null  null
2016 SENIOR COMPUTER CLASS
2016 SENIOR COMPUTER CLASS – JGAPL
Table of Contents
INTERNET TERMINOLOGY
2
HARDWARE TERMINOLOGY
10
Bits and Bytes
69
Page | 1
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
INTERNET TERMINOLOGY
INTERNET = The Internet is a global wide area network that connects computer systems across the
world. It includes several high-bandwidth data lines that comprise the Internet "backbone." These lines
are connected to major Internet hubs that distribute data to other locations, such as web servers and
ISPs.
In order to connect to the Internet, you must have access to an Internet service provider (ISP), which
acts the middleman between you and the Internet. Most ISPs offer broadband Internet access via a
cable, DSL, or fiber connection. When you connect to the Internet using a public Wi-Fi signal, the Wi-Fi
router is still connected to an ISP that provides Internet access. Even cellular data towers must connect
to an Internet service provider to provide connected devices with access to the Internet.
The Internet provides different online services. Some examples include:





Web – a collection of billions of webpages that you can view with a web browser
Email – the most common method of sending and receiving messages online
Social media – websites and apps that allow people to share comments, photos, and videos
Online gaming – games that allow people to play with and against each other over the Internet
Software updates – operating system and application updates can typically downloaded from
the Internet
In the early days of the Internet, most people connected to the Internet using a home computer and a
dial-up modem. DSL and cable modems eventually provided users with "always-on" connections. Now
mobile devices, such as tablets and smartphones, make it possible for people to be connected to the
Internet at all times. The Internet of Things has turned common appliances and home systems into
"smart" devices that can be monitored and controlled over the Internet. As the Internet continues to
grow and evolve, you can expect it to become an even more integral part of daily life.
URL = Stands for "Uniform Resource Locator." A URL is the address of a specific webpage or file on the
Internet. For example, the URL of the Armstrong Library website is "http://armstronglibrary.org". While
all website URLs begin with "http," several other prefixes exist. Below is a list of various URL prefixes:








http – a webpage, website directory, or other file available over HTTP
ftp – a file or directory of files available to download from an FTP server
news – a discussion located within a specific newsgroup
telnet – a Unix-based computer system that supports remote client connections
gopher – a document or menu located on a gopher server
wais - a document or search results from a WAIS database
mailto - an email address (often used to redirect browsers to an email client)
file - a file located on a local storage device (though not technically a URL because it does not
refer to an Internet-based location)
HTTP = Stands for "Hypertext Transfer Protocol." HTTP is the protocol used to transfer data over the
web. It is part of the Internet protocol suite and defines commands and services used for transmitting
webpage data.
Page | 2
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
HTTPS = Stands for "HyperText Transport Protocol Secure." HTTPS is the same thing as HTTP, but uses a
secure socket layer (SSL) for security purposes. Some examples of sites that use HTTPS include banking
and investment websites, e-commerce websites, and most websites that require you to log in.
Websites that use the standard HTTP protocol transmit and receive data in an unsecured manner. This
means it is possible for someone to eavesdrop on the data being transferred between the user and the
Web server. While this is highly unlikely, it is not a comforting thought that someone might be capturing
your credit card number or other personal information that you enter on a website. Therefore, secure
websites use the HTTPS protocol to encrypt the data being sent back and forth with SSL encryption. If
someone were to capture the data being transferred via HTTPS, it would be unrecognizable.
You can tell if a website is secure by viewing the URL in the address field of your Web browser. If the
Web address starts with https://, you know you are accessing a secure website. Most browsers will also
display a lock icon somewhere along the edge of the window to indicate the website you are currently
visiting is secure. You can click the lock icon to view the secure certificate that authenticates the
website.
So whenever you are asked to enter personal or financial information on a website, make sure that the
URL starts with "https://" and that the lock icon appears in the window. Then you can be sure that the
website is secure and any data you enter will only be recognized by your computer and the Web server.
CLIENT = In the real world, businesses have clients. In the computer world, servers have clients. The
"client-server" architecture is common in both local and wide area networks. For example, if an office
has a server that stores the company's database on it, the other computers in the office that can access
the datbase are "clients" of the server. On a larger scale, when you access your e-mail from a mail
server on the Internet, your computer acts as the client that connects to the mail server. The term
"client software" is used to refer to the software that acts as the interface between the client computer
and the server. For example, if you use Microsoft Outlook to check your e-mail, Outlook is your "e-mail
client software" that allows you to send and receive messages from the server. Isn't exciting how it all
works?
ADDRESS BAR = an address bar is a text field near the top of a Web browser window that displays the
URL of the current webpage. The URL, or web address, reflects the address of the current page and
automatically changes whenever you visit a new webpage. Therefore, you can always check the location
of the webpage you are currently viewing with the browser's address bar.
While the URL in the address bar updates automatically when you visit a new page, you can also
manually enter a web address. Therefore, if you know the URL of a website or specific page you want to
visit, you can type the URL in the address bar and press Enter to open the location in your browser.
NOTE: The URL typically begins with "http://", but most browsers will automatically add the HTTP prefix
to the beginning of the address if you don't type it in.
The appearance of the address bar varies slightly between browsers, but most browsers display a small
16x16 pixel icon directly to the left of the URL. This icon is called a "favicon" and provides a visual
identifier for the current website. Some browsers also display an RSS feed button on the right side of the
address bar when you visit a website that offers RSS feeds. In the Safari web browser, the address bar
also doubles as a progress bar when pages are loading and includes a refresh button on the right side.
Page | 3
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Firefox includes a favorite’s icon on the right side of the address bar that lets you add or edit a
bookmark for the current page.
The address bar is sometimes also called an "address field." However, it should not be confused with a
browser toolbar, such as the Google or Yahoo! Toolbar. These toolbars typically appear underneath the
address bar and may include a search field and several icons.
BOOKMARK = A bookmark is a saved shortcut that directs your browser to a specific webpage. It stores
the title, URL, and favicon of the corresponding page. Saving bookmarks allows you to easily access your
favorite locations on the Web.
BROADBAND = refers to high-speed data transmission in which a single cable can carry a large amount
of data at once. The most common types of Internet broadband connections are cable modems (which
use the same connection as cable TV) and DSL modems (which use your existing phone line). Because of
its multiple channel capacity, broadband has started to replace baseband, the single-channel technology
originally used in most computer networks. So now when you see companies like AT&T and CableOne
pushing those fancy "broadband" ads in your face, you'll at least know what they are talking about.
CAPTCHA = A captcha is program used to verify that a human, rather than a computer, is entering data.
Captchas are commonly seen at the end of online forms and ask the user to enter text from a distorted
image. The text in the image may be wavy, have lines through it, or may be highly irregular, making it
nearly impossible for an automated program to recognize it. (Of course, some captchas are so distorted
that they can be difficult for humans to recognize as well.) Fortunately, most captchas allow the user to
regenerate the image if the text is too difficult to read. Some even include an auditory pronunciation
feature.
CLOUD = The term "cloud" comes from early network diagrams, in which the image of a cloud was used
to indicate a large network, such as a WAN. The cloud eventually became associated with the entire
Internet, and the two terms are now used synonymously. The cloud may also be used to describe
specific online services, which are collectively labeled "cloud computing."
Examples of popular cloud-based services include web applications, SaaS, online backup, and other
types of online storage. Traditional Internet services like web hosting, email, and online gaming may also
be considered part of the cloud since they are hosted on Internet servers, rather than users' local
computers. Even social networking websites such as Facebook and LinkedIn are technically cloud-based
services, since they store your information online.
While "the cloud" is simply a buzzword for most consumers, it plays an important role for businesses. By
moving software services to the cloud, companies can share data more efficiently and centralize their
network security. Additionally, cloud-based virtualization can help businesses reduce the number of
computer systems and software licenses they need to buy. The end result and a more efficient and less
costly way of running a business.
NETWORK = When you have two or more computers connected to each other, you have a network. The
purpose of a network is to enable the sharing of files and information between multiple systems. The
Internet could be described as a global network of networks. Computer networks can be connected
through cables, such as Ethernet cables or phone lines, or wirelessly, using wireless networking cards
that send and receive data through the air.
Page | 4
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
SOCIAL NETWORKING = When the Web became popular in the mid-1990s, it enabled people to share
information in ways that were never possible before. But as limitless as the possibilities seemed, there
was a personal aspect that was lacking. While users could create home pages and post their own
content on the Web, these individual sites lacked a sense of community. In the early 2000s, the Web
became much more personal as social networking websites were introduced and embraced by the
masses.
Social networking websites allow users to be part of a virtual community. The two most popular sites
are currently Facebook and MySpace. These websites provide users with simple tools to create a custom
profile with text and pictures. A typical profile includes basic information about the user, at least one
photo, and possibly a blog or other comments published by the user. Advanced profiles may include
videos, photo albums or online applications (in Facebook). After creating a profile, users can add friends,
send messages to other users, and leave comments directly on friends' profiles. These features provide
the building blocks for creating online communities.
Thanks to social networking websites, users can share their lives with other people without needing to
develop and publish their own home pages. These websites also provide an important linking element
between users that allows friends to communicate directly with each other. Because people often have
friends from different places and different times in their lives, social networking sites provide an
opportunity to keep in touch with old friends and to meet new people as well. Of course, this means
that people you don't know may also be able to view your profile page. Therefore, if you join a social
networking website, it is a good idea to review the privacy settings for your account. And more
importantly, remember to always use discretion in what you publish on your profile.
SOFTWARE = Computer software is a general term that describes computer programs. Related terms
such as software programs, applications, scripts, and instruction sets all fall under the category of
computer software. Therefore, installing new programs or applications on your computer is synonymous
with installing new software on your computer.
Software can be difficult to describe because it is "virtual," or not physical like computer hardware.
Instead, software consists of lines of code written by computer programmers that have been compiled
into a computer program. Software programs are stored as binary data that is copied to a computer's
hard drive, when it is installed. Since software is virtual and does not take up any physical space, it is
much easier (and often cheaper) to upgrade than computer hardware.
While at its most basic level, software consists of binary data, CD-ROMs, DVDs, and other types of media
that are used to distribute software can also be called software. Therefore, when you buy a software
program, it often comes on a disc, which is a physical means of storing the software.
APPS = App is short for "application," which is the same thing as a software program. While an app may
refer to a program for any hardware platform, it is most often used to describe programs for mobile
devices, such as smartphones and tablets.
The term "app" was popularized by Apple when the company created the "App Store" in 2008, a year
after the first iPhone was released. As the iPhone and App Store grew in popularity, the term "app"
became the standard way to refer to mobile applications. Programs for Android and Windows Phone are
now called "apps" as well.
Page | 5
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Unlike applications for traditional PCs (often called "desktop applications"), mobile apps can only be
obtained by downloading them from an online app store. Most devices automatically install apps when
downloaded, which creates a seamless installation process for the user. Some apps are free, while
others must be purchased. However, mobile apps are typically much cheaper than PC applications, and
many are available for only 99 cents. In fact, most paid apps are less than $10.
Part of the reason mobile apps are cheaper than desktop applications is because they are often less
advanced and take less resources to develop. Apps are limited to the capabilities of the mobile
operating system (such as iOS or Android) and therefore may not offer as much functionality as a
desktop program. For example, a word processor for Android will most likely have significantly less
features than a word processing application for Windows. Most apps are designed to be small, fast, and
easy-to-use. Unlike desktop applications, apps are intended to be used on-the-go and are developed to
advantage of a small touchscreen interface.
NOTE: Apple released the Mac App Store in January, 2011, which offers downloadable applications for
Mac OS X. In this case, the term "app" refers to desktop applications. As of 2015, Microsoft now has the
Windows App Store which with the release of Windows 10 downloadable applications for its new
flagship OS.
HTML = Stands for "Hypertext Markup Language." HTML is the language used to create webpages.
"Hypertext" refers to the hyperlinks that an HTML page may contain. "Markup language" refers to the
way tags are used to define the page layout and elements within the page.
The web has gone through many changes over the past few decades, but HTML has always been the
fundamental language used to develop webpages. Interestingly, while websites have become more
advanced and interactive, HTML has actually gotten simpler. If you compare the source of an HTML5
page with a similar page written in HTML 4.01 or XHTML 1.0, the HTML5 page would probably contain
less code. This is because modern HTML relies on cascading style sheets or JavaScript to format nearly
all the elements within a page.
NOTE: Many dynamic websites generate webpages on-the-fly, using a server-side scripting language like
PHP or ASP. However, even dynamic pages must be formatted using HTML. Therefore, scripting
languages often generate the HTML that is sent to your web browser.
HYPERLINK = A hyperlink is a word, phrase, or image that you can click on to jump to a new document
or a new section within the current document. Hyperlinks are found in nearly all Web pages, allowing
users to click their way from page to page. Text hyperlinks are often blue and underlined, but don't have
to be. When you move the cursor over a hyperlink, whether it is text or an image, the arrow should
change to a small hand pointing at the link. When you click it, a new page or place in the current page
will open.
Hyperlinks, often referred to as just "links," are common in Web pages, but can be found in other
hypertext documents. These include certain encyclopedias, glossaries, dictionaries, and other references
that use hyperlinks. The links act the same way as they do on the Web, allowing the user to jump from
page to page. Basically, hyperlinks allow people to browse information at hyperspeed.
Page | 6
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
EMAIL = Email, short for "electronic mail," is one of the most widely used features of the Internet, along
with the web. It allows you to send and receive messages to and from anyone with an email address,
anywhere in the world.
Email uses multiple protocols within the TCP/IP suite. For example, SMTP is used to send messages,
while the POP or IMAP protocols are used to retrieve messages from a mail server. When you configure
an email account, you must define your email address, password, and the mail servers used to send and
receive messages. Fortunately, most webmail services configure your account automatically, so you only
need to enter your email address and password. However, if you use an email client like Microsoft
Outlook or Apple Mail, you may need to manually configure each account. Besides the email address
and password, you may also have to enter the incoming and outgoing mail servers and enter the correct
port numbers for each one.
The original email standard only supported plain text messages. Eventually, email evolved to support
rich text with custom formatting. Today, email supports HTML, which allows emails to be formatted the
same way as websites. HTML email messages can include images, links, and CSS layouts. You can also
send files or "email attachments" along with messages. Most mail servers allow you to send multiple
attachments with each message, but they limit the total size. In the early days of email, attachments
were typically limited to one megabyte, but now many mail servers support email attachments that are
20 megabytes in size or more.
Email Netiquette - When composing an email message, it is important to use good netiquette. For
example, you should always include a subject that summarizes the topic of the email. It is also helpful to
begin each message with the recipient's name and end the message with your name or "signature." A
typical signature includes your name, email address, and/or website URL. A professional signature may
include your company name and title as well. Most email programs allow you to save multiple
signatures, which you can insert at the bottom of an email.
If you want to send an email to multiple recipients, you can simply add each email address to the "To"
field. However, if the email is primarily intended for one person, you should place the additional
addresses in the "CC" (carbon copy) field. If you are sending an email to multiple people that don't know
each other, it is best to use the "Bcc" (blind carbon copy) field. This hides the email addresses of each
recipient, which helps prevent spam.
NOTE: Email was originally written "e-mail," but is now more commonly written as "email" without the
dash.
POP3 = Stands for "Post Office Protocol." POP3, sometimes referred to as just "POP," is a simple,
standardized method of delivering e-mail messages. A POP3 mail server receives e-mails and filters them
into the appropriate user folders. When a user connects to the mail server to retrieve his mail, the
messages are downloaded from mail server to the user's hard disk.
When you configure your e-mail client, such as Outlook (Windows) or Mail (Mac OS X), you will need to
enter the type of mail server your e-mail account uses. This will typically be either a POP3 or IMAP
server. IMAP mail servers are a bit more complex than POP3 servers and allow e-mail messages to be
read and stored on the server. Many "webmail" interfaces use IMAP mail servers so that users can
manage all their mail online.
Page | 7
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Still, most mail servers use the POP3 mail protocol because it is simple and well-supported. You may
have to check with your ISP or whoever manages your mail account to find out what settings to use for
configuring your mail program. If your e-mail account is on a POP3 mail server, you will need to enter
the correct POP3 server address in your e-mail program settings. Typically, this is something like
"mail.servername.com" or "pop.servername.com." Of course, to successfully retrieve your mail, you will
have to enter a valid username and password too.
SMTP = Stands for "Simple Mail Transfer Protocol." This is the protocol used for sending e-mail over the
Internet. Your e-mail client (such as Outlook, Eudora, or Mac OS X Mail) uses SMTP to send a message to
the mail server, and the mail server uses SMTP to relay that message to the correct receiving mail
server. Basically, SMTP is a set of commands that authenticate and direct the transfer of electronic mail.
When configuring the settings for your e-mail program, you usually need to set the SMTP server to your
local Internet Service Provider's SMTP settings (i.e. "smtp.yourisp.com"). However, the incoming mail
server (IMAP or POP3) should be set to your mail account's server (i.e. hotmail.com), which may be
different than the SMTP server.
IMAP = Stands for "Internet Message Access Protocol" and is pronounced "eye-map." It is a method of
accessing e-mail messages on a server without having to download them to your local hard drive. This is
the main difference between IMAP and another popular e-mail protocol called "POP3." POP3 requires
users to download messages to their hard drive before reading them. The advantage of using an IMAP
mail server is that users can check their mail from multiple computers and always see the same
messages. This is because the messages stay on the server until the user chooses to download them to
his or her local drive. Most webmail systems are IMAP based, which allows people to access to both
their sent and received messages no matter what computer they use to check their mail.
Most e-mail client programs such as Microsoft Outlook and Mac OS X Mail allow you to specify what
kind of protocol your mail server uses. If you use your ISP's mail service, you should check with them to
find out if their mail server uses IMAP or POP3 mail. If you enter the wrong protocol setting, your e-mail
program will not be able to send or receive mail.
SEARCH ENGINE = Google, Bing, Yahoo! Search, Ask, Aol Search, Wow, WebCrawler, MyWebSearch,
InfoSpace, Info.com, DuckDuck.go, and Dogpile are all search engines. They index millions of sites on
the Web, so that Web surfers like you and me can easily find Web sites with the information we want.
By creating indexes, or large databases of Web sites (based on titles, keywords, and the text in the
pages), search engines can locate relevant Web sites when users enter search terms or phrases. When
you are looking for something using a search engine, it is a good idea to use words like AND, OR, and
NOT to specify your search. Using these boolean operators, you can usually get a list of more relevant
sites.
SPAM = Originating from the name of Hormel's canned meat, "spam" now also refers to junk e-mail or
irrelevant postings to a newsgroup or bulletin board. The unsolicited e-mail messages you receive about
refinancing your home, reversing aging, and losing those extra pounds are all considered to be spam.
Spamming other people is definitely not cool and is one of the most notorious violations of Internet
etiquette (or "netiquette"). So if you ever get the urge to let thousands of people know about that hot
new guaranteed way to make money on the Internet, please reconsider.
Page | 8
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
STREAMING = Data streaming, commonly seen in the forms of audio and video streaming, is when a
multimedia file can be played back without being completely downloaded first. Most files, like
shareware and software updates that you download off the Internet, are not streaming data. However,
certain audio and video files like Real Audio and QuickTime documents can be streaming files, meaning
you can watch a video or listen to a sound file while it's being downloaded to your computer. With a fast
Internet connection, you can actually stream live audio or video to your computer.
PHISHING (Fishing) = Phishing is a con game that scammers use to collect personal information from
unsuspecting users. The false e-mails often look surprisingly legitimate, and even the Web pages where
you are asked to enter your information may look real. However, the URL in the address field can tell
you if the page you have been directed to is valid or not. They send out e-mails that appear to come
from legitimate websites such as eBay, PayPal, or other banking institutions. The e-mails state that your
information needs to be updated or validated and ask that you enter your username and password,
after clicking a link included in the e-mail. Some e-mails will ask that you enter even more information,
such as your full name, address, phone number, social security number, and credit card number.
However, even if you visit the false website and just enter your username and password, the phisher
may be able to gain access to more information by just logging in to you account.
If you receive an e-mail that asks that you update your information and you think it might be valid, go to
the website by typing the URL in your browser's address field instead of clicking the link in the e-mail.
For example, go to "https://www.paypal.com" instead of clicking the link in an e-mail that appears to
come from PayPal. If you are prompted to update your information after you have manually typed in the
Web address and logged in, then the e-mail was probably legitimate. However, if you are not asked to
update any information, then the e-mail was most likely a spoof sent by a phisher.
Most legitimate e-mails will address you by your full name at the beginning of the message. If there is
any doubt that the e-mail is legitimate, be smart and don't enter your information. Even if you believe
the message is valid, following the guidelines above will prevent you from giving phishers your personal
information.
Page | 9
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
HARDWARE TERMINOLOGY
3D Printer = A 3D printer is a computer-aided manufacturing (CAM) device that creates threedimensional objects. Like a traditional printer, a 3D printer receives digital data from a computer as
input. However, instead of printing the output on paper, a 3D printer builds a three-dimensional model
out of a custom material.
3D printers use a process called additive manufacturing to form (or "print") physical objects layer by
layer until the model is complete. This is different than subtractive manufacturing, in which a machine
reshapes or removes material from an existing mold. Since 3D printers create models from scratch, they
are more efficient and produce less waste than subtractive manufacturing devices.
The process of printing a 3D model varies depending on the material used to create the object. For
example, when building a plastic model, a 3D printer may heat and fuse the layers of plastic together
using a process called fused deposition modeling (FDM). When creating a metallic object, a 3D printer
may use a process called direct metal laser sintering (DMLS). This method forms thins layers of metal
from metallic powder using a high powered laser.
While 3D printing has been possible since the 1980s, it has been primarily used for large scale industrial
purposes. However, in recent years, 3D printers have become much cheaper and are now available to
the consumer market. As the technology becomes more widespread, 3D printers may become a viable
means for people to create their own home products and replacement parts.
Access Point = An access point is a device, such as a wireless router, that allows wireless devices to
connect to a network. Most access points have built-in routers, while others must be connected to a
router in order to provide network access. In either case, access points are typically hardwired to other
devices, such as network switches or broadband modems.
Access points can be found in many places, including houses, businesses, and public locations. In most
houses, the access point is a wireless router, which is connected to a DSL or cable modem. However,
some modems may include wireless capabilities, making the modem itself the access point. Large
businesses often provide several access points, which allows employees to wirelessly connect to a
central network from a wide range of locations. Public access points can be found in stores, coffee
shops, restaurants, libraries, and other locations. Some cities provide public access points in the form of
wireless transmitters that are connected to streetlights, signs, and other public objects.
While access points typically provide wireless access to the Internet, some are intended only to provide
access to a closed network. For example, a business may provide secure access points to its employees
so they can wirelessly access files from a network server. Also, most access points provide Wi-Fi access,
but it is possible for an access point to refer to a Bluetooth device or other type of wireless connection.
However, the purpose of most access points is to provide Internet access to connected users.
The term "access point" is often used synonymously with base station, though base stations are
technically only Wi-Fi devices. It may also be abbreviated AP or WAP (for wireless access point).
However, WAP is not as commonly used as AP since WAP is the standard acronym for Wireless Access
Protocol.
Page | 10
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Adapter = An adapter is a device that allows a specific type of hardware to work with another device
that would otherwise be incompatible. Examples of adapters include electrical adapters, video adapters,
audio adapters, and network adapters.
An electrical adapter, for instance, may convert the incoming voltage from 120V to 12V, which is
suitable for a radio or other small electronic device. Without regulating voltage through an adapter, the
incoming electrical surge could literally fry the internal components of the device. Most consumer
electronics have adapters attached to the plug at the end of the electrical cord. Whenever you see an
plug surrounded by a large box, it is most likely an electrical adapter. You can typically find the input and
output voltage printed directly on the adapter. A device that does not have an adapter on the end of its
electrical cable typically has a built-in voltage adapter. For example, desktop computers typically have
the adapter built into the internal power supply.
