Nonvolatile RAM on single board computers

From: Scott Stevens <>
Date: Thu May 20 22:41:48 2004

On Tue, 18 May 2004 20:05:02 -0700 (PDT)
SHAUN RIPLEY <> wrote:

> I have a SBC with nonvolatile RAM on it. There are
> DRAM and EPROM too. I guess the nonvolatile RAM might
> be used to hold some important parameters while EPROM
> is used to hold program.
> Since nonvolatile RAM has limited life, I wonder how
> you guys deal with nonvolatile RAM in your old
> computers. Reading out the content with a EPROM
> programmer is a solution that jumps into my mind.
> "Burn" a new nonvolatile RAM and wait for another 10
> years? It seems a boring work...
> vax, 3900
If you're careful (and preferrably can back up the contents of the
module first) you can sometimes dremel into the top of the module in
such a way that you can tack on an exteral battery. I wouldn't advise
it as a method of 'preserving' the current contents, as it would be very
likely to be blown during a battery replacement, but it's a reasonable
way to continue to use the module. There's a classic reference on how
to do this with SparcStation NVRAM modules, a conversion I do to almost
every old Sparc box I restore.

I'm not sure how to 'read out' the contents since I've never tried, but
they're often the same SRAM/EPROM footprint. Anybody tried reading the
contents with said EPROM programmer?

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Received on Thu May 20 2004 - 22:41:48 BST

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