Phalanx-Imawano
Just learned something about WinXP and ATAPI DVD-ROM drives - it's very strict with DMA support for them. Whereas Win95/98/ME will try as much as it can to enable DMA support if you activate it in the CDROM device properties, WinXP will check the bios bootup configuration and comply with it (i.e. if the bios detects the DVD-ROM drive as supporting only PIO mode, WinXP will configure it as such even if Ultra DMA mode is allowed in that drive's device properties; Win95/98/ME will try as much as it can to support DMA mode if you activate it regardless of bios settings).
I've had this instance. My PC used to be a PentiumIII 1GHz with ECS P6VXAT motherboard and Creative 8x DVD-ROM drive. At first the DVD-ROM drive would be detected by the bios and be configured in DMA Mode 2, and is automatically configured likewise in WinXP. Sometime later a problem seemed to develop on my mobo, and the DVD-ROM would only go to PIO mode. To my chargin WinXP followed suit, and the result was that DVD movie software playback got skippy and choppy (I read that Software DVD playback requires DMA support on the DVD-ROM drive). Sometime later I upgraded my system to a Pentium4 2GHz with ASUS P4S133 motherboard, while at first keeping the DVD-ROM drive - the drive would still be configured on PIO mode by the bios, and WinXP agreed! I decided on an experiment - I had a 2nd PC with an ASUS 8x DVD-ROM drive (that PC received the old PIII 1GHz CPU and ECS mobo). I swapped the ASUS and Creative drives between the two PCs. On bootup of the WinXP system which now had the ASUS drive, the ASUS drive was configured by the bios to DMA Mode 2 (to my surprise), and fortunately WinXP did the same. To my even bigger surprise when the PIII system (which had Windows ME) started up with the Creative drive, that one configured the Creative drive to PIO mode (at bios level), but WinME let me activate DMA support, which worked well (huh???). To test if it did work with DMA support, I popped in a DVD title and played it with my DVD software - no skipping (hmm...).
I wonder what gives here. Or is WinXP doing the right thing being "compliant" to the hardware setup while WinME is "cheating" and will eventually cause problems?
I've had this instance. My PC used to be a PentiumIII 1GHz with ECS P6VXAT motherboard and Creative 8x DVD-ROM drive. At first the DVD-ROM drive would be detected by the bios and be configured in DMA Mode 2, and is automatically configured likewise in WinXP. Sometime later a problem seemed to develop on my mobo, and the DVD-ROM would only go to PIO mode. To my chargin WinXP followed suit, and the result was that DVD movie software playback got skippy and choppy (I read that Software DVD playback requires DMA support on the DVD-ROM drive). Sometime later I upgraded my system to a Pentium4 2GHz with ASUS P4S133 motherboard, while at first keeping the DVD-ROM drive - the drive would still be configured on PIO mode by the bios, and WinXP agreed! I decided on an experiment - I had a 2nd PC with an ASUS 8x DVD-ROM drive (that PC received the old PIII 1GHz CPU and ECS mobo). I swapped the ASUS and Creative drives between the two PCs. On bootup of the WinXP system which now had the ASUS drive, the ASUS drive was configured by the bios to DMA Mode 2 (to my surprise), and fortunately WinXP did the same. To my even bigger surprise when the PIII system (which had Windows ME) started up with the Creative drive, that one configured the Creative drive to PIO mode (at bios level), but WinME let me activate DMA support, which worked well (huh???). To test if it did work with DMA support, I popped in a DVD title and played it with my DVD software - no skipping (hmm...).
I wonder what gives here. Or is WinXP doing the right thing being "compliant" to the hardware setup while WinME is "cheating" and will eventually cause problems?
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Responses to this topic
pmistry
Yeah I agree with you on Windows XP's DMA support, it sucks. I have an LG 52X CD-ROM drive, and while it doesn't support UDMA/33 it does support Multiword DMA Mode 2. In Windows 98/ME if I check off DMA and reboot, the drives will work in DMA mode and all is fine. In Windows XP if I select DMA if available, the drive will kick back into PIO mode because of the BIOS. If I go into my BIOS setup and select CDROM instead of AUTO for the device and manually input DMA, Windows XP will use DMA.
However I didn't have this problem with Windows XP until I installed CD-Rom burning update. Also under Service Pack 1, I get these issues too, probably because the CD-Rom burning update is included. Before using these updates I could select DMA If Available and Windows XP would enable DMA on the next reboot. Also installing my VIA drivers help as well.
However I didn't have this problem with Windows XP until I installed CD-Rom burning update. Also under Service Pack 1, I get these issues too, probably because the CD-Rom burning update is included. Before using these updates I could select DMA If Available and Windows XP would enable DMA on the next reboot. Also installing my VIA drivers help as well.
thatsteveguy
I had the exact same problem with my DVD drive in XP. Had no choice but to go back to win2k just to get DVD's to play.
if they ever get it sorted out I might move back to xp but for now 2k is just fine.
S
if they ever get it sorted out I might move back to xp but for now 2k is just fine.
S
Phalanx-Imawano
OP
Update: recall that PC that had WinME in it (the PC where the bios configures the DVD-ROM to PIO mode)? Well, after complaints from its users about instability (my mom and dad) I changed the OS to Win2k. Surprise surprise, just like the Win9x guys Win2k isn't so fussy as WinXP about DMA support on the DVD-ROM (i.e. Win2k will get it to run on DMA mode if the IDE properites is set to "DMA if available" even if the bios configured it to PIO mode).
pmistry
Yeah, same here, Windows 2000 is pretty good at DMA support.
pane00
I have an Afreey 52x CDROM and every now and again it will change it back to PIO mode. Even though it's UDMA 33.
