Path: utzoo!utgpu!watmath!clyde!att!rutgers!gatech!emcard!stiatl!john
From: john@stiatl.UUCP (John DeArmond)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Two Monitors W/Leading Edge Model D
Message-ID: <1882@stiatl.UUCP>
Date: 29 Nov 88 19:05:40 GMT
References: <432@bdt.UUCP> <4330111@hpindda.HP.COM>
Reply-To: john@stiatl.UUCP (John DeArmond)
Organization: Sales Technologies Inc., Atlanta, GA
Lines: 43

In article <4330111@hpindda.HP.COM> huilin@hpindda.HP.COM (Hui Lin Lim) writes:
>It is possible to have to monitors connected to a PC at the same time
>but you will not be able to *display* to both monitors simultaneously
>eg for a class room where you use the monochrome and the calss watches
>a large screen TV.

Actually, you CAN have both monitors active if the application is 
written properly.  Example, AutoCad will use a mono display for textural
display and a CGA for graphics.  Example:  A Mandelbrot program that 
Jim Willis and I wrote displays the set on an EGA/VGA while displaying
statistics on the mono screen.  Example:  I have modified my editor to
use 2 displays instead of split screen (ain't source code wonderful!!) 
Example:  CodeView gladly uses 2 screens, one for the application and
one for debug info.

The only 2 conditions that have to exist (assuming both display cards
are installed), are that the application must know where in the memory
map to write video in the proper format and that the video controllers
on both adaptors be initialized. (The leading edge model M is a glaring
exception to the rule that most bioses init all video cards at boot)


>
>Many years back (if my memory serves me correctly) PC Magazine published
>a memory resident utility called DOORS which allowed you to switch
>back and forth but as far as I know you *still* can't have both
>monitors active at the same time.
>

Well, I don't know about the PC mag utility but the following DOS commands
work just fine to change the active display:

mode co80  (cga)
mode mono  (mono)
>
>Hui Lin
>
>huilin@hpinddf@hplabs


John De Armond                             | "I can't drive 85!"
Sales Technologies, Inc.    Atlanta, GA    | Sammy Hagar driving 
...!gatech!stiatl!john                     | thru Atlanta!