Operating Systems

Operating systems are fundamental for computers. Its purpose is to:

• Allow the user to use the computer effectively,
• Manage memory,
• Control and monitor applications,
• Allow user interaction.

The four key parts of an operating system are the:

• Kernel,
• Device Drivers,
• User Interface,
• System Utilities.

The kernel controls the low-level tasks of a computer system. It has may purposes such as:

• Loading data and applications to and from memory,
• Preventing applications from interfering with each other,
• Control CPU time allowing it to be shared efficiently,
• Handle file management to and from secondary storage,
• Secure data,
• Schedule CPU tasks.

Hardware cannot directly communicate with the CPU, to allow them to communicate a piece of software called a driver is needed. It enables the hardware to connect with the operating system.

Usually, they come pre-installed and allow all hardware to communicate including input and output devices. Every piece of hardware needs a specific driver to allow it to work correctly. They can also be installed from discs. For example, GPUs often require discs otherwise the user would not be able to see anything on screen.

On Windows, they are stored in the registry whereas on Linux they are stored in configuration files.

It is important to keep drivers up to date because:

• They enhance features.
• Improve interaction with the user and the computer.
• Optimisations.
• Stability boost.

This part of the operating system is the bit which is visible to the user. It could be a command line (like on many Linux implementations) or a graphical interface (like on Windows).

The type of interface is based on the type of users who will use the operating system. More advanced users likely use Linux because of the advanced command line whereas a regular user would use something more user-friendly such as Windows.

There are other types of interface as well such as:

• Command Line Interface (CLI)
• Graphical User Interface (GUI)
• Menu Based (Tourism)
• Form Based (Feedback)
• Natural Language (For Disabled People)

User interface should be responsive to the user's input and display data when necessary.

The operating system is expected to carry out certain tasks for the user. Usually, the system utilities are designed to support the computer's infrastructure and maintain the computer. For example, it is expected to do things such as:

• Printing,
• Firewalls,
• Password Management,
• File Management (compression, defragmentation etc.)
• Basic Anti-virus.

The six key roles of the operating system are:

• File Management - Creating an effective directory system to allow data storage. It should be robust and reliable for fetching data from an external secondary storage device.
• Resource Management - Controls the amount of RAM available and handles virtual memory if needed. The caches and bandwidth of the CPU are also controlled by the operating system. Balance and efficiency is important.
• User Interface - Suitable interface for interaction with the system.
• I/O Controller - Controls the user's input and the data which is displayed or outputted over the hardware.
• Task Management - Prioritises applications and processes in order to improve CPU efficiency. Handles interrupt requests from hardware.
• Security - Usually basic security (like Windows Defender) which protects against common viruses and vulnerabilities. Quite essential for internet access.

Acronym: FRUITS

There are 7 main types of operating system. They are intended for specific purposes:

• Batch Processing - Used for things such as payrolls.
• Real Time Processing - Found in computer games, cars and traffic lights.
• Single User - Only one person at a time.
• Multi-Tasking - Completing multiple tasks in parallel.
• Multiple User - Supermarket tills.
• Network Distributed - Used in schools.
• Embedded - Found in phones and satnavs.

These types of operating systems are designed to complete repeated tasks with little to no variation from the original purpose. The only thing which usually changes is the input and output. The actual program does not change when run on a batch operating system.

For example, payroll systems can use these because only the amount of money each person is paid needs to change - not the whole software.

They require little to no human intervention after they have been initially setup.

These are used when a system needs to be controlled by a computer. They react to input and change their output to reflect this.

For example, they are found in cars which control the engine based on the position of the pedals. This needs to be done quickly by the car.

However, they do not always need to be fast. They are also used in traffic lights which can take a few seconds to react to input.

This type of operating system is found in supercomputers or mainframes. They must be able to:

• Allocate resources for each user.
• Log the amount of resources used.
• Maintain a secure environment for each user.
• Efficiently calculate the best way to execute all tasks scheduled by users.

Instead of single, simple processes being run, more complex ones are run and loaded into memory allowing them to be shared by multiple users in a secure way. Many users can use the same resource. For example, compilers can be used by multiple users as only one process needs to be loaded and each user can use a separate, secure thread for their task.

This type of operating system is much more complex and demanding because of the need to balance resources between multiple simultaneous users.

Computers which need to connect to a network and handle connections use network operating systems. This type of operating system needs to be able to:

• Monitor and observe user activity.
• Provide user accounts with adequate security.
• Use a complex file management system to allow users to access their files anywhere on the network.
• Store login details and files externally on a central server.
• Allow users to have individual settings which are loaded on to the computer they are using.

These are commonly used in schools to allow students and teachers to access their files from anywhere on the school network.