[comp.sys.mac] multiple mac displays

gw@cadre.dsl.PITTSBURGH.EDU (Gerhard Werner) (04/24/89)

Does anyone have any information on driving multiple duplicate
displays (i.e. more than one monitor) from a single MacII,
using the standard Mac video card(s).

  Gerhard Werner
  gw@cadre.dsl.pittsburgh.edu

dorourke@polyslo.CalPoly.EDU (David M. O'Rourke) (04/25/89)

In article <2680@cadre.dsl.PITTSBURGH.EDU> gw@cadre.dsl.PITTSBURGH.EDU (Gerhard Werner) writes:
>Does anyone have any information on driving multiple duplicate
>displays (i.e. more than one monitor) from a single MacII,
>using the standard Mac video card(s).

  I believe all you need to do is put a video card in the MacII and plug
a monitor into it.  The Monitor CDEV will then allow you to configure
the two monitors to display them however you want.

  Hope this helps.
-- 
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\|/////////////////////////////////////////
David M. O'Rourke____________________|_____________dorourke@polyslo.calpoly.edu
|       It's only 1's & 0's, so how difficult can Computer Science be?        |
|:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::|

mithomas@bsu-cs.bsu.edu (Michael Thomas Niehaus) (04/25/89)

In article <10654@polyslo.CalPoly.EDU>, dorourke@polyslo.CalPoly.EDU (David M. O'Rourke) writes:
> In article <2680@cadre.dsl.PITTSBURGH.EDU> gw@cadre.dsl.PITTSBURGH.EDU (Gerhard Werner) writes:
> >Does anyone have any information on driving multiple duplicate
> >displays (i.e. more than one monitor) from a single MacII,
> >using the standard Mac video card(s).
> 
>   I believe all you need to do is put a video card in the MacII and plug
> a monitor into it.  The Monitor CDEV will then allow you to configure
> the two monitors to display them however you want.
... 
> David M. O'Rourke

These are generally questions that I don't touch, because people have yelled
at me for providing answers to the wrong question.  Notice the key word in
the original message: DUPLICATE.  I gather from this one word that Gerhard
is trying to display the same image on two monitors that are connected to the
same machine.  So, the question is then transformed to:  How can I split a
Macintosh video signal so that I can display the same image on two different
monitors (usually so that it can be seen by a group of people)?

If anyone has the details of how to do this, I would appreciate knowing as
well, because I can think of many situations where this would be nice.

-Michael


-- 
Michael Niehaus        UUCP: <backbones>!{iuvax,pur-ee}!bsu-cs!mithomas
Apple Student Rep      ARPA:  mithomas@bsu-cs.bsu.edu
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jfm@ruddles.sprl.umich.edu.engin.umich.edu (John F. Mansfield) (04/25/89)

In article <10654@polyslo.CalPoly.EDU> dorourke@polyslo.CalPoly.EDU (David M. O'Rourke) writes:
>In article <2680@cadre.dsl.PITTSBURGH.EDU> gw@cadre.dsl.PITTSBURGH.EDU (Gerhard Werner) writes:
>>Does anyone have any information on driving multiple duplicate
>>displays (i.e. more than one monitor) from a single MacII,
>>using the standard Mac video card(s).
>
>  I believe all you need to do is put a video card in the MacII and plug
>a monitor into it.  The Monitor CDEV will then allow you to configure
>the two monitors to display them however you want.
>


Thats totally correct, I am writing this from a MacII with 2 monitors,
one color and one monochrome.  Both have 8-bit video boards.  In the
monitor cdev you can rearrange how they are placed wrt one another and
also where the menu bar and disk icons go.  The placement of the
startup screen is also selectable (you hold down the option key when
selecting the monitor icom in th econtrol panel).  The changes take
effect after reboot.  One thing that you cant do, that I would like is
to have the menu bar on one screen and the disk icons on the other. I
can do this using macromaker or somesuch but I would rather have them
configurable from the control panel.  I keep most of my finder windows
on the mono monitor and the active application(s) on the color
monitor. Trouble is MS Word and the like like to use the whole screen
and so you have to keep resizing windows to see the disk icons.  I may
be being dumb here but I havent read enough of my MS Word manual to
make the default window just small enough to see the disk icons.  

One
word of warning, once you have used 2 monitors you can never get used
to just one, let alone an SE or Plus screen!!

Hope this is of interest.
Cheers Jfm.



John Mansfield
North Campus Electron Microbeam Analysis Laboratory 2455 Hayward, Ann Arbor,
Michigan 48109-2143. 313-936-3352
Internet: jfm@ruddles.sprl.umich.edu or john_mansfield.um.cc.umich.edu

paul@taniwha.UUCP (Paul Campbell) (04/25/89)

In article <10654@polyslo.CalPoly.EDU> dorourke@polyslo.CalPoly.EDU (David M. O'Rourke) writes:
>In article <2680@cadre.dsl.PITTSBURGH.EDU> gw@cadre.dsl.PITTSBURGH.EDU (Gerhard Werner) writes:
>>Does anyone have any information on driving multiple duplicate
>>displays (i.e. more than one monitor) from a single MacII,
>>using the standard Mac video card(s).
>
>  I believe all you need to do is put a video card in the MacII and plug
>a monitor into it.  The Monitor CDEV will then allow you to configure
>the two monitors to display them however you want.

