[ih] Arpanet physical connectors

[Vint Cerf]

1973 most likely; certainly no later than 1974.
v


On Thu, Jul 23, 2020 at 10:06 AM Steve Crocker <steve at shinkuro.com> wrote:

> Vint,
>
> What year was that connection established?
>
> Steve
>
> On Thu, Jul 23, 2020 at 10:04 AM Vint Cerf <vint at google.com> wrote:
>
>> at Stanford my PDP-11/20 was connected by VDH to an IMP in another
>> building on the campus.
>>
>> v
>>
>>
>> On Thu, Jul 23, 2020 at 9:56 AM Steve Crocker via Internet-history <
>> internet-history at elists.isoc.org> wrote:
>>
>>> Much of this has been covered already in responses to your note, but we
>>> can
>>> add a little more.  The connectors were definitely NOT RS-232.  The BBN
>>> team designed the connector.  I believe they wanted it to be as simple as
>>> possible.  It was bit serial, operating at 100 kilobits per second.  The
>>> lines connecting the IMPs operated at 50 kilobits per second, so 100 kb/s
>>> was a reasonable fit.  Making it run much faster wouldn't have made a
>>> noticeable difference in the overall performance.  The interface was
>>> designed to operate up to 50 feet from the host.  A different interface
>>> was
>>> designed later to operate up to, I think, 1000 feet.  These were referred
>>> to as the Local Host (LH) and Distant Host (DH)  interface.  A third
>>> version was designed yet later to operate over unlimited distance.  It
>>> was
>>> called the Very Distant Host (CDH) interface.
>>>
>>> I believe Severo Ornstein and Ben Barker were the key hardware people at
>>> BBN.  Mike Wingfield at UCLA built the first host interface for our Sigma
>>> 7.  All are copied on this message.  BBN Report 1822 has the details, as
>>> reported in other messages.
>>>
>>> As noted, each site had to figure out how to connect the IMP into its
>>> host.  This required a separate design and implementation at each of the
>>> initial sites, and thus it was indeed important to have competent EE
>>> people
>>> involved.  After a while, ACC and DEC and perhaps others started to make
>>> interfaces available for various hosts.
>>>
>>> Steve
>>>
>>>
>>> On Thu, Jul 23, 2020 at 8:02 AM Stephane Bortzmeyer via Internet-history
>>> <
>>> internet-history at elists.isoc.org> wrote:
>>>
>>> > https://twitter.com/nielstenoever/status/1286254151874293760
>>> >
>>> > Dear Internet History nerds, what did the connectors and cables of the
>>> > ARPAnet look like?
>>> >
>>> > Were these serial cables? Seems likely because the RS-232 standard
>>> dates
>>> > back to 1960.
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>>> >
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>>
>>
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>>

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