[ih] Nit-picking an origin story

Mon Aug 18 07:21:43 PDT 2025

John,

See inline for comments.

Steve

On Mon, Aug 18, 2025 at 10:00 AM John Day via Internet-history <
internet-history at elists.isoc.org> wrote:

> Apologies for going back so far but just for the record, a couple of
> things.
>
> I have been working with David Hutchison at Univ of Lancaster and he has
> been digging through old archives.  He found a1965 memo by Davies who had
> just returned from a US conference where he heard several papers on about
> timesharing systems, and had the idea that they should do to networking
> what time-slicing did in OSs. He called it packet switching. (What is fun,
> David also found a memo by Derek Barber relating Donald coming back from
> the conference and excited about the idea.)
>
> What seem to me to be the two seminal events leading to the ARPANET were:
> 1) The Ann Arbor PI meeting in 67, where Roberts got a lot of pushback for
> the idea of putting them on a network and Wes Clark’s suggestion to put a
> minicomputer in front of each host. Hence the IMPs.
>

Agreed.  And I think it's relevant to note that Moore's Law played a
pivotal role here in the sense that the cost of minicomputers had come down
to the point where paying for a minicomputer for each site was (just
barely) feasible.  Reliability was also crucial.  We all remember that
time-shared systems rarely stayed up longer than several hours before
needing a reboot.

>
> 2) Later that same year, Roberts gave a talk at the Gatlinburg OS
> conference on the ARPA’s network plans. In one of those after the talk
> discussions, i.e., in the bar, there were two major discussions: 1)
> Roger Scantlebury from NPL (along with others) convinced Roberts to use
> packet switching. (Roberts had never heard of it, but later found Baran’s
> report in a stack of documents in his office.) ;-) and 2)     In his paper
> at the conference, Roberts had said they were going to use 2.4Kbps lines
> for the network.  Again Scantlebury convinced Roberts that that was no
> where near fast enough and that they had found that at least 50Kbps was
> needed.
>

Well, Len Kleinrock and Larry Roberts were office mates and worked together
at Lincoln Lab.  Len focused on message switching.  Larry was definitely
aware of the idea, and it played a central role in his thinking.

Re the use of 50Kbps lines, Larry discovered the government could lease
these lines at a special rate, which made it feasible within the budget he
had.

This last one I think doesn’t get enough credit. It is a very small thing,
> but I think was a major contribution to the success of the ARPANET. It
> would have worked at 2.4 or 9.6, but been so glacially slow as to have been
> considered not successful. At 50Kbps, we could do real work that was way
> beyond what people expected. Not to take anything away from the great
> software development that went into the IMPs and the NCPs, etc. I really
> think this gets too little credit for the success.

I agree.  John McCarthy, well known for his AI work but also a prime
supporter of time-sharing, argued against the Arpanet, pushing instead for
dial-up email forwarding service, i.e., the UUNET architecture.  UUNET was
quite successful in its own right, so McCarthy wasn't wrong, but I agree
that the 50Kbps lines in the Arpanet made a big difference.  I would add
that the reliability of the Arpanet was also a major contributor to its
success.  Frank Heart was adamant about it, and Ben Barker has a colorful
story about the lights on the IMP panel being a major source of outages.
The IMPs had a 98% percent uptime at first.  98% was astonishingly good
compared to other machines of the day, but intolerably poor in terms of
providing an always available service.  Ben re-engineered the lights and
brought the reliability up to 99.98%.  How's that for a small thing having
a big effect!

>
>
> (Also I have to admit, I kinda like the idea when small things have a
> major effect.)
>
> > On Aug 16, 2025, at 13:16, John Day via Internet-history <
> internet-history at elists.isoc.org> wrote:
> >
> > The NPL network already existed and had for awhile, a couple of years
> but I will have to go look at sources to be exact.
> >
> > Of course, what this should say is the first messages exchanged on the
> ARPANET.
> >
> > I am sure BBN tested it before they delivered it, but I don’t remember
> now what Hafner says about that.
> >
> > Take care,
> > John
> >
> >> On Aug 16, 2025, at 12:41, Dave Crocker via Internet-history <
> internet-history at elists.isoc.org> wrote:
> >>
> >> My Facebook feed just delivered a tidbit from UCLA that begins:
> >>
> >>  "In 1969, UCLA Professor Leonard Kleinrock directed the transmission
> >>  of the first message between two networked computers..."
> >>
> >> I found myself wondering a bit about that characterization:
> >>
> >> 1. Didn't BBN do some inter-host packet exchanges, when testing the
> >>  IMPs, before shipping them to UCLA and SRI?  Wouldn't that have
> >>  counted as the actual first?
> >> 2. There were other packet research projects, at the time, but I don't
> >>  remember the details of timing of other 'WAN' and 'LAN' project.
> >>  1969 was early enough that it's entirely possible the others were
> >>  later, but I'd be interested in hearing the details.
> >>
> >> I suspect the refinement of the UCLA statement would be:
> >>
> >>  "In 1969, UCLA Professor Leonard Kleinrock directed the transmission
> >>  of the first message between two networked computers
> >>
> >> --
> >> Dave Crocker
> >>
> >> Brandenburg InternetWorking
> >> bbiw.net
> >> bluesky: @dcrocker.bsky.social
> >> mast: @dcrocker at mastodon.social
> >> --
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