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SB Live DOS emulation - my fight with SERR# to NMI routing (Developers)

posted by RayeR Homepage, CZ, 19.05.2008, 14:44

> There might be different models for which they implemented different
> approaches. The NMI approach has severe limitations, so they might have
> changed their strategy. Anyways, IIRC I once verified that the DOS drivers
> for my SB Live don't touch the NMI vector in the IDT, which is a pretty
> good evidence that NMI is not used.
This experimets was done on the first version of SB Live 1024 with 4-channel output. I have 2 version of drivers. One that came on original CD made just for Live and latest drivers which are compatible with up to Audigy2. I don't know version numbers now (I can look later). Both drivers don't work without SERR#->NMI enabled. I also have Audigy2 in other PC. I tried it some months ago but behave same as Live.

> I mean hardware, since the legacy DMA controller is known and documented.
ICH7 DMA is also documented in intel datasheet. I hoped they would keep this peripherals compatible as possible. So I would need compare it. There's a lot of internal config registers. And one badly set (unset) bit may corrupt it all because of BIOS writers was lazy to mess with this things. Or maybe there's something missing in HW I don't know...

> But if the FDC and/or DMA is "non-standard" in your MB, wouldn't that mean
> that you'll need a driver to run - say - Win98 on it? I'm not sure, but I
> bet the FDC in Win98 is accessed by protected-mode drivers supplied with
> the OS, and not by BIOS interrupts.
Just note that under W98 it behaves same as under DOS (only MIDI, Adlib).
I don't need any drivers for floppy it works normal under all OSes. But I don't know if it use DMA in all cases or if there's something like PIO mode for HDDs which will then run without DMA but with higher CPU load. I only can say that when using FD under W98 system respose become slow but under WXP it doesn't.
Is there some program that can probe if DMA is working under DOS? I just tried SBEGO and PCDR diagnostic and it didn't reported problems but i don't know how did it test it.

Maybe this problem is releated to that ICH6 and later doesn't support some signals for PCI2ISA bridge needed for working ISA DMA. This signals are not needed here but maybe something else was ommited...

---
DOS gives me freedom to unlimited HW access.

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