[hovav]

Indeed, the History of Documented Unix Facilities [https://github.com/dspinellis/unix-history-man] says a vi(1) man page first appeared in 2BSD, and vi is implemented (as part of ex, with a 1979 copyright) in 2BSD src/ex, with the main routines at src/ex/ex_vmain.c: https://github.com/dspinellis/unix-history-repo/blob/BSD-2-S...