is turned off, the lubricant hardens as it cools causing the heads to stick to the disk. The heads will prevent the disk from spinning. To solve this problem, remove the drive and try to free the disk by manually turning the spindle motor shaft. You may have to remove the drive’s logic board to gain access to the spindle motor. Once free, the drive will probably operate normally. (3) If your drive has a stepper motor head actuator, check to see if it is operating properly. A stepper motor can develop dead spots or become stuck. Try to move the stepper motor manually if it is not operating properly. This will move it off the dead spot and the drive may operate long enough for you to recover the data you need. Finally, check the controller. If you have an identical  controller,  try  installing  it  in  the  computer  and see if this will solve your drive problems. If you don’t have a spare controller, try reseating the chips on the controller board. FIXED DISK CARE AND HANDLING Fixed disks require very little care and handling precautions. Since the head/drive assembly is a sealed assembly, you can’t very easily fix it, so you might as well take care of it. The following tips are designed to help you keep a fixed disk in good condition: Limit the number of times you turn the machine on and off. The power surge from turning on a disk drive can exceed 400 watts. If the heads were not parked,  this  start-up  power  surge  going  through  the heads could damage data on the disk. Protect your system from bad power. A good surge  protector,  power  conditioner,  or  uninterruptible power supply can protect your entire system from being destroyed by a power surge or blackout. If you are using a surge protector, be sure it is one that has been accepted by the Navy for use with personal computers. Mount   fixed   disk   drives   using   the manufacturer’s instructions and hardware. Low-level  format  a  fixed  disk  drive  in  the position and at the temperature that it will be used. Most fixed disk drives will work fine if the computer is stored on its side, but the fixed disk must be formatted in this position to avoid track alignment problems. Park the heads. This is extremely important to do every time you shut the power off if your disk has a stepper motor head actuator. Voice coil head actuators are self-parking when power is turned off. Parking the heads moves them to a safe landing zone so they do not damage the disk. CAUTION Certain  IDE  drives  may  be  damaged  by trying  to  park  the  heads.  Refer  to  the manufacturer’s instruction on head parking. Keep the area around a fixed disk system clean. Avoid eating, drinking, and smoking around fixed disks. SUMMARY—MAGNETIC  DISK STORAGE This chapter has introduced you to the major types of  magnetic  disk  storage  devices.  The  following information  summarizes  important  points  you  should have  learned: TYPES OF DISKS —Disks are classified as floppy disks or hard disks. Hard disks are furthered classified as disk memory sets that have removable disk packs or fixed disk systems. Infixed disk systems, the disk pack is in a sealed head/drive assembly and is not accessible  to  the  user. ORGANIZING DATA ON DISKS —Data is stored  on  disks  by  dividing  the  disk  into  tracks, cylinders, and sectors. A track is a concentric ring on the disk. A cylinder consists of all vertical tracks. A sector is apart of a track. Before a disk can be used, it must be formatted. Formatting is the process of writing the tracks and sectors on each recording surface of a disk or disk pack. On disk systems used in personal computers,  program  and  data  files  are  stored  in directories and subdirectories. FLOPPY DISKS AND DISK DRIVES —Floppy disk drives are the simplest of all magnetic disk storage devices. Two sizes are commonly used today: 5.25 inch and 3.5 inch. Floppy disks come indifferent densities. THE   5.25-INCH   FLOPPY   DISK   CON- STRUCTION —The 5.25-inch floppy disk consists of a flexible magnetic disk contained in a disk jacket. The jacket has several standardized cutouts. The media access hole provides for the heads to access the disk. The index hole indicates the start of the track. The write enable notch can prevent the disk from being written on if it is covered with a strip of tape. The stress relief notches help to properly position the disk in the drive and prevent the disk from warping while in the drive. 10-31