To further improve video quality on the Dragon 32 this board completely isolates the video circuits from the rest of the Dragon by making it a plugin. This also means that only a single version of the Dragon rev 3 board is needed to provide a PAL or NTSC solution.
This is a complete first hack at the design, based on the reference design in the 6847 datasheet with supporting information from the MC1372 datasheet.
The generator and amplifier circuits are isolated and should be good for a clean video signal.
Given most modern TVs work with NTSC and PAL, switching automatically, this slimline video board (compared to the PAL version of the board) should be a cheaper and more attractive option. The component count is much lower and the harder to find analogue multiplexer is not needed.