Configuring Windows Explorer
Registry Overview

With the introduction of Windows 95, Microsoft moved most configuration data from the *.ini and *.cfg files into the registry. (It is my firm opinion that this was done primarily as a means of copy protection.) Then Microsoft placed strong warnings everywhere that users should never directly edit the registry because a single error could render a machine completely inoperable. (Unfortunately, this is true.)

This section provides an overview of just that section of the registry which applies to the file associations and Windows Explorer context sensitive menus.

The registry is divided into sections called Hives. (Perhaps this reflects the idea that Microsoft is the master (queen bee) and that all other applications are drones (slaves). Or perhaps it is simply that the registry is honeycombed with data.)

Physically, most of the Windows 95 registry is stored in 2 files - user.dat & system.dat. In theory,

The sizes (above) are only the current sizes on my machine. They are given only as an example. As far as I can tell, they are modified every time the system is used and they only grow. It seems like deleted data is stored and the empty space is not reclaimed. For example, the size of software (below) is 2,396 KB, but that software.reg is only 1,395 KB. The size of data in the registry should be smaller than the same data in a text file.

On Windows NT 4.0 (and above), a different file structure is used. There appear to be 2 Default files. It is not clear how these are related.

KeyFileNT 4 Size XP Size
c:\winnt\profiles\{userID}\Ntuser.dat 444 KB
3,328 KB
HKEY_USERS\.DEFAULT c:\winnt\profiles\Default User\Ntuser.dat 200 KB
232 KB
HKEY_USERS\.DEFAULT c:\winnt\system32\config\default
136 KB
1 KB
512 KB
1 KB
HKEY_LOCAL_MACHINE\SOFTWARE c:\winnt\system32\config\software
2,396 KB
1 KB
12,800 KB
1 KB
HKEY_LOCAL_MACHINE\SYSTEM c:\winnt\system32\config\system
1,580 KB
1,580 KB
4,352 KB
HKEY_LOCAL_MACHINE\SECURITY c:\winnt\system32\config\security
32 KB
1 KB
256 KB
1 KB
HKEY_LOCAL_MACHINE\SAM c:\winnt\system32\config\sam
24 KB
4 KB
256 KB
1 KB

On a NT 4 Service Pack 4 system (Nov 2000), the software key (hive/file) was 9,580 Kb, the exported text file was 6,429 Kb. No wonder the system gets slower as you use it. (Compare this value to that for a new machine in the table above - 2,396 KB.)

Watch it, XP is a pig. The software hive grew from 2 meg (Win NT 4) to 13 Meg. Note also that the user profiles have moved from the windows directory to

Some Microsoft applications still use ini files. For example A search on my Windows 95 system lists 101 ini files in c:\windows and its subdirectories.
My Windows NT system has 34 ini files in c:\winnt and its subdirectories.
One Windows XP system has over 40 ini files in c:\windows and its subdirectories, over 500 on the system - 92 of these are desktop.ini.

hkey - hive key or handle to a key

Is hive the file or the registry key - NT 4.0 help says that it is a file

The primary source of registry information is c:\windows\inf\shell.inf. At the bottom of INF files are the Localizable Strings which can be customized for various languages.