NetBSD was my favourite playing around OS from the late 1990s to about 2010. Worked on any old crap I had lying around which was mostly thoroughly obsolete SPARC and x86 kit. Did the job. Never went wrong. Good documentation built in. Netbooted on anything.
No idea where it is now but this post has inspired me to have a look.
No idea where it is now but this post has inspired me to have a look.