If I were the inventor of a computer ...

Text 2A analogue & digital computers

find the answers to the questions below in the text underneath:

1. Into what two main classes were computing machines at first divided?

2. What does the essential difference between digital and analogue computers lie in?

3. Why are digital computers used more widely?

4. What are digital computers used for?

5. How many prob­lems can these machines solve at the same time?

6. What kind of machine may a digital computer be?

Computing machines were at first divided into two main classes: digital and analogue. The essential difference between digital and analogue computers does not lie in the machines themselves, but in the way their signals are interpreted.

An analogue computer is a device that simulates the behaviour of a physical system. The computer variables may, for example, be voltages, currents or shaft rotations.

The digital computer differs from the analogue one in that it handles numbers. The simplest digital computer is the human hand, from which the decimal system was derived. The first digital com­puter was probably the abacus, which is still used in many count­ries.

Digital computers are used more widely because of the follow­ing advantages over the analogue computers: a) a digital system is capable of greater accuracy than the analogue system and ope­rates more efficiently b) a digital system is more reliable and easier in maintenance than an analogue system.

Digital computers are used for handling problems, which require a great volume of calculations with high speed and accuracy. These machines are characterized by the ability to solve several prob­lems of different types at the same time. A digital computer or a data-processing system may be either a general-purpose or a special-purpose machine. The former is the "big brains" that solves the most difficult problems of science and engineering. The latter does only one job over and over again. It is built for only one purpose and cannot do anything else.