Re: capacity v bandwidth

Thanks for asking, Geoff.

On my first day of work at ARPA (as it was then called in 1976), I had to
report to the Pentagon to pick up my DOD building pass. I went into the
River Entrance and the guard told me to take a seat. Not long after, a guy
came out of the bowels of the Pentagon, conferred with the guard who
pointed at me. The man came over to me and said something that I didn't
really hear [you all know I wear hearing aids ...] but assumed it was
something like "good morning" - so I nodded and he escorted me into one of
the corridors. Soon we encountered another guard (Marine, armed) and they
attached another badge. We continued deeper into the Pentagon, I picked up
additional badges on the way until we entered a very big space with a lot
of people with headsets, large displays, even larger displays on the walls.
I said "This looks pretty elaborate for a personnel office." My escort
looked startled, turned purple (no kidding!)

"Aren't you Mr. Smith!!??" he said. "No, I'm Vint Cerf. I'm just here to
pick up my building pass."  My escort fell silent, whipped me around, said
not another word, marched me through the reverse path, shedding badges as
we went. I ended up back in the River Entrance. I had just inadvertently
visited the National Military Command Center. In all the years since,
despite my clearances, I have never returned to the NMCC!

Vint Cerf


On Sun, May 31, 2026 at 12:53 PM the keyboard of geoff goodfellow via
Internet-history <[email protected]> wrote:

> vint, any chance you would be willing to recount to the list what happened
> at the Pentagon on your first day at ARPA in 1976.. in how you mistakingly
> got mistook for someone else in the reception area.. and ended up being
> walked thru multiple levels of guarded "security" checkpoints and ended up
> in the "War Room" (or whatever it was) instead of the HR office (recalling
> that ARPA didn't have an HR office)?
>
> over the years yours truly has retold that story of yours -- that iirc you
> to related to us at a meeting or conference or something -- when people
> have said such-and-such a "security" breach thing was "fake"/"made up" and
> couldn't ever possibly have happened in real life (such as say the security
> breach incident in the 1997 movie "Contact" that resulted in deliberate
> sabotage) where someone "got/slipped through security"
>
> g
>
> On Sun, May 31, 2026 at 9:07 AM vinton cerf via Internet-history <
> [email protected]> wrote:
>
> > Yes, I left Stanford in July or August and started at ARPA in Sept 1976.
> >
> > V
> >
> > On Sun, May 31, 2026, 11:39 Lawrence Stewart via Internet-history <
> > [email protected]> wrote:
> >
> > > … Rummages around for information theory hat.
> > >
> > > I don’t think I am alone in holding that things with digital interfaces
> > > should say “bandwidth” and things with analog interfaces should say
> > > “capacity”.
> > >
> > > The Shannon-Hartley theorem is about the analog part of this.
> > >
> > > In the digital domain, I think almost everyone uses “bandwidth” to talk
> > > about peak available bits-per-second and “capacity” to talk about
> usable
> > > bits-per-second under certain loads, queuing policies, and the like.
> > >
> > > In the above, bandwidth is absolutely misused for digital circuits as
> > > compared to its analog meaning.  Capacity, unfortunately, has two
> > meanings
> > > and they get muddled all the time.
> > >
> > > Language evolves and non of this offends me.
> > >
> > > Regarding Vint at Stanford I arrived there in September 1976, and by
> the
> > > time I was corresponding with Vint about using Ron Crane’s VDH line
> > driver
> > > to get SU-ISL connected to the SUMEX IMP, he was back in Washington I
> > think.
> > >
> > > -L
> > >
> > >
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