[ih] X.25

[Ian Lance Taylor]

"Lyndon Nerenberg (VE7TFX/VE6BBM) via Internet-history"
<internet-history at elists.isoc.org> writes:

> I have a vague memory that it might have been Doug Evans
> who wrote the 'x' driver.  He did the 'z' driver as well.
> I would ask him, but we lost track of each other over
> three decades ago.
>
> I remember looking at 'x' and asking myself "why?"  It
> didn't seem to add anything to the 'f' driver, and just
> seemed gratuitously incompatible.  But again, hindsight
> is 20/20, but my memory is closer to 20/80 :-(

Yes, Doug Evans implemented the 'z' UUCP protocol. It was a rewrite of
the zmodem file transfer protocol for use in UUCP. The details can be
seen in the long comment at the top of

    https://github.com/ianlancetaylor/uucp/blob/main/protz.c

I don't think Doug Evans wrote the 'x' UUCP protocol. It was introduced
in the System V UUCP implementation. I've never seen the source code for
it.

The 'f' protocol had a pretty bad checksum; maybe the 'x' protocol
improved on that? The details of the 'f' protocol can be seen at

    https://www.airs.com/ian/uucp-doc/uucp_7.html#SEC98

(I have Doug Evans's current e-mail if anybody wants it.)

Ian