Herein described are at least a method and a system for prioritizing the transmission of one or more types of signals through a serial port. A coordinates correspondence part causes coordinates on a columnar space model arranged to surround a body to be operated to correspond to coordinates on input image planes on which the input images are positioned, respectively. The acoustic duct can be rigid while the driver sub-housing is flexible andor pliant to flex when the acoustic duct pivots relative to the driver sub-housing. Preferably, the system also includes the ability to view the progress of the milling operation and may include an imaging device such as a light microscope which permits monitoring of the area of interest on a specimen as the specimen is milled.