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Browse Prior Art Database

Unipolar Drive Orthogonal Mode Bit Storage Device

IP.com Disclosure Number: IPCOM000094594D
Original Publication Date: 1965-Mar-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Pugh, EW: AUTHOR

Abstract

Use of two parallel-oriented film layers having different uniaxial anisotropy values provides an orthogonal mode bit storage device capable of very high-speed operation at good signal levels. One film layer is switchable between 1 and 0 states. The other film layer returns always to the 1 state and serves for signal comparison.

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Unipolar Drive Orthogonal Mode Bit Storage Device

Use of two parallel-oriented film layers having different uniaxial anisotropy values provides an orthogonal mode bit storage device capable of very high- speed operation at good signal levels. One film layer is switchable between 1 and 0 states. The other film layer returns always to the 1 state and serves for signal comparison.

The device is made up of two film layers 11 and 12 separated by nonmagnetic layer 13. The easy axes of the two film layers are parallel to each other. Layer 11 has substantially lower anisotropy than layer 12. This relationship permits a unipolar bit drive since film 12 biases film 11 toward the 0 state unless overcome by the bit drive field. Both layers have relatively high coercive force to resist bit disturbs and relatively low dispersion for good rotational switching. Layer 11 is the storage film while layer 12 is a comparison film which returns always to its 1 state.

In operating, the outputs of films 11 and 12 buck and cancel when film 11 is in the 0 state, providing essentially a null signal, and add when film 11 is in the 1 state, providing a large output signal.

The critical curves for rotational switching of the two layers are shown in the asteroid. The relationships of bit drive and word drive currents IB and IW are such that their coincidence switches film 11 to the 1 state, the pulse IB being required to be on until after IW is turned off. Current IW, when applied alone, switc...