Patent GB-1176689-A (GB)
Title: Message Retrieval Systems.
Inventor: BRANDSTADTER JAY ROBERT
IPC: H04L12/58
Filed: 1967-02-21
Abstract: 1,176,689. Data retrieval system. WESTERN ELECTRIC CO. Inc. 21 Feb., 1967 [21 Feb., 1966], No. 8176/67. Heading G4C. A message retrieval system comprises first storage means for sequentially storing message signals associated with any of a plurality of message stations, and means responsive to each message to enter on a second storage means, in a portion thereof set aside for the message station associated with that message, an indication of the location of the message in the first storage means. Message storage.-Data is sent from a plurality of stations 10 1 -10 6  to a common control unit which sends the data to be stored to a selected one of the on-line tape units 40. Consecutive data is recorded on one tape unit, e.g. M until the tape is full whereon the data is forwarded by the control unit to the next tape unit, e.g. N. Each time data is stored on a tape record information is recorded in a cross reference memory 50 which comprises a pool of common file blocks, and a pair of blocks, (an accumulating block and a summary block) for each station 10 1 -10 6 . Each data word from a station causes the control unit to send the identity of that station to an address translator and after the process of each message is completed causes a counter 58 associated with that station to be advanced by 1. The address translator produces an address corresponding to the beginning of the accumulating storage block associated with the said station and applies this to an adder where the number from the counter is added thereto (00000 indicating the first word, 00001 the second . . . 11111 the thirty-second). This sum is applied to a memory accessor 64 which enables the appropriate location to store therein a tape reel designation, e.g. M and the record number of the particular record stored thereon e.g. the 5th word from station 10 1  may be the 101st word on the tape so M and 101 are stored in the 5th location of the accumulating block associated with station 10 1 . The embodiment described uses memory blocks 32 words in length so each counter 58 is followed by a modulo 32 inverter and when a counter reads 32 or 11111 a storage shifting circuit 72 is enabled to transfer the contents of the accumulating block associated with that counter to an empty file block, e.g. 7. The time and date of the last message received is stored in the first vacant location of the summary block associated with that station and the following location receives the address of the first location of the file block now holding the appropriate data. This process continues for all stations. Message retrieval.-When a station wishes to obtain a message sent previously information defining the date and time of the message is sent to the control unit. This causes the information to be compared with the times and dates stored in the appropriate summary block. When the first location that has a time and date later than or equal to the said information is found the address in the following location is added to the sum modulo 32 of the message number to define the location holding the address of the required data on tape. If a plurality of records are to be read the tape addresses are supplied to a queuing memory. The Queuing Memory includes a pair of adjacent cells QUEUE START and QUEUE STOP for each tape reel the remainder of the memory comprising a pool of common linking couplets. When a tape address is read from memory 50 it is passed to a translator and a retrieval request queuing circuit. The tape reel identity is converted to a QUEUE START address associated with that particular reel. The first retrieval request for a particular tape, e.g. M causes the tape reel designation M, the reel record number and the identity of the station 10 requesting retrieval to be written in a memory couplet from the common pool, the address of the first cell of the couplet to be written in the appropriate QUEUE START location and the address of appropriate QUEUE END location to be written in the second cell of the couplet. When succeeding requests are received the tape address is entered in the first cell of a new couplet and the previous entries are examined. When a reel record number is found that is greater than that of the number to be entered the address of the first cell of the found pair is entered in the second cell of the new couplet. If the new number is greater than the previous numbers, the couplet containing the highest previous cell receives the address of the first cell of the new pair and the second cell of the new pair receives the address of the QUEUE END cell. On tape read out the appropriate locations can be read in consecutive order and supplied to the appropriate stations.