The following guidelines will help you keep your
disk pack in peak condition:
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Always keep the disk pack in its container when
it is not being used.
Reassemble the disk pack canister, even when it
is empty.
Never touch the disk pack’s recording surfaces.
Do not expose the disk pack to stray magnetic
fields.
Always store a disk pack flat. Never store a disk
pack on its edge.
Store the disk pack in the same environment in
which the disk memory set operates.
TOPIC 4—FIXED HARD DISK
SYSTEMS
Fixed hard disk systems are commonly found in
minicomputers and microcomputers. They are called
fixed disks because the disk is enclosed in a sealed case
and is inaccessible to the user.
The technology of these disk drives is one of the
fastest changing in the computer world. In the 14 years
that fixed disks drives have been in common use,
capacities have increased from 10 megabytes on a
5.25-inch full height drive, to over 10 gigabytes on a
3.5-inch half height drive. Additionally, data transfer
rates have increased ten-fold, while the average seek
times have decreased from more than 85 milliseconds
(ms) to less than 10 ms. The cost of these systems has
also decreased significantly. A 10 MB drive originally
cost about
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,500.00 or an average of 0.00 per
megabyte of disk space.
Today the cost is less than
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.25 per megabyte.
FIXED HARD DISK DRIVE
CONSTRUCTION
Most fixed disk systems have the same basic
components and similar operational characteristics. A
typical hard drive’s components include:
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Disk platters
Head actuator assembly
Read/write head assembly
Cables and connectors
The heads, head actuator, and platters are usually
contained in a sealed unit commonly referred to as a
head disk assembly (HDA). The HDA requires a dust
free environment when opened to avoid contaminating
the disk. Figure 10-18 illustrates atypical fixed disk.
Figure 10-18.—A typical fixed disk drive assembly.
10-23
