Computers SimplifiedComputers Simplified

Supplemental Lecture Notes

IntroductionIntroduction

Chapter 1

Parts of A Computer

Hardware – you can see it or touch it Software – set of electronic instructions

– Application software – specific tasks– Operation software – controls overall activity

Peripherals – anything attached

What Computers Do

A computer collects (input), processes, stores and outputs information.

Storage Simplified

Bit: on or off– Smallest unit of information in a computer

Byte: one character– 8 binary digits

Bigger Is Better Kilobyte (KB)

– 1,024 character• One double-spaced typed page

Megabyte (MB)– 1,048,576 characters

• A book

Gigabyte (GB)– 1,073,741,824

• A shelf of books

Terabyte (TB)– 1,099,511,511,627,776 characters

• A library of books

Set-top Box

Computer device that you connect to your television.– Use telephone or cable connection– Email of Internet

Typical System

Computer case Monitor Printer Speakers Modem Keyboard Mouse

Computer Components Power supply Hard drive Expansion card Expansion slot System board CD-ROM or DVD-ROM Floppy disk Drive bay Central Processing Unit (CPU) Random access memory (RAM)

Power Plays

The capacity of a power supply is measured in watts

Computer uses 250; light bulb uses 60 Can use

– Surge protector– UPS

Ports

Ports are connectors at the back of a computer system that you use to plug in an external device. This allow instructions and data to flow between the computer and the device

Any Port in a Storm

Parallel port – 25 holes; female connector; LPT1; printer or storage devices

Monitor port Keyboard port Serial port – 9 or 25 pins; male connector; COM1; mouse

or modem Game port Network port USB port

– 127 devices– Printer, modem, joy stick

Growing

An expansion card is a circuit board that lets you add new features to a computer– Video– Modem– Sound– Network Interface

Upgrades

Upgrading refers to replacing an old or obsolete component with a newer component to improve the efficiency of the computer

Upgrading also can include adding a new component like a tape drive or DVD to increase the capabilities of a computer

Increasing the amount of memory in a computer is one of the most effective upgrades you can perform

Input and OutputInput and Output

Chapter 2

Mouse Actions

Click – selects Right click – displays commands Double click – opens Drop and Drag – moves items on screen

Mice

Types– Conventional– Wheel mouse– Wireless mouse– Programmable mouse – e.g. three buttons– Optical sensor mouse

Other devices– Touchpad– Trackball– Pointing stick

Keyboards

There are 101 keys on a keyboard to help you input information

Function keys let you perform specific task Can use CNTL-x shortcuts to execute

commands– CNTL-C – copy– CNTL-X – cut– CNTL-V – paste

Windows key will quickly display the start menu

Printers

Speed of a printer is measured in pages per minute (PPM). A higher speed represents faster output

Resolution determines the quality of images– A higher resolution results in sharper images– Printer resolution is measured in dots per inch (dpi)

• 600 dpi is acceptable; 1200 is better for images

– Resolution expressed with two numbers represents dots per inch across and down

Types of Printers Ink-jet: has a print head that sprays ink

through tiny nozzles onto a page– 2 to 10 pages (ppm)– 360 to 2400 dots per inch– Color printers spray cyan, magenta, yellow

and black to create different colors Laser-printer

– Works like a photo copier– Speed of 4 to 16 pages– Have a CPU– 600 to 2400– Memory – 2mb to 8 Mb

Other Types

Dot matrix– Print head contains small blunt pins that strike

an inked ribbon• Useful for multi-part forms

LED printer• Similar to lasers but cheaper

Color photo printer Multifunction Printer

Print Buffer and Spoolers

Printer buffer: section of memory printer stores information waiting to print

Printer spooler: program on your computer that stores information waiting to print– Stores more information than the buffer– One spooler for each connected printer

Monitors Video cards translate instructions from

the computer into a form Most computes the monitor can understand– require at least 2 mb of video card

memory– Accelerated Graphics Port (AGP) – uses

AGP bus to communicate directly with main memory

– 3D Graphics Accelerator has chip called a GPU optimized for 3-D graphics

Monitor Metrics

The smaller the dot pitch, the crisper the image– 0.28mm is acceptable

Refresh rate is measured in hertz (Hz)– Times per second computer redraws the image– 72 Hz or more is acceptable

