Abstract: Control of communication by a plurality of devices, such as computer programs and terminals, via a computer is controlled by an arrangement referred to as a connector. The connector receives a request for communication defining the devices to the communication and, in response to the request, establishes a mapping table defining the source devices and destination devices to the connection. A source device stores data in connector memory and the connector reads the mapping table to determine the destination devices for the stored data. The connector then creates a linked list coupling structure between the stored data and the determined destination devices. The destination devices issue read commands to which the connector responds by reading the stored data in accordance with the coupling structure and providing that data to the requesting device.

Abstract: A broadband packet switch arrangement comprising a broadband packet unit connected to a plurality of customer lines and a video switch for selectively connecting packetized video signals from a plurality of video sources to the customer lines. The broadband packet switch unit selectively connects customer lines and transmits received control packets received from the customer lines to a control unit which responds to video request packets by controlling the video switch to connect selected video packets to the customers lines. Each customer line includes a selector circuit which receives video packets and inter-customer broadband ISDN packets and merges them onto the customer line. After the control unit has granted permission to connect a video source to a customer line, video source change requests for the line are sent directly to the video switch which responds thereto by connecting a requested video source to the customer line.

Abstract: The switch units of a distributed switching system are connected by a central switch for advancing connections between the switch units and also by inter-switch unit trunks. To save switch unit resources, trunk services such as scanning and signaling are not provided to the inter-switch unit trunks while the central switch is available for advancing connections. When the central switch becomes unavailable for advancing connections, as detected by control units in the switch units, the inter-switch unit trunks are connected to the trunk serving circuitry of the switch units and connections are advanced between switch units over the inter-switch unit trunks. Serving the inter-switch units trunks while the central switch is unavailable requires additional switch unit resources but provides for continuity of service which would to otherwise be lost due to the unavailability of the central switch.

Abstract: A switching arrangement is disclosed in which connections are advanced between lines and trunks of a first telecommunication switching system via a central switch of the first telecommunication switching system and, when the central switch is unavailable, via a first trunk from the first telecommunication switching system to a second telecommunication system and a connection through the second telecommunication switching system to a second trunk back to the first telecommunication switching system. The first switching system comprises a first and second unit connected by the first and second trunks, respectively, to the second switching system. A control unit in the first switch unit determines when the central switch is unavailable and in response to a dialed request for connection to a line or trunk at the second switch unit, advances the connection via the first trunk to the second switch system.

Abstract: A packet distribution network including a distributed arrangement for selecting packets based on the availability or unavailability of packet destinations is disclosed. A plurality of input units receive and store packets before distribution. Each input unit also receives a sequence of addresses representing packet destinations and a sequence of usage indicators each describing the availability or unavailability of an associated one of the destination addresses. The sequence of addresses and the associated usage indicators are provided to the input units such that the address of each packet destination is contemporaneously received by only one input unit. Each input unit selects a stored packet based on the received destination addresses and associated usage indicators and marks previously available destinations unavailable to other input units by modifying the usage indicator associated with a packet destination for which a packet is selected.

Abstract: A packet switching arrangement in which packet retransmission is provided by the network for packets found by the network to be unusable. A packet switch node is equipped with a packet path and a control signaling path cooperating with packet address route arbitration and gating circuitry for effecting the packet retransmission. As a packet from a network input unit is passed from switch node to switch node a control signaling path through the switch nodes back to the input unit originating the packet is established. When a switch node detects an unusable packet a retransmit control signal is returned via the control signaling path to the input unit originating the packet. The input unit responds to the retransmit signal by resending the original packet. An unusable packet is blocked from further transmission in one embodiment and marked for removal at the network output ports in another embodiment. Unusable packets result from packet corruption or from packet collision within a switch node.

Abstract: A packet switch arrangement in which a first plurality of user devices is connected to a packet network by a first interface unit and a second plurality of user devices is connected to the packet network by a second interface unit. A virtual circuit is established between the interface units and control information is exchanged over the virtual circuit. The control information defines virtual channels on the virtual circuit and ones of the first and second pluralities of user devices which are to be sources and destinations for data in the defined virtual channels. Data from user devices is packetized and transmitted in the virtual channels by the interface units in accordance with the exchanged control information. Further, packets received in virtual channels on the virtual circuit are distributed to user devices by the interface units in accordance with exchanged control information.

Abstract: A network architecture of the sort-then-expand type for routing packets including destination information is disclosed. The network includes a distribution stage comprising a plurality of input sorts units, an intermediate stage comprising a plurality of intermediate sort units and an output stage comprising a plurality of output switches. The input sort units each distribute a plurality of packets to the intermediate sort units such that each intermediate sort unit receives approximately the same number of packets destined for each output switch as the other intermediate sort units. Each intermediate sort unit identifies packet groups for a common output switch and connects the groups to the destination output switch. Each destination output switch merges the received groups of packets and distributes them to output ports.

Abstract: Optical switch networks and the design rules for creating them are disclosed. The networks comprise a plurality of input and output stages of optical switch elements. Each input optical switch stage is comprised of a plurality of 1 by 2 optical switch elements and each output stage is comprised of a plurality of 2 by 1 optical switch elements. Using these stages, optical switch networks are constructed where switch elements are interconnected by optical waveguides diffused in a substrate. Further, the connections between adjacent stages include optical waveguide crossovers (crossthroughs).

