Concepts Unit A: Objectives
 Examine computer hardware and software.
 Explore networks and data communications
 Learn about security threats on the internet
and how to protect computer systems and
personal information
1
Defining Computers
A computer is an electronic device
 accepts input
 processes and stores data
 produces output
Types of Computers
 Personal computers
• Desktop
• Notebook (Laptop)
• Tablet PC
 Hand-helds: PDAs, MP3 players, Cell phones
 Mainframes
 Supercomputers
 Other computers (at home, in car…)
Types of Computers
 Personal computers are used for general computing
tasks.
 Hand-held computers fit in the palm of your hand and
run on batteries.
 Mainframes are used by companies to provide
centralized storage, processing, and management for
large amounts of data.
 Supercomputers are the largest and fastest of
computers, and can process an enormous volume of data.
Types of Computers
 Desktop: (HP, Dell, IBM…)
• Usually more powerful and cheaper than
laptops
• Needs separate monitor, not easy to move
around
• Could be replaced by laptops and tablets in
the near future?
Types of Computers
 Notebook, Netbook & iPad
• Small & lightweight.
• Portable
• Netbook: browsing
• Internet
• Tablets (7” and 10”)
Types of Computers
 Supercomputers are the
largest and fastest
computers. BNL Bluegene
 Mainframe s are very
powerful computers, but
not as powerful as
supercomputers.
 Clusters: consists of
hundreds and more
processors.
Computer Systems
A computer system is made up of:
 Hardware — the physical components. Can
be touched. If kicking it, your toe will get
hurt.
 Software — the programs or lists of
instructions. Can not be touched.
 Software could be more expensive than
hardware. Why do most people KEEP using
Windows system?
Can we reduce the weight of a
computer by deleting its
software (files).
No!!!
Software has no weight.
Hardware: major components
 Motherboard
 CPU (Central Processing Unit)
 Memory
 Storage devices
 I/O (Input/Output) devices
 Network devices
 Power supply, case, video card, sound card…
Hardware: Motherboard
 Also called
mainboard
 Located inside the
computer case
 Holds and connects
all essential
components
Hardware: CPU
 CPU - micro processor
• A silicon chip designed
to manipulate data
• The brain of a
computer.
• 64-bit CPUs and 32-bit
CPUs
Hardware: CPU (cont.)
 Intel, AMD, Apple, IBM… make CPUs.
 Its speed is determined by:
• Clock speed (Hz)
• Word size (32-bit and 64-bit)
• Processor type
• Usually, motherboard and CPU are the most
expensive components in a computer.
High-end video cards are not cheap either.
Question
1. What are the two most
expensive components in
a computer?
Hardware: Units of Memory and Storage
 Computer understands 0 and 1 only: on/off
state, N/S pole, 0/5 volts…
 1 (“on”) and 0 (“off”) are referred to as bits.
 Eight bits is a byte. Two bytes represent a
unique character (Unicode)
 Decimal numbers and binary numbers.
Hardware: Units of Memory and Storage
 Everything in the computer memory and




storage devices is a number! A computer
understands only numbers.
Number  number
Character  number (ASCII code)
Grey level  number ( usually 0 – 255)
Color  three numbers (R/G/B)
Question
2. A byte can store 256
different numbers, why
do we need two bytes to
store an English
character?
Hardware: units of Memory and
Storage
 Kilobyte (KB) = one thousand (1024) bytes
 Megabyte (MB) = one million (1024 KB)
bytes
 Gigabyte (GB) = one billion bytes
 Terabyte (TB) = one trillion bytes
Hardware: Memory
 Computer memory is a set of storage
locations.
 Five types of memory:
•
•
•
•
•
Random access memory (RAM)
Cache memory
Virtual memory
Read-only memory (ROM)
Complementary metal oxide semiconductor
memory (CMOS)
Hardware: Memory
 RAM --- Random Access Memory
• Sits on motherboard and closes to CPU
• Also called volatile memory, primary
memory, and main memory.
• Most important memory type.
• 256 MB to many GBs.
• Fast CPU + big memory + (fast graphical
card) a fast computer.
Hardware: Memory
 Cache memory
• Special high-speed memory chip on the
motherboard or CPU
• Stores frequently and recently accessed data
and commands.
• Usually 1 to ??? MB.
• The bigger, the better, also more expensive.
Hardware: Memory
 Virtual memory is extra memory that simulates
RAM if more is needed. Limited by the memory
space (word size).
 Read-only memory (ROM) is the permanent
storage location for a set of instructions the
computer uses.
 CMOS memory is semi-permanent information
about where essential software is stored.
Hardware: Storage Media
 Magnetic storage devices
• Hard disks—several magnetic oxide covered
metal platters usually sealed in a case inside
the computer
• Tape—inexpensive, slow, archival storage for
large companies who need to back up large
quantities of data.
• Floppy disks: (almost) obsolete
Hardware: Storage Media
 Optical storage devices
• CD-R - store 700 MB of data
• CD-RW: not reliable
• DVD—can store between 4.7 and 15.9 GB of
data; Blue-ray discs and HD-DVD can store
between 15 and 50 GB of data
Hardware: Storage Media
 Flash memory cards
• Small, portable cards: rewritable
• Used in digital cameras, handheld computers,
video game controllers, and other devices
• Most commonly-used: SD (HDSD) cards –
Secure Digital.
Hardware: Storage Media
 USB drive, USB flash
drive
• from 32 MB to 16 GB and
•
•
•
•
more
Plug directly into the USB
port (hot operation)
Rewritable
Best portable storage
Small and inexpensive:
$1.50/GB
Hardware: Differences between
memory & storage
Speed
Persistent
Size
Location
Memory
Fast
No
Limited
On board
Storage
Slow
Yes
Unlimited(?)
External
Question
3. When we talk about
memory and storage,
how do you compare
computers and people?
Hardware: Input/Output
 Input:
• Data you type
• Data by reading files
• Data through Internet.
• Data from sensors……
• Other sources
 Output: The result of computer
processing.
Hardware: Input/Output
 Peripheral devices
• Accomplish the input, output, and
storage functions.
• Not on the motherboard  slow
• I/O always is the slowest part of any
program execution
Hardware: I/O Devices
Input devices:
 Keyboard
 Mouse
 Others
Hardware: I/O Devices
 Output devices:
• Monitors
 CRT monitors (almost obsolete)
 LCD and LED
• Printers
• Others
Hardware: I/O Devices
Monitor’s quality
 Screen Size
(diagonal in inches)
 Resolution (in pixels)
 Setting the screen
resolution.
Hardware: I/O Devices
 Types of printers
• Laser
• Inkjet
 B/W printing:
buy laser printers
 Color laser printer:
very expensive
cartridges.
Inkjet printer
Hardware: Printer
 Turn OFF the printer when not printing to
prevent the heat from drying the
cartridges.
 Use the power button to turn off the
printer in order to make cartridges stay in
the proper housing. Do not pull the power
cord.
Hardware: Video Card
 Integrated (on-board) and dedicated
video cards
 Gaming: needs high-end video cards.
 High-end computers have dedicated
video-cards
 Usually, a video card has its own
memory; on-board video shares main
memory.
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Hardware: Network Devices




Network cables (Ethernet cables)
Modems and routers
Wireless cards and adapters
Building a home wireless network: Not as
hard as one thinks. Just follow the
instructions.
A Desktop Computer
Motherboard and others
The Back of a Computer
Power connection
Keyboard port
Mouse port
Audio
connection
Monitor port
FireWire port
USB ports
Network port
Speaker and
microphone
connections
Phone line
connection
Computer ports and connections
Hardware: How to fix it?
 Blue screen, won’t boot…
 If under warrantee, let manufacturer fix it
 Diagnostics
• Run diagnostic program
• Go to web to search solutions
 Hardware problem: DIY in many cases. It
is easier than you think
Hardware: How to fix it?
 Motherboard ($300-500): expensive, buy a
new computer or fix it?
 CPU ($100 and up): relatively expensive.
Installation: 30-60 minutes.
 Memory ($50 for 4GB): Installation: 10 - 30
minutes.
Hardware: How to fix it?
 Hard drive ($50 for 500GB): Need the
system reinstallation CD to build a system
drive. Installation: 10 - 30 minutes.
 CD/DVD drive ($30): Installation: 10-30
minutes.
 Laptop display screen ($200 and up):
installation: one-hour delicate job.
Professional help?
Hardware: How to fix it?
 Important: Always rub your hands with the
computer metal frame at first to get rid of
the static electricity.
 Do it carefully, but with confidence.
Software: major Components
 Operating system
• Windows
• Unix & Linux (open and free)
• MacOS
 System utilities
 Application software
Software: Introduction
 Software manipulates and processes data
 Data:
Strings, numbers, figures, sounds, images,
and graphics…
Software: Introduction
 File --- named collection of stored data.
• Executable file can be run to perform a specific
task.
• Data file contains data.
 Everything in a computer is represented by
a number on disk and in memory.
Software: Data Representations
 Every English
character is
represented by an
ASCII number.
 ASCII numbers
defined by ANSI.
