Review For Final
(Summer 2010)
© Abdou Illia
1
Computer Hardware
2
The Core Computer Components

Four subsystems in a computer system:
1. Input subsystem
2. Processing subsystem
3. Output subsystem
4. I/O (Storage) subsystem
Input/Output (storage)
Input
Process
Output
3
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 Card
Common resolution
Color Graphics Adapter CGA (1981)
640×200
Hercules (1984)
720×348
Extended Graphics Array XGA (1990)
1024×768
Super XGA
1280×1024
Ultra XGA
1600×1200
4
Printers

Speed and resolution


Pages per minute (PPM)
Dots per inch (DPI)



Impact printers



Number of ink dots to fill a square inch
Higher DPI = greater page clarity
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
5
I/O or Secondary Storage devices

Secondary compared to the main primary memory called RAM
Nonvolatile1 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
6
Measuring Storage Capacity
7
Processing subsystem
Motherboard: chipset that all components connect to
 Two major components in processing subsys.



CPU (Central Processing Unit) or Processor(s)
Primary Storage:
 Random Access Memory (RAM)
 Read Only Memory (ROM)
Other
components
on the
Motherboard
CPU
Busses that
transfer data
Primary Storage
8
Central Processing Unit
Processor

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
Clock
Instruction
Control Unit
Arithmetic
Logic Unit
Registers
9
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
-
Major Processor manufacturers
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
*FLoating point Operations Per Second
10
Primary Storage
 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)
Primary Storage
RAM
Program

RAM holds running programs
and the data they use

ROM contains critical
programs such as those that
boot the computer
Data
ROM
11
Summary Questions
Book
Notes
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?
12
Network Technology
13
Computer Network

Once connected to the network,
the computer (or another device)
becomes a network node
An interconnection of computers and
computing equipment using either wires
or radio waves over small or large
geographic distances
GHI
DEF
ABC
MNO
“Connect to GHI”
JKL
14
Physical
Transmission Media

Physical media



Wireless
Transmission media used to physically connect
nodes in to the network
Transmits electrical or optical signals
Could be cooper wire or fiber optic cable
15
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
16
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)

Infrared light




Affected by Multipath interference
Highly vulnerable to snooping
Limited distance
Blocked by thick objects

Close proximity and “line of sight” location required
Laptop
Comm.
Tower
17
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
18
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

19
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

20
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
21
Network Architecture

Defines how the
processing takes
place on the network

Two primary types


Client-server
Peer-to-peer (P2P)
22
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
23
The Internet and
eBusiness
24
Brief history of the Internet
Make sure you
know what DNS
is used for.
1969 The Defense Advanced Research Projects
developed ARPANET, the precursor of the Internet
1971 Ray Tomlison invents e-mail
1979 USENET newsgroups created at Duke University
and the University of North Carolina
1984 Domain Name System (DNS) established
1991 Tim Berners-Lee creates the World Wide Web
1994 First online shopping mall, first spam email, first
pizza ordered online, first advertisement banner
2000 A major denial of service attack brings down
websites such as Yahoo!, Amazon.com, and eBay
2002 Denial of service attack knocks out 8/15 root DNS
25
servers
Accessing the Internet (www)
Web
Browser
Network
Packet
Webserver
Software
Packet
Route
Router
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)
Webserver needs:
- Network (or Server) Operating System
- TCP/IP
- Domain name (e.g. eiu.edu)
- Internet access
26
- IP Address (e.g. 139.67.8.3)
Internet applications/services
 E-Mail
 File
transfers
 Instant messaging (IM)
 Newsgroups
 Streaming audio and video
 Internet telephony
 World Wide Web (WWW)
 Portal
27
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)
28
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
29
Summary Questions
Book
1) (a) Name some Internet applications/services (b)
What is Instant Messaging?
2) (a) What does a user PC needs for accessing the
World Wide Web? (b) What is needed on the
webserver side?
3) Name some Internet connection options available for
residential users and businesses.
4) (a) What is an intranet? (b) an extranet?
Refers to the slide #
in class posted notes
Notes
9,14,
7
5-6
18,19
30
Managing Security
31
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
32
Managing the Development
and Purchase of IS
33
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
34
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
35
Traditional Systems Development
Planning
Life Cycle (SDLC)
Analysis

