Programmer's calculator that simulates an HP 16C. It simulates the appearance and behavior of the original, including the seven-segment display, and the little blink you get when entering numbers. The 16C's windowing functions are implemented, but can be disabled to allow the display of longer numbers at one time.
Full source is available on Github. There is no advertising of any kind -- this is a hobby project, and a bit of a labor of love.
Do be aware that the 16C is a calculator intended for computer programmers. If you're not familiar with hexadecimal or stack-based RPN calculators, this probably isn't what you're looking for!