Communication between a disk and the main memory is done through DMA. The following information must be exchanged between the processor and the disk controller in order to specify a transfer.
Main memory address :
The address of the first main memory location of the block of words involved in the transfer.
Disk address :
The location of the sector containing the beginning of the the desired block of words.
Word count :
The number of words in the block to be transferred.
The disk address format is:
