1. Apparatus for providing access to an electrically controlled service for predetermined periods of time comprising: a record medium adapted to have encoded thereon data indicative of a definite time period during which access to said service is to be permitted, a reader adapted to receive said record medium and store the data encoded thereon, said reader including a sensor for sensing the presence of said card therein and a housing having two closely spaced parallel plates and a plurality of posts disposed between said parallel plates to form a channel for slidably receiving said medium and guiding said record medium toward said sensor while preventing skewing thereof, a processor including a clock network having an output signal indicative of instantaneous time, a comparator for comparing the data stored in said reader with said clock output signal, and a security control device operable in at least two states, one of said states permitting access to said service and the other of said states preventing access to said service, said security device being responsive to said comparator for permitting and preventing access to said service as a function of the data encoded on said record medium.