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:
Why is the operating system so important to the use of all types of computer?
What are the functions of the operating system?
How do knowledge workers obtain and use application software?
Describe the purpose and tools used in the software development process.
Review of Software
Software includes all of the instructions given to the computer’s hardware
There are two major categories of software:
operating systems software
All software has to be created by human programmers using a variety of computer languages which the computer can implement.
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
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.
MyPaper.doc; Budget.xls; My contacts.mdb
Parts of an OS
The functions of the operating system are:
Starting the computer
Providing services to application software
Controlling access to computer
Providing an interface for the user
Ensuring efficient use of the CPU
Starting the Computer
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.
JCL for Mainframe
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
Hierarchical File Structure
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
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 - 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.
Spreadsheet software accomplishes other tasks to help knowledge workers.
These including sorting data and creating charts to better understand data.
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 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.
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).
Open Source Software
Open source - software for which the programming code is freely available to any one who wishes to download it over the Internet. The only requirement is that any change a programmer makes to the open source code must also be made freely available to other persons.
Examples: Apache Web server software, the Linux operating system, mySQL database software.
Proprietary software - any software that requires a license that must purchased by a company and the source code is not available to anyone outside of the company.
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