Video adapters and audio adapters adapt one type of interface to another type of connector. For
example, a DVI to VGA adapter allows you to connect the DVI output of a laptop to the VGA input of a
projector. Most professional audio devices use 1/4" audio jacks, while most computers have 1/8"
"minijacks" for audio input and output. Therefore, 1/4" to 1/8" audio adapters are often used to import
audio into computers. Likewise, an 1/8" to 1/4" adapter can used to output audio from a computer to a
professional audio system. Since a large number of audio and video interfaces exist, there are hundreds
of audio and video adapters available.
Network cards, or NICs, are also called network adapters. These include Ethernet cards, internal Wi-Fi
chips, and external wireless transmitters. While these devices don't convert connections like audio or
video adapters, they enable computers to connect to network. Since the network card makes it possible
to connect to an otherwise incompatible network, the card serves as an adapter. Similarly, video cards
are sometimes called video adapters because they convert a video signal to an image that can be
displayed on a monitor.
ADSL = Stands for "Asymmetric Digital Subscriber Line." ADSL is a type of DSL, which is a method of
transferring data over copper telephone lines. While symmetrical DSL (SDSL) uploads and downloads
data at the same speed, ADSL has different maximum data transfer rates for uploading and downloading
data.
For example, an ADSL connection may allow download rates of 1.5Mbps, while upload speeds may only
reach 256Kbps. Since most users download much more data than they upload, this difference usually
does not make a noticeable impact on Internet access speeds. However, for Web servers or other
computers that send a lot of data upstream, ADSL would be an inefficient choice.
AGP (Dead Tech) = Stands for "Accelerated Graphics Port." AGP is a type of expansion slot designed
specifically for graphics cards. It was developed in 1996 as an alternative to the PCI standard. Since the
AGP interface provides a dedicated bus for graphics data, AGP cards are able to render graphics faster
than comparable PCI graphics cards.
Like PCI slots, AGP slots are built into a computer's motherboard. They have a similar form factor to PCI
slots, but can only be used for graphics cards. Additionally, several AGP specifications exist, including
AGP 1.0, 2.0, and 3.0, which each use a different voltage. Therefore, AGP cards must be compatible with
the specification of the AGP slot they are installed in.
Page | 11
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Since AGP cards require an expansion slot, they can only be used in desktop computers. While AGP was
popular for about a decade, the technology has been superseded by PCI Express, which was introduced
in 2004. For a few years, many desktop computers included both AGP and PCI Express slots, but
eventually AGP slots were removed completely. Therefore, most desktop computers manufactured after
2006 do not include an AGP slot.
Architecture = The word "architecture" typically refers to building design and construction. In the
computing world, "architecture" also refers to design, but instead of buildings, it describes the design of
computer systems. Computer architecture is a broad topic that includes everything from the
relationship between multiple computers (such as a "client-server" model) to specific components inside
a computer.
The most important type of hardware design is a computer's processor architecture. The design of the
processor determines what software can run on the computer and what other hardware components
are supported. For example, Intel's x86 processor architecture is the standard architecture used by most
PCs. By using this design, computer manufacturers can create machines that include different hardware
components, but run the same software. Several years ago, Apple switched from the PowerPC
architecture to the x86 architecture to make the Macintosh platform more compatible with Windows
PCs.
The architecture of the motherboard is also important in determining what hardware and software a
computer system will support. The motherboard design is often called the "chipset" and defines what
processor models and other components will work with the motherboard. For example, while two
motherboards may both support x86 processors, one may only work with newer processor models. A
newer chipset may also require faster RAM and a different type of video card than an older model.
NOTE: Most modern computers have 64-bit processors and chipsets, while earlier computers used a 32bit architecture. A computer with a 64-bit chipset supports far more memory than one with a 32-bit
chipset and can run software designed specifically for 64-bit processors.
ATA = Stands for "Advanced Technology Attachment." It is a type of disk drive that integrates the drive
controller directly on the drive itself. Computers can use ATA hard drives without a specific controller to
support the drive. The motherboard must still support an ATA connection, but a separate card (such as a
SCSI card for a SCSI hard drive) is not needed. Some different types of ATA standards include ATA-1,
ATA-2 (a.k.a. Fast ATA), ATA-3, Ultra ATA (33 MBps maximum transfer rate), ATA/66 (66 MBps), and
ATA/100 (100 MBps).
The term IDE, or "Integrated Drive Electronics," is also used to refer to ATA drives. Sometimes (to add
extra confusion to people buying hard drives), ATA drives are labeled as "IDE/ATA." Technically, ATA
uses IDE technology, but the important thing to know is that they refer to the same thing.
ATX = Stands for "Advanced Technology eXtended." ATX is a motherboard specification that defines the
board's physical dimensions, connector placement, I/O ports, and supported power supplies. It was
introduced by Intel in 1995 and was designed to replace the previous "AT" standard for desktop PCs.
Since then, many variations of the original ATX standard have been developed and some are still used in
today's desktop computers.
Page | 12
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
There are several distinct differences between ATX and the AT form factor it superseded. For example,
ATX has an I/O panel that is twice the height of the AT panel and allows for flexible interface layouts. It
also has different processor, memory, and drive I/O locations. These changes provide the following
benefits:







Fewer cables
Improved reliability
Support for modern I/O standards like USB
Support for integrated graphics
Larger expansion slots
Easier processor and memory upgrades
Reduced cost
A full size ATX motherboard is 12 inches wide and 9.6 inches deep (305 x 244 mm). There are also
several variants of ATX, which have slightly different form factors. This include the following:





FlexATX – 9 × 7.5 in (229 × 191 mm)
MicroATX – 9.6 × 9.6 in (244 × 244 mm)
Mini ATX – 11.2 × 8.2 in (284 × 208 mm)
Extended ATX (EATX) – 12 × 13 in (305 × 330 mm)
Workstation ATX (WTX) – 14 × 16.75 in (356 × 425 mm)
The ATX specification defines the mounting hole locations, which means any standard ATX motherboard
can be attached to any standard ATX case. Smaller boards (such as FlexATX, MicroATX, and Mini ATX)
have several of the same mounting hole locations, so they can be placed in a standard ATX case as well.
The universal compatibility of ATX boards and components make them a popular choice for hobbyists
who build their own PCs.
Bezel = The term "bezel" comes from the jewelry industry, in which case a bezel is a groove that holds a
gemstone or watch crystal in place. The term is also used to describe the rim around gauges, such as the
speedometer in a car. In the computer industry, a bezel may refer to either the edge around a monitor
or the front of a desktop computer case.
A monitor bezel, or screen bezel, is the area of a display that surrounds the screen. For example, if a
monitor has a one inch bezel, the screen is surrounded by one inch of plastic or metal. If a monitor's
bezel width is different on the sides than the top and bottom of the screen, the bezel specification will
include individual measurements for each side. As displays have evolved, bezel widths have generally
gotten smaller. For example, old CRT monitors often had bezel widths of two inches or more, while
modern LCD displays often have bezels that are less than one inch thick. Thinner bezels help maximize
the screen real estate of a laptops and make multiple desktop displays look more like a single screen
when placed side by side.
A computer bezel is the front face of a system unit or "tower." Most PC bezels include have openings for
one or more drive bays. These slots allow you to add devices such as an optical drive or an additional
internal hard drive. When extra drives are not installed, these bays are usually covered by plates that are
the same color as the bezel, but are not technically part of the bezel.
Page | 13
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Boot Disk = A boot disk is actually not a computer disk in the shape of a boot. If it was, most disk drives
would have a difficult time reading it. Instead, a boot disk is a disk that a computer can start up or
"boot" from. The most common type of boot disk is an internal hard drive, which most computers use to
start up from. The operating system installed on the hard drive is loaded during the boot process.
However, most computers allow you to boot from other disks, including external USB Flash Drives,
Firewire hard drives, CD-ROMs, DVD-ROMs, and floppy disks. In order to function as boot disks, these
disks need to have an operating system installed that is understandable by the computer. This can either
be a full-blown operating system like Windows or Mac OS X, or a small utility operating system, such as
Norton Utilities or DiskWarrior.
CD and DVD boot disks are often used to start up a computer when the operating system on the internal
hard drive won't load. This can happen when bad data blocks or other errors occur on the disk. By
running a disk repair utility from the CD or DVD, you can often fix the hard drive and restart from it,
using the full operating system.
BUS = While the wheels on the bus may go "round and round," data on a computer's bus goes up and
down. Each bus inside a computer consists of set of wires that allow data to be passed back and forth.
Most computers have several buses that transmit data to different parts of the machine. Each bus has a
certain size, measured in bits (such as 32-bit or 64-bit), that determines how much data can travel across
the bus at one time. Buses also have a certain speed, measured in megahertz, which determines how
fast the data can travel.
The computer's primary bus is called the frontside bus and connects the CPU to the rest of the
components on the motherboard. Expansion buses, such as PCI and AGP, allow data to move to and
from expansion cards, including video cards and other I/O devices. While there are several buses inside
a computer, the speed of the frontside bus is the most important, as it determines how fast data can
move in and out of the processor.
Cable Modem = A cable modem is a peripheral device used to connect to the Internet. It operates over
coax cable TV lines and provides high-speed Internet access. Since cable modems offer an always-on
connection and fast data transfer rates, they are considered broadband devices.
Dial-up modems, which were popular in the early years of the Internet, offered speeds close to 56 Kbps
over analog telephone lines. Eventually, DSL and cable modems replaced dial-up modems since they
offered much faster speeds. Early cable modems provided download and upload speeds of 1 to 3 Mbps,
20 to 60 times faster than the fastest dial-up modems. Today, standard cable Internet access speeds
range from 25 to 50 Mbps. On the high end, Comcast offers an "Xfinity Extreme" service with speeds up
to 505 Mbps.
Most cable modems include a standard RJ45 port that connects to the Ethernet port on your computer
or router. Since most homes now have several Internet-enabled devices, cable modems typically include
a built-in wireless router, eliminating the need for a second device.
NOTE: While "cable modem" includes the word "modem," it does not function as a traditional modem
(which is short for "modulator/demodulator"). Cable modems send and receive information digitally, so
there is no need to modulate an analog signal.
Page | 14
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Card Reader = generic term for an input device that reads flash memory cards. It can be a standalone
device that connects to a computer via USB or it may be integrated into a computer, printer, or
multifunction device. In fact, most multifunction printer/scanner/copiers now have built-in card readers.
Most card readers accept multiple memory card formats, including compact flash (CF), secure digital
(SD), and Sony's Memory Stick. Some card readers accept various other formats such as XD,
SmartMedia, Microdrive, and Memory Stick Pro Duo cards.
The purpose of a card reader is, not surprisingly, to read the data from a memory card. When you place
a memory card into a card reader, it will often show up on your computer as a mounted disk. You can
then view the contents of the memory card by double-clicking the card's icon. This icon typically appears
on the desktop of Macintosh computers or inside "My Computer" on Windows machines.
Since memory cards most often contain pictures from digital cameras, a photo organization program
may automatically open when you insert a memory card into you card reader. This provides an easy way
of importing your pictures into your photo album. If you don't want to import photos using the program,
you can simply close the program and the card will still be mounted on your computer.
Once you decide to remove the card, make sure you unmount or "eject" the disk before physically
removing the card. This will help prevent the data on the card from becoming corrupted.
Chip = Technically speaking, a computer chip is a piece of silicon with an electronic circuit embedded in
it. However, the word "chip" is often used as a slang term that refers to various components inside a
computer. It typically describes an integrated circuit, or IC, such as a central processor or a graphics chip,
but may also refer to other components such as a memory module.
While "chip" is a somewhat ambiguous term, it should not be confused with the term "card." For
example, a laptop might have a graphics chip embedded in the motherboard, while a desktop computer
may contain a graphics card connected to a PCIx or AGP slot. A graphics card may contain a chip, but the
chip cannot contain a card. Similarly, a CPU may contain a chip (the processor), but it may also contain
several other components. Therefore, the term "chip" can be used to refer to specific components, but
should not be used describe multiple components that are grouped together.
Chipset = A chipset is a group of integrated circuits that work together. It may refer to the design of a
single component or may describe the relationship of multiple components within a computer system.
For example, the chipset of video card describes the design of the card, while a motherboard chipset
describes its layout and the different components it supports.
Diagrams are often used to illustrate chipset designs. For example, a diagram of a video card chipset
may contain the GPU, video RAM, and the PCI bus. It may also include lines and arrows that represent
the circuitry between the components. Together, the components and circuitry make up the overall
design of the chipset, and may also be called the architecture of the video card.
A motherboard chipset diagram may include components such as the CPU, RAM, video card, and I/O
ports. A detailed diagram may also include lesser-known components, such as the northbridge,
southbridge and frontside bus. Regardless of level of detail, all motherboard chipset diagrams include
lines and arrows that visually describe the way data flows between the different components.
Page | 15
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Most internal computer components are designed for a specific chipset. Therefore, if you decide to
upgrade any internal hardware, it is important to know what type of chipset your computer uses. In
many cases, a computer's chipset is synonymous with the chipset of the motherboard. Once you find
out what chipset your motherboard uses, you can determine what components are compatible with
your machine.
Chromebook = A Chromebook is a laptop that runs Google's Chrome OS operating system. While Google
sells its own Chromebook model, the Chromebook Pixel, many other manufacturers offer Chromebooks
as well. Examples include Dell, HP, Toshiba, Samsung, ASUS, and Acer.
Chromebooks are designed to be inexpensive and highly portable. They are considered thin clients since
they have minimal internal storage. Unlike traditional laptops, Chromebooks are designed to run cloudbased applications and store data online. While the Chrome OS and some applications can run offline,
Chromebooks work best when used with an Internet connection.
The Chrome OS includes several Google apps, such as the Chrome web browser, Gmail, Google+, and
YouTube applications. It also runs the Google Drive office suite and related apps such as Google Docs,
Google Drawings, and Google Forms. Third party applications can be downloaded from the Chrome Web
Store. Some Android apps can also run on Chrome OS via Google's App Runtime for Chrome (ARC).
Since Chromebooks do not run Windows or OS X, they do not natively support many traditional
applications, such as Microsoft Office. However, you can run online versions of Word, Excel, and other
common applications from the Chrome OS or through the Chrome web browser. These applications run
on a remote server, but look and function like traditional desktop applications. Chromebooks also
support remote access software, which allows you operate Windows or OS X computers from a
Chromebook.
Clone = What do sheep, droids, and computers all have in common? They can all be cloned! Of the
three, computer clones are by far the most common.
The term "clone" arose in the mid-1980s to describe DOS or Windows-based computers made by
companies other than IBM. The machines were often referred to as "IBM clones," or "IBM compatible"
computers. They were called clones because the computers functioned exactly the same way as the
ones made by IBM. They used similar hardware and ran the same software.
PC clones are still around today. In fact there are dozens more manufacturers of Windows-based
computers now than there were in the 1980s. Companies like Dell, Gateway, HP, Compaq, and Sony all
make Windows-based computers, as well as many other manufacturers. Today, the term "PC," which
technically stands for "Personal Computer," is often used to refer to IBM clones. Macintosh clones were
made for a few years in the late 1990s, but Apple forced the end of their production by making the
Macintosh operating system only run on the Apple-branded machines.
"Clone" can also be used to refer to software that serves the same purpose as another more
mainstream software program. It can also refer to electronic devices other than computers that are
similar to other electronics.
Page | 16
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Also in large business or enterprise environments, a computer technician can “clone an Image” of the
hard disk drive of a configured desktop computer, then copy that image to multiple computers to
expedite deployment of desktop computers.
CMOS = Stands for "Complementary Metal Oxide Semiconductor." This technology is typically used in
making transistors. The "complementary" part of the term unfortunately does not mean these
semiconductors are free. Instead, it refers to how they produce either a positive or negative charge.
Because CMOS-based transistors only use one charge at a time, they run efficiently, using up very little
power. This is because the charges can stay in one state for a long period of time, allowing the transistor
to use little or no power except when needed. Because of their wonderful efficiency, processors that use
CMOS-based transistors can run at extremely high speeds without getting too hot and going up in
flames. You may also find CMOS memory in your computer, which holds the date and time and other
basic system settings. The low power consumption of CMOS allows the memory to be powered by a
simple Lithium battery for many years.
Coaxial Cable = Coaxial (or “coax”) cable is a common type of cable used for transmitting data over long
distances. It can carry either an analog or digital signal. While coax cables have many applications, they
are most commonly used to transmit cable TV and Internet signals.
Coax cables that run underground are typically thicker and more heavily insulated than the cables that
connect your cable box or cable modem to the wall outlet. However, they all transmit data via a thin
copper line in the middle of the cable. This wire is surrounded by a layer of insulation comprised of nonconductive or “dielectric” material. The dielectric layer is covered with one or more metallic shields that
provides additional protection from signal interference. Finally, a protective plastic outer layer
surrounds the entire cable.
The heavy duty design of coaxial cables is what allows them to carry data over long distances with
minimum signal degradation. In many cases, coax cables laid by cable companies several decades ago
are sufficient to provide HDTV and high-speed Internet access simultaneously. However, certain coax
cables (such as RG-59 cables) are designed for low bandwidth applications, like connecting a VCR to a
TV, and may not provide enough bandwidth to carry a full HDTV signal. Coax cables labeled as “RG-6”
are a better choice for HDTV and cable Internet service.
Component = Computers are made up of many different parts, such as a motherboard, CPU, RAM, and
hard drive. Each of these parts are made up of smaller parts, called components.
For example, a motherboard includes electrical connectors, a printed circuit board (PCB), capacitors,
resistors, and transformers. All these components work together to make the motherboard function
with the other parts of the computer. The CPU includes components such as integrated circuits,
switches, and extremely small transistors. These components process information and perform
calculations.
Generally speaking, a component is an element of a larger group. Therefore, the larger parts of a
computer, such as the CPU and hard drive, can also be referred to as computer components.
Technically, however, the components are the smaller parts that make up these devices.
Component may also refer to component video, which is a type of high-quality video connection. A
component connection sends the video signal through three separate cables — one for red, green, and
Page | 17
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
blue. This provides better color accuracy than composite video (typically a yellow connector), which
combines all the color signals into a single cable.
Computer = Technically, a computer is a programmable machine. This means it can execute a
programmed list of instructions and respond to new instructions that it is given. Today, however, the
term is most often used to refer to the desktop and laptop computers that most people use. When
referring to a desktop model, the term "computer" technically only refers to the computer itself -- not
the monitor, keyboard, and mouse. Still, it is acceptable to refer to everything together as the computer.
If you want to be really technical, the box that holds the computer is called the "system unit."
Some of the major parts of a personal computer (or PC) include the motherboard, CPU, memory (or
RAM), hard drive, and video card. While personal computers are by far the most common type of
computers today, there are several other types of computers. For example, a "minicomputer" is a
powerful computer that can support many users at once. A "mainframe" is a large, high-powered
computer that can perform billions of calculations from multiple sources at one time. Finally, a
"supercomputer" is a machine that can process billions of instructions a second and is used to calculate
extremely complex calculations.
Console = A console is the combination of a monitor and keyboard. It is a rudimentary interface in which
the monitor provides the output and the keyboard is used for input.
While any computer with a monitor and keyboard may be considered a console, the term most often
refers to a system used to control one or more servers. Early consoles in the 1970s and 1980s provided a
text-only "command line" interface, in which a network admin could type commands at a command
prompt. Modern consoles often provide a graphical interface that can be used to control machines on a
local network (LAN) or provide remote access to remote systems. These consoles typically include a
mouse for navigating graphical interfaces.
The terms "console" and "terminal" are often used synonymously. However, "terminal" may also be
used to describe the software that runs on a console, such as a command line interface or remote access
program. Mac OS X includes both a Terminal program that provides a command line interface, and a
Console utility that displays system logs and diagnostic reports.
A console may also refer to other types of hardware besides computer interfaces. For example, gaming
systems such as the PlayStation, Xbox, and Wii, are called video game consoles, while multi-channel
audio mixing boards are called mixing consoles.
Controller Card = The controller card, or simply "controller," is a piece of hardware that acts as the
interface between the motherboard and the other components of the computer. For example, hard
drives, optical drives, printers, keyboards, and mice all require controllers to work. Most computers
have all the necessary controllers built in the motherboard as chips, not full-sized cards. However, if you
add additional components such as a SCSI hard drive, you may need to add a controller card as well.
Controller cards are typically installed in one of the computer's PCI slots.
CPU = Stands for "Central Processing Unit." The CPU is the primary component of a computer that
processes instructions. It runs the operating system and applications, constantly receiving input from
the user or active software programs. It processes the data and produces output, which may stored by
an application or displayed on the screen.
Page | 18
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
The CPU contains at least one processor, which is the actual chip inside the CPU that performs
calculations. For many years, most CPUs only had one processor, but now it is common for a single CPU
to have at least two processors or "processing cores." A CPU with two processing cores is called a dualcore CPU and models with four cores are called quad-core CPUs. High-end CPUs may have six (hexacore) or even eight (octo-core) processors. A computer may also have more than one CPU, which each
have multiple cores. For example, a server with two hexa-core CPUs has a total of 12 processors.
While processor architectures differ between models, each processor within a CPU typically has its own
ALU, FPU, register, and L1 cache. In some cases, individual processing cores may have their own L2
cache, though they can also share the same L2 cache. A single frontside bus routes data between the
CPU and the system memory.
The terms "CPU" and "processor" are often used interchangeably. Some technical diagrams even label
individual processors as CPUs. While this verbiage is not incorrect, it is more accurate (and less
confusing) to describe each processing unit as a CPU, while each processor within a CPU is a processing
core.
CRT = Stands for "Cathode Ray Tube." CRT is the technology used in traditional computer monitors and
televisions. The image on a CRT display is created by firing electrons from the back of the tube to
phosphors located towards the front of the display. Once the electrons hit the phosphors, they light up
and are projected on the screen. The color you see on the screen is produced by a blend of red, blue,
and green light, often referred to as RGB.
The stream of electrons is guiding by magnetic charges, which is why you may get interference with
unshielded speakers or other magnetic devices that are placed close to a CRT monitor. Flat screen or
LCD displays don't have this problem, since they don't require a magnetic charge. LCD monitors also
don't use a tube, which is what enables them to be much thinner than CRT monitors. While CRT displays
are still used by graphics professionals because of their vibrant and accurate color, LCD displays now
nearly match the quality of CRT monitors. Therefore, flat screen displays are well on their way to
replacing CRT monitors in both the consumer and professional markets.
However, with the addition of 4k monitors, the death knell of CRT’s has rung.
MEMORY = DDR, DDR2, DDR3, DIMM, DRAM, Flash Drive, Flash Memory, SDRAM, Compact Flash, SD
Just like humans, computers rely a lot on memory. They need to process and store data, just like we do.
However, computers store data in digital format, which means the information can always be called up
exactly the way it was stored. Also, unlike our memory, the computer's memory doesn't get worse over
time.
While memory can refer to any medium of data storage, it usually refers to RAM, or random access
memory. When your computer boots up, it loads the operating system into its memory, or RAM. This
allows your computer to access system functions, such as handling mouse clicks and keystrokes, since
the event handlers are all loaded into RAM. Whenever you open a program, the interface and functions
used by that program are also loaded into RAM.
RAM is a very high-speed type of memory, which makes it ideal for storing active programs and system
processes. It is different than hard disk space in that RAM is made up of physical memory chips, while
Page | 19
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
hard disks are magnetic disks that spin inside a hard drive. Accessing RAM is much faster than accessing
the hard disk because RAM access is based on electric charges, while the hard drive needs to seek to the
correct part of the disk before accessing data. However, all the information stored in RAM is erased
when the computer's power is turned off. The hard disk, on the other hand, stores data magnetically
without requiring any electrical power.
Another common type of memory is flash memory, which is typically used for small devices such as
digital cameras, USB keychain drives, and portable music players like the iPod nano. This kind of
memory, known as "electrically erasable programmable read-only memory" (EEPROM), is convenient for
portable devices, since it stores information even when its power source is turned off, but is smaller and
more resilient than a hard drive.
