Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!killer!chasm
From: chasm@killer.UUCP (Charles Marslett)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Two Monitors on a PS/2?
Message-ID: <3892@killer.UUCP>
Date: 21 Apr 88 03:24:19 GMT
References: <206900111@prism> <7955@iuvax.cs.indiana.edu>
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 32
Summary: Should be able to do it!

In article <7955@iuvax.cs.indiana.edu>, bkliewer@iuvax.cs.indiana.edu (Bradley Dyck Kliewer) writes:
> In article <206900111@prism> jms@prism.TMC.COM writes:
> >
> >	Has anybody successfully configured a PS/2 model 50, 60, or 80
> >as a two monitor system?  Can the VGA adapter be used to display 
> >monochrome text while graphics are displayed from a separate EGA
> >adapter?  Thanks in advance.
> 
> Since the EGA and VGA use the same register addresses, it is unlikey that
> you will be able to do this.  The EGA register addresses can be changed,
> but you would have to write your own BIOS and anything which writes directly
> to the registers (i.e. just about every program) will cause problems.  You

> Bradley Dyck Kliewer                Hacking...
> bkliewer@iuvax.cs.indiana.edu       It's not just an adventure
>                                     It's my job!
> 
> Author: EGA/VGA A Programmer's Reference Guide

Actually, the PS/2 BIOS does have a set of calls to support a VGA installed
in a system with a VGA already present (the hardware I/O addresses are 0x03C3
and 0x4??? -- don't remember that one right off) -- the scheme only supports
one add in card and the one motherboard video, but at least on the model 30
it does work (we have installed STB VGA's and switched back and forth from
motherboard to/from add in card).

I am currently working on a new product that had 4 (expandable to 8) EGA's
in a single system (say WHY please!),  using the same scheme.  So it is
not only workable, but rather easily extended.

Charles Marslett
chasm@killer.UUCP
...!ihnp4!killer!chasm