TABLE OF CONTENTS Over the next 30 years, microprocessor-based design has become the nearly universal approach to systems design. Once microprocessors had achieved the requisite processing and I/O bandwidth needed to handle a large number of system tasks, they began to permeate system design. The reason for this development is simply engineering economics. Standard microprocessors offered as individual integrated circuits (ICs) provide a very economical way to package thousands of logic transistors in standard, testable configurations. The resulting mass-produced microprocessor ICs have become cheap, often costing less than $1 per chip, and they deliver abilities that belie their modest cost.
Microprocessors also dominate modern electronic system design because hardware is far more difficult to change than software or firmware. To change hardware, the design team must redesign and re-verify the logic, change the design of the circuit board (in pre-SOC times), and then re-run any required functional and environmental tests. Software or firmware developers can change their code, recompile, and then burn new ROMs or download the new code into the existing hardware.
In addition, a hardware designer can design a microprocessor-based system and build it before the system s function is fully defined. Pouring the software or firmware into the hardware finalizes the design and this event can occur days, weeks, or months after the hardware has been designed, prototyped, verified, tested, manufactured, and even fielded. As a consequence, microprocessor-based system design buys the design team extra time because hardware and firmware...
