From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 9474 invoked from network); 4 Oct 2023 06:52:48 -0000 Received: from minnie.tuhs.org (2600:3c01:e000:146::1) by inbox.vuxu.org with ESMTPUTF8; 4 Oct 2023 06:52:48 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 7E22840BFA; Wed, 4 Oct 2023 16:52:43 +1000 (AEST) Received: from mail-pg1-x52e.google.com (mail-pg1-x52e.google.com [IPv6:2607:f8b0:4864:20::52e]) by minnie.tuhs.org (Postfix) with ESMTPS id E39D240BF8 for ; Wed, 4 Oct 2023 16:52:36 +1000 (AEST) Received: by mail-pg1-x52e.google.com with SMTP id 41be03b00d2f7-5892832f8daso479613a12.0 for ; Tue, 03 Oct 2023 23:52:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kev009.com; s=google; t=1696402356; x=1697007156; darn=tuhs.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=is5+rijxDhwz5IfWu8Is91fGVr7oa/u6YYwgY0Rdj+E=; b=KhDwNM8mvr9TmKcXmOMYj3GjR7AA4tlU6fbJtMyRjqeoAg7CCa54hR1VbnMOiKxAIp ptutw6/DjLNrBXB4LtpyO/59VjoJwgBRSVjlpaT4t9rJmmQzoWA5x5zUdJJjkiF3KIqp bFEE9YVxbgREc4C2SSGT7GUrTA9nAX1CuViOM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696402356; x=1697007156; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=is5+rijxDhwz5IfWu8Is91fGVr7oa/u6YYwgY0Rdj+E=; b=pF7tmfisd8W7O14nHpvdr6PTyjEefp2fHBH425ehUuIMJsy5plgM9jxAu22xQtd/qR nwLK5tHUnzbqH9ww2AyuvF7L8UmBvYr0MXOQ9qMW6Me0JxXoLmlmbiNJQ5S4vDy/4T+C aKZsYYnnatU4XtY7Y7CpWrMAqiV0qWOOJ3i76wDCzPHN4jHQe1vJ75DrziZbRSRYAKZp BErTGpHFKJ+8YVvbkPklqv8lUFtAzW5VkzjFU1gwmwnhybgb3I5S7ltY3bwuQfv66eM3 147+hpy3wKor1dhhTDqUOnuUfM9uIN2nOLmDDBUFJ5NmBf/Utj0IobwTfjZ6tBiuHpxz 8yGw== X-Gm-Message-State: AOJu0Yw90OPb03pYU38IviDprnw4FJ/knl7OhjEOKfTCNUiGrHB2zC36 vwuK/5P/JKWPDGsAQUWFZw+dhGrEFYzL4aj4fDXWagUNf4eLRzw91D4= X-Google-Smtp-Source: AGHT+IElHzUy7fypsAoYedOUDRdjESfp9Qg3TJ0GJsm96ggI6IblHKI2bQ/RdSp7lHtg3TvTa3yH3UN1CapIz/kx9Bc= X-Received: by 2002:a17:90b:1091:b0:268:2af6:e48c with SMTP id gj17-20020a17090b109100b002682af6e48cmr2319746pjb.4.1696402355863; Tue, 03 Oct 2023 23:52:35 -0700 (PDT) MIME-Version: 1.0 References: <202309260137.38Q1btZU325043@darkstar.fourwinds.com> <1eaf63bd-5394-a692-ad42-c8dd5c1a741c@osta.com> In-Reply-To: <1eaf63bd-5394-a692-ad42-c8dd5c1a741c@osta.com> From: Kevin Bowling Date: Tue, 3 Oct 2023 23:52:24 -0700 Message-ID: To: heinz@osta.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Message-ID-Hash: CKDI7IKU7ZA5GBJIM32YLBB7SR6ZSDJX X-Message-ID-Hash: CKDI7IKU7ZA5GBJIM32YLBB7SR6ZSDJX X-MailFrom: kevin.bowling@kev009.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: tuhs@tuhs.org X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [TUHS] Re: Known Specimens of Pre-5ESS UNIX Telephone Switching Software? List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Tue, Sep 26, 2023 at 7:46=E2=80=AFPM Heinz Lycklama wro= te: > > 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 piece= s. > > 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 ev= en > 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 t= he > projects in his group was SS1, an all-digital exchange. I have some vagu= e > 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 manuall= y > 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 tha= t > 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 > >