computer
What is a Computer?
A computer is a programmable machine. The two principal characteristics of a computer are: it responds to a specific set of
instructions in a well-defined manner and it can
execute a prerecorded list of instructions (a
program).
Modern Computers Defined
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.
Computer Classification, By Size and Power
Computers can be generally classified by size and power as follows, though there is considerable overlap: