How does a computer locate devices?

Published on May 23rd, 2009 at 8:00 am

Last modified on August 13th, 2012 at 7:02 pm



A computer contains many different devices, including keyboards, memory, and network ports. What method does a computer use to keep track of these devices and locate them on the bus?

A) Direct memory access (DMA)

B) Interrupt request (IRQ)

C) I/O address

D) DDR memory


The answer: C) I/O address

The CPU keeps track of memory addresses and physical devices through a set of reserved I/O addresses. Almost every device in a computer has a set of addresses referenced by the CPU.

The incorrect answers:

A) Direct memory access (DMA)
DMA is a method of communication that bypasses the CPU and communicates directly to the memory. Because of the overhead and processing associated with the DMA process, most devices do not communicate to memory through DMA.

B) Interrupt request (IRQ)
IRQs are used by devices to get the “attention” of the CPU, not to identify a particular location of a device.

D) DDR memory
Double data rate memory is a type of memory, not a method of communication.

Want to know more? Watch “System Resources: I/O, IRQ, and DMA.”


If you’ve ever looked into the details of the Windows Device Manager, then you’ve probably seen references to I/O addresses, IRQ values, and DMA settings. In this video, we’ll explain what all of these abbreviations mean and show you how the Windows Device Manager can be used to view and modify the system resources in your personal computer.

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Category: CompTIA A+ Pop Quizzes

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