Well, can you be more specific? Are you talking about the PC's parallel port? If so, what standard i.e. SPP, EPP, or ECP?

If you're interested on the subject of PC parallel port interfacing there is a good reference on the subject. Check out http://www.lvr.com. There's a book called Parallel Port Complete written by Jan Axelson. She has written a very nice book on the subject, as well as several other references.

I hope this was useful.