TABLE OF CONTENTS Programmable, or stored program controlled, devices were made possible with the invention of the microprocessor. There now exists a range of devices targeted at applications demanding anywhere from from 4 to 64 bit processing capability. Microcontroller devices have progressed beyond microprocessors to incorporate processor, memory and I/O units onto a single chip. Two commercial applications are described for the i8051 and StrongARM processors.
With the introduction of small integrated CPUs, in the form of microprocessors, came the possibility of many new computer-based applications. But the early microprocessor chips still had to be supported on the PCB by up to a dozen peripheral chips: crystal oscillator, bus drivers, memory controller, UARTs (serial comms), PIOs (parallel I/O), interrupt controller, SRAMs, DRAMs and PROMs. Although the single chip processor had arrived, the single chip computer remained some way off. However, when circuit masks could be shrunk sufficiently, and cost effectively, it became feasible to integrate CPU, memory and I/O all on the same chip. These new highly integrated microcomputers were referred to as microcontrollers and reduced the cost of implementing embedded systems by a further substantial factor. Currently there is a fairly clear distinction between different categories of microprocessor, as summarized above.
| Type | Size | Speed | Examples | Roles |
|---|---|---|---|---|
| Low cost microcontroller high volume | 4/8 bits | 12MHz | Intel 8051 Microchip 16F84 | domestic white goods, toys, games |
| General purpose microcontroller | 8/16 bits | 25MHz 80 MHz | 80186 Infineon c166S | technical equipment, automotive applications |
| High... |
