The Best Calculator Ever

By Julianne Dalcanton | April 2, 2008 1:22 am

I’ve written before about my husband’s affection, or rather, obsession with Apple. Like all good converts, he feels compelled to proselytize, particularly about my perceived need for an iPhone. “But honey, you can check your email!” “Hey look! Google Maps knows where you are!”. I remain unconvinced.

However, the other day, he nearly got me:

“Did you know it can emulate the HP-15C?”

Be. Still. My. Heart.

The HP-15C is simply the finest piece of handheld computing technology ever. (Take that Steve Jobs). I got my first 15C back in high school, and it was the only calculator I used for the next couple of decades. I could operate it in the dark. I lost it in an airplane seat back pocket and have never gotten over it.

hp15c_front.jpg hp15c_back.jpg

I suppose in the intervening years we’ve gotten used to irrational devotion to electronic gadgets, but the 15C had to have been one of the first targets, at least in geeky circles. If you mention the 15C to a nerds of a certain age, our eyes grow misty at the utter perfection of it. It was a calculator that simply got everything right.

The genius of the 15C is multifold. First is the form factor. It’s essentially the same as an iPhone, held in landscape mode, with a nice weight that fits well in the hand. The buttons are large and well separated, and there are no more or no fewer than you could want. (In comparison, modern HP calculators are crammed with a thicket of unusable little buttons. Ick.) Second is the glory of reverse polish notation. The 15C operates with a memory stack, which when operating with RPN allows you to perform complex calculations with no need for parentheses. Third is the 15C’s unnatural durability. A former dog of mine literally mangled a friend’s 15C, and it continued to work in spite of the large teeth marks denting the keys. Fourth (and most critical for getting me through years of physics labs and observing runs) was that it’s programmable. That’s no big deal these days, but huge in the early 80’s. Spreadsheets were hardly widespread, and when one timed balls going down ramps or any other such repeated trial, doing repetitive calculations was a breeze on the 15C.

Now, am I alone if my love for the 15C? No, indeed. On Ebay, a 15C in good shape can go for hundreds of dollars. (And if you buy one, it’ll still work. I’m guessing one will not say the same about the iPod in 30 years.). There’s an on-line petition begging HP to bring the 15C back.

And, there are people out there writing emulators for it to run on the iPhone. If you ever see me with an iPhone, this will be why.

CATEGORIZED UNDER: Computing, Gadgets
  • Trent

    I wonder how much more stuff you and/or your husband like on this list:

    apart from Apple products.


  • Trent

    Actually, not restricting the list to your (and/or your husband) but all authors of this blog I’m fairly certain that the following are stuff you all like:

    * #93 Music Piracy
    * #92 Book Deals
    * #91 San Francisco
    * #90 Dinner Parties
    * #89 St. Patrick’s Day
    * #88 Having Gay Friends
    * #87 Outdoor Performance Clothes
    * #86 Shorts
    * #85 The Wire
    * #84 T-Shirts
    * #83 Bad Memories of High School
    * #82 Hating Corporations
    * #81 Graduate School
    * #80 The Idea of Soccer
    * #79 Modern Furniture
    * #78 Multilingual Children
    * #77 Musical Comedy
    * #76 Bottles of Water
    * #75 Threatening to Move to Canada
    * #74 Oscar Parties
    * #73 Gentrification
    * #72 Study Abroad
    * #71 Being the only white person around
    * #70 Difficult Breakups
    * #69 Mos Def
    * #68 Michel Gondry
    * #67 Standing Still at Concerts
    * #66 Divorce
    * #65 Co-Ed Sports
    * #64 Recycling
    * #63 Expensive Sandwiches
    * #62 Knowing What’s Best for Poor People
    * #61 Bicycles
    * #60 Toyota Prius
    * #59 Natural Medicine
    * #58 Japan
    * #57 Juno
    * #56 Lawyers
    * #55 Apologies
    * #54 Kitchen Gadgets
    * #53 Dogs
    * #52 Sarah Silverman
    * #51 Living by the Water
    * #50 Irony
    * #49 Vintage
    * #48 Whole Foods and Grocery Co-ops
    * #47 Arts Degrees
    * #46 The Sunday New York Times
    * #45 Asian Fusion Food
    * #44 Public Radio
    * #43 Plays
    * #42 Sushi
    * #41 Indie Music
    * #40 Apple Products
    * #39 Netflix
    * #38 Arrested Development
    * #37 Renovations
    * #36 Breakfast Places
    * #35 The Daily Show/Colbert Report
    * #34 Architecture
    * #33 Marijuana
    * #32 Vegan/Vegetarianism
    * #31 Snowboarding
    * #30 Wrigley Field
    * #29 80s Night
    * #28 Not having a TV
    * #27 Marathons
    * #26 Manhattan (now Brooklyn too!)
    * #25 David Sedaris
    * #24 Wine
    * #23 Microbreweries
    * #22 Having Two Last Names
    * #21 Writers Workshops
    * #20 Being an expert on YOUR culture
    * #19 Traveling
    * #18 Awareness
    * #17 Hating their Parents
    * #16 Gifted Children
    * #15 Yoga
    * #14 Having Black Friends
    * #13 Tea
    * #12 Non-Profit Organizations
    * #11 Asian Girls
    * #10 Wes Anderson Movies
    * #9 Making you feel bad about not going outside
    * #8 Barack Obama
    * #7 Diversity
    * #6 Organic Food
    * #5 Farmer’s Markets
    * #4 Assists
    * #3 Film Festivals
    * #2 Religions their parents don’t belong to
    * #1 Coffee

    Let me know if there are stuff on this list you actually do *not* like! :)

  • Dr. Goulu

    You forgot to mention the HP-15C was equipped with a nuclear battery or a way to extract energy from the Void, I’m not sure anymore. The fact is I never saw one with an empty battery. Mine lasted for more than 20 years before it was destroyed by a fire in my office…

    Anyway, you can react to the lost of yours :
    1) sign the petition on
    2) with this emulator, you won’t need to invest in a Mac :


  • Bob

    Well, if you have a blackberry, you can get the Pocket 10C SE emulator. It’s not the 15C, but the nice thing is that the Blackberry has nice keys, and the emulator uses most of them in an intuitive layout. And when using a calculator, I have found that there is nothing like good tactile feedback. Take that, iPhone!

  • Zeno

    I carry a 15C in the pocket of my briefcase and it goes with me practically everywhere. It is my precious.

    To make things even better, my students never try to borrow it. They are heathens who do not know the true religion of RPN. My precious stays safe with me.

  • John R Ramsden

    Trent (#1 or #2), although your list is evidently intended to summarize the tastes of left-wing trendies, surely it’s possible to love one’s calculator and be as right wing as Attila the Hun or even Ann Coulter?

    Oh wait, Apple Macs were mentioned too. Hmm, yes I see what you mean now 😉

  • Scott G.

    I received my HP15C as a gift from a friend around 1986. I still use it nearly as my sole calculator (I might have replaced the batteries once). I have a TI89 on my desk, but I will usually ignore it completely and grab my old friend for any serious calculations. At school, I love when folks ask me to borrow my calculator and gladly let them – for the 30 seconds it takes until they realize they have never even heard of RPN, much less know how to think in it.

    I was looking through that Things White People Like list the other day – oddly enough, almost none of it fits me, or fits badly (e.g., I like Netflix, but not for Indi films; I love bicycling, but my bike is way under $5k.).

  • Phased Weasel

    I was the only one I knew in middle school with a reverse Polish notation calculator. Fools!

  • Count Iblis

    My father still uses his HP 11c. I learned to program in that calculator when I was in primary school. I remember that if the program becomes too long you’ll start to lose memory addresses.

    Later I bought the HP 28s calculator I still use it today.

  • chemicalscum

    I know it is not a real substitute and you have probably already tried it, but the The Museum of HP Calculators has a HP-15C emulator for PC’s:

    It includes source code, Linux and Windows binaries so you should be able to run it on your Linux system straight off. It hasn’t been tested on a Mac but I guess it should be possible to get it going under X11 maybe its a task you could give your husband to get going on his Mac.

