In Need of Calculator Advice


My beloved 15c is well past its prime, and I feel it may be time to retire her from daily to occasional use. So I need to get another calculator. I have been investigating my options. While I would love to get another 15c, it is a very old calculator, and I don't want to risk picking one up that is not in very good shape. Unfortunately the ones in nice condition seem to sell for more than I can pay. I am currently considering the following options, and would really appreciate any advice.

Should I?

1) Try to pick up a used 32sii

I know and like this calculator. Though they sell high, I believe I could manage to acquire a decent one. I don't know anything about the original 32s, but it might also be an option.

2) Try to pick up a used 42s

I don't know this model as well, but it seems like a great machine. Also pretty pricey, but again, I believe I could get one with some patience.

3) Just get the 35s

No need to seek deals and auctions, and relatively cheap. I have read mixed reviews, some saying it is a return to real quality for HP, others saying the buttons are mushy and the design is poor. So I'm not sure what to think.

4) Something else

Is there any good option I am missing?
There are a couple others I have been looking into. I discovered the 28s, for instance, when I found this great website, and it looks like a fantastic calculator. It also seems to sell for a good bit less than the 32sii and the 42s. However, the design bothers me, and seems less sturdy than other models and a bit too bulky.

Thank you in advance for any thoughts, experiences, or advice.


I favor the 33s as being straightforward and affordable. If you can get by the clunky case and the strange keys it is a good value. First as a simple RPN scientific calc, then a good formula solver and then a RPN programmable with lots of space. You should be used to 26 storage registers. It is uncomplicated to use. Sam



what resources you must have in the other calculator? Which ones you never needed to use in your HP15C? The 'evolution' in terms of available resources is the HP42S: all you need in the HP15C plus a lot more. And an extra challenge: find one for sale with an affordable price. Any other choice would either lead to a 48/49/50 series or to a calculator with less resources. Neither the HP33S nor the HP35S have matrix capabilities, and the amount of extra memory does not imply an improvement, instead an enhancement. I think that the HP32SII would suffice in terms of usage, but it still lacks matrices and complex number resources.

I´d go for an HP42S, but it surely depends on what you actually need from the replacement.


Luiz (Brazil)

Edited: 24 Oct 2009, 9:58 p.m.


If you're having trouble with your 15c, I suspect, from all I've heard, that can breathe at least another decade of life into it.


I think you'll get as many different opinions as you get responses. In my case, I've never replaced my HP-15c, but instead supplemented it with a series of RPL calculators (HP-28S, 48SX, 50g) for programming tasks, and retained the HP-15c for straight keyboard function work. The HP-32SII and HP-35s are no match for the HP-15c and the HP-42s, while it has all the great capabilities of the HP-15c and more, it has no communication capabilities to save data and programs on a PC or develop/edit programs in a PC and transfer them to the calculator. I just cannot comprehend having 7200 bytes of storage and no way to remote load or store programs and data. Of course, the HP-42s does have an IR printer port, but so do the RPL calculators. So, if it were my decision and I were making it today, I'd just keep using the HP-15c for non-programming tasks, and buy a HP-50g, which includes a USB port and cable for between $100 and $150. If you're afraid the HP-15c will wear out or break, don't. It will probably outlive you.


Not knowing exactly how you're using the 15c, this may or may not help, but:

- Keep scouring auction sites for a 15c or 11c daily driver. I've picked up a cosmetically rough 15c for $40 and a broken but repairable 11c for $35. You just have to be patient.

- If you've got an iPhone or iPod touch, there are some great 15c emulators. Also there are generic RPN calculator apps available for the old Palm platform (including Treo/Centro phones) and I believe for Windows Mobile as well.

- I like the 35S but, as noted in the posts above, it depends on how you're using the 15c as to whether it would be a good fit for your use. I switched out my 32SII for it. (Of course I just switched the 35S out for a refurbished 55, but that's just me!)

Good luck!

Edited: 24 Oct 2009, 11:29 p.m.


