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The history of computer can be traced to mechanical age i.e there were mechanical devices for the calculation purpose. We can divide computer history in to 3 phase.

• Mechanical era
• Electro-mechanical Era.
• Electronic Era.

### Mechanical Era

#### Abacus:

It is a mechanical device that can be used as an aid for performing mathematical calculation. It was first used between 1000BC to 500 BC in ancient China Egypt etc. to count the cattle. The first Abacus was believed to be made with flat stone covered with sand or dust later on it was made from wood. It consist of two parts one above another. The upper part is called heaven and lower part consists of five bits and upper part consists of 2 beats.

#### Napier's Bone:

It is also called Napier rod and it was invented by Scottish mathematician John Napier. The Napier Bone is numbered rod which could be used to perform multiplication. John Napier is also remembered as the inventor of logarism.

#### Slide Rule:

A slide rule is a mechanical analogy device that can be used for making numerical computation and reading such as multiplication, division, finding power, root functions such as logarism and trigonometry .

#### Pascaline ( Pascal's machine)

It was developed by Blaise Pascal in 1642 A.D. It could add and subtract only by entering numbers by manipulating its dials. It counted whole number by the logs or teeth on a log wheel.

#### Analytical Engine:

It was invented by British mathematician Charles Babbage in 1842. The analytical engine was general purpose mechanical computer and it contained all components as below.

• The store ( equivalent to memory)
• The mill ( equivalent to CPU)
• The input section using punch card.

Since he gave the concept of memory in calculating device for first time, he is regarded as the "Father of Computer".

### Electro-mechanical Era:

In this era electricity was used in computer devices and they were partly programmable. Some of the parts of these computers consist of mechanical parts too... example: mark - I, ABC, Zuse etc.

#### Mark-I

It was developed by Howard Aiken and Grace Hopper at Harvard University USA. It was built by IBM in 1944 Ad and was brought into operation unit 1959. This giant computer was about 5 ton weight with dimension 51 feet long and 8 feet height and 240 feet depth . This huge device was used by U.S Navy for gunnery and ballistic calculation. This computer could carry out addition, subtraction, multiplication, division and reference to previous result. It had special subroutine for logarism and trigonometry functions. This computer worked in decimal number system and not binary. Mark- I is assumed us modern embodiment of Babbage Analytical Engine.

### Electronic Era:

In electronic era electronic circuit elements replace mechanical devices and calculations were purely digital and only done with electronic circuits. Examples: ENIAC, COLOSSUS, EDVAC, EDSAC, UNIAC etc...

#### ENIAC (Electronic Numerical Integrator And Calculator):

It was developed by John Mauchly and John Presper Eckert in 1946. The American military has sponsored their research. It was made up of 17468 vaccum tubes, 17,000 resistors, 10000 capacitor, 1500 relay and 600 manual switches. It covered 1800 sq.ft , weighed 30 tons and consumed 160 kw of electrical power. It could perform 5000 addition, 357 multiplication or 38 division. This computer was faster than earlier computer as it used vaccum tubes instead of mechanical switches and relays.

• There are mechanical, electro-mechanical era, and electronic era.
• In mechanical era abacus, slide rule, Napier's bone, pascaline, and analytical engine were developed.
• In Electro–mechanical Era mark-1 was developed.
• In Electro–mechanical Era ENIAC, COLOSSUS, EDVAC, EDSAC, UNIAC etc. were developed.
.

#### Click on the questions below to reveal the answers

Mark-I was the first electro mechanical computer developed by Howard Aiken. It was named as ASCC and was 8 ft high, 51 ft long and 2ft wide. It used more than 7 lakh 50 thousand parts and weighed more than 32 tons.

History of computer is based on mainly calculation devices. Therefore it is classified into the following three eras:

• Mechanical era.
• Electro-mechanical era.
• Electronic era.

Abacusis the first counting device, developed by Chinese and Egyptians, 2500 years ago. It performs mathematical concepts and arithmetical operations. It is a rectangular box, divided into two parts by mid bar , upper part is called heaven, consists of two beads and each bead equal to value 5 and lower part is is called earth, consists of five bead and each bead equal to value 1.

Napier's bone is multiplication tool invented in 1614 by mathematical John Napier of Scotland. The bones are a set of vertical rectangular rods, each one divided in 10 squares. John Napier is also the inventor of logarithms, a concept used to change multiplication into addition. Napier's bones was very successful and was widely used in Europe until mid 1960's. It is mainly used for multiplication table.

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• ### Which of the following is not the phase of computer history ?

Mechanical era
Electronic Era
Electro-mechanical Era.
Artificial Era
• ### Pascaline was developed in __ __ ..

Electro-mechanical Era
Electronic Era
Can't say
Mechanical era
• ### The upper part of Abacus is known as __ .

Heaven
Earth
Hell
None of these

The store
punch card
The mill

EDSAC
UNIAC
Mark- I
EDVAC