GB762057A - Improvements in or relating to electronic magnetic recording systems - Google Patents

Abstract

762,057. Electric digital-data storage apparatus; recording-apparatus. GENERAL ELECTRIC CO. Nov. 30, 1954 [Nov. 30, 1953], No. 34736/54. Classes 106 (1) and 106 (4). Electronic apparatus for enabling the recording and playing back of data indicative signals on a moving magnetic storage medium comprises a plurality of control heads 13 associated with the storage medium and arranged in a matrix of row and columns, the control heads each including a coil 63 and a magnetic flux directing element 65 for providing a flux path between the coil and the storage medium, together with switching means 15 for selecting a particular row and switching means 17 for selecting a particular column so that the control head at the inter-section of the selected row and column is energized and further switching means 19 for enabling the selected head to be used either to record data on to the magnetic storage medium or to read data from the magnetic storage medium. As shown, the matrix comprises only two rows A, B, and two columns a, b, and is particularly adapted for digital data. For recording data the read/record control switch 19 is set to connect a high potential (180 V.) source 107 to the row selecting switch. The row and column selecting switches 15, 17 are then appropriately set to select the desired head, say head Aa (top left). This results in a high voltage being applied to all the centre taps of the coils in the selected row and hence via rectifiers 69 to all the triodes 33, two of which are associated with each column, and in a gate opening potential being applied to two " and " gates 25, 27, associated with column a. A data signal to be recorded, either a " plus " generated by a device 21 of a " minus " generated by a device 23, then passes through gate 25 or gate 27, firing one of the tubes 33 and causing a current to flow in one direction or the other through the selected head, thus recording either a " plus " or a " minus " on the moving magnetic medium which may for example be a drum. To read data, a particular head is selected in the same way, but the read/record switch 19 is set to connect a low potential (10 V.) to the switch 15. This voltage is insufficient to permit tubes 33 to conduct but sufficient to unblock the right-hand rectifiers 69, each of which is earthed via a resistance 111. The column selecting switch also opens an " and " read gate 41 associated with the column a so that any signal developed across resistor 111, as a result of current flow in the selected head created by reading data on the magnetic medium, is passed via gate 41 to a read amplifier 45. The switches 15, 17 and 19 may be electronic trigger circuits.