Central Processing Unit
The Main Parts of a Computer
A computer system consists of a number of different units each of which has
its own special function.
||Central Processing Unit (cpu).
All the computer functions are co-ordinated by this unit, which interprets
and carries out the instructions contained in a program.
Immediate access (or main) store
This consists of a very fast access store. Since the operation is electronic
and there are no moving parts, data can be read in nanoseconds (one thousand
millionths of a second).
This is the operational unit. Here calculations are performed and the logical
processes of selecting, sorting and comparing of information take place.
These are small stores. They hold the data to be worked on in a calculation
and give it up as instructed. Data can be transferred from one register to
This reads the information to be stored in the machine and converts it into
an electrical form which can later be used in arithmetical calculations.
Data (information) can be permanently stored away here, usually in the form
of recordings on magnetic material. It contains the vast mass of data a computer
can deal with.
This presents the results of a computer operation, often in printed form
as on a payslip. It may be presented on a television screen, tape, disc,
cassette or card.
Reproduced from "How it Works"