What is Operating System (OS) ?

It is a program that acts as an interface between a user (applications) and the computer hardware.

TYPES OF OPERATING SYSTEM

• Batch OS
• Multiprogrammed OS
• Time sharing OS
• Real time OS

Batch Operating Systems

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

Example of batch OS: IBM OS/2

Multi-Programmed Systems

• Several jobs are kept in main memory at the same time and the CPU is multiplexed among them, to increase CPU utilization.

• When this job in execution needs an input/output operation to complete, Instead of waiting for the job to complete the input/output, it switches to the subset of jobs waiting for CPU.

Example: Windows and Unix

Time Sharing System (Multitasking)

• Time sharing or multitasking is a logical extension of multiprogramming. Multiple jobs are executed by the CPU switching between them, but the switches occur so frequently that the users may interact with each program while it is running.

Example: Windows, Linux and Unix.

Real Time System

Used when there are rigid time requirements on the operating of a processor or the flow of data. Systems that control scientific experiments, medical imaging systems, industrial control systems, and some display systems are real-time systems. Example: RTOS