Curta calculator: The mechanical marvel born in a Nazi death camp

What's worse was that inside the device each digit of a number was set on a separate register with its own mechanism that had to be repeated up to eight to 10 times. Then to compound the problem, subtraction meant duplicating all these in reverse, plus a special mechanism to handle carrying the number when necessary. No wonder a handheld calculator... See more

But the clever bit was when Hertzstark got rid of all the number registers and replaced them with a single unit called a step drum. This, as the name implies, is a drum made of metal cut in steps to correspond to different numbers. He then simplified things even further by adding a second drum on top of the first in reverse, so a simple shift in th... See more

"The head of the department, Mr. Munich said, 'See, Herzstark, I understand you've been working on a new thing, a small calculating machine. Do you know, I can give you a tip. We will allow you to make and draw everything. If it is really worth something, then we will give it to the Führer as a present after we win the war. Then, surely, you will b... See more

But he did have the plans and the prototypes of the Curta, which was a true marvel of design and construction – as much like a watch movement or the mechanism of a fine camera as it was a calculator. But could he find backers to manufacture it?

In 1945, that was a difficult question. At first glance, the Curta looks as much like a calculator as a po... See more

In the late 1940s, Hertzstark had filed new patents and eventually found a backer in the Prince of Liechtenstein. The country, where Hertzstark resettled until his death in 1988, was looking to expand its economy and the Prince agreed to help set up a company to build and market the Curta, the Contina AG Mauren, with Hertzstark holding 30 percent o... See more

"I started to concentrate on possible solutions and at first, naturally, didn't get any further," said Hertzstark. "Later, I had an idea that I should look at everything backwards. I thought to myself, I'll pretend that I have already invented everything. What does this kind of machine really have to look like, so that someone could use it? It cann... See more

Some relief from tedious manual number crunching came in the 17th century with the invention of logarithms followed by mechanical aids like the slide rule and the first adding machines. Unfortunately, they weren't that much of a help. Slide rules couldn't handle numbers to more than two or three decimal places and, for centuries, calculators were l... See more

And all this without batteries and to 8 to eleven places.

"And again and again, wherever one went, competitors came with wonderful, big machines, which were ever more expensive and electric, but something was missing in the world market," said Herzstark in an extensive interview (PDF) conducted by the Charles Babbage Institute in 1987. "'I would like to have a machine that fits into my pocket and can calc... See more