ANSI standard sample ASCII code
Software: Data Representations
 ASCII --- American Standard code for
Information Exchange
 ANSI --- American National Standards
Institute
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Software: System Software
 System software helps the computer
carry out it s basic operating tasks.
•
•
•
•
Operating systems
Utilities
Device drivers
Programming languages
Software: System Software
 Operating system
• Executes programs
• controls the input and output (I/O)
• allocates system resources and priorities
• Schedules tasks
• manages files on storage devices
• guards against equipment failure
• provides a graphical user interface (GUI)
• Others
Software: System Software
 Operating system
• Programmer: develop and write the system
• System administrator (SA): configure and
maintain the system
• End user: use the system
 Using GUI (Graphical User Interface)
 Manipulating files
Software: System Software
 Major Operating systems
• Windows by Microsoft: most recent version is
Windows 7.
• Unix/Linux: many flavors (Sun Solaris, HP-UX,
IBM AIX, Redhat, Debian, Ubuntu…)
• MacOS: only for Apple computers.
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Software: System Software
 Which OS is better?
• Windows: most popular. Easy to use. Many
applications. Hardware/software installation is
easy. Prone to virus attacks.
• Unix/Linux: free. Popular in academic world.
Hardware/software installation needs effort and
expertise. More secure than Windows.
• MacOS: nice GUI, stable and reliable. Pay a
premium because it’s Apple.
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Software: System Software
 We are users and we learn
• Basic knowledge of file systems.
• To use GUI of the system
• To configure the system
• To maintain the system
55
Software: System Software
 Utilities
• Analyze, configure, optimize and maintain
computer system: disk defragmenter, system
restore…
 Device drivers
• “Drives” a specific device (drive).
• The main task to install a device is to install its
driver.
Software: System Software
 Programming languages
• Used by a programmer to develop
programs.
• Most commonly used computer
language: C, C++, Java, C#, Visual
Basic, Fortran…
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Software: System Software
 Drive and Driver
• Drive --- Hardware
• Driver --- software to “drive” a specific
drive.
 Examples:
Hard (disk) drive --- Hard (disk) driver
USB drive --- USB driver
Printer --- Printer driver
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Software: System Software
Icons (you
might see
additional
icons on
your
screen)
Gadgets
(small
programs;
you might see
additional or
different
gadgets on
your screen)
Start button
Taskbar
Quick Launch toolbar
Windows Vista starting screen
Software: Application Software
 Enables you to perform specific
computer tasks
 Examples: web browsers, Microsoft
Office, DBMS, ……
Software: Application Software
 Document production software
• Word processing, desktop publishing…
• Microsoft Word, OpenOffice
 Spreadsheet software (Excel)
• Creates spreadsheets composed of a grid of
columns and rows
• Numerical calculations of cell data
Software: Application Software
 Database management software (Access)
• Collects and manages data
 Database
• Contains many tables to store data in a
uniform format of records and fields
• record—a collection of data items in a
database
• field—one piece of information in the record
Software: Application Software
 Presentation software (PowerPoint)
• Makes slides to be presented.
 Many other types of application
software.
Data Communications
 Data communications --- Transfer data
between computers
 The four essential components
•
•
•
•
Sender
Channel
Receiver
Protocols
Data Communications
 A sender is the computer that originates the




message.
The message is sent over a channel.
The receiver is the computer that receives the
message.
Protocols are the rules that governs the data
transfer.
Data bus: the data path.
Data Communications
Components needed to connect a printer to a computer
Data Communications
PCs have several types of ports:
• Parallel
• Serial
• SCSI
• USB
• MIDI
• Ethernet
Data Communications
 Parallel port—transmits data eight bits at a
time
 Serial port—transmits data one bit at a time
 SCSI (small computer system interface,
pronounced “scuzzy”) port—provides an
interface for one or more peripheral devices
at the same port
 USB (Universal Serial Bus) port—a highspeed serial port which allows multiple
connections at the same port
Data Communications
 Sound card port—usually includes jacks for
speakers and a microphone, which are
designed to work with a MIDI (Musical
Instrument Digital Interface, pronounced
“middy”) card
 Ethernet port—used to connect to another
computer, a LAN, a modem, or sometimes
directly to the Internet; allows data to be
transmitted at high speeds.
Data Communications
Computer ports and connections
Networks
 Network
• connects one computer to other computers
and peripheral devices
 Network interface card (NIC)
• creates a communications channel between
the computer and the network
• a cable connects the NIC port to the network
• Ethernet card
 Network software
• establishes the communications protocol
• controls the traffic flow
Networks
 Server - central storage location for
programs
 Client- computers on a network dependent
on and connect to a server
 Client/server network—a network with
server and many clients.
