> The rear DB25 serial connector is an A & B serial port combined. > > Sun had/sold a special Y-splitter cable to use for the combined port.
The RS232 specification allows for 2 serial channels on the DB25 connector. Most machines only use the primary channel. and Sun were sensible enough to wire their '2 ports on one connector' so that port A uses the primary channel pins and port B uses the 'back channel'. This means that if you plug a normal, minimally-wired serial cable in (say an adapter to a PC DE9 port) you connect to port A. You only need the splitter cable if you want to use port B -tony
