Chapter 2Hardware2.1 The System Unit2.2 Data and P

Chapter 2
Hardware
2.1 The System Unit
2.2 Data and Program Representa-
tion
2.2.1 Digital data and numerical data
Most computers are digital computers which use a spe-
cific language to communicate within itself in order to
process information. If there are programs running in
the background or a person is typing up a word docu-
ment for example, the computer needs to be able to in-
terpret the data that is being put into it by the human as
well as communicate to working components within it-
self. This language that digital computers use is called
binary code and is a very basic form of language com-
posed of only two figures; 1 and 0. Whereas the English
language is composed of 26 figures which we commonly
call the alphabet, computers use a language composed of
only two figures, hence its name Binary Code. Binary lit-
erally means two and refers to anything that consists of,
involves, or indicates two. The language known as Binary
Code operates on a system of 1’s and 0’s strung together.
Each 1 or 0 is referred to as a “bit.” “Bits” are the smallest
unit of data that a binary computer can recognize and ev-
ery action, memory, storage, or computation that is done
through a computer is composed of them. From playing
music through your speakers to cropping a photograph, to

typing up a document and preparing an important presen-
tation all the way down the line to browsing the internet
or picking up on a wifi signal in your area, everything
uses “bits” to complete the task needed. “Bits” string
into larger lines of information the way letters string into
words and then sentences. When eight “bits” are com-
pounded in this way they are then referred to as a “byte”.
“Bytes”, which are made up of “bits”, are commonly used
when referring to the size of the information being pro-
vided. For example, a song that is downloaded may con-
tain several kilobytes or perhaps even a few megabytes if
it is a whole c.d. and not just a single track. Likewise, pic-
tures and all other documents in general are stored on the
computer based on their size or amount of bytes they con-
tain. The amount of information that can be stored onto
a computer is also shown or displayed in bytes as is the
amount left on a computer after certain programs or doc-
uments have been stored. Since bytes can be extremely
long, we have come up with prefixes that signify how large
they are. These prefixes increase by three units of ten
so that a Kilobyte represents 1,000 bytes, a Megabyte
represents 1,000,000 bytes or one million bytes, a Giga-
byte represents 1,0000,000,000 or one billion bytes, etc.
Computers components have become so small that we can
now store larger and larger amounts of data bytes in the
same size computers resulting in the use of other larger
prefixes such as Tera, Peta, Exa, Zetta, and Yotta. Be-
low is a chart outlining the name of the prefix used and
powers of ten they symbolize.
0 1 1 0 1 0 0 0
1 1 0 1 0 0 0 0 0
1 0 0 1 1 1 0 1

0 1 0 0 1 1 1 00
1 0 0 1 1 1 0 0
1 1 0 0 1 1 1 0
b)
a)
c)
Bit shift
Digital Data Representation, otherwise known as how the
computer interprets data, is a key concept to understand-
ing computer data processing, as well as overall func-
tioning. Data is represented by particular coding sys-
tems. The computer recognizes coding systems- rather
than letters or phrases that the user of a computer views.
The actual process of the computer understanding cod-
ing systems is called digital data representation. A digital
23
24 CHAPTER 2. HARDWARE
computer operates by understanding two different states,
on or off. This means that the data is represented by
numbers- 0’s and 1’s, and is known as a binary computer.
The binary code is a very basic coding system for com-
puters to comprehend. An advantage to digital data com-
puting lies behind the binary coding systems. Although

the binary code has become decreasingly popular in the
professional, recreational fields due to an increase in tech-
nology, they still provide a use in programming. Digital
data creates a simple way to duplicate and transfer infor-
mation accurately from computer to computer, which is
why it is still used today.[1] The terminology for the small -
est unit of data is a bit, which consists of a single numeric
value,0 or 1. Bytes, on the other hand, consist of group-
ings of multiple groupings of bits. Bytes allow the com-
puter hardware to work more quickly and efficiently.[2]
(from the SI page on Wikipedia):
Representing data in a way that can be understood by a
digital computer is called Digital Representation and Bi -
nary Code is the most commonly used form of this. Bi-
nary Code is a Numerical Representation of data that uses
only 1 and 0 to represent every possible number. Mathe-
matics uses 10 symbols ranging from 1 TO 0 and include
2, 3, 4, 5, 6, 7, 8, and 9 as well. This Numerical Repre-
sentation of data is called the decimal numbering system
because it uses ten symbols. As shown on the chart, the
prefix deci symbolizes ten. In both systems, the position
of each digit determines to which power that number is
raised. In the deci-mal system each digit is raised by ten
so that the first column equals 1 (10^1) or ten raised to
the zero power, the second column equals 10 (10^2) or
ten raised to the first power, the third column equals 100
(10^3) or ten raised to the third power and so on. How-
ever, since Binary Code only operates with two symbols,
each digit is a power of two instead of ten. In binary
the first column equals 1 (2^0) or two raised to the zero
power, the second column equals 2 (2^1) or two raised
to the first power, the third column equals 4 (2^2) or two
raised to the second power, the fourth column equals 8
(2^3) or two raised to the third power, and so forth. Be-
cause the Binary system takes advantage of so few sym-

bols, the result is that more positions for digits are used to
express the same number than in decimal form, leaving
long lines of information for even the simplest expres-
sions.
2.2.2 Coding systems
There are a few different coding systems, EBCDIC,
ASCII and Unicode. EBCDIC (extended binary coded
decimal interchange code) was created for use in main-
frames, developed by IBM. The code uses a unique com-
bination of 0’s and 1’s, 8-bits in length, which allows for
256 different combinations. ASCII ( American standard
code for information interchange) was created for a more
personal use. ASCII uses a 7 bit code, though there is an
extended code which adds an extra bit, which nearly dou-
ASCII Code Chart-Quick ref card
A motherboard with an AMD chip.
bles the amount of unique characters the code can repre-
sent. however Unicode is a much longer string of code,
between 8 and 32 bits. With over one million different
possibilities, every language can be represented with this
code, every mathematical symbol can be represented, ev-
ery punctuation mark, and every symbol or sign from any
culture.
100 101 102 103 104 105 106 107 108 109 10A 10B 10C 10D
10E 10F
110 111 112 113 114 115 116 117 118 119 11A 11B 11C 11D
11E 11F
120 121 122 123 124 125 126 127 128 129 12A 12B 12C 12D

12E 12F
130 131 132 133 134 135 136 137 138 139 13A 13B 13C 13D
13E 13F
140 141 142 143 144 145 146 147 148 149 14A 14B 14C 14D
14E 14F
150 151 152 153 154 155 156 157 158 159 15A 15B 15C 15D
15E 15F
160 161 162 163 164 165 166 167 168 169 16A 16B 16C 16D
16E 16F
170 171 172 173 174 175 176 177 178 179 17A 17B 17C 17D
17E 17F
180 181 182 183 184 185 186 187 188 189 18A 18B 18C 18D
18E 18F
190 191 192 193 194 195 196 197 198 199 19A 19B 19C 19D
19E 19F
1A0 1A1 1A2 1A3 1A4 1A5 1A6 1A7 1A8 1A9 1AA 1AB 1AC
1AD 1AE 1AF
1B0 1B1 1B2 1B3 1B4 1B5 1B6 1B7 1B8 1B9 1BA 1BB 1BC
1BD 1BE 1BF
1C0 1C1 1C2 1C3 1C4 1C5 1C6 1C7 1C8 1C9 1CA 1CB 1CC
1CD 1CE 1CF
1D0 1D1 1D2 1D3 1D4 1D5 1D6 1D7 1D8 1D9 1DA 1DB 1DC
1DD 1DE 1DF
1E0 1E1 1E2 1E3 1E4 1E5 1E6 1E7 1E8 1E9 1EA 1EB 1EC

1ED 1EE 1EF
1F0 1F1 1F2 1F3 1F4 1F5 1F6 1F7 1F8 1F9 1FA 1FB 1FC 1FD
1FE 1FF
Non-Latin European scripts
African scripts
Middle Eastern and
Southwest Asian scripts
South and
Central Asian scripts
Southeast Asian scripts
East Asian scripts
American scripts
Cuneiform
Hieroglyphs
Notational systems
Symbols
Unallocated code points
As of Unicode 9.0
Roadmap to the Unicode SMP
Unicode is universal. With using 0’s and 1’s to represent

different data, it has become fit for any language used all
over the world. This code is replacing ASCII (American
https://en.wikipedia.org/wiki/SI
2.3. THE SYSTEM UNIT - THE MOTHERBOARD AND CPU
25
Standard Code for Information Interchange) because the
characters in this code can be transformed into Unicode,
a much more practical system for data. ASCII is known
as the alphabet code, and its numbering codes range from
0 all the way to 127 considered to be a 7 bit code. Alpha-
bets vary from language to langue, but 0’s and 1’s can
be understood worldwide. These codes apply to binary
coding systems, meaning the computer understands two
states of either On or Off. The problem with Unicode is
that it is not compatible with each computer system used
today. Windows 95/98 does not have the ability to run
Unicode while other Windows such as NT and 2000 are
closer to being able to. There is a program Sun Microsys-
tem’s Java Software Development Kit which allows you to
convert files in ASCII format into Unicode. While Uni-
code is a huge improvement for coding systems today, it
cannot process all symbols that are possible, leaving room
for new systems to one day take its place.[3]
2.2.3 Graphics Data
Image where individual pixels can be seen.
One type of multimedia data is graphics data. These data
are of still images, and can be stored in the form of a
bitmap image file. A bitmap image is a type of graphic
that contains pixels, or picture elements, that are arranged

in a grid-like pattern.[4] Each pixel is made up of a specific
group of numbers which corresponds to the color, and
the color’s intensity. Although there are a few other key
factors when determining the detail quality of an image,
pixels play an important role. An image with many pixels
allows there to be more potential of higher quality in that
image. However, this doesn’t mean that more pixels in
an image definitely results in a higher quality picture.[5]
When shopping for digital cameras consumers must be
aware of the amount of megapixels, or pixels by the mil -
lion, the cameras in front of them have. Today, an aver-
age person wishing to take decent and basic everyday pic-
tures will be satisfied with about an 8 megapixel camera.
In fact, many new smartphone cameras use 8 megapixels,
like the Apple iPhone 5C, a popular smartphone released
in September 2013. Someone with different intentions of
using images, perhaps for making high definition prints,
will require a camera with more megapixels. This would
allow for their prints to be large, but with appropriate and
exceptional quality.[6]
2.2.4 Audio Data
Audio Data is very similar to graphics data in that it is
understood in pieces. Instead of using pixels, however,
audio data uses samples. Audio data is usually recorded
with an input device such as a microphone or a MIDI con-
troller. Samples are then taken from the recording thou-
sands of times every second and when they are played
back in the same order, they create the original audio file.
Because there are so many samples within each sound file,
files are often compressed into formats such as MP3 or
MP4 so that they take up less storage space. This makes
them easier to download, send over the internet, or even
store on your MP3 player.

