Abstract: A universal memory element having multi-level, non-detectable states and methods and apparatus for programming the same, and methods and applications embodying the same in neural networks, artificial intelligence and data storage systems. The universal memory element is programmed by applying one or more sub-interval energy pulses insufficient to switch the memory element from said high resistance state to said low resistance state, but sufficient to modify the memory material such that accumulation of additional energy pulses causes the memory element to switch from said high resistance state to said low resistance state.