Very Computer

Does anyone know how I can setup a Linux system with more than one
VGA/SVGA?  I've been told that the PC hardware only allows one VGA/SVGA in
the system at a time.  Though some people have said if you have a PCI
machine, you can put in more than one card and have it work.

Let me know if you can help.

Greg Corson                            Phone:    (312) 243-6515
Chief Software Engineer                FAX:      (312) 243-7818

1100 West Cermak
Chicago, IL 60608

We provide a commercial X Server.  Some of the solutions below will
work as multiple graphics board systems, but I have no idea how you'd
use the boards *without* an X Server or *with* XFree86.  I'm sure
Harald can answer that!

1/      Multiple Matrox boards.  Lousy VGA behavior, fast native MGA
        performance, but you can just keep adding Matrox boards till
        you run out of slots.

2/      One or more Colorgraphic Communications graphics boards.
        These boards are ISA, VESA and PCI and support 2 or 4 monitors
        per board (multiple chipsets/board).  These are typically
        ET4000/W32i or S3 928 chips.  Up to four boards/system.

3/      Arbitrary combinations of PCI graphics boards - We've run #9
        Imagine-128, ATI Mach64 and Matrox boards in one system.  The
        PCI architecture lets you add in as many boards as you have
        slots.  The total that could be supported is therefore in the
        range of hundreds, but we don't know of any motherboards with
        more than three PCI slots :-)

4/      One VGA/SVGA board and one 8514 board.

There are also some multiple monitor cards from other vendors.  We're
in discussion with a few.

Cheers, JeremyC.
--

        X Inside Inc, P O Box 10774, Golden, CO 80401-0610, USA.
   Commercial X Server - for more information please try these services

Quote:> Does anyone know how I can setup a Linux system with more than one
> VGA/SVGA?  

Anybody know of VGA/SVGA cards which can coexist (more than one in a
machine), I'd like to know.

Quote:> I've been told that the PC hardware only allows one VGA/SVGA in
> the system at a time.  

That is true, of standard cards.  It's because each VGA expects to use
the same IO addresses (0x3Cx addresses in particular) for its internal
control registers.  

There is also a conflict with the 0x3Dx registers, but with only two cards
one could be remapped to the mono space at 0x3Bx; and with memory address
for the video buffers, but this could be handled by either mapping only one
at a time, or by using the mono addresses for one (ie: Axxx for one,
Bxxx for the other).  But both boards will require 0x3Cx IO addresses,
creating an irresolvable conflict.  Unless one has a non-standard card
which can have it's IO addresses re-assigned (like the original IBM EGA,
which had a never-used jumper to change to 2xx addresses).  Who makes such
cards?  I've heard of dual VGA boards, but they were way overpriced (lots
of money, neither VGA up to*feature wise).

Too bad the industry diverged from the IBM path one notch too soon (taking
flight from the EGA/VGA standard); the XGA allowed up to 8 cards to coexist.

Quote:> Though some people have said if you have a PCI
> machine, you can put in more than one card and have it work.

I've not heard this, nor how it could be done.  Does each slot get it's own
I/O address space?  That could be interesting, if true...  The other
aspects (like video memory address) could be worked around...
     Zhahai

: Does anyone know how I can setup a Linux system with more than one
: VGA/SVGA?  I've been told that the PC hardware only allows one VGA/SVGA in
: the system at a time.  Though some people have said if you have a PCI
: machine, you can put in more than one card and have it work.

you could do it on an ISA/VLB system.  just not without ingenuity. (and an
exacto knife and a trace pen).

: Greg Corson                            Phone:    (312) 243-6515
: Chief Software Engineer                FAX:      (312) 243-7818

: 1100 West Cermak
: Chicago, IL 60608

ohhhh, I see why you want to know.  hehe.  I'm not gonna help now.  we've
got the same plan.  then again, ours would be better anyway. 8^)
sorry, but you can't beat Gilbertson's really absolutely genuinely
intensely cool refresh method.  never test more polygons than are on the
screen plus those which are just off the edge.  twisted, but more
efficient than anything out there.  yes, this is shamelessly obnoxiously
stuck-up noise.  sorry.

how about this.  use one card, run it at 90 Hz refresh and then use a
custom-built frame buffer for each screen and then flip between two
virtual screens in the SVGA RAM every frame.  have the frame buffer
display each frame twice, and you've still got 45 Hz frame rate.  now you
just gotta get the software going that fast.