While most operating systems are written in C and C++, KolibriOS is written in pure x86 assembly and as a result small and lightweight enough to run off a standard 1.44 MB floppy disk, as demonstrated ...
KolibriOS fits on a single floppy disk, updated as recently as a few months ago. Despite its old-school appearance, it features a full GUI and internet connectivity. If interested, download the image ...