Answer - 1. Direct memory access is used to enhance the speed of the input output systems. 2. Here, buffers, counters and pointers are set for the devices. 3. The device controller transfers the block of data directly from own buffer storage to memory. 4. The data is not given to the CPU for further transfer between CPU and input output devices or CPU and memory. 5. Only one interrupt is generated per block than one interrupt per byte which enhances the speed.