Abstract: A distributed control switching system where the system control units cooperatively perform the terminating port determination function. In particular, the directory number translation function is done in a manner allowing flexibility in assigning directory numbers to switching system ports but minimizing the magnitude of the storage facilities required in each control unit. Each control unit stores the complete directory number translation for certain directory numbers but stores an index referencing other control units for the other directory numbers. Advantageously, the control units referenced are not necessarily the same ones that are associated with the ports defined by those other directory numbers. Thus the call setup sequence frequently involves three control units-the units associated with the originating and terminating ports, and an intermediate unit which stores the directory number translation information for the received directory number.

Abstract: A technique for moving and presenting an article to a work station is described. A plurality of articles, loaded onto a conveyor system, are moved so that a leading article is positioned at a pick-up and elevating station (46). A separating mechanism (44) is activated to lift (via 90, 91) from the conveyor system (42) all of the articles which trail the leading article, and to move them a predetermined distance behind and away from the elevating station (46). Next, the leading article is elevated above the plane of the conveyor system in order to facilitate its removal therefrom (FIG. 3).

Abstract: A substantial reduction in the common-mode noise generated by a switching-mode power converter is achieved by incorporating a multifilar-wound transformer into the converter in such manner that the inter-winding capacitances cause a cancellation of common-mode, noise components at the converter output.

Abstract: When a floating battery feed circuit is used to power telephone lines, it is desirable to provide an anti-corrosion biasing circuit to keep the voltage on the tip and ring conductors from becoming positive. This can be done using an anit-corrosion circuit that sinks a dynamic amount of current from the tip conductor. A line circuit including such biasing is, however, incompatible with special lines such as PBX lines that rely on a grounded tip conductor in the talk state. In accordance with the present invention, a constant current is supplied from a ground reference circuit to the ring conductor of such special lines only when loop current is flowing. The magnitude of this supplied current is such that the anti-corrosion circuit holds the tip conductor sufficiently close to ground potential to allow the proper operation of circuits connected to the special lines.

Abstract: A method and an apparatus for operating a display monitor to prevent burn-in of the screen. The entire display is imperceptibly moved in both vertical and horizontal directions by changing the temporal relationship between the information signal transmitted to the monitor and the signals used to synchronize the scanning of the screen.

Abstract: The microprocessor unit of a system implemented using metal-oxide-silicon (MOS) technology, is driven by a variable-frequency clock. The microprocessor controls the clock frequency based on the present rate of required microprocessor activity. By driving the microprocessor unit at a lower clock frequency when such activity rate is low, the energy dissipated by the microprocessor unit is reduced due to the MOS power-frequency characteristic.

Abstract: A test arrangement and method for use prior to the replacement of a first switching system serving a plurality of subscriber lines via a digital carrier facility and via a remote terminal, by a second switching system, where facility interface equipment of the second system is bridged directly onto the digital facility to allow monitoring of digital signatures transmitted from the remote terminal during the continued, uninterrupted operation of the first system. A pair gain test controller of the first system is advantageously used by the second system to control the generation of such digital signatures to verify the consistency of the translation databases of the two systems in associating directory numbers with subscriber lines.

Abstract: A distributed control switching system where the system control units cooperatively perform the terminating port determination function. The partial results obtained when a first control unit is unable to fully determine the terminating port are advantageously used by the second and subsequent control units such that time-consuming database access tasks are not unnecessarily repeated.

Abstract: A method and apparatus for bus contention resolution for use in a digital communications system wherein a plurality of communications controllers are connected to a shared bus for transmitting information in frames. A priority field is included in each transmitted frame. The bus is monitored such that any time the bus is conveying a frame, the priority field of that frame is known at each of the communications controllers. A given communications controller makes a determination based on the priority fields of a new frame and a present frame being actively conveyed by the shared bus that the new frame is of higher priority than the present frame. Upon such a determination, the given communications controller transmits the new frame.

Abstract: A method of assuring that each of a plurality of contemporaneously active database transactions comprising at least one read transaction and at most one update transaction has a consistent view of a database storing a plurality of versions of a relation. A transaction has a consistent view of a database if the data available to a transaction are not changed during its execution. An access dictionary is stored comprising an array of access blocks each defining the database location of one of the relation versions. At any given time, only one of the relation versions is defined as current. A relation dictionary comprising an array of relation blocks is stored such that as each database transaction is begun, a relation block associated with that database transaction is stored defining the access block defining the database location of the relation version then defined as current.

