1. 1 Review For Final © Abdou Illia (Summer 2010)

2. 2 Computer Hardware

3. 3 The Core Computer Components  Four subsystems in a computer system: 1. Input subsystem3. Output subsystem 2. Processing subsystem4. I/O (Storage) subsystem Input Process Output Input/Output (storage)

4. 4 Output Devices  Monitors Cathode ray tube (CRTs) Liquid crystal displays (LCDs) Quality of display  Resolution (width and height in pixels); e.g. 640 x 480)  Dot pitch in millimeters (e.g..25,.26)  Active-Matrix vs. Passive-Matrix display  Touch screens Input and output via display device Video CardCommon resolution Color Graphics Adapter CGA (1981)640×200 Hercules (1984)720×348 Extended Graphics Array XGA (1990)1024×768 Super XGA1280×1024 Ultra XGA1600×1200

5. 5 Printers  Speed and resolution Pages per minute (PPM) Dots per inch (DPI)  Number of ink dots to fill a square inch  Higher DPI = greater page clarity  Impact printers Create image by striking paper and ribbon Dot-matrix printers = most common impact printers  Non-impact printers Create image by spraying or rolling ink on the page

6. 6 I/O or Secondary Storage devices  Secondary compared to the main primary memory called RAM  Nonvolatile 1 storage of digital data  Could be Magnetic or Optical  Magnetic storage (i.e. data stored on magnetically coated surface) Examples: Magnetic tape, Hard disk, floppy disk Sequential access (e.g. tape) or direct access (e.g. HDD) Hard disk disks  many standards:  Parallel ATA (PATA) or IDE (Integrated Drive Electronics)  Serial ATA (SATA) 2  SCSI (Small Computer System Interface)  SCSI provides disk fault-tolerance by using RAID – Redundant Array of Inexpensive Disks; that is multiple disks set together to provide continued service in case one disk fails.  Disk speed:  Transfer rate in MBps (Megabytes per second)  Average Read Time (in milliseconds or ms)  Platter rotation speed in RPM (5400/7200/10,000/15,000) 1. Means that the stored data wouldn’t disappear (or be deleted) in case of power shortage 2. In SATA and PATA, ATA stands for Advanced Technology Attachment

7. 7 Measuring Storage Capacity

8. 8 Processing subsystem  Motherboard: chipset that all components connect to Motherboard  Two major components in processing subsys.  CPU (Central Processing Unit) or Processor(s)  Primary Storage:  Random Access Memory (RAM)  Read Only Memory (ROM) Busses that transfer data CPU Primary Storage Other components on the Motherboard

9. 9 Central Processing Unit  Clock: generate time that synchronize other components  ICU: Fetches instructions from RAM  ALU: Execute instructions (arithmetic & logic operations)  Registers: Store control information, data, intermediate results Processor Clock Instruction Control Unit Arithmetic Logic Unit Registers

10. 10 CPU speed  Speed measured in hertz Hertz = # of instructions executed per second Megahertz = 1 million of instructions per second Gigahertz = 1 billion of instructions per second  Speed is also measured in FLOPS* … especially in fields of scientific calculations where long divisions called Floating point divisions are used. Intel - Celeron - Pentium 3, Pentium 4, Pentium 4 Xeon, Dual Core Advanced Micro Devices (AMD) - K6 series processors (which compete with Intel Pentium 3) - Athlon series (which compete with Intel Pentium 4) IBM - PowerPC 740, 750, 750FX, 750GL, 750GX Major Processor manufacturers *FLoating point Operations Per Second

11. 11 Primary Storage  RAM holds running programs and the data they use  ROM contains critical programs such as those that boot the computer Primary Storage RAM ROM  Computer’s memory stored on semiconductor chips  Two categories:  RAM (Random Access Memory) which is volatile  Synchronous Dynamic RAM (SDRAM)  Double Data Rate SDRAM or DDR SDRAM  ROM (Read-Only Memory) which is non-volatile  Capacity in Megabytes (MB) or Gigabytes (GB) ProgramData

12. 12 Summary Questions BookNotes 1)Name two devices that could be used for both input and output. 2)What is the difference between: (a) a Kilobyte and a Gigabyte? (b) a Megabyte and a byte? 3)What is the function of the Instruction Control Unit or ICU found in the processing subsystem? 4)Explain the difference between RAM and ROM. 5)What is pixel? What is dot pitch 6)What is a byte? 7)What is a Hertz?

