Figure 10-9.—Floppy disk handling precautions.
telephone with a bell ringer uses an electromagnet to
ring the bell. If you keep a disk next to a phone, every
time the phone rings a 90-volt electromagnetic field is
generated around the phone. In time, the data on your
disk will start to mysteriously disappear. Another
hidden electromagnetic field is in the monitor
connected to your personal computer. Almost all
monitors manufactured today have an automatic
degaussing circuit. This circuit is design to demagnetize
the screen of the cathode-ray tube (CRT) by generating
a large electromagnetic field every time the monitor is
turned on. Again, your data starts disappearing.
Despite your best efforts to protect your disks,
disaster can strike. For example, a cup of sugar and
cream laden coffee spills on your 5.25-inch disk. You
have no back-up copy of this disk and to reconstruct the
data will take several weeks. What to do? The
following procedure is considered an emergency
recovery procedure and should be used only in
emergency situations.
First, take the damaged disk and very carefully cut
the top edge of the disk cover. Remove the disk and
wash it in a mild detergent with very light pressure to
avoid damaging the oxide coating. Rinse the disk
thoroughly. Dry the disk by laying it flat on a lint free
cloth and allow it to dry completely for at least 24 hours.
When the disk is dry, take a new disk and cut the
protective cover and remove the disk. Throw away the
new disk. We have to sacrifice the disk to get a clean
cover. Place the damaged disk in the new cover and
carefully tape the top closed. Insert the disk into the
drive and copy the information onto another disk.
Discard the damaged disk when you have finished
copying it.
TOPIC 3—DISK MEMORY SETS
Magnetic disk memory sets are mass storage
systems used to store large amounts of computer data
on interchangeable disk packs. A magnetic disk set can
be configured to operate with shipboard or shore-based
computers using parallel 16- or 32-bit CDS computer
channels and is found in a variety of mainframe
systems.
A magnetic disk memory set is composed of
variable configurations of magnetic disk recorder/
reproducers (disk unit controllers) and disk memory
units (memory units) housed in air-cooled or
water-cooled electronic equipment cabinets.
Our study of disk memory sets uses the AN/UYH-3
as the main example, but the functions described are
similar to other disk memory sets used in the Navy.
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