[Info-vax] Basic AUI and BNC ThinWire Ethernet (was: Re: Synch-On-Green Graphics, Adapters (was: Re: Troubles with using LCD monitor on Vaxstation 3100/38))

[Stephen Hoffman]

On 2016-11-04 22:55:01 +0000, maltboy20 at gmail.com said:

> Another idea, do I need to have a BNC terminator on the network out in 
> order for it to boot up?

To boot up?  No.   Switch to the serial console, if you don't have the 
graphics display working.   See "How can I set up an alternate console 
on a VAXstation" in the old FAQ.   For this case with a misconfigured 
or missing network, you'll get a console "?" diagnostic reported for 
the selected device media access unit (MAU), if the network diagnostics 
are not reporting an appropriate hardware connection.  In VAX consoles 
of that era, the "?" is flag used to indicate a configuration issue or 
other minor problem, and a "??" is a more serious problem.  If you get 
"¿" reported, you either have the wrong console hemisphere selected, or 
you've not connected to a usual network tap but rather to a network 
tapas.   Most systems had 10BASE5 AUI and 10BASE2 BNC ThinWire 
connections, some of the early Alpha systems had BNC ThinWire and 
10BASE-T UTP connections, and some VAX, Alpha and Itanium boxes have 
had other network connections.

> I am trying to test these without a working network.

And you can't test synch-on-green without a way to display it or maybe 
a fancy 'scope, nor an AUI connection without an AUI transceiver and a 
10BASE5 Ethernet connection, nor a 10BASE2 ThinWire network connection 
without a selection of appropriate ThinWire connectors and terminators. 
  Nor can you test a SCSI bus without proper termination, etc.

> Would a transceiver be adequate as a terminator?

10BASE5 Ethernet transceivers are not network terminators.   10BASE5 
does require terminators.   10BASE5 typically requires a network tap — 
most 10BASE5 taps were drilled so-called "vampire taps", back then — 
and a transceiver.

10BASE2 ThinWire networks do not utilize Ethernet transceivers.   
10BASE2 ThinWire does require network terminators, and uses T 
connectors to connect Ethernet stations into what amounts to a 
daisy-chain of coax pieces and parts.

http://labs.hoffmanlabs.com/vmsfaq
https://en.wikipedia.org/wiki/10BASE2
https://en.wikipedia.org/wiki/10BASE5


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