Operating System

An operating system (OS) can be considered to be a resource manager which manages all the resources of a computer, i.e., its hardware including CPU, RAM, Disk, Network and other input-output devices. 

It also controls various application software and device drivers, manages system security and handles access by different users.

Examples of OS:

• Apple macOS
• Microsoft Windows
• Google's Android OS
• Linux Operating System
• Apple iOS

The primary objectives of an operating system are two-fold:

• The first is to provide services for building and running application programs.
• The second objective of an operating system is to provide an interface to the user through which the user can interact with the computer.

OS User Interface 

There are different types of user interfaces each of which provides a different functionality. Some commonly used interfaces are:

1. Command Based Interface

• Command-based interface requires a user to enter the commands to perform different tasks like creating, opening, editing or deleting a file, etc.  
• The user has to remember the names of all such programs or specific commands which the operating system supports.
• Command based interface is often less interactive and usually allows a user to run a single program at a time.
• Examples of operating systems with command-based interfaces include MS-DOS and Unix.

2. Graphical User Interface

• Graphical User Interface (GUI) lets users run programs or give instructions to the computer in the form of icons, menus and other visual options.
• The input devices used to interact with the GUI commonly include the mouse and the keyboard. 
• Examples of operating systems with GUI interfaces include Microsoft Windows, Ubuntu, Fedora and Macintosh, among others.

3. Touch Based Interface

• Smartphones, tablets and PCs allow users to interact with the system simply using the touch input. 
• Using the touchscreen, a user provides inputs to the operating system, which are interpreted by the OS as commands like opening an app, closing an app, dialing a number, scrolling across apps, etc. 
• Examples of popular operating systems with touch based interfaces are Android and iOS. Windows 8.1 and 10 also support touch-based interfaces on touchscreen devices.

4. Voice Based Interface

• Users today can use voice-based commands to make a computer work in the desired way. 
• Some operating systems which provide voice-based control to users include iOS (Siri), Android (Google Now or “OK Google”), Microsoft Windows 10 (Cortana).

5. Gesture Based Interface

• Some smartphones based on Android and iOS as well as laptops let users interact with the devices using gestures like waving, tilting, eye motion and shaking. 

Functions of Operating System

1. Process Management

In an operating system, a task in execution is called a process. Process management concerns the management of multiple processes, allocation of required resources, and exchange of information among processes.

2. Memory Management

The main task of memory management is to give (allocate) and take (free) memory from running processes. Memory management concerns the management of main memory so that maximum memory is occupied or utilized by a large number of processes while keeping track of each and every location within the memory as free or occupied. 

3. File Management

File management involves the creation, updation, deletion and protection of these files in the secondary memory. 

File management system manages secondary memory, while memory management system handles the main memory of a computer system.  

4. Device Management

A computer system has many I/O devices and hardware connected to it. Device Management concerns the configuration of a particular device , so that it may be used by an end user or some other device, providing security measures and providing access control.