Mac OS® X Leopard™ Bible

Chapter 4. Transitioning to Intel Architecture and Universal/Binary Apps

IN THIS CHAPTER

• Introduction to processor architecture

• PowerPC versus Intel

• Migration considerations

In the simplest terms, a computer is built around several important devices. We're all fairly familiar with the basics, but to recap (again, on a very general, basic level), we've got the CPU, the hard drive, RAM, and some various busses. This chapter concentrates on the CPU, including what some of the recent changes in Apple's lineup mean to the end user.

When we talk about processor architecture, we're basically referring to the design of the chip and how it relates to the way it processes information. There are two main strategies that chip designers take: CISC and RISC. CISC stands for Complex Instruction Set Computers, and RISC stands for Reduced Instruction Set Computers. In a sense, these methodologies aren't much more than design philosophies, and in some sense were coined retroactively after the early chip design schemes had started to play out. Most early chips were CISC, when storage was at a premium. CISC chips are generally characterized by a greater number of operations built into the chip explicitly. On the other hand, RISC chips have comparatively few instructions, or operations, implemented. Generally RISC chips can perform individual instructions more quickly because they are simple and limited in scope, while CISC chips take longer to perform an individual instruction because they're more complex ...