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

the Curta hit the world market in 1949 selling for US$125 through mail order and in a handful of specialty shops. It was a lot of money in those days, but the Curta was still a hit with engineers, traveling accountants, pilots, and even rally drivers. In the end, 150,000 of them were built in two models over the course of 20 years. It also gained a... 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

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

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

"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

By 1938, Hertzstark had applied for patents for his new design and had made a couple of prototypes of the basic mechanism out of Bakelite plastic to demonstrate the principle. Unfortunately, that's as far as he got because in March 1938 the Anschluss took place and Nazi Germany's Wehrmacht marched over the border to annex Austria.

The inside of a Cu... 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

Then in 1937, Hertzstark had a breakthrough. Instead of making a machine that could add and subtract, make one that did nothing but add, but in such a way that it also subtracted.

"I can remember. I sat in a compartment alone and looked out and thought at that moment, 'Good Grief! One can get the result of a subtraction figuratively by adding the co... 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