[vcf-midatlantic] Good source for eproms?

Dave McGuire mcguire at neurotica.com
Fri May 27 13:37:47 EDT 2016

  FYI, at least one "package inspection" X-ray machine is identical,
except for the sticker on the front, to a model marketed to assembly
firms for weld inspection and PCB inspection.  Mine is such a machine.
Needless to say it was a very good deal. =)

  These are awfully, awfully heavy though...much more so than their size
would suggest, due to all the lead.  Be careful.


On 05/27/2016 01:35 PM, Jason Perkins via vcf-midatlantic wrote:
> There's a package inspection X-Ray machine at a recycler near me in
> VA. It works... and I bet they would take $50 for it.
> On Fri, May 27, 2016 at 1:32 PM, Chris Fala via vcf-midatlantic
> <vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
>> Oh, hey, somebody need an X-ray machine? Just see Dave! LOL
>> On Fri, May 27, 2016 at 11:46 AM, Dave McGuire via vcf-midatlantic <
>> vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
>>> 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
>>> --
>>> Dave McGuire, AK4HZ
>>> New Kensington, PA

Dave McGuire, AK4HZ
New Kensington, PA

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