We have written a driver that hooks the very last thing before windows turns off the power during a windows shutdown (xp, 2000 so far… others to follow). Just before we start our special dedicated code (long story, but we need to do it this way for this hardware control), we need to get the video subsystem into power-up condition (unprotected, VGA text-mode 80×25 with the text buffer in the standard place in upper memory). (We won’t be running DOS, BTW, in case that’s a question- just our dedicated code).
I am concerned about all the video bios’s out there that may not have a standardized way of doing this once the windows driver has monkeyed with the video chips.
Does anyone know of a consistent, reliable way to do this? It is OK if we have the windows driver do it as we hook windows during the power-down process, but it doesn’t seem to work that way in our experiments…
Thanks-
Doug
