A Level Computer Science OCR Practice Exam

In CPU architecture, what is pipelining primarily used for?

1. To create multiple processing units within the CPU

2. To increase the efficiency of instruction execution

3. To reduce the size of the CPU

4. To store multiple instructions for later use

The correct answer is: To increase the efficiency of instruction execution

Pipelining is primarily used to increase the efficiency of instruction execution within CPU architecture. This technique breaks down the instruction processing into separate stages, with each stage handling a distinct part of the instruction cycle—fetching, decoding, executing, and writing back results. By allowing multiple instructions to overlap in execution, pipelining significantly improves the throughput of the CPU. For instance, while one instruction is being executed, another can be decoded, and yet another can be fetched from memory, maximizing the use of CPU resources and minimizing idle time. This results in a more efficient use of the CPU’s capabilities, allowing it to process more instructions over the same time period compared to a non-pipelined architecture where each instruction must complete before the next one begins. The other options are related to CPU architecture but do not accurately capture the primary purpose of pipelining. While creating multiple processing units might involve additional techniques such as multi-core designs, and reducing the size of the CPU involves different considerations in architecture design, pipelining focuses specifically on enhancing the speed and efficiency of instruction processing. Storing multiple instructions for later use aligns more closely with concepts like queuing or buffering rather than the direct execution process outlined by pipelining.