[vcf-midatlantic] Good source for eproms?

Dave McGuire mcguire at neurotica.com
Fri May 27 11:46:49 EDT 2016

On 05/27/2016 11:02 AM, Herb Johnson via vcf-midatlantic wrote:
>>   They can be erased with X-rays.  EPROMs were originally designed to be
>> erased that way.  There are problems with that approach, however. (hence
>> the move to UV).
> The notion that one can plop non-quartz PROMs under an X-ray and erase
> them, has been mentioned here, and elsewhere for decades,  as a "could
> be done". But I'm not aware this has been, or is, any sort of common
> practice, much less an established procedure. I'm aware of 'theory', I
> know physics. I'm talking accepted practice.

  There is no accepted practice, but you and I know theory and physics,
so we know it's possible.  We've also read the documentation you
referenced below and know it had been done, and was originally the
intention for the product, but the approach had problems, so they moved
to an alternative method of erasure.

> Wikipedia....EPROM...citation 6...is a May 10 1971 article from
> Electonics Magazine by Dov Frohman, who apparently "invented the EPROM".
> Google.....
>  http://www.jmargolin.com/patents/eprom.htm
> references the article, and interviews the author later in 1993. The
> text say Intel shipped that 1702 EPROM "with a window because X-rays
> ....disrupted the structure" of the chip. The Web page has some details.
> I"ve not (yet) read the article, or checked the patent.
> This suggests that X-rays were not a production nor a customer practice.

  Yup.  But we already knew that. ;)

> so: Can you cite a reference I can find also, that shows a product
> announcement, or a production data sheet, that says specifically that a
> customer can erase a specific PROM product using X-rays of a particular
> wavelength and energy for a particular period of time?

  No.  I never said there were commercial products or production parts
that were intended to be erased with X-rays.

  I get the strong impression that you think I asserted that there were
production EPROMs which were intended to be erased in the field using
X-rays.  I made no such assertion.

> I'll grant the possibility this occurred for some very early product,
> some early development in the semiconductor lab, or some military or
> other specialized application.

  I think we can assume it had been done in the development lab because
the developer states that it "caused" a problem.  Not "could cause",
"may cause", but "caused".

> I'll grant some hackers could borrow a
> dental X-ray and erase an EPROM - did they do subsequent life-tests?
> Even that description would be of interest. Thank you.

  I have no idea if anyone has tried it outside of the original
development lab.  But I have an X-ray system, I could certainly try it
in my lab, or facilitate such experimentation here for others who have
more free time than I do.


Dave McGuire, AK4HZ
New Kensington, PA

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