Logic Analysers

Adrian Graham witchy at binarydinosaurs.co.uk
Wed Feb 1 17:18:43 CST 2017

Evening folks,

I have two so-called Logic Analysers, both cheap Chinese clones of other
more expensive units that hook up to the host via USB2 and stream readings
direct to software, in one case the open source Sigrok and in the other
genuine Saleae Logic.

I'm getting different and inconsistent readings out of both of them whilst
sampling at 25MHz which should be more than enough for this 6MHz Executel
I'm working on. Both of them are good for spotting dead or stuck outputs but
I still can't get a good set of readings from eg all points on a single
address line. Tonight I replaced all four ROM sockets and ROM chips, tested
each individual line for resistance (0.5 ohms on all apart from an
occasional 0.4 and 0.6) but still get ghost readings.

Is it me or the cheap clones?

Whilst looking for better quality units I came across a couple of 'proper'
HP/Agilent analysers, a 1663A 34 channel and 1661A 102 channel which seem
complete apart from the chip leg grabbers. Am I right to assume some of you
might have experience of these beasts?

Forums seem to mostly think the streaming USB units aren't worth anything
for more than a few channels but I'm still a relative beginner to all of
this. I really need to watch all 16 lines of an address bus and externally
clock it as Tony has suggested.

Any insights appreciated!

Binary Dinosaurs creator/curator
Www.binarydinosaurs.co.uk - the UK's biggest private home computer

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