Information Systems: Creating Business Value

by Mark Huber, Craig Piercy, and Patrick McKeown

Field Guide B: Details of IT Software

What We Will Cover:

Overview of the Operating System

What the Operating System Does

Overview of Application Software

Developing Customized Software

Student ROI (Return on Investment)

Your investment of time and effort in this course will result in your being able to answer these questions:

1. Why is the operating system so important to the use of all types of computer?

2. What are the functions of the operating system?

3. How do knowledge workers obtain and use application software?

4. Describe the purpose and tools used in the software development process.

Review of Software

Recall: Software includes all of the instructions given

to the computer’s hardware There are two major categories of software:

operating systems software application software.

All software has to be created by human programmers using a variety of computer languages which the computer can implement.

Operating System

Operating system software manages the many tasks going on concurrently within a computer.

The operating system: manages all of the message traffic that flows from the user to

the application software to the computer handles the allocation of resources and the assignment of tasks

to various software programs enables the user to carry out needed tasks with application

software without worrying about the hardware interfaces.

What does an OS do?

The operating system is a collection of software programs that manages the tasks performed concurrently in the computer.

The operating system must monitor input devices; manage output; control the operation of secondary storage and main memory; control the execution of application programs.

On mainframes and other servers, the operating system is responsible for additional tasks.

A server must respond to requests from multiple clients ensuring that the desired data, information, or file is sent to the client.

For local area networks (LANs), there must be a network operating system to control access to the files on the network.

Comparison of Operating Systems

Feature Mainframe Network Personal Computer

Handheld Device

Number of Simultaneous Users

Multiple Multiple One One

Security Sophisticated Sophisticated Minimal/user-enabled

Minimal/user-enabled

Peripherals Complex Numerous Few Few

Number of tasks

Many Many Many Few

Support Systems programmers

Networked-certified personnel

User Provider

Example OS390 Novell NOS Windows XP Windows Mobile

Using Files

Operating systems manage the storage and use of programs, data, and information on secondary storage

Files are programs, data, or information to which the user or software assigns a name.

Filenames: name.extension MyPaper.doc; Budget.xls; My contacts.mdb

OS Responsibilities

The functions of the operating system are:

1. Starting the computer

2. Providing services to application software

3. Managing hardware

4. Controlling access to computer

5. Providing an interface for the user

6. Ensuring efficient use of the CPU

Managing Hardware

The operating system acts as a go-between for the user, software and the hardware system.Hardware management includes:

Input: operations like accepting data from keyboard and instructions from a mouse

Output: sending information to the monitor screen and to a printer

Transfer of data, instructions, and information between the CPU chip and internal memory and secondary storage

Mainframes: hardware of multiple users Network OS: controls the communications between

devices on the network.

Controlling Access

A mainframe or network operating system must provide security to everyone's data, information, and programs against unwarranted intrusion.

Access controls exist that require the user to enter a password to use a PC.

Providing an Interface

The OS provides an interface to interpret the commands from the user and send them to the CPU.

Command driven – requires the use of text commands at a prompt. Mainframe and server OS like Unix may still require command driven interface.

Graphical User Interface (GUI) – uses graphic elements on a screen and a pointing device to allow the user to interact with the computer.

Result of DOS DIR/W Command

Efficient Use of CPU

A key task of the operating system is to insure that the slow I/O does not hold up the CPU.

One way to keep the I/O from interfering with processing is to perform run programs concurrently, that is--the CPU processes part of one program, then part of another, and so on.

Multitasking - handles multiple programs or tasks at the same time. The jobs are placed in a queue (waiting line) to be executed according to their level of priority.

PC network OS usually shift the processing burden from the central file server to local PCs.

Example of Multitasking

Providing Services to Application Software

Operating systems provide a number of services to application software including:

Running the application software and ensuring that needed resources are available

Determining the order in which concurrent programs will be processed

File/disk management Memory management.

Hierarchical File Structure

Application Software

Application software – Software designed to help us accomplish work and tasks on the computer.

Application software for business comes in two primary forms:

Commercially developed software: is ready to install and use without further modification on the part of the user.

Custom developed software: software which is developed by a company specifically for its own use.

Popular types of Commercially developed software

Word Processing Spreadsheets Database Presentation Web Browser and Internet

Word Processing Software

Word Processing - software that is used to compose, edit, save, and print various types of documents.

Desktop publishing can be used to combine word processing, graphics, and special page definition software to create professional documents.

Spreadsheet Software

Spreadsheet - an electronic table of rows and columns with the intersection of a row and a column being termed a cell.

Cells are denoted by the column letter and row number.

Spreadsheets are widely used by knowledge workers to carry out analyses.

What-If Analyses

Spreadsheet software accomplishes other tasks to help knowledge workers.

These including sorting data and creating charts to better understand data.

Database Software Database software –

software that provides tools for organizing data into a form that allows for efficient search and retrieval.

Data related to a specific question of concern can be accessed using a database query.

Presentation Software

Presentation software is aimed at creating presentations using text in many sizes and fonts, graphics, photos, and even audio and video files that can be used to inform an audience.

Widely used for professional quality presentations.

Web Browser and Internet Software

Web browser – software that is used to access the billions of pages of information available on the World Wide Web.

Browsers have become the “jack of all trades” for Internet operations by enabling: search for Web pages; communicate using e-mail, instant messaging, and chat rooms; and to download files.

Specialized Software

Software has been developed to handle specific situations be they financial, mathematical, engineering, or any number of other areas.

Developing Customized Software

Companies usually buy commercially developed software, like word processing programs or spreadsheets, for routine business tasks.

However, to achieve a competitive advantage, a company must often custom-develop software to meet its particular needs.

Computer programs are based on algorithms, where an algorithm is a detailed sequence of actions that, when followed, will accomplish some task.

The process of creating a computer program is called programming, which uses one of a variety of computer languages to communicate with the computer.

Commonly Used Languages

Language Common Use

C (including C++ and C#)

Writing a wide variety of applications for PCs or network servers.

Java Writing software for all types of computers; also, for writing browser and server-side Web software.

PHP Writing Web-based applications.

SQL(Structured Query Language)

Writing queries to relational database management systems.

VB.NET (Visual Basic .NET)

Writing software for PCs; also, for writing browser and server-side Web software (Microsoft’s competition of Java).