Specifications
176 AMD Geode™ GeodeROM Functional Specification
Video BIOS Support
32087C
13.1.17.9 Subfunction 12h: Set Block of RAMDAC Registers
Description:
Sets a block of RAMDAC registers to the values pointed to by ES:DX. This buffer should contain a sequence of red,
green, and blue values to be placed in the RAMDAC, starting at the specified index. The value in CX is not the length
of the buffer, but the number of registers to set. The buffer is actually three times the number of bytes specified in CX.
Each of the 256 RAMDAC locations contains three 6-bit values each for red, green, and blue. Values above 3Fh are
truncated (masked).
Passed:
Returns:
None.
13.1.17.10Subfunction 13h: Select Color Page
Description:
Calling this subfunction changes the block of RAMDAC registers used by non-256 color modes. Depending on the
color page mode (BL = 0), the RAMDAC is divided into either 4 or 16 different pages.
BX Color Page Mode
0000h 4 pages of 64 registers
0100h 16 pages of 16 registers
Passed:
Returns:
None.
13.1.17.11Subfunction 15h: Get Individual RAMDAC Register
Description:
Gets a specified, individual RAMDAC register’s R,G,B value. Each of the 256 RAMDAC locations contain three 6-bit
values each for red, green, and blue.
Passed:
Parameter Description
AH 10h
AL 12h
BX Starting index
CX Number of registers to set
ES:DX Pointer to buffer containing RGB values <R,G,B ... R,G,B> for CX number of entries
Parameter Description
AH 10h
AL 13h
BX Starting index
CX Number of registers to set
ES:DX Pointer to buffer containing RGB values <R,G,B ... R,G,B> for CX number of entries.
Parameter Description
AH 10h
AL 15h
BX Index