An operating system is a program which controls the execution of application programs and acts as an intermediary between the user of a computer and the computer hardware. A program which is being executed is also called a process or job. The different types of Operating Systems are discussed below:
Here, in this context, a batch is defined as a group of jobs (processes) with similar needs and resource requirements. These type of operating systems do not interact with the computer directly but is done with the help of a central component or operator. Batch processing system allows the users to submit jobs to the operator where these jobs will be sorted into a batch based on their similar needs. These batches are then subsequently placed on an input queue at the computer where each batch is considered as a single process and executed sequentially.
Advantages of Batch Processing
Batch processing provides for an easy management system since large amount of processes can be combined into a batch rather than processing them individually.
The processor can be left running without supervision once the process begins.
Multiple users can use this type of system.
Processors are aware of the time requirement of the jobs when they are in
Disadvantages of Batch Processing
There is no direct interaction between user and the computer.
Determining and maintaining the priority between the batches can be very difficult.
Batch systems are hard to debug and a failure in any job may mean the other jobs will have to wait for a long period of time before they are executed.
Time Sharing Operating System
A time sharing operating system allocates the computer resources to various programs in time slots and thus allows multiple users to share the compute resources simultaneously. It is also known as Multitasking Systems and the time allocated to each task to be executed is called quantum. That is, if n users are present, then each user gets a time quantum to use the resources
such as the processor, memory, etc.
Computer which were designed primarily as batch systems have been modified to time-sharing or multitasking systems.
Advantages of Time Sharing System
Multiple users can execute their task simultaneously. CPU idle time gets reduced.
An equal opportunity is given to each task.
Disadvantages of Time Sharing System
There is a question on the security and integrity of the user’s data and programs.
Since multiple processes are managed simultaneously, as a result, it requires
an adequate management of main memory.
Multi Programming Operating System
A multiprogramming operating system is a system that allows more than one or multiple active programs to be stored in main memory simultaneously. It is an extension to the batch processing system, designed to overcome the problem of under utilisation of CPU and main memory .
Each process requires CPU time as well as I/O time and in this type of system, each process is handled in such a way that when one process is transferred to I/O, the CPU picks out one of the other processes and start their execution.
Advantages of Multi Programming Operating System
Increases CPU utilisation and reduce CPU idle time.
Disadvantages of Multi Programming Operating System
In cases where the process consumes more than available memory, it may cause the system to slow down.
Real Time Operating System
A real-time system is an operating system which is intended to carry out real- time application requests. In other words, the time required to process inputs is so less that it is able to process data as it comes, without any buffering delay. This time interval required to process the input and display the output is called the response time. These type of OS are used in systems with fixed
time constraints such as scientific instruments, robots, air traffic control systems, etc.
Real time systems may be of two types:
Soft Real Time Systems: In these systems, even if the process is not executed within a certain deadline, the system will continue to work with no failures, however, its performance may degrade.
Hard Real Time Systems: If the processes are not executed within the given deadline, then the system will not work and may cause severe damage.
Advantages of Real Time Operating System
• There is maximum utilisation of devices and systems.
• This type of system accelerates the process by auto-managing the system resources.
• These type of systems are error free.
Disadvantages of Real Time Operating System
• If processes are not executed within the given time deadlines, it may result
in some damages.
• These systems are more vulnerable to security breaches.
• It uses heavy system resources and the algorithms are also complex in
Network Operating System
A Network Operating System runs on a server and provides connectivity among a number of autonomous computers. It is capable of managing data, users, security, applications and other networking functions. A typical configuration consists of a group of computers known as a tightly coupled systems, with a common server, printer, shared files and applications etc. tied
together usually by local area network (LAN) or other networks.
Networking Operating Systems may either be peer-to-peer or client-server systems. In a peer-to-peer network, all computers have the same privileges to use the resources available on the network. In the Client/server network operating systems, one of the computers act as a central file server responsible for providing access to resources and security to the other computers.
Advantages of Network Operating System
•In these type of systems, the security to the machines is managed by the server.
• New technology and hardwares can be easily integrated into the system.
•In this model, different machines can remotely access the server from different locations.
• Remote access to servers is possible from different locations and systems.
Disadvantages of Network Operating System
• Buying and running a server is costly.
• Regular maintenance and update is necessary.
Distributed Operating System
A distributed operating system is an extension of the network operating system which furthermore supports higher levels of communication and integration of various autonomous computers interconnected by the network.
These computers have their own processor and memory unit and are also known as loosely coupled systems.
These systems use multiple CPUs to serve multiple real-time applications and multiple users, wherein the processes or jobs are distributed among the processors and they communicate with one another through various communication lines, such as high speed buses or telephone lines.
Advantages of Distributed Operating System
• They are more reliable because unlike central systems, when one site fails
in a distributed system, the remaining sites can potentially continue
• Reduction of load on the host computer.
• These systems are easily scalable as many systems can be easily added to the network
Disadvantages of Distributed Operating System
• These type of systems are not only expensive but also very complex, and thus are rarely available.
• Failure of the main network will stop the entire communication
Multiprocessing Operating System
A multiprocessing operating system, also known as tightly coupled system, is one which uses two or more independent central processing units ( CPU )within a single computer system. The processors are in constant close communication with each other sharing resources such as memory and peripheral devices. They are typically utilised when there is a need to process
large volumes of data with high speed.
Advantages of Multiprocessing Operating System
• They offer shorter responses time or better performance than single processor systems.
• In the event that one of the processors may fail, the other processor(s) automatically takes over the system workload.
Disadvantages of Multiprocessing Operating System
• Expensive to procure and maintain.