type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  end;

  MyThread = class(TThread)
  private
      ig:Integer;
  protected
      procedure Execute; override;
      procedure UP;
  end;

var
  Form1 : TForm1;
  MT    : MyThread;

procedure TForm1.Button1Click(Sender: TObject);
var
   i,j,zzz : Integer;
begin
   MT:=MyThread.Create(False);
//симуляция вычислений
   for i:= 1  to  20000  do
       for j:= 1  to  5000  do
           zzz:=round(i/j);
end;

procedure MyThread.Execute;
var k : Integer;
begin
   for k:= 1  to  20000  do
     begin
        ig:=k;
        sleep( 200 );
        Synchronize(UP);
     end;
end;

procedure MyThread.UP;
begin
   Form1.Edit1.Text:=IntToStr(ig);
end;

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Button1: TButton;
    ProgressBar1: TProgressBar;
    procedure Button1Click(Sender: TObject);
  end;

  MyThread = class(TThread)
  private
      ig:Integer;
  protected
      procedure Execute; override;
      procedure UP;
  end;

var
  Form1 : TForm1;
  MT    : MyThread;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
   Form1.Button1.Enabled:=False;
   ProgressBar1.Position:= 0 ;
   ProgressBar1.Max:= 1000 ;
   ProgressBar1.Step:= 1 ;
   MT:=MyThread.Create(False);
   repeat
       Application.ProcessMessages;
       ProgressBar1.Position:=ProgressBar1.Position+ProgressBar1.Step;
       if ProgressBar1.Position=ProgressBar1.Max then
          ProgressBar1.Position:=ProgressBar1.Min;
       Sleep( 5 );
   until MT.Terminated;
   ProgressBar1.Position:=ProgressBar1.Max;
   ShowMessage('Конец процессу!');
   Application.Terminate;
end;

procedure MyThread.Execute;
var i:Integer;
begin
   for i:= 1  to  100  do
       begin
          ig:=i;
          Synchronize(UP);
          sleep( 100 );
       end;
   MT.Terminate;
end;

procedure MyThread.UP;
begin
   Form1.Edit1.Text:=IntToStr(ig);
end;