Data switching exchanges

Claim 1

A data switching exchange serving on a two-way transmission basis a plurality of digital subscribers'' stations, said stations being segregated into a plurality of data rate categories according to their individual operational data-rates and said exchange comprises in combination: a plurality of incoming and outgoing time division multiplex transmission highways arranged in pairs, each pair accommodating incoming and outgoing multiplexes respectively handling information in respect of the same plurality of subscribers'' stations on a character interleaved basis in the same synchronous multiplex time-slot appearance order there being at least one pair of highways for each data-rate category and each individual highway handles information in respect of one data-rate category only, a plurality of time switching cords arranged in groups, there being one group of cords dedicated to each data-rate category and each cord has an input path and an outpt path and includes a plurality of cord locations, each cord location when in use provides temporary storage for message data characters in transit and semi-permanent information stored for the duration of each call handled by the cord location, a message packet store containing a plurality of packet areas for the storage of assembled message packets, a plurality of packet-assembly buffers served by packet-assembly highways and connected to said message packet store, there being at least one packet-assembly highway for each data-rate category and each packet-assembly buffer is served exclusively or on a time division multiplex basis by one packet-assembly highway and said packet-assembly buffer includes means for accepting and temporarily storing data characters forthcoming over the related packet-assembly highway preparatory to communication to a predetermined packet area of said message packet store for the assembly therein of a message packet, a plurality of packet-dissembly buffers served by packetdissembly highways and connected to said message packet store there being at least one packet-dissembly highway for each data-rate category and each packet-dissembly buffer is served exclusively or on a time-division multiplex basis by one packet-dissembly highway and said packet-dissembly buffer includes means for transmitting each data character of an assembled message packet over the related packet-dissembly highway, a switching network segregated into sections there being one section for each data-rate category and each section comprises i. a first crosspoint array making selective connection to the input paths of any of the groups of cords dedicated to said particular category and ii. a second crosspoint array making selective connection to the output paths of any of said group of cords; said first crosspoint array includes a first rank of crosspoint switches, providing selective connection between each incoming highway serving subscribers'' stations of the particular category and said input paths, and a second rank of crosspoint switches, providing selective connection between each packet dissembly highway of said particular category and said input paths whereas said second crosspoint array includes a third rank of crosspoint switches providing selective connection between each outgoing highway of said particular category and said output paths and a fourth rank of crosspoint switches providing selective connection between each packet assembly highway of said particular category and said output paths and common control means operable to condition said semi-permanent information of a cord location with information indicative of a. the identities of the crosspoints in said first and third ranks serving the highways upon which two stations to be connected appear, b. the identities of the crosspoints in said first and fourth ranks serving the highways upon which a station and a packetassembly buffer to be connected appear or c. the identities of the crosspoints in said second and third ranks serving the highways upon which a packet-dissembly buffer and a station to be connected appear.