![Curta01](https://upload.wikimedia.org/wikipedia/commons/5/5c/Curta01.JPG)
The Curta is a hand-held
mechanical calculator
A mechanical calculator, or calculating machine, is a mechanical device used to perform the basic operations of arithmetic automatically, or (historically) a simulation such as an analog computer or a slide rule. Most mechanical calculators wer ...
designed by
Curt Herzstark
Curt Herzstark (January 26, 1902 – October 27, 1988) was an Austrian engineer. During World War II, he designed plans for a mechanical pocket calculator (the ''Curta'').
Life and career
Herzstark was born in Vienna, the son of Marie and Samuel ...
.
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
A grenade is an explosive weapon typically thrown by hand (also called hand grenade), but can also refer to a shell (explosive projectile) shot from the muzzle of a rifle (as a rifle grenade) or a grenade launcher. A modern hand grenade genera ...
also earned it the nickname "math grenade".
Curtas were considered the best portable calculators available until they were displaced by electronic calculators in the 1970s.
History
The Curta was conceived by
Curt Herzstark
Curt Herzstark (January 26, 1902 – October 27, 1988) was an Austrian engineer. During World War II, he designed plans for a mechanical pocket calculator (the ''Curta'').
Life and career
Herzstark was born in Vienna, the son of Marie and Samuel ...
in the 1930s in
Vienna
en, Viennese
, iso_code = AT-9
, registration_plate = W
, postal_code_type = Postal code
, postal_code =
, timezone = CET
, utc_offset = +1
, timezone_DST ...
,
Austria
Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
. By 1938, he had filed a key patent, covering his complemented stepped drum. 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
Nazi
Nazism ( ; german: Nazismus), the common name in English for National Socialism (german: Nationalsozialismus, ), is the far-right totalitarian political ideology and practices associated with Adolf Hitler and the Nazi Party (NSDAP) in ...
s forced him and his company to concentrate on manufacturing precision instruments for the German army.
Herzstark, the son of a Catholic mother and Jewish father, was taken into custody in 1943 and eventually sent to
Buchenwald concentration camp
Buchenwald (; literally 'beech forest') was a Nazi concentration camp established on hill near Weimar, Germany, in July 1937. It was one of the first and the largest of the concentration camps within Germany's 1937 borders. Many actual or su ...
, where he was encouraged to continue his earlier research:
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
Weimar is a city in the state of Thuringia, Germany. It is located in Central Germany between Erfurt in the west and Jena in the east, approximately southwest of Leipzig, north of Nuremberg and west of Dresden. Together with the neighbouri ...
, whose machinists were skilled enough to produce three working prototypes.
Soviet
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
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
Franz Joseph II (Franz Josef Maria Aloys Alfred Karl Johannes Heinrich Michael Georg Ignaz Benediktus Gerhardus Majella; 16 August 1906 – 13 November 1989) was the reigning Prince of Liechtenstein from 25 July 1938 until his death.
Franz Jose ...
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.
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 1970s.
The Curta, however, lives on, being a highly popular collectible, with thousands of machines working just as smoothly as they did at the time of their manufacture 40, 50 or 60 years previous.
An estimated 140,000 Curta calculators were made (80,000 Type I and 60,000 Type II). According to Curt Herzstark, the last Curta was produced in 1972.
Cost
The Curta Type I was sold for $125 in the later years of production, and the Type II was sold for $175. While only 3% of Curtas were returned to the factory for warranty repair,
a small, but significant number of buyers returned their Curtas in pieces, having attempted to disassemble them. Reassembling the machine was more difficult, requiring intimate knowledge of the orientation of, and installation order for, each part and sub-assembly, plus special guides designed to hold the pieces in place during assembly. Many identical-looking parts, each with slightly different dimensions, required test fitting and selection as well as special tools to adjust to design tolerances.
[Several specialized Curta tools pictured at curta.li](_blank)
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The machines currently have a high curiosity value and sell for around US$1,000, but can fetch as high as US$1,900 for models in pristine condition with notable serial numbers.
Design
Numbers are entered using slides (one slide per digit) on the side of the device. The ''revolution counter'' and ''result counter'' reside around the shiftable carriage, at the top of the machine. A single turn of the crank adds the input number to the result counter, at any carriage position, and increments the corresponding digit of the revolution counter. Pulling the crank upwards slightly before turning performs a subtraction instead of an addition. Multiplication, division, and other functions require a series of crank and carriage-shifting operations.
