Looking at the memory map of the dragon here> http://www.dragondata.co.uk/Publications/InsideTheDragon.pdf (page17) I think the best way for compatibility is to overlay text on graphics.
As the text is stored in a lower area of memory, one could "poke" the character codes into this area then poke another register to allow video overlaying of the text over the graphics screen. quite why Rotomoulder (Motorola) didn't incorporate this simple feature in the original 6847 is beyond me.
I like your Godil project, but I'm looking to leave most of the existing IC's in place and simply remove the MC6847 and drop in a replacement FPGA on a PCB. The Godil will do this but I DO NOT want to remove any other IC's from the PCB and any extra modes etc would require FPGA based RAM to that, to all intents and purposes, the Dragon sees nothing has changed.
I would like to have 8 colours or more per pixel in max res (256 X 192) and not be limited to green & black or duff and black in top res.
I have looked at the Dragon BASIC and it SEEMS to write whatever you tell it to to Video RAM, that is if you say COLOR 8 it does just that, but the MC6847 simply outputs black or white. I would be nice to SET a pixel like SET 128,64,8 ir set the Pixel @ 128 X 64 to colour 8.
I don't think much more work other than the GODIL project is required, except maybe for the text / graphics overlay.
I'm thinking to do the text like ZX Spectum attributes. In text mode the Dragon would see the normal 32X24 and the normall graphics memory with the text being "clocked" out at a sub multiple of the graphics dots (if you can see what I mean).
What to do next?