Abstract: A time-division switching system including first and second control units operating in accordance with a generic program is disclosed. After a new generic program is stored in the second control unit, the first control unit still operating in response to the old generic program initiates the performance of a test sequence by the second control unit. The first control unit times the execution of the test sequence. When the test sequence is not completed within a predetermined period of time or when test results generated by the test sequence do not match expected test results, a failure message is generated. Alternatively, when the test sequence is completed within the predetermined period of time and test results match the expected test results, a success message is generated.

Abstract: Methods and arrangements for associating control messages received in the D-channel of an integrated services digital network (ISDN) line with the call control process to which the message relates are disclosed. With ISDN, a single control channel, called the D-channel, can be used concurrently to control a plurality of calls. As each call is initiated, a call control process and data structure including the unique identity of the call, are created. The data structures associated with the same D-channel are linked together. When a control message including a given identity is received, the data structures associated with the D-channel conveying the message are searched in sequence until a data structure having the given identity is found. The contents of this data structure are used to access the control process associated therewith. When the search reveals no matching identity and the message is a call setup message, a new process and data structure are created.

Abstract: A time division switching system for providing telecommunications connections as defined by information stored in a plurality of control memories is disclosed. The switching system includes arrangements for transferring a new control program from a central control to a time-slot interchange unit controller associated with a time-slot interchange unit and connected line and trunk units. To generate a data base representing complete calls through the line and trunk units and the time-slot interchange unit, the time-slot interchange unit controller reads the information stored in the control memories, identifies complete telecommunications connections, and stores information defining such complete connections in a data base in a format usable by the new control program.

Abstract: A local area network comprising a plurality of terminals interconnected by a communication bus is disclosed. Each terminal comprises a memory, a main processor, and a co-processor. To transmit information in a communication mode, the main processor loads data into a transmit buffer area of the memory, and the co-processor reads the data from the transmit buffer area and transmits a packet on the communication bus. Similarly, the co-processor receives data from the communication bus and stores it in a receive buffer area from which it is read by the main processor for use. In an alternative mode, called the direct transfer mode, the co-processors are reconfigured so that data for transmission is read from the actual locations in memory where it is stored (not the transmit buffer area), and received data is stored in storage areas where it is expected to be used (not the receive buffer area).

Abstract: A connector (10) having two rows of opposed terminals (11, 12) joined by a pair of solder bars (13, 14) is mounted on a printed circuit board (16) with the terminals overlaying circuit board edge contact pads (15, 19) on opposite sides of the board. The assembled connector and circuit board is placed in a fixture whereafter pairs of comb devices are manipulated to position the comb tines between adjoining pairs of terminals. The fixture is conveyed at a fast rate in a first direction past a pair of heaters (34, 35) for preheating the two rows of terminals, the solder bars, and the circuit board pads. Next, the fixture is returned in a second opposite direction at a slow rate past the heaters to melt and thereby solder bond the comb held terminals to their corresponding board pads.

Abstract: Methods and arrangements for properly associating an alerting message from an ISDN user terminal with the control process associated with the message are disclosed. Each call, in a disclosed switching network, is associated with a call control process and data structure. When an external request for a call is received, a data structure including a predetermined broadcast Terminal Endpoint Identifier (TEI) and a call reference value selected by the network, is created. Further, a message including the broadcast TEI and the selected call reference value is sent to a user terminal. The user terminal responds with an alerting message including the selected call reference value and a TEI unique to that terminal (not the broadcast TEI). The switching network searches the data structures until a data structure is located which includes the call reference value of the received message and the broadcast TEI.

Abstract: A connector (10) having two rows of opposed terminals (11, 12) joined by a pair of solder bars (13, 14) is mounted on a printed circuit board (16) with the terminals overlaying circuit board edge contact pads (15, 19) on opposite sides of the board. The assembled connector and circuit board is placed in a fixture whereafter pairs of comb devices are manipulated to position the comb tines between adjoining pairs of terminals. The fixture is conveyed at a fast rate in a first direction past a pair of heaters (34, 35) for preheating the two rows of terminals, the solder bars, and the circuit board pads. Next, the fixture is returned in a second opposite direction at a slow rate past the heaters to melt and thereby solder bond the comb held terminals to their corresponding board pads.

Abstract: An arrangement for selectively connecting a first or a second frequency synchronous timing signal to an outgoing conductor is disclosed. When a transition from the first to the second timing signal occurs, the first timing signal is inhibited from being transmitting on the outgoing conductor and the logical AND of the second timing signal and a delayed version of the second timing signal is transmitted on the outgoing conductor for approximately one period of the timing signals. Thereafter, the second clock signal is transmitted on the outgoing conductor. Arrangements are also disclosed for switching from the second timing signal to the first timing signal.

Abstract: In a multiprocessing system, a method of efficiently maintaining a program process active while also ensuring that the process is deactivated when no longer needed. One or more subordinate processes are linked to a controlling process. Each subordinate process has an associated overall timer. As long as the controlling process keeps sending periodic keep-alive messages to a subordinate process, the associated overall timer is prevented from timing out. When the controlling process stops sending keep-alive messages, the associated overall timer times out and the subordinate process is deactivated.

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: A method and apparatus is disclosed for controlling the sampling of a composite analog color video signal so that the analog signal is sampled at precise locations relative to the phase of the color subcarrier of the color video signal in the absence of modulation. The invention thereby enables a digitized signal having a constant phase relationship relative to the unmodulated subcarrier phase to be provided which can be advantageously used in magnetic recording and reproducing apparatus. Since the constancy of the location of the samples relative to the phase of the color burst is maintained prior to recording, there is no phase error that would pose a problem during reproducing of the signal.