KOH_5F05h

5F05h – Refresh Rate

This function sets a new vertical refresh rate for a given mode and returns the current vertical refresh rate and available refresh rate for a given non-VGA mode.

5F05h, 00h – Set Refresh Rate

This sub-function sets a new default refresh rate for the selected pipe. If the mode is currently active, the CRT controller and other registers will be automatically programmed setting the requested refresh rate.

Note: This function is not entirely compatible with the Desktop and Mobile versions. It is not possible to set the refresh rate for a given mode in advance. This function sets the “desired” refresh rate which will be applied to all subsequent mode sets when possible. If the mode provided in BL is the current mode, then a mode change will be automatically performed.

Calling Register:

AX = 5F05h, Refresh Rate function

BH = 00h, Set Refresh Rate sub-function

BL = Mode Number

ECX = Refresh rate (indicated by setting one bit):

Bits 31 - 9 = Reserved

Bit 8 = 120 Hz

Bit 7 = 100 Hz

Bit 6 = 85 Hz

Bit 5 = 75 Hz

Bit 4 = 72 Hz

Bit 3 = 70 Hz

Bit 2 = 60 Hz

Bit 1 = 56 Hz

Bit 0 = 43 Hz (Interlaced - Not supported)

Return Registers:

AX = Return Status (function not supported if AL != 5Fh):

= 005Fh, Function supported and successful

= 015Fh, Function supported but failed

5F05h, 01h – Get Refresh Rate

This sub-function returns current vertical refresh rate for the selected pipe and available refresh rates information for a given Non-VGA mode.

Note: This sub-function returns a status of supported but failed (AX = 015Fh) if executed with a standard VGA mode.

Calling Registers: