A Calculator In 2020?

This week, Al Williams wrote up an article on what might be the last scientific calculator. Back in the day, the fanciest of scientific calculators had not just sin, cos, and tan, but were also programmable so that you could code in frequently used formulae. And the calculator that he reviews is certainly powerful: with a screen, processor, and memory almost rivalling a mid-scale smartphone.

Wait a minute! “Almost”? I have a smartphone in my pocket right now. Why would I want something less powerful, when all that the calculator brings to the table is a bit of software? And that app can even be purchased for $20!

I’ll confess. I want a proper desktop calculator from time to time. But why? Sure, I can run calculations on the very computer that I’m using to type right now. And in terms of programming languages, the resources are far superior on my laptop. Unit conversions? Units, or the Interwebs. Heck, I can even type calculations directly into the Unix world’s default editor.

But there’s something nice about the single-purpose device. Maybe it’s the feel of the keys. Maybe it’s because it doesn’t require a context-switch on the computer. Maybe it’s irrational calculator nostalgia. Or maybe it’s an elegant tool from a more civilized age: the user experience is better because the tool is just simpler.

I like stand-alone devices that do their one thing right, and I almost always pick them over their more complex, if also more capable, counterparts when I only need that function. The fixed wrench over the adjustable wrench. The standalone audio recorder over my computer’s software. The simple bench power supply over the programmable. And, when I’m actually setting out to take good photos, a real camera instead of my cell phone’s. Purpose-built tools tend to work much better for their purpose than devices that try to do everything.

The days of the standalone calculator are nearly gone, though, so what am I going to do? I’m certainly not going to shell out megabucks for an overly-fancy calculator, nor am I going to be lured by nostalgia into picking up an antique at the ridiculous prices they fetch online. That leaves one option, and it’s both the Hackaday and the Jedi way. I’m going to have to build it myself. Where am I going to get a nice-feeling numeric keypad?

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91 thoughts on “A Calculator In 2020?

  1. I bought a Sinclair scientific clone, running using a arduino board and I had some hopes of writing a new firmware for it (long, long term project) since it is not as limited as the original calculator chip it is now emulating.
    Why a stand alone calculator? Because it is made for one thing, have no distractions and does it well.
    (The last part might not be true for the Sinclair but the name and history makes it worth having.)

  2. “But why”? Really? Because touch screens are horrible for fast, accurate input. No tactile feedback. There are hilarious autocorrect memes for a reason.

    I wish calculators had better tactile differences between keys, but at least there’s *some*.

    1. Yeah although the numpad on my mechanical keyboard still feels brand new.

      That can be a treat if you build your one handed numpad skillz . I’m always envious when I can hear the telesupport person hammer in my reference number in a split second.

      1. No, not really. Any USB number pad ought to work just fine with an OTG or USB-C adapter as apropriate. But why? I just checked Fleabay. Bluetooth number pads start at just 88 cents with free shipping! It looks like a higher quality one might cost as much as $15.

        So… tell me again about smartphones vs dedicated calculators and the value of real buttons!

        1. So let me get this straight: you want to carry around an additional separate number pad for calculator entry on the smartphone? An additional, separate device… so you don’t have to carry around a calculator?

          Isn’t that the same as… y’know… carrying around a calculator?

          1. Of course not! The phone by itself is fine for occasional casual use on the go. The number pad stays at the office desk or workshop for use when there is a lot of work to be done.

  3. My 20 year old nephew, whom recently completed his masters in computational physics, has been after me for several years for at least one of my three HP calculators. So, soundly based on a sample of one, I do not think that the hard-corps technoids will allow the ‘stand-alone’ calculator to die.

    My oldest ‘professional’ calculator is an HP11c (bought in 82 upon my military discharge as part of my school kit). The calculator that sits on my shop and lab benches is an HP15. And the calculator that sits on my desk is an HP42s.

    Perhaps I will give the kid an HP11…

    1. I have a slide rule I’ve used no more than 4 times in my life.

      When it comes to oldskool it’s not all about usage.

      Maybe he’ll turn your hard working HP into a shelf queen, and won’t that be a sad thing?

      1. I still have a slide rule. I used to use it frequently (around 2010) when doing field work in inclement weather. I had a really good hand calculator (some metal case programmable casio), but it wouldn’t work reliably in extreme cold.

        Only problem was RNG isn’t a thing on a slide rule. So I started carrying large, brightly coloured dice from tabletop role playing games, and built sampling grids around what the dice could generate.

        My GPS kept failing too so I switched to compass and bearings.

        It was an interesting experience that got me interested in IoT — as I shivered in the snow and mud measuring things, I couldn’t help but think ‘Don’t we have machines to do this?’. Now I run a company that largely makes machines to do that… but I still have my slide rule, just in case.

      2. It would be good to teach engineering students to use a slide rule, since it helps to better understand number relations and also the significance of X-many digits especially in different ranges. I still use a slide rule once in a while to sharpen my mind. When you’re skilled at it, it’s not really any slower than a calculator. What got me to convert 40 years ago was that the slide rule was not programmable, and I needed to be able to run programs with thousands of loop iterations.

  4. I use a stand-alone calculator because it’s simply faster to do a simple calculation. It’s slower to start the calculator app and then enter the expression using the general-purpose keyboard than just grabbing the calculator pressing the “on” button and enter the expression with the specially-designed keyboard.

    Now not to scoff at the desire to make one, but a quick look at staples.com shows almost 50 models to choose from, many quite capable scientific units less than $20.

    Even then, designing a calculator exactly the way you want is a great reason to make one. The display, CPU, and software is not much of a problem, but you put your finger (pun intended) on the biggest issue: the keyboard. Unfortunately Cherry doesn’t make calculator keyboard switches so it would have to be something custom. Swiss Micros, a two-man shop, did it with their HP recreations, though.

    1. Cherry etc. mechanical keyboard switches have a great “feel” – but take up a lot of real estate. There are a variety of keycaps, but they stand quite high.
      Once you get into fancier calculators, you need more [smaller] keys AND the ability to have more than one function per key. With custom keycaps, you can add text to the front side to augment the top. With smaller keys, you can add text to a backing plate that goes between keys.

      Keep the number of keys below 80, and you can use the TCA8418 encoder (I2C protocol). If the LCD control, power, and “brain” CPU / microcontroller are on a 2nd PCB, you could even experiment with different keyboard types without starting from scratch.

  5. I wrote a much longer comment but it got lost, so here is a shorter version.

    My daily driver in power electronics grad school is the king of TI calculators, the TI-92+. While it is a bit overwrought for most calculations, I love it for its native (no context switching required) symbolic calculations and dimensional analysis (many times saved my calculations from unit conversion errors), which place it above Matlab and most TI calculators I’ve used for small daily calculations. The full qwerty keyboard places it above the 89 and Nspire CAS because it lets me easily type in function names without using menus, while the AA batteries place it above its direct successor, the Voyage 200, in battery life.

    For simpler math on the bench or at home, I use the TI-36X Pro, which I bought for a single class in undergrad that required it.

    For harder stuff, I go straight to Matlab when its available.

    I’m sure a similar HP calculator could work just as well or better for me, but the 92+ is what was given to me when my high school calculus teacher was cleaning out her closet and it’s been with me ever since.

    Regardless, nothing beats being asked “Is that a computer?” every time someone new sees me using it.

    I still wish for a scientific calculator like the TI-36X pro that also lets me write custom functions for it, preferably without having to battle unfamiliar, confusing syntax, so I can do basic EE math (like filter calculations or resistor parallel/capacitor series) quickly without having to lug my heavy 92 around.

  6. I can use the numeric keypad on a keyboard. But I feel more comfortable and sure of my numbers when I lean back and use both thumbs on my calculator. The HP keyboard bump lets me know my number is there. My muscle memory let’s me build up speed. I can never build up any confidence entering data for my calculations on my phone, my fingers are too fat and I have to concentrate on where my fingers are instead of what I’m thinking.
    I’d be fine with a Bluetooth keyboard that felt like my HP 48G+ (Or my old HP 25) but did all the calculations on my phone or computer.

  7. Hackaday calculator checklist..
    * tactile keyswitches
    * dot matrix gas plasma with nixie emulation mode
    * LiPo battery with solar and hand crank backup
    * Runs CP/M
    * Runs OS/9
    * Runs BeOS
    * Programmable in HPL
    * Programmable in Python
    * Default use of Tau instead of Pi
    * 2.4Ghz and 5Ghz wifi
    * Network addressable API
    * 16 channel ADC
    * Tricorder mode
    * TEMPEST shielding
    * Fourier based wave form synthesis with audio level and RF outputs.
    * Dimmable power on LED
    * Shoulder holster
    * Speak’N’Math emulator
    * Magic 8 ball mode

      1. Of course, it’s multiplexed with USB-C, HDMI, one PCIe lane and MIDI over the 5 pin DIN… currently having problems finding someone to make a breakout dongle smaller than the calculator.

        1. I’m looking into modernizing an ancient BINGO flashboard and it’s looking like the least expensive way is with a RasPi Zero. All it’ll have to do is control 80 LEDs – while having the computing power to emulate an original Playstation. But for $5? I doubt there’s a dedicated programmable LED matrix driver so cheap.

      2. I got into the HP-41cx and HPIL and Extended I/O modules specifically to be able to use it as a hand-held controller for a lot of lab instrumentation, going through the HP82169A HPIL-to-IEEE488 interface converter. It was nice to have a small unit that I could easily take with me from my desk to the workbench and back, and was much easier to program than the laptops of the day (which were almost non-existent at that time). I interfaced to signal generators, programmable power supplies, DMMs, relay boxes, plus the usual printers and mass storage, all at once.

      1. YAY 4 Forth!

        What do I want?
        An Org/Babel-PDA!

        I’m doing all from literate programming to reproducible research (like polyglot Jupyter notebooks) in Org/Babel. Addicted! I confess! Org’s PIM stuff is not my thing and I’m not married with Emacs. If I could get Org/Babel features without Emacs, I’d definitely try it.

        Well… a Pi0 already should be enough, but I still haven’t found the keyboard and screen combination I’d like to have in a pocket size form factor. The last ones I really liked were Psion5 and HP Jornada 7xx. A netbook is too big, a screen-only device is not my way. And a battery charge should give at least 18 hours of runtime! Really running! That probably kills the Gemini PDA from my wish list?

        My dream PDA probably only exists in heaven.


        Or Easter-Bunny!
        Prove me wrong!

        Ok… alternative dream: Keep all oooomh @home and use only a mobile teminal… can we (“the dimension Hackaday”) do that?

        I had a “really don’t think twice about it” cheap mobile plan for a while with only ISDN speed (cap’ed 2.5G) but 8kbytes/s is a lot for a text UI with MOSH. A small OpenWrt system (400-600MHz) with nice keyboard and screen would do it! But that still lets the keyboard and screen questions unanswered. The netbook was not mobile enough for my taste and yet the battery was not fat enough.


        Ok… more caffeine and then back to work…

    1. You missed the most important thing in a calculator- the keys. Nothing beats the buttons in the old HP calculators. My 36 year old HP-11C works like new and the buttons are as close to perfection as has ever existed, and will probably never be duplicated.

      1. I have collected old calculators for ages, but my collection has grown the most int he past 10 years. I have ancient discrete component gems from approximately 1965, like a Friden EC132 and a Smith Corona-Marchant (SCM) Cogito 240SR. Both use CRTs as displays! I have a Sperry Rand Remington 1259S scientific, which uses Nixie tubes as it’s display, and does not blank the screen while it performs calculations… Which is a TRUE JOY to witness! My Monroe Statistician 344 uses a Panaplex display, and is the size of an old portable cassette recorder from the late 1970s. The 344 is portable, and ONLY takes 4 “D” batteries to run! XD

        Video of the Sperry Rand Remington 1259S in operation.

        I also have stacks of handheld calculators. Commodore N60, S61, and P50, TI30, TI59 (with the printer base accessory), and just more than I can even name off the top of my head. Thing is, with the portable ones, I keep them strewn all around my place! On my workbench, I have the trusty TI30. My computer desk has the compact Commodore SR7919.

        I can vouch for the value of key feel. There is something satisfying about the tactile feedback of a physical button press. Whether it’s the fine perfection of an HP key, the tactile feel of a classic Klixon keyboard, the satisfying “kerchunk” of a mid sixties desktop monster, or the simple feel of a modern key. Heck, even the terribly spongy keys many Commodore or soviet era Электроника calculators were infamous for… Still have more in their key feel than merely tapping a screen or clicking a mouse.

      1. It’s sorta possible, but you only get one gate per 555, and using that gate 4 at a time to build other gates winds up to more 555s than can run off a 9V battery for half an hour.

  8. you must not have high school going kids. High schools mandate scientific calculators (vs any other computer/device) of specific brands to eliminate possibility of cheating. that’s why likes of TI can get away with charging hundreds of bucks for $5 worth of electronics.

    1. The components in the high end scientific calculators may not be expensive or hard to find now. But what happens when you drop your smart phone or laptop from even a tiny height? The build quality and its inherent reliability have a value of their own. One reason why I still like abacus and slide rules enough to try and keep my eye in with them (though I did not grow up with them) they work just fine no matter where you are.

      1. Bah, the last TI-83 we bought had been so cost-reduced it’s embarrassing. The flex circuit to the display got guillotined on a PCB interposer board glued to the back of the display, so it’s dead. Everything inside is the cheapest crap imaginable, un-sealed, loosely mounted, and chintzy. Coasting on .edu penetration.

        Even my HP-48GX died when the keyboard stopped responding. No parts availability that I could find, unfortunately. For the last couple of years I had to squeeze it just so below the LCD bezel to make contact and even that quit working.

        The last calculator I bought was a Swiss Micros DM16L and it’s beautiful. I’ll probably be buried with it. I’m eyeing up the Numworks machine too.

        1. Your HP-48GX probably isnt quite dead. Apply some pressure near the bottom of the screen while pressing the dead buttons, they might respond. Google it, its a common and unfortunate issue with what is otherwise an indestructible calculator.

    2. And university. No school will let anyone use a general-purpose tool during a test. Ever.

      This is a monopoly to outlast time itself, until some chinese manufaturer of cheap calculators takes on the effort of convincing schools to allow their inexpensive “TI-compatibles.”

    3. That’s funny, because when calculators first came out we told we could bring them to class but no way would they be allowed in the exams. One justification for the ban was that only rich kids could afford them.

      But I am still using the Casio fx-180P I used in school. The case is a little chipped, bu still works fine. Another 10 years and I might think about replacing it :)

  9. I keep my old high school scientific calculator because it’s *solar powered*. Still works decades later, no batteries to replace or corroded ones to clean out. Always halfway dreamed that, come “the collapse of civilization”(TM), I’d be prepared to help rebuild.

    1. I bought a scientific calculator from Radio Shack (too poor for an HP)n ’83 or ’84 for my first attempt at college. It ran on two AA batteries.

      Sometime last year, the original RS batteries finally died. I was sad.

  10. Hp35s is not too expensive and feels like a culmination of the hp scientific calculators, leaving behind the stuff a computer just is better at (hp4x) and returning to a more solid feel. Why build one, when this exists?

    1. There are numerous annoyances with this particular model, but sticking to the keyboard issue, I’ll say this. It drops keystrokes. Afaict the individual keyswitches are reliable enough, it’s that the processor/software is too slow. I got the 35s hoping to not wear out my aging 32s, and was hoping .. for too much I guess. With the 32s I can go my flat out fastest and it never drops a key, but with the 35s, it’s goooo sloooow and still watch that every key registered correctly. Renders it about useless in my opinion. And the old 32s just keeps on trucking

  11. Back in the 70s I got a TI calculator for Xmas and was happy to have it but my teacher’s HP calculator just felt *solid* and getting used to RPN was like joining a secret society.

    UNIX editor? Whatchoo talkin’ ’bout Willis? Just put your calculation into Google.

  12. I dunno, was about to buy a DM15 for my nephew, but talked to a guy that had problems with the keypad and LCD after a year of use of his DM15. Do a search it appears that there may be a material and/or manufacturing issue.

    1. I agree with all previous comments on how it feels better to use a purpose built tool that does it’s job perfectly over one that tries to do it all but is often average in everything.
      On the calculator part, I also need to have a real proper keyboard and even if there great calculator apps, the phone just keeps turning off the screen because it can’t compete with the ultra low power consumption of calculators so it is also very annoying to press the wake up button, login in and then finally accessing the calc app again…
      I own an old hp32s like in the article and an hp48g with its slightly different use of the stack which in the end I prefer !
      I always liked microcontrollers and the use of RPN always felt more natural to me though I truly understand why Casio or TI fanboys prefer to enter their calculations just like we write them.
      I just started with HP and I’m now wired for it :)
      There was a time when I would use it everyday for my job and back to some friends I had to use a 1€ calculator, I can assure you that I felt dumb when I had to start over 6 times before entering the numbers and operations right without forgetting to hit the equal button ;)

  13. The reason why calculators and other such widgets have a place in my life is because my phone has personal information on it, and must perforce have a strong passphrase. The awkward, buttonless interface makes typing the passphrase a relatively cumbersome affair. If you are “securing” your phone with a four-digit PIN or, God help you, biometrics, you are playing with fire security-wise. Eventually, you will lose your phone and be in a world of hurt if anyone less-than-saintly finds it.

    1. If you work in a secure area, there’s no way you will be allowed to carry a mobile phone.
      Unfortunately, security won’t be happy to see a home built calculator either. Getting authorisation for such a device would be *possible* but a headache.

    2. The phone won’t last either, which is one of several reasons I don’t use a smartphone. My wife and son have had quite a few, and invariably after a couple of years major portions begin failing, in spite of the ridiculously high prices (hundreds of dollars to over a thousand). My HP-41cx from 1986 is still going strong, and I have had some of the programs I use most in its memory continuously for 25 years, without ever re-loading them.

  14. I often have so many tabs open that the last thing I want to do is open another tab! My goto is an old Radio Shack solar, but my heart will always belong to my SR 50. Costing almost a full month’s TA salary, it got me through EE grad school.

  15. I don’t think your analogies are very good. An adjustable wrench is an awful replacement for a fixed wrench. I have no issues with a programmable power supply, and for bringing something big up the first time, having something you can set a current limit on it a good thing. If you like your hand held calculator, that is great, no need to justify it, just be happy there are still a lot of them available. I will admit that I am not super happy with touch keyboards, but I am also not happy with carrying around a briefcase full of devices. My phone does a good job at so many things. It is a phone, I can at least check my mail, I will admit replying with the little keyboard is a pain, but in a pinch I can also dictate to it, and for someone who is pretty old school, I have caught onto doing that pretty quickly. I don’t need to drag a GPS from car to car anymore, my phone covers that, and again I can ask it to navigate me and not have to type in where I want to go.. I have a voice recorder, a video recorder, a camera, a language translator, oh, and a calculator all in a little monolith I keep folded up in my wallet. Perhaps I am a convert, but the convenience far outweighs the bother about the keyboard. Also, unless it is solar powered the chance of the batteries being alive in one of my physical calculators is very very low. Curable but another bar to the pick it up and go mentality.

  16. My wife (and I) uses the HP-12C and it sits upstairs in the Kitchen. My HP-15 and HP-16 is what I use in my library/work area. No way would I be without my HPs with RPN. Granted I don’t use them a lot any more, but still… Now, I have used TIs (even have a cheap scientific solar one at work because if stolen, it’s no biggie), but really can’t understand why they are so popular compared to the nice RPN calculators….

    As for smartphones …. Some people shake their heads, as I use it to just ‘phone/text’. It was required for my work (on call times) . Otherwise I probably still would not have one. Land line works great. If people want to get a hold of you they can leave a message if your not home…. No reason to be connected 24×7.

  17. I’m sure I remember a third party keyboard for the “IBM PC” that included a simple calculator. I can’t remember if it used the number pad keys or were more standalone.

    Calculators aren’t likely to disappear completely. I’ve seen scientific calculators in dollar stores that have the same functions and layout as my Casio from about 1988, except real cheap. I assume they bought the IC or maybe just the design as the company moved on.

    TI and HP aren’t the only scientific calculator makers. Casio still makes them, so do I guess it’s Sharp. The latter have up to “472 functions” and about $20 Canadian. Not RPN, and not programmable, but more than enough capability for many. The Sharp even do hex and binary, and octal, and some logic operations, unlike my circa 1988 Casio, which only handled octal, binary and hex, so it couid convert between them, but only did arithmetic, not logic operations.

    I did get a TI-83+ a few years ago for seven dollars at a rummage sale.

    1. That would be the Focus KeyPro FK-9000 with a switch to toggle the numpad to a calculator. It also had two columns of programmable function keys on the left end – programmable from the keyboard so that works with any computer the board can be adapted to. There’s a NiCd battery that charges from the keyboard port. They work fine with a PS/2 adapter. They have 8 arrow keys surrounding a Turbo key that changes the repeat rate. There’s also an adjustable angle piece at the top which holds function key guides and it included preprinted ones for popular DOS office software, and a few blanks.

      I have two of these keyboards. They are HUGE. 20.75 x 7.25 inches. Not my daily driver because with my current main use desktop I’d have nowhere for my M570 trackball. Hmmm, perhaps I should see if I can acquire an FK-9200?

      The FK-9200 had all that plus a small trackball below the spacebar.

      The one thing they *don’t* have but should have is a way to dump the output from the calculator into the computer. That would make one especially useful for spreadsheets. Click on a cell, do your add, subtract etc then *pop* the result into the cell.

      I would dearly love to see a modern version of this, with the calculator able to feed into the computer, and with the key layout slightly altered. They have the reverse L Enter with the big Backspace above it. Unfortunately the backslash is taking a bit off the right end of the right shift. That could be fixed by moving it to where the Prog key is between the right Alt and Ctrl. Move the Prog key to a special button out of the way. There’s a blank key that does nothing between the left Ctrl and Alt, change it to the Win key. Then lop a little off the right end of the spacebar for the menu key. That would be perfection.

      My first PC keyboard had the “Big Three” layout which literally zero keyboard manufacturers have made since the introduction of the Windows keys, because they all move the backslash to take a chunk out of Enter or the right shift. I’m currently typing on a Gateway KB-2961 which has the full sized right shift and backspace. Backslash is where the vertical part of Enter is supposed to be. On my first keyboard I always hit the upper part of Enter and the left end of right shift, the two most common refugee relocations for backslash on WinKey boards. The FK-9000 is tolerable because it took off the right end of right shift for backslash to make room for Prog.

  18. I used to work at TI in Richardson, Texas. When I started on the job I brought my stuff including my HP-11C calculator that I had for 16 years after it replaced a failed TI-58 that had lasted about 2 years. It was on my desk all the time and I used to get a lot of snide comments about it, but fortunately it never disappeared. Of course, I only worked there for about a year…

    That calculator is still in daily use. In the 36 years I have had it, I think I replaced the batteries 3 or 4 times. The little rubber feet on the bottom are finally coming loose and the HP logo came off years ago, but the keyboard is perfect. Somewhere along the way I bought an HP-49g+ with a horrible keyboard that failed in about a year.

    You can have my HP-11C when you pry it from my cold, dead hands.

    1. Pickett slide rule for trig and a Sears (Bowmar) 4-banger got me through undergrad, followed by an HP-25 for grad school (still have it) and an HP-41C after I graduated (still have it, too).

      Now it’s 41C emulators on Linux, Windows and my iPhone.

      But nothing has the feel of those HP keys. When I was in college it was TI vs HP and HP won on the strength of their keyswitches. I knew too many TI owners with flakey keyboards. Learning RPN was the price I had to pay for reliability, but it comes naturally now.

  19. I still have the HP-67 I got while in college but my daily driver is my HP-16C. I literally use it every day. Much faster and easier than launching an app on either my phone or computer.

  20. As long as we have universities we will have instructors that insist we use scientific (not even graphing) calculators for tests. One of my physics teachers even had a prohibition against anything with letter keys and would make you remove the cover and leave it in a locker before entering the test room. Pretty annoying when you are used to using a good calculator and now you have something with a whole different layout and a character lcd with no backlight.

    1. Testing/test taking will allow most calculators but insisting on clearing memory before test. No possible way to bypass that problem. Ha. Absolutely no cellphones allowed.
      The idea is to remove cheating. Doesn’t really stop anyone with basic electronics knowledge from doing so. Z80 based TI. Sooo hard to hack. Heee he he. NOT.
      Wide selection of cheap FLASH and micro sized WIFI that should fit nicely in casing. I’m sure no one has ever considered using NRF24L01 or an ESP-M in a calculator.

  21. I’m currently reviving my old Casio 161K desktop calculator.
    It has 16 digit nixie display, reed switch buttons, and pmos/fairchild LSI smarts.
    Problem is that replacement silicon is unobtanium, so it’s getting a drop-in replacement board (no modifications to the original parts or pcb!) with an Arduino Nano and a bunch of I2C I/O expanders.

    The trick I gotta work out now, is to find something more compact and elegant to use for the cathode transistors.
    Using MPSA42 and MPSA92 transistors means using 32 transistors for the 16 nixies… A little unwieldy….

  22. You are not the only one I’m accountant and simple big button big display calculator is one of best tools i have. Yes i can use excel i use accounting program but if i just need to add multiply divide and so on bigger numbers than my brain can process fast then calculator is best. For complicated calculations theres excel of course.

  23. Do those of you who have a fondness for “real” dedicated calculators carry them around with you? Or do you just have it in the place you are most likely to use it. In the latter case having a matching emulator app on your phone could come in handy for occasional use.

    I can’t imagine actually carrying a calculator around with me. Most pants come with two front pockets. One gets stuffed with wallet, the other with keys. I have enough back problems without sitting on my wallet and I never did do that anyway after watching a news report about pick-pockets as a kid. And people that spends 100s of dollars on a smartphone only to sit on it and crack the screen? Yah, I’m going to teach my daughter to watch out for guys that do that. It has to be a sign of wastefulness and irresponsibility.

    So, all that means I already have one very un-cool belt holster for my cellphone. I so miss the 90s or was that the 0s when cellphones were fat, everyone wore holsters and it looked normal! One is bad enough. A second one for a calculator? No way!

    And all that really even applies if you are using it on a regular basis. Don’t get me wrong, I do occasionaly use my HP48G emulator for more than simple arithmetic. But it’s a rare thing. If I had a dedicated calculator I would probably go to use it one day only to discover the batteries leaked and all the contacts are corroded!

    Did I mention that I also don’t like batteries?

    1. ” I already have one very un-cool belt holster for my cellphone”

      Greetings, fellow engineer!

      I have a leather one from Duluth. Because otherwise I would destroy my pricey hand-me-down iPhone

  24. I often see those simple calculators at almost every shop near me. The same shop keepers own smartphones too and are well aware of it’s calculator functionalities. Also, the physical calculator they prefer doesn’t even have basic trigonometric functions (although it costs roughly $1.5~$5). If I had to press those same keys every 20sec ~ 8mins for 14 hours a day, I would prefer a cheap simple calculator rather than an expensive smartphone, for many reasons.

  25. I keep a calculator app pinned to my start bar for verifying my math before running it in code. But I never use it, I use a Casio FX-260 Solar instead. Why click an icon and wait a second for it to appear when my Casio is literally always on and ready, as long as there’s a light on. It makes even more sense considering I use a TKL keyboard, though even if it were full-size the Casio still offers a much more feature rich keypad and in a smaller space as well.

    You can buy the Casio FX-260 Solar II for $8. If you don’t mind pressing an On button before getting started there’s the $16 FX-991EX with a large textbook display and extra features like base conversion, or the $50 HP-35 programmable RPN for all you hipsters out there, and the $100 NumWorks open source graphing calculator that runs on Python for Linux fans. If none of these modern calculators do it for you there’s guaranteed to be something that fits your niche on eBay. I’ve been eyeing the Casio CM-100 personally.

  26. Elliot W. says he doesn’t want to spend a fortune in buying an antique on eBay. Fair enough… me neither!

    What I do is to drop in at every thrift shop, Goodwill store, and yard sale that I drive by! It only takes a minute or two: the person either looks at you like you have two heads (“What? An HP calculator? Why would I have one of those?”) or they say “SURE!” and show you one.

    This worked a lot better before COVID, so you might have to wait another 6 months (by which time you might have your project all built and tested!)

    I have a fairly big collection of them now, most of which I’ve purchased for $20 when they sell for $90-200 on eBay. (Most sellers only want $2-10 and when I tell them they can get it for a LOT more, they generally still won’t bump up the price by much.) This includes an HP-48g and an HP-32s II. Both powerful engineering workhorses.

    A few of the more valuable ones, I’ve paid $50 or $60 (my HP-11c and 15c come immediately to mind).

    My only splurge was an HP-16c “Computer Programmer” (a rarity), in MINT condition, that I found online for about $200. Most sellers were looking for double that; I had “birthday money” and decided that I’d really like to have it BEFORE I retire, so I could actually use it in my profession.

    BTW, if you really want something NEW, fast, and modern, but in the spirit of the old HP engineering calculators, you might do a web search for a company called “SwissMicros.” They make some HP-workalikes that are NICE!

    Hope This Helps!

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