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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 "X" in all current TI-30 models refers to the addition of a 10+2 display (that is, a 10 digit mantissa plus a 2-digit exponent) in 1993; with the addition of a 2-line display and a D-pad in the XIIS/XIIB in 1999, the TI-30 line split in 2, with the TI-30Xa becoming TI's overall entry-level scientific, and the enhanced XII designs offering ...
The FX-603P was a programmable calculator, manufactured by Casio from 1990. It was the successor model to the Casio FX-602P . Since it was only released in a limited number of countries in small quantities, it is now an excessively rare item which commands high prices when sold.
For example, the principal square root of 9 is 3, which is denoted by √ 9 = 3, because 3 2 = 3 • 3 = 9 and 3 is nonnegative. However raising x to the power of 0.5 using the y x key works if the number is entered as a real number with a complex part equal to zero. [11] Inverse and hyperbolic trigonometry functions cannot be used with complex ...
With an eight-digit display, the calculator could display positive numbers between 0.0000001 and 99,999,999, and negative numbers between -0.000001 and -9,999,999. [12] Calculators of the time tended to have displays of between 3 and 12 digits, as reducing the number of digits was an effective way of reducing the cost of the calculator.
The Cambridge had been preceded by the Sinclair Executive, Sinclair's first pocket calculator, in September 1972.At the time, the Executive was smaller and noticeably thinner than any of its competitors, at 56 by 138 by 9 millimetres (2.20 in × 5.43 in × 0.35 in), fitting easily into a shirt pocket.
The Executive impressed the engineers at Texas Instruments, who had used the same chip to produce a longer and wider calculator that was over three times as thick and a great deal more expensive. [10] In 1974, sales of the Executive exceeded £2.5 million, and Sinclair was producing 100,000 calculators each month, of which 55% were exported. [11]
The product was named Otis King's Patent Calculator, and was manufactured and sold by Carbic Ltd. in London from about 1922 to about 1972. With a log-scale decade length of 66 inches, the Otis King calculator should be about a full digit more accurate than a 6-inch pocket slide rule.