For computers based on three-address instruction formats, each address field…
2015
For computers based on three-address instruction formats, each address field can be used to specify which of the following:
(S1) A memory operand
(S2) A processor register
(S3) An implied accumulator register
Answer: A. Either S1 or S2 — Key idea: In three-address instruction formats each operand is supplied explicitly by the instruction. A memory operand (S1): allowed — an address field can…
- A.
Either S1 or S2
- B.
Either S2 or S3
- C.
Only S2 and S3
- D.
All of S1, S2 and S3
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Correct answer: A
Key idea: In three-address instruction formats each operand is supplied explicitly by the instruction.
A memory operand (S1): allowed — an address field can name a memory location.
A processor register (S2): allowed — an address field can name a register.
An implied accumulator register (S3): not allowed — implied accumulators are used in accumulator (one-address) architectures, but three-address instructions provide all operand addresses explicitly.
Conclusion: Each address field can specify either a memory operand or a processor register (S1 or S2), so the correct choice is the one that states Either S1 or S2.
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