27 Nov
2014
27 Nov
'14
10:59 p.m.
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".
--Chuck