Как узнать букву CD-ROM?

Code:

function GetFirstCDROMDrive: char;

var

  drivemap, mask: DWORD;

  i: integer;

  root: string;

begin

  Result := #0;

  root := 'A:\';

  drivemap := GetLogicalDrives;

  mask := 1;

  for i := 1 to 32 do

  begin

    if (mask and drivemap) <> 0 then

      if GetDriveType(PChar(root)) = DRIVE_CDROM then

      begin

        Result := root[1];

        Break;

      end;

    mask := mask shl 1;

    Inc(root[1]);

  end;

end;

procedure TForm1.Button2Click(Sender: TObject);

begin

  ShowMessage(GetFirstCDROMDrive);

end;