[TUHS] Is there a good, even definitive, list of reimplementations of the Unix kernel? What would good cut-off criteria be?

[Arnold Robbins via TUHS]

"Jeremy C. Reed via TUHS" <tuhs at tuhs.org> wrote:

> On Sat, 25 Apr 2026, Arnold Robbins via TUHS wrote:
>
> > Clem Cole via TUHS <tuhs at tuhs.org> wrote:
> >
> >> [Keith wrote Nvi himself, which was often
> >> said to be the tool that would never be replaced].
> >
> > For the record, he started with a vi clone named Elvis, and then
> > turned it into a "bug for bug compatible" clone of vi.
>
> Bostic contacted Steve Kirkendall for permission to use his ex/vi clone's
> source code while he was writing nvi ---
> probably to drive home the fact that it wasn't derived from
> the original Bell Lab's ed (via vi).
> ``As far as I can tell, he didn't copy any of elvis' source
> code into nvi, however elvis' source code does clearly document
> the quirks of each command in an organized way and I'm sure he
> found that useful,'' Kirkendall later said.\cite{kirkendall1}
> Bostic's nvi documentation stated: ``Without his work, this work
> would have been far more difficult.''
>
> (per my personal correspondence in Nov. 2010)

I would have to go back to my old emails with Kieth from when I worked on
various editions of O'Reilly's "Learning the vi and Vim Editors",
but ISTR that he started with Elvis 1.0 and hacked on it until
it was "bug for bug compatible", and that he did NOT start from scratch.

Or, I could just ask him again.

Arnold