Operating System II – SS1 Data Processing Lesson Note (Second Term)

An operating system (OS) is a collection of programs that controls the application software users run and links the hardware to that software. It also manages shared resources such as memory, hard drives and the monitor. Its main functions are booting the computer, performing basic tasks, providing a user interface, handling system resources and managing files.

Behavioural objectives

By the end of the lesson, students should be able to:

• give examples of operating systems;
• list the basic functions of an operating system;
• distinguish between a cold boot and a warm boot;
• describe the two main types of user interface;
• name the two main types of file system and state the advantages of NTFS.

What is an operating system?

An operating system is a collection of programs that control the application software that users run and provide a link between the hardware and the software currently running on the computer. The operating system is also responsible for the management and control of all resources (memory, hard drives, monitor, etc.) that are shared among the different application programs that may be running at the same time.

Examples of operating systems

Examples of common personal computer operating systems are:

• Windows 7
• Windows Vista
• Windows Server 2003
• Linux
• Mac OS X
• SunOS

Short forms: OS, O/S. The kernel is the core part of the operating system.

Example: Google announced that it was developing a new operating system for users to run on their PCs.

What are the functions of an operating system?

The basic functions of an operating system are:

1. Booting the computer.
2. Performing basic computer tasks, for example managing peripheral devices such as the mouse and keyboard.
3. Providing a user interface, for example a command line or a graphical user interface (GUI).
4. Handling system resources, such as the computer’s memory and the sharing of central processing unit (CPU) time by various applications or peripheral devices.
5. Providing file management, which refers to the way that the operating system manipulates, stores, retrieves and saves data.

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.

Performing basic computer tasks

The 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.

Providing a user interface

A user interacts with software through the user interface. The two main types of user interfaces are a 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.

The operating system is responsible for providing a consistent application program interface (API). This is important because 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 storage is different on the two machines.

Handling system resources

The operating system handles system resources such as the computer’s memory and the sharing of 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 resources it needs to maximise the functionality of the overall system.

Providing file management

The operating system 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, copying 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 two main types of file systems are the File Allocation Table (FAT) and the New Technology File System (NTFS).

What are the types of file system?

Advantages of NTFS

One major advantage of NTFS is that it includes features to improve reliability. For example, NTFS includes fault tolerance, which automatically repairs hard drive errors without displaying error messages. It also keeps detailed transaction logs, which track hard drive errors. This can help prevent hard disk failures and makes it possible to recover files if the hard drive does fail.

NTFS also allows permissions (such as read, write and execute) to be set for individual directories and files.

Evaluation

1. List four examples of personal computer operating systems.
2. State the five basic functions of an operating system.
3. Explain the difference between a cold boot and a warm boot.
4. Name the two main types of user interface and give one example of each.
5. State two advantages of NTFS over FAT.

Assignment

1. Explain what plug and play means, using a printer as an example.
2. Describe the file management tasks an operating system allows a user to perform.