[NumLock]

Код:

procedure TForm1.Button1Click(Sender: TObject);
var
  FBoundary: String;
begin
  Randomize;
  FBoundary:='';
  while Length(FBoundary)<8 do
    FBoundary:=FBoundary+Chr(Random(26)+97); // Ord('a') = 97
  Memo1.Lines.Add(FBoundary);
end;