2. NAND gate or gate:
3. The NAND gate forms a NOT gate:
Gate circuit: the unit circuit used to realize basic logic operation and compound logic operation is called gate circuit. Commonly used gate circuits have several logical functions, such as AND gate, OR gate, NOT gate, NAND gate, NOR gate, NOR gate and XOR gate.
Any electronic circuit that switches pulses on the pulse path is called gate circuit, which is a basic logic circuit. A gate circuit can have one or more inputs, but only one output. Only when the pulse signals applied to the input terminals of the gate circuit meet certain conditions, the "gate" will be opened, that is, the pulse signals will be output. Logically speaking, it is the "cause" of the input meeting certain conditions and the "result" of the signal output. The function of gate circuit is to realize some causal relationship-logical relationship. So gate circuit is a kind of logic circuit. There are three basic logical relationships: and logic, or logic and illogical. Correspondingly, the basic gate circuit is AND gate or NAND gate.
References:
Baidu Encyclopedia "Gate" Entry