1 Review For Final © Abdou Illia (Fall 2007)

2 Computer Hardware

3 The Core Computer Components  Three subsystems in a computer system: 1. Input subsystem 2. Processing subsystem 3. Output subsystem

4 Output Devices  Monitors Cathode ray tube (CRTs) Liquid crystal displays (LCDs) Quality of display  Resolution in pixels (e.g. 640 x 480)  Dot pitch in millimeters (.26 to.28)  Active-Matrix vs. Passive-Matrix display  Touch screens Input and output via display device Monitor sizeCommon resolution 15 inches640 x inches800 x 600 or 1024 x inches1024 x 768 or 1280 x 1024

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 I/O devices or Secondary Storage  Nonvolatile storage of digital data  Magnetic or optical  Magnetic storage (Floppy disk, Magnetic tape, Zip disk, Hard disk) Sequential access (tape) or direct access (HDD) Hard disk drives  Two main standards:  IDE (Integrated Drive Electronics) aka ATA (AT Attachment)  SCSI (Small Computer System Interface)  SCSI allows disk fault-tolerance through RAID – Redundant Array of Inexpensive Disks  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)

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8 Processing subsystem  Two major components  CPU (Central Processing Unit) or Processor(s)  Primary Storage:  Random Access Memory (RAM)  Read Only Memory (ROM) CPU Primary Storage Busses that transfer data

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 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 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

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 Summary Questions BookNotes 1)Name three 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 Software Technology

14 Relationship of software to hardware

15 Main Types of Software  Systems software Programs that manage computer hardware and application software Three types of systems software:  Operating systems (e.g. Windows, Linux)  Language translators (C++ compiler, VB compiler)  Utility programs (e.g. Norton Utilities) Systems Software Application Software

16 Main Types of Software  Application software Programs that allow users to accomplish specific tasks Examples  Word processing  Web browser  Tax preparation  Data management  Desktop publishing   Groupware  Presentation graphics  Programming editors  Spreadsheet

17 Operating Systems (OS)  Software platform on which other programs run  Provides a connection between application programs and the computer hardware  Major tasks Starting the computer Managing files Managing Programs and Memory (RAM) Ensuring security Providing a user interface  Example of OS: Linux, Windows XP, Windows 2000, UNIX.

18 Managing Memory: Multiprogramming

19 ￭ A technique that “extends” primary memory (RAM) by using secondary storage devices ￭ Needed when there is not enough RAM to hold programs Managing Memory: Virtual Memory

20 Summary Questions BookNotes 1)What are the functions (or tasks) of an OS? 2)What do application programs allow? 3)What is the function of the Instruction Control Unit or ICU found in the processing subsystem? 4)What is meant by virtual memory? 5)What is meant by multiprogramming?

21 Network Technology

22 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

23 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

24 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  Fiber optic Thin glass fibers surrounded by coating Uses lasers for light source Very fast (10+ Gbps, 100 miles without any repeater) Very secure Source Photo diode (LED or LD) Destination Photo receptor (LED or LD) Fiber optic cable

25 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

26 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

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

28 Protocols  An agreed upon set of rules that govern communications in a network  Example: TCP/IP suite, Ethernet, Token Ring Computer 1 Rules for Task 1 Rules for Task 2 Rules for Task 3 Rules for Task 4 Rules for Task 5 Computer 2 Rules for Task 1 Rules for Task 2 Rules for Task 3 Rules for Task 4 Rules for Task 5

29 TCP/IP  TCP/IP suite is named after its two main protocols: TCP and IP  Transmission Control Protocol (TCP) Provides a reliable byte-stream transfer service between two endpoints on an internet  Internet Protocol (IP) Defines a delivery mechanism for packets of data sent between all systems on an Internet  It’s the protocol suite for the Internet TaskSample rules/protocols ApplicationHTTP, FTP, SMTP TransportTCP, UDP InternetIP PhysicalEthernet, Token Ring, PPP, Modem standards

30 Ethernet  A set of rules for transmitting messages in LANs  Most widely used protocol for LANs  Uses a method called CSMA/CD* for wired LANs 1) All computers (“carriers”) listen (“sense”) for traffic on the LAN 2) If no traffic, computer that wishes to transmit may transmit 3) If collision occurs, computers must wait a random amount of time 4) The computer with smallest random number send again first. * Carrier Sense Multiple Access with Collision Detection CSMA/CD*

31 Token Ring  Other set of rules for transmitting messages in LANs  Only one node “talks” at a time  A node only transmit when it receives a special packet called a “Token”  Only one Token on the ring  No collisions

32 Transmitting Data in a Network  Two major techniques: 1)Circuit switching network  Traditionally used for voice transmission 2)Packet switching network  Used for computer data transmission.

33 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 6)Could collisions occur in Token Ring networks? In Ethernet networks? 7)What is TCP/IP? 8)Distinguish between circuit switching and packet switching.

34 IS For Business Integration Refer to Review For Exam 3 material posted to the course web site

35 Development of IS Refer to Review For Exam 3 material posted to the course web site

36 Security and privacy Refer to Review For Exam 3 material posted to the course web site