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
drives 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
. 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 dont
have a spare controller, try reseating the chips on the
FIXED DISK CARE AND HANDLING
Fixed disks require very little care and handling
precautions. Since the head/drive assembly is a sealed
assembly, you cant 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
manufacturers 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.
Certain IDE drives may be damaged by
trying to park the heads. Refer to the
manufacturers instruction on head parking.
l Keep the area around a fixed disk system clean.
Avoid eating, drinking, and smoking around fixed
This chapter has introduced you to the major types
of magnetic disk storage devices. The following
information summarizes important points you should
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. In fixed 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.