PHW_DEVICE_EXTENSION HwDeviceExtension,
      ULONG ModeNum

Routine Description:

    This routine is the main execution routine for the miniport driver. It
    acceptss a Video Request Packet, performs the request, and then returns
    with the appropriate status.


    HwDeviceExtension - Supplies a pointer to the miniport's device extension.

    ModeNum - Index of the mode in which the adapter must be programmed.

Return Value:

    NO_ERROR if the function completed successfully
    ERROR_INVALID_PARAMETER if the requested mode is invalid for the device.