| A calculator is a device for performing | | | | addition, subtraction, multiplication and |
| calculations. Although modern calculators | | | | division) |
| often incorporate a general purpose computer, | | | | |
| the device is designed for performing | | | | A Cancel button, to clear the current |
| specific operations, rather than for | | | | calculation |
| flexibility. For example, there are graphing | | | | |
| calculators which focus on graph-centered | | | | On and off buttons |
| math like Trigonometry and Statistics. Also, | | | | |
| modern calculators are more portable than | | | | Other basic functions, such as square root |
| most computers, though some PDAs are | | | | and percentage (%). |
| comparable in size to handheld calculators. | | | | |
| | | | More advanced models may have a single-number |
| Overview | | | | memory, which can be recalled where |
| | | | necessary. It might also have a Cancel Entry |
| In the past, mechanical clerical aids such as | | | | button, to clear the current numbers being |
| abaci, comptometers, Napier's bones, books of | | | | entered. |
| mathematical tables, slide rules, or | | | | |
| mechanical adding machines were used for | | | | Since the late-1980s, simple calculators have |
| numeric work. The word "calculator" denoted a | | | | been installed in other small devices, such |
| person who did such work for a living using | | | | as mobile phones, pagers or wrist watches. |
| such aids as well as pen and paper. This | | | | The wristwatch calculator was made popular by |
| semi-manual process of calculation was | | | | Dr. James Buccanon, president of the |
| tedious and error-prone. | | | | University of Pennsylvania. |
| | | | |
| Modern calculators are electrically powered | | | | Advanced electronic calculators |
| and come in countless shapes and sizes | | | | |
| varying from cheap, give-away, credit-card | | | | More complex scientific calculators support |
| sized models to more sturdy adding | | | | trigonometric, statistical and other |
| machine-like models with built-in printers. | | | | mathematical functions. The most advanced |
| | | | modern calculators can display graphics, and |
| Electronic calculators | | | | include features of computer algebra systems. |
| | | | They are also programmable; calculator |
| In the past, some calculators were as large | | | | applications include algebraic equation |
| as today's computers. The first mechanical | | | | solvers, financial models and even games. |
| calculators were mechanical desktop devices, | | | | Most calculators of this type can print |
| which were soon replaced by electromechanical | | | | numbers up to ten digits or decimal places in |
| desktop calculators, and then by electronic | | | | full on the screen. Scientific notation is |
| devices using first thermionic valves, then | | | | used to notate numbers up to a limit chosen |
| transistors, then hard-wired integrated | | | | by the calculator designer, such as |
| circuit logic. Today, most calculators are | | | | 9.999999999*1099. If a larger number or a |
| handheld microelectronic devices. | | | | mathematical expression yielding a larger |
| | | | number than this is entered (a common example |
| Basic configuration | | | | comes from typing "100!", read as "100 |
| | | | factorial") then the calculator might simply |
| The complexity of calculators varies with the | | | | display "error". |
| intended purpose. A simple modern calculator | | | | |
| might consist of the following parts: | | | | "Error" might also be displayed if a function |
| | | | or an operation is undefined mathematically; |
| A power source, such as a battery or a solar | | | | for example, division by zero or even roots |
| panel or both | | | | of negative numbers (most scientific |
| | | | calculators do not allow complex numbers, |
| A display, usually made from LED lights or | | | | though a few do have a special function for |
| liquid crystal (LCD), capable of showing a | | | | working with them). Some, but not most, |
| number of digits (typically 8 or 10) | | | | calculators do distinguish between these two |
| | | | types of "error", though when they do, it is |
| Electronic circuitry | | | | not easy for the user to understand because |
| | | | they are usually given as "error 1" or "error |
| A keypad containing: | | | | 2". |
| | | | |
| The ten digits, 0 through 9 | | | | Only a few companies develop and make modern |
| | | | professional engineering and finance |
| The decimal point | | | | calculators: The most well-known are Casio, |
| | | | Sharp, Hewlett-Packard (HP) and Texas |
| The equals sign, to prompt for the answer | | | | Instruments (TI). Such calculators are good |
| | | | examples of embedded systems. |
| The four arithmetic functions (namely, | | | | |