I decided it might be fun to reverse the ATR8000. The schematic really sucks, at least, by todays standards. My first step is to redraw the schematic. The copy I have is a Rev C. Were there any other revs?
The second question is, does any body know the bit pattern in U46. This part is a 32x8 prom. But only 16x4 of it is being used. It would be nice if somebody has already done this, but I will get it myself if I have to.
Just for fun, here is the image of the Data Separator for the ATR8000.