STe - Bad DMA Chip

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tzok
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Re: STe - Bad DMA Chip

Postby tzok » Sat Sep 15, 2018 3:32 pm

I have an STE with a "bad" DMA and a MC68HC000FN16 (it runs @8MHz in the STe) and "We Were @" runs just fine on it. Same on TOS 2.06 ad on TOS 1.62.

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Re: STe - Bad DMA Chip

Postby czietz » Sat Sep 15, 2018 4:25 pm

joska wrote:Edit: We Were @ - another recent trackloader - does not load with an HC installed either. It does run from harddrive (IDE), but it apparently does some crazy stuff because my LCD TV does not like it at all :D


For reference: I (only) tested the harddrive version of "We were @" on the HC CPU. Closure on the other hand was -- of course -- loaded from a (real) floppy disk during my test.

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Re: STe - Bad DMA Chip

Postby joska » Sat Sep 15, 2018 4:31 pm

So atleast two people has successfully tested with a HC CPU . tzok has a "bad" DMA, czietz - which DMA do you have in your STE? I have the "good" DMA.
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Re: STe - Bad DMA Chip

Postby czietz » Sat Sep 15, 2018 4:38 pm

joska wrote:So atleast two people has successfully tested with a HC CPU . tzok has a "bad" DMA, czietz - which DMA do you have in your STE? I have the "good" DMA.


Like tzok, I have the purportedly "bad" DMA in my STE. However, even with the original NMOS CPU I can use my Gigafile with it without any issues. I tried hard to provoke any errors but couldn't, even though my DMA is supposed to be "bad".

Maybe your "good" DMA chip doesn't like the HC CPU? :wink:

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Re: STe - Bad DMA Chip

Postby joska » Sat Sep 15, 2018 4:42 pm

czietz wrote:Like tzok, I have the purportedly "bad" DMA in my STE. However, even with the original NMOS CPU I can use my Gigafile with it without any issues. I tried hard to provoke any errors but couldn't, even though my DMA is supposed to be "bad".


The "bad" DMA only has problems with certain hardware. E.g. original Atari disks almost never gave problems. I guess that's why this bug slipped through the engineers' fingers in the first place.

czietz wrote:Maybe your "good" DMA chip doesn't like the HC CPU? :wink:


Yes, that is possible. Both STE's where closure and We Were fails have the "good" DMA, and (so far) all STE's where these demos works on even with the HC CPU have the "bad" DMA. If this pattern can be confirmed it's bad news for future 68000-based accelerators. But too early to say with only four machines tested.
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Re: STe - Bad DMA Chip

Postby czietz » Sat Sep 15, 2018 4:47 pm

joska wrote:The "bad" DMA only has problems with certain hardware. E.g. original Atari disks almost never gave problems. I guess that's why this bug slipped through the engineers' fingers in the first place.


Yes, but the Gigafile (along with the Ultrasatan) is known to be problematic in some STEs according to Exxos' research. It just goes to show that every machine is slightly different and having a so called "bad" DMA does not automatically mean that you will have problems.

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Re: STe - Bad DMA Chip

Postby tzok » Sat Sep 15, 2018 6:59 pm

For the ones having a Gigafile/UltraSatan - do you have any resident programs / accessories loaded? I've found some of the CPXs cause a system crash when loading certain games/demos.

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Re: STe - Bad DMA Chip

Postby ijor » Sat Sep 15, 2018 7:25 pm

czietz wrote:
joska wrote:Edit: We Were @ - another recent trackloader - does not load with an HC installed either. It does run from harddrive (IDE), but it apparently does some crazy stuff because my LCD TV does not like it at all :D


For reference: I (only) tested the harddrive version of "We were @" on the HC CPU. Closure on the other hand was -- of course -- loaded from a (real) floppy disk during my test.


Somebody is familiar with "We were" internals? Does it have its own floppy loader as Closure?

It is conceivable that the CMOS CPU affects the floppy interface negatively. Not saying that it does, just that it is conceivable. And if it does, this will likely affect only code that doesn't have a good floppy retry logic (again, that seems to be a problem with Closure 1.0). So it might be mostly harmless, and then not noted, on most other cases.

Note that the CMOS CPU, besides better DC characteristics as a direct consequence of being CMOS, it also has better AC specifications because it is much faster. Not sure how this could affect the floppy interface that is completely isolated from the CPU though.

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Re: STe - Bad DMA Chip

Postby troed » Sat Sep 15, 2018 7:36 pm

(joska tested Closure v1.1 and it was the same. That said, my code could still be crappy ;) I hope I also get the error when I put an HC CPU in my "good DMA" STE)

I believe Leonard also has his own floppy DMA code.

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Re: STe - Bad DMA Chip

Postby ijor » Sat Sep 15, 2018 9:20 pm

troed wrote:(joska tested Closure v1.1 and it was the same. That said, my code could still be crappy ;)
...
I believe Leonard also has his own floppy DMA code.


He has, but why you assume his floppy code is as crappy as yours? LOL, just kidding.

Seems the problem is something else anyway. And I have a feeling it won't fail for you when you put a CMOS CPU ...

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Re: STe - Bad DMA Chip

Postby joska » Sun Sep 16, 2018 7:21 pm

joska wrote:Yes, that is possible. Both STE's where closure and We Were fails have the "good" DMA, and (so far) all STE's where these demos works on even with the HC CPU have the "bad" DMA. If this pattern can be confirmed it's bad news for future 68000-based accelerators. But too early to say with only four machines tested.


A third successful test with HC and {closure} has been done, again with an STE with the "bad" DMA. The plan is to replace the DMA with a good one and see what happens.
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