Hi!

I'm just wondering when the production of the HP41CX Halfnut started. I just got a Halfnut as far as I can determine without opening by its rounded display for which the contrast can be changed. The back looks for me like of a HP41C/CV where the ALPHA keyboard is shown (the "true" 41CX shows the display of the Edit menu).
The serial number shows 2339S41xxx, and for my taste 1983 was just the introduction of the Fullnut. Concluding, I suspect that the calculator was "refurbished" with a back of a 41C/CV.

Has somebody a clue about this finding? Could that engine I have be an original despite of that back?

Kind regards

I don't know what you mean when you write: "the ALPHA keyboard is shown (the "true" 41CX shows the display of the Edit menu)".

That is an incorrect assertion.

I have the HP-41CX that I bought new in early 1984 (2403Sxxxxx). Its back shows the keyboard ALPHA assignments. Mine is very definitely a "true" HP-41CX.

I believe you have a machine that started out as an HP-41CX fullnut, then was subsequently HP-repaired with halfnut internals.

According to and article entitled "HALFNUT -- AN INTERNALLY IMPROVED HP-41C,CV,CX" by Richard Nelson and Jeremy Smith in the CHHU Chronicle V2N4 (Jul/Aug '85):

"Halfnut is a code name given to the engineering effort of redesigning the HP-41C, HP-41CV, and HP-41CX to improve its manufacturability and reliability. The code name is a hold over from another engineering project started in the summer of 1983 to investigate a product similar to the HP-41, but only have half the number of ports. Since the four-port HP-41 was code named "Coconut," it was natural to call a two-port version "Halfnut." There are stories around that say Halfnut got its name from a goal to reduce the IC count by half, or to cut the manufacturing cost by half, etc.. I don't know how the older product variation project turned into a manufacturing-improvement project, but certain secrets of HP's internal operation are never known."

It says coconuts could get replaced with halfnuts in the repair service, but HP did not make any halfnut announcements.

So again, work on it started sometime after the project that started in the summer of '83 got changed, and they got it to market in '85 and stopped selling coconuts at that time. There never was a "fullnut."

Mike,



I'm sorry about the somewhat imprecise description of the 41CX's back.

What I refer to as "Edit label" is printed in white with most remarkable changes on the row where the shift key is.

There shows "|-, INSERT, GTO, REC" as shifted assignments of the "K, L, M, SST" keys.

In contrast, on the 41C/CV the print color was orange with "APPEND, ASTO, ARCL, BST" on the shifted keys of the shift-key row.





Gart,



you are correct, the designation "Fullnut" never was an official designation of the early HP41CX.

According to a list "All of HP’s Calculators – In “reversed time” Order" by "Richard J. Nelson, Jake Schwartz,

& Wlodekz Mier-Jedrezjowicz" which (re-)appeared in the HP Calculators Newsletter of Aug 2010 (HP Solve #20 Page 23-24)

the designation of the HP41CX was "Honeynut" and of the HP41C was "Coconut".

The designation "Fullnut" was a logical deduction; if there was a "Halfnut" there should be also a "Fullnut".

And it appears to be a pretty solution to make the destinction between both versions of the HP41CX.





The explanation that an HP41 was replaced by the customer service with a new model seems to be plausible.

However, I wonder whether only the top has been changed in such a procedure leaving the back as it was before,

so the customer would have a repaired calculator with the serial number of the machine he sent to HP.





By the way, the weight of both calculators (without batteries) differ with about 12% more for the Fullnut:

Fullnut: 149g (5.256 ounces)

Halfnut: 133g (4.691 ounces)

My apologies, Frido, for my ignorance of that distinction between the various backside labels of the HP-41 series. I've owned a HP-41C since 1980, and a HP-41CX since 1984, yet I never took notice of that difference before. Thanks for your precise explanation!

With respect to the desciptive labels "fullnut" versus "halfnut", I believe that many (myself included) use the terms exactly as you describe...not as a reference to a particular HP project designation, but only as CLEARLY descriptive and unambiguous terms for the two major versions of HP-41 internal configuration.

So, there is an element of mystery to the HP-41CX that you have. The cited serial number could apply to a very early HP-41CX. Is it possible that these came from HP with the earlier HP-41C/CV backside label? Someone here who owns a HP-41CX with an even earlier serial number could answer that question.

Quote:

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...that distinction between the various backside labels of the HP-41 series. I've owned a HP-41C since 1980, and a HP-41CX since 1984, yet I never took notice of that difference before...So, there is an element of mystery to the HP-41CX that you have. The cited serial number could apply to a very early HP-41CX. Is it possible that these came from HP with the earlier HP-41C/CV backside label? Someone here who owns a HP-41CX with an even earlier serial number could answer that question.

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The front label clearly shows "41CX." The display however, does not have the easily identifiable rounded corners of a CX, but rather the full, sharp cornered display of the earlier models (as an aside, I like this better anyway). Catalog 1 shows 219 registers, as I would expect on a default setting of a CX. The back label has the white label "INSERT, GTO,..." descriptions above the L and M keys as the shift functions. Yet the serial number is "251454nnnn" seemingly indicating a much newer model or production run.

While a bit confused by this all, I am simply happy to have a 41 again!