Bit Rot?

From: Dwight K. Elvey <dwight.elvey_at_amd.com>
Date: Mon Apr 5 16:57:25 2004

>From: "Scott Stevens" <sastevens_at_earthlink.net>
>
>On Mon, 5 Apr 2004 10:35:44 -0700 (PDT)
>Vintage Computer Festival <vcf_at_siconic.com> wrote:
>
>>
>> Is there a good description of the various forms of ROM/PROM/EPROM bit
rot
>> phenomena on the web somewhere? Or could someone provide a good
>> description?
>>
>> I know in the case of EPROMs the charge will eventually "leak". And
with
>> masked ROMs and PROMs the "fuse" can actual re-grow and turn a 0 into
a 1.
>>
>> We've discussed it briefly before. More detailed information would be
>> appreciated. Thanks!
>>
>
>Masked ROMs don't really have a 'fuse' to regrow. If Masked ROM parts
start degrading, just about any other silicon is going to start having
the same problems.

Hi
 No, mask ROM are not the same as PROMs that have fuses. These
only fail when a transistor fails. There are no fuses blown
in a mask ROM. There are wires that are there or not there
from the begining. Nothing to regrow.

>
>I'd like a reference to good information on this topic, as well. We
should all be backing up our EPROMs.

 The EPROMs on my SIM-4 still have there original data ( 1702A's ).
I've made both EPROM and on disk copies. These are about '73 someplace.
Not to bad for part that were only suppose to hold for 10 years.

>
>An interesting unrelated side topic is the phenomenon of the Light
Emitting EPROM. Has anybody else ever wired one of these into a circuit?
 (you do it by plugging the EPROM into the socket backwards)

 They only emit light for a few minutes this way. But yes, there
is a nice orange low.


 All ROMs can suffer from the effects of EM ( electro-migration ).
They can suffer from impurity ions as well. Copper and
sodium are real bad.
Dwight
Received on Mon Apr 05 2004 - 16:57:25 BST