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Logic Gate Simulator

Logic Gate & Truth Table Builder

Pick a gate, toggle its inputs, and see the live output plus the complete truth table.

Inputs
AND Output
0
ABAND(A, B)
000
010
100
111

About the Logic Gate & Truth Table Builder

Every digital circuit, no matter how complex, reduces to combinations of these seven basic gates. This tool lets you toggle inputs and see exactly how each gate responds, plus its complete truth table.

Why NAND and NOR are called universal gates

Any logic function can be built using only NAND gates, or only NOR gates, wired together in different combinations — try building an inverter from a NAND gate by tying both its inputs together, or an AND gate from two NAND gates in series. This universality is why many real chip manufacturing processes are optimized around fabricating one gate type extremely well and repeating it billions of times, rather than building many different gate structures.

Frequently asked questions

Why does the NOT gate only have one input?

NOT is a unary operation — it simply inverts a single input (0 becomes 1, 1 becomes 0) — so it only needs one input signal, unlike AND, OR, NAND, NOR, XOR, and XNOR, which are all binary operations comparing two inputs.

What is the difference between XOR and XNOR?

XOR (exclusive OR) outputs 1 when its two inputs differ from each other, and 0 when they match. XNOR is simply the inverse of XOR: it outputs 1 when the inputs match, and 0 when they differ.

Related tools & guides

Digital Logic Design FundamentalsVerilog vs VHDL Syntax Reference