In microprocessor based systems DMA facility is required to increase the speed of data transfer between the:

1. Direct memory access (DMA) is a feature of computer systems that allows certain hardware subsystems to access main system memory (random-access memory), independent of the central processing unit (CPU).

2. DMA avoids using the CPU thus allowing the CPU to attend another job

3. It increases the speed of the data transfer between the memory and the I/O devices

4. DMA is used when a large amount of data is to be printed out from the memory of a computer

5. The problem of slow data transfer between input-output port and memory or between two memory is avoided by implementing the Direct Memory Access (DMA) technique

6. It is implemented by using an 8257 DMA controller