COMPTIA A+
220-901 STUDY GUIDE
BY POWERCERT
Written by Scott Prieto
From the creator of PowerCert Animated Videos
on
Version 2.0
This ebook is designed to study for the
CompTIA A+ 220-901 exam.
Check out my youtube channel:
PowerCert Animated Videos
© PowerCert 2017. All rights reserved. No part of this document
may be reproduced nor transmitted in any form, by any means
(electronic, photocopying, recording, or otherwise) without the prior
written permission of the author.
TABLE OF CONTENTS
1 input Devices & Peripherals 77 cooling
Keyboards, mouse, digital cameras, Case fans, passive vs active cooling,
barcode scanners, scanners, heatsink, thermal compound, water
touchscreens, webcams, card cooling.
readers, docking stations, KVM
83 cpu, socket, & chipset
switches, smart TVs, biometric
devices, motion sensors, digitizers, ZIF, PGA, LGA, Intel & AMD socket
gamepads & joysticks. types & CPUs, CPU core, 32 vs 64-bit,
memory cache, northbridge,
12 Monitors
southbridge, buses, hyper-threading.
CRT, LCD, LED, TN vs IPS
98 bus slots
backlighting, degauss, resolutions.
PCI, PCI express, PCI-X, mini PCI.
19 printers
102 mobile issues - PHONES & LAPTOPS
Inkjet, laser, thermal, dot matrix,
printer issues, trouble shooting, Not responsive, apps not loading,
virtual printing. slow performance, GPS, no display,
dim display, inverter, flickering
31 storage devices
monitor, keys sticking, ghost cursor,
Hard drives, SSD, tape drives, CD, overheating, battery not charging,
DVD, Blu ray drives, discs, SD cards, intermittent wireless connection.
eMMC.
111
bios/cmos
39 power supply BIOS, CMOS, battery, settings, POST,
beep codes, UEFI, secure boot.
Power supply, connectors.
42 motherboard 121 Front Panel Connector
Motherboard, form factors, ATX, AT, Motherboard connector, front USB &
Micro ATX, BTX, NLX, ITX. audio ports, power & reset buttons,
drive activity light.
46 motherboard i/o interfaces
123 RAID
PS/2, USB, serial, parallel, firewire,
RAID levels 0, 1, 5, 10.
NIC, video, sound, eSATA, eSATAp.
53 adapter / expansion cards 128 networking cables & connectors
Video card, VGA, DVI, S-Video, HDMI, RJ-11, RJ-45, BNC, F-type, firewire,
DisplayPort, sound, USB, RAID, USB, thunderbolt, RCA, LC, ST, SC,
eSATA, video capture, TV tuner, NIC, plenum vs non plenum, powerline
wireless NIC, network adapter, HDMI, wiring
standards.
62 ram (memory) slots
139 firewall
DIMM, SIMM, bit vs byte, data paths
Host-based firewall.
64 ram
DRAM, SRAM, SDRAM, DDR, 140 media types
bandwidth, dual channel, triple
Twisted pair cable categories, UTP,
channel, single-sided vs double
STP, coaxial cable, single & multi-
sided, ECC, SODIMM, buffered vs
mode fiber.
unbuffered.
144 network components
Cable modem, hub, switch, bridge,
router, PoE, wireless access point,
NIC, MAC address, modem card,
patch panel.
150 wireless technologies
Wireless standards, bluetooth.
151 ip address
IPv4, IPv6, subnet mask, public &
private IP addresses.
157 ip addressing methods
DHCP, dynamic, static, APIPA.
160 tcp/ip protocol suites
TCP, UDP, DNS, NAT, FTP, SFTP,
TFTP, SMTP, POP3, IMAP4, HTTP,
HTTPS, telnet, SSH, SNMP, ports.
170 ports
Port numbers and services.
171 internet access technologies
DSL, ADSL, SDSL, VDSL, broadband
cable, POTS/PSTN, ISDN, satellite,
mobile hotspot.
176 network types
PAN, LAN, MAN, WAN.
178 networkING TOOLS
Wire crimper, punch down tool,
media tester, cable stripper,
multimeter, tone generator,
182 soho routers, wifi encryption
DHCP, SSID, channels, WEP, WPA,
WPA2, WPS, MAC filter, DMZ.
193 Network Utilities
Ping, traceroute, nbtstat, netstat,
ipconfig, ifconfig, default gateway,
nslookup, dig.
