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● 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 theIntrepid IC. The AGP bus has 32data lines, a clock speed of 66MHz, andsupports
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 andsupported resolutions, see “Flat-PanelDisplay” (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.
CHAPTER 2
Architecture