The Free On-line Dictionary of Computing (30 December 2018):

Visual Interface

    (vi) /V-I/, /vi:/, *never* /siks/ A screen
   editor crufted together by Bill Joy for an early BSD
   release.  vi became the de facto standard Unix editor and a
   nearly undisputed hacker favourite outside of MIT until the
   rise of Emacs after about 1984.

   It tends to frustrate new users no end, as it will neither
   take commands while expecting input text nor vice versa, and
   the default setup provides no indication of which mode the
   editor is in (one correspondent accordingly reports that he
   has often heard the editor's name pronounced /vi:l/).
   Nevertheless it is still widely used (about half the
   respondents in a 1991 Usenet poll preferred it), and even
   some Emacs fans resort to it as a mail editor and for small
   editing jobs (mainly because it starts up faster than the
   bulkier versions of Emacs).

   See holy wars.

   (1995-10-03)