Whereas Chapter 8 introduced the lowest levels of hardware control, this chapter provides an overview of the higher-level bus architectures. A bus is made up of both an electrical interface and a programming interface. In this chapter, we deal with the programming interface.

This chapter covers a number of bus architectures. However, the primary focus is on the kernel functions that access PCI peripherals, because these days the PCI bus is the most commonly used peripheral bus on desktops and bigger computers, and the one that is best supported by the kernel. ISA is still common for electronic hobbyists and is described later, although it is pretty much a bare-metal kind of bus and there isn’t much to say in addition to what is covered in Chapter 8 and Chapter 9.