This past Halloween, Alan Cox announced Fuzix OS, a project for building a UNIX-like operating system for 8 bit computers, based on UZI sources. This OS targets a number of physical machines, both old and homebrew computers, and some emulators too.
The easiest and more approachable way for trying Fuzix OS is running it on
cpmsim, which comes bundled inside the Z80pack package. If want to give it a try the easy way, just continue reading.