Managing Information Technology

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Copyright © 2009 Pearson Education, Inc.

Publishing as Prentice Hall

1

Managing Information Technology

CHAPTER 3

COMPUTER SOFTWARE

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Building Blocks of Information
Technology

Hardware

Software

Network

Data

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EVOLUTION OF COMPUTER
PROGRAMMING


Machine language (1GL)


Each instruction must be expressed in unique form for a
particular computer


Complete program consists of thousands of instructions


Programming is a tedious, time
-
consuming process


Assembly languages (2GL)


Easily remembered mnemonic operation codes substituted
for machine language operation codes


Assembler used to convert mnemonic codes to machine
language

First and Second Generation Languages

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EVOLUTION OF COMPUTER
PROGRAMMING

First and Second Generation Languages

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EVOLUTION OF COMPUTER
PROGRAMMING


Procedural languages (3GL)


Typically machine independent


Express a step
-
by
-
step procedure devised by the
programmer


Must be compiled or interpreted (translated into
machine language)


Include FORTRAN, COBOL, BASIC, PL/1, PASCAL,
ADA, and C

Third and Fourth Generation Languages

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EVOLUTION OF COMPUTER
PROGRAMMING

Third and Fourth Generation Languages

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EVOLUTION OF COMPUTER
PROGRAMMING


Nonprocedural languages (4GL)


Also referred to as productivity languages


Use more English
-
like statements for program
instructions


Easier to use, write, and less error
-
prone


Use a built
-
in interpreter to convert to machine
language


Take much longer to execute than 3GLs


Include FOCUS, CA
-
Ramis
, IFPS, and SAS

Third and Fourth Generation Languages

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EVOLUTION OF COMPUTER
PROGRAMMING

Third and Fourth Generation Languages

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EVOLUTION OF COMPUTER
PROGRAMMING


Object
-
oriented languages


3GLs with some 4GL features


Built on idea of embedding procedures (methods)
in objects, and putting objects together to create
an application


Include Smalltalk, C++, Java, and Visual Basic


Third and Fourth Generation Languages

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KEY TYPES OF SOFTWARE

1.
Applications software

2.
Support software

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APPLICATIONS SOFTWARE


Programs written to accomplish particular tasks


Many different types of applications software


Standard applications products generally purchased
from an outside source


Applications unique to the organization generally
developed internally


Personal productivity software most important to
managers


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APPLICATIONS SOFTWARE


Peachtree accounting software


Commercial accounting package for smaller
businesses


Includes general ledger, accounts receivable,
accounts payable, inventory, payroll, time and
billing, job costing, fixed asset accounting, and
analysis and reporting tools


$500 for single
-
user version



Examples of Application Software

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APPLICATIONS SOFTWARE


Sage
Accpac

200 ERP


Modular financial management systems for midsized
businesses


Web
-
based, so only a Web browser is needed to
access the application


System Manager module manages security, ensures
data integrity, handles bank reconciliation and tax
processing, and allows for customized reports


Several other modules available as well


Examples of Application Software

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APPLICATIONS SOFTWARE


Word processing


Used to create documents for printing


Most popular is Microsoft Word


Others include Corel WordPerfect, Lotus WordPro,
and Sun’s StarOffice Writer


All employ WYSIWYG


Personal Productivity Software

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APPLICATIONS SOFTWARE


Spreadsheets


Used to create applications that fit a row
-
column
format


Most popular is Microsoft Excel


Others include Lotus 1
-
2
-
3 and Corel Quattro
Pro


All employ rows, columns, cells, formulas, and
“what
-
if” analysis


Personal Productivity Software

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APPLICATIONS SOFTWARE


Database management systems


Used to create databases similar to those on
larger machines


Most popular is Microsoft Access


Others include FileMaker Pro, Corel Paradox, and
Lotus Approach


All employ a relational data model


Personal Productivity Software

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APPLICATIONS SOFTWARE


Presentation graphics


Used to create largely textual business
presentations


Most popular is Microsoft PowerPoint


Others include Corel Presentations and Lotus
Freelance Graphics


All allow embedding of clip art, photos, graphs,
and other media



Personal Productivity Software

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APPLICATIONS SOFTWARE


Web browsers


Used to access information on the Web


Requires ISP service to link PC to Internet


Create documents for printing


Most popular are Internet Explorer and Firefox… both free!


