stfm problem

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thecaver99
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stfm problem

Post by thecaver99 » Tue Sep 01, 2020 7:29 pm

Hi all

I have got my hands on an stfm with a problem
I have added 2 pics one of the screen and one of the board
so its switched on and tuned in and I get vertical coloured lines on the screen thats all.

20200901_192610.jpg
20200901_192610.jpg (393.25 KiB) Viewed 636 times
20200901_192602.jpg
20200901_192602.jpg (253.59 KiB) Viewed 636 times

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JezC
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Re: stfm problem

Post by JezC » Tue Sep 01, 2020 7:49 pm

I'm not sure but that looks like a ram fault.

Can you try a diagnostic cart/ROM image with a serial connection to a PC (or another working ST) as that might help pinpoint the problems.

thecaver99
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Re: stfm problem

Post by thecaver99 » Tue Sep 01, 2020 8:16 pm

i have ordered some boards to build a diag cart, but you have intrigued me is there a diag image for the 6 rom boards like this one as i would burn them and fit as that would make it a lot faster for me

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JezC
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Re: stfm problem

Post by JezC » Tue Sep 01, 2020 9:30 pm

Yes, I took the image from Terriblefire's GitHub repo & put that into a pair of 27C512 EPROMS & replaced a 2 chip TOS set with those to diagnose a few systems.

I've not yet split that into multiple 27C256 images for a 6 ROM system but it would be pretty simple to do so.

I'm away on work for a couple of days otherwise I would send you the images from the 27C512 devices...but if you can wait a few days I can send the image files before the weekend.

I want to make a cart version too...but have not had the chance or money to buy the bits so far.

If you can't find the posts about his image let me know... more difficult to search & link on my phone, so I can do that when I get home too.

Edit: There's a topic for DiagROM for ST under Terriblefire's section with a link to his GitHub repo.

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Smonson
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Re: stfm problem

Post by Smonson » Wed Sep 02, 2020 12:19 am

What's interesting to me is that
  • There seems to be a palette in the shifter, which would suggest that it's at least running the first bit of code from ROM
  • The pattern isn't repeating every 16 pixels, but every 80 pixels. That's interesting because it's not a power of 2
I'd also check the MMU is seated properly.

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rubber_jonnie
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Re: stfm problem

Post by rubber_jonnie » Wed Sep 02, 2020 9:19 am

Looks like a RAM fault, but I would suggest you need to use a diag cart with the Atari diagnostics tools connected to a PC with Terminal software over a null modem cable so you can see the output. Exxos does have them in stock.

I personally haven't tried the diagrom route as I prefer a cartridge that is easily moved between machines without the need for opening up, but ultimately it's your own personal preference.

As Smonson said, I agree that code is starting to run from the ROM, so aside from RAM, which you'll need some sort of diagnostics tool to test.

I would also suggest a reseat of the MMU, and perhaps tweak the MMU sockest at the same time: viewtopic.php?f=17&t=1484&hilit=plcc

If you have a multimeter, then you may want to check the data lines between the CPU and the MMU for continuity too.
Collector of old Atari things:
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Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
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thecaver99
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Joined: Tue Sep 01, 2020 7:18 pm

Re: stfm problem

Post by thecaver99 » Thu Sep 03, 2020 5:44 pm

i have reseated the mmu and swapped out the glue to no effect, im awaiting 5 boards to butild a diag cart, i have the eproms ready.

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