From: raynor@cs.scarolina.edu (Harold Brian Raynor) Subject: Re: Multiple Monitors with Linux Date: 1 Apr 1993 00:34:47 GMT
davesimp@soda.berkeley.edu (David Simpson) writes:
>I've read that with certain patches, you can run Linux with two monitors,
>one being VGA and the other being hercules or monochrome.
Can't answer the Linux part itself, haven't tried it, but I may be of
some help below.
>Two questions:
>With this arrangement, is there a program that would allow you to run
>X on both monitors and move the mouse pointer in between them, or would
>they be completely separate?
I strongly doubt that you would be able to have one "virtual screen"
running between two monitors unless you have a super expensive (read
$2000 + ) video card made to do this sort of thing, and then having
Linux to drive it is another story.
In short, I don't think you can do this like you can on the Mac easily.
You would have two totally separate screens I would believe.
>Also, what sort of hardware do you need? Could you use two VGA cards,
>one emulating a monochrome card, or would that just not work.
Some VGA cards, even when emulating a Hercules card, still will steal
the normal VGA addresses. If you pop the second VGA card (the one you
want to use as Herc) into an 8 bit slot (unusually this helps) AND flip
the switches (if any) on it to force it to Herc only mode, it may work.
Most cards though you will need to boot the machine up, and then run a
utility program forcing it into Herc mode, and then reboot. Problem is
if you have another VGA card in there at the same time, you won't be
able to boot into the system far enough to run the program!
A Hercules-only card will usually work just fine with a VGA (as long as
you disable the VGA's herc mode, most let you do this, some don't).
>I am not that knowledgable about the low level implementation of all this,
>but I guess the memory addresses for VGA, Hercules, and Monochrome are
>fixed values, but are different.
I don't remember exactly the addresses off the top of my head, so these
may be wrong, but yes Monochrome (including Herc) and Color (CGA, EGA<
VGA) use different areas of memory.
Monochrome (I believe starts at $B000 while color starts at $B800. EGA,
and most SVGA cards, of course will use more (they map the VGA memory
into the old CGA memory and bankswitch, some for speed actually use a much
bigger address space so they don't have to bankswitch as much, often
overwriting the monochrome buffer area).
>Any help would be appreciated. I sent mail to the author of the patch
>earlier, but he had been so swamped with mail from all this, he could
>only send out a group letter which didn't answer these questions. So if
>you CAN answer these questions, please don't direct me elsewhere. Thanks.
Hope this helps, if not, mail me back and I can look up specs (I have
them readily available, just haven't looked for quite some time).
Thanks,
Brian Raynor