[Coco] CoCo3 RGB port question...

John W. Linville linville at tuxdriver.com
Sat Dec 30 20:23:25 EST 2017

At one point Roy Justus was going to use it for signaling related to tuning his VGA adapter with software running on the CoCo. I'm not sure if he ever put that to good use or not.
Sent from my Verizon 4G LTE smartphone

-------- Original message --------
From: Zippster <zippster278 at gmail.com> 
Date: 12/30/17  7:18 PM  (GMT-05:00) 
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com> 
Subject: [Coco] CoCo3 RGB port question... 

Hello everyone,

On the CoCo3’s RGB port, pin 10 is held high by a pull up and goes to PB3 (PIN 13) of PIA 1 (Audio).

I vaguely remember a thread long ago discussing this that basically seemed to relate that this was
intended as some sort of display ‘sense’ pin, to be used to detect the presence of an RGB monitor.

From what I remember it was also said that this feature was never used to anyone’s knowledge.

Does anyone know if this is true, or exactly what the deal is with this pin?

- Ed

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