Chapter 3. Inside an Apple

Apple initiated its transition from the 68K hardware platform to the PowerPC in 1994. Within the next two years, Apple's entire line of computers moved to the PowerPC. The various PowerPC-based Apple computer families available at any given time have often differed in system architecture,^[1] the specific processor used, and the processor vendor. For example, before the G4 iBook was introduced in October 2003, Apple's then current systems included three generations of the PowerPC: the G3, the G4, and the G5. Whereas the G4 processor line is supplied by Motorola, the G3 and the G5 are from IBM. Table 31 lists the various PowerPC processors^[2] used by Apple.

^[1] System architecture refers to the type and interconnection of a system's hardware components, includingbut not limited tothe processor type.

^[2] The list does not account for minor differences between processor modelsfor example, differences based solely on processor clock frequencies.

Table 31. Processors Used in PowerPC-Based Apple Systems

Processor	Introduced	Discontinued
PowerPC 601	March 1994	June 1996
PowerPC 603	April 1995	May 1996
PowerPC 603e	April 1996	August 1998
PowerPC 604	August 1995	April 1998
PowerPC 604e	August 1996	September 1998
PowerPC G3	November 1997	October 2003
PowerPC G4	October 1999
PowerPC G5	June 2003
PowerPC G5 (dual-core)	October 2005

On June 6, 2005, at the Worldwide Developers Conference in San Francisco, Apple announced its plans to base future models of Macintosh computers on Intel processors. The move was presented as a two-year transition: Apple stated that although x86-based Macintosh models would become available by mid-2006, all Apple computers would transition to the x86 platform only by the end of 2007. The transition was faster than expected, with the first x86 Macintosh computers appearing in January 2006. These systemsthe iMac and the MacBook Prowere based on the Intel Core Duo^[3] dual-core processor line, which is built on 65 nm process technology.

^[3] This processor was originally codenamed Yonah.

In this chapter, we will look at the system architecture of a specific type of Apple computer: a G5-based dual-processor Power Mac. Moreover, we will discuss a specific PowerPC processor used in these systems: the 970FX. We focus on a G5-based system because the 970FX is more advanced, more powerful, and more interesting in general than its predecessors. It is also the basis for the first 64-bit dual-core PowerPC processor: the 970MP.