Resolution

Amount of information a monitor can display– Measured by the number of horizontal and vertical

pixels

Monitors switch settings based on the resolution and refresh rate of video card

Video card determines number of colors a monitor can display– 256 suitable for most home use– 24-bit displays more colors than eye can distinguish

Communications Modems let a computer exchange

information through telephone lines Speed of a modem determines how fast it

sends and receives messages– 56,000 bps (56 Kbps)

• V.90 standard: receive 56K and send 33.6K

– Speed at which information flows depend on the quality of the phone line

A modem needs a communications package to manage the transmission of information

Data compression – squeezes together data

High-speed Connections ISDN – Integrated Services Digital Network

– Digital phone line– 56 Kbps to 128 Kbps

Cable Modem– Same cable as TV– 4000 Kbps

DSL – Digital subscriber line– High speed digital phone line– 1000 – 6000 Kbps

Satellite

Sound Cards

Sampling Rate: at least 44.1 KHz Full-duplex

– Talk and listen at same time

Musical Instrument Digital Interface (MIDI) support– Wavetable synthesis

• Actual recordings

– FM synthesis• Imitated sounds

TV Tuner Cards

Require a video card to operate

Scanners A scanner is a device that reads

images and text into a computer– Most scanners come with Optical

Character Recognition (OCR) software. This software places scanned text into a document that can be edited in a word processor

– Color dept is measured in bits and indicates the number of colors a scanner can detect

• 36 bit color depth is acceptable

Resolution

Resolution determines the amount of detail a scanner can detect

• Ranges from 600 dpi to 2400 dpi

• You usually don’t need to scan at a higher resolution than a printer can produce or a monitor can display

– Most monitors are 73 dpi

– Printers vary

Cameras

Resolution is measured in megapixels– 1000 x 1000 pixels– 1, 2 and 3 megapixel cameras are available

Digital video cameras use a Charged Coupling Device (CCD) to capture video– Quality depend on amount of detail a CCD can detect

• Most CCD’s have resolution between 250,000 and 700,000 pixels

Web cameras – resolution and speed determine quality of image– Common transfer rates– 15 frames per second at 640 x 480 pixels– 30 frames per second at 352 x 288 (clearer but smaller)

MP3

Sound format used to CD-quality music over the Internet– Compresses sound

Commonly 64 bit memory

USB and Firewire

High-speed ports that allow information to quickly transfer between a computer and an external device– USB

• Supports up to 127 device– USB 1.0: 12 megabits per second

– USB 2.0: 480 Mbps

– FIREWIRE• 63 devices at 400 Mbps

• Can purchase Firewire expansion card

ProcessingProcessing

Chapter 3

CPU Central Processing Unit Processes instructions, performs calculations,

and manages the flow of information through a computer system

Performance:– Each generation of CPU is more powerful than the

one before– CPU speed is a major factor in determining how fast

a computer operates (faster the speed, faster computer operates)

• Measured in megahertz (MHz)

Processing

The Central Processing Unit (CPU) is the main chip in a computer– Processes instructions– Performs calculations– Manages the flow of information

Types of CPUs Intel Pentium Processor

– Speeds of 450 MHz to 1.13 GHz

Intel Celeron– Needs of home machines (500-700MHz)

AMD Athlon Processor– Business and home use

AMD Duron Processor– Home use

VIA Cyrix Processor– Inexpensive CPU

Processing Random Access Memory – Temporarily stores data

inside a computer– Constantly overwritten– Measured in megabytes (MB)

• 64 minimum these days100 MHz (millions of cycles per second)

– Dynamic RAM is type of memory chip that makes up memory in many computer systems. Access speed measured in megabits

• Most system boards can support access speed of Single Inline Memory Module (SIMM) – 9 memory chips

• Dual Inline Module (DIMM) – 18 memory chips

If you have limited memory or you have many programs open, your computer may need to use part of the hard drive to simulate more memory

Using Memory Cache

1. Look through documents on your desk (internal cache)

2. Look through documents in your desk drawer (external cache)

3. Looking through documents in your filing cabinet (RAM)

Using Memory Cache

1. Look through documents on your desk (internal cache)

2. Look through documents in your desk drawer (external cache)

3. Looking through documents in your filing cabinet (RAM)

Storage DevicesStorage Devices

Chapter 4

Memory Cache

Speeds up computer by storing data the computer has recently used– Internal Cache: On CPU chip (L1 or primary cache– External Cache: On the system board and consists of

