Fiducia TogetherLogic gates
AND, OR and NOT, and the truth tables that describe them.
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
Logic gates take binary inputs and produce a binary output. AND outputs 1 only if all inputs are 1; OR outputs 1 if any input is 1; NOT inverts. XOR, NAND and NOR appear on some specifications.
Where it applies
GCSE and A Level computer science.
How it works
A truth table lists every possible combination of inputs with the output. Two inputs give four rows; three give eight.
Logic gates are how a processor computes, which is the link back to the CPU.
How to use it in your work
Write every input combination in a systematic order — 00, 01, 10, 11 — so none is missed.
For circuits with more than one gate, add a column for each intermediate output. Trying to do it in one step is where errors happen.
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.