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

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

[segaloco via TUHS]

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.

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.

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

[Jon Steinhart]

segaloco via TUHS writes:
> 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.
> 
> 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.

Heinz might know something about this.  If I remember correctly, one of the
projects in his group was SS1, an all-digital exchange.  I have some vague
memory of him and Carl poring over some gigantic switch statement looking
for a bug - the long distance code wasn't sending the ST pulse and as a
result all of the key pulse senders at the Berkeley Heights telephone
exchange were taken off line and needed a technician to go in and manually
reset them.  They were not amused.  Fortunately, they and BTL were both
children of Ma Bell.

If my memory serves me correctly, the system had a pair of PDP-11/10s that
ran Hal Alles's digital filter code, a PDP11/70 behind the whole thing,
Harry Breece's active replacement circuitry for the hybrid transformers,
and some huge insanely fast wire-wrapped boards designed by John Sheets
that did TDM switching.

Jon

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

[Jon Steinhart]

Oh yeah, and I think that this is why Heinz wrote MERT, but
he should know more than me about it.

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

[Andrew Hume]

i’m sure there are standing references to all this. but as i recall,
the 5ESS was a more or less local switching system.

the guts of the long distance network were embedded in the (roughly) 140 1ESS’s. they ran
a completely separate (and substantially older) code that supported things like SS7 (signaling code
that was NOT embedded in the voice channel). the 1ESS was a complex piece of equipment.

my interaction with this was tangential. throughout the 1980-90s, i had a tight grip on how
accounting messages were handled within AT&T and wrote some C code that handled a
a transition from one level of the standard software to another level. and that code ran inside
the 1ESS.

but this was a long time ago.

> On Sep 25, 2023, at 6:24 PM, segaloco via TUHS <tuhs@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.
> 
> 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.

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

[steve jenkin]

For those playing along at home, 
“Gecko” was written up.

Virtual Data Warehousing, Data Publishing and Call Detail 
	<https://link.springer.com/chapter/10.1007/10721056_8>

and a conference paper of the same name
	<https://www.researchgate.net/publication/221629788_Virtual_Data_Warehousing_Data_Publishing_and_Call_Detail>

from 
Databases in Telecommunications: International Workshop, Co-located with VLDB-99, Edinburgh, Scotland, UK, September 6th, 1999. Proceedings
	<https://www.researchgate.net/publication/321558305_Databases_in_Telecommunications_International_Workshop_Co-located_with_VLDB-99_Edinburgh_Scotland_UK_September_6th_1999_Proceedings>



> On 26 Sep 2023, at 11:50, Andrew Hume <andrew@humeweb.com> wrote:
> 
> i’m sure there are standing references to all this. but as i recall,
> the 5ESS was a more or less local switching system.
> 
> the guts of the long distance network were embedded in the (roughly) 140 1ESS’s. they ran
> a completely separate (and substantially older) code that supported things like SS7 (signaling code
> that was NOT embedded in the voice channel). the 1ESS was a complex piece of equipment.
> 
> my interaction with this was tangential. throughout the 1980-90s, i had a tight grip on how
> accounting messages were handled within AT&T and wrote some C code that handled a
> a transition from one level of the standard software to another level. and that code ran inside
> the 1ESS.
> 
> but this was a long time ago.

--
Steve Jenkin, IT Systems and Design 
0412 786 915 (+61 412 786 915)
PO Box 38, Kippax ACT 2615, AUSTRALIA

mailto:sjenkin@canb.auug.org.au http://members.tip.net.au/~sjenkin

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

[Kevin Bowling]

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On Mon, Sep 25, 2023 at 6:25 PM segaloco via TUHS <tuhs@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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[TUHS] Re: Known Specimens of Pre-5ESS UNIX Telephone Switching Software?

[Brad Spencer]

Andrew Hume <andrew@humeweb.com> writes:

> i’m sure there are standing references to all this. but as i recall,
> the 5ESS was a more or less local switching system.
>
> the guts of the long distance network were embedded in the (roughly) 140 1ESS’s. they ran
> a completely separate (and substantially older) code that supported things like SS7 (signaling code
> that was NOT embedded in the voice channel). the 1ESS was a complex piece of equipment.
>
> my interaction with this was tangential. throughout the 1980-90s, i had a tight grip on how
> accounting messages were handled within AT&T and wrote some C code that handled a
> a transition from one level of the standard software to another level. and that code ran inside
> the 1ESS.
>
> but this was a long time ago.
>
>> On Sep 25, 2023, at 6:24 PM, segaloco via TUHS <tuhs@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.
>> 
>> 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.


