Abstract: A power interrupt device for detecting activity remote from the detector and/or device and for producing a signal capable of interrupting power to a load, such as an electronic display. The detector can sense remote activity, and the activity or associated object need not contact the detector. Depending upon whether the activity is present or not present, the detector and associated interrupt circuitry can turn on or off a power load device such as an electronic display. The power interrupt device is well suited for turning off an electronic display when a user is no longer in the room or working area. The computer can remain running, however, the associated display can be remotely turned off to reduce the amount of heat dissipated from the display during periods when the user is not present.

Abstract: A circuit which controls the selection and activation of one of a plurality of clock circuits arranged in copies. Selection circuitry is used to detect failure of an on-line clock circuit, scan a plurality of available clock circuits in a predetermined sequence and place the next available properly operating clock circuit on line. Control circuitry prevents erroneous clock selection during power-up/power down operations and enables predetermined clock circuit copies to be disabled.

Abstract: A clock synchronization system for use in a digital switching system including multiple clock circuits. This circuit includes multiple synchronization circuits connected in a master-slave arrangement. Each synchronization circuit includes a counter chain which provides a periodic system framing pulse and a trigger circuit which insures that its slave system framing pulse is in synchronization with the master system framing pulse.

Abstract: A circuit which selects and enables one of a plurality of clock circuits. Logic circuitry is used to detect failure of an on line clock circuit, scan a plurality of available clock circuits in a predetermined sequence and place the next available properly operating clock circuit on line.