ITPEC FE Subject A April 2025 Question 8
Topic: Computer Component
For a CPU with a clock frequency of 800 MHz, where one instruction is executed in an average time of 4 clock cycles, what is the CPU performance in MIPS?
Explanation
200 MIPS — divide the clock rate by the number of clock cycles each instruction takes.
- •Clock: 800 MHz = 800 million cycles per second
- •Instructions per second: 800 ÷ 4 = 200 million
- •MIPS counts millions of instructions per second, so the performance is 200 MIPS
Answer (c)
Why not others:
- •(d) 3,200 — multiplies by the 4 cycles, 800 × 4, instead of dividing
- •(b) 20 — a factor-of-ten slip, as if the clock were 80 MHz
- •(a) 0.2 — the right rate expressed in billions of instructions per second (0.2 GIPS), not millions
Key rule: MIPS = clock frequency in MHz ÷ average cycles per instruction; more cycles per instruction means fewer instructions per second.
Computer Component · AI-written, may contain errors
This question comes from an official ITPEC past paper. ITPEC Practice is an independent study tool and is not affiliated with ITPEC. See the official FE past-paper collection or Report an issue.