 Because of its relatively late debut, Prodigy was able to skip the intermediate step of persuading American consumers to attach proprietary boxes to their televisions; it was among the earliest proponents of computer-based videotex.NAPLPS-based systems (Teleguide) were also used for an interactive Mall directory system in various locations, including the world's largest indoor mall, West Edmonton Mall (1985) and the Toronto Eaton Center.It was also used for an interactive multipoint audio-graphic educational teleconferencing system (1987) that predated today's shared interactive whiteboard systems such as those used by Blackboard and Desire2Learn.