HP16C

A faithful recreation of the legendary HP 16C Computer Scientist calculator for iPhone, with a few modern upgrades.

If you've ever needed to perform hex arithmetic, bit manipulation, or base conversion on your phone and been frustrated by the available options, this is for you. RPN-16C gives you the full power of the original HP 16C in your pocket.

WHAT IT DOES

- Full RPN (Reverse Polish Notation) calculator

- Integer arithmetic in HEX, DEC, OCT, and BIN

- Configurable word size from 1 to 64 bits

- Unsigned, one's complement, and two's complement modes

- Complete bit operations: shift, rotate, rotate through carry, AND, OR, XOR, NOT, mask, bit set/clear/test, count bits, left justify

- Float mode with configurable precision (FLOAT 0-9)

- Keystroke programming with labels, subroutines, loops, and conditionals

- Storage registers with direct and indirect addressing

- Programs can be imported from text (long-press the display to paste)

ENHANCEMENTS OVER THE ORIGINAL

- Two-line display: see both X and Y registers at once. No more guessing what's on the stack.

- Wider LCD: displays all 32 bits in binary without scrolling. The original could only show 8 at a time.

- Haptic feedback on every key press

- State persistence: pick up right where you left off

- SHOW function to peek at values in other bases

FAIR WARNING

This is a quirky calculator. It uses Reverse Polish Notation, has no equals key, and expects you to know what two's complement means. If you're looking for a simple calculator, this is not it. If you've ever wished you could do a bitwise rotate through carry on your phone, welcome home.

DESIGNED FOR PROGRAMMERS

The key layout matches the physical HP 16C exactly, including the f (gold) and g (blue) shift labels. If you know the original, you already know this one. The original HP 16C Owner's Handbook is freely available on the Internet Archive: https://archive.org/details/hp-16c_handbook