concepts sem i

8/3/2019 Concepts Sem I

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Interacting with Computer

This lesson includes the following sections:

The Keyboard

The Mouse

Variants of the Mouse


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A standard computer keyboard has about 100 keys.

Most keyboards use the QWERTY layout, named for

the first six keys in the top row of letters.

The Keyboard - Standard Keyboard Layout


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5. Cursor-movement keys

4. Modifier keys

3. Function keys

2. Numeric keypad

1. Alphanumeric keys

Most keyboards have keys arranged in five groups:



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* * * * *



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The Keyboard - How a Keyboard Works

Key Board

Keyboard Controller Keyboard

BufferSystem Software

(Operating System)

CPU


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The Mouse

All modern computers have a variant

Allows users to select objects

The mouse is a pointing device. You use

it to move a graphical pointer on the

screen.

The mouse can be used to issue

commands, draw, and perform othertypes of input tasks.


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The Mouse - Mouse Techniques

1. Pointing; Move the mouse to move the on-screen pointer.

2. Clicking; Press and release the left mouse button

once.

3. Double-clicking; Press and release the left mouse

button twice.

4. Dragging; Hold down the left mouse button as youmove the pointer.

5. Right-clicking; Press and release the right mouse button.

Using the mouse involves five techniques:


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The Mouse

Mechanical mouse

Rubber ball determines direction and speed

The ball often requires cleaning

Optical mouse Light shown onto mouse pad

Reflection determines speed and direction

Requires little maintenance


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The Mouse

Benefits

Pointer positioning is fast

Menu interaction is easy

Users can draw electronically


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Trackballs

Upside down mouse

Hand rests on the ball

User moves the ball

Uses little desk space


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Track pads

Stationary pointing

device

Small plastic

rectangle

Finger moves across

the pad

Pointer moves with

the pointer Popular on laptops


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Track point

Little joystick on the keyboard

Move pointer by moving the joystick


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Inputting Data In Other Ways


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Devices for the Hand

Pen based input

Tablet PCs, PDA

Pen used to

write data

Pen used as

a pointer

Handwriting

recognition

On screen keyboard


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Devices for the hand

Touch screens

Sensors determine

where finger points

Sensors create an

X,Y coordinate

Usually presents a

menu to users

Found in cramped or

dirty environments


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Devices for the hand

Game controllers

Enhances gaming experience

Provide custom input to the game

Modern controllers offer feedback Joystick

Game pad


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Optical Input Devices

Allows the computer to see input

Bar code readers

Converts bar codes to numbers

UPC code

Computer find number in a database

Works by reflecting light

Amount of reflected light indicates number


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Optical Input Devices

Image scanners

Converts printed media into electronic

Reflects light off of the image

Sensors read the intensity Filters determine color depths


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Optical input devices

Optical character recognition (OCR)

Converts scanned text into editable text

Each letter is scanned

Letters are compared to known letters Best match is entered into document

Rarely 100% accurate


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Audiovisual Input Devices

Microphones

Used to record speech

Speech recognition

Understands human speech Allows dictation or control of computer

Matches spoken sound to known phonemes

Enters best match into document


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Musical Instrument Digital Interface

MIDI

Connects musical instruments to computer

Digital recording or playback of music Musicians can produce professional results


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Digital cameras

Captures images electronically

No film is needed

Image is stored as a JPG file Memory cards store the images

Used in a variety of professions


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Output Devices

Hard copy output :

The data consisting of text or

graphics that is obtained as printouts or

microfilm using printers or plotters isknown as hardcopy.

Soft copy output:

The data that is stored in a storagedevice such as floppy disk, hard disk,

CD-ROM magnetic tape and so on is

called softcopy.


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Monitors

Most common output device

Connects to the video card

Categorized by color output

Monochrome

One color with black background

Grayscale

Varying degrees of gray Color

Display 4 to 16 million colors


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Monitors

Cathode Ray Tube (CRT)

Most common type of monitor

Electrons fired from the back

Electrons excite phosphor to glow Phosphor is arranged in dots called pixels

Dot mask ensures proper pixel is lit


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CRT Monitors

Electron Gun

Magnetic Yoke

Phosphor coated screen

Electron beam


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Monitors

CRT color

Phosphor dots arranged in triads

Red, green, and blue dots

Three colors blend to make colors Varying the intensity creates new colors


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Monitors

CRT drawbacks

Very large

Very heavy

Use a lot of electricity


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Monitors

Liquid Crystal Display (LCD)

Commonly found on laptops

Desktop versions exist

Solve the problems of CRT Fluorescent lights provide illumination


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Monitors

Passive matrix LCD

Pixels arranged in a grid

Pixels are activated indirectly

Row and column are activated Animation can be blurry


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Monitors

Active matrix LCD

Each pixel is activated directly

Pixels have 4 transistors

One each for red, green, blue One for opaqueness

Transistors arranged in a thin film

Animation is crisp and clean


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Monitors

Drawbacks to LCD

More expensive than CRT

Must sit directly in front of screen

Can be more fragile than CRT


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Copyright 2006 by The McGraw-Hill Companies, Inc. All rights reserved.McGraw-Hill Technology Education

