Discovering Computers 2016
Tools, Apps, Devices, and the Impact of Technology
Chapter 8
Digital Storage
Storage
• A storage medium, also called secondary storage, is the physical
material on which a computer keeps data, information, programs,
and applications.
• Examples of storage media include Hard Disks, Solid-state Drives
(Both Of Which Can Be Internal Or External), Memory Cards, USB
Flash Drives, Optical Discs, Network Attached Storage Devices,
Magnetic Stripe Cards, Smart Cards, RFID Tags, and NFC tags.
• Another storage option is cloud storage, which keeps information on
servers on the Internet.
• The user accesses files on cloud storage through a browser using an
app from the storage provider, the actual media on which the files
are stored are transparent to the user.
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Storage
• A storage device is the hardware that records
and/or retrieves items to and from storage media
Reading is the process
of transferring items
from a storage medium
into memory
Writing is the process of
transferring items from
memory to a storage
medium
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Storage
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Figure 8-1 in whole or in part.
Storage
• Capacity is the number of bytes a storage medium
can hold
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Table 8-1 in whole or in part.
Storage
• Items on a storage medium remain intact even
when you turn off a computer or mobile device
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Figure 8-2 in whole or in part.
Storage
• Access time measures:
– The amount of time it takes a storage device
to locate an item on a storage medium
– The time required to deliver an item from
memory to the processor
– Memory (chips) accesses items in billionths
of a second (nanoseconds). Storage devices,
by contrast, access items in thousandths of
a second (milliseconds) or millionths of a
second (microseconds).
– Transfer rates for storage are stated in KBps
(kilobytes per second), MBps (megabytes
per second), and GBps (gigabytes per
second).
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Figure 8-3 in whole or in part.
Hard Drives
• A hard disk, also called a hard disk
drive (HDD) contains one or more
inflexible, circular platters that use
magnetic particles to store data,
instructions, and information.
• Desktops and laptops often
contain at least one hard disk.
The entire hard disk is enclosed
in an airtight, sealed case to
protect it from contamination.
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Figure 8-4 in whole or in part.
Hard Drives
• The storage capacity of hard disks varies and is
determined by:
– The number of platters the hard disk contains
– Whether the disk uses longitudinal or perpendicular
recording
– Density
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Hard Drives
• Formatting is the process of dividing the disk into tracks
and sectors
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Figure 8-5 in whole or in part.
Hard Drives
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Figure 8-6 in whole or in part.
SSD (solid state drive)
• An SSD (solid state drive) is a flash memory storage
device that contains its own processor to manage its
storage
• An SSD (solid state drive) has several advantages over
traditional (magnetic) hard disks:
Faster access Faster transfer Quieter
More durable Lighter weight
times rates operation
Less power Less heat Defragmentatio
Longer life
consumption generation n not required
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in whole or in part.
SSD (solid state drive)
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in whole or in part.
Hard Drives
• An external hard disk is a separate freestanding
storage device that connects with a cable to a USB
port or other port on a computer or mobile device
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Figure 8-9 in whole or in part.
Portable Flash Memory Storage
• Sometimes called a thumb drive, USB flash drives
plug into a USB port on a computer or mobile
device. USB flash drives are convenient for mobile
users because they are small and lightweight
enough to be transported on a keychain or in a
pocket.
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Figure 8-13 in whole or in part.
Cloud Storage
• Cloud storage is an Internet service that provides storage
to computer or mobile device users. Cloud storage is
available for home and business users, with various levels
of storage services available. Cloud storage fee
arrangements vary, depending on the user’s storage
requirements.
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in whole or in part.
Optical Discs
• An optical disc consists of a flat, round, portable
disc made of metal, plastic, and lacquer that is
written and read by a laser. Optical discs used in
computers typically are 4.75 inches in diameter
and less than 1/20 of an inch thick.
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Figure 8-14 in whole or in part.
Characteristics of Optical Discs
A land causes light to reflect, which is read as binary digit 1. Pits absorb the light; this
absence of light is read as binary digit 0.
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Figure 8-15 in whole or in part.
Optical Discs
• Optical discs commonly
store items in a single
track that spirals from
the center of the disc to
the edge of the disc
• Track is divided into
evenly sized sectors
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Figure 8-16 in whole or in part.
Other Types of Storage
• A magnetic stripe card is a credit card, entertainment
card, bank card, or other similar card with a stripe that
contains information identifying you and the card
• A smart card, which is an alternative to a magnetic stripe
card, stores data on an integrated circuit embedded in
the card.
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Figures 8-22 – 8-23 in whole or in part.
