On 02/03/2017 02:55 AM, Adrian Graham wrote:
Ah yes, sorry, I'm aware of that. What I meant in this
specific case is that with 4 2764s right next to each
other with a direct signal path between adjacent address
and data pins that has a resistance of 0.5 ohms pin to pin
surely I should be able to put a clip on each (for
example) A4 address line and see the same pulse at all
four channels?
Well, if the two logic analyzers were synched together, or
you were sampling at 100 MHz or above, then yes.
But, if the logic analyzers are running too slow, sampling
irregularly (I have no trust in Chinese gizmos until PROVEN
that they do it right) you could get very different
results. Is there a clock on the microprocessor that you
can check? Maybe something like a baud rate clock or
something that is at a few MHz. See if that shows up as
totally regular square waves. If not, then the LA may not
be sampling at a regular rate, or might have gaps while
sending data to the PC. I'm just suspicious of these units,
given the results you report.
(On my $130,000 Tektronix analyzer, I don't have to worry
about such stupid stuff, I know they got it right. I paid
less than $750 for it, it will do 100 MHz on 288
synchronized channels, with a 128K record length. But, it
is bigger than a big kitchen microwave, and much noisier, too.)
Jon
