open the COM1 port

Com port is treated as file in Win32. So use CerateFile Win32 API function to open file and ReadFile and WriteFile to read/write data from/to port.

  HANDLE hPort = ::CreateFile
  ( _T("COM1"),
            GENERIC_READ | GENERIC_WRITE,
            0,    // exclusive access                
            NULL, // no security attributes
            OPEN_EXISTING,
            FILE_ATTRIBUTE_NORMAL,
            NULL  // No template
  );