Chapter 4B

PrintingPrinting


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Commonly Used Printers

Impact printers

Generate output by striking the paper

Uses an inked ribbon

Non-impact printers Use methods other than force

Tend to be quiet and fast


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Dot matrix printers

Impact printer

Used to print to multi-sheet pages

Print head strikes inked ribbon Line printers

Band printers

Speed measured in characters per second


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Dot Matrix Print Head


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Dots Per Inch


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Laser printer Non-impact printer

Produces high quality documents

Color or black and white Print process

Laser draws text on page

Toner sticks to text

Toner melted to page

Speed measured in pages per minute

Quality expressed as dots per inch


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All-in-one peripherals Scanner, copier, printer and fax

Popular in home offices

Prices are very reasonable


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Comparing Printers

Determine what you need

Determine what you can spend

Initial cost

Cost of operating

Image quality

Speed


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High-Quality Printers

Plotters Large high quality blueprints

Older models draw with pens

Operational costs are low Output is very slow


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End of ChapterEnd of Chapter


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Operating SystemBasics

Operating SystemBasics


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Functions of Operating Systems

Provide a user interface

Run programs

Manage hardware devices

Organized file storage


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Types of Operating Systems

Real-time operating system Very fast small OS

Built into a device

Respond quickly to user input MP3 players, Medical devices


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Single user/Single tasking OS One user works on the system

Performs one task at a time

MS-DOS and Palm OS Take up little space on disk

Run on inexpensive computers


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Single user/Multitasking OS User performs many tasks at once

Most common form of OS

Windows XP and OS X Require expensive computers

Tend to be complex


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Providing a User Interface

User interface How a user interacts with a computer

Require different skill sets


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Graphical user interface (GUI) Most common interface

Windows, OS X, Gnome, KDE

Uses a mouse to control objects Uses a desktop metaphor

Shortcuts open programs or documents

Open documents have additional objects

Task switching

Dialog boxes allow directed input


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Graphical User Interface


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Command line interfaces Older interface

DOS, Linux, UNIX

User types commands at a prompt User must remember all commands

Included in all GUIs


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Command Line Interface


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Managing Hardware

Programs need to access hardware

Interrupts

CPU is stopped

Hardware device is accessed

Device drivers control the hardware


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Organizing Files and Folders

Organized storage

Long file names

Folders can be created and nested

All storage devices work consistently


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Survey of PC and

Network Operating

Systems

Survey of PC and

Network Operating

Systems


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PC Operating Systems

Microsoft Windows is the most popular Installed more than other OS combined

Installed on about 95% of computers

Apple and Linux represent the other 5%


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DOS Disk Operating System

Single user single-tasking OS

Command line interface 16-bit OS

Powerful

Fast

Supports legacy applications


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Windows NT Designed for a powerful system

32-bit OS

Very stable Windows NT Workstation

Single user multi tasking OS

Windows NT Server

Multi user multi tasking OS

Network operating system


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Windows 9x 95, 98, and Millennium Edition (Me)

32-bit OS

Supported 16-bit programs well Very pretty not stable OS

Still found in large corporations

95 introduced the Start button

98 introduced active desktop

Me improved multimedia software


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Windows 2000 Look of 9x with NT stability

Optimized for office and developers

Application software ran very well Entertainment software ran very poorly


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Windows XP Microsofts newest desktop product

Different look from 2000

Many different versions Digital multimedia support was enhanced

Communications was enhanced

Mobile computing became a priority


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UNIX Runs on all computer types

32- or 64-bit

Very stable and fast Command-line interface

Can cost thousands of dollars


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Linux Free or inexpensive version of UNIX

32-bit OS

Very stable and fast Most flavors are open source

X Windows GUI

Command line interface is available


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Chapter 9A

Network BasicsNetwork Basics


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Network Definition

Set of technologies that connectscomputers

Allows communication and collaboration

between users


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The Uses of a Network

Simultaneous access to data Data files are shared

Access can be limited

Shared files stored on a server Software can be shared

Site licenses

Network versions

Application servers


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Sharing Data

File server contains documentsFile server contains documents

used by other computers.used by other computers.


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Personal communication Email

Instantaneous communication

Conferencing Tele conferencing

Videoconferencing

Audio-conferencing

Data-conferencing Voice over IP

Phone communication over network wires


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Easier data backup Backup copies data to removable media

Server data backed up in one step


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Common Network Types

Local Area Network (LAN) Contains printers, servers and computers

Systems are close to each other

Contained in one office or building Organizations often have several LANS


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Common Network Types

Wide Area Networks (WAN) Two or more LANs connected

Over a large geographic area

Typically use public or leased lines Phone lines

Satellite

The Internet is a WAN


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Hybrid Network Types

Campus Area Networks (CAN) A LAN in one large geographic area

Resources related to the same organization

Each department shares the LAN


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Metropolitan Area Network (MAN) Large network that connects different

organizations

Shares regional resources A network provider sells time


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Home Area Network (HAN) Small scale network

