unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
Function GetCDList : String;
Var
   I    : Integer;
  Drives: Integer;
  Tmp   : String;
begin
Drives := GetLogicalDrives;
  Result := '';
// units A=0 to el Z=25
  For I := 0 To 25 Do
    If (((1 Shl I) And Drives)<>0) Then
    Begin
      Tmp := Char(65+I)+':\';
      If (GetDriveType(PChar(Tmp))=DRIVE_CDROM) Then
                                   Result := Result+Char(65+I);
     End;
End;
procedure TForm1.Button1Click(Sender: TObject);
begin
    showmessage(GetCDList);
end;

end.