So...  I am speaking from a single point of view about stuff I worked on
a very long time ago....

On the operations support system I worked on at AT&T/Lucent...  we
supported all manor of switches, all of those made by AT&T/Lucent and a
whole lot made by other companies.  This is what I recall...

I believe that the 1A had left the building and no longer existed in any
installed base in the US when I started, although we supported it still
in our software because of the pain of ripping it out.  The 1E did exist
in some numbers (I may have these backwards, BTW... it might have been
the 1A that existed and the 1E had crossed the rainbow bridge).  I do
recall that either the 1A or 1E had a lot of features, but it may have
been more of a case of it just being around a long time and was infected
with warts.  The work horses, however, were the 4ESS and the 5ESS.  The
4E did the long haul work and was often configured in a tandem set up
(that was the term used, Tandem, which meant something specific at the
time).  The 4E was also a very large monster of a device... taking up
pretty much an entire floor of a building.  The software in it was very
old with lots of add on sub-devices to provide new ability (our product
used some of those sub-devices).  Those sub-devices might have run their
own operating systems and could have been computers all by themselves...
that is, there were multiple glued together computers to get the 4E
effect.  The 5E was a lot cleaner and much smaller.  It also had some
sub-device stuff going on but nothing like what the 4E had.  I do seem
to recall that the 5E runs some version of Unix, at least on part of the
device, but I don't remember if the main switching engine did, however
(I suspect not, BTW).  I am almost 100% sure that the 4E did not run
Unix on the main switching engine, but it would not surprise me that it
found its way into it somewhere or other (probably in multiple places
given how large the device was).

The 5E and 4E may have started out life with particular roles, but this
wasn't very strict.  That is it was completely ok for a 5E to do long
haul work if so configured and it was very possible for a 4E to
terminate a call.  There was a great deal of flexibility present.  AT&T
long wire was a bit of a different place with respect to the 4E..  I
seem to remember that at the time I was there they had something like
800 4E configured to do long distance service in the US.  At least the
traffic management part was managed by a set of Amdauls (using Unix as
the operating system I believe) running an operation system product that
was very much related to the one I worked on...  simular internals for
example and in my early days we all sat in the same group.

The product I worked on also supported the SS7 switches (I say
"switches" here, but that probably isn't exactly what they were.  I also
don't remember their actual names...  STM, maybe??).  I worked with the
SS7 development group on a new operations system interface and during
that conversation they mentioned that the SS7 switch ran a more or less
unmodified Unix Solaris (one would assume on a Sparc).  They also
mentioned that they had performed kernel modifications in the past, but
the cost of maintaining that sort of thing was very high, so they had
moved away from doing that towards a more "push it to userland" way of
thinking.






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

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

[Sebastien F4GRX]

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Hello,

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 : 
https://www.youtube.com/watch?v=k865-VjWUk8

Sebastien

Le 26/09/2023 à 04:20, Kevin Bowling a écrit :
>
>
> On Mon, Sep 25, 2023 at 6:25 PM segaloco via TUHS <tuhs@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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[TUHS] Re: Known Specimens of Pre-5ESS UNIX Telephone Switching Software?

[segaloco via TUHS]

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Thanks for all the great information everyone. It sounds like I need to start considering a little trip down to Seattle to check out a few of these different computing/technology history organizations. They're a quick train ride down the coast, and my dreams of pulling together some sort of computing/technology history collective up here have been fruitless thus far, maybe I just need to recognize it as a big city thing and get more comfortable with considering little trips for this kind of stuff.

- Matt G.
------- Original Message -------
On Tuesday, September 26th, 2023 at 9:07 AM, Sebastien F4GRX <f4grx@f4grx.net> wrote:

> Hello,
>
> 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 : https://www.youtube.com/watch?v=k865-VjWUk8
>
> Sebastien
>
> Le 26/09/2023 à 04:20, Kevin Bowling a écrit :
>
>> On Mon, Sep 25, 2023 at 6:25 PM segaloco via TUHS <tuhs@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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[TUHS] Re: Known Specimens of Pre-5ESS UNIX Telephone Switching Software?

[George Michaelson]

It may be obvious, certainly to anyone who owns the BSTL series (I
don't. I read it in the library at uni), but would I be  right in
thinking the motivation behind "real time UNIX" was switching? It's
the closest problem to Bell labs which demands time critical outcomes,
the delay tolerance in circuit establishment and end-to-end telephony
signaling was there, but it was finite. And, for capacity planning
purposes being told a single unit of UNIX logic controlling a
telephone switch could handle X call setup and tear-down events per
second meant you could do the Erlang sums over customers call volumes
and phone handset counts.

