[TUHS] UNIX v4 Source Code Commentary - complete book now available

[segaloco via TUHS]

On Monday, January 12th, 2026 at 15:51, Thalia Archibald via TUHS <tuhs at tuhs.org> wrote:

> On Jan 12, 2026, at 16:20, Phil Budne wrote:
> 
> > General question: Is "v4" really the right thing to call the tape?
> 
> 
> 
> The manual editions are a messy way to refer to UNIX snapshots.
> UNIX was versioned by the manual releases, but the system was distributed as a
> copy of the current system on the Research machine, whenever the tape was cut.
> Different licensees received different snapshots, but the same manual.
> 
> Since we only have a few snapshots now, it’s tempting to call them by the manual
> in use at the time, but it’s rather inaccurate. It’s much better to call them by
> some unique identifier; Utah V4 in this case or Dennis_v5, Henry_Spencer_v7,
> Nijmegen_v7, etc., as in the TUHS Archive. Or alternatively, to call it a UNIX
> V4 snapshot from 12 June 1974.
> 
> As you say, the V5 manual is dated June 1974. The files on the Utah V4 tape are
> dated 12 June 1974 and documented to have been sent after May 1974, but with a
> V4 manual. So we’re looking at near-V5 code just days or weeks before the V5
> manual was released. However, I continue to call it “V4”, as that is evidently
> what this particular tape was thought of as, since that was the manual version
> that accompanied it.
> 
> Thalia

The new USG docs refer to USGs providence as coming from a "frozen" machine.  This does make me wonder why they didn't just start shipping USG UNIX instead since it was separated into "stable" releases.

Granted either way they couldn't "support" it, but you'd figure it'd be easier for everyone to just keep sending out cuts of USG UNIX.  Would it being AT&Ts internal supported UNIX make it too close to shipping a supported product and shipping random cuts from Research instead kept them out of scrutiny?  They eventually warmed up to shipping PWB, so this remains a point of curiosity to me.

- Matt G.