[Coco] RGB to XGA (Bruce Borer)

[Bruce Borer]

Hi Andrew,
    Just like I did not know that the CoCo3 could do 225 lines, the CoCo3
can do 256 colours with the GIME-X.
So I decided to support it as well.  3-3-2 means 3 red bits, 3 green bits
and 2 blue bits or colour.
    My design currently supports 3-3-2  D/A on the output but only 2-2-2
A/D on the inputs from the CoCO3.  If I decide to get a GIME-X I may
support 3-3-2 on the input as well.

Bruce P. Borer
Cobourg, Ontario


On Thu, Jan 1, 2026 at 3:13 AM Andrew Ayers via Coco <
coco at listserv.adelphi.edu> wrote:

> Bruce,
>
> I'm not sure what you mean by "256 colours (3,3,2)", in relation to
> video from the CoCo 3...?
>
> The CoCo 3 doesn't generate 256 colors; to be clear, the "256-color"
> "mode" is an artifact color system; the colors are generated by how the
> four-color gray-scale is displayed by the limited-bandwidth of the NTSC
> composite video system (much like four colors in PMODE 4 are displayed
> on an NTSC composite video system, when only black and white are being
> actually used).
>
> I'm just confused in wondering if you understood what I was saying, or
> you've implemented something else, or I am misunderstanding what you are
> meaning by "256 colours" in your response?
>
> Andrew L. Ayers
> Glendale, Arizona
> phoenixgarage.org
> github.com/andrew-ayers
>
> On 12/31/25 7:28 PM, Bruce Borer wrote:
> > Hi Andrew,
> >      I got 225 lines working on my converter.
> > I now supports 32, 40 and 80 characters per line,
> > 192, 200 and 225 lines and
> > 256 colours (3,3,2).
> >     The new version of firmware needs to be uploaded to GitHub,
> > probably this week.  I also want to demonstrate on UTUBE.
> >
> > Bruce P. Borer
>
> --
> Coco mailing list
> Coco at listserv.adelphi.edu
> http://listserv.adelphi.edu/cgi-bin/mailman/listinfo/coco
>