here are some ideas on dma. I dont think the links are active so you will have to type them. good luck
1) MAD about DMA
Wow! What a commotion the current WinMag article on DMA caused! (See
http://www.winmag.com/columns/explorer/2001/02.htm ) Many, many
readers have reported instant speed increases similar to the ones I
reported (5-15%); and all just by clicking on the right choice-box in
Windows.
There have been some interesting side effects, too, such as this note
from reader Ralph Todd:
Your suggestion on turning on the DMA function to increase
the speed speed of various drives had an unexpected
benefit. For weeks I've been unable to defragment my new
20gig Maxtor hard drive due to a dynamic drive overlay that
the software automatically installs. For some reason, when
I turned on the DMA function, it apparently bypassed the
BIOS limitation on my old pentium pro 200 and the norton
utility defragmentation now works perfectly.
But, as the WinMag article said, you have to test to be sure, because
it doesn't work on all machines. And sometimes, the test leads to
further discoveries:
Your advice to activate DMA mirrors my own advice up until
about a month ago. However, a close friend did extensive
tests, timing large transfers from drive to drive, some
IDE, some SCSI (IDE to IDE, IDE to SCSI). He found that
with DMA enabled, the transfers actually took longer (5% or
so) !! (Win98) Of course (I suppose) this is irregular, but
increases in speed cannot be guaranteed !!
In addition, I have encountered troubleshooting guides for
CD writers that request that DMA be disabled if problems
occur. There is obviously more to this than meets the eye.
Perhaps some MoBoards or perhaps chipsets do not respond
properly to DMA transfers.
There was also an issue for certain versions of win95 as
whether to use the MS or Intel Bus Mastering drivers, which
could alter the results. This is not an issue with win98.
http://developer.intel.com/design/chipsets/drivers/busmastr/index.htm
I believe that ALI & VIA chipsets use their own bus
mastering drivers, and of course improved versions from
what windows installs can always be downloaded. --- Greg
Some users of Win95 SR2 and early version of Win98 found something
else, such as:
Check out the article at
http://www.microsoft.com/hwdev/devdes/idedma.htm It seems
that the good programmers at MS forgot to add a key line in
Windows 98 that allows DMA to be enabled at all. You must
go manually into the inf file Mshdc.inf and under
ESDI_AddReg section add the lines (if you are one of the
lucky ones they may actually be there but in a lot of
systems they are not) HKR,,IDEDMADrive0,3,01 and
HKR,,IDEDMADrive1,3,01 below it in order to enable the
driver.--- mouse51
And some CD/CDR/CDRW users dug out additional info on using DMA with
those drives, like this:
You may want to mention in a followup to your story on
enabling DMA an apparently common problem with CDROM/CDRW.
When DMA is enabled, the Windows 98 Explorer will sometimes
not recognize the drive, even though it shows up in the
System Properties in Control Panel. I spent hours trying to
figure this one out, finally ending up (should have gone
there earlier...) at the MSKnowlege base. You can read all
about it here
http://support.microsoft.com/support/kb/articles/Q235/8/59.ASP
Even after reading through the MSKB article it took
some fiddling to get it to work, but now my Plextor CDRW is
working great...*with* DMA. --- Butch Berney
Thanks to all who wrote!
DMA is a hot and complex topic, and well worth checking out. But if you're going
to try modifying the DMA settings on your system, be sure to read
both the current article (
http://www.winmag.com/columns/explorer/2001/02.htm )and the older one
it references (
http://www.winmag.com/columns/explorer/1999/1206.htm
). If you follow the instructions there, odds are you WILL see a
speed increase and you WON'T have trouble. But as the combined
articles fully explain, even if you do have trouble, there are simple
ways to get back to exactly where you were before
You Dont Want To Be The Last to Know Anything.
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