## Introduction Logic Gates:

Aristotle, the founder of European logic, and later the mathematician Leibniz, believed that the fundamental principles of logic could be expressed in mathematical language.

Then the scientist George Boole (1815-1864) successfully expressed this concept of logic in mathematical language. George Boole, through his various research papers, established the logic-based algebra containing the new concept, later known as Boolean algebra. In 1904 E. V. Huntington defined Boolean algebra by creating axioms or initial conditions of Boolean algebra. Claude Shannon first used Boolean algebra in practical applications. Shannon Pathom applies switching algebras. The on state of the switch is denoted by switch 1 (Switch-on) and the off state by switch off 0 (Switch-off).

## Switch of Logic in Boolean Algebra:

In general algebra we use the functions +, -, x and ÷ etc. But in the case of Boolean algebra, functions like AND, OR and NOT are used and are called logic gates.

## AND Function:

An electronic circuit in which two or more switch classes are cooperatively connected is expressed by the AND function. The diagram or symbol of the AND gate is shown in the figure. The two inputs are A and B and the output is F. An AND gate with three inputs A, B and C has only one output F. AND gate can have more than three inputs. An end gate with N number of inputs is shown.

If the AND gated truth table has two variables A, B, the number of rows of the truth table will be 2² = 4, the number of rows of the truth table with three variables A, B and C will be 2³ = 8. End gates are logical multiplication operations expressed by the dot (.) symbol.

In the case of AND gate, if all the inputs are 1, then the output will be 1. In all other cases, the output will be 0. The following table shows two three-input end gates.

## OR Function:

An electronics circuit in which two or more switches are connected in parallel is expressed by the OR function.

The diagram or symbol of the OR gate is shown in the figure. Two inputs are A and B and output is F. An OR gate with three inputs A, B and C has a single output F. OR gate can have more than three inputs. A diagram of N number of connected OR gates is shown.

OR gate is a logical addition operation which is expressed by (+) sign so in case of OR gate any input is 1 then the output will be 1. Only if all inputs are 0 will the output be 0. The truth table of the OR gate has two and three rows, the number of rolls of the two table will be 2² = 4 and 2³ = 8 respectively. The truth table with two and three inputs is shown below.

## NOT Function:

The NOT function always has an input and an output. The output is always the exact opposite or complement of the input. NOT function A is input and output is Ā. This operation is called complementation or inversion. A is the input and f = Ā is the output in the diagram of NOT gate shown in figure.

Since the input of a NOT gate is always opposite to the output. If the input is 0, the output will be 1, but if the input is 1, the output will be 0. Truth table for NOT gate is shown next.

## Frequently Asked Question (FAQs):

### What is Logic Gate?

Then the scientist George Boole (1815-1864) successfully expressed this concept of logic in mathematical language. George Boole, through his various research papers, established the logic-based algebra containing the new concept, later known as Boolean algebra. In 1904 E. V. Huntington defined Boolean algebra by creating axioms or initial conditions of Boolean algebra.

### AND Function

An electronic circuit in which two or more switch classes are cooperatively connected is expressed by the AND function. The diagram or symbol of the AND gate is shown in the figure.

### OR Function

An electronics circuit in which two or more switches are connected in parallel is expressed by the OR function.

### NOT Function

The NOT function always has an input and an output. The output is always the exact opposite or complement of the input. NOT function A is input and output is Ā.