An automatic pullback catheter system includes a disposable catheter assembly mountable to a drive assembly. In an embodiment, the HEMT semiconductor device can include a GaN film and an AlGaN film. One embodiment of a method for operating a filter system comprises exposing a sensor to a pre-selected number of self-regeneration cycles, and increasing the temperature of the filter system. A plurality of inputoutput elements are preferably adapted to receive and read the media stored in the storage elements. If there is an instruction that branches control flow, a phantom entry is intentionally created and instruction pre-fetching is applied to the entry.