GB1085955A - Improvements in or relating to magnetic core storage matrices - Google Patents

Abstract

1,085,955. Magnetic storage matrices; transistor current switching circuits. AUTOMATIC TELEPHONE & ELECTRIC CO. Ltd. June 16, 1964 [July 27, 1963], No. 29879/63. Headings H3B and H3T. Current to a row or column drive winding of a coincident current matrix, in which each winding is connected between a primary and a secondary transistor selector, is obtained from a transistor connected to the primary selector which current is diverted from a path to a first source of potential to a path through the winding when a third transistor selector connected between a second source of potential and the secondary selector is energized subsequent to the energization of the primary and secondary selectors. In the 64 x 64 matrix of Fig. 1 the core lines are divided into groups of eight and the method of selecting a core line is such that the primary selectors RYP1, WYP1, RXP1, WXP1 &c. are each connected to all the core lines of a particular group while the secondary selectors WYS1, RYS1, WXS1, RXS2 &c. are each connected to corresponding core lines in all the groups. The references in brackets attached to various leads indicate the core lines to which such leads are connected. The primary and secondary selector stages are connected to current defining circuits TXD and to current defining circuits TS as shown in Fig. 2. When no magnetic core lines are being selected all the current defining transistors TXD conduct while all the other selector transistors are cut off. In order to select the core line CL for writing purposes stages WYP1 and WYS1 are actuated but the current through transistors TXP and TXS of these stages do not conduct sufficiently to switch the cores. Subsequent to and during the activation of the primary and secondary selector stages transistor TXT is rendered conductive by application thereto of a pulse from transistor TXA over transformer T1 so that transistors TXS, TXP pass the total collector current of transistor TXD, i.e. halfcurrent pulse required for coincident current core selection. Saturation of the transistors is prevented by diode D4. At the end of the pulse from the secondary winding of T1 transistor TXT is cut off and diode D1 and voltage source V1 again provides collector current for transistor TXD which transistor is protected against back e.m.f.'s by diode D2. After transistor TXT is cut off the transistors TXS and TXP are rendered non-conducting.