Buggy 11C


I have an 11C with a bug. When you enter 0.0xxx then backspace over all the digits & press enter, 1.00 was entered rather than 0.00. Does this hamper the functionality of the calculator? Thanks in advance for any help.


Hi, Mitch;

I remember I saw something about it at Craig Finset's database sometime ago. I searched there and I found this:


From Stephen J Thomas <sjthomas@bcfreenet.seflin.lib.fl.us>
HP did acknowlege a bug in the 11C, but never released a ROM version
which corrected this (I don't know why this popped into my brain last
nite after lying dormant for several years).

If you are entering a number with a decimal point, and then use the
back-arrow key to erase any (and all) digits to the right of the
decimal point AND erase the decimal point, the magnitude of the
integer portion of the number will be incremented by 1 when the ENTER
key is pressed.

For example,

1 1 . <- ENTER

should put 11 in the X-register, but 12 is entered instead.

Another example,

2 . 3 4 CHS <- <- <- ENTER

will put -3 in the X-register instead of -2.

I'm not sure if this also occurs when a function key -- such as [+] --
is pressed rather than [ENTER], or if this occurs on any other
Voyager-series models.


The mentioned bugs arent present by S/N 2750A15169.

Hope this helps.

Luiz (Brazil)

Edited: 13 July 2003, 11:32 p.m.


Thank you Luiz


My 11C, USA made, but unfortunately the S/N has been erased, does not have this bug...


My 11c (2323B13010) doesn't have the bug.


Neither of my HP-11C's exibit this bug--drat!


Mark Hardman


My 11C is 2206A00034 and it has this bug.

I have also tried this in the 15C emulator for PocketPC and it does not have this bug, but it behaves differently to my 11C when deleting the decimal point.

The 11C deletes the decimal point as if it was a seperate character (as expected), but the 15C emulator deletes bothe the decimal point and the zero before it together.

Does a real 15C do this?

Try it by typing 2 or 3 zeroes before the decimal point 000.123 then delete backwards and see if the decimal point takes the preceding zero with it.


A real HP-15C deletes the decimal point independent of the number that precedes it. Same behavior as the HP-11C. I'd expect that the program you are using on your Palm is an HP-15C simulator and not an emulator.

Mark Hardman

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