Objectives
• Understand differences between programming languages generations
• Explain how application software differs from system software
• Understand the strengths and weaknesses of custom vs. off-the-shelf software
• Be familiar with the latest developments in application and system software
• Have the basic tools for evaluating packaged software applications for business use.

Software: Instructions to the Computer
• A computer program is a series of instructions to a computer to execute any and all processes
• All instructions are made up of series of electrical signals alternation between two states, either on or off

Programming Languages
• Machine language
• The only language the computer understands.
• Represented as a series of ones and zeros.

• Programming languages
– Abbreviated forms of instructions that are automatically translated into machine language.

• Running Programs
– Translating the program into machine language and sending the CPU instructions

Levels of Programming Languages
• Different levels of programming languages are grouped by generations.
• Machine Languages
• Assembly Language
• Procedural Languages
• Fourth Generation Languages

Object Orientated Languages
• Fundamentally different than earlier generations

– Combines Data and Instructions
– Goal is to simulate a situation

Object
• An object encapsulates a set of data with the code that is used to operate on it.
• Object Characteristics

– Methods
– Attributes
– Inheritance
– Encapsulation

Application vs. System Software
• Application Software addresses specific needs. It works with system software to implement a solution.
• System software includes programs that are designed to carry out general operational routines such as loading and displaying files.

Application Software
• Either addresses specific needs or allows a user to develop systems that satisfy specific needs.
• Application specific software are programs that are designed to perform specific jobs.
• General purpose application software, such as spreadsheets, are used for entire application categories.

Custom Designed Applications
• If an organization develops the software itself for its specific purposes, it is referred to as a custom designed application.
• Advantages: Good fit, good potential maintenance.
• Disadvantages: High cost, long lead time, may be difficult to interface.

Shrink Wrap Solutions
• Also known as Off-the-shelf software.
• Advantages: Cost, quality, support, availability.
• Disadvantages: Still needs to be adopted to the companies needs.

Word Processing
• Most widely used type of software.
• Desktop publishing features.
• Internet interoperability.
• Web publishing features.

Spreadsheets
• Primary purpose is analysis and simulation.
• Data Modeling allows the user to simulate a situation.

– What if analysis.
– Linear problem solving

Data Base Management Systems
• Storage and reporting of information.
• Unlike other micro software packages is not dominated by a single app.
• SQL server is the open standard.
• Access, SQL Server, Oracle.
• Relational methodology is the norm.

Suites
• As users demand document centric computing, integration becomes more important.
• Suites guarantee integration.
• Note that each suite is becoming more object orientated.

– OO supports document centric computing.

Multimedia
• Multimedia means integration multiple types of data (Graphics, audio, video)

– Normally is user driven and non linear
– Made possible by OO

Virtual Reality
• Mimics sensory reality using software.
• Aircraft simulators.
• Internet Aviators.
• Medical applications

– Teaching surgery
– Distance diagnosis

Compilers and Interpreters
• A compiler scans the entire source code, looks for syntactic errors, and execution errors. When appropriate, it translates the source code into object code that the computer executes.
• An interpreter checks one statement at a time. And the computer executes its output one line at a time.

Proprietary vs Open Systems
• A proprietary system is one that is owned by a single company and leased to customers. It is usually an annual lease/maintenance agreement.

– Application software is O/S specific and custom apps cannot be ported.

Proprietary Systems
• Lock in customers.
• Once you have thousands of person years invested in programs, you are reluctant to start over.
• Movement is firmly away from these type of systems.

Open Systems
• While still a goal, O/S’s with open characteristics are becoming dominant.
• Unix -- several flavors.
• Windows -- single source but many open characteristics.
• Originally Open referred to hardware.

Principles