A large number of keys arranged in a matrix are provided on the keyboard (KB) of a host computer. Of these keys, keys (K10, . . . , K15, . . . ), located at positions corresponding to Learning terminals in a classroom, are assigned to the respective learning terminals....http://www.google.fr/patents/US5011414?utm_source=gb-gplus-shareBrevet US5011414 - Key-input apparatus or CAI system
