[TUHS] Early supported UNIX manual

[Noel Chiappa]

    > From: Phil Budne

    > The cover page has:
    > ...
    > Upper right corner:
    > PA-1C300-01
    > Section 1
    > Issue 1, January 1976
    > AT&TCo SPCS

I have a very similar manual; I got it a long time ago, and no longer recall
how I came by it. Minor difference: mine is for PD-1C301-01, and at the
bottom of the page, it says "ISSUE 1 1/30/76", followed by a prominent trade
secret notice.

TUHS has a copy of this version, here:

  https://www.tuhs.org/Archive/Distributions/USDL/unix_program_description_jan_1976.pdf

The README file in that directory:

  https://www.tuhs.org/Archive/Distributions/USDL/README

speculates that "this is PWB/1.0" but admits "this has not yet been
confirmed". It's not PWB1, it's stock V6. If you look at the writeup of
sys1$exec(), on pg. 39 of the PDF, you'll see it describing how arguments are
copied into a disk buffer; that right there is the tip-off. In PWB1 (whose
source we do have):

  https://minnie.tuhs.org/cgi-bin/utree.pl?file=PWB1/sys/sys/os/sys1.c

you'll see that PWB1 accumulates the arguments in a chunk of swap space.
V6 _does_ use a disk buffer for this:

  https://minnie.tuhs.org/cgi-bin/utree.pl?file=V6/usr/sys/ken/sys1.c

So this is for V6.

	Noel