q[alex] writes "Caldera International has done a very good thing. They have released the "Ancient" Unices they inherited when they purchased SCO under a "BSD-style" license. The license is available here, instructions on finding the source are here. Caldera (and before that SCO) had required people to obtain a free (as in beer) but somewhat restrictive license in order to get these old sources. The new BSD-style licensing only applies to the 16-bit PDI-11 versions and some of the early 32-bit releases (excluding System III and System V), but it's still very cool."