The Curta calculator can also do multiplication and division.

* Curta calculator

Cayce strikes a deal with him: she buys a Curta calculator for him and he finds the email address to which the watermark code was sent.

Using 20th-century relics, such as a Curta calculator, an excavated Stuka, Hobbs Baranov, and Voytek's planned ZX81 show, Gibson raises the question of how a contemporary society views past societies.

* The Curta calculator used the method of complements for subtraction, and managed to hide this from the user.

A Curta mechanical calculator

A partially disassembled Curta calculator, showing the digit slides and the stepped drum behind them

Curta Type I calculator showing view from top

Curta Type I calculator showing view from bottom

Curta ( Type I ) mechanical calculator shown in the operational position ( left hand ).

The Curta is a small, hand-cranked mechanical calculator introduced by Curt Herzstark in 1948.

This drum would prove to be the key to the small, hand-held mechanical calculator the Curta would become.

* Curta calculator

Curta ( Type I ) mechanical calculator shown in the operational position ( left hand ).

During World War II, Curt Herzstark's plans for a mechanical pocket calculator ( the Curta ) literally saved his life.

* Biographical information about Curt Herzstark and the Curta calculator.

In 1948, the Curta was introduced.

The Curta was conceived by Curt Herzstark ( 1902 – 1988 ) in the 1930s in Vienna, Austria.

The Curta Type I was sold for $ 125 in the later years of production ; the Type II was sold for $ 175.

The Curta was affectionately known as the " pepper grinder " or " peppermill " due to its shape and means of operation.

According to Curt Herzstark, the last Curta was produced in 1972.

The Curta was popular among contestants in sports car rallies during the 1960s, 1970s and into the 1980s.

The Curta was also favored by both commercial and general-aviation pilots, before the advent of electronic calculators, because of both its precision and the user's ability to confirm the accuracy of his or her manipulations via the revolution counter.

For example, Florin Curta, among others, suggested that the DAI was a political document, rather than a strictly historical one.

Many historians ( e. g., György Györffy, Florin Curta ) suggest that at the time of the Hungarian conquest Árpád was the gyula, who was later considered to be the ancestor of the dynasty that ruled Hungary until 1301.

By the early 1970s electronic pocket calculators ended manufacture of mechanical calculators, although the Curta remains a popular collectable item.

Florin Curta suggests that when the kende of the conquest ( whom he does not name ) died in 902, the leadership passed onto Árpád, and one of Árpád ’ s kinsmen became gyula.

The Type I Curta has 8 digits for data entry ( known as " setting sliders "), a 6-digit revolution counter, and an 11-digit result counter.

The larger Type II Curta, introduced in 1954, has 11 digits for data entry ( known as " setting sliders "), an 8-digit revolution counter, and a 15-digit result counter.

* F. Curta, " Byzantium in dark-age Greece ( the numismatic evidence in its Balkan context )", Byzantine and Modern Greek Studies 29 ( 2005 ), 113-45.

Mechanical calculators, like the base-ten addiator, the comptometer, the Monroe, the Curta and the Addo-X remained in use until the 1970s.

* F. Curta, The Making of the Slavs: History and Archaeology of the Lower Danube Region, Cambridge University Press, Cambridge 2001, ISBN 0-521-80202-4.

* Curta, Florin The Making of the Slavs.

The Curta, however, lives on, being a highly-popular collectible, with thousands of machines working just as smoothly as they did 40, 50, and 60 years ago when they were manufactured.

While only 3 % of Curtas were returned to the factory because of repairs under warranty, a small, but significant number of buyers returned the Curta in pieces.

Many purchasers attempted to disassemble the Curta.

* Curta. org

Babbage's first attempt at a mechanical computing device, the Difference Engine, was a special-purpose calculator designed to tabulate logarithms and trigonometric functions by evaluating finite differences to create approximating polynomials.

The Apple I was Apple's first product, and to finance its creation, Jobs sold his only means of transportation, a VW van and Wozniak sold his HP-65 calculator for $ 500.

In 2002, a homebrew version for the TI-83 graphing calculator was released.

Later, the Antikythera mechanism, invented some time around 100 AD in ancient Greece, was the first mechanical calculator utilizing gears of various sizes and configuration to perform calculations, which tracked the metonic cycle still used in lunar-to-solar calendars, and which is consistent for calculating the dates of the Olympiads.

Commodore soon had a profitable calculator line and was one of the more popular brands in the early 1970s, producing both consumer as well as scientific / programmable calculators.

The first solid state electronic calculator was created in the 1960s, building on the extensive history of tools such as the abacus, developed around 2000 BC ; and the mechanical calculator, developed in the 17th century.

By the end of that decade, calculator prices had reduced to a point where a basic calculator was affordable to most and they became common in schools.

He was followed by Gottfried Leibniz who spent forty years designing a four-operation mechanical calculator, inventing in the process his leibniz wheel, but who couldn't design a fully operational machine.

The Arithmometer, invented in 1820 as a four-operation mechanical calculator, was released to production in 1851 as an adding machine and became the first commercially successful unit ; forty years later, by 1890, about 2, 500 arithmometers had been sold plus a few hundreds more from two arithmometer clone makers ( Burkhardt, Germany, 1878 and Layton, UK, 1883 ) and Felt and Tarrant, the only other competitor in true commercial production, had sold 100 comptometers.

The Casio Computer Company, in Japan, released the Model 14-A calculator in 1957, which was the world's first all-electric ( relatively ) " compact " calculator.

There were great efforts to put the logic required for a calculator into fewer and fewer integrated circuits ( chips ) and calculator electronics was one of the leading edges of semiconductor development.

The Canon Pocketronic was a development of the " Cal-Tech " project which had been started at Texas Instruments in 1965 as a research project to produce a portable calculator.

Sharp put in great efforts in size and power reduction and introduced in January 1971 the Sharp EL-8, also marketed as the Facit 1111, which was close to being a pocket calculator.

Pico was a spinout by five GI design engineers whose vision was to create single chip calculator ICs.

The first truly pocket-sized electronic calculator was the Busicom LE-120A " HANDY ", which was marketed early in 1971.

Made in Japan, this was also the first calculator to use an LED display, the first hand-held calculator to use a single integrated circuit ( then proclaimed as a " calculator on a chip "), the Mostek MK6010, and the first electronic calculator to run off replaceable batteries.