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This article is explained about the direct memory access we have two types of memeory access is their they are 1.direct memeory access 2.memory mapped i/0 Direct Memory Access (DMA) is used by Symbian OS to offload the burden of high bandwidth memory to peripheral data transfers and allow the CPU to perform other tasks. DMA can reduce the interrupt load by a factor of 100 for a given peripheral, saving power and increasing the real-time robustness of that interface.

this article help full to the beginners to the symbian development--Narendrachinni 07:56, 8 September 2009 (UTC)

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narendrachinni

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The article mentioned here simply explains the concept of DMA(Direct Memory Access) for Symbian OS. The author has also explaioned various types of DMA engines.

DMA engines are used for transfering data between local memory and main memory with less CPU overhead. Without DMA, the CPU would have to copy each piece of data from the source to the destination, making it unavailable for other tasks. This situation is aggravated because access to I/O devices over a peripheral bus is generally slower than normal system RAM. With DMA, the CPU gets freed from this overhead and can do useful tasks during data transfer.In the same way, a DMA engine in an ARM processor allows its processing element to issue a data transfer and carries on its own task while the data transfer is being performed.

There are various types for DMA engines which includes Double-buffered DMA engines, Scatter-gather DMA engines, Multi-channel DMA engines etc. Author has explained the importance and working of these types. This article is specially meant for beginners.

--Deepikagohil 15:59, 8 September 2009 (UTC)

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