Shady Characters advent calendar 2023: the HP-35

Welcome to day eleven of the first ever Shady Characters advent calendar! I’m counting down to Christmas by way of a collection of beautiful, clever, important, and/or outright odd calculators and calculating devices. Some come from the pages of Empire of the Sum, some are part of my Calculator of the Day series, and some will be new to the blog. I won’t manage twenty-four posts, but I do plan to hit at least one every other day. I hope you enjoy the series!

Today, a repost of an entry from my Calculator of the Day series. We’re looking at the Hewlett-Packard HP-35, a scientific calculator that today looks quite unremarkable — and yet which, at the time, was revelatory.

Hewlett-Packard HP-35
A well-used Hewlett-Packard HP-35, as many of them were. (CC BY 4.0 image courtesy of the Flygvapenmuseum.)

Depending on the reader’s age, the name “Hewlett-Packard” may evoke calculators, desktop computers or printers. (Or, maybe, nothing at all.) But for the first few decades of the company’s existence, it specialised in electronic “instruments” such as the oscilloscopes, signal generators and other tools that an engineer might use to design or test an electrical or electronic circuit. Conceived by HP’s co-founder, Bill Hewlett, the HP-35 was to be the company’s route out of that niche and into a wider world of consumer electronics.

The thing about the HP-35 is this: unlike many other calculators at the time, no part of it was truly without precedent. Scientific calculators were not new, although they were sized for desks rather than pockets (and nor had anyone thought to market them to consumers rather than engineers). Integrated chips were not new, although they were rarely as complex as those in the HP-35. LED displays were not new, but they were very expensive and not often seen in calculators. What the HP-35 did do that no other device had managed before was to bring all these things together into a package that was portable, powerful, and, crucially, aesthetically pleasing.

HP’s first pocket calculator turned out to be a smash hit. Sold at Macy’s and advertised in Esquire, the HP-35 had an appeal far beyond mathematicians and scientists, and the company could barely keep up with demand. Students sold their cars to buy them. NASA engineers had to lock theirs away to stop them from going walkabout. US army math instructors devised a new course as an excuse to buy HP-35s on expenses. And HP never looked back: the company that had once built engineering gadgets for engineers now aimed its products at the public at large. Some observers, in fact, credit the HP-35 with inaugurating the whole category of consumer electronics; your iPhone, tablet or laptop computer may never have come about without it.

A big thank you to Jim Hughes at Codex99, whose article was the catalyst for my chapter on the HP-35. His writing is excellent, and his site is well worth a moment of your time.

Shady Characters advent calendar 2023: the Canon Pocketronic

Welcome to day ten of the first ever Shady Characters advent calendar! I’m counting down to Christmas by way of a collection of beautiful, clever, important, and/or outright odd calculators and calculating devices. Some come from the pages of Empire of the Sum, some are part of my Calculator of the Day series, and some will be new to the blog. I won’t manage twenty-four posts, but I do plan to hit at least one every other day. I hope you enjoy the series!

Today, a repost of an entry from my Calculator of the Day series: we’re taking a look at the Canon Pocketronic, a machine with a decent claim to being the first ever pocket electronic calculator.

The Canon Pocketronic, a beige and black printing calculator based on a Texas Instruments prototype.
The Canon Pocketronic. (CC BY-SA 2.0 image courtesy of Vicente Zorilla Palau.)

The Pocketronic was both an imposter and a failure. It started life as the “Cal Tech”, a prototype calculator designed by Texas Instruments as a means to sell microchips to the average person on the street. The problem was that TI was not, at first, very good at making those chips. Despite having pioneered the integrated circuit, the Cal Tech’s chips were so complex that the company could not reliably produce them en masse. Another problem was that the usual calculator display mechanisms were inimical to the Cal Tech’s hoped-for pocketable form factor: LEDs were too power hungry, and so-called Nixie tubes — lightbulbs, essentially, with filaments twisted into the shape of numerals — were too large. In their place, TI put a reliable but obsolescent printing mechanism. This was a calculator that could run out of batteries and paper.

TI had never meant to build the Cal Tech itself, and so, years later, when it had solved its production issues, it handed the design to Canon for refinement into a more consumer-friendly device. The Pocketronic was born, considerably later than intended and so bulky that the “pocket” part of its name was as much an aspiration as a statement of fact. It was never the success that TI had hoped, and yet it gave the company a taste of a calculator market that only promised to grow and grow.

