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Nondestructive Readout Thin Film Memory

IP.com Disclosure Number: IPCOM000094517D
Original Publication Date: 1965-Feb-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Jutzi, W: AUTHOR

Abstract

Each memory cell consists of two magnetically coupled films separated by a conducting shield, e. g., a silver layer. Binary information is represented by the alignment of the magnetization in the easy axis in an antiparallel closed flux mode. For 1 the magnetization of the upper film points backwards and that of the lower film forwards. For 0 the reverse applies. The sandwich films are positioned between the metallic ground plate and the bit-sense transmission lines. They can be common or arranged side by side in the same plane. Their attenuation is kept small. Dummy lines can also be provided in the same plane for bit noise compensation. The word transmission lines which are placed on top run orthogonally to the bit-sense lines. Word, bit-sense, and dummy lines are preferably slotted.

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Nondestructive Readout Thin Film Memory

Each memory cell consists of two magnetically coupled films separated by a conducting shield, e. g., a silver layer. Binary information is represented by the alignment of the magnetization in the easy axis in an antiparallel closed flux mode. For 1 the magnetization of the upper film points backwards and that of the lower film forwards. For 0 the reverse applies. The sandwich films are positioned between the metallic ground plate and the bit-sense transmission lines. They can be common or arranged side by side in the same plane. Their attenuation is kept small. Dummy lines can also be provided in the same plane for bit noise compensation. The word transmission lines which are placed on top run orthogonally to the bit-sense lines. Word, bit-sense, and dummy lines are preferably slotted. The shielding layer is continuous at least in the area of the cells. The metallic ground plate serves as common return conductor for all transmission lines.

For nondestructive read operation, the cycle R is about 15 sec.

In this operation, relatively short word fields are applied along the hard axis of the film. As a result the magnetization of the upper film rotates with high speed towards the hard axis. Owing to the generation of eddy currents in shielding layer and ground plate, rotation of the magnetization of the lower film is strongly impaired.

The sense line picks up the resulting magnetic flux change. The fast-switching upper film ess...