OPERATING SYSTEM

 OPERATING SYSTEM

Operating System services and components

What is Operating System (OS) ?

Operating System is a system software that manages all the resources of computing devices. Manages overall resources and operations of computer. Controls and monitors the execution of all other programs that reside in the computer, which also includes application programs and other system software of the computer.

⭐ Components of Operating System

1. Process Management

2. Main Memory Management

3. File Management

4. I/O System Management

5. Secondary Storage Management

⭐ Types of Operating System

1. Batch Operating System

2. Multi-programmed Operating System

3. Time Shared Operating System

4. Multiprocessor Operating System

5. Real Time Operating System

6. Mobile OS (Android OS)

1. Batch Operating System 

This type of operating system does not interact with the computer directly. There is an operator which takes similar jobs having the same requirements and groups them into batches. It is the responsibility of the operator to sort jobs with similar needs. Batch Operating System is designed to manage and execute a large number of jobs efficiently by processing them in groups.

⭕ Advantages of Batch Operating System

1. Multiple users can share batch systems.

2. Easy to manage large work.

3. Idle time for batch OS is less.

❌ Disadvantages of Batch Operating System

1. Hard to Debug 

2. Costly

3. If any job fails, others will have to wait.

4. In a batch operating system, average response time increases as all processes are processed one by one.

🔳 Examples : Payroll Systems, Bank Statements, etc.

2. Multiprogramming Operating System

🔸In multiprogramming, more than one program lies in the memory. 
🔸The scheduler selects the jobs to be placed in ready queue from a number of programs.
🔸The ready queue is placed in memory and the existence of more than one program in main memory is known as multiprogramming.
🔸Since there is only one processor, there multiple programs cannot be executed at a time.
🔸Instead the operating system executes part of one program, then the part of another and so on.
🔳 Example : User can open word, excel, access and other application in a system.

⭕ Advantages of Multiprogramming Operating System

1. CPU is better utilized, and the overall performance of system improves.

2. It helps in reducing the response time.

3. Memory utilization is efficient.

❌ Disadvantages of Multiprogramming Operating System

1. Programmers also cannot modify a program that is being executed.

2. User is not able to interact with jobs when it is executing.

3. CPU scheduling is compulsory because lots of jobs are ready to run on CPU simultaneously.

3. Time Shared Operating System

🔸It is a type of Multiprogramming system with every process running in round robin manner. 
🔸Each task is given some time to execute so that all the tasks work smoothly. 
🔸Each user gets the time of the CPU as they use a single system. 
🔸These systems are also known as Multitasking Systems. 
🔸The task can be from a single user or different users. 
🔸The time that each task gets to execute is called quantum. 
🔸After this time interval is over, the OS switches over to the next task.

⭕ Advantages of Time Shared OS

1. Each task gets an equal opportunity.

2. Fewer chances of duplication of software.

3. CPU idle time can be reduced.

❌ Disadvantages of Time Shared OS

1. Reliability problem.

2. Data Communication problem.

3. One must take care of the security and integrity of user programs and data.