My own experience only goes back to 6th Edition. As I recall it came on a standard 2400' 1/2" 9 track tape.  The 6th Edition "Setting Up" document describes it as: "3. The UNIX software on magtape or disk pack. "If you are set up to do it, it might be a good idea immediately to make a copy of the disk or tape to guard against disaster.  The tape contains 12100 512-byte blocks followed by a single file mark; only the first 4000 512-byte blocks on the disk are significant. " The system as distributed corresponds to three fairly full RK packs.  The first contains the binary version of all programs, and the source for the operating system itself; the second contains all remaining source programs; the third contains manuals intended to be printed using the formatting programs roff or nroff.  The 'binary' disk is enough to run the system, but you will almost certainly want to modify some source programs." The document then goes on to describe how to boot from the tape into a tiny copy program that allows you to copy from the tape to disk packs. My recollection of the 4BSDs was that they also came on standard 1/2 inch tapes, though the way the data was organized and the installation process were different.  If I look hard enough, I think I've got a copy of the 4.3BSD tapes in the basement. BLS On Friday, July 30, 2021, 8:16:52 PM EDT, Acker, Amelia <aacker@ischool.utexas.edu> wrote: Dear colleagues, I am researching early uses of magnetic tape for sharing and storing information with minicomputers, especially DEC machines. I am trying to gather stories where magnetic tapes are used to share software and data. I’ve been learning about how Ken Thompson developed UNIX using the PDP-7 and later installing version 6 on a PDP-11 at Berkeley. According to Salus’ Quarter Century of UNIX, around 1978, Bill Joy begins offering a BSD distribution tapes described as '800 bpi magnetic tape, 1200 foot reel at $50'. Other accounts also mention "the 50 fixes" diff tape and Bell’s lawyers demanding licensees destroy the diff tape. I’m having trouble finding more information about the specifications of these tape formats.  Does anyone know what format(s) these early UNIX distribution tapes or would be? I would like to confirm that they were magnetic tape (and not paper?), and if any were DECtape or another kind of data tape format. Any ideas? Or good place to look for confirmation? I would be grateful for any sources you can point me too.  Thanks,  Amelia  Amelia Acker, Assistant Professor Director, Critical Data Studies Lab The University of Texas at Austin ​| School of Information  http://www.ameliaacker.com/ _______________________________________________ This email is relayed from members at sigcis.org, the email discussion list of SHOT SIGCIS. Opinions expressed here are those of the member posting and are not reviewed, edited, or endorsed by SIGCIS. The list archives are at http://lists.sigcis.org/pipermail/members-sigcis.org/ and you can change your subscription options at http://lists.sigcis.org/listinfo.cgi/members-sigcis.org