Re: Video Mode 13h in windows XP ... impossible?

From: wolfgang kern (nowhere_at_nevernet.at)
Date: 02/20/04 

Date: Fri, 20 Feb 2004 20:00:43 -0000

"The Half A Wannabee" asked:

| > My (fastest) way is using direct hw-access,
| > but this goes a bit deeper and needs hardware specific routines,
| > so I can only support a few known cards that way,
| > for all 'unknown' stuff I have to use VBE/VESA method.
|
| Nice post. I was thinking.Would it be possible to install a driver in
| windows to record anything send to the Nvidia driver and from the Nvidia
| driver to the hardware ? I do not intend to do this, but just for
| curriosity. My only question is, would it be possible ? Beth, Wolf. Anyone?

To find out how "all used by windoze" functions of your graphics card
may work in detail, you need to resident install a debugging tool,
which can hook, trace and store all associated I/O and/or
memory-mapped actions including PCI.
But this sounds like an awful complex job, as this tool
needs to be somehow smart (far away from usual stuff).
Not to forget the additional delay which may fool the results.

For cards with no available info from manufacturer/NG/else,
I usually disassemble the Video-BIOS and find more features
and more supported modes than M$ or directX will ever use.

The VBIOS-hardware link is just a small piece of code.
Subtract fonts, OEM-strings, and other unimportant things,
from the 32 KB ROM space, the remaining rest can be analysed
manually in deep detail within one or two weeks.
Follow the mode-set, pixel-draw, page-flip, ..
using the VESA-pointer rather than int10 service.
A scan of the PCI features-block can also tell some about the device.
__
wolfgang