[emeritus]

In the 1970's a former colleague who was then working for another company told me that they had found out that you could erase non-erasable eproms by putting them in a microwave oven. This allowed them to use cheap non-erasable eproms in their development lab rather than the expensive UV-erasable type having a quartz window. I think that the type they were using used the same chip type in both the erasable and non-erasable types, the package being the only difference. I don't recall how long a dose was required and have had no experience with eproms myself, whether ancient or modern. Nor do I know whether this technique had any long-term effects on reliability, not an issue in the circumstances in which they were using them.