[Coco] CoCo3 RBG Video Questions

rietveld rietveld rietveldh at hotmail.com
Thu May 28 16:23:49 EDT 2020

Just run this quick patch when you want to play any coco1/2 game that uses artifacting


  Original Message
From: Kevin Becker
Sent: Thursday, May 28, 2020 4:17 PM
To: CoCoList for Color Computer Enthusiasts
Reply To: CoCoList for Color Computer Enthusiasts
Subject: Re: [Coco] CoCo3 RBG Video Questions

Yeah, artifact colors don't work on RGB.  Solutions like the Switch-a-
Roo let you flip over to composite while still connecting to a modern
monitor so you can have the best of both worlds.
That being said, I think it would be worth it to document the
"fiddling" you did with the Extron so that can be documented for other
potential users.  There are a lot of VGA monitors in the world that
would be nice to use with CoCos.

On Thu, 2020-05-28 at 16:09 -0400, Jason Reighard wrote:
> Sounds like PMODE 4 artifact colors which do not work on RGB
> https://en.wikipedia.org/wiki/Composite_artifact_colors
> Jason
> On Thu, May 28, 2020, 3:51 PM Frank Thompson <
> frank.thompson.iv at gmail.com>wrote:
> > Hi Everyone!
> > Based on some searches of past messages, I saw a tip about using a
> > videoscaler to adapt the 15kHz RGB video signal from the CoCo3 to a
> > standard VGAmonitor.
> > I purchased the scaler mentioned in these postings, an Extron DVS
> > 304.  Ihave some unusual behavior that I'm trying to isolate to
> > determine who isat 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 itto work, but now that it is set up, it is AMAZING.  The video
> > signal isjust gorgeously clean and crisp.  (By the way, if anyone
> > wants to know thefiddling I needed to do to get it to work, let me
> > know.  It is not relevantto 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, butlegible) black and white screen.  Examples
> > include Pitfall II and even myGamepak based Hunt the Wumpus.
> > I confirmed that the composite video out of the RCA jack on the
> > back of theCoCo 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
> > thosegames just aren't usable with RGB monitors (I'm not sure why
> > that would bebut I don't know the hardware).  If it is the fault of
> > the scaler, doesthat imply that there is a difference in the
> > signals out of the CoCo RGBport for the different games and the
> > scaler just can't handle certaindifferences?
> > Again, as a tangent, I can post more of my details of getting the
> > Extron towork (not much to it really) if people are interested.
> > Thanks all!
> > --Coco mailing listCoco at maltedmedia.com
> > https://pairlist5.pair.net/mailman/listinfo/coco
> >

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