Who first used the term "bit rot"?

The oldest reference on Usenet I can find is in the subject line "Creeping Bit Rot in Bnews" in this 24th January 1982 net.news.b posting, discussing data loss.

It's next mentioned in this 22nd April 1983 net.misc posting, discussing various sources of bit rot in computing:

I have always heard "Program Entropy" referred to as "bit rot". It is a serious and ubiquotous phenomenon of computing systems. Any working program will in time tend to deteriorate if not periodically cared for. The minimal level of care requires periodic recompilation and fixing the bugs you discover.

However, Usenet only dates back to 1981 so I'm sure there's something earlier.