A Level Computer Science OCR Practice Exam

Which of the following best describes the fetch-decode-execute cycle?

1. A repetitive sequence for program storage

2. A method for managing system memory

3. A cycle for carrying out instructions in the CPU

4. A process for transferring commands between buses

The correct answer is: A cycle for carrying out instructions in the CPU

The fetch-decode-execute cycle is a fundamental process that describes how a CPU operates to carry out instructions from a program. This cycle consists of three main stages: fetching the instruction from memory, decoding the instruction to determine what action is required, and executing the instruction to perform that action. This repetitive nature allows the CPU to process a continuous stream of instructions, making it the core mechanism for executing programs. In the context of computer architecture, understanding this cycle is critical because it lays the foundation for how a computer performs tasks, making it central to the operation of any system using a CPU. Each stage of the cycle is integral to ensuring that the CPU systematically processes instructions and manages tasks efficiently. The other options do not accurately represent the cycle's main characteristics and function. They address aspects like program storage, system memory management, and bus communication, which, while important to a computer's operation, do not specifically define the cycle inherent to instruction processing in the CPU.