3.1 Introduction

This chapter describes aspects of CPUs that do not directly relate to their instruction sets. We consider a number of mechanisms that are important to interfacing to other system elements, such as interrupts and memory management. We also take a first look at aspects of the CPU other than functionality—performance and power consumption are both very important attributes of programs that are only indirectly related to the instructions they use.

In Section 3.2, we study input and output mechanisms including both busy/wait and interrupts. Section 3.3 introduces several specialized mechanisms for operations like detecting internal errors and protecting CPU resources. Section 3.4 introduces co-processors that provide optional support for parts of the instruction set. Section 3.5 describes the CPU’s view of memory—both memory management and caches. The next sections look at nonfunctional attributes of execution: Section 3.6 looks at performance while Section 3.7 considers power consumption. Finally, in Section 3.8 we use a data compressor as an example of a simple yet interesting program.