[ih] Fw: Nit-picking an origin story

[Steve Crocker]

Dave,

Each IMP had four "fake hosts."  These were host level processes running
inside the IMP.  They had regular network addresses.  In that sense they
were regular hosts.  (And thus a single IMP could support up to EIGHT
hosts, four fake hosts and four real hosts.). The fake hosts could both
initiate and receive messages.  One was for the TTY that was connected to
the IMP.  Another collected statistics and periodically sent them off to
BBN.  A third was a traffic generator.  You could connect to it, configure
traffic generation, and turn it on.  The fourth was a debugger.  You could
connect to it from any host on the net and use it to examine and modify any
part of memory.  Very elegant, clean and simple design.

However, the demo of logging in to the SRI SDS 940 from the UCLA  Sigma 7
added an important element.  This tested not only the basic end-to-end
processes implemented by the IMP subnet, it also tested the hardware and
software connections to two hosts, each of which was from a separate vendor
and each of which had been programmed by a different team.  ("Team" might
be a slightly grand term to use for Bill Duvall at SRI and Charley Kline at
UCLA, but you get the point.).  Since the fake hosts were virtual
constructs inside the IMPs, I think we're in agreement that the "MISAN"
message, which I'm sure was reassuring and heartwarming at the moment,
didn't rise to the level of being the first message sent [between real
hosts] over the Arpanet.

Steve


On Sat, Aug 16, 2025 at 3:46 PM Dave Crocker via Internet-history <
internet-history at elists.isoc.org> wrote:

> On 8/16/2025 12:06 PM, Alexander McKenzie via Internet-history wrote:
> > TTY Fake Host at UCLA
>
> Apologies but I don't know the details of 'fake host'.  Was this a
> virtual construct inside the IMP or a special device attached to it?
>
> If the latter, then I'd think that -- for the purposes of historical
> milestones -- it qualifies as sufficient to demonstrate end to end, long
> haul networking.
>
> d/
>
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> Dave Crocker
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