Computer have made great in roads. Computers play a major role in all spheres of our life and are used in variety of applications: In process automation, education, medicines, research and development, business, banking, product design, space technology, communication, transport, legal system, metrology etc.
A system is a machine which is capable of performing high speed calculations and logical operations. It can also store and retrieve information instantly. It can accept input in a prescribed form, process it and give the results of the processing in a specified format as an output, using a set of instructions called ‘program’.
Evolution of computers
1. The ABACUS - The first calculating machine and earliest known computing device is ABACUS. It has beads or marbles strewn together in a wooden frame with a divider bar. The addition or subtraction is carried out by moving the beads or marbles.
2. The Slide Rule - Later, the slide rule, an analog device was invented by William Oughtred, an English mathematician. It represents numbers by length and uses the concept of logarithms.
3. Pascal’s calculating machine (Pascaline) - In 1641, the French Mathematicians Blaise Pascal, invented a mechanical calculating machine. It was called pascaline. It consists of dials and toothed wheels. In order to carry out addition/subtraction operation, the numbers to be added/subtracted are dialed and the result could be seen at a window. Due to his diversified interests, Pascal could not improve the Pascaline machine. Leibniz another great German mathematician incorporated multiplication and division operations and improved the performance of Pascaline.
4. Analytical Engine - In 1983, Charles Babbage, an English professor of mathematicians, proposed a calculating machine called Analytical Engine. This machine contained many of the concepts of present’s day computers. If developed, the machine would have taken an input, would have a storage unit, would have performed the arithmetic operations and would have given a printout of the results. Hence, for this pioneering work, Charles Babbage is known as the father of the computers. Ada Augusta Byron, daughter of the famous English poet Lord Byron, helped Babbage in his work. She is infarct considered to be the world’s first, computer programmer. ‘The programming language ADA, has been developed in her honor.
5. Punched card - Dr. Herman Hollerith, an American statistician, used punched cards for tabulating and calculating data that was collected during the census.
6. Mark-I computer - The Harvard professor, Howard Aiken developed the first electromechanical computer. Mark-I computer was a huge machine occupying several rooms. Electromechanical relays and mechanical counters were used to carry out arithmetic calculations.
7. Atanasoff-Berry computer (ABC) - Dr. John Vincent Atanasoff, professor of physics and mathematicians from Iowa state college developed the first electronic computer and called it Atanasoff Berry computer (ABC). In this computer vacuum tubes were used as storage devices.
8. Electronic Numerical Integrator and Calculator (ENIAC) - The ENIAC was built by John Mauchly. It could perform 300 multiplications per second and was the fastest machine at the time of its development. The external plug boards or switches were used to give instructions to the computer.
In 1945, von Neumann used binary numbering system for the computers in place of decimal systems.
9. Electronic delayed storage Automatic Computer (EDSAC) and Electronic Discrete Variable Automatic Computer (EDVAC)- The EDVAC and EDSAC computers used the concept of stored program developed by Coldstine, Burks and Von Neumann. These computers were also called stored programs computers. A punched paper tape was used to store the computer program.
10. UNIVersal Automatic Computer (UNIVAC) - The UNIVAC was developed by Eckert and Mauchly magnetic tapes were used for data input and output operations.
11. Generation of computers-
The first generation computer (ENIC, EDVAC, EDSAC, UNIVAC) were bulky and occupied lot of space. They were built up of vacuum tubes. Hey produced lot of heat and there were frequent breakdowns or faults.
The second generation computer (IBM 1401) used transistors in place of vacuum tubes. The relays were replaced by magnetic core storage device. The drawbacks in the first generation computers namely, large size and frequent failures and large heat generation are alleviated in the second generation computers. The second generation computers were compact in size and consumed less power. The sped of operations is also increased.
The third generation computers (IBM 360, 370 series) were characterized by the use of integrated solid state circuiting, new inputs and output devices and improved storage devices. These computers became very compact in size. The arithmetic and Logic operations were carried out in milliseconds.
The fourth generation computer made use of Large Scale Integration (LSI) and Very Large Scale Integration (VLSI) based chips. This led to the development of microprocessor based minicomputers and microcomputers.
The fifth generation computers provided advanced hardware with higher speeds and higher storage capacities. They incorporate artificial intelligence and expert systems. The other features include, use of new computer languages, advancement in man-machine communication, input/output devices incorporating speech recognition and recognition of handwritten characters etc.