Design contest ;)


Ok, I didn't want to do that again, but since two requests were posted recently you find here a number of drafts showing some opportunities present HP calculator housings allow. As mentioned elsewhere, most drafts were posted earlier already. With respect to the upcoming HHC2010, they are published here in a new thread to foster discussions about a new scientific RPN calculator. After all, these financial guys drove us into last crisis, now, HP, give the engineers a good, handy pocket calculator before they will do alike! ;)

First picture shows what's possible based on a 15C with minimal modifications:

You may note an INV prefix for inverting functions top left, and an arrow prefix for conversions (top right). Respective applicable functions are connected with a white dash. Everything else is old technology (no need to get used to something new, hurrah!).

With a little more effort, particularily a full dot matrix display (hey, a change after almost 30 years! How dare you!), one may reach something like this:

Similar layouts can be done easily based on
a 42S: , a 17BII Silver: , or a 35S:.

As many of you know, Paul Dale and me have started a 20B repurposing project some (many) months ago. This is our present layout:
Of course, we'll use the 30B HW now. There is a 49-page manual available for this draft already - if you want a copy please drop me a note.

This as well as all other drafts published here and the related documentation are subject to updates without notice. So, as written elsewhere already, comments, critics, suggestions etc. are most welcome, especially if some reasoning is included. Don't hesitate to ask questions you may have! Though you can't buy any of these models yet, maybe you may get one of them once when either our repurposing project will end successfully or a renowned calculator corporation which will not be named here will take the chance ... ;)

Ceterum censeo: HP, launch a new scientific!




Put me down for a 34s :)


Hi Walter,

As many of you know, Paul Dale and me have started a 20B repurposing project some (many) months ago. This is our present layout: [...]
Of course, we'll use the 30B HW now. There is a 49-page manual available for this draft already - if you want a copy please drop me a note.

Is there a working implementation?

What do I need to install the new firmware if given? I'm asking for a dummies guide here ;-).

Is / would the 20b still (be) supported?



Is there a working implementation?

Not quite. The bulk of the coding is done & runs fine in a terminal window. The port to the actual hardware isn't done.

Is / would the 20b still (be) supported?


- Pauli

Edited: 31 Aug 2010, 3:37 a.m.


All these implementations look good, especially those based on the 15C. However, the question that we have to ask ourselves is, is anyone with any power to bring out a new calculator, listening.

It seems that the calls for a good rpn scientific calculator have been going on for years. The 33s with it's chevron keyboard and it's decimal point, wasn't an option. The 35s apparently has keyboard issues.

That said though, those mock ups look really good.


What would really be cool is implementing software that makes these working emulators (since there is real model to simulate).




Responding to the questions raised by M. Joury in the old thread:

If you were able to design your own machine where would you start? What current or past implementation would you base it on? I think I would vote for the HP42S as the starting point. Then add the best of the current crop (35s, 30b, etc.) and make sure to give it at least 32K RAM and some form of offline backup.

For the 34S, we took the function set of the HP-42S as you suggest. We added the
  • function set of the HP-16C,
  • fraction mode of the HP-32SII and successors,
  • statistical distributions of HP-21S,
  • constants and conversions of HP-35S,
  • complete Greek and extended Latin letter set (beyond English),
  • a real time clock,
  • date and time calculations,
  • and more SI<->IMP conversions, physical constants, statistical distributions (like Poisson, Exponential, Geometric, Weibull and the error function), and some more arcane functions (like Euler's Beta, incomplete regularized gamma etc., coming Paul's way while coding ;) )
RAM is given and thus limited there, of course, but it's sufficient for all this and 500 program steps, 100 general purpose registers, and 100 user flags. No way for I/O for backup as you suggested. And we had to drop the matrix functions due to display limitations :(

A little more than a simplistic start :)

The other drafts are just this - drafts - based on the housings given. Sometimes I dared to dream of reasonable displays allowing matrix operations and a row of softkeys, and an SD or Micro SD slot for I/O. FWIW

Edit: Forgot date and time.

Edited: 31 Aug 2010, 12:57 p.m.


When I posited my question I was thinking more in terms of a clean slate design. No restrictions and not assuming current hardware. But I like what you have here and would definitely buy 1 or more! As others have noted I think that it is obvious that for some of us a powerful scientific calculator in a compact package with a smallish (compared to graphing calculators) screen and the straight-forward HP41/HP42 programming paradigm is badly needed.

Thanks for your answer.

M. Joury


The mere fact that we're having this discussion shows the desperate need for keyboard overlays and assignable keys. If you have those, then question of which functions are on which keys largely goes away. If you don't like them, just change them.



That's the reason for the golden ASN on some drafts below of orange "m". Quoting an explanatory text of January 2009:

ASSIGN will allow you assigning a command, program, variable, character, or a menu to the key you specify. Pressing {m} plus this specific key thereafter will execute the command or program, recall the variable, display the menu or insert the character assigned, respectively.
  • Enter {f} {ASN} name {key} . {key} may include prefixes if necessary.

    For example, to assign a program 'ABC' to the m-shifted SQRT key of a 45S, you enter
    {f} {ASN} 'ABC' {SQRT}.
    Thereafter, whenever you press {m} {SQRT} , your 45S will execute your program 'ABC' instead of the previous m-shifted function of this key. ...
  • You may use keyboard overlays to show your assignments. If you want to reset a particular key, use {g} {ASN^-1} {key} to recall the default m-shifted function of this key.

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