Managing information technology
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Managing Information Technology. CHAPTER 3 COMPUTER SOFTWARE. EVOLUTION OF COMPUTER PROGRAMMING. First and Second Generation Languages. Machine language (1GL) Each instruction must be expressed in unique form for a particular computer Complete program consists of thousands of instructions

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Managing Information Technology

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Managing Information Technology

CHAPTER 3COMPUTER SOFTWARE


EVOLUTION OF COMPUTER PROGRAMMING

First and Second Generation Languages

  • Machine language (1GL)

    • Each instruction must be expressed in unique form for a particular computer

    • Complete program consists of thousands of instructions

    • Programming is a tedious, time-consuming process

  • Assembly languages (2GL)

    • Easily remembered mnemonic operation codes substituted for machine language operation codes

    • Assembler used to convert mnemonic codes to machine language


EVOLUTION OF COMPUTER PROGRAMMING

First and Second Generation Languages


EVOLUTION OF COMPUTER PROGRAMMING

Third and Fourth Generation Languages

  • Procedural languages (3GL)

    • Typically machine independent

    • Express a step-by-step procedure devised by the programmer

    • Must be compiled or interpreted (translated into machine language)

    • Include FORTRAN, COBOL, BASIC, PL/1, PASCAL, ADA, and C


EVOLUTION OF COMPUTER PROGRAMMING

Third and Fourth Generation Languages


EVOLUTION OF COMPUTER PROGRAMMING

Third and Fourth Generation Languages

  • Nonprocedural languages (4GL)

    • Also referred to as productivity languages

    • Use more English-like statements for program instructions

    • Easier to use, write, and less error-prone

    • Use a built-in interpreter to convert to machine language

    • Take much longer to execute than 3GLs

    • Include FOCUS, CA-Ramis, IFPS, and SAS


EVOLUTION OF COMPUTER PROGRAMMING

Third and Fourth Generation Languages


EVOLUTION OF COMPUTER PROGRAMMING

Third and Fourth Generation Languages

  • Object-oriented languages

    • 3GLs with some 4GL features

    • Built on idea of embedding procedures (methods) in objects, and putting objects together to create an application

    • Include Smalltalk, C++, Java, and Visual Basic


KEY TYPES OF SOFTWARE

  • Applications software

  • Support software


APPLICATIONS SOFTWARE

  • Programs written to accomplish particular tasks

  • Many different types of applications software

  • Standard applications products generally purchased from an outside source

  • Applications unique to the organization generally developed internally

  • Personal productivity software most important to managers


APPLICATIONS SOFTWARE

Examples of Application Software

  • Peachtree accounting software

    • Commercial accounting package for smaller businesses

    • Includes general ledger, accounts receivable, accounts payable, inventory, payroll, time and billing, job costing, fixed asset accounting, and analysis and reporting tools

    • $500 for single-user version


APPLICATIONS SOFTWARE

Examples of Application Software

  • Sage Accpac 200 ERP

    • Modular financial management systems for midsized businesses

    • Web-based, so only a Web browser is needed to access the application

    • System Manager module manages security, ensures data integrity, handles bank reconciliation and tax processing, and allows for customized reports

    • Several other modules available as well


APPLICATIONS SOFTWARE

Personal Productivity Software

  • Word processing

    • Used to create documents for printing

    • Most popular is Microsoft Word

    • Others include Corel WordPerfect, Lotus WordPro, and Sun’s StarOffice Writer

    • All employ WYSIWYG


APPLICATIONS SOFTWARE

Personal Productivity Software

  • Spreadsheets

    • Used to create applications that fit a row-column format

    • Most popular is Microsoft Excel

    • Others include Lotus 1-2-3 and Corel Quattro Pro

    • All employ rows, columns, cells, formulas, and “what-if” analysis


APPLICATIONS SOFTWARE

Personal Productivity Software

  • Database management systems

    • Used to create databases similar to those on larger machines

    • Most popular is Microsoft Access

    • Others include FileMaker Pro, Corel Paradox, and Lotus Approach

    • All employ a relational data model


APPLICATIONS SOFTWARE

Personal Productivity Software

  • Presentation graphics

    • Used to create largely textual business presentations

    • Most popular is Microsoft PowerPoint

    • Others include Corel Presentations and Lotus Freelance Graphics

    • All allow embedding of clip art, photos, graphs, and other media


APPLICATIONS SOFTWARE

Personal Productivity Software

  • Web browsers

    • Used to access information on the Web

    • Requires ISP service to link PC to Internet

    • Create documents for printing

    • Most popular are Internet Explorer and Firefox… both free!

