[TUHS] forgotten versions

Brad Spencer brad at anduin.eldar.org
Wed Jun 22 12:55:38 AEST 2022

Larry McVoy <lm at mcvoy.com> writes:

> On Tue, Jun 21, 2022 at 05:56:02PM -0600, Jacob Moody wrote:
>> I recently stumbled across the existence of datakit
>> when going through the plan9foundation source archives.
>> Would be curious to hear more about its involvement
>> with plan9.
> Pretty sure datakit predated Plan 9, didn't Greg Chesson work on that?
> He was my mentor at SGI, my memory is datakit was sort of early on in
> his career and then he did XTP, which nobody knows about but I believe
> is still used by the military.
> Unless the early Bell Labs datakit and the Plan 9 datakit are different
> things.

When I was at AT&T in the early to mid '90s Datakit could manifest in a
couple of ways.  The simplest was as a tty ..  that is you had a serial
terminal and used a dial string with bangs in it to get somewhere.  This
method would have used some number of copper pairs into a RJ45 to DB25
adaptor connected to the terminal.  The terminals were usually 730s or
6xx (630s maybe).  They had some graphics ability, sort of, with some
windowing support.  The version of SVR3 we had running on the Vaxs had a
program in it that would be able to take advantage of the windowing
features of the 730 over a serial tty line (multiple windows, X-Windows
like sort of).  I have totally forgotten what that was called, however.
These terminals also had a mouse with them.  The second way that Datakit
would show itself was as a fiber pair tied directly to a computer
system.  There were Datakit fiber boards for nearly all of the platforms
that the group I was in used...  Vax (via a companion box), Tandem, Sun
Sparc, at the very least.  There was, usually, a third party kernel
driver required that would sometimes be a bit messy and/or have a
personality to it.  This set up sometimes provided a dkcu command and/or
a modified cu command and you could use a bang path dial string from the
system to get somewhere else using the Datakit network and act like a
tty.  Or, you could do native Datakit in your user land code.  This is
what the product I worked on did to talk to a Datakit network at the
RBOCs to get access to the switches in the telco network for monitoring
purposes.  Often in those cases, Datakit would be transported over a
X.25 network.  Later, as ethernet and TCP/UDP/IP became the thing, the
switches learned how to speak TCP/IP, although sometimes indirectly
though a translator box in front of the switch.  A number of the telco
switches we talked to spoke a dialect of X.25 called BX.25 (Bell X.25 or
some such) and the translator boxes would exist on the switch side and
our side and basically tunnel BX.25 over TCP/IP.  This was a bit
different then using the Datakit network to get to the switch, but I
seem to remember that some RBOCs did something where BX.25 was sent via
Datakit which in the wider area network was transported over X.25 to the
monitoring system.

There were things called Datakit switches that was a cabinet a few feet
tall and a couple of feet wide.  It housed a bunch of boards of your
choosing depending on how you wanted to use Datakit.  Our group had
their own switch at the site I was at run by the persons dealing with
our development lab.  There was also a number of Datakit switches for
the site itself run by the general IT organization.  I seem to remember
those switches having hot pluggable boards with an embedded 3B system
inside (although I may be misremembering that a bit).

Brad Spencer - brad at anduin.eldar.org - KC8VKS - http://anduin.eldar.org

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