nanochess/bootOS — reverse-engineered prompt

Build me a tiny educational operating system that fits inside a single 512 byte boot sector for an old IBM PC compatible machine. I want to assemble it into a floppy image and boot it in QEMU or VirtualBox.

When it starts, it should show a simple text prompt. It needs basic commands to format the disk area, list files, delete a file, enter raw hex bytes for a tiny program, save that program with a name, run it, and return to the prompt when the program exits.

Keep the filesystem very small and easy to understand, about 32 files max, with each file taking one sector. This is not meant to be a modern OS, it’s more like a fun retro demo that proves an OS can load, run, and save tiny programs from a bootable floppy image.

Please include the assembly source, a build command, a ready to run image if possible, and short instructions for testing it in an emulator.