What is Direct Memory Access? Explain the working of DMA. What are the different kinds of DMA transfers?
Interrupt driven I/O transfer rate is limited by the speed with which the processor can test and service a device. No. of instructions are involved while the processor is tied up in managing an I/O transfer. However, Direct Memory Access (DMA) allows CPU to grants I/O module to read from or write to memory without involvement. when large volumes of data are to be moved, a more efficient technique is required: Direct memory access. The DMA function can be performed by a separate module on the system bus, or it can be incorporated into an I/O module. A DMA module exchange the data between main memory and an I/O module. The processor sends a request for the transfer of a block of data to the DMA module and is interrupted only after the entire block has been transferred.