Computer ArchitectureComputer ScienceNetwork DMA represents Direct Memory Access. It is a hardware-controlled data transfer method. An external device can control data transfer. The external device creates address and control signals that are needed to control data transfer. External devices also enable peripheral devices to directly access memory. The external device which controls the data transfer is known as the DMA controller. There are three different modes of DMA data transfer which are as follows −
By frequently obtaining and free control of the system buses, the DMA controller substantially interleaves instructions and data transfers. The CPU processes an instruction, then the DMA controller sends a data value, thus the CPU processes another instruction, then the DMA controller sends another data value, etc.
The benefit of transparent mode is that the CPU never stops implementing its programs. The DMA transfer is complementary in terms of time. The hardware requires to decide when the CPU is not utilizing the buses can be fully complex and relatively costly. In addition, more advanced CPUs overlap their internal services and use the system but virtually every cycle.
Published on 27-Jul-2021 08:52:49
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