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Disabling Command Queuing
To improve standalone system performance and to improve performance with some high-
performance SCSI peripherals, you should disable command queuing in the Windows NT
Registry.
WARNING
Do not change values in the Registry other than as directed. If you introduce incorrect
values into the Registry, you may cause serious operating system problems, and you
may have to reinstall Windows NT. If you change values in the Registry that make
your system unusable, you may be able to restart the system and use the Last Known
Good Configuration option to undo the damage. See the operating system
documentation for more information on the Last Known Good Configuration option.
To disable command queuing:
1. Start the Registry Editor (
REGEDT
32.
EXE
) to open the Registry.
2. Open the following subkey in the Registry:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\aic78xx
3. From the Edit menu, select Add Key.
4. Type
Device into the Key Name box, and then select OK. Do not set a Class value.
5. Open the following subkey in the Registry:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\aic78xx\
Device
6. From the Edit menu, select Add Value.
7. Type
DisableTaggedQueuing into the Value Name box.
8. Select REG_DWORD for the Data Type, and then select OK.
9. Type
1 into the Data box.
10. Set the Radix value to Hex, and then select OK.
11. Exit from the Registry Editor and restart the system.
Enabling Bus Mastering for IDE/ATAPI Devices
Your system shipped with bus mastering for IDE/ATAPI devices enabled. If you reinstall
Windows NT 4.0 and Service Pack 3 software, you should enable IDE/ATAPI bus mastering.
NOTE
If you have a CD-Recorder drive installed, do not enable IDE/ATAPI bus mastering. The CD-
Recorder drive is incompatible with IDE/ATAPI bus mastering.
