The Device Interface layer provides virtual devices to hide the real or simulated devices used by the
program. The mid-level design of this layer merely adds the devices conforming to the interfaces
specified at the architectural level of detail. The diagram in Figure B-11-9 includes various “real” device
classes. These are placeholders for one or more device drivers for actual hardware devices.
The mid-level static structure of the Device Interface layer is shown in Figure B-11-9.