Hypothetical HP 15CII or 34S


(The following is a repost of an earlier message, evidently Tripod.com doesn't allow remote loading of images so I had to look for another website that would allow remote loading. So here goes, hope this works... )

I was just browsing through Archive 14 when I saw a very interesting thread there for a "hypothetical HP 15CII". The picture by Chris Woodhouse is very promising. I thought I would suggest a similar idea but so as not to confuse it with Chris's idea I've renamed it the "hypothetical HP 34S". Here's a picture of what it might look like:

You might notice in the picture the following:

- The ENTER key has been brought back in the horizontal orientation, which in my opinion makes entry easier

- The keys are in color-coded groups to facilitate quick location of a desired group; white for the number keys, light grey for the stack manipulation keys, a darker grey for the programming keys, and olive green for the trigonometric keys

- The keys are of the beveled type used in the Woodstock and Spice series; this is so that there need be only one legend above each key, namely the gold legend, while the blue legend resides on the bevel; in my opinion this design should have been retained by HP because it leads to a less uncluttered keyboard appearance

- The case is of the Pioneer type, with rounded corners, which I find easier to hold than the square corners of the Voyager type

I'd appreciate hearing any comments on the design, and thanks to Chris Woodhouse for the original suggestion.


* It's funny to notice that after there has been some discussion (if I remember well) about the up/down placement of the left and right shift keys on a.o. an HP-32SII (some cosider this inconsistent), you do the same thing the other way round. You seem to fancy the up/down orientation of the functions on the keys, but you use the "traditional" location of f and g prefixes.

* A more important thing is that it lacks an "F" key. The display shows hex facilities, so you'll have to be able to input a full hex number, won't you? I don't think that the F can be on top of STO, so you'll have to rearrange some keys.

* I myself would have exchanged the display and the badges. You'd be able to use A through E (F?) as a kind of function keys like the HP-20S does.

* Good thing that the display is alpha. So much easier than key codes in programming mode.

* Anything else? Well, not for the moment. You obviously borrowed the keys from a few calculators and put them together for their main functions (duplicate FRAC/INT function), so let's wait for more reactions and a new "design". anyway, it was nice having had to think about it.


Hehe, you're right! I was in such a hurry to "cut and paste" together my imaginary calculator that I neglected to check for duplicate functions. :-) I think I even duplicated the x^2, 1/x, y^x, etc. Anyway, I thought the picture would be useful to those out there who wanted to get a general idea of the keyboard layout of a possible replacement for the much-reviled HP-33S. Point well taken about the lack of an "F" key for hex entry, perhaps the "F" can just replace the top "FRAC" since there's another "FRAC" anyway.

Thanks for the suggestions and comments.


ANd double delta% and double L.R. etc.

Ha! Even the [R/S] has double PSE !!

Maybe you could have a HP-16C on the back-side and the HP-15C on the other side...



"Maybe you could have a HP-16C on the back-side and the HP-15C on the other side..." Come to think of it, maybe not a bad idea! The new HP15/16S is on the way!!! ;-)


First impressions:

Like the format, keys, colours and 23(?) digit display. Also like the way the calc has been merged from several others. The mock-up needs a bit more thought...

Enter key too far from number keys - lots of finger travel when typing with one hand.

Eng, Sci, Fix keys not needed if menu select available.

If calc has Hex mode then A-F keys needed.

I don't use the Sigma+ key that often so could be moved to make the Enter key (which is used all the time) nearer the middle of the calc (like all other -real- HPs?)

Nice try, just needs a bit more refinement for the features it looks like it could have - again thanks for the effort and posing the question.

Edited: 23 June 2004, 7:39 a.m.


Yup, I was debating whether to put the ENTER key closer to the keypad and at first I thought I'd position it where the "TAN" and "RCL" keys are located. But then I was thinking that perhaps some people who hold the calculator with two hands would be able to use their left thumb for ENTER, although I must agree that some people prefer entering both the numbers and ENTER with the right hand.

