Such software calculators first emerged in the 1980s as part of the original Macintosh operating system (System 1) and the Windows operating system (Windows 1.0). Some software calculators directly simulate one of the hardware calculators, by presenting an image that looks like the calculator, and by providing the same functionality. Software calculators on the Internet There is now a very wide range of software calculators, and searching the Internet produces very large numbers of programs that are called calculators. The results include numerical calculators that apply arithmetic operations or mathematical functions to numbers, and that produce numerical results or graphs of numerical functions, plus some non-numerical tools and games that are also called calculators. Many of the results are calculators that do not imitate or simulate hardware calculators, but that take advantage of the greater power of computer software to implement alternative types of calculators. Software calculators are provided on the Internet which are customizable to use any conceivable algebraic expression. These user-customizable software calculators can also be used in conjunction with formula or equation creation capabilities so that the software calculator can now be created to perform all possible mathematical functions. No longer limited to a set of trigonometric and simple algebraic expressions, versions of the software calculator are now tailored to any and all topical applications. Examples Numerical calculators Every type of hardware calculator has been implemented in software, including conversion, financial, graphing, programmable and scientific calculators. Other numerical calculators that do not imitate hardware calculators include: Formula calculators Window-based calculators Specialised calculators. Window-based calculators Window-based calculators present a dialog box that allows users to enter data, rather than data and operations, and they have a built-in formula that is automatically applied to this data. There are many examples of such calculators in finance, mathematics, science and other disciplines. Specialised calculators There are software calculators that contain operations relevant to a specific application area and profession, including automotive, construction and electrical engineering. Non-numerical tools Non-numerical calculators include life-style and scientific calculators: Love calculator: The input is two names, and there is a button to work out the compatibility, as a percentage, of two people with these names. Formula weight calculator: The input is a chemical molecular formula, using the periodic-table symbols and notation, and there is a button to work out the percentages of its constituents. Astronomical calculator: The input is a date and one or multiple celestial