To anyone familiar with the HP41:

I am confused by the "Fullnut" & "Halfnut" business.
I understand the basic C, CV, CX differences, viz. lines of program increase 5x from c to cv, and additional functions to CX, incl time functions.

And I think I understand "Blanknut"--this is a CX with "clean" keyboard for customization?

I hope the answer is straightforward, but I am prepared for the confusion!




My first post appears to have been lost, so I'll try again.

I think that the Blanknut has a blank top row of keys. This allowed for a degree of customization.

The Fullnut is distinguishable by the square corners on the display screen and is the earlier generation of the 41. I think is is a little heavier than the Halfnut, and the reason is the full size main circuit board in the unit. The Halfnut has greater integration and as a result the main board is smaller.

Probably one of the other 41 "Nuts" could explain this better than I can!


OK, so then there are actual physical differences between half and fullnut.

So the next questions are:

1. Are the half- and full-nut labelled or named at all differently, or are they identical in HP designation?

2. this difference (half and fullnut) only happened to the CX?

3. Are there any _functional_ differences? (Is greater integration merely a physical integration, or is there something more?)?

(By the way, I have the Virtual HP-41, on the PC, and it makes me smile--and my co-workers get a kick out of it, too! But the REAL THING would be even better...)


I have had both calculators 41CX full and Halfnut - the fullnut was swiped by an unscrupulous low life. Anyways in functionality if I recall, they are identical. The physical differences are internal, with the only external identifier being the screen as mentioned in earlier post.

They were not labelled differently, although there may be differences in where they were mfg'd, resulting in a different serial number.

I can't say for sure about if the 41C/CV had halfnut variations. Again, I will need to defer to other Nut nuts for this question.

Glad you are enjoying the emulator. I have one for my pocketpc and although I love to use it, it is a poor second compared to using the real thing!


Coconut was the HP internal codename for the original 41C, the 41CX was Honeynut and the 41CV Silverbird. There was a version known as Option 001 which was meant to be customised by the user and therefore had no labels on the upper rows of keys or on the surrounding keypad. This was the blanknut.

During the 41's life it was modified with a reduced number of electronic components and these versions became known as the halfnuts with the earlier versions becoming known as fullnuts. As already mentioned in an earlier post the display is the obvious external difference bewteen half- and fullnuts. I think all three types, 41C, CV and CX can come in either half- or fullnut versions. I am not certain if HP used the halfnut or fullnut designations internally or whether these originated from enthusiasts - anyone know?


PS - I think that one functional difference is that with halfnuts it is possible to program the display to get a full set of lower case characters and also to adjust the contrast of the display.


I would be interested in learning how to do this on my 'arfnut. I recall that to get lower case you go into Alpha mode, then shift, a - e (the upper row) is then lowercased. I am unaware of how to do this unless it is through a routine or program. I don't think they are available through standard keyboard access.

Anyone know how to do this?


Not really, but it appears to involve the use of the 41's machine code programming (way beyond my expertise) - see for example earlier archive threads:

and for a good explanation of the internal differences between halfs and fulls:


To access the contrast control, or the lower case characters (except for a-e), you have to program in machine code. The font for all characters are defined in the display driver, but the HP-41 software was not changed to access any of this, so it is totally impossible to get to this using either normal user code, nor synthetic code.


Thanks to everyone for your responses!



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