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A flat-backed D shape, outputting true only when every input is true.
Also known as: AND gate, D shape logic symbol
The D-shaped AND gate outputs true only when all its inputs are. Two incompatible symbol sets exist for logic gates — the distinctive shapes and the rectangular IEC forms — and engineers overwhelmingly use the shapes.
Outputs a true signal only when every one of its inputs is true, implementing logical conjunction in hardware.
Contexts: Technical drawing, Electrical equipment
Exists in two competing notations: the distinctive shapes, which dominate in practice, and the rectangular IEC forms, which are standardised and comparatively little used.
Contexts: Technical drawing, Electrical equipment
Is negated by a small circle on its output, which turns it into a NAND gate — one bubble changing the function entirely.
Contexts: Technical drawing, Electrical equipment
Is drawn two different ways by two different standards. The international form defined by the IEC is a plain rectangle containing the label &; the form defined by the American ANSI and IEEE standards is a distinctive shape with a flat back and a semicircular front, the outline most people picture when they hear 'logic gate'. Neither is a mistake and neither is old-fashioned — a reader meeting an unfamiliar drawing of a familiar component is usually looking at the other continent's standard rather than at an error.
Contexts: Technical drawing, Electrical equipment
Related forms that are not treated as separate canonical symbols — see our variant rules.
IEC rectangular form
A rectangle with an ampersand inside it and the inputs on the left. Extends cleanly to gates with many inputs, which is why it dominates in formal documentation.
ANSI distinctive-shape form
The flat-backed, round-fronted 'D' outline. Recognisable at a glance without reading a label, which is why textbooks and hobbyist schematics keep it.
A shape with a straight vertical back and a semicircular front, with two or more input lines entering the flat side and one output leaving the curved side.
Flat back against curved back, for opposite logic.
The basic logic gate symbol set.
The same operation in hardware and in formal logic.