CreateFile,WriteFile,CloseHandle,GetSystemDirectory

var
  Qchar:array[0..254] of Char;
  handle:HFILE;
  WriteNo:DWORD;
begin
  getsystemDirectory(Qchar,255);
  handle:=CreateFile('SystemRoot.txt',
    GENERIC_WRITE,
    0,
    0,
    CREATE_ALWAYS,
    FILE_ATTRIBUTE_NORMAL,
    0);
  if handle<>INVALID_HANDLE_VALUE then
  begin
    if WriteFile(handle,qchar,lstrlen(Qchar),WriteNo,0) then
      ShowMessage(IntToStr(GetLastError));
  end;
  CloseHandle(handle);
end;