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.
Abacus
 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 beadand 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.
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 
MarkI

Prof. Howard Aiken in U.S.A constructed in 1943 constructed an electromechanical computer named MarkI

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