HP 11c


Please help! – I’m away from the office and feeling naked without the manual for my 11c Mysteriously, my “period” has set itself to a “comma” – can someone kindly explain how to turn it back.

Many thanks in anticipation.



AFAIR press and hold the period key *before* pressing the ON key. After pressing ON release the period key. This should toggle between period and comma.



Thanks Raymond - worked a treat!


He complains!

I have no manual at all for my 11C.

Since I'm used to the 28S and the 48SX, I never have really known how to properly operate an 11C.


Such a terrible fate for a wonderful machine!

I think you have an obligation to sell your 11C to me for a very small amount of money. Maybe then the spirits of HP engineers gone by will forgive you your sacrilege!

(P.S. Alternatively, why not buy the museum's DVD/CDs which has all the manuals you could ever want??)




Actually, I have a manual for the 15C. It's a "one of these days" thing that I have to see how well the 15C manual works for the 11C.

The first programmable calculator I ever bought was a Sharp that served well. I mislaid it and bought a little sort of programmable pocket whazzit as a fill in. One of the guys in the lab had an HP 28S and that was it. Bought one, and later an HP 48SX so the 28 & 48 series became my thing.

I'm considering putting my extra calculators on eBay. they include the 11C, a 12C, a 32SII, possibly a 27, a 48GX, possibly a 48G+, and outside of HP, a TI 83 and a Casio 7000g.


Hi, unspellable;

I own one of each: HP11C and HP15C. Using the HP11C with an HP15C Owner's Hanbook "in hands" is not hard at all, but some resources described in the HP15C's manual are not applicable to the HP11C, of course. Except for the four extra major enhancements found in the HP15C, being Complex Numbers handling, Matrices arithmetic, numerical SOLVE and Integration, both share the following equivalent points:

- math resources for real numbers, including trigs, logs and hypebolics

- stastics functions and ressources are the same for both, but there is a difference related to statistics registers location: in the HP15C the block is defined between R2 and R7, and in the HP11C it is located in registers R0 to R5;

Some of the differences are:

- memory handling, organization and availability: the HP15C has the equivalent to 67 registers (469 bytes) against 21 registers plus 63 program steps (210 bytes) in the HP11C available for the user

- register arithmetic in the HP11C is limited to [STO] operation [R0 to R9 and RI]; the HP15C goes far beyond this

- the hP15C allows RCL RAN# (Randon pseudo-generator seed) and the HP11C does not

- programming resources differ in three aspects:

relational operators - the HP15C has twelve and need TEST n function to access ten of them, while only ten are available in the HP11C

[LBL][.] n, [GTO][.] n and [GSB][.] n are not available in the HP11C

flags - the HP11C has general-purpose flags 0 and 1, while the HP15C has general-purpose flags 0 to 7; flags 8 and 9 in the HP15C have specifc meaning and application;

- [SCI] and [ENG] in the HP11C are not defined for eight and nine digits

I feel as if I'm missing something, but these are the raw differences and equivalences. Reading HP15C Owner's Handbook when using the HP11C demands taking these facts into account.

My 2¢.

Luiz (Brazil)


Luiz posted: "[SCI] and [ENG] in the HP11C are not defined for eight and nine digits"

Indeed they are, IIRC, but only if executed from the keyboard. SCI 8, SCI 9, ENG 8, and ENG 9 cannot be
included as program lines because of the limit on just
256 different keycodes. The same happens with the HP-34C
(where only 1 keycode is unused out of 256 possible).

"I feel as if I'm missing something"

Yes, a number of things, among them:

  • ISG and DSE only work with the I register in the HP-11C, while the HP-15C versions can work with any register, directly or indirectly, including individual matrix elements

  • in the HP-11C, you must use GTO . nnn to go to step nnn while in program mode, but as LBL . n is legal in the HP-15C you must use GTO CHS nnn instead.

  • in the HP-11C, the x<> swap instruction can only work
    with arbitrary registers indirectly, while on the HP-15C, you can swap arbitrary registers directly (i.e: x<>3 or x<>.2), indirectly, or even individual matrix elements.

  • the HP-11C allows for three levels of subroutine nesting, while the HP-15C allows for seven levels.

there are other minor differences as well.

Best regards from V.

Edited: 10 July 2003, 10:35 a.m.


One of those minor differences I just discovered is that you cannot recall the current random number. On the 15C, the sequence [RCL][f][RAN#] gets you the random number returned by the last call to [f][RAN#]. You can do this as often as you like, always getting the same number back. On the 11C, you can store into the random number register (i.e., set the seed), but not recall from it.


Best regards from V.

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