introduction to computer system جامعة أم القرى قسم السنة التحضيريه...

Introduction To Computer System

القرى أم جامعةالتحضيريه السنة قسم

التدريس: هيئة أعضاء اعداد

Computer Generations

First Second Third Fourth

Computer Generations

First Second Third Fourth

Years 1951-1958 1959-1964 1965-1970 1971-

Technology Vacuum Tubes

Transistor Integrated Circuits

Large Scale Integrated Circuits

I/O Cards Tape Disks Variety

Size Room Closet Desk Small

$ per million $10 $1 $0.10 $0.0001 or less

The First Transistor (1948)

IBM 360 Computer System

IBM 704

Used discrete

transistors

IBM 709 Mainframe

Last of the vacuum

tube computers,

c. 1959

Digital Equipment Corp

Left: DEC PDP-8, c. 1965

Right: DEC PDP-11, c. 1970

Computer

What is the Computer ?The Computer is a set of independent physical components and devices (Hardware), which have a specific job to do for each one and working together by Software to make up the computer system.

Computer perform three main operations:

Computer Classifications (types)

Microcomputer Minicomputer Mainframe Supercomputer

Microcomputer

Users: One Speed: Slow Price: $500 - $3,000 Size: desktop or smaller Examples: IBM PC, Apple ][, Apple

Macintosh, Imac “personal computers”

Minicomputer

Users: 2 - 50 Speed: Faster Price: $10,000 - $250,000 Size: file cabinet Examples: HP 9000

DEC VAX “departmental computers”

Mainframe Computer

Users: 50 + Speed: Fast Price: $500,000 - millions Size: refrigerator-sized on up Examples: IBM 3090, Unisys 2200

company-wide (“enterprise”)

Supercomputer

Users: a few Speed: very, very fast Price: $ millions Size: room Examples: Cray, Fujitsu

scientific uses

Understand the Terms Intelligent and Dumb Terminal.

An intelligent terminal, for example a PC: -– Performs a lot of the processing locally– You could use a PC, linked to a mainframe

A dumb terminal: -– Has very limited processing capabilities itself,

but allows you to connect to a large powerful computer such as a mainframe.

– When you process your data from the dumb terminal, it is the mainframe at the other end of the network that is performing all the calculations.

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HARDWARE

SOFTWARE

Look inside the computer

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Computers are made of

1. HARDWARE 2. SOFTWARE

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Hardware

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Hardware

The parts of computer itself (tangible objects ) including :

CPU (or Processor) and Primary memory (or Main Memory)

Input devices i.e the keyboard and mouse

Output devices Storage devices

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The Case (System Unit or System Cabinet)

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Hardware

1. Central Processing Unit (CPU)2. Input units3. Output units4. Memory (Main or Primary Memory &

Secondary or Auxiliary Memory)

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Components of a Computer System

Central Processing Unit (CPU)

Central Processing Unit (CPU)

control unit (CU)

ArithmeticlogicUnit (ALU)

RAM

ROM

MemoryMemory

Inputunits

output units

Auxiliary

Memory

Data

Information/Knowledge

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Hardware Organization

motherboard

CPU

memory

hard drive

Input Devices ...

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Input Devices

• Translate data from form that humans understand to one that the computer can work with

• Most common are keyboard and mouse

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Examples of Input Devices

1. Keyboard 2. Mouse 3. Scanner 4. Pre-storage Devise (Disk, CD’s, … etc.) 5. Optical mark recognition (Light Pin ,

Bar code scanners) 6. Microphone 7. Joystick .

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8. Point and Draw devices 9. Trackball10. Touchpad11. Touch screen 12. Magnetic stripes and smart

cars. 13. Digital Cameras

Examples of Input Devices(2)

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Hardware Organization

CPU

memory

hard drive

للفهم فقط مطلوبة غير

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RAM

Mother-Board (or Main Board)

CPU

ROM

للفهم فقط مطلوبة غير

للفهم فقط مطلوبة غير

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Hardware Organization

motherboard

CPU

memory

hard driveللفهم فقط مطلوبة غير

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Central Processing Unit (CPU)

• A specific chip or the processora CPU's performance is determined by the rest of the computers circuitry and chips.

