phys169@canterbury.ac.nz (09/27/90)
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.