COMPUTER is a programmable machine. The two
principal characteristics of a computer are:
It responds to a specific set of instruction in a
well-defined manner.
It can execute a prerecorded list of instructions (a program.)
Modern computers are electronic and
digital. The actual machinery wires,
transistors, and circuits is called Hardware; the instructions and
data are called Software.
All general-purpose computers require the following hardware components:
In addition to these components, many others make it possible for the basic
components to work together efficiently. For example, every computer requires a bus that transmits data
from one part of the computer to another.
Computers can be generally classified by size and power as follows, though
there is considerable overlap:
