Serial NB Card: Multiple Serial Port Support

The Serial NB Card theoretically gives you four additional serial ports. With the introduction of Apple Remote Access (ARA) MultiPort Server you can simultaneously use all four serial ports on a card.

However, there isn't any other software that uses more than one of these ports at a time. This includes MacX25, and SNA*ps, which cannot coexist on one card. You could continue using the two built-in serial ports with the one additional "external" serial NB port (in conjunction with MacX25 or SNA*ps software), so you could have a total of three serial ports available simultaneously.