SCO Unix (or OpenDesktop or whatever they're calling it now) would be an example of a 'state of the art' x86 Unix before Linux matured. I, however, was always

SCO Unix (or OpenDesktop or whatever they're calling it now) would be an example of a 'state of the art' x86 Unix before Linux matured. I, however, was always more fond of Dell Unix SVR4 for x86; a more 'pure' Unix. Install images are 'around'. It's new enough to be familiar and comes with a bunch of extras (like a pile of ported GNU tools). Interactive or Microport SVR3 are a little more old-skewl, if that's where you're at. Xenix is very old school, and shows you what you can to with very limited x86 hardware (esp Xenix for the 8086 or 80286), and you'll find a lot of tools you might want don't compile for various reasons (like a K&R C compiler). Other folks shipped an x86 SVR3 or SVR4, but they generally added very little to the AT&T code base. If you go the emulated route (e.g. SIMH), I'd go with BSD 4.3 or Sun SunOS 3.5. That's where I started out with Unix so there's a lot of nostalgia there.