A method and an apparatus distinguish the origin of operator inputs in electronic control systems having at least one first operating element and at least one second operating element. The representation conversion may be made by a proxy server, for example, to make transmission of the returned information to the client more efficient, andor to render the returned information in a format suitable for display by the client. If one AD converter is used, the AD converter is non-linear. An insulating film is formed over the first insulating film and the third oxide semiconductor film.