Setting up a network and sharing internet

[Lennart Sorensen]

On Tue, Aug 23, 2005 at 10:14:41AM -0400, James Knott wrote:
> I have worked on one 10base5 installation.  It was a DECNET connecting
> several VAX 11/780 computers.  That was my first experience with
> ethernet.  However, my first experience with LANs predates that by
> several years (1977).  I used to work on a Collins 8500C system, which
> used TDM loops, instead of packets, to create a local area network.  A
> device that wanted to send data reserverd a time slot and "owned" it,
> until released.  IIRC, the high speed "TDX" loop ran at 8 Mb/s and the
> low speed TDM loop was 2 Mb.  Devices such as the CPU, tape stands, disk
> drives etc., were connected to the TDX loop.  Slower devices, such as
> the printer, card reader and a bunch of PDP-11 computers were connected
> via the TDM loop.  The interface between the two speeds, was a box that
> sat on both the TDX and TDM loops.  The TDM loop used coax, but the TDX
> loop used triaxial (two separate shields) cable.

Hmm, never heard of triaxial.  I have seen twinax used to connect IBM
terminals.  I always thought those looked weird enough (and at close to
an inch thick, they looked expensive to wire).

> In the Collins network that I mentioned above, the connections were
> similar to token ring, in that there were relays, that connected a
> device to the loop.  However, the relays were located under the floor,
> near the equipment, not at a central location.  Adding or dropping a
> device would cause the loop synchronizer to "chirp", while it re-synced.

Lennart Sorensen
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