example of controlling a relay from the PC parallel printer port
http://ourworld.compuserve.com/homepages/Bill_Bowden/page6.htm#PPRIC
gives you 256 different positions over the full range of the servo
http://www.geocities.com/SiliconValley/Lakes/7156/articl4.htm
http://www.geocities.com/zoomkat/ppswitcher.htm
http://www.geocities.com/zoomkat/ppswitcher2.htm
http://www.geocities.com/zoomkat/ppswitcher3.htm
http://www.electronicsforu.com/efylinux/circuit/jun2000/cir1.htm
venerable parallel-printer adapter has found many uses during its long lifetime
http://www.edn.com/archives/1995/062295/13df3.htm
http://sound.westhost.com/project28.htm
http://www.geocities.com/CapeCanaveral/Launchpad/3632/sonar.htm
http://www.opamplabs.com/intercom.htm