From: Brian S. Julin <bri@tull.umassp.edu>
  To  : ggi-develop@eskimo.com
  Date: Tue, 11 May 1999 22:26:14 -0400 (EDT)

Re: Multiple ATI Video Cards

On Tue, 11 May 1999 becka@rz.uni-duesseldorf.de wrote:
> I'd either write a usermode "lookalike" that just does what atyfb would do
> in its init procedure or copy the init function somewhere in the driver, 
> where you can call it with an ioctl or similar at driver runtime.

He may well find that atyfb does not do a full card initialization.
If so, there are two ways to find out what registers it misses.
One is to read the VGADOC ATI.TXT file and write a program to
probe all the registers on the main card and on the secondary card and 
find out what's different, and hope there's nothing undocumented.

(Be careful probing PIO cards -- remember to turn off hard cursor and
scrollback support so the console output from your program doesn't corrupt
your data.  Or run it on another computer's screen.)

Another is to boot dosemu and let it run the video BIOS on the primary
card, with a monitor on all the card's control register ports.  This
would turn up any undocumented registers.

Both are rather labor intensive, but having two monitors is a cool thing :)

--
Brian