1. Chapter 1 Introduction to Operating System Part 2
F2032 Fundamental Of Operating System

2. Chapter Summary At the end of this chapter, students will be able to:
List types of operating system such as: Batch system, multiprogramming, and distributed system.
Explain the differences between different types of operating system.

3. Types of Operating System: Batch System
A batch system is one in which jobs are bundled together with the instructions necessary to allow them to be processed without intervention.
The basic physical layout of the memory of a batch job computer is shown below:
The monitor is system software that is responsible for
interpreting and carrying out the instructions in the batch jobs.
- When the monitor starts a job, the entire computer is dedicated to the job, which then controls the computer until it finishes.
Monitor (permanently resident)
User Space (compilers, programs, data, etc.)

4. Types of Operating System: Batch System
Advantages:
Move much of the work of the operator to the computer
Increased performance since it was possible for job to start as soon as the previous job finished
Disadvantages:
Due to lack of protection scheme, one batch job can affect
pending jobs (read too many cards, etc)
Example: A job could corrupt the monitor, thus affecting pending jobs
A job could enter an infinite loop

5. Types of Operating System: Multiprogramming
As machines with more and more memory became available, it was possible to extend the idea of multiprogramming (or multiprocessing) as used in batch systems.
This create a systems that would load several jobs into memory at once and cycle through them in some order, working on each one for a specified period of time.
The basic physical layout of a multiprogramming system is as shown:
Monitor (more like an operating system)
User program 1
User program 2
User program 3
User program 4

6. Types of Operating System: Multiprogramming
At this point the monitor is growing to the point where it begins to resemble a modern operating system.
It is responsible for:
Starting user jobs
Spooling operations
IO for user jobs
Switching between user jobs
Ensuring proper protection while doing the above

7. Spooling ?
Spooling refers to a process of transferring data by placing it in a temporary working area where another program may access it for processing at a later point in time.
Spooling refers to putting jobs in a buffer, a special area in memory or on a disk where a device can access them when it is ready.
Spooling is useful because devices access data at different rates. The buffer provides a waiting station where data can rest while the slower device catches up.
This temporary working area would normally be a file or storage device.

8. Types of Operating System: Multiprogramming
There are different type of Multiprogramming Operating System such as:
Multitasking Operating System
A type of multiprogramming operating system which can perform several process simultaneously.
The earliest multitasking OS available to home users was the AmigaOS.
All current major operating system support this feature.

9. Types of Operating System: Multiprogramming
Multi-user Operating System
A multi-user operating system allows for multiple users to use the same computer at the same time and/or different times.
Linux, Unix,Windows OS are some example of multitasking operating system.
Multiprocessing Operating System
An operating system capable of supporting and utilizing more than one computer.

10. Types of Operating System: Multiprogramming
Real Time Operating System
Often used as a control device in a dedicated application such as controlling scientific experiments, medical imaging systems, industrial control systems, and some display systems.
Well-defined fixed-time constraints.

11. Types of Operating System: Distributed System
A Distributed Operating System is the one that runs on multiple, autonomous CPUs which provides its users an illusion of an ordinary Centralized Operating System that runs on a Virtual Uniprocessor.
Distributed Operating Systems provide resource transparency to the user processes.
“If you can tell which computer you are using, you are not using a distributed operating system.” - Tanenbaum

12. Types of Operating System: Distributed System
The Distributed Operating System is unique and resides on different machines.
 User processes can run on any of the CPUs as allocated by the Distributed Operating System.
 Data can be resident on any machine that is the part of the Distributed System.
 All multi-machine systems are not Distributed Systems.
“It is the software not the hardware that determines whether a system is distributed or not” - Tanenbaum

13. Types of Operating System: Distributed System
Advantages:
Price/Performance advantage (Availability of cheap and powerful Microprocessors).
Resources Sharing
Computation speed up – load sharing
Reliability and Availability.
Provides Transparency.
Disadvantages:
Lack of security - Easy access also applies to secret data.

14. Types of Operating System: Distributed System
An example of a distributed system: Amoeba
An open source microkernel-based distributed operating system developed by Andrew S. Tanenbaum and others at the Vrije Universiteit.
The aim of the Amoeba project is to build a timesharing system that makes an entire network of computers appear to the user as a single machine.
Development seems to have stalled: the files in the latest version (5.3) were last modified on 12 February 2001.
Amoeba runs on several platforms, including i386, i486, , Sun 3/50 and Sun 3/60.

15. Activity
What is the main differences between batch, multiprogramming and distributed operating system?
AmigaOS is a ……………………… operating system.
Draw a basic physical layout of a multiprogramming operating system.