HP-71B reset?


I have just purchased an old HP-71B.
I removed the only ROM in the machine (an old British Social Welfare ROM used with a Bar Code Wand) and powered up via the AC adaptor - all is well so far - it worked.

I then tried batteries - however all I get is the ">" prompt and the RUN message and the "f" symbol in the display - the whole system seems to have frozen.

Can anybody tell me how to "reset" the HP-71B?

It seems dead to all key input now - just that above display when I apply any power.




Although I have used a 71B for 17 years, I have not encountered the problem of a frozen display. So this suggestion is offered not from direct experience, but from referring to the owner's manual (p.274), which I gather you do not have. The manual says:

1)Unplug the AC adapter, remove batteries, and remove all modules.
2)Press and hold down the ON key for about 30 seconds to discharge the circuits.
3)Install batteries or connect the AC adapter, and press ON. The message "Memory Lost" should be in the display. Pressing any key should display the BASIC prompt and Replace cursor.

Good luck!!



hi Tom

Thanks for your help
Tried this with no luck - kind of curious!
It seems like it has crashed and a backup (if it has one) battery of some sort is maintaining the crashed state.

It was working until I placed the batteries in it.

Now frozen - maybe for ever - I hope not!


PS. No I have no manuals!



Oh, dear. Perhaps someone else will have a remedy. About all I can add is that there is no back-up battery, but it is possible that the capacitance of the circuits needs more than the 30 seconds to discharge. Maybe the best thing to do is to do nothing for awhile, letting it sit on the shelf for a day or so without its batteries. One way or another, I think you will win in the end.

All the best,



I don't know how long the 71B can retain its memory without batteries, but I have some 41CX machines that last over a month. Most 41xx machines last well over a week. The manuals say only a few minutes.


Hold down the '\' key while turning it on.

Then you can enter 1, 2 or 3 for full reset.

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