On the Wonderswan, you can connect on serial port
- a cable link (2 player support)
- a wonderwave (IR)
- a digimon connector
- a gps
- a sonar
- a mobilegate

How MAME allows to select what is connected to a port ?

I'm currently adding cable link support (using socket, similar to Sega Model1/2/32 driver), and so I'd like to know how to activate it ....