From: Bob Blick <bobblick@outlook.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Mon, 22 Mar 2021 21:17:02 -0700
Subject: Re: [EE]: 27xx64 EPROM Programmer
Thread-Topic: [EE]: 27xx64 EPROM Programmer
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Regarding unapproved methods of erasing EPROMs, I have permanently damaged =
some using both sunlight and germicidal lamps. I attributed it to overdosin=
g at an incorrect wavelength, and since then have always used an approved l=
amp and never had a problem. EPROMs seemed more fussy about the correct wav=
elength than photoresist :-)

Friendly regards, Bob=20

________________________________________
From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> on behalf of Russel=
lMc=20
Sent: Monday, March 22, 2021 6:51 PM
To: Microcontroller discussion list - Public.
Subject: Re: [EE]: 27xx64 EPROM Programmer

On Tue, 23 Mar 2021 at 13:41, Brent Brown wrote:

> ... I see that I have some second hand 27C64's in a drawer, hopefully
> blank
> else I'd have to dig a little deeper to find my UV eraser.
>
> A few hours of good NZ sunlight will erase UV EPROMS.
Long ago we used to erase a significant number this was - through window
glass ! - with good results.
EPROMs MUST be on a conductive surface or in electrostatic- protective
foam.
Erasure on a nice dry warm brick window-ledge cost us a number of
fatalities until we realised.

Memory fades (around 1980) but if you erase until apparently blank and then
double this time it should suffice.
Time used varies but it got so we could erase them reliably without
checking based on "sunnyness" - well under a day.
I have a very capable UV germicidal source for large volumes.
Works short term wonders on eyes if allowed - spectacles will apparently
refract the light at a steep angle and allow eye burn even when not looking
directly at the source!
Ask my wife how I know ! :-( :-).
It also possibly saved the sight in one of her eyes due to unrelated
pending retinal detachment being detected when UV burn was being treated.


             Russell

--=20
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