DOS Fn 4404H: IOCTL Receive Control Data from Block Device

                                                         Compatibility: 2.0+ 
 Expects: AX    4404H
          BL    drive number (0=default, 1=A, 2=B, etc.)
          CX    buffer size (maximum number of bytes to receive)
          DS:DX Address of buffer to receive data
 Returns: AX    error code  if CF is set to CY
                Number of bytes actually received (if no error)
    Info: Some block device drivers support this method of providing
          device-specific information to programs; for instance, it is used
          to tell DoubleSpace to flush its cache.  The layout and contents
          of the returned data varies from device to device.

   Notes: ■ This fn is supported only if bit 14 of the Device Attribute
            (the rDevAttr field of the driver's DevHdrRec structure) is
            set.  Use Fn 4400H to check this bit.

          ■ DoubleSpace API supports IOCTL strings for some fns.

See Also: Fn 44H (IOCTL)
          Fn 4402H (Receive Control Data from Character Device)
          Fn 4405H (Send Control Data to Block Device)
          DoubleSpace API
          DOS Functions