Abstract: A mechanism is disclosed for receiving a disk cartridge and guiding the cartridge to an operating position within a disk drive, and for subsequently ejecting the cartridge when its use is complete, all responsive to the opening and closing of the disk drive door. The mechanism for ejecting the cartridge also automatically opens a transducer head access door when the cartridge is inserted into the receiver, and automatically closes the door upon cartridge ejection. Improvements are also disclosed in the manner of mounting a lift collar designed to support the disk and hub within a cartridge, and for an improved method of adjusting the cartridge to operate alternatively in write protect and write enable modes.