Chapter 13: System Resources^309
Troubleshooting DMA Channels
DMA channels are fairly straightforward to troubleshoot. A DMA device will use what-
ever channel is available to it, so what may look like a DMA channel problem (meaning it
isnotanIRQproblem)mayactuallybeeitheranI/Oaddressormemoryaddressissue.
First, try choosing another I/O address or memory address for the device, if the de-
vice lists alternatives. If that fails, try using the Windows Troubleshooting utility before
calling the manufacturer’s technical support.Running Windows Troubleshooting
Boot the PC into Windows Safe Mode by pressing the F8 key when you see the first Win-
dows screen and choosing Safe Mode from the menu. From the Safe Mode Desktop, do
the following:- Open the Control Panel and double-click the System icon.
- Choose the Performance tab and choose the File System button from
the Advanced Settings near the bottom of the window. - The File System Properties window displays, as shown in Figure 13-17.
Choose the Troubleshooting tab. - Check every option in the Settings area and attempt to reboot the PC
into normal mode. - If the PC does boot into normal mode, uncheck one item and restart the PC.
Keep repeating this step, unchecking another item and restarting the PC until
it fails. You should have isolated the problem device.
However, if the PC will not reboot into normal mode, reboot into Safe Mode. Use the
DeviceManagertodisableeverydevice(exceptthoseunderSystemDevices)andthenat-
tempt to reboot into normal mode. If you can, more than likely the issue is a bad or
out-of-date device driver. Re-enable devices by type and restart the PC. You should even-
tually isolate the device group that has the problem device.
The really bad news comes when you cannot get the PC to boot into Safe Mode. In this
case,youneedtophysicallyremovedevicesfromthePCandrestartuntilthePCwillboot
and you have isolated the device causing the problem. Just to be sure, try putting the
other devices back into the PC and rebooting. More than one or a combination of devices
may be causing the problem.