MANAGINGINFORMATIONTECHNOLOGY CHAPTER 3 C OMPUTER S OFTWARE

MANAGINGMANAGINGINFORMATIONINFORMATIONTECHNOLOGYTECHNOLOGY

CHAPTER 3

COMPUTER SOFTWARE

1. Machine language (1GL) Each instruction must be expressed in unique form for a particular computer Complete program consists of thousands of instructions Programming was tedious, time-consuming process

2. Assembly languages (2GL) Use computer itself to perform many aspects of the programming Create a machine language program as output, that is then used by the

computer’s control unit

First and Second Generation Languages

EVOLUTION OF COMPUTER PROGRAMMING

First and Second Generation Languages


SOURCEPROGRAM

OBJECTPROGRAM

(which can be directly executed

on computer)

3. Procedural Languages (3GL) Generally are machine independent. Express a step-by-step procedure developed by programmer Must be compiled or interpreted (translated into machine

language) Include FORTRAN, COBOL, BASIC, PL/1, PASCAL, ADA,

and C

Third and Fourth Generation Languages


Figure 3.2 Compiling and Running a Procedural Language Program

SOURCEPROGRAM

OBJECTPROGRAM

Figure 3.3 Interpreting and Running an Interpretive Language Program

SOURCEPROGRAM

4. 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



Object-Oriented (Visual) 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



1. Applications software

2. Support software

KEY TYPES OF SOFTWARE

Figure 3.4 The Software Iceberg

Spheres of Influence & Application Software

Personal

Workgroup

Enterprise

• programs that serve the needs of an individual user• word processing, spreadsheets, databases, e-mail

• programs that support the firm in its interaction with its environment• order entry, billing

• Two or more people who work together to achieve a common goal• Systems that support information sharing, group scheduling, group decision making, and conferencing

Programs written to accomplish particular tasks Diverse … some general-purpose and some specific Examples include:

General ledger accounting Portfolio management Sales forecasting Material requirements planning (MRP) Electronic mail Desktop publishing

APPLICATIONS SOFTWARE

Peachtree Accounting Complete 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

$300 for single-user version

APPLICATIONS SOFTWAREExamples of Applications Packages

Figure 3.5 “My Business Page” from Peachtree Complete Accounting

Word processing Spreadsheets Presentation graphics Electronic mail and groupware Database management systems Desktop publishing Web browsers Statistical packages

APPLICATIONS SOFTWAREPersonal Productivity Software

Word processing Used to create documents for printing Most popular is Microsoft Word Others are Corel WordPerfect, Lotus Word Pro, and Sun’s StarOffice

Writer All employ WYSIWYG


Spreadsheets Used to create applications that fit a row-column format Most popular is Microsoft Excel Others are Lotus 1-2-3 and Corel Quattro Pro All employ rows, columns, cells, formulas, “what-if” analysis


Database Management Systems Used to create databases similar to those on larger machines Most popular is Microsoft Access Others are FileMaker Pro, Corel Paradox, and Lotus Approach All employ a relational data model


Presentation Graphics Used to create largely textual business presentations Most popular is Microsoft PowerPoint Others are Corel Presentations and Lotus Freelance Graphics All allow embedding of clip art, photos, graphs, and other media


World Wide 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 Netscape Navigator … both free! Both employ standard hypertext-based approach (way to link text and media objects to each other) Use pull technology – browser requests a Web page before it is sent to desktop Use push technology – data sent to client without requesting it (such as e-mail)


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


Office Suites Popular software applications bundled together and sold as a single package

(suite) Used for home or office Most popular is Microsoft Office Others are Corel WordPerfect Office, Lotus SmartSuite, and Sun StarOffice



Microsoft Office 2003

Edition Applications Purpose Retail price

Standard Word

Excel

PowerPoint

Outlook

Word processing

Spreadsheets

Presentation graphics

E-mail, scheduling

$399

Small Business

Adds:

Publisher Desktop publishing

$449

Professional Adds:

Access Database management

$499

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

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

SUPPORT SOFTWAREThe Operating System

Operating system – complex program that controls operation of computer hardware and coordinates other software


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

Virtual Memory Concerned with management of main memory Makes it appear more memory available than actually is Used only on larger computers Permits multiprogramming to operate more efficiently



