Windows Registry

**Hardwareman** · 28-06-2008

Introduction

Central element of Windows since Windows NT and 95 (even if it already existed in Windows 3.1, with a more restricted role), the registry is a great unknown for a number of users. Among the common places that are circulating about him, you know vaguely that it grows as installations, and it would be a factor worsening performance of Windows, which in extreme cases, led to its relocation. However, if one examines them, it provides a number of important information on the system, and lets you modify certain parameters, namely the condition of use.

To see more clearly, we offer an overview of the registry: what is it, how it is structured, what are the important elements… We will try to answer these questions, and that the questions raised about its growing problems of size and potential impact this may have on performance.

Warning: the words and concepts that we will detail in this article may be too technical for a neophyte user. Modify the registry of Windows is a complex task that can lead to instability in the system or make it unusable. If this is your case, do not run in this operation without the guidance of an expert.

Definition of the registry
The registry database contains, all information relating to the configuration of Windows: Windows settings and applications built into the system, third-party software settings, preferences of different users of the system or file associations are stored. The base replaces the many text files containing such information in MS DOS and Windows 3.x (Autoexec.bat, Config.sys and other files. INI). Windows includes the famous course Regedit to view and edit the content. Little detail: even if we talk about Windows registry in our article, the term is commonly used, Microsoft generally uses the term Register.

Before embarking on the exploration of each key, it also seems important to explain the different types of data that may be encountered in the database. A directory of the registry is called a key. The key may contain different data:

REG_BINARY: binary data figures it is strongly discouraged editing. These data are easy to spot in the editor: they present themselves as "ff 00 05 00 01 02 00 ... » "
REG_DWORD: coded data from 32 bits, which can take the form decimal or hexadecimal
REG_SZ: strings, frequently used in the base. It should be noted two other types of chains of character: the type REG_MULTI_SZ chains may contain several channels, while chains such REG_EXPAND_SZ are scalable and can contain variables.

Structure of the registry

The registry database is broken down into 5 main sections. Each section contains information relating to a category of parameters. These sections are also known as hives ( "Hives"), but they are more commonly called "key" in referring to sub-categories as sub keys.

HKEY_LOCAL_MACHINE
Also called HKLM, this branch includes mainly the system and equipment parameters such as security settings, adjusting software built into Windows and third-party software, access roads to applications, information on the hardware configuration or some parameters network. In examining the tree, there are including the following keys:

HARDWARE: this subkey includes information on the hardware configuration, as detected by the Windows startup. By deploying in the sub-category Description, for example, you can find information on the processor, as reflected in the panel system from Microsoft. It is also in DeviceMap and RessourceMap, information on devices and system resources. The key is generated each startup from material detected.
SECURITY and SAM: both contain key information on user accounts. he key change is impossible, even for a system administrator.
SOFTWARE: as its name suggests, the key Software contains parameters relating to software included in Windows, as well as third-party software. It should be noted that in deploying the keys are held under the tree Publisher / Software. The parameters present in the key SOFTWARE are parameters that apply to all users. Other parameters specific to the user find the keys HKEY_USERS or HKEY_CURRENT_USER.
SYSTEM: this subkey contains parameters equipment and system information, such as pilots or system memory. It should be noted that under contains two key games configuration, Windows always using the latest game configuration has not been a problem.

HKEY_ USERS and HKEY_CURRENT_USER
This branch is called usually HKU contains information about users of the system. There are parameters including the appearance of Windows, setting accessibility, location, account settings Outlook Express / Windows Mail, user settings for software, or even parameters printing. By deploying the key HKEY_USERS, we notice several entries, including a first entitled DEFAULT. This entry contains default settings that will apply to all users of the system. There are also entries for the different users of the machine, whose current user, which is also the root of the key HKEY_CURRENT_USER (HKCU) The information for each user break down as follows:

AppEvents: records the sounds associated with events Windows
Console: all the parameters windows command line (MS-DOS) as colors, fonts or size of the cursor
Control Panel: includes all settings in the Control Panel (mouse settings, desktop theme, colors and accessibility, international parameters ...
Identities: includes parameters Outlook Express / Windows Mail
Keyboard: information on the keypad
Printers: information on printers installed
Session Information: displays the number of applications open
Software: contains certain parameters users installed applications. This section is not the Software section of the key HKEY_LOCAL_MACHINE that stores software parameters valid for all users: here, the parameters are specific to the user in question. We find the same tree Publisher / Software.

