3. Interrupt Sequence and Interrupt Handling (20 points) a. Describe an advantage of using interrupts over polling. (3 points) b. Assume an interrupt occurs on Port J, pin 7. Describe the sequence of steps that occurs on an HCS12 to initiate execution of the ISR once a valid IRQ on port ) pin 7 is signaled (7 points)? c. Assume an interrupt occurs on Port ), pin 7. Describe the sequence of steps that allows the HCS12 to return from the ISR to the main program with global interrupts enabled. (7 points) d. Describe why global interrupts should not be enabled in an ISR. (3 points)