But don't EEPROMs also have a data retention problem at high temperatures?

Now that we know he only wants a few bytes, he could use software fault tolerance methods to reduce the susceptibility to changed memory bits.

Better information on data retention would be very helpful. Perhaps there is a temperature above which it becomes extremely likely that the contents change. Then EEPROM would become out of the question. As I recall, punch cards retain their memory state well above 125 C... Except in places like Florida ;)

- Lee