By and by, TI worked the kinks out of its manufacturing processes and, eventually, started to make calculators in house. A decade or so later and it was one of the largest calculator manufacturers in the world. And as any US schoolchild will tell you, it still is today.

Shady Char­ac­ters advent calendar 2023: the Curta

Welcome to day nine of the first ever Shady Characters advent calendar! I’m counting down to Christmas by way of a collection of beautiful, clever, important, and/or outright odd calculators and calculating devices. Some come from the pages of Empire of the Sum, some are part of my Calculator of the Day series, and some will be new to the blog. I won’t manage twenty-four posts, but I do plan to hit at least one every other day. I hope you enjoy the series!

Today, a repost of an entry from my Calculator of the Day series: we’re taking a look at the “math grenade”, as William Gibson calls it in his novel Pattern Recognition, the mechanical, cylindrical, pocketable Curta.

Curta mechanical calculator with case and box.
Curta mechanical calculator with case and box. (CC BY-SA 2.0 image courtesy of Magnus Hagdorn.)

The Curta is noteworthy for two reasons. One is that it was the first practical pocket calculator, being as it was a miniaturised version of an existing mechanical calculator called the arithmometer. (The arithmometer, in turn, had its roots in a mechanism called the “Leibniz wheel”, an invention of the prolific but unlikeable Gottfried Wilhelm von Leibniz. This seventeenth-century German polymath was allegedly so unpopular that his funeral was attended only by his secretary.) With a Curta, a practiced user could add, subtract, multiply and divide numbers by adjusting a few sliders and then turning the crank on top. The answer then appeared in a set of displays arrayed around the top of the device.

It’s possible to be simultaneously entranced by the Curta’s mechanical cleverness and sobered by the circumstances of its creation. That’s because the second reason for the Curta’s prominence is that it was designed in a Nazi concentration camp. Curt Herzstark, its inventor, thinking it his only way out, designed the Curta to appease his captors — and, after the liberation of the notorious Buchenwald camp in which he was imprisoned, found his way to the tiny principality of Liechtenstein to see his blueprints put into production.

Perhaps alone among the calculators I write about in Empire of the Sum, the Curta melds tragedy and triumph in a single artefact. Herzstark’s tenacity in the face of one of the great atrocities of our time, and the ingenuity of the calculator that resulted, are equally worthy of note.

Shady Char­ac­ters advent calendar 2023: the E-6B

Welcome to day eight of the first ever Shady Characters advent calendar! I’m counting down to Christmas by way of a collection of beautiful, clever, important, and/or outright odd calculators and calculating devices. Some come from the pages of Empire of the Sum, some are part of my Calculator of the Day series, and some will be new to the blog. I won’t manage twenty-four posts, but I do plan to hit at least one every other day. I hope you enjoy the series!

Most slide rules are rectangular. (If you’ve never seen one before, there’s a good example of a rectangular slide rule belonging to the US astronaut Sally Ride in a previous post here at Shady Characters.) We won’t go into the mechanics of it all here,* but, in essence, a slide rule helps its user to multiply numbers simply by reading off a pair of distances, as on a conventional ruler. One distance plus another distance is a third, and all three can be read off a pair of logarithmic scales lined up next to each other. Really, a rectangle is all you need.

An E6-B flight computer, as owned by Sally Ride, the first female American astronaut. (CC0 image courtesy of the National Air and Space Museum.)
An E-6B flight computer, as owned by Sally Ride, the first female American astronaut. (CC0 image courtesy of the National Air and Space Museum.)

Yet in some cases, a circle is better. You can stretch a longer scale around the circumference of a circle than you can fit across its diameter, and a longer scale means more accurate measurements and more accurate multiplications.1 As such, the discerning slide rule enthusiast appreciates the accuracy of the circular slide rule as much as the portability of the rectangular version. And accuracy, it turns out, is very handy when navigating an aircraft. That’s where this slide rule, the Dalton E-6B dead reckoning computer, comes in.

Designed in the 1930s by an American naval pilot named Philip Dalton, the E-6B combined a circular slide rule with a “wind triangle” computer — a clever analogue mechanism for figuring out how the direction of an aircraft flying at a particular speed will be affected by the wind.2,3 The slide rule portion allowed a practiced pilot or navigator to compute air speed given a distance travelled and a time taken (or, indeed, to compute any one of those quantities given the other two); to calculate fuel burn rates; to convert between nautical miles and kilometres; to estimate how far off course an aircraft may have travelled; and to correct observed air pressure for the outside air temperature.2,3 Or even — *gasp* — to simply multiply or divide a pair of numbers.

