command reordering in the hub - interface unit of enhanced direct memory access functions is described . without command reordering in the edma , commands are issued by the hiu to the peripheral in order of issue . if the higher priority transfers are issued later by the edma , the previously issued lower priority transfers would block the higher priority transfers . command reordering in the hiu causes transfers to be reordered and issued to the peripheral based on their priority . reordering allows the edma and hiu is to give due service to high priority transfer requests with decreased weight placed on the order in which the requests were issued .