(i) BOSS
(ii) Unix
(iii) Ms-DOS

The function of Operating system includes file management, memory management, process management and device management.

The different types of operating system used in the computer
(i) Single User and Single Task Operating System
(ii) Multi User Operating System
(iii) Multi Processing Operating System
(iv) Distributed Operating System
(v) Prominent Operating System

This is a one of the features of Operating System. It has two or more processors for a single running process (job).

Multi-user Operating Systems:
(i) It is used in computers and laptops that allow same data and applications to be accessed by multiple users at the same time.
(ii) The users can also communicate, with each other. Windows, Linux and UNIX are examples for multi-user Operating System.

The functions of OS
(i) Process Management
(ii) Device Management
(ill) Memory Management
(iv) File Management
(v) Security Management
(vi) Storage Management

(i) Single user operating system
(ii) Multi-user Operating system
(iii) Distributed Operating system
(iv) Operating system
(v) Mobile Operating system.

(i) Easy interaction between the human and computer.
(ii) Starting computer operation automatically when power in turned on (Booting).
(iii) Controlling input & output devices.
(iv) Managing the utilization of main memory.
(v) Providing security to user program.

(i) Multiprocessing is the use of two or more CPUs within a single computer system.
(ii) A system is said to be multiprocessing if it has more than one physical processors. Since it has multiple processors available, multiple processes can be executed at a time.
(iii) In Multiprocessing, processes can be assigned to a different processor for its execution.
(iv) With the help of multiprocessing system more work can be done in a shorter period of time.
(v) Multiprocessing system provides increased reliability means that if one processor fails, the other processor will continue its working. For example, if there are10 processors and 1 fails then the work does not halt, instead the remaining 9 processor will share the work of 10 th processor.
(vi) Multiprocessing system increases the Throughput i.e. if we increase the number of processors, more work can be completed.
(vii) As multiprocessing occurs by parallel processing, it is cost saving since it parallelly shares memory, buses, peripherals, etc.
(viii) Multiprocessor refers to hardware (CPU units) rather than software (running programs).

User interface:
(i) It is one of the important features of an Operating system.
(ii) User interface allows user to interact with computer effectively.
(iii) An interactive Operating system provides astonishing feature of Graphical User Interface.
(iv) GUI is one of the advanced features that have made Windows and other interactive Operating system highly popular.
(v) Some properties of GUI are display of icons, movement of cursor, etc.
Memory Management:
(i) Operating system performs the function of memory management. Memory Management is the process of controlling and coordinating with computers main memory.
(ii) The Operating system keeps a track of main memory/primary memory i.e. which portion of memory is currently being used and who is using them.
(iii) Memory Management involves allocation and de-allocation of memory blocks.
File Management:
(i) File Management is an important function of Operating System that maintains and manages file operation.
(ii) File Management manages files, folder and directory system on computer.
(iii) The process of File Management includes creating, modifying and deleting of files.
(iv) File Management of Operating system helps to create new files and place them at specific location and makes the process of sharing of files easy.
Process Management:
(i) Process Management includes creation and deletion of processes.
(ii) Process Management provides mechanism for communication and synchronization of processes.
I/O Management:
(i) The Operating system is responsible for all sorts of input from keyboard, mouse, desktop, etc.
(ii) Operating system effectively handle I/O operation to hide the peculiar behavior from the end-user.
Security Management:
(i) Operating system provides security by protecting unauthorize access to computer and uses password and other similar technique to protect user data

(i) Android is a mobile operating system developed by Google, based on the Linux and designed primarily for touchscreen mobile devices such as smartphones and tablets.
(ii) Google has further developed Android TV for televisions, Android Auto for cars and Android Wear for wrist watches, each with a specialized user interface.
(iii) Variants of Android are also used on game consoles, digital cameras, PCs and other electronic gadgets.

UNIX:
UNIX is a family of multitasking, multi-user operating systems that derive originally from AT&T Bell Labs, where the development began in the 1970s by Ken Thompson and Dennis Ritchie.
Linux:
(i) Linux is a family of open-source operating systems. It can be modified and distributed by anyone around the world.
(ii) This is different from proprietary software like Windows, which can only be modified by the company that owns it.
(iii) The main advantage of Linux operating system is that it is open source. There are many versions and their updates
(iv) Most of the servers run on Linux because it is easy to customize.

(i) File management is an important function of OS which handles the data storage techniques. The operating System manages the files, folders and directory systems on a computer.
(ii) Any type of data in a computer is stored in the form of files and directories/folders through File Allocation Table (FAT).
(iii) The FAT stores general information about files like filename, type (text or binary), size, starting address and access mode (sequential/indexed/indexed-sequential/direct/relative).
(iv) The file manager of the operating system helps to create, edit, copy, allocate memory to the files and also. updates the FAT.
(v) The OS also takes care of the files that are opened with proper access rights to read or edit them. There are few other file management techniques available like Next Generation File System (NTFS) and ext2 (Linux).

(i) The user interface determines how command are given to the computer and how data is displayed on the screen.
(ii) User interface allows user to interact with computer effectively.
(iii) User interface is the first impression of a software where the user interacts with computer.
(iv) The user interface is mostly of two types:
1. Command line interface
2. Graphical user interface
(v) Command line interface: It indicates user must know machine language and program language.
(vi) Graphical user interface: In this user gives command by clicking or selecting the icons displayed on the screen.
The following points should be noted while creating a user interface for an Operating system:
(i) The user interface should satisfy the customers based on their needs.
(ii) The user interface should reduce number of errors committed by the user.
(iii) The user interface should save user time.
(iv) The user interface should make simple, common task easy.
(v) The user interface should be flexible and tolerant.

The Distributed Operating System is used to access shared data and files that reside in any machine around the world. The user can handle the data from different locations. The users can access as if it is available on their own computer.
The advantages of distributed Operating System are as follows:
(i) A user at one location can make use of all the resources available at another location over the network.
(ii) Many computer resources can be added easily in the network
(iii) Improves the interaction with the customers and clients.
(iv) Reduces the load on the host computer.