[ih] Fwd: Fw: First ARPANET Link Put Into Service: November 21, 1969
Alexander McKenzie
aam3sendonly at gmail.com
Sun Nov 23 18:58:20 PST 2025
When IMP #2 was delivered to SRI it was accompanied by Marty Thrope from
BBN. Marty connected the IMP to the already installed phone line. Ben
Barker was at the UCLA IMP. When Ben saw the UCLA IMP declare the line up,
he used the IMP Teletype to send a message to the SRI IMP Teleletype sayin
"Hi Misan". ["Misan" was Thrope's Harvard radio station "handle"; Ben was
also part of the Harvard radio station crowd.] The message was delivered
and Marty responded; then they both went home, mission accomplished. This
preceded the well-known first Host-to-Host transmission well documented by
Kleinrock.
I do not believe IMPs had hardware that gave them their numbers.
Ben Barker died a couple of years ago.
Alex
----- Forwarded Message -----
*From:* Jack Haverty via Internet-history <internet-history at elists.isoc.org>
*To:* Steve Crocker <steve at shinkuro.com>
*Cc:* "internet-history at elists.isoc.org" <internet-history at elists.isoc.org>
*Sent:* Sunday, November 23, 2025 at 05:51:03 PM EST
*Subject:* Re: [ih] First ARPANET Link Put Into Service: November 21, 1969
There was a process involved in adding an IMP to the ARPANET. It no
doubt changed over time, so what happened with IMP #1 and #2 may be
different. I tried asking Ben Barker, since he is mentioned in that
1969 log entry, but the email addresses I have sadly no longer work.
IMPs had "fake hosts" which acted like real hosts but were implemented
as software inside the IMP. Back in 2012, Ben was helping with the
resurrection of the old IMP code and told me:
"The IMP code supported a number of "fake hosts". The TTY was one. DDT was
another. There may have been another 1 or 2; I had no use for them if they
existed, and do not remember them.
Each IMP had a hardware card that contained its IMP number, I believe.
There was a bit in the header that specified whether the message was for a
real host or a fake host.
I believe that the TTY was fake host 1 and the DDT was fake host zero.
I believe that the default was that the TTY would be set to connect to the
same IMP's DDT."
Part of the process of getting an IMP online was to first get the two
IMPs talking to each other. The TTY on one IMP could connect to the TTY
on the other IMP, so the engineers at the two sites could "talk" over
the net. You could also connect to the remote IMP's debugger (DDT) and
examine or modify the remote machine's memory.
After all that connectivity was working and the IMPs were judged
functional, then the actual physical hosts could test their ability to
communicate.
So it's possible that the fuzziness in the timeline was because it may
have taken a few weeks to run tests, get all the bugs out, and then
declare the first 2 nodes of the ARPANET, and the NCPs in their attached
hosts, to be "in service". The stories I've heard recounted that the
initial testing crashed with only the LO part of LOGIN successful.
One of the other fake hosts in the early IMPs was the one that sent
measurement data to UCLA. More than a decade later, when we were
involved in getting TCP/IP deployed, we noticed that the UCLA fake host
was still in the code. So we used it to create a "Remote Datascope" for
DDN (of course, worked in other ARPANET clones too) that could capture
the TCP and IP headers of host-host traffic -- invaluable for figuring
out what TCP was doing, especially as newly-written implementations by
big government contractors were coming online.
I doubt anyone knew, in 1969, what was starting then and how important
it would be.
/Jack
On 11/23/25 13:04, Steve Crocker wrote:
> After seeing the back and forth on this thread, I now think 21 Nov 1969
was when Larry Roberts came to UCLA. I'll try to check with Kleinrock.
