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. Dwight ________________________________ From: cctalk <[email protected]> on behalf of Al Kossow via cctalk <[email protected]> Sent: Wednesday, March 29, 2017 2:35:54 PM To: [email protected] 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. > > http://pdp10.froghouse.org/qsic/pic_24_2.gif > > 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
