双语教学双语教学6.doc

《双语教学双语教学6.doc》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、Ch6   The Expanded System of Single Chip MicrocomputerlKeywords：静态RAM（SRAM，StaticRandomAccessMemory）动态RAM（DRAM，DynamicRandomAccessMemory）快擦写型存储器（FlashMemory）只读存储器（ROM，Read-onlyMemory）随机存取存储器（RAM，RandomAccessMemory）lIntroduction：    The8031'sDataMemorymaynotbe

2、usedforprogramstorage.Soitmeansyoucan'texecuteinstructionsoutofthisDataMemory.   But,thereisawaytohaveasingleblockofoffchipmemoryactingasbothProgramandDataMemory.Bygatingtogetherbothmemoryreadcontrols(RDandPSEN)usinganANDgate,acommonmemoryreadcontrolsignalcan

3、begenerated. Inthisarrangement,bothmemoryspacesaretiedtogetherandtotalaccessiblememoryisreducedfrom128Kbytesto64Kbytes.     The8031canreadandwriteintothiscommonmemoryblockanditcanbeusedasProgramandDataMemory.  Youcanusethisarrangementduringprogramdevelopmenta

4、nddebuggingphase.WithouttakingMicrocontrolleroffthesockettoprogramitsinternalROM(EPROM/FlashROM),youcanusethiscommonmemoryforfrequentprogramstorageandcodemodifications.        Thetipicalexpandedchipof8031is8155and8255.8155isa2048-bitstaticMOSRAMwithi/oportsan

5、dtimer.    8255provides24I/Opinswhichmaybeindividuallyprogrammedin2groupsof12andusedin3majormodesofoperation.InMODE0,eachgroupof12I/Opinsmaybeprogrammedinsetsof4and8tobeinputsoroutputs.InMODE1,eachgroupmaybeprogrammedtohave8linesofinputoroutput.3oftheremainin

6、g4pinsareusedforhandshakingandinterruptcontrolsignals.MODE2isastrobedbi-directionalbusconfiguration.8255isaprogrammableperipheralinterfacedevicedesignedforuseinIntelmicrocomputersystems.ItsfunctionisthatofageneralpurposeI/Ocomponenttointerfaceperipheralequipm

7、enttothemicrocomputersystembus.Thefunctionalconfigurationofthe8255isprogrammedbythesystemsoftwaresothatnormallynoexternallogicisnecessarytointerfaceperipheraldevicesorstructures.    This3-statebidirectional8-bitbufferisusedtointerfacethe8255tothesystemdatabus

8、.DataistransmittedorreceivedbythebufferuponexecutionofinputoroutputinstructionsbytheCPU.Controlwordsandstatusinformationarealsotransferredthroughthedatabusbuffer.    Thefunctionofthisbloc