function DD_DS: String; 
var 
  DD: _DISPLAY_DEVICEA; 
begin 
  DD.cb := sizeof(DD); 
  if EnumDisplayDevicesA(nil, 0, DD, 0) then 
    result := String(DD.DeviceString) 
  else 
    result := ''; 
end; 
 
procedure TForm2.Button1Click(Sender: TObject); 
var 
  s: String; 
begin 
  s := DD_DS; 
  if s = '' then 
    s := 'Nicht erkannt' 
  else 
    s := 'Grafik-Karte: ' + s; 
  showmessage(s); 
end;