HKEY_CLASSES_ROOT
This section contains all information relating to the combination of different types of files with applications that launch from the explorer. It is the merger of two information subkeys: HKEY_LOCAL_MACHINE \ Software \ Classes and HKEY_CURRENT_USER \ Software \ Classes. The tree lists the various file extensions and programs associated with them. In fact, this brings together key information from two other locations: HKEY_LOCAL_MACHINE \ Software for associations applying default, and HKEY_CURRENT_USER \ Software for the parameters that apply to the user, the latter being the first priority.

Changing the information contained in this key allows to specify the applications necessary to open a certain file type. The information contained correspond to the possibilities offered options since records Explorer in Windows XP (File Types tab) or from the panel Programs default in Windows Vista: the applications that support the extension (called "Applications recommended" when you change a file associations in the explorer), but also the actions associated with a file type (reading, opening new…).

HKEY_CURRENT_CONFIG
This branch is a copy of the information contained on the site HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Hardware Profiles \ Current. It gathers information on the hardware profile in use. This information is collected to start the PC.

**Hardwareman** · 28-06-2008

Cleaning the Windows registry

The registry database tends to swell as the installation of software, and even their uninstall it does not necessarily performed very own. The resulting registry keys obsolete who meet unnecessarily. Each problem necessarily inspiring Windows software publishers, the basic problems that afflict Windows registry have generated a market for cleaners registry database and this for years now. Some are tools specifically for this task as CCleaner or Registry Mechanic, others are included in broader solutions Cleaning Windows (TuneUp Utilities, System Mechanic, Glary Utilities ...)

What can be done to clean the registry? The software cleaning act by removing keys they deem unnecessary, for example referring to applications that are no longer installed on the system. The case is quite common: despite the "clean" deemed modules uninstall software, thank you Windows Installer, it is often traces, including the level of user settings contained in sections HKEY_USERS or HKEY_CURRENT_USER.

The gain of performance obtained after cleaning the registry, particularly at the time of startup, is the main selling point of these programs. However, many reservations have been made in recent years on the effectiveness of this action at this level. Several experts have concluded that this transaction brings real results in Windows 95, 98 or Me, but much less evident on NT-based systems, including Windows XP and Vista.

While trying to see things more clearly, we conducted a test on a Dell PC Vostro 200 Core 2 Duo 2.20 GHz with 2 GB of RAM, hard disk of 300 GB (206 GB free) and Windows Vista Service Pack 1. The PC in question is used on a daily basis and has already "suffered" many facilities and uninstalled software. We have not carried out a resettlement of "clean" system for the purposes of the test, nor installed and uninstalled software specifically for the purpose of artificially reducing its performance. The PC takes about 65 seconds to start (average obtained from three successive measures)

In this configuration, we used the module cleaning registry TuneUp Utilities 2008. It locates 1362 errors, mostly on key historical files. After cleaning mistakes, gain performance at startup is totally imperceptible: the start is even slower than a second on our measurements (66 seconds). These are not to take the letter, the startup may be random. However, this test shows no noticeable performance gain. Good point, however, for stability: it does not seem that it has been impacted by the errors repaired. In addition, registry cleaners database generally offer an option to save and restore the base, if dysfunctional manifested.

If the performance had no gain, then why take the risk to clean up its registry database? This question can be answered that it helps to clean house in a database that can become confused if one is forced to search for information: uninstall modules that are not always clean properly, you can end up with entries who have nothing more to do. For the user who does not pass his life in Regedit, it is not very useful, but as was mentioned in particular Mark Russinovich (founder of Sysinternals, since bought by Microsoft), it is quite different for a system administrator. It may also raise the argument of saving in disk space: Just as the removal of temporary files and other historical, cleaning the registry can save up disk space, even negligible, and reduce memory footprint thereof, leaving more for other applications. But in no circumstances could consider this operation as a panacea to make your PC's performance yesterday, at least not on recent versions of Windows.

Some tips to customize Windows

Finally, we offer some tips operating the registry database to customize certain details of Windows, whose settings are inaccessible in the tools offered by default. These are very numerous and draw up an exhaustive list would be impossible. Nevertheless, here are a few that we tested with Windows Vista and Windows XP. Before applying these changes, remember to save your base. For that, Regedit proposes an export function in the File menu. The dialog box offers several levels of export branch under exploration or "All". Choose the second option to save the whole database in the form of a file. REG that you can place it in the folder of your choice. Similarly, to restore it, you just have to execute this file. REG.

