1. A memory device comprising: a first memory unit comprising at least first and second resistance variable memory elements, the first and second memory elements having a common first electrode, and respective second electrodes; a second memory unit comprising at least third and fourth resistance variable memory elements, the third and fourth memory elements having a common first electrode, and respective second electrodes, the second and third memory elements having a common second electrode; and switching circuitry for selectively applying a voltage access selected second electrode and a selected first electrode.