That's good/clear example about dma,... in other words, dma requies a piece of hardware makes it happens as the word "dma" explain itself. The added hardware's just a statemachine, or people call it the dma engine, this can be done with cpld, fpga, or another dedicated uC,...now go back to original post, wonder if he want the 8051 working this way? if so i think it's doable...