From: jnc@mercury.lcs.mit.edu (Noel Chiappa)
Subject: [TUHS] TUHS Digest, Vol 14, Issue 63
Date: Tue, 17 Jan 2017 10:32:07 -0500 (EST) [thread overview]
Message-ID: <20170117153207.B39A518C094@mercury.lcs.mit.edu> (raw)
> 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 reply other threads:[~2017-01-17 15:32 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-17 15:32 Noel Chiappa [this message]
2017-01-18 14:29 ` Paul Ruizendaal
-- 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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