Patent GB-990822-A (GB)
Title: Improvements in or relating to data processing equipment
IPC: H03K17/64
Filed: 1961-08-04
Abstract: 990,822. Automatic exchange systems. STANDARD TELEPHONES & CABLES Ltd. Aug. 4, 1961 [Aug. 9, 1960], No. 28472/61. Addition to 942,183. Heading H4K. In a data handling system comprising a read-only programme memory PM, Fig. 1, which emits a partial address and an instruction, staticized in PAP and ORP respectively, the staticizing time is divided into a number of elementary intervals t 1  ... t 10 , the first of which is used for addressing the memory PM and at least some of the remainder are used for performing logical operations in accordance with the instruction. The invention is described in relation to an automatic exchange system comprising a register memory REGM having several compartments for storing details of calls in the process of being set up or released and a " supervisory " not shown which contains inter alia details of all calls in progress, the systems being similar to those described in Specifications 904,232, 904,233, 977,420 and 990,821 in which connections are set up on a time division multiplex basis. The register REGM reads out and writes in information segmentially and cyclically to and from staticizing devices PAR, CAR, INR the staticizing period being 120 Á sec. divided into twelve periods t 0 , t 1  ... t 10 , t 11 , the first and last being used for communication of data between REGM and its staticizing devices. Staticizer PAR receives partial addresses for PM, CAR, receives complementaty addresses for PM and INR receives identities of elements involved in the connection existing at this time, i.e. identitities of calling subscriber, called subscriber, dial tone sources &c. When the register REGM is called into action it receives the appropriate identities and addresses indicative of the state of the call at that time. At t 0  these are read out into PAR, CAR, INR. At t 1  the addresses in PAR, CAR are used to address PM to receive a partial address staticized in PAP and an instruction staticized in ORP. The latter performs tests and effects controls through the logic circuit REG during t 2  ... t 8  as a result of which a new partial address is inserted in CAR at (or before) t 9 . At t 10  the partial address PAP is inserted in PAR and ORP, PAP are erased. At t 11  the identities &c. now present in PAR, CAR, INR are re-inserted into REGM. The succeeding compartments of REGM are then treated in a similar manner, until the compartment in question again comes round when operations relative to the pertaining connections are resumed with the new addresses derived from the previous operations. Initial calling condition: class of service determination.-When a line is scanned and found to be off hook the equipment identity of the line and partial address OI is received at t 0  from REGM and inserted into INR and PAR. Address OI is sufficient to read out from permanent memory PM the partial address 81 and the instruction A which are inserted in PAP and ORP respectively. This instruction causes the examination of a bi-stable device associated with the line. If the bi-stable device shows the line to be marked busy this causes the complementary address C 2  to be inserted in CAR, but otherwise, i.e. if the line is newly off-hook, the instruction A causes the line to be marked busy and address C 1  to be inserted in CAR. On the next time round the details of this connection are read out from REGM to PAR, CAR, INR and if the address is 81C 2  row 21 of PM is addressed to cause instruction S and partial address OO to be read out. This zeroizes all the storage devices in CAR, INR and causes OO to be returned via PAR to REGM to signify that this compartment is free to deal with another call. If, however, the address is 81C 1  then this causes the next read out to provide the partial address 82 and instruction B. This causes reference to be made to a further semi-permanent memory COL, Fig. 4, which stores inter alia the class of service in addresses determined by store CGR which at this time stores the equipment number of the calling line. If the class of service is "outgoing calls barred " an output is applied to SC which at time t 9  writes the complementary address C 4  into CAR. If the call is a normal one an output is applied to NC which causes complementary address C 1  to be written into CAR. The circuit has a built-in safeguard against failure of COL to provide any output. Thus at t 3  the complementary address is changed to C 0  which inhibits at G 13  any change in the PAR address, and allows a further attempt at the next staticizing period. A time-out device may be provided for giving an alarm if this condition persists. The next time round instruction 82C 4  gives rise to partial address O 2  and instruction K which is used to initiate return of busy tone. On the other hand 82C 1  gives rise to partial address 83 and instruction C. Sending of dial tone, Fig. 3. A plurality of dial tone sources are provided and a free source must be allocated to the calling subscriber and free multiplex channels allocated to connect this source to the subscriber. Staticizer INR contains elements capable of coding the identity of each source. At time t 2 , instruction C causes INR to staticize the identity of the first source and to emit a signal on a corresponding lead to G 8  and G 9 . At t 3  the complementary address is changed to C 3 . If the first source is free an associated bistable circuit BS 1  is in its " 0 position and, at t 9 , G8 changes BS 1  to its " 1 " or busy position and writes C 2  into CAR. At t 10  partial address 83 is written into PAR. If the source had been busy G 9  steps INR to register the identity of the second source and C 3  is retained in CAR. The next time round the address 83C 3  causes the permanent memory PM to emit the same signals, viz. 83, C and the second source is similarly tested and so on. When a free source is found C2 is written into CAR so that next time address 83C 3  is used which results in 84, D being emitted from PM. This initiates the hunting for a free channel for connecting the calling subscriber with a busy tone source. If all the sources are busy, gate G<SP>1</SP>9 corresponding to the last source causes C, to be inserted in CAR. Address 83 C 4  causes PM to emit 02, K which initiates reversion of busy tone. Next time round the partial address (which in this case serves as a complete address) causes PM to emit instruction J and no partial address. Instruction J causes the register to transfer its data to the supervisory equipment. In the case of 84D the complementary address C 1  may be obtained (by means not shown when suitable pulse channels have been selected) which provides partial address 85 and instruction E to initiate the sending of the dialling tone by transferring the necessary data to slave equipments associated with the multiplex highways &c. When the dial tone is to be cut-off on receipt of the first dial pulse 84 is written into PAR and complementary address C 4  is written into CAR, Fig. 2. This causes 04 and U to be read out of PM. Instruction U in conjunction with the dial tone unit identity stored in INR causes restoration of the bi-stable circuit BSX associated therewith to release the unit. Translation of directory number into equipment number and vice versa.-Mention is also made of the fact that the read-only store COL, Fig. 4, may be used to contain translations of directory numbers into equipment numbers and vice versa for calling and called lines and also to indicate class of service of called lines (e.g. PBX). In the case of calling lines translation of equipment numbers into directory numbers may be utilized for automatic accounting apparatus, the latter obtaining access thereto during elementary time intervals different from those used above to obtain class of service indications. The arrangement may also be used for performing other functions, with suitable interchanging of information between the supervisory and the register, such as choosing suitable channels for setting up a call, or reverting busy tone when the wanted subscriber is busy or when suitable channels are not available. The memory PM may be of the capacitative type described in Specification 918,603.