DOS/32 Advanced DOS Extender - Programmer's Reference

4.02 - VGA function 1Ch - Save/Restore VGA State



AH = 1Ch
AL = subfunction:

00h - get state buffer size
Returns: EBX = number of 64-byte blocks needed
01h - save video states
02h - restore video states

ECX = states to save/restore:

bit 0 - VGA video hardware state
bit 1 - VGA BIOS data state
bit 2 - VGA DAC state

ES:EBX = pointer to save/restore buffer

Out: AL = 1Ch (if function supported by VGA BIOS)


a) many BIOSes corrupt the video registers when saving the state, so a program should restore the state immediately after saving it (the saved data is uncorrupted).

b) For subfunctions 01h and 02h, the DOS Extender will internally call subfunction 00h to extract the information about size of data that is to be copied.


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