DDR Stands for "Double Data Rate." It is an advanced version of SDRAM, a type of computer memory.
DDR-SDRAM, sometimes called "SDRAM II," can transfer data twice as fast as regular SDRAM chips. This
is because DDR memory can send and receive signals twice per clock cycle. The efficient operation of
DDR-SDRAM makes the memory great for notebook computers since it uses up less power. There are
multiples type of DDR memory all the way up to DDR5.
To summarize, memory is a vital part of the way computers and many electronic devices function. While
memory and RAM can often be used synonymously, it is good to know about other types of memory as
well. Hopefully you will be able to store the information you've learned in your own memory.
Degauss = Degaussing is the process of reducing a magnetic field. It can be used to reset the magnetic
field of a CRT monitor or to destroy the data on a magnetic storage device.
Desktop Computer = A desktop computer (or desktop PC) is a computer that is designed to stay in a
single location. It may be a tower (also known as a system unit) or an all-in-one machine, such as an
iMac. Unlike laptops and other portable devices, desktop computers cannot be powered from an
internal battery and therefore must remain connected to a wall outlet.
Digital Camera = A digital camera is a similar to a traditional film-based camera, but it captures images
digitally. When you take a picture with a digital camera, the image is recorded by a sensor, called a
"charged coupled device" or CCD. Instead of saving the picture on analog film like traditional cameras,
digital cameras save photos in digital memory. Some digital cameras have built-in memory, but most use
an SecureDigital or Compact Flash card.
Digital cameras have several advantages over their analog counterparts. While film rolls typically hold
about 24 pictures, memory cards have the capacity to store several hundred or even several thousand
pictures on a single card. Therefore, photographers can be much more liberal in the shots they take.
Since the images are captured digitally, unwanted images can be deleted directly on the camera. Most
digital cameras also include a small LCD screen that shows a live preview of the image, which makes it
easier to capture the perfect picture. These cameras usually include an option to record video as well.
In the past, people would need to drop off their film at a photo processing location in order to get their
pictures developed. With digital cameras, you can simply import the pictures to your computer via a USB
cable. Once the digital photos have been imported, you can publish them online or e-mail them to
friends. You can also edit them using photo editing software. If you want to print hard copies of your
photos, you can use a home printer or an online printing service.
Page | 20
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Digital cameras range greatly in size in quality. On the low end are portable electronic devices such as as
cell phones and iPods that have digital cameras built into them. In the mid range are are standalone
point-and-shoot cameras that have additional features and picture taking modes. On the high end are
digital SLR (single lens reflex) cameras, which support interchangeable lenses. These cameras are used
by photography professionals and capture high resolution images with accurate color.
While early digital cameras did not perform as well as their film-based counterparts, modern digital
cameras can now capture even higher quality images. Today's point-and-shoot cameras now have
resolutions in excess of 10 megapixels, which allows them to capture crystal clear images. They also
focus and capture images much faster than before, which gives them the responsiveness of analog
cameras. These improvements, along with the many advantages of digital photography, are why nearly
all photographers have gone digital.
Disk Drive = A disk drive is a device that reads and/or writes data to a disk. The most common type of
disk drive is a hard drive (or "hard disk drive"), but several other types of disk drives exist as well. Some
examples include removable storage devices, floppy drives, and optical drives, which read optical media,
such as CDs and DVDs.
While there are multiple types of disk drives, they all work in a similar fashion. Each drive operates by
spinning a disk and reading data from it using a small component called a drive head. Hard drives and
removable disk drives use a magnetic head, while optical drives use a laser. CD and DVD burners include
a high-powered laser that can imprint data onto discs.
Since hard drives are now available in such large capacities, there is little need for removable disk drives.
Instead of expanding a system's storage capacity with removable media, most people now use external
hard drives instead. While CD and DVD drives are still common, they have become less used since
software, movies, and music can now often be downloaded from the Internet. Therefore, internal hard
drives and external hard drives are the most common types of disk drives used today.
DMA = Stands for "Direct Memory Access." DMA is a method of transferring data from the computer's
RAM to another part of the computer without processing it using the CPU. While most data that is input
or output from your computer is processed by the CPU, some data does not require processing, or can
be processed by another device. In these situations, DMA can save processing time and is a more
efficient way to move data from the computer's memory to other devices.
For example, a sound card may need to access data stored in the computer's RAM, but since it can
process the data itself, it may use DMA to bypass the CPU. Video cards that support DMA can also
access the system memory and process graphics without needing the CPU. Ultra DMA hard drives use
DMA to transfer data faster than previous hard drives that required the data to first be run through the
CPU.
In order for devices to use direct memory access, they must be assigned to a DMA channel. Each type of
port on a computer has a set of DMA channels that can be assigned to each connected device. For
example, a PCI controller and a hard drive controller each have their own set of DMA channels.
Docking Station = A docking station, or dock, is a device that connects a laptop to multiple peripherals.
It provides a single connection point that allows a laptop to use a connected monitor, printer, keyboard,
and mouse. This allows a laptop to function like a desktop computer.
Page | 21
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Laptop manufacturers often build custom docking stations for their laptops. These docks usually have a
proprietary input port that connects to a matching port on specific laptop models. Early docks, such as
those built in the 1990s, included serial ports for connecting input devices, parallel ports for connecting
printers and scanners, and VGA ports for connecting monitors. In recent years, laptop docking stations
have become more standardized, with USB ports for connecting most peripherals and DVI ports for
connecting displays.
While modern docks provide standardized I/O ports, many docking stations still use a proprietary dock
connector, which means when you buy a new laptop, you may need to buy a new dock. Fortunately, the
Thunderbolt connector, first used in Apple's MacBook laptops, eliminates the need for a docking station.
A single Thunderbolt connection can support USB, FireWire, Ethernet, and DisplayPort connections.
Therefore, a Thunderbolt hub serves the same purpose as a laptop dock and is compatible with any
computer that has a standard Thunderbolt connection.
NOTE: Docking stations may also refer to hardware used to connect tablets, smartphones, and other
portable devices to one or more peripherals. However, these devices are generally called "docks" and
typically have fewer I/O connections than a laptop dock.
Dongle = A dongle is a small device, typically about the size of a flash drive, that plugs in to a computer.
Some dongles act as security keys while others serve as adapters. While early dongles connected to
parallel ports on PCs and ADB ports on Macs, modern versions typically connect to a USB port.
Security Keys - Security dongles are used for copy protection are designed to prevent software piracy.
For example, some high-end software applications, such as professional audio and video production
programs, require a dongle in order to run. The dongle, which is included with the software, must be
plugged in when you open the software program. If the correct dongle is not detected, the application
will produce an error message saying a dongle is required in order to use the software.
Adapters - Certain types of adapters are also called dongles. For instance, a dongle may provide a laptop
with different types of wired connections. Previous generations of laptops had expansion slots called
PCMCIA ports that were too skinny to include an Ethernet jack. Therefore, a dongle was required. These
types of dongles were typically one to three inch cables that connected to the card on one end and had
an Ethernet jack on the other. Modern Ethernet dongles have a similar appearance, but they usually
connect to a USB or Thunderbolt port.
Today, many dongles provide wireless capabilities. For example, USB Wi-Fi adapters are often called
dongles. Since most computers now have built-in Wi-Fi chips, cellular data adapters, such as 3G and 4G
dongles, are more prevalent. These types of dongles allow you to connect to the Internet via a cellular
carrier like Verizon or AT&T even when Wi-Fi is not available.
Dot Pitch = Dot pitch, or "pixel pitch," also commonly called DPI is a measurement that defines the
sharpness of a display. It measures the distance between the dots used to display the image on the
screen. This distance is very small and is typically measured in fractions of millimeters. The smaller the
dot pitch, the sharper the picture.
Dot pitch applies to both CRT monitors and flat-screen displays. While some large-screen CRTs have dotpitches as high as 0.51 mm, most computer displays have a dot pitch between 0.25 and 0.28 mm.
Similarly, most LCD displays have a dot pitch between 0.20 and 0.28 mm. Some high-end displays used
Page | 22
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
for scientific or medical imagery have dot pitches as low as 0.15 mm. These displays usually cost several
times as much as consumer displays of the same size.
While the terms "dot pitch" and "resolution" are related, they have different meanings. A display's
resolution refers to how many pixels can be displayed on the screen. For example, a 20" monitor may
have a maximum resolution of 1680 x 1050 pixels. When a display is set to its native resolution (typically
the maximum resolution), it may display exactly one pixel per dot. However, if the resolution is reduced,
the pixels will be larger than the dots used to display the image on the screen. In this case, each pixel is
mapped onto multiple dots.
Drive = A drive is a computer component used to store data. It may be a static storage device or may use
removable media. All drives store nonvolatile data, meaning the data is not erased when the power is
turned off.
Over the past several decades, drives have evolved along with other computer technologies. Below is a
list of different types of computer drives.






5.25 inch floppy drive - uses flexible removable media drive, stores up to 800 KB per floppy disk,
popular in the 1980s
3.5 inch floppy drive - uses more rigid removable media, stores up to 1.44 MB per disk, popular
in the 1990s
Optical drive - uses removable optical media such as CDs (800 MB), DVDs (4.7 - 17 GB), and Bluray discs (25-50 GB), available in both read-only and writable models, popular in the 2000s
Flash drive - a small, highly portable storage device that uses flash memory and connects
directly to a USB port
HDD (hard disk drive) - the most common internal storage device used by computers over the
past several decades, can store several terabytes (TB) of data
SSD (solid state drive) - serves the same purpose as a hard drive but contains no moving parts;
uses flash memory and provides faster performance than a hard drive
While there are many different types of drives, they are all considered secondary memory since they are
not accessed directly by the CPU. Instead, when a computer reads data from a drive, the data first gets
sent to the RAM so that it can be accessed more quickly. Even the fastest drives, likes SSDs, have much
slower read/write speeds than RAM.
Why are computer drives called "drives?" - While an official answer remains elusive, a compelling reason
is that early drives required a rotating device that would spin or "drive" the disk. While some modern
drives have no moving parts, the legacy term "drive" seems to have stuck.
DSL = Stands for "Digital Subscriber Line." DSL is a communications medium used to transfer digital
signals over standard telephone lines. Along with cable Internet, DSL is one of the most popular ways
ISPs provide broadband Internet access.
When you make a telephone call using a landline, the voice signal is transmitted using low frequencies
from 0 Hz to 4 kHz. This range, called the "voiceband," only uses a small part of the frequency range
supported by copper phone lines. Therefore, DSL makes use of the higher frequencies to transmit digital
signals, in the range of 25 kHz to 1.5 MHz. While these frequencies are higher than the highest audible
Page | 23
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
frequency (20 kHz), then can still cause interference during phone conversations. Therefore, DSL filters
or splitters are used to make sure the high frequencies do not interfere with phone calls.
Symmetric DSL (SDSL) splits the upstream and downstream frequencies evenly, providing equal speeds
for both sending and receiving data. However, since most users download more data than they upload,
ISPs typically offer asymmetric DSL (ADSL) service. ADSL provides a wider frequency range for
downstream transfers, which offers several times faster downstream speeds. For example, an SDSL
connection may provide 2 Mbps upstream and downstream, while an ASDL connection may offer 20
Mbps downstream and 1.5 Mbps upstream.
In order to access the Internet using DSL, you must connect to a DSL Internet service provider (ISP). The
ISP will provide you with a DSL modem, which you can connect to either a router or a computer. Some
DSL modems now have built-in wireless routers, which allows you to connect to your DSL modem via
Wi-Fi. A DSL kit may also include a splitter and filters that you can connect to landline phones.
NOTE: Since DSL signals have a limited range, you must live within a distance of an ISP’s DSLAM in order
to be eligible for DSL Internet service. While most urban locations now have access to DSL, it is not
available in many rural areas.
DSLAM = Stands for "Digital Subscriber Line Access Multiplexer." A DSLAM is a device used by Internet
Service Providers (ISPs) to route incoming DSL connections to the Internet. Since a "multiplexer"
combines multiple signals into one, a DSLAM combines a group of subscribers' connections into one
aggregate Internet connection.
For example, a DSL access multiplier may receive signals from all the DSL modems in a certain
neighborhood and patch them through to the Internet backbone. The DSLAM processes each incoming
connection and may limit the bandwidth of certain DSL lines. Most DSL service providers use multiple
DSLAMs to help route incoming and outgoing traffic in the most efficient way possible.
Dual-Core = A dual-core processor is a CPU with two processors or "execution cores" in the same
integrated circuit. Each processor has its own cache and controller, which enables it to function as
efficiently as a single processor. However, because the two processors are linked together, they can
perform operations up to twice as fast as a single processor can.
The Intel Core Duo, the AMD X2, and the dual-core PowerPC G5 are all examples of CPUs that use dualcore technologies. These CPUs each combine two processor cores on a single silicon chip. This is
different than a "dual processor" configuration, in which two physically separate CPUs work together.
However, some high-end machines, such as the PowerPC G5 Quad, use two separate dual-core
processors together, providing up to four times the performance of a single processor. Quad-core and
higher multi-core processor configurations have become common for general-purpose computing, not
only for PCs but for mobile devices such as smartphones and tablets.
While a dual-core system has twice the processing power of a single-processor machine, it does not
always perform twice as fast. This is because the software running on the machine may not be able to
take full advantage or both processors. Some operating systems and programs are optimized for
multiprocessing, while others are not. Though programs that have been optimized for multiple
processors will run especially fast on dual-core systems, most programs will see at least some benefit
from multiple processors as well.
Page | 24
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
DVI = Stands for "Digital Video Interface." DVI is a video connection standard created by the Digital
Display Working Group (DDWG). Most DVI ports support both analog and digital displays. If the display is
analog, the DVI connection converts the digital signal to an analog signal. If the display is digital, no
conversion is necessary.
There are three types of DVI connections: 1) DVI-A (for analog), 2) DVI-D (for digital), and 3) DVI-I
(integrated, for both analog and digital). The digital video interface supports high bandwidth signals,
over 160 MHz, which means it can be used for high resolution displays such as UXGA and HDTV. You
may find DVI ports on video cards in computers as well as on high-end televisions.
DVR = Stands for "Digital Video Recorder." A DVR is basically a VCR that uses a hard drive instead of
video tapes. It can be used to record, save, and play back television programs. Unlike a VCR, however, a
DVR can also pause live TV by recording the current show in real time. The user can choose to fast
forward (often during commercials) to return to live television.
Most satellite and cable TV companies offer a DVR as an option with their digital television packages.
Since cable boxes already provide program listings through some kind of TV guide interface, most DVRs
allow users to use the guide to schedule recordings. For example, a user can use the remote to search
through the guide's program listings for the current week and select the shows he would like to record.
TiVo, the "brand name" DVR, performs the same functions as a DVR offered directly from a cable
company. However, TiVo users can choose to buy the DVR box instead of renting it. Since TiVo is a
standalone box, it does not require cable or satellite TV. While TiVo users who buy their own TiVo boxes
may avoid the monthly rental fees, they must pay a monthly fee for program listings if they want to
schedule recordings.
DVRs conveniently save shows in an list that the user can access at any time. Since the shows are stored
on DVR's hard drive, there is no need to rewind or fast forward to play a certain show, like a VCR
requires. While DVRs make it even easier to record your favorite shows every week or even every day, it
also makes it easier to watch more TV. And an excuse to watch more TV is something most of us don't
need.
E-reader = An e-reader, or "e-book reader," is a portable hardware device designed for reading digital
publications. These include e-books, electronic magazines, and digital versions of newspapers. Since
textual data does not require a lot of storage space, most e-readers can store thousands of books and
other publications. Just like an iPod can store an entire music library, a single e-reader can store a large
collection of books.
Dozens of different e-readers are available, but some of the most popular ones include the Amazon
Kindle, the Barnes and Noble Nook, and the Sony Reader. These devices all support a wide range of
eBook formats and can download content over a wireless network. Many e-readers have a monochrome
display, often called "electronic paper," while others have a full-color backlit display. While the
electronic paper displays do not provide color images, the screen appears more like a paper page from a
book, and it can be easily viewed in bright sunlight.
Tablets, such as the Apple iPad, the BlackBerry PlayBook, and the Amazon Kindle Fire are often
considered e-readers, since they can be used for reading digital publications. However, it is more
accurate to refer to these devices as tablets that can be used as e-readers since they are not designed
Page | 25
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
primarily as digital readers. Tablets offer more capabilities than e-readers, but e-readers are often better
suited for just reading e-books.
EIDE = Stands for "Enhanced Integrated Drive Electronics." EIDE is an improved version of the IDE drive
interface that provides faster data transfer rates than the original standard. While the original IDE drive
controllers supported transfer rates of 8.3 Mbps, EIDE can transfer data up to 16.6 Mbps, which is twice
as fast.
The term EIDE can be a bit ambiguous, since it technically refers to an ATA standard known as ATA-2 or
Fast ATA. Therefore, the terms EIDE, ATA-2, and Fast ATA may be used synonymously. To add to the
confusion, EIDE may also refer to the ATA-3 standard, which is similar to ATA-2, but includes additional
features. ATA-3 supports the same maximum data transfer rate as ATA-2, but has SMART support and
uses a 44 pin connector.
While EIDE was the most common drive controller used for many years, it has since been replaced by
updated versions of the ATA standard that support Ultra DMA. These include the ATA-4 through ATA-7
standards, which provide data throughput rates from 33 to 133 Mbps. Most modern computers use a
completely new standard called "Serial ATA," or SATA, which supports even faster transfer rates.
eSATA = Stands for "External Serial Advanced Technology Attachment." eSATA is a variation of the SATA
interface that supports external storage devices. It was standardized in 2004 and uses the same pins and
same protocols as internal SATA. However, it provides a slightly different, more rugged connector. The
eSATA standard also supports a cable length of two meters compared to the one meter cable length
supported by SATA.
Since eSATA uses the same protocols as SATA, an eSATA drive offers the same high-speed data transfer
rates as an internal SATA drive. For example, an eSATA 3.0 drive can transfer data at 6 Gbps or 4.8 Gbps,
taking into account the data encoding process. This is significantly faster than Firewire 800 (800 Mbps)
and USB 2.0 (480 Mbps) and is on par with USB 3.0 (5 Gbps).
Because eSATA offers such fast transfer rates, it has been a popular external hard drive interface used
by video editors, audio producers, and other media professionals. While eSATA is one of the fastest
interfaces available, it is surpassed by both Thunderbolt (10 Gbps) and Thunderbolt 2.0 (20 Gbps), which
are alternatives to eSATA.
eSATAp =Unlike Firewire, USB, and Thunderbolt, the eSATA interface does not provide power to
connected devices. Therefore, all drives connected via eSATA must include a separate power connector
to provide electricity to the device. A variation of eSATA, called eSATAp or eSATA USB Hybrid Port
(EUHP), combines four USB pins and two 12-volt power pins into the eSATA connector. An eSATAp port
supports both eSATA and USB connectors. It allows connected devices to draw power from the
computer's power supply, eliminating the need for a separate power cable.
Ethernet = Ethernet, pronounced "E-thernet" (with a long "e") Ethernet is also known by its technical
name, "IEEE 802.3.", is the standard way to connect computers on a network over a wired connection. It
provides a simple interface and for connecting multiple devices, such computers, routers, and switches.
With a single router and a few Ethernet cables, you can create a LAN, which allows all connected devices
to communicate with each other.
Page | 26
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
A standard Ethernet cable is slightly thicker than a phone cable and has an RJ45 connector on each end.
Ethernet ports look similar to telephone jacks, but are wider. You can plug or unplug devices on an
Ethernet network while they are powered on without harming them.
Like USB, Ethernet has multiple standards that all use the same interface. These include:



10BASE-T - supports up to 10 Mbps
100BASE-T - supports up to 100 Mbps
1000BASE-T (also called "Gigabit Ethernet") - supports up to 1,000 Mbps
Most Ethernet devices are backwards compatible with lower-speed Ethernet cables and devices.
However, the connection will only be as fast as the lowest common denominator. For example, if you
connect a computer with a 10BASE-T NIC to a 100BASE-T network, the computer will only be able to
send and receive data at 10 Mbps. If you have a Gigabit Ethernet router and connect devices to it using
100BASE-T cables, the maximum data transfer rate will be 100 Mbps.
While Ethernet is still the standard for wired networking, it has been replaced in many areas by wireless
networks. Wi-Fi allows you to connect your laptop or smartphone to a network without being tethered
to the wall by a cable. The 802.11ac Wi-Fi standard even provides faster maximum data transfer rates
than Gigabit Ethernet. Still, wired connections are less prone to interference and are more secure than
wireless ones, which is why many businesses and organizations still use Ethernet.
Expansion Card = An expansion card is a printed circuit board that can be installed in computer to add
functionality to it. For example, a user may add a new graphics card to his computer to give it more 3D
graphics processing power. An audio engineer may add a professional sound card to his machine to
increase the computer's audio input and output connections. Users that need more Firewire or USB
ports can add Firewire or USB expansion cards, which provide additional connections.
Most expansion cards are installed in PCI slots. This includes variations of PCI, such as PCI-X and PCI
Express. Graphics cards may also be installed in an AGP slot, which is designed specifically for video
cards. Since expansion cards require open slots, they can only be installed in computers that have
available expansion slots. Therefore, computers like the Apple iMac and other all-in-one machines
cannot accept expansion cards. Computer towers, however, often have two or three open expansion
slots, and can accept multiple cards.
Laptops don't use traditional expansion cards because of their small form factor. However, some models
can accept removable PCMCIA cards that add extra ports or other functionality to the computer.
External Hard Drive = Nearly all personal computers come with an internal hard drive. This drive stores
the computer's operating system, programs, and other files. For most users, the internal hard drive
provides enough disk space to store all the programs and files. However, if the internal hard drive
becomes full or if the user wants to back up the data on the internal hard drive an external hard drive
may be useful.
External hard drives typically have one of three interfaces – USB, eSATA or Firewire. USB hard drives
commonly use the USB 2.0 interface because it supports data transfer rates of up to 480 Mbps. USB 1.1
only supports transfers of up to 12 Mbps, which would make the hard drive seem slow to even the most
Page | 27
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
patient people. Firewire drives may use either Firewire 400 or Firewire 800, which support data transfer
rates of up to 400 and 800 Mbps respectively.
The most likely users to need external hard drives are those who do audio and video editing. This is
because high-quality media files can fill up even the largest hard drives. Fortunately, external hard drives
can be daisy chained, which means they can be connected one after the other and be used at the same
time. This allows for virtually unlimited amounts storage.
Users who do not require extra storage may still find external hard drives useful for backing up their
main hard drive. External hard drives are a great backup solution because they can store an exact copy
of another hard drive and can be stored in a safe location. Using the drive to restore data or perform
another backup is as simple as connecting it to the computer and dragging the necessary files from one
drive to another.
While most external hard drives come in heavy, protective cases, some hard drives are designed
primarily for portability. These drives usually don't hold as much data as their larger desktop
counterparts, but they have a sleek form factor and can easily be transported with a laptop computer.
Some portable drives also include security features such as fingerprint recognition that prevent other
people from accessing data on the drive in case it is lost.
Fiber Optic Cable = Fiber optic cable is a high-speed data transmission medium. It contains tiny glass or
plastic filaments that carry light beams. Digital data is transmitted through the cable via rapid pulses of
light. The receiving end of a fiber optic transmission translates the light pulses into binary values, which
can be read by a computer.
Because fiber optic cables transmit data via light waves, they can transfer information at the speed of
light. Not surprisingly, fiber optic cables provide the fastest data transfer rates of any data transmission
medium. They are also less susceptible to noise and interference compared to copper wires or
telephone lines. However, fiber optic cables are more fragile than their metallic counterparts and
therefore require more protective shielding. While copper wires can be spliced and mended as many
times as needed, broken fiber optic cables often need to be replaced.
