battery drain when the power is available a battery assist circuit at 47 provides power for the interlock means 31 as long as normal power is available the digital logic circuit means 40 has a reset input 42 and has a pair of outputs 43 and 44 also provided to the digital logic circuit means 40 is an input conductor 45 that is critical to the interlock function the conductor 45 includes interlock switch means 32 and 32 39 a snap type switch 32 39 that has a moveable member 51 connected to a plunger 50 is one embodiment that can be used for this function a further terminal 52 is connected to ground 53 for the digital logic circuit means 40 whenever the fuel burner control means 26 in which the digital logic circuit means 40 is included is removed from the base means 12 the interlock means 32 changes the state of the digital logic circuit means 40 this can also occur if the base unit 12 is removed from mounting surface 19 the change in state is then recognized at the next operation of the system this means that for each time the fuel burner control means 26 or base means 12 is moved the interlock means 31 by means of the digital logic circuit means 40 causes the need to reprogram so that the program is appropriate for the particular installation being controlled it is apparent that the present invention could be embodied in many physical configurations the physical embodiments would include a battery backup in a microcomputer based device and the need to reprogram the device being moved from one physical location to another the present invention entails a mechanical.