    I never really got into RPN though I did try it for a while using an old Linux RPN calculator program a few years ago. I never had an HP calculator in my youth, anyway when I was an undergraduate student we used slide rules and teletypes to access a computer.

  • Glenn McDavid

    See Free 42 for an emulator that runs on other handheld devices. In particular

    What if HP put the logic and display of a 42S in the compact and convenient form factor of a 15C? You’d have the 42C

    which you can have on the Zaurus X/Qt and Nokia 770.

  • loonunit

    And for persons of my generation, RPN was a horrible prank our professors would spring on us if we foolishly forgot to bring calculators to our exams.

  • jackd

    The business geeks are just as crazy about the HP 12C.

    This is waaay down the food chain from the landscape HPs of yore, but I’ve got a TI-55 III obtained in 1985 or ’86. Still on the original batteries.

  • rob

    ahh…the 15C. I was always jealous of those that had one. i myself have the 11C. at least i think it is–the label fell off years ago and i have had to replace the rubber feet on the back. it is about 23 years old. i wonder how long that is in iphone years? 72.26?

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  • Ron H

    I still use my HP11C, My HP48G sits to one side – little used due to it’s complexity. The HP25 (Hmm not a 25C but real close) is also used a lot.

  • chris

    hi glen (#11),

    on a zaurus you can run maxima. i know this is kind of religious, but prefering a upn calculator over a complete cas is… well.. religious i guess.

  • Annika Peter

    My dad has that calculator and wears it in the pocket of his shirt every single day. No one would mistake him for anything but a science professor.

  • Robert

    My first contact with HP calculators was my dad’s HP25 which I learned to use at some point. And for many years after had a desktop HP calculator. I don’t know which model it was but according to it must have been something like a HP 9820A. The feature I remember is that it hat a “Spiel gut” sticker on it > This sticker was usually found on wooden toys of high pedagogical value.

    Later, in high school, my physics teacher, had an HP calculator which could read little magnetic strips: You could store time and your location and declination and rectascention (sp?) of some celestial object in some registers and then read in three strips and it gave you coordinates in which direction to look. I was quite impressed.

    A bit later, I got my own HP 32S which I still have (here on my desk). I can second this feature that the RPN prevents to much desire from other people to borrow it but I think it soon needs some new batteries (and I vaguely remember of having them changed once already in the past). Unfortunately, by now it also has a few faulty pixels.

    I have to admit I do not use it too often as I try to do physics order of magnitude estimates in my head as a sport. And when I need more than half a significant digit I tend to use calcoo which is more handy as it is permanently open on my (computer) desktop whereas the HP 32S is in a drawer. In addition you can configure it to have a virtually infinite stack (rather than the four levels of the original HP’s). It happened only a few times but I consider a finite stack depth to be a bug rather than a feature even though the HP manual lists an application where the finite depth is actually used. IIRC it’s computing the powers of 2: Press


    and then * as often as needed.

  • sam

    what about the TI-1250?

  • PAgent

    I still have and use my beloved HP 11C that I bought when I was an undergraduate for the princely sum of $75. In the intervening 22 years I have replaced the batteries *once*. Best. Calculator. Ever.

  • Martin Gale

    Finance quants have a similar unbounded affection for the HP12C (the 15C’s sister ship).

  • Ian B Gibson

    RPN calculator, binary clock, unix operating system, Lisp programming language, LaTeX document processing – the high road is a lonely road!

    Although admittedly binary clocks are just showing off, rather than being superior like the other examples I gave.

  • Costanza

    Ahhhhhh, the 15C. I began w/ HP when I was given the fabulous 11C as a birthday gift (Pardons if I don’t say which one). Ok, I’ll give myself a time stamp…it was a tremendous struggle to give up my slide rule (how many out there have ever used those? I still do…), but HP won in the end. Eventually I managed to get my hands on a 15C….all 3 calculators still cook (in a number crunching sense).

    Oh, Re #3: the energy DOES come from the vacuum.

  • John R Ramsden

    Costanza (#24) wrote:
    > how many out there have ever used those? I still do…),

    I don’t use slide rules these days; but I snaffle any I see for sale in junk shops and charity shops, and have now accumulated several dozen of all shapes and sizes.

