Patent GB-839570-A (GB)
Title: Improvements in magnetic storage systems
IPC: G11C11/06
Filed: 1956-10-31
Abstract: 839,570. Circuits employing bi-stable magnetic elements. INTERNATIONAL BUSINESS MACHINES CORPORATION. Oct. 31, 1956 [Nov. 3, 1955], No. 33225/56. Class 40 (9). [Also in Group XIX] In a magnetic matrix core store having row and column windings means are provided for connecting a pulse generator to both the row and column winding corresponding to the selected core. A 4 x 4 matrix of cores 10, Fig. 2, has row windings X1 to X4 and column windings Y1 to Y4 connected through a bus 20. An output or sense winding S threads half the cores in one direction and the other half in the other direction. Bi-directional electronic switches 15-1 to 15-4, each comprising two oppositely-connected triodes, are provided, one for each Y winding, grid control lines 25-1 to 25-4 being connected for selective energization of the switches 15-1 to 15-4 by a decoding switch matrix 26. The X lines are pulsed from a current driver unit 28 which energizes a particular X line in accordance with signals directed over the selection lines 29-1 to 29-4 selectively energized by the decoding matrix switch 30. For reading from or writing in a particular core the current driver 28 is activated to pass a pulse of the appropriate polarity along the selected X line through the bus 20 along the Y line selected by energization of one of the switches 15 and to ground via the lead 16. The switches 15 are electronic but may alternatively be solid state switches comprising transistors, diodes or magnetic elements. In a modification, Fig. 4, the return line 16 is connected to the pulse driver source via ground through two paths firstly through resistor R1 and secondly through a resistor R2 and a winding W linking all the cores of the matrix in the same sense, the impedance of the two paths being substantially equal. A current driver unit provides two units of current to the selected line. Due to the presence of the winding W the selected core thus receives three units and every other core one unit only so that a three-to-one selection ratio is obtained. In another arrangement a three-toone selection ratio is obtained by utilizing a separate bias current source. A single current driver unit capable of producing pulses of one direction only may be employed for both reading and writing and this source may be utilized in an arrangement wherein all the core windings are in the same sense so as to facilitate construction of the arrays (Figs. 6, 7, not shown). Any of the plane matrix modifications may be stacked to form a three-dimensional matrix store, Fig. 8, in which an individual word is stored in a vertical line. AND circuits 80-1 to 80-4 are provided, one for each of the Y windings of each horizontal plane, one input being from the Y decoding switch matrix 26 and the other from a terminal 85. To read the information in a particular word line, the terminals 85 of each plane are energized and the appropriate switches 15-1 to 15-4 conditioned. The pulse from the current driver unit 28 energizes the appropriate one of the buses 81 to 84. In those planes in which a flux change occurs an output is developed in the sense winding S. To write, the current driver 28 delivers a pulse in the write direction but only in those planes where it is desired to write a one are the potentials of terminals 85 raised to control the AND gate 80 so that in the other planes a zero remanence is retained. Specifications 784,549 and 789,096 are referred to.