So I guess we should take a vote, how many of you would like to leave the ENTER key where it is in the photo, and how many of you would like to see it moved closer to the keypad? Let's hear your input on this folks!


The real 15C provided the perferct orientation and placement of the ENTER key (i.e. vertical and near numbers).
Please don't try to change it.



I like the ENTER near the number keys. I like the alphanumeric screen and the color code of the keys.


So I guess we should take a vote, how many of you would like to leave the ENTER key where it is in the photo, and how many of you would like to see it moved closer to the keypad?

Keep the original 15C keyboard layout (including the vertical ENTER), along with your new case, display and color scheme, and this would be my idea of a perfect calculator!


Hmm, well I was never a big fan of the vertical ENTER key. Prior to the introduction of the Voyager series, I had gotten so used to the horizontal ENTER key on the Spice and Woodstock series that it became second nature to me. The vertical ENTER key would have been great had HP made it the right way. But if you'll notice, on every Voyager series calculator the vertical ENTER key can be clicked with maximum travel only at the upper end, whereas at the lower end it is too firm and has barely a hint of travel. I always did find this hugely annoying and needless to say I was quite happy when the HP-32S came out with the horizontal ENTER key again, although I must admit I was never a fan of the orange-colored key legends. I haven't tried the HP-12C Platinum yet so I don't know if it suffers from the same problem (with regards to the vertical ENTER key clicking fully only at the top and not the bottom) as its other Voyager siblings, perhaps someone out there with a Platinum can tell us if the problem still exists.

There've been a few people who've posted messages saying that an alphanumeric display is preferable to the old Voyager numeric-only display (although the 16C did have a simulated, limited set of alpha).

The idea of color-coded key groups wasn't really my idea, but that's how HP calculators used to be made prior to the Voyager series. I'm hoping that HP can bring back this very useful idea, rather than investing in useless teeny-bopper fads like a chevron keyboard layout (hint, hint...)


The 12C Platinum clicks at both ends of the enter key. Although, it is a bit stiff at the lower part of the key. Keep in mind though that my platinum is fairly new, so that may be why it's stiff.



with regards to the vertical ENTER key clicking fully only at the top and not the bottom

The keys are on pivots. All the keys have their pivots at the bottom, and are free at the top. That is why you do not get the same "click" in the same way when pushing the bottom of the key--you have less leverage against the spring.

I just don't push it at the bottom--something a voyager user figures out.

Of course, I think the oversize enter key has nothing to do with function, and everything to do with MARKETING.

Like, why is <enter> more important than the number 3? Or the number 1? Or 0? Or +? You really don't even use <enter> as much as you think---once you are in a chain, you never touch it!

Best regards,




I am dreaming about an HP calc, what is works with negative binary/decimal system. No more CHS, no more negative numbers, no more substraction. The placevalues are 1, -10, 100, -1000, ... (or, maybe: -1, 10, -100, 1000, ...)

If you earns many money with this idea, please, give me some percents ;) (Or 3-4 HP15C)



Csaba posted:

"If you earns many money with this idea, please, give me some percents ;) (Or 3-4 HP15C)"

That's Donald E. Knuth's idea, see "The Art of Computer Programming", vol. 2, 'Seminumerical Algorithms', "Negadecimal".

Best regards from V.


Wow....I darn near p!ssed myself when I saw this!! Nice job. I would prefer a vertical enter key myself.


Very nice work! I think it's much more what the pioneer series *should* have looked like (if I had anything to do with it).

One thing I find highly appealing is the contrast created using different colors for functional blocks of keys. Not only does it look nice, it would be highly user friendly as well.

I only have a couple of actual complaints (as a form factor). #1 is that the case is too long. 3"x5" will fit in a front shirt pocket. Bring it in a bit on each side and shrink the logos, that should get you there. #2 is the location of the enter key. Perhaps it wouldn't be too bad if you use a two handed technique for entry... but it's just hard to get away with it being on the other side of the machine from the numbers.

