ΜPD7755C/µPD7756C pinout

NEC µPD7755, µPD7756: 18-pin 0.3" DIP (used with mappers 18, 72, 86, and 92)

         .--V--.
  I4  -> |01 18| <- I3
  I5  -> |02 17| <- I2
  I6  -> |03 16| <- I1
  I7  -> |04 15| <- I0
 Iref -> |05 14| <- /START
SOUND <- |06 13| <- /CS
/BUSY <- |07 12| <- X1
 /RST -> |08 11| -> X2
  Gnd -- |09 10| -- Vdd
         '-----'

The amount of current flowing into Iref specifies the amount of current flowing into the SOUND output when the DAC is set to 16 (1/32nd full scale). This is usually configured with an external resistor.

X1 and X2 should be hooked up to a 640kHz ceramic resonator.