Input Devices &
Peripherals
One of the most basic input devices on a computer is a
keyboard. A keyboard is a device that is used to input
commands to the computer. It has keys that are made
up of alphabets, numbers, and symbols that you can
press with your fingers. The most basic function of a
keyboard is to do things like word processing, write
letters, emails, visit web pages, and so on. Keyboards
come equipped with two different connector types.
There's the older 6 pin DIN connector, which has pretty
much become obsolete, and there is also the modern
USB connector. A lot of keyboards will have the ability to
use both connectors because a lot of times they will
come with a DIN to USB adapter which you can use with
any computer with either a DIN or USB connection.
Keyboard
A mouse is another basic input device that is used on a
computer. It's a pointing device that fits in the palm of
1
your hand and replicates the movement of the mouse
onto the computer screen.
Wireless mouse Wired mouse
It’s used for things like starting applications, file and
folder management, surfing the internet, and so on. A
mouse will typically have one or two buttons. A
Macintosh mouse will have one button, while a Windows
mouse will have at least two buttons. A mouse can be
either wired or wireless.
A digital camera is a device that takes digital pictures
and videos. Unlike standard cameras, where the images
are stored on film, a digital camera stores the images on
its internal storage or SD card. Then once the images
are stored, they can be transferred to a computer by
using a USB cable or by the SD card. Then once they're
on the computer, the images can be viewed or printed.
Digital
camera with
an SD card.
2
A barcode reader is a device that is used for reading
barcodes. It uses light to scan barcodes and it's
typically used to detect point of sales and maintain
inventory. It can connect to a computer through a serial
port, USB port, or a wireless connection. Barcode
readers come in several forms, but the most popular is
the handheld trigger type.
Handheld trigger
type barcode reader
Now a scanner is a device that enables you to put a
digital copy of a physical copy, on your computer. So
for example, if you have a photo or a document and
you wanted to put a digital image of that photo or
document on your computer, well that's what a scanner
enables you to do. Scanners will typically have a
flatbed where you can place a photo or document, and
at the press of a button, it will scan it for you. Then
once it's done scanning, it will save the document or
photo to your computer. Scanners will typically come in
a combination with a printer, or you can also purchase
a scanner all by itself.
3
Flat bed scanner
A touchscreen is basically an LCD monitor with an
input detection system. It's a grid that senses the touch
by a finger.
Touchscreen monitor
It works the same way as if you were using a mouse, but
without the mouse itself because you are using your
finger instead. The touchscreen receives a touch in the
same way as if you were clicking a mouse button.
4
Typically one click of the mouse button equal one tap by
a finger, and two clicks of the mouse button equal two
taps by a finger. Touchscreens are commonly used in
all-in-one computers, and also in tablets, such as the
iPad. They're also used on certain phones with touch
screen technology.
Devices that use touchscreen technology.
All-in-one iPad tablet Smart
computer phone
A webcam is a device that is
used for capturing video and
images. Webcams are mainly
used for video conferencing and
video calling over the internet. So
any two people in the world can
visually communicate with each
other if they both have a webcam
Webcam and an internet connection.
5
Most webcams also have a built-in microphone to
capture audio. A webcam connects to a computer
through a USB cable and they are often used with
messaging applications such as Skype, for making visual
calls. Two of the biggest manufacturers of webcams are
Logitech and Microsoft.
Webcams used
during a video call.
A media card reader gives the computer the ability to
read memory cards from devices such as cameras. It's
a small device that usually has a USB cable that
connects to a computer and then the body of the reader
has slots to accommodate various sizes of memory
cards, for example, micro SD and mini SD cards. Then
once connected, the data from the memory cards can
be read and transferred to the computer.
Media card
reader
SD cards
6
A docking station is used for laptop computers. It's a
device that is used for basically turning your laptop into
virtually a desktop computer.
Docking station
We all know that laptops are generally smaller than
desktops. For example on the laptop, the monitor and
keyboard are generally small. So if you wanted to use
your laptop at your desk and you wanted to use a
bigger monitor and keyboard, you can simply set the
laptop in the docking station and it will automatically
connect to them and use them, depending on what is
already plugged into the docking station, whether it's a
monitor, keyboard, mouse, printer, etc.
Laptop in Docking
station
7
It eliminates the hassle of connecting all these devices
individually. You just simply attach the laptop into the
docking station and then start using the devices
instantly. But there's one thing to remember about
docking stations, and that is that they are specific to the
manufacturer of the laptop. So there is no such thing as
a one-size-fits-all docking station. You need to get the
specific one for the laptop.
KVM switch
A KVM switch allows you to control multiple computers
from a single monitor, keyboard, and mouse. A KVM is
typically a box with ports for a monitor, mouse, and
keyboard. Each computer has their own individual cable
connection to the KVM. Each KVM has buttons that you
can press so that you can switch to a different computer
that you want to control. KVMs also come in different
sizes, depending upon how many computers that KVM
can handle. A low-end KVM switch will have the ability to
control two computers, while a higher-end KVM can
control 8 computers. KVMs are handy when you want to
control multiple computers without the need for a
dedicated monitor, keyboard, and mouse, for each one.
This not only saves money, but it also saves space.
8
A smart TV is a television where you can not only
watch TV, but you can also connect to the internet. So
basically it's a television combined with a computer.
And when it's connected to the internet, you can go to
web pages, stream movies, and television shows. A
smart TV can also interact with other people across the
internet by using video messaging services such as
Skype because a lot of smart TVs will also have a built-
in webcam and microphone.
One way to prove the identity of a person is by using a
smart card. A smart card is a good choice to prove
your identity because you always have to have it with
you when proving your identification. A smart card is
the same size as a credit card with an embedded
microprocessor chip.
Smart card reader Smart card
9
There is also a smart card reader which is a device that
is used to accept and read smart cards.
A biometric device is used
to prove the identity of a
person by recognizing unique
physical characteristics, for
example, a fingerprint
scanner. Fingerprint
scanners are used to read a
user's fingerprint, to prove
authentication. These days a
lot of fingerprint scanners will
be built into a device such as
Laptop with built- a laptop or a smartphone.
in fingerprint
scanner You just swipe your finger
across the fingerprint scanner
and the scanner what either
grant or deny you access
based on your fingerprint.
Another type of input device
is a motion sensor. A
motion sensor records your
hand movement in mid-air
without making any physical
contact with the device. A
motion sensor would also
typically connect to your
computer using a USB Motion sensor
cable.
10
A digitizer is a device that is used to convert analog
movement, such as a hand drawing, and convert it into
a digital form on your computer. It's a tablet with a
stylus, and as you draw on the flat surface using a
stylus, it will record the image from the stylus and
process the drawing on your computer screen. A
digitizer typically connects to your computer using a
USB cable.
Digitizer
Other input devices include gamepads and
joysticks. These are controllers that would typically
be used for gaming systems, such as Xboxes and
PlayStations. But you can also use these for
computers, and if you're going to use these with a
computer, they would typically connect using a USB
connection.
Gamepad Joystick
11
Monitors
The computer monitor is a primary output component
of a computer. It connects to the computer's video
adapter through a monitor cable and displays images on
the screen. A computer monitor may have a VGA, DVI,
HDMI, or a DisplayPort.
CRT Monitor LCD Monitor
Now an older type of monitor is called CRT. CRT
stands for a cathode ray tube, which was the technology
first used in TV sets. These monitors are bulky and
heavy and take up a lot of space, and they are pretty
much non-existent in the marketplace today.
An image is produced
on a CRT by using 3
color electron guns.
These colors are red,
blue, and green.
Which, when you
combine them, can
produce any color on
3 color electron guns the color spectrum.
12
These guns shoot beams of electrons on the screen
and create an image that we see. These beams
repeatedly sweep across the face of the monitor, many
times per second. So it's constantly redrawing the
image that we see on the screen.
This redrawing of the
image is known as the
refresh rate. The refresh
rate is measured in hertz.
So for example, if the
refresh rate is 60 hertz,
and that means that the
beams sweep across the
entire face of the monitor,
redrawing the image at The refresh rate is the
the rate of 60 times per number of times per
second. Now to the second that a monitor
redraws the image.
naked eye, most people
cannot detect this
because it does it so fast.
But a lot of times, some people complain of discomfort
in their eyes because they are noticing this constant
refreshing of the image. But this problem is usually
solved by increasing the refresh rate, which makes the
refreshing of the image less noticeable, which reduces
the amount of eye discomfort.
13
Inside CRT monitors is a metal plate called a shadow
mask. This metal plate can pick up outside external
magnetic fields, which can cause discoloration on the
screen, and because of this, CRT monitors need to be
degaussed.
Before a degauss After a degauss
Degaussing is the process of getting rid of the
unwanted magnetic fields. Most CRTs do an
automatic degauss when the monitor is turned on, or
the monitor may have a button that you can press to
do a degauss.
Another type of monitors are
LCD, which stands for liquid
crystal display. LCD monitors
produce an image on a flat
surface by using liquid crystals.
