3.9 Summary

Numerous mechanisms must be used to implement complete computer systems. For example, interrupts have little direct visibility in the instruction set, but they are very important to input and output operations. Similarly, memory management is invisible to most of the program but is very important to creating a working system.

Although we are not directly concerned with the details of computer architecture, characteristics of the underlying CPU hardware have a major impact on programs. When designing embedded systems, we are typically concerned about characteristics such as execution speed or power consumption. Having some understanding of the factors that determine performance and power will help you later as you develop techniques for optimizing programs to meet these criteria.