Software calculator  A software calculator is a calculator that has been implemented as a computer program, rather than as a physical hardware device. They are among the simpler interactive software tools, and, as such, they:  As a "calculator", rather than a computer, they usually:  Software calculators are available for many different platforms, and they can be:  Computers as we know them today first emerged in the 1940s and 1950s. The software that they ran was naturally used to perform calculations, but it was specially designed for a substantial application that was not limited to simple calculations. For example, the LEO computer was designed to run business application software such as payroll. Software specifically to perform calculations as its main purpose was first written in the 1960s, and the first software package for general calculations to obtain widespread use was released in 1978. This was VisiCalc and it was called an "interactive visible calculator", but it was actually a spreadsheet, and these are now not normally known simply as calculators. The Unix version released in 1979, V7 Unix, contained a command-line accessible calculator. Calculators have been used since ancient times and until the advent of software calculators they were physical, hardware machines. The most recent hardware calculators are electronic hand-held devices with buttons for digits and operations, and a small window for inputs and results. The first software calculators imitated these hardware calculators by implementing the same functionality with mouse-operated, rather than finger-operated, buttons. 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. 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.