exxos's Atari, Amiga & retro forum

Icky wrote: 21 Sep 2018 16:36 I think there might be a problem with CS line (possibly my soldering - I never rule out my soldering as the first issue) as E on ACIA is ok but CS is floating around 200mV on both ACIAs.

This is the route if it helps..

exxos wrote: 21 Sep 2018 16:42 This is the route if it helps..

These diagrams help a lot in tracing. Thanks

Icky wrote: 21 Sep 2018 16:36 I think there might be a problem with CS line (possibly my soldering - I never rule out my soldering as the first issue) as E on ACIA is ok but CS is floating around 200mV on both ACIAs.

Am going to check it out and see if I find anything.

CS line is intact and not shorted all the way from the GLUE to the ACIA - chip pin to chip pin.

The scope output below is PINK = VPA - measured directly on CPU pin, BLUE = CS and YELLOW = E - measured at ACIA

What I find odd is that the VPA and CS are 500mV

Icky wrote: 21 Sep 2018 17:31 What I find odd is that the VPA and CS are 500mV

Thats switching noise.. I wouldn't pay to much attention to it right now... Put your scope on 5V/div like the E clock...

Because the machine crashes, it many only pulse VPA once, so you might have to setup a trigger on your scope to trigger on VPA pulse..

exxos wrote: 21 Sep 2018 17:55

Icky wrote: 21 Sep 2018 17:31 What I find odd is that the VPA and CS are 500mV

Thats switching noise.. I wouldn't pay to much attention to it right now... Put your scope on 5V/div like the E clock...

Because the machine crashes, it many only pulse VPA once, so you might have to setup a trigger on your scope to trigger on VPA pulse..

Thanks - this is a new scope to me and I am finding out all the functions. I really appreciate your help as my electronics skills are very rusty and knowledge from 25+ years ago is just starting to come back to life.

Icky wrote: 21 Sep 2018 18:05 Thanks - this is a new scope to me and I am finding out all the functions. I really appreciate your help as my electronics skills are very rusty and knowledge from 25+ years ago is just starting to come back to life.

What I mostly do is just put the scope on 2 second time, START after you turn on the ST, then it should capture the VPA,VMA pulsing (likely only once) etc... you might have to reset a few times to capture it.. but its good for a first indication if the signals are switching at all or not.

Triggering on yours scope you can see the exact timings of it all, but if signals are switching.. I assume its all running fine...

Added 16MHZ OPTIONAL FIX - https://www.exxosforum.co.uk/forum/viewt ... =30#p10361

No change

Just thought I would share what the board looks like when booting with the diagnostic cart.

Showing the E7 Spurious Interrupt message and a few graphical glitches

Morning icky,

Mine is the same except for the random characters, just a plain red background. I wonder if this time if the Ram is making the difference between our two attempts.

Will post a photo shortly of mine with the marpet fitted.

Forgottenmyname wrote: 22 Sep 2018 09:32 Morning icky,

Mine is the same except for the random characters, just a plain red background. I wonder if this time if the Ram is making the difference between our two attempts.

Will post a photo shortly of mine with the marpet fitted.

Yes - its good that we have two boards (as Exxos has stated in your thread) at the same stage as this means its not now soldering etc.

As you mention we are using different ram solutions, which I think is helpful as we may uncover things quicker if one of the boards starts to deviate from the other. I too am wondering if the ram difference is contributing to my graphical weirdness.