have you ever withnessed calculators not working anymore due to corrupted memory?

[sleibson]

HP made the NMOS ROMs for the HP 9825's HPL language. The 9825A's big HPL language ROM is a slide-out drawer in the side of the machine. Early in the manufacturing cycle, we had a problem with sodium contamination in the ROM processing line. Sufficiently contaminated ROMs would initially work but would die over time as the sodium atoms migrated into the MOS transistor channels and shorted out the transistors. You tested for contamination with a leakage test. Leaky ROMs still worked but you knew they would eventually die. In the earliest days, it was easy to get prototypes of the 9825A hardware but really hard to get tested and certified ROMs, so a few of us got sets of leaky language ROMs and soldered them up so we'd have complete 9825As to work on for developing I/O cards. My "leaky" language ROM died after a year or so, but by then we had the contamination problem under control.

The point of this little history snippet is that many IC manufacturing processes back in the 1970s and 1980s were plagued by some level of contamination. RAMs or ROMs, it didn't matter. A transistor is a transistor. So all of those old ICs are possibly subject to eventual destruction.