🚀 go-pugleaf

In article <6154@uceng.UC.EDU>, mfinegan@uceng.UC.EDU (michael k finegan) writes:
> Now - I have a question for the net. Resetting all VGA registers to their
> default (or previous) values != calling int 10h to set video mode. What is
> different ? I have an application where calling int 10h after various
> direct programming operations on the VGA restores the video, but saving all
> registers, performing operations, and restoring all registers does not. Why ?
> I have tried resetting the sequencer, and hardware, with sequencer register's
> reset register and crt controller register's mode control register. No luck.
> What does the Bios do that I don't know about ?
> 
I don't suppose you're getting the values for low-numbered CRT controller
registers by trying to read what's there, as opposed to looking up a table,
are you?? Often they are write-only (you cannot read what is there, for some
stupid reason). Look at the 6845 spec sheets - its a good place to start, even
if the card doesn't actually use one. There are tables in memory somewhere of
what to write to the registers, but I dodn't know where they are in VGA cards.

Mark Aitchison, Physics Computologist, University of Canterbury, New Zealand.