Since fiber optic cables provide fast transfer speeds and large bandwidth, they are used for a large part
of the Internet backbone. For example, most transatlantic telecommunications cables between the U.S.
and Europe are fiber optic. In recent years, fiber optic technology has become increasingly popular for
local Internet connections as well. For example, some ISPs now offer "fiber Internet," which provides
Internet access via a fiber optic line. Fiber connections can provide homes and businesses with data
transfer speeds of 1 Gbps.
File Server = As the name implies, a file server is a server that provides access to files. It acts as a central
file storage location that can be accessed by multiple systems. File servers are commonly found in
enterprise settings, such as company networks, but they are also used in schools, small organizations,
and now are very popular in home networks for storage of pictures, music and video.
A file server may be a dedicated system, such as network attached storage (NAS) device, or it may
simply be a computer that hosts shared files. Dedicated file servers are typically used for enterprise
applications, since they provide faster data access and offer more storage capacity than non-dedicated
systems. In home networks, personal computers are often used as file servers. However, personal NAS
Page | 28
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
devices are also available for home users that require more storage capacity and faster performance
than a non-dedicated file server would allow.
File servers can be configured in multiple ways. For example, in a home setting, a file server may be set
to automatically allow access to all computers on the local network (LAN). In a business setting where
security is important, a file server may require all client systems to log in before accessing the server.
Others may only grant access to a specific list of machines, which can be defined by MAC address or IP
address. Internet file servers, which provide access to files over the Internet, often require an FTP login
before users can download files.
NOTE: When you connect to a file server on a local network, it usually appears as a hard disk on your
computer. You can double-click the hard disk icon to view the contents and browse through directories
on the server, just like local folders. If you want to copy a file from the server to your computer, simply
drag the file to your desktop or another folder on your local disk. If the file server has write permissions
enabled, you can also copy local files to the server by dragging them to a directory on the server. When
you copy files to or from the file server, it may appear that they are simply being transferred from one
local folder to another. However, the files are actually being transferred across the network.
Firewire = Firewire not dead, but it’s on life support. FireWire is an I/O interface developed by Apple
Computer. It is also known as IEEE 1394, which is the technical name standardized by the IEEE. Other
names for IEEE 1394 include Sony i.Link and Yamaha mLAN, but Apple's FireWire name the most
commonly used.
There are two primary versions of the FireWire interface – FireWire 400 (IEEE 1394a) and FireWire 800
(IEEE 1394b). FireWire 400 uses a 6-pin connector and supports data transfer rates of up to 400 Mbps.
FireWire 800 uses a 9-pin connector and can transfer data at up to 800 Mbps. The FireWire 800
interface, which was introduced on Macintosh computers in 2003, is backwards compatible with
FireWire 400 devices using an adapter. Both interfaces support daisy chaining and can provide up to 30
volts of power to connected devices.
FireWire is considered a high-speed interface, and therefore can be used for connecting peripheral
devices that require fast data transfer speeds. Examples include external hard drives, video cameras,
and audio interfaces. On Macintosh computers, FireWire can be used to boot a computer in target disk
mode, which allows the hard drive to show up as an external drive on another computer. Mac OS X also
supports networking two computers via a FireWire cable.
While FireWire has never been as popular as USB, it has remained a popular choice for audio and video
professionals. Since FireWire supports speeds up to 800 Mbps, it is faster than USB 2.0, which maxes out
at 480 Mbps. In fact, even FireWire 400 provides faster sustained read and write speeds than USB 2.0,
which is important for recording audio and video in real-time. Future versions of IEEE 1394, such as
FireWire 1600 and 3200, were designed to support even faster data transfer speeds. However, the
FireWire interface has been superseded by Thunderbolt, which can transfer data at up to 10,000 Mbps
(10 Gbps) and is backwards compatible with multiple interfaces.
Flatbed = A flatbed is a type of scanner or copier that uses a flat, glass surface for scanning documents
or other objects. Most flatbed scanners have an adjustable lid that can be raised to allow magazines,
books, and other thick objects to be scanned. This is a significant benefit over sheet-fed scanners or
Page | 29
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
copiers (sometimes referred to as automatic document feeders, which can only accept paper
documents.
Flatbed scanners and copy machines range in size from standard letter size (8.5"x11") to legal size and
beyond. For example, a scanner used to scan architectural blueprints may be the size of several lettersize scanners. Because of their large size capacity and ability to scan thick objects, flatbed scanners are
more versatile than sheet-fed scanners. However, they cannot automatically feed pages into the
scanner, which means scanning multiple pages can be a time-consuming process. For this reason, some
scanners and copy machines include both a flatbed scanning surface for large or thick objects, and an
ADF for feeding multiple pages at once.
Floppy Disk = Floppy disks have an interesting name, considering they do not appear to be "floppy."
However, if you take the actual disk out of the protective casing, you will discover that the disk is, in fact,
rather flexible. It is coated with iron oxide and stores data magnetically, just like a hard disk.
The first floppy disks were created in 1969, the same year the Internet had its origin. These disks were 8
inches in diameter and were read-only, like a CD-ROM, meaning no data could be written to them by the
user. The first 8 inch disks only held 80KB of data, but later versions could hold as much as 800KB.
In 1978, a 5.25 inch disk was introduced, which could hold a whopping 360KB of data. Later revisions of
the 5.25 inch floppy disk could store 1.2MB. These disks were used in early desktop PCs, such as the
Apple IIe. In 1987, the 3.5 inch HD (high density) floppy disk was released, which could hold 1.44MB
after being formatted. These disks were a little more durable than the 5.25 inch disks and were also
more portable. For the next decade, the 3.5 inch floppy disk became the standard means of distributing
commercial software titles and backing up personal data.
In the late 1990s, CD-ROMs began to replace floppy disks as the standard means of distributing
software. A few years later, consumers began migrating to recordable CDs for backing up their data.
Apple's original iMac, released in 1998, was the first mainstream computer to not even include a floppy
disk drive. While it took several years, many PC manufacturers eventually followed suit.
Now most software is distributed on CDs and DVDs and most people back up their data either on
recordable CDs or USB flash drives. Floppy disks are finally becoming a thing of the past, which is good,
considering they are notorious for losing data. Still, the floppy disk will always have a special place in the
hearts and minds of veteran computer users as it was the data storage medium many people grew up
with.
Gateway = A gateway is a hardware device that acts as a "gate" between two networks. It may be a
router, firewall, server, or other device that enables traffic to flow in and out of the network.
While a gateway protects the nodes within network, it also a node itself. The gateway node is
considered to be on the "edge" of the network as all data must flow through it before coming in or going
out of the network. It may also translate data received from outside networks into a format or protocol
recognized by devices within the internal network.
A router is a common type of gateway used in home networks. It allows computers within the local
network to send and receive data over the Internet. A firewall is a more advanced type of gateway,
which filters inbound and outbound traffic, disallowing incoming data from suspicious or unauthorized
Page | 30
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
sources. A proxy server is another type of gateway that uses a combination of hardware and software to
filter traffic between two networks. For example, a proxy server may only allow local computers to
access a list of authorized websites.
NOTE: Gateway is also the name of a computer hardware company founded in the United States in
1985. The company was acquired by Acer in 2007 but still sells computers under the Gateway name.
GPU = Stands for "Graphics Processing Unit." Like the CPU (Central Processing Unit), it is a single-chip
processor. However, the GPU is used primarily for computing 3D functions. This includes things such as
lighting effects, object transformations, and 3D motion. Because these types of calculations are rather
taxing on the CPU, the GPU can help the computer run more efficiently.
The first company to develop the GPU was NVidia, Inc. Its GeForce 256 GPU can process 10 million
polygons per second and has over 22 million transistors. Compare that to the 9 million transistors found
on the Pentium III chip. Wow -- that's a lot of processing power. There is also a workstation version of
the chip called the Quadro, designed for CAD applications. This chip can process over 200 billion
operations a second and deliver up to 17 million polygons per second. If only you could think that fast
during those darn Calculus tests...
SSD, HDD, Hard Disk, Hard Drive = When you save data or install programs on your computer, the
information is typically written to your hard disk. The hard disk is a spindle of magnetic disks, called
platters, that record and store information. Because the data is stored magnetically, information
recorded to the hard disk remains intact after you turn your computer off. This is an important
distinction between the hard disk and RAM, or memory, which is reset when the computer's power is
turned off.
The hard disk is housed inside the hard drive, which reads and writes data to the disk. The hard drive
also transmits data back and forth between the CPU and the disk. When you save data on your hard
disk, the hard drive has to write thousands, if not millions, of ones and zeros to the hard disk. It is an
amazing process to think about, but may also be a good incentive to keep a backup of your data.
A solid-state drive (SSD, also known as a solid-state disk although it contains neither an actual disk nor a
drive motor to spin a disk) is a solid-state storage device that uses integrated circuit assemblies as
memory to store data persistently. SSD technology primarily uses electronic interfaces compatible with
traditional block input/output (I/O) hard disk drives, which permit simple replacements in common
applications. Additionally, new I/O interfaces, like SATA Express, have been designed to address specific
requirements of the SSD technology.
SSDs have no moving (mechanical) components. This distinguishes them from traditional
electromechanical magnetic disks such as hard disk drives (HDDs) or floppy disks, which contain spinning
disks and movable read/write heads. Compared with electromechanical disks, SSDs are typically more
resistant to physical shock, run silently, have lower access time, and less latency. However, while the
price of SSDs has continued to decline over time, consumer-grade SSDs are still roughly eight to nine
times more expensive per unit of storage than consumer-grade HDDs.
As of 2014, most SSDs use NAND-based flash memory, which retains data when power is lost. For
applications requiring fast access but not necessarily data persistence after power loss, SSDs may be
Page | 31
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
constructed from random-access memory (RAM). Such devices may employ batteries as integrated
power sources to maintain data for a certain amount of time after external power is lost.
Hybrid drives or solid-state hybrid drives (SSHDs) combine the features of SSDs and HDDs in the same
unit, containing a large hard disk drive and an SSD cache to improve performance of frequently accessed
data.
Hardware = Computer hardware refers to the physical parts of a computer and related devices. Internal
hardware devices include motherboards, hard drives, and RAM. External hardware devices include
monitors, keyboards, mice, printers, and scanners.
The internal hardware parts of a computer are often referred to as components, while external
hardware devices are usually called peripherals. Together, they all fall under the category of computer
hardware. Software, on the other hand, consists of the programs and applications that run on
computers. Because software runs on computer hardware, software programs often have system
requirements that list the minimum hardware required for the software to run.
HDMI = Stands for "High-Definition Multimedia Interface." HDMI is a digital interface for transmitting
audio and video data in a single cable. It is supported by most HDTVs and related components, such as
DVD and Blu-ray players, cable boxes, and video game systems.
While other types of A/V connections require separate cables for audio and video data, HDMI carries the
audio and video streams together, greatly eliminating cable clutter. For example, a component cable
connection requires three cables for video and two for audio, totaling five cables in all. The same
information can be transmitted using one HDMI cable.
Because HDMI is a digital connection, HDMI cables are less prone to interference and signal noise than
analog cables. Also, since most components, such as DVD players and digital cable boxes process
information digitally, using HDMI eliminates the analog to digital conversion other interfaces require.
Therefore, HDMI often produces the best quality picture and sound compared to other types of
connections.
HDMI cables are typically more expensive than analog cables, largely because they cost more to
manufacture. But it is important to remember that with HDMI, you don't need to buy separate audio
and video cables. Besides, the single all-purpose connection may alone be worth the difference to those
who don't like dealing with confusing cables and connections. Just remember that before you buy an
HDMI cable, make sure the devices you are connecting have HDMI connections available.
Heat Sink = A computer's CPU may perform millions of calculations every second. As the processor
continues to work at a rapid pace, it begins to generate heat. If this heat is not kept in check, the
processor could overheat and eventually destroy itself.
Fortunately, CPUs include a heat sink, which dissipates the heat from the processor, preventing it from
overheating. The heat sink is made out of metal, such as a zinc or copper alloy, and is attached to the
processor with a thermal material that draws the heat from away the processor towards the heat sink.
Heat sinks can range in size from barely covering the processor to several times the size of the processor
if the CPU requires it.
Page | 32
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Most heat sinks also have "fins," which are thin slices of metal that are connected to the base of the
heat sink. These additional pieces of metal further dissipate the heat by spreading it over a much larger
area. A fan is often used to cool the air surrounding the heat sink, which prevents the heat sink from
getting too hot. This configuration is referred to as a heat sink and fan or HSF combination. While heat
sinks are used in nearly all computer CPUs, they have become commonplace in video card processors, or
GPUs, as well.
Host = A host is a computer that is accessible over a network. It can be a client, server, or any other type
of computer. Each host has a unique identifier called a hostname that allows other computers to access
it.
Depending on the network protocol, a computer's hostname may be a domain name, IP address, or
simply a unique text string. For example, the hostname of a computer on a local network might be TechTerms.local, while an Internet hostname might be techterms.com. A host can access its own data over a
network protocol using the hostname "localhost."
Host vs Server - The terms host and server are often used interchangeably, but they are two different
things. All servers are hosts, but not all hosts are servers. To avoid confusion, servers are often defined
as a specific type of host, such as a web host or mail host. For instance, a mail host and mail server may
refer to the same thing.
While a server refers to a specific machine, a host may also refer to an organization that provides a
service over the Internet. For example, a web host (or web hosting company) maintains multiple web
servers and provides web hosting services for clients. A file host may provide online storage using
multiple file servers. In other words, a hosting company hosts multiple servers that serve data to clients.
Hot Swappable = In electronics terminology, the word "hot" is often used to mean "active" or "powered
on." Therefore, a hot swappable device is a peripheral or component that can be removed or added
while a computer is running. Replacing a device while a computer is powered on is called "hot
swapping."
Most early I/O devices were not hot swappable. This is because early ports, such as parallel ports and
SCSI ports did not support connecting or removing devices while the computer was powered on. In fact,
removing devices from these older ports while the computer was running could cause damage to them
or the computer. Since it was hassle for users to turn off their computers each time they needed to
connect or reconnect a device, newer I/O ports were designed to be hot swappable. Modern ports that
support hot swapping include USB, FireWire, and Thunderbolt.
Most modern PCs include only hot swappable ports. Therefore, the term is now used most often to
describe internal components that can be replaced while the computer is running. A common example is
a server hard drive. Since servers need to run constantly to avoid downtime, they typically support hot
swappable hard drives. Rack-based servers often provide easy access to one or more hard drives on the
front face of the rack unit. This allows server administrators to quickly add more storage or replace old
hard drives without powering down the server.
NOTE: Except for rare exceptions, RAM is generally not hot swappable.
Page | 33
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
HUB = A network hub is a device that allows multiple computers to communicate with each other over a
network. It has several Ethernet ports that are used to connect two or more network devices together.
Each computer or device connected to the hub can communicate with any other device connected to
one of the hub's Ethernet ports.
Hubs are similar to switches, but are not as "smart." While switches send incoming data to a specific
port, hubs broadcast all incoming data to all active ports. For example, if five devices are connected to
an 8-port hub, all data received by the hub is relayed to the five active ports. While this ensures the data
gets to the right port, it also leads to inefficient use of the network bandwidth. For this reason, switches
are much more commonly used than hubs.
USB hub = A USB hub is a device that allows multiple peripherals to connect through a single USB port. It
is designed to increase the number of USB devices you can connect to a computer. For example, if your
computer has two USB ports, but you want to connect five USB devices, you can connect a 4-port USB
hub to one of the ports. The hub will create four ports out of one, giving you five total ports. The USB
interface allows you to daisy chain USB hubs together and connect up to 127 devices to a single
computer.
Some USB hubs include a power supply, while others do not. If you're connecting basic devices like a
mouse, keyboard, and USB flash drive, an unpowered or "passive" USB hub should work fine. However,
some peripherals, like external hard drives and backlit keyboards, require additional electrical power. In
order for these types of devices to function through a USB hub, you may need use a powered or "active"
hub that provides 5 volts of power to connected devices.
IBM Compatible = The personal computer market in the early 1980's consisted primarily of Apple and
IBM computers. Apple's systems ran a proprietary operating system developed by Apple, while IBM
machines primarily ran PC-DOS. As the demand for personal computers began to grow, IBM decided to
license the DOS operating system to other manufacturers. These companies began producing personal
computers that were called PC clones or IBM compatibles.
As several other manufacturers began producing PCs, supplies grew and costs began to drop. This
enabled more people to afford PCs and sales of IBM compatibles began to dominate the personal
computer market. It wasn't long until the new manufacturers' PC sales surpassed the number of
computers sold directly by IBM. The Apple Macintosh also gained substantial market share when it was
introduced in 1984, but the low cost and wide availability of IBM compatibles kept their sales strong.
Sales of IBM compatibles surged again in 1995, when Microsoft introduced the Windows 95 operating
system. However, by that time, the term "IBM compatible" had become almost irrelevant, since most
PCs used Microsoft Windows as the primary operating system. Also, PC manufacturers had been
building their own computers for many years, and there were few similarities between IBM's own PCs
and IBM compatibles.
In 2005, IBM stopped manufacturing personal computers. The company that started the PC revolution is
no longer in the market. Therefore, the term "IBM compatible" is a bit outdated, though it can still be
used to describe Windows-based computers. The term "PC" is more appropriate, albeit a bit ambiguous,
since Macs are technically PCs too. Therefore, the term "Windows computer" seems to be the best way
to describe a modern day IBM compatible.
Page | 34
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
IDE (Hardware) = IDE was the most widely-used type of hard drive from the mid 1990s to the late 2000s.
The "integrated" aspect of the name describes how the controller is integrated into the drive itself. IDE
and ATA are often used synonymously since they both refer to the same type of hard drive. However,
ATA describes the interface while IDE describes the actual hard drive.
The first IDE standard (ATA-1) was released in 1994 and supported data transfer rates of 8.3 Mbps in
DMA mode. Enhanced IDE (ATA-2) was standardized in 1996 and supported data transfer rates up to
16.7 Mbps – twice the rate of the original standard. The next several IDE standards were labeled using
ATA versions (up to ATA-7), maxing out at 133 Mbps. The IDE interface was eventually superseded by
SATA, an even faster interface.
Impact Printer = An impact printer is a type of printer that operates by striking a metal or plastic head
against an ink ribbon. The ink ribbon is pressed against the paper, marking the page with the
appropriate character, dot, line, or symbol. Common examples of impact printers include dot matrix,
daisy-wheel printers, and ball printers.
Dot matrix printers work by striking a grid of pins against a ribbon. Different characters are printed by
using different pin combinations. Daisy-wheel printers use a circular wheel with "petals" that each have
a different character or symbol on the end. In order to print each character, the wheel spins to the
appropriate petal and a hammer strikes the petal against the ribbon and the page. Similarly, ball printers
use a spherical ball with raised characters on the outside. The ball spins to each character before
printing it on the page.
While impact printers still have some uses (such as printing carbon copies), most printers are now nonimpact printers. These printers, such as laser and inkjet printers are much quieter than impact printers
and can print more detailed images.
Inkjet = Inkjet printers are the most common type of consumer printers. The inkjet technology works by
spraying very fine drops of ink on a sheet of paper. These droplets are "ionized" which allows them to be
directed by magnetic plates in the ink's path. As the paper is fed through the printer, the print head
moves back and forth, spraying thousands of these small droplets on the page.
While inkjet printers used to lack the quality and speed of laser printers, they have become almost as
fast as laser printers and some can even produce higher-quality images. Even low-budget inkjet printers
can now print high-resolution photos. The amazing thing is, as the quality of inkjet printers has
improved, the prices have continued to drop. However, for most people, refilling the inkjet cartridges a
few times will often cost more than the printer.
Input Device = An input device is any device that provides input to a computer. There are dozens of
possible input devices, but the two most common ones are a keyboard and mouse. Every key you press
on the keyboard and every movement or click you make with the mouse sends a specific input signal to
the computer. These commands allow you to open programs, type messages, drag objects, and perform
many other functions on your computer.
Since the job of a computer is primarily to process input, computers are pretty useless without input
devices. Just imagine how much fun you would have using your computer without a keyboard or mouse.
Not very much. Therefore, input devices are a vital part of every computer system.
Page | 35
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
While most computers come with a keyboard and mouse, other input devices may also be used to send
information to the computer. Some examples include joysticks, MIDI keyboards, microphones, scanners,
digital cameras, webcams, card readers, UPC scanners, and scientific measuring equipment. All these
devices send information to the computer and therefore are categorized as input devices. Peripherals
that output data from the computer are called output devices.
Integrated Circuit = An integrated circuit, or IC, is small chip that can function as an amplifier, oscillator,
timer, microprocessor, or even computer memory. An IC is a small wafer, usually made of silicon, that
can hold anywhere from hundreds to millions of transistors, resistors, and capacitors. These extremely
small electronics can perform calculations and store data using either digital or analog technology.
Digital ICs use logic gates, which work only with values of ones and zeros. A low signal sent to to a
component on a digital IC will result in a value of 0, while a high signal creates a value of 1. Digital ICs are
the kind you will usually find in computers, networking equipment, and most consumer electronics.
Analog, or linear ICs work with continuous values. This means a component on a linear IC can take a
value of any kind and output another value. The term "linear" is used since the output value is a linear
function of the input. For example, a component on a linear IC may multiple an incoming value by a
factor of 2.5 and output the result. Linear ICs are typically used in audio and radio frequency
amplification.
Interface = The term "interface" can refer to either a hardware connection or a user interface. It can
also be used as a verb, describing how two devices connect to each other.
A hardware interface is used to connect two or more electronic devices together. For example, a printer
typically connects to a computer via a USB interface. Therefore, the USB port on the computer is
considered the hardware interface. The printer itself also has a USB interface, which is where the other
end of the USB cable connects. Several common peripherals connect to a computer via USB, while other
devices use a Firewire connection or other interface. Ethernet connections are commonly used for
networking, which is why most cable modems and routers have an Ethernet interface.
Many other electronic devices besides computers use some type of interface to connect to other
equipment. For example, a TV may connect to a Blu-ray player via an HDMI cable and may connect to a
cable box using component cables. Audio devices may have either analog or digital audio connections
and may include a MIDI interface, which is used to transfer MIDI data. iPods have a proprietary "dock
connector" interface, which allows them to connect to a power source and transfer data via USB.
Since there are many different types of electronic devices, there are also a lot of hardware interfaces.
Fortunately, standards like USB, Firewire, HDMI, and MIDI have helped consolidate the number of
interfaces into a manageable number. After all, it would be pretty difficult if each digital camera, printer,
keyboard, and mouse used a different interface. Computers would need a lot more ports on the back!
iPad = The iPad is a tablet computer developed by Apple. It is smaller than a typical laptop, but
significantly larger than the average smartphone. The iPad does not include a keyboard or a trackpad,
but instead has a touchscreen interface, which is used to control the device.
Like the iPhone, the iPad runs Apple's iOS operating system. This allows the iPad to run third-party apps,
which can downloaded from Apple's App Store. While apps designed for the iPhone can also be installed
Page | 36
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
and run on the iPad, many iOS apps are developed specifically for the iPad. Since the iPad's screen is
much larger than the iPhone's screen, iPad apps can include more user interface features that would not
fit within an iPhone app. Therefore, productivity, graphics, and video-editing apps are often developed
specifically for the iPad rather than the iPhone.
The iPad's 9.7 in screen size also makes it ideal as an e-reader. The iBooks app allows you to download
electronic versions of books from the iBookstore and read them on your iPad. Since the iPad has a full
color screen, it supports novels as well as art books and illustrated children's stories. Books can be read
one page at a time in portrait mode or with pages side by side in landscape mode.
All versions of the iPad include Wi-Fi capability, which can be used for surfing the Web, checking email,
and downloading apps directly to the device. Some versions of the iPad also include 3G support for
transferring data over a cellular connection, though this capability requires a monthly cellular service
contract. While the original iPad did not include a camera, the iPad 2 includes both rear-facing and
front-facing cameras. These cameras can be used for video conferencing with other iPad, iPhone, or Mac
users via the FaceTime feature.
iPhone = The iPhone is a smartphone developed by Apple. The first iPhone was released in June, 2007
and an updated version has been released roughly every year since then. While the iPhone was
originally only available to AT&T customers, the iPhone 4 was released on the Verizon network in
February, 2010.