The E-6B went on to become a standard part of the average US aviator’s training and tools, and although today it has been largely replaced by specialized electronic navigation computers (many of which look a lot like pocket calculators), the FAA’s own Weight and Balance Handbook still makes reference to the E-6B in its chapter on computing aircraft weight and balance.4

So useful was the E-6B in its day, in fact, that the professional prognosticators of the 1960s imagined that it would still be in use in the 23rd century: Mr Spock, science officer of the USS Enterprise, is shown with an E-6B in hand in two separate Star Trek episodes.5 And if it’s good enough for Mr Spock, who am I to argue?

1.
Bruderer, Herbert. “How Does One Calculate With A Circular Slide Rule?”.

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2.
National Museum of American History. “Dalton E-6B Dead Reckoning Computer by Jeppesen”. Accessed December 2, 2023.

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3.
Safetech E-6B Computer Manual. Newtown, PA: Safetech, n.d.

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4.
Weight & Balance Handbook. Federal Aviation Administration, 2016.

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5.
Valerio, Pablo. “E6B Computer: Celebrating 75 Years Of Flight”. InformationWeek.

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*
…but you can buy my book to learn more! ↢

Shady Char­ac­ters advent calendar 2023: the addiator

Welcome to day seven of the first ever Shady Characters advent calendar! I’m counting down to Christmas by way of a collection of beautiful, clever, important, and/or outright odd calculators and calculating devices. Some come from the pages of Empire of the Sum, some are part of my Calculator of the Day series, and some will be new to the blog. I won’t manage twenty-four posts, but I do plan to hit at least one every other day. I hope you enjoy the series!

Not all mechanical calculators were as sophisticated as the arithmometer or as intuitive as the Comptometer — or as large as either of them. Some, like the addiator, were very simple and very small indeed.

An addiator manufactured around 1930. (CC0 image courtesy of Volkskunde- und Freilichtmuseum Roscheider Hof & Rainer Blazejewicz.)
A pocket-sized addiator manufactured around 1930, accompanied by a stylus to moves its numeric sliders. (CC0 image courtesy of Volkskunde- und Freilichtmuseum Roscheider Hof & Rainer Blazejewicz.)

Technically speaking, “addiator” is a trade name often used to refer to a class of small adding machines more properly called slide adders. (They were also sometimes called “Troncets”, after another early manufacturer.) Slide adders comprised a number of parallel, toothed metal strips sandwiched between two boards. Each slide was visible through a slot cut in the board above it — and sometimes the one below it, too, in order to handle subtraction as well as addition. Users moved the sliders up or down in their slots using a stylus, following simple rules to handle carries from one column to the next.1,2,3

For me, the addiator is a fascinating device, and that’s at least partly because I don’t know very much about it. It hovered around the periphery of the more “mainstream”, computer-adjacent calculators that populate Empire of the Sum, but I could never quite make the case to myself that it should be included with them. There were a number of sticking points.

First, setting aside the pioneering idea that an adding machine could fit in a pocket, the addiator was essentially a dead end: neither its internal mechanisms nor its “user interface” seem to have inspired any later devices. As such, very little was written about it at the time.

Equally, despite many modern sources calling the addiator a popular device, there isn’t much data to back up that assertion. The only sales figures I’ve seen suggest that the “Arithma”, a West German model imported to the USA between 1957 and 1973, sold around 2.5 million copies.4 That’s a lot — more than 150 thousand per year — but by way of comparison, Victor, an American firm that made Comptometers and other desktop calculators, churned out twice as many devices in 1968, each one of which would have cost far more than an addiator.5.

Finally, I’m just not sure that I detect the fondness for the addiator that I do for the slide rule or the many different mechanical calculators that came after it. There are many slide rule and calculator collectors; there are far fewer addiator collectors.

And so for Empire at least, the addiator ended up on the cutting room floor. A shame, because this pocketable gadget was nothing if not ingenious in its simplicity.

1.
Wolff, John. “Slide Adding Machines”. John Wolff’s Web Museum.

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2.
Tout, Nigel. “’Addiator’ Type Calculators”. Vintage Calculators Web Museum. Accessed December 13, 2023.

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3.
Scriven, John. “Addiators”. A Collection of Mechanical Calculators (blog).

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4.
Parsons, F. “Addiator Arithma”. American Stationer (blog).

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5.
Darby, Edwin. It all adds up; the growth of Victor Comptometer Corporation. Chicago: Victor Comptometer Corporation, 1968.

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