Transcript 0619213221_236885

Chapter 5
Information Systems
in Business: Software
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Learning Objectives
• Explain why professionals must keep abreast of
software developments
• Enumerate the different generations of
programming languages and explain how they
differ
• Explain the difference between application
software and system software
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Learning Objectives (Cont.)
• Compare the strengths and weaknesses of tailored
software versus off-the shelf software
• Cite the latest major developments in application
and system software
• List characteristics that are important in
evaluating packaged software applications for
business use
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Software: Instructions
to the Computer
• A computer program is a series of instructions to a
computer to execute any and all processes
• Computers only “understand” instructions consisting
of electrical signals alternating between two states
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Software: Instructions
to the Computer (Cont.)
• Application software enables users to complete a
particular task, such as word processing
• System software enables application software to run
on a computer and manages the interaction between
hardware devices
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Programming Languages
• Abbreviated forms of instructions that translate into
machine language
• New programming languages make programming
easier for people who are not necessarily hardware
experts
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Programming Languages (Cont.)
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First Generation: Machine
Languages (ML)
• Only languages computers can directly interpret to
carry out instructions
• ML coding: time-consuming and error-prone
• ML programmers: concerned with hardware details
• Every computer or family of computers has its own
ML; each is machine-dependent
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Second Generation: Assembly
Languages
• Represent a string of ‘0s’ and ‘1s’ for machine
language instruction
• More English-like; codes shorter than machine
languages
• Assembler translates into machine language
• Advantages of machine or assembly languages
– Programmer in control of hardware
– Programs written in low-level languages run more
efficiently
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Third Generation: Procedural
Languages
• Third-generation (procedural) languages are more
English-like than assembly languages
• Programmers focus on the procedure of the
application problem at hand
• Some languages are standardized or portable
• Relatively easy to learn, write, and debug
• FORTRAN, COBOL, BASIC
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Fourth Generation Languages (4GL)
• 4GLs are more English-like than procedural
languages
• Programmer only has to select an action without
having to specify the action’s formula or
procedure
• Easy to learn and use; shorter application
development time
• PowerBuilder, FOCUS, NOMAD, and RAMIS
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Fourth Generation Languages
(Cont.)
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Visual Programming
• Languages that let programmers create field
windows, scroll-down menus, click buttons, etc.,
by choosing from a palette
• Appropriate code written automatically
• Accelerates work
• Microsoft’s Visual Basic
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Object-Oriented Programming
(OOP)
• Emphasis on the objects involved in the task, not
on the procedure
• An object encapsulates a data set with the code
that is used to operate on it
• Standardized programming modules can be reused
• Applications can be rapidly developed with
appropriate objects from an object library
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Object-Oriented Programming
(OOP) (Cont.)
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The object EMPLOYEE
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Application Software vs. System
Software
• Application:
– Program developed to address a specific
business need; software for development of
such programs
• System:
– Programs designed to carry out general routine
operations, such as loading, copying, or
deleting a file
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Programming Languages (Cont.)
– Levels of Programming Languages: Pluses
and Minuses
– Language Translation: Compilers and
Interpreters
• Source code
• Object code
• Compiler
• Interpreter
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Programming Languages (Cont.)
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Programming Languages (Cont.)
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Bugs
• Errors in a program to be eliminated before it
runs smoothly
• Occur when a certain operation cannot be
carried out
• Logic errors are most difficult to spot
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Application Software
• Application-specific programs
– Programs designed to perform specific jobs
• General-purpose programs
– Usable for different purposes
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Custom-Designed Application
Advantages
• Meeting the organization’s needs exactly
• In-house developers are sensitive to the
organizational culture
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Custom-Designed Application
Disadvantages
• High cost
• Production schedule subject to long delays
• Incompatible with other organizations’ systems
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Advantages and Disadvantages
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Packaged Software
• Advantages:
– Low cost
– High quality
– Vendor support
– Immediate availability
• Often tested at user sites (alpha sites and beta
sites) before the final version is released
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Packages Software (Cont.)
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Packaged Software (Cont.)
• Word processors
• Electronic spreadsheets
• Database management systems
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Packaged Software (Cont.)
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Multimedia
• Can handle many different types of data such as
text, voice, and image
• Powerful means of communicating
• Uses include education, training, research, and
business
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Virtual Reality (VR)
• Mimics sensory reality
• Some sophisticated VR software includes use of
goggles, gloves, earphones, and a moving base
• Business use of VR is expected to grow
dramatically for design and testing of new
products, and for marketing
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System Software
• Manages computer resources and performs
routine tasks not specific to any application
– Copying and pasting sections and files
– Printing documents
– Allocating memory
• Developed to partner with application
software
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Operating Systems (O/S)
• Most important system software
– Developed for a certain microprocessor or
microprocessors
– Addresses technical details such as registers and
RAM addresses
– Plays the role of “traffic cop” or the “boss” of
computer resources
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Operating Systems (O/S) (Cont.)
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System Software
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Operating System Functions
• Systems Management
• User Interface
• Memory Allocation
• Multitasking, Multiprogramming, and
Multiprocessing
• Times and Statistics
• Increasing Services from O/Ss
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Popular Operating Systems
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Data Communication Programs
• Controls and supports data communication
activities in a network
– Setting up rules that govern transmission and
reception of data
– Connecting and disconnecting communication
links
– Assigning priorities among terminals in a network
– Detecting and correcting transmission errors
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Linux and the Open Source
Revolution
• Proprietary software: source code of the
software public
• Open source software: source code can be
obtained free of charge
• Contains fewer bugs because thousands of
independent programmers review the code
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Considerations in Purchasing
Software
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Considerations in Purchasing
Software (Cont.)
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Summary
• Software developments and the impact on
business
• Application software versus operating system
software
• Tailored software versus off-the-shelf software
• Major developments in application and system
software
• Evaluation of package software
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