What is the cause for DMA to fallback to PIO mode?



My friend owns the DVR-A06-J, and recently on certain occasions it tends to fall back from UDMA2 to PIO. He is using a tower casing and the cable (ATA-33), is stretched quite a bit as it just fits.

Also, the pioneer is on the Sec slave channel while the dvd-combo is on the master.
Is it just a faulty IDE cable that needs to be replaced? :bow:


the cause is WindowsXP. If you look in event viewer you might see CDROM errors showing, or you might not. But when windows sees a certain number of errors, it switches to PIO.
Reading errors, like some game protections, can cause it.


In my case if I don’t put Automatic in my motherboard’s BIOS for the A07 (secondary master) cause Win2K doesn’t switch to UltraDMA mode never, it becomes DMA mode only.


I have a sneaking suspicion that iTunes for Windows (that’s the iPod SW) has caused it to happen on a couple of occasions. I have no definitive proof of this but it seems fairly coincidental that on both occasions that it happened I had just started to listen to some streaming audio.



blue screens can cause it. its always good to check after a crash, and if its no longer in dma mode… remove the channel from device manager and reboot.