[Coco] Coco 3 256 Color Composite Mode

[Andrew]

You miss a few emails and POW! You get sucker punched!

I haven't been following things lately due to all kinds of other issues 
getting in the way, but I was clearing out my email backlog a small bit 
and ran across this new graphics "mode". I can't believe it is this simple:

http://www.coco3.com/community/2009/02/256-color-mode-composite-mode-artifacting/comment-page-6/#comments

I haven't had time to try it (my CoCo 3 system is packed away for right 
now), but it makes complete sense. The thing that makes my stomach drop 
is how close the CoCo community was to seeing this mode, back in Rainbow 
days.

I remember an article that detailed using dithered colors on the 
640x200x4 color mode to get more colors; the sample programs were bar 
code displays (IIRC), and they used different colors (not the grey 
scale), essentially blending the colors. I think you could get 9 
pseudo-colors that way (?).

I don't know why NOBODY thought to use grey-scales; I sincerely believe 
that this is likely the "hidden" 256 color mode. I am glad this was 
discovered, I only wish it could have been done sooner.

Oh well. Something I now wonder: Could doing palette switching (ala 64 
color mode, or Sockmaster's modes) in this mode boost the number of 
colors any? Is there are way to poke some values in certain GIME 
registers to effectively use this mode, but manipulate it as if it truly 
were the 160x200 mode (ie, only have to deal with that number of bytes, 
instead of the larger number in the 640x200 mode - not sure if that 
makes any sense).

Anyhow - wow! I can't wait to try it, and see what else comes out using 
it; congrats and thank you to all involved!

--- Andrew L. Ayers, Glendale, Arizona