Early Continuous Memory Models

[bshoring]

(06-11-2015 09:38 PM)PANAMATIK Wrote:  

(06-11-2015 07:26 PM)bshoring Wrote:  Thanks all for your insights. I guess I was thinking there would only be seconds to maybe a minute to change batteries. I am impressed that a 35 year old device could hold its memory intact for over 5 minutes. Maybe the fact that I changed before the low battery indicator came on could be a factor as well.

HP-29C manual says

Quote:If it becomes necessary to replace the baltery pack, use only another Hewlett-Packard battery pack like the one shipped with your calculator. Continuous Memory requires that batteries be replaced as quickly as possible. Normally you have a minimum of 5 seconds to change the batteries. Leaving batteries out of the calculator for extended periods will result in loss of information in Continuous Memory.

Obviously the engineers were very conservative to avoid giving a promise that couldn't be kept.

The "Non Early Continuous Memory Models" HP-25E and HP-29E retains their "Continuous memory" for unlimited time without batteries.

Bernhard

Yes, they must have been very conservative, indeed. Would you ever consider selling whole units (or fully assembled HP-25E or P-29E) ? I'm not very good with fixing things.