There’s something about Reverse Polish Notation (RPN) and the calculators that use it. It calls to mind a time when a calculator was a serious tool, and not just a throwaway toy. Created in the legacy of such calculators by HP and Texas Instruments, [Simon Boak] shows off his SB116, sporting an Arduino Nano under the hood. It’s a fully custom design, with a hand-built metal case, a custom PCB for the keyboard, and a tiny OLED display for maximum retro green goodness.
The impetus for this build was to replace a particular calculator, a well-used TI Programmer, that’s useful for working with 6502 assembly. The SB116 supports binary, octal, decimal, and hex; and boasts some downright useful functions — AND, NOT, OR, XOR, and bitshifts. The source code is available, but you’re on your own for the case and keyboard. And for maximized retro faux-nostalgia, [Simon] designed a box that would have looked right at home on an 80s store shelf.