SOFTWARE

• Software also called a program, consists of a series of instructions that tells the computer what tasks to perform and how to perform them.

• User interact with a program through its user interface.

• User interface controls how user enter data and instructions and how information is displayed on the screen.

• Software today often has a graphical user interface (GUI).

What is SOFTWARE?

• With GUI, users interact with the software using text, graphics and visual images such as icons.

• An icon is a miniature image that represents a program, an instruction or some other object.

• Users can use the mouse to select icons that perform operations such as starting a program.

• Two categories of software are system software and application software.

System Software

System software consists of the programs that control or maintain the operations of the computer and its devices.

System software serves as the interface between the user, the application software and the computer’s hardware.

Two types of system software are the operating system and utility programs.

Allows the parts of a computer to work together and also

provides a platform to run high-level system

software and application software. OS provides a means for users to

communicate with the computer and other software.

When a user starts a computer, portion of the OS are copied into memory from the computer’s hard disk. These parts of the OS remain in memory while the computer is on.

Operating system is a set of programs that coordinates all

the activities among computer hardware devices.

Many of today’s computers use Microsoft Windows or Mac OS, Apple’s operating system.

Operating

System

Starting and Shutting down a

computer

Performs basic

computer tasks eg

managing the

various peripheral

devices eg mouse,

keyboard

Provides a user interface, e.g. command line, graphical user interface (GUI)

Handles system resources such as

computer's memory and sharing of the central processing unit (CPU) time by

various applications or peripheral

devices

Provides file management which refers to the way that the operating system manipulates, stores, retrieves and saves data.

Functions of Operating System

Programs and data were

submitted in groups or batches

Single stream

A multi-user

operating system

allows for multiple

users to use

the same computer

at the same time and

different times

Multi-user

Allows different parts of a single program to run concurrently.

An operating system that is

capable of allowing multiplesoftware

processes to run at the same

time.

Multitasking

Multithreading

Important characteristics of Operating System

Windows XPWindows 98Windows 95

Windows 2000Windows XP

Windows VistaWindows 7Windows 8

Windows

A Unix-like computer OS assembled under the model

of free and open source software development and

distributionE.g.: Fedora, Ubuntu,

Redhat

Linux

Unix is an operating

system developed by

Bell Labs to handle

complex scientific

applications using

command line interface.

A series of graphical user interface-based OS

developed by Apple Inc. for their Macintosh line of computer systems.E.g.: Mac OS X

Mac

Unix

Major Operating Systems for Personal Computers

Functions of OS1. Booting the computerThe process of starting or restarting the computer is known as booting. A cold boot is when you turn on a computer that has been turned off completely. A warm boot is the process of using the operating system to restart the computer.

2. Performs basic computer tasksThe operating system performs basic computer tasks, such as managing the various peripheral devices such as the mouse, keyboard and printers. For example, most operating systems now are plug and play which means a device such as a printer will automatically be detected and configured without any user intervention.

Functions of OS

3. Provides a user interface

A user interacts with software through the user interface. The two main types of user interfaces are: command line and a graphical user interface (GUI).

With a command line interface, the user interacts with the operating system by typing commands to perform specific tasks. An example of a command line interface is DOS (disk operating system).

With a graphical user interface, the user interacts with the operating system by using a mouse to access windows, icons, and menus. An example of a graphical user interface is Windows Vista or Windows 7.

Functions of OS

The operating system is responsible for providing a consistent application program interface (API) which is important as it allows a software developer to write an application on one computer and know that it will run on another computer of the same type even if the amount of memory or amount of storage is different on the two machines.

Functions of OS

4. Handles system resources

The operating system also handles system resources such as the computer's memory and sharing of the central processing unit (CPU) time by various applications or peripheral devices. Programs and input methods are constantly competing for the attention of the CPU and demand memory, storage and input/output bandwidth. The operating system ensures that each application gets the necessary resources it needs in order to maximise the functionality of the overall system.

Functions of OS

5. Provides file management

The operating system also handles the organisation and tracking of files and directories (folders) saved or retrieved from a computer disk. The file management system allows the user to perform such tasks as creating files and directories, renaming files, coping and moving files, and deleting files. The operating system keeps track of where files are located on the hard drive through the type of file system. The type two main types of file system are File Allocation table (FAT) or New Technology File system (NTFS).

Allows the parts of a computer to work together and also

provides a platform to run high-level system

software and application software. For example, a user can use a utility

program to transfer digital photos to an optical disk.

User can also buy utility programs that allow user to perform additional computer management functions.

Utility program allows a user to perform maintenance-type

tasks usually related to managing a computer, its devices or

its programs.

Most OSs include several utility programs for managing disk drives, printers and other devices and media.

Utility

program

Application SoftwareApplication software consists of programs designed to make users more productive and to assist them with personal tasks.

Widely used type of application software related to communications is a Web browser.

Other application software includes word processing software, spreadsheet software, database software and presentation software.

Other types of software that enables users to perform a variety of tasks: personal information management (PIM), accounting, note taking, photo editing, desktop publishing, Web page authoring, education, audio and video editing, entertainment (games, simulations, etc.), multimedia authoring and etc.

Word Processing Software

This software enables the users to create and edit

documents. E.g.: MS-Word,

WordPad, Notepad

SpreadsheetSoftware

PresentationSoftware

Spreadsheet software allows users to perform

calculations. They simulate paperworksheets by

displaying multiple cells that make up a

grid.E.g.: Microsoft Excel

A softwarethat is used to

display information in the form of a slide

show.

E.g.: Microsoft PowerPoint

A software that allow users to create and play audio and

video media.E.g.: Real Player,

Media Player

Multimedia Software

Database is a structured collection

of data. Database software allows the users to store and retrieve data from

databases. E.g.: ORACLE,

Microsoft Access

DatabaseSoftware

EducationalSoftware

SimulationSoftware

Content Access Software

Used in teaching and self-learning.

It has the capabilities of

running tests and tracking progress.

A software used primarily to access

content without editing.

E.g.: Media Players, Web Browsers, Help

browsers, Games

Software for simulation of physical or abstract

systems for either research, training or

entertainment purposes.E.g.: flight simulators and

scientific simulator

Types of application software for modern usage: