DMA means Direct memory access, its used to get data's from
memory devices.....

U can see that an DMA controller is used to get data's from
floppy disk

DMA-Direct Memory Access.It means microprocessor can access 
datas present in the external memory (can be 
ROM,DRAM,EEPROM,etc) without CPU.

DMA basically used for speed up the data transfer 
using DMA it is possible to get fast data.....

DMA means Direct memory access ''for fast transfer of data 
between I/O devices and Memory devices and does not involve 
the microprocessor''

whn a text file is o/p to a disk drive, we are concerned 
with transferring data from memeory to that drive. yet with 
programmed or interrupt driven I/O approches tht data mst 
be read from memeory into the cpu and then transffered to 
the didk drive . the microproccessor is na 
unnecessary "middleman" in this process with the result 
that the transfer rate is decresed. the dma is approach is 
to turn off the processor and let the disk drive access the 
data file in memeory itself : a sort of direct memory 
access.

for fast tranfering data