While rummaging through a box of old PC (5150) parts, I found a half-size
board that looks like a comm port board.  It was made by Forte Data Systems and
has a copyright date of 1986 on it.  The board provides a male 24-pin connector
and has 3 jumpers of 3 pins each, two labelled A B C.  I plugged it into my PC
and ran Advanced diagnostics several times, changing the jumper positions each
time, but the system did not recognise a comm port.

Does anyone have a clue as to what this board might be or how to configure it?
I could use another comm port if it's free.