TECO /tee'koh/ N.,v. Obs. 1. [originally An Acronym For `[paper] Tape Editor And COrrector'

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TECO /tee'koh/ n.,v. obs.

1. [originally an acronym for
`[paper] Tape Editor and COrrector'; later, `Text Editor and
COrrector'] n. A text editor developed at MIT and modified by just
about everybody. With all the dialects included, TECO may have
been the most prolific editor in use before EMACS, to which it
was directly ancestral. Noted for its powerful
programming-language-like features and its unspeakably hairy
syntax. It is literally the case that every string of characters
is a valid TECO program (though probably not a useful one); one
common game used to be mentally working out what the TECO commands
corresponding to human names did. 2. vt. Originally, to edit using
the TECO editor in one of its infinite variations (see below).
3. vt.,obs. To edit even when TECO is not the editor being
used! This usage is rare and now primarily historical.

As an example of TECO's obscurity, here is a TECO program that
takes a list of names such as:

Loser, J. Random
Quux, The Great
Dick, Moby

sorts them alphabetically according to surname, and then puts the
surname last, removing the comma, to produce the following:

Moby Dick
J. Random Loser
The Great Quux

The program is

[1 J^P$L$$
J <.-Z; .,(S,$ -D .)FX1 @F^B $K :L I $ G1 L>$$

(where ^B means `Control-B' (ASCII 0000010) and $ is actually
an alt or escape (ASCII 0011011) character).

In fact, this very program was used to produce the second, sorted
list from the first list. The first hack at it had a bug: GLS
(the author) had accidentally omitted the @ in front
of F^B, which as anyone can see is clearly the Wrong Thing. It
worked fine the second time. There is no space to describe all the
features of TECO, but it may be of interest that ^P means
`sort' and J<.-Z; ... L> is an idiomatic series of commands
for `do once for every line'.

In mid-1991, TECO is pretty much one with the dust of history,
having been replaced in the affections of hackerdom by EMACS.
Descendants of an early (and somewhat lobotomized) version adopted
by DEC can still be found lurking on VMS and a couple of crufty
PDP-11 operating systems, however, and ports of the more advanced
MIT versions remain the focus of some antiquarian interest. See
also retrocomputing, write-only language.