The Curta's design is a descendant of Gottfried Leibniz
Gottfried Wilhelm (von) Leibniz . ( – 14 November 1716) was a German polymath active as a mathematician, philosopher, scientist and diplomat. He is one of the most prominent figures in both the history of philosophy and the history of mathem ...
's Stepped Reckoner and Charles Thomas's Arithmometer
The arithmometer (french: arithmomètre) was the first digital mechanical calculator strong enough and reliable enough to be used daily in an office environment. This calculator could add and subtract two numbers directly and could perform lon ...
, accumulating values on cogs, which are added or complemented by a stepped drum mechanism.
Models
The Type I Curta has eight digits for data entry (known as "setting sliders"), a six-digit revolution counter, and an eleven-digit result counter. According to the advertising literature, it weighs only . Serial number 70154, produced in 1969, weighs .
Uses
The Curta was popular among contestants in sports car rallies during the 1960s, 1970s and into the 1980s. Even after the introduction of the electronic calculator for other purposes, they were used in time-speed-distance (TSD) rallies to aid in computation of times to checkpoints, distances off-course and so on, since the early electronic calculators did not fare well with the bounces and jolts of rally racing.
The Curta was also favored by commercial and general-aviation pilots before the advent of electronic calculators because of its precision and the user's ability to confirm the accuracy of their manipulations via the revolution counter. Because calculations such as weight and balance are critical for safe flight, precise results free of pilot error are essential.
Collections
The Curta calculator is very popular among collectors and can be purchased on many platforms. The Swiss entrepreneur and collector Peter Regenass holds a large collections of mechanical calculators among them over 100 Curta calculators. A part of his collections is on display at the Enter Museum
Enter is a museum for computer and consumer electronics in the Swiss town of Solothurn. Now a non-profit foundation ("Stiftung ENTER"), it originated as the project of Swiss entrepreneur Felix Kunz. It is the largest private technology collection ...
in Solothurn
Solothurn ( , ; french: Soleure ; it, Soletta ; rm, ) is a List of towns in Switzerland, town, a Municipalities of Switzerland, municipality, and the Capital (political), capital of the canton of Solothurn in Switzerland. It is located in the n ...
/Switzerland. In 2016 he donated a Curta calculator to the Yad Vashem Museum in Jerusalem.
Popular culture
The Curta plays a role in William Gibson
William Ford Gibson (born March 17, 1948) is an American-Canadian speculative fiction writer and essayist widely credited with pioneering the science fiction subgenre known as ''cyberpunk''. Beginning his writing career in the late 1970s, his ...
's ''Pattern Recognition'' (2003) as a piece of historic computing machinery as well as a crucial "trade" item.
In 2016 a Curta was designed by Marcus Wu that could be produced on a 3D printer.[ The 3D-Printed Curta Calculator](_blank)
on Thingiverse
Thingiverse is a website dedicated to the sharing of user-created digital design files. Providing primarily free, open-source hardware designs licensed under the GNU General Public License or Creative Commons licenses, the site allows contributor ...
() The Curta's fine tolerances are beyond the ability of present printer technology to produce at scale, so the printed Curta is about the size of a coffee can and weighs some three pounds.[This Retro Mechanical Calculator Has Gorgeous 3D-Printed Guts](_blank)
/ref>
Further reading
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References
External links
Vintage Calculators Web Museum: Mechanical Calculators
Curta.org
Video on internal workings of the Curta by MechanicalComputing
Many resources
http://www.curta.ch
Information about Curta / Video about the assembly of a Curta / Book about Curt Herzstark (Kein Geschenk für den Führer - Schicksal eines begnadeten Erfinders)
curta.li: model history, user and service manuals, parts photos, blueprints, etc.
Type and Age of your Curta
A 3D printed working model (reddit)
Curta.fr
Mainly focused on maintenance, repair and support. In french.
*
*{{cite journal , first=Herbert , last=Bruderer , title=A Multiple Curta , journal=Resurrection: The Bulletin of the Computer Conservation Society , issue=79 , date=Autumn 2017 , issn=0958-7403 , url=https://www.computerconservationsociety.org/resurrection/res79.htm#e
Computer-related introductions in 1948
1948 in Austria
Mechanical calculators
Austrian inventions