Using DMA Mode in Windows® XP
The DMA mode for ATA/ATAPI Devices in Windows® XP
The Microsoft® Windows® XP operating system was developed as the successor to the earlier Windows® Me Edition. The Windows® XP stands short for Windows® eXPerience and it is known so because of the interface it brings to the users. There was a great change in the appearance and functionality between the earlier Windows® Millennium Edition and the Windows® XP. The new operating system only required a minimum configuration of 233 MHz, 63 MB of RAM memory and a 1.5 GB hard disk capacity to run it. The DMA is known as the Direct Memory Access. When the DMA is enabled for Windows®, it allows faster transfer of data between the hard disk and CD-ROM without allowing the data to flow into the microprocessor.
The following description presents how the DMA mode works on the ATA/ATAPI devices running on Windows® XP operating system.
- Use of DMA mode
- Setting the ATA/ATAPI devices to DMA mode
- Errors that might occur in DMA mode
Use of DMA mode
The DMA mode is the Direct Memory Access mode for the ATA/ATAPI interface that connects the drives such as the CD-ROM and the hard disk on the PC. The DMA mode provides means of accessing the data between the drives without the processor coming into the picture. There is also an option of ultra DMA mode that allows the higher transfer of data rate between the system drives. If the IDE channels are set to DMA access in the operating system, then all the channels would be set to run on the DMA mode.
Setting the ATA/ATAPI devices to DMA mode
Enabling the DMA mode on the system is very simple. The DMA can be enabled through the 'Control Panel' in Windows® XP operating system. Go to 'Control Panel' and the 'Device Manager'. Double click the 'IDE ATA/ATAPI' Controllers. Click on the 'Primary IDE' and select 'Properties', go 'Step wise', enable 'DMA on the Device 1' by setting it, and then for Device 2 set the DMA mode. After this, click the 'Secondary IDE', open the 'Advanced Settings' and follow the same process to enable and set the DMA mode. Certain devices though, would permit PIO (Programmed Input Output) mode only.
If errors occur in the DMA mode, the IDE chipsets tend to revert themselves back to the original ATA/ATAPI mode. The compatibility testing on the chipsets sometimes shows that enabling the DMA mode can cause the corruption and the loss of data from the drives. The common error that occurs in the drive would be the Cyclic Redundancy Error (CRC). If, while running on the DMA mode, this error occurs more than five times, the Windows® XP system would disable the DMA mode by itself and return to the PIO mode for the particular device.