Unleashing Windows: Understanding the Windows 95 Registry (Part II)

Last time we talked about the Windows 95 Registry covering the basic overview of what it does. We also looked at the different keys in the Registry. This time let's take a look at the Windows 95 Registry subkeys and values.

However, once again, before we begin:

***** CAUTION ******
The Windows 95 Registry is critical to the proper operation of Window 95. In this article, we are just going to look at the Registry structure. However, we are going to look at it using a program called the Registry Editor, which allows modification of the Registry. Do NOT modify any entries in the Registry unless you are SURE of the proper syntax of the entry and what the implications of the entry are. If you incorrectly modify the Windows 95 Registry, Windows 95 will not operate properly or even worse, the Windows 95 system may not start.
********************

As we mentioned last time, the Windows 95 Registry has four types of entries: keys, subkeys, values, and hives. The six keys contained in the Registry are: HKEY_CLASSES_ROOT, HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE, HKEY_USERS, HKEY_CURRENT_CONFIG, and HEKY_DYN_DATA. Now, let's look at the subkeys and values of the Windows 95 Registry.

Registry subkeys are containers for Registry values or other subkeys. The subkeys break up the six main keys into logical groups. Each key has a set of default subkeys, but most systems have additional subkeys depending on the user or applications that are on the machine.

The last levels in the Registry tree structure are values. Values contain the actual configuration information used by the system. The Registry values are similar to the text values used in the Windows 3.1 .INI files. Values are composed of three parts: the value name, the data type and the actual value entry. However, Registry values are not limited to being just text strings, they can have different data types. Values can have the following data types:

BINARY - This data type stores data in raw binary format. Only one value is allowed per entry. It is displayed in hexadecimal format when using the Registry Editor. Hardware component information is typically stored in the raw binary format.

DWORD - This data type is numeric data that is 4 bytes long. Like the BINARY data type, only one value is allowed per entry. This data type is typically used by device drivers and other Windows 95 hardware information.

STRING - This data type is a data string type, also known as readable text. This is the most commonly used data type for non-hardware information. Only one value is allowed per entry.

Finally, hives are the files used to make up the Windows 95 Registry. The Windows 95 Registry uses two files : USER.DAT and SYSTEM.DAT to make up the Windows 95 Registry. The USER.DAT file is made up of user information and configuration settings of that user. If the Windows 95 machine has multiple user accounts, a user hive is created for each user. When a user logs onto the Windows 95 system, the user's USER.DAT hive is used. The SYSTEM.DAT is used to contain non-user specific information, such as hardware devices, etc. Only one SYSTEM.DAT hive exists on for a Windows 95 machine.

This finishes the overview of the major Windows 95 Registry components. Next time, we'll actually look at how the Windows 95 system interacts with the Registry. Of course, in the meantime, you'll probably want to explore the Registry structure further. Just remember not to change any values or any other components of the Windows 95 Registry. You might also want to consider backing up the Registry, if you haven't recently.

Back to the Unleashing Windows Index