What is a computer?

The word computer comes from a Latin word which means to count. A computer is a machine with a complex network of electronic circuits that operate switches or magnetize tiny metal cores. The switches, like the cores, are capable of being in one of two possible states, that is, on and off; magnetized or demagnetized. The machine is capable of storing and manipulating numbers, letters, and characters. The basic idea of the computer is that we can make the machine do what we want by inputting signals that turn certain switches on and turn others off, or that magnetize or do not magnetize the cores.

The basic job of computers is the processing of information. For this reason, computers can be defined as devices which accept information in the form of instructions called a program and characters called data, perform mathematical and/or logical operations on the information, and then supply results of these operations. The program, or part of it, which tells the computers what to do and data, which provide the information needed to solve the problem, are kept inside the computer in a place called memory.

For outputting information, two common devices used are a printer which prints the new information on paper, or a CRT display screen which shows the results on a TV-like screen.

There are different kinds of computers. Some do only one job over and over again. These are special-purpose computers. 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. Computers help our space program, our business and industry, medicine and education. They are powerful tools which help to change our life and the world around us.

Electronic computers.

Electronic circuits work a thousand times more rapidly than nerve cells in the human brain. A problem that takes the human brain 2 years in order to solve it can be solved by a computer in one minute. The heart of the electronic computer is its transistors. In order to work a computer must have instructions; this is called “programming”.

There are two main types of electronic computers: analogue and digital. In analogue computers problems are solved by analogy, the problems which analogue computers can solve are the following: mechanical forces, speeds, rotations, etc. Analogue computers are used for investigation of mechanical processes, in general, they are used for scientific and engineering problems in which great accuracy is not required but answers accurate enough are required quickly.

In digital computers problems are solved by counting. They may be very large and powerful. All the data connected with the problem which must be solved are converted into electrical pulses by very fast electronic switches and these pulses are stored and counted. With modern electronic devices a single switching operation can take place in a few nanoseconds (a nanosecond is a thousand — millionth of a second).