It is amazing how much old stuff still shangs around such as the 8 NAAH, let's not go there :).

Anyhow, the code memory checksum idea stem from the olden days when memory was ferrite beads and the risk of corrupted memory was real. The best example I have seen of the futility in transferring what used to be to what is is that I once saw a mask programmed chip with a code memory checksum check.

to Jan:
want to check a section which is likely to be corrupted e.g. when ISP reprogramming goes wrong. That is the one relevant use I know of. With chips with a readback capability, however, I prefer a compare of each and every byte. Now some of the more modern chips do not have a readback capability because of the desire to protect from code theft and in such cases, the checksum is relevent.

HOWEVER, the likelyhood of the checksum checking working (not corrupted) and something else being corrupted is infinitessimally small.

Erik