IIRC, EPROMs were still cheaper than EEPROMs for many years. EPROMs probably were sold in commercial quantities well into the 80s, and maybe used in the 90s.

EPROMs were erased by just throwing them into a UV-bin and blasting them with UV light. In contrast, EEPROMs needed transistors inside to handle the erasing cycle.

Finally, EPROM's last stand was as a low-cost one-time-programmable ROM (aka: PROM). All you had to do was make the same chip except without the expensive "window" (that'd normally receive UV-light for erasure).

And thanks for the info, I don't have direct experience dealing with EPROM and I had conflated EEPROM and EPROM together in my mind, but a quick google search quickly reveals my inadequate knowledge, which has now been updated, even if only good enough for trivia.