[NumLock]

Код:

unit Unit1;

interface

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

type
  TMyThread = class(TThread)
  private
    i: Integer;
  protected
    procedure Execute; override;
    procedure Memo;
  end;

  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  memo1: TMemo;

implementation

{$R *.dfm}

{ TMyThread }

procedure TMyThread.Execute;
begin
  i:=0;
  while i<100 do
  begin
    Inc(i);
    Sleep(Random(100));
  end;
  Synchronize(Memo);
end;

procedure TMyThread.Memo;
begin
  memo1.Lines.Add('*');
end;

procedure TForm1.FormCreate(Sender: TObject);
var
  i: Integer;
begin
  Randomize;
  memo1:=TMemo.Create(Self);
  memo1.Parent:=Self;
  memo1.Width:=ClientWidth;
  memo1.Height:=ClientHeight;
  for i:=1 to 20 do TMyThread.Create(False);
end;

end.