[Eug-lug] Computer time

[Bob Miller]

Jim K wrote:

>      I just did a man ex on a mandrake 10 community system and it 
> displayed the vim man page. Is ex just an alias for vim?

Okay, guys.  Time for text editor history class.

Emacs.  I already alluded to the fact that it was from MIT.  In 1960,
MIT got one of the first PDP-1 computers made by the startup company,
Digital Equipment Corporation (DEC).  A group of nerds took it over
and started developing software for it.  One nerd, Alan Kotok, started
writing TECo, for Text Editor and Corrector.  (Alan later went to work
at DEC and was the chief architect of the PDP-10.)  TECo was a line
oriented editor: you type a command, the computer responds with
something.  That's because the terminal was a Teletype machine, which
prints on paper.  TECo was probably the world's first text editor, as
the idea of interactively using a computer was radical in the early
1960s.

Anyway, TECo grew and evolved, and was ported to other platforms.  In
the early 1970s, DEC gave the MIT Lab for Computer Science four PDP-10
computers.  MIT developed its own operating system for them, ITS.
TECo was ported to ITS.  By this time, TECo had grown into a fairly
complex and ugly language.  I used to be very fluent in it, but since
I stopped using it in the early 1980s, I can't remember squat about
it.  Richard M. Stallman (RMS, yes, that RMS, who later founded the
Free Software Foundation and the GNU project) took up maintenance of
TECo on the PDP-10s.  He also developed a set of personal TECo editing
shortcuts, or macros, which got popular at the lab.  He called them
EMACS.  It probably was short for "editing macros", though officially,
EMACS doesn't stand for anything.

That's why when RMS started the GNU project, the first program he
wrote for it was GNU emacs, a port of emacs to the C language and Unix
platform.

I'll briefly mention some other emacses.

An engineer at DEC reimplemented TECo for the PDP-11, and gave it a
small fraction of the original's feature set.  This was the most
popular TECo, because it ran on thousands of PDP-11s and VAXes, and is
the version I learned.

Somebody did an emacs clone for Unix at Bell Labs around 1980.  It was
written in C and small enough (barely) to run on a PDP-11.  Since it
wasn't extensible in any way (couldn't even rebind keys) most people
thought it didn't count as an emacs.

James Gosling (who later created the Java language), while at CMU,
wrote an emacs implementation for Unix, usually called Gosling emacs
or gosmacs.  Later, he made it into a commercial product, Unipress
Emacs.  I tried to find a copy of gosmacs screen.c which starts with
the very best comment I've ever seen in a source file, but it seems to
be lost to antiquity.  Gosling also published a paper in the CACM
about the algorithms in that file.

There was a fork of gnu emacs called Lucid Emacs and later xemacs.
I personally use the unforked version, sometimes called FSF emacs
to disambiguate.  They used to be horribly incompatible, but
they've been evolving into greater compatibility lately.

That's the Emacs family.

Meanwhile, at Bell Labs, Unix was being born.  In the mid 1970s, the
way to interact with a Unix system was through a Teletype.
Accordingly, ed was written.  ed is a fairly powerful and regular
editor, given the interface.  Not as powerful as TECo, but a lot
easier to learn.  Bell Labs started giving away Unix licenses to
universities in the mid 1970s.  (One of the engineers of that era said
the reason ed never prints a prompt is that the machines were so slow,
they'd always be several commands behind you and when you finally
issued a print command (p or l) to see what you'd done you'd wait and
wait for it to catch up.)  I remember using mini-Unix on a PDP-11/40,
and can vouch that a context switch took about three seconds on that
box.  If another process ran during your editing session, the editor
would be swapped out for a minimum of six seconds.

Sometime in the late 1970s, an undergraduate at Berkeley, Bill Joy
(who later became lead programmer in the DARPA-funded project to make
Unix a suitable computer science research platform, Berkeley Unix (aka
Berkeley Software Distribution, BSD), then later founded Sun
Microsystems), started adding features to ed.  He called his "extended
ed" ex.  Eventually he added "visual mode", or "vi", to display text
on a CRT terminal while it's being edited.  So ex and vi were the same
editor, and both derived from ed.

Since I'm primarily an emacs user, I don't know the history of various
vi versions and clones.  The dominant vi variant today seems to be
vim, for "vi improved".  Maybe somebody else would like to fill that
part in?

Steven Levy's book, Hackers, is the best published history of this
era, especially the MIT bit.  The O'Reilly book, Open Sources, has a
good synopsis history of BSD written by Mike Karels.

* ITS, the Incompatible Timesharing System, had the weirdest file
  naming convention I've ever seen.  The machine had a 36 bit word, a
  character set called 6-Bit was devised to fit six characters per
  word.  If I remember, it mapped ASCII characters 32 (space) through
  95 (backslash), so it had the uppercase letters, the digits, and
  most of the punctuation, including space (which had code \00,
  suitable for NULL-padding short names.  A filename was two
  6-character words separated by a space.  A common convention was to
  use the second word as a version number.  So the TECo Manual,
  version 51, would have been named "TECORD     51".

-- 
Bob Miller                              K<bob>
kbobsoft software consulting
http://kbobsoft.com                     kbob at jogger-egg.com