Multiple state memory

Claim 2

An isotropic thin film memory system for reading and writing information out of and into defined storage locations each of which has multiple storage states, said system comprising, in combination: a thin film memory plane having a surface of substantially isotropic magnetic material, a plurality of column conductors disposed adjacent said surface and substantially parallel with one another, a plurality of row conductors which are substantially parallel with one another and are spaced from and transverse to said column conductors, said storage locations being located within said magnetic surface and associated with the points of intersection of said column and row conductors, first generating means for generating signals of a prescribed amplitude applied to respective column and row conductors for writing information into mutually respective storage locations, said prescribed amplitude signals to said column conductors having the same magnitude as said prescribed amplitude signals to said row conductors, said first generating means including second means for generating a signal of an amplitude at least twice said prescribed amplitude applied to at least one of said column conductors for reading information out of associated storage locations, and sensing means coupled to said row conductors for detecting the information read out of the storage locations.

Claim 3

The thin film memory system as defined in claim 1 wherein selector means are coupled to said generating means and said conductors for selecting column and row conductors to carry respective signals for writing information into associated storage locations and for selecting a given column conductor to carry a signal for reading information ouT of associated storage locations.

Claim 4

The thin film memory system as defined in claim 1 wherein said magnetic material is isotropic in directions mutually perpendicular to each other and said column and row conductors are aligned with respective isotropic directions and are substantially perpendicular to each other.

Claim 5

The thin film memory system as defined in claim 3 wherein said first generating means includes means for timing said signals to be carried by respective column and row conductors for writing information into a given storage location so that one signal leads and is concurrent with a portion of the other at said storage location, whereby the other signal determines the storage state of said storage location.

Claim 6

A planar memory having a plurality of storage locations in a magnetic plane, each location being associated with a respective point of intersection of column and row conductors disposed over the magnetic memory plane, comprising: a continuous plane of isotropic magnetic material that has two axes of easy magnetization which are mutually perpendicular to each other, said magnetic material being capable of attaining opposed states of residual flux density along each of said axes of easy magnetization and having magnetic moments capable of being rotated through said states by the application of a magnetic field of a prescribed intensity; a plurality of column conductors disposed over said magnetic plane and aligned with one axis of magnetization so that a flow of current therethrough establishes a first magnetic field at substantially 90* from said axis; a plurality of row conductors spaced from and transverse to said column conductors and aligned with the other axis of easy magnetization so that a flow current therethrough establishes a second magnetic field at substantially 90* from said axis; means for selectively producing a first current flow through at least one of said column conductors and a second current flow through at least one of said row conductors to establish a combined write-magnetic field of sufficient intensity to couple their mutually respective storage locations and attain a state of residual flux density along one of said axes of easy magnetization according to the polarity of the last terminating current flow; and means for selectively producing a current flow through at least one of said column conductors to establish a read-magnetic field of sufficient intensity to couple its respective storage locations and to rotate the magnetic moments at said respective locations from their original state to the state determined by the direction of said read-magnetic field; and means coupled to said row conductors for sensing the change or absence of change in state of said magnetic moments at said respective locations.

Claim 7

A planar memory having a plurality of storage locations in a magnetic plane, each location being associated with a respective point of intersection of column and row conductors disposed over the magnetic memory plane, comprising: a continuous plane of isotropic magnetic material that has two axes of easy magnetization which are mutually perpendicular to each other, said magnetic material being capable of attaining opposed states of residual flux density along each of said axes of easy magnetization and having magnetic moments capable of being rotated through said states by the application of a magnetic field of a prescribed intensity; a plurality of column conductors disposed over said magnetic plane and aligned with one axis of magnetization so that a flow of current therethrough establishes a first magnetic field at substantially 90* from said axis; a plurality of row conductors spaced from and transverse to said column conductors and aligned with the other axis of easy magnetization so that a flow current therethrough establishes a second magnetic field at substantially 90* from said axis; means for selectively producing a first current flow through at least one of said column conductors and a second current flow through at least one of said row conductors to establish a combined write-magnetic field of sufficient intensity to couple their mutually respective storage locations and attain a state of residual flux density along one of said axes of easy magnetization according to the polarity of the last terminating current flow; and means for selectively producing a current flow through at least one of said column conductors to establish a read-magnetic field of sufficient intensity to couple its respective storage locations and to rotate the magnetic moments at said respective locations from their original state to the state determined by the direction of said read-magnetic field; and means coupled to said row conductors for sensing the change or absence of change in state of said magnetic moments at said respective locations.