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• He invented a working model of the mechanical computer, called the Difference Engine in
1822 and Analytical Engine in 1837.
• The Analytical Engine had four units-Mill , Store , Reader and Printer .

• These units worked like a modern computer. All the computers that are used nowadays, are
based on them.
• The Store was used for storing the data and Mill was the calculating unit.

• The Reader and Printer were input and output devices.

Difference Engine Analytical Engine

Boolean Logic
George Boole was an English mathematician. He realised that complex mathematical
problems could be solved by reducing them to a series of questions having either positive or
negative answers. He linked them with the binary number system and represented the
positive results by 1 and negative ones by 0. This theory of Boolean Logic became the
fundamental principle for the design of computer circuitry.

ELECTRONIC COUNTING DEVICE

Tabulating Machine
• Herman Hollerith, an American statistician, invented the
machine called the Tabulating Machine.

• It was capable of reading data, processing it and giving
the desired output.
• The input was given through punched cards.
• The punched cards were used to record and store data or
information.
Tabulating Machine

MODERN CALCULATING DEVICES OR COMPUTERS

Mark I
• Howard Aiken was the primary engineer in IBM, who
developed the first Automatic Sequence Controlled
Calculator, the Mark I in 1944.

• It was capable of executing long computations
automatically.
Automatic Sequence
13 Controlled Calculator