My calculations show…

I lived through the transition from mechanical to digital calculators. Here’s a look back at the calculators I’ve used over the past 50 years.

Underwood Sundstrand Adding Machine

Underwood SundStrand Adding Machine

My first experience with a calculator was this 30-pound chunk of hardware that my father bought used and planted on the large partners desk in our den at home in the early 1970s. It could add, subtract, and repeat, so you could do some primitive multiplication. Everything printed out on a paper spool. The machine was loud.

Oscar and David Sundstrand first marketed adding machines around 1915. Their firm was acquired by Elliott Fisher Company in 1927, and that was merged later that year with Underwood Typewriter Company. So we had an Underwood Sundstrand machine by Elliott Fisher. The Sundstrands were the ones who introduced the ten-key layout that became ubiquitous and is still found on computer numeric keypads.

You can see how the machine worked in the video below by a youngster working to figure out one that he picked up from Goodwill.

An old Underwood Sundstrand adding machine

Monroe Monromatic Calculator

In the 1950s and 1960s, when he worked in the Gas Measurement department of Cities Service Gas, my father’s fellow office workers had Monroe Monromatic Calculators. Those were far more sophisticated mechanical marvels that could add, subtract, multiply, and divide to many places. They cost about $275 each in 1955, which would be over $3,000 in 2022 when adjusted for inflation.

Operating such machines was non-intuitive compared to today’s electronic calculators:

A Monroe Monromatic in action

My Mechanical Calculators

Needless to say, those devices were not suitable for calculations when you were out shopping at a grocery store or a five-and-dime. I had two handheld devices which my parents had picked up at garage sales.


The first was a Super Add-A-Matic. You could hold it in your hand and depress buttons for dollars, dimes, and cents to add up the cost of items as you placed them in your basket. That way you could ensure you didn’t exceed the cash you were carrying.

The device could only add, and it reset to zero when you passed $19.99. I used it a few times at the local T.G.&Y. back when my allowance was a few bucks a week. Inflation rendered these devices obsolete decades ago.


I also had one of those little stylus computators. You had to stick the stylus in the appropriate slot and drag it to add or subtract. I found its operation clunky and not very useful, eventually prying it apart and playing with its sliders before chucking it all in the trash.

How stylus computators worked

Canon Canola L 163

Canon digital calculator

The first digital calculator I encountered was the Canon Canola L 163 that my father had on his desk at work in the mid-1970s. I was fascinated by its silence and the weird display. It used 16 Nixie Tubes, which were made of glass and contained a wire mesh anode and multiple cathodes, with each of the latter shaped like different numbers. The appropriate cathode would glow when selected, and I could see the wires for the other numbers both in front of and behind the one that was glowing. I remember staring intently into the display to figure out why its numbers appeared at different depths.

That device originally cost $845 in 1971, or over $6,000 in 2022 dollars when adjusted for inflation.

Puttering around on an early digital calculator with Nixie Tubes

Casio personal-mini

As an elementary school student, I was oblivious to the handheld calculator wars of the early 1970s, unaware that the commoditization of integrated circuits and LED and LCD displays were making handheld calculators incredibly cheap compared to the desktop digital calculators of just a few years earlier. Texas Instruments released the first calculator priced under 10 dollars in 1974.

So I was surprised at age 11 to find a Casio personal-mini four-function calculator on sale for a few bucks at a neighborhood garage sale. I rode home on my bicycle to collect all of my savings, hurrying back to purchase it before someone else snatched it up.

That device sold for $13.50 in 1976, which would be over $70 in 2022 dollars when adjusted for inflation. I was thrilled to get it in 1977 for $4, which would be about $20 in 2022 dollars after inflation.

It had a six-digit vacuum fluorescent display, instead of the more typical eight, as a cost-savings measure. If a result had more than six significant figures, you pressed the arrow key to see the remaining digits. I was struck by how its zeroes were half-sized. It was so slow that you could see the digits changing on a calculation, somewhat like watching the dials on an even slower mechanical calculator. And if you divided by zero, it would go into an infinite loop; pressing the arrow showed a steadily increasing counter.