The british digital switch experience in the System-X series Was
GEC/Plessey, and ran CORAL which was the real time system they used to
do MILSPEC stuff. It was explicitly fault tolerant design, lots of 2
and triple redundant componentry.

-G

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

[Heinz Lycklama]

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To answer Jon's following question (2 minutes later):
------------------------------------------------------------------------
Oh yeah, and I think that this is why Heinz wrote MERT,
but he should know more than me about it.
------------------------------------------------------------------------
Yes, my Dept. in MH was involved in the early days of digital switching
and the need for real-time response was certainly recognized.
But MERT was not developed with a specific telephony project in mind.
I was mostly involved in software in support of current projects
being done in the Dept. We started the MERT project at the
time that DEC announced their PDP-11/45 mini-computer in
the early 1970's because it supported 3 separate address
spaces - system, supervisor, and user. This enabled us to
run operating system environments with different user
application program needs, specifically real-time under
control of one supervisor and time-sharing applications
in another supervisor, to start with. Hence its name -
Multi-Environment Real Time (MERT). Once we had MERT up
and running on the PDP-11/45 and PDP-11/70 computers, some
projects in other Bell Labs locations involved in telephony projects
started building their projects on the MERT system. The
DMERT system was developed later on by projects at yet
another Bell Labs location.

Heinz

On 9/25/2023 6:37 PM, Jon Steinhart wrote:
> segaloco via TUHS writes:
>> 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.
>>
>> 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.
> Heinz might know something about this.  If I remember correctly, one of the
> projects in his group was SS1, an all-digital exchange.  I have some vague
> memory of him and Carl poring over some gigantic switch statement looking
> for a bug - the long distance code wasn't sending the ST pulse and as a
> result all of the key pulse senders at the Berkeley Heights telephone
> exchange were taken off line and needed a technician to go in and manually
> reset them.  They were not amused.  Fortunately, they and BTL were both
> children of Ma Bell.
>
> If my memory serves me correctly, the system had a pair of PDP-11/10s that
> ran Hal Alles's digital filter code, a PDP11/70 behind the whole thing,
> Harry Breece's active replacement circuitry for the hybrid transformers,
> and some huge insanely fast wire-wrapped boards designed by John Sheets
> that did TDM switching.
>
> Jon

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

[Lars Brinkhoff]

Maybe also visit the ICM Museum / SDF Museum.

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

[Kevin Bowling]

On Tue, Sep 26, 2023 at 7:46 PM Heinz Lycklama <heinz@osta.com> wrote:
>
> To answer Jon's following question (2 minutes later):
> ________________________________
> Oh yeah, and I think that this is why Heinz wrote MERT,
> but he should know more than me about it.
> ________________________________
> Yes, my Dept. in MH was involved in the early days of digital switching
> and the need for real-time response was certainly recognized.
> But MERT was not developed with a specific telephony project in mind.
> I was mostly involved in software in support of current projects
> being done in the Dept. We started the MERT project at the
> time that DEC announced their PDP-11/45 mini-computer in
> the early 1970's because it supported 3 separate address
> spaces - system, supervisor, and user. This enabled us to
> run operating system environments with different user
> application program needs, specifically real-time under
> control of one supervisor and time-sharing applications
> in another supervisor, to start with. Hence its name -
> Multi-Environment Real Time (MERT). Once we had MERT up
> and running on the PDP-11/45 and PDP-11/70 computers, some
> projects in other Bell Labs locations involved in telephony projects
> started building their projects on the MERT system. The
> DMERT system was developed later on by projects at yet
> another Bell Labs location.

I don't have access to IEEE but there is a paper on MERT
https://ieeexplore.ieee.org/document/6770410.  The 3B20D and DMERT are
also cronicaled in the BSTJ, I have hard copies of that but it should
be on IEEE.

There is a lot of detail on the 3B20D and 3B21D in the 254 BSPs as
well as some coverage of UNIX RTR
https://www.telecomarchive.com/plant-all.html.

There is more coverage of the 3B20 elsewhere, for instance
https://dl.acm.org/doi/pdf/10.1145/1500412.1500418.  Wing N. Toy, one
of the hardware engineers, published some nice books that tangentially
touch on these designs but contain a lot of great microcoding
knowledge.

