What is a computer?

A computer is really a very specific kind of counting machine. It can do arithmetic problems faster than any person alive. By means of electric circuits it can find the answer to a very difficult and complicated problem in a few seconds.

A computer can «remember» information you give it. It stores the information in its «memory» until it is needed. When you are ready to solve a problem, you can get the computer to sort through its stored facts¹and use only the proper ones. It works the problem with lightning speed. Then it checks its work to make sure there are no mistakes.

There are different kinds of computers. Some do only one job over and over again. These are special-purpose computers. Each specific application requires a specific computer. One kind of computer can help us build a spacecraft another kind of computer can help us navigate that spacecraft. A special-purpose computer is built for this purpose alone and cannot do anything else.

But there are some computers that can do many different jobs. They are called general-purpose computers. These are the «big brains» that solve the most difficult problems of science. They answer questions about rockets and planes, bridges and ships - long before these things are even built.

We used to think of a computer as a large machine with many buttons and flashing lights that took up a whole room. But today computers are becoming smaller and smaller and are even being put inside other devices. Though these small devices are called microcomputers or minicomputers, they are still true computers.

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