What's all this about DMA?

DMA, if on, can greatly speed up communications between your PC and its hard drive and DVD/CD drives.

The following assumes your hard drive is on the primary channel and the CD/DVD drive is on the secondary.

To check if it is on:

1. Right click on My Computer
2. Select Properties
3. Click on Hardware
4. Click on Device Manager
5. Double click on IDE ATA/ATAPI controllers
6. Double click on Primary channel
7. Click Advanced Settings and check it says DMA if available and is set to Ultra DMA, mode 5.
8. Do the same for the secondary channel -- it should be Ultra DMA, mode 2.

Don't worry if it says "Not applicable" - it means there is no device connected to that port.

The following diagram shows my primary channel (I have 2 hard drives connected):

If your PC doesn't have DMA enabled, the easiest way to re-enable it is to remove the channel and reboot. Windows will then automatically reinstall it and reset the counters that deactivated DMA in the first place.

To remove the channel:

1. Right click on the relevant channel in Device Manager (you know how to get there - follow steps 1 thru 5 above 
2. Click on uninstall
3. Reboot
4. When you have rebooted (and the drive and been recognised by Windows again), go back to Device Manager and change the setting to DMA if available.
5. Windows NT/2000 users reboot again. XP users, you're good to go.