An area navigation system including a map display unit for entering navigation information to form or modify a programmed navigational route is disclosed. The map display unit is connected to an area navigation computer to supply a cartographic display of a geographic area relevant to a particular navigation...http://www.google.com/patents/US4086632?utm_source=gb-gplus-sharePatent US4086632 - Area navigation system including a map display unit for establishing and modifying navigation routes
