RPN Calculator is a reverse polish notation programmable calculator for science and engineering. It supports over 180 functions and 11 data types (real, integer, variable, vector, matrix, list, program, unit, complex, string, and tag). The stack, variables, and programs can be saved and reloaded. The number of levels of stack that can be used is virtually unlimited. If the number of levels in the stack exceeds the display, you can scroll up or down to see more. RPN Calculator is compatible with Windows 95, 98, Me, NT 4.0, and 2000. The $20 reg fee includes the Windows CE version.