CPU performance terminology: The time required for fetching and executing one simple machine instruction is referred to as what?
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ADelay time
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BCPU cycle
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CReal time
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DSeek time
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ENone of the above
Answer
Correct Answer: CPU cycle
Explanation
Introduction / Context:Measuring processor performance often involves understanding the duration associated with instruction processing. The question asks for the standard term used for one fetch–execute sequence.
Given Data / Assumptions:
- Instruction is 'simple' and typical.
- We consider the combined fetch and execute operations.
Concept / Approach:
The CPU cycle (also called the machine cycle) spans the necessary steps to fetch an instruction from memory and execute it. It differs from a single oscillator clock tick; multiple clock cycles may compose one CPU cycle depending on architecture.
Step-by-Step Solution:
1) Associate 'fetch + execute' with 'machine/CPU cycle'.2) Eliminate unrelated timing terms.3) Select 'CPU cycle'.Verification / Alternative check:
Architectures document instruction timing as cycles per instruction (CPI), i.e., number of clock cycles required per CPU cycle for a given instruction mix.
Why Other Options Are Wrong:
- Delay time: generic latency term.
- Real time: refers to time-constrained systems.
- Seek time: storage head movement delay, unrelated to CPU.
- None: incorrect because 'CPU cycle' is correct.
Common Pitfalls:
- Confusing a clock cycle with a CPU/machine cycle; the latter may include several clock ticks.
Final Answer:
CPU cycle.