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                         Lets Know About History Of Computer

There is a long development history of the of computer and computing devices. Generally, the history of a computer development can be categorized into the following there different Eres.

1)Mechanical Calculating Eras

2)Electromechanical Era

3)Electronic Computer Eras

Mechanical calculating Era

The mechanical calculating devices were based on the counting principles. They were based on the decimal number system. These devices were constructed with the mechanical part for computing that is the counting.

The Abacus

The abacus, a simple counting device invented in Babylonia in the fourth century BC, is considered by many to be the first computing device. Abacus is made of wooden frame with stings and beads. It is divided into two parts: heaven and earth. Each bead in heaven is equivalent to 5 and each bead in earth is equivalent to 1. Calculation is done sliding the beads in both sections. Early merchants used the abacus to keep trading trading transactions. But as the use of paper and of paper and pencil spread, particularly in Europe, the abacus lost its importance. It took nearly 12 centuries, however, for the next significant advance in computing devices to emerge.

Napier's Bone

Napier's bones was invented by John Napier (1550-1617), a Scottish mathematician and scientist in 1614. In this device the bone rods are vertically arranged in a rectangular shape/ The Napier's bones, also called Napier's rods, are numbered rods which can be used to perform multiplication of any number by a number 2-9. By placing "bones" corresponding to the multiplicand next to it to the right, and product can be read off simply by adding pairs of number (with appropriate carries as needed) in the row determined by the multiplier.

There are ten bones ten bones corresponding to the digits 0-9, and a special eleventh bone that is used they represent the multiplier. The multiplier bone is simply a list of the digits 1-9 arranged vertically downward. The remainder of the bones each has a digit written in the top square, with the multiplication table for that digits written downward, with the digits split by a diagonal line going from the lower left to the upper right. In practice, multiple sets of bones were needed for multiplication of number containing repeated digits.

Slide Rule

Slide rule was invented by English mathematical William Oughtred in 1622. It is a mathematical cal-

culating device that can be used for performing numerical computa-
tions such as multiplication, division, powers, and roots. The slide rule was built on the work by Napier on logarithms. The slide rule consisted of two rulers and scale. Calculation was possible just by
sliding one scale against the another and adjusting the scale to a appropriate position. It was complex to use and only the mathematicians and engineers used this deice.

Pascaline

In 1642, Blaise Pascal the 18-year-old son of a French tax collector 

invented what he called a numerical wheel calculator to help his father with his duties. This brass rectangular box, also called a Pascaline, used eight movable dials to add sums up to eight figures 

long.

Pascal's device used a base of ten to accomplish this. For example, as one dial moved ten notches, or one compete revolution, it moved

the next dial-which represented the ten's column - one place. When the ten's dial moved one revolution, the dial representing the hundred's place moved one notch and so on. The drawback to the pascaline, of course, was its limitation  to addition.

Leibniz Machine

In 1694, a German mathematician and philosopher, Gottfried Wilhem von Leibniz, improved the Pascaline by creating machine

that could also multiply. Like its predecessor, Leibniz's mechanical  multiplier worked by a system of gears and dials. Partly by studying

Pascal's original notes and drawings, Leibniz was able to refine his 

machine.

The centerpiece of the machine was its stepped-drum gear design,

which offered an elongated version of the simple flat gear. It wasn't until 1820, however, that mechanical calculators gained widespread use.

Charles Babbage Machines

The real beginnings of computers as we know them today, however, lay with an English mathematics professor, Charles Babbage. He is known
as father of computer. He invented mainly two devices perform the methodical calculation more accurately and quickly.

Difference Engine

Babbage's first proposed a machine to perform differential equations, called a Difference Engine. Powered by steam and
large as a locomotive, the machine would have a stored program
and could perform calculations and print the results automatically.

Analytical Engine

In 1833, Charles Babbage, (English mathematician) developed Analytical Engine which a kind of a general purpose computer designed to solve any arithmetical problems. It was significant in a way that it had most of the elements present in today's digital computer systems, that's why he's called "Father of modern computer science." It incorporated the following components for the computation (counting, storing):

1) The Input: The punch card was used as an input device.
2)The Mill: It is an equivalent to CPU and used for the processing.
3)The Output: The result was given in punch cards.
4) The Storage: The punch card was also used as a punch card. It is an equivalent to memory of the today's computer.

Lady Ada Augusta, disciple of Charles Babbage, after his demise developed several program for performing mathematical calculation on Analytical engine. She is considered as the first programmer in history and hes to her credit a computer language called ADA named after her.

                                                      FIG: Lady Ada Augusta

Hollerith Machine

In 1889, an American inventor, Herman Hollerith, also applied the jacquard loom concept computing. His first task was to find a faster way to compute the U.S census. The previous census in 1880 had taken nearly seven years to count and with an expanding population, the bureau feared it 

                                                                  Herman Hollerith

Unlike Babbage's idea of using perforated cards to instruct the machine, Hollerith's method used cards to store data information which he fed into a machine that compiled the results mechanically.

Each punch on a card represented one number, and combinations of two punches represented one letter. As many as 80 variables could be stored on a single cards. Instead of ten years, census takers compiled their results in just six weeks with Hollerith's machine. In addition to their speed, the punch

cards served as a stored as a storage method for data and they helped reduce computational errors. Hollerith brought his punch card reader into the business world, founding Tabulating Machine Company in 1896, later to become International Business Machines (IBM) in 1924 after a series of mergers. Other companies such as Remington Rand and Burroghs also manufactured punch readers for business used. Both business used. Both business and government used punch cards for data processing until the 1960's.