Page 138 - Programming Microcontrollers in C

Chapter 3

What Are Microcontrollers?

A microcontroller differs from a microprocessor in several im­
portant ways. The early name for a microcontroller was
microcomputer. The big difference between a microprocessor and a
microcomputer/microcontroller is the completeness of the machine
each represents. A microprocessor was simply the “heart” of a com­
puter. To put a microprocessor into use, the designer required memory,
peripheral chips, and serial and parallel ports to make a completely
functional computer. By contrast, the microcomputer was designed
to be a complete computer on a single chip. Necessary memory and
peripheral components were integrated onto the chip so that a com­
plete computer-based system could be built with a minimum of
external components. A basic microcontroller is shown in block dia­
gram form in Figure 3-1.

Program
Memory

Arithmetic
Input/Output
Logic Unit

Data Memory

Figure 3-1: A Typical Microcontroller Block Diagram

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