SEMICONDUCTOR WAFER STORAGE KIOSK
A semiconductor wafer cassette storage cabinet or stocker (10) having retrieval and transfer system constructed in the form of a kiosk encircling a pick-up and transfer apparatus. The structure is fo rmed of a plurality of identical sections (12) having walls and a roofjoined together to form a nearly semi-circular enclosure aroundt he pick-up and transfer apparatus. Each section has multiple level input/output ports adjacent to each other with a shelf (26,28) for supporting a semiconductor wafer cassette (16). Shelves (26,28) at the input/ouput ports are constructed of rails (30,32) supporting drive rollers (36) and a photo-detector (40) to activate the drive rollers to fill an output port whenever a casstte has been retrieved and transferred.