A method of programming data regions in a nitride read-only memory cell is described. In an erased state, the nitride read-only memory cell exhibits a low Vt value. A data region that is to be programmed to a highest Vt value is programmed first. Remaining data regions in the nitride read-only memory cell are programmed in a time order according to their descending Vt values. For a nitride read-only memory cell that, in an erased state, exhibits a high Vt value, a data region that is to be programmed to a lowest Vt value is programmed first with remaining data regions programmed in a time order according to their ascending Vt values.