    • Both employ standard hypertext-based approach (way to link text and media objects to each other)

    • Pull technology: browser requests a Web page before it is sent to desktop

    • Push technology: data sent to client without requesting it (such as e-mail)


APPLICATIONS SOFTWARE

Personal Productivity Software

  • Electronic mail

    • Preferred way of communicating in business today

    • Easy to use and precise

  • Groupware

    • Incorporates e-mail and other productivity features, such as calendaring, scheduling, and document sharing


SUPPORT SOFTWARE

  • Provides computing environment that is easy and efficient for humans to use

  • Enables applications programs to be carried out

  • Ensures that computer hardware and software are used efficiently

  • Almost always purchased from a hardware vendor or software house


SUPPORT SOFTWARE

Operating System

  • Most important type of support software

  • Complex program that controls operation of computer hardware and coordinates other software

  • User communicates with operating system software to control hardware and software resources

  • Communication made easier with a graphical user interface (GUI) feature


SUPPORT SOFTWARE

Operating System


SUPPORT SOFTWARE

Operating System

  • Job control language (JCL): keyed instructions from the computer user to communicate with the operating system

  • Multiprogramming: employed on larger machines to overlap input and output operations with processing time, keeping the CPU busy and speeding up execution

  • Multitasking: similar to multiprogramming, but employed on microcomputers

  • Multithreading: similar to multitasking, but multiple threads within the same program are overlapped


SUPPORT SOFTWARE

Operating System

  • Virtual Memory:

    • Concerned with management of main memory

    • Makes it appear that an unlimited amount of memory is available

    • Permits multiprogramming to operate more efficiently

  • Multiprocessing: work that takes place when two or more CPUs are installed on same computer system


SUPPORT SOFTWARE

Operating System

  • Sources of operating systems

    • Proprietary systems: most popular type of operating systems, written for a particular computer hardware configuration

      • Microcomputers: MS-DOS, PC-DOS, Windows XP

      • Midrange systems: OS/400

      • Large systems: VM and MVS

    • Open systems: not tied to any particular computer system or hardware manufacturer – will run on virtually any computer system

      • Examples: UNIX and Linux


SUPPORT SOFTWARE

Operating System

  • Network operating systems (NOS)

    • Software running on a server that manages network resources and controls the operation of a network

    • Enhanced operating system that allows for:

      • Sharing disk drives and printers

      • Handling server side of client/server applications

    • Major players include:

      • UNIX and Linux

      • Microsoft Windows NT, 2000 Server, 2003 Server

      • Novell NetWare


SUPPORT SOFTWARE

Third Generation Languages

  • Procedural languages (3GL)

    • Require logical thinking

    • Entail development of a detailed step-by-step procedure

    • Can be developed using structured programming


SUPPORT SOFTWARE

Third Generation Languages


SUPPORT SOFTWARE

Third Generation Languages

  • Structured programs

    • Divided into modules, where each has one entry and one exit point

    • Advantages

      • Program logic easier to follow

      • Maintenance and correction easier and faster

      • Do not use GO TO logic


SUPPORT SOFTWARE

Third Generation Languages

  • Most popular procedural languages

    • BASIC

    • C

    • COBOL

  • Other procedural languages

    • FORTRAN

    • PL/1

    • PASCAL

    • ADA


SUPPORT SOFTWARE

Third Generation Languages - BASIC


SUPPORT SOFTWARE

Third Generation Languages - COBOL


SUPPORT SOFTWARE

Fourth Generation Languages

  • Nonprocedural languages

    • Use very high-level instructions

    • Require fewer instructions

    • Easier to write, modify, and understand

    • Example: FOCUS


SUPPORT SOFTWARE

Fourth Generation Languages - FOCUS


SUPPORT SOFTWARE

Markup Languages

  • Employ tags to “mark up” documents

  • HTML

    • Used to create Web pages

    • Consists of special tags that tell the Web browser how to display various elements on a Web page (e.g., bold-faced or italic text, image location, links to other Web pages)

