Long description

Part (a): There are three devices connected to the bus: C P U, Interrupt controller, and Disk Controller. Another fourth device Disk Drive is connected to Disk Controller. There is a forward arrow numbered 1 from C P U to the Disk controller. There are three backward arrows: One from Disk Controller to Interrupt controller numbered 2. Second and third, from Interrupt controller to C P U numbered 3 and 4. Part (b): There is a vertical rectangular block labeled Interrupt handler with five partitions. The first partition from the top is empty. The second partition is labeled Current instruction. The third partition is labeled Next instruction. The fourth partition is empty. The fifth partition is labeled 2. Dispatch to the handler and highlighted. In the fifth partition, there is a small rectangle with one vertical partition is formed at the lower right end of the partition. An arrow labeled 1. Interrupt from Current instruction points to 2. Dispatch to handler. An arrow from 2. Dispatch to handler points to the interrupt handler. An arrow labeled 3. Return from the interrupt handler points to the third partition Next instruction.