Which sequence correctly represents steps to execute a computer program?

Which sequence correctly represents steps to execute a computer program?

• A. Decode, Fetch, Execute
• B. Fetch, Decode, Execute
• C. Execute, Fetch, Decode
• D. Fetch, Execute, Decode

Answer: (B)

Understanding how a CPU processes one instruction: it follows an instruction cycle that fetches the next instruction, decodes what needs to be done, and then executes it. First, the CPU fetches the instruction from memory into its instruction register so it has a concrete command to work with. Next, it decodes that instruction to figure out the operation to perform and which data or operands are involved. Finally, it executes the operation, carrying out arithmetic, data movement, or control changes as specified. This fetch-decode-execute sequence repeats for every instruction in a program, which is why it’s the standard order. If you tried to decode before fetching, there would be nothing to decode; if you attempted to execute before decoding, the processor wouldn’t know what to do. Hence, fetching first, then decoding, then executing is the correct order.

Understanding how a CPU processes one instruction: it follows an instruction cycle that fetches the next instruction, decodes what needs to be done, and then executes it. First, the CPU fetches the instruction from memory into its instruction register so it has a concrete command to work with. Next, it decodes that instruction to figure out the operation to perform and which data or operands are involved. Finally, it executes the operation, carrying out arithmetic, data movement, or control changes as specified. This fetch-decode-execute sequence repeats for every instruction in a program, which is why it’s the standard order. If you tried to decode before fetching, there would be nothing to decode; if you attempted to execute before decoding, the processor wouldn’t know what to do. Hence, fetching first, then decoding, then executing is the correct order.