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NAND gate

technology Maturity 11-13 Next article →

Computers make decisions using tiny parts called logic gates. One very important part is the NAND gate. The name NAND stands for "NOT AND." This gate works by looking at its inputs. It only gives a LOW or "0" output if every input is HIGH or "1." If even one input is LOW, the output stays HIGH. This makes it the opposite of an AND gate.

NAND ANSI Labelled
NAND ANSI Labelled

We can see how this works by looking at switches. Imagine two switches, S1 and S2, in a circuit. If either switch is open, the output stays at 1. This happens because a pull-up resistor sets the signal. But if both switches are closed, they override the resistor. This forces the output to 0. Engineers build these gates using transistors and diodes.

NAND IEC
NAND IEC

NAND gates are special because of functional completeness. This is a big term that means something very useful. It means you can build any other logic function using only NAND gates. You could use them to make AND or OR gates. You could even build a whole computer processor using just NAND gates. This makes them a very powerful tool for building digital systems.

NAND from NOR
NAND from NOR

Many different types of chips hold these gates. For example, the 4011 is a common CMOS chip. This specific chip contains four independent NAND gates. There are also many other versions like the 4023 or 4068. These can have three, four, or even eight inputs. You can find them from many different makers. They come in different shapes like DIL or SOIC.

4011 Pinout
4011 Pinout

NAND gates are often better than NOR gates in CMOS circuits. This is because of how fast parts move charge. In these circuits, n-type transistors move charge faster than p-type ones. A NAND gate uses these fast parts in a way that is more efficient. This is why engineers often choose NAND gates for their designs. They help make electronic systems work well and quickly.

NAND ANSI Labelled
NAND ANSI Labelled
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File:NAND ANSI Labelled.svg
NAND ANSI Labelled.svg
File:NAND IEC.svg
NAND IEC.svg
File:NAND DIN.svg
NAND DIN.svg
File:4011 Pinout.svg
4011 Pinout.svg
File:NAND from NOR.svg
NAND from NOR.svg
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