Computer Science

In recent years, the computer industry has grow at a phenomenal pace. In a short time of 35 years or so computers have improved tremendously. In the last decade the speed of computer has increase. The cast per unit of calculating has gone down by 500 times. The storage capacity is increasing so fast that now it seems that nothing is impossible to store. Large data can be stored in very small devices.



First Generation of computer(1942-1955):-


Until 1951, electronic computers were exclusive possession of scientists and the military. Till then nobody tried to use them for business purpose. The idea of marketing them was conceived mushily and Eckert, creators of ENIAC’S. as US census bureau was already using IBCP cards, they were the pioneers in US buying this computer for the first time in 1951. the company created by M and ETS become UNIVAC division of Sperry and Corporation (later known as UNISYS).


Computer belonging to this generation had the following characteristics:

1. Comparatively large in size as composed to present day computers.
2. Generated lot of heat, they were not consistent and reliable as the valves tended to fall frequently.
3. low capacity internal storage.
4. individual, non-related models.
5. processors operated in the milliseconds speed range.
6. internal storage consisted of magnetic drum and delay lines.






Second Generation (1955-1964):

FGC were very unreliable, mainly because of vacuum tubes which kept on burning out. Users had to be prepared all the time with dizen of extra tubes to replace them. The computers of this generation were characterized by the use of Solid State devices(transistors) misted of vacuum tubes. Transistorized circuits were smaller, generated little heat, were expensive and consumed less power than vacuum tube circuits and were much greater in processing capacity.

Since transistors had a faster switching action, this generation than first generation computers. The use of magnetic cores as the primary internal storage medium and the introduction of removable magnetic disc pack were other major developments of the second generation. Although magnetic tapes were still used commonly. These computers had built in error detecting devices and more efficient means were developed to input and retrieve from the computer.



Some of the popular models in this generation of computer systems, we IBM-1401, IBM-1620, BURROUGHS B-200 SERIES, HONEY-WELL H-400, these computers were used for business applications.



Third Generation of Computer(1964-1975)

A revolution in the computer developments took place with the development of integrated circuits (IC) on a single silicon chip. In 1958, jack St Clair Kebly and Robert Noyce invented the first IC. IC incorporated number of transistors and electronic circuits on a single wafer or chip of silicon IC is called chip beause of the way they are made. They are also called as semi conductors as combining layers of materials that have varying capacity to conduct electricity from them.

This ushered in the third generation of computer systems in 1964. the integrated circuits enhanced considerably the processing capability of placing 12 or more logic gates on a single chip was developed into a well-defined technology was redefined to a point where hundreds or more gates could be placed on a chip of silicon and incorporated as functional logic block in an overall system.


Computers of this generation have the following characteristicts:


1. Smaller in size as compared to second generation computers.
2. Higher capacity internal storage.
3. Remote communication facilities.
4. Multiprogramming facilities.
5. Reduced cost of access storage.
6. Processors, which operate in nanosecond speed range.
7. Use of high level languages such as COBOL.
8. Wide range of optional peripherals.




Fourth Generation of Computer (1975-1989)


The 1970’s marked the beginning of a new generation of computers, produced by computer giants like IBM, ICL, CNR and Burrought. From design viewpoint, the new generation provided increased input-output capability, longer component life as well as greater system reliability. From the functional view point, new powerful language were developed to broaden the use of multiprogramming and multiprocessing and major shift from batch processing to on line, remote interactive processing.


The development of microprocessor chip, which contains an entire Central Processing Unit(CPU) on a single silicon chip led to the mushroom growth of inexpensive computers. They are not computers by themselves but they can perform all the functions of arithmetic logic unit and control units of the CPU. When these microprocessor are connected with memory and input-output devices, they become microcomputers.

The use of very large integrated circuits (VLSI) has made the froth generation (micro) computers very compact, much less expensive, faster, more reliable and of much greater data processing capacity than equalized third generation computers.

Some computers belonging to fourth generation are DEC-10, STAR-1000, PDP-11 AND APPLE Series Personal computers.




Fifth Generation Computers (1989-Present)

Till fourth generation of computers, the major stress was on improving the hardware from values to transistors and then to integrated circuits, which resulted in miniaturization and fast speed of computers. Hardware, the lack of thinking power has forced the scientists to work further for fifth generation computers.

The concept of “Artificial Intelligence” is being used in these computers and Japanese call them “Knowledge Processors”. Automatic programming, computational logic, pattern recognition and control of robots, the processes and which need skill and intelligence are examples of Artificial Intelligence. These computers, when developed, will have be able to execute billion of instructions per second and will have unimaginable storage capacities. The present day high level languages will become obsolete on these machines and new computer language and related software will be needed.

Computers of this generation have the following characteristics:

1.Easy to computers with high intelligence and natural human input and output mechanism;

2.Reliable and efficient software development by new languages, new computer architectures and systems software which overcome previous problems;

3.Improved overall functions and performance aimed at making computers smaller, lighter, faster, faster, of greater capacity, more flexible and more reliable