Cross-talk square-wave?

dwight dkelvey at
Wed Mar 29 19:33:24 CDT 2017

270K is not a transmission line load.

As I recall ribbon cable is around 100-150 ohms

impedance some place.

The signal does look nice and square.

I doubt is is inductive coupling, with that high a

load, I'd say it was capacitive.

inductive coupling requires current flowing.


From: cctalk <cctalk-bounces at> on behalf of Al Kossow via cctalk <cctalk at>
Sent: Wednesday, March 29, 2017 2:35:54 PM
To: cctalk at
Subject: Re: Cross-talk square-wave?

On 3/29/17 2:14 PM, David Bridgham via cctalk wrote:
> And I think this picture is the smoking gun.
> Again, the bottom trace is the CS signal in question and the upper trace
> is now one of the QBUS DAL lines (after the bus transceiver and level
> converter) that's running across the ribbon cable near the CS signal.
> It does appear that induction can make a fairly clean square wave.

simple thing to try is split the ribbon cable between the two signals

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