TOPS-20

From: Scott Ware <ware_at_xtal.pharm.nwu.edu>
Date: Tue Oct 20 09:57:28 1998

On Tue, 20 Oct 1998, Cameron Kaiser wrote:

(regarding tcsh and filename / command completion)

> It *does* do command completion, though.

Tcsh will do command completion for names of executables that are in the
current path. Additionally, typing the ambiguous beginning of a command
name followed by ^D will return a list of possible commands in the path
that start with the characters that you have entered.

Of course, it's important (at least in the context of this thread) to
remember where the "t" in tcsh comes from. From Richard M. Alderson III's
comments in the tcsh man page:

THE T IN TCSH

In 1964, DEC produced the PDP-6. The PDP-10 was a later re-implementation.
It was re-christened the DECsystem-10 in 1970 or so when DEC brought out
the second model, the KI10.

TENEX was created at Bolt, Beranek & Newman (a Cambridge, Mass. think
tank) in 1972 as an experiment in demand-paged virtual memory operating
systems. They built a new pager for the DEC PDP-10 and created the OS to
go with it. It was extremely successful in academia.

In 1975, DEC brought out a new model of the PDP-10, the KL10; they
intended to have only a version of TENEX, which they had licensed from
BBN, for the new box. They called their version TOPS-20 (their
capitalization is trademarked). A lot of TOPS-10 users (`The OPerating
System for PDP-10') objected; thus DEC found themselves supporting two
incompatible systems on the same hardware--but then there were 6 on the
PDP-11!

TENEX, and TOPS-20 to version 3, had command completion via a
user-code-level subroutine library called ULTCMD. With version 3, DEC
moved all that capability and more into the monitor (`kernel' for you Unix
types), accessed by the COMND% JSYS (`Jump to SYStem' instruction, the
supervisor call mechanism [are my IBM roots also showing?]).

The creator of tcsh was impressed by this feature and several others of
TENEX and TOPS-20, and created a version of csh which mimicked them.

--
Scott Ware          NUMS-MPBC Macromolecular Crystallography Resource 
303 East Chicago Avenue, Ward 8-264, Chicago, IL 60611  (312)503-0813
     PGP Public Key:  http://xtal.pharm.nwu.edu/~ware/public.txt
Received on Tue Oct 20 1998 - 09:57:28 BST

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