ES-Calc - Version 2.1a A calculator designed to be used by scientists and engineers. It allows evaluation of complex expressions and can handle most any function contained on a scientific calculator. An expression is entered in a form similar to a formula in a spread sheet. Previously entered expressions can be recalled. Registers are available to store and reuse answers. A very wide range of conversion factors are also available. Has a Hex/Octal/Binary Converter. Does clock arithmetic and much more. A great value.