Has anyone ever heard of the Apple YACC, or YACCintosh? it was a 68010 prototype mac intended to do colour in 1986. Weirdly enough someone managed to find the ROMs *and* the PALS for it, but no schematics have turned up yet.
All of the stuff is on bitsavers.
I do not know what to add here. This seems to be one of the most obscure – if not the most obscure – Apple efforts out there, as there are virtually zero references of it online.