Thursday, October 7, 2010

VGA Monitor ID Signal

VGA monitor ID signals

From: Newsgroups: sci.electronics Subject: Re: VGA monitors Date: 22 May 91 01:49:05 GMT Organization: The Portal System (TM) 
Mike Diack asked about VGA monitors.

Mike, I don't know if this is related to your problem or not, but IBM monitors have 3 pins dedicated to a "monitor ID" code, which is available to the VGA (or 8514/A or XGA) card, and also to the software. OS/2 uses it, for example, to automatically install the correct display support. The code:

PIN 4      PIN 11      PIN 12           Meaning  n/c        n/c         n/c         No monitor attached  n/c        n/c         GND         Mono monitor with no support for 1024x768  n/c        GND         n/c         Color monitor with no support for 1024x768  GND        GND         n/c         Color monitor with support for 1024x768 
Maybe your projector is not providing the code to tell the VGA that it is there. If so, you can try modifying the plug.

DISCLAIMER: I know this works for some Sony monitors, which support 1024x768 but don't provide the proper code to the PS/2, so they come up in 640x480. By changing the plug, the system sees the monitor as high-res-capable, and configures itself for 1024x768. Whether grounding pins in your plug will your projector, however, I can't say (although I doubt it).

Good luck.


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