System N history correction

[Geoff Collyer]

Guy Harris, in denouncing ulimit (in net.unix), recently wrote 	

	The only explanation
	I can think of is homesickness for PWB/UNIX (S3 and S5 are derived
	from a mix of V7, PWB/UNIX, and various other internal UNIX systems),
	where the V6 file system was hacked to only support singly-indirect
	blocks and as such didn't support files bigger than 1 Mbyte in any
	form.

It's time to set this long-standing misconception straight:
System N are *not* derived from V7; they are derived from a late V6.
This may seem a small point, but AT&T sells System N in part by claiming
that they are a merger of V7, PWB and other internal (mainly USG) UNIX brand
operating systems, implying that System N contains everything of value
from V7.  To quote from an AT&T (nee Bell) System III advertisement:
``UNIX System III combines the features of the UNIX System, Seventh Edition
(V7), and the PWB/UNIX System with several major enhancements. ...
UNIX System III = V7 + PWB + EXTRAS''.

Here is a partial list of software found in V7 which is absent in System III
and probably System V, though I haven't kept track since it became apparent
that I don't want to run System N.

	at(1): run commands at a later time, due to broken chown(2)
	enroll(1), xsend, xget - secret mail
	grep(1) -y: case-insensitive grep
	(ld(1): System N ld doesn't understand random libraries)
	learn(1): CAI about UNIX brand operating systems
	look(1): binary search on a sorted file
	lookbib(1): search bibliographic data base, uses dbm(3)
	(mv(1): System N mv can't move directories up or down the tree)
	pubindex(1): generate bibliographic index, uses dbm(3)
	quot(1m): summarise disk use by user
	ranlib(1): convert object archives to random libraries for ld
	refer(1): bibliographic troff pre-processor, uses dbm(3)
	sort(1) -T: change temporary directory (undocumented, may be in the code)
	struct(1): convert Fortran to Ratfor
	mpx(2): file multiplexor, replaced only in V8 by stream I/O
	pkon(2), pkoff: packet protocol
	dbm(3x): a simple but effective data base manager
	mp(3x): multi-precision integer arithmetic
	(tty(4): replaced by USG's arguably better but utterly incompatible one)
	ms(7): the -ms macros (due to obvious rivalry with -mm)

Clearly the USG didn't take all this software out of System III; it was never
a part of System III because System III was based on a pre-V7 system.
Some of the above may have been deliberately omitted (e.g. at, ms and pkon),
but not all of this (why would USG ship an inferior mv and grep?).

Note to OEMs:  your System N licence covers V7.  You can correct the omissions
of the USG and add most of this software into your distributed System N
(admittedly putting mpx back in and getting it debugged may take some effort).
Actually the USG should correct these omissions in future System N releases.
-- 
System V: none genuine without the mark of the USG sledgehammer of approval.