 Peer-to-peer network
• a network without a server
• all of the computers are equal
Networks
 Standalone computer—a personal
computer that is not connected to a
network
 Workstation—a personal computer that is
connected to a network
 Node—any device connected to the
network
Networks
 LAN (local area network)
 WAN (wide area network)
• more than one LAN connected together
• the Internet is the largest example of a WAN
 WLAN (wireless local area network)
• Computers and peripherals that use high-
frequency radio waves instead of wires to
communicate and connect in a network
• Wi-Fi (wireless fidelity) describes WLANs
connected using a standard radio frequency
established by the Institute of Electrical and
Electronics Engineers (IEEE)
Networks
 PAN (personal area network)—a network that allows two
or more devices located close to each other to
communicate or to connect a device to the Internet
• infrared technology—uses infrared light waves to beam data
from one device to another
• Bluetooth—uses short range radio waves to connect a device
wirelessly to another device or to the Internet
 WiMAX (Worldwide Interoperability for Microwave
Access)
• allows computers to connect over many miles to a LAN
• a WiMAX tower sends signals to a WiMAX receiver built or
plugged into a computer
Networks
Analog
signal
Digital
signal
Digital
signal
Sending site
Modem
Modem
Using modems to send and receive data
Receiving site
Security Threats: virus (malware)
 Software programs infesting computers:




Worms, Trojan horse, spyware, adware…
Replicates itself and fill up disks
Damages computer systems
Erases files and wipes out disks
Ties up network and computers. Slows
down program execution
Security Threats: viruses
 Pops up ads
 Keylogger: steals personal
information
 Creates a back-door and lets remote
users access your computer
 A bad virus spreads very fast and
affects millions computers.
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Security Threats: Sources of
viruses
 Downloading virus-infected files
 Opening malicious emails and their
attachments
 Infected disks and CDs
 Worst incidents: Melissa, ILOVEYOU
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Security Threats: Anti-virus
 Firewall
• Stop unwanted and unsolicited incoming
network messages and data.
• Can be either hardware or software.
 Antivirus software
• Every computer must equip with an antivirus
software.
 System and software update:
• Automatic update
Security Threats: Antivirus
 Microsoft: security_essentials (free)
 Paid: Norton, MacAfee, Trend Micro
 Free:
• ClamAV: open source. For Unix/Linux , also for
•
•
•
•
Windows
Clamwin: variant of ClamAV for Windows
Stopzilla
Avast!
AVG Anti-Virus
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Security Threats: Antivirus
There is no excuse not to install an
antivirus software, at least it should have
security_essential installed from
www.microsoft.com/security_essential
SE is free and works well!
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Security Threats: Spoofed sites
 Spoofed site
• A Web site set up to look like another Web
site, but which does not belong to the
organization portrayed in the site
• The URL (address on the Web) looks similar
to a URL from the legitimate site
www.citibank.com and www.citybank.com
• Usually set up to try to convince customers
of the real site to enter personal information
Security Threats: Phishing
 Phishing
• Sending e-mails to customers of a legitimate Web
site (banks and institutions) asking them to click a
link in the e-mail because of
 Security upgrade
 Account update
 Account compromised
 Other reasons
• If the customer does not click the link, his/her
account will be suspended or closed
• the link leads to a spoofed site and asks personal
and/or login information.
Security Threats: Other tricks
 Nigerian scams
• Lottery winner, request processing fee
• Unclaimed treasure: needs your account number to
deposit
 Over-payment scam
• You sell an item (a car…)
• A far-away guy will buy it and send you a bank
check larger than your asking price
• He asks you to mail the extra to himself or
someone else through western union…
• You deposit the check and send the extra back (real
money). Several weeks later, the check bounced.
Security Threats: Phishing
 Too good to be true >>> not true
 Never open an unsolicited email, especially, its




attachments
Never reveal your personal information (SSN,
bank account number, credit number…) unless
you initialize the communication
Never make any payment to a (faraway) stranger.
Wait for the check cleared, then take action.
If someone specifically ask you to send money
through Western Union or Money Gram  most
likely it’s a scam.
Security Threats: Phishing
 To clear a bank check needs one to
several weeks, especially foreign checks.
 Payment by Western Union… is not
traceable.
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Security Threat: Strong password
 At least eight characters long
 Consists of upper- and lowercase
letters and numbers
 Does not include common personal
information
Security Threats: Encryption
 Encrypt important files especially when
files are on a USB drive.
 TrueCrypt: free and easy to use for Unix,
Linux, and Windows.