HP-41C serial number



Today I got an HP-41C.

1) The serial number is "1720A01115". How is this possible? 17+1960=1977, two years before release date?
The Earliest Serial Numbers published in the museum register a "1926...".

2) The keys are more "square shaped" than the keys on my HP-41CV or 41CX. I suppose this is common to all HP-41C. or it doesn´t?



You're correct. A S/N of 1720 would date from the time of the HP-67, not the 41c.

Either...the S/N has been altered or you've somehow misread it. :-)

My early model has a S/N of 1932A...

Try typing 49 STO 01
Then Gold SF Gold 01

What happens on the display?


The result of the sequence of keys that you told is "NONEXISTENT". What that it means?

I just write a html page with photos in my site, where you can see the S/N:

The serial number seems to be "hand made", instead of "typed" as the ones in my other calculators.



Hi. It does look like a previous owner etched the S/N onto the back of the calculator. Brings up an interesting question...why wasn't there a S/N there already? Doesn't seem like it was there to me, unless the person who etched the S/N onto the 41c did it right over the original.

The series of key presses I gave you allows a very early 41c with a bug called "bug 3" to set the system flag for the low battery indicator. This is not normally possible on a 41c, but these early ones could do it in the way I described.

Good looking 41c, regardless! :-)


Nice photos. Serial number appearance is quite different from my units (2452S41134, 2133B94184).
By the way - it looks like the plastic frame that goes between the two halves of the case is mounted upside down.
Saudacoes do Brasil.


Renato you were right! The plastic frame were mounted upside down. I opened the calc, inverted the frame, and mounted all together again. Now it looks as supposed.
You are a very good observer.



my c also has the tall, more box-like keys.


The unit is a warranty repair replaement unit. These had blank serial number areas that were filled in by hand with the original unit number. Obviously somebody copied the old number incorrectly.


I have a low key 41C that has a serial number somewhat like that too. It looks like it was hand heat stamped.


Is the serial number.

My tall key 41C that I bought originaly has the serial number.


So it is somewhat obvious by the serial number sequence and the keys that the first one is a serviced unit.



I also have a 41C with serial number beginning with
20, and the golden balls in the charger tunnel.
I know for a fact that this
is a reparied unit, since I am the original owner


Possibly Related Threads...
Thread Author Replies Views Last Post
  DIY HP 30b WP 34s serial flash/programming cable Richard Wahl 2 693 12-04-2013, 11:14 AM
Last Post: Barry Mead
  A fast Bernoulli Number method for the HP Prime Namir 16 1,549 11-22-2013, 04:46 PM
Last Post: Namir
  [HP Prime] Calculating Prandtl Number with Units (bug found in USIMPLIFY) Timothy Roche 1 398 11-13-2013, 04:07 PM
Last Post: cyrille de Brébisson
  HP Prime: Converting number to Sci notation and back BruceTTT 1 385 11-12-2013, 02:11 AM
Last Post: Phil Wipf
  HP PRIME: Fixed 4 number format 0.001000 Joseph Ec 18 1,774 11-07-2013, 11:51 AM
Last Post: Geoff Quickfall
  HP Prime: Number of external Variables Davi Ribeiro de Oliveira 0 317 11-01-2013, 08:10 PM
Last Post: Davi Ribeiro de Oliveira
  HP PRIME: command to read the SERIAL ? Joseph Ec 9 1,792 11-01-2013, 12:43 AM
Last Post: Joe Horn
  Oldest HP 41c aka earliest Serial Number Gene Wright 23 1,909 09-05-2013, 03:45 AM
Last Post: Geoff Quickfall
  HP 50G serial port programming Chris Smith 2 465 06-15-2013, 02:47 PM
Last Post: Chris Smith
  HP 85 Serial Interface; INPUT Example? inaki 1 390 06-12-2013, 11:09 PM
Last Post: Paul Berger (Canada)

Forum Jump: