Telecommunication exchange apparatus

1,015,646. Automatic exchange systems. ERICSSON TELEPHONES Ltd. Oct. 9, 1964 [Aug. 30, 1963], No. 34370/63. Heading H4K. Highways providing 30 channels each serve corresponding groups of subscribers such as those having direct access to exchange lines and those on party lines, metering being effected by a cycle of 56 group pulses and a cycle of 13 vernier pulses each group pulse and vernier pulse being equal in duration to a cycle of channel pulses on a highway, the group pulses providing selective access to meter total stores provided for each class of subscriber and the vernier pulses controlling the manipulation of the metering totals for the addition of charges. Separate stores are provided for direct exchange line subscribers, for X party subscribers and for Y party subscribers. An everflow store is also provided to expand the capacity of direct exchange line subscriber stores should a classof-service mark be associated for this purpose. Each store comprises 30 eight-bit storage units each unit being accessed in the time slot of the subscriber it serves. As shown in Fig. 1, a store MS can have a storage unit read out in parallel over amplifiers SA to a parallel adder PA which increases the count by one and passes it to a temporary store TS. Two adders PA are provided to deal with the counts in odd and even channel pulse periods alternately, a delay D of one channel period precedes each adder. The temporary store TS comprises ten one-bit storage units TS1 to TS10, TS1 to TS8 holding the count pending its restoration in the meter store MS and TS9 and TS10 being used for supervision. If an eight-bit storage unit is stepped to a maximum count then further addition is barred unless a subscriber's class of service mark indicates the provision of overflow counting. A bit injected in unit TS10 of temporary store TS during a clearing down operation in vernier pulse V9 is read out in vernier pulse V10 in the time slot of the subscriber to be charged and during a group pulse associated with the subscriber's group as indicated from a supervisory unit governing metering. Read out of TS10 in V10 reads out the subscriber's meter total to the adder and places the new total in TS1 to TS8. In the next occurring V10 pulse the total is restored to MS. Since reading and writing in the meter stores occurs in consecutive vernier pulses V10, reading will be in a given group pulse and writing will be in a given different group pulse thirteen pulses ahead in the cycle. Should