Which of the following may not definitely occur in an instruction cycle? (i)…
Which of the following may not definitely occur in an instruction cycle?
(i) Fetch cycle
(ii) Execution cycle
(iii) Indirect cycle
Answer: B. (iii) only — Answer: Only the indirect cycle may not definitely occur in an instruction cycle. Explanation: Fetch cycle: This is compulsory because the CPU must read the…
- A.
(ii) and (iii)
- B.
(iii) only
- C.
(i) only
- D.
(i) and (ii)
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Show answer & explanation
Correct answer: B
Answer: Only the indirect cycle may not definitely occur in an instruction cycle.
Explanation:
Fetch cycle: This is compulsory because the CPU must read the instruction from memory before any further action.
Execution cycle: This is compulsory because the CPU must carry out the operation specified by the instruction.
Indirect cycle: This is conditional and only occurs when the instruction uses indirect addressing (i.e., when an additional memory reference is needed to obtain the effective operand address). If the instruction uses direct or immediate addressing, the indirect cycle is skipped.
Therefore, the indirect cycle may not occur for some instructions, while fetch and execution cycles are always performed.