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System Resources

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This chapter helps you to prepare for the Core Hardware module of the A+ Certification examination by covering the following objectives within the "Domain 1.0: Installation, Configuration, and Upgrading" section.

1.3 Identify available IRQs, DMAs, I/O addresses, and procedures for device installation and configuration.

Content might include the following:

  • Standard IRQ settings

  • Modems

  • Floppy drive controllers

  • Hard drive controllers

  • USB ports

  • Infrared ports

  • Hexadecimal Addresses


  • An IBM-compatible PC system is a very flexible tool because it can be configured to perform so many tasks. By selecting appropriate hardware and software options, the same basic system can be customized to be an inventory-management business machine, a multimedia-development system, or a simple game machine.

  • The computer technician must be able to determine what system resources are required for the device, what resources are available in the system, and how they can be allocated to successfully install hardware components in a PC. The following sections describe various standard I/O methods and peripheral connection schemes used to attach options to a PC system.



Extended I/O

Moving Data

Initiating I/O Transfers

Polling and Programmed I/O


Direct Memory Access

Onboard I/O


Floppy Drive Controllers

Hard Drive Controllers

USB Ports

Infrared Port

Hexadecimal Addresses

Chapter Summary

Apply Your Knowledge

Review Questions

Answers and Explanations

Challenge Solutions

Study Strategies

To prepare for the Installation, Configuration, and Upgrading objective of the Core Hardware exam,

  • Read the objectives at the beginning of this chapter.

  • Study the information in this chapter.

  • Review the objectives listed earlier in this chapter.

  • Perform any step-by-step procedures in the text.

  • Answer the review questions at the end of the chapter and check your results.

  • Use the PrepLogic test engine on the CD-ROM that accompanies this book for additional review and exam questions concerning this material.

  • Review the exam tips scattered throughout the chapter and make certain that you are comfortable with each point.


The most frequent operation that occurs in a personal computer involves the movement of information from one location to another. The initial section of the chapter deals with common methods of controlling the movement of data through the system.

Moving data through the system involves allocating system resources (that is, Interrupt Request channels, I/O addresses, and Direct Memory Address channels) to the system's different hardware devices. For this reason, the chapter also presents typical resource assignments associated with PC-compatible systems.

Because the computer industry references resource assignments in terms of hexadecimal addresses and values, the final section of the chapter presents a quick description of hexadecimal counting and addressing.

After completing the chapter, you should be able to describe standard PC resource assignments associated with common I/O connection points (ports) and devices. These assignments include IRQ channels, I/O and memory address ranges, and DMA channels.

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