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Hardwired and microcode methods form two radically different approaches to control unit design. Each has advantages and disadvantages when performance and cost are compared.
It is worth mentioning that, in general, the Complex Instruction Set Computers (CISC), e.g. Intel family of processors (i.e. 8086, Pentium, etc.), use the microprogrammed control unit design approach. However, in general, the Reduced Instruction Set Computers (RISC), e.g. SUN SPARC processors, use the hardwired control unit design approach. Improving Performance of Microprogrammed Control UnitFetching an instruction from the control store takes considerably longer than generating control signals using hardwired circuits. To improve performance of microprogrammed control unit, the following measures can be taken:
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