Sure you can multiplex, but if the filter board has no active components, how would it do that?
If it's multiplexing on the pc board, it's no longer a standard lpt port.
Besides that, something needs to tell the multiplexer which devices to connect to the inputs, which is again not a standard LPT port feature.
It might help if someone could take pictures of the chips connected to the 30 pin connector. Those could help identifying the filter board interface. Mame code could probably help as well. No idea how well the Lindbergh is emulated in Mame.
If it's multiplexing on the pc board, it's no longer a standard lpt port.
Besides that, something needs to tell the multiplexer which devices to connect to the inputs, which is again not a standard LPT port feature.
It might help if someone could take pictures of the chips connected to the 30 pin connector. Those could help identifying the filter board interface. Mame code could probably help as well. No idea how well the Lindbergh is emulated in Mame.