Summary
Highlights
Similar to the NOR gate, the NAND gate combines an AND gate with a NOT gate, providing the opposite output of an AND gate. If A=0 and B=0, Y=1 (opposite of AND gate's 0). If A=1 and B=0, Y=1 (opposite of AND gate's 0). If A=0 and B=1, Y=1. If A=1 and B=1, Y=0 (opposite of AND gate's 1).
A logic gate is a basic building block of any digital system, featuring one or more inputs and a single output. The relationship between inputs and output is based on a specific logic. There are seven basic types of logic gates: OR, AND, NOT, NOR, NAND, Exclusive OR, and Exclusive NOR. This video will discuss each, along with their truth tables.
The OR gate has two inputs (A, B) and one output (Y). Its truth table shows that the output is '1' if at least one input is '1'. For example, if A=0 and B=0, Y=0. If A=1 and B=0, Y=1. If A=0 and B=1, Y=1. If A=1 and B=1, Y=1. It can be visualized as a light bulb with two parallel switches; the bulb glows if either switch A or B (or both) are on.
The AND gate also has two inputs (A, B) and one output (Y). Its function is based on multiplication. For the output to be '1', both inputs A and B must be '1'. If A=0 and B=0, Y=0. If A=1 and B=0, Y=0. If A=0 and B=1, Y=0. If A=1 and B=1, Y=1. This can be understood as A multiplied by B equals Y.
The NOT gate, or inverter, has a single input and a single output. It outputs the opposite state of its input. If the input is '1', the output is '0', and if the input is '0', the output is '1'.
The Exclusive OR (XOR) gate gives an output of '1' only when there is a signal in exactly one of its inputs. If both inputs are the same (either both 0 or both 1), the output is '0'. So, if A=0 and B=0, Y=0. If A=1 and B=0, Y=1. If A=0 and B=1, Y=1. If A=1 and B=1, Y=0.
The Exclusive NOR (XNOR) gate is formed by combining an XOR gate with a NOT gate, producing the complementary output of an XOR gate. It outputs '1' when both inputs are the same (both 0 or both 1). If A=0 and B=0, Y=1. If A=1 and B=0, Y=0. If A=0 and B=1, Y=0. If A=1 and B=1, Y=1.
The NOR gate is a combination of an OR gate followed by a NOT gate. This means its output is the opposite of an OR gate's output for the same inputs. If A=0 and B=0, Y=1 (opposite of OR gate's 0). If A=1 and B=0, Y=0 (opposite of OR gate's 1). If A=0 and B=1, Y=0. If A=1 and B=1, Y=0.