Shady Characters advent calendar 2023: the Sinclair Executive


It was 1972 and Sinclair Radionics of Cambridge, England, was riding high. Founded a decade earlier on an excess of pluck and a surfeit of ambition, inventor Clive Sinclair’s company had matured from home-built transistor radios to stylish hi-fi gear. But a visit to the USA had inspired Sinclair to design a new product: the thinnest, lightest pocket calculator the world had ever seen.

A Sinclair Executive calculator. (CC BY-SA 3.0 image courtesy of MaltaGC on Wikipedia.</a>)
A Sinclair Executive calculator. (CC BY-SA 3.0 image courtesy of MaltaGC on Wikipedia.)

The Sinclair Executive was a huge gamble, and an equally huge hack. The calculator’s elegant silhouette was possible only because its Texas Instruments’ microchip was periodically starved of electrons by a circuit designed at Sinclair Radionics. This meant the calculator could run on tiny coin-shaped cells rather than the bulky cylindrical batteries of its competitors.

Some time later, in Moscow, a Russian diplomat thought he was having a heart attack. He was not: instead, his Sinclair Executive had exploded in his shirt pocket. A defective on/off switch had caused the calculator to grow so hot the batteries burst. An official investigation was begun; an international incident loomed.

Or did it?

The story of the exploding Executive seems to have grown out of a real, although much less dramatic incident. Chris Curry, Sinclair’s friend and one-time employee, explained some years later that the batteries had leaked — not exploded — in an Executive belonging to one Lord Rothschild, a British aristocrat. Curry had been dispatched with a replacement calculator to placate Rothschild, who had once been Sinclair’s banker. Thus, if a Sinclair Executive had ever met its demise in the pocket of a notable personage, it most likely happened in England, not Moscow — yet without much proof either way, there remains the tantalising possibility that there is more to the story.

In time, Clive Sinclair would become famous, and then infamous, for a string of other inventions, eventually to be felled by the disastrous Sinclair C5, an electric trike that placed the rider at car exhaust level and came to halt after 20 miles. Yet among his hits and misses, the Executive stands tall. It was driven by a hack, but an elegant one. It was an alluring electronic device at a time when the very idea of consumer electronics was still in its infancy. And maybe, just maybe, an overtaxed Executive popped its batteries in the pocket of a Russian diplomat who had obtained for himself a token of wealth and influence, and gave him the fright of his life.

Shady Characters advent calendar 2023: the HP-35


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


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


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


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.

 

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

 

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

 

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

 

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

 

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