I am using a Dell Pentium II 233 with 192 Megs Ram, and a 13 gig Maxtor HD (7200). I have a Plextor 1210A RW, and a NEC CD Rom. My question is should all these devices have DMA enabled? The plextor does, but not the others. When I have tried to enable DMA on the HD or CD Rom the setting does not seem to take (the check mark in the DMA box disappears). Buring seems to go fine but is somewhat long. FredE

not all drives support dma

Apologies for hi-jacking your thread FredE, but I'm having the same problem. I had it under Win98 SE and recently uprgaded to XP. Same problem - altho when I try to enable DMA under XP the drives disappear from Device Manager! Thankfully they reappear when I disable DMA.

Re pakalolo joe's point, I don't necessarily agree. My CD writer is a Cyberdrive 32x which has just come out and the manual specifically recommends that DMA be enabled to get the best performance, so it clearly supports it. My mobo is also fairly new and seems to have no problem enabling DMA for my 2 hard drives.

I'm a bit frustrated as my new supposedly fast writer writes OK but it takes about 20 minutes to copy a 700mb CD (my Cd-Rom drive is 48x). The performance is not much quicker than the 4x writer I've just upgraded from.

I think the DMA issue is the key to my problems and would also appreciate some advice. Would an investment in a Raid IDE controller help in any way?

Windows XP will turn off DMA mode for a device after encountering certain errors during data transfer operations. If more that six DMA transfer timeouts occur, Windows will turn off DMA and use only PIO mode on that device.
In this case, the user cannot turn on DMA for this device. The only option for the user who wants to enable DMA mode is to uninstall and reinstall the device.
Windows XP downgrades the Ultra DMA transfer mode after receiving more than six CRC errors. Whenever possible, the operating system will step down one UDMA mode at a time (from UDMA mode 4 to UDMA mode 3, and so on).
If the mini-IDE driver for the device does not support stepping down transfer modes, or if the device is running UDMA mode 0, Windows XP will step down to PIO mode after encountering six or more CRC errors. In this case, a system reboot should restore the original DMA mode settings.
All CRC and timeout errors are logged in the system event log. These types of errors could be caused by improper mounting or improper cabling (for example, 40-pin instead of 80-pin cable). Or such errors could indicate imminent hardware failure, for example, in a hard drive or chipset.

From http://www.microsoft.com/hwdev/tech/storage/IDE-DMA.asp

Don't know about the NEC CD-ROM, but there's no way a 7200RPM hard drive is not designed to run DMA (actually UDMA). Make sure you are not running in MS-DOS compatability mode. This could be caused by loading real mode CD-ROM device drivers in autoexec.bat that were intended for an MS-DOS boot. They will conflict with the protected mode drivers from Windows. There should be no CD-ROM drives loaded in autoexec.bat or config.sys. Run msconfig to and uncheck any line referencing CD-ROM drivers.

FredE,

You specify that you are using a P11 233, which is most probably where your problem lies. One of my machines is a P11 333, and it is running a 7200 Hd at UDMA5 but only because it is run from a Promise ATA100 controller. I have the CD-RW set to UDMA in system settings, in Win98SE, and although the setting appears to have taken, I don't think so because it is a PIO mode 4 Cd-Rw and it shows as PIO mode4 in the Dos part of the boot sequence.

I could have saved the earlier part of the message by just saying that a Mobo which supported P11 233's just does not have a bios which supports maybe even UDMA3 or any other UDMA which probably wasn't out back then. You may have updated your bios? but I doubt if it would ever support the ATA100? drive.

traduk

Yep agree with Traduk, its not the drive its the system. Most older systems will have probs with DMA and this is an older system. It can cause all sorts of weird errors and is NOT recommended on these older PC's. I'm afraid that until you upgrade yur stuck with it as is.
btw I have what is probably the same Maxtor drive in my old PC and it will handle DMA just fine, so that's not it.

Thanks fellas. You have answered my question. Even though DMA for the Plextor remains checked, it is probably not active. I have not set DMA for the hard drive, as I assume the mother board will not support this either. What threw me was that Dell told me that the motherboard would support DMA. The CDR drive burns just fine. Just a little slow. What does PIO stand for? Thanks again Fred