For centuries machines have been designed to perform specific tasks. For example, a washing machine washes clothes, a weaving machine weaves cloth, an adding machine adds numbers, and so on. The computer has changed all that.
The computer is a machine that does nothing—until it is given instructions on what to do. So your computer can play games, draw pictures, or calculate π to a million decimal places; it all depends on what program (or instructions) you give the computer. The computer can do all this because it is able to accept instructions and logically change those instructions based on incoming data. This versatility makes computers useful in nearly every aspect of human endeavor.
The idea of a computer was described theoretically in the 1940's by the mathematician Allan Turing in what he called a universal machine. In 1945 the mathematician John Von Neumann, extending Turing’s ideas, built one of the first electronic computers.
Mathematicians continue to develop new theoretical bases for the design of computers. The heart of the computer is the “chip,” which is capable of processing logical instructions. To get an idea of the chip’s complexity, consider that the Pentium chip has over 3.5 million logic circuits!
(http://sw.daffodilvarsity.edu.bd/mod/file/thumbnail.php?file_guid=127520&size=large)
Alan Turing (1912-1954)
(http://sw.daffodilvarsity.edu.bd/mod/file/thumbnail.php?file_guid=197430&size=large)
John von Neumann with the stored-program computer at the Institute for Advanced Study, Princeton, New Jersey, in 1945.
Further reading
Saba Fatema Alan Turing: The Master of Code Breaking http://forum.daffodilvarsity.edu.bd/index.php?topic=9702.msg38548#msg38548