[ih] Arpanet physical connectors

[John Day]

About the same time, we had a VDH at Illinois to connect Purdue.

John

> On Jul 23, 2020, at 10:08, Vint Cerf via Internet-history <internet-history at elists.isoc.org> wrote:
> 
> 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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