2.2.5 Video Data
Video data is also similar to graphic and audio data, but
instead of using pixels or samples, video data is recorded
with the use of frames. Frames are still images that are
taken numerous times per second and that when played
simultaneously, create a video (most films are recorded
using twenty-four frames per second).[7] Similar to audio
data, because video data contains so much information,
the files can be compressed, making it possible for full
length movies containing thousands of frames to be stored
on optical discs.
2.3 The System Unit - The Mother-
board and CPU
Motherboard
“The motherboard can be thought of as the “back
bone” of the computer.” This quote is from the article
Motherboard. Inside the system unit contains the moth-
erboard. The motherboard is the “glue” of the computer.
It connects the CPU, memory, hard drive, optical drives,
video card, and sound card together. The front of the
motherboard are peripheral card slots. The slots contain
different types of cards which are connected to the moth-
erboard. The left side of the motherboard contain ports.
The ports connect to the monitor, printer, keyboard,
mouse, speakers, phone line, and network cables.[8]
Like many of the components of computers, mother-
http://pcsupport.about.com/od/componentprofiles/p/p_mobo.htm

Realtimeclock Motherboard Baby AT crop
boards have not always been as advanced as they are to-
day. Motherboards on early PCs did not have many inte-
grated parts located directly on the board. Instead, most
of the devices, such as display adapters and hard disk
controllers, were connected through expansion slots. As
technology advanced, more and more devices were built
in directly to the board itself. At first, this began to cre-
ate problems as manufacturers began to find that if one of
the devices on the motherboard was faulty or in some way
damaged, that the entire motherboard must be replaced.
This led manufactures to change the design in a way that
allowed them to remove faulty parts easily and replace
them, especially parts that are growing and changing so
quickly, such as the RAM or CPU. Today, a motherboard
comes equipped with many parts working in conjunction
with each other. One can find anything, from back up bat-
teries, keyboard and mouse connectors, to cache memory
chips, in close proximity to the CPU. The computer is
able to do tasks faster as its components continue to be
closer to one another. The advancement of technology
has allowed for these parts to become smaller and more
powerful, allowing more surface area on the motherboard
to fit more devices. It is common today to find even audio
and video components built into it as well. With technol-
ogy moving as fast as it is, one may wonder what a moth-
erboard will be capable of containing in the near future.[9]
• Annotated Motherboard
• Motherboard Diagram
CPU

The CPU is the abbreviation for the central processing
unit. The computer needs the CPU in order to function
correctly. It is known as the brains of the computer where
the calculations occur. The microprocessor and the pro-
cessor are two other names for the central processing unit.
The Central processing unit attaches to a CPU socket on
the motherboard. A common CPU is called the multi-
core CPU. This specific type of CPU is efficient because
Motherboard
it allows computers to work on more than one task at a
time. Also, these multi core CPU’s experience less over
heating than the original CPU which causes much less
problems to the computer. A typical CPU is two by two
inches.
• Intel i7 940
• AMD Dual Core
History of the CPU
The Intel 4004
2.4. THE SYSTEM UNIT - MEMORY, BUSES, PORTS 27
The first CPU ever made was the Intel 4004, which was
designed by Federico Faggin. After ten months of Faggin
and his colleagues working on the chip, it was released
by Intel Corporation in January 1971. Even though this
first generation, 4-bit microprocessor could only add and
subtract, it was a major breakthrough in technology. The

amazing quality was that all of the processing was done
on one chip, as opposed to prior computers which had a
collection of chips wired together. This invention lead to
the first portable electronic calculator.[10]
While technology has advanced quite a bit since 1971, old
technology is not as “out-of-date” as one thinks. There
are still CPU chips made in the 1970’s and 1980’s that are
still being used today. Personal computers, such as PC’s
and Mac’s, use faster, more up-to-date CPU’s because the
users run many programs at the same time. However, the
more simple computers embedded in cars, printers, and
microwaves can still use the older forms of microproces-
sors. For example, one famous CPU was the MOS 6502,
made in 1975, and it was still being used in many ap-
pliances up until 2009. Control processing units are the
key component in any computer, and thus sometimes the
simpler styles work best.[11]
2.4 The System Unit - Memory,
Buses, Ports
2.4.1 Memory
The Template:Gaps byte (512×220) capacity of these RAM
mod-
ules is stated as “512 MB” on the label.
Memory identifies data storage that comes in the form of
chips and is used to store data and programs on a tem-
porary or permanent basis. There are two main types
of memory storage which are random- access memory
(RAM) and read-only memory (ROM). Inside the sys-
tem unit, ROM is attached to the motherboard. Random-
access memory can read data from RAM and write data
into RAM in the same amount of time. RAM is measured

in bytes and includes the cache memory and registers. It
is volatile which means that it loses the information/data
stored on it when the power is turned off. In order to re-
trieve an important file at a later date, one needs to store
it on a separate, non-volatile, storage medium (such as a
flash drive or hard-drive) so that, even though the infor-
mation is erased from RAM, it is stored elsewhere. RAM
has different slots where it stores data and keeps track of
addresses. Read-only memory cannot be written to and is
non-volatile which means it keeps its contents regardless
of whether the power is turned off or not. Flash memory
(solid-state) is starting to replace ROM. It is also a non-
volatile memory chip that is used for storage on devices,
like mobile phones, tablets, digital cameras, etc. This
type of memory can often be found in the form of flash
drives, SD cards, and Solid-State hard drives. The reason
for this is so that the data can be quickly updated over
time while taking up a smaller amount of physical space
in comparison to its precursors. Flash memory is also
more resistant to outside forces, such as electro-magnetic
fields or shock, than other memory alternatives such as
traditional hard-drives.
A microprocessor, which may use cache memory.
Cache memory is a specific kind of memory that al-
lows a computer to perform certain tasks much more
quickly. A good analogy from HowStuffWorks compares
the computer to a librarian, data to books, and cache to a
backpack.[12] Suppose somebody walks into a library and
asks the librarian for a copy of the book Moby Dick. The
librarian goes back into the room full of books, grabs that
book, and gives it to the reader. Later that day, the reader
returns, having finished the book, and gives it back to the
librarian, who returns it to the same storage room. Then,

a second reader walks in asking for the same book, Moby
Dick. The librarian has to get up and go all the way back
to the room in order to get the book he was just handling,
which is a waste of time. Instead, suppose the librarian
had a backpack that could store up to 10 books. When
the first person returns Moby Dick, the librarian puts it
into his backpack instead (after making sure the back-
https://en.wikibooks.org/wiki/Template:Gaps
pack doesn't have 10 books in it already.) Then, when
the second person comes in requesting that same book,
the librarian can just check his bag, get the book out, and
hand it to the second person without having to walk all
the way back into the other room.
Cache memory functions like that backpack. It stores
previously accessed data in a specific area with a limited
amount of memory so that the processor can get this data
much more quickly.
2.4.2 Ports
Parallel Printer Port
Ports are on the outside of the system unit and they are
used to connect hardware devices. There are physical
ports and virtual ports. A physical port is a physical con-
nection to a computer where data is transferred. It is
when something is physically plugged into the computer
or some other device. Virtual ports allow software ap-
plications to share hardware resources without having to
physical connect to each other or to interfere with one
another.[13] Parallel ports are most often used with a key-

board, printer or mouse, but these are more commonly
known as legacy ports instead. Each port has a certain
connector to plug it into the computer. Different type
of ports would be power connectors, VGA monitor port,
USB ports, Firewire port, HDMI port, Network port, au-
dio ports, and empty slots. The connectors would be
Monitor (VGA, HDMI), USB, Firewire, network, and au-
dio connector. Each port has also a different purpose and
connector. Almost all PCs come with a serial RS-232C
port or a RS-4222 port and they are used for connect-
ing a modem, mouse, or keyboard. They also have par-
allel ports that are used to connect printers. These are
also considered USB ports because they are physical ports
and which standardize communications between comput-
ers and peripheral. USB ports were created in the mid
1990’s; USB stands for Universal Serial Bus. There are
also network ports used to connect a computer to a net-
work. Ethernet was developed in the 1980s and it is a
system for connecting a number of computer systems to
form a local area network.
A serial port is used to connect modems to personal com-
puters. The term “serial” signifies that data sent in one
direction always travels over a single wire within the ca-
ble. The last main kind of port is the FireWire, which are
used to connect FireWire devices to the computer via a
FireWire connector. These are used with mostly digital
video cameras and other multimedia devices.
2.4.3 Thunderbolt port
Thunderbolt-Connector
A Thunderbolt port connect peripheral devices through
that cable. These ports allow for you to connect more de-
vices to your computer and is very fast. Thunderbolt ports

use hardware controllers I/0 protocols onto one efficient
protocol with the use of just one cable. I/O technology
is input and output is a device that that transfers the data
to the computer peripherally (a CD-ROM would be an
example of an I/O technology).This port lets there to be
full bandwidth for both directions of the port, thus allow -
ing the user to faster and more efficient with the ports it
has to connect. This type of technology allows for people
to plug in as many devices they could use on their com-
puter and not slowing any of those devices down. The
thunderbolt port is also small so it is easy to travel with as
well.[14]
2.4.4 Power supply unit
Computers need power. There are two main functions
the PCUs are responsible of. The first is to convert the
type of electrical power available at the wall outlet such
as110V 60Hz AC (alternating current) or 230v 50Hz AC
to the type the computer circuits can use. The other cru-
cial task is to deliver low voltages to each device due
their requirements. The converting currents could be
represented either by built in PSU (desktops, servers,
mainframes) or by the separate power supply adapters
for computers with rechargeable batteries inside (laptops,
tablets). Three main voltages are used to power com-
puter : +3.3v, +5v, and +12v DC, Usually, the +3.3 or
2.5. HOW THE CPU WORKS 29
PSU-gold-rear
+5 voltages are being used by logic circuits and some dig-
ital electronic components (motherboard, adapter cards,

and disk drive logic boards) while the motors (disk drive
motors and any fans) use the +12v power. The power sup-
ply must provide a good, steady supply of DC power for
the proper system operation. Devices that run on voltages
other than these must be powered by onboard voltage reg-
ulators. For example the CPUs operate 1.5V and 2V and
require very stable power with high power consumption.
[15]
2.4.5 Ethernet Cable in Theatre
A commonly used cable today is Ethernet cable. You a
probably most familiar with its use involving the internet
in your home, mostly going from your modem, to another
computer of to a Wi-Fi router. However, the use of Eth-
ernet cable has been instrumental in the changing would
of technical theatre. Before its introduction, the most
common computer cables used in theatre were DMX and
XLR, for lighting and sound respectively. This issue with
this is that each cable can only carry the information for
one device, be that a microphone or light. In addition, if
these cables are stored improperly, they can corrupt the
information being transmitted. Ethernet is much smaller,
and can transmit far more data. Also, there is less of a
danger regarding storing cable. Ethernet, combined with
new operating system and equipment, has made thing far
more efficient. For example, an analog board must have
one XLR cable go to each microphone, so if you wanted
to run 40 microphones, you must have 40 channels avail-
able on your soundboard. Also, the size of a cable with
40 smaller lines inside it can reach a one-inch diameter,
and can weigh several hundred pounds. Now, a digital
soundboard can control up to 100 microphones on a sin-
gle Ethernet cable.
An Ethernet cable

