On Sun, May 18, 2008 at 03:40:05PM +0200, Magnus Danielson wrote: Most of it is here: http://www.tuhs.org/Archive/PDP-11/Distributions/research/ which includes source for 5th, 6th and 7th Editions, and a kernel written just before 4th Edition. We don't have 2nd, 3rd, or 4th Edition source, but the 3rd and 4th Edition manuals are in there. The source to the 1st Edition UNIX kernel has recently been found in a paper document, available at http://www.tuhs.org/Archive/PDP-11/Distributions/research/1972_stuff/Prelim…. Cheers, Warren