32 and 64 bit wide DMA channels

According to Wikipedia, the DMA channels 0, 1, 2 and 3 with 8-bit and DMA channels 4, 5, 6 and 7 with only 16 bits.

But why so little?
What's with 32 and 64 bit wide channels?

With a 64-bit wide DMA channel, there can be much more data in the same period in the memory slide.

But where is DMA still used today?

It is used for example when hard drives, even the video card uses it.

Quote:

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Originally Posted by Devasis

With a 64-bit wide DMA channel, there can be much more data in the same period in the memory slide.

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The memory is certainly as fast, but it remains to ask whether the secondary memory is so fast that it is observed :wink:

So far nothing would broaden to 64-bit, since the source of the data is not as fast that can deliver.

The classic DMA channels with external DMA controller, but is no longer used.

Aufm PCI bus for example, calls itself the whole bus mastering and works differently.

So as I understand it, is the DMA, with these DMA channels has a completely different technology than the DMA when Ultra DMA. I remember how I felt UDMA hard drive and I had wondered then that nothing in the occupancy of DMA channels appeared. A buddy gave me an explanation that both are nothing to do.

DMA is direct memory access. Depending on the context, but the memory of a completely different type, generally thought as the memory. UDMA one may think same as DMA but it provides direct access to the disk, which are 2 totally different things.