![]() Curta Type II mechanical calculator | |
Type | Mechanical calculator |
---|---|
Manufacturer | Contina AG Mauren |
Introduced | 1948 (Type I) 1954 (Type II) |
Discontinued | 1972 |
Date invented | 1930s |
Invented by | Curt Herzstark |
Cost | $125 (Type I) $165 (Type II) |
Calculator | |
Precision | 11 digits (Type I) 15 digits (Type II) |
Display type | Mechanical counter |
Display size | 6-digit revolution counter, 11-digit result counter (Type I) 8-digit revolution counter, 15-digit result counter (Type II) |
Other | |
Weight | 230g (Type I) 360g (Type II) |
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]
Curtas were considered the best portable calculators available until they were displaced by electronic calculators in the 1970s. [1]
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 1970s. [1] 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. [1] [6] [7]
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. [6]
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, [6] 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. [8]
The machines have a high curiosity value; in 2016 they sold for around US$1,000, but buyers paid as much as US$1,900 for models in pristine condition with notable serial numbers. [5]
The Curta's design is a descendant of Gottfried Leibniz's Stepped Reckoner and Charles Thomas's Arithmometer, accumulating values on cogs, which are added or complemented by a stepped drum mechanism.
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 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 8 ounces (230 g). Serial number 70154, produced in 1969, weighs 245 grams (8.6 oz).
The larger Type II Curta, introduced in 1954, has eleven digits for data entry, an eight-digit revolution counter, and a fifteen-digit result counter. [9]
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 rallying. [1]
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.
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 collection of mechanical calculators, among them over 100 Curta calculators. A part of his collections is on display at the Enter Museum in Solothurn, Switzerland. In 2016 he donated a Curta calculator to the Yad Vashem Museum in Jerusalem. [10]
The Curta plays a role in William Gibson'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. [11] The Curta's fine tolerances were beyond the ability of printer technology of 2017 to produce to scale, so the printed Curta was about the size of a coffee can and weighed about three pounds. [12]
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: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)An electronic calculator is typically a portable electronic device used to perform calculations, ranging from basic arithmetic to complex mathematics.
An adding machine is a class of mechanical calculator, usually specialized for bookkeeping calculations. In the United States, the earliest adding machines were usually built to read in dollars and cents. Adding machines were ubiquitous office equipment until they were phased out in favor of calculators in the 1970s and by personal computers beginning in about 1985. The older adding machines were rarely seen in American office settings by the year 2000.
The ANITA Mark VII and ANITA Mark VIII calculators were launched simultaneously in late 1961 as the world's first all-electronic desktop calculators. Designed and built by the Bell Punch Co. in Britain, and marketed through its Sumlock Comptometer division, they used vacuum tubes and cold-cathode switching tubes in their logic circuits and nixie tubes for their numerical displays.
In mathematics and computing, the method of complements is a technique to encode a symmetric range of positive and negative integers in a way that they can use the same algorithm for addition throughout the whole range. For a given number of places half of the possible representations of numbers encode the positive numbers, the other half represents their respective additive inverses. The pairs of mutually additive inverse numbers are called complements. Thus subtraction of any number is implemented by adding its complement. Changing the sign of any number is encoded by generating its complement, which can be done by a very simple and efficient algorithm. This method was commonly used in mechanical calculators and is still used in modern computers. The generalized concept of the radix complement is also valuable in number theory, such as in Midy's theorem.
The Comptometer was the first commercially successful key-driven mechanical calculator, patented in the United States by Dorr Felt in 1887.
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 were comparable in size to small desktop computers and have been rendered obsolete by the advent of the electronic calculator and the digital computer.
A slide calculator, also known as an Addiator after the best-known brand, is a mechanical calculator capable of addition and subtraction, once made by Addiator Gesellschaft of Berlin, Germany. Variants of it were manufactured from 1920 until 1982. The devices were made obsolete by the electronic calculator.
