Supplemental Reading on Logic Gates

Logic Gates

Knowing how logic gates work is important to understanding how a computer works. Computers work by performing binary calculations. Logic gates are electrical components that tell a computer how to perform binary calculations. They specify rules for how to produce an electrical output based on one or more electrical inputs. Computers use these electrical signals to represent two binary states: either an “on” state or an “off” state. A logic gate takes in one or more of these binary states and determines whether to pass along an “on” or “off” signal.

Several logic gates have been developed to represent different rules for producing a binary output. This reading covers six of the most common logic gates.

Six common logic gates

NOT gate

The NOT gate is the simplest because it has only one input signal. The NOT gate takes that input signal and outputs a signal with the opposite binary state. If the input signal is “on,” a NOT gate outputs an “off” signal. If the input signal is “off,” a NOT gate outputs an “on” signal. All the logic gates can be defined using a schematic diagram and truth table. Here’s how this logic rule is often represented: