsupervisionbecausetheproblemofcontrollingthismechanicalpowerwasnotatallstraightforward.Manytypesofautomaticcontrolsystemshaveappearedduringthetwentiethcentury,basedonelectronic,mechanical,hydraulicandfluidicprinciples.Ineachcasethedesigntechniqueshavebeensimilarbecauseeachcomponentofthesystemusuallycontributesasinglewelldefinedfunctiontothesystembehavior.Themicroprocessorrepresentsafundamentallydifferentapproachtothedesignofasystem.Itsphysicalformisquitesimpleandreliable,consistingofafewgeneralpurposeelementswhichcanbeprogrammedtomakethesystemfunctionasrequired.Itisthecontrollingprogramwhichmustbedesignedtogivethesystemtherequiredbehavior,andwhichwillcontaincomponentsandsubassembliesjustlikeanyotherkindofengineering.Theprogram,orsoftware,isjustoftheengineeredsystemasthephysicalhardware,butitismuchlesssusceptibletofailure,providedthatitisdesignedproperly.Theideaofprogrammedsystemsisnotnewelectroniccomputershavebeeninexistenceformanydecades.However,ithastakenthedevelopmentofthelargescaleintegratedcircuitthesiliconchiptoproducecomputerswhicharecheap,rugged,andreliableenoughtobeincorporatedintoengineeringdesignsascomponents.Thetechniquesofsoftwaredesignarewellknowntocomputerscientistsanditisnotsurprisingthattheprinciplesofgoodengineeringdesignandsoftwareengineeringareessentiallythoseofgoodengineeringdesign.Weshallseethatengineeringdesignusingsoftwareallowssystemstobedesignedmoreeasilythanusingmoreconventionaltechniques.Itisthecombinationofdevelopmentsinelectronicdevicetechnologywiththoseincomputertechnologywhichhasenabledthemicroprocessortobeproduced,andthesetechnologieshaveconvergedtoproducethemicroelectronicindustrywhichweseetoday.Morerecentdevelopmentsinintegratedcircuittechnologyhaveledtotheintroductionofmicroprocessorsmallcomputersfabricatedusingrelativelyfewintegratedcircuitcomponents.In徐州工程学院毕业设计论文2factanentiremicroprocessorcanbemadeasasinglechip.AttheheartofanycomputerisaCentralProcessingUnitorCPU,andthecorrespondingheartofthemicroprocessorisMPUMicroProcessorUnit,whichissimplyaCPUimplementedonasiliconchip.Itsprocessingpowerisgreaterthanthatofitsgiantpredecessorsandyetitischeapandrobustenoughtobetreatedassimplyanotherengineeringcomponent.Themicroprocessorwasconceivedasadevicewhichcouldbeprogrammedinaveryflexiblefashiontogivealmostanydesiredbehaviorbymeansofalistofelectronicinstructions.Usingamicroprocessorinvolvesprogrammingskillinproducingtheselistsofinstructionsaswellasmoreconventionalelectronicandmechanicaldesigntechniques.Asitsnamesuggests,themicroprocessorisorganizedinmuchthesamewayasaconventionalcomputerindeed,itmayberegardedasthenaturaloutcomeoftheevolutionofthecomputerfromitsearliestdays.SystemsUsingMicroprocessorsElectronicsystemsareusedforhandlinginformationinthemostgeneralsensethisinformationmaybetelephoneconversation,instrumentreadingoracompanysaccounts,butineachcasethesamemaintypesofoperationareinvolvedtheprocessing,storageandtransmissionofinformation.Inconventionalelectronicdesigntheseoperationsarecombinedatthefunctionlevelforexampleacounter,whetherelectronicormechanical,storesthecurrentcountandincrementsitbyoneasrequired.Asystemsuchasanelectronicclockwhichemployscountershasitsstorageandprocessingcapabilitiesspreadthroughoutthesystembecauseeachcounterisabletostoreandprocessnumbers.Presentdaymicroprocessorbasedsystemsdepartfromthisconventionalapproachbyseparatingthethreefunctionsofprocessing,storage,andtransmissionintodifferentsectionsofthesystem.ThispartitioningintothreemainfunctionswasdevisedbyVonNeumannduringthe1940s,andwasnotconceivedespeciallyformicrocomputers.Almosteverycomputerevermadehasbeendesignedwiththisstructure,anddespitetheenormousrangeintheirphysicalforms,theyhaveallbeenofessentiallythesamebasicdesign.Inamicroprocessorbasedsystemtheprocessingwillbeperformedinthemicroprocessoritself.Thestoragewillbebymeansofmemorycircuitsandthecommunicationofinformationintoandoutofthesystemwillbebymeansofspecialinput/outputI/Ocircuits.Itwouldbeimpossibletoidentifyaparticularpieceofhardwarewhichperformedthecountinginamicroprocessorbasedclockbecausethetimewouldbestoredinthememoryandincrementedatregularintervalsbythemicroprocessor.However,thesoftwarewhichdefinedthesystemsbehaviorwouldcontainsectionsthatperformedascounters.Theapparentlyratherabstract徐州工程学院毕业设计论文3approachtothearchitectureofthemicroprocessoranditsassociatedcircuitsallowsittobeveryflexibleinuse,sincethesystemisdefinedalmostentirelyinsoftware.Thedesignprocessislargelyoneofsoftwareengineering,andthesimilarproblemsofconstructionandmaintenancewhichoccurinconventionalengineeringareencounteredwhenproducingsoftware.Howthesethreesectionswithinamicrocomputerareconnectedintermsofthecommunicationofinformationwithinthemachine.Thesystemiscontrolledbythemicroprocessorwhichsupervisesthetransferofinformationbetweenitselfandthememoryandinput/outputsections.Theexternalconnectionsrelatetotherestthatis,thenoncomputerpartoftheengineeringsystem.Althoughonlyonestoragesectionhasbeenshowninthediagram,inpracticetwodistincttypesofmemoryRAMandROMareused.Ineachcase,thewordmemoryisratherinappropriatesinceacomputermemoryismorelikeafilingcabinetinconceptinformationisstoredinasetofnumberedboxesanditisreferencedbytheserialnumberoftheboxinquestion.MicrocomputersuseRAMRandomAccessMemoryintowhichdatacanbewrittenandfromwhichdatacanbereadagainwhenneeded.Thisdatacanbereadbackfromthememoryinanysequencedesired,andnotnecessarilythesameorderinwhichitwaswritten,hencetheexpressionrandomaccessmemory.AnothertypeofROMReadOnlyMemoryisusedtoholdfixedpatternsofinformationwhichcannotbeaffectedbythemicroprocessorthesepatternsarenotlostwhenpowerisremovedandarenormallyusedtoholdtheprogramwhichdefinesthebehaviorofamicroprocessorbasedsystem.ROMscanbereadlikeRAMS,butunlikeRAMStheycannotbeusedtostorevariableinformation.SomeROMshavetheirdatapatternsputinduringmanufacture,whileothersareprogrammablebytheuserbymeansofspecialequipmentandarecalledprogrammableROMs.ThewidelyusedprogrammableROMsareerasablebymeansofspecialultravioletlampsandarereferredtoasEPROMS,shortforErasableProgrammableReadOnlyMemories.Othernewtypesofdevicecanbeerasedelectricallywithouttheneedforultravioletlight,whicharecalledElectricallyErasableProgrammableReadOnlyMemories,EEPROMS.Themicroprocessorprocessesdataunderthecontroloftheprogram,controllingtheflowofinformationtoandfrommemoryandinput/outputdevices.Someinput/outputdevicesaregeneralpurposetypeswhileothersaredesignedforcontrollingspecialhardwaresuchasdiscdrivesorcontrollinginformationtransmissiontoothercomputers.MosttypesofI/Odevicesareprogrammabletosomeextent,allowingdifferentmodesofoperation,whilesomeactuallycontainspecialpurposemicroprocessorstopermitquitecomplexoperationstobecarriedoutwithoutdirectlyinvolvingthemainmicroprocessor.徐州工程学院毕业设计论文4Themicroprocessor,memoryandinput/outputcircuitmayallbecontainedonthesameintegratedcircuitprovidedthattheapplicationdoesnotrequiretoomuchprogramordatastorage.Thisisusuallythecaseinlowcostapplicationsuchasthecontrollersusedinmicrowaveovensandautomaticwashingmachines.Theuseofsinglepackageallowsconsiderablecostsavingstobemadewhenarticlesaremanufacturedinlargequantities.Astechnologydevelops,moreandmorepowerfulprocessorsandlargerandlargeramountsofmemoryarebeingincorporatedintosinglechipmicrocomputerswithresultingsavinginassemblycostsinthefinalproducts.Fortheforeseeablefuture,however,itwillcontinuetobenecessarytointerconnectanumberofintegratedcircuitstomakeamicrocomputerwheneverlargeramountsofstorageorinput/outputarerequired.Anothermajorengineeringapplicationofmicrocomputersisinprocesscontrol.Herethepresenceofthemicrocomputerisusuallymoreapparenttotheuserbecauseprovisionisnormallymadeforprogrammingthemicrocomputerfortheparticularapplication.Inprocesscontrolapplicationsthebenefitsoffittingtheentiresystemontoasinglechipareusuallyoutweighedbythehighdesigncostinvolved,becausethissortofequipmentisproducedinsmallerquantities.Moreover,processcontrollersareusuallymorecomplicatedsothatitismoredifficulttomakethemassingleintegratedcircuits.Twoapproachesarepossiblethecontrollercanbeimplementedasageneralpurposemicrocomputerratherlikeamorerobustversionofahobbycomputer,orasapackagedsystem,designedforreplacingcontrollersbasedonoldertechnologiessuchaselectromagneticrelays.Intheformercasethesystemwouldprobablybeprogrammedinconventionalprogramminglanguagessuchastheonestobeintroducedlater,whileintheothercaseaspecialpurposelanguagemightbeused,forexampleonewhichallowedthefunctionofthecontrollertobedescribedintermsofrelayinterconnections.IneithercaseprogramscanbestoredinRAM,whichallowsthemtobealteredtosuitchangesinapplication,butthismakestheoverallsystemvulnerabletolossofpowerunlessbatteriesareusedtoensurecontinuityofsupply.AlternativelyprogramscanbestoredinROM,inwhichcasetheyvirtuallybecomepartoftheelectronichardwareandareoftenreferredtoasfirmware.Moresophisticatedprocesscontrollersrequireminicomputersfortheirimplementation,althoughtheuseoflargescaleintegratedcircuitsblursthedistinctionbetweenminiandmicrocomputers.Productsandprocesscontrollersofvariouskindsrepresentthemajorityofpresentdaymicrocomputerapplications,theexactfiguresdependingononesinterpretationofthewordproduct.Virtuallyallengineeringandscientificusesofmicrocomputerscanbeassignedtooneorotherofthesecategories.MicrocomputerInterface