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REG: Device Driver Entries, PART 5

This article was previously published under Q102992
This article has been archived. It is offered "as is" and will no longer be updated.
The article contains REGISTRY entries for Sound Card and Video Drivers.These subgroups are included:
  • Sound Card Drivers
  • Video Device Driver
    • Video Information in the DeviceMap Subkey
    • Video Device Entries in the Services Subkey
There are 5 parts to the Device Driver Entries article series:

Part 1: Device Driver Entries, containing:
  • File System Drivers and Recognizers
  • Disk, Serial and Parallel Ports
Part 2: Mouse and Keyboard Entries, containing:
  • Microsoft Bus Mouse Port Driver
  • Intel 8042 Port Driver
  • Microsoft InPort Bus Mouse Port Driver
Part 3: Mouse and Keyboard Entries, cont'd, containing:
  • Microsoft Serial Mouse Port Driver
  • Mouse Class Driver
  • Keyboard Class Driver
  • Device Map Entries for the Keyboard and Mouse
Part 4: SCSI Miniport Entries

Part 5: Sound Card and Video Device Driver Entries


Note You can view current settings for these device drivers by choosingthe Devices button in WinMSD.

Sound Card Driver Entries

Usually, sound drivers consist of two parts: a front-end for installationand request processing, consisting of files such as SNDBLST.DLL orSYNTH.DLL; and a kernel driver for communicating with the hardware,consisting of files such as SNDBLST.SYS or SYNTH.SYS.

There is also a helper driver named MMDRV.DLL that transforms most low-level calls to Wave, MIDI, and AUX devices into calls to kernel modedrivers.

These are the installable sound kernel drivers for Windows NT:
Sound Driver   CommentMIPSSND.SYS    MIPS ARCSystem 100/150 built-in soundMVAUDIO.SYS    Media Vision Pro Audio Spectrum 16               and Pro Studio 16MVOPL3.SYS     Synthesizer driver for Media Vision               Pro Audio Spectrum 16 and Pro Studio 16SNDBLST.SYS    SoundBlaster 1.5 and compatiblesSNDSYS.SYS     Windows sound system and Compaq               Business AudioSYNTH.SYS      Ad Lib and OPL3 MIDI synthesizer driver				
For each installed sound driver, several parameters are stored in theRegistry, based on choices made by using the Drivers icon in Control Panel.The following shows the Registry path for sound system driver entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\      Services\SoundDriverName\Parameters				
The actual key name in the Registry is the same as the filename of therelated kernel driver. For example, for SNDBLST.SYS, the key name isSndblst.

Some drivers can write over the values they receive on the basis ofinformation read from the hardware. The following shows some typical valuesfound in the Parameters subkey for sound cards:
Configuration Error    REG_DWORD     0, 1, 2, 3, or 4Specifies an error that occurred during install. This value is onlyrelevant if the driver fails to load. (Not all drivers write thisinformation into the Registry.)Value     Meaning0         Nonspecific error1         Hardware not found (usually the wrong          I/O port was assumed)2         Specified interrupt was incorrect or          did not work3         Specified DMA channel was incorrect or          did not work4         Hardware is present but not workingDmaChannel     REG_DWORDDefines the DMA channel settings for transferring digitized sound.Default: Depends on the sound card-not user-configurable.Interrupt    REG_DWORD     Interrupt numberDefines the interrupt number used by the hardware.Default: 0xa (configured for Interrupt 10)LeftLineInAtten    REG_DWORD     NumberSpecifies the current volume level of the left channel of the line-ininput.Port    REG_DWORD     AddressDefines the I/O port start address used to communicate with the hardware.Default: 0x220 for SNDBLST.SYSRightLineInAtten    REG_DWORD     NumberSpecifies the current volume level of the right channel of the line-ininput.				

Video Device Driver Entries

This section describes the entries for video device drivers under theDeviceMap subkey and under the CurrentControlSet\Services subkeys forspecific video drivers.
Video Information in the DeviceMap Subkey-----------------------------------------				
The hardware device mapping for video is under the following subkey:
This information is volatile and is reconstructed at startup by the videoport driver. It can change from startup to startup based on externalfactors, such as failure to initialize a video adapter or the addition ofother video cards to the system.

