I wouldn't even assume it's parallel. There's a lot of interfaces out there that use a DB25 connector.
If it is for the PC, that one will almost certainly be one of the variety they used to refer to as a "Bus Mouse
", and it'll need a card of some description.
This isn't DB25, but I think some of the earlier specialised interfaces were.
It looks vaguely familiar. Can't place it yet though.
"dsakey" on trademe. Apple II's are my thing.