Get an iPod Touch and 42S, i41CX+ and m48 plus any 15C emulator, sit down, fasten your seat belt and enjoy the flight ;)


Is there something wrong with you 15c? If there is something wrong with it then you should try to get another one in good condition. If there is nothing wrong with it but you simply want to retire it then get the 35s. It's not as good as the older calculator in many respect but it brings lots of new stuff too. It would be an interesting calculator to have, just for the change of pace. You may not like it very much but it's not expensive, brand new and easy to get.


Hi, Chan Tran;

just to ask you if you succeed testing the IR module (HP82242) with the digital camera.


Luiz (Brazil)


Thanks Luis for asking. I tried and it works but it wasn't what I had in mind. I want to analyze the data (not so much from the 41c but from the TV remote control) so I can replicate it.


3) Just get the 35s

No need to seek deals and auctions, and relatively cheap. I have read mixed reviews, some saying it is a return to real quality for HP, others saying the buttons are mushy and the design is poor. So I'm not sure what to think.
The keys are quite good, the firmware is the problem. It's buggy. Another problem might be the glossy display.

If you like the 32SII, get one. I very much prefer it over the 35s due to its better display. Try to get a late Singapore model without the fraction bug. There's another bug with this calculator, but you will probably never find it.


If you use the "equation" feature of the 32sii you most certainly will find the bug, and it will drive you nuts! It messed me up a few times.


The keys are quite good, the firmware is the problem.
I have to correct myself. The "arrow up" key on my 35s isn't recognised anymore despite its audible key click. I have to push it real hard. If I had some doubts about this calculator being completely unsuable for any professional task, this is history now.

Dear HP, you lost another customer.


My recommendations, to be executed top down: IF:

  • your 15C is developing some defects, THEN contact Randy at FixThatCalc,
  • your 15C displays an asterisk, THEN replace the batteries,
  • ELSE continue using it.
  • IF you like to see something more powerful, with a better programming interface (commands instead of keycodes), more space, better complex support, etc., THEN look out for a 42S. It may cost some money, but it's the best RPN calc you can get nowadays still, though 20 years old.
  • IF you are afraid your 15C may get lost / stolen / destroyed THEN check what you really need and use every day: IF matrices and complex numbers are not in THEN buy a 35S, ELSE take even better care of your 15C. The 35S is a nice straightforward affordable calc, but you may be disappointed since you know a better tool already.




Thank you everyone for your great input. What an awesome forum community you have here!

I have decided to put all my responses together to keep this thread from becoming a mess.

I suppose I should have provided more information on my calculator needs, but I did not want to make my post so long that no one would want to read it. I am a college student, and am also involved in biological research. Basic scientific functions, and ease of their use is a major factor for me. Statistical capabilities are also very important (this is also what I write programs for much of the time).

I don't think the 33s will work for me. It could be that the reviews I have read blasting the keyboard responsiveness of that model are incorrect, but in the end I want a calculator that I can really enjoy using, and though cost is a major consideration for me, the 33s is just so hideous that I have pretty much ruled it out.

Thanks for the tip about matrix support. I did not realize the 42s is the only one of those models that has matrices. They are not essential for me (I do have a TI grapher), but they are important, and that really bumps the 42s up on my list. Complex numbers are not as big of a deal for me.

I checked out the fixmycalc website, and they are not taking new repair orders due to overwhelming demand. That is not really an ideal option anyway. I would like to get my 15c fixed up at some point, but I need a calculator daily so I would have to get another one anyway if I send my 15c out. The truth is I could be overly paranoid about my 15c. It is functioning pretty well. The biggest issue is that the "f" (gold shift) key does not register about a third to a half of the times I hit it. There are a couple of more minor key issues, but nothing is completely broken. Furthermore, no matter what I get to replace it, I will definitely miss the "landscape" keyboard layout. I find it so much better than typical calculator layouts. That is actually the main reason I was interested in the 28s, but I'm not sure it would really be the same since it has the hinge. It seems like it would have to be laid on a surface to use.

I enjoy programming features, and consider them a necessity, but don't really require anything more than my 15c can do (though I expect I might come to enjoy additional capabilities). I really have no need for a grapher, and want something compact (I actually do like to stick my calculator in my shirt pocket from time to time).