Connects computers and entertainment

appliances Found mainly in the home

H b id N k T


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Personal Area Network (PAN) Very small scale network

Range is less than 2 meters

Cell phones, PDAs, MP3 players

H N t k A St t d


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How Networks Are Structured

Server based network Node is any network device

Servers control what the node accesses

Users gain access by logging in Server is the most important computer

H N t k A St t d


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How Networks Are Structured

Client/Server network Nodes and servers share data roles

Nodes are called clients

Servers are used to control access Database software

Access to data controlled by server

Server is the most important computer


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N t k T l i


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Network Topologies

Topology Logical layout of wires and equipment

Choice affects

Network performance Network size

Network collision detection

Several different types

N t k T l i


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Network Topologies

Packets Pieces of data transmitted over a network

Packets are created by sending node

Data is reassembled by receiving node

Packet header

Sending and receiving address

Packet payload

Number and size of data Actual data

Packet error control

N t k T l i


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Network Topologies

Bus topology Also called linear bus

One wire connects all nodes

Terminator ends the wires Advantages

Easy to setup

Small amount of wire

Disadvantages

Slow

Easy to crash

N t k T l i


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Network Topologies

Star topology All nodes connect to a hub

Packets sent to hub

Hub sends packet to destination

Advantages

Easy to setup

One cable can not crash network

Disadvantages One hub crashing downs entire network

Uses lots of cable

Most common topology

St T l


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Star Topology

N t k T l i


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Network Topologies

Ring topology Nodes connected in a circle

Tokens used to transmit data

Nodes must wait for token to send Advantages

Time to send data is known

No data collisions

Disadvantages Slow

Lots of cable

N t k T l i


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Network Topologies

Mesh topology All computers connected together

Internet is a mesh network

Advantage Data will always be delivered

Disadvantages

Lots of cable

Hard to setup

Mesh Topolog


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Mesh Topology

Network Media


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Network Media

Links that connect nodes Choice impacts

Speed

Security Size

Wire Based Media


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Wire Based Media

Twisted-pair cabling Most common LAN

cable

Called Cat5 or

100BaseT Four pairs of copper

cable twisted

May be shielded from

interference Speeds range from

1 Mbps to 1,000 Mbps

Wire Based Media


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Wire Based Media

Coaxial cable Similar to cable TV wire

One wire runs through cable

Shielded from interference Speeds up to 10 Mbps

Nearly obsolete

Wire Based Media


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Wire Based Media

Fiber-optic cable Data is transmitted

with light pulses

Glass strand instead

of cable Immune to

interference

Very secure

Hard to work with Speeds up to

100 Gbps

Wireless Media


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Wireless Media

Data transmitted through the air LANs use radio waves

WANs use microwave signals

Easy to setup

Difficult to secure

Network Hardware


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Network Hardware

Network interface cards Network adapter

Connects node to the media

Unique Machine Access Code (MAC)


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Network Hardware


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Network Hardware

Hubs Center of a star network

All nodes receive transmitted packets

Slow and insecure


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Network Hardware


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Network Hardware

Bridge Connects two or more LANs together

Packets sent to remote LAN cross

Other packets do not cross

Segments the network on MAC addresses

Network Hardware


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Network Hardware

Router Connects two or more LANs together

Packets sent to remote LAN cross

Network is segmented by IP address Connect internal networks to the Internet

Need configured before installation

Network Hardware


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Network Hardware

Gateway Connects two dissimilar networks

Connects coax to twisted pair

Most gateways contained in other devices

Network Cabling


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Network Cabling

Cabling specifications Bandwidth measures cable speed

Typically measured in Mbps

Maximum cable length

Connector describes the type of plug

Network Cabling


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Network Cabling

Ethernet Very popular cabling technology

10 Base T, 10Base2, 10Base5

Maximum bandwidth 10 Mbps Maximum distances100 to 500 meters

Network Cabling


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Network Cabling

Fast Ethernet Newer version of Ethernet

Bandwidth is 100 Mbps

Uses Cat5 or greater cable Sometimes called 100Base T

Requires a switch

Network Cabling


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Network Cabling

Gigabit Ethernet High bandwidth version of Ethernet

1 to 10 Gbps

Cat 5 or fiber optic cable Video applications

Network Cabling


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Network Cabling

Token ring Uses shielded twisted pair cabling

Bandwidth between 10 and 25 Mbps

Uses a multiple access unit (MAU) Popular in manufacturing and finance

Network Protocols


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Network Protocols

Language of the network Rules of communication

Error resolution

Defines collision and collision recovery Size of packet

Naming rules for computers

Network Protocols


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Network Protocols

TCP/IP Transmission Control Protocol/Internet

Protocol

Most popular protocol

Machines assigned a name of 4 numbers

IP address

209.8.166.179 is the White Houses web site

Dynamic Host Configuration Protocol Simplifies assignment of IP addresses

Required for Internet access

Network Protocols


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Network Protocols

Token ring Popular in manufacturing and finance

Nodes communicate when they have the

token

Chapter 9A


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Chapter 9A

End of ChapterEnd of Chapter

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