If the number of write erase cycles is modest, the program flash may be used for EEPROM functions. The flash can be programmed an instruction word at a time. And by using EEPROM emulation methodologies within your software, you can increase the effective endurance, up to 10K write erase cycles. Should the application require very high numbers of write erase cycles, Microchip can provide external serial EEPROM products to achieve a cost effective solution.