[vcf-midatlantic] Good source for eproms?

Dave McGuire mcguire at neurotica.com
Fri May 27 16:21:50 EDT 2016

On 05/27/2016 03:23 PM, Herb Johnson via vcf-midatlantic wrote:
> I'm persisting, because this "x-rays to erase EPROMS" keeps getting
> talked about, decade by decade. But it is just - plain - impractical,
> and never WAS practical, but most certainly was not approved by the
> manufacturers in products. Please note my qualifiers.

  Yup, I think we're all in agreement here.

>>  We've also read the documentation you
>> referenced below and know [x-ray erasure] 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.
> Dave, my point is to debunk the idea that X-rays were EVER intended to
> be a way to erase EPROMS, except as some early lab result or research
> idea. "Intention for the product" says to me "we are developing a
> product that will include use of X-rays to restore the product to an
> unprogrammed state", with the implication that it would be within its
> *production design* and *approved customer use* to be erased that way.
> But it wasn't. So X-rays were never recommended or used *in practice*.
> Practice, Dave, not that someone didn't TRY it at some point.

  Herb, seriously, I GET IT.  I personally do not believe there was ever
a practical method to erase EPROMs using X-rays.  I only asserted that
it is possible, which we both seem to believe that it is.  Possible.
That's all.

  I NEVER said it was a production technique.  I NEVER said it was an
"accepted" (by whom?!) process.  I NEVER said it was a good way to do
it.  I NEVER said it would help one lose weight, keep away pimples, keep
one's dog from crapping on the floor, or anything else.  I ONLY said IT

  Further, unless Dov Frohman can be reached and simply asked about this
(which I will pursue independently), we will never know for sure if it
was the INTENTION or PLAN that EPROMs be erased with X-rays.  However,
we know their team investigated it.

> The "erasable" 1702 was designed for production with a quartz window, so
> the customer or factory could erase the EPROM, by specified light, time,
> and energy. That's "production", that's "accepted practice". It's on the
> data sheets! Dave, do you see my point?

  I do.  But Frohman's description of the process in which they decided
to put a window in what we can reasonably assume to have previously
considered to be an unwindowed package, like every other IC built up to
that point, suggests strongly to me that it was the original intention.

  Note well, once again, that I never said it was a practical production

> reports  a 1971 article by Frohman (Intel's designer of the EPROM) is
> quoted to describe how a "package is sealed, information can still be
> erased...by X-ray...with commercial X-ray generators".

  Yes.  Which is exactly what I said originally.

> BUT - the above Web page carries an interview - by the Web page author
> so it's second-hand - with the author in 1993. And Frohman said in 1993
> as paraphrased: (quoting the reportage) "they ended up deciding to ship
> the part with a window because erasing the EPROM with X-rays created
> surface states in the silicon that required annealing." Annealing is
> described as a process above 450 degrees Celsius.
> Need I explain the impact of 450 C upon a plastic package?  Or guess the
> impact upon a sealed ceramic package? the melting temperature of solder,
> expoxies, etc? Dave, I can probably erase an EPROM with *fire*, but I
> don't expect it to work afterwards!

  Of course.  I don't think anyone ever mentioned plastic packages though.

> Those interested can do their own research. If anyone finds positive
> evidence for use of X-rays to erase EPROMS as a matter of approved
> product use of production EPROMS, please please direct me to that
> evidence. A weaker assertion, you can do it anyway and not goof up the
> EPROM - with proof of lack of damage (tough to establish) - would be of
> interest, too. Thanks for your patience, if you read this far.

  Wow!  What's going on here, Herb?  I never said it was a production


Dave McGuire, AK4HZ
New Kensington, PA

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