Seven phases
1)
2)
3)
4)
Planning
Systems Analysis
Systems Design
Development
Design
5) Testing
6) Implementation
7) Maintenance
Development
Testing
Implementation

Typically one phase needs to be
completed before beginning the next

Problem in later phase may require
return to previous phase
Maintenance
36
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
37
Feasibility Analyses
Planning

Feasibility analyses

Technical 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



Do the technologies exist to develop the system?
Economic Analysis


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
38
Project Management software
Systems Analysis
Analyze current system
Define new system requirement

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
39
Systems Analysis

Analyze current system
Define new system requirements
Step 2: Define new system’s requirements

Main Objective:


To be defined:





Specify What need to be done (not how to do it)
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
40
Data Flow Diagrams (DFD)
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
Data flow
. Symbolized by an arrow.
. Shows data being passed from or to a process
External Entity
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.
Data storage
Used to store data in the system.
Represents a file, a database, etc.
41
Systems Design

Using the requirements from Systems Analysis phase
to design the new or modified system.

Logical systems design




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



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
Scope creep
Feature creep
Performed by system designer or (system analyst in
42
some case)
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)
2)
3)
4)
5)
Review the input, processing, output, and storage requirements
Develop the logic of the programs (using Flowcharts and Pseudo code)
Write the programs using code generators & programming languages
Test and debug the programs
Complete the programs documentation
43
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.
Code generators:
Software that
generate programs
that programmers
could modify.
Programming languages:
-Java
-C++
-Visual Basic
-Etc.
44
Testing

Programmers test modules



Development team do unit testing


Do they return proper outputs?
Do they handle incorrect data appropriately?
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
45
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
46
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
47
Summary Questions
Book
Notes
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?
48
Questions

During what SDLC phase software programs like
Microsoft Project could be used?
a)
b)
c)
d)
e)
f)

Maintenance
Implementation
Development
System Analysis
Planning
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)
b)
c)
d)
e)
Interviews
Observing future users doing their job
Using pseudocode
Using software programs to draw data flow diagrams
All of the above
49
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)
b)
c)
d)
e)

Operational Feasibility
Financial Feasibility
Economic Feasibility
Beneficial Feasibility
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)
b)
c)
d)
e)
f)
Maintenance
Implementation
Development
System Analysis
Planning
None of the above
50
Questions

During what phase of the SDLC the Database
component of a new system is created?
a)
b)
c)
d)
e)
f)

Maintenance
Implementation
Development
System Analysis
Planning
None of the above
During what phase of the SDLC code generators
could be used?
a)
b)
c)
d)
e)
f)
Maintenance
Implementation
Development
System Analysis
Planning
None of the above
51
Questions

The implementation strategy in which the old
system is immediately replaced by the new
one is called:
a)
b)
c)
d)

Staged conversion
Direct cutover
Systematic testing
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
52
SDLC: Recap
Steps
Key actors
Tools/Techniques
1. Planning
Project Manager
Project Management software,
Total Cost Ownership analysis, etc.
2. System Analysis
System Analyst, Users.
Interviews, observing users at
work, DFD
3. System Design
System analyst (or system
designer)
System Flowchart, Structure chart
4. Development
Programmers, database
developers, network engineers
Program Flowchart, Pseudo code,
programming languages, DBMS
5. Testing
Development team, Users
Unit testing, verification,
validation
6. Implementation
Development team, Users
Direct cutover, parallel conversion,
pilot testing, staged conversion
7. Maintenance
internal IS staff, external
consultant
Make sure you can answer questions about System
Development (see SDM Quest link in Review section)
53
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INTRODUCTION TO INFORMATION SYSTEMS TECHNOLOGY