NAND (Chip)

In digital electronics, a NAND gate (negative-AND) is a logic gate which produces an output which is 0 (low) only if all its inputs are 1 (high); thus its output is complement to that of the AND gate. A 0 (low) output results only if all the inputs to the gate are 1 (high); if at least one of the inputs are 0 (low), a 1 (high) output results.

The NAND gate is significant because any boolean function can be implemented by using a combination of NAND gates. This property is called functional completeness.

If no signal is connected to an input pin, the input is read as 1 (high). This is done by internal pull-up resistors that pull the signal to high in the absence of an input signal. Using this mechanism the NAND gate can be used with 2 or 3 inputs in the exact same way.

Play with the 3 buttons to see the function of the NAND gate. You will see that the output is only 0 (low) if all 3 inputs are 1 (high).