I remember VxWorks. Bigger than a while loop, but used in space missions back in the 90s: http://www.windriver.com/inspace/ http://www.windriver.com/inspace/

I remember VxWorks. Bigger than a while loop, but used in space missions back in the 90s: http://www.windriver.com/inspace/ http://www.windriver.com/inspace/ Edit: looks like VxWorks wants a 32-bit CPU, 128KB of ROM, and 1-2MB of RAM. But you get threads, networking, filesystem, etc.