Which memory upgrade is this?

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NicolasTwoK
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Re: Which memory upgrade is this?

Post by NicolasTwoK »

I think it's just fine at the moment. If the socket ever starts to bulge, I could 3D print a tight fitting brace to put over it and keep everything in shape.

So I'll leave it alone for the moment and focus on removing the RAM expansion.
elliot
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Re: Which memory upgrade is this?

Post by elliot »

Why do you want to take it out?

I know there are a few older software releases that do not like >1mb but I think the benefits of having 4mb far outways having 1mb. For example MultiTasking, Sound sampling, etc. There is even software that will fool the mem size routines which does help a couple of bits of naughty software to work.

I know the top RAM is not working right but that looks to be a simple swap no?
Falcon with CT60 in rack mountable case. Two STFMs, one upgraded lots. My original STE from when I was a teen with Switchable TOS, 1.44Mb drive, 4MB RAM, Supra Hard Drive and very very yellow case. Mega STE with (currently none working) Crazy Dots 2. Atari 2600 and a Jag. And a mountain of commercial software and lots of hardware addons.
NicolasTwoK
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Re: Which memory upgrade is this?

Post by NicolasTwoK »

I dont' know exactly where the error is so it might take quite some swapping before it's solved, and looking at Ebay prices for those memory chips (15 per piece, or a lot less but loads of shipping from the US) I don't feel like experimenting with it, taking my limited level of knowledge into account. Also I'm not good at unsoldering IC's. My unsoldering skills tend to stop at two legged components with a good grip. I will remove the expansion in a reversible way so I can try to fix it if I ever feel like it, but at this moment it's just not a good idea for me.
elliot
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Re: Which memory upgrade is this?

Post by elliot »

That is fair.

I am no expert (as most here will tell you) but those chips don't look like any memory I have seen before (maybe 386 cache). I am not pushing my point, just interested but I wonder if they could (all) be replaced with something cheaper/easier (maybe a single chip)! All that will be there is address and data lines with a power/ground and sync or something.
Falcon with CT60 in rack mountable case. Two STFMs, one upgraded lots. My original STE from when I was a teen with Switchable TOS, 1.44Mb drive, 4MB RAM, Supra Hard Drive and very very yellow case. Mega STE with (currently none working) Crazy Dots 2. Atari 2600 and a Jag. And a mountain of commercial software and lots of hardware addons.
NicolasTwoK
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Re: Which memory upgrade is this?

Post by NicolasTwoK »

I've seen experiments with more common RAM bars that used similar connections to the main board on first sight, so likely you could brew something like that. More than likely that would go way beyond my level to get to work by myself without any very concrete installation guide from someone else who has done the hard work already.

When dismantling the expansion, I'll keep future reuse in mind so I'll leave as much as possible there. Certainly the two side headers can remain fully intact. Most of the central header as well.
NicolasTwoK
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Re: Which memory upgrade is this?

Post by NicolasTwoK »

My gift for today: the Catch Computer CCMB4 expasion fully documented!
CraftComputer CCMB4.jpg
Up next: undoing all this in my STFM. :-)
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siriushardware
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Re: Which memory upgrade is this?

Post by siriushardware »

Thanks for doing that, it's really appreciated especially when I am sure you would rather just be getting on with the process of removing the expansion.

I have a couple of questions for clarification:

Are the details regarding main connector pin 77 / U56 pin 64(?) "via back of main PCB" and the little drawing of U56 underside all part of the same information about where main connector pin 77 goes to?

What is the meaning of the 'N' and 'S' suffixes on some of the labels, for example R61.N and R61.S? These would seem to indicate one end or the other end of R61 or its pads, but which end is which?
NicolasTwoK
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Re: Which memory upgrade is this?

Post by NicolasTwoK »

That is pin 11, not 77.

The detail is the backside of u56, refering to that pin 11 connection. I made a drawing because I'm not sure how the pins are counted from 61 up. There is a wire that goes from expansion connector pin 11 to the underside of the motherboard to u56.

N and s are north and south. With the atari in front of you, north is the psu side and south the keyboard side.
siriushardware
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Re: Which memory upgrade is this?

Post by siriushardware »

That is pin 11, not 77.
Are you sure? Having examined the sketch more carefully I now see that what I first thought was '77' is actually '17', not 11. Sorry for the initial mis-read though, it was never really going to be pin 77.

Thanks for the explanation of N,S. - I thought that might be it, but it would be useful to have that stated on the sketch for the avoidance of doubt.
NicolasTwoK
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Re: Which memory upgrade is this?

Post by NicolasTwoK »

Yes, it should be pin 17.

N and S are explained in written text on the right hand side of the paper.
siriushardware
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Re: Which memory upgrade is this?

Post by siriushardware »

I see that now, thanks. Good luck with the de-installation.
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1st1
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Re: Which memory upgrade is this?

Post by 1st1 »

If you install such memory extensionm in any ST please make sure that there is a massive ground connection between ST board and memory board. This solves a lot of mostly randomly placed memory errors.
Power without the Price. It's not a bug. It's a feature. _/|\_ATARI

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NicolasTwoK
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Re: Which memory upgrade is this?

Post by NicolasTwoK »

Mine has two fat ground wires to the peripheral ground of the main board, so no gains to be found there.
NicolasTwoK
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Re: Which memory upgrade is this?

Post by NicolasTwoK »

I've removed the expansion and replaced the resistors.

The STFM isn't working correctly now. In GEM, it doesn't show the top row menu items text. They are there, you just can't see them. Also browsing in detail list doesn't show the text until you select a file. Most programs/games don't load well. Stunt Car Racer on the other hand runs perfectly.

My guess is that the expansion wasn't necessarily sheduled beyond the original 1MB of RAM. So the fault might have been in the original RAM all along but it worked as 3+1MB instead of 1+3MB.

Unless anyone has a magical solution, I think that's the end of this particular STFM for me. I'll keep the STF that runs Cubase, but let go of the troubled STFM, the RAM expansion, and an untested ST520+.
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