Operating System

 

What is Operating system?

An Operating System performs all the basic tasks like managing files, processes, and memory. Thus operating system acts as the manager of all the resources, i.e. resource manager. Thus, the operating system becomes an interface between user and machine. 

Types of Operating Systems:

1.      Batch Processing

2.      Multiprogramming

3.      Time Sharing OS

Batch Processing OS:

This type of operating system does not interact with the computer directly. There is an operator which takes similar jobs having the same requirement and group them into batches. It is the responsibility of the operator to sort jobs with similar needs.

Advantages of Batch Operating System: 

• It is very difficult to guess or know the time required for any job to complete. Processors of the batch systems know how long the job would be when it is in queue
• Multiple users can share the batch systems
• The idle time for the batch system is very less
• It is easy to manage large work repeatedly in batch systems

Disadvantages of Batch Operating System:  

• The computer operators should be well known with batch systems
• Batch systems are hard to debug
• It is sometimes 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. 

Multi Programming OS:

Multiprogramming is an extension to batch processing where the CPU is always kept busy. Each process needs two types of system time: CPU time and IO time.

In a multiprogramming environment, when a process does its I/O, The CPU can start the execution of other processes. Therefore, multiprogramming improves the efficiency of the system.

Advantages of Multiprogramming OS

• Throughout the system, it increased as the CPU always had one program to execute.
• Response time can also be reduced.

Disadvantages of Multiprogramming OS

• Multiprogramming systems provide an environment in which various systems resources are used efficiently, but they do not provide any user interaction with the computer system.

Time Sharing OS:

Each task is given some time to execute so that all the tasks work smoothly. Each user gets the time of 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 also. The time that each task gets to execute is called quantum. After this time interval is over OS switches over to the next task. 

Advantages of Time-Sharing OS:  

• Each task gets an equal opportunity
• Fewer chances of duplication of software
• CPU idle time can be reduced

Disadvantages of Time-Sharing OS:  

• Reliability problem
• One must have to take care of the security and integrity of user programs and data
• Data communication problem

Examples of Time-Sharing OSs are: Multics, Unix, etc.