Feurio Frequently Asked Questions - Definition:
Busmaster Driver (DMA)
Unfortunately many Windows versions operate IDE devices (i. e. IDE CD-ROMs and
IDE CD-Writers) in the "Programmed IO-Mode", i. e. the CPU sends each byte actively
to the device and receives each byte actively, too. Of course this requires a
lot of process time!
To solve this problem, a "busmaster driver" has to be installed.
If a "busmaster driver" is activated, the transfer is done without using the
CPU - the CPU only sends the command "I urgently need the sectors from x to y.
Would you mind storing them at memory address z?". The whole transfer is done
without the CPU's help and therefore doesn't need any process time. - Where
do I get a Busmaster driver?
Usually a disk/ CD with with the appropriate busmaster driver should be delivered
along with your mainboard/ computer. Please take a careful look at the disks/
CDs and mainboard/ computer manuals that came along with your system.
Depending on the version Windows already contains busmaster drivers for certain
boards (especially Intel boards) - on a Windows 98 Second Edition or Windows
2000 system busmaster drivers are installed automatically for boards with Intel
chipsets.
If you didn't succeed in finding the correct driver, you can download a "generic"
busmaster driver from http://www.bmdrivers.com/
that should work fine on most systems. - Windows 95/98 User:
Under Windows 95/98 busmaster mode can be activated/ deactivated for single devices;
even after installing a busmaster driver, the busmaster mode is oftenly deactivated.
To activate start the Device Manager (Start -> Settings -> Control Panel),
select "Device" and expand the branch "CD-ROMs". Select the CD-ROMs/ CD-Writers,
"Properties" -> "Settings" and activate the switch "DMA".
If no switch "DMA" is present, the busmaster driver has not been correctly installed
- or it is a vendor specific busmaster driver, that can not be controlled by
Windows - in this case the manufacturer should have provided a configuration
tool - please take a look at the drivers information!
- Windows 2000 User:
Under Windows 2000 the busmaster mode can be configured for each device, too:
Start" -> "Settings" -> "Control Panel". Start "System", select tab "Hardware",
click on "Device Manager".
Expand the branch "IDE ATA/ ATAPI Controller". Click on "Primary IDE channel"
resp. "Secondary IDE channel", right mouse button -> "Properties". Select
the tab "Advanced Properties".
Within the boxes "Device 0" and "Device 1" you can select the "transfer mode"
for the particular device attached to the channel. Change the transfer mode to
"DMA, if available" to activate the busmaster mode. You can find the currently
used transfer mode under "Current transfer mode".
Attention:
Some CD-ROMs as well as some CD-Writers can not be operated in busmaster mode,
please check carefully and deactivate the busmaster mode for this device, if
necessary.
NOTE FOR NOT-INTEL CHIPSETS:
If you own a mainboard that is not equipped with an Intel chipset: Usually the
boards' manufacturers offer own busmaster drivers for their chipsets - unfortunately
we gained the experience that these busmaster drivers are oftenly "buggy" respectively
not developed completely - most of the time they work fine with hard disks. But
they fail with CD-ROMs and especially CD-Writers! (This is probably caused by
the fact, that hard disks always transfer multiples of 512 bytes - however CD-ROMs
and CD-Writers might possibly transfer other values than 512 bytes more often
- obviously these busmaster drivers can not handle this.
The effects may range from strange error messages to a complete frozen system.
Under Windows NT even the feared "Blue Screens" occured in some cases.
For additional information see:
Frequently Asked Questions - Definitions
Frequently Asked Questions - Main Page
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