Information Systems Software

1. Information Systems Software Chapter 3

2. 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

3. 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

4. Key Information Systems Software Issues • Data • Raw material, recorded, unformatted information • Information • Formatted data • Knowledge • Accumulated information • Wisdom • Accumulated knowledge

5. 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

6. 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

7. 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)

8. 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

9. Operating Systems Interfaces

10. 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

11. 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 Examples of Information Systems Application Software

12. 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

13. 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

14. 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

15. How a Compiler Does its Job How an Interpreter Does its Job

16. 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

17. 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

18. Second Generation:Assembly Language • Bits replaced with letters • Easier to understand • Converted to machine language by assemblers

19. 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

20. Fourth Generation:Outcome-Oriented Languages • Sentence-like statements • Focus on desired output rather than procedures • Often used to ask queries of a database

21. Fifth Generation:Natural Languages • User communicates in English sentences • Used for document searches and retrievals, and database queries • Still being further developed

22. 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

23. 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++

24. 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”