[Coco] EPROM question

[Mike Pepe]

jdaggett at gate.net wrote:
> On 7 Feb 2008 at 1:31, Joef6809 wrote:
> 
>> Interesting, The window has a sticky label over it as most do. I'll
>> probably take a dump of it just in case anyway. Its not like its
>> valuable or anything but its part of the collection now so it need to
>> be taken care of. BTW are you saying alpha particals will also erase
>> an EPROM? -----
> 
> _______________________________
> 
> Not alpha particles but UV light in the 235 nM range or what is often refered to as UVC light 
> will erase the UVEprom.  It is the programming voltage that causes charge to bore through 
> the oxide layer in a tunnelling mode known as the Fowler-Nordheim tunneling process. This 
> allows the charge to drain off the floating gate transistor and thus result in the bit to read 
> "zero". UV light restores the oxide boring hole and the charge and the bit will read a logic 
> "one". You can over erase an UV EPROM also with to much UVC exposure. This can  yield 
> in the bit not properly reprogrmming. 
> 
> --
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco

Yes- alpha particles won't be able to penetrate the quartz window. They 
won't make it through a piece of paper!