[TUHS] Known Specimens of Pre-5ESS UNIX Telephone Switching Software?

Sebastien F4GRX f4grx at f4grx.net
Wed Sep 27 02:07:34 AEST 2023


You beat me to it! I was about to reply that the Connections Museum of 
Seattle would have more info about this, or know people who do.

This video of their channel shows a 3ESS software boot : 


Le 26/09/2023 à 04:20, Kevin Bowling a écrit :
> On Mon, Sep 25, 2023 at 6:25 PM segaloco via TUHS <tuhs at tuhs.org> wrote:
>     Hello, my studies lately bring me to the question: Are there any
>     extant examples of telephone switching software, built on UNIX,
>     from the various parts of the Bell System prior to the
>     introduction of the 5ESS and 3B20D?  My focus veers earlier as
>     some 5ESS/3B20D/DMERT technology is still in active use, that
>     sleeping dragon can lie.
> Your best bet may be to contact Sarah Autumn at the Connections 
> Museum, they have a 1ESS and 3ESS.
> http://www.telcomhistory.org/connections-museum-seattle-exhibits/electronic-switching/
> I don't remember if they have the 1A variant but they should have the 
> BSPs for all of this which would give you a lot of what you are after.
>     What's gotten me curious is reading about 1ESS in a BSTJ volume I
>     picked up, noting the particulars on how previous concerns of
>     manual and electro-mechanical systems were abstracted into
>     software.  Even without surviving examples, were previous systems
>     such as the 1ESS central control ever ported to or considered for
>     porting to UNIX, or was the hardware interface to the telco lines
>     too specific to consider a future swap-out with, say, a PDP11
>     running arbitrary software?  Columbus's SCCS (switching, not
>     source code) also comes to mind, although all I know that survives
>     of that is the CB-UNIX 2.3 manual descriptions of bits and pieces.
>     By the way, it's funny, I have UNIX to thank for my current
>     experiments with telephones and other signalling stuff, what with
>     making me study the Bell System more generally.  It's starting to
>     come full circle in that I want to take a crack at reading
>     dialing, at least pulse, into some sort of software abstraction on
>     a SBC that can, among other things, provide a switching service on
>     top of a UNIX-like kernel.  I don't know what I'd do with such a
>     thing other than assign work conference call rooms their own phone
>     numbers to dial with a telephone on a serial line...but if I can
>     even get that far I'd call it a success.  One less dependency on
>     the mobile...
>     - Matt G.
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