Patent GB-899292-A (GB)
Title: Improvements in or relating to register devices of the magnetic drum type
Inventor: CLARK THOMAS HAROLD
IPC: H04Q3/42
Filed: 1958-11-05
Abstract: 899,292. Automatic exchange systems. BRITISH TELECOMMUNICATIONS RESEARCH Ltd. Nov. 5, 1959 [Nov. 5, 1958], No. 35557/58. Class 40 (4). Subscribers' lines are scanned sequentially to connect them to individually corresponding minor storage sections on a magnetic drum, a calling line causing seizure of a major storage section on the drum into which the calling line address is written from the line's minor storage section, whereby the scanner is marked to connect the calling line to the major storage section at the appropriate time. In order that the connection of a calling line with a major storage section may be carried out by the same equipment that effects scanning of the lines, each scanning action is preceded by a period in which the scanner may be put to use as a connector under the control of non-cyclic pulses which repeatedly connect the calling line to the same major storage section. The scanning equipment is therefore controlled by two interleaved sets of pulses, one set being cyclic to scan the lines by connecting them sequentially to their minor storage sections, the other set being produced according to the identity of the calling line recorded in the major storage section and at a time determined by the position on the drum of the major storage section. The process of connecting with the second set of pulses is referred to in the Specification as back-masking. In a 1000-line exchange minor storage section records the condition of its line, the class of service to which it is entitled, and its accumulated meter fees. Each major storage section can record ten digits and provides translation facilities. Minor stores are accommodated on 10 tracks of 100 stores each, the 100 lines of each track being connected to their associated minor stores in sequence by a scanner particular to that track, all 10 tracks being scanned simultaneously and in step with one another. As shown in Fig. 1, a scanner for the 100 lines of one minor store track comprises ten tens' transistor gates such as TR1, each connecting groups of ten lines, such as L1 to L10, to a common highway to the associated minor store track. Units' pulses U1 to U10 sequentially connect the lines of each group to their respective tens' gate. For the purpose [of connecting lines to the major storage sections each of the ten common highways to the minor store tracks is connected to a hundreds' transistor gate such as TR2 controlled by hundreds' pulses H1 to H10 giving access to the single highway S7 to the major stores which are accommodated in 5 tracks of 10 stores each. Each minor storage section embraces the 20 time slots marked by pulses TA1 to TA20 and is synchronous with one of the pulses TB1 to TB10 embracing 10 such sections. Each major storage section extends over and is synchronous with a pulse sequence TB1 to TB10 and is co-terminus with one of the pulses TC1 to TC10. The units' and tens' pulses are derived from the TB and TC pulses, shown in Fig. 3, as applied to the gates shown in Fig. 2. In order to interleave the scanning function required for the minor stores with the connecting function required for the major stores, a waveform CO, see top of Fig. 2, is employed together with its complement CO. By gating the pulses TB1 to TB10 with the waveform CO cyclic pulses U1 to U10 are produced during the time slots TA11 to TA20 of each TB pulse. Non-cyclic, or back-marking, units' pulses are produced during the time slots TA1 to TA10 by gating the waveform CO with one of the units marking pulses US1 to US10 set up on a staticizor by the address of a line taken from a major store. Similarly, cyclic tens' pulses T1 to T10 are produced by gating the pulses TC1 to TC10 while non-cyclic backmarking tens' pulses are produced by gating one of the tens marking pulses TS1 to TS10 set up on a staticizor by the major store, the role of the CO, and CO pulses being reversed in this instance as the TC and TS pulses are negative. The hundreds gates are of use only when the lines are to be connected to a major storage track so that the hundreds' pulses H1 to H10 are identical with the marks HS1 to HS10 extended from the hundreds section of the staticizor. When a calling line closes its loop, a mark is written in the line's minor storage section which causes the address of the calling line to be read from the minor store on to a staticizor common to the whole exchange and initiates a search for a free major storage section. When seized, the first idle major storage section has the calling line's address written into it and the common staticizor is released. The major store then periodically writes the calling line's address into a staticizor, as referred to above, of which one is provided for each major store track, these staticizors producing the non- sequential back-marking pulses US1 to US10, TS1 to TS10, and HS1 to HS10. Since there are 5 major store tracks and at any one time 5 major storage sections may want connection to lines over the scanning equipment it is necessary to stagger these connections over 5 separate intervals during the transit of a major storage section. This is done by the use of a so-called allotter track shown at the bottom of Fig. 4 where it is shown related to the 5 major storage tracks above. Each major storage track contains ten sections, the first and second section of each track being shown in full. Each section is divided into 10 equal intervals by the pulses TB1 to TB10. The allotter track is divided up into compartments spanning two TB pulses so that a section coincident with a major storage section comprises 5 compartments each of which is associated with a storage track, In period TB1, for instance, the number of the calling line associated with the first major store track is read into the allotter track to provide a backmarking connection in period TB2. In periods TB3, TB4, the second track is similarly served by the allotter track; the third, fourth, and fifth tracks having connections in periods TB5, TB6, and TB7, TB8, and TB9, TB10, respectively. Since all that has to be detected is the line condition, five toggles M1 to M5 (not shown) suffice to record the inputs from the lines during the passage of any set of five major storage sections, M1 being connected by the backmarking pulses at TB2, M2 at TB4, M3 at TB6, M4 at TB8, and M5 at TB10. The states of all the toggles are examined and read on to the major stores in parallel at the end of the major store sections during the time slots TA11 to TA20. Examples of non-sequential backmarking pulses are shown in Fig. 3 where the staticizor is set up by the first major store track to extend marks US4, TS2, HS2, in the period TA1 to TA10 of pulse TB2, during the passage of the first major storage section 1 which has been seized in the service of the line 224. Similarly, the second storage section on the first major store track has been seized to serve the line 931 and during its passage past the reading heads the allotter track sets up the staticizor to produce marks US1, TS3, HS9, in the period TA1 to TA10 of pulse TB2. These lines are repeatedly connected up to be sensed by the toggle M1 for as long as the major storage section demands.