Cyber ECL Wiring

Chuck Guzis cclist at
Fri Nov 28 00:59:20 CST 2014

On 11/27/2014 10:35 PM, Billy Pettit wrote:

> You are correct.  Eric, have you seen a Cyber 170 chassis?  There is
> no back plane.  Every signal uses twisted pair wire wrap from module
> to module.  It was horrible to build, wire mats inches thick.  We
> used to allow field engineers 10 minutes per signal line for
> engineering change orders.
> Provided, the line did not need to be tuned.  Tuning was done by
> changing wire length.  It was not elegant by later standards but was
> very very fast for the era. One of the downsides to using
> differential wiring throughout the system was the manufacturing time
> measured in months.  Of course, they sold for millions or tens of
> millions of dollars so it was worth this approach.

It didn't start with the 170, did it Billy?  I remember a nice thick mat 
of twisted-pair wires on the backplanes of 6000s, as well as in a lot of 
attached controllers.  Taper pin technology.

A co-worker of mine had, as his first job fresh from UofM, measuring all 
of the loops to which  Seymour had attached tags that said "Tune".


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