please can you describe in words the principle of your code for life extension

I need only to write one word (which can not be 0xffff).

I search for the first slot that is 0xffff and write the new data there

I search for the first slot that is not 0xffff and read the data one slot back.

when the EEPROM is full I erase it which set all slots to 0xffff.

This way the life of the EEPROM becomes (bytes in eeprom)/(data size)*(EEPROM guaranteed writes)

Erik