13. 13 Network Technology

14. 14 Computer Network  An interconnection of computers and computing equipment using either wires or radio waves over small or large geographic distances “Connect to GHI” ABC DEF GHI JKL MNO Once connected to the network, the computer (or another device) becomes a network node

15. 15 Transmission Media  Physical media Transmission media used to physically connect nodes in to the network Transmits electrical or optical signals Could be cooper wire or fiber optic cable Physical Wireless

16. 16 Transmission Media (Continued)  Twisted Pair CategoryUseSignalData rateDistanceProblem Category 1TelephoneAnalog/Digital<100Kbps3-4 milesSecurity, noise Category 2T1, ISDNDigital<2 Mbps3-4 milesSecurity, noise Category 3LANsDigital10 Mbps100 mSecurity, noise Category 4LANsDigital20 Mbps100 mSecurity, noise Category 5LANsDigital100 Mhz100 mSecurity, noise Category 6LANsDigital250 Mhz100 mSecurity, noise Category 7LANsDigital600 Mhz100 mSecurity, noise

17. 17 Wireless Media  Uses electromagnetic waves or electromagnetic radiation for data transmission  Propagation through space, and indirectly, through solid objects  Two kinds of wireless media used Radio waves (radio Frequency)  Affected by Multipath interference  Highly vulnerable to snooping  Limited distance  Blocked by thick objects Infrared light  Close proximity and “line of sight” location required Laptop Comm. Tower

18. 18 Network Topologies  The configurations of network components How physically the network looks like How logically data is transferred on the network  Widely used network topologies: Bus Star Ring

19. 19 Bus Network Topology  Most simple network topology  All devices connected to a common central cable called a “bus”  Inexpensive  If cable fails, the entire network will shut down

20. 20 Star Network Topology  Centered around central device called a hub or a switch  All network nodes connect to the hub/switch  Easy to install and update  If hub fails, network fails

21. 21 Ring Topology  Node connected to a logical ring in a central device called MAU  More reliable than bus or star Only one node sends at a time (no collisions)  Expensive and limited speed

22. 22 Network Architecture  Defines how the processing takes place on the network  Two primary types Client-server Peer-to-peer (P2P)

23. 23 Summary Questions MalagaNotes 1)What is a node? 2) Name physical and wireless media used in networking 3) What transmission media is used for the telephone? 4)What are the main network topology? What are the differences between them? 5)Distinguish between Client-server and P2P networks

24. 24 The Internet and eBusiness

25. 25 Brief history of the Internet 1969The Defense Advanced Research Projects developed ARPANET, the precursor of the Internet 1971Ray Tomlison invents e-mail 1979USENET newsgroups created at Duke University and the University of North Carolina 1984Domain Name System (DNS) established 1991Tim Berners-Lee creates the World Wide Web 1994First online shopping mall, first spam email, first pizza ordered online, first advertisement banner 2000A major denial of service attack brings down websites such as Yahoo!, Amazon.com, and eBay 2002Denial of service attack knocks out 8/15 root DNS servers Make sure you know what DNS is used for.

26. 26 Webserver needs: - Network (or Server) Operating System - TCP/IP - Domain name (e.g. eiu.edu) - Internet access - IP Address (e.g. 139.67.8.3) User PC needs: - Workstation Operating System - TCP/IP - Web browser (e.g. Internet Explorer) - Internet access (e.g. thru an ISP) - IP Address (e.g. 128.150.50.9) Accessing the Internet (www) Network Web Browser Packet Router Packet Route Webserver Software

27. 27 Internet applications/services  E-Mail  File transfers  Instant messaging (IM)  Newsgroups  Streaming audio and video  Internet telephony  World Wide Web (WWW)  Portal

28. 28 Intranets and Extranets  Intranet Internal company network that uses Internet and WWW technologies. Typical Use:  Finding and sharing work documents  Collaboration between employees to work in teams  Communication tool Typically, only internal employees can get access  Extranet Web site that allows customers and business partners limited access to organizational intranet Uses Internet and WWW technologies Add additional security through the use of a Virtual Private Network (VPN) Virtual Private Network

