For example, when a driver communicates with hardware, it manipulates registers to request some desired operation of the device.
例如，在驱动程序与硬件进行通信时，它操纵寄存器以便请求一些所需的设备操作。
2
When the guest operating system's driver peeks and pokes at the memory and hardware registers, software exists underneath to emulate the device (see Figure 2).
在来宾操作系统的驱动程序窥探内存和硬件寄存器时，软件存在于下面来仿真设备（参见图 2）。
3
Suppose your devicedriver must be written from scratch, and you do not have the actual hardware while developing this devicedriver.