Hey...just a guick update with a couple of links...
I found some helpful Dragon folks that were interested in this project. One of them ran the code on his PAL Dragon and posted the results on this thread. Surprisingly enough, the code seems to more-or-less work "as is".
I know that the PAL CoCo's and Dragons use the same (NTSC-only) 6847 VDG chip as the NTSC machines. They have added circuitry that basically puts the VDG to sleep while extra lines are added to drive the PAL display. I had presumed that those extra horizontal lines would be visible to the software, but apparently that isn't true.
I guess the lack of visibility for those extra lines is good news for this project. OTOH, I had thought that the horizontal sync signal could be a good timing source for sound/music playback. Now I would guess that those extra "invisible" lines would break any code using the horizontal sync signal for music playback. So, if I ever want to support PAL machines in some future music-enhanced version of Fahrfall then I will have to find another way to make it work...
Show Me, Show Me, Show Me!
I posted a few more examples of pics displayed using the 44-color technique on my CoCo. They are available in an album on my Facebook page. Have a look!