Types of Operating System

Types of Operating System

There are operating systems from the very first generation of computers and they continue to develop over time. In this chapter, we will discuss some of the most widely used significant types of operating systems.

Batch operating system

Batch operating system users aren't specifically interacting with the computer. Each user prepares his job, like punch cards, on an off-line system and submits it to the computer operator. Jobs with common needs are batched together to speed up processing and run as a group. The programmers leave the operator with their programmes, and the operator then sort the programmes with similar requirements into batches.

Batch Systems problem is as follows –

• Lack of interaction between the user and the job.
• CPU is often idle because the speed of the mechanical I/O devices is slower than the CPU.
• Difficult to provide the desired priority.

Time-sharing operating systems

Time-sharing is a technique that allows several users to simultaneously use a particular computer system, located at different terminals. Multiprogramming is a functional extension of time-sharing or multitasking. The time that is shared by multiple users at the same time is called time-sharing.

The key difference between Multi programmed Batch Systems and Time-Sharing Systems is that in the case of Multi programmed batch systems, the target is to optimise processor utilisation, while in Time-Sharing Systems the goal is to reduce response time.

The Processor executes several jobs by switching between them, but the switches only occur too often. So the user can get an immediate answer. For example, the processor executes each user programme in a short burst or a quantity of computation in a transaction processing. That is, each user can get a quantum time if n users are present.

The operating system uses CPU scheduling and multiprogramming to produce a specific portion of time for each user. Computer systems that were originally configured as batch systems were changed to time-sharing systems.

Timesharing operating systems have the following benefits −

• Provides the value of the quick response.
• Avoids software duplication.
• Reduces idle time on CPU.

Time-sharing operating systems have the following disadvantages-

• Reliability Issues.
• Issue of Software systems and data protection and honesty.
• Data Communication Issues.

Distributed operating System

Distributed systems use multiple central processors to support multiple applications and multiple users in real-time. Data processing jobs are accordingly distributed among the processors.

The processors communicate with each other through various lines of communication (such as high-speed buses or telephone lines). These are called loose linking or distributed systems. The size and role of the processors within a distributed system can vary. These processors are referred to as web pages, nodes, computers, etc.

Distributed systems profit as follows −

• With the facility of resource sharing, a user at one site can be able to use the available resources at another.
• Speed up data exchange with each other via electronic mail.
• In a distributed system, if one site fails, the remaining sites may theoretically continue running.
• Better service to the customers.
• Reduction of the load on the host computer.
• Reduction of delays in data processing

Network operating System

A network operating system runs on a server and gives the server the ability to handle data, users, groups, protection, applications and other networking functions. The network operating system's primary purpose is to allow shared file and printer access between multiple computers in a network, usually a local area network ( LAN), a private network or other networks.

Examples of network operating systems include Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX, Linux, Mac OS X, Novell NetWare, and BSD.

The network operating systems profit as follows −

• Centralized servers are remarkably stable.
• Protection is handled on the server.
• Easily incorporate upgrades to modern software and hardware into the system.
• Different locations and types of systems allow remote access to servers

The network operating systems have the following drawbacks −

• High cost to buy and run a computer.
• For most activities dependence on a central location.
• Includes daily maintenance and updates.

Real Time operating System

A real-time system is characterised as a data processing system where the time period needed for processing and responding to inputs is so small that the environment is regulated. The system's delay in responding to input and showing the necessary updated information is called response time. The response time in this system is also much less than in online processing.

Real-time systems are used when the operation of a processor involves rigid time or data flow, and real-time systems may be used as a control device in a specialised programme. An operating system in real-time must have well-defined, fixed time constraints or the system would fail.

For example, Scientific experiments, medical imaging systems, industrial control systems, weapon systems, robots, air traffic control systems, etc.

There are two types of real-time operating systems.

Hard real-time systems

Hard real-time systems ensure critical tasks are performed on time. Secondary storage is minimal or missing in hard-time real-time systems and the data is stored in ROM. Virtual memory is almost never contained in such systems.

Soft real-time systems

Less rigid soft real-time systems. A vital task in real-time takes precedence over other tasks and holds the priority until it is complete. Soft real-time systems have little effectiveness compared to hard real-time systems. Multimedia, virtual reality, Advanced Research Projects such as exploration missions, planetary rovers etc.