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, HTML_MESSAGE,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 12387 invoked from network); 16 Jun 2020 22:42:06 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 16 Jun 2020 22:42:06 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id 166159C878; Wed, 17 Jun 2020 08:42:03 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id C06229C856; Wed, 17 Jun 2020 08:41:19 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=planet.nl header.i=@planet.nl header.b="Oq3Xk5N9"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id C65139C856; Wed, 17 Jun 2020 08:41:16 +1000 (AEST) Received: from cpsmtpb-ews07.kpnxchange.com (cpsmtpb-ews07.kpnxchange.com [213.75.39.10]) by minnie.tuhs.org (Postfix) with ESMTP id 75BBF9C851 for ; Wed, 17 Jun 2020 08:41:12 +1000 (AEST) Received: from cpsps-ews13.kpnxchange.com ([10.94.84.180]) by cpsmtpb-ews07.kpnxchange.com with Microsoft SMTPSVC(8.5.9600.16384); Wed, 17 Jun 2020 00:41:10 +0200 X-Brand: 7abm2Q== X-KPN-SpamVerdict: e1=0;e2=0;e3=0;e4=(e1=10;e3=10;e2=11;e4=10);EVW:Whi te;BM:NotScanned;FinalVerdict:Clean X-CMAE-Analysis: v=2.3 cv=Pv8IkzE3 c=1 sm=1 tr=0 cx=a_idp_e a=LO2mTXPAMClkaqVt2RTykg==:117 a=soxbC+bCkqwFbqeW/W/r+Q==:17 a=x1i13A_MHe4A:10 a=nTHF0DUjJn0A:10 a=AoeSMSUmAAAA:8 a=019PLASFR3d1WDHXFw0A:9 a=QEXdDO2ut3YA:10 a=4yNg-XxIvkw7qbIx:21 a=_W_S_7VecoQA:10 a=2UY7SMgi64q-0UtCmZ5F:22 X-CM-AcctID: kpn@feedback.cloudmark.com Received: from smtp.kpnmail.nl ([195.121.84.12]) by cpsps-ews13.kpnxchange.com over TLS secured channel with Microsoft SMTPSVC(8.5.9600.16384); Wed, 17 Jun 2020 00:41:10 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=planet.nl; s=planet01; h=to:date:message-id:subject:mime-version:content-type:from; bh=NlYYZCUVUaxOt2UsESrydjNDlFycD3VGFmsH6r1dRws=; b=Oq3Xk5N93N3uoRAiRdZCr76SkpTZ3lJTt30XA/tUxHHSQBCvrsMxuhacYyxV6KU9J1GcBW41HoqF9 sdjHYCiQEXGSctu2Lc7/a7kBBFR8JmG2vhNNpeMcqtfAX9jOJ/95QG08Ibr0fDv9v71d8fON1k7I7f SIALK4i9vf/XYomI= X-KPN-VerifiedSender: Yes X-CMASSUN: 33|r2tdceXPi1KzNg/S/7KP73qLz0viW8tsEa2x3i9wj5pi82Xl0Q3cXzr9EP22wML Ago7dITFjwdD7/eJVpJ5dmg== X-Originating-IP: 80.101.112.122 Received: from mba1.fritz.box (sqlite.xs4all.nl [80.101.112.122]) by smtp.kpnmail.nl (Halon) with ESMTPSA id 793e94ca-b022-11ea-9983-00505699772e; Wed, 17 Jun 2020 00:41:10 +0200 (CEST) From: Paul Ruizendaal Content-Type: multipart/alternative; boundary="Apple-Mail=_9E499E2B-ACA3-4538-9609-2103A0A4E6F5" Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) Message-Id: <1F6AD3BF-E7E8-49BD-8993-2539A10F1A89@planet.nl> Date: Wed, 17 Jun 2020 00:41:09 +0200 To: TUHS main list X-Mailer: Apple Mail (2.3445.9.1) X-OriginalArrivalTime: 16 Jun 2020 22:41:10.0243 (UTC) FILETIME=[3B435B30:01D6442F] X-RcptDomain: minnie.tuhs.org Subject: [TUHS] updated: loop networks at Bell Labs X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" --Apple-Mail=_9E499E2B-ACA3-4538-9609-2103A0A4E6F5 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 With some further reading and research (and the kind help of Heinz = Lycklama and Jon Steinart) I=E2=80=99ve found that my understanding of = early loop networks at Bell Labs confused several different systems. As = far as I can currently tell there were at least 4 different loop = networks developed around 1970 at Murray Hill. 1. The first one is the =E2=80=9CNewhall Loop=E2=80=9D (paper published = in 1969). This loop used twisted pair cabling, ran at about 3Mhz and = used variable sized messages. It seems to have used some sort of token = to coordinate between hosts. This might have been the network that Ken = Thompson recalled as having been in operation when he arrived at the = labs in 1966. 2. The second one appears to have been the =E2=80=9CPierce Loop=E2=80=9D, = as described in 3 BSTJ papers submitted in 1970/71. This one was coax = based, used T1 compatible frames and was used to connect H516 computers = with various bits of equipment. It seems to have had a very short life = span. Part of my confusion was that the term Pierce Loop also appears to = have been used in a generic sense to denote loop networks with = fixed-sized frames. 3. The third one is the =E2=80=9CWeller Loop=E2=80=9D (paper published = in 1971). This loop used coax cabling, ran at 3.3Mhz and used fixed 35 = bit frames/cells. Each cell carried one address byte and two data bytes. = One participant on the loop was the controller and effectively polled = the other stations. In its 1971 form it appears to have been for the = H516=E2=80=99s only and was referred to as a =E2=80=9CSerial I/O bus=E2=80= =9D. This is what Jon Steinhart was talking about. The Weller loop was later redesigned (memo written in 1973) to interface = with PDP-11=E2=80=99s as well. Heinz Lycklama used this loop in 1974 to = connect several systems running (rump) Unix - see his paper about = peripheral Unix here: = https://www.tuhs.org/Archive/Documentation/TechReports/Heinz_Tech_Memos/TM= -75-1352-2_Emulation_of_UNIX_on_Peripheral_Processors_19750109.pdf = This Serial I/O bus remained in use for several years at least. 4. The fourth and best known one is the =E2=80=9CSpider Loop=E2=80=9D = (memo published in 1974, but operational from 1972). Twisted pair = cabling, using T1 compatible frames. In use until about 1978. Main uses = appear to have been the =E2=80=98nfs=E2=80=99 file store and the = =E2=80=98npr=E2=80=99 remote printing service. My conclusion from all that is that in 1974 Unix had access to two = networks, Spider and the Serial I/O bus. For both, first experiments = would have been in 1973. It is hard to be sure which one came first. If = I had to venture a guess today, I=E2=80=99d say that Spider connected to = Unix several months before the Weller loop (even though the 1st = generation Weller loop preceded Spider). Maybe the conclusion is that = both happened more or less in parallel: Weller was also one of the = designers of the Spider hardware. --Apple-Mail=_9E499E2B-ACA3-4538-9609-2103A0A4E6F5 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 With = some further reading and research (and the kind help of Heinz Lycklama = and Jon Steinart) I=E2=80=99ve found that my understanding of early loop = networks at Bell Labs confused several different systems. As far as I = can currently tell there were at least 4 different loop networks = developed around 1970 at Murray Hill.