Light shines through these
crystals to produce an image
on the screen, and it uses
LCD monitor
14
filters to produce different colors. LCDs were first used
in laptop computers. And now have made their way to
the desktop marketplace and have completely
replaced CRT monitors. They are lighter, thinner, use
less power, and take up less space than CRTs. LCDs
are also known as flat panel displays.
Modern LCDs use a technology called TFT, which
stands for thin-film-transistor. And as its name
implies, this technology uses a thin-film-transistor to
create a higher quality image, when compared to a
standard LCD, because each single pixel on the
screen has its own transistor. All LCDs sold today
have TFT technology.
In order for LCD monitors
to show an image on the
screen, it needs to have a
light source, and there are
a couple of different types
of backlighting that an
LCD monitor uses. One
type of lighting is by using Monitor with fluorescent
lamp backlighting
fluorescent lamps.
These fluorescent lamps are the circular, glass, straight
tubing types, similar to regular fluorescent lamps that
we're all used to seeing. These lamps emit ultraviolet
light that's created when the mercury vapor inside the
lamp is ionized.
15
Another type of backlighting
that LCD monitors use is
LED. LED monitors use
multiple light emitting
diodes that are arranged in a
pattern that displays the
images on the screen. Now
this is a more modern form of
backlighting compared to Monitor with LED
backlighting
fluorescent lamp backlighting.
Most, if not all new LCDs, use
LED backlighting.
Now both of these monitors are considered LCD
monitors, but the LCD that uses the LED backlighting, is
considered an LED monitor. So an LED monitor is just
an LCD monitor that uses LED backlighting.
Now there are two different types of LCD monitors that
you’re going to need to know for the exam.
And one of them is called TN. TN stands for twisted
nematic. This type of LCD monitor works by liquid
crystals actually twisting the light as it comes through.
TN is an older and cheaper technology that’s been
around for several decades. The viewing angle and the
color reproduction on a TN monitor are not as good as a
more modern LCD monitor. A TN monitor is often used
with calculators, digital watches, and older LCD
monitors.
16
A newer and more modern type of LCD monitor is IPS.
IPS stands for in-plane switching. This type of monitor
works by instead of the liquid crystals twisting, like in a
TN monitor, the liquid crystals stay in place and are
aligned in parallel with the glass. IPS LCDs use more
transistors than a TN monitor, so as a result, it does
consume more power. IPS was developed because of
the limitations of TN monitors, so as a result, IPS
monitors have better color reproduction and better
viewing angles.
Viewing angle
comparison
IPS monitor has a
better viewing angle,
compared to the TN
monitor.
TN monitor IPS monitor
Resolution is defined as the
number of pixels that are
used to display an image on
the screen. For example, if a
monitor is set to a resolution
of 1280 x 720, then this
means that there are 1280
horizontal pixels, by 720
vertical pixels.
17
Which means that there are 921,600 pixels that are
being used. The higher the resolution, the higher the
number of pixels will be used. Which means a clearer
and sharper image. Depending on the hardware and
software being used, resolutions can be set anywhere
from 640 x 480, all the way up to ultra-high definition at
3840 x 2160. LCDs produce their best quality image
whey they are set to their highest resolution, which is
called their native resolution.
18
Printers
Printers allow the
ability to print copies of
documents and photos,
onto paper from a
computer. There are
several different ways
that a computer can
physically connect to a
printer, but the most
common way is by
using a USB cable.
This is known as a local connection because the
printer is directly connected to the computer. But you
can also connect a printer to a network if the printer
has a network interface, such as an Ethernet port or a
wireless network card. These are known as network
printers. Network printers are convenient because
they can be placed almost anywhere in a home or
office, as long as it's connected to the network (wired
or wireless). Another method of connecting is through
a network share.
Printer being shared over a network.
19
For example, you can allow other computers that are
on your network, connect to your local printer by
sharing your printer over the network. So after the
network share is complete, the other computers can
now print to the printer that is connected to your
computer. So your computer basically acts as a
gateway for other computers to access your printer.
But the drawback is that your computer has to be on in
order for others to use your printer.
There are several different types of printers. There are
non-impact printers and impact printers. Non-
impact printers print without striking an ink ribbon onto
paper, these include laser, inkjet, and thermal printers.
Impact printers are dot matrix printers, which will talk
about shortly.
Inkjet printers are the
most common printers that
are used for home use.
An inkjet printer works by
the print head moving
back and forth across the
paper during printing.
During this process, the
print head places ink on
the paper in very tiny
dots. In fact these dots
are so tiny that they are
smaller in diameter than a
human hair.
20
As these dots are precisely placed, they form to create
an image on paper.
Lower-end inkjet printers
typically come with two ink
cartridges, one is for color
and the other is for black.
Higher-end inkjets may
come with four ink
cartridges.
Inkjet printers are more affordable than laser printers
and they can produce photo quality results, but one of
the drawbacks is that the ink from an inkjet printer may
smudge, while ink from a laser printer does not
smudge.
Laser printers come in different sizes, from small
personal ones to larger ones for businesses. Laser
printers provide the highest quality print available
today and they are the most expensive.
21
A laser printer basically works by first placing an
electric charge on a rotating drum.
Rotating drum
Then a laser discharges a lower electrical charge on
the drum.
Laser drawing
image on drum.
So basically the laser draws the image that is going to
be printed, on the drum itself.
22
Then the drum is coated with a fine black powder,
known as toner. And as the drum is being coated, the
toner only clings to the areas where the laser has
drawn.
Black toner coating
the drum.
Then as the paper goes through the printer, the toner
is placed on the paper. And the result is a high-quality
print that is second to none.
Toner being placed
on paper.
23
Another non-impact printer
is called a thermal printer.
Thermal printers print by
using heat. They use a
special paper called
thermal paper, and on this
paper is wax-based ink.
When heat is applied to this
paper, it turns black. So in Thermal printer
a thermal printer, the only
thing the print head does is
apply heat to the areas
where the ink should be
placed. Then when the ink
is cooled it becomes
permanent. And because
of this technology, thermal Wax-based thermal paper
printers are very quiet.
Thermal printers are commonly used for printing
labels and barcodes.
Dot Matrix printers are
almost non-existent today.
They are an old
technology that produced
mediocre print quality
when compared to laser or
Dot matrix printer inkjet printers. They are
also very noisy.
24
Dot matrix printers are impact
printers. The print head in a Prints characters in the
dot matrix printer moves form of dots.
across the paper, and as it
moves, the pins on the print
head strike against a cloth ink
ribbon which then comes in
Printer Issues
direct contact with the paper,
producing each character in
the form of dots.
But despite being and outdated technology, dot matrix
printers can print multi-copy documents, such as
carbon copies. They are also very durable and last a
long time.
Several issues can
happen when you're
printing. For example, if
you're printing something
and you see streaks, then
this could be a problem
with the ink cartridges in
an inkjet printer.
A lot of times the software that comes with the printer
will have a list of tools that you can use to clean the
print head. However, if the streaks are real bad, you
25
may have to remove the ink cartridges from the print
head and manually clean them with a lint-free cloth.
Another problem that
could happen, is when you
try to print something and
the image is faded or it's
completely blank. This
could also be a problem
with dirty ink cartridges, or
it could be that you're low
on ink or out of ink.
Ghosting is a problem
that can happen with laser
printers. Ghosting is
when you see a faint
image of a page you
previously printed and you
see the same image on a
newly printed page.
This is usually caused by the drum or the fuser. The
drum on a laser printer has a lifespan after so many
prints and then you have to replace it. So you can try
replacing the drum, but if you still see the same
problem after you replace the drum, then the problem
could be the fuser. If the problem is the fuser then
depending on what printer you have, you might need
to take the printer to a professional to get it fixed if
you’re not familiar with changing the fuser.
26
Paper jams are
another problem that
can happen with
printers. So if you try
to print something and
the paper doesn't
come out, then you
could have a paper Paper jam
jam.
Paper jams could be caused
by debris inside the printer,
and debris inside the printer
could also be the reason
why the paper is coming
out creased. Paper jams
could also be caused by
faulty pick up rollers. This
typically happens with older
printers. When rollers wear
out, they tend to have
difficulty grabbing the paper
and feeding it through. So
in these cases, you might
want to inspect the rollers to
Old and worn out pick up
rollers could cause paper see if they need replacing,
jams and creases. or open up the printer and
check for any debris inside
the printer.
27
Another issue that could
happen, is that when you're
printing something and the
color may not print
correctly. Then all this
could be, is that one of your
color ink cartridges are
faulty, or they are low on ink
or even out of ink.
A lot of times when you try
Be sure printer is turn to print something, and
on and plugged in.
nothing happens! Well
this could be a
connectivity issue.
