Microprocessor-based system

This is any system that contains a microprocessor, and does not
necessarily have anything to do with computing. In fact, despite all the
hype, computers use only a small proportion of all the microprocessors
manufactured. Our garage door opening system is a
microprocessor-based system or is sometimes called a microprocessorcontrolled
system.

Microcomputer

The particular microprocessor-based systems that happen to be used
as a computer are called microcomputers. The additional circuits
required for a computer can be built into the same integrated circuit
giving rise to a single chip microcomputer.

Microcontroller

This is a complete microprocessor-based control system built onto a
single chip. It is small and convenient but doesn’t do anything that
could not be done with a microprocessor and a few additional
components. We’ll have a detailed look at these in a later chapter.

MPU and CPU

An MPU is a MicroProcessor Unit or microprocessor. A CPU is a
Central Processing Unit. This is the central ‘brain’ of a computer and
can be (usually is) made from one or more microprocessors. The IBM
design for the ‘Blue Gene’ supercomputer includes a million
processors!

Micro

The word micro is used in electronics and in science generally, to
mean ‘one-millionth’ or 1  10–6. It has also entered general language
to mean something very small like a very small processor or
microprocessor. It has also become an abbreviation for microprocessor,
microcomputer, microprocessor-based system or a micro
controller – indeed almost anything that has ‘micro’ in its name. In the
scientific sense, the word micro is represented by the Greek letter 
(mu). It was only a small step for microprocessor to become
abbreviated to P