QUESTIONS AND PROBLEMS
1. Which microprocessor pins are used to request and acknowledge a DMA transfer?
2. Explain what happens whenever a logic 1 is placed on the HOLD input pin.
3. A DMA read transfers data from to .
4. A DMA write transfers data from to .
5. The DMA controller selects the memory location used for a DMA transfer through what bus signals?
6. The DMA controller selects the I/O device used during a DMA transfer by which pin?
7. What is a memory-to-memory DMA transfer?
8. Describe the effect on the microprocessor and DMA controller when the HOLD and HLDA pins are at their logic 1 levels.
9. Describe the effect on the microprocessor and DMA controller when the HOLD and HLDA pins are at their logic 0 levels.
10. The 8237 DMA controller is a(n) channel DMA controller.
11. If the 8237 DMA controller is decoded at I/O ports 2000H –200FH, what ports are used to program channel 1?
12. Which 8237 DMA controller register is programmed to initialize the controller?
13. How many bytes can be transferred by the 8237 DMA controller?
14. Write a sequence of instructions that transfer data from memory location 21000H –210FFH to 20000H –200FFH by using channel 2 of the 8237 DMA controller. You must initialize the 8237 and use the latch described in Section 12–1 to hold A19 –A16.
15. Write a sequence of instructions that transfers data from memory to an external I/O device by
using Channel 3 of the 8237. The memory area to be transferred is at location 20000H – 20FFFH.
16. What is a pen drive?
17. The 3 1/2" disk is known as a(n) floppy disk.
18. Data are recorded in concentric rings on the surface of a disk known as a(n) .
19. A track is divided into sections of data called .
20. On a double-sided disk, the upper and lower tracks together are called a(n) .
21. Why is NRZ recording used on a disk memory system?
22. Draw the timing diagram generated to write a 1001010000 using MFM encoding.
23. Draw the timing diagram generated to write a 1001010000 using RLL encoding.
24. What is a flying head?
25. Why must the heads on a hard disk be parked?
26. What is the difference between a voice coil head position mechanism and a stepper motor head positioning mechanism?
27. What is a WORM?
28. What is a CD-ROM?
29. How much data can be stored on a common DVD, an HD-DVD, and a Blu-ray DVD?
30. What is the difference between a TTL monitor and an analog monitor?
31. What are the three primary colors of light?
32. What are the three secondary colors of light?
33. What is a pixel?
34. A video display with a resolution of 1280 × 1024 contains lines, with each line divided into pixels.
35. Explain how a TTL RGB monitor can display 16 different colors.
36. What are the DVI-D and HDMI connectors?
37. Explain how an analog RGB monitor can display an infinite number of colors.
38. If an analog RGB video system uses 8-bit DACs, it can generate different colors.
39. If a video system uses a vertical frequency of 60 Hz and a horizontal frequency of 32,400 Hz, how many raster lines are generated?