From searching around I gather that there is a voltage pin at the end and ground at the other, and there must be a couple of pins to say whether the cart is being accessed in read or write mode. I think that 15 of them are used to address a memory location and 8 of them are used to output a byte (and maybe input it too, if you're in write mode). I don't really have complete information on it though.
Edit: I remember reading that there is an "audio" pin but that was never used in anything.
Edit 2: I found the answer here
- VCC – Power (5 volts)
- CLK – Clock signal (not used)
- ~WR – if low(grounded) and if RD is low, we can write to the SRAM and load a ROM or SRAM bank
- ~RD – if low (grounded) and if WR is high, we can read the ROM and SRAM
- CS_SRAM – if enabled, selects the SRAM
- A0 – A15 – the 16 addresses lines that we tell the ROM which particular byte of data we want to read
- D0 – D7 – the 8 data lines that we read the byte of data selected by the 16 address lines. These data lines can also be used to control which ROM bank to load (important for later).
- Reset – needs to be connected to VCC
- Audio in – (not used)
- GND – Ground