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Main ICs and Buses
The architecture of the PowerBook G4 17-inch computer is designed around the PowerPC G4 microprocessor
and Intrepid IC that contains the memory controller and I/O device controller.
The PowerPC G4 microprocessor is connected to the Intrepid IC by a MaxBus bus. The bus clock speed is 167
MHz. Other buses that connect with the Intrepid IC are summarized in Table 2-1 (page 19), which is in the
section “Intrepid Controller and Buses” (page 19).
The Intrepid I/O controller has a 32-bit PCI bus with a bus clock speed of 33 MHz. That bus also connects to
the Boot ROM and the CardBus controller. The Intrepid IC has other buses that connect with the hard disk
drive and the optical drive, the power controller IC, the sound IC, the internal modem module, and the
wireless LAN module.
Each of the components listed here is described in one of the following sections.
Microprocessor and Caches
The microprocessor communicates with the rest of the system by way of a 64-bit MaxBus bus to the Intrepid
IC. The microprocessor has a separate bus to its internal second-level cache.
PowerPC G4 Microprocessor
The PowerPC G4 microprocessor used in the PowerBook G4 17-inch computer has many powerful features,
including an efficient pipelined system bus called MaxBus.
Features of the PowerPC G4 include
● 32-bit PowerPC implementation
● superscalar PowerPC core
● Velocity Engine (AltiVec technology): 128-bit-wide vector execution unit
● dual 32 KB instruction and data caches
● an on-chip level 2 (L2) cache consisting of 256 KB with a clock speed ratio of 1:1
● high bandwidth MaxBus (also compatible with 60x bus)
● fully symmetric multiprocessing capability
The PowerPC G4 microprocessor in the PowerBook G4 17-inch computer runs at a clock speed of 1 GHz.
18
Microprocessor and Caches
Legacy Document | 2003-03-01 | © 2003 Apple Computer, Inc. All Rights Reserved.
CHAPTER 2
Architecture