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