It will probably be the one that the computer is calling LPT3 that you are wanting, it is likely that LPT1 is just a ghost as windows is loading drivers for the non existant onboard port.
If there is no resource tab then try by going to Start, All Programmes, Accesories, System Tools and finally System Information. Look under Hardware resources then I/O and find your LPT ports, you can use the search bar at the bottom to get there quicker
It may be however that the port is no use as it seems like the a800 would be the correct address.
Hood