What is Computer ? ?
Introduction
A computer is device or machine for processing information according to a program - a compiled list of instructions. The information to be processed may represent numbers, text, pictures, or sound, amongst many other types.Computers are extremely versatile. In fact, they are universal information processing machines.
Computers are present in a variety of physical packages. The original computers were the size of a large room, and such enormous computing facilities still exist for specialised scientific computation - supercomputers - and for the transaction processing requirements of large companies, generally called mainframes. Smaller computers for individual use, called personal computers, are perhaps the form most people are most familiar with, and their portable equivalent the notebook computer. However, the most common form of computer in use today is the embedded computer, a (usually) small computer used to control another device.
History
Originally, a "computer" was a person who performed numerical calculations under the direction of a mathematician, often with the aid of a variety of mechanical calculating devices from the abacus onward.
During the first half of the 20th century, many scientific computing needs were met by some increasingly sophisticated, special purpose analog computers, which used a direct physical or electrical model of the problem as a basis for computation. These became increasingly rare after the development of the digital computer.
How Computer Works
While the technologies used in computers have changed dramatically since the first electronic, general-purpose, computers of the 1940s, most still use the stored program architecture (sometimes called the von Neumann architecture).The architecture describes a computer with four main sections: the Arithmetic and Logic Unit (ALU), the control circuitry, the memory, and the input and output devices (collectively termed I/O). These parts are interconnected by a bundle of wires (a "bus") and are usually driven by a timer or clock (although other events could drive the control circuitry).
Computer Applications
From the beginning, stored program computers were applied to business problems. The LEO, a stored program-computer built by J. Lyons and Co. in the United Kingdom, was operational and being used for inventory management and other purposes 3 years before IBM built their first commercial stored-program computer. Continual reductions in the cost and size of computers saw them adopted by ever-smaller organizations. And with the invention of the microprocessor in the 1970s, it became possible to produce inexpensive computers. In the 1980s, personal computers became popular for many tasks, including book-keeping, writing and printing documents, calculating forecasts and other repetitive mathematical tasks involving spreadsheets.
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