1 Why do CISC machines use microprogramming 2 Suppose that o

1. Why do CISC machines use micro-programming?

2. Suppose that our MIPS core instruction subset is expanded to include the ori (or immediate) instruction. How many clock cycles would be required to execute the ori instruction on the multi-cycle datapath? Describe any new states and transitions required for the FSM (finite state machine) description and indicate the proper setting for all control signals used in each state . If no changes are needed, explain why.

3. Suppose that our original MIPS core instruction subset is expanded to include the addi (add immediate) instruction. How many clock cycles would be required to execute the addi instruction on the multi-cycle datapath? Describe any new FSM states and/or transitions that would be required and indicate the proper setting for all control signals used in each new state . If no changes are needed, explain why.

Solution

1.

CISC means Complex Instruction Set Computer. It hascomplex instructions and generally used in complex addressing modes.
It executes different machine programsand it uses micro-program control unit. CISC processors have limited number of registers.

So, CISC machines use micro-programming.