Blanknut question


I recently purchased a HP-41C Blanknut Option 001. I was wondering if anyone knows why the plastic cover is put over the user and program keys. What was HP's intention?
Is there any way to enter program mode without using the prgm switch? Is the plastic cover removeable?
This particular machine has the following features of a blanknut
1. It is a HP-41CV
2. It has the plastic cover over the program and user switch
3. It does not have a front label (Hewlett Packard ...)
4. It has a serial # on the back
5. It does not have a back label, but has MADE IN SINGAPORE stamped in silver


To program without using the PRGM toggle switch, you can set system flag 52. With a PPC Module us IF (Invert Flag)


That should put you in the PRGM mode. If you executed IF from ROM, then you will be in PRGM mode in the ROM. Do a CATalog 1 to catalog through user programs in RAM. Stop where you want, and have fun programming.


The plastic cover can be removed easily. I removed them on my blank nuts. I think the purpose of the plastic cover is to prevent users from modifying the program or turn off the user mode.


Which of course, one can do by clearing flag 27.

I suppose that's one of those technical things that HP figures users will never care about these days (and back then).


None of my blanknuts had a switch cover. It was either an option (but none of my HP literature mentions it) or an aftermarket thing.


Seven of my eight blanknuts have the switch cover. One, a 41CXHNBN, is NIB, and the cover came in a little plastic baggie inside the HP issue box.


was there any paperwork describing the the purpose/function of the blanknut option in the NIB calc? Maybe it describes the purpose of the bar.


OK, tom, I have to ask...

I consider myself a collector. I have the 41C, CV, and CX, and recently bought an early 41 with the "high top" keys and gold ball bearing in the charger port. And finally, after some years, I found a blanknut. So now I have 5 HP-41s, with two versions of the 41C.

I suppose if I were really obsessed I might try to find halfnut versions of all of them.

But anyway...why in the world do you have EIGHT blanknuts?


once you start, you can't stop! (possible explanation)


I think it was a clearing stock, so he got them cheap.

A few years ago I had the chance to get 6 (six) IL tape drives, and 4 (four) IL printers, six card readers, etc, from a company, amongst many other HP items, for a symbolic price;-)
The units were all near mint.
I sold most of them for a few bucks more,
keeping one unit of each.

The prices weren't as crazy as today.

BTW: The HP-41 Option 001 was described in some flyers from HP, and yes, all photos showed the 001 *with* the bar across the PRGM & USER switches.
So it may have been another option to get the 001 *without* the bar.



Well. You have to have the 41C halfnut and fullnut blanknuts. and the 41CV halfnut and fullnut blanknuts. and then there's the 41CX halfnut and fullnut blanknuts. and you need a couple of halfnut and fullnut blanknuts to trade, of course!


It seems to be that a very possible explanation concerning the black bar is that it came with the option 001's but not originally affixed to the calculator. After you entered your custom program, you would not want it messed with so you would put on one of the plastic bars. That would explain why some blanknuts have the bars and some don't. The bar looks to be an HP product. The finish of the plastic is the same as the body of the 41C. There is even a small rectangular area on the bar that might have been intended for some kind of sticker you would put on to identify the function of the machine. If you had blanknuts performing different tasks at a company, you would want to identify them.

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