Patent GB-1057946-A (GB)
Title: A storage arrangement with associative interrogation
IPC: G06F17/30
Filed: 1963-10-23
Abstract: 1,057,946. Associative memories. TELEFUNKEN PATENTVERWERTUNGS G.m.b.H. Oct. 23, 1963 [Oct. 24, 1962], No. 41825/63. Heading G4C. An associative memory arrangement includes a mask register for limiting the comparison of a search word with the words stored in the memory, a detector element for each memory word for indicating a successful comparison, and a threshold device connected between each stored word and its associated detector element, each threshold device being operated when not more than m differing binary places exist between the search word and the stored word associated with the threshold device. Matrix store.-Words stored in columns of a matrix array of bi-stable elements 1, 2, 3 &c. are compared with a search word in a register SR with which is associated a mask register MR. For each binary comparison order, a gating arrangement 10-14 is provided to energize an output 15 only when corresponding stages 2, 5 of the storage column and search register SR are different and the corresponding stage 8 of the mask register MR is on. The outputs 15 for each column are connected to an associated threshold device 16 which may comprise a magnetic core (Fig. 2, not shown), having a plurality of inputs, a variable potential bias winding and an output connected to a bi-stable detector element 17. Alternatively the threshold device may comprise a transistor or tunnel diode. In operation, the detector elements 17 &c. are initially switched on and those stages in the mask register are reset where no comparison is required. When the comparison takes place, all those detector elements 17 are reset where the corresponding threshold device 16 has a greater number of energized inputs than the set threshold permits, these detector elements corresponding to words which are too different from the search word. The other stored words can then be read out if desired. The threshold value of the devices 16 can then be lowered and a fresh comparison made, this process being continued if desired, until the closest approximation to the search word is found. In a modification (Fig. 4, not shown), there is provided an additional masking register and associated gating circuits connected directly to reset the detector elements (17) when a single differing binary place is found, those stages of the additional mask register being set for which equality between the search bit and stored bit is essential. Drum store.-Data words read from a drum store (31, Fig. 5, not shown) are compared in a comparator (32) with a search word in a register (SR) in so far as the stages of the register (SR) are not masked by a mask register (MR) and for each binary place in which no coincidence is found, a counter (41) is stepped. A threshold device in the form of a comparator (44) compares the contents (k1) of the counter (41) with the contents (k2) of a register (42) which is reset after each drum revolution, and (whenever k1 < K2) causes a detector element (35) to gate the contents of the counter (41) into the register (42) and the contents of the drum buffer register (PR) into a register (SPR). Thus at the end of one drum revolution, the register (SPR) contains the drum word which most closely resembles the search word, the number of discrepancies being indicated in the register (42). In another embodiment employing a drum store (Fig. 3, not shown), a threshold device as in Fig. 1 is employed instead of the counter (41).