Abstract: A security system that grants access to authorized persons includes a central controller, insertion-type card readers, proximity-type card readers, and an interface module that interfaces between the central controller and the proximity-type readers in order to make the proximity-type readers appear to the central controller as though they were insertion-type readers. When indentification data is presented to one of the card readers in the system, the identification data is passed to the central controller, which then checks its memory to determine whether the identification data identifies an authorized person. If the identification data is present in the memory of the central controller, then the person is authorized to enter, and the central controller sends a command to the approximate card reader instructing it to unlock the door that the card reader controls.