Both employ standard hypertext
-
based approach (way to
link text and media objects to each other)


Pull technology:

browser requests a Web page before it is
sent to desktop


Push technology:

data sent to client without requesting it
(such as e
-
mail)



Personal Productivity Software

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APPLICATIONS SOFTWARE


Electronic mail


Preferred way of communicating in business today


Easy to use and precise


Groupware


Incorporates e
-
mail and other productivity
features, such as calendaring, scheduling, and
document sharing



Personal Productivity Software

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SUPPORT SOFTWARE


Provides computing environment that is easy and
efficient for humans to use


Enables applications programs to be carried out


Ensures that computer hardware and software are
used efficiently


Almost always purchased from a hardware vendor or
software house



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SUPPORT SOFTWARE


Most important type of support software


Complex program that controls operation of
computer hardware and coordinates other
software


User communicates with operating system
software to control hardware and software
resources


Communication made easier with a graphical
user interface (GUI) feature



Operating System

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SUPPORT SOFTWARE

Operating System

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SUPPORT SOFTWARE


Job control language (JCL):
keyed instructions from the
computer user to communicate with the operating
system


Multiprogramming:
employed on larger machines to
overlap input and output operations with processing
time, keeping the CPU busy and speeding up execution


Multitasking:
similar to multiprogramming, but
employed on microcomputers


Multithreading:
similar to multitasking, but multiple
threads within the same program are overlapped







Operating System

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SUPPORT SOFTWARE


Virtual Memory:


Concerned with management of main memory


Makes it appear that an unlimited amount of
memory is available


Permits multiprogramming to operate more
efficiently


Multiprocessing:
work that takes place when two
or more CPUs are installed on same computer
system








Operating System

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SUPPORT SOFTWARE


Sources of operating systems


Proprietary systems:
most popular type of operating
systems, written for a particular computer hardware
configuration


Microcomputers: MS
-
DOS, PC
-
DOS, Windows XP


Midrange systems: OS/400


Large systems: VM and MVS


Open systems:
not tied to any particular computer
system or hardware manufacturer


will run on
virtually any computer system


Examples: UNIX and Linux









Operating System

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SUPPORT SOFTWARE


Network operating systems (NOS)


Software running on a server that manages network
resources and controls the operation of a network


Enhanced operating system that allows for:


Sharing disk drives and printers


Handling server side of client/server applications


Major players include:


UNIX and Linux


Microsoft Windows NT, 2000 Server, 2003 Server


Novell NetWare







Operating System

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SUPPORT SOFTWARE


Procedural languages (3GL)


Require logical thinking


Entail development of a detailed step
-
by
-
step
procedure


Can be developed using structured programming







Third Generation Languages

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SUPPORT SOFTWARE

Third Generation Languages

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SUPPORT SOFTWARE


Structured programs


Divided into modules, where each has one entry
and one exit point


Advantages


Program logic easier to follow


Maintenance and correction easier and faster


Do not use GO TO logic




Third Generation Languages

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SUPPORT SOFTWARE


Most popular procedural languages


BASIC


C


COBOL


Other procedural languages


FORTRAN


PL/1


PASCAL


ADA







Third Generation Languages

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SUPPORT SOFTWARE

Third Generation Languages
-

BASIC

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SUPPORT SOFTWARE

Third Generation Languages
-

COBOL

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SUPPORT SOFTWARE


Nonprocedural languages


Use very high
-
level instructions


Require fewer instructions


Easier to write, modify, and understand


Example: FOCUS







Fourth Generation Languages

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SUPPORT SOFTWARE

Fourth Generation Languages
-

FOCUS

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SUPPORT SOFTWARE


Employ tags to “mark up” documents


HTML


Used to create Web pages


Consists of special tags that tell the Web browser how to
display various elements on a Web page (e.g., bold
-
faced
or italic text, image location, links to other Web pages)


XML


Used to facilitate data interchange among Web
applications


Metalanguage

consisting of tags that identify particular
data elements


Markup Languages

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SUPPORT SOFTWARE


Requires more computing power


Has built
-
in GUI


Neither 3GL nor 4GL … new paradigm


Creates objects only once and stores for reuse


Object examples:


