I would also add that 4.1 also ties into research UNIX v8. On the VAX (via SIMH) its bootstrapped from a 4.1 system. David du Colombier's guide uses the 4.1 image I found and modified with some 4.2 to get running on SIMH http://9legacy.org/9legacy/doc/simh/v8 Not having 4.1 would have made this far more involved. 4.2 is no doubt a major Internet milestone on the way to SunOS & 4.3 while 4.0/4.1 are important in a pre-tcpip focused world. Naturally I'm biased into thinking they are all important, but I know resources /time are limited. On Tue, Mar 12, 2019 at 2:22 PM +0800, "Nigel Williams" wrote: On Tue, Mar 12, 2019 at 4:39 AM Larry McVoy wrote: > Other than for history's sake, I don't see the value of 4.1 On the history side, I found having 4.1 BSD important when we were recovering the build of a programming language on this version. As we had the binary we wanted to be sure that when we re-compiled we could confirm that the result was identical to the original. This was to ensure that we had recovered the build environment as it was originally. For that reason, I would urge preservationists to always try to recover as many incremental versions as possible.