Evolution of Computers
Table of Content:
The need for a device to do calculations along with the growth in commerce and other human activities explain the evolution of computers. Computers were preceded by many devices which man-kind developed for their computing requirements. However, many centuries elapsed before technology was adequately advanced to develop computers. Some of the ancient time devices which led to evolution of computers are as follows:
Sand Tables
In ancient times, people used ?ngers to perform the calculations such as addition and subtraction. Even today, simple calculations are done on ?ngers. Soon, mankind realized that it would be easier to do cal-culations with pebbles as compared to ?ngers. Consequently, pebbles were used to represent numbers, which led to the development of sand tables. They are known to be the earliest device for computa-tion. A sand table consists of three grooves in the sand with a maximum of 10 pebbles in each groove. To increase the count by one, a pebble has to be added in the right-hand groove. When 10 pebbles were collected in the right groove, they were removed and one pebble was added to the adjacent left groove.
Abacus
Abacus is a counting device devised by the people in Asia Minor to simplify the process of counting. The word ‘abacus’ was derived from Arabic word ‘abaq’ which means ‘dust’. An abacus consists of sliding beads arranges on a rack, which has two parts, namely, upper and lower. The upper part contains two beads and the lower part contains ?ve beads per wire. The numbers are represented by the position of the beads on the rack. For example, in the upper part of the rack, a raised bead denotes 0 whereas a lowered bead denotes digit 5. In the lower part, a raised bead stands for 1 and a lowered bead for 0. The arithmetic operations such as addition and subtraction can be performed by positioning the beads appropriately.
Napier Bones
In 1614, a Scottish mathematician, John Napier made a more sophisticated computing machine called ‘Napier bones’. This was a small instrument made up of 10 rods, on which the multiplication table was engraved. It was made up of the strips of ivory bones, and so the name Napier bones. This device enabled the multiplication in a fast manner, if one of the numbers was of one digit only (e.g., 6 × 6,745). Incidentally, Napier also played a key role in the development of logarithms, which stimulated the inven-tion of slide rule, which substituted the addition of logarithms for multiplication. This was a remarkable invention as it enabled to perform the multiplication and division operations by converting them into simple addition and subtraction.
Slide Rule
The invention of logarithms in?uenced the development of another famous invention known as ‘slide rule’. In AD 1620, the ?rst slide rule came into existence. It was jointly devised by two British mathema-ticians, Edmund Gunter and William Oughtred. It was based on the principle that the actual distances from the starting point of the rule are directly proportional to the logarithm of the numbers printed on the rule. The slide rule is embodied by two sets of scales that are joined together, with a marginal space between them. This space is enough for the free movement of the slide in the groove of the rule. The suitable alliance of two scales enabled the slide rule to perform multiplication and division by a method of addition and subtraction.
Pascaline
In 1623, Wilhelm Schickard invented the calculating clock, which could add and subtract, and indi-cated the over?ow by ringing a bell. Subsequently, it helped in the evolution of Pascaline. In AD 1642, French mathematician, scientist and philosopher, Blaise Pascal invented the ?rst functional automatic calculator. It had a complex arrangement of wheels, gears and windows for displaying numbers. It was operated by a series of dials attached to wheels with each wheel having ten segments (numbered from zero to nine) on its circumference. When a wheel made a complete turn, the wheel on its left advanced by one segment. Indicators above the dial displayed the correct answer. However, usage of this device was limited to addition and subtraction only.
Analytical Engine
Analytical engine is considered to be the ?rst general-purpose programmable computer. Babbage’s innovation in the design of the analytical engine made it possible to test the sign of a computed number and take one course of action if the sign was positive and another if the sign was negative. Babbage also designed this device to advance or reverse the ?ow of punched cards to permit branching to any desired instruction within a program. Lady Ada Lovelace helped Babbage in the development of the analytical engine. She wrote articles and programs for the proposed machine. Due to her contributions, she is known as the ?rst programmer. However, Babbage never completed the analytical engine, but his proposal for this device reviewed the basic elements of modern computer such as input/output, storage, processor and control unit.
Hollerith’s Tabulator
Herman Hollerith invented the punched-card tabulating machine to process the data collected in the United States’ census. This electronic machine was able to read the information on the cards and pro-cess it electronically. It consisted of a tabulator, a sorter with compartments electronically controlled by the tabulator‘s counter and the device used to punch data onto cards. This tabulator could read the presence or absence of holes in the cards by using spring-mounted nails that passed through the holes to make electrical connections. In 1896, Hollerith founded the Tabulating Machine Company, which was later named as International Business Machines (IBM).