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This chapter is from the book

Apply Your Knowledge

Review Questions

  1. On which I/O address would you find the second IDE controller in a PC-compatible system?

    1. 070

    2. 170

    3. 278

    4. 378

  2. Which IRQ channel would you expect to be servicing an external modem in a PC system that was using a serial mouse in COM1 for input?

    1. IRQ 2

    2. IRQ 3

    3. IRQ 4

    4. IRQ 10

  3. If you wanted to add a color ink-jet printer to a system with a secondary printer port that already had a laser printer attached to LPT1, how could you configure it?

    1. Connect the color printer to LPT2.

    2. Connect the color printer to COM1.

    3. Connect the color printer to COM2 so that the mouse can remain on COM1.

    4. Install a printer switch box so that both printers can use LPT1.

  4. How many DMA channels are there in an AT-compatible system?

    1. 2

    2. 4

    3. 8

    4. 16

  5. Which standard system device uses IRQ6?

    1. The keyboard

    2. Floppy disk drives

    3. The system board's DRAM Refresh circuitry

    4. The parallel printer port

  6. What action normally accompanies installing an external modem?

    1. Rebooting the system

    2. Pushing the reset button on the modem

    3. Disabling the second parallel port

    4. Disabling the second onboard COM port

  7. What type of problem will create an NMI type of interrupt in the system? (Select all that apply.)

    1. A Parity Check (PCK) error in the system's DRAM memory

    2. IRQ conflict between devices

    3. When an active IO Channel Check (IOCHCK) signal is received from an adapter card located in one of the board's expansion slots

    4. Over-voltage of the system board

  8. Which of the following describes the bit pattern that would appear on the address bus to activate the first serial port? (You may use a scientific calculator.)

    1. 0111110000

    2. 1001111000

    3. 1011111000

    4. 1111111000

  9. What does the computer system typically use to stop the processes of the microprocessor so that attention can be given to the demands of a particular device?

    1. ATX

    2. ATA

    3. IRQ

    4. NMI

  10. Which interrupt request channels are available for use through the ISA bus?

    1. IRQ 0-15

    2. IRQ 0-7, 14-15

    3. IRQ 3-7, 9-12, 14-15

    4. IRQ 1-4, 9-11

  11. The IRQ1 channel is used _______ and cannot be used for other devices.

    1. for the system's internal time-of-day clock

    2. by the system's keyboard receiver

    3. by the floppy disk drive

    4. by the printer for LPT1

  12. The IRQ0 channel is _______.

    1. used by the system's timer/counter and cannot be used for other devices

    2. used by the keyboard and cannot be used for other devices

    3. used by the floppy disk drive and cannot be used for other devices

    4. open and can be used for any device requiring an IRQ channel

  13. Which interrupt is cascaded with IRQ2?

    1. IRQ5

    2. IRQ7

    3. IRQ9

    4. IRQ10

  14. Which device normally uses IRQ7?

    1. A laser printer

    2. A modem

    3. A floppy disk drive

    4. A hard disk drive

  15. IRQ4 is normally assigned to the device connected to the ______.

    1. COM1 port

    2. LPT1 port

    3. COM2 port

    4. LPT2 port

  16. A floppy disk drive uses which of the following IRQs?

    1. IRQ2

    2. IRQ5

    3. IRQ6

    4. IRQ9

  17. Which IRQ is the default assignment for the printer attached to LPT1?

    1. IRQ3

    2. IRQ5

    3. IRQ7

    4. IRQ13

  18. What is the IRQ for COM1?

    1. IRQ1

    2. IRQ2

    3. IRQ3

    4. IRQ4

  19. Which of the following combinations are correct? (Select all that apply.)

    1. IRQ1 is the default for COM2 and COM4.

    2. IRQ2 is the default for COM1 and COM3.

    3. IRQ3 is the default for COM2 and COM4.

    4. IRQ4 is the default for COM1 and COM3.

  20. What is the standard IRQ for COM2?

    1. IRQ3

    2. IRQ4

    3. IRQ2

    4. IRQ1

  21. On which I/O address would you find the primary IDE controller in a PC-compatible system?

    1. 070

    2. 170

    3. 1F0

    4. 3F8

  22. Which standard PC device uses a DMA channel?

    1. LPT1

    2. COM1

    3. INTC1

    4. FDD

  23. What I/O address range is typically assigned to the video controller BIOS?

    1. C000-C7FF

    2. C700-CFFF

    3. D000-C7FF

    4. D800-D8FF

  24. Which IRQ channel is reserved for the Real-Time Clock module in an ATX system?

    1. IRQ0

    2. IRQ1

    3. IRQ8

    4. IRQ9

Answers and Explanations

  1. B. The first or Primary IDE controller is assigned IRQ14 while the Secondary controller uses IRQ15 to interrupt the system. The I/O port address for the second IDE controller is 170h-177h. For a detailed listing, consult Table 3.3: I/O Port Addresses. For more information, see the section "Onboard I/O."

  2. B. The modem (or its host COM port) should be configured to for addresses 278 through 27Fh, IRQ3, and COM2. For more information, see the section "Modems."

  3. A. If you have a secondary printer port, the new printer should be configured to LPT2. For more information, see the section "Interrupts."

  4. C. There are two DMA controllers of four channels each. One of these channels (CH4) is a cascade channel and is not available for designation. Therefore, although there are eight DMA channels total, only seven are actually available. For more information, see the section "Direct Memory Access."

  5. B. IRQ6 is normally assigned to the floppy disk drives (FDDs). For more information, see the section "Interrupts."

  6. D. In the case of the internal modem, the UART in the modem normally replaces one of the two COM port UARTs provided by a typical PC system. If the COM port UART is not disabled, the system might have trouble differentiating between the two ports and a conflict can develop. Therefore, it is common practice to disable an onboard UART when an internal modem is installed. The COM ports can be enabled or disabled through the system's CMOS Setup—Peripherals screen. For more information, see the section "Modems."

  7. A, C. There are two system board-based conditions that will cause a Non-Maskable Interrupt (NMI) signal to be sent to the microprocessor. The first condition occurs when an active IO Channel Check (IOCHCK) signal is received from an adapter card located in one of the board's expansion slots. The other event that will cause an NMI signal to be generated is the occurrence of a Parity Check (PCK) error in the system's DRAM memory. For more information, see the section "Interrupts."

  8. D. The first serial port is 3F8h. This translates to a binary bit code of 1111111000. For more information, see the section "Onboard I/O."

  9. C. In the course of normal operations, the various I/O devices attached to a PC, such as the keyboard and disk drives, require servicing from the system's microprocessor. Because these service requests can happen at any time and tend to require immediate attention, I/O devices generally have the capability to interrupt the microprocessor while it is executing a program. The I/O device accomplishes this by issuing an interrupt request (IRQ) input signal to the microprocessor. For more information, see the section "Interrupts."

  10. C. See Table 3.1: System Interrupt Levels. For more information, see the section "Interrupts."

  11. B. See Table 3.1: System Interrupt Levels. For more information, see the section "Interrupts."

  12. A. See Table 3.1: System Interrupt Levels. For more information, see the section "Interrupts."

  13. C. See Table 3.1: System Interrupt Levels. For more information, see the section "Interrupts."

  14. A. See Table 3.1: System Interrupt Levels. For more information, see the section "Interrupts."

  15. A. See Table 3.1: System Interrupt Levels. For more information, see the section "Interrupts."

  16. C. See Table 3.1: System Interrupt Levels. For more information, see the section "Interrupts."

  17. C. See Table 3.1: System Interrupt Levels. For more information, see the section "Interrupts."

  18. D. See Table 3.1: System Interrupt Levels. For more information, see the section "Interrupts."

  19. C, D. See Table 3.1: System Interrupt Levels. For more information, see the section "Interrupts."

  20. A. See Table 3.1: System Interrupt Levels. For more information, see the section "Interrupts."

  21. B. The first or Primary IDE controller is assigned IRQ14, whereas the Secondary controller uses IRQ15 to interrupt the system. The I/O port address for the primary IDE controller is 1F0h-1F7h. For a detailed listing, consult Table 3.3: I/O Port Addresses. For more information, see the section "Onboard I/O."

  22. D. See Table 3.2: System's DMA Channel Designations. For more information, see the section "Direct Memory Access."

  23. A. See Table 3.4: System Memory Map. For more information, see the section "Onboard I/O."

  24. C. See Table 3.1: System Interrupt Levels. For more information, see the section "Interrupts."

Challenge Solutions

  1. He should assign the new printer IRQ5, which is the standard second LPT port (LPT2) in a PC-compatible system. The system will be able to communicate with the printer at hex addresses 278-27Fh. For more information, see the section "Interrupts."

  2. You should be able to fax him the following list:

170-177 Second IDE Controller
1F0-1F7 First IDE Controller
2F8-2FF Serial Port #2
378-37F Parallel Port #1
3F8-3FF Serial Port #1
  1. For more information, see the section "Onboard I/O."

Suggested Readings and Resources

  1. I/O Transfer Methods http://www.ebiz.com.pk/pakistan/dma.doc

  2. IRQ http://webopedia.internet.com/TERM/I/IRQ.html

  3. System Resources http://www.pcguide.com/ref/mbsys/res/

  4. DMA http://www.pcguide.com/ref/mbsys/res/dma/

  5. Introduction to Hexidecimal http://www.intuitor.com/hex/bases.html

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