Re: UDB video modes

Jay A Estabrook (
Tue, 05 Nov 1996 20:01:00 -0500

At 04:06 PM 11/5/96 -0500, you wrote:
>According to D. Steven Daniel:
>> What do the jumper settings on the UDB motherboard really control?
>I've wondered about this myself. On the ZLXp-E1 they allow you to
>select between 16 video modes, but not dynamically. Maybe they are not
>used for the TGA chip. I have set multiple modelines in my XF86Config
>successfully, so it seems that all modes are ``enabled''.

[We are talking about the rectangular group of 4 jumpers on the UDB MB]

They are used for the same thing as the DIP switches on a TGA PCI card;
they indicate to the *SRM* console (and subsequently, to the DU TGA server)
what resolution/refresh rate you wish to run console (and X server) at.

They are ignored by ARC console (AlphaBIOS as well, I think), and MILO.

When first booting a UDB, SRM console is active, so you may see a quite
different resolution/refresh rate during that (brief) period of time. Then,
when ARC becomes active, you'll see the familiar 640x480 @ 60Hz blue screen
we've all come to know and love.

>> Can the text mode sync frequencies be re-programmed?
>As I understand it, the TGA chip is not programmable.

It must be; check out the clock programming code in the new TGA server
from XFree86, included in the latest release, 3.2. Graphics and text modes
are all the same to the TGA (ie graphics), unlike VGA.


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