GB833376A - Improvements in or relating to pulse generating apparatus - Google Patents

Abstract

833,376. Circuits employing bi-stable magnetic elements. INTERNATIONAL COMPUTERS & TABULATORS Ltd. May 19, 1958 [July 19, 1957], No. 22928/57. Class 40 (9). In a circuit utilizing magnetic cores with rectangular hysteresis loops, the Switching current applied to an arrangement of cores 1, 7 for the purpose of applying a reading pulse to a selected row winding of a magnetic storage matrix 6 is limited in amplitude by reversing the saturation remanent state of a further core 9. This current amplitude limitation is stated to be necessary to avoid overcoming an inhibiting bias applied to a winding 4 on the core 1, 7 associated with an unselected row. In operation, the switching current pulse is applied to cores 1, 7 and 9 by way of a triode or pentode valve 8. The pulse is of such amplitude and duration that it terminates before core 9 completely reverses its magnetic state, and a writing pulse is established in the output winding 5 of an unhibited core 1, 7. A valve 14 is then made conductive so that core 9 is reset to its initial magnetic state. A valve 15 controls the application of a switching pulse to windings 3 on cores 1 and 7 so that writing pulses are induced in windings 5, the recording of information being effected in the usual manner by coincidence of currents in row and column windings (not shown). The amplitude of each row writing pulse is restricted by limiting the potential across windings 3, and a limiting circuit comprising a rectifier 18 biased by an adjustable low-impedance source comprising a cathode follower 19 and an adjustable potentiometer 20 is provided for this purpose