iirc (so many years) AMOS was based on DEC's RSTS hence a lawsuit which AM eventually won the western digital chipset that powered the first am systems was a

iirc (so many years) AMOS was based on DEC's RSTS hence a lawsuit which AM eventually won the western digital chipset that powered the first am systems was a five-chip 40-pin set connected by a private cmos bus ... probing with a scope was amusing the instruction set was basically identical to the pdp-11