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The Explorer: Soup Up Your Hard Drive with DMAThe Explorer: Soup Up Your Hard Drive with DMA

Several weeks ago in my newsletter, I suggested that readers check to see if their hard drives were set up to use DMA (direct memory access) because using DMA can reduce the load on your CPU by up to 40 percent during disk operations. When I activated DMA disk access on my system, I saw an immediate 15 percent increase in hard drive speed with no ill effects whatsoever. Many, many readers reported similar or even greater increases.

Fred Langa

March 10, 2004

2 Min Read

And if that doesn't work, well, now you know why I suggested that you make a full backup. You can always restore your system (ideally, from DOS, to be sure the Registry gets completely overwritten) and get back to the way things were.

I'm including all this troubleshooting information so you'll have it if you need it -- but chances are, with most systems of reasonably recent vintage, you won't have any trouble at all. Instead, with that simple click of the DMA option, you'll immediately begin enjoying faster -- even much faster -- drive speed. I hope this has helped you -- and now I hope you can help me. You see, there's more to the DMA business, and some of it I simply can't track down at all. For example, right click My Computer/Properties, then Device Manager, then System Devices, then Direct Memory Access Controller. Click the Settings tab and you'll see two options -- a way to reserve an arbitrary amount of memory for the DMA buffer, and a choice of two ways to restrict DMA transfers. I have no clue what these settings do, and a search of both the Microsoft Knowledgebase and the TechNet CD turned up exactly zero -- zilch, nada, nil -- hits. Microsoft built these settings, but appears to be mute on how to use them. Can anyone tell me -- tell us -- what these settings do and what the optimal choices are? In fact, if you have any information to share on DMA, or if you have questions, please click on over to the discussion area! Let's pool out knowledge! DMA/UDMA Info from Microsoft: What To Do If Your Drive Does Not Have a DMA Check Box

What To Do If The DMA Check Box Does Not Remain Checked

General Info on Ultra DMA/UDMA66

Windows 95 IDE Support DMA
http://support.microsoft.com/support/kb/articles/Q154/4/35.asp (includes patch)

What to Do if Your Win95 SR2 Computer with UDMA Hangs
DMA/UDMA/UDMA66 Info from Western Digital (most is not specific to WD drives) http://www.westerndigital.com/products/drives/drivers-ed/udmatp.html
http://www.westerndigital.com/fitness/ata66issues.htm To discuss this column with other readers, please visit Fred Langa's forum on the Listening Post. To find out more about Fred Langa, please visit his page on the Listening Post.

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