Methods of programming memory cells and control circuitry for memory arrays facilitate a reduction of program disturb. A memory cell is shifted from a first data state to a second data state if it is desired to alter a first digit of a data value of the memory cell. If it is desired to alter a second digit of the data value of the memory cell, the memory cell is shifted to a third data state if the memory cell is in the first data state and shifted to a fourth data state if the memory cell is in the second data state. The first, second, third and fourth data states correspond to respective non-overlapping ranges of threshold voltages. The threshold voltages corresponding to the fourth data state are greater than the threshold voltages corresponding to the third data state.