A novel method and apparatus is described for reducing the number of CDMA codes for a constellation of multiple trasponder platforms serving a number of subscribers in the same service area. The transistor switch comprises a graded channel region between a source region and a drain region, the graded channel region configured for providing a low resistance to mobile negative charge carriers moving from the source region to the drain region, wherein the graded channel comprises at least two doping levels. One set of shift registers are coupled to each cell array, and the nth set of shift registers successively activate word line selection signals according to a given control signal, so that the corresponding word lines of the nth cell array will be refreshed. These surface images may be used by the position module to determine subsequent positions of the device. The handling assembly moves through the rack interior to load media elements held by cells into a player.