COMPSCI 61C Lecture Notes - Lecture 8: Motorola 68000 Series, Mips Instruction Set, Instruction Set
28 Aug 2017
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Document Summary
Basic job of a cpu: execute lots of instructions. Instructions are primitive operations that the cpu might execute. The set of instructions a particular cpu implements is an instruction set architecture (isa) Early trend was to add more and more instructions to new cpus to do elaborate operations (ex. Risc philosophy (cocke ibm, patterson, hennessy, 1980s): reduced instruction set. Let software do complicated operations by composing simpler ones. Mips: branch delay slot (the instruction immediately after an if is always executed) Arm: 32b, 64b is generic risc with condition codes for instructions; allow you to say. Only do this instruction if previous value was true / false . Mips: semiconductor company that built one of the rst commercial risc architectures. Accident of history: patterson & hennessy in mips. Unlike hll (higher level languages) like c or java, assembly can"t use variables because they must keep hardware simple. Limited number of special locations built directly into the hardware.