• The Central Processing Unit (CPU) performs the actual processing of data

• The speed (clock speed) of CPU measured by Hertz (MHz)

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The CPU consists of :

Control Unit (CU) Arithmetic and Logical Unit

(ALU) Some Registers

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Central Processing Unit (CPU)Central Processing Unit (CPU)

Control Unit (CU)

Arithmetic Logic Unit (ALU)

Registers

Central Processing Unit (CPU)

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The Control Unit (CU) :

coordinates all activities of the computer by:

Determining which operations to perform and in what order to carry them out.

The CU transmits coordinating control signals to other computer components.

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The ALU :

consists of electronic circuitry to perform:

Arithmetic operations (addition, subtraction, multiplication and division)

Logical operations (and, or, not, …) and to make some comparisons (less-than, equal, … etc.)

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Hardware Organization

motherboard

CPU

memory

hard drive

للفهم فقط مطلوبة غير

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Primary Memory

Memory (fast, expensive, short-term memory): Enables a computer to store, at least temporarily, data, programs, and intermediate results.

Two general parts:1. RAM 2. ROM

Know How Computer Memory Is Measured

Bit– All computers work on a binary numbering system, i.e. they

process data in one's or zero's. This 1 or 0 level of storage is called a bit.

Byte– A byte consists of eight bits.

Kilobyte– A kilobyte (KB) consists of 1024 bytes.

Megabyte– A megabyte (MB) consists of 1024 kilobytes.

Gigabyte– A gigabyte (GB) consists of 1024 megabytes.

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Main Memory

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RAM (Main Memory)

its a primary storage or random access memory (RAM).

it temporarily holds data and programs for use during processing (volatile)

Any information stored in RAM is lost when the computer is turned off.

RAM is the memory that the computer uses to temporarily store the information as it is being processed. The more information being processed the more RAM the computer needs.

RAM consists of locations or cells. Each cell has a unique address which distinguishes it from other cells.

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ROM: Read Only Memory

ROM is part of memory Programmed at manufacturing time Its contents cannot be changed by users It is a permanent store

Q: Mention some examples of ROM?A: (PROM & EPROM )

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Other Kind of Memory

PROM: Programmable Read Only Memory. EPROM: Erasable Programmable Read Only

Memory Cache Memory Registers: not part of the main memory.

Q : Registers are part of “ …… ” ?

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Secondary StorageSecondary Storage

Stores data and programs permanently: its retained after the power is turned off

Examples• Hard Drive (Hard Disk)

Located outside the CPU, but most often contained in the system cabinet

• Floppy Disk• Optical Laser Discs

CD-ROM, CD-RW, and DVD

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Kinds of Disk DrivesDrives

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Common Secondary Media

• DiskettesDiskettes– Data represented as magnetic spots on

removable flexible plastic disks– Most common size is 3 1/2 inches, in a rigid

plastic case – Disk drive holds the diskette, reads or

retrieves the data and writes or stores data

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Common Secondary MediaCommon Secondary Media

• Hard drive– Data is represented magnetically as

with diskettes– Normally more than one rigid platterplatter

in a sealed unit– These disksdisks are not removablenot removable– Significantly more capacity and faster

operating than diskettes

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Optical Laser Discs

CD ROM & DVD’s Data is represented as pits and lands Some kinds are read only (CD-ROM) and some

Kinds are rewritable (CD-RW) Significantly more capacity and faster operating

than diskettes

DVD: Digital Video Disk

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Disk sizeAmount of storageApproximate printed 8.5 x 11 inch pages

