一个wdm方式硬盘驱动例子，PIO方式访问硬盘，比较底层访问硬盘的方法，估计目前很少有人去学习ATA协议了，看看还是能学到不少东西。-PIO access to the hard disk, more low-level disk access methods, estimated that very few people to learn the ATA protocol, and to see or to learn a lot.