DMA Win XP ???

[JENI]

Can somebody explain to me what is DMA ???

Thank you

[tazdevl]

First suggestion. Google is your friend. Takes much less time to find the answer yourself than wait for a response from someone on the boards.

FYI DMA isn't exlusive to Windows XP. Short answer is that it's a less CPU intensive method of moving data from a device into the computers memory. It bypasses the CPU and goes direct into the memory, unlike PIO which brings the CPU into the loop... which isn't a good thing as it wastes cycles.

Direct Memory Access

Direct Memory Access (DMA) is a capability provided by some computer bus architectures that allows data to be sent directly from an attached device (such as a disk drive) to the memory on the computer's motherboard. The microprocessor is freed from involvement with the data transfer, thus speeding up overall computer operation.

Usually a specified portion of memory is designated as an area to be used for direct memory access. In the ISA bus standard, up to 16 megabytes of memory can be addressed for DMA. The EISA and Micro Channel Architecture standards allow access to the full range of memory addresses (assuming they're addressable with 32 bits). Peripheral Component Interconnect accomplishes DMA by using a bus master (with the microprocessor "delegating" I/O control to the PCI controller).

An alternative to DMA is the Programmed Input/Output (PIO) interface in which all data transmitted between devices goes through the processor. A newer protocol for the ATA/IDE interface is Ultra DMA, which provides a burst data transfer rate up to 33 MB (megabytes) per second. Hard drives that come with Ultra DMA/33 also support PIO modes 1, 3, and 4, and multiword DMA mode 2 (at 16.6 megabytes per second).

[Inertia]

See Direct Memory Access (DMA) Modes and Bus Mastering DMA for a detailed explanation.

[tazdevl]

I know this question has been asked more than once. Next time you might want to do a search of the forums to see if it's been answered before posting.

[JENI]

Thank you for your answer.

How do I know in wich channel IDE primery or secondry is connected the cdwr or the cd rom??

[Wedge Maniac]

JENI, do you know how to look at the BIOS?

Or, is this completely foreign to you? If so, don't be shy. We are here help.

[cfitz]

One easy way to get a summary of your system configuration is to run Nero Info Tool and look at the "Configuration" tab. It will tell which drives are on which channels and whether or not DMA is enabled for each.

If you don't have Nero Info Tool, you can download it from this link as found on:

http://www.cdspeed2000.com/go.php3?link=download.html

cfitz

[Inertia]

How do I know in wich channel IDE primery or secondry is connected the cdwr or the cd rom??

If you are installing the CD-RW and CD-ROM for the first time, look in your motherboard manual to see the location of the primary and secondary IDE ports. If you have a hard drive connected to a motherboard IDE cable, it will normally on the primary channel as master. That would make the other IDE cable the secondary channel.

As Wedge Maniac has mentioned, if the drives are already connected, the system BIOS should detect and list the channels to which they are connected. Read your manual to learn how to open the BIOS menu. A lot of BIOS'es open by holding down the Del key when the computer is first booted up.

[JENI]

I look at the nero info tool and it tells me that my Lg cd wr is master and is in the secondary Ide channel and has DMA off and autorun on. The slave is my cd rom and has DMA on and autorun on.
Primery save ( must be the hard drive) DMA on.

What should i do to change DMA off to on, because i have read the threads and they say it DMA must be on.

I have little experience with computers.

Thank you.

[cfitz]

A step-by-step guide may be found in the FAQ section:

http://www.cdrlabs.com/phpBB/viewtopic.php?t=9667

cfitz

[JENI]

No change at all nothing happened it stays in PIO. I rebooted. What is your opinion on doing the changes below???


And another alternative, courtesy of Han with some additional elaboration by Null (this applies to both XP and 2000):

If deleting the IDE channel and your burner from Device Manager doesn't help, open the Registry (Start -> Run -> Regedit) and open the following key:

HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Control \ Class \ {4D36E96A-E325-11CE-BFC1-08002BE10318}

Within this key you will find several subkeys. Most likely you will see the following:

0000 (for the IDE controller)
0001 (for the Primary IDE channel)
0002 (for the Secondary IDE channel)

Each of these subkeys has a named valued called "DriverDesc" that will make it clear to you to which component they correspond. Open the subkey corresponding to the channel on which your troublesome drive is located. Then, if the troublesome drive is the master, delete the "MasterIdDataChecksum" named value. Or, if the troublesome drive is the slave, delete the "SlaveIdDataChecksum" named value.

Reboot. The OS will redetect the device DMA capabilities after reboot.

Note that for many older CD-ROM drives DMA can not be enabled in Windows 2000/XP, so be sure to check the capabilities of your particular drive if you continue to have problems.

[cfitz]

First, what is the exact model of your LG CD-RW drive that is stuck in PIO mode?

Second, did you check your BIOS? Is the secondary master DMA mode set to auto-detect?

Third, did you already try deleting the secondary IDE channel from the device manager as descibed in the FAQ prior to the portion you quoted? I would try that before editing the registry.

cfitz

[JENI]

I just went on and edited. Reboot and DMA was enabled. Everything is working.
I have LG 52x 24x 52x cd wr.

With DMA now on, the cd wr will copy faster??

Thank you for your help.

[cfitz]

I just went on and edited. Reboot and DMA was enabled. Everything is working.

Good deal. There is nothing wrong with that trick, but since you indicated you were inexperienced with computers, I thought it might be safer to exahaust all the alternatives first. Somehow I think either you aren't as inexperienced as you claim, or else you are a fast learner.

With DMA now on, the cd wr will copy faster??

Yes, you should see faster transfer rates that will result in faster copies.

Thank you for your help.

You're welcome.

cfitz

[JENI]

I know how to get around, but don`t know what I am doing.


One last question does the primery IDE channel needs to be in DMA also, or it has to be in PIO.


Thank ypu for your help.

[cfitz]

It does not have to be in PIO mode. On the contrary, for best performance every device that supports DMA transfer modes should be in DMA mode. That effectively translates to "every device should be in DMA mode", since all modern devices do support DMA transfer modes. These days PIO mode is just a last-resort fall-back position in case there is some problem getting DMA mode to work properly.

cfitz

[CDRecorder]

Cfitz is right; all devices need to be in DMA if you want your computer to run at the speed at which it's capable of running. If the hard drives are in PIO mode, they will run really slowly, too.

[Wedge Maniac]

Somehow I think either you aren't as inexperienced as you claim, or else you are a fast learner.
cfitz

Ditto that. If you are a newbie to all of this JENI, to the registry in particular, then you are one astute individual. The registry is not something to play with unless you are certain of what you are doing.