Patent GB-1126046-A (GB)
Title: Improvements in or relating to associative memory devices
IPC: G11C15/02
Filed: 1965-10-05
Abstract: 1,126,046. Associative stores. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 5 Oct., 1965 [8 Oct., 1964], No. 42190/65. Heading G4C. [Also in Division H3] In an associative memory comprising a plurality of magnetic elements arranged in rows and columns, each element having four parallel magnetic paths, information to be stored in an element by the direction of magnetization in one of the paths is written into the element by simultaneously applying a current to the column and row conductors which are coupled to a second magnetic path of the elements of the same column and to the third and fourth magnetic paths of the same row respectively. In the arrangement of Fig. 3, information is permanently stored in the line A of each magnetic element M, Fig. 1 (not shown), the magnetization being upwards to store a binary " 1 " and downwards to store a binary " 0 ". Each column wire, Y 1 , Y 2  or Y 3 , is coupled to limb B which in this embodiment forms the second magnetic path and the row or word wires X 1  or X 2  are coupled to the limbs C and D which form the third and fourth paths. If word 101 is to be written into the first row, M 11 , M 12 , M 13  conductor X 1  is energized so that the C legs are magnetized upwards and the D legs downwards and simultaneously positive currents are applied to conductors Y 1 , Y 3  and a negative current to conductor Y 2  such that the B legs of elements M 11 , M 13  are magnetized downwards and that of the element M 12  is magnetized upwards. Since the legs B, C, D are forced into a given magnetization state the A leg assumes a magnetization opposite to that of leg B. In order to reset elements in the other words to the normal condition conductors X 1  and X 2  are energized for a short period of time after the currents in the column conductors have been terminated. If an element is storing a binary " 1 ", a positive enquiry current on the Y conductor followed by a resetting pulse on conductor X has no effect on the flux patterns, Fig. 2 (not shown). However a negative enquiry current applied to the conductor results in a flux reversal in limbs B, C inducing a voltage in sense conductor S coupled in opposite sense to the X conductor to limbs C, D. A subsequent resetting pulse returns the flux pattern to the original condition. When the element is in the " 0 " condition legs B, D reverse their magnetizations when a positive pulse is applied to the Y conductor inducing a voltage in winding S of the same polarity as if a " 1 " had been stored. When a negative pulse is applied to the Y conductor no flux variations occur. Thus no output pulse appears during the associative enquiry at the sense conductor of those words of which the address word associates with the key word. In the arrangement of Figs. 4, 5 (not shown), the column conductors are coupled to the C legs while the row and sense conductors are coupled to the B and D legs respectively. The C-leg of Fig. 4 may be coupled to two column conductors instead of one, Fig. 6 (not shown), which conductors in addition are coupled to the legs B and D respectively in opposite senses. For writing a " 1 " one of these column conductors is energized whereas to write a " 0 " the other is.