1 Review For Final © Abdou Illia (Fall 2007). 2 Computer Hardware.

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Review For Final

© Abdou Illia

(Fall 2007)

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Computer Hardware

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The Core Computer Components Three subsystems in a computer system:

1. Input subsystem2. Processing subsystem3. Output subsystem

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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 size Common resolution

15 inches 640 x 480

17 inches 800 x 600 or 1024 x 768

19 inches 1024 x 768 or 1280 x 1024

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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

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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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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

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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

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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

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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)

Program Data

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Summary QuestionsBook Notes

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?

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Software Technology

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Relationship of software to hardware

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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

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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 E-mail Groupware Presentation graphics Programming editors Spreadsheet

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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.

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Managing Memory: Multiprogramming

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￭ 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

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Summary QuestionsBook Notes

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?

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Network Technology

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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

JKLMNO

Once connected to the network, the computer (or another device) becomes a network node

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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

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Transmission Media (Continued) Twisted Pair

Category Use Signal Data rate Distance Problem

Category 1 Telephone Analog/Digital <100Kbps 3-4 miles Security, noise

Category 2 T1, ISDN Digital <2 Mbps 3-4 miles Security, noise

Category 3 LANs Digital 10 Mbps 100 m Security, noise

Category 4 LANs Digital 20 Mbps 100 m Security, noise

Category 5 LANs Digital 100 Mhz 100 m Security, noise

Category 6 LANs Digital 250 Mhz 100 m Security, noise

Category 7 LANs Digital 600 Mhz 100 m Security, 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

SourcePhoto diode(LED or LD)

DestinationPhoto receptor(LED or LD)Fiber optic cable

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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

LaptopComm. Tower

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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

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Network Architecture

Defines how the processing takes place on the network

Two primary types Client-server Peer-to-peer (P2P)

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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

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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

Task Sample rules/protocols

Application HTTP, FTP, SMTP

Transport TCP, UDP

Internet IP

Physical Ethernet, Token Ring, PPP, Modem standards

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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 LAN2) If no traffic, computer that wishes to transmit may transmit3) If collision occurs, computers must wait a random amount of time4) The computer with smallest random number send again first.

* Carrier Sense Multiple Access with Collision Detection

CSMA/CD*

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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

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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.

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Summary Questions

Malaga Notes

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.

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IS For Business Integration

Refer to Review For Exam 3 material posted to the course web site

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Development of IS

Refer to Review For Exam 3 material posted to the course web site

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Security and privacy

Refer to Review For Exam 3 material posted to the course web site