Historical Development of Computers
We are living in the computer age. Most of our day to day jobs are being influenced by the use of computers. It is used increasingly in each and every field of our life. In the areas of science and technology improvements can not be achieved without the use of computers. Hence it has become necessary to have basic knowledge about computers.
Strictly speaking, computer is a calculating device having certain important characteristics like speed, storage capacity, accuracy etc. But, now days it is used for many more applications other than computing. It has become an indispensible tool in the field of communications.
History of Computers:
Historians start the history of calculations with the abacus, a wooden frame with balls or beads strung on parallel wires. But, principally first such machine having principles of today’s computing machines, was developed by Charles Babbage in Nineteenth Century. It had certain basic ideas of stored computer programs in the machine. Such a machine was devised by Babbage in the year 1822 and was called difference engine. It was used to perform simple arithmetic computation needed for setting up of trigonometric and logarithmic tables. Further he developed and analytical engine around 1871 that was a prototype computer.
Meanwhile an important theoretical development occurred, around 1850, when Geroge Boole, a mathematician developed an algebraic system which is now called as Boolian Algebra. This Boolian algebraic system is used to represent quantities as binary numbers i.e 0s and 1s and also represent and manipulate logical expressions.
The significance of Boolian Algebra was not utilized at that time. In the nineteenth Century, around 1880, Hollerith developed techniques and machine that had significant impact on the future design of computers. He designed a machine in which data was represented in the form of punched holes on paper cards. This machine could work with punched cards and handled 50-80 punched cards per minute. The punched cards contained 80 columns and rectangular punches. These machines were called tabulators. These machines were also used for semiautomatic selection and sorting of cards. He set up his own company “Computer Tabulating Recording Company” which eventually became International Business Machine Corporation (IBM). Today, IBM is one of the largest companies in the computer world.
In, 1937, Howard Alken, of Harward University, designed a huge mechanical calculator called MARK I with a number of switches, mechanical relays and cards. The size was 15X 2.4 m X 0.6 m. This was the immediate predecessor of automatic electronic computers. ENIAC (Electronic Numerical Integrator and Calculator) designed in 1946was the first electronic calculator. It occupied a room of 15X 9m and its weight was 30 tons. It was water cooled and much faster than MARKXI.
Around 1950, a computer named EDVAC (Electronic Discrete Automatic Computer) was designed which was based on Neumann’s idea. (Frequently referred to as father of modern computer) He was first to use stored programme concept in computers. The storage capacity of EDVAC was 1024 words of 44 bits each. It also had an auxiliary storage of 20,000 words.
First Generation of Computers (1946-55):
The computers manufactured between 1945 -55 are called first Generation Computers. They were extremely large in size with vacuum tubes in their circuitry which generated considerable heat. Hence, special air conditioning arrangements were required to dissipate this heat.
They were extremely slow and their storage capacity was also very less compared to today’s computers. In these computers punched cards were used to enter data in to the computer. These were cards with rectangular holes punched in them using some punching devices. UNIVACI was the first commercially available computer, built in 1951 by Remington Rand Company. It had storage capacity of about 2000 words. These were used mostly for payroll, billing and some mathematical computing.
Second Generation Computers (1956-1965):
The computers, in which vacuum tubes were replaced by transistors made from semiconductors, were called second generation computers. The use of transistors reduced the heat generated during the operation. It also decreased the size and increased storage capacity. It required less power to operate and were much faster than first generation computers. Magnetic media was being used as an auxiliary storage of data. These computers used high level languages for writing computer programs. FORTRAN and COBOL were the languages used.
Third Generation Computers (1966-1976):
The third generation computers started in 1966 with incorporation of integrated circuits (IC) in the circuitry. IC is a monolithic circuit comprising a circuitry equivalent to tens of transistors on a single chip of semiconductor having a small area a number of pins for external circuit connections.
IBM 360 series computers in this generation had provision for facilitating time sharing and multiprograms also.
These were small size and cost effective computers compared to Second generation computers. Storage capacity and speed of these computers was increased many folds as include user friendly package programs, word processing and remote terminals. Remote terminals could use central computer facilities and get the result, instantaneously.
Fourth Generation Computers:
Fourth Generation Computers were introduced after 1976 and in these computers electronic components were further miniaturized through Large Scale Integration (LSI) techniques Microprocessor which are programmable Ics fabricated using LSI technique are used in these computers. Micro computers were developed by combing microprocessor with other LSI Chips, with compact size, increased speed and increased storage capacity. In recent days, Ics fabricated using VLSI (Very Large Scale Integration) techniques are used in Computers. Through this techniques, the storage capacity is increased many folds. Not only that, the speed of these computers is also very high as compared to earlier computers.
During 1980s, some computers called as super computers were introduced in the market. These computers perform operation with exceptionally high speed (approx 100 million operations per sec). This speed is attained by employing number of microprocessors consequently there cost is also very high. These are normally used in very complex application like artificial intelligence etc.