It uses Reverse Polish Notation (RPN), which uses the ENTER key instead of the "=" (equals) key. In addition to all the functions you'd expect from an ordinary calculator, WRPN 16c also has many features specifically designed for the computer professional: • Word sizes from 1-64 bits per word • Signed math (1's complement, 2's complement, unsigned) • Logical operators (and, or, xor, not, masks, etc) • Bit-wise operators (shift, rotate, rotate with carry, etc) • 32 storage registers • 4 position stack • 203 lines of program memory WRPN 16c is available on other platforms, such as Windows, MacOS, and Linux from the following web site http://www.wrpn.emmet-gray.com Note: The source code to WRPN 16c is also available!