This method is not necessarily the most effective because it means as we still have access to Windows to launch Regedit and restore the file. If you are unable to start the system, it will have made backups of the files. The case is complicated somewhat because the registry is contained in several files, which is spread over different locations. Most files are in the Windows folder \ System32 \ Config. These files headings:

COMPONENTS
DEFAULT
SAM
SECURITY
SOFTWARE
SYSTEM

The file corresponding to the branch HKEY_CURRENT_USER is to be found in the directory of the user. The file is ntuser.dat and it is hidden by default (remember to show hidden files and folders in Explorer). If multiple users are registered, you will need to recover the ntuser.dat file of each user. To restore files, it will replace the damaged files on your backups, for example via the console recovery of Windows XP.

Move the menu bar of Internet Explorer 7
If Internet Explorer 7 available for Windows XP, its ergonomics was thought to Windows Vista, and the tendency of Microsoft was to hide, by default bar menu in Internet Explorer. It is possible to view, but this one is found between the navigation bar and bookmarks bar, which is not the location is expected in Windows XP, and without being able to move Even when the toolbars are not locked. To put it "in the right place, you can go through the registry. Go to the following location in the tree: HKEY_CURRENT_USERS \ Software \ Microsoft \ Internet Explorer \ WebBrowser. Then, create a new DWORD (Edit> Create> DWORD value) that you call ITBar7Position. Right click to edit and assign it a value of 1. Start IE7 and Bang. Note that this manipulation works under Windows Vista, but then breaks the seamless interface of IE7. Anyway, this behavior is rather inconvenient for users of Windows XP.

Remove the arrows on shortcut icons on Windows Vista
Without wanting to cut their hair into four, small arrows added to the shortcuts are absolutely enormous in Windows Vista. However, no option panel can not remove them. A solution using the registry exists. It nevertheless requires downloading a prior blank icon that you find here. Unzip the contents of the archive in the Windows directory. Then, in the publisher of the registry, go to the location HKEY_LOCAL_MACHINE \ Software \ Microsoft \ Windows \ CurrentVersion \ explore. Create a new key named "Shell Icons." In this key, create a new string and then call 29. Finally, change and assign him the value% SystemRoot% \ noarrow.ico, 0. The file noarrow.ico must lie at the root directory of Windows, which corresponds to the variable% SystemRoot%. The amendment is taken into account after the restart Windows. A note, if you already use TuneUp Utilities, this modification is part of the "tweaks" proposed by the software (as well as other similar tools). In TuneUp, you can find in the module TuneUp Styler, according to the "Icons" on the side panel, then choosing the "Appearance". If you do not TuneUp, you can find a software, a small tool and very appropriately named Vista Shortcut Overlay Remover quite functional to implement this change without affecting the base.

Reducing the time required to settle Windows
If you find the length of extinction Windows too long, it is possible to reduce it by acting on the time before the closure of services. one is set by default to 20 seconds. This data is in the registry at the site HKEY_LOCAL_MACHINE \ System \ CurrentControlSet \ Control, which contains a string entitled WaitToKillServiceTimeout. This time is expressed in milliseconds: to reduce it to 5 seconds, give him a value of 5000. The change takes effect immediately.

Disable alerts in case of disk space low
Windows warns the user when disk space is low, which is quite normal. However, these alerts rather insistent can quickly cause some annoyance. To disable them, we must get to the location HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Policies \ Explorer, and then create a DWORD value entitled NoLowDiskSpaceChecks, and assign a value of 1. You should then have peace.

Disable "pop-up" for sites in HTTPS
Internet Explorer offers a tool for blocking pop-up that may prove practical to block certain advertisements too invasive. To enable nevertheless display these windows on secure sites whose URL starts with "https: / /", go to the location HKEY_CURRENT_USER \ Software \ Microsoft \ Internet Explorer \ New Windows. You'll find an item titled Allow HTTPS, which you only have to assign a value of 1. The pop-ups continue to be blocked for sites "standard".

In the interest of the registry

This gives us the opportunity to warn you that the: the registry remains a tool of great complexity, which requires real knowledge to know what to delete or modify. Make a blind trust to tools cleaning the base, without the help of a competent person in this area can be quite dangerous, as well as modify a parameter of a key can have an impact on the stability of the system . Again, cleaners often offer an overview of key considered "obsolete", sometimes accompanied by explanations on why the software considers invalid. Do not hesitate to seek advice from a specialist who will without doubt better guide you on the subject. If you venture in such manipulation, make sure to back the base beforehand. This is possible since Regedit, and expected by most software cleaning, doing some even automatically, with the possibility to cancel the amendments in a single click.