A while back - A Unix distribution with installation media that could boot on several platforms?

Quite a while I saw a distribution of a *nix operating system where the installation media (CD? DVD?) contained binaries for several hardware platforms, and could boot and install directly on _several_ of these. My best bet is that this was either OpenBSD or NetBSD but I cannot remember when or where I saw this. I would like to have a closer look at the boot code making this possible. My question is, what was it I saw back then?