Patent GB-890008-A (GB)
Title: Intelligence storage apparatus
Inventor: WRIGHT ESMOND PHILIP GOODWIN
IPC: H04L13/08
Filed: 1960-12-02
Abstract: 890,008. Digital-data-storage. STANDARD TELEPHONES & CABLES Ltd. Dec. 2, 1960, No. 41592/60. Class 106 (1). [Also in Group XL (b)] An intelligence storage apparatus for use in connection with intelligence transmission systems wherein the transmission channel may become temporarily unsuitable for transmission comprises a primary intelligence store which has a maximum capacity of n characters and a minimum capacity of one character, and includes a secondary intelligence store of minimum capacity of n characters and any suitable maximum capacity, the primary and secondary intelligence stores being so arranged that incoming intelligence characters are admitted to both stores simultaneously, the primary store delivering up its stored characters immediately if transmission conditions are suitable, the secondary store retaining under these conditions the minimum of n characters, the characters being stored sequentially, each character in the secondary store being discarded when the corresponding character is transmitted by the primary store, switching means being provided to transfer the delivering up of characters from the primary store to the delivering up of the characters from the secondary store should the former become full to the point where it holds n characters and is about to receive the (n+1)th character, further switching means being provided to prevent the delivering up of stored characters from the secondary store if transmission is further delayed and at the same time to allow the capacity of the secondary store to increase with the continued inflow of incoming characters, transmission of the stored characters reverting to the primary store when the accumulated characters in the secondary store have been reduced to the minimum. General arrangement.-Incoming 5-unit code signals pass via unit 2 to a character timescale unit 5, to the primary store 3, which may be a ferrite matrix, and to the secondary store 4, which is here shown as a tape store. On the reception of each character, unit 5 delivers a start pulse to the primary store and to a clutch 8 which advances the tape of the secondary store 6 past a writing head 6. The start pulse also passes to a clutch 9 which advances the tape past the reading head 7. When the portion of the tape between the heads is tight n characters can be stored thereon. Characters are erased after passing the reading head 7. Under good transmission conditions signals stored in the primary store 3 are passed directly at 10 to the transmitter, read-out command signals at 11 from the transmitter occurring after the successful transmission of each character. Under poor transmission conditions it may happen that signals are passed to the primary store more frequently than they are read out. If, in this instance, the primary store 3 becomes full, i.e. has n characters stored therein switches 15, 16 are reversed and switch 13 is opened. Incoming signals are stored as before in both the stores, the oldest character in store 3 being erased as each new character arrives. Reading of the signals in the secondary store 4 now occurs only when clutch 9 receives a command from the transmitter so that the tape between the heads becomes slack and has more than n characters stored thereon. When conditions again become favourable read-out occurs from store 4 and, read-out and transmission being more rapid than read-in, the tape between the heads eventually becomes tight again whereupon switches 13, 15, 16 revert to their original positions and read-out takes place once again from the primary store. Circuitry is provided for sensing the conditions of the tape and of the stores, and it is arranged that the change of read-out from store 3 to store 4 does not occur during read-out of a character, as detailed hereunder. Where the primary store is required to process the signals prior to transmission, the output of the secondary store is fed to the primary store instead of direct to the transmitter. Store switching arrangements.-A bi-stable circuit 19 associated with the primary store 3 gives an output signal, when that store is full, which operates a relay 12 to open switch 13. The signal also passes to a coincidence gate 22, this gate having further inputs of the incoming character start pulse from 5 and a signal from unit 23 indicating that no character is being read out of either store. When the gate 22 gives an output this signal passes via a bistable circuit 24 to a relay 14 which reverses the switches 15, 16 and therefore changes readout from one store to the other. This condition is maintained until circuit 24 changes to its other state. This change occurs when a " tape tight " switch 18 is operated and no character is being read out, a coincidence gate 25 being provided to detect these two conditions.