1. The first one is the =E2=80=9CNewhall = Loop=E2=80=9D (paper published in 1969). This loop used twisted pair = cabling, ran at about 3Mhz and used variable sized messages. It seems to = have used some sort of token to coordinate between hosts. This might = have been the network that Ken Thompson recalled as having been in = operation when he arrived at the labs in 1966.

2. The second one appears to have been = the =E2=80=9CPierce Loop=E2=80=9D, as described in 3 BSTJ papers = submitted in 1970/71. This one was coax based, used T1 compatible frames = and was used to connect H516 computers with various bits of equipment. = It seems to have had a very short life span. Part of my confusion was = that the term Pierce Loop also appears to have been used in a generic = sense to denote loop networks with fixed-sized frames.

3. The third one is the = =E2=80=9CWeller Loop=E2=80=9D (paper published in 1971). This loop used = coax cabling, ran at 3.3Mhz and used fixed 35 bit frames/cells. Each = cell carried one address byte and two data bytes. One participant on the = loop was the controller and effectively polled the other stations. In = its 1971 form it appears to have been for the H516=E2=80=99s only and = was referred to as a =E2=80=9CSerial I/O bus=E2=80=9D. This is what Jon = Steinhart was talking about.

The Weller loop was later redesigned = (memo written in 1973) to interface with PDP-11=E2=80=99s as well. Heinz = Lycklama used this loop in 1974 to connect several systems running = (rump) Unix - see his paper about peripheral Unix here:
https://www.tuhs.org/Archive/Documentation/TechReports/Heinz_Te= ch_Memos/TM-75-1352-2_Emulation_of_UNIX_on_Peripheral_Processors_19750109.= pdf

This = Serial I/O bus remained in use for several years at least.

4. The fourth and best = known one is the =E2=80=9CSpider Loop=E2=80=9D (memo published in 1974, = but operational from 1972). Twisted pair cabling, using T1 compatible = frames. In use until about 1978. Main uses appear to have been the = =E2=80=98nfs=E2=80=99 file store and the =E2=80=98npr=E2=80=99 remote = printing service.

My conclusion from all that is that in 1974 Unix had access = to two networks, Spider and the Serial I/O bus. For both, first = experiments would have been in 1973. It is hard to be sure which one = came first. If I had to venture a guess today, I=E2=80=99d say that = Spider connected to Unix several months before the Weller loop (even = though the 1st generation Weller loop preceded Spider). Maybe the = conclusion is that both happened more or less in parallel: Weller was = also one of the designers of the Spider hardware.
= --Apple-Mail=_9E499E2B-ACA3-4538-9609-2103A0A4E6F5--