"tenex", where does the word come from?

[Rob Warnock]

In article <623 at sdcc12.UUCP>, wa371 at sdcc12.UUCP (Bernd Riechelmann) writes:
> Recently learned about the tcsh shell, and the documentation says that 
> it is 'tenex' like.  I can not find tenex in the dictionary.
> Where does it come from and/or what does it mean?
> Thanks.

In the early 1970's, before DEC had ever built a paging version of the
PDP-10 processor, Bolt Beranek and Newman (BBN) built and sold a thing
called TENEX, for "PDP-10 EXtended", or some such. The TENEX hardware
consisted of an entire additional cabinet to your KA-10 processor (which
was already three boxes), plus around 150 wiring changes to the basic CPU
which connected the CPU to the new box, added some instructions, changed
the way some old instructions worked, etc. The main addition was a paging
unit, which allowed the possibility of demand paging of user programs. The
operating system which supported all of this was also called TENEX (or,
"the TENEX Operating System"), and a very interesting article on it was
published in CACM (I forget when). As I recall, the motivation was to
support some very large research projects being done by ARPAnet members,
for which BBN was (is?) a major contractor.

The command decoder was a major departure from previous DEC command-line
syntax, and had very advanced (for the day) features like command completion
and filename completion (you type a piece of the command or filename and
hit <ESC>, and it would try to finish the word or filename for you), and
various levels of help available at any time.

Also, TENEX was "process oriented" (like Unix), rather than "job oriented",
and had "fork()", essentially as Unix knows it (except that memory was by
default SHARED between parent and child, which made cooperating processes
like "cu" a lot easier to write -- but copy-on-write access was also
available). Programs were demand paged out of their ".EXE" files, etc.

Anyway, when DEC finally got around to adding paging to the PDP-10 line --
oops, by then the DECsystem-10 and DECsystem-20 line -- demand from users of
TENEX (mostly ARPAnet sites?) helped cause DEC to make the operating system
for the DECsystem-20 (TOPS-20) be more or less similar/equal to TENEX
[and that's ANOTHER long story!], hence the origin of another word you
may never see in a dictionary: "Twenex" (refers interchangably to TOPS-20
or TENEX).

It is primarily the user-visible command-decoder syntax of Twenex which is
being discussed when people are talking about "tcsh" or "ncsh", particularly
the command- and filename-completion features.


Rob Warnock
Systems Architecture Consultant

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