9 DIGITAL DISK AND DISKETTE DRIVES, DISK DRIVE CONTROLLERS AND POWER SUPPLIES FOR MEMORY SYSTEMS WHICH INCLUDE SUCH A 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