exxos blog - random goings on

[exxos]

Thanks to @philbo34 I now have a lifetime supply of soldering iron tips! :thanksyellow: :2k2: :cheers:

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In other news, my new small 6L Ultrasonics cleaner arrived. Hopefully it won't go up in flames like the last one did!!

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[exxos]

Still not had chance to try the new ultrasonic cleaner, mostly I was trying to build up some of the ST/STE536's before doing that.. But got distracted onto testing FPUs and CPUs for the DFB1X.. There's no current orders for any DFB1X, so they can take a back seat for now..

So I've got distracted again into testing the new batch of 4MB STFM RAM upgrades. These ones have been manufactured in the UK. I'm not sure how many of these I will produce because like I said previously, sales of everything is declining anyway, so this may well be the last batch I make of them.

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Finally found my test machine with vintage dust !

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Also got rid of the rubbish lead acid batteries out of my mother's emergency light as the back is only last about two years maximum. So hacked on a better battery which should hopefully last longer !

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[exxos]

I noticed my MMU socket is getting a bit worse for wear these days.. I mean it had like hundreds of insertions by now over the years..

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But this must've been a problem with the sockets anyway.. Atari had support braces on the sockets presumably to stop the bulging on the sides..

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So to get me out of a bit of a fix, I 3-D printed a outer brace.

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I may get some made out of metal that TLC but they are going to cost like £10 each. But maybe worth the investment considering the hammer my sockets get..

[dml]

I've been looking for those metal PLCC braces for some time without any luck. There is a double-cross type like yours shown and a single, diagonal type. The latter keeps the chip pressed in but doesn't help the socket keep its shape...

[exxos]

I've been looking for those metal PLCC braces for some time without any luck. There is a double-cross type like yours shown and a single, diagonal type. The latter keeps the chip pressed in but doesn't help the socket keep its shape...

Yeah, I was just too lazy to put the diagonal one on just to take it off again. :lol: The diagonal one stops the cross brace from springing off by itself as well.

How many do you want because I've got bits and bobs everywhere..

[exxos]

Still testing the 4MB RAM boards! But the end is in sight thankfully !

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[exxos]

Been working on yet another Falcon clock patch because of issues in this thread viewtopic.php?p=130589#p130589

Either has to be noise/ringing related, or timing issue. Though the 100pF cap which improves things actually does both ! :roll:

I did a new version 6 patch but not really sure is worth even producing at this point. Without a machine to actually diagnose issues I am just guessing at the problems :(

V6 has inverting and non-inverting options. Plus a 10ns delay which can skew the SDMA clock in either inverting or non-inverting mode. I also think there is probably too much variation in tolerances and issues across Falcons to use the existing clock traces.

So I would advocate that the FPU gets driven from its own clock (or not at all if a FPU isn't needed). Then a new wire to the DMA much like the Phantom clock patch did. This way it bypasses the whole bad clock trace and fully isolates the SDMA from FPU clock. The SDMA will need the 10K pulldown much like the V3 had as its helps with DC-offset issues across the clock. So basically its a amalgamation of every other clock patch design all rolled into one !

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Like I said previously, it feels like we are just all "dancing around" ground bounces on various parts of the board or something like that. Figuring out issues on Falcons is almost impossible because of the sheer expense and lack of boards I have here. It's not like working on STFMs where I can try on 100 different motherboards !

The version 5 clock patch which had the phase locked loop has been working fine in my Falcon since whenever I created it months ago. But I don't really see the point in that series either because again it only gets tested in my own Falcon machines to accept pretty much anything I throw at it anyway.

I don't know if there were different PCB companies making the same board or not ? Maybe the layer stack order is different on some boards than others causing variations ?

I was asking around if someone could loan me a rev J board as they seem more problematic but its difficult to say if board revisions are a issue or not. The only other option is if someone has a board which simply fails the SDMA related tests, which doesn't work with any other general clock patch out there already, that could be loaned to me to run tests on and compare against my own falcon here.

I would like to get to the bottom of these weird issues once and for all, but without any amount of Falcon motherboards to test and diagnose, I simply don't have a large enough sample set to draw any sort of conclusions.

I mean how can my Falcon work fine with any clock patch I threw at it and yet other people's boards seem to fail miserably.. It makes no sense.. Obviously this has been an issue since day one because there are so many variants of the clock patch out there already. There must be some weird difference between batches of motherboards or revisions, or maybe there are different batch numbers or revisions of the chipsets causing problems. Who the hell knows...

[JezC]

I've not had time (yet) to dig out my Falcon & check what revision it is...might get chance at the weekend maybe?

It's still got the original 'factory' mod on it (not sure if it was done at the factory or not as I had the board swapped by Atari Workshop back in the 90s as the original board was a bit unstable (and I can't remember if it had a clock patch or not...but it shipped with TOS 4.04 so wan't a really early Falcon).
I have a rev 2 clock patch to fit at some point but if you want to borrow it for a while then I can bring it down to CL4.

Just let me know if it's worth trying or not...

[exxos]

I've not had time (yet) to dig out my Falcon & check what revision it is...might get chance at the weekend maybe?

Just let me know if it's worth trying or not...

If it's anything but the D\C rev then it could help. I'd fot the V4 patch and compare the clocks to my board.. But it's probably stuff you could fit and test yourself first.. It it all works then no need to do anything else.

Its only theory that rev J is the issue currently.. Either way, if any board malfunctions with the V4 then it needs investigating why..

[JezC]

I'll check the revision either this afternoon or tonight & try to remember to post an update here...

EDIT:
Got bored while waiting for the work laptop to do a Windoze update (supposed to be at most 20 minuets, and now at the 45 minute mark and counting)...

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So probably not much use? But let me know if it will help to test on a wider range of boards anyway...

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