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:
Understanding the Computer Instruction Processing Cycle
Computers process instructions using a fundamental sequence known as the instruction cycle or the fetch-decode-execute cycle. This cycle ensures that the processor correctly interprets and carries out commands given to it. Let's break down the steps involved in processing each instruction:
Detailed Steps in Instruction Processing
1. Fetch the Instruction from Memory (B)
The process begins with the processor fetching the next instruction that needs to be executed from the main memory (RAM). The Program Counter (PC) register holds the address of this instruction, and after fetching, the PC is updated to point to the next instruction.
2. Decode the Instruction (C)
Once the instruction is fetched into the processor, it needs to be decoded. The control unit interprets the instruction's opcode (the part that specifies the operation to be performed) and identifies any operands or addresses required for the operation.
3. Calculate the Effective Address (A)
Some instructions require data or locations in memory that are not directly specified but need to be calculated. This step involves determining the effective address of the operand(s) based on the addressing mode specified in the instruction (e.g., direct, indirect, indexed, or relative addressing).
4. Fetch the Operands from Memory (D)
After decoding the instruction and calculating the effective address (if necessary), the processor fetches the required data (operands) from the memory locations specified. If the operands are already in processor registers, this step might be skipped or modified.
5. Execute the Instruction (E)
This is the final step where the actual operation specified by the instruction is performed. The processor's Arithmetic Logic Unit (ALU) and other components carry out the task, such as arithmetic calculations, logical comparisons, data movement, or control flow changes.
The Correct Sequence
Based on the standard computer architecture principles, the correct sequence for processing an instruction is:
- B: Fetch the Instruction from memory
- C: Decode the instruction
- A: Calculate the effective address
- D: Fetch the operands from the memory
- E: Execute the Instruction
Therefore, the correct sequence is B, C, A, D, E.
Important Questions from Instruction Cycle
Execute Cycle of Computer is
A fetch cycle is the
The first machine cycle of an instruction is always a
Identify the correct sequence of steps A-D followed by the CPU as it processes each instruction in a program.
A. Store
B. Decode
C. Fetch
D. Execute
Choose the correct answer from the options given below :