I think that he wants to put multiple monitors onto the same video card ...
the problem here is that video cabling is much like SCSI cabling - you need
to make sure that everything is terminated correctly otherwise you get
reflections which are visible as ghosting on the screen. Many monitors
have the terminating resistors built in, this means that you have to
remove the terminating resistors on all the monitors except for the last
one in a string. If you have more than 3 - 4 monitors you may also need a
special video splitter/amplifier (it has to be a special RGB one ...) which
splits things up into a number of strings, the last monitor in each string
should be the only one that is terminated .... finally you should note that
not all 'identical' monitors are the same, usually you will find some 
which have slightly different colors (this doesn't matter with just 1,
you notice it when there is one that's a little bluer than the other 14)
this can be solved by tuning the thing to match the rest or reordering the
monitors so all the 'blue' ones are together so that they are not so noticable.


	Paul

-- 
Paul Campbell
Taniwha Systems Design			UUCP:		..!mtxinu!taniwha!paul 
Oakland CA				AppleLink:	D3213

kaufman@polya.Stanford.EDU (Marc T. Kaufman) (04/25/89)

In article <2680@cadre.dsl.PITTSBURGH.EDU> gw@cadre.dsl.PITTSBURGH.EDU (Gerhard Werner) writes:
>Does anyone have any information on driving multiple duplicate
>displays (i.e. more than one monitor) from a single MacII,
>using the standard Mac video card(s).

No problem, but you can't use the standard cable.  Video signals from the Mac
video card are standard RS-172.  What you need is monitors that have
OPTIONAL 75 ohm termination.  Loop the signal through the monitors, and turn
the termination on for the last one only.  If you are doing this for a class,
you will probably get some 19+" monitors, and they generally have the ability
to loop signal and/or terminate.

Marc Kaufman (kaufman@polya.stanford.edu)

jfm@ruddles.sprl.umich.edu.engin.umich.edu (John F. Mansfield) (04/25/89)

In article <6926@bsu-cs.bsu.edu> mithomas@bsu-cs.bsu.edu (Michael Thomas Niehaus) writes:
>In article <10654@polyslo.CalPoly.EDU>, dorourke@polyslo.CalPoly.EDU (David M. O'Rourke) writes:
>> In article <2680@cadre.dsl.PITTSBURGH.EDU> gw@cadre.dsl.PITTSBURGH.EDU (Gerhard Werner) writes:
>> >Does anyone have any information on driving multiple duplicate
>> >displays (i.e. more than one monitor) from a single MacII,
>> >using the standard Mac video card(s).
>> 
>>   I believe all you need to do is put a video card in the MacII and plug
>> a monitor into it.  The Monitor CDEV will then allow you to configure
>> the two monitors to display them however you want.
>... 
>> David M. O'Rourke
>
>These are generally questions that I don't touch, because people have yelled
>at me for providing answers to the wrong question.  Notice the key word in
>the original message: DUPLICATE.  I gather from this one word that Gerhard


I have head that some of the overhead lcd projection screens use a
splitter so that you have the image on the projector and also on the
mac screen using just one regular mac video card.  Trouble is the lcd
screens are still not very good quality, the grey scale ones are still
pretty limited and pretty flakey. However, not to get too
side-tracked, I suspect you could use a similar splitter to run 2
regular screens.



John Mansfield
North Campus Electron Microbeam Analysis Laboratory 2455 Hayward, Ann Arbor,
Michigan 48109-2143. 313-936-3352
Internet: jfm@ruddles.sprl.umich.edu or john_mansfield.um.cc.umich.edu

mha@batcomputer.tn.cornell.edu (Mark H. Anbinder) (04/30/89)

In article <42d7cd62.a590@mag.engin.umich.edu> jfm@ruddles.sprl.umich.edu.UUCP (John F. Mansfield) writes:
>>> In article <2680@cadre.dsl.PITTSBURGH.EDU> gw@cadre.dsl.PITTSBURGH.EDU (Gerhard Werner) writes:
>>> >Does anyone have any information on driving multiple duplicate
>>> >displays (i.e. more than one monitor) from a single MacII,
>>> >using the standard Mac video card(s).
>
>I have head that some of the overhead lcd projection screens use a
>splitter so that you have the image on the projector and also on the
>mac screen using just one regular mac video card.  Trouble is the lcd
>screens are still not very good quality, the grey scale ones are still
>pretty limited and pretty flakey.

What the Mac world needs is a projection display system like the one
Steve Jobs used to display the NeXT computer at its introduction.  I was
astounded at the clarity of the image on a HUGE screen, which appeared
to be a faithful reproduction of the image on the computer Jobs was
playing on.

I asked around and found out what the display system was; apparently 
it's a ridiculously expensive system whose name I can't remember offhand
(I can find out again if anyone's really curious).  It's designed for
those applications where you absolutely HAVE to have a perfect image on
a screen for hundreds or thousands of people to view, and when this is
SO important that you'll pay many thousands of dollars for the privilege.

If someone could make this technology more affordable, and make it work
on the Mac, we'd be all set.  :-)


-- 
Mark H. Anbinder                                ** MHA@TCGould.tn.cornell.edu
NG33 MVR Hall, Media Services Dept.             ** THCY@CRNLVAX5.BITNET
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