In the case of an IRP_MJ_READ to a programmed I/O (PIO) sort of device, the access might take the form of a read operation directed to an I/O port or a memory register implemented by the device.

• 在这种情况下，（对于）一个程序I/O(PIO)类设备的IRP_MJ_READ，这种访问可能采取这种形式：直接对一个I/O端口的读操作或者通过设备执行一个内存注册。