procedure TForm1.Button1Click(Sender: TObject);
const Source: string = '4D 5A';
var S: string;
 t: Integer;
begin
 with TStringList.Create do
 try
  Text := StringReplace(Source, #32, #13#10, [rfReplaceAll]);
  S := '';
  for t := 0 to Count - 1 do
  S := S + Chr(StrToInt('$' + Strings[t]));
  ShowMessage(S);
 finally
  Free;
 end;
end;