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

Sources of Operating Systems

Microcomputers: Windows XP; Windows Vista; Mac OS X Midrange systems: OS/400 Large systems: VM and MVS


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


Examples: UNIX and Linux


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


Enhanced operating system to allow for sharing disk drives and printers handling server side of client/server applications


Network operating systems (NOS) – software running on a server that manages network resources and controls the operation of a network


Major players include: UNIX and Linux Microsoft Windows NT, 2000 Server, 2003 Server Novell NetWare


Network operating systems (NOS) – software running on a server that manages network resources and controls the operation of a network

Procedural languages (3GL) Require logical thinking Entail development of a detailed step-by-step procedure Can be developed using structured programming

SUPPORT SOFTWAREThird Generation Languages

Advantages: Program logic easier to follow Maintenance and correction easier and faster Do not use GO TO logic


Structured programs – divided into modules, where each has one entry and one exit point


Table 3.1 Stages in the Program Development Process

Most popular procedural languages: BASIC C COBOL


Figure 3.9 BASIC Program

Figure 3.10 C Program

Figure 3.11 COBOL Program



Other procedural languages: FORTRAN PL/1 PASCAL ADA


Nonprocedural languages: Use very high-level instructions Require fewer instructions Easier to write, modify, understand

Example: FOCUS

SUPPORT SOFTWAREFourth Generation Languages

Figure 3.12 FOCUS Program and Output

Most popular: HTML: used to create Web pages XML: used to facilitate data interchange

among Web applications

SUPPORT SOFTWAREMarkup Languages

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 SOFTWAREObject-Oriented Programming

Figure 3.13A Visual Basic Program

Figure 3.13B Visual Basic Screen Layout

HTML XML Server-side programming languages:

Perl Java Servlets and Java Server Pages Microsoft Active Server Pages (ASP, ASP.NET) ColdFusion

SUPPORT SOFTWARELanguages for Developing Web Applications

Figure 3.17 Grocery Store HTML Form

Figure 3.17

HTML and ASP.NET codeto accompany Grocery Store HTML Form

Figure 3.18

Program to Process Data from Grocery Store HTML Form

Figure 3.19 Grocery Store Confirmation Web Page

Figure 3.19

Code to Generate Confirmation Web Page

DBMS – support software used to create, manage, and protect organizational data

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

Relational DBMS 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 SOFTWAREDatabase Management Systems

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 SOFTWAREFile Organization

Figure 3.20 File Organizations

SUPPORT SOFTWARE

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

File Organization

Figure 3.20 File Organizations

Figure 3.21 Relationship Schemes

Relational DBMSs use this scheme

Growth slower than anticipated Radically changed nature of systems analyst and

programmer jobs

SUPPORT SOFTWARECASE Tools

Computer-aided software engineering (CASE) – collection of software tools to help automate all phases of the software development life cycle

Large computers need to control workstations and terminals Example software: IBM’s CICS, TSO, and CMS

LANs and WANs Need to connect to the Internet Web browsers Telenet File Transfer Protocol (FTP)

SUPPORT SOFTWARECommunications Interface Software

More complexity of hardware/software arrangements Less concern with machine efficiency More purchased applications More programming using object-oriented and visual languages More emphasis on applications that run on intranets and the Internet More user development More use of personal productivity software

THE CHANGING NATURE OF SOFTWARE

More complexity of hardware/software arrangements Less concern with machine efficiency More purchased applications More programming using object-oriented and visual languages More emphasis on applications that run on intranets and the Internet

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THE SOFTWARE COMPONENT OF THE INFORMATION SYSTEMS INDUSTRY

Trends in Computer Software

User-written programsMachine languages

Packaged programsSymbolic languages

Operating systemsHigh-level languages

DBMS Fourth-generation languagesMicrocomputer packages

Natural & object- oriented languagesMultipurpose graphic-interface network-enabled expert-assisted packages

Trend: Toward Easy-to-Use Multipurpose Network-EnabledApplication Packages for Productivity and Collaboration

Trend: Toward Visual or Conversational Programming Languages and Tools

UAL was the first airline to offer a competitiveadvantage with its frequent flyer mileage

Customer self-service software on the Internet from FedEx was an example of first-mover advantages

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MANAGINGINFORMATIONTECHNOLOGY CHAPTER 3 C OMPUTER S OFTWARE