Hi Jerry,

..you need a head start. It is too late when you are in power-fail to save your data. You need a reasonable method of detecting power fail, then means of holding up the supply long enough to do all you need to do.

Peter is right, a cap is often good enough, If you are really stuck, then a super-cap is better still.

Dallas do a range of parts to monitor and switch RAM to safe storage.

Steve