Static RAM (SRAM chips)• Sometimes built into chip

RAM – slower main memory– Each time the computer requests data from RAM, the

computer places a copy of the data in memory cache• Constantly contains the most recently used data

BUS

Electronic pathway that carries information between devices in a computer– Bus Width (think lanes of a highway)

• 8 bits is one character

– Bus Speed (think speed limit)• Measured in MHz (millions of cycles per second)

Bus Types

ISA (Industry Standard Architecture)– Slowest and oldest– 16 bits; 8MHz (millions of cycles per second)– Pentium, Pentium II

PCI (Peripheral Component Interconnect)– 32 or 64 bits– 66 MHz– Support Plug and Play– Pentium II, III, 4

AGP (Accelerated Graphics Port)– Between video card and main memory– 32 bits; 66 MHz

Using a Hard Drive Correctly

Virus protection Backups Defragmentation

– Prevents files from being broken up for storage

Repairing a Disk Disk Cleanup Data compression

– Only if disk is running out of space

Hard Drives

Magnetically stores data on rotating disks called platters

Stores your operating system and programs Document will not be lost when you turn

off the computer Capacity is measured in bytes Speed is measured in revolutions per

minute

File Systems

File system determines how information is stored on a hard drive– FAT– FAT32– NTFS

Connection Types

EIDE (Enhanced Integrated Drive Electronics) – Called IDE– Supports total of 4 devices (any drives)– Ultra Direct Memory Access (UDMA) is enhanced

IDE

SCSI (Small Computer System Interface)– Called ‘scuzzy”– Supports 7 devices– Expensive

Relation of Cache & Hard Drives

Disk cache speeds up the computer by storing the data the computer has most recently used– Constantly updated– Area of memory– Fast access– Then hard drive is searched

Floppy Drives and Drives

Removable media– Can be write-protected– Can be damaged magnetically

CD-ROM

ROM (Read-only memory) - can’t be changed 650 Mb of data

– Equal to entire set of encyclopedias– 400 Floppy disks– Music, games, software installs

Speed determines how fast a disk spins– Look for 24X

Speed of CD-ROM drive is the transfer rate– In Kb (e.g. 3600Kbs)

CD-R & CD-RW Drives

CD-R (Compact Disc – Recordable)– Permanent store; not erasable

CD-RW – Can be erased and rewritten– Read / Write and Re-write speeds– Usually 74 minutes

Special software needed to record onto a disk– Referred to as burning a CD

DVD-ROM Drive

DVD – Digital Versatile Disk– Generally cannot change the information stored on a

disk– Similar to CD but stores more information– Speed determines transfer rate (6 X)– Capacity

• 1 side / 1 layer – 4.7 GB

• 1 side / 2 layer – 8.5 GB

• 2 sides / 1 layer – 9.4 GB

• 2 sides / 2 layers – 17 GB

Tape Drive

Backup helps you copy files to tape cartridges Tape drives come with backup programs Schedule backups to run at night

– Backup programs compress data together Try to find a drive that can store the entire

contents of your hard drive Travan drives are the most common type of tape

drives – 10 GB DAT drives are faster than a Travan – 24GB

Tape Backups

Full Incremental

Removable Storage Devices

Jazz Drive – 2 GB Zip Drive – 250 MB LS-120 Drive – 120 MB

SoftwareSoftware

Chapter 5

Software

Software helps you accomplish specific tasks Manufacturers also may create minor software updates called

patches, to make corrections or improvements to software Application software:

– Word processor helps you create professional looking documents quickly and efficiently

• Documents

• Editing

• Printing

• Formatting

• Tables

• Images

• Mail merge

Spreadsheets

Perhaps the original ‘killer app’– Manage finances on your computer– Manage data in a list

Funtions– Formatting– Editing– Formatting– Formulas and calculations– Charts

Database Programs

Helps you manage large collections of information– Phone directories– Product listings– Payroll information

Features– Store information– Find information– Analyze and print information

Databases

Organized in: – Tables

• Collection of information about a specific topic

– Field• Category of information

– Record• Single instance of information

Application Suites

Word processing Spreadsheet program Presentation program Information management program

– Mail, calendars, address book

Database program

Utility Programs

Utility: A program that performs a specific task on your computer– Norton utilities: recover files– Virusscan: anti-virus– Acrobat Reader: View PDF (Portable Document

