Fiducia TogetherHardware and the CPU
The processor, what it does, and the three things that make it faster.
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.
What it is
The CPU executes instructions via the fetch-decode-execute cycle. Its parts include the control unit, the arithmetic logic unit, the clock and registers. Von Neumann architecture stores instructions and data in the same memory.
Where it applies
GCSE and A Level computer science.
How it works
Performance depends on clock speed (cycles per second), number of cores (instructions in parallel) and cache size (fast memory close to the processor, reducing waits for RAM).
More cores only help software written to use them, which is a standard higher-mark point.
How to use it in your work
When asked why a computer is slow, name a specific factor and explain the mechanism, not just "it needs more RAM".
Learn the fetch-decode-execute cycle as three named stages in order.
Cache is not RAM and RAM is not storage. Keep the three distinct.
Where to get help
Your teacher and your board's specification — the pseudocode and the required language differ between boards. Bitesize covers the concepts; the computer science song runs the topics.
Revise this with a song
These are ours. We write revision songs because a lot of people remember a tune when they cannot remember a page, and because revising out loud in the kitchen beats staring at a highlighter.
- The Computer Science Song The GCSE computer science topics, set to music.
Where to read more
Last reviewed 2026-08-28 by Fiducia Together · Next review due 2027-08-28
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.