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requires
  rtl,
  vcl;					

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{$ALIGN 8}					

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...
    function GetFreeSize(ADriveLetter: Char): Int64;
    function GetDriverVersion : String;  //<---------------------------
    procedure GetDrives(AList: TStrings; ADriveType: ShortInt); overload;
    procedure GetDrives(AList: TStrings; ADriveType: TDriveTypes); overload;
    property Count: Integer read GetCount;
    property Info[Index: Integer]: TDriveInfo read GetDriveInfo;
  published
    property DriveLetter: string read FDriveLetter write SetDriveLetter;
    property DriveType: TDriveTypes read FDriveType write SetDriveType;
    property Eject: Boolean read FEject write SetEject;
    property DriverVersion: String read GetDriverVersion;   //<---------------------------
  end;
...
function TfrDrive.GetDriverVersion : String;
begin
  Result:= '3.0';
end;
//-------------------------------------------
procedure TForm1.FormCreate(Sender: TObject);
begin
caption:= frDrive1.GetDriverVersion;
end;					

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unit Unit1; //20170318

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes,
  Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, DBT, Vcl.StdCtrls;

type
  TForm1 = class(TForm)
    Memo1: TMemo;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    UsbNotifyInfo : TDevBroadcastDeviceinterfaceA;
    UsbDeviceNotificationHandle : Pointer;
    Procedure UsbDeviceChangeNotification(Var Msg : TMessage); MESSAGE WM_DEVICECHANGE;
    { Private declarations }
  public
    { Public declarations }
    Procedure RegisterUsbNotification;
    Procedure UnregisterUsbNotification;
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure MM(s:string); begin Form1.Memo1.lines.add(s); end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  RegisterUsbNotification;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  UnregisterUsbNotification;
end;

Procedure TForm1.RegisterUsbNotification;
Var
  Error : Cardinal;
Begin
  ZeroMemory(@UsbNotifyInfo, sizeof(UsbNotifyInfo));
  UsbNotifyInfo.dbcc_size := sizeof(TDevBroadcastDeviceInterfaceA);
  UsbNotifyInfo.dbcc_devicetype := DBT_DEVTYP_DEVICEINTERFACE;
  UsbNotifyInfo.dbcc_reserved := 0;
  UsbNotifyInfo.dbcc_classguid := StringToGuid('{A5DCBF10-6530-11D2-901F-00C04FB951ED}');
  UsbDeviceNotificationHandle := RegisterDeviceNotification(self.Handle, @UsbNotifyInfo, Cardinal(0));
  If UsbDeviceNotificationHandle = NIL Then
  Begin
    Error := GetLastError;
    ShowMessage(Format('Registering Device Notification failed, error code: %d', [Error]));
  End;
End;

Procedure TForm1.UnregisterUsbNotification;
Begin
  If (UsbDeviceNotificationHandle <> NIL) Then
  Begin
    UnregisterDeviceNotification(UsbDeviceNotificationHandle);
  End;
End;

Procedure TForm1.UsbDeviceChangeNotification(Var Msg : TMessage);
Var
  device : PDevBroadcastHdr;
  DeviceInfoBlock : PDevBroadcastDeviceInterface;
  MyDevice : String;
Begin
  If Msg.Msg = WM_DEVICECHANGE Then
  Begin
  Winapi.windows.Beep(2000,50);
    If Msg.WParam = DBT_DEVICEREMOVECOMPLETE Then
    Begin
      device := PDevBroadcastHdr(Msg.lParam);
      If device.dbch_devicetype = DBT_DEVTYP_DEVICEINTERFACE Then
      Begin
        DeviceInfoBlock := PDevBroadcastDeviceInterface(Msg.LParam);
        MyDevice := String(Pchar(@DeviceInfoBlock.dbcc_name));
        MyDevice := Uppercase(MyDevice);
       MM('REMOVAL: '+#13#10+MyDevice);
      End;
    End
    Else
    If Msg.WParam = DBT_DEVICEARRIVAL Then
    Begin
      device := PDevBroadcastHdr(Msg.lParam);
      If device.dbch_devicetype = DBT_DEVTYP_DEVICEINTERFACE Then
      Begin
        DeviceInfoBlock := PDevBroadcastDeviceInterface(Msg.LParam);
        MyDevice := String(Pchar(@DeviceInfoBlock.dbcc_name));
        MyDevice := Uppercase(MyDevice);
        MM('ARRIVAL: '+#13#10+MyDevice);
      End;
    End;
  End;
End;

end.					

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caption:= frDrive2.GetVersion;					

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caption:= frDrive2.Version;