Format) files– Winfax pro– ViaVoice – Speech recognition– WinZip – Compress and decompress files

Operating SystemsOperating Systems

Chapter 6

Operating Systems

Software that controls the overall activity of the computer– Ensure that all of the parts of the computer work

together smoothly– Functions:

• Control hardware

• Run software

• Manage information

– Programs that run on one operating system platform do not generally run on others

Types of Operating Systems

MS-DOS• Command driven

Windows– Windows 3.1– Windows 9X (95, 98)– Windows ME– Windows XP– Windows NT– Windows 2000

• GUI – “Graphical User Interface”

UNIX MAC OS

MS-DOS

Characterized by the C:\> prompt Cursor is the flashing line on the screen

where you type File Organization: Root directory is C:\

– Path describes the location of a file

Files: Name is 8; extension is 3

Windows 3.1

Not technically an operating system– Works with MS-DOS

Program Manager is the control center File Manager used to organize files Desktop – Background area

Windows 95

True operating system – eliminated reliance on DOS

My Computer lets you browse all folders and documents

START button allows you to quickly access programs and documents

Windows Explorer: Shows the location of each folder and document on the computer

Windows -98

Similar to Windows-95 More reliable than Windows-95 Has multiple monitor capability Uses FAT32 file system Includes Internet functionality

• Explorer• Outlook Express• Front Page Express

Windows ME

Millennium Edition Similar to 98 Added features

– Record videos using Windows Movie Maker– Manage Multimedia Files with Media Player– Restore your computer– Set up a home network– Phone home

Windows XP Windows XP, which is available in Home and

Professional editions, was released in October. Windows XP Professional is intended to replace Windows 2000 Professional. Windows XP Home Edition was designed as the upgrade for the Windows 95, 98 and Me line.

Although the two systems run on the same kernel, or engine that drives the operating system,Windows XP has many features that are not included in Windows 2000.

• System Restore• Built-in Firewall• Much more graphic• NT look and feel• Multiple users• CD-RW functionality

Windows NT

Features advanced networking and security Separates Workstations and Servers Runs Windows-9X programs Workstations communicating with NT can run:

– NT– Linux– Win 9X– Mac OS 9

Windows 2000

Supports larger network Server and client re-united

UNIX

Can run single computer or entire network Developed on mainframes in late ’60’s Versions:

– SCO– Solaris– Linux– HP-UX– AIX

Most widely used operating system on Internet

Unix Features

Harder to install but provides more power and control

True multi-tasking OS Security

LINUX

Unix-based system offered as freeware on the Internet– Can purchase from Red Hat, Corel or mandrake

Can be set up with GUI operating system called GNOME or as a command line system

Features:– Software analogous to Windows available– Accounts for root and personal functions are available

MAC OS

Version 9– Advanced sound, video and graphics– Internet (Sherlock2)

Version 10– New GUI

• Includes dock for frequently accessed items

– Graphics: PDF, QuickTime and OpenGL– Improved operating system Kernel

Portable ComputersPortable Computers

Chapter 7

Notebook Computes

Small lightweight computer you can easily transport– Built-in keyboard and pointing devices

Batteries– Nickel-metal hydride (NiMH)– Lithium Ion

• More expensive but lighter and stronger

– Last only a few hours

Laptop Features

Screens– Uses liquid crystal display (LCD)– Measured diagonally– Backlit– Can use a full-size monitor– Types

• Passive Matrix– Hard to view from an angle

• Dual-Scan• Active Matrix (also called a Thin Film Transistor)

– Can be view from oblique angles

Laptop Features

Input / Output Devices– There are several device that let you move the pointer

around the screen of a notebook computer• Pointing stick

• Trackball

• Touchpad

– Keyboards– Modem– Sound card and speakers

Laptop Features

Input / Output Devices– There are several device that let you move the pointer

around the screen of a notebook computer• Pointing stick

• Trackball

• Touchpad

– Keyboards– Modem– Sound card and speakers

Laptop Features

Storage Devices– Hard Drive– CD-ROM or DVD-ROM– Floppy Drives– External Drives– PC cards: Personal Computer Memory Card

international Association (PCMCIA)• Compact Flash Memory

Processing

The Central Processing Unit (CPU) is the main chip in a computer– Processes instructions– Performs calculations– Manages the flow of information

