Patent GB-1279909-A (GB)
Title: Automatic telecommunication switching system
IPC: H04Q3/00
Filed: 1970-12-17
Abstract: 1279909 Automatic exchange systems INTERNATIONAL STANDARD ELECTRIC CORP 17 Dec 1970 [31 Dec 1969] 59925/70 Heading H4K A register connector comprises a number of switch groups of equal rank each switch having its own control circuit and comprising crosspoint elements operated by selection of one from each of two sets of control elements, each group of switches having a first common control seizable on demand by any one of the group's switch control circuits to select a control element from a first one of the sets for actuation from amongst those elements associated with a demand, the connector having a second common control circuit seizable on demand from one of the first common control circuits in order to select a control element from the second one of the sets in that switch the demand from which is being satisfied by the first common control. The switches are cross-bar switches CS1 to CS6 in each group P1 to P8. The sets of control elements associated with each switch are the horizontal select magnets and the vertical operate magnets. Each switch terminates a group of 22 incoming junction circuits IJ on respective horizontal conductors multipled over the 7 switch verticals. The remaining 6 horizontal select bars control access to individual crosspoint connections to a group of 42 registers RE, the group of registers being similarly connected in each switch of the group so that each register is accessible over corresponding verticals, and cross-points in those verticals, in each switch of the group. Each group of 6 registers accessible over a vertical is also accessible over one other vertical of a switch in another group. Thus register group RE1 to RE6 in group P1 is also accessible over a vertical in group P2, while group RE37 to RE42 in P1 is also accessible in P5. Tables are given for the distribution of the total of 168 registers over the groups P1 to P8. Each switch C5 has an associated control circuit LAC and each switch group has control circuits, such as M11 and M12 for group P1, either of which can be seized for a connection and both of which can work concurrently in establishing connections. The whole array of switch groups is served by a pair of common control circuits CM 1 , CM 2  either of which can be seized by a group control circuit M and both of which can function concurrently. A demand for a register signalled from an incoming junction IJ is registered in the associated switch control circuit LAC if there is a free vertical giving access to a free register. The registration of one or more such demands for connection in a switch group P signals the group control circuits M one of which, or each of which, responds to select and connect to one of the demanding switch control circuits LAC. Having connected to an LAC, the control circuit selects one of a number of junctions incoming to the associated CS switch and possibly competing for connection. Since two demands for connection can be handled concurrently in each switch group P, a total of 16 concurrent connecting operations can be handled by the whole connector. Selection of a junctor implies operation of its associated horizontal select magnet and is accompanied by a demand from the group control M for service from a common control CM. The common control circuits CM select one each from the existing demands from the M control circuits and connect themselves accordingly. The service provided by the common control circuits M comprises the selection of a free switch vertical having access to a group of registers having at least one register free, and further comprises the selection of a free register in that group. The common circuit CM sends the identities of its selections to the group control M which relays the information to the switch control LAC for the operation of the corresponding horizontal select magnet, to give access to the selected register, and to operate the vertical operate magnet with which the register is associated. Selection of a demanding control circuit M, selection of a vertical, and selection of a horizontal, are effected in circuits MSM, VSM, and HSM, respectively in each common control CM. Relay circuits for such selections are detailed in Figs. 2 to 6 (not shown). A selection circuit LASM, as used in the group control circuits to select a calling one of the switches, is of the kind described in Specification 1,279,910.