This DMA thing is really complicated

[357mag]

I've read about this enabling DMA on your computer to speed up your performance. But like so many computer things, the more you investigate, the more confused you get. One thing I don't understand is months ago when I looked at my drives in Device Manager it listed both of them as PIO enabled. Now when I look at them it mostly says DMA. How that got that way I don't know. Here is what I see:

Primary IDE Channel Device 0 DMA Device 1 DMA
Primary IDE Channel Device 0 DMA Device 1 DMA
Secondary IDE Channel Device 0 PIO Device 1 PIO
Secondary IDE Channel Device 0 DMA Device 1 DMA


Now I don't even know what is meant by Device 1 and Device 0. All I know is I have two hard drives and one is master and the other is slave. Now if my computer is already set up to use this DMA I don't see any performance increase. Seems like normal to me. So then I downloaded a program from BlackMaxPC.com that I guess checks your system and detects whether or not DMA is enabled. When I ran the program I got this:

DMA Detection Status

This setting indicates whether or not the Atapi driver will attempt to detect and use DMA support on a given channel. If DMA detection is disabled on a channel the Atapi driver will default to PIO transfers on that channel.

Current DMA Usage Channel 1

DMA not in use
DMA detection status
disabled

Now maybe that just means that it's not set up to detect whether or not you got DMA, maybe it does not mean whether DMA is actually enabled. I guess you can switch a setting and give it a go but I have not done that.

Well as I said it gets kinda complicated, like computers generally are.

[GaryRouth]

Hi 357mag

DMA might seem a little strange & complicated, but it's not quite as bad as it seems. Here's webopedia's blurb:

"DMA - Short for direct memory access, a technique for transferring data from main memory to a device without passing it through the CPU. Computers that have DMA channels can transfer data to and from devices much more quickly than computers without a DMA channel can. This is useful for making quick backups and for real-time applications".

The performance gain isn't always noticeable in smaller, non-demanding tasks, like word processing, or general Internet browsing.

To check your DMA status directly, press your Start button, then right-click the "My Computer" icon in the Start Menu. Select "Properties", then "Hardware", then "Device Manager". Left-click on the plus sign next to "IDE ATA/ATAPI controllers". Then right-click on "Primary IDE Channel", select "Properties" with a left-click, and then select "Advanced Settings" with a left click. The item "Current Transfer Mode" will show if your drive on each channel is using DMA or PIO. Make sure that for "Transfer Mode" for each device is set to "DMA if available". If a drive is set to "PIO ONLY", you can change it to DMA if you're certain your drive supports DMA.

You can inspect the setting for the Secondary IDE Channel in the same way.

The reason you see two "Device" listings for each IDE Channel (controller), is that you can attach two IDE drives to each controller. If you look at your IDE cables, it's likely you'll see the three connections: one for the motherboard, one for "Device 0" and one for "Device 1" (called "Slave" & "Master" in the older terminology). Two controllers, two devices each = four devices can be connected in total. That's the reason you see the list as you posted it.

The detection of devices on most computers will be set to "Auto" in the motherboard's "Bios Setup" screens. When your computer starts, often a banner message will briefly show: "Press F1 (or DEL, or F10, etc.) to enter Setup". One of the menus will have settings for IDE devices. If the devices are set to "Auto", the Bios will auto-detect their capabilities. But you need to have DMA and PIO modes enabled (there is a menu that does just that, sometimes called "Onboard Devices"), as some Bios items allow for disabling these. The manual for your motherboard should have all these settings, and a great many more, for you to check through. For more information on the Bios side of things, see Adrian's famous "Bios Optimization Guide" (there is a free version) over at http://www.rojakpot.com/default.aspx?location=7&var1=18

Hope that clears it up a little.
. . . Gary

[357mag]

Well I went into my BIOS looking for something that said "setup" but all there is is a heading at the top saying "Bios Setup Utility". There are other menus and I was looking for one that had settings for IDE devices and looking for the word "auto" but did not find it. Would that be under "PCI Configuration" Slot 1, Slot 2, Slot 3, Slot 4, Slot 5? Did not see "Onboard Devices" either. The manual actually doesn't say jack. I think it's really poor. In a bunch of languages with very little information useful to the average person.

[GaryRouth]

Hi again -

Take your time, there's no rush when sorting through Bios screens. Each Bios has it's own titles and language, but the basic work that each Bios does is fairly similiar.

The "Auto" item for IDE devices I spoke of is usually on one of the first one or two main menus. The menu is often called "Standard CMOS Features", and might look something like this, in general:
__________________________________________________
Date (mm:dd:yy) . . . . . . . . . . . Tue, July 11 2001
Time (hh:mm:ss) . . . . . . . . . . . 12 : 8 : 59

Primary Master IDE . . . . . . . . . . Auto
Primary Slave IDE . . . . . . . . . . . Auto
Secondary Master IDE . . . . . . . . Auto
Secondary Slave IDE . . . . . . . . . Auto
Drive A . . . . . . . . . . . . . . . . . . .[1.44M, 3.5 in.]
Drive B . . . . . . . . . . . . . . . . . . .[None]
Video . . . . . . . . . . . . . . . . . . . .[EGA/VGA]
Halt On . . . . . . . . . . . . . . . . . . [All errors]
Base Memory 640K
Extended Memory 31744K
Total Memory 32768K
___________________________________________________

In older systems that cannot auto-detect, you might see "User Define" in the spot where "Auto" usually appears in newer systems. To speed up the boot process, some like to set the channels that aren't in use to "None", so that the Bios doesn't waste time trying to detect a drive that isn't there. But most systems are so fast, it's the user's call - it's only a second or two difference.

