Logic Analysers

[dwight]

I'm not sure you want to hide glitches. There are times

when you might want to see them.

It is more about knowing when a glitch has meaning and when it doesn't.

Dwight


________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Adrian Graham <witchy at binarydinosaurs.co.uk>
Sent: Friday, February 3, 2017 3:46:32 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Logic Analysers

On 03/02/2017 23:29, "dwight" <dkelvey at hotmail.com> wrote:

> Adrian
>
>  What you see on the other select line is what is called a glitch.
>
> These are not that uncommon during the early part of the address.
>
> What is important is that there are no glitchs when ALE transitions.

Ah, ok, there's a glitch filter that I can apply to each channel, I'll
explore that.

Cheers!



> ________________________________
> From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Adrian Graham
> <witchy at binarydinosaurs.co.uk>
> Sent: Friday, February 3, 2017 2:34:18 PM
> To: General Discussion: On-Topic and Off-Topic Posts
> Subject: Re: Logic Analysers
>
> On 03/02/2017 19:43, "Tony Duell" <ard.p850ug1 at gmail.com> wrote:
>
>> But that's why I said 'about'. I am doing order-of-magnitude calculations,
>> not trying to design a delay line. I would estimate that between adjacent
>> ICs on the same board you'd get a delay measured in 10's or 100's of
>> picoseconds. That sort of order. So a 25MHz logic analyser, with an
>> effective time resolution of 40ns (if that) is not going to show it.
>>
>> There is no way you're going to get delays of 40ns between adjacent
>> ICs on any reasonable PCB.
>
> This is the sort of thing I mean:
>
> http://www.binarydinosaurs.co.uk/STCExecutelA1checking.jpg
>
> Watching the A1 address line (no triggers just sampling 6 points) and a
> pulse appears at ROM4 on the falling edge of the ALE signal but not the
> other 3 ROMs or the LS373 flip-flop that's demultiplexing the AD1 pin of the
> 8085. While I was thinking about the possibility of propagation delay I
> noticed this one:
>
> http://www.binarydinosaurs.co.uk/STCExecutelA1checking2.jpg
>
> Pulse missing from ROM3.
>
> Given the paths on this board aren't massive and resistance is equal between
> all points when measured with a DMM (and all sockets have been replaced,
> traces checked etc) what else could I be looking at?
>
> --
> Adrian/Witchy
> Binary Dinosaurs creator/curator
> Www.binarydinosaurs.co.uk - the UK's biggest private home computer
> collection?
>
>

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