Text box, check box, entity in an organization


Languages:


Smalltalk, C++, Java, Visual Basic.NET







Object
-
Oriented Programming

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SUPPORT SOFTWARE

Object
-
Oriented Programming
-

Java

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SUPPORT SOFTWARE


HTML form is the most common user interface
encountered by users


Server
-
side programming languages include:


Perl


Java Servlets and Java Server Pages


Microsoft Active Server Pages (ASP, ASP.NET)


ColdFusion







Languages for Developing Web Applications

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SUPPORT SOFTWARE

Languages for Developing Web Applications

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SUPPORT SOFTWARE


Support software used to create, manage, and
protect organizational data


Database:

shared collection of logically related
data organized to meet organizational needs


Five basic architectures:

1.
Hierarchical


Data are arranged in a top
-
down organization chart fashion


Example: IBM Information Management System (IMS)






Database Management Systems

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SUPPORT SOFTWARE


Five basic architectures:

2.
Network


Data are arranged like cities on a highway system, often with
several paths from one piece of data to another


Example: Computer Associates Advantage CA
-
IDMS

3.
Relational


Most common type


Data arranged in simple tables


Records related by storing common data in each associated
table


Examples: Microsoft Access and SQL Server, Paradox, DB2,
and Ingres







Database Management Systems

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SUPPORT SOFTWARE


Five basic architectures:

4.
Object
-
oriented


Data can be graphics, video, and sound as well as simpler data
types


Attributes and methods are encapsulated in object classes, and
relationships between classes can be shown by nesting one class
within another


Examples: Versant Object Database, Progress
ObjectStore
, and
Objectivity/DB

5.
Object
-
relational


Hybrid approach that can handle complex data types with the
simplicity of the relational model


Examples: Oracle, IBM’s DB2 and Cloudscape, and FFE Software’s
FirstSQL
/J








Database Management Systems

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SUPPORT SOFTWARE


Sequential:

arranges
records physically
adjacent and in order
by some (usually
unique) sort key


Direct:
uses key for
records placed so that
they are rapidly
accessed from DASDs


File Organizations

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SUPPORT SOFTWARE


Indexed


Compromise between
sequential and direct


Record keys only
arranged in sequence in
a separate table, along
with location of rest of
data associated with
that key


Popular types include
ISAM and VSAM


File Organizations

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SUPPORT SOFTWARE


Computer
-
aided software engineering (CASE)


Collection of software tools to help automate
all phases of the software development life
cycle


Growth slower than anticipated


Radically changed nature of systems analyst
and programmer jobs





CASE Tools

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SUPPORT SOFTWARE


Recent surge in CASE tools for
Unified
Modeling Language (UML)


UML is a general
-
purpose notational language for
specifying and visualizing complex software,
especially large, object
-
oriented projects


Examples of UML
-
base CASE tools


IBM’s Rational Rose


Borland’s Together


Sybase’s
PowerDesigner




CASE Tools

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SUPPORT SOFTWARE


Large computers


Need to control workstations and terminals


Example software: IBM’s CICS, TSO, and CMS


Increasingly important with growth of LANs and WANs


Web browsers:
enable users to look around, or
“browse,” the Internet


Telnet:
permits user to log into remote computer


File Transfer Protocol (FTP):
used to transfer files from
one computer system to another


Communications Interface Software

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THE CHANGING NATURE

OF SOFTWARE


Less

concern with
machine efficiency


More
purchased applications
, and, conversely, more
use of open source support software, such as Linux


More programming using
object
-
oriented languages


More emphasis on applications that run on intranets
and
the Internet


More
user development


More use of
personal productivity software
on
microcomputers


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THE SOFTWARE COMPONENT OF THE
INFORMATION SYSTEMS INDUSTRY


Hardware manufacturers


IBM, Hewlett
-
Packard, Sun Microsystems, Hitachi, and
Fujitsu


Software houses


Microsoft, Oracle, SAP, Computer Associates, and
Symantec


Consulting firms


PricewaterhouseCoopers Consulting (bought by IBM)

Major Groups