Having a nightmare getting the full frame de-interlaced scandoubler working. Turns out that even the default mode has different pixel widths depending on the rom version! I have a plan, it's ongoing Needless to say, its hard.
On the upside, the changes I have to make should make compatibility better with random screen modes. The de-interlaced progressive scan picture looks amazing with the Mode Mania images.
Any update on this? I have the CGAtoRGB adapter, got it in 2017 but I think I fried it somehow. (my GBS8220 is fried too) It's not working anymore with my new GBS8220. Very interested in the "C128 Video Mux NTSC" or whatever is to replace it.