basic computer

What is computer?
Computer is a faster working electronic, programmable, data processing device. Computer cannot do anything independently. It acts on the instructions from the user and processes it, gives the result in the desired form.
Application of computer
Some of the applications of the computer are given below.
Maintenance of accounts and producing reports.
Purchasing and stock control in super markets and factories.
Library book issue management and information retrieval.
Computer aided diagnosis of diseases.
Bank accounts and instant customer service.
Organization of examinations and tabulation of results.
Computer aided design of building, plants, and machinery.
Weather forecasting.
Computer controlled machines.
Computer aided learning.
Word processing and desk top publishing.
Crime detection – finger print processing and image processing.

Computer system characteristics:

Perform complex and repetitive calculations rapidly and accurately.
Storage large amounts of data and information for subsequent manipulations.
Hold a program of a model which can be explored in many different ways.
Make decisions.
Provide information to the user.
Automatically correct or modify – by providing signals – certain parameters of a system under control.
Draw and print graphs, and
Converse with users through terminals.
Computer Generations
First generation computers: 1947-1958

The first electronic computer was completed in 1946 by a team led by J. Prosper Eckert and John Mauchly. This computer was called ENIAC ( Electronic Numerical Integrator and Calculator). It used high-speed vacuum tube switching devices. Some other computers also developed in this period.
All the first generation computers possessed the following characteristics as compared to the later models:
Large in size
Slow operating speeds
Restricted computing capacity
Limited programming capabilities
Short life span
Complex maintenance schedules
Second generation computers: 1959 – 1965
In the second generation computers, there were used transistors instead of vacuum tubes. These transistors were made of germanium semi-conductor material. These computers were much faster and more reliable than their earlier counterparts. Further they occupied less space, required less power, and produced much less heat.
Third generation computers: 1965 – 1976
In this generation computers, the chief improvement was the replacement of germanium, transistors by silicon transistors. A single chip of silicon had on it integrated circuits consisting of transistors, resistors and capacitors. The single chip eliminated the need for wired interconnections between components, from small scale integrated circuits (SSI) which had only about 100 transistors, technology developed to medium scale integrated circuits with 1000 transistors per chip.
Consequently, the switching speed of the circuits went up, reliability increased, power dissipation decreased and the machine became much smaller. The effect of these was the emergence of extremely powerful CPUs with the capacity of carrying out one million instructions per second.
Forth generation computers: 1976 – present
The fourth generation computers use micro-processor chips. Very large scale integrated (VLSI) circuits packing about 10000 to 100000 transistors on a single chip have come into existence. A large number of microprocessors are being manufactured now.
Disk memory has become very large in size. Secondary storage devices like floppy disks and tapes provide low cost and high capacity peripheral memory. Networks of computers have been developed.
Programming languages also have become more powerful. Many new languages have emerged.
Fifth generation computers: ( under research )
Japan and many other countries are working on systems what are known as expert systems which will considerably improve the man-machine interaction. In it the artificial intelligence technology is used. Fifth generation computers are nothing but robot. These systems are very expensive.