[Coco] CoCo3 RBG Video Questions

[Bill Pierce]

I would definitely be interested in your "fiddling". I "rarely" use composite, so crisp RGB is perfect for me. It seems relatively cheap and connects to VGA of which I have about 4 13" square LCD monitors I've been saving for the Coco.


-----Original Message-----
From: Frank Thompson <frank.thompson.iv at gmail.com>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Sent: Thu, May 28, 2020 3:51 pm
Subject: [Coco] CoCo3 RBG Video Questions

Hi Everyone!

Based on some searches of past messages, I saw a tip about using a video
scaler to adapt the 15kHz RGB video signal from the CoCo3 to a standard VGA
monitor.

I purchased the scaler mentioned in these postings, an Extron DVS 304.  I
have some unusual behavior that I'm trying to isolate to determine who is
at fault:  the CoCo, my homemade RGB to DB15 cable, or the Extron unit.

So, to start, it took some fiddling with the knobs of the Extron to get it
to work, but now that it is set up, it is AMAZING.  The video signal is
just gorgeously clean and crisp.  (By the way, if anyone wants to know the
fiddling I needed to do to get it to work, let me know.  It is not relevant
to this present discussion so omitted).

I can boot up CoCo3 specific games in RGB mode and the video is awesome.
I've launched Robocop, Predator, Rescue on Fractulus, and FlightSim II.
However, some older games (not all) show up in a poor looking (fuzzy, but
legible) black and white screen.  Examples include Pitfall II and even my
Gamepak based Hunt the Wumpus.

I confirmed that the composite video out of the RCA jack on the back of the
CoCo is showing in proper color (hooking directly from CoCo to monitor).

I'm not sure if the issue is with the video scaler, the CoCo, or those
games just aren't usable with RGB monitors (I'm not sure why that would be
but I don't know the hardware).  If it is the fault of the scaler, does
that imply that there is a difference in the signals out of the CoCo RGB
port for the different games and the scaler just can't handle certain
differences?

Again, as a tangent, I can post more of my details of getting the Extron to
work (not much to it really) if people are interested.

Thanks all!

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