# 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 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.

• 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 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

# Mark-I

• 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