29. 29 Portal  Portal Web site that offers a broad array of resources and services; such as  email  newsgroup  Serach engines  Online shopping malls Example: yahoo!, msn, aol

30. 30 Summary Questions Refers to the slide # in class posted notes BookNotes 1)(a) Name some Internet applications/services (b) What is Instant Messaging? 9,14, 2) (a) What does a user PC needs for accessing the World Wide Web? (b) What is needed on the webserver side? 7 3)Name some Internet connection options available for residential users and businesses. 5-6 4)(a) What is an intranet? (b) an extranet? 18,19

31. 31 Managing Security

32. 32 Best way to prepare  Review the ppt notes or chapter 7, 12 in the book to make sure you can answer the following questions Security Review Questions available in the Final Review section of course web site Security Questions in Quiz 1

33. 33 Managing the Development and Purchase of IS

34. 34 Systems Development Methodology?  The process companies go through to develop and maintain an information system  Framework for successful IS development  A System Development Methodology is used For building a new system Or for modifying an existing system  Examples of SDM: System Development Life Cycle ￭ Prototyping Joint Application Development ￭ Rapid Application Development

35. 35 Questions  Which of the following is true about SDM? 1)They provide guidelines for developing IS and maintaining them which includes upgrading and improving them. 2)SDM are needed when a brand new IS has to be developed, but you don’t need to use a SDM when it comes to modifying an existing IS. 3)When a company is engaged in developing an IS, the process involves the company’s employees who would be the future users of the IS, and IS professionals like system analysts and programmers. But it doesn’t involve the company’s management 4)All of the above

36. 36 Traditional Systems Development Life Cycle (SDLC)  Seven phases 1)Planning5) Testing 2)Systems Analysis6) Implementation 3)Systems Design7) Maintenance 4)Development  Typically one phase needs to be completed before beginning the next  Problem in later phase may require return to previous phase Planning Analysis Design Development Testing Implementation Maintenance

37. 37 Question  In SDLC, the 7 phases are typically followed in a sequential order, which means we don’t return to a previous phase in any circumstances  True  False

38. 38 Planning  Feasibility analyses Technical Analysis  Do the technologies exist to develop the system? Economic Analysis  Can the organization afford the system?  Will it provide an adequate Benefit? Operational Analysis (i.e. assessing the human element of the proposed system)  Resistance to change  Organizational politics  System development schedule Is the proposed development time line realistic? Is the programming team available during Programming step?  Planning performed by Project Manager using Search and investigation (e.g. for technical analysis step) Total Cost of Ownership analysis Project Management software Feasibility Analyses System Development Schedule

39. 39 Systems Analysis  Systems analyst works with company to understand the problem fully and to detail the requirements of the proposed system  Step 1: Analyze current system Objectives:  Understand what things are done and how (business processes)  Identify any problems associated w/ current business processes Techniques:  Observe employees at work  Talk to employees (potential users)  Conducting interviews Analyze current system Define new system requirement

40. 40 Systems Analysis  Step 2: Define new system’s requirements Main Objective:  Specify What need to be done (not how to do it) To be defined:  Input requirements (nature of data, source, etc.)  Processing requirements  Output requirements (Types of reports, content, etc.)  Storage requirements Tools and techniques  Data flow diagrams (DFD)  Start with high level process  Add more levels with increased levels of detail  Computer-Aided Software Engineering (CASE) tools  Software that eases the systems development process Analyze current system Define new system requirements

41. 41 Data Flow Diagrams (DFD) Data flow Process External Entity Data storage. Symbolized by an arrow.. Shows data being passed from or to a process. Symbolized by a rectangle or a curved rectangle.. Action performed by people of organizational units in order to transform input into output OR Action performed by people in the organizational units to help the units achieve their objectives Symbolized by a square, an external entity is something (person, group, department, etc.) outside the system that interacts with the system by providing input or receiving information. Used to store data in the system. Represents a file, a database, etc.