    This is partly because they are nice things to own per se, and also of course they’re becoming rarer all the time and thus more valuable.

    The only one I haven’t come across yet is an ingenious sounding (and possibly mythical ?) complex number slide rule someone described to me some years ago. It comprised a helical slider embedded in a cylinder, with a sliding clear plastic outer cylinder, all with suitable graduations.

  • Count Iblis

    The HP 28s is not so energy efficient. I need to change the batteries every few years. It works on 3 N-Cell bateries, that we can’t get here in Europe in the regular shops. They only sell them at shops where they sell batteries for cameras and there they charge 15 euros for three N cell batteries (in the US they only cost $ 0.50 ) :(

  • Jim Harrison

    I’m not a 15C fan, but reading all these fond memories of an old technology, I’m struck with how many hardware and software products get worse as they are supposedly improved. The latest version of WORD for Mac is one case in point, but the same phenomenon occurs in games. The new editions have new features, some of which are actually functional; but the net effect of hanging a zillion doodads on the original product is often to produce a slower, less playable product. The latest version of EA’s golf game is downright decadent, the electronic equivalent of the Mexican Baroque.

    I know this is an old story and hardly limited to computer stuff–college textbooks often get worse from edition to edition, for example, which has even provided a business opportunity for publishers like Dover who make money by raising the dead. Why it happens is also pretty clear. From the producers point of view it is good to put out an excellent product, but it is imperative to put out a new one. And just as diabetes eventually makes your feet fall off, chronic marketing has a host of bad consequences.

  • Jon Hendry

    “Trent (#1 or #2), although your list is evidently intended to summarize the tastes of left-wing trendies, surely it’s possible to love one’s calculator and be as right wing as Attila the Hun or even Ann Coulter?

    Oh wait, Apple Macs were mentioned too. Hmm, yes I see what you mean now ”

    Actually, Rush Limbaugh is a big Mac user, and Karl Rove has an iPhone and for one of the primaries was seen on the Fox News set sitting at a MacBook Air for his political analysis gig.

    Some things transcend mere earthly politics.

  • Gareth Rees

    I inherited my HP-11C from my grandfather. He’s dead now, and whenever I use it, I think of him, and remember him teaching me to program it when I was six years old. It’s a gadget that spans the generations.

  • Eugene

    Here is the Mac OS emulator for Hp-15C

    20 bucks. but it’s worth it.

  • Z

    I’d much prefer if Wolfram somehow managed to get a version of Mathematica running on the iPhone

    THAT would be a truly compelling reason to get one.

  • Sili

    I miss my TI86 – no way near as durable as that. Gave out after ten years. I did once get a graph calculator, but I returned it when I couldn’t figure out how to use it.

    Don’t get me started on HPs though. Much too non-intuitive for simple little me.

  • Carl Brannen

    Hah! I own two of these though I only know where one is right now (nightstand next to bed). They used to be quite cheap, $29.95 if I recall, and I bought three of them at the University of Washington calculator store. Whenever I look at it, I idly wonder how much longer the battery will last.

    One of the cool features is that it has a huge number of storage locations. “recall xxx” is the command to recall a constant associated with the key “xxx”. I keep my favorite constants in various locations and use 0-9 for temporary storage.

    Way back in the day, there were other companies that sold RPN calculators. I had a Corvus which was considerably cheaper. Mine also had an amusing collection of chip defects that caused it to make errors that were occasionally noticeable. If you arranged for an even digit in the 7th location, i.e as in 555.555055, and you cycled the number through the stack, it would come back with that single digit changed to odd, i.e. as in 555.555155.

  • Nousha

    looks so complicated :)

  • andy.s

    All you brilliant quants posting here and yet you don’t realize that thanks to teh Intertubes, Nothing Is Ever Completely Off the Market:

    Get thee to EBay

    Go! And let the bidding wars begin!

  • catman306

    My HP 15-C has had a tough life, so the ‘2’ button sometimes fails to register. And my battery had to be replaced about 10 years ago. ‘Best calculator ever’ is really quite an understatement. Yeah, HP needs to start making these again so younger people can realize the beauty of RPN. I drove 200 miles to get one of the last ones in stock about 1990. I’ve never thought about that excess till this moment. I still have the manuals.

  • Trip Russell

    wow.. these calculators were built to last!

  • RogerF

    HP15C the Best Ever? Naturally! There is no competitor.

    The 15C was my second HP calculator – obtained after my HP35 died – they were both incredibly expensive by local standards which is why I (as an impoverished student & then engineer) sweated over each purchase decision – would it be the right one?

    The 15C is still my constant companion – in the briefcase every night so that I always have it at work or home! Rock solid, robust, and only one battery change in 20+ years. Used every day at work as well.

    I brought a 42S years later when the 15C was temporarily lost – wrong form factor, lightweight and fragile in comparison with the 15C. Gave it away to a colleague when I rediscovered the 15C. But it broke within a few years.

  • Ben

    I never had one of these and regret it, because I already had a TI programmable calculator and was too cheap to spring for another. I have a newer HP RPN calculator now, but the shape isn’t as adorable and the larger display uses the batteries up. Side note: my father bought the TI programmable calculator to teach me how to program; this was shortly before home computers dropped from insanely expensive to merely high-priced-for-16K-memory. The TI-57 was the least expensive model with a conditional branching instruction. I still have it and it works, although the rechargeable battery pack is long dead. This story sounds absolutely dinosauric, but I’m not _that_ old.

    Last week I was at the WIYN telescope and they had a couple of HPs on the desk for the observers’ use, which are probably older than the telescope.

  • Ben

    By the way, I really do not like the site. I don’t mind making fun of my demographic (wine-sipping Democrat elitist Appletards, or whatever we are). What bugs me about that site is that it stereotypes “white people” taste as affluent educated yuppie taste, and by implication, stereotypes non-white people taste as _not_ affluent educated yuppie taste. That ticks me off. There are plenty of non-white middle class people and affluent educated yuppies, with their own affectations and pretensions, but stuff like that site needs make them invisible to make its joke. I lived just outside D.C. for a couple of years, where there is a large prosperous black population and many ethnic communities, and there you’ll see lots of non-white people shopping at Whole Foods, drinking fancy coffee, riding expensive bicycles, typing on Apples, and doing most of the things listed (except maybe listening to David Sedaris).

    Yeah, I know, the site is a joke. But it’s a crappy joke. End of rant.

  • Count Iblis

    Z wrote:

    I’d much prefer if Wolfram somehow managed to get a version of Mathematica running on the iPhone

    You can already run Mathematica from any location as follows. You buy one of these handheld computers with internet connection. Install VNC and log on to your PC at the office :)

  • Mike

    I wrote an HP-15C (ish) emulator for the old Mac OS way back when, after my real 15C was stolen. It was shareware, and the absolute best payment I got for it was when someone sent me their own 15C, which I’m proud to say I still have.

    My programming masterpiece for this device was an “animated” hailstone sequence, the *3+1 … /2 game. (excuse me, the 1 ENTER 3 * + …. 2 / game).

  • Russ Brooks

    Funny you mention this, Julianne. I was at the OS X Terminal window not too long ago, and I accidentally typed “dc” rather than “cd” to change directories. The cursor sat there waiting for me to do something, so I realized that “dc” was a program of some sort. Additional research revealed that “dc” stands for “Desktop Calculator” and is one of the oldest UNIX applications in existence, predating even the invention of the C programming language – and still exists in our Macs to this day. Needless to say, Desktop Calculator is a “Reverse Polish Notation” calculator. This spawned a bunch of research about RPN which I logged to my blog:

    The article has some good links to other legendary RPN machines and some classic pics. Enjoy!

  • Philip Downey

    When I was about 7 years old (this would be the late 70s), I was given my first calculator, a small black Commodore with white buttons. I found it last year and it, with its original batteries, now about 30 years old, still worked. I was shocked.

  • JMG3Y

    Sharp EL-5100S Scientific Calculator (just pulled it out of my “archive” to check the number)

    Being of slide rule vintage, I’ve had a lot of different calculators, including HP’s and TI’s that I programmed, over the years but the Sharp was one of the best for just getting the job done, PhD and all, pre-laptop.


