[Coco] CoCo 1 / CoCo 2 video mode mod

[Robert Gault]

Richard Atkinson wrote:
> Hi,
> 
> With all the discussion of external character generator ROMs for lowercase
> characters, I had a look at the CoCo schematic and
> came up with an idea for some new video modes.
 ><snip>

You might want to remember that the Cocos 1&2 use more than just the 
6847 to generate graphics. The SAM 6883 is also involved and already 
makes use of many of your suggested GM#, A#/S, and INV settings for 
semigraphic S8, S12, & S24 modes. With the S24 mode, you can create any 
text character you could wish for. Additionally you have graphics with 
pixels of 4x1 size in 8 colors.