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!