5.25 low density360 Kb180 pages

3.5 low density720 Kb360 pages

5.25 high density1.2 Mb600 pages

3.5 high density1.44 Mb720 pages

CD700 MBa small library

DVD8.5 GBa feature length movie

Common Secondary MediaCommon Secondary Media

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tapes Panasonic's LS120 3.5 inch diskettes3.5 inch diskettes Iomega's Zip & Jazz disks VCR tape (Video Cassette Recorder ) Flash USB disks MMC (Multi Media Card ) SD

Common Secondary Media

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Hardware Organization

CPU

memory

hard drive

Output …للفهم فقط مطلوبة غير

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Output Devices

Pieces of equipment that translate the processed information fromfrom the CPU intointo a form that humans can understand.

CPUPr

oces

sed

info

rmat

ion

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Output Devices

Monitors Printers

Dot matrix printers Ink jet printers Laser printers

Sound Blasters (Sound Card By Creative Lab)

Controlling other devices

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Software

The instructions that tell the computer what to do

1. Application Software - helps end-users perform general purpose tasks

2. System Software - enables application software to interact with the computer

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System Software

The most important

System Software is the

Operating SystemOperating System

Examples of operating systems:Windows XP, DOS, Apple, UNIX

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System Software

• The software that controls everything that happens in a computer.

• Background software, manages the computer’s internal resources

Resources examples : CPU, RAM , I/O devices, …

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All hardware and software are under the All hardware and software are under the control of the operating systemcontrol of the operating system. Among other things, the operating the operating system:system:

1. Determines how valuable RAM is allotted to programs.

2. Performs tasks related to file management.3. Sets priorities for handling tasks.4. Manages the flow of instructions, data and

information to and from the processor (CPU).

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Examples ofExamples of Microcomputer Operating System Software

• DOS - original standard for IBM compatibles

• Windows - a graphical operating environment Windows VISTA, XP, millennium,

2000, 98, and 95

Continue …Continue …

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• Windows NT - for powerful workstations & networks

• OS/2 - competitor to Windows 2000• Macintosh Operating System• Unix - originally for minicomputers, now

used on microcomputers and Internet servers

QuestionQuestion: List some examples of operating systems ?

Examples ofExamples of Microcomputer Operating System Software ContCont..

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Application SoftwareApplication Software

• Packaged - “off the shelf”, pre-written programs ( General

purpose)• Custom - written for an

organization’s specific purpose (Special purpose)

Packaged Custom

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Application SoftwareApplication Software – Basic Tools – Basic Tools

• Word processors– example: example: Microsoft wordMicrosoft word

• Spreadsheets-- example: example: Microsoft ExcelMicrosoft Excel

• Database managers-- example: example: Microsoft AccessMicrosoft Access

• Graphics-- example: PhotoshopPhotoshopSpreadsheets: Computer software that allows the user to

enter columns and rows of numbers in a accounting book like format.

Internet

Talk Flow!

Introduction to the Internet– Brief history– Explaining basic protocols– Naming on the net

HTML Using search engines Questions

What is the Internet?

A Network of Computer Networks– Started as early as the 1960s– Built to work even if a large part of the network

fails

Internet

Network

Internet

Internet

Network

World Wide Web?

A part of the Internet– www1, www2 etc.,

Based on hypertext and hypertext transfer protocol (HTML & HTTP)

Supports multiple media - Multimedia Interactive, dynamic HTML

Brief History of the Internet

1960s - Department of Defense initiative ARPANET

1973 - ARPA launches the Internetting Project to explore the possibilities of linking networks

1980 – First Virus halts the Internet 1984 – DNS Introduced (Names rather than

numbers) 1999 – Internet Banking

Services through the net

Major services:– Email – Electronic Mail– FTP – File Transfer Protocol– Gopher (TCP/IP)– Newsgroups– Telnet – Remote session– WAIS – Wide Area Information System– WWW – World Wide Web

How to read an URL

http://www.uqu.edu.sa/cs100/windows.htm

specifies the protocol as http,

the host or WWW server as uqu.edu.jo

and the document as /cs100/windows.htm

Getting a Domain Name?

