A method comprises applying a first reference drive voltage to a wordline of memory cells to generate a respective first resulting voltage level from each respective cell in the wordline, and storing in memory a first respective logic value indicated by the respective first resulting voltage level for each memory cell. The method further comprises applying a second reference drive voltage to the wordline of memory cells to generate a respective second resulting voltage level from each respective cell in the wordline while detecting a pattern of logic values stored in the memory in parallel. The memory is modified based on a second respective logic value indicated by the respective second resulting voltage level, and at least one of the first reference drive voltage and the second reference drive voltage is modified based on the detected pattern data.