Nantettatte!! Baseball pinout

                        Deck | CART | Deck
                             /------.
                       M2 -> |02  01| -- GND
SS4 PRG /CE | SS4 PRG A17 -> |04  03| <- SS4 WRAM /CE | CPU R/W | $F000.4
                   CPU D3 <> |06  05| <> CPU D2
                   CPU D4 <> |08  07| <> CPU D1
                   CPU D5 <> |10  09| <> CPU D0
                   CPU D6 <> |12  11| <- CPU A0
                   CPU D7 <> |14  13| <- CPU A1
                  CPU A10 -> |16  15| <- CPU A2
              SS4 PRG A16 -> |18  17| <- CPU A3
                  CPU A11 -> |20  19| <- CPU A4
                   CPU A9 -> |22  21| <- CPU A5
                   CPU A8 -> |24  23| <- CPU A6
                  CPU A13 -> |26  25| <- CPU A7
              SS4 PRG A14 -> |28  27| <- CPU A12 
                      +5V -- |30  29| <- SS4 PRG A15 
                             \------' 
                      2x15 pin 0.1" edge connector
              

• Pin numbers correspond to the markings on edge connctor
• Even pins are on the label side of external cartridge (02=leftmost)

Source: [1], [2]