A fellow demonstrates what was my first calculator


When I was in high school chemistry in 1982, our old-school teacher forced us to memorize, to four significant figures, the values of sine, cosine, and tangent for every 5 degrees. We were to interpolate values between them as needed. Our mathematics textbook also had tables for sine, cosine, and tangent for each degree value.

All that seemed crazy to me, knowing that there were now handheld calculators that could do the trigonometric functions. I had saved up my allowance to buy a new TI-30 from Texas Instruments for $25, which would be about $75 in 2022 when adjusted for inflation. I remember how my old-school teachers, relying on trig tables and sliderules, would provide answers that were actually less accurate than mine, rapidly calculated on my TI-30. My father had the sliderule he used in college in the 1940s, showing me a bit of how to use it. I thanked my stars that I dodged that era in handheld computation.

My calculator had a carrying case with a belt loop and small red LED digits for its display. It came with The Great International Math on Keys Book. TI would sell 15 million of them from 1976-1983.

Tandy Pocket Computers

HP calculator
HP calculators often used Reverse Polish Notation, which I found baffling

In 1986, I decided that I needed a more powerful scientific calculator to help me in my Electrical Science and other engineering courses at the University of Oklahoma. Some of my engineering and math friends had Hewlett-Packard calculators of various types, with many of them using Reverse Polish Notation. I found that input system baffling, preferring the Algebraic Operating System used by Texas Instruments, but I wanted to be able to program advanced calculations and formulas into my device.

Radio Shack introduced its PC-5 Pocket Computer that year, which was a rebranded Casio FX-780P. I spend $120 of my scholarship money on one, which would be about $330 in 2022 when inflation-adjusted.

I loved that device, which folded open to reveal the usual scientific calculator keys on the bottom, but had a membrane QWERTY keyboard on its upper half, with shortcuts for various BASIC words, and a 24-character LCD display.

Tandy PC-6

It had searchable memos and a wonderful formula feature – you could save your own plain English formulas in memory and have it prompt you for the values and then it would calculate. For more complex work, I could write complete programs in BASIC.

That little machine took me through the rest of my undergraduate work and into my teaching career. I programmed it to work its way through student lab calculations to speed up my grading, and I did all of my grade calculations and associated statistics on it. It didn’t do graphs, but I prefer a big screen for that anyway.

The original PC-5 served me for a decade, with me paying for a few repairs at the local Radio Shack. When it finally wore out, I replaced it with the near-identical PC-6, which served me another 10 years.

Here is a guy looking at one of these nifty devices:



After 20 years of using a PC-5 and then a PC-6, I was chagrined when my PC-6 finally bit the dust. I still wanted a BASIC programmable calculator for lab calculations, with statistical functions to analyze test results. So I opted for a TI-86 graphing calculator. Those were introduced in 1996 and weren’t discontinued until 2006.

I almost never used the graphing capability, preferring to do my graphing on a personal computer with a large display. I never upgraded to a later model, since newer TI programmable calculators were not compatible with the TI-BASIC programs I had painstakingly rewritten into my TI-86 unit. I didn’t want to re-create all of that code a third time. So, whenever one would wear out, I’d replace it with another I purchased on eBay. That pattern continued until I retired from teaching in 2017.

End of an Era

My use of handheld calculators ended with my teaching career in May 2017. Now I lead the district’s technology and communications efforts, and I mostly use Google Sheets for calculations and analysis. If I need to crunch some simple numbers while at a Windows desktop computer, I just press the Calculator button on my multimedia keyboard, which opens the basic Windows calculator app. Or I could just type “calculator” in Google for it to display its own scientific calculator.

And when I’m out and about, my iPhone has its own calculator app, which is a basic four-function one in portrait mode, and a scientific one in landscape.

I lived through the years from mechanical calculators to digital desktop ones, on through handheld digital calculators, into this era where the smartphone has turned the calculator into just another app. I suppose some students are still stuck buying ridiculously overpriced TI graphing calculators for supervised testing, but otherwise such devices seem to be from another time and place.

About Granger Meador

I enjoy day hikes, photography, podcasts, reading, web design, and technology. My wife Wendy and I work in the Bartlesville Public Schools in northeast Oklahoma, but this blog is outside the scope of our employment.
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