Leg 16 is used by the ASIC to select the RAM bank to use. All other signals are totally parallel.
[[File:Piggy-backing-ram-pin16.png|framed|center]]
'''3) Pin 16 of both ram chips must be connected to ASIC NCAS1 (pin 91)'''
It is very easy to spot this leg, since it is the one just after the 90 written on the board, and it is not connected to anythin. (Beware, pin 89 just on the other side is a ground pin. Using it would select the RAM for all access and mess up everything.
[[File:Asic-pin-91.png|framed|center]]