[ih] Arpanet physical connectors

Jack Haverty jack at 3kitty.org
Thu Jul 23 11:54:56 PDT 2020

Yeah, lines were a problem everywhere too.   I was peripherally involved
in the 80s with an ARPANET clone that we deployed and then ran for a big
international corporation.   They tended to need IMPs and lines at sites
in unusual places which made it even harder to get them.   I remember
one time a line was needed in some obscure country (one of the tiny
countries in South America IIRC), and the quoted delivery time was
something like 2 years.  Even that was a "maybe".

As we engineers mused about alternatives like satellite circuits, the
corporation solved the problem as big corporations do.  They simply
bought the country's PTT operation.   The line we had ordered was
installed a few weeks later.

It got better though.  I remember at some point we created a portable
package (basically a PC, modem, and IMP, which were much smaller by
then) that a salesperson could take on a sales call.    A live demo was
performed - e.g., by simply unplugging the phone line from the phone on
the manager's desk, plugging it into the IMP/modem, and linking the node
in as part of our demo network back in Cambridge.  Took literally a few
minutes, and probably helped sell a few ARPANET clones during the 80s.

IMHO, part of the History of the Internet involves the History of the
Mundane - like connectors and lines.

Fun times...

On 7/23/20 10:15 AM, Steve Crocker wrote:
> Equal pain on the long distance lines.  They had to be ordered through
> AT&T Long Lines.  Standard delivery time was nine months.  In one case
> we ordered lines into and out of Boulder, CO.  And then the intended
> site balked and said they didn't want to be connected.  We wound up
> putting a TIP into a Dept of Commerce office building in Boulder.
> On Thu, Jul 23, 2020 at 1:00 PM Jack Haverty via Internet-history
> <internet-history at elists.isoc.org
> <mailto:internet-history at elists.isoc.org>> wrote:
>     On 7/23/20 8:53 AM, Noel Chiappa via Internet-history wrote:
>     > To start with DH (by far and away the most common), IMPs had a
>     specified round
>     > 'female' plug (a mil-spec connecter, available from AMP - like
>     the one in the
>     > URL Carsten provided - I think the axact part number is in the
>     documemtation),
>     > mounted on the back of the IMP somewhere.
>     I remember these connectors well, because of a strange experience
>     I had
>     involving them.  
>     They were big, sturdy, heavy, expensive military-grade connectors.   I
>     don't remember the part number though.   Computer interconnecting
>     cables
>     in that era were often large and unwieldy.  E.g., the PDP-10 bus
>     cables
>     to interconnect processor, memories, storage cabinets et al were huge,
>     and quite expensive.
>     At one point in the 80s, I was in charge of a contract to build and
>     deliver some equipment using the same connectors, in order to be
>     compatible with the IMPs.   We had a tight schedule, with the contract
>     requiring delivery of the first units 12 months after signing the
>     contract.  
>     Not expected to be a problem.    Except..... we quickly discovered
>     that
>     those particular connectors were readily available through the usual
>     channels --- with a lead time of 60 weeks to delivery!  
>     Apparently such
>     military-grade connectors are only built when needed, and unless we
>     ordered 10,000 or so they wouldn't schedule a special manufacturing
>     run.   We should have ordered them before we submitted the
>     proposal I guess.
>     So much easier these days.  After all there's not all that many
>     different flavors of USB physical connectors!  All available with
>     one or
>     two day delivery too.
>     /Jack
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