SOLUTION

• In SCSI bus transfers, the processor is not aware of the data being transferred.
• The SCSI controller sends an interrupt to the processor to inform it that the requested operation has been completed.
• This scenario shows that the messages exchanged over the SCSI bus are at a higher level than those exchanged over the processor bus.
• In this context, a “higher level” means that the messages refer to operations that may require several steps to complete, depending on the device.
• Neither the processor nor the SCSI controller needs to be aware of the details of the operation of the particular device involved in a data transfer.
• In the preceding example, the processor need not be involved in the disk seek operations.