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Calculators – from Prized Possessions to Everyday Helpers

Two researchers still have their first calculators decades later. These devices make us recall an earlier time – and they’re the perfect example of how Moore’s Law has granted many people access to this technology in such a short space of time.  

Claudia was born on a Wednesday. That was one of the first things that now-retired Siemens developer Ralph Oppelt worked out with the first calculator he ever owned. Claudia was Oppelt’s girlfriend at university – but let’s not confuse her with his wife, who’s also called Claudia. 

38 years later, he still has the piece of paper with Claudia’s name on it, as well as her date of birth and his calculations to determine the day on which she was born. It was carefully folded and stored in the box that his first calculator came in: a TI 58 C made by Texas Instruments. Oppelt purchased it back in 1981, three years after it was released when it was almost affordable for him in his student days. The battery has since died, but when he connects it to an external power supply, it works just as well as it used to.

The first portable calculator was the Cal Tech, a prototype developed by Texas Instruments in 1967. The Cal Tech was able to perform all the basic functions: addition, multiplication, subtraction and division. The Cal Tech research project also led to the creation of the Pocketronic, the first commercially available pocket calculator that was released in 1970.

In the original box, Oppelt still keeps the notes from the first calculations he made using the TI 58 C. © Moritz Peters
In the original box, Oppelt still keeps the notes from the first calculations he made using the TI 58 C. © Moritz Peters

Impressed at an early age

The newly retired Head of IT at the Fraunhofer Institute in Erlangen, Roland Plankenbühler, also remembers the first time he held a calculator: he was just 14 when his father bought a programmable device for 2,000 marks. Plankenbühler was blown away. He bought his very first calculator, an SR 51a, just after graduating from high school in 1975. It was on sale for 350 instead of 450 DM – which was still a lot of money for someone his age, especially when you consider that the average income 40 years ago is one third of today’s average.

At school, Plankenbühler and Oppelt only did sums using a slide rule – even at university, they weren’t allowed to use calculators as the use of any resources was banned. When they were first released, calculators were seen as a product reserved for the elite. “At school, only very few students from wealthy families had one,” recalls Oppelt. He tells us of one former classmate he was particularly in awe of – they had a TI59 that could do sums and print them out.

These days, all smartphones come with an integrated calculator app and every schoolkid has their own calculator. At German grammar schools, students first use calculators in class when they start 8th grade, and they can take them into their exams.

From giant devices to pocket-sized ones

Back when the two researchers first got their calculators, the technology was coming on in leaps and bounds. In a short space of time, the devices became much smaller, more powerful and more affordable for the general public and thus for young researchers Plankenbühler and Oppelt. Plankenbühler’s second calculator, a Sharp EL 506H, cost less than 30 marks! He still uses it to this day and is very happy with it: “I’ve only ever had to change the batteries twice.”

The Sharp EL 506H at the front is Plankenbühler’s second calculator. Not only is it more lightweight, it’s also considerably more affordable than the SR 51a released just a few years earlier. © Moritz Peters
The Sharp EL 506H at the front is Plankenbühler’s second calculator. Not only is it more lightweight, it’s also considerably more affordable than the SR 51a released just a few years earlier. © Moritz Peters

From a calculator costing 2,000 marks bought by Plankenbühler’s dad to the many millions of calculators that schoolkids use these days; from the Pocketronic that weighed in it at almost 1 kg to the ultra-lightweight mini calculators available today – the development of the calculator can most easily be described by Moore’s Law, named after co-founder of Intel, Gordon Moore, which states that microchip performance will rise exponentially every one to two years.

How Moore’s Law granted us easier access to technologies

This is all thanks to miniaturization: advancements in technology and production have enabled manufacturers to put more and more transistors on a microchip ever closer together. This development was what actually made it possible to build smaller, more lightweight devices. But you can only produce powerful microchips if you have an excellent optical process. Alongside miniaturization, the optical process is one of the most important advancements in technology and it has enabled processing power to grow exponentially.

After all, when it comes to producing the smallest possible microchip structures, the quality of the illumination system and high-resolution projection optics play a key role. Chip factories around the world rely on ZEISS lithography optics to get the job done. The first ZEISS optic had a resolution of 1.25 micrometers and was used by the company Telefunken in 1969 – today, the resolution is one sixtieth of the value achieved 50 years ago. The technological developments described by Moore’s Law have made it easier for people to access technologies. The calculator is an excellent example of this: it used to be a portable yet bulky device and is now light as a feather.

Cycling around the Earth three times – doing sums in one’s head

Ralph Oppelt has always deemed it important to be able to do sums in one’s head despite all the technology we have at our fingertips. This skill proved to be an asset throughout his career, especially when he rode his bike – every day he would cycle through the woods to get to work. In his 30-year career he cycled around the globe 3.5 times – another sum he did himself! “Cycling really gave me a chance to think about things that bothered me at work,” he says. Now that everyone has easy access to a calculator, Oppelt worries that fewer and fewer people will do sums in their heads. Then again, he doesn’t want to rely exclusively on brain power, so he keeps a calculator on his nightstand in case he has a brainwave while he sleeps.

Even though so much time has passed, Oppelt and Plankenbühler still have their first calculators. They hold them almost affectionately when showing them. “It makes me think back to a time that changed my life,” says Plankenbühler. A time when chips were still big and expectations great.

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