QUESTIONS AND PROBLEMS
1. What is interrupted by an interrupt?
2. Define the term interrupt.
3. What is called by an interrupt?
4. Why do interrupts free up time for the microprocessor?
5. List the interrupt pins found on the microprocessor.
6. List the five interrupt instructions for the microprocessor.
7. What is an interrupt vector?
8. Where are the interrupt vectors located in the microprocessor’s memory?
9. How many different interrupt vectors are found in the interrupt vector table?
10. Which interrupt vectors are reserved by Intel?
11. Explain how a type 0 interrupt occurs.
12. Where is the interrupt descriptor table located for protected mode operation?
13. Each protected mode interrupt descriptor contains what information?
14. Describe the differences between a protected and real mode interrupt.
15. Describe the operation of the BOUND instruction.
16. Describe the operation of the INTO instruction.
17. What memory locations contain the vector for an INT 44H instruction?
18. Explain the operation of the IRET instruction.
19. Where is the IRETQ instruction used?
20. What is the purpose of interrupt vector type number 7?
21. List the events that occur when an interrupt becomes active.
22. Explain the purpose of the interrupt flag (IF).
23. Explain the purpose of the trap flag (TF).
24. How is IF cleared and set?
25. How is TF cleared and set?
26. The NMI interrupt input automatically vectors through which vector type number?
27. Does the INTA signal activate for the NMI pin?
28. The INTR input is -sensitive.
29. The NMI input is -sensitive.
30. When the INTA signal becomes a logic 0, it indicates that the microprocessor is waiting for an interrupt number to be placed on the data bus (D0–D7).
31. What is an FIFO?
32. Develop a circuit that places interrupt type number CCH on the data bus in response to the INTR input.
33. Develop a circuit that places interrupt type number 86H on the data bus in response to the INTR input.
34. Explain why pull-up resistors on D0–D7 cause the microprocessor to respond with interrupt vector type number FFH for the INTA pulse.
35. What is a daisy-chain?
36. Why must interrupting devices be polled in a daisy-chained interrupt system?
37. What is the 8259A?
38. How many 8259As are required to have 64 interrupt inputs?
39. What is the purpose of the IR0–IR7 pins on the 8259A?
40. When are the CAS2–CAS0 pins used on the 8259A?
41. Where is a slave INT pin connected on the master 8259A in a cascaded system?
42. What is an OCW?
43. What is an ICW?
44. Where is the vector type number stored in the 8259A?
45. How many ICWs are needed to program the 8259A when operated as a single master in a system?
46. What is the purpose of ICW1?
47. Where is the sensitivity of the IR pins programmed in the 8259A?
48. Explain priority rotation in the 8259A.
49. What is a nonspecific EOI?
50. At which interrupt vectors is the master 8259A found in the personal computer?
51. What is the purpose of IRR in the 8259A?
At which interrupt vectors is the slave 8259A found in the personal computer?