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In the past, graphics drivers and Mac OS relied on a card's NuBus declaration ROM to get information on the card's capabilities. In PCI-based Power Macintosh computers, the programming interface for PCI graphics drivers lets the drivers provide the same information to the Mac OS.
Because of potential compilation problems, applications should avoid using high-level Device Manager routines when accessing PCI graphics drivers directly. Use the low-level PBOpen, PBClose, PBControlSync, and PBStatusSync routines (described in Inside Macintosh: Devices) instead of FSOpen, FSClose, Control, or Status.
The next sections detail the specific control and status calls to which a graphics driver must respond.