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1、1、外文原文（复印件）A:FundamentaIsofSingle-chipMicrocomputerof bothThesing1e-chipmicrocomputeristheculminationthedevelopmentofthedigitaicomputerandtheintegratedcircuitarguab1ythetowmostsignificantinventionsofthe20thcentury1LThesetowtypesofarchitectorearefoundinsingIe-chipmicrocomputer.Someemp1oythesplitprogr
2、am/datamemoryoftheHarvardarchitecture,showninFig.3-5A-1,othersfollowthephiIosophy,widelyadaptedforgeneral-purposecomputersandmicroprocessors,ofmakingnologicaldistinctionbetweenprogramanddatamemoryasinthePrincetonarchitecture,showninFig.3-5A-2.Ingeneraltermsasing1e-chipmicrocomputerischaracterizedbyt
3、heincorporationofalltheunitsofacomputerintoasingledevice,asshowninFig3-5A-3.ProgramInput&AHarvardtypeFig.3-5A-2.AconventionalPrincetoncomputerExternalSystemTimer/TimingSerialI/OResetROMInterruptsPrarallelCPUPowerFig3-5A-3.PrincipalfeaturesofamicrocomputerReadOnIymemory(ROM).ROMisusuallyforthepermane
4、nt,non-vo1ati1estorageofanapplicationsprogram.Manymicrocomputersandmicrocontrollersareintendedforhigh-vo1umeapplicationsandhencetheeconomicalmanufactureofthedevicesrequiresthatthecontentsoftheprogrammemorybecommittedpermanent1yduringthemanufactureofchips.Clearly,thisimpliesarigorousapproachtoROMcode
5、deveIopmentsincechangescannotbemadeaftermanufacture.ThisdeveIopmentprocessmayinvo1veemuIationusingasophiSticateddevelopmentsystemwithahardwareemuIationcapabiIityaswellastheuseofpowerfulsoftwaretools.Somemanufacturersprovideadditiona1ROMoptionsbyincludingintheirrangedeviceswith(orintendedforusewith)u
6、serprogrammab1ememory.Thesimplestoftheseisusuallydevicewhichcanoperateinamicroprocessormodebyusingsomeoftheinput/outputlinesasanaddressanddatabusforaccessingexternalmemory.Thistypeofdevicecanbehavefunctiona11yasthesinglechipmicrocomputerfromwhichitisderivedalbeitwithrestrictedI/Oandamodifiedexternal
7、circuit.TheuseoftheseROMlessdevicesiscommoneveninproductioncircuitswherethevolumedoesnot justify the development costs can still be a significant sav i ng to a conventional microprocessor replacement for ROM devices can be with ,p i ggy-back, EPROM(Erasable devices with EPROM instead of ROM 。expens
8、i ve than equivalent ROM device, but do circuit equ i va 1 ents. EPROM based devices are attract i ve for 1ow-voIume app1i cat ions where advantages of a s ing 1e-chip device, in terms etc. , with the conven i ence of flexible userof custom on-chip ROM2;there in I/O and other chips compared based ci
9、rcuit. More exact obtained in the form of variants programmab1e ROM ) sockets orThese devices are natural 1y more provide compIete also extreme 1y they provide the of on-chip I/O, programmability.Randomaccessmemory(RAM).RAMisforthestorageofworkingvariab1esanddatausedduringprogramexecution.Thesizeoft
10、hismemoryvarieswithdevicetypebutithasthesamecharacter!Sticwidth(4,8,16bitsetc.)astheprocessor,Specia1functionregisters,suchasstackpointerortimerregisterareoftenlogicallyincorporatedintotheRAMarea.11isalsocommoninHarardtypemicrocomputerstotreattheRAMareaasacollectionofregister;itisunnecessarytomakedi
11、stinctionbetweenRAMandprocessorregisterasisdoneinthecaseofamicroprocessorsystemsinceRAMandregistersarenotusual1yphysicallyseparatedinamicrocomputer.Centralprocessingunit(CPU).TheCPUismuchlikethatofanymicroprocessor.Manyapp1icationsofmicrocomputersandmicrocontrollersinvolvethehand1ingofbinary-codedde
12、cimal(BCD)data(fornumericaldisplays,forexample),henceitiscommontofindthattheCPUiswelladaptedtohand1ingthistypeofdata.11isalsocommontofindgoodfacilitiesfortesting,settingandresettingindividualbitsofmemoryorI/OsincemanycontrolIerapp1icationsinvolvetheturningonandoffofsingleoutputlinesorthereadingthesi
13、ngleline.Theselinesarereadi1yinterfacedtotwo-statedevicessuchasswitches,thermostats,solid-staterelays,valves,motor,etc.ParaII6Iinpuatuatpuat.Paral1elinputandoutputschemesvarysomewhatindifferentmicrocomputer;inmostamechanismisprovidedtoatleastallowsomeflexibilityofchoosingwhichpinsareoutputsandwhicha
14、reinputs.Thismayapp1ytoallorsomeoftheports.SomeI/Olinesaresuitab1efordirectinterfacingto,forexamp1e,fIuorescentdisplays,orcanprovidesufficientcurrenttomakeinterfacingothercomponentsstraightforward.SomedevicesallowanI/Oporttobeconfiguredasasystembustoallowoff-chipmemoryandI/Oexpansion.Thisfacilityisp
15、otentiallyusefulasaproductrangedevelops,sincesuccessiveenhancementsmaybecometoobigforon-chipmemoryanditisundesirablenottobuildontheexistingsoftwarebase.SiaIinpiltOUtPUt.Serialcommunicationwithterminaldevicesiscommonmeansofprovidingalinkusingasma11numberoflines.ThissortofcommunicationcanalsobeexpIoit
16、edforinterfacingspecialfunctionchipsorlinkingseveralmiCrocomputerstogether.Boththecommonasynchronoussynchronouscommunicationschemesrequireprotocolsthatprovideframing(startandstop)information.Thiscanbeimp1ementedasahardwarefacilityorU(三)ART(Universal(synchronous)asynchronousreceiver/transmitter)relievingtheprocessor(andtheapp1icationsprogrammer)
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