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Inserting an 82181A EM, losing existing contents
09-21-2016, 12:32 AM
Post: #1
Inserting an 82181A EM, losing existing contents
Question: how likely is it to lose existing extended memory/
main memory contents when inserting a new extended memory
Module? Hp41cx ...

Thanks
Todd
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09-21-2016, 02:14 AM
Post: #2
RE: Inserting an 82181A EM, losing existing contents
I got a double extended memory module several years ago on eBay, plugged it into my 41cx, and the only effect was that EMROOM suddenly jumped way up. I did not lose anything.

http://WilsonMinesCo.com  (Lots of HP-41 links at the bottom of the links page, at http://wilsonminesco.com/links.html#hp41 )
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09-21-2016, 02:36 AM
Post: #3
RE: Inserting an 82181A EM, losing existing contents
(09-21-2016 12:32 AM)twdeckard Wrote:  Question: how likely is it to lose existing extended memory/
main memory contents when inserting a new extended memory
Module? Hp41cx ...

Thanks
Todd

I would say it is unlikely.

The extended memory module appears in the memory map depending on the port you inserted it in. It will either take the 2XX or 3XX page depending on this. If you have two X-memory modules, plug one into port 1 or 3 and the other in 2 or 4. In other words, not on top of each other.

When the module is available, it will be linked into the rest of extended memory. It happens when it finds it, not immediately when you turn it on.

If there are no shaky connections, you should not lose existing memory provided you inserted them correctly. Having said that, I know from experience that the HP-41 is a bit trigger happy to clear its memory as soon as it finds any small motivation to do so. It is always a good reason to keep backups, but this has little to do with inserting a module, which tends to be fairly safe.
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09-24-2016, 12:21 AM
Post: #4
RE: Inserting an 82181A EM, losing existing contents
Inserted the EM wo incident. Appreciate the comments. I always have hard copy backups but if it had been likely to lose the existing content I would have put the module in my "traveling violin" instead.
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