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Evolution of Computers

  • The concept of a computer did not materialize overnight.

  • Ancient people used stones for counting or made scratches on a wall or tied knots in a rope to record information.

  • These data were manually computed.

  • Let us discuss about various development stages of computers.


  • The History of computers began by 3500BC, when the Babylonian merchants kept track of their business in clay tablets.
  • This led to the invention of abacus, the first manual calculating device.
  • In 1642, a young French man called Blaise Pascal invented the first mechanical calculating device
  • The Mesopotamians discovered the earliest form of a bead-and wire counting machine called abacus.
  • The abacus consists of beads divided into two parts which are movable on the rods of the two parts.
  • It performs addition, subtraction, multiplication and division.
  • The following figure shows the appearance of an abacus.

The Abacus

Note: Abacus is a Latin word that is originated from the Greek word abax or abakon (meaning "table" or "tablet")

Napier's 'Logs' and 'Bones'

  • John Napier developed the idea of Logarithm.

  • It is an abacus used for calculating products and division by using logs.

  • Logs are used to transform multiplication problem to addition problem.

  • This mechanism is later called as slide rule.

  • Using this, the Square root of any value can be found.

Pascal's Adding Machine

  • In 1640 Blaise Pascal conceives the first arithmetic machine in history.
  • It was made up of gears to add the numbers quickly.
  • It is also known as Pascaline
  • It is special for the nonreversible mechanism constrains to use a special technique for the subtraction.
  • It has two sets of numerical figured wheels in the opposite direction.
  • It works on clock work mechanism principle
  • It is capable of carry transfer automatically.

Pascal's Adding Machine

Leibnitz's Calculator

  • Gottfried Wilhelm von Leibnitz, successfully introduced an automatic calculator machine in the business place, in 1671.

  • It is able to perform multiplication and division as well.

  • It performs multiplication through repeated addition and division through repeated subtraction.

  • It works based on the wheels placed at the right angle, and displaced by a special stepping machine.

  • The stepped cylinder consists of nine teeth of varying lengths instead of wheels as was used by Pascal

Leibnitz's Calculator

Jacquard's Loom

  • In 1801 Joseph Marie Jacquard generated a punched card controlled loom that enables one person to generate fabric in a fraction of time automatically.
  • The entire operation was under a program's control.
  • The storing and retrieving of information started the great influence in the later era.

Jacquard's Loom

Babbage's Difference Engine

  • Charles Babbage a mathematical professor invented a long calculation machine with repeatable action in 1822.
  • It is powered by steam.
  • It is expected to perform logarithmic calculations.
  • The machine was capable of polynomial evaluation by finite difference and its operation was automatic multishop operation.

Babbage's Difference Engine

Babbage's Analytical Engine

  • In 1833, Charles Babbage designed Analytical Engine.
  • It has the basic principles of today's computer technology.
  • It performs all the four arithmetic operations.
  • It has the concept of central processor, storage area, memory and input and output devices.
  • It has two specialties like compression and modification of stored information.
  • With the invention of Difference engine and Analytical engine earned Babbage the title "Father of modern computer".

Babbage's Analytical Engine

Hollerith's Machine

  • In 1887, Herman Hollerith invented the first electromechanical punched card tabulator.
  • These machines was used by American Department of Census to compile their 1880 census data and were able to complete compilation in 3 years which already took 10 years to complete.
  • It used punched cards to give input and display output.

Hollerith's Machine

Note: Hollerith's Machine is also called as Tabulating Machine


  • Prof. Howard Aiken in U.S.A constructed in 1943 constructed an electromechanical computer named Mark-I

  • It uses a 10 digit number in 5 seconds at a time.

  • It works according to the pre programmed instruction.

  • This was the first operational general purpose computer.

Mark- I computer

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