Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!haven!uvaarpa!mcnc!rti!bcw
From: bcw@rti.UUCP (Bruce Wright)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Two Video Cards ??
Summary: Pretty easy actually
Message-ID: <2906@rti.UUCP>
Date: 23 Apr 89 02:26:57 GMT
References: <680@mccc.UUCP>
Distribution: usa
Organization: Research Triangle Institute, RTP, NC
Lines: 46

In article <680@mccc.UUCP>, pjh@mccc.UUCP (Pete Holsberg) writes:
> A friend would like to be able to run CGA graphics programs on his monochrome
> PC by adding a CGA board to the system.  Is it possible to do this?  Can a
> monochrome monitor handle both monochrome and RGB signals?  How?

For at least the vast majority of PCs, this is pretty easy.  (There may
be a FEW odd models out there whose BIOS is unable to handle this sort
of thing, but I've never encountered any).

All you have to do is to put in both the cards.  There are no
conflicts on either of the cards with other common non-video cards.

(NOTE:	It is not possible to mix Hercules with monochrome [why would
	you want to, anyway?], nor is it possible to mix EGA in a
	monochrome mode with a monochrome or a Hercules adapter [again,
	why would you want to?], and VGA doesn't mix well with other
	adapters.  Other than this, you can pretty much mix-and-match:
	EGA with mono, CGA with mono, EGA with Hercules, CGA with
	Hercules.  In fact, I'm writing this on a PC which has an
	EGA and a Hercules monochrome card).

You will have to use the DIP switches on the motherboard to select
the default display adapter -- if you want to keep the monochrome as
the default display, you don't have to do anything.

Switching between the two displays is quite easy:  Just issue a
"MODE CO80" to go to the CGA monitor, and "MODE MONO" to go to the
monochrome monitor.

Monochrome monitors can't handle RGB-type signals unless they are
multisync-type monitors (a little odd for a monochrome monitor, but 
they do exist).  It is possible to convert RGB to a monochrome signal,
but if you don't know how to do this you probably shouldn't try - you
can destroy the monitor and/or the adapter if you get it wrong.

By the way, if all you are interested in is monochrome graphics, and
aren't very interested in the color modes of the CGA, you will probably
find that a Hercules monochrome card will be a better solution - you
get MUCH better resolution than with a CGA, and save the cost of a
color monitor.  To install this you would just remove the old monochrome
adapter and put in the Hercules.  There is software to allow many
programs to use the Hercules modes (including BASIC).

Good luck.

						Bruce C. Wright