The iPhone has a sleek, minimalist design, and differs from other smartphones in its lack of buttons.
Most operations on the iPhone are performed using the touch screen display. The only physical buttons
include a sleep/wake button, a mute switch, volume up/down buttons, and a home button. All versions
of the iPhone have a rear-facing camera, but the iPhone 4 introduced a front-facing camera, which can
be used for video calls made using the FaceTime feature. The iPhone 4 also includes a 960 x 640 pixel
"retina display," which has double the resolution of previous iPhone displays.
Internally, the iPhone runs the iOS, an operating system developed by Apple for portable devices. This
allows the iPhone to run "apps," or applications developed specifically for the iPhone. Apps can be
downloaded from Apple's App Store, which can be accessed through iTunes or directly from the
iPhone's built-in App Store app. There are hundreds of thousands of apps available from the App Store,
which provide the iPhone with limitless functionality.
iPod = The iPod is a portable music player developed by Apple Computer. Though it is an Apple product,
the iPod can be used with both Macs and PCs. The iTunes software, also created by Apple, is used to
organize and transfer songs and playlists to the iPod. Both iTunes and the iPod support a wide variety of
audio formats, including MP3, AAC, WAV, and AIFF. MP3 is the most common audio compression
format, while AAC is the format used by the iTunes Music Store. WAV and AIFF are nearly identical
formats that store CD-quality audio.
Since introducing the iPod in 2001, Apple has released several new versions of the popular device. These
include iPod, iPod mini, iPod Special Edition, iPod photo, and iPod shuffle. iPod mini is a smaller version
of the iPod that comes in various colors and stores fewer songs. iPod Special Edition is a variation of the
basic iPod (the first being a black U2 iPod with the signatures of the band members on the back). iPod
photo is an iPod with a color screen that allows users to store and view a library of photos as well as play
Page | 37
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
music. iPod shuffle is an extra small iPod that only holds a couple hundred songs and does not have a
screen.
All iPods store data on an internal hard drive, except the iPod Shuffle, which uses flash memory. This
means each iPod, including the shuffle, can also be used as a hard drive. Aside from being a music
player, the iPod can serve as a backup device, a basic organizer, and an alarm clock. To transfer files to
the iPod, you must first connect it to your computer using a USB or Firewire cable. iTunes can
automatically transfer your playlists and songs or you can change the program's preferences to manually
update the iPod.
Because of its superb interface and unmatched ease of use, the iPod has become the staple product of
the portable music player market. Granted, the "cool factor" of owning an iPod has certainly helped it
gain popularity as well.
Keyboard = As the name implies, a keyboard is basically a board of keys. Along with the mouse, the
keyboard is one of the primary input devices used with a computer. The keyboard's design comes from
the original typewriter keyboards, which arranged letters and numbers in a way that prevented the
type-bars from getting jammed when typing quickly. This keyboard layout is known as the QWERTY
design, which gets its name from the first six letters across in the upper-left-hand corner of the
keyboard.
While the design of computer keyboards may have come from typewriters, today's keyboards have
many other keys as well. Modifier keys, such as Control, Alt/Option, and Command (Mac) or the
Windows key (Windows) can be used in conjunction with other keys as "shortcuts" to perform certain
operations. For example, pressing Command-S (Mac), or Control-S (Windows) typically saves a
document or project you are working on. Most of today's computer keyboards also have a row of
function keys (F1 through F16) along the top of the keyboard, arrow keys arranged in an upside-down T,
and a numeric keypad on the right-hand side. Some keyboards have even more buttons, allowing you to
change the system volume, eject a CD, or open programs such as your e-mail or Web browser.
Kindle = The Kindle is a portable e-reader developed by Amazon.com. It allows you to download and
read digital books, newspapers, magazines, and other electronic publications. The Kindle also includes a
built-in speaker and headphone jack for listening to audiobooks or background music.
The first Kindle was released in November 2007 and several updated versions have been released since
then. Each Kindle, except for the Kindle Fire, uses special type of display called "E Ink" or electronic
paper. Unlike a typical laptop screen or computer monitor, the E Ink display is monochrome and has no
backlight. Instead, it has a light-colored background and text and images are displayed in grayscale. The
result is a paper-like display that can be easily viewed in bright sunlight.
You can download content to a Kindle using the built-in Wi-Fi connection (available in Kindles released in
2010 or later) or Amazon's proprietary 3G Whispernet network. This Whispernet network is a free
service provided by Amazon.com to Kindle users and does not require a wireless subscription.
Amazon.com also provides a "Whispersync" that allows users to wirelessly sync data between multiple
Kindle devices.
While the Kindle was originally designed as a basic e-reader, each iteration has provided more
functionality. For example, recent versions of the Kindle include a web browser, which allows you to
Page | 38
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
view websites. The Kindle Fire, which was introduced in September 2011, is as much as tablet as an ereader, since it has a color touchscreen and runs the Android operating system. Kindle Fire users can
also download apps directly from the Amazon.com Appstore.
LAN = Stands for "Local Area Network," and is pronounced like "land" without the "d". (Computer
people will think you're weird if you pronouce it "L-A-N"). A LAN is a computer network limited to a
small area such as an office building, university, or even a residential home. Most mid to large-sized
businesses today use LANs, which makes it easy for employees to share information. Currently, the most
common type of LANs are Ethernet-based and use software from Novell or Oracle. However, with the
emergence of wireless networking, wireless LANs have become a popular alternative.
Laptop = Laptop computers, also known as notebooks, are portable computers that you can take with
you and use in different environments. They include a screen, keyboard, and a trackpad or trackball,
which serves as the mouse. Because laptops are meant to be used on the go, they have a battery which
allows them to operate without being plugged into a power outlet. Laptops also include a power
adapter that allows them to use power from an outlet and recharges the battery.
While portable computers used to be significantly slower and less capable than desktop computers,
advances in manufacturing technology have enabled laptops to perform nearly as well as their desktop
counterparts. In fact, high-end laptops often perform better than low or even mid-range desktop
systems. Most laptops also include several I/O ports, such as USB ports, that allow standard keyboards
and mice to be used with the laptop. Modern laptops often include a wireless networking adapter as
well, allowing users to access the Internet without requiring any wires.
While laptops can be powerful and convenient, the convenience often comes at a price. Most laptops
cost several hundred dollars more than a similarly equipped desktop model with a monitor, keyboard,
and mouse. Furthermore, working long hours on a laptop with a small screen and keyboard may be
more fatiguing than working on a desktop system. Therefore, if portability is not a requirement for your
computer, you may find better value in a desktop model.
Laser Printer = A laser printer is a printer that uses a focused beam or light to transfer text and images
onto paper. Though contrary to popular belief, the laser does not actually burn the images onto the
paper. Instead, as paper passes through the printer, the laser beam fires at the surface of a cylindrical
drum called a photoreceptor. This drum has an electrical charge (typically positive), that is reversed in
areas where the laser beam hits it. By reversing the charge in certain areas of the drum, the laser beam
can print patterns (such as text and pictures) onto the photoreceptor.
Once the pattern has been created on the drum, it is coated with toner from a toner cartridge. The
toner is black in most cartridges, but may be cyan, magenta, and yellow in color laser printers. The
positively charged toner clings to areas of the drum that have been negatively charged by the laser.
When the paper passes through the printer, the drum is given a strong negative charge, which allows
the toner to transfer and stick to the paper. The result is a clean copy of the image written on the paper.
Because laser printers do not use ink, they have less image smearing problems than inkjet printers and
are able to print pages faster. While laser printers and toner cartridges typically cost more than inkjet
printers and ink cartridges, most laser toner cartridges last several times longer than ink cartridges,
which makes their cost per page about equal. For this reason, businesses tend to use laser printers,
Page | 39
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
while consumers are more likely to use inkjet printers. Laser printers typically have a resolution of 600
dpi (dots per inch) or higher.
LCD = Stands for "Liquid Crystal Display." LCDs are super-thin displays that are used in laptop computer
screens and flat panel monitors. Smaller LCDs are used in handheld TVs, PDAs, and portable video game
devices. The image on an LCD screen is created by sandwiching an electrically reactive substance
between two electrodes. This color of this substance can be changed by increasing or reducing the
electrical current. Since LCD screens are based on the principle of blocking light (rather than emitting it),
they use up much less power than standard CRT (Cathode-Ray Tube) monitors.
LED = Stands for "Light-Emitting Diode." An LED is an electronic device that emits light when an electrical
current is passed through it. Early LEDs produced only red light, but modern LEDs can produce several
different colors, including red, green, and blue (RGB) light. Recent advances in LED technology have
made it possible for LEDs to produce white light as well.
LEDs are commonly used for indicator lights (such as power on/off lights) on electronic devices. They
also have several other applications, including electronic signs, clock displays, and flashlights. Since LEDs
are energy efficient and have a long lifespan (often more than 100,000 hours), they have begun to
replace traditional light bulbs in several areas. Some examples include street lights, the red lights on
cars, and various types of decorative lighting. You can typically identify LEDs by a series of small lights
that make up a larger display. For example, if you look closely at a street light, you can tell it is an LED
light if each circle is comprised of a series of dots.
The energy efficient nature of LEDs allows them to produce brighter light than other types of bulbs while
using less energy. For this reason, traditional flat screen LCD displays have started to be replaced by LED
displays, which use LEDs for the backlight. LED TVs and computer monitors are typically brighter and
thinner than their LCD counterparts.
Just so you know, the LED was discovered in 1908, but until 1962 wasn’t able to be developed.
MAC Address = Stands for "Media Access Control Address," and no, it is not related Apple Macintosh
computers. A MAC address is a hardware identification number that uniquely identifies each device on a
network. The MAC address is manufactured into every network card, such as an Ethernet card or Wi-Fi
card, and therefore cannot be changed.
Because there are millions of networkable devices in existence, and each device needs to have a unique
MAC address, there must be a very wide range of possible addresses. For this reason, MAC addresses
are made up of six two-digit hexadecimal numbers, separated by colons. For example, an Ethernet card
may have a MAC address of 00:0d:83:b1:c0:8e. Fortunately, you do not need to know this address, since
it is automatically recognized by most networks.
Mainframe = A mainframe is an ultra high-performance computer made for high-volume, processorintensive computing. They are typically used by large businesses and for scientific purposes. You
probably won't find a mainframe in any household. In the hierarchy of computers, mainframes are right
below supercomputers, the most powerful computers in the world. (Which is why they are aptly named
"supercomputers.") Yet a mainframe can usually execute many programs simultaneously at a high
speed, whereas supercomputers are designed for a single process. Currently, the largest manufacturers
of mainframes are IBM and Unisys.
Page | 40
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Microcomputer = A microcomputer is a computer designed for individual use. The term was introduced
in the 1970s to differentiate desktop computer systems from larger minicomputers. It is often used
synonymously with the term "desktop computer," but it may refer to a server or laptop as well.
In the 1960s and 1970s, computers were much larger than today, often taking up several cubic feet of
space. Some mainframe computers could even fill a large room. Therefore, the first computers that
could fit on a desktop were appropriately labeled "microcomputers" in comparison to these larger
machines.
The first microcomputers became available in the 1970s and were used primarily by businesses. As they
became cheaper, individuals were able to buy their own microcomputer systems. This lead to the
personal computer revolution of the 1980s, in which microcomputers became a mainstream consumer
product.
As microcomputers grew in popularity, the name "microcomputer" faded and was replaced with other
more specific terms. For example, computers purchased for business purposes were labeled as
workstations, while computers bought for home use became known as personal computers, or PCs.
Eventually, computer manufacturers developed portable computers, which were called laptops. While
computers have evolved a lot over the past few decades, these same terms are still used today.
Minicomputer = While a minicomputer sounds like a small computer, the name can be a bit misleading.
In fact, minicomputers are several times the size of desktop PCs and are only one step below
mainframes in the hierarchy of computer classes.
The term "minicomputer" was introduced in the 1960s to describe powerful computers that were not as
large as mainframes, which sometimes could fill an entire room. Instead, most minicomputers were a
few feet wide and several feet tall. They were primarily used by large businesses during the 1960s and
1970s to process large amounts of data. Some minicomputers also functioned as servers, allowing
multiple users to access them from connected terminals.
As computer processors became smaller and more powerful, microcomputers began to rival
minicomputers in processing power. Therefore, in the 1980s, minicomputers started becoming less
relevant and eventually became obsolete. Today, rack-based servers have assumed this obsolete type of
computer.
Modem= The word modem is actually short for Modulator/Demodulator. (There's something you can
really impress your friends with). A modem is a communications device that can be either internal or
external to your computer. It allows one computer to connect another computer and transfer data over
telephone lines (POTS –(plain old telephone service)). The original dial-up modems are becoming
obsolete because of their slow speeds and are being replaced by the much faster cable and DSL
modems.
Monitor = The term "monitor" is often used synonymously with "computer screen" or "display." The
monitor displays the computer's user interface and open programs, allowing the user to interact with
the computer, typically using the keyboard and mouse.
Older computer monitors were built using cathode ray tubes (CRTs), which made them rather heavy and
caused them to take up a lot of desk space. Most modern monitors are built using LCD technology and
Page | 41
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
are commonly referred to as flat screen displays. These thin monitors take up much less space than the
older CRT displays. This means people with LCD monitors have more desk space to clutter up with stacks
of papers, pens, and other objects.
"Monitor" can also be used as a verb. A network administrator may monitor network traffic, which
means he watches the traffic to make sure the bandwidth usage is within a certain limit and checks to
see what external sources may be attempting to access the network. Software programs may monitor
the system's CPU performance as well as RAM and hard disk usage.
Finally, monitors also refer to speakers used for monitoring sound. Audio engineers typically use "studio
monitors" to listen to recordings. These high-end speakers allow the engineers to accurately mix and
master audio tracks. So a sound mixer could be monitoring a recording visually using a computer
monitor, while monitoring the sound using audio monitors at the same. As you can tell, "monitor" serves
as a rather multipurpose word.
Motherboard = The motherboard is the main circuit board of your computer and is also known as the
mainboard or logic board. If you ever open your computer, the biggest piece of silicon you see is the
motherboard. Attached to the motherboard, you'll find the CPU, ROM, memory RAM expansion slots,
PCI slots, and USB ports. It also includes controllers for devices like the hard drive, DVD drive, keyboard,
and mouse. Basically, the motherboard is what makes everything in your computer work together.
Each motherboard has a collection of chips and controllers known as the chipset. When new
motherboards are developed, they often use new chipsets. The good news is that these boards are
typically more efficient and faster than their predecessors. The bad news is that older components often
do not work with new chipsets. Of course, if you are planning on upgrading multiple components, it may
be more cost-effective to just buy a new computer.
Mouse = While most people don't want to see a mouse running around in their home, they typically
don't have a problem seeing one sitting by their computer. This is because, along with the keyboard, the
mouse is one of the primary input devices used with today's computers. The name comes from the small
shape of the mouse, which you can move quickly back and forth on the mouse pad, and the cord, which
represents the mouse's tail. Of course, if you are using a wireless mouse, the analogy does not work so
well.
All mice have at least one button, though most mice have two or three. Some also have additional
buttons on the sides, which can be assigned to different commands. Most mice also have a scroll-wheel,
which lets you scroll up and down documents and Web pages by just rolling the wheel with your index
finger.
Early mice tracked movement using a ball in the bottom of the mouse. This "mouse ball" pushed against
different rollers as it moved, measuring the mouse's speed and direction. However, now most mice use
optical technology, which uses a beam of light to track the mouse's motion. Optical mice are more
accurate than roller-based mice and they have the added bonus of not getting dirty inside.
A plurality of plurals - When you refer to more than one mouse, you can call them either "mice" or
"mouses," since both terms are acceptable. However, "mouses" is technically the correct version since
"mice" is the plural form designated for living creatures. Still, most people have a hard time saying
"mouses," which is why "mice" is more commonly used.
Page | 42
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Mouse Pad = A mouse pad, or "mousing surface," is a surface designed for tracking the motion of a
computer mouse. Early mouse pads were literally "pads," which had soft surfaces. The slight cushion
allowed the mouse ball to roll smoothly in any direction. Modern mouse pads typically have harder
surfaces, designed to track the motion of optical mice.
Mouse pads come in many shapes and sizes. Most are rectangular, though are some are circular or oval
shaped. While the majority of mouse pads are less than a foot wide or long, graphic artists and CAD
designers sometimes use mouse pads that are much larger. These super-sized mousing surfaces allow
them to use a slow, precise mouse speed without needing to lift up the mouse very often. Computer
gamers also prefer larger mouse pads, because they offer more desktop real estate for making long, fast
motions.
Since optical mice track motion by detecting small changes in the surface below the mouse, the mouse
pad's surface affects how accurately the mouse responds to movement. Lighter colored mouse pads
typically produce the best results since they reflect the most light. Some highly reflective mouse pads
even claim to have "battery saving" capabilities for wireless mice. The improvement in battery life most
likely comes from how quickly the mouse enters low-power mode when it stops moving.
Since optical mice work on just about any opaque surface, you typically do not even need a mouse pad
to use a mouse. However, a good mouse pad can provide smooth, accurate motion, which is beneficial if
cursor accuracy is important for your work. When choosing a mouse pad, make sure you get one large
enough for your needs, but not so large that it won't fit on your desk. If possible, choose a mouse pad
with a built-in wrist rest or buy a separate wrist rest if necessary. This small ergonomic addition will
relieve a lot of strain on your wrist no matter what mouse pad you use.
Multiprocessing = For many years, the speed of computer processors increased through improvements
in the architecture and clock speed of processors. However, in recent years, chip manufacturers have
reached a limit in how small they can make the transistors inside CPUs without them overheating.
Therefore, using multiple processors, or multiprocessing, has become the next step in increasing
computing performance.
Multiprocessing can be implemented in two different ways: 1) using more than one physical processor,
or 2) using a processor with multiple cores. For example, early Power Mac G5 computers had multiple
physical processors, each with their own heat sink and frontside bus. When Apple switched to using
Intel processors in 2006, they began using dual-core processors. These chips look like a single processor,
but act as two. Now, some machines like the Mac Pro, have quad-core processors, which include four
processing cores. Some Mac Pros even have two physical quad-core processors, giving the computer a
total of eight processors. Most Windows and Linux-based PCs now use multi-core processors as well.
While multiprocessing sounds like a logical choice for improving computing performance, it must be
supported by the computer's operating system in order to work correctly. Fortunately, current versions
of both Windows and Mac OS X fully support multiprocessing. This means they can manage multiple
processors as one CPU, dividing the processing load between them. Still, not all tasks can be split equally
between two or more processors. Therefore, while multiprocessing may increase a computer's speed, it
does not typically improve performance by the exact factor of processors in the machine.
Page | 43
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
NAS = Stands for "Network Attached Storage." A typical computer stores data using internal and
external hard drives. If the computer is connected to a network, it can share data on its connected hard
drives with other systems on the network. While this allows multiple computers to send data back and
forth, it requires that each computer share its files individually. Therefore, if a computer is turned off or
disconnected from the network, its files will not be available to the other systems.
By using NAS, computers can store and access data using a centralized storage location. Instead of each
computer sharing its own files, the shared data is stored on a single NAS server. This provides a simpler
and more reliable way of sharing files on a network. Once an NAS server connected to a network
(typically via Ethernet), it can be configured to share files with multiple computers on the network. It
may allow access to all systems or may provide access to a limited number of authenticated machines.
NAS servers typically contain multiple hard drives, providing a large amount of shared disk space for
connected systems to save data. They are often used in business networks, but have become increasing
more common in home networks as well. Since NAS uses a centralized storage device, it can be a simple
way for family members to share and backup their data.
NIC = Stands for "Network Interface Card." Pronounced "nick," this is the card that physically makes the
connection between the computer and the network cable. These cards typically use an Ethernet
connection and are available in 10, 100, and 1000 Base-T configurations. A 100 Base-T card can transfer
data at 100 Mbps. So if you want to connect your computer to a network, you better get yourself a NIC.
Non-Impact Printer = Early printers, such as dot matrix and daisywheel printers were called impact
printers, since they operated by striking an ink ribbon against the paper. Most modern printers,
including inkjet and laser printers, don't include an ink ribbon and are considered to be non-impact
printers.
Non-impact printers are generally much quieter than impact printers since they don't physically strike
the page. For example, inkjet printers spray tiny drops of ink onto the page, while laser printers use a
cylindrical drum that rolls electrically charged ink onto the paper. Both of these methods are non-impact
and provide an efficient printing process that produces little sound. The low impact nature of inkjet and
laser printers also means they are less likely to need maintenance or repairs than earlier impact printers.
Northbridge = The northbridge is a chip inside a computer that connects the central processing unit
(CPU) to other primary components in the system. These components include RAM (a.k.a. system
memory), the frontside bus (FSB), PCI Express cards, and the AGP card. The northbridge also connects to
the southbridge, which controls the remaining components of the computer.
While the CPU is the main processor inside the computer, the northbridge is the primary controller. It
acts like a traffic cop directing data to and from the CPU. Therefore, the performance of the northbridge
chip affects the overall performance of the computer. On Intel systems, the northbridge is also called
the Memory Controller Hub (MCH), since it controls the data flow to and from the system memory.
NVRAM = Stands for "Non-Volatile Random Access Memory." NVRAM is a type of RAM that retains data
after the host device's power is turned off. Two common types of NVRAM include SRAM and EEPROM.
SRAM (pronounced "s-ram") retains data by using an alternative source of power such as a battery.
SRAM is often used to store computer hardware settings that need to be maintained when the
Page | 44
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
computer is shut down. Common examples include the BIOS settings on Windows computers or the
PRAM settings on Macintosh systems. Since SRAM typically uses a battery to retain memory, if the
battery dies or is disconnected, the data stored in the SRAM will be lost. Therefore, if BIOS or PRAM
settings are not retained after a computer is restarted, it is likely the computer's battery has lost its
charge and needs to be replaced.
EEPROM (pronounced "e-e-p-rom") stores data using electrical charges that maintain their state without
electrical power. Therefore, EEPROM does not need a battery or other power source to retain data. The
most common type of EEPROM is flash memory, which is used for USB keychain drives and other
portable electronic devices.
OLED = Stands for "Organic Light Emitting Diode" and is pronounced "oh-led." OLED is a type of flat
screen display similar to an LCD that does not require a backlight. Instead, each LED within an OLED
panel lights up individually.
An OLED screen has six layers that work together to produce color images. These layers include the
following, from bottom to top:






Substrate - the foundational structure that supports the panel; typically made out of glass or
plastic
Anode - a transparent layer that removes electrons when electrical current flows through it
Conductive Layer - contains organic molecules or polymers such as polyaniline that transfer
current to the emissive layer
Emissive Layer - contains organic molecules or polymers such as polyfluorene that light up when
current is passed through them
Cathode - injects electrons into the other layers when current flows through it
Cover - the top protective layer of the screen; typically made out of glass or plastic
How does an OLED work? - OLEDs display light using a process called electrophosphorescence. While
this may sound like an intimidating term, the process is relatively simple. Electrical current flows from
the cathode (negatively charged) to the anode (positively charged), causing electrons to move to the
emissive layer. These electrons find "holes" (where atoms missing electrons) in the conductive layer and
produce light when they fill these holes. The color of the light depends on the organic molecule that the
current passed through in the emissive layer.
Since the diodes in OLED displays light up individually, there is no need for a backlight. This means
OLEDs can have darker blacks than LED/LCD displays and use less electricity. The are also thinner and
may be curved or even bendable. While OLEDs have many advantages over LED/LCD displays, it has
been expensive to produce large, reliable OLED screens. Therefore, OLEDs have been more common in
small electronics, such as smartphones and tablets. As OLED production costs decrease and reliability
increases, the technology will become more commonly used in larger screens, such as televisions and
computer monitors.
