UNIX Family Tree? - (nf)

[Guy Harris]

Before anyone contemplating moving their favorite screen editor to System
III or System V, let me reassure them that the S3/S5 tty driver does provide
a mode with equivalent functionality to CBREAK mode; the only difference is
that to get at this mode you turn off a bit (specifically, the ICANON bit
in the "lflag" word of the "termio" structure).  Furthermore, TIOCSETN
set the terminal modes without either waiting for output to drain or
flushing input, which is exactly what TCSETA does on the S3/S5 terminal
driver; TIOCSETP is equivalent to TCSETAF (wait for output to drain, then
flush unread characters).

Also, I'd draw the graph with a line from a post-V6, pre-V7 "center 127"
release (I believe that's what the "127" and "135" refer to on the left
hand edge of Mark's graph; not ever having been employed by Bell Labs I
don't know exactly what a "center" is, but they use the term a lot.  AT&T,
like IBM, likes to invent lots of new words for common objects.) to
reflect the cross-migration of V7 features into UNIX/TS 1.0 as Mark
mentions (the internals of the S3 kernel resemble the internals of the V7
kernel fairly closely, far more closely than they resemble the V6 - or even
the "V6 + 50 changes" kernel that the PWB/UNIX 1.0 kernel resembles).

System III was, from what I can tell, a combination of the standard USG UNIX
release 3.0.1 plus a modified version of the PDP-11 3.0.1 done to support the
PDP-11/44 (which seemed to be unloved and unwanted within Bell, by and large).
(At least the "release" field of the structure the "uname" system call fills
in in System III fills it in as "3.0.1".)  There was a good deal of time
between the release of 3.0.1 within AT&T and its public release as System III,
but this is not reflected in any major changes.  System V was released about
3 months after it was internally released as UNIX 5.0.

	Guy Harris
	{seismo,ihnp4,allegra}!rlgvax!guy