The 8051 microcontroller from Intel and most other derivatives from other manufacturers has no provisions to implement DMA. As such if you want to make an external DMA controller work you have to install buffers between the memory bus interface of the microcontroller and the memory. Then external logic would have to be implemented to produce the DMA controller functionality.

In my honest opinion, DMA is just not feasible with an 8051 type microcontroller. You will find you will generally be better off to just write some software memory block move routines to copy areas of memory from one region to another.

The use of DMA is also most often applicable to applications where large blocks of data must be moved around at high speed. The 64K byte limit of memory size is anything but large by any measure used today for memory size.

Michael Karas