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Enabling DMA(UDMA2) on your Windows PC:
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This little guide deals with enabling DMA (Direct Memory Access) for
your Hard-disks in a Windows environment.
For a detailed explanaiton of DMA and whether or not your hardware supports
it, please take a look at John
Scott's guide.
Motherboard chipset to support UDMA2 (Intel 430TX, 440LX, 440EX, 440BX
or 440GX chipset and later or equivalent from another manufacturer).
A hard-drive that supports UDMA2.
(Most hard-drives manufactured after 1997 are DMA capable and newer
(post 1999) CD-Rom drives are even DMA capable too, so check your specs).
Operating system support for UDMA2 busmastering (i.e. drivers).
Windows 2000: you're set
Windows ME
Windows 98
Windows NT4: sp5, sp4 (or sp3 with idefix-i.exe
utility from MS)
Windows 95: patches...(see below)
DMA transfers may require to be specifically enabled too (as with the
Microsoft drivers).
None of Microsoft's Windows operating
systems come with DMA enabled by default, even if your hardware supports
it. So you need to go turn it on. Here's how.
Choose your poison:
Windows 2000:
11/09/00 update: Windows 2000 makes enabling DMA easy:
Go to Programs | Administrative Tools | Computer
Management.
Then open the IDE ATA/ATAPI controllers
tree the right pane and double-click on the Primary
IDE (or Secondary IDE) Channel.
In the dialog that comes up, select the Advanced
Options tab at the top. You will see a dialog similar to the
one below:
Under Transfer Mode select DMA
if available. *Notice that I didn't have DMA enabled on MY box.
You can do the same to any DMA capable devices on your IDE channels,
which used to be just newer hard-drives, but new CD-Rom drives these
days are also capable of DMA, so if your hardware is DMA capable, make
sure you enable DMA to get the most out of it.
Windows ME
A reader, Greg, sent this in:
For me i had to go to my DVD rom drive and select properties to turn
on DMA. You do not enable it thru the hard drive controllers but actually
the individual drives.
Windows 98:
Open control panel - system
applet. Go to the device manager tab.
Click on hard-disk controllers and press
properties.
Check the Dma-enabled box. Restart
 Windows NT: (sp4
or greater, or sp3 with fix)
Open RegEdit and go to the following key:
HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\Scsi\Scsi
Port 0 and set the DMAEnabled value
to 1 (enabled).
*NOTE: If you're running IDE hard-drives, Scsi Port 0 is the Primary
and Scsi Port 1 is the secondary.
Restart for changes to take effect.
 Related
links:
Benchtest.com enable DMA on NT article
The original
DMAchecki.exe
(for Intel processors, from microsoft
KB Q191774)
Simply checks whether or not you really do have DMA enabled under WinNT4.
I got this link from this
Japanese site with lots of DMA info (might be a little outdated)
idefix-i.exe (microsoft ftp)
If you're running NT4 sp3, you will need this patch. Thnx Benchtest
for the link
Windows 95: From:
John Scott's Guide:
To enable UDMA2 on Windows 95b/c (OSR2.x) using Microsoft drivers for the Intel
chipsets:
[step 1 may be omitted if no earlier (i.e. failed) attempts to install
busmaster drivers.]
1. Clean install OSR2
2. Install INF_UP.EXE (SETUPEX.EXE) from www.bmdrivers.com "Fixes &
Patches".
3. Install DSKTSUPD.EXE from ftp.Microsoft.com/softlib/mslfiles
4. Install REMIDEUP.EXE from ftp.Microsoft.com/softlib/mslfiles
5. Check the per drive DMA checkboxes in device manager as required
Do not install Intel's BM drivers.
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Other
sites with good info about DMA
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Benchtest.com
UDMA driver tests - here you can see the performance gains from enabling
DMA.
John
Scott's UDMA IDE Modes explained
John Scott breaks it down so you can separate the truth from the hype.
BMDrivers.com -
down
Everything you need - drivers, instructions, links...
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