Пример TWriter и TReader

procedure TForm1.Button1Click(Sender: TObject);
var
  sWrite, sRead: string[25];

  MyStream: TMemoryStream;
  MyWriter: TWriter;
  MyReader: TReader;
begin

  MyStream := TMemoryStream.Create;
  MyStream.SetSize(4096);
  MyWriter := TWriter.Create(MyStream, 4096);
  sWrite := 'sWriteContents';

  MyWriter.WriteListBegin;
  MyWriter.WriteString(sWrite);
  MyWriter.WriteListEnd;
  MyWriter.free;

  MyStream.Seek(0, 0);

  MyReader := TReader.Create(MyStream, 4096);
  MyReader.ReadListBegin;
  sRead := MyReader.ReadString;
  MyReader.ReadListEnd;
  MyReader.free;

  Label1.Caption := sRead;
  MyStream.free;
end;