>Erasable.  Just like in EPROM.  They actually contain EPROM
>guts, but in a plastic case, so you can't erase it.  (cheaper
>too, ceramic and quartz is expensive).
>  And before you ask, yes, it's been tried to erase these,
>though not successfully.  The EEPROM cells are only sensitive
>to UV, and that won't get through the plastic.

They are also erasable using x-rays. I remember a paper at a conference by a
guy who worked at a medical school and was asked to animate a dummy for use
under an x-ray to train students in the use of the machines without
requiring human patients to be exposed to the x-rays for extreme lengths of
time. His description of how the animations twitched and jerked as the
x-rays erased his EPROM's had to be heard to be believed. In his case he
solved the problem by using fusable link bipolar proms.

>> Shouldn't these devices be listed as Proms?

>They are usually listed as One Time Programables (OTP).

Agreed, just like the plastic cased versions of the non-flash PIC parts.

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