My first 10BASE5 network segment

Paul Koning paulkoning at
Fri Aug 26 09:56:17 CDT 2016

> On Aug 26, 2016, at 10:24 AM, Joseph Zatarski <jzatar2 at> wrote:
> ...
> Yes, the whole reflection thing could get into a bit of a complex
> discussion involving transmission line theory, but I am an electrical
> engineer, so here goes:
> Yes, you need proper termination at either end, or else you get the wrong
> voltages on the line and cause 'collisions' (well, detect collisions
> anyway, though there aren't really any until the first reflection comes
> back from the cable end).

That reminds me of an amusing error in a 1980s trade rag for DEC users ("The DEC Professional").  It discussed how you could mix 10Base5 and 10Base2 hosts by coupling the two size coax cables through an N to BNC adapter.  That's fine so long as you use the 10Base2 limits.  But instead of a barrel adapter, the article had a photo showing a T connector at the transition, with a "terminator" attached to it.  So that network had three terminators: one at each end and one in the middle.  I suspect it didn't work, or at least quite poorly.


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