STe - Bad DMA Chip

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exxos
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Re: STe - Bad DMA Chip

Postby exxos » Tue Sep 24, 2013 10:30 pm

oops, misread what you said , though all my tests were done between the DMA and ACSI port. I have not even gone back to the CPU. Though if you check alanh's thread, he had to place some capacitors on the CPU R/W lines due to noise problems ( I presume) so make of that what you will...

Repairs in notts ? Who was that then ? Seems to be a busy area around staffs of late with Atari activity... Though I been asleep for the past few years ;)

I suspect anyway, as parts go leaky over time, that its not helping the issues anyway. I think the ST was "borderline working" as it left the factory. Age and faster devices being connected are really showing up the design problems..
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Re: STe - Bad DMA Chip

Postby SteveBagley » Tue Sep 24, 2013 11:03 pm

exxos wrote:Repairs in notts ? Who was that then ? Seems to be a busy area around staffs of late with Atari activity... Though I been asleep for the past few years ;)


This was back in the 1990s, C&P Rossiter was the firm IIRC (run out of the guys front room). I've also just got back into the swing of things as my old machines died -- although I did pick up a Falcon and MEGA back in 2007 (and a MegaSTE earlier this year). I suspect all of them will be pressed into service in the next few weeks when I start teaching Computer Architecture :)

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Re: STe - Bad DMA Chip

Postby exxos » Tue Sep 24, 2013 11:19 pm

Sounds like a cool course, was Z80 in my day, and I am not *that* old :lol: 2K ram dev board to play with, nothing but a numeric screen and basic keyboard to enter machine code into ram and run it. was great stuff. Probably forgot most of it!

Always remember a task to count from 0000 to 1111 on a LED 8 bit output port.easy stuff.. kinda.. Then the tutor said now we have to get it to count on the upper 4 bits of the port, not the lower 4 bits... needless to say everyone over thought it and basically couldn't do it! I think one of my programs I actually ran out of ram! :lol: Tutor gave us a hint that we only needed 1 command to do it... "AH...oops" :lol: good days :cheers:
4MB STFM 1.44 FD- VELOCE+ 020 STE - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - various clutter

http://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
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Re: STe - Bad DMA Chip

Postby hedning » Mon Jul 30, 2018 3:00 pm

Oh, damn it. Here I am, wondering why my bad ass and beloved 4mb 2.06 STE always fights with me when playing around with my SatanDisk and my newly bought UltraSatan. Should have checked here first. I must have the bad DMA, right? It says "C025913-38 PH23-030 0A5 25". Picture added:

Image

Now. Is it the bad DMA? 8O

Second: Where do I get a good one?
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Re: STe - Bad DMA Chip

Postby TheNameOfTheGame » Mon Jul 30, 2018 3:08 pm

Yes, that is the "bad" DMA chip. Not sure where to get a good one.

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Re: STe - Bad DMA Chip

Postby mikro » Mon Jul 30, 2018 4:20 pm

It's not the DMA IC's fault but CPU's. Just buy this one: https://www.exxoshost.co.uk/atari/last/storenew/#0092, replace and you'll be fine.

More info here: http://exxoshost.co.uk/atari/last/DMAfi ... htm#LATEST

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Re: STe - Bad DMA Chip

Postby ijor » Mon Jul 30, 2018 6:19 pm

I think it is fair to say that there is some kind of controversy about the whole thing. Changing the CPU to an HCMOS part might fix the problem, but it might not. Similarly, changing the the DMA to a "good" one might solve or not the problem. Ideally, try both.

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Re: STe - Bad DMA Chip

Postby hedning » Mon Jul 30, 2018 6:53 pm

mikro wrote:It's not the DMA IC's fault but CPU's. Just buy this one: https://www.exxoshost.co.uk/atari/last/storenew/#0092, replace and you'll be fine.

More info here: http://exxoshost.co.uk/atari/last/DMAfi ... htm#LATEST


Interesting read! Thanx! Will try the CPU. Thankfully I have Troed in the same town, so I will force him to change the CPU for me so I don't burn down my house. ;)

Will be interesting to se if my random failures on my STE will be solved with the new CPU. I'll keep you posted.
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Re: STe - Bad DMA Chip

Postby hedning » Thu Aug 09, 2018 8:21 pm

I just installed the new CPU, and after reformatting my SD-cards (one could not be used again, btw! :O ) the UltraSatan gets recognized at every boot (that was not the case before), and the hangups in PARCP when copying stuff is gone. Will do some more testing, but it looks good!

I'd go with the CPU theory from now on. :)
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Re: STe - Bad DMA Chip

Postby siriushardware » Thu Aug 09, 2018 9:19 pm

I don't want to rock the boat, but what happens when you combine a 'Good' DMA IC with a 'Good' CMOS CPU? Anyone tried that?

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Re: STe - Bad DMA Chip

Postby ijor » Fri Aug 10, 2018 1:05 pm

siriushardware wrote:I don't want to rock the boat, but what happens when you combine a 'Good' DMA IC with a 'Good' CMOS CPU? Anyone tried that?


Probably somebody tried, possibly without knowing, an probably is not a problem.

It is almost obvious to me that the the DMA problem is caused by a combination of factors. You can't blame just the CPU because otherwise the problem would be present on all the computers. It is also not the "bad" DMA chip alone, because it is known to work without problems in some cases. Actually most STf/ST (pre STE) computers come with that version of the DMA chip. And probably there are other factors as well, including exactly which kind of device you have at the ACSI bus. Sometimes modifying only one of the factors fixes the problem, sometimes it doesn't.

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Re: STe - Bad DMA Chip

Postby hedning » Fri Aug 10, 2018 4:52 pm

What fascinates me is that both my SD-cards from when I ran the old CPU seems completely useless now. New unused SD-cards work fine on the new setup, but the old ones won't work even if I reformat them lowlevel on the PC or do anything else. The STE can't partition them anymore. Seems the old SD-cards were severlely corrupted somehow.
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Re: STe - Bad DMA Chip

Postby siriushardware » Fri Aug 10, 2018 4:54 pm

For the record. my STE has the 'good' DMA IC and standard CPU and has always 'just worked' both with an ICD based HDD unit (before that broke down with a fault on the ICD host adaptor) and with an UltraSatan, which is what I bought to replace it.

Between the two (A special IC produced only for a certain historic model of computer, and a CMOS version of a common microprocessor produced in far greater numbers and used in a wide variety of equipment) I would say that anyone having apparent DMA/HDD problems with an STE should probably try the CMOS CPU first, especially as it is always fitted in a socket - the DMA IC may not be.

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Re: STe - Bad DMA Chip

Postby czietz » Fri Aug 10, 2018 5:22 pm

Also for the record: my STE has the supposedly "bad" DMA IC and an NMOS CPU as well and still works fine with ACSI devices such as the Gigafile. This shows that even that combination is not guaranteed to fail as ijor already mentioned. (I really had hoped it would, because then I could have investigated the problem and maybe could have finally found the root cause.)
Last edited by czietz on Fri Aug 10, 2018 5:23 pm, edited 1 time in total.

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Re: STe - Bad DMA Chip

Postby hedning » Sat Aug 11, 2018 4:51 pm

Still going strong. Copied 1gb files between the SD-carts and from PC-Atari through ParCP without a single problem. My life is so much better now, thanx to Exxos! :D
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