I wanted a realtime operating system to experiment with so I could understand something about the field. So I looked for an alternative and Linux was just starting to be widely available. Linux has been wonderful. The strength of the Linux kernel development group is scary. All those and more.
Operating systems is, of course, the most interesting field in computer science.
Trying to avoid overdesign. It is really tempting to put features into code either because they seem clever or because they are standard. I've thrown out of lot of my code and many nice ideas. The current version is the result of three total re-writes and there is a new version in the works. The number of minor revisions is much larger than three.