Types of Operating Systems

Few Operating Systems

There are several types of operating systems out there in the market but we are going to understand some of the basic ones in order to understand the fundamental basics of computers with the help of them.

Batch Operating System

• used to have one computer (mainframe).
• users give their jobs/programs/tasks to the batch operating system one by one and wait until their result is computed.

Problems with Batch OS:

1. Example (starvation)
   • Suppose J1 will have less CPU time and more I/O time then in the meantime after giving some CPU time to J1 CPU gives J1’s control to I/O and while it is being entertained by I/O. According to the rules of Batch OS any other jobs (in our case J2 J3 J4) cannot be entertained in the meantime and they have to wait for J1 to complete first.
   • And because of this CPU Idle time is more here and the drawback is, it cannot be used for other things until the first job J1 is completed.
2. Less efficient.
3. Not interactive.

• Example of Batch OS is a payroll system, bank statements etc.

Multi-programming Operating Systems

• used when we have a POOL of processes which are ready to run.
• while the J1 is entertained by I/O device the CPU can give service other jobs ( in our case J2 J3 J3).
• CPU idle time is less in these type of operating systems.

Multitasking Operating Systems

• these are nothing but an extension to Multi-programming OS mentioned above.
• each job is entertained by CPU simultaneously and it may or may not be the case that before going to J2, J1 has to be completed.
• and in that way, everything seems like very interactive.
• CPI idle is also less here.

Multi-processing Operating Systems

• more than one CPU in the same computer.
• throughput is increased as the number of processes are going to be finished in per unit of time.
• these type of OS are more reliable.

Real-time Operating Systems

• all the processes are entertained on the based of time constraint.
• the time-constrained can be a response time.