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Better Performance and Reduced Errors Achieved by Enabling Direct Memory Access (DMA)

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Introduction

In order to enhance performance and reduce errors, HP recommends enabling DMA (Direct Memory Access) on the CD/DVD Writer and the hard drive.
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Information in this document applies to the following operating systems

Microsoft(R) Windows XP, Windows 98, Windows Me, and Windows 2000 Pro.
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Explanation of Direct Memory Access (DMA)

DMA is a technique for transferring data from main memory to a device (such as a CD/DVD Writer or hard drive) without passing the data through the central processing unit (CPU). While the data transfer takes place via the DMA controller and DMA process, the CPU is available for other functions. Computers with DMA channels can transfer data to and from devices more quickly than computers without DMA channels.
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Enable DMA for IDE CD-Writer

Use Table 1 below for information on how to enable DMA in different operating systems.
Table 1: Enabling DMA on IDE CD-Writers
Windows 98, Windows MeWindows 2000 Pro, Windows XP
  1. Click Start , Settings , and Control Panel .
  2. Double-click the System icon.
  3. Double-click the HP CD/DVD Writer drive listed, and the Settings tab.
  4. Place a check in the box next to DMA . If the DMA box has a checkmark, DMA is already enabled on the CD-Writer (See Figure 1)
  1. Windows 2000: Click Start , Settings , then click Control Panel . Windows XP: Click Start , then click Control Panel .
  2. Double-click the System icon.
  3. Select the Hardware tab, and click Device Manager .
  4. Double-click the IDE ATA/ATAPI Controllers icon.
  5. Double-click the controller where CD/DVD Writer is attached (usually the Secondary IDE Channel).
  6. Select the Advanced Settings tab.
  7. Next to Transfer Mode , select DMA if available from the drop-down menu.
  8. If DMA if available is selected, then DMA is already being used (See Figure 2).
NOTE: USB HP CD-Writers do not have the DMA checkbox available.
Figure 1: Settings tab, HP CD-Writer Properties
Figure 2: Advanced Settings tab, Secondary IDE Channel Properties
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Enable DMA for hard drives

Use Table 2 below for information on how to enable DMA for hard drives in different operating systems.
Table 2: Enabling DMA on hard drives
Windows 98, Windows MeWindows 2000 Pro, Windows XP
  1. Click Start , Settings , and Control Panel .
  2. Double-click the System icon.
  3. Click the Device Manager tab, then double-click Disk drives.
  4. Double-click the IDE DISK / hard drive(s) listed, then the Settings tab.
  5. Place a check in the box next to DMA . If the DMA box has a checkmark, DMA is already enabled on the hard drive (See Figure 3).
  1. Click Start , Settings , then Control Panel .
  2. Double-click the System icon.
  3. Select the Hardware tab and click Device Manager .
  4. From the list of devices, double-click IDE ATA/ATAPI Controllers.
  5. Double-click the controller to which the hard drive is attached (usually the “Primary IDE Channel”).
  6. Select the Advanced Settings tab.
  7. Next to Transfer Mode , select DMA if available from the drop-down menu.
  8. If DMA if available is selected, then DMA is already being used (See Figure 4).
Figure 3: Settings tab, IDE Hard Disk Drive
Figure 4: Advanced Settings tab, Primary IDE Channel Properties
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DMA will not stay enabled

If the DMA option does not stay enabled after restarting the computer, either the device (such as the hard drive or CD-ROM) does not support DMA, DMA is not available on the computer or DMA has not been enabled in the computer's BIOS (Basic Input/Output System). Refer to the computer manufacturer for more information on how to verify whether the computer supports DMA and that DMA is enabled in the BIOS.
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Problems occur after enabling DMA or if DMA is already enabled

Disable DMA if the following occurs

System locks

The system locks when accessing the CD/DVD Writer or locks when restarting the system.

Performance or quality issues

Performance or quality issues such as audio or buffer underruns occur, try disabling the DMA for the CD Writer and enabling DMA for the hard drive.
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