PC Cards

A PC Card adds a new capability such as memory, different devices or connectivity to a laptop– Type I, II, III– Can have one Type III card or two Type I or

IIs

Other Features

Network Interface Card Infrared port Port Replicator

– Lets you connect many devices to a notebook at once

Docking station adds a keyboard and a full-size monitor to the port replicator

Introduction to Handhelds

Portable computer small enough to carry– Called a Personal Digital Assistant (PDA)– Popular Handhelds

• Palm

• Visor

• CI

– Features• Stylus

• Collapsible keyboards

• Wireless modems

Handheld Systems

Operating Systems– Palm OS– Windows CE

Electronic organizers Information exchanges Other technologies

– Smart phones– RIM BlackBerry – two-way paging

Macintosh ComputersMacintosh Computers

Chapter 8

Macintosh Examined First computers with mouse and GUI Advantages

– Ease of use– WYSIWYG (what you see is what you get)

Types– Power Mac (G4)– Cube – Quarter-size– iMac – all-in-one– PowerBook

OS– Versions 9 & 10

Ports

Connectors for external devices– FireWire

• 63 devices• High speed for multimedia like cameras and external drives

– USB Port• 127 devices

– Network Port– Speaker Port– Microphone Port– Monitor Port

I/O Devices

Mouse Keyboard Monitor Video Sound Printer Modem Imaging

Processing

All new Macintosh computers use PowerPC microprocessors called Reduced Instruction Set Computer Chips (RISC)

Types of CPUs:– G3– G4 – may be in tandem

BUS: Peripheral Component Interconnect(PCI) bus with width of 32 or 64 bits and speed up to 64 MHz

128 mb of RAM is recommended

NetworksNetworks

Chapter 9

What Is a Network

A network is a group of connected computers that allow people to share information and equipment

Types of Networks

LAN (Local Area Network) connects computers within a small geographic area like a building

WAN (Wide Area Network) connects computers across a large geographic area like a city or country (often via satellite)

Internet: World-wide network of networks

Advantages

Road warriors Eliminate “sneakernet” Share information Share equipment

Who Runs It?

A network administrator manages the network and makes sure it runs smoothly– Often called a systems administrator or an IS

manager

Network Applications

Electronic mail Groupware

– Calendaring– Scheduling

Video-conferencing– Requires sound card, speakers, mike & camera

Physical Networking

Hubs– A hub is a device that provides a central location

where all the cables on a network come together NICs (Network Interface Card)

– An expansion card that physically connects each computer to the network

Cables– Coaxial, Unshielded Twisted Pair (UTP), Shielded

Twisted Pair, Fiber-optic– Wireless

How Information Is Stored

Client-Server:– Used for large networks– Files are stored on a central computer and everyone

who can access the network can be given access them• Easy to create scheme to backup and protect files

– Client: a computer that can access information stored on the server

– Server: Central computer that stores files– NetWare, UNIX, Windows NT/2000

How Information Is Stored

Peer-to-Peer:– Used for a small number of computes (e.g. 10)– Files stored on own computers; access given

to them to others on the network– LANtastic, Windows-98, Windows-ME

How Information Is Exchanged

Ethernet:– Most popular and least expensive solution– Each computer waits for a pause before

sending information• Like polite conversation

– Collisions between information often occur• Computers wait a moment, then resend

– Ethernet – 10 Mbps, Fast Ethernet – 100 Mbps, Gigabit Ethernet 1000 Mbps

How Information Is Exchanged

Token-ring is a type of network where a token that collects and delivers information is passed from compute to computer– Speeds of 4 or 16 Mbps

Asynchronous Transfer Mode (ATM) is a type of network that works by sending information in equal-sized pieces called cells– 25, 155, 622 or 2488 Mbps– Often networks networks

Network Security

Firewall – specialized hardware or software package designed to protect a private computer network from unauthorized access– Think “Moat”

User name and password– Used for authentication– Good passwords

Intranet

Small version of the Internet in a company Uses familiar web-browsers and email

packages Allows hyper-linking VPNs (Virtual Private Network)

– End-to-end encryption– More cost efficient than private lines

Internet and WWWInternet and WWW

Chapter 10

Internet Fundamentals

Dates from DARPA in the 1960s Consists of thousands of connected networks

around the world– Each organization on the Internet is responsible for

maintaining its own equipment• These organizations allow you to pass-through their nets