As for hunting down a deal on a rough but functional 15c, that is basically what I already have (I should have been more clear about its condition in my original post). My issue is also that it is hard to tell if rough looking calculators are really going to be fully functional, and I can't really afford to take the risk and get a loser.

The 35s is looking like a good option, but the bugs mentioned by Thomas Radtke concern me. I will have to see if I can find any information about what functions are affected. The only other issue I have with the 35s is that it looks like it is a bit larger than the Pioneer models (and of course the fact that I now know it does not do matrices).

At this point, I am thinking my strategy will be as follows. I may be overreacting to small issues with my 15c, but I still think it's a good idea to get another calculator for a variety of reasons. It seems like the 42s might be the way to go if I can find a deal (I have downloaded a program called free42 to check out how it works, and the menu system would take some getting used to, but the 2 line display is nice, and it definitely seems to more than meet my needs). However, if I can't find a deal on a 42s, I may just pick up a 35s if I can find out whether those bugs will be an issue for me (obviously only if I find that they will not be). Once I have another solid calculator, I will be free to send my 15c into the shop if I feel it is necessary. So I have all but ruled out the 32sii (it was my number one option coming in so this information has really helped me out).

Anyway, thank you to everyone, and please feel free to give me more feedback as I am still not certain what I will do.




God dag Anders,

For a list of the bugs of the 35S, please check here.




Wow, that is a troubling list. How on earth can HP's current top scientific model be so buggy?!
Anyway, thanks for the link (is there any information that is not somewhere on this website?). I have some more thinking to do now.


I don't think the 33s will work for me. It could be that the reviews I have read blasting the keyboard responsiveness of that model are incorrect, but in the end I want a calculator that I can really enjoy using, and though cost is a major consideration for me, the 33s is just so hideous that I have pretty much ruled it out.

I thought that this would be the case as well. However, having picked up an absolutely mint one on eBay for under $20, I have to say that in many ways I prefer it to my 35s. My main complaint is the legibility of the second and third key functions scripts - the purple and green are pretty washed out on the keyboard in most lighting conditions so that ALL text looks black. Other than that, I like it a lot.



So I have all but ruled out the 32sii (it was my number one option coming in so this information has really helped me out).

Personally, I wouldn't rule out the 32sII that quickly. It is arguably one of HP's finest in many respects - ease and speed of use, superb Pioneer form factor, construction and so on. The 35S doesn't do much more than the 32sII already does but the 35S is really a rather horrible affair in my book.

I know the 32sII doesn't do matrices or complex like the 15C but you've already said you don't need complex. I've never found matrices especially fun on any calc anyway but I don't use them much.

Unless there has been a surge on 32sII prices recently, I didn't think they go for much different than a new 35S and as a really well-balanced general purpose calc which is a lot of fun, the 32sII is a good solid buy. I really like it a lot and the older 32s is pretty good as well (but goes for higher prices).

So my advice would be - don't discount the 32sII totally as it has a lot to offer and even if you need more specialised functions in a different calc, having a 32sII for quickly bashing out calculations on a keyboard where everything is to hand is satisfying. I understand there is a speed-calculator competition somewhere and the calc of choice for people taking part is the 32sII because it is so quick and easy. That should tell you something about it, especially if you consider navigating your way round the maze of menus in a 42s (arrrggh!!!!).



A while ago I bought a new 35s as a light replacement for the 48SX and 48GII. But some of those bugs, especialy the display of floating point numbers and the handling of hexadecimal and binary, made it unusable in my job. So I went for a 33s and got a refurbished one from ebay at a very resonable price. No problems with the keyboard, and everything works as expected, so I'm very happy with it. I even got used to the Enter key in the lower right and meanwhile I find this a real improvement in usability.


I agree. The Enter key should be grouped with the +,-,x,/. On the 34c the Enter key and +,-,x,/ are on the left side of the keypad but on the 32sii the Enter key is on the left and the +,-,x,/ are on the right. At some point these important functions were separated. I prefer to have them grouped together as on the 34c or the 33s and not like the 32sii and 35s.




