41CX Features.

Ok, a dumb question, but I'm curious none. I saw this on RSkey.org

"The CX model of the HP-41 line was the most advanced, offering extra built-in memory, timer functions, and other features."

Anyone care to describe to me what those "other features" are in specifics? I'd kind of like to know what my 41C is missing.

You know where this is going... I gotta get another calculator. :)





Ray --

Please do take a look at the 41C* link on the MoHPC site as Raymond pointed out, as well as the "Compare Features" link on the home page -- there is much useful, well-presented info. The differences are fairly subtle, but this should cover most of them:

  • Maximum 319 (64*5-1) registers of RAM, instead of only 63 (64*1-1)
  • Built-in contents of Extended Functions Module ROM and other CX-specific Extended Functions
  • Built-in contents of Time Module ROM and other CX-specific Time Functions
  • Text Editor for Extended Memory text files
  • More types of catalog listings, including keycode assignments
  • Desired catalog listing can be selected for display (instead of waiting for it to come around in sequence)
  • Program catalog listings show size of program as well as the beginning external label (name).

Since the CX was made from 1983-89, and HP-41 models shifted to the Halfnut design in 1985, most 41CX's are Halfnuts -- unlike the 41C (1979-85?), which are (all?) of the older Fullnut design.

Fullnuts have better-designed displays and are much more repairable, but are more complicated and tend to require
more service.

-- Karl S.


Hello Karl, guys;

after wondering about the same question (Are there any HP41C build as halfnuts?) and exposing this subject sometime ago, I read that there were indeed some HP41C build as halfnuts mostly for replacement purposes (maybe some other purpose?). It seems to me it's a rare "piece", a true collectible.

I was given (a very good friend) an HP41CV halfnut that's faulty: it shows only the first 1/5 memory space, as it happens in an HP41C. It's memory "chips" (the hybrid under the LCD) are not reliable as well, because they tend to cnage their contents from time to time, i.e., programs stored in this calculator have their codes changed and barely work. I had an old, not-operative HP41C fullnut and I found out that the cases may be exchanged with a bit of extra work: after removing the keyboard, both full- and halfnut main PCB's fit each other's keyboard cases, but some plastic posts (rivets) must be removed (about eight, if I am not wrong). Now I have a fake/faulty HP41C halfnut! And that's neat!

My 2ยข.

Luiz (Brazil)

Edited: 29 Mar 2004, 5:42 a.m.


Also see:



The HP41 service manual lists (and gives a parts catalogue and schematics for) a halfnut HP41C. The difference between it and the halfnut CV (at the component level) is the display driver hybrid (it's not just a link that you have to swap). But I am told that these machines were never on general sale, only used as service replacements.

For a real rarity, how about an HP41 test calculator. I have never seen a genuine one. I have one, but it's home-made...


I was doing my reasearch on rskey.org and didn't think to check the musuem that thouroughly. Appologies, and I appreciate the link.

Those things happen in the late evening.


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