25.3 Updating the SYSTEM.INI File

Upon installation, the [drivers] section of the SYSTEM.INI file contains an entry for each installable driver. This entry has the following form:

entry=driver_filename optional_information

An application can open a driver by using its filename or its entry. If a fully qualified path is not specified with the filename, the driver file must exist on the standard Windows search path. The driver interface searches for the driver as follows:

If an application specifies a section name, that section of SYSTEM.INI is searched instead of the [drivers] section.

If an application specifies an entry in the search section, the driver with a filename corresponding to the entry is opened.

If the string specified by the application does not match an entry in the search section, the system assumes the string is a driver filename.

The optional information (optional_information) following the driver name (driver_filename) lists information a driver needs after installation. A driver maintains configuration information here if the information is limited or if it needs to be associated with the entry. For example, two prototype drivers could be installed in the system. The first driver could be associated with serial port one, and the second driver could be associated with serial port two. The [drivers] section of the SYSTEM.INI might show this association in the following way:

[drivers]
prototype1=proto.drv com1
prototype2=proto.drv com2

If your driver uses more extensive configuration information, it can create a section in the SYSTEM.INI file reserved for its parameters. For example, the installable driver PROTO.DRV might create the following [proto.drv] section:

[proto.drv]
port=230
int=3

When reserving a section for your driver, use the filename of your driver to identify the section. A driver usually configures and maintains this section of information when it displays the configuration dialog box used for the DRV_CONFIGURE message.

If you want your installable driver loaded when Windows starts, place its filename or an alias from the [drivers] section of the SYSTEM.INI file on the drivers= line of the [boot] section found in the SYSTEM.INI file. Windows loads these drivers at startup and sends DRV_LOAD and DRV_ENABLE messages to them but does not open them. This makes it possible for you to install drivers that remain resident while Windows is enabled.