3 1. OPERATING SYSTEMSThe operating system or`OS is the foundation software of a computer, that which schedules tasks, allocates storage, and presents a default interface to the user between applications.
4 Some Functions of an Operating System: Boot-up the computer.Control the hard drives. (This includes such features as formatting and defragmenting disks as well as saving files to and retrieving files from disk).Control input devices such as keyboards, mice and scanners.Control output devices such as the video display and printer.Control the external ports.(Ports are the external connections that enable peripheral devices to be connected to a computer. The important types of ports are USB ports).6. Provide the functionality for computers to be linked in a network.7. Provide the foundation for application software to be launched.8. Enable application software to access and use the hardware.
5 How the Operating System work? User / ProgrammerOperating SystemHuman Understandable Language (High Level Language)Machine Language (Low Level Language)Computer Machine
6 Operating systems can be classified as follows: Multi-userA multi-user operating system allows for multiple users to use the same computer at the same time and different times, examples :Linux, Unix , and Windows 2000 (Server)2. Single-user, single task This operating system is designed to manage the handheld computers so that one user can effectively do one thing at a time, example:The Palm OS for Palm handheld computers .
7 Operating systems ( Cont….) 3. Single-user, multi-tasking Most people uses this operating system on their desktop and laptop computers today, Microsoft's Windows , Apple's Mac OS 4. Real-time operating system (RTOS) Is a computer operating system designed to handle events as they occur. It commonly found and used in robotics, cameras, and Medical devices (medical imaging, nuclear medicine, medical diagnostics and several medical applications).
8 Popular Desktop Operating System: WindowsMacLinux
9 Popular Medical Operating Systems: 1. LynxOS:Nuclear Medicine Imaging SystemGENIE Acquisition system
12 Microsoft Disk operating system, MS-DOS Old Operating SystemMicrosoft Disk operating system, MS-DOS
13 Graphical user interface Graphical user interface (GUI), is a type of user interface that allows users to interact with electronic devices through graphical icons.The most widely used type of graphical user interfaces are WIMP systems. WIMP stands for Windows Icons Menu Pointer. Options are represented by small pictures or 'icons' arranged inside rectangular boxes called windows.
14 GUI basic components:Pointer : A symbol that appears on the display screen and that you move to select objects and commands. Usually, the pointer appears as a small angled arrow.Pointing device : A device, such as a mouse, that enables you to select objects on the display screen.Icons : Small pictures that represent commands, files, or windows. By moving the pointer to the icon and pressing a mouse button, you can execute a command or convert the icon into a window.
15 GUI basic components (Cont…) Desktop : The area on the screen that displays the icons, gadgets, and taskbar. Is often referred to as the desktop because the icons are intended to represent real objects on a real desktop.Windows: You can divide the screen into different areas. In each window, you can run a different program or display a different file. You can move windows around the display screen, and change their shape and size at will.Menus : Most graphical user interfaces let you execute commands by selecting a choice from a menu.
17 Advantages and Disadvantages of GUI’s: This type of interface is easy to use, especially for a beginner.Easy to explore and find your way around the system using a WIMP/GUI interface.Let you exchange data between different software application.Disadvantage:Require a lot of memory (RAM) to run.Take up a much amount of hard disc space.They use more processing power.
18 2. LanguagesLanguage software present a simplified means to execute a series of instructions. It consists of a vocabulary and an accompanying set of rules that tell the computer how to work.Languages permit the user to develop programs to perform specific tasks.Popular languages include:- C++.- COBOL (Common Business Oriented Language).- Java.- Visual Basic.
19 Language Generations1- Machine languages are the lowest level and consist of numbers only.2- Assembly languages are the next generation of languages, that give the programmer the ability to use names instead of numbers when telling the computer what to do.3- High level languages enables programmers to develop software applications using ordinary words and symbols rather than binary numbers.It refers to a computer programming language such as BASIC, PASCAL, or C++.
20 3. Applications Software Applications software (Also known as 'apps') are designed to allow the user of the system complete a specific task or set of tasks.Programmers used language software to write application programs.Major types of applications or programs include the following:1) General – purpose software such as:Word processor, Spreadsheet, Databases managers, presentation Graphics, communications programs, statistics software and Web page authoring programs.2) Educational programs such as:Training software, Simulations or computer – assisted learning (Internet).
21 3) Utility programs are a group of software programs that help with the management or maintenance of the computer and protection of the computer from the unwanted intrusion such as:Virus scanners, personal firewalls, screen servers and hard disk managers.4) Personal programs help people manage theirpersonal lives such as:Calculators and calendars.5) Entertainment programsThe class of software programs that the industryhas designed for fun such as:Games and simulations.
22 Computer FilesA file is an object on a computer that stores data, information, settings, or commands that are used with a computer program.In a graphical user interface (GUI) such as Microsoft Windows, files are shown as unique icons that relate to the program that opens the file.For example, in the picture to the right, is an example of the icon associated with Adobe Acrobat PDF files. Double-clicking this icon in Windows would open that file in Adobe Acrobat or the PDF reader installed on the computer
23 File extensionA file extension is the ending of a file that helps identify the type of file in operating systems, such as Microsoft Windows.For example, the filename "myfile.txt" has an extension of ".txt", which is a file extension associated with text files.Examples:File TypeFile extensionText Files.doc Microsoft Word Document.Data Files:.ppt PowerPoint PresentationAudio Files:.mp3 MP3 Audio File.