Any retrotechnologists out there want to try a Unixish which comes with source, is (almost) completely self-hosting, will happily run on an 8086 with no MMU, and which is so small that the bootable hard drive image is 6MB? (When I first saw that, I just assumed something was broken. It wasn't. All the tools, compilers and source code were in there.)
Yes, I have just built a Minix 2 distribution. I am running it on my new 386 laptop.