"John Robertson" wrote in message
...
On 2017/04/03 9:59 AM, tom wrote:
wrote in message
...
The EPROMs in one of my machines are at least 32 years old. Reading
online about EPROMs it seems that maybe my old devices are nearing the
end of the life of the memory contents. So I'm thinking I should copy
or have copied the data in these old devices. Am I right?
Thanks,
Eric

Definitely make a copy. Then program a second copy of the EPROMS and swap
them in to confirm the copy. If the copies are good, erase and reprogram
the
originals and keep as a spare.

Also replace any memory backup batteries while you are there.

You will probably be dead before you need the copies.



EPROMs are quite stable in my experience, however backing up and using the
second set of EPROMs to run the product seems reasonable if a bit of
overkill. Make a copy, archive it off-site and keep your burner in a safe
place. I would simply use the originals until they gave me cause for
doubt.

Also - do not erase the originals, simply reprogram (refresh) them after
telling the programmer that the chips are not blank. EPROMs have a limited
number of erase/burn cycles so why knock one cycle off? I do find that a
number of originally good EPROMs (that had valid data) fail to reprogram
after being erased.

I burn many classic EPROMs (2716s and up) and PROMs a month, so have some
experience in this matter.

John :-#)#

--

I would agree with you on that except there are some programmers that will
not permit you to program an EPROM that is not erased and does not have the
option.

So I was just keeping it generic. Also burning a second copy allows you to
confirm a good copy from the originals. Plus most of them are cheap.