1.Single Process OS

• eg: MS DOS
• Execute job one by one cannot multitask (maximum utilization of CPU is not done)
• Process starvation
• no high priority

2.Batch Processing

• eg:ATLAS OS
• Batch wise execution
• low cpu utilization
• Process Starvation inside batch
• Batch Starvation
• no high priority

3.Multi Programming OS

• eg: THE
• single cpu
• multitask
• context switching: when P1 goes for IO and P2 comes to execute.P1 gets stored in PCB(Process Control Block)

4.Multitasking OS

• eg: CTSS
• single cpu
• time sharing(when time is reached then next task is executed by stopping the previous one)
• max cpu utilization
• no starvation
• context switching
• high priority

5.Multi Processing

• eg: Windows
• time sharing
• context switching
• multiple cpu

6.Distributed OS

• eg: Solaris
• loosely coupled
• connected through network

7.Real Time OS

• eg: air traffic control in airport
• for high accuracy
• industrial applications like nuclear plant