I am planning to build a few prototype cases for OpenRPN this summer to test feel and key layouts (I may give this one a shot too).


Wow! Westridge! What a beautiful job!!!

But instead of running out to buy one, I'd only walk fast, because, I (and I seem to be the only one) prefer its layout orientation to be vertical, as in the Spices (34C) or Pioneers (32sII), as opposed to horizontal as you and the Voyagers (15C) have it.

I do really regret not owning a 15C, but one of the two reasons why I did not buy one was its horizontal layout (the other one being lack of funds!).


But instead of running out to buy one, I'd only walk fast, because, I (and I seem to be the only one) prefer its layout orientation to be vertical, as in the Spices (34C) or Pioneers (32sII), as opposed to horizontal as you and the Voyagers (15C) have it.

Do you mind if I ask why that is? Can you give more detail as to what about each layout that you like or dislike?

Chris W


Oh, it's just a personal preference: I've been using vertically oriented calculators since high school. Thus, it is easier for me to find the keys I'm looking for, if they are not the ones I always use and have memorized their positions. Also, when I hold a vertically aligned calculator in my hands, it feels better to me and it makes it easier to use the fingertips of the same hand to press the keys and yet have a clear, unobstructed view of the display.

Incidentally, I think all LCD displays should be the older cut element type rather than today's dot matrix style; it's just easier on the eyes.

Is there a reason why some people here prefer the horizontal layout?


Is there a reason why some people here prefer the horizontal layout?

If you read the section at hp15c.org on keyboard layout I explain why I prefer the landscape layout.

Chris W


Ah, so.

I suppose you and the website are correct in that some of us prefer to hold the calculator in only one hand. I also suppose that if I did own a 15C, I'd probably wind up keypressing the way prescribed on the site.

I just realized another thing. The 34C was my first "serious" calculator. How do you reason away a first love? By the way, I FULLY understand "reeeeeddddd leeeeeds"! The only reason why, if I were to design a calculator, to implement LCDs would be so that, as one poster said, we won't need to have a calculator the size of a (rechargeable) four-D-cell chamber!

But, whether portrait or landscape, if it's one of those old fashioned big ENTER key, RPN, impact resistant, durable and solid-feeling key HP models, I'm all for it!


Very nice looking design. I will have to echo what was said by OpenRPN, you need to narrow it up so you stay with in that 3 x 5 size. Also I am surprised no one has mentioned maximizing the use of vertical space and adding a second line in the display. I think that is a VERY nice feature for an RPN calculator, and am surprised that more don't have it. The enter key on the left side would be great when you hold it in your hands, because as I have said before, the best way to use a landscape layout calculator is to hold it with both hands and use your thumbs to push the keys. But if it is on your desk and you are only using one hand I don't think I would like the enter key so far away. Either way I would still prefer the vertical orientation of the enter key.

Chris W


Two line displays don't need to be as bulky as most people think. There is actually ample space for one in the LCD cutout on a voyager series calc... As long as you move the indicators off to one side. Doing things this way won't even sacrifice character height!


I always preferred the mode indicators at the bottom of the screen, with the top part of the screen dedicated to the stacks.

i.e.: 2: 5.
1: 6.


If you stop to picture what it would look like, I think the idea of indicators off to a side of the screen would be much more appealing. I usually find them a little difficult to see, whereas numbers would still be clearly visible.

The main thing is practicality: would you rather have 2-lines plus indicators and have something so wide it won't fit in your pocket? Or 2-lines and the same size as a 1-line display?


Making the font smaller for the two lines is fine, however, I don't want to squint every time I see the calculator's display.

About the size issue: three functions per key should be enough. Four (alpha) and the keyboard will be overrun (HP33S is an example).

I like to have 2nd/f/LS key for additional functions, and the 3rd/g/RS for Menus. The menus could replace the screen entirely (limited to 4-6 choices?) or have a referrence on the back of the calclulator (like the HP Voyager series had, I know the 12C does...) [I miss the days you recieved the small "cheat sheet" with your calculator...]

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