Method of operating a convertible memory system

Claim 3

The method of claim 1 wherein each of said magnetizable memory elements includes superposed pairs of thin-ferromagnetic-film layers each pair of layers including a relatively high Hk layer and a relatively low Hk layer, a bit and sense line sandwiched between and enveloped by said pairs of layers for coupling substantially longitudinal drive fields to said layers along a sense magnetic axis and for detecting output signals indicative of the particular stored state of said memory element, a word line for coupling substantially transverse drive fields to said layers along a drive magnetic axis that is substantially orthogonal to said sense magnetic axis, said layers having substantially parallel easy axes along which their remanent magnetization shall lie, said parallel easy axes skewed with respect to said sense magnetic axis an angle that is at least as great as the dispersion angle of the high Hk layers, the method of establishing each of said memory elements in one of a plurality of stored states comprising: establishing a memory element of said first portion in an NDRO 0 stored state by; coupling a current pulse to said word line for establishing in the areas of said layers a first transverse drive field of a first polarity along said drive magnetic axis; said first transverse drive field establishing the flux polarizations of the layers of each pair in an antiparallel relationship and the flux polarizations of the high Hk layers of each pair in a parallel relationship establishing said memory element in an NDRO 0 stored state; establishing a memory element of said first portion in an NDRO 1 stored state by; coupling a current pulse to said word line for establishing in the areas of said layers a second transverse drive field of a first polarity along said sense magnetic axis; coupling a current pulse to said bit line for establishing in the areas of said layers a first longitudinal drive field of a first polarity along said sense magnetic axis and of an intensity when combined with said second transverse drive field sufficient to bias the magnetization of the first pair of layers in a first direction away from said drive magnetic axis and sufficient to bias the magnetization of the second pair of layers in a Second direction, opposite from said first direction, away from said drive magnetic axis; terminating said second transverse drive field for permitting said still applied first longitudinal drive field to steer the magnetization of said layers in said first or second direction substantially along said sense magnetic axis; terminating said first longitudinal drive field for permitting the magnetization of said layers to reside in said first or second direction substantially along said easy axes; said combination of said second transverse drive field and said first longitudinal drive field establishing the flux polarizations of the layers of each pair in a parallel relationship and the flux polarizations of the high Hk layers of each pair in an antiparallel relationship establishing said memory element in an NDRO 1 stored state.

Claim 4

The method of claim 2 wherein each of said magnetizable memory elements of said second portion is established in a DRO 1 or DRO 0 stored state by; establishing said memory element in said NDRO 1 stored state; coupling a current pulse to said word line for establishing in the areas of said layers a third transverse drive field of a first polarity along said drive magnetic axis; said third transverse drive field substantially biasing the magnetization of said low Hk layers away from said easy axes but insubstantially biasing the magnetization of said high Hk layers away from said easy axes; coupling a current pulse of a first or of a second and opposite polarity to said bit line for establishing in the areas of said layers a second longitudinal drive field of a first or of a second and opposite polarity along said sense magnetic axes and of an intensity when combined with said third transverse drive field sufficient to substantially effect the magnetization of said low Hk layers but insufficient to substantially effect the magnetization of said high Hk layers; terminating said third transverse drive field for permitting said still applied second longitudinal drive field to said first or second polarity to bias the magnetization of said low Hk layers in a first or a second and opposite direction, respectively, substantially along said sense axis; terminating said second longitudinal drive field for permitting the magnetization of said low Hk layers to reside in said first or second direction substantially along said easy axes; said combination of said third transverse drive field and said first polarity second longitudinal drive field establishing the flux polarizations of the layers of each pair in a parallel relationship and the flux polarizations of the high H layers of each pair in an antiparallel relationship establishing said memory element in a DRO 1 stored state; said combination of said third transverse drive field and said second polarity longitudinal drive field establishing the flux polarizations of the layers of each pair in an antiparallel relationship and the flux polarizations of the high Hk layers of each pair in an antiparallel relationship establishing said memory element in a DRO 0 stored state.

Claim 5

The method of claim 3 further including reading-out the NDRO stored state of said memory element, comprising: coupling a current pulse to said word line for establishing in the areas of said layers a fourth transverse drive field of a first polarity along said drive magnetic axis; said fourth transverse drive field substantially effecting the magnetization of said low Hk layers but insubstantially effecting the magnetization of said high Hk layers; detecting the NDRO stored state of said memory element during the application of said fourth transverse drive field as a significant or insignificant output signal in said sense line indicative of the readout of an NDRO 1 stored state or of an NDRO 0 stored state, respectively; after said read operation uNconditionally coupling a current pulse to said bit line for establishing in the areas of said layers a third longitudinal drive field of a first polarity along said sense magnetic axis and of an intensity when combined with said fourth transverse drive field sufficient to substantially effect the magnetization of said low Hk layers but insufficient to substantially effect the magnetization of said high Hk layers for restoring the flux polarizations of said low Hk layers into their prior NDRO 1 stored state or their prior NDRO 0 stored state.

Claim 6

The method of claim 4 further including reading out the DRO stored state of said memory element, comprising: detecting the DRO stored state of said memory element during the application of said third transverse drive field as a first or a second and opposite polarity output signal in said sense line indicative of the readout of a DRO 1 stored state or of a DRO 0 stored state, respectively.

Claim 7

The method of claim 5 wherein said first and second transverse drive fields are of an intensity, in the areas of said layers, substantially equal to the Hk of the high Hk layers.

Claim 8

The method of claim 6 wherein said third transverse drive field is of an intensity, in the areas of said layers, substantially one-fourth the Hk of the high Hk layers.

Claim 9

The method of claim 7 wherein said fourth transverse drive field is of an intensity, in the areas of said layers, substantially one-fourth the Hk of the high Hk layers.