This is a Yamaha digital soundboard capable of running
ethernet
2.5 How the CPU Works
CPU Architecture and Components
As previously discussed on this page, the CPU is a com-
plex piece of the computer made up of many parts. The
way these parts all fit together inside the CPU is differ-
ent in each processor but they mainly contain the same
parts from device to device. The most abundant part in
the CPU would be the transistor. Modern CPU’s typi-
cally hold several hundred million transistors with some
of the more high-end computers holding over a billion,
and for good reason. Calculations in a computer can be
performed thanks to the combination of transistors turn-
ing off or on. Besides these transistors, there are sev-
A CPU core
eral parts that make up the CPU. Some of these include
the arithmetic/logic unit (ALU) and floating point unit
(FPU), the control unit, and the prefetch unit. The ALU
is the part of the CPU that deals with the mathematics in-
volving whole numbers and any functions done with those
numbers. The FPU takes care of the mathematics with
other numbers like fractions, or numbers with decimal
places.[16] These two parts work hand in hand, using arith-
metic and logical processes, to allow you to perform ba-
sically any function you perform on your computer. The

control unit takes charge in controlling where and when
information is transferred to and from the CPU. When in-
formation leaves the control unit, it is usually sent to the
ALU/FPU where it can be converted into a process. The
prefetch unit, as its name implies, fetches data before it
is needed. It uses a sequence of processes to guess what
information will be needed next, and have it readily avail -
able before the time it needed. Other components of the
CPU include the cache, the decode unit, and the bus in-
terface unit. The cache serves as high-speed memory for
instructions that the CPU would like to access faster, in
other words instructions that the CPU would rather avoid
retrieving from RAM or the hard drive. The decode unit,
just as it sounds, decodes instructions. Once the prefetch
unit fetches data, the data goes through the decode unit
so the instructions can be understood by the control unit.
The bus interface unit allows communication between the
the core and other CPU components. Think of it as liter-
ally a bus, taking information from one place and trans-
porting it somewhere else. [17]
2.6 How the CPU Works
The Internal Clock
Every computer actually has two different clocks. One
is the virtual or system clock that runs and is displayed
whenever the computer is on and running.[18] The other
is a real-time clock or hardware clock that runs continu-
ously, and is responsible for tracking the correct time and
day. This device does not count time in days and hours
for example. Instead it just runs a counter at times per
second. As far as the century goes, it is the job of the
BIOS, the Basic Input-Output System, to track this and
save it in the non-volatile memory of the hardware clock.

These two clocks run independently on each other. The
system clock is physically a small quartz crystal that can
be found on the motherboard. It also helps synchronize
all computer functions by sending out signals- or cycles-
on a regular basis to all parts, much like a person’s heart-
beat. Hertz is the unit of measure used to count the num-
ber of cycles per second. For example, one megahertz is
one million ticks of the system clock. This clock is very
important to the CPU because the higher the CPU clock
speed, the more instructions per second it could process.
Since the entire system is tied to the speed of the system
clock, increasing the system clock speed is usually more
important than increasing the processor speed.
PCs in the past only had one unified system clock with
a single clock, which drove the processor, memory, and
input/output bus. However, as technology advanced, the
need for a higher speed, and thus multiple clocks, arose.
Therefore, a typical modern PC now has multiple clocks,
all running at different speeds to enable any data to
“travel” around the PC. Furthermore, two CPUs with the
same clock speed will not necessarily perform equally.
For instance, if an old microprocessor required 20 cycles
to perform a simple arithmetic equation, a newer micro-
processor can perform the same calculation in a single
clock tick. Therefore, even if both processors had the
same clock speed, the newer processor would be a lot
faster than the old.
As mentioned previously, a CPU serves as a great ex-
ample for the synchronization that the system clock per-
forms. To synchronize, most CPUs start an operation on
either the falling edge, when the clock goes from one to
zero, or the rising edge, when the clock goes from zero
to one. All devices, such as a CPU, synchronized with

2.6. HOW THE CPU WORKS 31
The system clock alternates between zero and one at a periodic
rate.
the system clocks run at either the system clock speed
or at a fraction of the system clock speed; therefore, the
CPU is unable to perform tasks any faster than the clock.
For example, during each system clock tick, a CPU clock
speed of 2 GHz allows the CPU clock to “tick” 10 times,
executing one or more pieces of microcode. This abil -
ity to process multiple pieces of microcode at one time is
known as superscalar. [19]
The Machine Cycle
Instr. No.
1
2
3
4
5
IF ID MEM WB
Pipeline Stage
Clock
Cycle
1 2 3 4 5 6 7

EX
IF ID MEM WBEX
IF ID MEM WBEX
IF ID MEMEX
IF ID EX
5 Stage Pipeline
A machine cycle is a term often used when discussing
the clock. It has four main parts- fetch, decode, execute,
and store. The machine cycle occurs whenever a CPU
processes a single piece of microcode. The fetch opera-
tion requires the program instruction to be fetched from
either the cache or RAM, respectively. Next, the instruc-
tions are decoded so that the ALU or FPU can understand
it, known as the decode operation. Then, the execute op-
eration occurs when the instructions are carried out. Fi -
nally, the data or result from the ALU or FPU operations
is stored in the CPU’s registers for later retrieval, known
as the store operation. A fifth possible step in the cycle
is the register write back operation, which occurs in cer-
tain CPUs. The RISC CPU, which stands for reduced
instruction set computer processing unit, is an example
that uses the fifth step of the machine cycle. Machine cy-
cles can only process a single piece of microcode, which
forces simple instructions, like addition or multiplication,
to require more than one machine cycle. In order to make
computers faster, a system known as pipelining has been
created. Originally, one machine cycle would have to fin-
ish processing a single instruction before another instruc-
tion could be carried out through a second machine cycle.

With pipelining, as soon as an instruction passes through
one operation of the machine cycle, a second instruction
can start that operation. For example, after one instruc-
tion is fetched and moves on to decoding, the CPU can
fetch a second instruction. This invention allows for mul-
tiple machine cycles to be carried out at the same time,
which boosts the performance of the computer. Also, be-
cause of how fast the CPU can work with pipelining, it
can be measured in millions of instructions per second.[20]
Typical CPU Components (continued)
Just like a real life bus transports people, the bus interface unit
carries information from one destination to another
ANS700-CPU-board
To round up the simplified inventory of a CPU’s guts,
we have the decode unit, the registers and internal cache
memory, and the bus interface unit. Of the remaining
three sections of a CPU, the decode unit is easiest to
understand because its job immediately follows the job
of the prefetch unit. After the prefetch unit collects the
data, the decode unit decodes the data into a language
that is easier for the ALU/FPU to understand. It does
that by consulting a ROM memory that exists inside the
CPU, called microcode.[21] The registers are used during
processing; they're groups of high-speed memory located
within the CPU that can be accessed by the ALU and
FPU, or for other assorted optimization purposes. While
the registers provide the fastest speed of memory, their
space is extremely limited. In the cases where the small
register space isn't good enough, there are the caches to
save the day. The cache is used by the CPU for mem-
ory which is being accessed repeatedly, speeding up the

access time and having a slightly larger storage than the
register.[22] The bus interface unit does exactly what it
sounds like; it buses the data back and forth, connecting
the core of the CPU to interact with other components.[23]
Another aspect of the CPU is improving processing per-
formance. In the past most CPUs designed for desktop
computers had only one single core, so the only way to
improve performance was to increase the speed of the
CPU; however, increasing the speed also caused the CPU
to heat up. So now a days CPU have multiple cores in or-
der to increase the performance. In an article by Sebas-
tian Anthony on Extreme Tech on September 10, 2014 he
explains how the new Apple iPhone 6 CPU will be able to
perform faster. The new Apple iPhone is going to have a
new A8 SoC. It is going to have more transistors, which if
you recall, are small devices made of semiconductor ma-
terial that acts like a switch to open and close electrical
circuits. This new A8 chip will have about 2 million tran-
sistors according to the article Mr. Anthony wrote. Mr.
Anthony states, “The A8 SoC will, according to Apple,
be about 25% faster than its predecessor in CPU tasks.”
As of now, this information is coming from graphs and
information that Apple has shared. The thing to know
and realize is that companies are constantly striving to
improve performance and reworking the architecture of
the CPU can improve the performance.[24]
2.7 Improving the Performance of
Your Computer

Spindle Head
Actuator Arm
Actuator Axis
Actuator
IDE Connector
Jumper Block
Power Connector
Platter
Computer Hard Drive
2.7.1 Add More Memory and Buy a Larger
or Second Hard Drive
When it comes to technology, there is no question that
newer is better. New systems are able to process faster,
store more, and run more applications at once. However,
it is obviously not within everybody’s means to just run
out and purchase the newest and greatest technology the
minute it hits the market. Technology is expensive, and
therefore it is important to know your options. For exam-
ple, if you have a computer that is a couple of years old,
it is not unreasonable to assume that the hard drive and
memory on the system are starting to slow down. How-
ever, what many people may not know is that buying a
new computer is not the only solution to the problem. You
can add memory to your old system simply by purchas-
ing a new memory card and installing it into the computer

hardware. By doing this, you are saving money and buy-
ing yourself a little bit more time with the computer.[25]
Another way to speed up your computer with out having
to invest in a whole new one is by buying a second hard
drive. When the original hard drive starts to fill up, one
can simply purchase either an internal or external hard
drive for the computer and drastically increase the oper -
ating speed.[26]
2.7.2 Upgrade To A Solid-State Drive
An Intel X25-M Solid-State Drive
Since solid-state drives (SSDs) are hard drives that use
flash memory technology instead of hard disk platters
they have no moving parts. They also no longer make
noise, consume less power thus generating less heat, and
are much faster than hard drives. Since they are much
faster than hard drives, the performance of the computer
would also be improved. Running programs, opening
files, saving things to the disk, even browsing the web will
be much faster. Also with a mechanical hard drive, phys-
ical heads have to move around to read data from the disk
while in a solid-state drive data can be read and written
on any location thus there is no penalty in performance.
Not only are solid-state drives faster but they have also be-
come less expensive that upgrading to them is much more
affordable and reasonable. Even further, installing solid-
state drives is not too difficult or complex. It is basically
the same as installing regular hard drives. Also if the de-
cision of upgrading to solid-state drives seems a little too
final, it is possible to just add a solid-state drive alongside
the hard drive. Thus not only having more space, but also
having the ability to keep the old mechanical drive.[27]

