Specifications

206 AMD Geode™ GeodeROM Functional Specification
Video BIOS Support
32087C
13.2.16 Function 14h: OEM Extensions
Operates AMD specific extensions to the video BIOS.
13.2.16.1 Subfunction 00h: Refresh Rate Select
This function is used to indicate the desired refresh rate for successive mode switches. It does not change the refresh rate
of the current mode. Therefore, this function should be called before calling Function 02h to set a video mode.
The number of possible refresh rates is limited by tables in the video BIOS. Table 13-5 gives the supported frequencies for
the specified resolutions.
This function has no effect when setting the standard VGA modes.
Passed:
Returns:
None.
13.2.16.2 Subfunction 02h: Set Display Enable
Description:
This routine is called by the system BIOS during POST to set the initial display configuration (flat panel, CRT, or both).
This routine does not affect TV output, which is handled by separate system BIOS routines. If TV output is enabled,
however, this function should still be used to enable the fixed timings.
Passed:
Returns:
None.
Table 13-5. Refresh Rates
Resolution Frequency (Hz)
640x480 60 72 75 85
800x600 56 60 72 75 85
1024x768 60 70 75 85
1280x1024 60 75 85
Parameter Description
AX 4F14h
BL 00h
DL Refresh rate
Parameter Description
AX 4F14h
BL 02h
BH Display enable:
Bit 0 = Flat panel output enable
Bit 1 = CRT output enable
Bit 2 = Enable fixed timings