Abstract: A nonvolatile memory bank of an electronic memory and retrieval system is partitioned into at least three memory blocks, each block capable of storing an accounting program. The accounting program data is stored in duplicate with one copy of the data in one memory block and a second copy of the data in a second memory block. The remaining memory blocks of the partitioned memory bank are held in reserve status. The integrity of the data is preserved by comparing one data copy with the other data copy. When a difference between the two data copies is detected, a determination is made as to which data copy is the correct data copy. The data in the memory block having the correct data is duplicated into a reserve memory block, forming a new set of data in a new memory block, which is then substituted for the memory block having the incorrect set of data.