Connectivity issues are
extremely common
especially when you're
dealing with network
printers. But the first
Check LCD for
messages. things to check are the
obvious ones. For
example, make sure the
printer is turned on.
Check for any errors on
Check for the printer's LCD (if it has
connections on one). If it's a network
network printers.
printer with a wired
connection, make sure
28
Virtual Printing
the network cable is connected. You should always
check the obvious things first before diving into the more
complicated issues, such as checking if the network
printer has an IP address.
Instead of printing a document unto physical paper. You
can also print your document and store it on your
computer in a digital form. This is called virtual
printing. Virtual printing is done for several reasons,
and one of those reasons is called print to file.
Printing a document to a file, saves the document in a
format that another printer can print. So for example, if
you wanted to print something and you don't have a
printer, you can use the print to file feature and it will
save the document in an uneditable digital form that can
be sent to another computer that has a printer, and then
that computer can print the file for you.
Another form of virtual printing is called print to PDF.
PDF stands for portable document format.
29
Printing a file to PDF prints a virtual document into a format
that's universally readable across all devices such as
computers, tablets, and smartphones.
Word document
converted
(printed) to a
PDF
Word document PDF
This is because the PDF format is so common, that just
about every new device on the market will be able to
read a PDF file without adding any additional software.
But older devices may need additional software installed
in order to read a PDF document. The most common
PDF reader software is Adobe Acrobat Reader, which is
available free to download.
30
Storage Devices
A computer has basically two
types of memory: primary
memory and secondary
memory. Now primary
memory is temporary, which
we'll talk about later, but
secondary memory is
permanent, and this deals
with the hard disk drive. The
hard disk drive is a sealed Hard drive
case that contains magnetic
disks. These disks is where the actual data is stored on.
These disks rotate at high speeds, and as they do, the
actuator arm will either write data to the disks or read data
from the disks, depending upon what the user wants to
do. These magnetic disks can rotate at speeds of either
5,400, 7,200, or 10,000 RPM. The typical hard drive
that's used today in a desktop operates at 7,200 RPM. A
cheaper desktop hard drive operates at the 5,400 RPM
range, which is also the speed of a typical laptop hard
drive. Higher-end hard drives would operate at the
10,000 RPM range. However, these higher-end hard
drives are not commonly used anymore, because of the
advanced speeds of solid state drives. And hard drives
are considered non-volatile because they can retain and
store data when not connected to a power source.
31
Hard drives today use the
Serial ATA interface. Now,
this is a newer standard that
is faster than the old parallel
ATA interface. Instead of
data traveling in a parallel
path, the data travels and a
serial path. Which means
that data travels one bit at a
time. SATA drives have
transfer speeds averaging 6
Gbit/s, which is considerably
faster than the old parallel
ATA. Other advantages of
SATA drives are that they are
hot-swappable, and the
cables are a lot smaller,
SATA cable
which makes cable
management a lot easier.
Another type of storage
device is an SSD or solid
state drive. These drives
have no moving parts. These
drives use flash memory
chips to store data, and since
it has no moving parts, the
data transfer is very fast.
SSD drive
32
There are also drives out there that combine the use of
magnetic disks and flash memory. These are called
hybrid drives. Hybrid drives take advantage of the
large capacity and the low cost of magnetic disks, with
the speed of an SSD. In a hybrid drive, the magnetic
disks will be used to store data, while the flash memory
would be used for the caching of the data. Hybrid drives
are primarily used where cost is an issue, because SSD
drives are considerably more expensive than magnetic
hard drives.
Hybrid drives use both magnetic disks
and flash memory.
Removable storage is both
convenient and portable
because these types of
storage are not stored
internally in a computer,
they are attached from the
outside. So for example a
tape drive.
33
A tape drive is an inexpensive way to backup data from
your hard drive. It attaches to a computer, usually with a
USB cable, and then the data is backed up sequentially
to tape. Which basically means that if you ever have to
restore the data, you have to restore the data in the
same order as you backed it up.
CD-ROM drives have become a standard component in
computers today (but not for long). It's a device that
reads data from a CD-ROM, which is a disc that stores
permanent data. CD-ROM stands for compact disc
read-only memory, which means that the data can only
be read and cannot be changed or written to.
CD-RW stands for
compact disc re-writable.
A CD-RW drive can
change or write data to a
CD. It has a moving laser
assembly that writes or
burns the data to a CD.
