What is Computer?

A computer is an electronic machine or device that can be programmed to carry out sequences of arithmetic or logical operations automatically.


A computer is an electronic machine or device that performs processes, calculations and operations based on instructions provided by a software or hardware program. It has the ability to accept data (input), process it, and then produce outputs.

What is full form of Computer?

COMPUTER: – Common Operating Machine Purposely Used for Technological and Educational Research.

History of Computer

Before computers were developed people used sticks, stones, and bones as counting tools. As technology advanced and the human mind improved with time more computing devices were developed like Abacus, Napier’s Bones, etc. These devices were used as computers for performing mathematical computations but not very complex ones


Around 4000 years ago, the Chinese invented the Abacus, and it is believed to be the first computer. The history of computers begins with the birth of the abacus.

Structure: Abacus is basically a wooden rack that has metal rods with beads mounted on them.

Working of abacus: In the abacus, the beads were moved by the abacus operator according to some rules to perform arithmetic calculations. In some countries like China, Russia, and Japan, the abacus is still used by their people.

Napier’s Bones

Napier’s Bones was a manually operated calculating device and as the name indicates, it was invented by John Napier. In this device, he used 9 different ivory strips (bones) marked with numbers to multiply and divide for calculation. It was also the first machine to use the decimal point system for calculation.


It is also called an Arithmetic Machine or Adding Machine. A French mathematician-philosopher Blaise Pascal invented this between 1642 and 1644. It was the first mechanical and automatic calculator. It is invented by Pascal to help his father, a tax accountant in his work or calculation. It could perform addition and subtraction in quick time. It was basically a wooden box with a series of gears and wheels. It is worked by rotating wheel like when a wheel is rotated one revolution, it rotates the neighbouring wheel and a series of windows is given on the top of the wheels to read the totals.

Stepped Reckoner or Leibniz wheel

A German mathematician-philosopher Gottfried Wilhelm Leibniz in 1673 developed this device by improving Pascal’s invention to develop this machine. It was basically a digital mechanical calculator, and it was called the stepped reckoner as it was made of fluted drums instead of gears (used in the previous model of Pascaline).

Difference Engine

Charles Babbage who is also known as the “Father of Modern Computer” designed the Difference Engine in the early 1820s. Difference Engine was a mechanical computer which is capable of performing simple calculations. It works with help of steam as it was a steam-driven calculating machine, and it was designed to solve tables of numbers like logarithm tables.

Analytical Engine

Again in 1830 Charles Babbage developed another calculating machine which was Analytical Engine. Analytical Engine was a mechanical computer that used punch cards as input. It was capable of performing or solving any mathematical problem and storing information as a permanent memory (storage).

Tabulating Machine

Herman Hollerith, an American statistician invented this machine in the year 1890. Tabulating Machine was a mechanical tabulator that was based on punch cards. It was capable of tabulating statistics and record or sort data or information. This machine was used by U.S. Census in the year 1890. Hollerith’s Tabulating Machine Company was started by Hollerith and this company later became International Business Machine (IBM) in the year 1924.

Differential Analyzer

Differential Analyzer was the first electronic computer introduced in the year 1930 in the United States. It was basically an analog device that was invented by Vannevar Bush. This machine consists of vacuum tubes to switch electrical signals to perform calculations. It was capable of doing 25 calculations in a few minutes.

Mark I

In the year 1937, major changes began in the history of computers when Howard Aiken planned to develop a machine that could perform large calculations or calculations involving large numbers. In the year 1944, Mark I computer was built as a partnership between IBM and Harvard. It was also the first programmable digital computer marking a new era in the computer world.

Generations of Computers

First Generation Computers

In the period of the year 1940-1956, it was referred to as the period of the first generation of computers. These machines are slow, huge, and expensive. In this generation of computers, vacuum tubes were used as the basic components of CPU and memory. Also, they were mainly dependent on the batch operating systems and punch cards. Magnetic tape and paper tape were used as output and input devices. For example, ENIAC, UNIVAC-1, EDVAC, etc.

Second Generation Computers

In the period of the year, 1957-1963 was referred to as the period of the second generation of computers. It was the time of the transistor computers. In the second generation of computers, transistors (which were cheap in cost) are used. Transistors are also compact and consume less power. Transistor computers are faster than first-generation computers. For primary memory, magnetic cores were used, and for secondary memory magnetic disc and tapes for storage purposes. In second-generation computers, COBOL and FORTRAN are used as Assembly language and programming languages, and Batch processing and multiprogramming operating systems were used in these computers.

For example, IBM 1620, IBM 7094, CDC 1604, CDC 3600, etc.

Third Generation Computers

In the third generation of computers, integrated circuits (ICs) were used instead of transistors (in the second generation). A single IC consists of many transistors which increased the power of a computer and also reduced the cost. The third-generation computers are more reliable, efficient, and smaller in size. It used remote processing, time-sharing, and multiprogramming as operating systems. FORTRON-II TO IV, COBOL, and PASCAL PL/1 were used which are high-level programming languages.

For example, IBM-360 series, Honeywell-6000 series, IBM-370/168, etc.

Fourth Generation Computers

The period of 1971-1980 was mainly the time of fourth generation computers. It used VLSI (Very Large Scale Integrated) circuits. VLSI is a chip containing millions of transistors and other circuit elements and because of these chips, the computers of this generation are more compact, powerful, fast, and affordable (low in cost). Real-time, time-sharing and distributed operating system are used by these computers. C and C++ are used as the programming languages in this generation of computers.

For example, STAR 1000, PDP 11, CRAY-1, CRAY-X-MP, etc.

Fifth Generation Computers

From 1980 – to till date these computers are used. The ULSI (Ultra Large-Scale Integration) technology is used in fifth-generation computers instead of the VLSI technology of fourth-generation computers. Microprocessor chips with ten million electronic components are used in these computers. Parallel processing hardware and AI (Artificial Intelligence) software are also used in fifth-generation computers. The programming languages like C, C++, Java, .Net, etc. are used.

For example, Desktop, Laptop, NoteBook, UltraBook, etc.

What are the types of computers?

There are six core classifications of computers:

  1. Microcomputers, or Personal Computers
  2. Minicomputers
  3. Mainframe Computers
  4. Supercomputers
  5. Workstation Computers
  6. Servers