HP27S "Machine Reset" Message


Hope someone out there can help. I changed batteries in my 27S Calculator and I cannot get rid of the "Machine Reset" message. I have numerous formulas programed in the 27S that I use on a regular bases. Hope you can help solve this. I have tried the procedure published in the 27S manual. Dosen't seem to be working. Any other ideas?

Thank you kindly
Dave Conley



This message, "Machine Reset", is intended to be harmless. In the 42S (also Saturn-based) it means nothing is lost (programs and variables). I do not know the 27S, but I don´t believe it would be different. At least in the 42S, simply pressing [ON] key restores operating condition.


(BTW, what procedure in the manual you're referring to?)


Thank you also for your input. Tried that didn't work. I removed the batteries again but the same message "Machine Reset" pops up.
Any other ideas?

Thank you kindly




I got my HP42S in hands and forced a Machine Reset condition (in the 27S: [CLR]+[e^x} keys pressed together). It goes out of the condition after a single [ON]-key press ([CLR]-key, in the 27S). Have you tried to force this condition, say, [CLR]+[e^x] keys together?

If you want to try, tell us the results, please.



Nope No luck! The 27s has blue function "select" keys. I held down [CLR]+e^x. The calculator is capable of normal basic math. But each time I go to "function" [solve] to call up my equations the "machine reset" text pops up.

I also ran a self test according to the manual. The test is good everything is working.

Thank you kindly



Tough lesson. I removed the batteries long enough to erase everything. 27S is working fine. Next time I'll be smart enough to record critical info. prior to battery changes.

Thank you for you input

Dave Conley


If you don't have anything important in memory, you might try doing a memory clear - OFF & 1/X and SQR all three keys at the same time. If that doesn't work, you can try taking out the batteries and shorting the contacts in the battery compartment together with a paper clip for a few seconds while turning the calculator on.



Thank you for your input. I was hoping to keep my formulas as I use them for research. Any other ideas?


Just guessing, did you set the date and time (and also an alarm time) for the internal clock *after* changing the batteries? I suspect there may be some kind of alarm register or something similar, it may be corrupted and could be a cause of unusual behavior like the one you described. Again, it is only a guess, but you may try before clearing all memory... it seems there is nothing to lose.


Good suggestion. I just tried that no luck.
It wouldn't be a big deal to erase all and start over except I did not write the formulas down over the years.

Thank you so much for your suggestion



Tough lesson. I just removed the batteries long enough to erase everything. Lost all formulas and data. I appreciate your help. Hopefully I'll learn from this to record critical information before battery changes.

Thank you for you input

Dave Conley


Tough lesson. I removed the batteries long enough to erase all formulas and data. Next time I'll record critical info. prior to battery change.

Thank you for your input


Dave Conley

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