[Forum] AmigaOne's *software* DMA | ANN.lu |
Posted on 05-Jul-2004 01:07 GMT by atmel | 24 comments View flat View list |
I would like to know why the AmigaOne has a software-based DMA instead of having a northbridge that has hardware DMA built-in?
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List of all comments to this articleSorted by date, most recent at bottom |
Comment 1 | Anonymous | | 04-Jul-2004 23:15 GMT |
Comment 2 | tinman | | 04-Jul-2004 23:34 GMT |
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AmigaOne's *software* DMA : Comment 3 of 24 | ANN.lu |
Posted by Anonymous on 05-Jul-2004 02:48 GMT | In reply to Comment 2 (tinman): I suppose you've never heard of CachePreDMA/CachePostDMA? hardware DMA cache coherency checking is the x86 way of doing things, the Amiga has always handled cache coherency in the OS. This allows for smoother multitasking, because that way the exact time the brief bus stall that happens when the caches are synchronized, is fully under the control of the OS. Why do you think that even Linux has problems playing video and audio, unless you use "mpeg accelerators" that buffer raw undecoded data and decode it on the video card itself? After all, a 2GHz P4 should be more than capable of decoding mpeg video, yet if you use a card that does not have "mpeg acceleration" (or the drivers don't enable it) still manages to stutter. Those brief stutters are caused by the NB syncing the caches without the knowledge of the OS. |
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