Re: DMA modes

[Ivor Bowden <ivor@peritek.com>]

Here are a few descriptions as I understand them:

At 03:51 PM 6/23/00 -0400, you wrote:
>Hello all,
>
>Can anyone define these DMA modes for me, or point me to where I can
>learn about them.
>
>  Chaining

Chaining is when the DMA instructions are themselves DMA'd from
memory and at the end of the instruction list is the instruction
and address of the next list (which could be the same as the first).

>  Demand Mode
>  Block Mode

Block Mode is when the DMA controller arbitrates once and then
grabs the bus to transfer a block of data, instead of arbitrating
for each transfer.

>  Fly By

Fly By is when the DMA controller just generate the addresses and
bus signals, the data goes directly from the source to the destination
without passing through the controller.

>  Scatter Gather


>Thank you in advance,
>
>Jeff
>
>
>
>