Designed to provide multiple routing to bypass disabled computers

Called cyber-space or the information superhighway

Internet Offerings

Electronic mail (Most popular application) Information Entertainment Discussion Groups Chat Programs (Shareware) Online shopping

Connecting

Computer Software Modem or high-speed connection ISP (Internet Service Provider)

– Access for a fee

World Wide Web

Part of the Internet consisting of a huge collection of documents stored on computers around the world– Web server: computer that stores and delivers web

pages– Web site: collection of web pages

• URL (Uniform Resource Locator) – unique address– HTTP, Computer, Directory, Name of Page

– Hyperlinks jump to different web pages

Browsers

A program that lets you view and navigate information on the World Wide Web– Home Page: Web page that appears each time you

start your web browser– Browser:

• Internet Explorer

• Netscape Navigator

– Features• Bookmark

• History lists

Multimedia

MP3 – compressed files containing music or video– WinAmp

Streaming video – requires player– RealPlayer, QuickTime

Enhancements– Java– JavaScript– ActiveX

Web Portal

Central starting point for browsing personalized by the individual– Yahoo, Excite, Go, Lycos– Info– Free services like email, shopping, chat,

games, stock quotes and sports scores

Shopping

Auctions Secure web sites – i.e. HTTPS

Children on the Web

Inappropriate information– Pictures– Documents

Protection– Adult supervision– Browser restrictions– Restriction programs

• CyberPatrol

• NetNanny

Create & Publish Web Pages

HyperText Mark-up Language is a computer code used to create Web pages

There are many programs available, called visual editors which can help you create Web pages without having to learn HTML

Publishing your pages – loaded to an addressable server

Electronic Mail & Electronic Mail & Mailing ListsMailing Lists

Chapter 11

E-Mail

E-mail is a fast, economical and convenient way to send messages to family, friends and colleagues

Addresses– Location of an individual mailbox on the

Internet– User name, @ sign, domain – no spaces

Web-based E-mail

Don’t need email client Popular Web-based E-mail Services

– www.hotmail.com– www.email.com– mail.yahoo.com

Organization

By type:• .com

• .edu

• .gov

• .mil

• .net

• .org

By country• Australia - .au

• Canada - .ca

• Ireland - .ie

• Italy - .it

• Japan - .jp

• United Kingdom - .uk

Other new codes have been defined

E-mail Features

Address books Signatures Attachment of files

– Try to keep under 50Kb– Sometimes certain types of files are

screened

E-Mail Issues

Emoticons :-) Abbreviations

– LOL – TTFN

Netiquette– Shouting– Flame

Viruses

An e-mail virus is a program that can disrupt the normal operation of a computer– Display of unusual messages– Destroying files on the hard drive– Sending mail to people in your address book

Opening files; sometimes only in preview Virus programs available commercially

– Must be kept up-to-date

Newsgroups and ChatNewsgroups and Chat

Chapter 12

Mail Groups

A mailing list is a discussion group that uses e-mail to communicate– A list of mailing lists is at www.liszt.com

Moderated vs. un-moderated lists Must subscribe to participate Two addresses

– Mailing list addresses– Administrative addresses

Newsgroups

A discussion group that allows people with common interests to communicate with each other

USENET (User’s Network)– All the computes that distribute newsgroup

information Messages

– Individual posts Threads

– Messages and all replies

Addressing

First word describes the main topic Each additional word is separated by a dot

and serves to narrow the topic

Networking Aspects

Newsreader – program that lets you read and post online– Microsoft Outlook has a built-in reader– Gravity– Free Agent

News server– A computer that stores newsgroup messages

Newsgroup Categories

alt

biz

comp

misc

rec

sci

Soc

talk

General Interest Business Computers Miscellaneous Recreation & Hobbies Science Social

(culture/politics) Debate

• alt.fans.actors

• biz.entrepreneurs

• comp.security.misc

• misc.books.technical

• rec.food.recipes

• sci.physics

• soc.history

• talk.politics.misc

Newsgroup Etiquette

Lurk first Read FAQ Reply Send a private reply

Chatting

One of the most popular features on the Internet (but no one admits to doing it)

Text-based Multi-media

– Internet Relay Chat (IRC) channels• Need a program to participate (www.mirc.com)

Instant messaging allows you to communicate privately with others– MSN or AOL