4.1 Main functions, structure and types of operating system
4.2 Windows os
4.3 Working with files and directories
Main functions, structure and types of operating system
An operating system is the most important software that runs on a computer. Every general-purpose computer must have an operating system to run other programs. It also allows you to communicate with the computer without knowing how to speak the computer's language. It manages the computer's memory, processes, and all of its software and hardware, i.e. manages all the other programs in a computer. The other programs are called applications or application programs. Most of the time, there are many different applications running at the same time, and they all need to access your computer's central processing unit (CPU), memory, and storage. The operating system coordinates all of this to make sure each program gets what it needs.
Layers and views of a computer system
The structure of OS consists of 4 layers:
Hardware (Hardware consists of CPU, Main memory, I/O Devices, etc. );
Software i.e. Operating System (Software includes process management routines, memory management routines, I/O control routines, file management routines);
System programs (This layer consists of compilers, Assemblers, linker etc.);
Application programs(This is dependent on users need).
Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers. In addition, users can interact directly with the operating system through a user interface such as a command language or a graphical user interface (GUI).
Classification of Operating systems
Multi-user: Allows two or more users to run programs at the same time. Some operating systems permit hundreds or even thousands of concurrent users.
Multiprocessing : Supports running a program on more than one CPU.
Multitasking : Allows more than one program to run concurrently.
Multithreading: Allows different parts of a single program to run concurrently.
Real time: Real-time operating systems are used to control machinery, scientific instruments and industrial systems. All tasks in that system must execute on time General-purpose operating systems, such as DOS and UNIX, are not real-time.
Operating systems usually come preloaded on any computer you buy. Most people use the operating system that comes with their computer, but it's possible to upgrade or even change operating systems. All modern operating systems use a graphical user interface, or GUI (pronounced gooey). A GUI lets you use your mouse to click icons, buttons, and menus, and everything is clearly displayed on the screen using a combination of graphics and text.
Each operating system's GUI has a different look and feel, so if you switch to a different operating system it may seem unfamiliar at first. However, modern operating systems are designed to be easy to use, and most of the basic principles are the same.
Windows OS. The three most common operating systems for personal computers are Microsoft Windows, Apple Mac OS X, and Linux.
Microsoft created the Windows operating system in the mid-1980s. Over the years, there have been many different versions of Windows, but the most recent ones are Windows 8 (released in 2012), Windows 7 (2009), and Windows Vista (2007). Windows comes preloaded on most new PCs, which helps to make it the most popular operating system in the world
When you first switch on your computer, it will automatically go to the Windows OS screen. This screen is known as the desktop. The desktop is the starting point of all activities in Windows.
This is what the Windows OS desktop looks like:
Shortcut icons
Taskbar
Start button
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Start button:
The Start button gives us access to all the applications on the computer. When you click on the Start button, the Start menu appears. You have various options to choose from.
Turn off computer:
This is used to shut down the computer. All applications should be closed and all work saved before the computer is shut down.
All Programs:
Opens a sub menu of all the programs installed on the computer.
Run:
The Run command is used to install applications on your hard disk drive.
Search:
Opens a window which you can use to quickly find documents.
Help and support:
This will bring up the HELP menu. You can also press the F1 key on your keyboard to launch the Help menu.
Printers and Faxes:
Shows installed printers and fax printers and helps you add new ones.
Control Panel:
Provides options for you to customize the appearance and functionality of your computer, add or remove programs, etc.
My Computer:
Gives access to, and information about the disk drives, scanners, cameras and other hardware connected to your computer.
My Music:
Opens the MY MUSIC folder where you can store music and other audio files.
My Pictures:
Opens the MY PICTURE folder where you can store digital photos, images and graphics files.
My Recent Documents:
This option displays a list of the most recently worked on documents. You can quickly view and open the document selected.
My Documents:
Opens the MY DOCUMENT folder where you store letters, reports, notes and other kinds of documents.
The Taskbar:
The taskbar can be found at the bottom of your screen. This bar shows all the applications that are open as well as the time.
Windows:
A window can be opened by double-clicking on the shortcut icon or by using the Start button.
This is the window for My Computer:
The Title Bar contains the name of the open
window and the minimize, maximize / restore
and the close buttons.
1 2 3 4
1 is the minimize button. This reduces the window to an icon button on the taskbar, but does not close it.
2 is the maximize button. This enlarges the window to the size of the entire screen / desktop.
3 is the restore button. This restores the window from its maximized / full screen state to original window size
4 is the close button. This will close the window completely.
Commands and shortcuts