Nantettatte!! Baseball pinout

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