  • XML

    • Used to facilitate data interchange among Web applications

    • Metalanguage consisting of tags that identify particular data elements


SUPPORT SOFTWARE

Object-Oriented Programming

  • Requires more computing power

  • Has built-in GUI

  • Neither 3GL nor 4GL … new paradigm

  • Creates objects only once and stores for reuse

  • Object examples:

    • Text box, check box, entity in an organization

  • Languages:

    • Smalltalk, C++, Java, Visual Basic.NET


SUPPORT SOFTWARE

Object-Oriented Programming - Java


SUPPORT SOFTWARE

Languages for Developing Web Applications

  • HTML form is the most common user interface encountered by users

  • Server-side programming languages include:

    • Perl

    • Java Servlets and Java Server Pages

    • Microsoft Active Server Pages (ASP, ASP.NET)

    • ColdFusion


SUPPORT SOFTWARE

Languages for Developing Web Applications


SUPPORT SOFTWARE

Database Management Systems

  • Support software used to create, manage, and protect organizational data

  • Database: shared collection of logically related data organized to meet organizational needs

  • Five basic architectures:

    • Hierarchical

      • Data are arranged in a top-down organization chart fashion

      • Example: IBM Information Management System (IMS)


SUPPORT SOFTWARE

Database Management Systems

  • Five basic architectures:

    • Network

      • Data are arranged like cities on a highway system, often with several paths from one piece of data to another

      • Example: Computer Associates Advantage CA-IDMS

    • Relational

      • Most common type

      • Data arranged in simple tables

      • Records related by storing common data in each associated table

      • Examples: Microsoft Access and SQL Server, Paradox, DB2, and Ingres


SUPPORT SOFTWARE

Database Management Systems

  • Five basic architectures:

    • Object-oriented

      • Data can be graphics, video, and sound as well as simpler data types

      • Attributes and methods are encapsulated in object classes, and relationships between classes can be shown by nesting one class within another

      • Examples: Versant Object Database, Progress ObjectStore, and Objectivity/DB

    • Object-relational

      • Hybrid approach that can handle complex data types with the simplicity of the relational model

      • Examples: Oracle, IBM’s DB2 and Cloudscape, and FFE Software’s FirstSQL/J


SUPPORT SOFTWARE

File Organizations

  • Sequential: arranges records physically adjacent and in order by some (usually unique) sort key

  • Direct: uses key for records placed so that they are rapidly accessed from DASDs


SUPPORT SOFTWARE

File Organizations

  • Indexed

    • Compromise between sequential and direct

    • Record keys only arranged in sequence in a separate table, along with location of rest of data associated with that key

    • Popular types include ISAM and VSAM


SUPPORT SOFTWARE

CASE Tools

  • Computer-aided software engineering (CASE)

  • Collection of software tools to help automate all phases of the software development life cycle

  • Growth slower than anticipated

  • Radically changed nature of systems analyst and programmer jobs


SUPPORT SOFTWARE

CASE Tools

  • Recent surge in CASE tools for Unified Modeling Language (UML)

    • UML is a general-purpose notational language for specifying and visualizing complex software, especially large, object-oriented projects

    • Examples of UML-base CASE tools

      • IBM’s Rational Rose

      • Borland’s Together

      • Sybase’s PowerDesigner


SUPPORT SOFTWARE

Communications Interface Software

  • Large computers

    • Need to control workstations and terminals

    • Example software: IBM’s CICS, TSO, and CMS

  • Increasingly important with growth of LANs and WANs

  • Web browsers: enable users to look around, or “browse,” the Internet

  • Telnet: permits user to log into remote computer

  • File Transfer Protocol (FTP): used to transfer files from one computer system to another


THE CHANGING NATURE OF SOFTWARE

  • Less concern with machine efficiency

  • More purchased applications, and, conversely, more use of open source support software, such as Linux

  • More programming using object-oriented languages

  • More emphasis on applications that run on intranets and the Internet

  • More user development

  • More use of personal productivity software on microcomputers


THE SOFTWARE COMPONENT OF THE INFORMATION SYSTEMS INDUSTRY

Major Groups

  • Hardware manufacturers

    • IBM, Hewlett-Packard, Sun Microsystems, Hitachi, and Fujitsu

  • Software houses

    • Microsoft, Oracle, SAP, Computer Associates, and Symantec

  • Consulting firms

    • PricewaterhouseCoopers Consulting (bought by IBM)


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