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Curta

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From Wikipedia, the free encyclopedia

Mechanical pocket calculator

For other uses, see Curta (disambiguation).

CurtaCurta Type II mechanical calculator<br>TypeMechanical calculatorManufacturerContina AG MaurenIntroduced1948 (Type I)<br>1954 (Type II)Discontinued1972Date invented1930sInvented byCurt HerzstarkCost$125 (Type I)<br>$165 (Type II)CalculatorPrecision11 digits (Type I)<br>15 digits (Type II)Display typeMechanical counterDisplay size6-digit revolution counter, 11-digit result counter (Type I)<br>8-digit revolution counter, 15-digit result counter (Type II)OtherWeight230 g (8.1 oz) (Type I)<br>360 g (13 oz) (Type II)

Curta Type I, on display at the Musée des Arts et Métiers, Paris.<br>A partially disassembled Curta calculator, showing the digit slides and the stepped drum behind them<br>Curta Type I calculator, top view<br>Curta Type I calculator, bottom view

The Curta is a hand-held mechanical calculator designed by Curt Herzstark.[1] It is known for its extremely compact design: a small cylinder that fits in the palm of the hand. It was affectionately known as the "pepper grinder" or "peppermill" due to its shape and means of operation; its superficial resemblance to a certain type of hand grenade also earned it the nickname "math grenade".[2][failed verification]

Curtas were considered the best portable calculators available until they were displaced by electronic calculators in the 1970s.[1]

History<br>[edit]

The Curta was conceived by Curt Herzstark in the 1930s in Vienna, Austria. By 1938, he had filed a key patent, covering his complemented stepped drum.[3][4] This single drum replaced the multiple drums, typically around 10 or so, of contemporary calculators, and it enabled not only addition, but subtraction through nines complement math, essentially subtracting by adding. The nines' complement math breakthrough eliminated the significant mechanical complexity created when "borrowing" during subtraction. This drum was the key to miniaturizing the Curta.

His work on the pocket calculator stopped in 1938 when the Nazis forced him and his company to concentrate on manufacturing precision instruments for the German army.[5]

Herzstark, the son of a Catholic mother and Jewish father, was taken into custody in 1943 and eventually sent to Buchenwald concentration camp, where he was encouraged to continue his earlier research:

While I was imprisoned inside Buchenwald I had, after a few days, told the [people] in the work production scheduling department of my ideas. 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 be made an Aryan.' For me, that was the first time I thought to myself, my God, if you do this, you can extend your life. And then and there I started to draw the CURTA, the way I had imagined it.

— Curt Herzstark, Oral history interview with Curt Herzstark (1987), pp. 36-37[6]

In the camp, Herzstark was able to develop working drawings for a manufacturable device. Buchenwald was liberated by U.S. troops on 11 April 1945, and by November Herzstark had located a factory in Sommertal, near Weimar, whose machinists were skilled enough to produce three working prototypes.[6]

Soviet forces had arrived in July, and Herzstark feared being sent to Russia, so, later that same month, he fled to Austria. He began to look for financial backers, at the same time filing continuing patents as well as several additional patents to protect his work. Franz Joseph II, Prince of Liechtenstein eventually showed interest in the manufacture of the device, and soon a newly formed company, Contina AG Mauren, began production in Liechtenstein.

It was not long before Herzstark's financial backers, thinking they had got from him all they needed, conspired to force him out by reducing the value of all of the company's existing stock to zero, including his one-third interest.[1] These were the same people who had earlier elected not to have Herzstark transfer ownership of his patents to the company, so that, should anyone sue, they would be suing Herzstark, not the company, thereby protecting themselves at Herzstark's expense. This ploy now backfired: without the patent rights, they could manufacture nothing. Herzstark was able to negotiate a new agreement, and money continued to flow to him.

Curtas were considered the best portable calculators available until they were displaced by electronic calculators in the...