[TUHS] Joe Condon [ long, slightly off-topic post ]

Rob Pike robpike at gmail.com
Sun Apr 21 15:52:13 AEST 2019

The Unix on 516s sounds wrong to me. Perhaps it conflates GCOS remote job
entry and Unix?

But the PBX story is correct. To demonstrate how message passing was a good
model for a switching system, in particular to make a point to the
switching systems division of Bell Labs/AT&T, Ken and Joe bought a
commercial PBX and swapped out its processor for a PDP-11/23 (I think), and
programmed it up. It was just before I arrived there but I was given the
impression it had the desired strategic influence on Indian Hill.

The feature we all loved it for was that instead of ringing the phone in
the Unix room when you got a call, it would announce your name through the
voice synthesizer: "Phone call for Ken." "Phone call for Joe". One rapidly
stopped even hearing the announcement if it didn't end with your name.


On Sun, Apr 21, 2019 at 8:58 AM Jon Steinhart <jon at fourwinds.com> wrote:

> So as part of my attempt to remember the names of the folks with who I
> worked
> I just read Joe's wikipedia page which doesn't seem accurate to me.  If
> this
> is too off topic let me know.
> The page says that Joe "was exposed to UNIX on the Honeywell 516 machines
> in
> the early 1970s."  This seems wrong to me.  We did have a 516, but it ran
> an
> experimental virtual memory system called 516-TSS.  I lived on this system
> and still have some of the octal instruction opcodes burned into my
> brain-ROM.
> I seem to recall that the department got a PDP-11/40 that ran UNIX version
> 3 in
> maybe the summer of 1972 which I used for writing up the documentation for
> my
> project.
> The page also says that "Condon and Ken Thompson promoted the use of the C
> programming language for AT&T’s switching system control programs.  Condon
> acquired a small AT&T PBX (telephone switch) that handled about 50 phones;
> he made the necessary hardware changes and Thompson wrote the necessary
> software
> programs. The PBX code rewrite in C was a success and hastened the
> adoption of
> C for all switching system software within AT&T."  This also doesn't match
> my
> recollection.
> One of the big projects in the department was what I think was called SS1
> for
> Slave Switch 1, which was an all-digital telephone exchange.  It replaced
> some
> other monstrosity whose details I can't recall except that Joe and Dave
> Weller
> signed the appropriate paperwork allowing me to take a good portion of it
> home
> when it was decommissioned giving me a huge stock of Augat wirewrap boards
> and
> 7400-series parts.  The SS1 was originally going to use LSI-11s but the
> stupid
> way in which DEC implemented the DRAM refresh made that impossible.  I
> think
> that the final thing used a couple of PDP-10s.  As part of being
> all-digital
> it used the digital filter work by Jim Kaiser and Hal Alles.  I do remember
> going into Carl Christensen's office to ask him a question and found him
> staring
> at a huge C listing; it turns out that a bug in the code had caused SS1 to
> send
> KP pulses without their corresponding ST pulses with the result that every
> single
> keypulse sender in the Berkeley Heights telephone exchange was taken off
> line and
> needed to be manually reset to restore long distance service.  They were
> not happy.
> Anyway, unless there was something that happened later after I was gone,
> I'm
> thinking that the wikipedia page is incorrect and that this PBX was built,
> not
> acquired.  It was, as far as I know, the first use of C to control
> machinery.
> It's actually because of this machine that I'm trying to track down the
> name
> of some folks from down at the end of the hall.  I have strong memories of
> the
> Bell System exhibit at the '64 World's Fair, especially the booth where one
> could go and talk and they had bar graphs on a monitor showing the spectrum
> of your speech and could mess with it.  Many years later, while waiting for
> some deck of cards to finish loading, I poked my head into the lab down the
> hall to see what they were doing in there, and noticed polaroid photos of
> that
> exhibit featuring the guys in the lab.  Once they stopped telling stories
> from
> the World's Fair, they taught me a lesson about systems engineering that
> opened
> my eyes.  They were developing a circuit that replaced the pound of iron
> hybrid
> transformers that were on every telephone line with a small toroid and an
> op-amp.
> Their circuit would sense when the iron was getting close to saturation
> and run
> current through an additional winding to keep it in the linear region.
> While
> that circuit cost a lot more than a hybrid transformer, it paid for itself
> by
> reducing the amount of concrete needed to build telephone exchanges.
> Would love to know who these guys were which is why an org chart would
> help.
> And maybe someone out there like Ken can help me out with the accurate
> history.
> Jon
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