Accession Number : AD0896844

Title :   A Coincident-Current Magnetic Memory Unit,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE SERVOMECHANISMS LAB

Personal Author(s) : Papian, William N.

Report Date : 08 SEP 1950

Pagination or Media Count : 86

Abstract : A small, toroidal, ferromagnetic core whose B-H characteristic is properly 'rectangular' in shape may be made to operate so that its flux polarity reverses only when the right combination of two or three magnetizing coils are coincidentally excited. The core may then be used as a coincident-current binary memory device which might be assembled, with many others, into a two- or three-dimensional memory system. Selection within such a system would be accomplished by means of physical-line switching along the two or three space coordinates. The response times of rectangular-loop cores are found to vary over an extremely large range. To a first approximation, eddy-current shielding accounts for these response times, which range from tenths of a second for some metallic cores to less than a microsecond for some ferritic cores. Information-retention ratios and signal ratios are defined and are used to assess the ability of a core to operate as a coincident-current memory unit. A test setup which makes it possible to obtain these ratios for different sets of operating conditions is devised and used on a number of cores. Selected results are presented and discussed relative to the pertinent hysteresis-loop shapes.

Descriptors :   (*DIGITAL COMPUTERS, FEASIBILITY STUDIES), (*CORE STORAGE), (*MAGNETIC CORES), FERROMAGNETIC MATERIALS, EDDY CURRENTS, SHIELDING, REACTION TIME, RETENTION(GENERAL).

Subject Categories : Computer Hardware

Distribution Statement : APPROVED FOR PUBLIC RELEASE