2.7. IMPROVING THE PERFORMANCE OF YOUR
COMPUTER 33
Internet Connection
2.7.3 Upgrade Your Internet Connection
If your system seems to be running poorly while using the
internet, you may have to upgrade your internet connec-
tion. Upgrading your internet connection may become
more costly but there is a significant change in the pro-
cessor. Your first step would be to discuss any upgrades
or check if the provider needs to be enhanced in any way.
Then find a browser that is suitable for your connection
type. With that being stated, you can change the settings
on the router in order to speed up the internet connec-
tion. In order to prevent your internet connection becom-
ing slower, it’s highly suggested to have a password in or-
der to access the internet. In addition, every computer
owner should provide maintenance to their computer in
order to prevent viruses or any bugs the computer may
receive but it also prevents an internet connection from
being slow. In order to do so, keep up with upgrading and
cleaning the computer because the more the computer is
trying to maintain, the slower the internet connection may
become.[28]
2.7.4 System Maintenance
In order for computers to operate at their maximum effi -
ciency, users must be aware of the importance of system
maintenance because, over a period of time, one may no-
tice a reduction in system performance. This can be at-
tributed to a number of common factors that lead to the
degradation in performance. One major reason is hard

drive fragmentation. As more programs are installed
onto the hard drive, the pieces of the files that are on those
programs take longer to be located. The longer pieces
of the program become shorter and fragmented, leading
to a longer waiting period for the user as the computer
searches for these scattered pieces. Related to this, al-
though not nearly as detrimental to system performance
as fragmentation, is the cluttering of pieces and refer-
Video Graphics Card
ences to uninstalled programs in the operating system.
For Windows users, this occurs in the Registry. After
the user uninstalls a program, there are references to that
program left behind in the Registry that can possibly im-
pact performance. However, performance is not neces-
sarily the issue here. For example if the user is going
to update the system by switching from an Nvidia graph-
ics card to an AMD one, it might be a good idea to not
only uninstall all drivers and related programs but also to
clean the Registry of any references to the Nvidia drivers
and software (in order to avoid possible conflicts when the
AMD card is installed). This will ensure a “clean” install
of both the hardware and software components. A free
registry cleaner utility one can use is CCleaner.[29]
Temporary files (e.g. from web browsers and installation
programs) can take up valuable storage space if they are
not removed after extended periods of times. Also, users
should be aware of the programs they are installing and
decide which specific programs are to run at startup. Too
many programs can slow down the initial startup time of
the computer because it must launch program after pro-
gram. Only those programs that are necessary should be
included, and to check for this, click Start (in the lower-
left Windows icon) and enter the command msconfig in

the search tab. This will open the System Configuration
window. Programs that run at startup are listed under the
Startup tab. Here the user can enable or disable programs,
which can affect startup time.
Another important factor in determining system perfor-
mance is the corruption of system files by malware.
Viruses, worms, trojans, spyware, and other forms of
malware can infect a system by various means, so it is im-
portant for the user to be aware and defensive. Anti -virus
programs and other security software provide protection
from malware, so it is recommended that a user has some
sort of program installed and regularly scans the system
for any traces.
Lastly, dust can accumulate in and on heatsink fans (e.g.
processor and graphics card), case fans, ports, power sup-
plies, and motherboards. Every internal component can
accumulate dust, and this can be a major issue for sys-
tem integrity because dust acts as an insulator by trapping
heat. Fans with too much dust do not operate efficiently
because the fins do not spin quickly, which further exac-
erbates the heating problem. Not only that, but dust can
also cause electrical shorting of the circuits, which can
irreversibly damage components.[30] To clean the com-
puter, power off the system, which includes turning off
the power supply. It should not be connected to any
source. Then open the case and use a can of compressed
air to blow out the dust wherever it may be. The goal is
to rid the case of any remnants of dust. Following this
and the other tips listed above will help ensure reliable
performance and a longer lifespan for the computer.

2.7.5 Future Trends
The supremacy of supercomputers may not be as evident in the
future.
The challenge of making computers faster and more ef-
ficient has brought new ideas to the table of technol -
ogy. One such idea is nanotechnology, which uses mi-
croscopic components only nanometers in length. Car-
bon nanotubes are already being used in technology to-
day in products such as lithium ion batteries because of
their great performance conducting electricity. Other
nanotechnology includes nanoparticles and nanosensors.
Another idea that has received increased recent attention
is quantum computing. These computer’s go beyond reg-
ular computers’ binary system using qubits, which can
be either a 1, a 0, or both simultaneously.[31] Although
these computers are only able to perform seemingly sim-
ple tasks like sudoku puzzles as of recently, their potential
is outrageous for tasks such as encryption. Optical com-
puting is another form of future technology which uses
light waves to transfer data. Since the in fared beams do
not interfere with each other, optical computers can be
much smaller and more efficient that electronic comput-
ers. In fact, once optical computers have been mastered
the computers will be able to process information at the
speed of light using very little power at all.[32] In years to
come, the extraordinary power of supercomputers is pre-
dicted to be available in more common computers using
technology like terascale computing to process at incred-
ible speeds.
2.7.6 Review Definitions
Application Software: Programs that enable users to

perform specific tasks on a computer, such as writing let-
ters or playing games.
Computer: A programmable, electronic device that ac-
cepts data input, performs processing operations on that
data, and outputs and stores the results.
Data: Raw, unorganized facts.
Information: Data that has been processed into a mean-
ingful form.
Computer Network: A collection of computers and
other hardware devices that are connected together to
share hardware, software, and data, as well as to com-
municate electronically with one another.
Hardware: The physical parts of a computer system,
such as the keyboard, monitor, printer, and so forth.
Internet Appliance: A specialized network computer
designed primarily for Internet access and/or e-mail ex-
change.
Operating System: The main component of system
software that enables a computer to operate, manage its
activities and the resources under its control, run applica-
tion programs, and interface with the user.
Output: The process of presenting the results of pro-
cessing; can also refer to the results themselves.
Software: The instructions, also called computer pro-
grams, that are used to tell a computer what it should do.
Storage: The operation of saving data, programs, or out-
put for future use.
URL: An Internet address (usually beginning with
http://) that uniquely identifies a Web page.
Web browser: A program used to view Web pages.
World Wide Web (WWW): The collection of Web
pages available through the Internet.
Web server: A computer that is continually connected
to the Internet and hosts Web pages that are accessible
through the Internet.[33]

2.7.7 Review Questions
1) What is the key element of the CPU?
2) What are the connectors located on the exterior of the
2.8. REFERENCES 35
system unit that are used to connect external hardware
devices?
3) What is an electronic path over which data travels?
4) _________ are locations on the motherboard into
which _________ can be inserted to connect those cards
to the motherboard.
5) What is used to store the essential parts of the operating
system while the computer is running?
6) The ______________________ consists of a variety
of circuitry and components that are packaged together
and connected directly to the motherboard
7) A _________ is a thin board containing computer
chips and other electronic components.
8) The main circuit board inside the system unit is called
the ___________ .
9) Before a computer can execute any program instruc-
tion, such as requesting input from the user, moving a file
from one storage device to another, or opening a new win-
dow on the screen, it must convert the instruction into a
binary code known as ____________.
10) In order to synchronize all of a computer’s operations,
a __________ is used.[34]
2.7.8 Review Answers
1) Transistor 2) Ports 3) Bus 4) Expansion slots, Expan-
sion cards 5) RAM 6) Central Processing Unit 7) Circuit

Board 8) Motherboard 9) Machine Language 10) System
Clock
2.8 References
[1] http://courses.cs.washington.edu/courses/cse100/99au/
FIT100-99.L5.pdf
[2] http://compnetworking.about.com/cs/basicnetworking/
f/bitsandbytes.htm
[3] http://www.peachpit.com/articles/article.aspx?p=
31286&seqNum=16
[4] http://desktoppub.about.com/od/glossary/g/bitmap.htm
[5] http://www.cambridgeincolour.com/tutorials/
digital-camera-pixel.htm
[6] http://www.cambridgeincolour.com/tutorials/
digital-camera-pixel.htm
[7] https://en.wikipedia.org/wiki/Frame_rate
[8] http://pcsupport.about.com/od/componentprofiles/p/p_
mobo.htm
[9] http://www.pctechguide.com/motherboards/
evolution-of-the-motherboard
[10] http://www.howstuffworks.com/microprocessor.htm
[11] http://www.cpushack.com/life-cycle-of-cpu.html
[12] http://computer.howstuffworks.com/cache2.htm

[13] http://www.computerports.net/
[14] http://www.tomshardware.com/reviews/
thunderbolt-performance-z77a-gd80,3205.html
[15] http://www.instructables.com/id/
Power-Supply-For-Arduino-power-and-breadboard
[16] http://www.techterms.com/definition/alu
[17] http://education-portal.com/academy/lesson/
central-processing-unit-cpu-parts-definition-function.
html#lesson
[18] http://scholar.lib.vt.edu/vtpubs/spectrum/sp970911/3b.
html
[19] https://courses.engr.illinois.edu/ece390/books/artofasm/
CH03/CH03-2.html
[20] http://www.jegsworks.com/lessons/lesson4/lesson4-4.
htm
[21] http://www.hardwaresecrets.com/printpage/
How-a-CPU-Works/209
[22] http://www.moreprocess.com/devices/
computer-memory-hierarchy-internal-register-cache-ram-hard-
disk-magnetic-tape
[23] http://www.electronics.dit.ie/staff/tscarff/BIU/bus_
interface_unit.htm
[24] http://www.extremetech.com/computing/
189787-apples-a8-soc-analyzed-the-iphone-6-chip-is-a-2-
billion-transistor-20nm-monster

[25] http://www.pcworld.com/article/129177/article.html
[26] http://windows.microsoft.com/en-us/windows7/
install-or-remove-a-hard-disk-drive
[27] http://www.howtogeek.com/194750/
its-time-why-you-need-to-upgrade-to-an-ssd-right-now/
[28] http://www.auslogics.com/en/articles/speed-up-internet/
[29] http://www.piriform.com/ccleaner
[30] http://www.computerdust.com/downloads/special_
report_on_the_effect_of_dust_on_electronics.pdf
[31] http://www.dwavesys.com/quantum-computing
[32] http://www.extremetech.com/extreme/
187746-by-2020-you-could-have-an-exascale-speed-of-light-
optical-computer-on-your-desk
[33] http://coursemate.cengage.com/CPReader/View/
9781133114598/default.aspx?eISBN=9781133114598#
70a7d313-0a5d-4ddc-ba5c-766e5fb0dc77
[34] http://ng.cengage.com/static/nb/ui/index.html?nbId=
7345&nbNodeId=1013914#!&parentId=1013922
http://courses.cs.washington.edu/courses/cse100/99au/FIT100-
99.L5.pdf
http://courses.cs.washington.edu/courses/cse100/99au/FIT100-
99.L5.pdf
http://compnetworking.about.com/cs/basicnetworking/f/bitsandb
ytes.htm
http://compnetworking.about.com/cs/basicnetworking/f/bitsandb

ytes.htm
http://www.peachpit.com/articles/article.aspx?p=31286&seqNu
m=16
http://www.peachpit.com/articles/article.aspx?p=31286&seqNu
m=16
http://desktoppub.about.com/od/glossary/g/bitmap.htm
http://www.cambridgeincolour.com/tutorials/digital-camera-
pixel.htm
pixel.htm
pixel.htm
pixel.htm
https://en.wikipedia.org/wiki/Frame_rate
http://www.pctechguide.com/motherboards/evolution-of-the-
motherboard
http://www.pctechguide.com/motherboards/evolution-of-the-
motherboard
http://www.howstuffworks.com/microprocessor.htm
http://www.cpushack.com/life-cycle-of-cpu.html
http://computer.howstuffworks.com/cac he2.htm
http://www.computerports.net/
http://www.tomshardware.com/reviews/thunderbolt-
performance-z77a-gd80,3205.html
http://www.tomshardware.com/reviews/thunderbolt-
performance-z77a-gd80,3205.html
http://www.instructables.com/id/Power-Supply-For-Arduino-
power-and-breadboard
http://www.instructables.com/id/Power-Supply-For-Arduino-
power-and-breadboard
http://www.techterms.com/definition/alu
http://education-portal.com/academy/lesson/central-processing-
unit-cpu-parts-definition-function.html#lesson

http://scholar.lib.vt.edu/vtpubs/spectrum/sp970911/3b.html
http://scholar.lib.vt.edu/vtpubs/spectrum/sp970911/3b.html
https://courses.engr.illinois.edu/ece390/books/artofasm/CH03/C
H03-2.html
https://courses.engr.illinois.edu/ece390/books/artofasm/CH03/C
H03-2.html
http://www.jegsworks.com/lessons/lesson4/lesson4-4.htm
http://www.jegsworks.com/lessons/lesson4/lesson4-4.htm
http://www.hardwaresecrets.com/printpage/How-a-CPU-
Works/209
http://www.hardwaresecrets.com/printpage/How-a-CPU-
Works/209
http://www.moreprocess.com/devices/computer-memory-
hierarchy-internal-register-cache-ram-hard-disk-magnetic-tape
http://www.moreprocess.com/devices/computer-memory-
hierarchy-internal-register-cache-ram-hard-disk-magnetic-tape
http://www.electronics.dit.ie/staff/tscarff/BIU/bus_interface_uni
t.htm
http://www.electronics.dit.ie/staff/tscarff/BIU/bus_interface_uni
t.htm
http://www.extremetech.com/computing/189787-apples-a8-soc-
analyzed-the-iphone-6-chip-is-a-2-billion-transistor-20nm-
monster
http://www.extremetech.com/computing/189787-apples-a8-soc-
analyzed-the-iphone-6-chip-is-a-2-billion-transistor-20nm-
monster
http://www.pcworld.com/article/129177/article.html
http://windows.microsoft.com/en-us/windows7/install-or-
remove-a-hard-disk-drive
http://windows.microsoft.com/en-us/windows7/install-or-
remove-a-hard-disk-drive
http://www.howtogeek.com/194750/its-time-why-you-need-to-

upgrade-to-an-ssd-right-now/
http://www.howtogeek.com/194750/its-time-why-you-need-to-
upgrade-to-an-ssd-right-now/
http://www.auslogics.com/en/articles/speed-up-internet/
http://www.piriform.com/ccleaner
http://www.computerdust.com/downloads/special_report_on_the
_effect_of_dust_on_electronics.pdf
http://www.computerdust.com/downloads/special_report_on_the
_effect_of_dust_on_electronics.pdf
http://www.dwavesys.com/quantum-computing
http://www.extremetech.com/extreme/187746-by-2020-you-
could-have-an-exascale-speed-of-light-optical-computer-on-
your-desk
http://www.extremetech.com/extreme/187746-by-2020-you-
could-have-an-exascale-speed-of-light-optical-computer-on-
your-desk
http://coursemate.cengage.com/CPReader/View/9781133114598
/default.aspx?eISBN=9781133114598#70a7d313-0a5d-4ddc-
ba5c-766e5fb0dc77
ba5c-766e5fb0dc77
ba5c-766e5fb0dc77
http://ng.cengage.com/static/nb/ui/index.html?nbId=7345&nbNo
deId=1013914#!&parentId=1013922
http://ng.cengage.com/static/nb/ui/index.html?nbId=7345&nbNo
deId=1013914#!&parentId=1013922
2.9 Storage
2.10 Storage System Characteris-

tics
2.11 Floppy Disk
The floppy disk is an archaic physical external storage de-
vice that is now obsolete. There might be some banks that
still use this storage medium, but any business or person
who is considered computer literate does not use this sys-
tem to store information. The down sides to floppy disks
are that they are not compatible with any device that is
contemporary, their security is non-existent, and the stor-
age capacity is low - usually with a maximum of 1.44MB.
The last version of a floppy disk was released in 1987 by
IBM.
2.11.1 Storage Media, Storage Technol-
ogy, and Volatility
Types of Storage Media
Storage media is the hardware in which information is
physically stored. This differs from the storage device
which is usually the docking bay for the storage medium.
One example of a storage device would be your CD/DVD
drive in which you place your disks when inserting them
into your computer or your USB flash drive reader. Stor-
age media would be the actual CD/DVD disk itself or the
memory within your computer known as RAM. Storage
media can be internal or external meaning that it can be
either hard-wired to the computer, like the hard drive for
example, or it can be a separate physical storage facility
thats meant to be more mobile, like a USB flash drive,
Ipod, or an external hard drive for instance. Internal stor -
age media is usually faster since it is hard-wired to the
desktop or laptop and does not requires any extra space
outside of the computer. On the other hand, external me-

dia is very mobile, can be transferred from one computer
to another rather quickly, and is easily secured in a safe
place separate from your main working station. On top
of this the Non-Volatility of these storage medias have
made them very valuable. Normally when a computer is
shut down, any unsaved information is wiped clean from
the RAM, or if the information isn't being used, while
the computer is still on, the RAM may delete it to make
room for processes being recalled more frequently. Stor -
age media on the other hand, saves data despite the com-
puter being powered down and can only be deleted by the
user. Because of this, storage media such as flash drives
and data c.d.s are used for anything that would be needed
for future reference.
Magnetic Hard Drive
Bouncing Wave or ASE from a Laser Disk
Storage Technology usually comes in three forms; mag-
netic, optic, and solid state. Some common magnetic
storage systems are hard drives, floppy disks, and cassette
tapes. Though cassette tapes don't work with computers
they use the same technology and this is why they are
worth mentioning. In each case this type of technology
stores binary code using polar alignments on the magnetic
medium and can change those alignments as needed when
information is altered, deleted, or rewritten. The magnet
does this by converting the binary code from 1’s and 0’s
to positive and negative charges, respectively, which are
recorded on an iron oxide film inside the media. Optics
use laser beams which rely on marking the media. In this
case, lasers burn in lines of data which represent the bi -
nary code it is converting. “Rewritable” media has also
become a popular choice for those who want to reuse the

same disk. Rewritable media relies on changing the re-
2.11. FLOPPY DISK 37
flectivity of the media instead of scarring it. When the
binary number 1 is recognized, the laser alters the reflec-
tion of the discs surface in certain spots. Data is then
separated by the pits in between reflectivity which rep-
resent the binary number 0 so that 1’s alter the reflec-
tion and 0’s leave the reflection of the media as is. This
creates a “bouncing-wave” like appearance on the surface
of the disk called an Amplified Spontaneous Emission or
ASE for short. Solid State Drives, or SSD’s as they are
called, do not contain any moving parts such as lasers
or magnetic heads. They operate electronically by stor-
ing the binary code as electrons which are either trapped
or not trapped inside the flash memory cells within the
unit. These types of media tend to be faster than the other
two since they rely on electrical polarity within a cell in-
stead of electronic motors to be read or rewritten. This
also makes them more resistant to shock, allows them to
run more quietly, and reduces the latency of the media.
Typical storage media of this kind are “jump” drives or
“thumb” drives, but some computers use this technology
in their hardware as well.
2.11.2 Clusters, Sectors, and Tracks
A
B
C
D

Disk structure showing a track (A), a sector (B) and a sector of
track (C) and a cluster of sectors(D).
Hard disks have many circular pieces called platters in-
side them. These platters have two sides are made up
of tracks, sectors, and clusters. A cluster is a group of
sectors, and a sector divides tracks into pie shaped sec-
tions. Each cluster, sector, and track is numbered in order
to help the computer quickly locate where specific stored
data is. For example, data can be saved to side 2, sector
1, track 5. A track can be compared to the grooves on
a music record, because there are physical indents where
the data is actually stored. Data is read and written by a
read/write head, also commonly referred to as a “head.”
Each platter has a head. When data is to be stored on
a hard disk, the heads will align with the same track on
every platter, and write the data across each one. There
are a few measurements you can take to see how well a
hard disk preforms. The most important measurement is
calculating seek time. Seek time will tell you how long it
takes for a head to move from one track to another. The
quicker the seek time the better because that would mean
data can be reached faster.[1]
2.11.3 Random vs. Sequential
Sequential access
Random access
1 2 3 4 5 6 7 8
1 3 7 2 8 6 4 5
Random vs sequential access

