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and display of required updated information is termed as the response time. Real-time operating systems are used
when there are rigid time requirements on the operation of a processor or the flow of data. A real-time operating
system must have well-defined, fixed time constraints, otherwise the system will fail. Major applications of real-time
operating system are in weather forecasting systems, scientific experiments, medical imaging systems, industrial
control systems, weapon systems, robotics, air traffic control systems, etc.

A real-time operating system can be a Soft real-time operating
system which usually meets the specified response deadline, or a
Hard real-time operating system which always meets the specified
response deadline.

Distributed Operating System

Distributed operating systems is a recent advancement in the world of computer
technology and are being widely accepted all over the world. Distributed operating
systems use multiple central processors to serve multiple real-time applications
and multiple users. Data processing jobs are distributed among the processors
accordingly. The processors communicate with one another through various
communication lines (such as high-speed buses or telephone lines). Processors in
a distributed operating system may vary in size and function. These processors
are referred to as sites, nodes, computers, and so on.
Independent systems possess their own memory unit and CPU. These are referred as loosely coupled systems
or distributed systems. These systems’ processors differ in size and function. The major benefit of working with
these types of operating systems is that it is always possible that one user can access the files or software which
are not actually present on his system, but on some other system connected within this network, i.e., remote
access is enabled within the devices connected in that network. Examples of distributed operating systems are
DYNIX, Solaris and Mach.

Network Operating System
A Network operating system (NOS) runs on a server and provides the capability to manage data, users, groups,
security, applications, and other networking functions. These operating systems allow shared access of files,
printers, security, applications, and other networking functions over a small private network. One more important
aspect of Network operating system is that all the users are well aware of the underlying configuration of all
other users within the network, their individual connections, etc. Thus, these computers are known as tightly
coupled systems. Examples of NOS are Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX,
and Linux.
Mobile Operating System

A Mobile operating system allows smartphones, tablet PCs,
and other devices to run applications and programs. A
mobile operating system typically starts up when a device
powers on, presenting a screen with icons or tiles that present
information and provide application access. All mobile operating systems are GUI and multitasking systems.
Examples of mobile operating systems are Android, iOS, and Tizen.
Popular Operating System

Some popular operating systems are:

Windows
Windows is one of the most popular operating system used all over the world. The graphical
user interface, combined with the ease of operating and features such as multi-tasking, plug,
and play support for devices makes it one of the easiest operating systems to learn and use.

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