42. 42 Systems Design  Using the requirements from Systems Analysis phase to design the new or modified system. Logical systems design  Details the system’s functionality (what it should do?)  Uses Structure charts to create top-down representation of system’s modules  Uses System flowcharts to show relationships between modules Physical systems design  Specifies all of the actual components (hardware, network, etc) used to implement the logical design The design must be frozen at end of this phase to prevent the to system grow indefinitely in terms of its scope and features  Scope creep  Feature creep  Performed by system designer or (system analyst in some case)

43. 43 Development  Programming process is usually the most difficult and time consuming in the Development process.  Development performed by programmers, database developers, and network engineers  Programmers use Program Development Cycle 1) Review the input, processing, output, and storage requirements 2) Develop the logic of the programs (using Flowcharts and Pseudo code) 3) Write the programs using code generators & programming languages 4) Test and debug the programs 5) Complete the programs documentation

44. 44 Development tools Program Flowchart: Graphical illustration of the problem-solving logic within a program Pseudocode: English-language statements that describe the processing steps of a program in paragraph form. Programming languages: -Java -C++ -Visual Basic -Etc. Code generators: Software that generate programs that programmers could modify.

45. 45 Testing  Programmers test modules  Do they return proper outputs?  Do they handle incorrect data appropriately?  Development team do unit testing  i.e. testing how modules work together  System testing (software along with database and network component) Verification: Testing system in simulated environment with simulated data Validation: Testing system in real working environment with real data

46. 46 Implementation  Implementation strategies Direct cutover: Quick change to new system Parallel conversion: Old and new systems used in parallel for a while. Pilot testing: New system installed at only one location or one department Staged conversion: Only one part of the system installed, then another part is installed.  User training

47. 47 Maintenance  Maintenance counts for as much as 80% of the total cost of an information system  Tasks Correct errors found during implementation System enhancements  Incremental upgrades  Addition of major new features

48. 48 Summary Questions BookNotes 1)What is a System Development Methodology? What is it used for? 2) What are the 7 phases of the SDLC methodology? 3)What kind of Feasibility analyses need to be performed during the Planning phase? Why is the system development schedule important? 4)What are the two steps in the Systems Analysis phase? What techniques and tools are used during the Systems Analysis phase? 5)What tools do programmers usually use during the Development phase? 6)What is the difference between the Verification and the Validation tests performed during systems testing?

49. 49 Questions  During what SDLC phase software programs like Microsoft Project could be used? a)Maintenance b)Implementation c)Development d)System Analysis e)Planning f)None of the above  Which of the following tools or techniques could be used during the System Analysis phase of the SDLC? (Choose all correct answers) a)Interviews b)Observing future users doing their job c)Using pseudocode d)Using software programs to draw data flow diagrams e)All of the above

50. 50 Questions  What kind of feasibility analysis seeks to determine if an organization can afford the new information system and if the system will provide the adequate benefits? a)Operational Feasibility b)Financial Feasibility c)Economic Feasibility d)Beneficial Feasibility e)None of the above  During the Development phase of a new medical IS, the development team finds out that most of the technologies needed to develop and implement the system are not yet available on the market. At what step of the SDLC that kind of problem should have been identified? a)Maintenance b)Implementation c)Development d)System Analysis e)Planning f)None of the above

51. 51 Questions  During what phase of the SDLC the Database component of a new system is created? a)Maintenance b)Implementation c)Development d)System Analysis e)Planning f)None of the above  During what phase of the SDLC code generators could be used? a)Maintenance b)Implementation c)Development d)System Analysis e)Planning f)None of the above

52. 52 Questions  The implementation strategy in which the old system is immediately replaced by the new one is called: a)Staged conversion b)Direct cutover c)Systematic testing d)None of the above  Validation testing performed during the Testing phase of the SDLC ensures that the system is working properly in the real working environment using real data. a)True b)False

53. 53 SDLC: Recap StepsKey actorsTools/Techniques 1. PlanningProject ManagerProject Management software, Total Cost Ownership analysis, etc. 2. System AnalysisSystem Analyst, Users.Interviews, observing users at work, DFD 3. System DesignSystem analyst (or system designer) System Flowchart, Structure chart 4. DevelopmentProgrammers, database developers, network engineers Program Flowchart, Pseudo code, programming languages, DBMS 5. TestingDevelopment team, UsersUnit testing, verification, validation 6. ImplementationDevelopment team, UsersDirect cutover, parallel conversion, pilot testing, staged conversion 7. Maintenanceinternal IS staff, external consultant Make sure you can answer questions about System Development (see SDM Quest link in Review section)