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.

• Short forms: OS and O/S.
• Kernel: the core part of the operating system.
• Shared resources managed: memory, hard drives and the monitor.

Behavioural objectives

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

1. give examples of operating systems;
2. list the five basic functions of an operating system;
3. distinguish between a cold boot and a warm boot;
4. describe the two main types of user interface;
5. 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 controls application software and links the hardware to the software running on the computer.

• Control of software: it manages the application programs that users run.
• Link to hardware: it connects the software to the physical parts of the computer.
• Resource management: it controls memory, hard drives and the monitor, which are shared by programs running at the same time.

What are examples of operating systems?

Common personal computer operating systems include Windows, Linux and Mac OS X.

• Windows 7: a Microsoft operating system with a graphical interface.
• Windows Vista: an earlier Microsoft operating system with a graphical interface.
• Windows Server 2003: a Microsoft operating system for servers.
• Linux: an operating system used on many computers and servers.
• Mac OS X: the operating system of Apple Mac computers.
• SunOS: an operating system from Sun Microsystems.
• Chrome OS: an operating system developed by Google for PCs.

What are the functions of an operating system?

An operating system has five basic functions: booting, performing basic tasks, providing a user interface, handling system resources and managing files.

1. Booting the computer: starting or restarting the computer.
2. Performing basic computer tasks: managing devices such as the mouse and keyboard.
3. Providing a user interface: a command line or a graphical user interface (GUI).
4. Handling system resources: sharing memory and central processing unit (CPU) time among applications and devices.
5. Providing file management: manipulating, storing, retrieving and saving data.

What is booting?

Booting is the process of starting or restarting the computer.

• Cold boot: turning on a computer that has been switched off completely.
• Warm boot: using the operating system to restart a computer that is already on.

How does the operating system perform basic computer tasks?

The operating system manages peripheral devices such as the mouse, keyboard and printers.

• Plug and play: the computer detects and configures a new device automatically, without user intervention.
• Example: a printer is connected and the operating system sets it up by itself.

What is a user interface?

A user interface is the means by which a user interacts with software.

There are two main types of user interface: the command line interface and the graphical user interface (GUI).

• Command line interface: the user types commands to perform specific tasks, as in DOS (disk operating system).
• Graphical user interface: the user uses a mouse to access windows, icons and menus, as in Windows Vista or Windows 7.

What is an application program interface (API)?

• Meaning: a consistent interface provided by the operating system for software developers.
• Use: a developer can write an application on one computer and know it will run on another computer of the same type.
• Benefit: it works even if the memory or storage differs between the two machines.

How does the operating system handle system resources?

The operating system shares memory, CPU time and other resources among the programs and devices that need them.

• Competition: programs and input methods constantly compete for the attention of the CPU.
• Demands: they also need memory, storage and input/output bandwidth.
• Role of the OS: it makes sure each application gets the resources it needs, so the whole system works as well as possible.

What is file management?

File management is the way the operating system organises and tracks files and directories (folders) saved on or retrieved from a disk.

• Create: make new files and directories.
• Rename: change the name of a file.
• Copy and move: duplicate files or place them in another location.
• Delete: remove files.

The operating system tracks where files are on the hard drive through the type of file system.

What are the types of file system?

There are two main types of file system: the File Allocation Table (FAT) and the New Technology File System (NTFS).

What are the advantages of NTFS?

NTFS is more reliable than FAT32 and lets users control access to files.

• Fault tolerance: it automatically repairs hard drive errors without displaying error messages.
• Transaction logs: it keeps detailed records that track hard drive errors.
• Prevention of failure: the logs help prevent hard disk failures.
• File recovery: the logs make it possible to recover files if the drive does fail.
• Permissions: read, write and execute permissions can 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

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