Re: multiple monitors

Snow Cat (
Mon, 8 Apr 1996 00:16:19 -0700 (PDT)

Zachary R Amsden once wrote:
> From Sun Apr 7 21:27:08 1996
> Excerpts from mail: 5-Apr-96 Re: Dual Monitor by Snow Cat@math.CSUFresno.
> >
> > Why not? <S>VGA cards use A000 for graphics mode and hercules uses B000.
> > XFree86 has a dual head server for 16-color + mono screens, but for
> some reason
> > not for 256 color+mono.
> >
> I was unaware of this - I thought they both started at A000. However,
> A000-B000 only gives 64k of memory, enough for 320 by 200 at one byte per
> pixel, or 640 by 200 at 16 colors. These resolutions are pretty poor, and
> for that reason I am looking into adding support for PCI cards which are
> fully configurable, or ColorGFX multiple monitor cards instead. This will
> be a major doing, and will not even have X support. X will need to be
> handled separately, and outside of the kernel. Hopefully the linux-ggi
> project will provide a good base for this.

SVGA video cards have always used bank switching on mapping the video buffer
to high memory to get higher resolution. It's another problem that many
SVGA boards don't allow one to configure memory and I/O range that they use,
so you can't have more than one board (of these models) of the same time.
But there should be no problem with SVGA + Hercules. You can even run two
separate XFree86 servers for both monitors - this just doesn't let you move
mouse from one screen to another or use copy and paste.

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