Hardware Registry Secrets
Table of contents
MGA Powerdesk
These registry entries let you tweak the features and performance of the PowerDesk software that ships with the Matrox Millenium and Mystique cards.

II-33 Hive: HKEY_LOCAL_MACHINE
Key: System\CurrentControlSet\Services\MGACtrl\PowerDesk
Value Name: PowerDeskPath
Data Type: REG_SZ
Value: C:\Program Files\MGA NT PowerDesk

This value sets the path to the configuration files for the Matrox PowerDesk configuration software. For example, to find out where the monitor configuration files are, look here for the path, then look in the MON subdirectory located under this path.

II-34 Hive: HKEY_LOCAL_MACHINE
Key: System\CurrentControlSet\Services\MGACtrl\PowerDesk\ CurrentSettings
Value Name: BitsperPixel
Data Type: REG_DWORD
Value: 08h

This value sets the number of colors that the card is currently configured to display in bits per pixel (bpp). Valid values are 08h (8 bpp, or 256 colors); 0Fh (15 bpp, or 32 K colors), 10h (16bpp, or 64 K colors), 18h (24 bpp, or 16,777,216 colors), and 20h (32bpp, or true color).

II-35 The next two settings determine the resolution (in pixels) of your desktop area, which includes your entire Windows workspace.

Hive: HKEY_LOCAL_MACHINE
Key: System\CurrentControlSet\Services\MGACtrl\PowerDesk\ CurrentSettings
Value Name: Mga.DesktopX
Data Type: REG_DWORD
Value: 0x400

II-36 Hive: HKEY_LOCAL_MACHINE
Key: System\CurrentControlSet\Services\MGACtrl\PowerDesk\ CurrentSettings
Value Name: Mga.DesktopY
Data Type: REG_DWORD
Value: 0x300

Your Windows workspace consists of everything you see on-screen and in the off-screen area when you�re using a �virtual desktop.� (You use a virtual desktop, or viewport, when your desktop area is larger than your display area.)

II-37 These two settings govern the resolution (in pixels) of your display area.

Hive: HKEY_LOCAL_MACHINE
Key: System\CurrentControlSet\Services\MGACtrl\PowerDesk\ CurrentSettings
Value Name: Mga.DesktopX
Data Type: REG_DWORD
Value: 0x400

II-38 Hive: HKEY_LOCAL_MACHINE
Key: System\CurrentControlSet\Services\MGACtrl\PowerDesk\ CurrentSettings
Value Name: Mga.DesktopY
Data Type: REG_DWORD
Value: 0x300

Your display area is your on-screen workspace, or the actual resolution that the video card sets your monitor to. Generally, these settings are set to the same values as your Desktop settings, though these values can be set smaller than the desktop values to create a viewport into your desktop.


CD-ROM

II-39 Sometimes when running NT 4.0, you get frequent Event Viewer messages specifying an ATAPI source error, Event #9: �The device \device\scsiport0 did not respond within the timeout period.� You can tell Windows NT to stop polling the CD-ROM for disk changes by changing the following registry entry.

Hive: HKEY_LOCAL_MACHINE
Key: System\CurrentControlSet\Services\CdRom
Value Name: Autorun
Data Type: REG_DWORD
Value: 0


SCSI CONTROLLERS

II-40 You recently decided to add a SCSI CD-ROM to your system, and you add a 1522 just for the CD-ROM. You boot NT and it hangs after trying to boot from the 1522. How can you dictate the boot process? This registry entry does the trick.

Hive: HKEY_LOCAL_MACHINE
Key: System\CurrentControlSet\Services\ SCSI_CONTROLLER_NAME
Value Name: Tag
Data Type: REG_DWORD
Value:

You�ll need the value from the new SCSI controller and from the original controller. If you swap these values, your system should boot from the original controller.

II-41 If you use the Sparrow.sys driver for your SCSI adapter, you may have noticed that by default it is assigned IRQ 11 and this assignment seems to be hardcoded. Do not despair. This registry entry lets you override the hardcoded IRQ 11 and change it to anything you want.

Hive: HKEY_LOCAL_MACHINE
Key: System\CurrentControlSet\Services\Sparrow

Add the following key under the Sparrow key.

Key: Parameters

Now that you have the Parameters key, you need to add another subkey: Device(n). The n is the device number you are changing the IRQ for. If you only have one adapter, it is Device0.

Key: Device0

Next, you need to add the actual value that lets you change the IRQ settings:

Hive: HKEY_LOCAL_MACHINE
Key: System\CurrentControlSet\Services\Sparrow\Parameters\ Device0
Value Name: DriverParameter
Data Type: REG_SZ
Value: IRQ=12 (or any other valid IRQ setting)

You must reboot the machine for this change to take effect.

II-42 To increase the throughput of your SCSI adapter, try changing this registry entry.

Hive: HKEY_LOCAL_MACHINE
Key: CurrentControlSet\Services\aic78xx

Add the following key under the aic78xx key:

Key: Parameters

Now add an additional subkey:

Key: Device

Now we are ready to change the value that improves throughput.

Hive: HKEY_LOCAL_MACHINE
Key: CurrentControlSet\Services\aic78xx\Parameters\Device
Value Name: MaximumSGList
Data Type: REG_DWORD
Value: 0xFF

This change works with Adaptec cards and may work with other SCSI adapters, too. As always, make sure you�ve backed up your registry before proceeding.


SOUND

II-43 You just applied the Windows NT 4.0 upgrade and now your audio doesn�t work. Try this registry modification to fix it.

Hive: HKEY_CURRENT_USER
Key: Control Panel\Sound

Make sure the following value exists.

Value Name: Beep
Data Type: REG_SZ
Value: yes

Reboot the system for these changes to take effect

II-44 Your sound card locks up any time you play a .wav file. The only solution is to restart the computer. Try this registry parameter to help solve the problem.

Hive: HKEY_LOCAL_MACHINE
Key: System\CurrentControlSet\Control\GraphicsDrivers

Add the following key under the GraphicsDrivers Key:

Key: DisableUSWC

You don�t need to specify anything else. By adding this key, you tell Windows NT not to use Uncache Speculative Write Combining on the video cards. Reboot the machine for this change to take effect.


HP DESKSCAN II 2.3

II-45 You upgraded to HP DeskScan II 2.3 from version 2.1 or older, and the program doesn�t run. Changing the following registry entries should solve your problem.

Hive: HKEY_LOCAL_MACHINE
Key: System\CurrentControlSet\Services

Add the following Key and the next two values:

Key: Aspi32
Value Name: ErrorControl
Data Type: REG_DWORD
Value: 1

Value Name: Start
Data Type REG_DWORD
Value: 2

Value Name: Type
Data Type: REG_DWORD
Value: 1

II-46 This entry is the second part of installing the new DeskScan II 2.3 software.

Hive: HKEY_CURRENT_USER
Key: Control Panel\Mmcpl

Add the following value under the Mmcpl key:

Value Name: HP_Scanjet
Data Type: REG_SZ
Value: %systemroot%\system\hpscnmgr.dll

Reboot your system for these changes to take effect. Windows NT now runs the correct driver.

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