A Level Computer Science OCR Practice Exam

What process encompasses the fetching, decoding, and executing of instructions?

1. Command Cycle

2. Action Cycle

3. Instruction Cycle

4. Processor Cycle

The correct answer is: Instruction Cycle

The process that encompasses fetching, decoding, and executing instructions is known as the Instruction Cycle. This cycle is fundamental to the operation of a CPU and is pivotal in understanding how computers process information. During the instruction cycle, the CPU retrieves (or fetches) an instruction from memory. This is the first step and involves accessing the memory address where the instruction is stored. Once the instruction has been fetched, the CPU then decodes it to understand what action is required. This decoding process translates the binary instruction into a format that can be understood and executed by the CPU. Finally, the execution phase follows, where the CPU carries out the instruction. This could involve arithmetic operations, moving data from one location to another, or interacting with peripherals, among other tasks. This combination of fetching, decoding, and executing instructions allows the CPU to perform tasks and run programs, making the Instruction Cycle a core concept in computer architecture and operation. Understanding this cycle is crucial for grasping how processors function and how they carry out tasks as directed by software.