On: Xv6, a simple Unix-like teaching operating system

[rst]

You might want to look for 2.9BSD, a PDP-11 Unix variant which was more or less v7 with the TCP stack from 4.xBSD grafted in. Patching this into an x86 port would still be a bit of a project, but it's probably easier than starting with 4.xBSD directly, or starting from scratch.

[ChuckMcM → rst]

This is great advice. 2.9BSD was the first UNIX I got to play with in depth it has all the pieces you need and it can do networking.

[stplsd → rst]

What about 386BSD?