Abstract: A method and arrangement for controlling a time division switching system including a time multiplexed switch is disclosed. The time division switching system comprises a plurality of time-slot interchange units which connect subscriber sets to the input/output ports of a time multiplexed switch. When a connection is to be established between time-slot interchange units, a central control transmits to the time multiplexed switch a path setup message defining the input/output ports to be connected and the time slot to be used for such a connection. The time multiplexed switch controller responds to the path setup messages by disconnecting existing connections through the time multiplexed switch which potentially conflict with the requested connection, then by completing the requested connection. Accordingly, the switching system operates effectively without requiring separate disconnect messages when connections through the time multiplexed switch are no longer needed.

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: 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: 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. Each remote switching module selects the channels on the interconnection to the host system which are used for conveying information between the host system and the remote module.

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: Inexpensive Mn or Mg ferrites may be used as negative temperature coefficient thermistors. Fabrication of devices with the desired high temperature coefficients is facilitated by a processing method which forms a thin layer of oxidized and high resistivity material on a low resistivity layer of ferrite material.

Abstract: A method and apparatus for executing parts of a program process on two processors of a multiprocessor system. A home process resides in a home processor and is the destination process of all interprocess messages. The home process may call for the execution of a selected procedure on a remote processor. A call message is sent to the remote processor and a remote process is initiated. When the selected procedure has been executed in the remote processor, a return message is sent to the home process and execution of the home process is continued. Interprocess messages to the program process are received by the home processor and are forwarded to the remote processor. Interprocess messages generated by the selected procedure are transmitted by the remote processor, but are tagged with the identity of the home processor and home process.

Abstract: Communications between stations served by different time slot interchangers (TSI) nodes in a telecommunications network are made possible without the use of either an intermediate stage of time multiplex space division switching or central time slot allocation by an arrangement in which each TSI node is linked to every other node by a patent in which each nodes time slots are "broadcast" to every other node in the network. Each time slot word includes a data or address (D/A) field and a status (ST) field. The D/A field of the time slot word is made subject to interpretation by the contents of the ST field and indicates an encoded item of telecommunications information only when the ST field is "busy". When the ST field requests or acknowledges allocation of the time slot by a TSI, the D/A field respectively identifies the address of the target or requesting TSI.

Abstract: A time division switching system having a time-space-time architecture is disclosed. The time-multiplexed communication links of this system comprise a plurality of channels certain of which are used to convey control information and the remaining ones of which are normally used to convey digital representations of subscriber signals. When a large quantity of control information must be exchanged, the system preempts selected channels from conveying digital representations of subscriber signals and uses these preempted channels to convey the large quantity of control information.

Abstract: A bus fault location arrangement for locating the source of a fault condition on a bus connecting a plurality of devices energized by a power supply. When such a fault condition is detected, a bus diagnostic unit included in the arrangement transmits a signal to place a given one of the plurality of devices in a high impedance state. The bus diagnostic unit then transmits a given signal level on the bus. To determine whether the given device is the source of the fault condition, current flow between the device and the power supply is sensed and an error signal is stored when the sensed current exceeds a predetermined magnitude.

Abstract: A circuit for generating a common signal as a function of either of two reference signals comprises a pair of phase-locked loops which share an oscillator. Each phase-locked loop generates a control signal as a function of one of the reference signals. One or the other of the control signals is coupled to the oscillator which generates the common signal. A comparator compares the two control signals and generates a signal indicative of their difference. While the control signal generated by the first phase-locked loop is coupled to the oscillator, the difference signal is applied to the second phase-locked loop where it controls the generation of the second control signal to minimize the difference between the two control signals. While the control signal generated by the second phase-locked loop is coupled to the oscillator, the second phase-locked loop is nonresponsive to the difference signal.

Abstract: A time division switching system having distributed control processors is disclosed. The switching system includes time-slot interchange units having associated subscriber sets and a time-shared space division network for interconnecting the time-slot interchange units. Each of the time-slot interchange units and the time-shared space division network are controlled by separate control processors. In response to called subscriber set identifying information from a calling subscriber set, the control processor associated with the time-shared space division network completes the communication path through the time-shared space division network to connect the time-slot interchange units associated with the calling and called subscriber sets. The control processors in the time-slot interchange units then determine if communication path continuity is present between them before the subscriber sets are connected to the communication path through the time-slot interchange units.

