Specifications

188 AMD Geode™ GeodeROM Functional Specification
Video BIOS Support
32087C
Passed:
Returns:
13.1.19.8 Subfunction 35h: Display Switch
Switches between an adapter VGA and a motherboard (planar) VGA on the IBM PS/2 Model 30. Subfunctions 02h and
03h are valid only after Functions 00h and 01h have been called. The same buffer (pointed to by ES:DX) must be used
in all calls to this function since the BIOS calls Function 1Ch to save/restore the video state into this buffer.
Note that most motherboards that have a VGA on them do NOT support this call and in fact can only be disabled with
either jumpers/dip switches or through the CMOS setup.
Passed:
Returns:
13.1.19.9 Subfunction 36h: Enable/Disable Video Screen
Enables or disables the video screen. Unlike Subfunction 32h, all I/O and memory accesses are still valid. In fact, blanking
the screen has the effect of giving full memory bandwidth to the CPU, since the CRTC does not require memory fetches.
Passed:
Returns:
Parameter Description
AH 12h
AL Enable emulation flag:
0 = Enable
1 = Disable
BL 34h
Parameter Description
AL 12h
Parameter Description
AH 12h
AL Display switch subfunction:
00h = Initial switch off adapter VGA
01h = Initial switch on motherboard VGA
02h = Switch off active VGA
03h = Switch on inactive VGA
BL 35h
ES:DX Pointer to 128-byte buffer
Parameter Description
AL 12h
Parameter Description
AH 12h
AL Enable video flag:
0 = Enable
1 = Disable
BL 36h
Parameter Description
AL 12h