This subkey contains the mappings from Windows NT logical video devices tothe physical device they represent in the CurrentControlSet\Servicessubkey. This mapping allows the system to find the right display driver forthe currently installed video device.
%device_object_name%     REG_SZ     Registry path for deviceIndicates the first logical video device is the first physical adapter. Forexample, the following entry indicates that the first logical video deviceis the second physical XGA adapter:Video\Device0 = \Registry\Machine\CurrentControlSet\Services\XGA\Device1				
In this example, the value indicates that the second logical video deviceis the first physical VGA adapter:
Video\Device1 = \Registry\Machine\CurrentControlSet\Services\Vga\Device0				
These values point to entries in the Services subkey, as described in thenext section.
Video Driver Entries in the Services Subkey-------------------------------------------				
The port driver portion of the video driver is hardware-independent andcontains operating system-specific code. Therefore, the port driver,VIDEOPRT.SYS, can support one or more video devices. The Services\Videoprtsubkey has no added parameters, and its standard entries are:
Value Entry     Default valueErrorControl    0x1 (Normal)Group           VideoStart           0x1 (system)Type            0x1 (Kernel driver)				
The specific subkey for each video driver contains all the informationrequired to initialize and program the device properly. If several adapterscan be handled by a single driver, the subkeys Device1, Device2, and so onwill contain information for the other devices. The Registry path lookslike this, where VideoDriverName is the name of a specific video devicedriver:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services     \VideoDriverName\Device0				
The VideoDriverName subkeys for drivers in Windows NT include thefollowing. This is not an exhaustive list:
For example, the following subkey contains information for the firstlogical device of type VGA:
The following values can be set in a video driver subkey.
DefaultSettings.BitsPerPel     REG_DWORD     Number of bits per pixelContains the number of colors for the mode requested by the user. Forexample, for the v7vram miniport, the following value yields a 256-colormode:DefaultSettings.BitsPerPel = 8DefaultSettings.Interlaced     REG_DWORD     0 or 1Determines whether the mode requested by the user is interlaced. Forexample, for the v7vram miniport:DefaultSettings.Interlaced = 0x0 (FALSE)DefaultSettings.VRefresh     REG_DWORD     Number HzContains the refresh rate of the mode requested by the user. For example,for the et4000 miniport:DefaultSettings.VRefresh = 72DefaultSettings.XResolution     REG_DWORD     Number of pixelsContains the width of the mode requested by the user. For example, for theet4000 miniport:DefaultSettings.Xresolution = 1024DefaultSettings.YResolution     REG_DWORD     Number of pixelsContains the height of the mode requested by the user. For example, for theet4000 miniport:DefaultSettings.Yresolution = 768DeviceData     REG_BINARY     Binary codeContains binary data specific to the Windows display driver. For example,for the VGA miniport:DeviceData = 05a0 5075 8ef0 8456 c8ddInstalledDisplayDrivers     REG_MULTI_SZ     Driver namesContains a list of names of display drivers that can function with thisminiport, depending on which mode is selected by the user.				
NOTE: Display driver names do not contain the .DLL filename extension.

The system attempts to initialize the adapter by calling each displaydriver, using the user-selected parameter. If the combination of displaydriver and monitor do not support the mode requested by the user, thedisplay driver fails to initialize and the system tries the next displaydriver. If all display drivers fail to initialize, the system calls thefirst display driver again to set the adapter to any mode it can.

For example, for the et4000 miniport:

InstalledDisplayDrivers = "vga" "vga256" "vga64k"

For the S3 miniport:

InstalledDisplayDrivers = "s3"
Monitor     REG_SZ     Monitor nameThis entry is reserved to contain the name of the VESA VDIF monitorinformation file for the monitor connected to the adapter. No such filesare provided with Windows NT in the current version.				
If a file is supplied and a value is added, the miniport can load this fileto determine the exact timings of the monitor connected to the physicaldevice.

For example, for the XGA miniport, if a NEC4FS monitor was attached to theXGA card:

Monitor = "NEC4fg.vdb"
VgaCompatible     REG_DWORD     0 or 1Determines whether the driver supports all of the VGA functionalityrequired to perform full-screen operations.				
If this value is 1, the driver supports full-screen applications in x86-based computers. If this value is 0, the VGA miniport (described under theVga subkey) will also be used to enable and disable full-screen modes fornon-Windows applications.

As a rule, all drivers for SVGA adapters should set this value to 1,because they must implement all the VGA functionality to perform extendedsave/restore of all registers. A video accelerator designed as anaccelerator working independently of the VGA miniport (via pass-through)can set this to 0 and let the VGA miniport do all the full-screen work.

For example, for the et4000 miniport:
VgaCompatible = 0x1 (TRUE)

For the S3 miniport:
VgaCompatible = 0x0 (FALSE)

This functionality is not required for other computer platforms, such asRISC-based computers, because the VDM sessions are emulated usingNTVDM.EXE, and there are no full-screen sessions.

None of the values should be read by the miniportdirectly -that is, using VideoPortGetRegistry() parameters. All values are only to be read by the window manager andare passed in a DEVMODE structure to the display driver. It is up to theWindows display driver to match these settings with the modes returned bythe miniport driver.
The Windows NT Resource Kit for OperatingSystem Version 3.1.
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Article ID: 102992 - Last Review: 12/04/2015 09:39:07 - Revision: 2.2

Microsoft Windows NT Advanced Server 3.1, Microsoft Windows NT Workstation 3.1, Microsoft Windows NT Advanced Server 3.1

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