Similar with me, only I went through 33s (found the 26 storage places a limitation), bought 35S (found some terrible problems like not showing the Exx portion!!, shifted STO, having to press XEQ A AND ENTER etc.). I also have a 50g which is fine but rather large for quite simple tasks I use it for. Now, my 35S is totally unused, 33S and 50g in use.
Conclusion: 33S got extremely harsh response from tradition-loving users (what a keyboard layout! - in fact it's probably better than 35S keyboard layout), but it works much better than the (at first) praised 35S. Very good value for money.


I also find the 33s to have gotten a bad wrap. Sure, at first glance it looks a little funky and un-traditional, but it is a great little calculator nonetheless.

I have the 15C, 32sii, 42s, 35s, and several graphing calcs (11 different HP models in all). I strongly recommend, based on your intended use of the calculator, getting the 33s as your replacement calculator. You will be pleasantly surprised with its rather well thought-out keyboard. It truly is the evolution of the 32sii (just not as aesthetically pleasing).

Jeff Kearns


the 33s is a great little calculator nonetheless.

That's right. And if you are into programming, it is very FAST, much faster than its successor the 35s.



Hi Anders,
Luckily I own both the 35S and 42S :-), so I may add some comments for comparison.

The 35S:
* no matrix capabilities but a built in solver for 2x2 and 3x3 linear equations and a unique vector data type.
* Complex number support is only partially implemented (fully in the 42S) but still quite usable.
* Linear regression and interpolation is available in the 35S. The automatic selection of the best model among various nonlinear regression modes can be programmed (built in in the 42S).
* a useful and timesaving equation mode; No need to write a program to use the solver or numeric integration but only single letter variables! This makes things quite confusing when you have lots of equations stored.
* a built in constants library and mode to calculate with fractions
* a superb carrying case
* some quirqs: bugs in trig functions for large arguments,shifted sto key, hex mode, polar->rect, ...

The 42S
* state of the art pocket sized RPN calculator
* top notch build quality
* full matrix and complex number support
* clean keyboard layout, many functions hidden in menus
* multiletter alphanumeric variable names -> meaningfull names
* loads of programs available (HP41 compatible)

At the end, both are useful tools. The 42S is still at the top of the RPN model range but you have to pay the price accordingly.

Ps.) For a pack of HP35S statistic programs have a look at Namir Shammas webpage.
He is a frequent and esteemed contributor to this forum.



You should consider supplementing your 15c use with a 12c. Depending on your needs for arithmetic (+,-,x,/), scientific functions, programming and portability the 12c could possibly be sufficient and extend the life of your 15c.

Good Luck!



Well, Anders, your experience is a perfect capture of what has bothered countless thousands of HP users for over a decade: Nothing exists in their lineup to properly pick up where the 15c left off. Nothing. Only the big graphing calcs, and they are big. They are not in the same league. They are sledgehammers where a pair of tweezers is desired. And that, is the reality.

Edited: 25 Oct 2009, 8:50 p.m.


Have you considered a non-HP calculator? Given your need for statistical functions and your desire for something small, perhaps you should look at the Casio FX-9860G Slim. It supports matrices; it has a built-in spreadsheet useful for handling experimental data; it will draw graphs if you want it to. The number of built-in statistical functions is quite extraordinary. It's not RPN, but two (at least) RPN calculator programs are available to run on it. One of these (Reckon) has matrix support: you can find information about it on this forum.

I really like this calculator. It isn't drop-dead gorgeous like the HP-15C, but it's well-made, well-designed, and very usable. It is definitely worth thinking about!





I agree!!! Burn the Heritic!!!

Sadly, I also agree with the Heritic, the Casio is a great choice. (But I didn't say it first AND I learn by example!!!) 8^)

Another good selection (IF you don't need trig) is the Hp17Bii. You can get the older Hp17Bii for NOT a lot of money and the newest one also looks pretty good.

While it doesn't have formal programming, its solver is capable of implementing Cramer's Rule for matrix solutions. The older one of renown quality has 7K of RAM available which is actually plenty since you have no I/O ability aside from an IR printer. The newer one has 32K of RAM and same I/O as earlier model.

