I have lots of AM27C512 65k x 8b EPROMS (with the UV window) which are quite old (1980's.) Using a Xeltek SuperPro 3000U, most can still be read and verified. A few have failed outright and were replaced.
Question: Can these be successfully "refreshed" by reprogramming the same bit pattern back to them, without UV-clearing them first? They seem to take a reprogramming fine, but was curious whether this is moot without an erasure first.
Edit: Wanted to mention that so far, I've tried "refreshing" about 10 of these 256kB EPROMS. All of them read fine, were programmed (with the same data) fine, and verify fine. So "refreshing" hasn't seemed to hurt them at all. I'm still a little sketchy about whether this will make any lasting difference in their longevity however - answers are quite mixed.