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9. Parts of an operating system

As has been mentioned in earlier pages, the operating system can be broken down into four main parts, namely

• Kernel
• Device Drivers
• User Interface
• System Utilities

This section will explain a bit more about what each part does and how they differ between types of operating system

Kernel

This has the task of loading the applications into memory, making sure they do not interfere with one another and allowing them to share use of the CPU efficiently. The kernel also handles file storage to and from secondary storage devices such as hard disks and optical drives.

In other words the kernel handles:

• Loading / Unloading applications from memory
• Scheduling tasks to run on the CPU
• Memory management
• File management
• Data security

The single user, single application operating system does not have to deal with networking, unlike the network operating system, on the other hand, a device such as a mobile phone will have to have an extremely efficient memory management kernel as its memory is a very limited resource. So the Kernel of each type of operating system will have been designed with different duties in mind.

Device Drivers

Every piece of hardware that makes up the computer or connected to it, will have a device driver that allows the operating system to control and communicate with it. There could be hundreds of device drivers pre-installed with the operating system, and the right ones for that particular computer set-up is loaded on boot-up.

The exact detail of which device driver is needed by the operating system is kept in a file - in Windows, the file is called the 'registry' and in Linux the details will be stored as a number of 'configuration files'.

Makers of printers, graphics tablets, scanners, digital cameras and so on, will normally provide device drivers for each make of operating system. A device driver for Windows is different from the device driver for Linux.

This is why if you remove an operating system such as Windows from a hard disk, and install Linux instead, you will need to make sure you have all the correct device drivers available for each piece of hardware.

User interface

This part of the operating system is directing what you see on the screen (via the device driver) and reacting to your key presses and other inputs. The user interface could be a basic command line interface, as you might find on a server, or it might be a full blown Graphical User Interface (GUI) such as the Mac OS X, Windows or perhaps Gnome on Linux.

System Utilities

This part of the operating system provides all the basic facilities that run in the background without user interaction. For example,

• Print spool services
• Cryptographic password management.
• File management services