From: bert.tyler@satalink.com (Bert Tyler)
Newsgroups: alt.fractals
Subject: Fractint & ATI Ultra
Date: 25 Jul 92 14:05:00 GMT
Reply-To: bert.tyler@satalink.com (Bert Tyler)
Organization: SataLink Info Systems - Huntingdon Valley, PA - 215-364-3324

For some time now, I've been getting reports of problems with our
Fractint program and the new ATI Graphics Ultra video adapter.  I've
seen reports indicating that other graphics programs have problems
with this adapter as well.

Last week, my new Gateway computer arrived with an ATI Graphics Ultra,
and I'm happy to report that there are fixes to those problems.  I'm
posting this message on various Compuserve and BBS Graphics-related areas
because folks using this video adapter should be able to take advantage
of these fixes both with Fractint and with other graphics programs.

First a quick description of the adapter.  The ATI Graphics Ultra adapter
is really two adapters in one: an ATI SuperVGA adapter with 512K of
video memory, and a register-compatible 8514/A adapter (with proprietary
extensions to 800x600x256 and 1280x1024x16) with 1MB of video memory.

With my Gateway PC as delivered, Fractint could run its "SuperVGA
Autodetect" resolutions at 640x480x256, 640x380x256, and 800x600x16 -
but not at 800x600x256, 1024x768x16, or 1024x768x256.  The symptom
was the same on all three failed resolutions - Fractint would *think*
it had switched the adapter to the appropriate resolution, but it
really hadn't.  At the same time, however, the Windows drivers supplied
with the adapter *did* work at 800x600x256 and 1024x768x256.

It turns out that the *symptoms* were identical, but that the *underlying
cause* was unique for each of the failed video modes!  One by one:

1024x768x256 - the ATI SuperVGA side of this adapter only has 512K of
memory, and so does not support this video mode at all (the Windows 
drivers ATI supplies with this adapter work at this resolution because
they all use the 8514/A side of the adapter).  Fractint's 8514/A-specific
video modes (SF10 through CF3) work fine with the ATI Graphics Ultra.
The current versions of Fractint (which go through the 8514/A API)
require that ATI's HDILOAD program be activated first - the next
version of Fractint will include a register-compatible 8514/A interface
that does not require HDILOAD and works fine with the ATI.

1024x768x16 - When Fractint auto-detects the presence of an ATI adapter,
it assumes that it's dealing with an older ATI VGA Wonder that used a
packed-pixel scheme at this resolution.  The ATI Graphics Ultra uses
the more common planar scheme.  The solution is to fire up ATI's VVESA
TSR to make the ATI Ultra VESA-compliant.  Fractint checks for VESA-
compliance before it looks for vendor-specific chipsets, so with VVESA
active Fractint goes through the VESA interface instead - and uses
the information supplied automatically by that interface to handle
the 1024x768x16 mode correctly.

800x600x256 - As delivered on my Gateway PC, my ATI Graphics Ultra
used its default 72hx refresh rate for all video modes.  Jonathan
Osuch discovered a reference in his ATI manuals (a reference that
was *not* in my Gateway manuals - $%^&@#@#!!) mentioning that
80x600x256 mode is disabled automatically by the adapter at 72hz,
but enabled at 70hz (again, the Windows drivers supplied by ATI work
at 800x600x256 because they go through the 8514/A side of the adapter 
and a proprietary ATI extension of that interface).  *If* your
monitor can handle 800x600 at 70hz, the solution is to fire up the
adapter's INSTALL program, select 'Set Power Up Configuration' and
then the 'Monitor Type' option, select "Custom" as your monitor type
(it's the last entry, and it's a *ways* down the list), and change
the refresh rate at 800x600 to 70hz.  Once that is done, the ATI side
of the adapter enables its 800x600x256 mode and Fractint works fine.
(If you have the VVESA interface active when you do this, you have to
de-activate ('vvesa off') and then reactivate ('vvesa') it afterwards
to get it to enable that video mode as well, as it only checks the
availability of video modes when it is first activated).

*Warning* - the ATI manuals and INSTALL program warn you that setting
a refresh rate other than one your monitor can support can destroy
your monitor.  If your monitor can't hold this refresh rate at 800x600
and you make the above change and damage it, neither ATI, Gateway, nor
I will accept responsibility for the damage.

                   Bert Tyler   (bert.tyler@satalink.com)
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 . DeLuxe./386 1.25 #343sa . Did you expect mere proof to sway my opinion?