>
> Steve
>
> Sent from my iPhone
>
>> On Nov 23, 2025, at 3:48 PM, Jack Haverty via Internet-history <
internet-history at elists.isoc.org> wrote:
>>
>> Perhaps someone in the Bay Area can go to CHM and ask what actually
happened on November 21, 1969...? /Jack
>>
>>> On 11/23/25 12:22, Barbara Denny via Internet-history wrote:
>>> Here is Don Nielson's response to my inquiry. I did cut out the first
paragraph as it only was for me. There is a typo regarding the 1972 ICC
meeting.
>>> barbara
>>> ----- Forwarded Message ----- From: Don Nielson <nielsonz at pacbell.net>To:
Barbara Denny <b_a_denny at yahoo.com>Sent: Friday, November 21, 2025 at
10:05:40 PM PSTSubject: Re: Fw: [ih] First ARPANET Link Put Into Service:
November 21, 1969
>>> "*** paragraph deleted*****
>>> I'm certain about the following:
>>> 1. First ARPANET connection - Between Bill Duvall at SRI and
Charlie Kline of UCLA
>>> on what has been accepted as 29 Oct 1969. I tried my best to
confirm the date
>>> while this date was being pushed by Len Kleinrock of UCLA. Even I
and Marc Weber
>>> the CHM dug into Engelbart's dinky handwritten notebooks and other
stuff on file at
>>> Stanford. As far as we could tell, nothing was noted on the SRI
end, indicating no big
>>> deal at the time. So, what has come to be accepted derives from a
brief jot on Charlie's
>>> scratchpad: "22:30 Talked to SRI Host to Host". Charlie and Bill
are still around
>>> and have confirmed and elaborated on the incident, being quoted in
some places.
>>> 2. ARPANET demo at the International Computer Communication Conference
in WDC
>>> of NCP in Oct 19723.
>>> 3. First 2-net demo of TCP was on 27 Aug 1976. PRNET and ARPANET.
>>> 4. First 3-net demo of TCP was on 22 Nov 1977. PRNET, SATNET, and
ARPANET.
>>> All this is easily available so 21 Nov 1969 seems an aberration by
someone.
>>> Take good care, Don
>>> On 11/21/25 10:14 AM, Barbara Denny wrote:
>>> Hi Don
>>> Hope you are doing well. This came up on the internet history
list. I am wondering if you could shed some insight on the log.
>>> Hope you have a good holiday.
>>> barbara
>>> ----- Forwarded Message ----- From: Vint Cerf via Internet-history
<internet-history at elists.isoc.org> To: Jack Haverty <jack at 3kitty.org> Cc: "
internet-history at elists.isoc.org" <internet-history at elists.isoc.org> Sent:
Friday, November 21, 2025 at 09:50:33 AM PST Subject: Re: [ih] First
ARPANET Link Put Into Service: November 21, 1969
>>> crocker and I were wondering the same thing off the list.
>>> v
>>> On Fri, Nov 21, 2025 at 12:49 PM Jack Haverty via Internet-history
<
>>> internet-history at elists.isoc.org> wrote:
>>> > Can anyone explain why the article says "What Happened on November
21st"
>>> > but the image of the "First ARPANET IMP log" shows "29 OCT"? /Jack
>>> >
>>> > On 11/21/25 09:37, vinton cerf via Internet-history wrote:
>>> > > there are so many milestone dates....
>>> > >
>>> > > v
>>> > >
>>> > >
>>> > >
>>> > > On Fri, Nov 21, 2025 at 12:03 PM Frantisek Borsik via
Internet-history <
>>> > > internet-history at elists.isoc.org> wrote:
>>> > >
>>> > >> Happy birthday to the Internet!
>>> > >>
>>> > >> https://www.computerhistory.org/tdih/november/21/
>>> > >>
>>> > >> All the best,
>>> > >>
>>> > >> Frank
>>> > >>
>>> > >> Frantisek (Frank) Borsik
>>> > >>
>>> > >>
>>> > >> *In loving memory of Dave Täht: *1965-2025
>>> > >>
>>> > >> https://libreqos.io/2025/04/01/in-loving-memory-of-dave/
>>>
>>>
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