Chapter 4The Firmware and the Bootloader

When a computer system’s power is turned on, or the system is reset, the process of its “coming up” is called bootstrapping, or simply booting.[1] A modern Apple computer presents a capable and interesting firmware environment even before an operating system runs on it. In this chapter, we will explore this environment on a PowerPC-based Macintosh computer. We will also look at the sequence of events that happens during booting—up to the point where the Mac OS X kernel gains control. Finally, we will briefly discuss an equally interesting firmware environment (EFI) for x86-based Macintosh computers.

4.1 Introduction

As we saw in Chapter 3, a representative computer system consists of a main logic board ...

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