1 examine computer hardware and software. explore networks and data communications learn about...

1

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

Concepts Unit A: Objectives

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


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


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


Output devices:• Monitors

CRT monitors (almost obsolete) LCD and LED

• Printers• Others


Monitor’s quality Screen Size

(diagonal in inches)

Resolution (in pixels)

Setting the screen resolution.


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.

36Microsoft Office 2007-Illustrated Introductory, Premium Video Edition

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

Computer ports and connections

Power connection

Mouse port

FireWire port

Network port

Phone line connection

Speaker and microphone connections

USB ports

Monitor port

Audio connection

Keyboard port

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


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.


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?


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

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

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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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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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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


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.



Programming languages• Used by a programmer to

develop programs. • Most commonly used computer

language: C, C++, Java, C#, Visual Basic, Fortran…



Drive and Driver• Drive --- Hardware• Driver --- software to “drive” a

specific drive. Examples:

Hard (disk) drive --- Hard (disk) driverUSB drive --- USB driverPrinter --- Printer driver


Windows Vista starting screen

Icons (you might see additional

icons on your

screen)

Start button

Taskbar

Quick Launch toolbar

Gadgets (small programs; you might see additional or different gadgets on your 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


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


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 high-speed 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

Using modems to send and receive data

Sending site

Digital signal

Modem

Analog signal

Modem

Digital signal

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

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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

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

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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 fromwww.microsoft.com/security_essential

SE is free and works well!

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.


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.

1 examine computer hardware and software. explore networks and data communications learn about...

Documents

computer hardware

cpus slide

storage computer

output slide

car slide

computer memory

powerful computers

fastest computers