PC Hardware

The Registry

As explained in Lesson 1, the Registry is a common database composed of two binary files: SYSTEM.DAT and USER.DAT, which are located in the Windows directory. Inside the Registry is information on all the hardware in the computer, network information, user preferences, and file types, as well as virtually anything else you might run into within Windows 95.

The Registry is intended to replace CONFIG.SYS, AUTOEXEC.BAT, and every .INI file. However, Windows 95 still reads all .INI files at boot up for backward compatibility with Win 3.x programs that need them.

Why the Change in Windows 95?

Windows 3.1x supported two kinds of .INI files: system initialization files and private initialization files. System initialization files controlled the Windows environment and included SYSTEM.INI and WIN.INI. Private initialization files included CONTROL.INI, PROGMAN.INI, WINFILE.INI, and PROTOCOL.INI, as well as any application .INI files. Initialization files created a bridge between the application and the Windows operating environment.

In addition to .INI files, Windows 3.1 used a host of other text files to manage operations. The files included AUTOEXEC.BAT and CONFIG.SYS. It was conceivable for a user to have more than 150 files responsible for the operation of the computer and the Windows environment.

During the development of Windows 3.11, it became apparent that a move away from the .INI files was needed. A new file type was introduced into the programming environment. The file was called REG.DAT and was the precursor to the Windows 95 Registry. REG.DAT included information used for drag-and-drop operations, object linking and embedding (OLE), and establishing associations between data files and their programs.

The binary file REG.DAT was bundled with its editor, REGEDIT.EXE. While this began the process of centralizing computer operations, REG.DAT came with some serious size limitations. It could not exceed 64 KB, which is the same limit established for the .INI files in Windows 3.11.

Accessing the Registry

The recommended way to access the Registry is through the Control Panel. It lets a user modify settings with an easy to use interface that never even mentioned the word Registry. In Windows 3.x, most such changes required modifying the SYSTEM.INI file.

Everything necessary to configure the system so that it will work can be handled from the Windows 95 Control Panel. The three areas where Windows 95 preferences/settings can be viewed and configured are the Control Panel, the System Monitor, and the Registry.

Directly changing an entry (to be done only by a knowledgeable user) is accomplished with the Registry Editor, REGEDIT.EXE. To open it, type REGEDIT at a command prompt. This can be obtained by typing the command in the dialog box that appears when you choose Run from the Start menu. The Registry itself is stored in binary format, so you can't open, view, or edit the contents directly.

Microsoft tried to make the Registry as inaccessible as possible. The fact that the Registry is the central repository creates its principal weakness-once it has been corrupted, it's hard to recover settings if they haven't been backed up.

The Registry is stored in three locations:

  • SYSTEM.DAT: Stores most of the data, including the majority of hardware and software configurations.
  • USER.DAT: Stores data about a particular user.
  • The Virtual Registry: Consists of a host of files that are created by Windows 95 when the system is started up. They are stored in RAM. These settings relate to many of the performance-monitoring tools such as PVIEW.EXE.