9 DIGITAL DISK DRIVES; DISKETTE DRIVES, DISC DRIVE CONTROLLERS AND POWER SUPPLIES FOR MEMORY SYSTEMS FEATURING A DISK DRIVE; CONTROLLER AND ONE OR MORE DISK DRIVES, CABINETS, CONNECTING CABLE, POWER CORDS, DISKETTES, PROTECTION DEVICES TO PREVENT UNWANTED RECORDING, SPARE PARTS AND DISKETTE EXERCISERS FOR SUCH DISK DRIVES AND MEMORY SYSTEMS