NAND gate
A NAND gate is a logic gate used to build digital logic circuits. It is a combination of an AND and NOT gate. The name refers to this. The NAND gate is a “universal gate”, that means all other types of logic gates can be obtained by wiring exclusively one or more NAND gates in a particular manner.
Behavior
[change | change source]Given two inputs, A and B, A NAND B will be true if at most one of A and B is true. In other words, A NAND B is false if both A and B are true, and true otherwise.
| INPUT | OUTPUT | |
| A | B | A ⊼ B |
| 0 | 0 | 1 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 0 |
Symbols
[change | change source]There are three symbols for drawing NAND gates in electrical circuit schematics: the "distinctive shape" symbol, the “military” symbol, and the “rectangular” symbol. For more information see logic gate symbols.
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“Distinctive shape” NAND symbol, also that used by US ANSI -
“Military” NAND symbol, also that used by DIN -
“Rectangular” NAND symbol, used by IEC
Application
[change | change source]Since a NAND gate is a universal gate, microprocessors can be built using this type of gate only. For example:
- the negation can be represented by ¬A ≡ A ⊼ A
- and the disjunction can be obtained by A ∨ B ≡ (A ⊼ A) ⊼ (B ⊼ B)