Starting at the end of the nineteenth century, well before the advent of electronic computers, data processing was performed using electromechanical machines collectively referred to as unit record equipment, electric accounting machines (EAM) or tabulating machines. Unit record machines came to be as ubiquitous in industry and government in the first two-thirds of the twentieth century as computers became in the last third. They allowed large volume, sophisticated data-processing tasks to be accomplished before electronic computers were invented and while they were still in their infancy. This data processing was accomplished by processing punched cards through various unit record machines in a carefully choreographed progression. This progression, or flow, from machine to machine was often planned and documented with detailed flowcharts that used standardized symbols for documents and the various machine functions. All but the earliest machines had high-speed mechanical feeders to process cards at rates from around 100 to 2,000 per minute, sensing punched holes with mechanical, electrical, or, later, optical sensors. The operation of many machines was directed by the use of a removable plugboard, control panel, or connection box. Initially all machines were manual or electromechanical. The first use of an electronic component was in 1937 when a photocell was used in a Social Security bill-feed machine. Electronic components were used on other machines beginning in the late 1940s.
The arithmometer 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 long multiplications and divisions effectively by using a movable accumulator for the result.
Curt Herzstark was an Austrian engineer. During World War II, he designed plans for a mechanical pocket calculator.
Pascal's calculator is a mechanical calculator invented by Blaise Pascal in 1642. Pascal was led to develop a calculator by the laborious arithmetical calculations required by his father's work as the supervisor of taxes in Rouen. He designed the machine to add and subtract two numbers directly and to perform multiplication and division through repeated addition or subtraction.
A pinwheel calculator is a class of mechanical calculator described as early as 1685, and popular in the 19th and 20th century, calculating via wheels whose number of teeth were adjustable. These wheels, also called pinwheels, could be set by using a side lever which could expose anywhere from 0 to 9 teeth, and therefore when coupled to a counter they could, at each rotation, add a number from 0 to 9 to the result. By linking these wheels with carry mechanisms a new kind of calculator engine was invented. Turn the wheels one way and one performs an addition, the other way a subtraction.
The stepped reckoner or Leibniz calculator was a mechanical calculator invented by the German mathematician Gottfried Wilhelm Leibniz around 16 and completed in 1694. The name comes from the translation of the German term for its operating mechanism, Staffelwalze, meaning "stepped drum". It was the first calculator that could perform all four basic arithmetic operations.
Frank Stephen Baldwin was an American who invented a pinwheel calculator in 1875. He started the design of a new machine in 1905 and was able to finalize its design with the help of Jay R. Monroe who eventually bought the exclusive rights to the machine and started the Monroe Calculating Machine Company to manufacture it.
A mechanical computer is a computer built from mechanical components such as levers and gears rather than electronic components. The most common examples are adding machines and mechanical counters, which use the turning of gears to increment output displays. More complex examples could carry out multiplication and division—Friden used a moving head which paused at each column—and even differential analysis. One model, the Ascota 170 accounting machine sold in the 1960s, calculated square roots.
Ryōichi Yazu was a Japanese inventor. He is best known for his invention of Japan's first mechanical calculator.
A Leibniz wheel or stepped drum is a cylinder with a set of teeth of incremental lengths which, when coupled to a counting wheel, can be used in the calculating engine of a class of mechanical calculators. Invented by Leibniz in 1673, it was used for three centuries until the advent of the electronic calculator in the mid-1970s.
The Millionaire was the first commercially successful mechanical calculator that could perform a direct multiplication. It was in production from 1893 to 1935 with a total of about five thousand machines manufactured.
The Odhner Arithmometer was a very successful pinwheel calculator invented in Russia in 1873 by W. T. Odhner, a Swedish immigrant. Its industrial production officially started in 1890 in Odhner's Saint Petersburg workshop. Even though the machine was very popular, the production only lasted thirty years until the factory was nationalised and closed down during the Russian revolution of 1917.
The Fuller calculator, sometimes called Fuller's cylindrical slide rule, is a cylindrical slide rule with a helical main scale taking 50 turns around the cylinder. This creates an instrument of considerable precision – it is equivalent to a traditional slide rule 25.40 metres long. It was invented in 1878 by George Fuller, professor of engineering at Queen's University Belfast, and despite its size and price it remained on the market for nearly a century because it outperformed nearly all other slide rules.