Calculators

A calculator is a device for performing numerical calculations. The type is considered distinct from both a calculating machine and a computer in that the calculator is a special-purpose device that may not qualify as a Turing machine. more...

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Although modern calculators often incorporate a general purpose computer, the device as a whole is designed for ease of use to perform specific operations, rather than for flexibility. Also, modern calculators are far more portable than most other devices called computers, though many PDAs are comparable in size to handheld calculators.

Overview

In the near past, mechanical and clerical aids such as abacuses, 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 who did such work for a living using such aids as well as pen and paper. This semi-manual process of calculation was tedious and error-prone.

Modern calculators are electrically powered and are made by numerous manufacturers, in countless shapes and sizes varying from cheap, give-away, credit-card sized models to more sturdy adding machine-like models with built-in printers.

Electronic calculators

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 hard-wired integrated circuit logic. Today, most calculators are handheld microelectronic devices.

A basic calculator

The complexity of calculators varies with the intended purpose. A simple modern calculator, suitable for everyday activities such as shopping or checking a bill, might consist of the following parts:

• A power source, such as a battery or a solar panel
• A display, usually made from LED lights or liquid crystal (LCD), capable of showing a number of digits (typically 8 or 10)
• Electronic circuitry
• A keypad containing:
  • The ten digits, 0 through 9
  • The decimal point
  • The equals sign, to prompt for the answer
  • The four arithmetic functions (namely, addition, subtraction, multiplication and division)
  • A Cancel button, to clear the current calculation
  • On and off buttons
  • Other basic functions, such as square root and percentage (%).
• More advanced models may have a single-number memory, which can be recalled where necessary.

Since the late-1980s, it has become common to incorporate simple calculators in other small devices, such as mobile phones, pagers or wrist watches.

Advanced electronic calculators

More complex scientific calculators support trigonometric, statistical and other mathematical functions. The most advanced modern calculators can display graphics, and include features of computer algebra systems. They are also programmable; calculator applications include algebraic equation solvers, financial models and even games.

Read more at Wikipedia.org