Hi John,
Interesting! The 800 lb. gorilla in the room that everybody *tries* to ignore seems to be S100 video (80x24 or 25, that is).
Perhaps there is another option besides the 6845? Intel came out with a similar controller about the same time as Motorola introduced the 6845 - the i8275. It has similar capabilities, I think. There was a fellow (in Illinois, I believe) who sold a S-100 card, based on the i8275, back in the mid-80's. The big(?) selling point was that it produced VGA video (at a time when the whole microcumputer world was moving toward IBM and MS-Doze). I think I have one here somewhere, and maybe even a schematic and documentation? Might take me a while to find it, however (*grin*). I have NO idea about the availability of the i8275 anymore. It was a 40-pin DIP.
As far as the 6845 goes, the only video circuit I ever saw was one published in "Byte", in the Ciarcia column? Am I dreaming this? Anybody else confirm? Considering the source, it was most certainly NOT S-100. *shrug* Oh, and maybe there was another that came out in the "CRT Controller Handbook"? Again, probably NOT S-100. I'll have to look.
Love to hear peoples' thoughts about S-100 video.
Roger