An integrated circuit or other device whose inputs and

outputs represent Boolean or binary values as voltages

(TTL uses 0V for False or 0, +5V for True or 1). Different

gates implement different Boolean functions: AND, OR,

NAND, NOR (these may take two or more inputs) NOT (one

input), XOR (two inputs). NOT, NAND and NOR are often

constructed from single transistors and the other gates made

from combinations of these basic ones. These functions are

all combinatorial logic functions, i.e. their outputs depend

only on their inputs and there is no internal state. Gates

with state, such as latches and flip-flops, are

constructed by feeding some of their outputs back to their

inputs.