[vcf-midatlantic] Good source for eproms?

Herb Johnson hjohnson at retrotechnology.info
Mon May 30 12:45:24 EDT 2016

Dave Mc Guire:

>   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.

Herb and response:

>> 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
> process!

I'll be brief and answer your question, Dave - the issue is not what's 
possible, it's what is practical and productive. I can't prove a 
negative, period. And you can't prove the positive when you can keep 
saying "I could do this if I wanna, I just don't wanna".

Those interested in rigorous argument, can look up "proving a negative".

So "possible" comes down to "I can put a chip under an X-ray - so I 
win". I say, "you win a faulty chip, most likely". And that amounts to 
my agreement with your proposition - as brief as I can be.

What's also going on, which is interesting to me, is the early history 
of EPROMS, which noted X-rays could erase devices, but would damage the 
devices. But UV radiation would erase without damage. It may be - if one 
checks the history of developing electric-charge programmed EPROMS - 
that their erasure and reprogram-ability was a happy accident, not an 
initial research goal. Then it became a product feature.

The  way I look at that question of history, goes like this. Many 21st 
century people, look back at vintage computing, and ask questions like 
"who invented erasable reusable EPROMs?", as though that was some design 
goal, something that everyone wanted and was "racing" to achieve, etc. 
I'm saying, like many other 1970's computing developments, it could have 
been a consequence, not a goal.

I appreciate most don't care about formal argument methods, or early 
origins of computing devices. Sorry for the prolonged discussion. But 
the myth of X-ray erasure (of unwindowed devices) I consider busted as 
"impractical, likely destructive" based on early-development evidence. 
The end.


Herbert R. Johnson,  New Jersey USA
http://www.retrotechnology.com OR .net
preservation of 1970's computing
email: hjohnson AAT retrotechnology DOTT com
alternate: herbjohnson ATT retrotechnology DOTT info

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