But the main reason I suggest it, is that it is one of the best pocket calculators for Statistics available. It has list based stats with a strong function set in stats. And what it doesn't have can easily be remedied with its built in solver.

As anyone here with a 32K model Hp42s or newer Hp17Bii, THAT extra RAM is really useless, unless you have extreme persaverance. One MEMORY LOST on you LCD display will re-adjust your love of the 32K of ram you have installed. Yes, my Hp42s will never be short on memory and I actually have added ram to a few calculators (I like the pry and peel method as if it is done right, leaves NO idication of work). However, without anyway to save programs, any large amount of programming is LOST and that can be very annoying. That is the reason I switched over to a 48G model.

Edited: 26 Oct 2009, 9:54 a.m.


Thank you for the relatively mild reactions to my heretical suggestion! I had expected to be hung, drawn, and quartered at the very least. Seriously, the FX-9860G is a nice machine for which Casio provides firmware updates and a SDK for writing C/C++ programs. The only modern machine which HP supports in a similar way is the HP-50g, a machine that I admire but find too unwieldy in every sense for regular use.

One further point in the Casio's favour is its USB port allowing programs and data to be easily backed up. It can also be linked to datalogging equipment, although I haven't tried this myself.

This calculator should be on the shortlist of anyone looking for a small but powerful scientific calculator. It is powerful and a lot of fun!

Nigel the Heretic (who does actually own and enjoy a lot of HP calculators too!)


I think the 50G is the very best, offering the most options for all calculating problems. Great display, great keyboard, great software, file manager, SD card backup, inexpensive, new, etc. How could you go wrong with that? I can only think of two ways that the 15C is better - battery life and portability.


I just wanted to say thanks a bunch to everyone again. I got a lot out of this feedback, and ended up going with an option that I had not even been considering at first, the 33s.

I still find it somewhat lacking in appearance, and find the keyboard labeling somewhat crowded, and the unusual angles make a little more difficult to get used to. However, I really like this calculator, and its appearance does not bother me as much as I had thought it would. It serves my needs very well, and I saved a ton of money by getting it rather than an older model (I picked up a new 33s for $30!). Overall, I am very pleased with it.

Edited: 7 Nov 2009, 3:25 p.m.


one thing that's still bad about it is the small decimal point, even on the second generation one that i have. if that bothers you; try switching it to the euro display where the radix is a (larger) comma and the separator is a decimal.
as you said: not a bad unit for the price.

Possibly Related Threads...
Thread Author Replies Views Last Post
  HP 50g advice Chris Smith 17 1,675 12-04-2012, 11:47 AM
Last Post: Peter Murphy (Livermore)
  New owner of 41c seeks advice mbrethen 46 4,437 09-16-2012, 10:09 AM
Last Post: mbrethen
  Advice on using the HP-50G Matt Agajanian 22 1,983 05-19-2012, 01:52 PM
Last Post: Matt Agajanian
  Restoring an HP-55, advice appreciated ! Alberto Fenini 4 730 05-15-2012, 03:43 AM
Last Post: Alberto Fenini
  Advice needed John Abbott (S. Africa) 15 1,500 04-19-2012, 04:04 PM
Last Post: Luiz C. Vieira (Brazil)
  Need an experts advice: which is currently best CAS? Mike (Stgt) 18 1,804 04-16-2012, 07:48 AM
Last Post: Mike (Stgt)
  HP41 Cleaning Advice John Abbott (S. Africa) 5 758 04-10-2012, 01:51 AM
Last Post: John Abbott (S. Africa)
  HP65 related: I know it belongs in the adds, but I need advice. Luiz C. Vieira (Brazil) 2 494 04-07-2012, 07:31 AM
Last Post: Luiz C. Vieira (Brazil)
  Advice with HP41 Card Reader John Abbott (S. Africa) 11 1,179 04-06-2012, 04:20 PM
Last Post: M. Joury
  Needing more advice with my HP-48S Palmer O. Hanson, Jr. 3 606 09-19-2011, 04:38 AM
Last Post: Bart (UK)

Forum Jump: