https://qooah.com/2011/06/02/acer-iconia-a100-%e4%b9%9f%e4%be%86%e5%8f%83%e4%b8%8a%e4%b8%80%e8%85%b3%e5%8f%af%e6%83%9c%e5%8f%aa%e6%9c%89-android-2-2/