Michael A. Terrell wrote in message
m...

Gareth Magennis wrote:

"William Sommerwerck" wrote in message
...

I'm not sure what your question is. Or if you have a question.

3V lithium coin cells are commonly used to back up memory, including 5V
systems. They can last for years; I've never seen two used to add
capacity.

I've never seen 2 cells used as memory backup either.
My initial thoughts were that the two cells are wired in an OR
configuration, meaning designed in redundancy rather than a need for an
increase in capacity.
Should one cell fail, the other will keep the memory intact.

Is this equipment from the Space Shuttle by any chance?


We had to use CapStore RAM in the equipment we built for NASA. No
lithium batteries were allowed into space.

Maybe they wanted to be able to replace the batteries one at a time,
without losing what was stored in the RAM.


For the same reason that Boeing should have stopped them being incorporated
on their recent product fiasco?

Both batteries are tanged and would require desoldering/soldering to replace
either. If designed to allow one failure then I'd expect at least for them
to be from different batches if not different suppliers, both same make and
batch number here