Why are the read and write control lines in a DMA controller bi-directional?

The read and write control lines in a DMA (Direct Memory Access) controller are bi-directional because they need to facilitate communication in both directions between the DMA controller and the memory or peripheral devices. When the DMA controller is transferring data from memory to a device, it uses the read line, while the write line is used when transferring data from the device to memory. This bi-directional capability allows the DMA to efficiently manage data transfers without needing to constantly request CPU intervention, thereby improving overall system performance.