The GetLogicalDriveStrings function fills a buffer with strings that specify valid drives in the system.     DWORD GetLogicalDriveStrings(        DWORD nBufferLength,        // size of buffer 
    LPTSTR lpBuffer         // address of buffer for drive strings 
   );    The GetDriveType function determines whether a disk drive is a removable, fixed, CD-ROM, RAM disk, or network drive.     UINT GetDriveType(        LPCTSTR lpRootPathName         // address of root path 
   );    

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 GetLogicalDisks: string;
var
  i,n :integer;
  buf :pchar;
begin
  buf:=stralloc(255);
  n:=GetLogicalDriveStrings(255,buf);
  Result:='';
  for i:=0 to n do
    if buf[i]<>#0 then begin
      if (ord(buf[i]) in [$41..$5a]) or (ord(buf[i]) in [$61..$7a]) then
        Result:=Result upcase(buf[i])
    end else
      if buf[i 1]=#0 then
        break;
  strdispose(buf);
end;    procedure TForm1.Button1Click(Sender: TObject);
var
  s: String;
begin
// Logical devices
  s:=GetLogicalDisks;
  showmessage(s);
end;    end.