Computer Software Basics

Types of software

Software types

• Application software

Performs information processing tasks for end users

• System software

Manages and supports operations of computer systems and networks

Application software

• General purpose

Programs that perform common information processing jobs for end users

E.g., word processing, spreadsheet, etc.

Also called productivity packages

• Application-specific

Programs that support specific applications of end users

E.g., electronic commerce, customer relationship management, etc.

Software classifications

• Classify based on how it was developed
• Custom software

Software applications that are developed within an organization for use by that organization

• COTS software

Commercial Off-the-shelf (COTS)

Software developed with the intention of selling the software in multiple copies

• Why would you choose Custom over COTS?
• Why would you choose COTS over Custom?

Software Suites

• Software suites integrate software packages

Advantages:

• Cost less than buying individual packages
• All have a similar GUI
• Work together well

Disadvantages

• Features not used by all users
• Take a lot of disk space

Integrated Packages

• Integrated packages

- Combine the functions of several programs into one package

- E.g., Microsoft Works, AppleWorks

Advantages:

• Many functions for lower price and smaller disk space

Disadvantage

• Limited functionality

Web Browser

• Software applications that support navigation through the point-and-click resources of the Web
• Surfing the web
• Becoming a universal software platform for Internet-based applications
• Microsoft Explorer, Netscape Navigator, Firefox, Opera or Mozilla

E-mail, Instant Messaging and Weblogs

• E-mail

                 - Software to communicate by sending and receiving messages and attachments via the Internet, intranet or extranet

• Instant messaging (IM)

                  - Receive electronic messages instantly

• Weblog or blog

                  - A personal website in dated log format

                  - Updated with new information about a subject or range of subjects

Word processing and Desktop publishing

• Word processing
        - Create, edit, revise and print documents
        - E.g., Microsoft Word, Lotus WordPro and Corel WordPerfect
• Desktop Publishing
        - Produce printed materials that look professionally published
        - E.g., Adobe PageMaker, Microsoft Publisher and QuarkXPress

Electronic Spreadsheets and Presentation Graphics

• Electronic Spreadsheets

              - Worksheet of rows and columns

              - Used for calculations and charts

              - E.g., Lotus 1-2-3, Microsoft Excel, Corel QuattroPro

• Presentation Graphics

             - Convert numeric data into graphics displays

             - Prepare multimedia presentations including graphics, photos, animation, and video clips

             - E.g., Microsoft PowerPoint, Lotus Freelance, Corel Presentations

Personal Information Manager and Groupware

• Personal Information Manager (PIM)

               - Software for end user productivity and collaboration

               - Store information about clients, schedules, manage appointments, manage tasks

               - E.g., Lotus Organizer, Microsoft Outlook

• Groupware

                - Software that helps workgroups collaborate on group assignments

                - E-mail, discussion groups, databases, videoconferencing

                - E.g., Lotus Notes, Novell GroupWise, Microsoft Exchange

Sources of Software

Proprietary and Off-the-Shelf Software

 Software : for sale/free/rent

• Commercial software:

                  - proprietary software or package software 

                  - Copyright : exclusive legal right

                  - Software license : the right to use

                  - You don’t buy software: you buy a license to 

                     use the software under the terms

                    of  the licensing agreement

                  - Licensed to protect the vendor’s property right

• Public-domain software

                 - not protected by copyright

                 - For ex: open source software

Software : for sale, for free or for rent ?

• Shareware

                 - distributed free of charge but requires users to make a monetary contribution to

                  continue using it

• Freeware

                  - Copyright software that is distributed free of charge

• Rentalware

                   - The users lease software

• Pirated software  # counterfeit software

System software

• Software that manages and supports a computer system
• System management programs

               - Programs that manage hardware, software, network, and data resources

               - E.g., operating systems, network management programs, 

                    database management systems, systems utilities

• Systems development programs

               - Programs that help users develop information system 
                  programs

Operating System

Integrated system of programs that  

                  - Manages the operations of the CPU

                  - Controls the input/output and storage resources and

                    activities of the computer system

                  - Provides support services as computer executes 

                    applications programs

Operating System basic functions

User Interface

• Part of the operating system that allows you to communicate with it
• Three main types:

               - Command-driven

               - Menu-driven

               - Graphical user interfaces (GUI)

Resource management 

• Part of operating system that manages the hardware and networking resources of a computer system

               - Includes CPU, memory, secondary storage device,  
                 telecommunications, and input/output peripherals

• Virtual memory

        - Swapping parts of programs and data between memory

          and magnetic disks

File management

• Part of the operating system that controls the creation, deletion, and access of files of data and programs

Task Management

• Part of the operating system that manages the accomplishment of computing tasks of the end users

Multitasking

         - Task management approach that allows for several tasks to be performed in a  seemingly simultaneous fashion

•   Assigns only one task to CPU but switches between tasks so quickly looks like executing all programs at once                                                                                                                     -  Also called multi programming or time-sharing

Popular Operating Systems

• Windows

            - GUI, multitasking, networking, multimedia

            - Microsoft’s operating system

            - Different versions manage servers

• Unix

            - Multitasking, multiuser, network-managing

            - Portable – can run on mainframes, midrange and PCs

• Linux

            - Low-cost, powerful reliable Unix-like operating system

            - Open-source

• MAC OS X

            - Apple operating system for the iMac

            - GUI, multitasking, multimedia

Other system software

• Utilities

              - Miscellaneous housekeeping functions

              - Example, Norton utilities includes data backup, virus protection, data compression, etc.

• Performance monitors

              - Programs that monitor and adjust computer system to keep them running efficiently

• Security monitors

              - Programs that monitor and control use of computer systems to prevent unauthorized 

                 use of resources

Programming Languages

Machine Languages

• First-generation languages
• All program instructions had to be written using binary codes unique to each computer
• Programmers had to know the internal operations of the specific type of CPU

Assembler Languages

• Second-generation languages
• Symbols are used to represent operation codes and storage locations
• Need language translator programs to convert the instructions into machine instructions
• Used by systems programmers (who program system software)

High-Level Languages

• Third-generation languages
• Instructions that use brief statements or arithmetic expressions
• Macro instructions:  each statement generates several machine instructions when translated by compilers or interpreters
• Easier to learn than assembler
• Machine independent
• Less efficient than assembler

Fourth-Generation Languages

• Variety of programming languages that are non procedural and conversational
• Non procedural – users specify results they want while computer determines the sequence of instructions that will accomplish those results
• Natural Language – very close to English or other human language

Object-Oriented Languages

• Combine data elements and the procedures that will be performed upon them into Objects
• E.g., an object could be data about a bank account and the procedures performed on it such as interest calculations

• Most widely used software development languages today
• Easier to use and more efficient for graphics-oriented user interfaces
• Reusable:  can use an object from one application in another application
• E.g., Visual Basic, C++, Java

Web Languages

• HTML 
• A page description language that creates hypertext documents for the Web
• XML
• Describes the contents of Web pages by applying identifying tags or contextual labels to the data in Web documents
• Java
• Object-oriented programming language that is simple, secure and platform independent
• Java applets can be executed on any computer

Web Services

• Software components 
• based on a framework of Web and object-oriented standards and technologies 
• for using the Web 
• to electronically link the applications of different users and different computing platforms

Language Translator Programs

• Translate instructions written in programming languages into machine language
• Assembler

              - translates assembler language statements

• Compiler 

             - translates high-level language statements

• Interpreter

             - compiler that translates and executes each statement in a program one at a time

             - Java is interpreted