Now, there are two
different kinds of CDs that
A laser from a CD-RW drive,
can be written to: a CD-R, writing data to a CD.
which stands for a CD
recordable, or a CD-RW,
34
which stands for a CD re-writable. A CD-R can only
be written once to, but a CD-RW allows data to be
rewritten multiple times. And CD-ROMs hold
approximately 700 megabytes of data.
DVD-ROM drive is a
device that reads DVD
discs. The DVD drive
has largely replaced
ordinary CD-ROM drives
because of the larger
storage capacity of DVD
discs. A DVD can store
approximately 4.7 GB of
data. And all DVD
drives today can read
both DVDs and CD-
ROMs.
Just like a CD-RW drive,
there is also a DVD-RW
drive. A DVD-RW drive
can change or write data
onto a DVD. It can write
data onto DVD-R discs
and rewrite data onto
DVD-RW discs.
Some DVD burners have the capability of burning dual-
layer DVDs. These are called DVD-RW DL drives. Dual-
layer DVDs have two recordable layers. So they can
35
store twice the amount of data than a regular DVD. Dual-
layer DVDs can hold approximately 8.5 gigs of data.
A dual layer DVD can hold
twice the amount of data as a
standard DVD. Approx. 8.5
GB
Blu-ray is the latest
optical drive to date that
was released in 2006.
Blu-ray will eventually
replace the DVD format
because of its high
capacity. Blu-ray uses a
shorter wavelength laser
Blu-ray drive
compared to DVD, which
allows a Blu-ray disk to
store far more data than
a DVD. A standard Blu-
ray disc can hold 25 GB
of data, which is 5 times
more than a DVD.
Blu-ray disc
Now just like CD and DVD recordable drives, Blu-ray also
has a recordable drive, and this is called a BD-R or Blue
Ray disc recordable drive.
36
A BD-R drive is where you can burn data to a Blu-ray
disc, one time. Or you can also erase data or overwrite
the data on a Blu-ray disc using a BD-RE or Blu-ray
recordable erasable drive. So as stated before
standard single-sided Blu-ray discs hold 25 gigabytes of
data, or there's also Blu-ray double sided discs which
hold 50 gigabytes of data.
An external hard drive is a
hard drive that's enclosed in a
case. It's a portable hard drive
that can be externally attached
to any computer typically using
a USB cable. External hard
drives are primarily used to
backup data from a computer's
internal hard drive, to prevent External hard drive
data loss.
Another type of removable
storage is what's known as a
solid state disk. Now, these
have no moving parts. This type
of memory uses memory chips
to store data. These include
USB flash drives. A USB flash
drive is a miniature storage
USB flash drive - also device with a USB interface.
known as a thumb drive. These drives can store
anywhere from 250 MB - 128
GB, and their size is small
37
enough to fit on a keychain. They are a fast and
convenient way to store data on the go.
Secure digital or SD cards are a
popular type of flash memory. These
are primarily used in digital cameras
for storing photographs and videos.
Then, these photographs and videos
can then be easily transferred to a
computer using an SD card reader
interface. SD cards come in various
capacities, anywhere from 2 GB up to
512 GB.
Other types of SD cards include the mini SD and the
micro SD, and you can see the comparison of the
different sizes below. While the standard SD card is
used for storage in digital cameras, the micro SD card
is what’s commonly used in most smartphones for
adding extra storage.
SD Mini SD Micro SD
Another type of flash drive that is commonly used in a
lot of DSLR cameras is compact flash. Compact flash
cards provide quick and easy storage for pictures and
38
videos in DSLR cameras. And then, they can be easily
transferred to a computer using a card reader.
Compact flash card
Commonly used in
DSLR cameras.
A type of non-standard SD
card would be the older XD
picture card, where XD stands
for extreme digital. This was
a type that was proprietary in
Olympus and Fujifilm xD picture card
cameras.
The kind of memory that you
would typically find inside
smartphones and tablets is
called eMMC. eMMC stands
for embedded multi-
media controller. eMMC
consists of putting flash
memory and a flash memory
controller into one package.
So this is the tablet’s or
smartphone’s internal or
embedded memory, and not
external storage like an SD
card.
39
Power Supply
The power supply is a device
that supplies power to the
computer. It's a square metal
box with a bunch of wires
emerging from one end that
fits inside the computer case.
The power supply is usually
located at the very top or the Power supply
bottom of a standard tower
case. The power supply converts 110 volt AC current
into the specific voltages that the computer needs.
The most common form factor that a power supply
comes in, is ATX.
A power supply is equipped
with different types of
connectors. One type is
called the P1 connector.
