A printer port adapter which permits electronic keys to be accessed through the printer port of the PC, without disrupting the normal operation of the printer port in any mode of operation whatsoever. The electronic keys used have a one-wire signal interface, and this interface can be inserted into the...http://www.google.com/patents/US5506991?utm_source=gb-gplus-sharePatent US5506991 - Printer port adapter with overlaid one-wire interface for electronic key
