Some of the operand accessing modes in the processor are given below:

6 clock cycles are consumed for memory reference, 2 clock cycles are consumed for arithmetic computation and zero memory reference is required for register mode or the operand is an instruction itself. Calculate the average operand fetch time if the processor of 0.25 GHz frequency is used?

(A) 30 ns
(B) 40 ns
(C) 50 ns
(D) None of these.


Answer: (A)

Explanation: Average operand fetch = Σ AM mode frequency * cycle consumed in particular AM
I.e. = (15 * 0 + 10 * 0 + 30 * 8 + 25 * 16 + 7 * 12 + 13 * 2) / 100
2.4 + 4 +0.84 + 0.26 = 7.5 cycles
Processor uses 0.25 GHz frequency
I.e. 4 ns cycle
Average operand fetch time = Average operand fetch * cycle time
7.5 * 4 ns = 30 ns
So, option (A) is correct.

Quiz of this Question