[Coco] CoCo3 RBG Video Questions

[Jason Reighard]

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 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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