Calculator
From Academic Kids

A calculator is a device for performing numerical calculations. It should not be confused with a calculating machine. Nowadays many people have a calculator with them as part of their mobile phone and/or personal digital assistant. Engineers and accountants make use of calculators for problems where a computation is not complex enough to demand the use of a generalpurpose computer. In most developed countries, Students use calculators for schoolwork. Also, some wrist watches contain a calculator (although this was more a fad of the 1980s).
Contents 
Overview
Today calculators are electrically powered, most often by battery, and are made by numerous manufacturers, in countless shapes and sizes varying from cheap, giveaway, creditcard sized models to more sturdy adding machinelike models with builtin printers. Only a very few companies develop and make modern professional engineering and finance calculators; the most wellknown are Casio, HewlettPackard (HP) and Texas Instruments (TI). Such calculators are good examples of embedded systems.
In the near past, mechanical and clerical aids such as abaci, comptometers, Napier's bones, books of mathematical tables, slide rules, adding machines, were used for serious numeric work, and the word "calculator" denoted a person (most often male) who did such work for a living using such aids as well as pen and paper. This semimanual process of calculation was tedious and errorprone.
Electronic calculators
Today most calculators are handheld microelectronic devices, but in the past some calculators were as large as today's computers. The first mechanical calculators were mechanical desktop devices, which were soon replaced by electromechanical desktop calculators, and then by electronic devices using first thermionic valves, then transistors, then hardwired integrated circuit logic.
A pocket calculator is a small batterypowered or solar powered electronic digital computer made possible by integrated circuit and semiconductor technology. Typically they are limited to an 8–10 digit singlenumber display and a few basic functions of arithmetic, but some modern ones have more of the features of a generalpurpose computer. Pocket calculators rendered the slide rule obsolete.
Calculators vary in their capabilities. Some are limited to only basic arithmetic; others support trigonometric and other mathematical functions. The most advanced modern calculators are programmable, can display graphics, and include features of computer algebra systems.
History
One of the first calculators was Pascal's calculator invented in 1645. This was used for taxes in France until 1799. Later on in 1954, IBM demonstrated a large alltransistor calculator. In 1957, IBM released the first commercial alltransistor calculator (the IBM 608). The first handheld calculators, as opposed to desktop ones, went on sale in 1970 with models from Japanese manufacturers Sharp and Canon weighing around 1.7 lb (770 g).
1970s to mid1980s
The first pocketsized calculator, the Bowmar 901B measuring 5.2×3.0×1.5 in (131×77×37 mm), came out in the fall of 1971, with four functions and an eightdigit red LED display, for $240, while in August 1972 the fourfunction Sinclair Executive became the first slimline pocket calculator measuring 5.4×2.2×0.35 in (138×56×9 mm) and weighing 2.5 oz (70g). It retailed for around $150 (GB£79). By the end of the decade, similar calculators were priced less than $10 (GB£5).
The first pocket calculator with scientific functions, i.e. the first slide rulereplacing model, was the 1972 HP35 from Hewlett Packard (HP); it, along with all later HP engineering calculators, used reverse Polish notation (RPN) (where a calculation like "6 – 2" is performed by pressing "6", "Enter↑", "2", and "–"; instead of algebraically: "6", "–", "2", "=").
Most common among early scientific calculators was the TI30 from Texas Instruments (TI). The first programmable handheld calculator was the HP65, in 1974; it had a capacity of 100 instructions, and could store and retrieve programs with a builtin magnetic card reader. A year later the HP25C introduced continuous memory, i.e. programs and data were retained in memory during poweroff. In 1979, HP released the first alphanumeric, programmable, expandable calculator, the HP41C. It could be expanded with RAM (memory) and ROM (software) modules, as well as peripherals like bar code wands, cassette tape and floppy disk drives, paperroll printers, and miscellaneous communication interfaces (RS232, HPIL, HPIB).
Mid1980s to date
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In March 2002, HP announced that the company would no longer produce calculators, which was hard to fathom for some fans of the company's products; the HP48 range in particular had an extremely loyal customer base. Nevertheless, HP restarted their production of calculators in late 2003. The new models, however, reportedly didn't have the mechanical quality and sober design HP's earlier calculators were famous for (instead featuring the more "youthful" look and feel of contemporary competing designs from TI).
The business calculator HP12C is still produced. It was introduced in 1981 and is still being made with nearly no changes. In 2003 several new models were released, including an improved version of the HP12C, the "HP12C platinum edition".
Trivia
 The word "calculator" is occasionally used as a pejorative term to describe an inadequately capable generalpurpose microcomputer. The synonym of this meaning is "bitty box", as discussed in the Jargon file.
 A curious episode of the mid 1970s involved the Melcor 635, a scientific calculator with a bug in its trigonometric functions. Because the CORDIC algorithms used in most calculators cannot compute the inverse functions of zero, these need to be hardcoded —and some engineer at Melcor got it wrong. For any input other than exactly zero, even for instance 1.0E99, the calculator worked correctly; the user simply had to remember not to compute the arccosine of zero. The company discovered this after making 50,000 calculators. The upshot was an advertisement in Scientific American headlined 'Somebody Goofed', offering these calculators for sale at halfprice.
 As many schoolchildren and students know, some words and simple phrases can be written using an ordinary sevensegment display calculator; this involves entering certain numbers and then viewing the resulting words from the opposite side of the calculator display. Typical words/phrases obtainable in this fashion are (some of them, not surprisingly, quite representative of the demographic in question):
See also
General interest:
Mechanical calculators:
Electronic calculators:
Patents
 Template:US patent  Complex computer  G. R. Stibitz (electromachanic device that would calculate, record, and print results)
 Template:US patent  Miniature electronic calculator  J. S. Kilby (TI electromachanic device)
External links
 Online Calculator Software (http://web.peoriadesignweb.com/calculator)
 Scientific Calculator (http://ostermiller.org/calc/calculator.html)  Scientific notation, hex, octal, decimal, binary, and math functions. Requires JavaScript. (from ostermiller.org)
 The Old Calculator Web Museum (http://www.oldcalculatormuseum.com)
 Calculator Museum (http://www.calculators.de)
 Museum of Soviet Calculators (http://www.taswegian.com/MOSCOW/soviet.html)
 Soviet Calculators Collection (http://www.rk86.com/frolov/calcolle.htm)
 Vintage Calculators (http://www.vintagecalculators.com/index.html)
 various calculators (http://www.lendingok.com)
 Broken Calculator (http://www.cuttheknot.org/Curriculum/Arithmetic/BrokenCalculator.shtml)
 GraphCalc – an Open Source graphing calculator program (http://www.graphcalc.com)
 HiDigit scientific calculator (http://www.binarythings.com/hidigit/)
 The Museum of HP Calculators (http://www.hpmuseum.org) (slide rules/mech. section (http://www.hpmuseum.org/prehp.htm))
 HP Calculator Wiki (http://www.hydrix.com/wiki/)
 On TI's US Patent No. 3,819,921 (http://www.ti.com/corp/docs/company/history/calc.shtml)
 Library of online calculators (http://www.mortgageloansolutions.com/calculators.htm)da:Lommeregner
de:Taschenrechner es:Calculadora fr:Calculatrice he:מחשבון nl:Rekenmachine ja:電卓 pl:Kalkulator pt:Calculadora ru:Калькулятор sl:računalo sv:Miniräknare zh:电子计算机