In a disk-based data storage system, a controller configured to control a reference count regeneration operation, the controller includes a control register, an address register, a status register, a boundary register, and an embedded memory. The bone screws provide a method to strengthen or repair damaged bones, or to promote bony fusion, and in conjunction with the inserts, provide a method of delivering a continuous or regulated amount of medicant to a desired location within the bone such as a fracture interface. A first downconverter receives the RF input signal and converts the frequency band of the signal into the IF band to output an IF input signal. At least the travel times of the rays and their dip angles at each subsurface point are stored in computer memory as they are computed.