Abstract: To provide a suitable number of display fields (e.g. ARRIVAL; TIME; etc.), each of which characterizes and identifies the significance or import or meaning of a displayed numerical value on a display device (16), the display fields are associated in groups or sets (11-15; 42-45) having a particular geometric position (columns; segmental), and a plurality of keys (21-25) are provided with each key being associated with a group or set of the display fields, and connected to a counter (61) to select a particular one of the display fields within the group or set by the number of key operations, the numerical value associated with the display field then being displayed on the numerical display (16).

Abstract: To supervise a program controlled device which is subject to stray noise or disturbance pulses, particularly microprocessor controlled automotive vehicle electronic systems, a timing circuit is provided responsive to check pulses added to the program and defining a timing interval, the monitoring system distinguishing between disturbance pulses and static defects by supervising the control pulses and, upon failure of the control pulses, generating a program restart or interrupt signal, respectively, which both initiate a new start of the program cycle or, respectively, define a timing interval which, upon failure to sense further control pulses, initiates energization of an emergency switching system. Continuous failure to receive control pulses also can initiate the emergency switching system.