Logic - Basic Gates
The NOT Gate
The Not Gate performs the operation called inversion.
The NOT operation changes one logic level to the opposite logical level. When the input is Low, the output is high. When the input is high, the output is low.
It effectively flips the bit! (0 becomes 1 and 1 becomes zero)
The Symbol
The Truth Table
The Logical Expression
X = NOT A
X = Ā
The AND Gate
An AND gate has two inputs and performs what is know as multiplication.
The output of AND gate is high when all inputs are high otherwise all outputs are low.
The Symbol
The Truth Table
The Logical Expression
X = A AND B
X = A.B
The OR Gate
OR gate has two inputs and performs what is known as logical addition.
The output of OR gate is Low when all inputs are low, otherwise all outputs are high.
The Symbol
The Truth Table
The Logical Expression
X = A OR B
X = A+B
The XOR Gate
XOR gate has inputs and performs what is known as true addition.
The output of an XOR gate is High when only 1 input is High. The output is Low if both inputs are the same.
The Symbol
The Truth Table
The Logical Expression
X = A Not Equal to B
X = A⊕B