Computer Organization 21. Processorsvon Neumann CPU Data Path<insert diagram>- register-memory instructions- register-register instructionso data path cycle- fetch-decode-execute cycle- interpretero program fetches, examines, executes instructions of another programo design new machine NMo specify machine language NML for new machine NM o build hardware processor for NM to execute programs written in NML oro use language OML which runs on another machine OM to write interpreter which will fetch & examine statements written in NML and cause them to be executed on the machine OM- NM – complex instructions- OM – simple instructions - interpreter breaks complex NML instructions into simpler OML instructions- complex instruction set faster execution but expensive machines- machine families – replication of instruction sets across all machines- interpreted instructionso simple machines – lower costo add new instructions at minimal costo change the implementation of old instructionso efficient implementation of complex instructionsComplex Instruction Sets Implemented Directly in Hardware ProcessorCray SeriesControl Data Corp Cyber SeriesImplemented via an Interpreter Digital Equipment Corp VAX Motorola 68000control storesfast read-only memoriesexecution speeddirect hardware implementation speed == ½ (interpreted implementation
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