2 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 andapplication 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).
3 System SoftwareSystem 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.
4 Operating SystemOperating system is a set of programs that coordinates all the activities among computer hardware devices.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.Many of today’s computers use Microsoft Windows or Mac OS, Apple’s operating system.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.
5 Starting and Shutting down a computer Functions of Operating SystemPerforms basic computer tasks eg managing the various peripheral devices eg mouse, keyboardProvides a user interface, e.g. command line, graphical user interface (GUI)Starting and Shutting down a computerHandles system resources such as computer's memory and sharing of the central processing unit (CPU) time by various applications or peripheral devicesProvides file management which refers to the way that the operating system manipulates, stores, retrieves and saves data.
6 Important characteristics of Operating System MultitaskingMulti-userAn operating system that is capable of allowing multiple software processes to run at the same time.A multi-user operating system allows for multiple users to use the same computer at the same time and different timesSingle streamPrograms and data were submitted in groups or batchesMultithreadingAllows different parts of a single program to run concurrently.
7 E.g.: Fedora, Ubuntu, Redhat Major Operating Systemsfor Personal ComputersLinuxMacA Unix-like computer OS assembled under the model of free and open source software development and distributionE.g.: Fedora, Ubuntu, RedhatA series of graphical user interface-based OS developed by Apple Inc. for their Macintosh line of computer systems.E.g.: Mac OS XWindowsWindows XPWindows 98Windows 95Windows 2000Windows VistaWindows 7Windows 8UnixUnix is an operating system developed by Bell Labs to handle complex scientific applications using command line interface.
8 Functions of OS 1. Booting the computer The 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.
9 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.
10 Functions of OSThe 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.
11 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.
12 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).
13 Utility programUtility program allows a user to perform maintenance-type tasks usually related to managing a computer, its devices or its programs.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.Most OSs include several utility programs for managing disk drives, printers and other devices and media.User can also buy utility programs that allow user to perform additional computer management functions.
14 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.
15 Types of application software for modern usage: Word Processing SoftwareDatabaseSoftwareSpreadsheetSoftwarePresentationSoftwareDatabase is a structured collection of data. Database software allows the users to store and retrieve data from databases.E.g.: ORACLE, Microsoft AccessSpreadsheet software allows users to perform calculations. They simulate paper worksheets by displaying multiple cells that make up a grid.E.g.: Microsoft ExcelA softwarethat is used to display information in the form of a slide show.E.g.: Microsoft PowerPointThis software enables the users to create and edit documents.E.g.: MS-Word, WordPad, NotepadMultimedia SoftwareEducationalSoftwareContentAccess SoftwareSimulationSoftwareA software that allow users to create and play audio and video media.E.g.: Real Player, Media PlayerUsed 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, GamesSoftware for simulation of physical or abstract systems for either research, training or entertainment purposes.E.g.: flight simulators and scientific simulator