GB1195582A - Selection Circuit for Magnetic Core Memories - Google Patents

Abstract

1,195,582. Circuits employing bi-stable magnetic elements. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 27 June, 1967 [30 June, 1966], No. 29526/67. Heading H3B. [Also in Division G4] In a magnetic core memory matrix a column or row of magnetic cores is selected by means of a transistor switch in the primary circuit of a transformer which supplies write or read pulses to the column, or row. In order to supply read current from current pulse source I L to a selected matrix wire MD transistor T L is made conductive and transistor T s switched off. Thus transistors T<SP>1</SP> m and transistor T n conduct when pulses are applied to their bases whilst transistors T m and T n <SP>1</SP> remain cut off. Read current i L flowing through the primary of transformer TR m and transistor T m <SP>1</SP> causes a current pulse to be induced in the secondary winding of transformer TR m which flows through diode D, matrix wire MD, diode D L , transistor T n and transistor T L . After transistor T L is cut off at the end of the read cycle transistor T s is made conductive for the write cycle. When transistors T n , and T n <SP>1</SP> are rendered conductive by current pulses applied to their bases, transistors T n ,<SP>1</SP> and T n remaining cut off, a current write pulse i s from a common write current source Is flows through transformer TR n and transistor T n <SP>1</SP> inducing a write current pulse in the secondary of transformer TR n . This pulse flows through diode D s in the reverse direction through the matrix wire MD, through transistor T n , and transistor Ts.