Information Systems Software

Chapter 3

Chapter Objectives• Understand the importance of information

systems software for today’s organizations• Describe the common functions of system

software• Explain the various types of application software• Describe characteristics of various types of

programming languages• Discuss evolution of computer software

The Increasing Importance of Software to Organizations

• Shift in technology costs– Declining hardware costs– Increasing complexity of software with

increased costs– Increasing salaries of programmers

• Software aids in “re-engineering” of the organization

• Software helps standardize business procedures

Key Information Systems Software Issues

• Data – Raw material, recorded, unformatted information

• Information – Formatted data

• Knowledge – Accumulated information

• Wisdom – Accumulated knowledge

Key Information Systems Software Components

• Software – A program or set of programs that control the

operation of computer hardware

• Program– A set of coded instructions read and executed

by a computer

• Documentation – A set of instructions that assist the user in

operating the computer program

Systems Software • Also called the “operating system”• Collection of programs that control basic

operations of the computer hardware• Goal - to make computer operations

transparent to users

Common Systems Software Functions

• Performs system operations– Booting the computer– Reading programs into memory– Managing memory allocation of programs– Maintaining structure of directories– Controlling peripherals

• Provides an interface for the user– Command-based interface– Graphical user interface (or GUI)

Types of Operating Systems

• MVS/ESA - IBM mainframe

• UNIX - many platforms, but mainly used on workstations

• MS-DOS - original Microsoft command interface for PCs

• OS/2 - PC operating system by IBM

• Windows - Microsoft GUI

• Macintosh OS

Operating Systems Interfaces

Application Software

• Allows user to perform a specific task – Write a letter– Balance your checkbook– Send an e-mail

• Interacts with the systems software• Two basic types

– Customized– Off-the-shelf

Examples of Information Systems Application Software• Business

Information Systems– Perform

organization-wide operations of firm

– Payroll– Inventory– General accounting

• Office Automation/ Personal Productivity– To accomplish a wide

range of tasks– Word processing– Spreadsheets– Database– E-Mail– Web browser

Programming Language

• A computer program used to write other computer programs

• Used to develop all application software

• Invisible to the user

• Many different languages exist

Some Common Languages• BASIC

– Simple language for novice programmers

• C/C++ – Powerful general-purpose language – C++ is object-oriented version

• COBOL– Language for business applications

• Java– Language used to develop Web applications

Compilers and Interpreters

• Translate program code into machine code

• Compilers– Translate the program into a new, separate

machine language program

• Interpreters– Convert each line of code to machine language– Execute each line code– Conversion/execution done one line at a time

How a Compiler Does its Job

How an Interpreter Does its Job

The Evolution of Information Systems Software

• First Generation: Machine Language

• Second Generation: Assembly Language

• Third Generation: High-level Languages

• Fourth Generation: Outcome-Oriented Languages

• Fifth Generation: Natural Languages

First Generation:Machine Language

• Binary code– Binary digits are 0 and 1– Each digit called a “bit”

• Tells computer which circuits to turn on and off

• A low-level language• High-level languages converted to

machine language

Second Generation:Assembly Language

• Bits replaced with letters– Easier to understand

• Converted to machine language by assemblers

Third Generation:High-level Languages

• Symbolic code– English-like words and commands

• One high-level instruction translates to many machine language instructions

• Different languages appropriate for different tasks– COBOL: data processing– JAVA: Web

Fourth Generation:Outcome-Oriented Languages• Sentence-like statements

• Focus on desired output rather than procedures

• Often used to ask queries of a database

Fifth Generation:Natural Languages

• User communicates in English sentences

• Used for document searches and retrievals, and database queries

• Still being further developed

Object-Oriented Languages

• Objects– Group data with instructions related to that data

• Encapsulation– Process of grouping the data and instructions

• Inheritance– Nodes inherit the characteristics of parent nodes

• Make programs easier to maintain • Create easily reusable code

Visual Programming Languages

• Allow programmer to create today’s graphic-intensive applications

• Based on libraries of common reusable objects

• Programmer drags and drops objects onto a preformatted form

• Examples are Visual Basic and Visual C++

Emerging Trends in Software• Merging of Hardware and Software

– Small computers contain software directly programmed on a microchip

– Designed to perform a single task or set of tasks

• Integrated Telecommunications– Software tied to telecommunications

• Global Positioning System (GPS)• World Wide Web• Java “applets”