Casio PV-1000/Cartridge connector

This diagram represents a top-down looking directly into the connector. The "B" side pins are on the label side of the cartridge.

Pin pitch is 0.1 inch. PCB thickness not yet known.

Cartridges are required to have a key cut between 10 and 11. No extra space is afforded for this: those pins are as close as any other pair.

  (front)                 (back)
  PV-1000    | Cart  |    PV-1000
              -------
      +5V -- |B01 A01| -- GND
     /IRQ <> |B02 A02| -- chassis ground
      A14 -> |B03 A03| <- A15
      A12 -> |B04 A04| <- A13
      A10 -> |B05 A05| <- A11
       A8 -> |B06 A06| <- A9
       A6 -> |B07 A07| <- A7
       A4 -> |B08 A08| <- A5
       A2 -> |B09 A09| <- A3
       A0 -> |B10 A10| <- A1
       D6 <> |B11 A11| <> D7
       D4 <> |B12 A12| <> D5
       D2 <> |B13 A13| <> D3
       D0 <> |B14 A14| <> D1
     /M07 -> |B15 A15| <- /MREQ
      /WR -> |B16 A16| <- /RD
    audio <- |B17 A17| <- /IORQ
      +5V -- |B18 A18| -- GND
              -------

With the exception of /M07 and audio, all the other signals are just connected directly to the Z80 and ULA

Expansion audio is mixed in via a 3.3kΩ resistor and 47nF capacitor, which means:

• There's a significant highpass filter with corner frequency 1026 Hz
• A square wave that's 0.5Vpp will be the same volume as SquareFA
• Increasing the output impedance and voltage of whatever drives the audio pin will lower the corner frequency of the highpass