• shrey mittal

Logic Gates | Integrants of Digital World

Updated: Aug 19, 2020

Have you ever wondered how does your laptop machine does so much in such less time? Or have you gaped how does your laptop just displays the character on screen that we teletype on the keyboard?

I bet you have because everyone does that, if not, then, I guess I am special. The logic gates are the answer; they are the building blocks of an electronic device.

They are like the cells for an electronic device as every organ is made of cells. Every device is made by #LogicGates.

What are logic gates?

A logic gate is a physical electronic device implementing a #Boolean function, a logical operation performed on one or more binary inputs that produce a single binary output.

The basic gates are AND, OR, and NOT.

The keyboard through which I am typing this is a mere example. Even a key of a keyboard is made of several networks of logic gates.

They can be constructed using diode transmitters, and in older times vacuum tubes were used. Logic gates bind up to form multiplexers, resisters, etc. These add up to form microprocessors. RAM is made of millions of resistors so you can assume how vital is a logic gate.

History about Logic gates

The logic gates were mechanically made. In 1837, Charles Babbage concocted the Analytical Engine. Electromagnetic transfers were later utilized for logic gates.

In 1924, Walther Bothe, got part of the Nobel Prize in physics in the year 1954, for the first modern electronic AND gate.

Utilizing this property of electrical switches to apply logic is the essential idea that underlies all electronic computerized PCs.

Even many tech labs are researching on making more transistors from these circuits and they are reaching their goal. So I guess we should all thank George Boole for giving us #Boolean algebra and introducing us to logic gates otherwise we would have a more difficult life. I believe that we should take from the past and give it to the future so let's get started.

Electronic Gates

Electronic gates can be connected together to form a logic gate function with any desired number of inputs, or to form combinational and sequential type circuits from standard gates.

These gates can be combined into more useful gates like NAND, NOR.

NAND is a combination of NOT and AND gate. NOR gate is a combination of NOT and OR gate also known as a universal gate as any other gate can be formed using this gate. These gates exert the input as 1 and 0 or we can say true or false respectively.

AND gate returns true only when both the inputs are true. OR gate returns false only when both the cases are false.

There are 2 more important digital logic gates XOR and XNOR gate. They are also called biconditional gates and majorly used in devices. XOR gate allows electricity to pass only when the inputs are different and false when inputs are true. XNOR gate is true when vales are the same and false when they are different.

Types of Logic Gates:

OR Gate

If any of the input is high, then the output is high.

NOR Gate

If both the inputs are low, then the output is high, otherwise low.


If both the inputs are high, then the output is low, otherwise high.

XOR Gate

If both the inputs are high or low, then the output is low, otherwise high.


If both the inputs are high or low, then the output is high, otherwise low.

NOT Gate

The output is inversely proportional to the input.

Uses of logic gates :

  1. They are the basic building block of a digital computer.

  2. They are used to make microprocessors, microcontrollers, embedded systems.

  3. They are used to make switches and electronic circuits as well.

  4. They are basically used in every digital and electronic device.

See Also

  1. NAND Gate as a Universal Gate

  2. NOR Gate as a Universal Gate

  3. EX-NOR gate using transistor







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