The Registry 4: Control, Part 3
At HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\ we find thevalues for controlling the system. Some of these were covered in the previous two articles, Control Sets and Session Manager . In this article and the nexttwo we will look at the rest of these variables.
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Caution: Editing the registry can be extremely dangerous and candisrupt your system to the point where your only option is to re-install Windows NT. |
Refer to the article Registry:Basics for information on safe handling of the registry.
Many of the \Control value entries are necessary for the system tostart, so you must be careful if you make any changes and always make sure you have backed up the registry properly.Most of these parameters can be controlled through Control Panel; where that is possible, it is the best way tomake changes. Changes in this area almost always require a reboot to take effect.
Convention: Keys and Sub-keys are bold-face ( \ComputerName );value entries are in italics ( ComputerName ). Also, note that some of these variables may not appear in yourregistry; they can be added if needed, but make sure you spell and capitalize them correctly.
The Control Value Entries
CurrentUser, REG_SZ. This is for holding the username of you,the user who is currently logged on.
RegistrySizeLimit, REG_DWORD, Default 8 megabytes, 25% of PagedPoolSize ( \CurrentControlSet \Control \SessionManager \MemoryManagement ). This is the amount of memorythat can be used for registry data. It can range from 4 megabytes up to 80 percent of PagedPoolSize .The value is entered as the number of bytes, not the number of megabytes. If you increase PagedPoolSize ,this value will also increase. A value of 0xFFFFFFFF sets RegistrySizeLimit to 80% of PagedPoolSize .
SystemStartOptions, REG_SZ. If the firmware passes system argumentsto the system, they are listed here. You will not need to change anything here.
WaitToKillServiceTimeout, REG_SZ, Default 20,000 milliseconds(ms). Sets how long the service control manager will wait for each service to complete the shut-down request.
The Control Sub-Keys
There are more than thirty sub-keys under \Control .Some will not appear in your registry, but can be added if you need them. Some have enough sub-keys of their ownto fill a whole article. I am not covering them alphabetically, so dont be concerned if I seem to skip a few; thereare several more articles coming.
\BootVerificationProgram
ImagePath, REG_SZ or REG_EXPAND_SZ, Defaults to blank. Thisvalue entry contains the path and filename of the program which the service controller uses to verify the LastKnown Good configuration.
If you change this from the default, you must also go to HKEY_LOCAL_MACHINE\SOFTWARE \Microsoft \Windows NT \CurrentVersion \WinLogon and set the value entry ReportBootOK (REG_SZ) to zero. These sub-keys should be left at the default unless you are quite certain you know what you aredoing. For one thing, you will probably have to write the program it calls.
\Class
You will find a dozen or more sub-keys under \Class ,each with a cryptic name. Don't worry about them, because, like most \Control entries, you shouldnot modify them. These sub-keys define devices such as keyboard, mouse, modem, etc., and are modified from ControlPanel.
\ComputerName: This has two sub-keys, \ActiveComputerName and \ComputerName (yes, the name is identical). The value entry ComputerName, REG_SZ, willbe in the first sub-key, and may be in the second. This is the network name of the computer. You can change itin \Network \Identification .
\FileSystem: Contains four value entries:
NtfsDisable8dot3NameCreation, REG_DWORD, Default 0. Allowslong file names on NTFS partitions. If you set this value to 1, long file names cannot be used on your NTFS partitions.If Windows NT is taking a very long time to process directories, it may be due to having a large number of longfile names. If so, setting this value to 1 may speed up the directory processing. On the other hand, you will notbe able to use long file names, and you will not be able to use MS-DOS shortcuts that have long file names.
NtfsDisableLastAccessUpdate, REG_DWORD, Default 0. WheneverWindows NT accesses a file or folder, even if its just to display the name in a list of folder contents, the LastAccessed Date is updated. If you normally deal with large numbers of files and folders, this could slow you down.To disable this feature, set this value to 1.
Win31FileSystem, REG_DWORD, Default 0. Controls whether theFAT will allow creation, enumeration, opening, or querying of long file names, and whether extended time stampinformation (CreationTime and LastAccessTime) is stored and reported. This value defaults to 0; set it to 1 (true)to revert to basic Win3 x (and Windows NT 3.5) semantics. Note: Changing this value does not change any diskstructures. It simply changes how the system behaves from now on. You must reboot the system for a change to thisvalue to take effect.
Win95TruncatedExtensions, REG_DWORD, Default 0. When set to0, this makes all file extensions look like 3-character extensions. Thus, Windows NT would consider all of theseextensions to be the same: .LIS, .LIST, .LISTS, .LISTED, .LISTING, and so on. Any action done on *.LIS would beperformed on all of these files. To disable this feature, set this value to 1.
\Keyboard Layout:
KeyboardLayout, REG_SZ. This key contains the name of the .DLLfile, which the system loads to map your keyboard. You will probably never need to change this. It contains twosub-keys:
\DosKeybCodes: This contains a set of value entries,each of which is an MS-DOS style layout name. The system uses it to convert Windows NT layout names. Each valueentry is the code. For example, US is 00000409. Note that these are text strings, so the value type is REG_SZ.
\Substitutes: If a particular user prefers a keyboardlayout which is different from the default, the code for the layout is recorded here. When that user logs in, thesystem loads the corresponding .DLL file. As under \DosKeybCodes , each value entry is the code.The type is REG_SZ, Default is blank.
\Keyboard Layouts: Under this key we have a sub-keyfor each layout name, (as listed in \Keyboard Layout \DosKeybCodes ). Each sub-key contains twovalue entries:
LayoutFile, REG_SZ. Contains the name of the .DLL file.
LayoutText, REG_SZ. Contains the name of the keyboard layout.
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