Abstract: An integrated packet switching and circuit switching system comprising a number of switching modules each connected to a corresponding plurality of user terminals. Each switching module includes a time-slot interchange unit for providing circuit-switched communication channels and a control unit that controls the operation of the time-slot interchange unit. Each switching module also includes a packet switching unit used both to provide packet-switched communication channels among the user terminals connected to that switching module, and to switch control information between the user terminals and the control unit to establish circuit-switched calls and packet-switched calls. A time-multiplexed switch interconnects the switching modules to provide circuit-switched communication channels and packet-switched communication channels between user terminals of different switching modules.

Abstract: A method of testing interfaces between computer program modules. The individual cause/effect charts of each of the modules are used to test the interfaces between the modules by executing the test cases in the charts in such manner that each test case need only be executed once. The variables passed between modules are monitored and compared with the input conditions in the charts.

Abstract: An integrated packet switching and circuit switching system comprising a number of switching modules each connected to a different plurality of user terminals. Each switching module includes a time-slot interchange unit for providing circuit-switched communication channels and a control unit that controls the operation of the time-slot interchange unit. Each switching module also includes a packet switching unit used both to provide packet-switched communication channels among the user terminals connected to that switching module, and to switch control information between the user terminals and the control unit to establish circuit-switched calls and packet-switched calls.

Abstract: An arrangement comprising a host switching system and a number of remote switching modules which are directly interconnected such that voice and data traffic as well as control information can be conveyed between modules without being routed through the host system network. The arrangement allows the integrated stand-alone operation of the remote switching modules and advantageously reduces traffic through the host system network during normal operation.

Abstract: A two-stage, rearrangeable multiconnection switching network for connecting N.sub.1 input channels to n.sub.2 output channels. The network comprises a number of first stage switches and a second stage switch, e.g., rectangular arrays. The second stage switch has n.sub.2 outlets each connected to one of the n.sub.2 output channels. A connection arrangement connects each of the first stage switch inlets to an associated predetermined input channel such that for any group of n.sub.2 of the input channels, there is a group of n.sub.2 of the first stage switches each having one inlet connected to a different one of that group of n.sub.2 of the input channels. The approach is easily extendible to switching networks serving any larger number, N.sub.2, of output channels by adding second stage switches and connecting each additional second stage switch to each first stage switch. In larger networks, the first and second stage switches are themselves replaceable by two-stage networks in accordance with the invention.

Abstract: An arrangement comprising a host switching system and a number of remote switching modules which are directly interconnected such that voice and data traffic as well as control information can be conveyed between modules without being routed through the host system network. The arrangement allows the integrated stand-alone operation of the remote switching modules and advantageously reduces traffic through the host system network during normal operation. For each pair of remote switching modules, one of the modules selects the channels of the direct interconnection which are used for conveying information between the modules.

Abstract: An arrangement comprising a host switching system and a number of remote switching modules which are selectively interconnected by a time-multiplexed switch such that voice and data traffic as well as control information is conveyed between modules without being routed through the host system network. The arrangement allows the integrated stand-alone operation of the remote switching modules and advantageously reduces traffic through the host system during normal operation.

Abstract: A duplicated switching system including a number of communication units wherein each digital word transmitted by an originating communication unit is conveyed via both of the duplicate time-multiplexed switches in the system and a destination communication unit autonomously selects the digital words to be used for further communication based upon whether the word error check portions can be derived from the word information portions. Advantageously, the system continues to operate in the presence of system faults not simultaneously affecting digital words from both time-multiplexed switches without any erroneous words being used for further communication and without involving a system central control.

Abstract: A method and apparatus for graceful preemption on a digital communications link used for selective communication from a plurality of user devices. Link controllers are used to implement the enforcement of a protocol on the link. When a first user device is actively communicating over the link, a second user device can gracefully preempt the first user device by having a link controller transmit a preempt character. The link controllers at either end of the link each save values of a set of status variables collectively defining the status of the link controller. When the second user device relinquishes link access, the saved values are used to return the link controllers to their status at the time of preemption such that the first user device can resume communication from the point of interruption without requiring data retransmission.

Abstract: Apparatus for interconnecting a printed wiring board (10) and an electrical module carrying board (50) with zero insertion force. Conductors (15) permanently connected to the PWB (10) and extending substantially at right angles therefrom, pass freely through insulative actuator plate means (20, 21) and then extend freely through the plated-through holes (52, 53) of the module board (50). Manually operable cam means (37, 46, 49, 33, 35) are provided which cause opposite lateral movement of the actuator plate means (20, 21). The actuator plate means (20, 21) in turn act against the conductors (15) to cause their flexure into electrical contact with the walls of the plated-through holes (52, 53) of the module board (50).