The present invention provides a cord controller to be mounted on a top rail of a window covering. A speech recognition unit converts to electronic speech data a voice command received through a microphone to select for viewing, for a selected dental patient, one of a plurality of dental images stored in a computer storage device. The invention also relates to a lamp device comprising such a light sensor device. The virtual memory management apparatus further includes a virtual swap device manager configured to allocate a virtual swap device to the virtual machine with reference to a virtual swap device map. The same method also enables audio information to be synchronized.