Logic Gates
Tap the gate that matches the table
What is Logic Gates?
Logic Gates is a free puzzle game about the switches that every computer is built from. A gate takes two inputs, each on (1) or off (0), and produces one output. AND is on only when both inputs are on, OR when either is, XOR when they are different. You are shown a gate's complete behaviour as a truth table and have to name it. Ten puzzles a round.
How to play Logic Gates
Controls: Tap the gate that matches the table
- 1Read the truth table: it lists every possible pair of inputs and what the gate outputs for each.
- 2Blue circles are the two inputs, green is the output. 1 means on, 0 means off.
- 3Work out which gate behaves that way across all four rows.
- 4Tap the gate name you think it is.
- 5The right answer is revealed with a short description, then the next puzzle appears.
Logic Gates tips and strategy
- Check the bottom row first, where both inputs are 1. AND and OR both give 1 there, while XOR, NAND and NOR all give 0 - that one row splits the field in half immediately.
- Then check the top row, where both inputs are 0. Only NAND and NOR give 1 there.
- XOR is the odd one out: it is the only basic gate that cares whether the inputs are different rather than how many are on.
- NAND and NOR are just AND and OR with every output flipped. If a table looks like an upside-down AND, it is NAND.
Logic Gates FAQ
What is a logic gate?
A tiny circuit that takes one or two inputs, each either on or off, and produces a single output according to a fixed rule. Combining millions of them is how a processor adds numbers, compares values and makes decisions.
What is the difference between AND, OR and XOR?
AND outputs 1 only when both inputs are 1. OR outputs 1 when at least one input is 1. XOR outputs 1 only when the two inputs are different, so it gives 0 when both are 1 - which is where people usually trip up.
What is a truth table?
A table listing every possible combination of inputs and the output for each one. Because a two-input gate only has four possible input combinations, a truth table describes its behaviour completely.
Why does NAND matter so much?
Because you can build every other gate out of NAND gates alone. That makes it enormously convenient for chip manufacturing, and a lot of real hardware is built almost entirely from them.
