## Graphics Adapter Device Driver Reference

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### VIDEOCFG.DLL Exported Functions

The VIDEOCFG.DLL shared library represents the video configuration module in OS/2. Resolution, monitor, and refresh configuration methods are standardized, meaning that IBM- and vendor-shipped drivers for different video devices have the same user interface for the video configuration. The configuration of the resolution is handled by Page 1 of the System Icon notebook. The monitor configuration is handled by Page 2 of the System icon notebook. Page 2 is offered whenever the PMI subsystem contains timing information in its mode table and the attached monitor does not support the VESA DDC standard. For DDC monitors, Page 2 is not offered, because the DDC standard provides a software interface for retrieving monitor specifications and no user interaction is required.

Resolution listbox entries are based on the mode table supported by the display driver, as retrieved via the DspQueryDisplayResolutions API. Refresh listbox on Page 1 is offered for each display driver supported mode that has timing information (VerticalRefresh other than 0xFFFF) in the PMI subsystem mode table.

User configuration is recorded at closing of the System object in VIDEO.CFG , a private profiling file. This is a flat file with syntax similar to that of the PMI. The very first VIDEO.CFG is created by the SVGA.EXE utility ( both the IBM-shipped version and the SVGAOEM.EXE provided in the DDK for vendor modification) and reflects the detected monitor configuration at install time. The only generic monitor detection built into the utility is that of the VESA DDC standard. For adapter-specific current monitor configuration, the utility has to be modified to "read" the current settings. An alternative approach is to choose and hard code some standard settings as the default monitor configuration. All of the legacy monitors, as well as the original default settings, are stored in the monitor database. The monitor database is composed of MONITOR.DIF and the optional PRIVATE.DIF. The PRIVATE.DIF can be created by vendors performing RIPL install who prefer to leave MONITOR.DIF as a read-only file. .DIF files are flat files with PMI-like syntax and can be edited to correct or add new legacy monitor entries.

VIDEOCFG.DLL also supports a generic display driver configuration, which allows display drivers to declare one or more settings, the type of each setting, possible values, as well as current value of each setting. When the display driver does have a need to handle some user interface, this feature is the preferred method to any custom configuration. The reason it is preferred is that, in the future, with dynamic resolution change and adapter change, the configuration manager will be able to save and restore all of the display driver custom settings. Note that VIDEOCFG does not attempt to understand the nature of each setting, nor is it performing any profiling of the setting changes.

When the feature is exported by the display driver via a DevEscape (see Generic Video Configuration Interface), VIDEOCFG provides a "Capabilities" button on Page 1 that opens a notebook with one page dedicated to each declared setting. Help for each setting, if desired, has to be exported by the display driver via a resource module and a resource ID for the help. As the user makes changes to the settings, the display driver is notified at the time the System Icon changes and is responsible for recording ( profiling) the new value. Each time the pages of the settings are opened, VIDEOCFG will query the display driver for the current value of each exported setting.

Current monitor and mode configuration can be queried and changed via the VIDEOCFG's exported APIs, all of which are listed here and prototyped in h\svgadefs. h.