电气工程及其自动化专业 外文文献 英文文献 外文翻译 plc方面.docx

1、 外文原文A:FundamentalsofSingle-puterThesingle-puterandtheintegratedcircuitarguablythetowmostsignificantinventionsofthe20thcentury[1].Thesetowtypesofarchitecturearefoundinsingle-,-5A-1,othersfollowthephilosophy,eneral-putersandmicroprocessors,ofmakingnologicaldistinctionbetweenprogramanddatamemoryasinthePrincetonarchitecture,-5A--puterintoasingledevice,asshowninFig3-5A-&-5A-1AHarvardtypeInput&memory -5A-2. puterExternalSystemTimer/ponentsSerialI/OResetInterruptsPowerROMPrarallelI/ORAMCPUFig3-5A-(ROM).ROMisusuallyforthepermanent,non--,(orintendedforusewith)/-chipROM[2];therecanstillbeasignificantsavinginI/'piggy-back'EPROM(ErasableprogrammableROM)socketsordeviceswithEPROMinsteadofROM。ThesedevicesarenaturallymoreexpensivethanequivalentROMdevice,-volumeapplicationswheretheyprovidetheadvantagesofasingle-chipdevice,intermsofon-chipI/O,etc.,withtheconvenienceofflexibleuserprogra