This is a 512-byte boot sector demo running in a PC emulator (in 16-bit mode). It uses 8087 floating-point instructions, and accesses VGA hardware directly. (Credit to v86 for the excellent x86 PC emulator, incidentally using a Wasm backend which is pretty cool!)
Source: github.com/cfallin/treeos. Originally developed in 2019, but finally posted online in an emulator in 2025.
Happy holidays!
-- cfallin