1. A non-volatile solid state resistive device, comprising: a first electrode; a p-type polycrystalline silicon-bearing second electrode; a non-crystalline silicon nanostructure electrically connected between said electrodes such that said nanostructure has a resistance that is adjustable in response to a voltage being applied to said nanostructure via said electrodes; and a control circuit operable to adjust the resistance of said silicon nanostructure between more than two resistance values.