DMA mode won't enable in XP. HELP!!

[jga]

I can't seem to enable DMA mode in XP.
I have my cd-rw as my secondary master and a regular cd-rom as my secondary slave.
I know my cd-rw can reach DMA mode 4 and my cd-rome can reach DMA mode 2 in windows 2000 but in XP the cd-rw stays at DMA mode 2 and my cd-rom is in PIO mode.
This is really frustrating since everything worked fine in win2k.

Anyone having similar problems and/or can help?

 

[jga]

someone help please

 

[jga]

pretty please?

 

[jga]

with a cherry on top?

 

[elkinm]

If they realy can support DMA as in they show up as DMA in BIOS then windows whould run them that way. One thing that worked for me was going to the device manager in System properties and uninstall the IDE chanels and restart, after restart they were installed with the right settings. If that doesn't work you need to go to the registry. Go to HKEY_LOCAL_MACHINE -> Hardware -> Devicemap -> SCSI.
Click on one of the SCSI ports and you will see the DMAEnabled key go deaper into that port and the proper bus unill you get to the target and Identity to make sure you have the right device and then change the HEX value of DMAEnabled. For Multiword DMA 2 instead of PIO mode set the value to 1 and if you have other faster devices try, a higher number, for instance my ATA100 Hard Drive had a setting of three which was also shared with my DVD drive with only UDMA 2. Maybe a value of 2 sets it for UDMA66 like you want.

If this does not work, TweakXP.com has a tweak for UDMA66 if you look at list of tweaks.

 

[Aosh]

Are we talking about the same DMA here? Is there any correlation between the DMA (Direct Memory Access) and UDMA33/66/100/etc? I thought they were two different animals?

 

[elkinm]

All of them are DMA but regular Multiword DMA mode 2 is the initial DMA with max transfers of 16.6 MB/sec. And alhough CPU usage is greatly reduced it is still high. UDMA is the next step which comes in three flavors, 33/66/100 and each brings slightly improved performance as it has a higher max burst transfer rate as well as slightly lower CPU usage. Althogh from my experience there is a huge diference going from PIO 4 to Multiword DMA 2 and a very noticable diference going from MW DMA 2 to UDMA33 but there is almost no difference going to UDMA66 or 100 especialy for CD/DVD drives as they are to slow anyway. Some newer hard drives utilize UDMA66 and may even benefit from UDMA100. The new standard now is ATA133 (UDMA133) I guess, and it gives a boost to hard drive in most case but nothing extreme.

 

[benjamat]

You dont list your system details but if you have a newer Via chipset system such as 266 or 266A you may well have loaded the latest Via 4 in 1 drivers and that could be your problem. Over at Via arena there are numerous posts on this issue for you to look at.
For myself I found that letting XP manage all the drivers and not installing any 4 in 1's made everything work perfectly.

 

[jga]

thanks guys.
i'm home for the break but i'll try it when i get back to school

 

[jga]

<< If they realy can support DMA as in they show up as DMA in BIOS then windows whould run them that way. One thing that worked for me was going to the device manager in System properties and uninstall the IDE chanels and restart, after restart they were installed with the right settings. If that doesn't work you need to go to the registry. Go to HKEY_LOCAL_MACHINE -> Hardware -> Devicemap -> SCSI. >>



Worked wonderfully.
Thanks a lot elkinm!