Operating systems are there from the very first computer generation and that they keep evolving with time. In this chapter, we’ll discuss a number of the different types of operating systems which are most ordinarily used.
Batch operating system
TThis type of operating system does not interact with the computer directly. There is an operator which takes similar jobs having same requirement and group them into batches. Each user prepares his job on an off-line device like punch cards and submits it to the pc operator. To speed up processing, jobs with similar needs are batched together and run as a group.
Advantages of Batch Operating System
- Multiple users can share the batch systems
- The idle time for batch system is very less
- It is easy to manage large work repeatedly in batch systems
Disadvantages of Batch Operating System
- Lack of interaction between the user and therefore the job.
- Batch systems are hard to debug.
- CPU is usually idle, because the speed of the mechanical I/O devices is slower than the CPU.
- Difficult to provide the desired priority.
- It is sometime costly.
- The other jobs will have to wait for an unknown time if any job fails.
Examples of Batch based Operating System: Payroll System, Bank Statements etc.
Time-sharing operating systems
These are multi-user and multi-process systems. Multi-user means system allows multiple users simultaneously. In this system, a user can run one or more processes at the same time. Examples of time-sharing systems are UNIX, Linux, Windows server editions.Time-sharing may be a technique which enables many of us , located at various terminals, to use a specific computing system at an equivalent time. Time-sharing or multitasking may be a logical extension of multiprogramming. Processor’s time which is shared among multiple users simultaneously is termed as time-sharing.
The main difference between Multiprogrammed Batch Systems and Time-Sharing Systems is that just in case of Multiprogrammed batch systems, the target is to maximise processor use, whereas in Time-Sharing Systems, the objective is to minimize response time.
Multiple jobs are executed by the CPU by switching between them, but the switches occur so frequently. Thus, the user can receive an immediate response. For example, during a transaction processing, the processor executes each user program during a short burst or quantum of computation. That is, if n users are present, then each user can get a time quantum. When the user submits the command, the reaction time is in few seconds at the most .
The OS uses CPU scheduling and multiprogramming to supply each user with a little portion of a time. Computer systems that were designed primarily as batch systems are modified to time-sharing systems.
Advantages of Timesharing Operating System
- Provides the advantage of quick response.
- Less chances of duplication of software.
- CPU idle time can be reduced.
Disadvantages of Timesharing Operating System
- Reliability problem.
- Question of security and integrity of user programs and data.
- Problem of data communication.
Examples of Time-Sharing OS : Multics, Unix etc.
Distributed operating System
Distributed 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 each other through various communication lines (such as high-speed buses or telephone lines). These are referred as loosely coupled systems or distributed systems. Processors during a distributed system may vary in size and performance . These processors are referred as sites, nodes, computers, and so on.
Advantages of Distributes Operating System
- With resource sharing facility, a user at one site could also be ready to use the resources available at another.
- Electronic mail increases the data exchange speed.
- If one site fails during a distributed system, the remaining sites can potentially continue operating.
- Better service to the customers.
- Load on host computer reduces.
- Delay in data processing reduces.
Disadvantages of Distributed Operating System
- Entire communication will stop on failure of main network.
- Language are not well defined to establish distributed systems.
- Not available easily as they are vey expensive.
- underlying software is highly complex and not understood well.
Example of Distributed Operating System : LOCUS
Network operating System
These systems run on a server and supply the potential to manage data, users, groups, security, applications, and other networking functions. These sort of operating systems allow shared access of files, printers, security, applications, and other networking functions over alittle private network. another important aspect of Network Operating Systems is that each one the users are cognizant of the underlying configuration, of all other users within the network, their individual connections etc. and that’s why these computers are popularly referred to as tightly coupled systems.
Advantages of Network Operating System
- Centralized servers are highly stable.
- Security is server managed.
- Upgrades to new technologies and hardware are often easily integrated into the system.
- Remote access to servers is feasible from different locations and kinds of systems.
Disadvanatages of Network Operating System
- High cost of buying and running a server.
- Dependency on a central location for most operations.
- Regular maintenance and updates are required.
Example of Network Operating System : Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX, Linux, Mac OS X, Novell NetWare, and BSD.
Real Time operating System
A real-time system is defined as a knowledge processing system during which the interval required to process and answer inputs is so small that it controls the environment. The time taken by the system to reply to an input and display of required updated information is termed because the reaction time . So during this method, the reaction time is extremely less as compared to online processing.
Real-time systems are used when there are rigid time requirements on the operation of a processor or the flow of knowledge and real-time systems are often used as an impact device in a dedicated application. A real-time OS must have well-defined, fixed time constraints, otherwise the system will fail. For example, Scientific experiments, medical imaging systems, industrial control systems, weapon systems, robots, traffic control systems, etc.
There are two types of real-time operating systems.
Hard real-time systems
Hard real-time systems guarantee that critical tasks complete on time. In hard real-time systems, auxiliary storage is restricted or missing and therefore the data is stored in ROM. In these systems, virtual storage is nearly never found.
Soft real-time systems
Soft real-time systems are less restrictive. A critical real-time task gets priority over other tasks and retains the priority until it completes. Soft real-time systems have limited utility than hard real-time systems. For example, multimedia, computer game , Advanced Scientific Projects like undersea exploration and planetary rovers, etc.
Advanatages of Real-time Operating System
- produce more output utilizing maximum devices and system.
- shifting time of task is very less.
- more focus is given on running application than on application which are on queue.
- they can be used on embedded system
- they are almost error free.
- memory allocation is best managed.
Disadvanatages of Real-time Operating System
- Less number of task can run at the same time.
- complex algorithm
Examples of Real-tome Operating System:Scientific experiments, medical imaging systems, industrial control systems, weapon systems, robots, air traffic control systems, etc.
Read more: Operating System
Join Us: Facebook page