About the IDE drive "type" -- changing this setting can cause loss of data, so if the drive was set up as Auto or LBA, don't change things to Large, or Normal.

This is all somewhat basic computer-building information, you might want to visit the build-your-own instructional areas available from the home pages here at PC Mechanic. Lots of good info there. The Build-Your-Own CD offered here has gotten some good reviews, too.
. . . . . . . .

The Bios menu in which you'll find the DMA & PIO modes enabled (or not = though I've yet to see a system with this setting disabled) usually has the Onboard Devices terminology somewhere in it's menu title. In some Award Bios Setup menus, it's called "Integrated Peripherals", and looks something like this:
_______________________________________
USB 2.0 Support . . . . . . . . . . [Enabled]
OnChip IDE Device . . . . . . . . . [Press Enter]
OnChip PCI Device . . . . . . . . . [Press Enter]
Super I/O Device . . . . . . . . . . [Press Enter]
Init Display First . . . . . . . . . . . [PCI Slot]
OnChip USB Controller . . . . . . . [All Enabled]
USB Keyboard Support . . . . . . .[Disabled]
USB Mouse Support . . . . . . . . .[Disabled]
IDE HDD Block Mode . . . . . . . . .[Enabled]

--> For the items that say "Press Enter", there are submenus:
The "OnChip IDE Device" submenu carries this explanatory text in an area to one side of the screen:

On-Chip IDE Channel 0/1 (Enabled)
Use these items to enable or disable the PCI IDE channels that are integrated on the mainboard.

IDE Prefetch Mode (Enabled)
The onboard IDE drive interfaces supports IDE prefetching, for faster drive access. If you install a primary and secondary add-in IDE interface, set this field to Disabled if the interface does not support prefetching.

IDE Primary/Secondary Master/Slave PIO (Auto)
Each IDE channel supports a master device and a slave device. These four items let you assign which kind of PIO (Programmed Input/Output) is used by IDE devices. Choose Auto to let the system auto detect which PIO mode is best, or select a PIO mode from 0-4.

IDE Primary/Secondary Master/Slave UDMA (Auto)
Each IDE channel supports a master device and a slave device. This mainboard supports UltraDMA technology, which provides faster access to IDE devices. If you install a device that supports UltraDMA, change the appropriate item on this list to Auto. You may have to install the UltraDMA driver supplied with this mainboard in order to use an UltraDMA device.
_________________________________________

Were you able to check your current DMA settings for the drive controllers in XP's Device Manager, using the instructions I posted in the first reply? Remember that PIO modes can be forced from choices in Device Manager's settings for the hard drive controllers in Windows XP.

I think you'll find a little background reading will help a lot. Not a Master's degree, just a good set of articles, or a good book.

Sorry this post is so long, with the cut-and-paste it's almost a book itself.
Best of luck
. . . Gary

[357mag]

I hit the Delete key during startup and it brings me into one big basic menu. I've done some looking for hard drive and the word "auto" and PIO and DMA but I'll have to go look again. As far as what is in Device Manager it already says "Use DMA if available" and 3 out of the 4 drives are already set to DMA. Least that what it looks like.

[357mag]

Went into the BIOS screen again. In mine here are the menus at the top:

Main Advanced Security Power Boot Exit


I snooped around in all of them and the only one that appeared similar to what you talked about was the Advanced menu. Under that menu there is something called PCI Configuration. Beneath that there is something called IRQ Priority. Then it says:

PCI Slot 1 Auto
PCI Slot 2 Auto
PCI Slot 3 Auto
PCI Slot 4 Auto
PCI Slot 5 Auto

That's the closest thing that I could find.

[GaryRouth]

Just to make sure you're not spending time searching needlessly: what drives are in your system?

If you have just one hard drive (likely on the Primary IDE controller as "Master") and just one optical drive (for your CDs/DVDs or both) - which plug is the optical drive plugged into? If the optical drive is over six years old, PIO mode won't hurt at all. Older optical drives don't transfer at high enough speeds to worry much about performance differences between DMA and PIO.

I'll guess that an older optical drive is plugged into the Secondary IDE controller as "Master".

If your motherboard manual is really a bad one (and you're not alone if it's alarmingly lacking in helpful details = there are a lot of poor motherboard manuals around) go ahead an take a look at the free version of Adrian's Bios Optimization Guide that I gave the link for earlier.

As long as you make sure your drive controllers are set to "Use DMA if available", your Windows setup is good. To make sure a Bios setting isn't getting in the way, you'll need to find the right menu. Navigation tips are usually printed at the bottom of the first screen that you see when entering Bios Setup. Try another look.

. . . Gary

[357mag]

I have two hard drives. One is master and the other is slave. What is plugged into what I don't know. I also have two optical drives. A CD-ROM and a DVD+RW. My motherboard is a fairly new Intel D865PERL.