From: pnr@planet.nl (Paul Ruizendaal)
Subject: [TUHS] TUHS Digest, Vol 14, Issue 63
Date: Wed, 18 Jan 2017 15:29:26 +0100 [thread overview]
Message-ID: <E811C617-5058-4BCE-8914-4B70E41F0247@planet.nl> (raw)
In-Reply-To: <20170117153207.B39A518C094@mercury.lcs.mit.edu>
I asked over at the internet history list
(http://mailman.postel.org/pipermail/internet-history/2017-January/thread.html)
Short of it is that it used Bell 303C modems which operated at 50kb/s operating
over an analog "broadband" channel predating the T1. It used the space of 12 voice
channels and some fairly fancy modulation techniques. Connection to the trunk
exchange was over a leased line.
On 17 Jan 2017, at 16:32 , Noel Chiappa wrote:
>
>> From: Joerg Schilling
>
>> Was T1 a "digital" line interface, or was this rather a 24x3.1 kHz
>> channel?
>
> Google is your friend:
>
> https://en.wikipedia.org/wiki/T-carrier
> https://en.wikipedia.org/wiki/Digital_Signal_1
>
>
>> How was the 64 ??? Kbit/s interface to the first IMPs implemented?
>> Wasn't it AT&T that provided the lines for the first IMPs?
>
> Yes and no. Some details are given in "The interface message processor for the
> ARPA computer network" (Heart, Kahn, Ornstein, Crowther and Walden), but not
> much. More detail of the business arrangement is contained in "A History of
> the ARPANET: The First Decade" (BBN Report No. 4799).
>
> Details of the interface, and the IMP side, are given in the BBN proposal,
> "Interface Message Processor for the ARPA Computer Network" (BBN Proposal No.
> IMP P69-IST-5): in each direction there is a digital data line, and a clock
> line. It's synchronous (i.e. a constant stream of SYN characters is sent
> across the interface when no 'frame' is being sent).
>
> The 50KB modems were, IIRC, provided by the Bell system; the diagram in the
> paper above seems to indicate that they were not considered part of the IMP
> system. The modems at MIT were contained in a large rack, the same size as
> the IMP, which stood next to it.
>
> I wasn't able to find anything about anything past the IMP/modem interface.
> Perhaps some AT+T publications of that period might detail how the modem,
> etc, worked.
>
> Noel
next prev parent reply other threads:[~2017-01-18 14:29 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-17 15:32 Noel Chiappa
2017-01-18 14:29 ` Paul Ruizendaal [this message]
-- strict thread matches above, loose matches on Subject: below --
2017-01-16 19:46 Noel Chiappa
2017-01-17 0:30 ` Brad Spencer
[not found] <mailman.1.1484532001.2693.tuhs@minnie.tuhs.org>
2017-01-16 16:00 ` Doug McIlroy
2017-01-16 16:22 ` Marc Rochkind
2017-01-16 16:44 ` Larry McVoy
2017-01-16 16:52 ` Marc Rochkind
2017-01-16 19:17 ` Steve Johnson
2017-01-16 19:21 ` Larry McVoy
2017-01-16 19:57 ` Ken Thompson
2017-01-16 23:41 ` Tim Bradshaw
2017-01-16 23:45 ` Brantley Coile
2017-01-17 4:07 ` Jason Stevens
2017-01-17 5:22 ` William Corcoran
2017-01-17 11:43 ` Jason Stevens
2017-01-17 14:27 ` Joerg Schilling
2017-01-17 14:21 ` Joerg Schilling
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