>I had a girlfriend who is a doctor in a vet clinic. So I made up a test
>card of EPROMs and EEPROMs, in two batches.
>She then exposed them to the X-rays, the first batch for about 10 secs,
>the second four times that.
>I wanted to get maybe a second life out of the big number of OTP parts
>that are around...
>
>But sorry, no go, the intensity was WAY too low, and as it was in a
>clinic I am inlcined to say that YES, it would have stained a film...

X-rays will eventually erase EPROM's.
I remember a story related by someone presenting a paper at a conference. He
worked in a university that had a medical section, and was asked to build a
dummy patient that could be used by students when training on a x-ray
machine so they could see the motion of organs. This machine must have been
capable of continuous display.

Everything worked well for a while, but then intermittently the dummy body
would give an involuntary twitch, with intervals between twitches getting
shorter until the dummy body went into total spasm. The x-ray machine had
erased the EPROM's used. In this situation the solution was to move to
bipolar fusible link proms that were pin compatible.

As a side issue to this, in the space electronics environment where I now
work, we use small pieces of tantalum sheet glued and tied over the top and
bottom of components that do not have sufficient radiation capability for
earth orbit flight. One of my colleagues recently did this for some EEPROMS
used on a low earth orbit instrument he was working on. Tantalum is
apparently one of the highest density metals when it comes to stopping
radiation, presumably on a weight/radiation stopping trade-offs, but that is
not my area of expertise.

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