Did you ever feel like your life was missing a fully bootable RPN calculator in less than 512 bytes? No? Doesn't matter, I made it anyway.
This is a pretty simple implementation of a calculator, and doesn't use any super fancy space-saving techniques but still manages to fit in under the required 512 bytes to fit into a PC boot sector.
The only requirement in terms of software to compile it is a copy of nasm.
You can make the bootsector by running make. To run it you'll need qemu,
if you've got that you can run make run to run the program.