The latest version of the KeyCalc calculator is available from
http://pmoylan.org/pages/os2/keycalc.html
KeyCalc is a free and open-source scientific calculator, supporting
* the usual trigonometric, etc., functions
* your choice of algebraic or Reverse Polish notation (RPN)
* your choice of real or complex arithmetic
* binary, octal, decimal, or hexadecimal
* ten memory cells, of which four are visible on the screen
* the first few elements of the calculation stack are visible
* fonts and colours may be changed by the usual operation of dropping them from a palette.
-- Peter Moylan
http://www.pmoylan.org
Source: eCSoft/2