[Coco] RGB to XGA (Bruce Borer)

[Andrew Ayers]

Though as you said, the Pico probably couldn't handle it, it would be 
nice if you could get the 256-color mode to "work" (or emulate it in 
some fashion). I'm not if any of the adapters do this (versus just 
running the actual composite output or something)?

Also - you may want to adjust things, if you can, to allow for the 225 
line mode; not super-critical, as I don't know if there is much that 
uses it.

How about the other "usable" modes? The CoCo 3 has a few other modes 
that can be dropped into, but aren't supported by BASIC - POKEs can get 
you into them, but really for anything reasonable you need ML. I think 
only a couple of them are actually usable for anything (IIRC, they are 
both a 160x192x16 color mode, and a 256x192x16 color mode; there also 
may be 4 and 2 color modes for each, I forget); I think they are 
mentioned in the service manual, and are also really detailed in some 
memory maps floating out there (including one mode that is something 
like 320x"infinite" that scrolls vertically; I think one of the guys on 
this list or elsewhere did a sound visualizer with it).

I take it that the SG modes all look ok (there's only a few on the CoCo 3)?

Additional resources which may be of interest:

https://github.com/hoglet67/RGBtoHDMI
https://retrohackshack.com/product/rgbtohdmi/

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https://github.com/qbancoffee/coco_rgb_to_hdmi_adapter/tree/main (might 
be related to the above adapter, unsure)

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https://www.thingiverse.com/thing:5528298 (unfortunately, just an STL 
file, so modding it may or may not be easy?)

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Hope these help or inspire...

Andrew L. Ayers
Glendale, Arizona
phoenixgarage.org
github.com/andrew-ayers