A portable cable identifier and tester assembly for a four line token ring network type cable, including a first unit having a power supply and connector mateable to one end of the cable and a second unit mateable to ends of potentially matching cables to provide a signal indicating cable identification....http://www.google.ca/patents/US4837488?utm_source=gb-gplus-sharePatent US4837488 - Portable identifier and tester units for computer communication cables
