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 processes 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 keeps the information in its «memory» until it is needed.
There are different kinds of computers. Some can do only one job. These are special-purpose computers. Each specific problem requires a specific computer. One kind of computer can help us to build a spaceship, another kind can help us to navigate it. 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.
Our grandparents used to think of a computer as a large machine that took up a whole room. But today computers are becoming smaller and smaller. Though these small devices are called microcomputers or minicomputers, they are still true computers.
The most important parts of a general-purpose computer are as follows:
1) memory, where information is kept;
2) an arithmetic unit for performing calculations;
3) a control unit for the correct order of operations;
4) input devices;
5) output devices for displaying the results of calculations.
The input and output devices are called peripherals.
There are several advantages in making computers as small as one can. Sometimes weight is particularly important. A modern plane carries many heavy electronic apparata. If it is possible to make any of them smaller, it can carry a bigger weight. But weight is not the only factor. The smaller the computer is, the faster it can work. The signals go to and from at a very high but almost constant speed.
Some of the first computers cost millions of dollars, but people quickly learned that it was cheaper to let a million dollar computer make the necessary calculations than to have a hundred clerks trying to do the same by hand. Scientists found out that computers made fewer mistakes and could fulfill the tasks much faster than almost any number of people using usual methods. Computers became popular. As their popularity grew the number of factories producing them also grew.