KS-201 pinout

National Semiconductor KS-201: 28-pin DIP (Canonically NES 2.0 Mapper 554)

           .-\_/-.
 CPU M2 -> |01 28| -- +5V              
 CPU A1 -> |02 27| -> PRG A13
 CPU A2 -> |03 26| -> PRG A14
 CPU A3 -> |04 25| -> PRG A15
 CPU A4 -> |05 24| -> PRG A16
 CPU A5 -> |06 23| -> CHR A13
 CPU A6 -> |07 22| -> CHR A14
 CPU A7 -> |08 21| -> CHR A15
 CPU A8 -> |09 20| -> CHR A16
 CPU A9 -> |10 19| -> PRG /CE
CPU A10 -> |11 18| <- unknown input (VCC)
CPU A11 -> |12 17| <- CPU /ROMSEL
CPU A12 -> |13 16| <- CPU A14
    GND -- |14 15| <- CPU A13
           '-----'

This was also used on NES 2.0 Mapper 312:

           .-\_/-.
 CPU M2 -> |01 28| -- +5V              
 CPU A1 -> |02 27| -> PRG /A14
 CPU A2 -> |03 26| -> PRG A15
 CPU A3 -> |04 25| -> PRG A16
 CPU A4 -> |05 24| -> n/c
 CPU A5 -> |06 23| -> n/c
 CPU A6 -> |07 22| -> n/c
 CPU A7 -> |08 21| -> n/c
 CPU A8 -> |09 20| -> n/c
 CPU A9 -> |10 19| -> n/c
CPU A10 -> |11 18| <- unknown input (VCC)
CPU A11 -> |12 17| <- CPU /A14
    n/c -> |13 16| <- CPU /ROMSEL
    GND -- |14 15| <- CPU A13
           '-----'