The Traditional Vi
Source Code for Modern Unix Systems

The vi editor is one of the most common text editors on Unix. It
was developed starting around 1976 by Bill Joy at UCB, who was
tired of the ed editor. But since he used ed as a code base, access
to the original sources has required a Unix Source Code License
for more than twenty years. In January 2002, Caldera was so kind
to remove usage restrictions to the Ancient Unix Code by a BSD-style
license (see the announcement at Slashdot) and thus vi is now
finally free.

Compared to most of its many clones, the original vi is a rather
small program (~120 KB code on i386) just with its extremely powerful
editing interface, but lacking fancy features like multiple undo,
multiple screens or syntax highlighting. In other words, it is a
typical Unix program that does exactly what it should and nothing
more. I intend to preserve this style in maintaining my port, except
for changes to achieve POSIX.2 standards compliance, features in
the SVr4 versions of vi, and, of course, bug fixes.