Patent GB-1133143-A (GB)
Title: Improvements in or relating to supervisory arrangements for information transfer
IPC: H04Q3/545
Filed: 1966-03-08
Abstract: 1,133,143. Computer control of telephone systems. TELEFONAKTIEBOLAGET L. M. ERICSSON. 8 March, 1966 [8 March, 1965], No. 10227/66. Heading G4A. [Also in Division H4] In a system having a number of equipments which may be addressed individually by a pair of synchronously operating computers, the equipments are located at the crosspoints of an address matrix, any row of which can be selected by appropriate operation of a crosspoint of a selection matrix. Address data coming from the computers is translated before being applied to the rows and columns of the selection matrix (or matrices). The address matrix is provided with a special column conductor which produces an error signal in the event of a fault occurring during an addressing period whereby a fault detection process is initiated. The process consists in addressing a particular test row of the address matrix whereby if the error signal ceases this indicates that the address matrix is not at fault. Then, utilizing the original address as an input, the translators are disconnected in turn until the error signal again ceases and thereby indicates the faulty translator. The faulty equipment is cut-out of service until it is repaired or replaced. The system is described with reference to a telephone system in which the equipments are line circuits or selector switches whose states (i.e. busy or free) need to be assessed or controlled by a computerized central control system. Computers, D1, D2.-Details of these are not given. They are linked to the peripheral equipments via two bus systems, one of which carries 16 bit address words for selecting a particular equipment and the other of which carries 16 bit data words. Each bit position of the latter words is individual to an equipment and the bit may indicate to the computer the state of the equipment or may represent a command from the computer to the equipment. Fault detection circuitry, including a comparator, are provided for ensuring synchronous operation of the computers. Translators, OV1, OV2.-Each computer has an individual translator which translates 16 bit input words into one, 1 out of 8 code and five, 1 out of 4 codes. Selection matrices UM.-Each of these comprises an 11 x 8 transistor array of which the columns are selected by the 1 out of 8 code emanating from a translator and the rows are selected by some of the 1 out of 4 codes. In order that a crosspoint such as UP1 (Fig. 5) may be operated, its corresponding row AND gate OK1c (Fig. 4) must receive identical and coincident signals from the translators via respective AND gates OK1a and OK1b assuming, as is normally the case, that relays BRr1 and BRr2 are both up. Address matrices AP.-Each of these comprises an 81 x 16 capacitor array, of which a crosspoint only delivers an output pulse, when interrogated, if its associated equipment is busy. Capacitor Cb1 (Fig. 5) is of much larger value than Ca1 and together with resistor R3 in the associated line circuit forms an integrating circuit for rapidly recharging Ca1 after each interrogation. Decoupling diodes G1 are provided. An additional column kk (Fig. 6, not shown) is provided for fault detection purposes. Operation.-During a normal interrogation at least column kk of the required address matrix produces an output. If this does not occur, logic circuitry (Fig. 7, not shown) causes the stored address of that crosspoint which corresponds to row 81 of the address matrix, to be applied to the selection matrix. Provided that kk now supplies an output pulse it is assumed that the address matrix is operating correctly. The logic now opens gate AC1 (left-hand side of Fig. 4) whereby relay B1 falls, followed by BRr1 and BRk1. The original address is supplied entirely by translator OV2 to the selection matrix, since the relays have disconnected OV1. If column kk still produces no output pulse, the logic releases relay B1 (centre right-hand side of Fig. 4) whereby relays BRr2 and BRk2 fall back so as to allow the address to be supplied only from translator OV1. If there is still no output from kk, it is concluded that the selection matrix is faulty. If at any time an output does occur during the substitution testing it is assumed that the currently disconnected equipment is at fault.