B-1

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Appendix B Information System Software www.pre
nhall.com/jessup
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Classes of Software
System Software The collection of programs that
control the basic functions of computer hardware
Application Software Programs that let the user
perform a specific task or operation by
interacting with the system software
Development Languages and Environments Automated
software tools used by system developers to
design and implement information systems
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System Software a.k.a. Operating Systems
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Operating System
Operating System Manages common tasks for
computers including getting input from a device,
reading and/or writing data from a storage
device, and presenting information to the user

• Common Functions
• Booting or (starting) the computer
• Reading programs into memory and managing memory
  allocation
• Managing where programs and files are located in
  secondary storage
• Maintaining the structure of directories and
  subdirectories
• Formatting disks
• Controlling the computer monitor
• Sending documents to the printer

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Operating System
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Operating System Interfaces
Interfaces After boot up, the computer provides
an interface for the user or programmer to
interact with it. Different operating systems
use different types

• Common Interface Type
• Command-based interface this type requires a
  user to type commands to perform basic functions
  (i.e. DELETE File1 means erase File1)
• Menu interface this type presents a list of
  options from which the user selects to invoke a
  command or system operation
• Graphical user interface (GUI) the most common
  interface today that uses pictures, icons, and
  menus to send instructions form the user to the
  computer system

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Common Operating Systems
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Operating Systems - Utilities
Utilities Programs that manage computer
resources and files and may be included in the
operating system or purchased separately as
needed
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Application Software
Application Software This software performs
specific user functions (e.g. e-mail)

• Customized Application Software
• Software that is developed to meet the
  specification of an organization. This can be
  developed in-house by IS staff or by an outside
  vendor. Advantages include
• Customizability tailored to meet specific needs
• Problem specificity pay for only those
  functions that are developed for and used by the
  organization

Off-the-Shelf Software Packaged software
developed by a vendor for a particular problem or
industry but is not specific to an organization.
This is a lower cost approach that may be
combined with custom development to tailor it
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Types of Application Software
Types of Application Software Application
software come in two types for use by
organizations 1) large business systems and
office automation 2) personal productivity tools

• Business Systems
• These large systems support enterprise-wide
  operations such as
• Accounting -A/P, A/R, general ledger, payroll
• Operations - inventory management, order
  processing, shipping, etc.

• Personal Productivity
• Used by individuals or groups to support a
  variety of common tasks such as
• Communication e-mail, word processing
• Scheduling group calendars
• Analysis - spreadsheets

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Application Software Examples
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Open Source Software
Open Source A special class of software that
includes operating systems, application software,
and programming languages in which the source
code (the actual program code) is freely
available to the general public for use and/or
modification

• Popular Open Source Applications
• A number of mainstream open source applications
  can be found across many organizations. Here are
  just a few
• Operating systems Linux
• Web browsers Mozilla
• Web servers Apache
• E-mail processing Sendmail
• Internet domain naming service BIND
• Secure connection standard - OpenSSL

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Open Source Software
Open Source Initiative (OSI) The OSI is a
certification process developed by the open
source community to ensure that open source
software meets a set of standards

• OSI Standards
• The author or holder of the license of the source
  code (SC) cannot collect royalties on the
  distribution of the program
• The distributed program must make the SC
  accessible to the user
• The author must allow modifications of the work
  under the programs original name
• No person, group, or field of endeavor can be
  denied access to the program
• The rights attached to the program must not
  depend on the programs being part of a
  particular software distribution

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Compilers, Languages, and Environments
Compilers and Interpreters Software designed to
translate programming languages into machine code
or binary in order to allow the computer to
execute the program instructions
Programming Languages Languages used to write
program instructions that have evolved from early
machine language to higher-level languages that
are easier to write and understand
Automated Development Environments Automated
software tools used by systems developers to
design and implement information systems and
increase quality and productivity
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Open Source Software
Compilers These highly-specialized software
applications are used to convert program
instructions (source code) into the machine code
(object code) prior to being loaded into a
computers secondary storage
Compiler Example
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Compilers and Interpreters
Interpreter These specialized software
applications are similar to compilers but instead
of translating the source code to machine
language prior to loading, it reads, translates,
and executes one line of source code at a time
during operation
Interpreter Example
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Programming Languages - Generations
Programming Languages These languages are used to
write program instructions and have evolved over
time making them more powerful, easier to read
and write, and more natural language-focused
Generations of Programming Languages
mid 1950s
1940s
1950s
1970s
1990s
1st Machine Binary
2nd Symbolic Use of symbols
3rd High-Level Use English like words for
procedures
4th Outcome Oriented Use outcome focused words
5th Artificial Intelligence Natural
language (spoken English)
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Popular Programming Languages
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Programming Languages More Recent High-Level

• Object-Oriented Programming (OOP)
• These languages allow programmers to group data
  and program instructions together into modules
  (objects) that can be manipulated by a programmer
  (e.g Java or C). Characteristics of OOPs
  programming include
• Encapsulation grouping pieces of data together
• Inheritance as one class of objects are
  defined, all other objects with the same
  characteristic are automatically defined
• Event-driven these programs are driven by
  events (e.g. a button being pushed) instead of
  following sequential logic

Visual Languages These languages take advantage
of graphical user interfaces (GUIs) allowing
additions of visual objects (e.g. buttons) with a
few clicks versus coding the object pixel by
pixel
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Programming Languages Visual Language example
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Programming Languages Web Development
Web Development Languages These languages are
used to develop Web pages and operations using
both static and dynamic content
Hypertext Markup Language (HTML) This is a
text-based file format that uses a series of
codes, or tags to set up a document. Programming
can be done either in native HTML or using an
HTML editor that generates the HTML code from
visual renderings
Extensible Markup Language (XML) XML was
designed to be used as a Web page construction
tool allowing users to create markup tags or
build database queries. It is a powerful
language used to create database fields for
accessing databases from Web pages and can be
read using a browser called an XML parser
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Programming Languages Common HTML Tags
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Programming Languages Web Development
Dynamic Content Markup languages are used for
laying out or formatting content, while dynamic
languages are needed to provide animation or
dynamic (changing) content

• Dynamic Languages
• Several languages are available for creating
  dynamic content such as
• Java Invented by Sun Microsystems, this
  language is very popular for use in Web pages to
  provide animation (applets) or for writing more
  general purpose programs allowing them to run on
  all platforms
• ActiveX Invented by Microsoft to perform the
  same function as Java but is designed to run
  under MS Windows
• Scripting Languages (JavaScript) this language
  allows the direct inbedding of program functions
  (scripts) into HTML pages and is frequently used
  for validation of user input (e.g. validate zip
  code)

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Programming Languages A Java Enabled Web Page
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Processing Automated Development Environments
Computer-aided Software Engineering (CASE) These
are automated software tools used by systems
developers to design and implement information
systems. These tools continue to evolve and come
in many types
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Automated Development Environments A CASE Tool
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Automated Development Environments CASE
Influence
Influence of CASE Tools on Individuals CASE can
dramatically increase the speed and quality of
system development and maintenance while having a
strong impact on culture. For IS managers it is
commonly positive due to higher quality and lower
risk, while for IS developers it is often
negative for fear of replacement