Top Domains:– edu – Educational Institutions– com – Company / Commercial Organizations– org – Non-profit Organizations– net – Network, network of sites– mil – Military Installations– gov – Government sites

Sub Domains:– sa- Saudi Arabia– jo - Jordan– uk – United Kingdom

Identifying a PC on the Internet

IP Number– 220.226.64.35– 10.15.3.20 (Intranet, Local IP)

To find your IP number on Windows– Execute ipconfig on your command prompt – XP

Hypertext

Hypertext, a method of preparing text that allows readers to choose their own pathways through the material, is invented by Ted Nelson.

The underlined word represents a hyperlink that lets the reader click and jump to a new page.

Provides interactive browsing

Browsers

Browser software allows us to view, hear, retrieve information created for the web

Internet Explorer, Netscape Navigator, Lynx

Computer VirusesComputer Viruses

Computer Viruses

– A computer virus is an application program designed and written to destroy other programs.

– It has the ability to: Link itself to other programs Copy itself (it looks as if it repeats itself)

Examples of Viruses

Monkes ABC Crabs CIH

Viruses and Virus Protection

A virus program– Infects programs, documents,

databases and more …– It is man-made– It can hide and reproduce– It can lay dormant (inactive)

and then activate

Anti-virus programs can helphelp

A variety of highly contagious “viruses” can spread from computer to computer, much the way biological viruses do among human beings. Just as a virus can infect human organs, a

computer virus can infect programs and databases. It can also hide duplicates of itself within legitimate programs.

Viruses and Virus Protection (2)

Viruses and Virus Protection(3)

These viruses, which are programs, reside on and are passed between magnetic disks.

Most people who write and circulate virus programs fall into two groups.

1. The first group uses viruses to show off for their peers.

2. The second, and far more dangerous group, creates viruses with malicious intent.

Sources of Computer Viruses

Three primary sources– The Internet

Via downloads and exchanges

– Diskettes Exchanging disks

– Computer networks Can spread from one network to

another

How do you know if you have a virus?

Lack of storage capability Decrease in the speed of executing programs Unexpected error messages Halting the system

Virus Protection

• The software package distributed with new PCs always includes an antiviral program. The best way to cope with viruses is to recognize their existence and use an antiviral, or antivirus program.

1. Delete e-mails from unknown or suspicious, untrustworthy (unreliable) sources, especially those with files attached to an e-mail.

2. Never open a file attached to an e-mail unless you know what it is, even if it appears to come from a friend.

3. Download files from the Internet only from legitimate and reputable sources.

4. Update your antivirus software at least every two weeks as over 200 viruses are discovered each month.

5. Backup your files periodically6. Traditionally virus protection has been at the PC or

client level. However, this may change as companies look to network and Internet service providers for more services.

Some tips that will help minimize your vulnerability to viruses:

Computer Ethics

You shall not use a computer to harm other people. You shall not snoop around in other people's computer files. You shall not use a computer to steal. You shall not use other people's computer resources without

authorization or proper compensation. You shall always use a computer in ways that show

consideration and respect for your fellow humans.

Computer Uses

1- Supermarkets: Use a bar code reader.2- Libraries: Use computers to search for books; to record bookslending and return ….3- Banks: Enable customers to access their accounts via ATM.4- Plastic Cards: Used in computer system to facilitate customerslife (mobile, telephone and credit cards)5- Electronic Commerce: Uses Internet in business forpurchasing, payment, or reservations.6- Touch Screens: Allow unskilled customers to accessinformation easily.7- Hospitals: Use computers to store records of patients and tohelp in the diagnosis and analysis of the treatment.8- Cars: Computers are used to display maps and giveinstructions to the driver.