What Is a Computer and What
Does It Do?
Computer: programmable, electronic device that
accepts data, performs operations, presents the
results, and can store the data or results
Input—entering data into the computer
Processing—performing operations on the data
Output—presenting the results
Storage—saving data, programs, or output for
future use
What Is a Computer and What
Does It Do? Cont’d
Data vs. Information
• Data = raw, unorganized facts
– Can be in the form of text, graphics, audio, or
video
• Information = data that has been
processed into a meaningful form
• Computers process data into information
The components of a computer
• 6 Primary components
– Input devices
– Processor
– Memory
– Output devices
– Storage devices
– Communication devices
• All the components are housed in a box
called the system unit
Hardware
• The physical parts of a computer are
collectively referred to as hardware
– Internal hardware: located inside the main box
(system unit) of the computer
– External hardware: located outside the
system unit and plug into connectors called
ports located on the exterior of the system
unit
Storage Devices
• Used to store instructions data and
information when they are not being used
for memory
• Disks
• Tape
• Mobile Storage
Communication Devices
• Hardware component that allows a
computer to send and receive data,
instructions and information to and from 1
or more computers
• Communications occur over transmission
media
INPUT AND OUTPUT
• Hardware that allows
you to enter data,
programs or
commands
• Keyboard
• Mouse
• Scanner
• Microphone
• Hardware that makes
the information that
was processed
available for use
• Printers
• Display devices
• Speakers
Software
• The programs or instructions used to tell the computer
hardware what to do
• System software: allows a computer to operate
• Operating system: the main system software program
– Boots the computer and launches programs etc. at
the user’s direction
– Windows, Mac OS, Linux, etc.
Software
• Application software: performs specific
tasks or applications
– Creating letters, budgets, etc.
– Managing inventory and customer databases
– Scheduling appointments
– Viewing Web pages
– Sending and receiving e-mail
– Designing homes
– Playing games
– And much, much more
Electrical Components
• Electrical components include:
– Motherboard
– Processor
• ALU
• CPU
– Memory
• Usually measured in kilobytes (1,000 bytes),
megabytes (1 million) or gigabytes (1 billion)
• A byte is equal to one character
Computers to Fit Every Need
• Five basic categories
– Mobile devices
– Personal computers
– Midrange servers
– Mainframe computers
– Supercomputers
Mobile Devices
• Very small device with some type of
built-in computing or Internet capability
• Typically based on cellular phones
• Smart phones can be used to access
the Web and e-mail, take photos, play
games, access calendars, and address
books
• Smart watches can download
information from the Internet, store
data, play music files, etc.
Personal Computers
• Small computer system designed to be used by one
person at a time; small enough to fit on a desktop,
inside a briefcase
• Also called a microcomputer
• PC-compatible: evolved from the original IBM PC;
typically runs the Windows operating system
• Macintosh: type of personal computer manufactured
by Apple, uses the Mac OS operating system
• Can be desktop, notebook, tablet, or handheld
computers
Desktop PCs
• Desktop PC: the complete computer system fits
on or next to a desk; case styles include:
• Tower
• Desktop
• All-in-one
Midrange Servers
• Minicomputer or
midrange computer:
medium-sized computer
used to host programs
and data for a small
network
• May consist of a
collection of individual
circuit boards called
blades (blade servers)
Mainframe Computers
• Standard choice for large
organizations, hospitals,
universities, large businesses,
banks, government offices
• Larger, more expensive, and
more powerful than midrange
servers; usually operate 24
hours a day
• Also called high-end
servers or enterprise-class
servers
Supercomputers
• Fastest, most expensive, most powerful
type of computer
• Space exploration, missile guidance,
satellites, weather forecast, oil exploration,
scientific research, complex Web sites,
decision support systems, 3D applications
• Commonly built by connecting hundreds of
smaller computers, supercomputing
cluster
Supercomputers, Cont’d
Computer Networks and the
Internet
• Computer network: collection of hardware and other
devices that are connected together so that users can
share hardware, software, and data, as well as
communicate with each other
• Network servers: manage resources on a network
• Clients: computers on a network that access resources
through the network server
• Computer networks exist in many sizes and types
What Are the Internet and the
World
Wide Web?
• Internet: largest and most well-known computer
network in the world
• Individuals connect to the Internet using an
Internet service provider (ISP)
• Most common Internet activities: e-mail and
accessing the World Wide Web (WWW)
• “Internet” refers to the physical structure of that
network, the World Wide Web is one resource (a
vast collection of Web pages) available through
the Internet
Accessing a Network or the
Internet
• Need a modem or network adapter to physically
connect your computer to the network
• Software (often built into the operating system)
allows you to log on to the network and access
resources
• Many networks and Internet connections require
a user ID and password to log on to the network
Accessing a Network or the
Internet, Cont’d
• Internet addresses are used to access
resources on the Internet
– IP address —numeric address that identifies
computers (207.46.138.20)
– Domain name —text-based address that
idenfies computers (microsoft.com)
– Uniform resource locator (URL) —identifies
Web pages (http://www.pbskids.org)
– E-mail address —identifies people for e-mail
exchange (jsmith@thomson.com)