In an access system and method for buses, a master card and respective slave cards for respective students are provided. The cards are read by a card reader to control access to the bus. A microprocessor and memory are provided together with an annunciator which determine whether a slave card annunciator...http://www.google.com/patents/US6631841?utm_source=gb-gplus-sharePatent US6631841 - Access system and method for buses