Abstract: A time division switching system having distributed control processors is disclosed. The distributed processors exchange control messages and cooperate in the completion of talking paths between subscribers. Each control message includes an address portion defining the destination for the control message and is transmitted to a time-shared space division switch on the same time multiplex lines that speech representations are transmitted. Control messages are routed by the time-shared space division switch to a control distribution unit where the address portion is interpreted. When the address portion defines a distributed processor which controls the time-shared space division switch, the control distribution unit transmits the associated control message directly to that processor. Alternatively, when the address portion defines one of the other distributed processors, the control distribution unit transmits the associated control message to the defined processor via the time-shared space division switch.

Abstract: A trunk interface circuit (105) is disclosed for executing communication and signaling functions associated with telephone calls between subscriber stations of separate telecommunication systems (100, 140). A semiautonomous control circuit (200) is responsive to state signals generated from a central control circuit (120) for establishing the trunk interface circuit (105) in a plurality of states. The semiautonomous control circuit (200) comprises a memory (320) having predetermined data stored therein corresponding to each of the plurality of states. A processor (300) within the semiautonomous control circuit (200) executes certain of the communication and signaling functions as determined by the stored data corresponding to the present state of the trunk interface circuit (105). The communication functions comprise reception of periodic charging pulses from a distant office and subsequent transmittal of signals to the central control circuit (120) representative of the charging pulses.

Abstract: A time-division switching system for switching data words from data word sources received in channels of a time-multiplex line where a first plurality of data word sources uses a channel only once every n channels and a second plurality of data word sources uses a channel once every m channels where m is less than n and n is not an integer multiple of m. The switching system operates in response to control words sequentially provided by a control word source. The control word source of the disclosed embodiment comprises a first storage arrangement having n storage locations for storing control words and a second storage arrangement having m storage locations for storing control words. A storage reading circuit substantially simultaneously reads the contents of one storage location of both storage arrangements sequentially.

Abstract: An arrangement and method for providing operator services to a plurality of subscribers wherein each subscriber is associated with one of a plurality of service acceptability times is disclosed. Service requests from the subscribers are stored when they are received by the arrangement and served in a predetermined order. Also, a record is maintained of the number of subscribers served. The time that each service request is held in the store waiting for service is then computed and compared with the service acceptability time associated with the service request and a count is maintained of the total number of requests that are not served within their associated service acceptability times. When the number of service requests not served within their associated service acceptability time exceeds a predetermined relationship to the total number of subscribers served, the number of service requests stored in the system is reduced.

Abstract: A time-division switching system having a space-division network with a plurality of input terminals, each uniquely associated with a first buffer memory, and a plurality of output terminals, each uniquely associated with a second buffer memory, is disclosed. Time-shared communication paths through the space-division network are predominately completed such that digital data words representing signals from both parties to a conversation are transmitted through the space-division network during the same time slot. Normally, data words representing signals from telephone subscribers are assigned to first buffer memories in accordance with a fixed distribution plan. The system includes an arrangement which modifies the fixed distribution plan when it is determined that both parties to a conversation will have their data words stored in the same first buffer memory and switches data words representing signals from the called party of the conversation to an idle storage location in a different first buffer memory.

Abstract: Announcements for each subscriber are assembled specifically for that subscriber from speech segments stored in a digital memory. Each speech segment comprises a predetermined number of consecutive digital words stored in the digital memory and identified by a unique base address. A sequence of speech segment base addresses is placed in a first shift register which is rotated at a fixed rate. An incrementer increments the base addresses read from the shift register by an amount equal to the number of times that the entire base address sequence has been rotated, up to the number of digital words per speech segment. The incremented base addresses are used to access the digital memory. During the rotation of the first shift register, a second shift register is loaded with a second sequence of base addresses.