This is the main power
connector that connects
P1 connector will
directly into the motherboard have 20 or 24 pins.
and provides it with power.
The P1 connector has either
20 or 24 pins.
Another type of connector is called the P4. This is a 4
pin connector that also connects into the motherboard.
40
The P4's purpose is to supply
power to the CPU. This connector
is used with modern motherboards.
P4 connector
Another type is called molex. The
molex connector is a 4 pin
connector that connects disk
drives, such as hard drives, and
CD and DVD-ROM drives. Molex
There is also a SATA
connector. This is a 15 pin
connector, that is used to
connect disk and optical
SATA connector drives that have a serial ATA
power connection.
Another connector is called the 4
pin BERG connector or mini
connector. This is a small
connector that is used to supply
power to the floppy drive. 4 pin BERG
Finally, there's the 6 pin or 8
pin connector, and this is
used to supply power to
certain PCI-E video cards.
6 pin connector
(also comes in 8 pin)
41
Motherboard
The motherboard is the main component of a
computer. It's basically a large circuit board where all
the computer components connect to, such as the CPU
socket. The CPU socket is where the CPU or central
processing unit is placed. There's also the memory
slots, and this is where the primary memory modules,
known as RAM, are inserted. There is also the bus
slots. The bus lots are used to install various
components to add more capabilities to a computer,
such as a video card, sound card, network card, and so
on.
CPU
socket RAM
(memory)
slots
Bus
slots
Motherboard
42
Motherboards come in different shapes and sizes,
known as a form factor.
The most common form
factor motherboard that is
used in PCs today is ATX.
ATX stands for advanced
technology extended. It
was created in 1995 and is
now the de facto standard
form factor for PCs today.
A full-size ATX motherboard
is 12 x 9.6 inches.
Prior to the development of
ATX, was the AT form
factor. AT stands for
advanced technology.
This was used in the 1980s
that was developed by IBM.
AT motherboards are 12 x
13.8 inches in size, and
they're no longer in
development since the
succession of ATX.
Another version of the ATX
motherboard is the Micro
ATX. The micro ATX
motherboards are smaller
than ATX boards, as its
name suggests. Micro ATX
43
boards are 9.6 by 9.6 inches. It's a square design,
compared to the standard rectangular design of the ATX.
They're cheaper than ATX boards and were designed to
fit in smaller computer cases. They also have fewer
features and consume less power than a standard ATX
board.
The BTX form factor was
designed by Intel to make
further improvements from
the ATX form factor; such
as an improved board
design, which creates a
more inline air flow, which
improves cooling.
For example notice how the memory and bus lots are
horizontal, flowing with the direction of airflow, instead of
inhibiting it, compared to the ATX form factor. Another
improvement is the structure design, which is flexible
enough to work on both smaller cases and larger tower
cases.
Another form factor is the
NLX board with riser
NLX. NLX was created by card installed
Intel, and it was designed
for low-end, low profile
computers. Instead of
expansion cards that plug
perpendicular into the
motherboard, the NLX
board use a riser card
44
for expansion cards, so they can plug in parallel with the
motherboard. You would typically find NLX boards in
slimline computer cases.
Even smaller than Micro ATX
and BTX motherboards, there
is the ITX form factor. The
ITX form factor came out in
2001, starting with the Mini-
ITX. This was designed for
the ever-increasing demand
for smaller, space saving
Mini ITX
computers.
The ITX standard consumes less power, and because it
uses less power, they are often cooled only by using heat
sinks and not with fans. ITX was developed by VIA
Technologies, and there are currently four sizes that are
in the ITX form factor.
There's the Mini-ITX (above).
There is also the Nano-ITX
which came out in 2005, and
this was designed to be used in
devices such as digital video
Nano-ITX recorders, media centers, and
cars. Then there's also the
Pico-ITX which came out in
2007. And in 2009, VIA
Technologies introduced the
Pico-ITX
45
smallest x86 CPU module
6 cm
specification in the industry,
with the release of the
Motherboard
mobile-ITX. The mobile-ITX
6 cm measures 6 cm x 6 cm and it
was designed to provide
developers with a
Mobile-ITX standardized and ultra-
compact specification for
building new computer based
products.
I/O INTERFACES
Motherboards come built with several input-output
interfaces these interfaces are largely located on the
rear input-output panel of the motherboard.
Motherboard I/O panel
For example, the PS/2 connector. The PS/2 connector
is a 6-pin, mini-DIN connector. A motherboard would
typically have one or two of these and are usually
located towards the top of the motherboard.
46
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