A peripheral device of a host computer includes a microcontroller and two virtual devices. The first virtual device passes, to the microcontroller, commands of a first command set from any user of the host computer and preferably also commands of a second command set from only privileged users of the host computer. The second virtual device passes, to the microcontroller, commands of the second set from any user of the host computer. In one physical implementation of the invention, the two virtual devices are implemented as separate physical devices, and the second device is connected to an interface to the host computer only if the user is not privileged. In another physical implementation of the invention, the two virtual devices are implemented in a common physical device, and a sector of a memory of the peripheral device is reserved for handling commands of the second set from non-privileged users.