Differences between hardwired and micro-programmed control unit



S.N.
Hardwired Control Unit
Micro-programmed Control Unit
1.
It is implemented through the use of sequential logic circuit. Its input logic signals are transformed into a set of output logic signals which are control signals.
It is implemented through the use of micro-programs. Micro-programs (control information) are organized as a sequence of micro-instructions stored in a special control memory.
2.
This design uses a fixed architecture so, it require changes in wiring if the instruction set is modified.
It is easy to reconfigure and modify instruction set.
3.
It is difficult to build a circuit that satisfies all the operations.
It is simple in structure.
4.
It has faster mode of operation.
It is comparatively slower.
5.
It is comparatively expensive.
It is cheaper.
6.
It is preferred for less number of instruction sets.
It is preferred for large number of instruction sets.
7.
It is preferred for RISC (Reduced Instruction Set Computer).
It is preferred for CISC (Complex Instruction Set Computer).






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