Thanks Rob, I wondered about that, is that the RC register they talk about in the datasheet?
I can store the previous best number ( 0-99) preferably in 2 bytes ( so I can just use each one - tens and units - easily for the display.) Although I still have to compare it to the current elapsed days to see which is the "best"
The date can be yyyy mm dd or seconds since 1970 . so I don't know the best way to try to store it.
If I store it in seconds since 1/1/1970 I can easily divide down the difference between latest and stored seconds to get elapsed days, but I still will need to display the previous date after a power down.....?