HP15c - HELP


I have a "c" annunciator on the display and don't know what it means. It may be coincidental that the calculator works unpredictably also. What is it and how do I turn it off? I dont have a manual handy. Thanks



this annunciator means your HP15C is operating in Complex (numbers) mode.

To clear it and return to normal operation:

[g] [CF] ([5] key) [8]

It should disappear.

Best regards.

Luiz C. Vieira - Brazil


Listen to Luiz. Not only is he faster off the mark, he's also more accurate. Of course, you set and clear flags with the [g] prefix, not [f]. Didn't have the machine in front of me...

On the other hand, Mitch, if you really can't be bothered, why not send the 15C to me and be done with it? I'll certainly pay your shipping charges.... ;-) It'll save you a trip down to the railroad tracks.


Hello, Patrick;

I consider myself as playing in the best team: ours.

It was a matter of about 1 minute. And your answer called the attention to the one of three possible ways to set Complex mode ON; mine didn't.

Best regards fornm a "forumate".

Luiz C. Vieira - Brazil

(A curiosity of mine: what's the story behind the railroad tracks?)


Seems like people on one side of the tracks can afford an Hp or even better, lots of Hp's.

On the other (wrong) side of the tracks, one can only afford one Hp, or worse, have to use a Ti.


I think this was a reference to Norm's advice on how to repair a 32SII:


Time sweeps our sins away - into the Archives!


Hi, Ellis;

that was my first guess... A mention to Norm's post or a possible "name"/person confusion.

Best regards.

Luiz C. Vieira - Brazil


U guys are really skeptical of that advice
about using train tracks to repair stuff.

Listen, I have fixed clock radios, televisions,
and old modem boards using the same techniques.

I did it mostly when I was a teenager in high
school, but even nearing 40, I still occasionally
fix things by the same method.


-- To make stable or unchangeable.

Yeh, I can see how that would do it. ;-)


Ever heard of Dictionary.com ?


I've been using it ever since my dictionary got
buried underneath a landslide of old vinyl records
and dirty laundry.

"FIX" as a term comes up fine:


Pronunciation Key (fks)
v. fixed, fix·ing, fix·es
v. tr.

1. a.To place securely; make stable or firm: fixed the tent poles in the ground. See Synonyms at fasten.

1. b.To secure to another; attach: fixing the notice to the tracks.

2. a.To put into a stable or unalterable form: tried to fix the conversation in her memory.

2. b.To make nonvolatile or solid.

2. c.Biology. To kill and preserve (a specimen).

3. To direct steadily: fixed her eyes on the railroad ahead.

4.To capture or hold: The train engineer with the long beard fixed our attention.

5. a.To set or place definitely; establish: fixed her residence in a coastal village.

5. b.To determine with accuracy; ascertain: fixed the date of the repair of the calculator.

5. c.To agree on; "I will fix your calculator using that train track method".


The machine has gone into "Complex" mode wherein it performs operations with complex numbers. There are a number of reasons why it might do this, the most common being that you pressed: f I

To go back to normal calculation mode (Real mode), clear flag 8: f CF 8

Possibly Related Threads…
Thread Author Replies Views Last Post
  1984 HP15C rattles Footloose (Illinois) 4 1,910 10-15-2013, 09:43 PM
Last Post: BobVA
  HP15c continued fraction for Ln(Gamma) Tom Grydeland 0 1,111 09-30-2013, 05:48 AM
Last Post: Tom Grydeland
  HP15c LE emulator with unlimited number of activations Nick_S 23 6,120 01-24-2013, 03:59 PM
Last Post: Victor Quiros
  battery test for the HP15c Limited Edition Guido (Canada) 3 1,661 01-03-2013, 08:17 AM
Last Post: Jeff O.
  uRCL* on HP15C Csaba Tizedes (Hungary) 2 1,365 12-29-2012, 06:09 PM
Last Post: Luiz C. Vieira (Brazil)
  HP15C strange complex number behavior Mike W 5 2,000 09-11-2012, 04:36 PM
Last Post: Mike W
  HP15C Paul Averis ( Australia ) 1 1,149 06-18-2012, 03:33 AM
Last Post: Alexander Oestert
  HP15c LE - highest serial number over 23.000 Jose Gonzalez Divasson 1 1,204 05-16-2012, 03:19 AM
Last Post: Torsten
  HP15C LE Price Lowered by HP Namir 23 5,590 02-05-2012, 05:34 PM
Last Post: Andreas Grund
  HP15C LE Pause Operation not as expected Russell Dobson 13 3,740 02-03-2012, 05:43 PM
Last Post: Marcus von Cube, Germany

Forum Jump: