1973: When Calculators Were Built Like Computers

Should you ever pick up [Steve Wozniak]’s autobiography, you will learn that in the early 1970s when his friend [Steve Jobs] was working for Atari, [Woz] was designing calculators for Hewlett Packard. It seems scarcely believable today, but he describes his excitement at the prospects for the calculator business, admitting that he almost missed out on the emerging microcomputer scene that would make him famous. Calculators in the very early 1970s were genuinely exciting, and were expensive and desirable consumer items.

[Amen] has a calculator from that period, a Prinztronic Micro, and he’s subjected it to an interesting teardown. Inside he finds an unusual modular design, with keyboard, processor, and display all having their own PCBs. Construction is typical of the period, with all through hole components, and PCBs that look hand laid rather than made using a CAD package. The chipset is a Toshiba one, with three devices covering logic, display driver and clock.

The Prinztronic is an interesting device in itself, being a rebadged 1972 Sharp model under a house brand name for the British retailer Dixons, and that Toshiba chipset is special because it is the first CMOS design to market. It was one of many very similar basic calculators on the market at the time, but at the equivalent of over 100 dollars in today’s money it would still have been a significant purchase.

Long-tern Hackaday readers will remember we’ve shown you at least one classic calculator rebuild in the past, the venerable 1975 Sinclair!

55 thoughts on “1973: When Calculators Were Built Like Computers

  1. Today, you think of a calculator as one of those things clogging your kitchen junk drawer, probably acquired at Walmart for $5. You don’t use it, because you can do calculations with your phone or computer.

    When HP made scientific calculators in the 1970s and 1980s, there were no phones or computers that you could use for that. They made billions of dollars. That’s billions with a “b”.

    1. Exactly. With the one exception being my HP-16C, which I still use about once every 2 days.

      I wonder if Woz worked on that? I don’t think so, it was only released in 1982.

      But just think about this: I have an Apple II which sits on top of my bookcase as a display item. While my HP-16C is in my backpack getting almost everyday use. Which designer deserves more praise? :)

        1. dec/hex/bin conversions, N-bit math (where N is from 1 to 64, but generally 8, 16 or 64 bits ;)), boolean arithmetic, bitwise operators, and all sorts of ‘normal’ calculations, and some basic statistics.

          What I like MOST about the HP-16C is that it just has basic functionality, and everything is reachable through one button. The keyboard layout is really the greatest thing about this calculator. And the fact that I can do arithmetic in any bit-width from 1 to 64 bits, unsigned, 1’s complement and 2’s complement.

          1. Thanks for responding to my question!
            I have a 16C, but it is mostly collecting dust (no, I won’t part with it, I’m a bit of a hoarder B^)!
            My recent string of jobs have very little use for its capabilities (sigh!).

      1. interesting; I myself never found the 16 that compelling and just stuck with my 11, so I’d be curious as to what you find useful — might learn a new trick.
        FYI, the 16 was apparently a “skunkworks project within R&D”. I base this claim on a video of a talk given by an HP employee at the time who was project manager for the stuff. This video is principally about the 12C’s continued tenacity in the marketplace, but they discuss general Voyager topics. Someone asked if there were other planned but unreleased models, and the presenter said ‘no’, but also commented that the 16 “was a skunkworks project within R&D”.
        Q.v. at 22:15 mark:

        1. If HP wouldn’t have created the 16C, I might have made something like it myself. :)

          To be honest, I also have a Casio does-it-all graphical calculator. It can do everything that the 16C can. Just not instantly after switching it on. And it has too many keys. Or more precisely: it has enough keys, but they’re all mapped to stuff that I don’t need. And to get to the stuff that I do need, I have to press a lot of different keys, changes modes, bla bla bla. Just not practical.

          1. I bought a used graphical Casio years ago for $10.
            To me it wasn’t “intuitive” when trying to do bin/dec/hex conversions, or other stuff, even though it came with a thick manual. I ended up giving it to charity.

          2. Lol; I had plans long ago to make a ‘cryptgraphic calculator’. I have a sundry of little command-line tools for doing things like DES and RSA primitives, and fintech algorithms like PVV CVV DUKPT etc. I always loved the design of the voyager, so I started to ‘rebrain’ a 12C with a PIC32. I got this working electrically, but the LCD was not pretty (2×16, but way shorter than the voyager display) and I had a little difficulty getting all the stuff in the case since I wasn’t laying out a custom PCB to replace the existing one.



            maybe I’ll get back to it one day!

          1. teehee; yes hacking up a specimen of any other of the species would be sacrilege, but a 1994 12c seemed reasonable.
            I was on MoHPC before they changed infrastructure and I lost my identity — not really active, but I did post about this work. It was received positively, though folks were particularly interested in my technique for removing the various plates, and also about measuring the actuating force for the snap-domes. Too much calculator will do that to you, I guess; lol.
            After that, an small company of enthusiasts made some reproductions. I reached out and said that I might like to hack their calculator, and if they would mind my doing so. But it turned out the platform at that time was too weak for the crypto I had planned, however they planned another that was definitely strong enough. We spoke for a couple years, but at one point they got angry at me, complaining that I had leaked secret advance info. This was completely untrue (and anyway I had nothing anyone without a voltmeter on ‘continuity test’ couldn’t independently discover as I already had). But out of respect I withdrew from that scene. An aftermath of that commotion was my making a little project doing a knockoff of the HP infrared printer, making a receiver for the IR from the calculator (which has some challenges) and rasterizing it and putting it out on a thermal receipt printer (which has a separate set of challenges).
            So something good comes from something bad.

    2. Funnily enough, my favorite smartphone calculator app is the one that shipped with the Palm Handspring Visor. It can do trig, hex, statistics, basically the only thing it doesn’t do is simplify equations and graph. It’s the only touchscreen calculator I’ve seen that is actually worth it to use over a standard physical calculator.

    3. I just grabbed a calculator from the “still good” shed at my town dump – inside, there’s a hand-written date code of “1973”.

      The reason I grabbed it was the ergonomics – the keys are mechanical with a satisfying “snap” when pressed, the display is a bright LED with lensed bevels, and the whole thing fits in your palm and can be used one-handed.

      Then I want to the dollar store and compared with the $5 POC mentioned in your post. Membrane keys with no tactile feedback that you have to mash forceably to get a reliable press, credit-card format that has to be used with both hands, LCD display with low contrast that can’t be read in dim light, with a bezel that reflects surrounding light.

      I’m constantly impressed with the awful calculator interfaces on my home PC as well. The default calculator on linux mint requires the square-root operator to be placed *in front* of the numbers, so you can’t enter, say 9-9-9-sqrt, you have to grab the mouse, click before the first 9, and then enter the sqrt operator, then press “return”.

      The Windows calculator had a lot of bad aspects as well – there’s an X^2 key, but no sqrt key, and you can’t click to select the results, you have to use edit->copy, and then you get the entire number instead a subset if that’s what you wanted.

      Those old calculators are useful if for nothing more than the ergonomics. They’re wonderfully easy to use.

      1. I carry a Dollar store Scientific Calculator in my backpack, but before I bought it, I tested all the keys for function as well as all the display digits. Two others on the peg failed that test. It does Base conversions, metric conversions, trig…

        1. Oh, come on… if you want a really steep learning curve, use ‘bc’ on Linux. Like ‘vi’ when it comes to editors, it can do a LOT, but it takes a while before you get an idea how to make it work.

          And if you want RPN, look at ‘dc’.

  2. Olivetti Programma 101 is the gold standard of coolness in old calculators.

    RetepV: sorry the Apple II wins this contest. Every human with a computer is getting daily use of technology that originated from the Apple II. The number of people on this planet who can get useful work done on an HP calculator is vanishingly small, HP’s efforts to teach the world RPN were a dismal failure. Indeed which designers deserve more praise?

        1. I’m sure that RPN was only popular since it was easy to write an expression parser with operator precedence. Having said that, I do have a few HP lookalike apps on the phone, but the display doesn’t go blank for a few seconds while the result is calculated, as the real ones at University used to in the 70s.

        2. Every Apple computer shipped today includes an RPN calculator. Two actually. The graphical one has an RPN mode and dc, the cli desktop calculator, which has been a part of unix and unix like systems since the 70’s.

      1. We can start with “Dan Bricklin’s Demo Program” and “EA Pinball Construction Set”. The first examples of meta-programming at the consumer level. Never before were computer users able to directly program computers without coding.

        1. Examples of meta-programming at the consumer level doesn’t count as originating. Never mind meta-programming vastly pre-dates the Apple ][. Was it novel? Yes. Originating? No.

          1. Okay if that is your mindset then I will say that there has not been a single iota of innovation in the computer business since the IBM 360. Bill Beausoleil was the last living person to make an innovation in computer technology. Since then every computer has been just a slavish clone of the 360. How’s that?

          2. In fact, it was God who invented the binary system. When he made all the animals as male and female. Strangely God forgot to do the same for Adam. So Adam had to in fact ask God to make him a binary-complementary man.

            Actually, secretly, God DID create a woman together with Adam, at the time. She was named Lilit. But she wouldn’t listen to Adam, Adam being quite a possessive guy and not giving her any freedom of movement. Lilit warned Adam about his possessiveness. But Adam didn’t want to change and still tried to make Lilit do his bidding. So Lilit gave Adam the finger and ran away. Then Adam was sad because he was lonely again. But still thought that he was always right. So after a while God took pity on Adam and created a new woman from Adams rib. Hoping that this time, the woman would be more like Adam himself and make him feel more secure in his opinions.

            Well, and we all know how well THAT ended…

            But the main point of my story is that God invented the binary system.

        2. I assume you are talking about FORTH. That originated in 1970, long before the Apple II.
          I’m genuinely interested to know what technologies we benefit from every day, originated with the Apple II. I was there and I don’t recall them myself.

    1. There’s very little technology I can think of that started in the Apple ][. In fact, the only thing I can think of is the disk controller that was pretty much all software. Apple didn’t want to spend the $17 for an FDC chip so Woz did the whole thing in software. Was a good idea, but it had issues. Compatibility with anything else being #1 in my book.
      It also used a switching power supply, which while novel, wasn’t original. Sprites? Similar, there were prior implementations. All in one kbd/processor? Predating the Apple ][ was the SOL-20. Also done by Radio Shack about the same time as Apple, later by Commodore (once they ditched the monitor on top of the PET).

      The Olivetti 101 was indeed a monster. Best friend in high school had one. The mag card reader was pretty spectacular in use. But my gold standard for old calculators is a Curta. :)

      I never owned an Apple ][, and I’ve been playing with computers since before it was released. I really wanted a SOL-20, but settled for an Altair 680b and ADM3a before I got some other machines in the stable.

      Today I use an HP calculator, or emulator thereof, every day. I can’t not think in RPN.

        1. There was plenty of third party software before the Apple ][. The Apple ][ didn’t have a UI to speak of. Mac, certainly, Apple ][ was pretty CLI driven. There were some common icons and UI like structures, but those were part of the 3rd party software, and many of which came from other places and were hardly unique to the Apple.

          Apple has had plenty of innovation on existing technologies, I just don’t think much of it is ‘original’ in the Apple ][. Did it help the spread of some things? Probably. Did it help drive adoption of computers? Certainly. But that was because of Apple’s educational purchase programs, not the technology.

    1. Some calcs had a K button for Constant (but C was already used for Clear).
      If you entered a number under K, the calc would retain it for subsequent operations (until it was shut off).

      1. That is semantics.
        compute: verb, calculate or reckon (a figure or amount).
        computer: noun, an electronic device for storing and processing data
        All of those devices help a human to compute, but they are not general purpose computers as most people now use the term. Historically a computer was a person whose job it was to compute.

        1. The definition of the word “computer” is not fixed. We called that old Olivetti a “computer” back then, but today nobody would call it a “computer”. And yet a vape pen has an actual computer inside it but nobody would call a vape pen a computer.

  3. I was a teenager in the 70’s. My dad was a machinist for Boeing and bought a calculator when they first came out. The excitement in the family was palpable. I remember to this day the wonder and awe when it was my turn to type numbers into the new-fangled device and watch them show up on the LED display. It was pure magic….something I can never articulate to the current generation.

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