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HP-39GII: Will it become a desired collectible?
01-18-2015, 03:59 PM
Post: #45
RE: HP-39GII: Will it become a desired collectible?
(01-17-2015 09:27 PM)jebem Wrote:  Sorry about your calculator fault.
(01-18-2015 01:00 AM)Jim Horn Wrote:  Collectors here have often gone to great lengths to get older HP machines that couldn't do a tiny fraction of what the 39gII does....Meanwhile, it serves me just fine.

Hi, Jose and Jim! Glad to hear that your devices operate well. Perhaps, my following notes will be useful to somebody.

1. During power 39gii on, there is an information read process from flash into RAM, and short-time rise of current up to 100...150 mA in a supply circuit is watched. A voltage of run out batteries falls to negative-going input threshold (Vit). The supervisory circuit monitors Vdd (or treshold voltage of reset) and keeps STMP-reset active as long as Vdd remains below the treshold voltage Vit. In this case calc. won`t turn on even if in the normal conditions batteries could work still very long. (Now it clear for me what for they set four batt. in parallel in 39gii). IMO, bad circuitry solution.
2. Periodically you should switch on and turn off this calculator during the long operation with it to avoid loss of results. In case of fatal hangup your new changes in data won`t remain. 39gii saves into flash the last status of RAM only after normal switch-off, not after abnormal extraction of batteries.
At least, my device always behaved quite so.
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RE: HP-39GII: Will it become a desired collectible? - Hlib - 01-18-2015 03:59 PM

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