Multiple modes of operation in a cross point array

1. A method comprising:

providing a first layer of conductive array lines, the conductive array lines being arranged so that they do not come into direct contact with each other;

providing a second layer of conductive array lines, the conductive array lines being arranged so that they do not come into direct contact with either each other or any of the conductive array lines of the first layer;

selecting at least one conductive array line pair, the conductive array line pair being one of the conductive array lines from the first layer and one of the conductive array lines of the second layer;

applying a read voltage across the at least one conductive array line pair during a read mode, the read voltage producing a read current, wherein the read current is indicative of a first program state when the read current is at a first level and indicative of a second program state when the read current is at a second level, the read current being ineffective to produce a change in program state;

applying a first voltage pulse across the least one conductive array line pair during a first write mode if in the second program state, wherein the first voltage pulse is effective to modify the programming state from the second program state to the first program state; and

applying a second voltage pulse across the least one conductive array line pair during a second write mode if in the first program state, wherein the second voltage pulse is effective to modify the programming state from the first program state to the second program state.

2. The method of claim 1 , wherein the conductive array line pair represents the exclusive electrical path to a memory plug defined by the conductive array line pair.

3. The method of claim 2 , wherein the memory plug includes an oxide that is sensitive to the first voltage pulse and the second voltage pulse.

4. The method of claim 3 , wherein the oxide is crystalline.

5. The method of claim 4 , wherein the oxide is polycrystalline.

6. The method of claim 2 , wherein the memory plug includes a non-ohmic device that exhibits a high resistance regime for a certain range of voltages and a low resistance regime for voltages above and below that range.

7. The method of claim 6 , wherein the read voltage, first write voltage and second write voltage are all within the low resistance regime.

8. A cross point array comprising:

a first layer of conductive array lines, the conductive array lines being arranged so that they do not come into direct contact with each other;

a second layer of conductive array lines, the conductive array lines being arranged so that they do not come into direct contact with either each other or any of the conductive array lines of the first layer;

wherein a first voltage pulse is applied across at least one conductive array line pair during a first read mode, the conductive array line pair being one of the conductive array lines from the first layer and one of the conductive array lines of the second layer;

wherein a second voltage pulse is applied across at least one conductive array line pair during a second write mode;

wherein a read voltage is applied across at least one conductive array line pair during a read mode, the read voltage producing a read current;

wherein the read current from a conductive array line pair is at a first level subsequent to the conductive array line pair having the first voltage pulse applied during the first write mode and before the second voltage is applied during the second write mode;

wherein the read current from a conductive array line pair is at a second level subsequent to the conductive array line pair having the second voltage pulse applied during the second write mode and before the first voltage is applied during the first write mode.