var
 Reg: TRegistry;
 buf : array [0..4] of byte;
 i: Integer;
begin
 Reg := TRegistry.Create;
 try
  Reg.RootKey := HKEY_CURRENT_USER;
  if Reg.OpenKey('\Software', True) then begin
  for i:=1 to 4 do buf[i]:=0;
  buf[0]:=1;
  Reg.WriteBinnaryData('Value', buf, sizeof(buf));
  Reg.CloseKey;
  end;
 finally
  Reg.Free;
  inherited;
 end;
 {...}
end;