When thinking of storage systems, one could presume
that all of your data in one folder is located next to each
other within the hard drive. This is false when talking
about random access. With random access your informa-
tion can be pulled from any location on the disk. Mean-
ing, your one folder could have its data scattered about the
physical hard drive. The benefit of this type of storage is
that you could access data in any order. Think of it as your
CD player, your favorite song ends and you want to hear it
again just hit back and you instantly hear it again. It’s fast
and nearly instantaneous, unlike sequential. You could
think of sequential access like a cassette within a cassette
player. When a song finishes and you want to listen to
it again, you must rewind the cassette, or if you want to
skip a song you must fast forward the tape.[2] This is used
with magnetic tape drives which, are used for backup pur-
poses. Even though in random access media devices may
seem like data could be misplaced or somehow lost in the
sea of data. When created, every file is given a unique
name by the computer system, other wise called address-
able media, in order to keep tabs on all the data.
Random access and sequential access of data are two sep-
arate ways a computer can access data. Random access
is the ability to access data in any given location within
the hard drive, quickly and efficiently. Most computers
use random access today, because it saves the user time,
as well as avoids confusion. Sequential access requires
data being accessed in a sequence. Examples of sequen-
tial access would be: data on a disk file, or magnetic tape
data storage. This can be useful to some users, if they
are purposely attempting to process a sequence of data
elements in order. However, this can also be time con-

CDROM-Random Access
Tape-Sequential Access
suming for users who are trying to find a certain file on
a disk or tape, which requires skimming through all of
the data in a sequence. An example of a comparison be-
tween random access and sequential access would be the
A-Z method. Sequential access would inquire the user
to go through letters A-Z to achieve the goal of meeting
point” Z”; whereas with random access, the user is able
to jump directly to point “Z”.
2.11.4 Storage Devices and Storage Media
The storage medium is a part of the storage system where
the actual data is stored, such as on a DVD or a memory
card. This medium can then be put into a storage device
like a DVD player or phone to read this data. You usu-
ally find these two parts to be separate pieces, making the
storage medium removable. Some storage devices can be
found inside of the system unit, while others are plugged
into an external port. There are letters on the storage de-
vice that go along with this that helps the unit to identify
USB Stick,Storage Medium
them. These letters or words describe where these are and
what they are used for. For example, when you plug in a
USB into the USB port on the computer, while viewing
this USB in “My Computer” you will see a letter next to it
verifying what it is used for in the system unit. Storage de-
vices contain primary and secondary memory. Primary
memory is volatile memory, which means that when the

device is shut off, the information is lost. Secondary is
the exact opposite, being non-volatile in that the memory
remains even if the computer is turned off.[3] The prob-
lem with these devices is you must be cautious with how
they are treated, especially if they have important infor -
mation. Misplacing or mistreating can result in a loss of
important data that could be impossible to get back de-
pending on the circumstances.
2.12 Hard Drives
Every computer contains one, if not two, hard drives.
There are internal and external hard drives. The internal
hard drive is located inside the system unit, and the ex-
ternal hard drive is connected to the computer for extra
storage. It is vital that an owner of a computer purchases
an external hard drive to backup his or her computer in
case it crashed. An external hard drive is extremely con-
venient to store information; however, one must be cau-
tious of the possibility of “hard drive theft” because i t
is easy for someone to access a random, external hard
drive into their own computer. Many people today use
a finger print or password to access to their hard drive
because of this reason. Without a hard drive, one could
not store the countless amount of information contained
to a computer. The hard drive holds a port to connect
to the motherboard.[4] There are a wide range of capac-
ity for hard drives, depending on the computer owner’s
preference.[5] Magnetic hard drives and solid-state hard
drives are two common hard drives used for computers.
A magnetic hard drive is the term computer users mean
when they say hard drive, and solid-state hard drives cause
flash memory technology. Without hard drives, many in-
formation and data would be lost and forgotte n.
• Magnetic hard drive

2.12. HARD DRIVES 39
External hard drives
• Solid-state hard drive
Datawalker LA18
Hard drives are used as primary storage units to store
most data and computer programs to operate on a com-
puter. The two types of hard drives available for purchase
are: internal hard drives, and external hard drives. There
are many things to consider if you are a consumer seek-
ing these storage devices. The internal hard drive, which
can be included in the computer before purchase, is di -
rectly connected to the motherboard, (A.K.A the brain
of the computer), as well as other components inside the
tower or casing of the computer/laptop. An external hard
drive is commonly used amongst users who are either
portably transporting data/programs from device to de-
vice, or seeking extra storage space for their files. Ex-
ternal hard drives can be very small, and convenient for
traveling with data. There are multiple different options
to explore while considering a hard drive: speed, consis-
tency, and durability. The types of hard drives offered
include either of the following: magnetic storage, optical
storage, and electrons which use flash memory media.[6]
2.12.1 Disk Access Time
Disk access time is a measurement that calculates the
amount of time it takes before for a drive to read and

Hard drive head
write data. Disk access time involves three major steps:
seek time, rotational delay (or rotational latency), data
movement time. Seek time is the amount of time it takes
for the head to move to the disk to prepare for reading.
Rotational delay is the delay that occurs when waiting for
the disk to begin rotating. Data movement time involves
the movement of data from the disk to memory of the
computer or the movement of data from the memory of
the computer to the disk. Maximum rotational latency
is the time it takes for the disk to perform a full rotation
excluding any acceleration time. There are two types of
ways in which a disk rotates: constant linear velocity and
constant angular velocity. Constant linear velocity occurs
when the rotational speed of the disk is dependent upon
the location of the head. Constant angular velocity oc-
curs when the disk is spun at the same speed regardless
of the location of the head, like vinyl records. Certain
low-noise disks utilize a slower disk access time to reduce
noise created by the hard drive. Slower rotational speeds
and seek speeds are purposefully installed to make sure
that audible clicks and crunching sounds don’t interfere
with recordings.
2.12.2 Hard drive interface standards
A hard drive interface (or hard disk interface) refers to
“the logical and physical means by which the hard disk
connects to the PC.”[7] For over a decade, the most com-
mon hard drive interface was by a wide margin AT At-
tachment/ATA, also known as Parallel ATA or PATA.
ATA is still used in modern PCs, but it is not as sig-
nificant as the more modern interface, Serial ATA, or
SATA. The more modern SATA uses smaller cables, is
more reliable, and possesses greater bandwidth than the

now-obsolete PATA. SATA and ATA are not compatible,
but there exist adapters to connect ATA interfaces with
SATA drives (or SATA interfaces with ATA drives). An-
other common interface is SCSI (or Small Computer Sys-
A hard drive with a SATA interface.
tem Interface), which is especially useful for multitasking
where multiple hard drives are used, such as in a work-
place environment.[8] Essentially, the difference between
these three interfaces can be summarized as follow s:
• ATA interfaces are cheaper and are still fairly com-
mon, but they are slower and outdated.
• SATA interfaces are the most useful: the only prob-
lem is that you need to buy additional adapters for
them to interact with older systems, but they are
still relatively cheap, they have high speed, and their
wires are small, which frees up more room in the
computer and helps prevent overheating.
• SCSI interfaces are very fast and can handle a wide
range of applications and amount of data, but they
are quite inexpensive and impractical for home use;
SCSI is used more for networks than personal use.[9]
2.13 Optical Discs
2.13.1 Characteristics
An optical disc is a flat, circular disc that stores data and

is made out of a very strong plastic called polycarbonate
substrate. This helps to protect the disc with many layers
of coating. Data on these discs are read optically, which
means that they store data using laser beams. Data can be
stored on one or both sides of the disc. The track, which is
a single spiral around the disc, spins from inside the cen-
ter track (or groove) to the outermost track for the data to
be read. Most people today have already switched from
VHS movies to DVD movies, and now to Blu-ray DVDs.
The advancement in technology has made viewing and
Optical Disc
burning capabilities for DVDs and CDs much more ben-
eficial. These optical discs do not degrade, like VHS and
magnetic media do. Optical discs are used in our every
day lives for storage, backing up, photos, movies, music,
and much more.
Read only discs are molded and stamped to show the
data so that it can only be read (and not over written).
This happens with most CDs for music and software, and
DVDs for movies. A recordable or rewritable optical disc
with a CD or DVD uses a laser to represent the data. An
example of this would be burning a CD for music, or an
iMovie project to a DVD. There is a complex process that
takes place when writing the data on the optical disc. To
mold or stamp the discs, bumps (called pits) are formed
on the disc’s surface. The places that are not changed
on the optical discs are called lands. Switching from a
pit to a land represents a 1 (like discussed in the system
unit). CD discs use infrared lasers, DVDs use red lasers,
and Blu-ray discs use blue-violet lasers. These different
types of lasers are used to store different amounts of data
at a more compact size.
Optical drives are the machines that read the discs of
CDs, DVDs, and BD drives. Many households have

switched to Blu-ray DVD players. However, users are
upset because only BD discs can be played on BD drives
which is considered a hassle to some. These drives are
also used to burn data on the discs.
2.13.2 History
Optical disks were invented in 1958 by David Paul Gregg,
he patented them. James T. Russell was then the first per-
son to have made a recording audio digitally to an optical
disk. Later Sony and Phillips research physicists made
the CD’s we know today that can store large amounts of
2.13. OPTICAL DISCS 41
Gnome-dev-removable
data. For this first generation of CD’s they could hold up
to 75 minutes of audio with 650Mb of storage. The pur-
pose of the first generation was only for audio and com-
puter software. They were capable of making a CD video
but the VHS cassette was more popular at the time and
it cost too much to produce them. These CD’s were read
with an infrared laser. Later the second generation could
store even more data and was used for video. They were
read with a visible laser light which allowed the lands a
pits to be smaller thus creating more space to for more
data. They allowed 4.7 GB of storage on a standard sin-
gle disc. The third generations are being developed to
create even more storage available, like a Blu-ray disc.
The Blu-ray disc use blue-violet lasers. There is even a
fourth generation to be discovered that could hold up to
one terabyte of storage.

