Computers is a machine for manipulating data
according to a list of instructions. Computers takes numerous physical forms. Early electronic computers
were the size of a large room, consuming as much power as several
hundred modern personal computers. [1] Today, computers can be made
small enough to fit into a wrist watch and be powered from a watch
battery. Society has come to recognize personal computers and their
portable equivalent, the laptop computer, as icons of the
information age; they are what most people think of as "a computer".
However, the most common form of computer in use today is by far the
embedded computer. Embedded computers are small, simple devices that
are often used to control other devices�for example, they may be
found in machines ranging from fighter aircraft to industrial robots,
digital cameras, and even children's toys.
The ability to store and execute programs makes
computers extremely versatile and distinguishes them from
calculators. The Church�Turing thesis is a mathematical statement of
this versatility: Any computer with a certain minimum capability is,
in principle, capable of performing the same tasks that any other
computer can perform. Therefore, computers with capability and
complexity ranging from that of a personal digital assistant to a
supercomputer are all able to perform the same computational tasks
as long as time and storage capacity are not considerations.