Function of DMA controller

Function of DMA controller

  

The Direct Memory Access (DMA) controller allows I/O devices to transfer data directly to and from memory. This frees the system microprocessor of I/= tasks, resulting in a higher throughput.The functions of the DMA controller can be grouped into two categories: program mode and DMA transfer mode. The DMA controller supports the following:

    * Register an program compatibility with the IBM Personal Computer AT DMA channels                          (8237 compatible mode)

          * 16MB 24-bit address capability for memory and 64Kb 16-bit address capability for I/O

        * Eight (AT only 4?) independent DMA channels capable of transferring data between memory and I/O devices

DMA Controller Operations

The DMA controller does two types of operations:

          * Data transfer between memory and I/O devices

          * Read verifications