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Microsoft Windows includes a Bus Mastering feature known as Direct Memory Access or DMA. When this DMA feature is enabled, it basically allows your Hard Drive and CD Rom Drive to transfer their information directly to and from memory without passing through the Microprocessor. Hence the word, Direct Memory Access. In short, when your disk drives use Direct Memory Access to access their information, this reduces the load placed upon your CPU and your system works faster.
Essentially, Direct Memory Access (DMA) is the theoretical data access rate of a Drive measured in megabytes per second. For instance, an Ultra DMA-100 Hard Drive will theoretical access data at a rate of 100 megabytes per second and an Ultra DMA-133 Drive will theoretical access data at a rate of 133 megabytes per second. So this technical brief will show you how to enable Direct Memory Access (DMA) on your Computer System.
How To Enable the DMA Setting on Your Hard Disk Drive
Go into your Control Panel by first clicking on the Start Button.
Then click on Settings, then Control Panel.
Then Double click on the System icon to open up the System Properties window.
Then click on the Device Manager tab at the top of the screen.
Now click on the plus sign [+] next to the Disk drives Icon to expand that section.
Double click on your IDE Disk Drive to display the Properties Window.
Then click on the Settings Tab located at the top of the screen.
Within the Options section, You will see a white box next to DMA.
Placing a check mark into this white box will enable the high speed DMA transfer setting.
Clearing an existing check mark from this white box will disable the DMA transfer setting.
Then click on the OK button at the bottom of the screen to save your settings.
And then click on OK to exit the System Properties Window.
Select Yes when Windows Prompts you to Restart your Computer now.
Repeat the above procedure on any additional Hard Drives you have in your system.
How To Enable the DMA Setting on Your CD Rom Drive
Go into your Control Panel by first clicking on the Start Button.
Then click on Settings, then Control Panel.
Locate the System icon and Double click on it to open up the System Properties window.
Then click on the Device Manager tab at the top of the screen.
Now click on the plus sign [+] next to the CD ROM Icon to expand that section.
Double click on your CD Rom Drive to display the Properties Window.
Then click on the Settings tab at the top of the screen.
Within the Options section, You will see a white box next to DMA.
Placing a check mark into this white box will enable the high speed DMA transfer setting.
Clearing an existing check mark from this white box will disable the DMA transfer setting.
Then click on the OK button at the bottom of the screen to save your settings.
And then click on OK to exit the System Properties Window.
Select Yes when Windows Prompts you to Restart your Computer now.
Repeat the above procedure on any additional CD Rom Drives you have in your system.
How To Enable DMA For Windows XP
For Windows XP, Direct Memory Access is not set for individual Hard Drives and CD Rom Drives as depicted above. Instead, DMA is set for the Primary IDE Channel and the Secondary IDE Channel. In short, each Channel allows us to have two devices connected for a total of four devices. These devices can be a combination of Hard Disk Drives, CD Rom Drives, CDRW Drives, DVD Drives and Tape Backup Drives etc. Therefore, if both channels are set for DMA access, then all the devices in your system will be set to use DMA.
For Windows XP
Go into your Control Panel by first clicking on the Start Button.
Then click on Settings, then Control Panel.
Then double click on the System icon to open up the System Properties window.
Now click on the Hardware tab located at the top of the screen.
Then click on the Device Manager button in the center area of the screen.
Now click on the plus sign [+] next to the IDE ATA/ATAPI controllers to expand that section.
Then double click on the Primary IDE Channel to display the Primary IDE Properties window.
Then click on the Advanced Settings Tab at the top of the screen.
Now for Device 0, ensure that the Transfer Mode: selection is set to DMA if available.
Then for Device 1, ensure that the Transfer Mode: selection is also set to DMA if available.
Then click on the OK button at the bottom of the screen to save your settings.
Then double click on the Secondary IDE Channel to display the Secondary IDE Properties window.
Then click on the Advanced Settings Tab at the top of the screen.
Now for Device 0, ensure that the Transfer Mode: selection is set to DMA if available.
Then for Device 1, ensure that the Transfer Mode: selection is also set to DMA if available.
Then click on the OK button at the bottom of the screen to save your settings.
Then close Device Manager and the Control Panel to return back to your Windows session.