Calculators

A calculator is a device for performing mathematical calculations, distinguished from a computer generally by a limited problem domain and an interface optimized for interactive calculation rather than programming. more...

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Calculators can be hardware or software, and mechanical or electronic, and are often built into devices such as PDAs or mobile phones.

Modern electronic calculators are generally small (often pocket-sized) and usually inexpensive. In addition to general purpose calculators, there are those designed for specific markets; for example, there are scientific calculators which focus on advanced math like trigonometry and statistics. Modern calculators are more portable than most computers, though most PDAs are comparable in size to handheld calculators.

Overview

In the past, mechanical clerical aids such as abaci, comptometers, Napier's bones, books of mathematical tables, slide rules, or mechanical adding machines were used for numeric work. This semi-manual process of calculation was tedious and error-prone.

Modern calculators are electrically powered (usually by battery and/or solar cell) and vary from cheap, give-away, credit-card sized models to sturdy adding machine-like models with built-in printers. They first became popular in the late 1960s as decreasing size and cost of electronics made possible devices for calculations, avoiding the use of scarce and expensive computer resources. By the 1980s, calculator prices had reduced to a point where a basic calculator was affordable to most. By the 1990s they had become common in math classes in schools, with the idea that students could be freed from basic calculations and focus on the concepts.

Computer operating systems as far back as early Unix have included interactive calculator programs such as dc and hoc, and calculator functions are included in almost all PDA-type devices (save a few dedicated address book and dictionary devices).

Electronic calculators

In the past, some calculators were as large as today's computers. The first mechanical calculators were mechanical desktop devices which were replaced by electromechanical desktop calculators, and then by electronic devices using first thermionic valves, then transistors, then hard-wired integrated circuit logic. By the mid-1970s, pocket-sized calculators based on ICs were routinely available, often at prices less than $100, and by the early 1980s the LED displays of 1970s units had been replaced by power-saving liquid crystal displays. Modern electronic calculators range in size from keychain-sized units only a couple of centimeters long all the way up to desktop calculators the size of a textbook, and in complexity from very basic up to graphing calculators capable of video display and sometimes extensive general-purpose programming capability.

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