    I have a HP 10C, quite similar to the 15C except maybe for the battery which has to be changed every 3-5 years. I got it in France in the early 80’s and on the back it is still written: Fin de la guarantie: 29.06.1984. But it is still working perfectly and I use it every day. For the 2 previous decades I had a slide rule which I still have somewhere in a drawer.

  • Frank

    Being a computer guy, I bought a 16C Back In The Day. I still have it. I still use it occasionally. Working at Google, I’ve pulled it out once or twice just to impress the kids. :-)

  • Tim May

    The first HP-35 was just appearing when I was still in college. Way too expensive for me…I think it was $350 or $395. But it was amazing…I used to play with it in the campus bookstore.

    A year later, at a little company called Intel, I could afford one–with my own money, that is. The HP 25 had just come out, at a more affordable $150-175. It was my constant pocket companion for a year. I taught myself statistics, for analyzing experiments (Student’s T, Poisson distribution, etc.) And RPN was utterly natural, allowing rapid-fire calculations.

    By 1976 I decided to get an HP-67. Still my favorite for so many reasons. I practically wore out the keys doing calculations related to a chip problem we were having (alpha particles causing memory errors).

    Later, I replaced it with an HP-41C, but it wasn’t noticeably better, and by then I had a home PC (a Processor Technology SOL), and minicomputers at work, and less need for doing lots of calculations, so the era of HP calculators faded a bit for me. I did get an HP 11C, for portability, then an HP 28S (hated it), and, finally, some variant of an HP 48.

    Mostly I use the Mac’s calculator, set to RPN and Scientific mode, so it’s like some mutated version of HP calculators. Works pretty well.

    I’m long gone from Intel, by the way, and now favor Haskell over either Mathematica (which I used for a while) or Lisp (ditto).

    The iPhone looks interesting. Maybe when the 3G iPhone 2 hits the shelves, I’ll get one. And then rediscover the HP 15C?


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  • Sven DiMilo

    Man this is weird–I just mentioned my trusty HP15C last week over at Mark Chu-Carroll’s blog Good Math, Bad Math. I got mine my first semester of grad school because it did linear regression; I thought it was sent from Heaven. Still have it, still use it, though mostly for checkbook balancing these days.

  • etbnc

    Uh oh, I can’t find my 15C. I’d better sign that petition!

  • Martha

    I have an HP 11C that I bought in 1985. I can’t live without it (as an architect, it comes in very handy) and no other calculator will do. And I haven’t ever changed the batteries. Ever. (That still doesn’t make me want an I-Phone, but then I still have my 11C.)

  • Luc

    Hey, I am looking into buying a calculator for my Blackberry. I can choose from the 10B, the 10C and the 12C. Which one do you recommend? Thanks.

  • Greg

    Bought my HP15c in the early 80’s and I use it all the time. I love it!

    Thin. Elegant. Well built. RPN. Wonderful. When HP was still an electrical engineering company. The real HP is now Agilent.

    My iMac has an RPN calculator.

  • Jeff

    The HP15C was truly a classic – it was part of a series: HP41C, HP10C, HP11C, HP12C, HP15C & HP16C. All used precisely the same custom-designed 56-bit (!) HP microprocessor – the only difference between them was the final metal mask layer which slightly customized the microcode with the largest difference being between the 41 and the 10-seres. The clock rate of the 10-series is slower than the 41 in order to save power and and all are in the 100 KHz range which was slow even in its day (which was typically 2-6 MHz (20-60x); compare than with 2-6 GHz today – 1000x). The design of this family actually dates back to the mid-1970s yet the business brother of the 15C, the 12C, has remained in production. I still have and use my HP 16C – which has boolean and digital calculations.

    HP calculators have only gone down hill since the late 90s. Sadly at the turn of the millennium HP decided it wasn’t worth the effort to do much product R&D anymore. To quote their director of supply chains in 1999: “We’ll let Intel do our hardware R&D, Microsoft will do our software R&D and we’ll own the supply chain”. HP Corvallis calculator operations had already been moved to Australia and not long after in 2001 the Australian operation was shutdown and the calculator division was moved to Singapore. At that point calculator design and manufacture was largely outsourced.

