What is the function of DMA address register?

Every DMA channel has one DMA address register. The function of this register is to keep the address of the starting memory location, which will be accessed by the DMA channel. Therefore the starting address of the memory block that will be accessed by the device is first loaded in the DMA address register of the channel. Naturally, the device that requires transferring data over a DMA channel, will access the block of memory with the initializing address stored in the DMA Address Register.