interchanging 34c commas and dots


I have a *foreign* 34c which uses a comma for a decimal point and dots for digit separators. Is there a jumper or something to reverse this behavior?


"There is a hardware jumper that can change the display to non-US notation (switch the dot and comma). Location is not known (outside of HP)."





sometime ago, Katie Wasserman showed that this jumper is located in the power supply board. In fact, it is located there, but it connects two pins in the mainboard, not necessarily power supply components. I can say that I REMEMBER seeing some Spice's power supplies and found only one jumper, but I cannot say I'm one hundred percent positive about my own memories...

I'll test it and post later.

Luiz C. Vieira - Brazil


Please don't laugh - I don't know the HP 34C.

On the voyager-models you can change the comma-dots by holding down the dot-key while turning on the calculator.



Hello, Thomas;

if someone laugh, he's the one that's wrong.

The HP34C is something like the HP11C with a LED display, vertical case instead of the horizontal one found in all Voyagers, no nPk (permutation) neither nCk (Combination), four flags instead of two, two direct access lables ([A] and [B] keys) instead of the five ones of the HP11C and its autotest is started with the sequence [STO][ENTER] instead of [ON]&[×] (or [ON]&[+]) of the HP11C. It uses rechargeable batteries and is older than the Voyagers ( it was introduced in the same month and year of the HP41C).

When applicable to the place it was commercialized, the Spices (HP34C include, of course) were available with a comma as radix mark. For example, in Brazil it's the standard representation. And to change this "condition" the only way is to change a jumper inside the calculator. I wonder if a small externaly accessible miniswitch would be applicable...

Hope this helps a bit. And never hold a question too long, mostly if there are teachers around you...

Best regards.

Luiz C. Vieira - Brazil

Edited: 19 June 2003, 11:10 a.m. after one or more responses were posted


hey that last one was a pretty picture!

I like a calculator that looks like that.

Where can I go buy one brand new, just like that ? Tell me and I will buy a whole bunch, for me and some friends.



Hey, Norm;

I forgot to post the credit, but the link would say that.

It's the very picture of the HP34C that is available at the MoHPC. You should thak Dave Hicks.

Best regards.

Luiz C. Vieira - Brazil


Hello Luiz,

thanks - thanks for the pretty picture. I know the design of the calculator. But nothing about the usage.

It was only an idea. HP do anything for easy usage. :-))



Hey, Tim;

I opened an HP38C that has the separator set to "dot" and checked for the jumper. Look at the image below:

This is the small power supply board (PS board) and it's the same one used in the HP34C. If you open the calculator (excuse me if this is a silly question: do you have the skills to handle this? I'd not like to know you tried and dammaged your calculator) and fasten the PS board, you'll see the jumper shown above is not present, meaning your unit is set to comma separator. After generating this image I cut the jumper, rebuilt the calculator and switched it to ON: comma as radix mark. The relation is:

Jumper closed - dot separator
Jumper opened - comma separator

In your case, you'll have to use a small wire and connect both terminals as shown in the picture.

I hope you are successful. Let us know.

Luiz C. Vieira - Brazil

Edited: 18 June 2003, 3:53 p.m.


If you waz a pilot, you'd be flying the SR-71 blackbird.

I am very impressed with your detective work and the photograph of the jumper.

You figured it out very fast for everybody.

I will print it out for my records.

Awesome, absolutely awesome. Good job dude.

SHOULDN'T that go to Dave Hicks for posting into a "service-database" ?? I think stuff like that should be recorded in a big long list, for the model(s) that it applies to. Like a master service index.


Hello Norm, guys;

thank you, Norm. That's the least I can do.

But I must be fair: I'm supported by giant's shoulders. Katie Wasserman posted this information about one year ago. I have the "bad" habit of not forgetting what I take as a rational and coherent information. I think this is why I still remember some of English from my 1982's classes. Oh, yes, for the reords: the image is a scanned image. I'd like having a camera, but NOT an HP camera...

And if I'm a pilot, I'd surely try to fly a Blackbird... Wonderfull machines: SR-71 and the B-52. Oh, my...

Luiz C. Vieira - Brazil



Neat picture.

I can identify the (rather amazing) mish-mash of components, except for the circular thing on the right, with the 10 wires coming out of (going into?) it. What is that? An inductor? A switch? ???


That is the switching power supply inductor (transformer).

By the way, there are a couple of different styles of Spice power supply. Your's may look a bit different. I have seen one where the jumpers looked like small surface mount resistors.


Despite the risk of causing mischief, I had to ask.

Feel free to answer, "Open up your 34C and find out!"

(To which I'll have to reply, "I started to open it once, and just didn't have the heart to keep prying the case halves apart -- they seem sure to break!")


Hi, Paul;

all Spices I saw so far have this jumper opened. I was not curious enough to follow it and see what is it related to.

Sorry not giving you a better answer.

Best regards.

Luiz C. Vieira - Brazil


Luiz, thank you very much for the information and the photo. I have the skills, as soon as I get the time I will try this out and report back.



For what it's worth, that jumper would connect pin 6 of all three 8 pin chips, and pin 14 of the 40 pin chip, to the negative terminal of the battery, which is also connected to pin 7 of all three 8 pin chips and pin 13 of the 40 pin chip.


Hello, Ellis;

thank you for the information.

Have you also measured voltage across them? What do you think, could these points be connected together or maybe they are test points?

I know that without knowing precise pin function under each possible situation it's just speculation.

But it's also fuin to exercise the brain cells. Our brain cells...

Best regards.

Luiz C. Vieira - Brazil

Edited: 18 June 2003, 8:24 p.m.

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