    The result was the “return to the market mediocre” loss of RPN. Only market demand seems to have resulted in a grudging implementation in the latest versions. At this point you’d have to hold a gun to my head AND pay me to even accept possession of a new HP calculator, which is quite a reversal for someone who was an early and long-standing PPC member, 30-year user of HP calculators and 10-year veteran of HP itself! They are *so* bad. The sad part is they’ve lost the very thing that allowed the higher product margins which funded the features which locked-in engineering students and elite users who could afford the prices. Break the cycle and you have to compete with the dogs!

    The best hope for having a revived 10-series is to look to non-HP sources – i.e. the enthusiasts and hackers. This community has historically been amazingly technical. Back in the day these folks “discovered” synthetic programming which is a back door into the HP41’s firmware. I was a hardcore synthetic programmer back in college. Several calculator enthusiast groups on the web have voiced a desire (and sort of started) attempts to create from scratch RPN/RPL calculators in the original HP spirit.

    I think the biggest problem is they are probably biting off too much to both create the hardware and extend it. Reproducing an HP 15C with modern components without trying to go too far beyond is quite doable and probably with some impressive speed/power performance. A single current FPGAs could trivially implement the entire hardware of a 10-series which originally had several ICs (the original 10-series used an early form of surface mount).

    It’s always about time however. For example I’ve completely reverse engineered and built HP-IL (calculator networking for the HP41, HP71, HP75) from the ground up with modern off-the-shelf components but I haven’t had time to do much with it let alone document and publish how to do it.

  • Ferval Lankman

    On a whim, I did a Google search for a very specific attribute of my HP11C: I have never once changed its batteries since receiving it as a gift during my junior year of high school (’85-’86). It’s interesting to see that so many others have had the same experience.

    The days of smiling quietly to myself when people asked to borrow it and ignored my warnings of “if you haven’t used one before you probably won’t be able to add 2 and 2” are long gone, but this is easily the object I would miss most if it were to disappear off my desk.

  • Lou

    I had my HP15c from 1982 to 1983. I found that there was nothing
    that could do complex number calculations better (split stack!).

  • Carlos

    I am using athe hp 15c that belonged to may father , I have using since school to college, like 12 years almost, its amazing hoy it’s work, I think I’ll never change it.

  • Chris

    I used my HP 15C in college way back in the mid-80’s. It got me through calculus, physics, modern physics, statics, and circuits before my backpack got stolen. I’m not sure when they stopped making them, but I replaced it with a 28C instead of a 15C. The 28C is great and still works, but it definitely missed something compared to the 15C.

    I’d tried several of the other RPN calculators on the iPhone (including a very nice 41C emulator), but they never felt right and I had to hunt-and-peck too much to figure out the keys. When I saw the 15C emulator, I spent $20 for it (the most money I’ve spent on a single app).

    Here’s the weird psychological thing. I haven’t touched a real 15C in a bit over 20 years, but my fingers still remembered where most of the keys were and I can tap out problems pretty quickly on the iPhone. Even without tactile feedback, it “feels” like a 15C. As geeky as this sounds, I’ve actually dug out some math problems to solve just because I’m so happy to have a 15C again…

    Once I found a scan of the 15C manual, I was all set. They really don’t write calculator manuals like that anymore, either.

  • Bob J.

    My loyalty is with the HP-25 (my first calculator – got me through college) and the 41C (I practically did backflips when I noticed it had alpha keys – used it in the Navy to do all kinds of stuff). I own four 41C’s – got a bunch for free when a previous employer was junking theirs (replaced by PC’s). HP RPN machines RULE!

  • Alex

    It’s here! HP 15C emulator, $29.99 in the App Store.

  • Mike

    Having used my 15c since 1983 it has finally died. A very sad day indeed.
    Being a Land Surveyor it had a hard life out on site in all weathers. Having dropped it numerous times and expecting the worse ,it always survived. I think I replaced its batteries about 5 times over its life, say every 5 years. I loved it due to its size which fitted perfectly in your pocket,so robust and easy to use.
    Have decided to purchase a i Phone and obtain the 15c emulator.(but its not going on site)


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