Whenever N data bits are stored in a cell of a memory that programs each of its cells to represent any one of 2.sup.N different patterns of N>1 bits as a respective one of 2.sup.N ordered cell states, the N data bits are mapped to a transformed pattern of N bits according to a transformation that maps the pattern of the lowest state (typically all 1's) to a different pattern, and the cell is programmed to represent the transformed pattern. The transformation may invert all, some or only one of the bits of each pattern. Whenever the cells of the memory are read, the transformation is inverted.