Specifications

For more information on the HyperTransport technology, go to the World Wide Web at

http://www.hypertransport.org

PCI USB Controller

The Power Mac G5 CPU uses a PCI USB controller ASIC with one Enhanced Host Controller Interface (EHCI)

function and two Open Host Controller Interface (OHCI) functions. The controller has a total of five ports

available to support three external USB ports and the internal AGP slot, which goes through the AGP to support

the USB hub on the Apple display. The PCI USB controller also supports the Bluetooth and AirPort Express

interfaces. If connected to classic-speed USB devices, the two rear panel ports are connected to separate OHCI

controllers.

The five USB ports comply with the Universal Serial Bus Specification 2.0. The USB register set complies with

the EHCI and OHCI specifications. For more information, see USB Ports (page 30).

K2 I/O Controller

The K2 custom IC provides all the I/O functions. These functions are described in the following sections.

DMA Support

The K2 IC provides DB-DMA (descriptor-based direct memory access) support for the following I/O channels:

●

Ultra ATA/100

●

Ethernet interface

●

FireWire interface

●

I2S channel to the sound subsystem

●

Serial ATA

The DB-DMA system provides a scatter-gather process based on memory-resident data structures that describe

the data transfers. The DMA engine is enhanced to allow bursting of data files for improved performance.

Architecture

PCI USB Controller