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 Computer
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.
Types of Computer :
Personal computer: a small, single-user computer based on a microprocessor. In addition to the microprocessor, a personal computer has a keyboard for entering data, a monitor for displaying information, and a storage device for saving data.
workstation: a powerful, single-user computer. A workstation is like a personal computer, but it has a more powerful microprocessor and a higher-quality monitor.
minicomputer: a multi-user computer capable of supporting from 10 to hundreds of users simultaneously.
mainframe: a powerful multi-user computer capable of supporting many hundreds or thousands of users simultaneously.
supercomputer: an extremely fast computer that can perform hundreds of millions of instructions per second.
