The computer needs to process each instruction with the following sequence of…
2025
The computer needs to process each instruction with the following sequence of steps:
A. Calculate the effective address
B. Fetch the Instruction from memory
C. Decode the instruction
D. Fetch the operands from the memory
E. Execute the Instruction
Choose the correct answer from the options given below:
- A.
A, B, C, D, E
- B.
B, A, D, A, E
- C.
B, C, A, D, E
- D.
C, B, A, D, E
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Show answer & explanation
Correct answer: C
Correct sequence of steps for processing an instruction:
Fetch the instruction from memory: The processor reads the instruction bits from memory into the instruction register.
Decode the instruction: Interpret the opcode and addressing mode so the CPU knows what action to perform and where operands are located.
Calculate the effective address (if required): Use addressing mode information obtained during decode to compute the memory address of any operand.
Fetch the operands from memory (if required): Read operand data from the calculated effective address or obtain operands from registers.
Execute the instruction: Perform the operation (ALU operation, memory write, branch, etc.) using the fetched operands.
Why other orders are incorrect:
Decoding cannot occur before fetching because there are no instruction bits to decode.
Calculating effective address and fetching operands must follow decoding so the CPU knows the correct addressing mode and whether operands are in memory or registers.
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