Chapter 3. Processor Basics

In this chapter

• Stand-alone Processors page 38

• Integrated Processors: Systems on Chip page 43

• Hardware Platforms page 61

• Chapter Summary page 62

In this chapter, we present some basic information to help you navigate the huge sea of embedded processor choices. We look at some of the processors on the market and the types of features they contain. Stand-alone processors are highlighted first. These tend to be the most powerful processors and require external chipsets to form complete systems. Next we present some of the many integrated processors that are supported under Linux. Finally, we look at some of the common hardware platforms in use today.

Literally dozens of embedded processors are available to choose from in a given embedded design. For the purposes of this chapter, we limit the available discussion to those that contain a hardware memory-management unit and, of course, to those that are supported under Linux. One of the fundamental architectural design aspects of Linux is that it is a virtual memory operating system.^[1] Employing Linux on a processor that does not contain an MMU gives up one of the more valuable architectural features of the kernel and is beyond the scope of this book.

^[1] Linux has support for some basic processors that do not contain MMUs, but this is not considered a mainstream use of Linux.