Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!mintaka!bloom-beacon!eru!hagbard!sunic!mcsun!ukc!tcdcs!mee.tcd.ie!richard
From: richard@mee.tcd.ie
Newsgroups: sci.electronics
Subject: Re: VGA monitors
Message-ID: <1991May20.143019.1@mee.tcd.ie>
Date: 20 May 91 14:30:19 GMT
References: <1991May18.074619.18581@kcbbs.gen.nz>
Sender: news@cs.tcd.ie
Organization: Microelectronics Dept, Trinity College Dublin
Lines: 20
Nntp-Posting-Host: ampere

> Anyone know how a VGA card senses that a monitor is connected (or not) 
> Problem : connect a sony video projector up to a vga port on a computer 
> via a transparent interface , and nothing happens - piggyback a standard 
> monitor on to the port and BOTH projector ond monitor work fine. How 
> did the computer "know" that the monitor was there , and how can i dummy 
> up the connections so the computer works into the projector WITHOUT 
> the monitor ... all helpful hints appreciated , thanx , M.D.


I think the solution is to ground pin 11 on the vga card to pin 10 (digital
ground) this pin is monitor i/d and floats to hi if left unconnected.
A similar thing happens if you boot the pc without a monitor attached, the
card switches to monochrome mode and won't let you soft-switch it back up
without rebooting.

-Richard.

Richard Bolger                //
Trinity College Dublin       //       rbolger@vax1.tcd.ie       
Republic of Ireland         //