A longstanding HP-34C mystery


Hello all.

Even though mine's been around for years (since 79), I've always wondered about one of its most peculiar keyboard design elements.

Since the 'Big Three' RPN necessities are ENTER^, Rv and Last X that makes for good reason that they're usually primary function keys. Further, for the Spice scientifics--31, 32 and 33, they're standard primary functions. Given R^ has been a shifted key ever since the 65, that I've come to expect since only the higher-level programmables have the R^ anyway. So, why, on the 34C is the Rv a shifted key?

Edited: 2 May 2012, 5:09 p.m.



Since the 'Big Three' RPN necessities are ENTER^, Rv and Last X (...)
I'd add a fourth one: [x<>y]. You cannot do the x<>y with any combination of these three without loosing at least one of the existing data in the stack registers. E.g.:

Luiz (Brazil)

Edited: 2 May 2012, 5:16 p.m.


Luiz. Glad you reminded me. Hmm, x<>y. Can't believe I forgot that one. Thanks for the remind.

And yes, three rolls down make a roll up but, two rights STILL don't make a left. And from a programming standpoint three rolls are somewhat a concern with programming space (especially for models such as HP-10C, 11C, 25/33, 19C, 29C). But, I wonder if using the three Rv as a subroutine is any more efficient in programming.

Edited: 2 May 2012, 5:28 p.m.


Couple of options:

1) the 3 shift keys of the HP 34C. You lose a primary key to that shift key.

2) The A and B keys at the top take away two primary keys too.


Do you think maybe a 65, 67 keyboard layout with 35 keys would have been a better design so as to accommodate the stack manipulators as primary keys in addition to a better distribution of secondary, tertiary function key design?

Edited: 2 May 2012, 6:56 p.m.


The keyboard layout of the 34C doesn't bother me. I actually don't find that I use RDN a lot in manual calculations. I do use it in programs and I do use X<>Y a whole lot in manual calculations so I would have really hated that to be shifted. I have always been partial to the size, weight, and feel of the HP-34C in my hand.

I find the shifted STO function of the 35S a whole lot more annoying!




Good. And I thought it was just me :). Seriously though. That is very befuddling, confusing and most peculiar--why would something as essential for even an AOS calculator, a STO key, be demoted to a shifted key? Honestly...just what was HP thinking?


On the HP-28C/S it is just the opposite. Anyway, if one of the keys has to be shifted then the newer approach makes more sense as numbers are stored only once and recalled once or more times.


I never thought of it that way. Thanks. Funny thing too. I had a 28 and although I used both, I never noticed STO & RCL's function placements.

Edited: 2 May 2012, 11:15 p.m.


Never used my 34c at work so i forgot that it didn't have a roll down. Got an 11c instead. Surveyors and others who do a lot of repetitive arithmetic do use that function quite a bit. If it'd been up to me i'd have put the EEX, or even the (sacrilege!) STO in the shifted dungeon.


On RPL calcs like the 28S, RCL is used less than STO. Please see the respective manuals. - I agree a shifted STO on a RPN calc is an annoyance. Regarding RDOWN, I tend using it like Marwan so I don't care if it's shifted.



two rights STILL don't make a left.

But three do! ;-) At least while driving. Politically, that's a whole different story...

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