[TUHS] Re: v6 Unix Documents

[Dan Plassche <boomer3200@gmail.com>]

Hey Branden,

Apologies for the duplicate message.  I had a mailer issue this 
evening where the message did not reach TUHS.

On Fri, 18 Oct 2024, G. Branden Robinson wrote:

> I do observe that this web page credits the publisher of the document as
> "Western Digital Corporation".  Shouldn't that be "Western Electric
> Company"?

Yeah, Western Electric issued licenses and official printed 
documentation externally for Research Unix in the 1970s.

I completely looked past that typo in the catalog amidst the 
thrill of obtaining the document!

I've let an archivist at the CHM know of the correction.  I found 
in the course of researching that most other catalogs list the 
documentation as a single serial item from 1971 onwards with 
Thompson and/or Ritchie as authors, so finding any specific item 
can be difficult.

> > The [nt]roff user manual,
> 
> Noteworthy but frustrating here is that at this point, the forerunner of
> CSTR #54 was still titled simply "NROFF Users' Manual" (PDF pp. 173ff.).
> References to troff are present, but the typesetting program is not
> fully documented.  Frustrating!

We can trace the evolution using nroff as a starting point.

Nroff appeared in v2 Unix in 1972 and the preceeding roff 
formatter did not change afterwards.

The v3 manpage for nroff includes the first reference to the 
"NROFF User's Manual" (MM-73-1271-2) and a summary of all 
commands.  The summary is available with each dated and revised 
manpage for nroff through v5.

The v6 manual from 1975 is identified as the second edition of 
the "NROFF User's Manual" as revised in Sept. 1974.

If the documentation and changes to the extant source code from 
v4 to v6 are in alignment, we should have a baseline history with 
a clear indication of differences across versions.  I will send a 
summary with further details to the groff mailing list in the 
coming weeks.

The development of troff before the rewrite to C between v6 and 
v7 is a lot less clear.  Troff appears in v4 with a mention of a 
preliminary user's manual, but I suspect the manual is a summary 
of unique troff features that were not documented elsewhere until 
v7.  The manpages only cover troff invocation.

> Also we have here the (unnumbered) first edition of the eqn User's
> Guide (PDF pp. 269ff.).
... 
> The biggest nroff change that leaps out at me right now is that in V6
> _special character escape sequences did not yet exist_.  Given that the
> C/A/T typesetter had already been in use for years by 1975 (with eqn
> giving it strenuous exercise from early on), I find this fascinating.

Perhaps special characters did exist for troff but were not 
documented in this v6 manual.  It's not clear without seeing an 
earlier troff manual, but I'm staring to think that the v6 manual 
may be a continuation of the nroff manual alone.  In that case, 
general users would have fallen back on overstrikes for most 
special characters.  The greek characters in eqn and the various 
copyright symbols on earlier programmer's manuals seem to support 
the assumption that special characters were in use with troff.  
The documents and programmer's manuals were all printed with 
troff from v4 onwards.


> Evidence of the close relationship with the Teletype Model 37 is
> present, with the `\x` and `\y` escape sequences mapping to "ASCII
> Shift-out" and "ASCII Shift-in", respectively (PDF p. 177).

I was surprised to see the ribbon shift-in/out feature existed 
and then got removed, since it would seem that the command could 
have been reused for changing the typing element on Selectric 
consoles and daisywheel printers that were fairly widespread.

> .xh		Extra half-line mode on.

Half line motions are surprisingly common on older documents and 
probably a major reason for using troff output that's setup to 
look like an nroff device.

> I see that the `ad` request did not accept arguments "l" or "b", just
> "c" and "n".  Since "b" and "l" were redundant, my imaginations conjures
> office arguments over the meaning of the word "adjustment".  With the
> design in such flux, too bad I wasn't there to lobby for the separation
> of "alignment" and "adjustment".  ;-)
> 
> No worries, I'll be there soon!  <https://savannah.gnu.org/bugs/?65954>
> (Fifty years late but moving fast, as Douglas Adams might have said.)

The v6 design certainly seems clearer and in support of your 
cleanup.

> > tmg compiler-compiler, and m6 macro processor memos were previously
> > missing from the distributions in TUHS and later efforts to re-create
> > the documentation.
> 
> I'm intensely interested in both of these from a personal perspective.
> 
> I observe that the TMG and  m6 documents appear may have been prepared
> by vintage 1972 and 1971 nroff, making them worthwhile exhibits on that
> basis alone (PDF pp. 211ff., 239ff., respectively).  I wonder why they
> were never typeset.  Would the document sources have required too much
> "porting" to troff?

I was very interested to find the papers as well.  The output 
seems to be roff formatted like the v1 manual on TUHS and frozen 
from around 1972.

> In summary, there is a boatload of information here that is useful to me
> in understanding Why Things Look The Way They Do.
> 
> Please keep the groff list apprised of further findings.  Fascinating
> stuff.
> 
> Good work!
> 
> Regards,
> Branden

Thank you for your feedback and the credit in re-creating the 
Unix porting paper, which I have been following with interest.

I really appreciate all of the extra work you put in as 
maintainer to understand the history of roff design and output in 
order to better document, validate, and develop groff.


Sincerely,

Dan