UltraSatan clears SD card on Atari power off

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tzok
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UltraSatan clears SD card on Atari power off

Postby tzok » Thu Sep 05, 2019 10:15 am

Like in the topic, whenever I turn off my STe and there is a SD card in the UltraSatan slot, the card is blank. Activity LED turns on on UltraSatan for a few seconds immediately after powering off the Atari, and I know that card is clear at this moment. Afterwards some cards have just 0x00, others have FxFF, but all are completely blank, no garbage, just 0s or Fs. This happens only on the STe. On STfm it works fine. Whats is more interesting, when I powered STe from a Mean-Well power supply it stopped erasing the card (almost - it still happened occasionally, but once for a few power cycles, not every time). The modern power supply has less output capacity, and voltage falls more rapidly after cutting mains power off.

My STe is one of the early units (with a bodged TTL chip), but I have replaced CPU to HC version, and MASK-ROMs to Flash memory.

siriushardware
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Re: UltraSatan clears SD card on Atari power off

Postby siriushardware » Sat Sep 07, 2019 6:08 pm

This sounds a lot like the legendary STe 'bad DMA' chip problem, especially since the UltraSatan works OK with the ST. I note you've already tried changing the CPU to the HC variant which has been found in many cases to be an alternative medicine for this problem.

I don't want to get into any arguments about the rights or wrongs of whether the DMA IC is really responsible for this and if so why, but certainly, if I had a 'good' DMA IC to drop in and try, that would be the next thing I would try before anything else.

If it fixed the problem I would not agonise over why that was, I'd just be happy that it had fixed the problem.

If it didn't fix the problem there will always be someone further down the line who is also having STe hard drive problems and may wish to try a 'good' DMA IC to see if it fixes their problem, so you would have no difficulty selling the chip on if it made no difference in your particular case.

I have an STe and UltraSatan and they work fine together, but my STe has always had the 'normal' CPU and the 'good' DMA IC since new.

tzok
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Re: UltraSatan clears SD card on Atari power off

Postby tzok » Sat Sep 07, 2019 9:15 pm

If I could get a "good DMA" I'd certainly replaced it. But as the card doesn't get corrupted, but completely deleted it doesn't seem to be DMA problem. It only happens after powering off the Atari, never on reset.

I've tried both CMOS (HC) and NMOS CPUs, I've added 4k7 pull-ups to the DMA bus, changed the P100 pull-ups array near the CPU to 1k5, added 33 pF capacitor between XBR and GND under the CPU socket. It changed noting.

I certainly have a bad DMA, as since new this unit was occasionally destroying FAT on diskettes.

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Re: UltraSatan clears SD card on Atari power off

Postby siriushardware » Sun Sep 08, 2019 10:05 am

tzok wrote:If I could get a "good DMA" I'd certainly replaced it.


As I've never needed to obtain one myself I don't know how difficult or easy they are to obtain, so you have my sympathies if you have already tried and failed to obtain one. That would certainly explain why you seem to have tried everything else.

tzok wrote:I certainly have a bad DMA, as since new this unit was occasionally destroying FAT on diskettes.


That sounds like reason enough to try to replace the DMA IC and associated components if at all possible, even if you have to buy another mainboard with one fitted.

tzok
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Re: UltraSatan clears SD card on Atari power off

Postby tzok » Sun Sep 08, 2019 10:15 am

After replacing MC68000 with MC68HC000 I no longer experience any "bad DMA" symptoms. This issue doesn't seem to be directly connected with a "bad DMA". The card is cleared not corrupted, and only at Atari power-off, never on reset or read/write access.

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Re: UltraSatan clears SD card on Atari power off

Postby siriushardware » Sun Sep 08, 2019 10:53 am

Fair enough, good luck, and please post the solution here if you ever resolve it.

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Re: UltraSatan clears SD card on Atari power off

Postby siriushardware » Sun Sep 08, 2019 1:32 pm

Oh, one thing I forgot to ask: Does this problem still occur if you hold down the STe's reset button before, and while, and for a little while after the machine is powering down?

In theory this should suspend all DMA port activity while the power rails are collapsing, so it would be interesting to see if the card still gets wiped even under those conditions.

Second question I forgot to ask: When a card has been wiped in this way, are you able to make it work again by reformatting it, or does the card never work again afterwards?

tzok
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Re: UltraSatan clears SD card on Atari power off

Postby tzok » Sun Sep 08, 2019 3:33 pm

Card works just fine after reformatting. What is even more interesting - I've changed ACSI ID of USatan from 0, 1 to 1, 2 and the card is no longer erased. On ACSI 0, keeping reset button pressed during powering off also helps.

Don't know if it is normal, but I can't boot to TOS 2.06 without a card or with a clean (unformatted) card in USatan - I got 4 bombs.

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Re: UltraSatan clears SD card on Atari power off

Postby tzok » Fri Sep 13, 2019 11:43 am

The ultimate solution of the problem was replacing the ACSI bus buffers (U302 & U307).

Strangely on the old buffers there were no problem with the Megafile 60 nor with the ACSI-CF adapter (both ACSI #0).

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Re: UltraSatan clears SD card on Atari power off

Postby siriushardware » Sun Sep 22, 2019 9:41 am

Tzok, if you still have them to examine, what brand / type were the original buffer ICs and what brand / type did you replace them with?

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Re: UltraSatan clears SD card on Atari power off

Postby siriushardware » Sun Sep 22, 2019 12:40 pm

Another question. Since you changed those buffers, has the STe stopped destroying the FAT on floppies, as you said it did from time to time in post #3 of this thread?

tzok
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Re: UltraSatan clears SD card on Atari power off

Postby tzok » Sun Sep 22, 2019 8:17 pm

My STe stopped destroying FAT on floppies long time ago, after replacing CPU with a HC version and Mask ROMs with Flash.

Original buffers were GD74LS244 (Goldstar) and 74LS245N (Signetics). I have replaced them with HD74LS244P (Hitachi) and SN74LS245NC (Texas Instruments). Both removed ICs test OK on TL866.
Last edited by tzok on Mon Sep 23, 2019 5:01 pm, edited 1 time in total.

siriushardware
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Re: UltraSatan clears SD card on Atari power off

Postby siriushardware » Mon Sep 23, 2019 4:08 pm

tzok wrote:and SN74LS425NC (Texas Instruments)


I assume you meant SN74LS245NC :)

Thanks, it's always useful to have little bits of information like this in the public domain.

tzok
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Re: UltraSatan clears SD card on Atari power off

Postby tzok » Mon Sep 23, 2019 5:02 pm

siriushardware wrote:I assume you meant SN74LS245NC :)
Your assumption was correct ;) I have corrected that.


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