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Sunday, December 19, 2010

HISTORY OF COMPUTING MACHINES

INTRODUCTION

          A computer is an invention of human beings to enhance their capabilities to accomplish tasks. Modern computers are developed after a gradual change over a long period of time.
Tribal life in ancient time required man to remember a lot of information, so an early man felt the need to count the things. Then he started counting using his own fingers. However, the limited number of fingers had made it difficult for him to remember more facts. Thus, he started different methods to count using stones, sticks, scratches on a rock or wall or a knot in a string. As a result, during fifth century Hindu philosophers were able to develop a new method of counting using the numbers (digits) 0 to 9. Since there are ten digits, the Arabic Number System method was called Decimal Number System of counting. Hence, the history of computer implies the gradual change in the concept over a long period of time. Under following titles, we have explain the history of computing machines from their early forms to the most modern high speed electronic computers.


ABACUS

          In early days, people used pebbles or beads on a counting board carry out simple calculations. This tool is called the Abacus. Its exact origin is unknown. It may have originated in China, Egypt and Greece during 5000 B.C. to 2000 B.C.
The abacus employs a positional number system (Place Value Notation). The value of a bead depends on its location, the majority of abacuses use decimal system. The abacus has several rows of beads string on rigid wires fixed in a rectangular frame. The beads on the rightmost wire represent ones, on the next adjacent wire towards left represent-tens; on the third wire representing hundreds, and so on. If an abacus has 11 wires the beads in the left most wire will have a place value of 1010. A bead is counted by moving the same towards the crossbar. A bead above the cross bar is equivalent to five of these below the cross bar.
An abacus can be used to add, subtract, multiply and divide. Even today the abacus is used in many parts of the world (example China). If the operator is a skilled one, the abacus could be as fast as a desktop calculator.


NAPIER'S BONE

          In 1614, John Napier, a Scottish Mathematician, first published the first table of logarithms. It was very helpful in simplifying multiplication of large numbers.
In 1617 Napier also developed a numbered rod in order to multiply, divide and extract roots, known as Napier's bone. It was called so because it was made up of strips of bones on which numbers were painted. By the combination of these bones, direct multiplication could be done.
The Napier's bone uses the principle of performing multiplication by the addition of logarithms.
Napier constructed his Napier's bone using nine pieces of card; each divided vertically into nine squares. Each square is divided diagonally from the top right hand corner to the bottom left hand corner.


SLIDE RULE

          In 1620, Slide Rule was developed by William Oughtred, UK which is an analog device. It used the principle of logarithms.
There are two graduated scales, one scale slides or slips upon the other. With the proper alignment of the two scales, it is easy to find the product, quotient or any other function simply by viewing on the scales.
Whenever the 1 of middle scale is aligned with 2 of the top scale, we can easily read the multiple of 2 along the scale. Similarly, the division may be performed.


PASCAL'S ADDING MACHINE

         Better techniques for keeping the records by hand along with specialized calculating device continued to be developed through the centuries. The first real calculating machine that could add and subtract was a mechanical calculator called Pascal's Adding Machine or Pascaline, invented by a French scientist Blaise Pascal in 1642.
Pascal's Adding machine consisted of toothed wheels or gears with each wheel or gear heaving digits 0 through 9 engraved on it. The addition or subtraction was performed by turning these wheels. The wheels were turned in such a way that when one wheel made a complete revolution, the next adjacent wheel towards the left made one tenth of a revolution. It could be said that wheels had different place values following the decimal number system.
This machine had the capacity to add or subtract 8 - Column numbers. The maximum number that it can add or subtract is up to 9,99,99,999 and it had an automatic carry generation capacity. The disadvantage of this machine was that it could add subtract, but it could not carry out multiplication and divisions.


LEIBNIZ'S CALCULATOR

          The first calculator that could perform automatic addition, subtraction as well as multiplication and division was developed by a German philosopher Gottfried Wilhelm Von Leibniz.
It worked on the principle that multiplication and division can be accomplished by repetitive addition and subtraction respectively.
In 1694, Leibniz modified his calculator. It was also known as Stepped Reckoner. It consisted of a drum upon which teeth were mounted, nine at one end. A gear wheel was positioned on the shaft mounted along the drum. The gear wheel could be moved to mesh in with the teeth of the drum at any position.
For example to multiply by 5, the gear wheel was moved 5 positions on the drum. One revolution of the drum moved the gear wheel through 5 teeth, two revolution through 10, and so on. The carry-over mechanism was also employed. Leibniz used the new concept of binary system in a calculating machine.


JACQUARD'S LOOM

          At the beginning of the nineteenth century (i.e. A.D. 1801), Joseph Marie Jacquard of France invented a punched card as an accessory to the loom. The punched card could automate the loom for  Weaving of intricate patterns. Thus, he could control the weaving loom through the set of holes in a card, which could store the instruction for the loom. The holes could allow the wires to pass through and cause the thread to be lifted (as the wires were attached to the wrap thread in a fabric). The jacquard's loom.

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