[COFF] [TUHS] Re: project athena (was Re: Setting up an X Development Environment for Mac OS)

[Warner Losh]

On Fri, Feb 10, 2023 at 8:33 AM Dan Cross <crossd at gmail.com> wrote:

> On Fri, Feb 10, 2023 at 10:26 AM Warner Losh <imp at bsdimp.com> wrote:
> > On Fri, Feb 10, 2023, 3:12 AM Lars Brinkhoff <lars at nocrew.org> wrote:
> >> Jonathan Gray wrote:
> >> >> Any chance this DOS supdup software is still around?
> >> >
> >> > https://web.mit.edu/Saltzer/www/publications/pcip-1985.pdf
> >> > http://www.bitsavers.org/bits/MIT/pc-ip/
> >>
> >> Great, thanks!
> >>
> >> It's a bit sad to read in supdup.mss "Unfortunately, very few machines
> >> have TCP/Supdup servers.  The only servers known to us are on Mit-MC and
> >> Su-AI, and 4.2 Unix machines running a server we distribute."  At this
> >> point, three old ITS machines had recently fallen over, one after the
> >> other, and MC was the only one left standing.  But not long after, four
> >> new ones would appear.  One of which is still up and running!
> >
> > I wonder if this was the same supdup that the early BSDs used to
> distribute their source in the 90s ..
>
> I believe they are entirely different.
>
> If I recall correctly (and it's been a while...) csup, CVSup, et al
> were based on `sup`, which was a file distribution tool somewhat like
> `rdist`, which came from CMU. csup/cvsup was optimized for moving
> source code deltas (a la CVS repositories) around. I recall a
> graphical client written in Modula-3?
>

cvsup was written by John Polstra in Modula-3. IT had an optional GUI
client.
It was notable at the time for using the radical new concept of threading to
stream the exchange elements of the protocol, speeding it up radically over
the old sup protocol, which was entirely synchronous. In addition, it knew
about the structure of RCS files, and exchanged only delta information so
could make a number of interesting optimizations in transmission of data
and delta data (since RCS had rules for the version number's forms, etc). It
was from the very early days of the FreeBSD project (somewhere between
FreeBSD 2.0 and 2.1) because the sup protocol was killing the wallnut creek
CD-ROM servers with its load (a primary motivation for teaching it about the
structure of RCS files).

csup was a later rewrite in 'c' as the module-3 compiler fell into
disrepair. It
was written by Maxime Henrion and is protocol compatible with the cvsup
programs. It lacked a gui, but was way more portable and didn't require that
a new architecture in FreeBSD first port the Module-3 compiler to it so
source
updates were possible (only slight exaggeration). cvsup was ported between
three or four different Modula-3 compilers as support for the language was
fading away....

Both became obsolete when the FreeBSD project moved to svn. It offered
not-quite-as-good, but good-enough delta updates, so cvsup and csup
became relegated to the dustbin of history.


> The SUPDUP protocol used by ITS hosts was a "Display Protocol" based
> on TELNET: https://www.rfc-editor.org/rfc/rfc734
>
> I think the similarity in naming was just a coincidence.
>

Now that you say that, I recall that as well...

Warner
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