Logic gates
Pick a gate, then flip the switches. The bulb shows the gate’s output, and the truth table highlights the row you are on.
AND gate
Tap the switches to turn them on and off.
| A | B | Q |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
What is a logic gate?
A logic gate is a tiny electronic part that takes one or two inputs, each either 1 (on) or 0 (off), and gives one output. Computer chips are made of millions of them, working together.
The five gates
- AND: the output is 1 only when both inputs are 1.
- OR: the output is 1 when at least one input is 1.
- NOT: has one input and flips it. 1 becomes 0, and 0 becomes 1.
- NAND: “NOT AND”. The opposite of AND. The small circle on its symbol means “flip the output”.
- NOR: “NOT OR”. The opposite of OR. The output is 1 only when both inputs are 0.
What is a truth table?
A truth table lists every possible set of inputs and the output for each. A gate with two inputs has four rows, because there are four ways to set two switches.
Ready to join gates together? Try the logic circuit builder.