Expansion Connector Pinout [made by Kevin Horton (khorton@iquest.net)]
--------------------------

                                  +-------\
                              +5V |01   48| +5V
                              GND |02   47| GND
                         Audio In |03   46| NC
                              R/W |04   45| Out2 (from CPU)
                              A15 |05   44| Out1 (from CPU)
                cart con. pin #51 |06   43| Out0 (from CPU- strobe on sticks)
                Cart con. pin #52 |07   42| Cart con. pin #16
                Cart con. pin #53 |08   41| Cart con. pin #17
                Cart con. pin #54 |09   40| Cart con. pin #18
                Cart con. pin #55 |10   39| Cart con. pin #19
                  /OE for stick 2 |11   38| Cart con. pin #20
                     Player #1 D1 |12   37| /OE for stick 1
                     Player #1 D3 |13   36| Player #1 D4
                             /IRQ |14   35| Player #1 D0
                     Player #2 D2 |15   34| /OE for stick 1
                     Player #2 D3 |16   33| Player #1 D2
                  /OE for stick 2 |17   32| D0
                     Player #2,D4 |18   31| D1
                     Player #2,D0 |19   30| D2
                     Player #2,D1 |20   29| D3
                        Audio out |21   28| D4
                        Video out |22   27| D5
                              +9V |23   26| D6
                      4.00MHz CLK |24   25| D7
                                  +-------/
                              Expansion Connector

NOTES: Pins 06-10 and 38-42 Come directly from the cartridge connector. With
       those pins, you can pass 10 bits of whatever you like to/from the
       expansion port to/from a cartridge board.