Optical Drive = In the real world, "optical" refers to vision, or the ability to see. In the computer world,
however, "optical" refers to lasers, which can "see" and read data on optical discs. These discs include
CDs and DVDs, which are made up of millions of small bumps and dips. Optical drives have lasers that
read these bumps and dips as ones and zeros, which the computer can understand.
Page | 45
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Some common types of optical drives include CD-ROM, CD-RW, DVD-ROM, DVD-RW, and Blu-ray drives.
CD and DVD writers, such as CD-R and DVD-R drives use a laser to both read and write data on the discs.
The laser used for writing the data is much more powerful than the laser that reads the data, as it
"burns" the bumps and dips into the disc. While optical drives can spin discs at very high speeds, they
are still significantly slower than hard drives, which store data magnetically. However, because optical
media is inexpensive and removable, it is the most common format used for distributing computer
software.
Optical Media = Blu-ray, DVD, DVD+R, DVD+RW, DVD-R, DVD-RAM, DVD-RW, CD, CD-R, CD-ROM, CDRW - Media, in the computer world, refers to various types of data storage. For example, hard drives,
CDs, DVDs, and USB drives are all different types of media. Optical media refers to discs that are read by
a laser.
Optical media typically does not have as fast of a seek time as hard drives (the time it takes to access
information on different parts of the disk), but it has many other advantages. Because optical discs are
not based on magnetic charges like hard drives are, the discs are less likely to lose their data and have a
longer shelf life -- around seven times longer than magnetic media. The discs are also more durable than
hard drives and are much cheaper to produce, making them great for backups and for transferring small
amounts of data between different computers.
OSD = Stands for "On Screen Display." Most monitors include an on screen menu for making
adjustments to the display. This menu, called the OSD, may be activated by pressing the Menu button
located on the side or front of your monitor. Once the OSD appears on the screen, you can navigate
through the menu and make adjustments using the Plus (+) and Minus (-) buttons, which are usually
located right next to the menu button.
On screen displays vary between monitors, but most include the basic brightness and contrast controls.
Some include more advanced color controls, allowing you to calibrate individual red, green, and blue
(RGB) settings. Many monitors also support positioning adjustments, which can be used to make slight
modifications to the position and tilt of the screen. Monitors that include built-in speakers may include
audio adjustments as well.
Most CRT and flat screen monitors, such as LCD and LED displays, include OSDs. However, flat screen
displays typically have less adjustment options since their screen position is more consistent than older
CRT monitors. Some newer monitors also allow users to make adjustments through a software interface
rather than using the standard on screen display. Regardless of what monitor you have, it is good to be
familiar with the OSD so you know how to adjust the display settings
Output Device = Any device that outputs information from a computer is called, not surprisingly, an
output device. Since most information from a computer is output in either a visual or auditory format,
the most common output devices are the monitor and speakers. These two devices provide instant
feedback to the user's input, such as displaying characters as they are typed or playing a song selected
from a playlist.
While monitors and speakers are the most common output devices, there are many others. Some
examples include headphones, printers, projectors, lighting control systems, audio recording devices,
and robotic machines. A computer without an output device connected to it is pretty useless, since the
Page | 46
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
output is what we interact with. Anyone who has ever had a monitor or printer stop working knows just
how true this is. Of course, it is also important to be able to send information to the computer, which
requires an input device.
Overclocking = For some people, fast is never fast enough. In the world of computers, a fast processor
can be made even faster by overclocking it. Overclocking involves increasing the clock speed of the
computer's CPU past the rate at which it was originally designed to run.
Some ways to overclock a processor include increasing the CPU's operating speed in the system BIOS or
changing the hardware jumper settings for the processor. Modifying these settings may allow the
processor to run faster than set by the manufacturer, which may increase the overall performance of
the computer. However, since other settings, such as the memory speed, frontside and backside bus
speeds, and other components are fixed, there may not be a significant increase in performance.
Regardless of how overclocking is done, it potentially may cause problems with the computer. After all,
when you overclock a computer, you are altering the manufacturer's design of the machine. For
example, if there is not enough electrical current to to power the processor at the new rate, it may slow
down or stop running completely. Also, if the heat sink cannot sufficiently cool the processor running at
the faster rate, it may overheat, causing your computer to freeze or crash. This is actually a preventive
measure, since the computer stops functioning when the CPU gets too hot. Otherwise, the CPU may
literally fry itself and your overclocked processor may become an overcooked processor.
In summary, overclocking a processor can be a risky endeavor. It is best left to computer enthusiasts
who understand their hardware and are willing to accept the risks associated with it. Since overclocking
voids your computer's warranty, don't expect the manufacturer to replace your cooked CPU for free. If
you want a fast machine that is supported by the manufacturer, buying a fast processor to begin with is
your best bet.
Parallel Port = This interface is found on the back of older PCs and is used for connecting external
devices such as printers or a scanners. It uses a 25-pin connector (DB-25) and is rather large compared
to most new interfaces. The parallel port is sometimes called a Centronics interface, since Centronics
was the company that designed the original parallel port standard. It is sometimes also referred to as a
printer port because the printer is the device most commonly attached to the parallel port. The latest
parallel port standard, which supports the same connectors as the Centronics interface, is called the
Enhanced Parallel Port (EPP). This standard supports bi-directional communication and can transfer data
up to ten times faster than the original Centronics port. However, since the parallel port is a rather
dated technology, don't be surprised to see USB or Firewire interfaces completely replace parallel ports
in the future.
PC = Stands for "Personal computer." PCs are are what most of us use on a daily basis for work or
personal use. A typical PC includes a system unit, monitor, keyboard, and mouse. Most PCs today also
have a network or Internet connection, as well as ports for connecting peripheral devices, such as digital
cameras, printers, scanners, speakers, external hard drives, and other components.
Personal computers allow us to write papers, create spreadsheets, track our finances, play games, and
do many other things. If a PC is connected to the Internet, it can be used to browse the Web, check e-
Page | 47
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
mail, communicate with friends via instant messaging programs, and download files. PCs have become
such an integral part of our lives that it can be difficult to imagine life without them!
While PC stands for "personal computer," the term can be a bit ambiguous. This is because Macintosh
computers are often contrasted with PCs, even though Macs are also technically PCs. However, Apple
itself has used the term "PC" to refer to Windows-based machines, as opposed to its own computers,
which are called "Macs." While the Mac/PC dilemma remains, PCs can always contrasted with other
types of computers, such as mainframes and server computers, such as Web servers and network file
servers. In other words, if you use a computer at home or at work, you can safely call it a PC.
PCI = Stands for "Peripheral Component Interconnect." It is a hardware bus designed by Intel and used
in both PCs and Macs. Most add-on cards such as SCSI, Firewire, and USB controllers, use a PCI
connection. Some graphics cards use PCI, but most new graphics cards connect to the AGP slot. PCI slots
are found in the back of your computer and are about 3.5" long and about 0.5" high. So before you go
buy that Firewire expansion card, make sure you have at least one PCI slot available.
PCI Express = First came PCI, then PCI-X, then PCI Express. PCI Express can be abbreviated as PCIe or,
less commonly and more confusingly, PCX. Unlike earlier PCI standards, PCI Express does not use a
parallel bus structure, but instead is a network of serial connections controlled by a hub on the
computer's motherboard. This enables PCI Express cards to run significantly faster than previous PCI
cards.
Because the PCI Express interface is a serial connection, it does not have a speed measured in
Megahertz, like PCI or PCI-X. Instead, its performance is measured in data throughput speeds, which are
several times faster than PCI-X. Furthermore, PCI Express is available in x1, x4, x8, and x16
implementations, which increases the bandwidth by the corresponding amount. However, larger
implementations require longer PCI Express slots. For example, a x4 slot is larger than a x1 slot and a x16
slot is larger than a x8 slot. A PCI Express card can be inserted in any slot that is large enough for it. For
example, a x8 card could be inserted into a x16 slot, but a not a x1 or x4 slot.
Since PCI Express connections can support such fast data transfer rates, they can be used to connect
high-speed devices such as Gigabit Ethernet cards and high-end video cards. For this reason, PCI Express
is expected to replace both PCI and AGP connections. Fortunately, PCI Express was designed to be
backwards compatible with both PCI hardware and software. However, to use a PCI Express card, your
computer must have at least one available PCI Express slot.
PCI-X = Stands for "Peripheral Component Interconnect Extended." Once again, "Ex" is abbreviated with
an "X" instead of an "E." Most desktop computers include one or more PCI slots for expanding the
computer's I/O capabilities. Common PCI cards include network cards, sound cards, and video cards. In
the early 1990s, when PCI was first introduced, the 66 MHz speed of PCI was more than sufficient for PCI
cards available at the time. However, a decade later, expansion cards supported much faster data
transfer rates and therefore became faster than the PCI bus would support. To prevent the interface
from becoming a bottleneck, PCI-X was introduced.
The first version of PCI-X supported data transfer rates of 133 MHz, which is more than twice as fast as
the original PCI standard. Then along came PCI-X 2.0, which can run at speeds of 266 or 533 MHz. These
speeds are fast enough to support Gigabit Ethernet cards and video capture devices without slowing
Page | 48
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
them down. PCI-X cards can only be installed in PCI-X slots, but the slots themselves are backwards
compatible with PCI cards.
PCMCIA = Stands for "Personal Computer Memory Card International Association." It can also mean,
perhaps more appropriately, "People Can't Memorize Computer Industry Acronyms." This way-to-long
acronym stands for an association founded in 1989 which develops standards for expansion cards for
portable computers. However, the term is most commonly associated with the actual cards
standardized by the organization. These cards are referred to as "PCMCIA cards," or simply "PC cards."
There are three types of PCMCIA cards, all of which are rectangular and measure 8.56 by 5.4 cm., but
have different widths:



Type I: up to 3.3 mm. thick, mainly used to add additional ROM or RAM.
Type II: up to 5.5 mm. thick, typically used for fax/modem cards.
Type III: up to 10.5 mm. thick, often used to attach portable disk drives.
PCMCIA slots also come in three sizes -- a Type I slot can hold one Type I card, a Type II slot can hold one
Type II card or two Type I cards, and a Type III slot can hold one Type III card or one Type I and one Type
II card. PC Cards can be removed or inserted "on the fly," which means you don't have to turn your
computer off to exchange them and you don't have to restart for your computer to recognize them.
NOTE: This technology has mostly been phased out and it’s extremely hard to find any new computers
with this interface.
PDA = Stands for "Personal Digital Assistant." These are the little electronic devices you see people
jotting stuff down on in public. Usually, when you see someone with a PDA, they will be holding it out
far front of them for everyone to see. Fortunately, as PDAs become more common, more people will
have them and we won't have to deal with the people who make sure everyone else sees that they have
one.
The first PDA, called the Newton, was created by Apple in 1993. Since then, numerous other companies
have jumped on the bandwagon and have added many new designs and options to the PDA market. The
Palm Pilot, Handspring Visor, HP Jordana, Compaq Aero, Sharp Mobilon, and Sony Cli? are all common
PDAs. Ironically, Apple's Newton was discontinued when the company was having financial difficulties in
1998. Today's PDAs allow you to organize your schedule, take notes, do math calculations, play games,
write memos, and even surf the Internet and send e-mail. They are cool things to have, but if you decide
to get one, please do us all a favor and don't show it off in public. Nearly every smartphone in use today
is also a PDA, although not commonly called as such.
PDA also stands for "Public Display of Affection," and though this term is all too relevant at college
campuses, it has nothing to do with this definition.
Peripheral = A computer peripheral is any external device that provides input and output for the
computer. For example, a keyboard and mouse are input peripherals, while a monitor and printer are
output peripherals. Computer peripherals, or peripheral devices, are sometimes called "I/O devices"
because they provide input and output for the computer. Some peripherals, such as external hard
drives, provide both input and output for the computer.
Page | 49
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Plug and Play = Plug and Play, sometimes, abbreviated PnP, is a catchy phrase used to describe devices
that work with a computer system as soon as they are connected. The user does not have to manually
install drivers for the device or even tell the computer that a new device has been added. Instead the
computer automatically recognizes the device, loads new drivers for the hardware if needed, and begins
to work with the newly connected device.
For example, if you connect a Plug-and-Play mouse to the USB port on your computer, it will begin to
work within a few seconds of being plugged in. A non plug-and-play device would require you to go
through several steps of installing drivers and setting up the device before it would work.
While Plug and Play usually refers to computer peripheral devices, such as keyboards and mice, it can
also be used to describe internal hardware. For example, a video card or hard drive may be a Plug and
Play device, meaning the computer will recognize it as soon as it is installed. The only difference is that
internal components usually require the computer to be turned off when they are installed, while
external devices can typically be installed while the computer is running.
Power Cycle = While the phrase "power cycle" appears to be a noun, it is actually more commonly used
as a verb. In simple terms, to power cycle a device means to turn it off and turn it back on again. For
example, the user manual of a router may ask you to power cycle the router if it stops responding. This
may mean switching the power to OFF and then ON again or may require physically unplugging the
device and then plugging it back in again. Power cycling is often synonymous with resetting a device.
As we all know, computer equipment can be rather finicky at times. A device that was working fine ten
minutes ago may begin acting strangely or may not be responding at all. Often the low-tech solution of
simply turning off the device and turning it back on again will fix the problem. This is because
information stored in the device's RAM may have gotten corrupted and caused the device to hang up or
stall on a certain instruction. Power cycling the device erases the RAM and allows it to boot up with
fresh information. Typically it is a good idea to wait 5 to 10 seconds before turning the device back on to
make sure it has chance to fully reset. Of course, if you need to power cycle your computer, you should
save any work you currently have open, since it will be erased from the RAM once the system is
restarted.
Power Supply = A power supply is a hardware component that supplies power to an electrical device. It
receives power from an electrical outlet and converts the current from AC (alternating current) to DC
(direct current), which is what the computer requires. It also regulates the voltage to an adequate
amount, which allows the computer to run smoothly without overheating. The power supply an integral
part of any computer and must function correctly for the rest of the components to work.
You can locate the power supply on a system unit by simply finding the input where the power cord is
plugged in. Without opening your computer, this is typically the only part of the power supply you will
see. If you were to remove the power supply, it would look like a metal box with a fan inside and some
cables attached to it. Of course, you should never have to remove the power supply, so it's best to leave
it in the case.
While most computers have internal power supplies, many electronic devices use external ones. For
example, some monitors and external hard drives have power supplies that reside outside the main unit.
These power supplies are connected directly to the cable that plugs into the wall. They often include
Page | 50
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
another cable that connects the device to the power supply. Some power supplies, often called "AC
adaptors," are connected directly to the plug (which can make them difficult to plug in where space is
limited). Both of these designs allow the main device to be smaller or sleeker by moving the power
supply outside the unit.
Since the power supply is the first place an electronic device receives electricity, it is also the most
vulnerable to power surges and spikes. Therefore, power supplies are designed to handle fluctuations in
electrical current and still provide a regulated or consistent power output. Some include fuses that will
blow if the surge is too great, protecting the rest of the equipment. After all, it is much cheaper to
replace a power supply than an entire computer. Still, it is wise to connect all electronics to a surge
protector or UPS to keep them from being damaged by electrical surges.
Print Server = A print server is a device that allows you to share a printer with multiple computers. It
may be a standalone adapter or may be integrated within a printer or a router. When activated, the
print server allows a printer to connect to a local network rather than a single computer. The printer can
then be accessed by multiple devices (including both Mac and Windows computers) as a "network
printer."
Standalone print servers come in several varieties. Most have a USB port, which connects directly to the
USB port of the printer. However, some print servers can connect to a printer's Ethernet or parallel port
as well. Wired print servers include an Ethernet port for connecting directly to a router, while wireless
versions are able to connect to a Wi-Fi network.
Printers that include a built-in print server are often called "network printers" or "wireless printers."
These printers may have an Ethernet port for connecting directly to a LAN or a built-in Wi-Fi card, which
enables the printer to show up on a wireless network. Since many homes and businesses now have
wireless networks, wireless printers have become a popular way to share a printer with multiple
computers.
Some routers can also function as print servers. Besides the typical Ethernet ports, they also include a
USB port for connecting a printer. When you connect a printer to the router, the printer becomes a
network device and can be accessed by other devices on the network.
Printer = A printer is an output device that prints paper documents or converts an open document into
another format. This includes text documents, images, or a combination of both. The two most common
types of printers are inkjet and laser printers. Inkjet printers are commonly used by consumers, while
laser printers are a typical choice for businesses. Dot matrix printers, which have become increasingly
rare, are still used for basic text printing.
The printed output produced by a printer is often called a hard copy, which is the physical version of an
electronic document. While some printers can only print black and white hard copies, most printers
today can produce color prints. In fact, many home printers can now produce high-quality photo prints
that rival professionally developed photos. This is because modern printers have a high DPI (dots per
inch) setting, which allows documents to printed with a very fine resolution.
In order to print a document, the electronic data must be sent from the computer to the printer. Many
software programs, such as word processors and image editing programs, include a "Print..." option in
the File menu. When you select "Print," you will typically presented with a Print dialog box. This box
Page | 51
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
allows you to select the print output settings before sending the document to the printer. After
choosing the appropriate settings, you can hit the Print button, which will send the document to the
printer.
Of course for the document to print, the printer must be turned on and connected to the computer.
Most modern printers are connected using a standard USB cable. However, some printers can be
wirelessly connected to one or more computers over a Wi-Fi network. You can also use more than one
printer on a single computer, as long as the correct drivers are installed.
While printers are notorious for breaking down at inopportune times, modern printers are fortunately
more reliable than the printers of the past. Of course, keeping extra ink or toner cartridges on hand is
still your responsibility.
Processor = A processor, or "microprocessor," is a small chip that resides in computers and other
electronic devices. Its basic job is to receive input and provide the appropriate output. While this may
seem like a simple task, modern processors can handle trillions of calculations per second.
The central processor of a computer is also known as the CPU, or "central processing unit." This
processor handles all the basic system instructions, such as processing mouse and keyboard input and
running applications. Most desktop computers contain a CPU developed by either Intel or AMD, both of
which use the x86 processor architecture. Mobile devices, such as laptops and tablets may use Intel and
AMD CPUs, but can also use specific mobile processors developed by companies like ARM or Apple.
Modern CPUs often include multiple processing cores, which work together to process instructions.
While these "cores" are contained in one physical unit, they are actually individual processors. In fact, if
you view your computer's performance with a system monitoring utility like Windows Task Manager
(Windows) or Activity Monitor (Mac OS X), you will see separate graphs for each processor. Processors
that include two cores are called dual-core processors, while those with four cores are called quad-core
processors. Some high-end workstations contain multiple CPUs with multiple cores, allowing a single
machine to have eight, twelve, or even more processing cores.
Besides the central processing unit, most desktop and laptop computers also include a GPU. This
processor is specifically designed for rendering graphics that are output on a monitor. Desktop
computers often have a video card that contains the GPU, while mobile devices usually contain a
graphics chip that is integrated into the motherboard. By using separate processors for system and
graphics processing, computers are able to handle graphic-intensive applications more efficiently.
PS/2 = PS/2 is a type of port used by older computers for connecting input devices such as keyboards
and mice. The port was introduced with IBM's Personal System/2 computer in 1987 (which was
abbreviated "PS/2"). In the following years, the PS/2 port became the standard connection for
keyboards and mice in all IBM compatible computers.
The PS/2 port has six pins and is roughly circular in shape. Since each PS/2 port is designed to accept a
specific input, the keyboard and mouse connections are typically color-coded. For example, the
keyboard port on the back of the computer is often purple, while the mouse port is usually green.
Similarly, the connector on the end of the keyboard cord is purple and the mouse cord connector is
green. This makes it easy for all users to know where to plug the cables into the computer. The concept
Page | 52
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
is similar to the color-coded composite audio/video connections on the back of a TV, which use red,
white, and yellow connectors.
While the PS/2 port enjoyed a good run for almost two decades, now most keyboards and mice use USB
connectors. Unlike PS/2 ports, USB devices can be plugged into any USB port or even a USB hub and the
computer will automatically determine what the device is. USB is also "hot swappable," meaning the
connections can be removed while the computer is running. If you remove a PS/2 device while the
computer is on, it may potentially cause damage to the hardware. Therefore, if you are using a PS/2
device, it is best to turn off the computer before connecting or unplugging a keyboard or mouse.
NOTE: The term "PS2" is also a common abbreviation for Sony's PlayStation 2 game console.
Quad-Core = See Multiprocessing
RAM = See Memory
Repeater = A repeater is an electronic device that relays a transmitted signal. It receives a signal on a
specific frequency, then amplifies and rebroadcasts it. By amplifying the signal, a repeater increases the
transmission range of the original signal.
Repeaters have many applications, but in computing they are most commonly used in wireless
networks. For example, a Wi-Fi network in a large home may benefit from using one or more repeaters
to relay the signal to different areas of the house. Homes that have brick walls or cement floors may also
benefit from having a repeater relay the signal around the obstacle. Businesses often use a series of
repeaters to create a single wireless network within a large building.
While repeaters all serve the same purpose, they come in many forms. Some wireless devices, often
called "range extenders" are designed to be used specifically as repeaters. Other devices, such as hubs,
switches, and routers can all be configured as repeaters using a software utility or web interface that
controls the wireless device.
NOTE: Since repeaters only relay an incoming signal, using a router as a repeater does not make use of
its signal routing capability. Therefore, it make more sense to use a range extender as a repeater if
possible.
Retina Display = The term "retina display" is a hardware term coined by Apple in June, 2010. It describes
a display that has a resolution of over 300 dpi. The iPhone 4, which was also announced in June, 2010,
has a screen resolution of 326 dpi and was the first Apple product to include a retina display.
The name "retina display" refers to way the high-resolution display appears to the human eye. When a
display has a resolution over 300 dpi, most humans cannot recognize individual pixels when viewing the
screen from a distance of about 12 inches. Therefore, the pixels seem to run together, creating a
smooth appearance. This is similar to digital audio that is recorded with a high sampling rate. Since the
audio samples are so close together, we perceive the sound as a smooth analog signal.
Since some people have better vision than others, there is no scientifically accurate number that defines
a retina display. In fact, some people may in fact be able to identify individual pixels in a retina display.
Still, compared to a typical computer monitors, which has a resolution of 72 dpi, a retina display will look
noticeably sharper to all users.
Page | 53
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Retina displays are especially useful for reading text on a small screen, such as an iPhone or iPod Touch.
The increased resolution makes small text legible and medium-sized text easier to read. As display
technology continues to evolve, retina displays are expected to be made available in larger devices, such
as the iPad and HiDPI monitors.
RFID = Stands for "Radio-Frequency Identification." RFID is a system used to track objects, people, or
animals using tags that respond to radio waves. RFID tags are integrated circuits that include a small
antenna. They are typically small enough that they are not easily noticeable and therefore can be placed
on many types of objects.
Like UPC labels, RFID tags are often used to uniquely identify the object they are attached to. However,
unlike UPCs, RFID tags don't need to be scanned directly with a laser scanner. Instead, they can be
recorded by simply placing the tag within the range of an RFID radio transmitter. This makes it possible
to quickly scan several items or to locate a specific product surrounded by many other items.
RFID tags have many different uses. Some examples include:








Merchandise tags - These tags are attached to clothing, electronics, and other products to
prevent theft from retail stores. These tags are typically deactivated at the place of checkout.
Tags that have not been deactivated will sound the alarm system near the store's exit.
Inventory management - Products stored in warehouses may be given RFID tags so they can be
located more easily.
Airplane luggage - RFID tags may be placed on checked bags so they can be easily tracked and
located.
Toll booth passes - E-ZPass and I-Pass receivers may be placed in automobiles, allowing cars and
trucks to pass through toll booths without needing to stop. This enables drivers to make toll
payments automatically.
Credit cards - Some credit cards have built-in RFIDs so they can be "waved" rather than "swiped"
near compatible readers. The SpeedPass wand is an example of an RFID-only payment device.
Animal tags - RFID tags can be placed pet collars to make help identify pets if they are lost. Tags
may also be placed on birds and other animals to help track them for research purposes.
Library Content Management – placed on the inside cover of books, DVD’s and other Library
materials to manage inventory.
Companies are requesting employees to get “Chipped”-instead of using a card to gain access to
facilities you get a RFID chip inserted under your skin!
The above list includes just a few of the applications of radio-frequency identification. There are many
other existing and potential applications for RFID tags as well.
ROM = Stands for "Read-Only Memory." Please do not confuse this term with RAM or a hard drive, as
many people already do. ROM is memory containing hardwired instructions that the computer uses
when it boots up, before the system software loads. In PCs, the instructions are read from a small
program in the ROM, called the BIOS (Basic Input/Output System).
ROUTER = See Gateway
SATA = Stands for "Serial Advanced Technology Attachment," or "Serial ATA." It is an interface used to
connect ATA hard drives to a computer's motherboard. SATA transfer rates start at 150MBps, which is
Page | 54
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
significantly faster than even the fastest 100MBps ATA/100 drives. For this and other reasons, Serial ATA
is likely to replace the previous standard, Parallel ATA (PATA), which has been around since the 1980s.
Besides faster transfer rates, the SATA interface has several advantages over the PATA interface. For
one, SATA drives each have their own independent bus, so there is no competition for bandwidth like
there is with Parallel ATA. They also use smaller, thinner cables, which allows for better airflow inside
the computer. SATA cables can be as long as one meter, while PATA cables max out at 40cm. This gives
manufacturers more liberty when designing the internal layout of their computers. Finally, Serial ATA
uses only 7 conductors, while Parallel ATA uses 40. This means there is less likely to be electromagnetic
interference with SATA devices.
In summary, Serial ATA is a better, more efficient interface than the dated PATA standard. If you are
looking to buy a computer that will support fast hard drives for years to come, make sure it comes with
a SATA interface.
Scanner = A scanner is an input device that scans documents such as photographs and pages of text.
When a document is scanned, it is converted into a digital format. This creates an electronic version of
the document that can be viewed and edited on a computer.
Most scanners are flatbed devices, which means they have a flat scanning surface. This is ideal for
photographs, magazines, and various documents. Most flatbed scanners have a cover that lifts up so
that books and other bulky objects can also be scanned. Another type of scanner is a sheet-fed scanner,
which can only accept paper documents. While sheet-fed scanners cannot scan books, some models
include an automatic document feeder, or ADF, which allows multiple pages to be scanned in sequence.
Scanners work in conjunction with computer software programs, which import data from the scanner.
Most scanners include basic scanning software that allows the user to configure, initiate, and import
scans. Scanning plug-ins can also be installed, which allow various software programs to import scanned
images directly. For example, if a scanner plug-in is installed for Adobe Photoshop, a user can create
new images in Photoshop directly from the connected scanner.
While Photoshop can edit scanned images, some programs like Acrobat and OmniPage can actually
recognize scanned text. This technology is called optical character recognition, or OCR. Scanning
software that includes OCR can turn a scanned text document into a digital text file that can be opened
and edited by a word processor. Some OCR programs even capture page and text formatting, making it
possible to create electronic copies of physical documents.
Scroll Wheel = Computer windows are often not large enough to display the entire contents of the
window at one time. Therefore, you may need to scroll through the window to view all the contents.
Traditionally, this has been done by clicking and dragging the slider within the scroll bar. However, many
mice now come with scroll wheels that make the scrolling process even easier.
The scroll wheel typically sits between the left and right buttons on the top of a mouse. It is raised
slightly, which allows the user to easily drag the wheel up or down using the index finger. Pulling the
scroll wheel towards you scrolls down the window, while pushing it away scrolls up. Most modern mice
include a scroll wheel, since it eliminates the need to move the cursor to the scroll bar in order to scroll
through the window. Therefore, once you get accustomed to using a scroll wheel, it can be pretty
difficult to live without.
Page | 55
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Most scroll wheels only allow the user to scroll up and down. However, some programs allow the user to
use a modifier key, such as Control or Shift, to change the scrolling input to left and right. Some mice
even have a tilting scroll wheel that allows the user to scroll left and right. The Apple Mighty Mouse has
a spherical scrolling mechanism (called a scroll ball) that allows the user to also scroll left and right and
even diagonally. Whatever the case, any type of scroll wheel is certainly better than nothing.
SCSI = stands for "Small Computer System Interface," and is pronounced "scuzzy." SCSI is a computer
interface used primarily for high-speed hard drives. This is because SCSI can support faster data transfer
rates than the commonly used IDE storage interface. SCSI also supports daisy-chaining devices, which
means several SCSI hard drives can be connected to single a SCSI interface, with little to no decrease in
performance. While SCSI is still used for some high-performance equipment, newer interfaces have
largely replaced SCSI in certain applications. For example, Firewire and USB 2.0 have become commonly
used for connecting external hard drives. Serial ATA, or SATA, is now used as a fast interface for internal
hard drives.
SD = Stands for "Secure Digital." It is a type of memory card used for storing data in devices such as
digital cameras, PDAs, mobile phones, portable music players, and digital voice recorders. The card is
one of the smaller memory card formats, measuring 24mm wide by 32mm long and is just 2.1mm thick.
To give the cards some orientation, the top-rght corner of each SD card is slanted. Even though the cards
are extremely small, as of late 2004, they can hold up to 8GB of data.
Part of the reason the cards are called "Secure Digital" cards is because the cards have a copyright
protection feature built in. The security feature, called "key revocation" means protected data on the
card can only be read by specific devices. The cards can have both secured and unsecured areas on them
for copyrighted and non-copyrighted data. For more information on SD cards, visit the SD Card
Association.
Serial Port = The serial port is a type of connection on PCs that is used for peripherals such as mice,
gaming controllers, modems, and older printers. It is sometimes called a COM port or an RS-232 port,
which is its technical name. If that's not enough to confuse you, there are two types of serial ports -DB9 and DB25. DB9 is a 9-pin connection, and DB25 is, you guessed it, a 25-pin connection.
A serial port can only transmit one bit of data at a time, whereas a parallel port can transmit many bits
at once. The serial port is typically the slowest port you'll find on a PC, if you find one at all. Most newer
computers have replaced serial ports with much faster and more compatible USB ports.
Server = A server is a computer that provides data to other computers. It may serve data to systems on
a local area network (LAN) or a wide area network (WAN) over the Internet.
Many types of servers exist, including web servers, mail servers, and file servers. Each type runs
software specific to the purpose of the server. For example, a Web server may run Apache HTTP Server
or Microsoft IIS, which both provide access to websites over the Internet. A mail server may run a
program like Exim or iMail, which provides SMTP services for sending and receiving email. A file server
might use Samba or the operating system's built-in file sharing services to share files over a network.
While server software is specific to the type of server, the hardware is not as important. In fact, a
regular desktop computers can be turned into a server by adding the appropriate software. For
Page | 56
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
example, a computer connected to a home network can be designated as a file server, print server, or
both.
While any computer can be configured as a server, most large businesses use rack-mountable hardware
designed specifically for server functionality. These systems, often 1U (less than 2”) in size, take up
minimal space and often have useful features such as LED status lights and hot-swappable hard drive
bays. Multiple rack-mountable servers can be placed in a single rack and often share the same monitor
and input devices. Most servers are accessed remotely using remote access software, so input devices
are often not even necessary.
While servers can run on different types of computers, it is important that the hardware is sufficient to
support the demands of the server. For instance, a web server that runs lots of web scripts in real-time
should have a fast processor and enough RAM to handle the "load" without slowing down. A file server
should have one or more fast hard drives or SSDs that can read and write data quickly. Regardless of the
type of server, a fast network connection is critical, since all data flows through that connection.
SIM Card = Stands for "Subscriber Identification Module Card." A SIM card is a small removable chip that
identifies a mobile device on a cellular network. It contains an integrated circuit that stores a unique
identifier called an "international mobile subscriber identity" (IMSI) number and other information
specific to the mobile carrier.
A SIM card or an embedded SIM is required in order for any cell phone, smartphone, or tablet to be
used on a cellular network. When you activate a cell phone, the cellular provider links your phone
number to your SIM card, which allows you to make receive calls and access cellular data. If you replace
your SIM card or a get a new phone with a new SIM card, the new SIM identifier must be linked to your
account in order for your mobile device to be recognized on the network.
SIM cards have been standardized in increasingly smaller sizes since the first SIM card was used in 1991.
Below are several SIM card formats.




Full size (1991) - 85.6 x 53.98 mm x 0.76 mm
Mini-SIM (1996) - 25 x 15 mm x 0.76 mm
Micro-SIM (2003) - 15 x 12 mm x 0.76 mm
Nano-SIM (2012) - 12.3 x 8.8 mm x 0.67 mm
Cellular devices are designed to work with a specific SIM card format so if you need to replace your SIM
card, it is important to verify the correct size with your cellular provider.
Removing a SIM card is usually pretty simple. Some devices, like the iPhone, have a SIM card tray that
pops out from the side of the device. You can open the tray by pressing the access hole with a paperclip.
Other devices, such as the Samsung Galaxy, require you to remove the back cover and battery to access
the SIM card. You can remove and replace the SIM card without powering down your device.
SLI = Stands for "Scalable Link Interface." SLI is a technology developed by NVIDIA that allows multiple
graphics cards to work together in a single computer system. This enables faster graphics performance
than what is possible with a single card. For example, using SLI to link two cards together may offer up
to twice the performance of a single video card. If each card has two GPUs, the result may be up to four
times the performance of a typical video card!
Page | 57
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
For video cards to be linked using NVIDIA's SLI system, the computer must have multiple PCI Express
slots. PCI Express is the first video card interface that allows the linking of multiple graphics cards
because the slots share the same bus. Previous technologies, such as PCI and AGP, used separate buses,
which did not allow graphics cards to be bridged together. The PCI Express slots must also support
enough bandwidth for the cards, which typically means they must be x8 or x16 slots. Of course, the
cards themselves must also support SLI bridging in order to work together.
Smartphone = A smartphone is a mobile phone that includes advanced functionality beyond making
phone calls and sending text messages. Most smartphones have the capability to display photos, play
videos, check and send e-mail, and surf the Web. Modern smartphones, such as the iPhone and Android
based phones can run third-party applications, which provides limitless functionality.
While smartphones were initially used mostly by business users, they have become a common choice
for consumers as well. Thanks to advancements in technology, modern smartphones are smaller and
cheaper than earlier devices. Users also have a much wider range of smartphones to choose from than
before. While the RIM Blackberry dominated the smartphone market for many years, other
manufacturers like Apple, HTC, and Samsung now offer a wide variety of smartphone options as well.
This increase in smartphone availability has led to a corresponding decline in the usage of standard
PDAs, which do not include phone capabilities.
Since smartphones have a wide range of functionality, they require advanced software, similar to a
computer operating system. The smartphone software handles phone calls, runs applications, and
provides configuration options for the user. Most smartphones include a USB connection, which allows
users to sync data with their computers and update their smartphone software.
Solid State = Solid state, at its most basic level, means "no moving parts." Therefore, solid state
electronic devices are made up of solid components that do not move. Some examples include
computer motherboards and integrated circuits. Devices that use only solid state parts, such as
television sets, speakers, and digital watches, are often referred to as solid state products.
Flash memory devices are solid state products, while hard drives are not. This is because hard drives use
a spinning disk and moving drive head to read and write data, while flash memory uses electric charges
to perform the same functions. For this reason, flash memory devices are seen as more durable than
hard drives. This is why flash memory is often used in products such as portable MP3 players and digital
cameras.
Because solid state devices have no moving parts, they are less likely to break down than devices that
have mobile mechanisms. For this reason, it is often more worthwhile to buy an extended warranty on
electronics that have moving parts than those that do not. That is something you may want to think
about next time you are shopping.
Sound Card = The sound card is a component inside the computer that provides audio input and output
capabilities. Most sound cards have at least one analog line input and one stereo line output connection.
The connectors are typically 3.5 mm minijacks, which are the size most headphones use. Some sound
cards also support digital audio input and output, either through a standard TRS (tip-ring-sleeve)
connection or via an optical audio port, such as Toslink connector.
Page | 58
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
While there are many types of sound cards, any type that produces an analog output must include a
digital-to-analog converter (DAC). This converts the outgoing signal from digital to analog, which can be
played through most speaker systems. Sounds cards that support analog input also require an analog-todigital converter (ADC). This digitizes the incoming analog signal, so the computer can process it.
In some computers, the sound card is part of the motherboard, while other machines may have an
actual card that reside in a PCI slot. If you want to more audio capabilities to your computer, such as
additional input or output channels, you can install a new sound card. Professional sound cards often
support higher sampling rates (such as 192 kHz instead of 44.1 kHz) and may have more inputs and
outputs. Some cards may also have 1/4 in. connectors instead of 3.5 mm, which accommodates most
instrument outputs.
While professional sound cards can add more audio capabilities to your computer, another popular
option for multi-channel recording is a breakout box. This is an external box that typically includes a
built-in sound card and multiple audio connections. For example, a breakout box may support 16
channels of audio, which would be impossible to fit on a single card. Most breakout boxes connect to a
Firewire or USB port, though some connect to a sound card specifically designed to communicate with
the box.
Southbridge = The southbridge is a chip that connects the northbridge to other components inside the
computer, including hard drives, network connections, USB and Firewire devices, the system clock, and
standard PCI cards. The southbridge sends and receives data from the CPU through the northbridge
chip, which is connected directly to the computer's processor.
Since the southbridge is not connected directly to the CPU, it does not have to run as fast as the
northbridge chip. However, it processes data from more components, so it must be able to multitask
well. On Intel systems, the southbridge is also referred to as the I/O Controller Hub, since it controls the
input and output devices.
Speakers = Speakers are one of the most common output devices used with computer systems. Some
speakers are designed to work specifically with computers, while others can be hooked up to any type of
sound system. Regardless of their design, the purpose of speakers is to produce audio output that can
be heard by the listener.
Speakers are transducers that convert electromagnetic waves into sound waves. The speakers receive
audio input from a device such as a computer or an audio receiver. This input may be either in analog or
digital form. Analog speakers simply amplify the analog electromagnetic waves into sound waves. Since
sound waves are produced in analog form, digital speakers must first convert the digital input to an
analog signal, then generate the sound waves.
The sound produced by speakers is defined by frequency and amplitude. The frequency determines how
high or low the pitch of the sound is. For example, a soprano singer's voice produces high frequency
sound waves, while a bass guitar or kick drum generates sounds in the low frequency range. A speaker
system's ability to accurately reproduce sound frequencies is a good indicator of how clear the audio will
be. Many speakers include multiple speaker cones for different frequency ranges, which helps produce
more accurate sounds for each range. Two-way speakers typically have a tweeter and a mid-range
speaker, while three-way speakers have a tweeter, mid-range speaker, and subwoofer.
Page | 59
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Amplitude, or loudness, is determined by the change in air pressure created by the speakers' sound
waves. Therefore, when you crank up your speakers, you are actually increasing the air pressure of the
sound waves they produce. Since the signal produced by some audio sources is not very high (like a
computer's sound card), it may need to be amplified by the speakers. Therefore, most external
computer speakers are amplified, meaning they use electricity to amplify the signal. Speakers that can
amplify the sound input are often called active speakers. You can usually tell if a speaker is active if it has
a volume control or can be plugged into an electrical outlet. Speakers that don't have any internal
amplification are called passive speakers. Since these speakers don't amplify the audio signal, they
require a high level of audio input, which may be produced by an audio amplifier.
Speakers typically come in pairs, which allows them to produce stereo sound. This means the left and
right speakers transmit audio on two completely separate channels. By using two speakers, music
sounds much more natural since our ears are used to hearing sounds from the left and right at the same
time. Surround systems may include four to seven speakers (plus a subwoofer), which creates an even
more realistic experience
Supercomputer = As the name implies, a supercomputer is no ordinary computer. It is a high
performance computing machine designed to have extremely fast processing speeds. Supercomputers
have various applications, such as performing complex scientific calculations, modeling simulations, and
rendering large amounts of 3D graphics. They may also be built to simply showcase the leading edge of
computing technology.
If you are hoping to have a supercomputer on your desk, you may be out of luck. Supercomputers are
typically several times the size of a typical desktop computer and require far more power. A
supercomputer may also consist of a series of computers, which may fill an entire room. Examples of
single machine supercomputers include the early Cray-1 and Cray X-MP systems developed by Cray
Research as well as the more recent Blue Gene and Roadrunner systems developed by IBM. System X is
an example of a multi-system supercomputer, which was developed by Virginia Tech and is comprised of
1,100 Apple Xserve G5s.
Supercomputers cost a fortune to build and are expensive to maintain, which is why only a few exist in
the entire world. Furthermore, computing power continues to advance each year, meaning it isn't too
long before a ground-breaking supercomputer isn't so super. The good news is that the supercomputers
of the past eventually become the personal computers of today. Therefore, your home PC most likely
has more computing power than many supercomputers from previous decades. Now that's super cool.
Surge Protector = The surge protector is an important, yet often overlooked part of a computer setup. It
allows multiple devices to plugged in to it at one time and protects each connected device from power
surges. For example, a home office may have a computer, monitor, printer, cable modem, and powered
speakers all plugged into one surge protector, which is plugged into a single outlet in the wall. The surge
protector allows many devices to use one outlet, while protecting each of them from electrical surges.
Surge protectors, sometimes called power strips, prevent surges in electrical current by sending the
excess current to the grounding wire (which is the round part of the plug below the two flat metal
pieces on U.S. outlet plugs). If the surge is extra high, such as from a lightning strike, a fuse in the surge
protector will blow and the current will prevented from reaching any of the devices plugged into the
Page | 60
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
surge protector. This means the noble surge protector will have given its life for the rest of the
equipment, since the fuse is destroyed in the process.
While surge protectors all perform the same basic function, they come in many shapes and sizes with
different levels of protection. Some may look like basic power strips, while others may be rack mounted
or fit directly against the wall. Most surge protectors offer six to ten different outlets. Cheaper surge
protectors offer limited protection for surges (under 1000 joules), while more expensive ones offer
protection for several thousand joules and include a monetary guarantee on connected devices if a
power surge happens. Typically, you get what you pay for, so if you have an expensive computer system,
it is wise to buy a quality surge protector that offers at least 1000 joules of protection.
Some surge protectors also include line conditioning, which uses an electromagnet to maintain a
consistent level of electricity when there are slight variations in current. For example, you might notice
your computer monitor or television fade for a moment when you turn on a high-powered device, like a
vacuum or air conditioner. A surge protector with line conditioning should prevent connected devices
from being affected by these slight variances in current.
While you may be able to hook up your computer system without a surge protector, it is important to
protect your equipment by using one. You may not need a large, expensive surge protector with line
conditioning, but using a quality surge protector for all your electronic devices is a smart choice
Switch = A switch is used to network multiple computers together. Switches made for the consumer
market are typically small, flat boxes with 4 to 8 Ethernet ports. These ports can connect to computers,
cable or DSL modems, and other switches. High-end switches can have more than 50 ports and often are
rack mounted.
Switches are more advanced than hubs and less capable than routers. Unlike hubs, switches can limit
the traffic to and from each port so that each device connected to the switch has a sufficient amount of
bandwidth. For this reason, you can think of a switch as a "smart hub." However, switches don't provide
the firewall and logging capabilities that routers do. Routers can often be configured by software
(typically via a Web interface), while switches only work the way the hardware was designed.
The term "switch" can also be used to refer to a small lever or button on computer hardware. And while
it has nothing to do with computers, "riding switch" means riding backwards in skateboarding and
snowboarding.
System Requirements = Whenever you purchase software or hardware for your computer, you should
first make sure your computer supports the system requirements. These are the necessary specifications
your computer must have in order to use the software or hardware. For example, a computer game may
require you computer to have Windows XP or later, a 2.0 GHz processor, 512 MB or RAM, a 64 MB
graphics card, and 500 MB or hard drive space. If your computer does not meet all of these
requirements, the game will not run very well or might not run at all.
It is just as important to check system requirements for hardware devices. For example, if you buy a
printer, it may require either Windows XP or Mac OS X 10.3 or later. It may also require a USB port and
80 MB of available hard drive space. If your computer does not have any USB ports, you will not be able
to physically connect the printer. If your machine does not have Windows XP or Mac OS X 10.3 or later,
Page | 61
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
the printer drivers may be incompatible with your operating system. This means you computer will be
unable to recognize the printer.
Most hardware and software products have the system requirements printed on the side or bottom of
the product packaging. When you are shopping for computer software or hardware, it is a good idea to
first find out exactly what your system's specifications are and write them down on a piece of paper. The
important information to record includes:






Operating System (i.e. Windows XP, SP 2 or Mac OS X 10.3.8)
Processor Speed (i.e. Pentium 4, 3.2 GHz or Power PC G5, 2.0 GHz)
Memory, a.k.a. RAM (i.e. 512 MB)
Graphics Card (i.e. ATI Radeon 9800 w/ 256 MB video memory)
Hard Disk Space (i.e. 80 GB available)
I/O Ports (i.e. USB, Firewire, Serial, Parallel, SCSI, VGA, DVI ports)
By recording these specifications from your computer, you will be able to make sure your computer
supports the products you are buying.
System Unit = The system unit, also known as a "tower" or "chassis," is the main part of a desktop
computer. It includes the motherboard, CPU, RAM, and other components. The system unit also
includes the case that houses the internal components of the computer.
The term "system unit" is often used to differentiate between the computer and peripheral devices,
such as the monitor, keyboard, and mouse. For example, if a repair shop asks you to bring in your
computer, it may be unclear whether you need to bring your monitor and peripheral devices as well. If
you are told to just bring your system unit, it is clear you only need to bring the computer itself.
Some modern computers, such as the iMac, combine the system unit and monitor into a single device.
In this case, the monitor is part of the system unit. While laptops also have built-in displays, they are not
called system units, since the term only refers to desktop computers.
Tablet = A tablet, or tablet PC, is a portable computer that uses a touchscreen as its primary input
device. Most tablets are slightly smaller and weigh less than the average laptop. While some tablets
include fold out keyboards, others, such as the Apple iPad and Motorola Xoom, only offer touchscreen
input.
Early tablet touchscreens were designed to work with light pens, but most modern tablets support
human touch input. Many tablets now support multitouch input, which allows you to perform gestures
with multiple fingers, such as pinching an image to zoom out, or spreading your fingers apart to zoom in.
Tablets without physical keyboards allow you to enter text using a pop-up keyboard that appears on the
screen.
Since tablets do not use a traditional keyboard and mouse as their primary forms of input, the user
interface of a tablet is different than a typical laptop. For example, instead of double-clicking to open a
program, most applications open with a single tap. Instead of clicking on a scroll bar to scroll through a
window, most tablet applications allow you to swipe up and down anywhere within a window to scroll
through the content.
Page | 62
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Since tablet PCs provide a different interface than traditional computers, they offer unique possibilities
for graphics applications, games, and other programs. Because of their small form factor, they are
extremely portable and can be easily stowed in a backpack or a briefcase. Still, because tablets lack a
keyboard and mouse, some tasks such as typing documents and writing email messages, are more
difficult on tablets than traditional computers. Therefore, tablets are generally seen as accessories to
laptops and desktop computers rather than replacements.
Tape Drive = This is a removable storage device mainly used for backing up data. It is similar to a Zip
Drive, but instead of Zip disks, it uses small tapes. The drive acts like a tape recorder, reading data from
the computer and writing it onto the tape. Since tape drives have to scan through lots of tape to read
small amounts of scattered data, they are not practical for most storage purposes. That is why they are
used almost exclusively for data backup. The benefit of tape drives is that they typically have large
capacities for storing data, for a lower cost than hard drives similar in size. Also, multiple tapes can be
used to make incremental backups (daily, weekly, monthly, etc.), which is much cheaper than using
multiple hard drives.
Thin Client = In the 1950s, minimalism emerged as an popular art movement. In the 1990s, minimalism
emerged again as a popular computer trend. As computer networking became more commonplace,
minimalist computers became more common as well. In fact, these trimmed-down machines, often
referred to as thin clients, are still popular today.
Thin clients function as regular PCs, but lack hard drives and typically do not have extra I/O ports or
other unnecessary features. Since they do not have hard drives, thin clients do not have any software
installed on them. Instead, they run programs and access data from a server. For this reason, thin clients
must have a network connection and are sometimes referred to as "network computers" or "NCs."
Thin clients can be a cost-effective solution for businesses or organizations that need several computers
that all do the same thing. For example, students in a classroom could all run the same program from a
server, each using his own thin client machine. Because the server provides the software to each
computer on the network, it is not necessary for each NC to have a hard drive. Thin clients also make it
easier to manage computer networks since software issues need to be managed only on the server
instead of on each machine.
Thunderbolt = a high-speed I/O interface that was developed by Intel and was introduced by Apple in
2011. It is based on the PCI Express and DisplayPort technologies and supports both data devices and
displays. Since Thunderbolt is based on the PCI Express architecture, external devices connected via
Thunderbolt can achieve performance that was previously only possible from internal components.
Additionally, the Thunderbolt interface offers 10 Gpbs of throughput in both directions. That is more
than 12 times as fast as Firewire 800 and over 20 times faster than USB 2.0. While a FireWire 800
interface can only support one stream of 720p video, a Thunderbolt interface can support 8
simultaneous 720p video streams.
Like USB and FireWire, Thunderbolt can provide power to connected peripheral devices. That means
external devices that require 10 watts of power or less can be powered directly from the Thunderbolt
port. Additionally, simple adapters can be used to connect USB, FireWire, and Ethernet devices to a
Thunderbolt port.
Page | 63
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
While Thunderbolt is primarily used as a high-speed data interface, it can also be used to connect highresolution displays. The Thunderbolt interface is physically identical to the Mini-DisplayPort interface
and therefore can be used to connect a DisplayPort monitor. Like HDMI, DisplayPort supports both
audio and video, eliminating the need for a separate audio cable.
Thunderbolt devices can be daisy-chained, meaning multiple devices can be connected in sequence to a
single Thunderbolt port. For example, you can connect a Thunderbolt display to a computer and a
Thunderbolt external hard drive to the display. You could also connect a second Thunderbolt monitor to
the first display. This means you can connect two external displays to a laptop, as long as the laptop
supports the resolution required for two screens.
Touchscreen = A touchscreen is a display that also serves as an input device. Some touchscreens require
a proprietary pen for input, though most modern touchscreens detect human touch. Since touchscreen
devices accept input directly through the screen, they do not require external input devices, such as
mice and keyboards. This makes touchscreens ideal for computer kiosks, as well as portable devices,
such as tablets and smartphones.
While a touchscreen may look like an ordinary display, the screen includes several extra layers that
detect input. The first layer is a hard protective layer that protects the actual display and the
touchscreen components. Beneath the protective layer is an electronic grid that detects input. Most
modern touchscreens use capacitive material for this grid, in which the electrical charge changes
wherever the screen is touched. Beneath the touchscreen layer is the LCD layer, which is used for the
actual display.
While early touchscreens could only detect a single point of input at a time, modern touchscreens
support "multi-touch" input. This technology, which was made popular by the original iPhone, enables
the screen to detect multiple finger motions at once. For example, on some touchscreen devices, you
can rotate an image by twisting three fingers in a clockwise or counterclockwise motion. Many
touchscreen applications also allow you zoom in and out by spreading two fingers apart or pinching
them together.
Thanks to multi-touch and other improvements in touchscreen technology, today's touchscreens are
easier and more natural to use than they used to be. In fact, improved touchscreen technology has
greatly contributed to the popularity of the iPad and other tablet PCs.
Trackball = A trackball is an input device used to enter motion data into computers or other electronic
devices. It serves the same purpose as a mouse, but is designed with a moveable ball on the top, which
can be rolled in any direction. Instead of moving the whole device, you simply roll the moveable ball on
top of the trackball unit with your hand to generate motion input.
Trackballs designed for computers generally serve as mouse replacements and are primarily used to
move the cursor on the screen. Like mice, computer trackball devices also include buttons, which can
serve as left-click and right-click buttons, and may also be used to enter other commands. While
trackballs are most commonly used with computers, they may also be found in other electronics, such as
arcade games, mixing boards, and self-serve kiosks. These devices often have trackballs that are larger
than the ones used in computer input devices.
Page | 64
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Besides the capability to be built into various devices, trackballs have a number of other advantages
over mice. Some advantages include the small footprint (since they don't require a mousepad or large
area to move the mouse), fingertip control (which may offer more accuracy), and improved ergonomics
(since there is less strain on the wrist). Still, many people find trackballs harder to use than mice, since
they feel less natural and may require practice to get used to. For this reason, the vast majority of
computers include a mouse, rather than a trackball, as the default input device.
Ultra DMA = This technology for transferring data between a computer's hard disk and memory was
developed by Quantum and Intel. The maximum burst rate of an Ultra DMA hard drive is 33.3 MBps. The
original DMA (Direct Memory Access) protocol could only transfer data at half that speed.
Thanks to Ultra DMA, programs can open faster and run more smoothly. This is because Utlra DMA can
send more data to the memory in less time than the original DMA. Ultra DMA also has a built-in utility
called Cyclical Redundancy Checking (CRC) that helps protect data integrity. So if you want a nice, fast
hard drive, look for one that supports Ultra DMA.
UPnP = Stands for "Universal Plug and Play." Plug and Play describes devices that work with a computer
system as soon as they are connected. UPnP is an extension of this idea that expands the range of Plug
and Play devices to networking equipment. Universal Plug and Play uses network protocols to allow a
wide range of devices to be interconnected and work seamlessly with each other.
UPnP devices can be connected via wired (i.e. Ethernet and Firewire) or wireless (i.e. Wi-Fi and
Bluetooth) connections. As long as a product supports UPnP, it can communicate with other UPnP
devices within a network. The connections are typically created using the DHCP networking protocol,
which assigns each connected device a unique IP address.
While UPnP is helpful for setting up networks, it also can be used to set up compatible audio and video
(AV) devices. UPnP AV is a group of standards based on UPnP that allows audio and video components
to be connected via network connections. This enables media files and streaming data to be sent
between devices. For example, a movie stored on a hard drive in a bedroom could be played back on the
TV screen in the living room. The central controller of a UPnP AV network is called a MediaServer and
can be run from a Macintosh, Windows, or Linux computer or from a hardware device specifically
designed to manage the network.
Since most UPnP devices support zero-configuration setup (like ordinary Plug and Play devices), it is
simple to add devices to a network and use them immediately. While the networking terms associated
with UPnP can be a bit intimidating, setting up a UPnP network is meant to be hassle-free ? and that is a
term we can all appreciate.
UPS = Stands for "Uninterruptible Power Supply." In the technology world, UPS is more than just a
brown shipping company. It is also a type of power supply that uses battery backup to maintain power
during unexpected power outages.
A typical consumer UPS is a surge protector that contains a high-capacity rechargeable battery. Smaller
UPS devices look like bulky power strips, while larger ones may stand upright and look almost like small
computers. Many businesses use uninterruptible power supplies to keep their equipment running in
case of a power failure. While a UPS may only keep a computer running for 15 minutes after the power
is lost, it is usually sufficient time to save all necessary documents and properly shut down the
Page | 65
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
computer. That extra time can be invaluable to someone who is working on an important document or
project that has not been recently saved.
Because UPS devices run the power through a battery, they have a limit on the wattage load they can
support. The maximum power load limit is often included in the name of the UPS, followed by the
letters "VA." For example, the APC (American Power Conversion) Battery Backup 750VA has a load limit
of 750VA. However, the maximum wattage a UPS supports is typically 60% of the VA number. So the
750VA UPS supports a maximum of 450 watts for connected devices. It is important to check how many
total watts your computer setup uses before buying a UPS to make sure you get one with enough
wattage so you don't overload it.
USB = Stands for "Universal Serial Bus." USB is the most common type of computer port used in today's
computers. It can be used to connect keyboards, mice, game controllers, printers, scanners, digital
cameras, and removable media drives, just to name a few. With the help of a few USB hubs, you can
connect up to 127 peripherals to a single USB port and use them all at once (though that would require
quite a bit of dexterity).
USB is also faster than older ports, such as serial and parallel ports. The USB 1.1 specification supports
data transfer rates of up to 12Mb/sec and USB 2.0 has a maximum transfer rate of 480 Mbps. Though
USB was introduced in 1997, the technology didn't really take off until the introduction of the Apple
iMac (in late 1998) which used USB ports exclusively. It is somewhat ironic, considering USB was created
and designed by Intel, Compaq, Digital, and IBM. Over the past few years, USB has become a widelyused cross-platform interface for both Macs and PCs.
Each successive generation is fully backwards compatible with previous versions. Older devices always
work in newer sockets and newer devices always work in older sockets, albeit at the slower speed.
Currently USB 3.0 devices can reach speeds of up to 625 MBps. A proposal to increase the speed of USB
3.0 is due to be finalized by 2014, maximum transfer speeds will double to 1,250 MBps (matching
Thunderbolt), maximum power output will increase from 10 to 100 watts and a new reversible C type
plug will be introduced. These upgrades to the specification have been entitled USB 3.1 rather than USB
4.0.
USB devices include fans, keyboards, webcams, mice, sound cards and more. For the majority of these
peripherals speed isn't relevant as the specification already allows for much greater bandwidth than
most of these devices will ever require. Considerations such as energy consumption, cable length and
the ability to supply power are often more important to peripherals and since these factors are
improved by the spec upgrades even speed insensitive devices benefit as the USB specification
progresses.
USB-C = Stands for "Universal Serial Bus Type-C." USB-C is a type of USB connector that was introduced
in 2015. It supports USB 3.1, which means a USB-C connection can transfer data up to 10 Gbps and send
or receive up to 20 volts or 100 watts of power. Unlike the previous USB Type-A and USB Type-B ports,
the USB-C port is symmetrical, which means you never have to worry about plugging in the cable the
wrong way.
The USB-C connector is the most significant change to the USB connector since the USB interface was
standardized in 1996. USB 1.1, 2.0, and 3.0 all used the same flat, rectangular USB-A connector. While
Page | 66
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
there have been several variations of USB-B, such as Mini-USB and Micro-USB, they are all designed for
peripheral devices, which connect to a Type-A port on the other end. The Type-C connector introduced
with USB 3.1 is designed to be the same on both ends.
There is no mini or micro version of USB-C, since the standard USB-C connector is about the same size of
a Micro-USB connector. This means it can be used in small devices like smartphones and tablets. Since
USB-C supports up to 100 watts of power, it can also be used as the power connector for laptops. In fact,
the first laptops to include USB-C ports – the 2015 Apple MacBook and Google Chromebook Pixel – do
not include power connectors. Instead, the power cable connects directly to the USB-C port.
A USB-C connector will only fit in a USB-C port, but USB-C cables are backwards-compatible with other
USB standards. Therefore, a USB-C to USB-A or USB-C to USB-B adapter can be used to connect older
USB devices to a USB-C port. However, the data transfer rate and wattage will be limited to the lower
standard.
VGA = Stands for "Video Graphics Array." It is the standard monitor or display interface used in most
PCs. Therefore, if a montior is VGA-compatible, it should work with most new computers. The VGA
standard was originally developed by IBM in 1987 and allowed for a display resolution of 640x480 pixels.
Since then, many revisions of the standard have been introduced. The most common is Super VGA
(SVGA), which allows for resolutions greater than 640x480, such as 800x600 or 1024x768. A standard
VGA connection has 15 pins and is shaped like a trapezoid.
Video Card = Most of the processing done on a computer is done via the computer's central processing
unit, or CPU. So in order to give the CPU a break and help it run more efficiently, a video card can be
used to process the graphics portion of the processing load. Because most of today's programs are
graphically oriented, the video card can help almost any program run more efficiently. However, the
difference in performance is especially noticeable in image editing applications and 3D games.
Video cards, also called graphics accelerators, can speed up both 2D and 3D graphics rendering.
Programs such as photo editors and Web browsers may benefit from 2D acceleration, while CAD design
programs and video games will most likely benefit from the card's 3D acceleration. Some programs rely
so heavily on the video card, that they will not run if a supported video card is not installed.
Most video cards support the OpenGL and DirectX libraries. These libraries include commands for
manipulating graphics that programmers can include in their code. Some of these commands may
include moving or rotating an object, morphing polygons, or casting light and creating shadows. By using
standard OpenGL or DirectX functions, it makes it easier for developers to create graphically-oriented
programs. Of course, it also makes it necessary for the computer to include a supported video card in
order for the program to run.
WAN = Stands for "Wide Area Network." It is similar to a Local Area Network (LAN), but it's a lot bigger.
Unlike LANs, WANs are not limited to a single location. Many wide area networks span long distances via
telephone lines, fiber optic cables, or satellite links. They can also be composed of smaller LANs that are
interconnected. The Internet could be described as the biggest WAN in the world. This library is part of a
WAN that connects to many different libraries in the state.
Webcam = The term webcam is a combination of "Web" and "video camera." The purpose of a webcam
is, not surprisingly, to broadcast video on the Web. Webcams are typically small cameras that either
Page | 67
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
attach to a user's monitor or sit on a desk. Most webcams connect to the computer via USB, though
some use a Firewire connection. Webcams typically come with software that allows the user to record
video or stream the video on the Web. If the user has a website that supports streaming video, other
users can watch the video stream from their Web browsers.
Webcams can also be used for video chat sessions with other people. Instead of broadcasting the video
on the Web, users can set up a video chat session with one or more friends and have a conversation
with live audio and video. For example, Apple's iSight camera, which is built into Apple laptops and
iMacs, allows users to video chat using the iChat instant messaging program. Several other chat
programs also work with webcams, allowing users to set up video chat sessions with friends.
Since streaming video over the Internet requires a lot of bandwidth, the video stream is typically
compressed to reduce the "choppiness" of the video. The maximum resolution of a webcam is also
lower than most handheld video cameras, since higher resolutions would be reduced anyway. For this
reason, webcams are relatively inexpensive compared to most video cameras. And while they may not
be ideal for filming a movie, webcams are great for video chat sessions with friends.
X86 = x86 is the generic name for Intel processors released after the original 8086 processor. These
include the 286, 386, 486, and 586 processors. As you can see, the "x" in x86 stands for a range of
possible numbers. Technically, x86 is short for 80x86 since the full names of the processors are actually
80286, 80386, 80486, and 80586. The "80" is typically truncated to avoid redundancy.
If a computer's technical specifications state that is based on the x86 architecture, which means it uses
an Intel processor (not AMD or PowerPC). Since Intel's x86 processors are backwards compatible, newer
x86 processors can run all the programs that older processors could run. However, older processors may
not be able to run software that has been optimized for newer x86 processors.
While numbers provide a simple way to distinguish between processor types, they cannot be
trademarked. For this reason, Intel's 586 processor is formally known as the Pentium processor.
However, software developers still often refer to processors by their number. Of course, what else
would you expect from computer nerds?
X86_64 = (also known as x64, x86_64 and AMD64) is the 64-bit version of the x86 instruction set. It
supports vastly larger amounts (theoretically, 264 bytes or 16 exbibytes) of virtual memory and physical
memory than is possible on its 32-bit predecessors, allowing programs to store larger amounts of data in
memory.
Page | 68
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Bits and Bytes
BIT (b)= A bit (short for "binary digit") is the smallest unit of measurement used to quantify computer
data. It contains a single binary value of 0 or 1.
While a single bit can define a boolean value of True (1) or False (0), an individual bit has little other use.
Therefore, in computer storage, bits are often grouped together in 8-bit clusters called bytes. Since a
byte contains eight bits that each have two possible values, a single byte may have 28 or 256 different
values.
The terms "bits" and "bytes" are often confused and are even used interchangeably since they sound
similar and are both abbreviated with the letter "B." However, when written correctly, bits are
abbreviated with a lowercase "b," while bytes are abbreviated with a capital "B." It is important not to
confuse these two terms, since any measurement in bytes contains eight times as many bits. For
example, a small text file that is 4 KB in size contains 4,000 bytes, or 32,000 bits.
Generally, files, storage devices, and storage capacity are measured in bytes, while data transfer rates
are measured in bits. For instance, an SSD may have a storage capacity of 240 GB, while a download may
transfer at 10 Mbps. Additionally, bits are also used to describe processor architecture, such as a 32-bit
or 64-bit processor.
BYTE (B)= A byte is a unit of measurement used to measure data. One byte contains eight binary bits, or
a series of eight zeros and ones. Therefore, each byte can be used to represent 2^8 or 256 different
values.
The byte was originally developed to store a single character, since 256 values is sufficient to represent
all standard lowercase and uppercase letters, numbers, and symbols. However, since some languages
have more than 256 characters, modern character encoding standards, such as UTF-16, use two bytes,
or 16 bits for each character.
While the byte was originally designed to measure character data, it is now the fundamental unit of
measurement for all data storage. For example, a kilobyte contains 2^10 or 1,024 bytes. A megabyte
contains 1,024 x 1,024, or 1,048,576 bytes. Since bytes are so small, they are most often used to
measure specific data within a file, such as pixels or characters. Even the smallest files are typically
measured in kilobytes, while data storage limits are often measured in gigabytes or terabytes.
KILOBYTE (KB)= A kilobyte is 103 or 1,000 bytes.
The kilobyte (abbreviated "K" or "KB") is the smallest unit of measurement greater than a byte. It
precedes the megabyte, which contains 1,000,000 bytes. While one kilobyte is technically 1,000 bytes,
kilobytes are often used synonymously with kibibytes, which contain 1,024 bytes.
Kilobytes are most often used to measure the size of small files. For example, a plain text document may
contain 10 KB of data and therefore would have a file size of 10 kilobytes. Small website graphics are
often between 5 KB and 100 KB in size. While some files contain less than 4 KB of data, modern file
systems such as NTFS (Windows) and HFS+ (Mac) have a cluster size of 4 KB. Therefore, individual files
typically take up a minimum of four kilobytes of disk space.
Page | 69
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
MEGABYTE (MB) = A megabyte is 106 or 1,000,000 bytes.
One megabyte (abbreviated "MB") is equal to 1,000 kilobytes and precedes the gigabyte unit of
measurement. While a megabyte is technically 1,000,000 bytes, megabytes are often used
synonymously with mebibytes, which contain 1,048,576 bytes (220 or 1,024 x 1,024 bytes).
Megabytes are often used to measure the size of large files. For example, a high resolution JPEG image
file might range is size from one to five megabytes. Uncompressed RAW images from a digital camera
may require 10 to 50 MB of disk space. A three minute song saved in a compressed format may be
roughly three megabytes in size, and the uncompressed version may take up 30 MB of space. While CD
capacity is measured in megabytes (typically 700 to 800 MB), the capacity of most other forms of media,
such as flash drives and hard drives, is typically measured in gigabytes or terabytes.
GIGABYTE (GB) = A gigabyte is 109 or 1,000,000,000 bytes.
One gigabyte (abbreviated "GB") is equal to 1,000 megabytes and precedes the terabyte unit of
measurement. While a gigabyte is technically 1,000,000,000 bytes, in some cases, gigabytes are used
synonymously with gibibytes, which contain 1,073,741,824 bytes (1024 x 1,024 x 1,024 bytes).
Gigabytes, sometimes abbreviated "gigs," are often used to measure storage capacity. For example, a
standard DVD can hold 4.7 gigabytes of data. An SSD might hold 256 GB, and a hard drive may have a
storage capacity of 750 GB. Storage devices that hold 1,000 GB of data or more are typically measured in
terabytes.
RAM is also usually measured in gigabytes. For example, a desktop computer may come with 16 GB of
system RAM and 2 GB of video RAM. A tablet may only require 1 GB of system RAM since portable apps
typically do not require as much memory as desktop applications.
TERABYTE (TB) = A terabyte is 1012 or 1,000,000,000,000 bytes.
One terabyte (abbreviated "TB") is equal to 1,000 gigabytes and precedes the petabyte unit of
measurement. While a terabyte is exactly 1 trillion bytes, in some cases terabytes and tebibytes are
used synonymously, though a tebibyte actually contains 1,099,511,627,776 bytes (1,024 gibibytes).
Terabytes are most often used to measure the storage capacity of large storage devices. While hard
drives were measured in gigabytes for many years, around 2007, consumer hard drives reached a
capacity of one terabyte. Now, all hard drives that have a capacity of 1,000 GB or more are measured in
terabytes. For example, a typical internal HDD may hold 2 TB of data. Some servers and high-end
workstations that contain multiple hard drives may have a total storage capacity of over 10 TB.
Terabytes are also used to measure bandwidth, or data transferred in a specific amount of time. For
example, a Web host may limit a shared hosting client's bandwidth to 2 terabytes per month. Dedicated
servers often have higher bandwidth limits, such as 10 TB/mo or more.
PETABYTE (PB) = A petabyte is 1015 or 1,000,000,000,000,000 bytes.
One petabyte (abbreviated "PB") is equal to 1,000 terabytes and precedes the exabyte unit of
measurement. A petabyte is slightly less in size than a pebibyte, which contains 1,125,899,906,842,624
(250) bytes.
Page | 70
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Since most storage devices can hold a maximum of a few terabytes, petabytes are rarely used to
measure the storage capacity of a single device. Instead, petabytes are more commonly used to
measure the total data stored in large computer networks or server farms. For example, Internet
companies like Google and Facebook store over 100 petabytes of data on their servers.
EXABYTE (EB) = An exabyte is 1018 or 1,000,000,000,000,000,000 bytes.
One exabyte (abbreviated "EB") is equal to 1,000 petabytes and precedes the zettabyte unit of
measurement. Exabytes are slightly smaller than exbibytes, which contain 1,152,921,504,606,846,976
(260) bytes.
The exabyte unit of measure measurement is so large, it is not used to measure the capacity of data
storage devices. Even the storage capacity of the largest cloud storage centers is measured in petabytes,
which is a fraction of one exabyte. Instead, exabytes are used to measure the sum of multiple storage
networks or the amount of data transferred over the Internet in a certain amount of time. For example,
several hundred exabytes of data are transferred over the Internet each year.
ZETTABYTE (ZB) = A zettabyte is 1021 or 1,000,000,000,000,000,000,000 bytes.
One zettabyte (abbreviated "ZB") is equal to 1,000 exabytes and precedes the yottabyte unit of
measurement. Zettabytes are slightly smaller than zebibytes, which contain
1,180,591,620,717,411,303,424 (270) bytes.
A single zettabyte contains one sextillion bytes, or one billion terabytes. That means it would take one
billion one terabyte hard drives to store one zettabyte of data. Because the zettabyte unit of
measurement is so large, it is only used to measure large aggregate amounts of data. Even all the data in
the world is estimated to be only a few zettabytes.
YOTTABYTE (YB) = A yottabyte is 1024 or 1,000,000,000,000,000,000,000,000 bytes.
One yottabyte (abbreviated "YB") is equal to 1,000 zettabytes and is the largest SI unit of measurement
used for measuring data. It is slightly smaller than its IEC-standardized counterpart, the yobibyte, which
contains 1,208,925,819,614,629,174,706,176 bytes (280) bytes.
A single yottabyte contains one septillion, or one trillion times one trillion bytes, which is the same as
one trillion terabytes. It is also a number larger than any human can comprehend. There is no need for a
unit of measurement larger than a yottabyte because there is simply no practical use for such a large
measurement. Even all the data in the world consists of just a few zettabytes.
Page | 71
Patrick Landers | Judge George W. Armstrong Library|220 S. Commerce St, Natchez, MS 39120
http://www.armstronglibrary.org | http://ebooks.armstronglibrary.org | http://catalog.armstronglibrary.org
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement