## Graphics Adapter Device Driver Reference

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### Video Manager (VMAN)

This section describes how the Video Manager (VMAN) component fits into the GRADD model.

When VMAN is initialized, a series of components are loaded and initialized . These components include SOFTDRAW and the GRADDs required for the available graphics adapters (each graphics adapter may require more than one GRADD).

The GRADD model supports multiple GRADDs. If a developer wants to extend the GRADD model or to filter out operations, a filter GRADD can be placed between VMAN and the primary GRADD running the hardware. This form of linking GRADDs is called chaining and provides a way of modifying a GRADD's behavior without rewriting and recompiling the GRADD. "Adding Extensions" in Graphics Adapter Device Drivers discusses the specifics involved when extending the GRADD architecture.