Apple 17-INCH manual Controller, DMA Support

CHAPTER 2

Architecture

●support for 64 MB of DDR video memory with 128-bit interface

●2D and 3D graphics acceleration

●transform acceleration

●lighting acceleration

●video acceleration

●support for MPEG decoding

●support for video mirror mode

●support for dual-display mode

●S-video output for a TV monitor

The interface between the graphics IC and the rest of the system is an AGP4x (accelerated graphics port, quadruple speed) bus on the Intrepid IC. The AGP bus has 32 data lines, a clock speed of 66 MHz, and supports deeply pipelined read and write operations.

The graphics IC uses a graphics address remapping table (GART) to translate AGP logical addresses into physical addresses. The graphics driver software can allocate memory in both the graphics SDRAM and the main memory.

The graphics IC supports the internal flat-panel display and an external monitor. The external monitor can either mirror the built-in display or show additional desktop space (dual-display mode). For information about the displays and supported resolutions, see “Flat-Panel Display” (page 44) and “External Monitors” (page 45).

I/O Controller

The I/O controller IC in the PowerBook G4 17-inch computer is a custom IC called Intrepid. It provides the interface and control signals for the devices and functions described in the following sections.

Note: In the device tree, the I/O controller is named “mac-io”.

DMA Support

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

●Ultra DMA ATA interface to the the internal hard drive

●modem slot interface to the built-in modem

●IIS channel to the sound IC

I/O Controller 21

Legacy Document 2003-03-01 © 2003 Apple Computer, Inc. All Rights Reserved.