In this configuration the I/O modules are connected to the DMA through another I/O bus. In this case the DMA module is reduced to one.
Transfer of data between I/O module and DMA module is carried out through this I/O bus. In this transfer, system bus is not in use and so it is not needed to suspend the processor.
There is another transfer phase between DMA module and memory. In this time system bus is needed for transfer and processor will be suspended for one bus cycle. The configuration is shown in the Figure 6.13.

                                 

                                  Figure 6.13: Seperate I/O bus for DMA transfer