2.13.3 CDs, DVDs, and BDs
Recordable CDs
Read-only optical discs include CD-ROM, DVD-ROM,
and BD-ROM discs. These are CDs or DVDs that come
with something already prerecorded on them and they
cannot be cleared. This is because the pits that are
molded into the surface of the disc are permanent. There
are also read-only discs for video games and different
software.[10]
Recordable optical discs are also sometimes referred to as
write-once discs. This means that these can be written to
but the discs cannot be reused or erased. These include
CD-R, DVD-R, DVD+R, and BD-R discs. The differ-
ence between the DVD-R and the DVD+R is the standard
being used. There is also a DVD-R DL and a DVD+R
DL, which indicates whether or not it is dual layer. Using
DVD+R will allow you to instantly eject the DVD without
having to wait for the finalized version. It also allows you
to record some of the DVD on a personal computer and
some of it on the TV. Another feature is that is it 100%
compatible with all DVD players. Recordable CDs are
often used for backing up files, making music CDs, or
sending large files to other people. BD-R discs are used
for even larger back ups that need even more storage and
they are used for high-definition multimedia files.[11]
Rewritable optical discs include CD-RW, DVD-RW,
DVD+RW, and BD-RE discs. These can be written on
and then erased and rewritten on. To rewrite on these
types of discs they use phase change technology. So ba-
sically the rewriteable disc is coated with a metal alloy
compound. They then use heating and cooling to write

on the disc without making it permanent. These are used
for backing up files but they are more convenient than
recordable optical discs because they can be used multi-
ple times.
Details about CDs
Small cdisk ubt
Compact Disc (CD) is used to store video, audio, and
data in different formats classified in the Rainbow Books.
It includes formats like CD-ROM (Compact Disc Read-
Only Memory), CD-R (Compact Disc- Recordable), CD-
RW (Compact Disc-ReWritable), VCD (Video Compact
Disc), photo CD, and Enhanced Music CD. Compact
Disc comes in standard 12 cm (120mm) or 8 cm (80mm)
in diameter. The most popular is the 12 cm type with a
74- or 80-minute audio capacity and a 650 or 700 MB
(737,280,000 bytes) data capacity. The 8 cm type is used
in electronic devices like portable compressed digital au-
dio players or data storage products like miniature CD
recorders.[12] CD-Rs were invented by Philips and Sony
and together with CD-ROM there were about 30 billion
CDs sold worldwide in 2004. The high-capacity record-
able CDs can hold 90 or 99 min of audio on a 12 cm
disc and 30 minutes of audio on a smaller disc (8 cm).
The ability to write beyond the manufacturer’s declared
capacity on a CD-R or CD-RW disc is called oversiz-
ing or overburning. However, Overburning might affect
product warranties and result in lost data so it is not rec-
ommended. However, it might affect product warranties

and result in lost data so it is not recommended.[13] These
days, more and more compact discs are being replaced by
flash drives or downloading.
Details about BDs
Blu-ray disc (BD-RE)
The newest form of optical disk is the Blu-ray disk (BD),
which was officially announced on February 19, 2002,
and was first available to consumers on April 10, 2003.
Blu-ray gets its name from the blue laser that reads it (as
opposed to the red laser that reads DVDs). BDs have
more storage capability than its predecessor and also has
a variety of new functions that DVDs did not have, such
as the following: record high-definition television with-
out losing quality, record one program while watching an-
other at the same time, automatically search for an empty
space on the disc to avoid recording over a program, and
access the Web to download subtitles and other features.
The way BDs achieve this is by having smaller pits, so
more data can be stored, and having a laser with a shorter
wavelength, a blue laser, that can read more precisely.
DVDs could not fit more information because a red laser
is not precise enough to read pits that are packed together
as close as the pits on a BD. Pits on a DVD could be
a minimum of 0.4 microns, while BDs pit minimum is
0.15 microns. Also, the track pitch on BDs has been re-
duced from 0.74 microns to 0.32 microns. Because of all
these improvements, a BD can hold more than 25 GB of
information, which is five times the amount that a DVD
can hold.[14]
Xbox360 scratch

How to Repair a Scratched CD or DVD Compact
Discs (CDs) and Digital Video Discs (DVDs) both store
their data externally on a disk. Unfortunately, as we all
have experienced, these disks often times get scratched,
making the CD or DVD skip, or sometimes not work at
all. Depending on where the scratch is located, the disc
may or may not be able to be repaired. It seems scratches
on the top, shiny part of the disc are harder to repair than
if the scratch is on the lower plastic part of the disc. Al -
though some companies are developing scratch resistant
discs, their efforts may be in vain due to technology mov-
ing fast past these forms of storage. For those people still
utilizing CDs and DVDs, scratches on them can be an-
noying and frustrating. There are a few simple remedies
consumers can try to repair their discs and attempt to get
more life out of them. The first step is to clean the disc
with a mild soap and water. This can help by removing
any finger prints that may be hindering the disks’ func-
tionality. Users then want to dry the disc with lint free
cloth, as even the smallest fibers can scratch and damage
the disc further. After the disc is dry, the user can then
apply toothpaste to it, smoothing it out in a straight di-
rection from the disc’s center. After this, the disc should
be rewashed to remove any excess paste. If this proce-
dure is successful, the toothpaste will fill in the scratches
2.14. FLASH MEMORY 43
so the disc can again be played with little or no skipping.
Often times, scratches to these discs are too severe for
this method to help. If that is the case, companies ad-
vise consumers to discard the disc altogether. Luckily,
as technology continues to advance, the reliance on these
forms of storage is decreasing, and with it, the annoyance

and frustration that comes from their malfunctioning.[15]
You don't need this anymore
Are Optical Discs Becoming Obsolete? While Opti-
cal Discs may be excellent media of storage, their neces-
sity has now come into question with the ever advancing
of technology. Floppy disks used to be what everyone
used to store information and that soon became obsolete.
As the cycle of technology inevitably catches up to opti -
cal discs, they may no longer be as useful as before. First,
there’s the rise of technologies that no longer make use
of optical discs because of the size. Most tablets and lap-
tops no longer having optical drives because they take up
space and may make the device less portable. Next is the
fact that there are many more storage options that have
become available that are much more convenient. Cloud
storage has been on the rise as well as regular flash drives
have had an increase in storage capacity as compared to
optical discs. Then there’s the fact that many media com-
panies have moved to a disc free environment. Stream-
ing services have made renting CDs and DVDs obsolete.
Gamers no longer buy physical discs but rather just down-
load a digital copy. Even music has moved to a streaming
service that makes buying physical albums and LPs more
of a novelty. Finally, there is the fact that consumers want
what’s convenient and optical discs are no longer as con-
venient as they used to be. However which way you look
at it, the advancement of technology will eventually make
anything obsolete. The future holds many possibilities for
other forms of storage and that too will eventually become
obsolete.[16]
2.14 Flash Memory
Flash Memory and How It Works

Word
Line 0
Word
Line 1
Word
Line 2
Word
Line 3
Word
Line 4
Word
Line 5
Word
Line 6
Word
Line 7
Bit Line
Select
Transistor
Ground
Select
Transistor
Bit Line

N N N N N N N N N N N
P
Flash Memory Structure
Flash memory is a type of storage device that uses elec-
tronic memory. Flash memory comes in a variety of ways
and is known as a solid state storage device, meaning
“there are not moving parts – everything is electronic in-
stead of mechanical.” Flash memory is used in many dif-
ferent devices, such as, computers, digital cameras, and
mobile phones. Flash memory is a type of EEPROM
chip. EEPROM stands for Electronically Erasable Pro-
grammable Read Only Memory. Inside of a flash mem-
ory chip is a grid of columns and rows with a cell. There
are two transistors at each intersection and a thin oxide
layer separates them. One transistor is known as a floating
gate and the other one is known as the control gate. An
electrical charge comes through the columns to the float-
ing gate, which is called tunneling. The electrical charge
causes the floating gate transistor to act like an electron
gun. When the electrons get trapped on the other side
of the thin oxide layer, closer to the control gate transis-
tor, they act like a barrier between the two transistors. A
cell sensor monitors the level of the charge. If the flow is
above the 50% threshold, it has a value of 1 and if it is
less, the value changes to 0. This is how information/data
is being read on the flash memory device. Nowadays,
flash memory has become the “dominant memory type
wherever a system requires a significant amount of non-
volatile, solid state storage.” [17]
Embedded Memory

Embedded memory is becoming an increasingly popular
type of flash memory due to its small, convenient size.
In today’s society these types of memory can be found
in phones, cameras, gaming devices, and even handheld
devices like a GPS.[18] In July 2013, Samsung announced
that they developed the world’s fastest embedded mem-
ory. These new products will be available in the 16,
32, and 64 GB sizes and feature an interface speed of
400 MB/s. This will increase user’s abilities to multitask
and perform tasks such as file transferring, browsing, and
gaming. It also decreases the amount of time it takes to
boot and load applications. This is a key factor in mobile
devices where the physical space for additional storage
or memory is limited. Memory cards are being used less
and less when manufacturing mobile devices and smart-
phones. One limitation of the chip is the amount of mem-
ory it could store. The larger the chip, the more expensive
the device is going to cost. Something else to consider is
the problem that arises if the device breaks. Any valuable
information that was stored on it is virtually irretrievable.
That is one advantage of having a removable memory as
discussed below.
Flash Memory Cards and Readers
One of many different types of flash memory card that exists on
the market.
If you want a fast and easy method of storing various types
of media, you can't get much better than a flash mem-
ory card. Most modern portable devices contain a flash

memory card because of its versatility and ease of use;
cellphones, mp3 players, and digital cameras are but just
a few examples of products that benefit from flash mem-
ory cards. However, just like how not all electronic de-
vices can use the same type of battery, not all flash mem-
ory cards are compatible with every electronic portable
device.[19] That’s why it’s always important to read your
user manual for instructions on the right card to purchase
if you ever need a replacement.
Although the devices themselves can only use a spe-
cific flash memory card model, most modern desktop
and notebook computers come with a flash memory card
reader. The reader typically supports a number of differ -
ent cards so you're able to organize and transfer the data
from card to computer. If you aren't one of the fortunate
few to have this reader built in to your computer, external
models are sold at most stores that sell computer compo-
nents and they're inexpensive.
Although a general-purpose flash memory card is used for
most applications, there are other special memory cards
Sony PlayStation Memory Card, made for gaming purposes
only.
that are made only for one unique purpose. For example,
a professional compact flash memory card is designed for
professional photographers for improved speed, quality,
and storage capacities, taking telling a story through a pic-
ture to the next level. Also, special gaming flash memory
cards are used for all game consoles, like Nintendo Wii
and Sony PlayStation, to hold saved game data. Other
special flash memory cards include HD memory cards for
capturing high-definition videos; netbook memory cards
to expand the storage of a netbook computer; and Wi-
Fi enabled flash memory cards used to wirelessly upload
photos from a camera. [20]

