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I have found that my HP 30b will not stay on the settings that I choose in the mode menu. I prefer RPN. Oddly, the only settings that undesirably change is RPN will change to chain, and radian will go to degrees. Is there a way to keep the mode settings from changing?
That's strange; those modes are supposed to persist. If they don't, I'd suspect it's either operator error (e.g. not changing the modes correctly) or a hardware problem (I'd guess either a low battery or a flaky connection somewhere, such as the battery contacts).

Let's rule out operator error: After pressing MODE, then pressing either arrow key 5 times to get to the RPN option, then pressing INPUT to rotate RPN into view, you should press the ON key to exit that menu and carve your RPN choice into stone. If you're doing that, and you still lose RPN mode, try changing the battery and/or cleaning the battery terminals.

Needless to say, resetting memory clears RPN mode. But I won't mention that, because it's needless to say.

EDIT: Oh! It just struck me! Do you have a program in memory which changes the modes? <Sorry, I should have thought of that first.>
Hi Joe,

I am not running the program or two that is in the calculator. I just changed the batteries, just in case. I rotated the RPN choice into view again, just in case, after putting in the new batteries. Hopefully, this will solve the problem.

Do you know where to find a bug listing for this calculator? I remember seeing some comments on the old forum from accounting class professors that referred to some bugs (that to them, was a deal breaker in recommending the calculator to students). I have not encountered bugs...did encounter a bad error in a tutorial segment that HP had on the web...the calculator was correct, tutorial incorrect! I do not use the 30b for programming as it is rather cumbersome to do so, especially if I wished to utilize a function that required figuring out how many inputs or down arrows were necessary to choose the function in question!

The HP 30b is a handy calculator, and is one of the last to give RPN as an option.
My HP20B behaves like your HP30b. I set the Fix mode to 11 digits and when I turn on the calculator, the setting is lost and starts again with Fix=2. The same for the RPN/CHAIN/ALGEBRAIC mode.

I have not tried to change batteries as no annunciator of low battery appeared.
Hmmm... Does anybody know if the 20b and/or 30b are known to misbehave due to low power BEFORE the low-battery annunciator comes on? Losing settings like this should not happen.
I have exactly the same issue with my 30B, changed setting to Fix = 11 and RPN mode and it will not stay with that mode.

I am wondering if it is the issue with this 30b machine or simply battery issue.

You say the settings get lost. Do other things get lost (programs, currently displayed stuff on the screen)?

With all HP ARM based calculators, my first suspicion is the battery.

Please use a good brand from a reputable supplier. Cheap ones from e.g. eBay will not do.

Coupling the ARM processor design with coin cells was not a good decision. These ARM based calculators use current in high pulses which coin cells are not designed for (they have a high internal resistance compared to e.g. AAA cells). The battery low warning is not reliable on these calculators either.
I was not saving any programs or data in the unit, just was surprised on a number of occasions to discover, when grabbing it for calculations, that it had gone to chain and degrees. Since putting new batteries in, it has not changed settings yet...
the problem is now solved.
All you need to do is take out both CR2032 batteries, waited 10 second then install them back, turn on the 20b/30b machine, and press "RESET" button for 3-5 seconds.

My RPN MODE and FIX setting no longer reset to default anymore.
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