Four words in the memory space (8000h-8003h) are designated as ID locations where the user can store checksum or other code identification numbers. These locations are readable and writable during normal execution. See the “NVMREG Access to DIA, DCI, User ID, DEV/REV ID, and Configuration Words” section for more information on accessing these memory locations. See the “Memory Programming Specification” section in the “Electrical Specifications” chapter for information on the electrical parameters required to program these memory locations. For more information on checksum calculation, see the “Family Programming Specification”.