1. Recall that the control unit of the processor drives the Fetch-Execute instruction cycle by generating an
appropriate sequence of control signals. Consider the following simple computer.
The fetch of the next instruction pointed at
by the PC needs the following steps
(micro-operations):
[MAR] โ [PC]
[PC] โ [PC] + 1 (Increment PC)
[MBR] โ Memory read from MAR addr.
[IR] โ [MBR]
Once fetched into the IR, the LOAD R0, M
instruction needs the following steps to
execute:
[MAR] โ [IR]
Address
[MBR] โ Memory read from MAR addr.
[R0] โ [MBR]
a) What would be the steps needed to
execute the STORE M, R1 instruction?
b) What would be the steps needed to
execute the ADD R1, R0 instruction?
c) What would be the steps needed to
execute the BRA T instruction?
d) What would be the steps needed to
execute the BEQ T instruction?
Computer Org. Lecture 20 Name:_______________
Lecture 20 Page 1
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