Tiny bare-metal programs: Mandelbrot in 88 bytes, an OS in 512 bytes

As a warm up:

With all that setting the scene done, let’s get down to how I wrote an 88-byte 8086 bare-metal mandelbrot generator.

An 88 Byte Bare-Metal Mandelbrot Generator

And here’s Óscar Toledo G’s BootOS:

bootOS is a monolithic operating system that fits in one boot sector. It’s able to load, execute, and save programs. Also keeps a filesystem. It can work with any floppy disk size starting at 180K.

[Side note; the Familia Toledo are performing a ground-up computing crusade. Here’s their $99 computer with homegrown OS and web browser.]

In the HN discussion about BootOS, we see many interesting points and links, and more offerings:
bootBASIC, a 512-byte application for BootOS
SaxOS another, unrelated, OS in 512 bytes

Oh, and it seems there was an annual contest for 512 byte operating systems.