The requirements in this section relate to BIOS support for graphics adapters.
42. Chips support linear packed-pixel frame buffer, relocatable above 16 MB
Required
Note: For DirectDraw, the graphics adapter’s chip set must support linear access to the frame buffer by the host.
Windows is optimized for a graphics adapter with a packed-pixel frame buffer at all supported resolutions. Memory-mapped packed-pixel frame buffers also provide a fast and simple interface between Windows and the graphics adapter. The Windows DIB engine provides a very fast display by writing directly to packed-pixel frame buffers, and this architecture requires that the hardware developer write only a small, simple device driver.
For optimized support with Windows, a linear packed-pixel frame buffer is required over a bank-switched frame buffer. Use 32-bit addresses to allow the linear frame buffer to be placed above the 16-MB ISA boundary, which enables a system to be populated with large amounts of RAM.
If memory or other resources conflict with the frame buffer being mapped into a linear address space, the page frame address can be used with minimal degradation of performance.
43. Option ROM supports DDC2B
Required
This requirement does not apply for systems that use RISC-based processors. The option ROM for the graphics adapter must meet current DDC host requirements documented in Display Data Channel Standard, Version 2.0, Level B (DDC2B), published by VESA. This standard defines the functions that support the data channel between the graphics adapter and a DDC-compliant monitor.
44. BIOS setup utility provides option to force use of system-board graphics
Recommended
The OEM should provide an option in the system BIOS setup utility to force the system-board graphics device to be used (that is, to ignore and leave disabled any PCI graphics adapters). This option would ensure that a user with a PCI hot-docking system is always able to undock, because the VGA device will be in the mobile unit.
45. BIOS supports large frame buffers for graphics adapters
Required
The BIOS must support large frame-buffer graphics adapters that have up to 256 MB of frame buffers.