Almost two months ago, a tape containing UNIX v4 was found. It was sent off to the Computer History Museum where bitsavers.org would handle the further handling of the tape, and this process has now completed. You can download the contents of the tape from Archive.org – which is sadly down at the moment – while squoze.net has a readme with instructions on how to actually run the copy of UNIX v4 recovered from the tape.
This is just amazing!