UNIBUS extension card/cable sets

Paul Koning paulkoning at comcast.net
Thu Jun 25 12:38:25 CDT 2015

> On Jun 25, 2015, at 1:02 PM, Noel Chiappa <jnc at mercury.lcs.mit.edu> wrote:
>> From: tony duell
> ...
>>> I was wondering if maybe the M9015 was an M9014 with termination
>>> resistors, or something (the way the QBUS versions come with and with
>>> termination)
>> I would be very surprised. Unibus is normally terminated at the ends
>> and not in the middle.
> Right, but the very similar QBUS does have terminations (of a sort - the
> rules for when you need terminations on QBUS extensions are so complex that I
> don't really grok them yet) 'in the middle', so…

That doesn’t seem likely.  While DEC engineers on average didn’t understand transmission lines as well as, say, Cray engineers, the definition of “termination” is something that you learn in EE 101 and are unlikely to forget.


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