In the
Amiga 500 schematic picture "scanp6.JPG" shows the HY1 chip as being supplied with R0-3, G0-3, B0-3.
Perhaps the inputs to the HY1 "Video hybrid" can be hooked into such that one can grab the digital signal directly? then one could use a converter board to provide DVI (or HDMI) video or similar quality?
(I assume sync signals are the easy part)