USB Flash Drives
Sushiusb
The USB storage device is one that has been growing
rapidly in popularity. It is a very user friendly form of
storage. To save information to a USB flash drive, one
simply must plug in the USB drive into the USB port
(usually on the side or back of the computer), click the
“save as” option on their project, then select the drive on
their computer which represents the USB. Then one can
eject the USB and take the saved information anywhere
2.15. OTHER TYPES OF STORAGE SYSTEMS 45
they need. USBs are quickly advancing as well. There
are now ways that you can create an entire mobile com-
puter, a fingerprint enabled secure file, and secure the use
of your computer all with the use of a single USB flash
drive. These new advances are sure to be hot on the mar-
ket. USBs are high in demand right now, not just because
of their technical abilities but also because of how you can
choose a USB to fit into any lifestyle or match any person-
ality. There are thousands of custom USBs available in
stores and online. These range in colors, sizes, amounts of
memory, and even shapes.[21] USB flash drives are some-
thing that will definitely be here to stay for a while longer,
even with the ever emerging cloud. USB flash drives are
also very secure ways to store information. Since they are
not connected to the Internet, they cannot be hacked, and
some can be encrypted to prevent unauthorized access.
The one down side to this use is the possibility of the
flash drive being lost or stolen, but with proper precau-

tions and organization, this can be avoided. Flash drives
also preserve data and documents in a non-volatile state.
As some specialized computers (such as theatre control
boards) are prone to crashes and glitches, saving infor-
mation on a flash drives prevents is from being corrupted
or lost in the event of a system crash or other glitch. In
simpler systems, flash drives can be used as the central
storage point for a computer. While this may be ineffi-
cient on most machines, those that are single use and do
not require large amounts of memory can benefit from
this, as the system is flexible, and more memory space
can be added as needed. However, the primary benefit
of flash drives remains the mobility. Flash drives are an
inexpensive and more secure alternative to the cloud and
other means of Internet storage.
USB flash drive
USB drives are the perfect devices for transporting data
and files. They are easy to use and their portability makes
them incredibly convenient. In addition to storing files,
they can also be used to run portable apps. Certain ap-
plications can be turned into portable versions of them-
selves. You can have access to various software appli -
cations to use on any computer. Free programs exist to
convert applications to portable ones to, in essence, cre-
ate a portable PC on a thumb drive. USB drives range in
storage capacity from 2 GB to 256 GB. With 256 GB of
storage in such a portable size, the limits to their use are
virtually endless.
USB drives can be password protected, or some can even
be secured using biometric features, like a finger print.
There are some concern related to USB drive security.
They can contain large amounts of information, and
given their portability, they can be used for transporting

files secretly. Anyone with access can simply plug a USB
drive into a computer, copy files onto it, and remove
them from the premises. USB drives carry an additional
security risk in that they can contain malware that can
be launched using AutoPlay as soon as they are plugged
in. http://www.howtogeek.com/203061/don%E2%80%
99t-panic-but-all-usb-devices-have-a-massive-security-problem/
2.15 Other Types of Storage Sys-
tems
SAN NAS
N
AS
CL
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N
TS
BL
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CK
ST
O
RA
G
E
N
ET

W
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RK
FI
LE
SE
RV
ER
S
FiberChannel, iSCSI, or AoE SMB, NFS, AFS
Network Storage
2.15.1 Remote Storage
Remote storage is there to expand the disk space without
hard disks and isn’t connected to the computer directly
but accessed through internet. That way you can access
your files wherever you are, whenever you want, on your
laptop or Smartphone or even a different computer. This
is the basic concept of cloud storage. When you need to
access a file, you open the file as usual but if the data isn’t
on your local volume, Remote Storage retrieves the infor-
mation from a media library. When data is removed from
a file, the logical size of the file remains but the physical
size is reduce. [22]
Being much faster and reliable than storage devices like
CDs, DVDs, hard disks, and flash drives, an online re-
mote storage provides protection against system errors
like viruses, and enables one to recover lost data from
any potential system crashes. Being critical to not only

businesses, but home computer users as well, an online
storage provides low-cost and easily accessible security
for data management and storage. To assure maximum
security, many online companies automatically backup
systems on a daily, weekly, or monthly basis, to an “elec-
tronic vault.” Also, unlike CDs or DVDs, using remote
storage diminishes its vulnerability to damage and data
http://www.howtogeek.com/203061/don%25E2%2580%2599t-
panic-but-all-usb-devices-have-a-massive-security-problem/
http://www.howtogeek.com/203061/don%25E2%2580%2599t-
panic-but-all-usb-devices-have-a-massive-security-problem/
loss. Living in today’s high-tech society, the online re-
mote storage system is definitely a very essential, yet af-
fordable tool to assure that the countless amounts of data
being saved on devices is still remediable after a com-
puter failure. [23]
2.15.2 Holographic Storage
Detector
Gating light
Laser
Beam splitter
Mirror
Shutter

Crystal
Holographic Data Storage
Holographic storage utilizes photo-sensitive media and
innovative laser beam technology as a means of computer
storage. This is unlike previous methods of data record-
ing, such as magnetic and optical hard drives, which in-
volve a rotating disk or simple 2D lasers. Instead, holo-
graphic storage begins with a single laser that is split
into two separate parts -- the signal beam (carries data),
and the reference beam (reconstructs hologram when
prompted). A spatial light modulator is used to encode
data for the signal beam, followed by a conversion of elec-
tronic data into binary code. It is then arranged into a
specific pattern of dark and light pixels (representing ze-
ros and ones), consisting of >1 million bits each. The
signal and reference beams intersect, and a holographic
image is created through a 3D refraction that is etched
into the media. Advantages include a safe, fast, reliable,
and portable system of storage. Disadvantages include
expense, limited capacity, and recording fails. Since the
concept is still in its infancy, however, problems are ex-
pected to diminish greatly over time.
[24]
2.15.3 Storage area network
Storage area networks are clusters of high performance
computers used to transfer huge amounts of data. SANs
are also used for distributed processing applications re-
quiring fast local network performance and designed
specifically for data management. SANs move storage
resources off the common user network and into an inde-
pendent network. What this does is allow each server too
access any shared storage extremely quickly, as if it was

already attached to the server. Typically, a SAN is assem-
bled using three components: cabling, host bus adaptors,
and switches. [25] [26]
The storage cloud enables storage devices like a PC, a desktop,
or
a mobile phone to communicate with the host computer system,
as well as with each other.
What makes a good storage area network? A SAN defi-
nitely needs to be indestructible and have a built-in pro-
tection against any potential harmful failure. If a SAN is
vulnerable to failures and is unable to recover lost data, an
enterprise may even go out of business! Secondly, a vast
amount of storage capacity is another essential to a valu-
able storage network; since the number of devices con-
nected to one host system may increase by time, the or-
ganization’s storage and processing also needs to expand
accordingly. A big advantage of using a good storage area
network is the fact that even if all of one’s system servers
crash, the SAN remains online and provides disaster re-
covery. [27]
2.15.4 Network Attached Storage
NAS is a type of dedicated file storage device typically
connected by a wired networking connection, therefore
only providing local area network users with storage.
NAS supports file transfers, in which it will back up any
data that appears in the form of files, such as email boxes,
web content, remote system backups. The main advan-
tage of a network attached storage is that network storage
is no longer limited to the amount the computing device
can hold. NAS devices typically look very box-like, with-
out a keyboard or display. NAS products come in levels
of capable storage space, drive capacity and drive scal -

ability, often placed into one of 3 categories: Desktop
NAS, devices aimed at small businesses and home users;
Mid-market NAS, devices capable of running several
hundred terabytes but not clustering; Enterprise NAS, de-
vices that can store huge amounts of files, including vir-
tual images, and being able to NAS cluster. [28] [29]
2.15. OTHER TYPES OF STORAGE SYSTEMS 47
NAS
2.15.5 NAS vs SAN and Cloud Storage
Both systems of storage serve different purposes for their
clients. The main difference between SAN storage and
NAS storage is the way that the systems interact with the
network. A NAS network will behave in a way that makes
it similar to any other network component. In contrast,
the storage devices of a SAN network are found in a sep-
arate network but connected to the main one. Overall
though, both systems are used for storage and over time
the performance offered by both is becoming harder to
distinguish. For example a SAN uses Fibre Channel in-
terconnects while NAS makes Ethernet and TCP/IP con-
nects, but now many SAN systems are switching over to
those connection routes NAS systems use.[30]
Cloud storage, sometimes just called online storage, is
simply the use of a remote storage device that is accessed
by means of the internet. Cloud storage has seen a mas-
sive increase in popularity over the last few years, and the
industry for it has grown substantially to the point where
there are now hundreds of companies that offer a vari -
ety of cloud storage services. More specifically, some

cloud services focus only on digital pictures or email mes-
sages, while other systems store all kinds of digital data.
Some services, like Google Drive, allow users to save
Sharing via “The Cloud”
their files in one of many massive data centers Google op-
erates where, for instance, multiple users can collaborate
on projects by having access to the same file.[31]
As the cloud’s popularity is growing, more and more busi-
nesses are transferring over to its storage capabilities.
Many businesses are using the application as a back up
program for their software and documents. By scheduling
a set time for the computer to automatically transfer doc-
uments over, businesses can be sure that their information
lies safely in the hands of the Internet without having to
spend the tedious amount of time backing it up manually.
Though the different applications of the cloud do some-
times have a monthly fee to pay, it is a small price to pay
for the time and convenience it lends you. By utilizing
these applications, anybody is able to access their doc-
uments anywhere worldwide. An individual is no longer
tied down to just one electronic device in one set area, but
can instead revise a version of a document on their laptop
and then pull it up at work for a presentation the next day.
This is just one example of the hundreds of ways that the
application can be used conveniently to meet your day-
to-day needs. The cloud is connecting electronic devices
all across the globe and making every day processes just
a little bit easier. [32]
Despite of the fact, that a Cloud storage term has ap-
peared in use quite recently, people and businesses ac-
tuality use online storages for a long time. For example
saving copies of letters on mail server or retrieving net-

Cloud Services
work configuration files from TFTP server. These days
Cloud storage term should be considered is one of many
other Cloud computing services. It could be provided as
separate product – “Storage-as-a-Service”, and also be a
part of others, for example: Infrastructure-as-a-service,
Platform-as-a-service or Software-as-a-service. As was
mentioned above, the rapidly growing popularity is pri-
marily due to quite low cost for a service itself (Storage-
as-a-Service) when users pay only for the volume of data
they stored, and if we are talking about the Infrastructure
or Platform services which are great opportunity for busi -
ness to reduce an IT expenses as well. With all advantages
are given by online storing, there are few things users
should be aware deciding entrust the care of their data to
the provider. It might be as purely technical concerns (re-
liable internet connectivity, provider’s backup algorithm,
disaster recovery, security of access, etc.) and legal as -
pects as well (ownership of data, jurisdiction, rights to
audit). [33]
2.15.6 Smart Cards
Back of a smart card
A smart card is a credit card-sized piece of plastic that
contains computer circuitry, like a processor, memory,
and storage. Smart cards can only store low amounts of
data, around 8 kilobytes of RAM or 346 kilobytes of
ROM. The processor is actually a microprocessor, and

Chapter 2Hardware2.1 The System Unit2.2 Data and P

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