Patent GB-1059672-A (GB)
Title: Improvements in or relating to telecommunication systems
IPC: H04Q3/54
Filed: 1963-08-13
Abstract: 1,059,672. Automatic exchange systems. SIEMENS & HALSKE A.G. Aug. 13, 1963 [Aug. 13, 1962], No. 31943/63. Heading H4K. A telecommunication exchange comprises an information store containing information relating to subscribers' lines, and a control system containing a further store (referred to as the " intermediate store "). This latter store comprises multi-bit cells one of which is taken into use only for the duration of a control operation, in which cell is written the address of a cell in the information store containing the relevant subscriber information. The cells of the intermediate store are scanned cyclically to cause read-out of the addresses of the cells in the relevant information store, these addresses causing the information stored therein to be read out and fed back for storage in the intermediate store, where it is then used to instigate appropriate control operations. The stores are preferably magnetic core stores. Fig. 4 illustrates an arrangement for collecting dial pulses and feeding them to a selection control circuit 4E. When a dial pulse is due for collection as indicated by its presence in a section of store 4I, the address of the section is fed from the address generator 4AI to one of the sections 4BF. When scanner 4AW encounters a section 4BW of intermediate store 4W having no address in its left-hand portions, this scanner is stopped and scanner 4AF started. The first address encountered in 4BF is then inserted into the empty section of 4BW. Priority may be given to certain information stored in 4BF in a manner similar to that described with reference to store 4H below. During subsequent scanning by 4AW the address so stored is used to interrogate 4BI for a stored dialled pulse which is fed to adder 4D. The middle portions of 4BW stores the existing dial count and feeds it out each time to the adding circuit, the up-dated dial count being then reinserted in the store. At the end of the dial train 4TW by means not shown enables gates 4K1 . . . 4K6 to pass the digit to the first free section of store 4H, and also enables a converter 4U which inter alia tests to see that the digit is plausible (if not an alarm signal is emitted from 4g 1 ) and also determines any priority ratings for the digit, appropriate priority signals being emitted from 4g 2 , 4g 3  and also stored in 4H. When the selection control circuit 4E is ready it starts 4AH scanning and if a priority digit is found gate 4G stops the scanning and the digit is read out to 4E. If no priority digit is found a second scan is made for ordinary digits which are then transferred to 4E. The above description is of a simplified version in order to illustrate the principles involved. In practice further equipment capable of timing the dial pulses is substituted for the store 4I. Such equipment is described with reference to Fig. 5 (not shown) and is identical with equipment described in Specification 1,059,671. Fig. 8 illustrates an arrangement for giving busy flash to an incoming inter-exchange line. During the attempt to set up a call relevant information received from apparatus whose address is stored in portions a . . . f, is stored in portions g . . . l. When the section concerned is scanned the circuit 8J receives this information and inserts the address of the line circuit in portions u . . . x, and a signal into m indicative of the nature of the signal to be sent to the linein this case busy flash. When the appropriate section of 8W is sampled by generator 8AW, the address read out of u . . . x selects the appropriate line circuit 8BA and passes a pulse from m to the read-in circuit 8ZA. Sections n . . . s carry an accumulated total of pulses which total is fed to adder 8L which also receives the pulse from m, the up-dated total being reinserted in n . . . s. The pulses delivered to 8BA are integrated therein to provide the flash period. After a prescribed number of scannings the read-out total opens gate 8K1 to insert a 1 in portion t. On subsequent read-out the signal from t inhibits 8G to prevent further pulses being applied to 8ZA. This starts the pause between the flashes. When the count reaches a further prescribed value gate 8K2 opens resets 8L (and consequently n . . . s) and also zeroizes portion t. The flash period then recommences and so on.