PIO mode on secondary IDE controller

  • Thread starter Thread starter swingman
  • Start date Start date
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swingman

I've seen this issue on a great many computers running XP where the primary
IDE controller is set to "DMA If Available" and the secondary controller
defaults to "PIO Mode Only". If I change the setting to "DMA If Available"
on the secondary controller the mode will always change to DMA for the
connected device (usually a CDROM drive). Any idea why this happens and if
there's a way to make XP default to the "DMA IF Available" setting?
 
If a CD drive encounters too many read errors while accessing a CD, the
speed of that IDE channel is dropped down automatically. This will read the
CD at a slower, and hopefully, more reliable speed. It will keep dropping
down to the minimum, as you have found out. A simple reboot will not change
this back.

You have to go into the device manager and uninstall the offending IDE
channel. Then close the device manager and reboot. Remove any CD's from the
drive. The IDE channel will be redetected upon startup and all should be
well - until the next time you install a faulty CD into the drive.

--
Regards,

Richard Urban
Microsoft MVP Windows Shell/User

Quote from: George Ankner
"If you knew as much as you thought you know,
You would realize that you don't know what you thought you knew!"
 
You will need to make sure that you have an 80 wire / 40 pin Ultra DMA IDE
cable on the secondary IDE controller port. With-out this cable, it would
only set the transfer mode to PIO.
 
I've encountered the situation you describe, where a device has been
downgraded to PIO mode and it's been necessary to remove/re-install the IDE
channel to restore DMA, however this is different. In this situation the
CDROM's are defaulting to PIO. Simply changing the setting on the secondary
IDE controller to DMA (without removing/re-installing it) makes DMA
available and the CDROM's immediately switch to (usually) DMA Multi Word 2
without rebooting.
 
swingman said:
I've seen this issue on a great many computers running XP where the
primary IDE controller is set to "DMA If Available" and the secondary
controller defaults to "PIO Mode Only". If I change the setting to "DMA
If Available" on the secondary controller the mode will always change to
DMA for the connected device (usually a CDROM drive). Any idea why this
happens and if there's a way to make XP default to the "DMA IF Available"
setting?
Click to expand...

This behavior is caused by faulty media. When XP encounters errors it will
lower the speed. I had this problem with a faulty copy of Office 2000. I
dug out the original CD then burned a fresh copy. _End of problem_.
 
Depends which subset of DMA you're talking about. The first and second DMA
modes work fine with a 40 wire cable. 66/100/133 all require the cable
you're referring to.

I recommend such an 80 wire cable always due to subsequent reduction or
elimination in crosstalk and onboard RF interference.
 
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