Patent GB-1040022-A (GB)
Title: Improvements relating to data storage devices
Inventor: VINAL ALBERT WATSON
Filed: 1963-06-20
Abstract: 1,040,022. Magnetic storage devices. INTERNATIONAL BUSINESS MACHINES CORPORATION. June 20, 1963, No. 24521/63. Heading H3B. A storage matrix comprises magnetic elements each having a control aperture C and a read aperture R, the column energizing conductors being common to both the read and write apertures of respective columns of elements, and the row energizing conductors being separately associated with the control and read apertures in each row. A binary digit is written into or read from a magnetic element by applying the pulse trains (1)-(8), (1<SP>1</SP>)-(8<SP>1</SP>) shown in Fig. 2 to respective conductors passing through the read aperture 11 and control aperture 12, Fig. 2 (a), which shows an element in the unblocked state. When alternate read pulses (1)-(4) are of significant magnitude and the control pulses (1<SP>1</SP>)-(4<SP>1</SP>) are of lesser magnitude, the flux encircling the read aperture is reversed in direction, Figs. 2(b) to 2(e), and an output (1)<SP>11</SP>-(4)<SP>11</SP> is induced in a sense winding (not shown) threading aperture 11. An element is blocked when substantially the whole of its flux passes around both apertures as shown in Figs. 2 (f) to 2 (h), this condition being established by applying a significant negative control pulse (5<SP>1</SP>) and a coincident read pulse (5) of lesser magnitude. When a core is blocked, read pulses of significant magnitude (6), (7) have negligible effect on the stable magnetic state and no output is produced. The element is unblocked into the state shown in Fig. 2(a) by the coincident application of a positive control pulse (8<SP>1</SP>) of significant magnitude with a negative read pulse of lesser magnitude. The arrangement of matrix conductors in the various embodiments of a data store produce the significant pulses at the intersections of energized row and column conductors, and the pulses of lesser magnitude at all other apertures threaded by a single energized conductor. The lesser amplitude pulses act as biases which permit less critical current amplitudes to be used. Storage matrices. In Fig. 6, bipolar current sources 128, 129 are connected to respective conductors RX1, CY1 and RY2, CY2 which pass through all the reading and control apertures R, C of storage elements 101-104. Bipolar current sources for the other co-ordinate are connected to conductors RX1, CX2 and RX2, CX1, each threading control apertures in one column and read apertures in the other column. To read a single element a column and a row pulse source are rendered operative, the combined pulses in the read aperture of the selected element being sufficient to reverse the flux direction about that aperture. The adjacent element having its control aperture threaded by both energized conductors is unaffected as the currents act in opposite directions and mutually cancel. Similarly an element is blocked by applying pulses of appropriate polarity to a selected row and a column conductor. A modified circuit is shown in Fig. 7 in which separate pulse sources 130<SP>1</SP>, 130<SP>11</SP> and 1311, 131<SP>11</SP> are provided for the columns of read and control apertures. The Fig. 6 arrangement is applied to a larger matrix in Fig. 8 which shows the sense winding 140 and an inhibit winding 141, the latter winding being utilized in threeco-ordinate store applications. Each of the matrix conductors includes a characteristic impedance 180 only one of which is shown, this impedance being connected in parallel with the associated conductor between the pulse source and ground. A three co-ordinate matrix arrangement is shown in Fig. 9 in which a single element in each plane may be read or blocked simultaneously. Instead of separate magnetic elements a multi-aperture plate of ferrite 181 may be used, Fig. 11, the control and read apertures being positioned so as to prevent interference between the various magnetic circuits.