Regards,
Kevin


> Heinz
>
> On 9/25/2023 6:37 PM, Jon Steinhart wrote:
>
> segaloco via TUHS writes:
>
> 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.
>
> 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.
>
> Heinz might know something about this.  If I remember correctly, one of the
> projects in his group was SS1, an all-digital exchange.  I have some vague
> memory of him and Carl poring over some gigantic switch statement looking
> for a bug - the long distance code wasn't sending the ST pulse and as a
> result all of the key pulse senders at the Berkeley Heights telephone
> exchange were taken off line and needed a technician to go in and manually
> reset them.  They were not amused.  Fortunately, they and BTL were both
> children of Ma Bell.
>
> If my memory serves me correctly, the system had a pair of PDP-11/10s that
> ran Hal Alles's digital filter code, a PDP11/70 behind the whole thing,
> Harry Breece's active replacement circuitry for the hybrid transformers,
> and some huge insanely fast wire-wrapped boards designed by John Sheets
> that did TDM switching.
>
> Jon
>
>

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

[Kevin Bowling]

On Tue, Oct 3, 2023 at 11:52 PM Kevin Bowling <kevin.bowling@kev009.com> wrote:
>
> On Tue, Sep 26, 2023 at 7:46 PM Heinz Lycklama <heinz@osta.com> wrote:
> >
> > To answer Jon's following question (2 minutes later):
> > ________________________________
> > Oh yeah, and I think that this is why Heinz wrote MERT,
> > but he should know more than me about it.
> > ________________________________
> > Yes, my Dept. in MH was involved in the early days of digital switching
> > and the need for real-time response was certainly recognized.
> > But MERT was not developed with a specific telephony project in mind.
> > I was mostly involved in software in support of current projects
> > being done in the Dept. We started the MERT project at the
> > time that DEC announced their PDP-11/45 mini-computer in
> > the early 1970's because it supported 3 separate address
> > spaces - system, supervisor, and user. This enabled us to
> > run operating system environments with different user
> > application program needs, specifically real-time under
> > control of one supervisor and time-sharing applications
> > in another supervisor, to start with. Hence its name -
> > Multi-Environment Real Time (MERT). Once we had MERT up
> > and running on the PDP-11/45 and PDP-11/70 computers, some
> > projects in other Bell Labs locations involved in telephony projects
> > started building their projects on the MERT system. The
> > DMERT system was developed later on by projects at yet
> > another Bell Labs location.
>
> I don't have access to IEEE but there is a paper on MERT
> https://ieeexplore.ieee.org/document/6770410.  The 3B20D and DMERT are
> also cronicaled in the BSTJ, I have hard copies of that but it should
> be on IEEE.
>
> There is a lot of detail on the 3B20D and 3B21D in the 254 BSPs as
> well as some coverage of UNIX RTR
> https://www.telecomarchive.com/plant-all.html.
>
> There is more coverage of the 3B20 elsewhere, for instance
> https://dl.acm.org/doi/pdf/10.1145/1500412.1500418.  Wing N. Toy, one
> of the hardware engineers, published some nice books that tangentially
> touch on these designs but contain a lot of great microcoding
> knowledge.

I was reviewing this book
https://archive.org/details/computerhardware0000toyw and it is one of
the best computer architecture books I've seen.  Somehow in 400 pages
the authors manage to cover logic, language implementation,
compilation, instruction set design, various aspects of operating
systems design, and fault tolerance citing timeless pedagogical
hardware (PDP11, VAX, S/370, System/38, iAPX-432, WE32000) and
software (VMS, UNIX, DMERT).  Readers of this list will enjoy it!

> Regards,
> Kevin
>
>
> > Heinz
> >
> > On 9/25/2023 6:37 PM, Jon Steinhart wrote:
> >
> > segaloco via TUHS writes:
> >
> > 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.
> >
> > 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.
> >
> > Heinz might know something about this.  If I remember correctly, one of the
> > projects in his group was SS1, an all-digital exchange.  I have some vague
> > memory of him and Carl poring over some gigantic switch statement looking
> > for a bug - the long distance code wasn't sending the ST pulse and as a
> > result all of the key pulse senders at the Berkeley Heights telephone
> > exchange were taken off line and needed a technician to go in and manually
> > reset them.  They were not amused.  Fortunately, they and BTL were both
> > children of Ma Bell.
> >
> > If my memory serves me correctly, the system had a pair of PDP-11/10s that
> > ran Hal Alles's digital filter code, a PDP11/70 behind the whole thing,
> > Harry Breece's active replacement circuitry for the hybrid transformers,
> > and some huge insanely fast wire-wrapped boards designed by John Sheets
> > that did TDM switching.
> >
> > Jon
> >
> >