1. TYPES OFF OPERATING SYSTEM
Lecture 2

2. Common Operating Systems and Their Differences
Network Operating System
UNIX / Linux / MS Windows2000 Server
Desktop Operating System
MS Windows 9X/Me / Mac OS / DOS
Mobile Operating System
Palm OS and Pocket PC

3. Examples Common operating systems WINDOW UNIX
used in IBM compatible microcomputers
UNIX
multi-user, multi-tasking OS used in minicomputers and microcomputers

4. DOS interface

5. GUI

6. Different Types of Operating System

7. Type of Operating System
Batch processing
Real time processing
Time sharing processing
Distributed operating System
Network operating System

8. Batch processing
Jobs, together with input data, are fed into the system in a batch.
The jobs are then run one after another.
No job can be started until previous job is completed

9. Real time processing immediate response is needed. For example
anti-missile defense system
airplane landing control system
interrupt error in computer system

10. Time sharing processing
Each user is given a time slice to interact with the CPU.
The size of the time slice will depend on the system.
Each user is served in sequence.

12. Distributed operating System
Distributed systems use multiple central processors to serve multiple real time application and multiple users. Data processing jobs are distributed among the processors accordingly to which one can perform each job most efficiently.
The processors communicate with one another through various communication lines.
Processors in a distributed system may vary in size and function.
These processors are referred as sites, nodes, computers and so on.

13. Advantages of distributed systems
The advantages of distributed systems are following.
With resource sharing facility user at one site may be able to use the resources available at another.
Speedup the exchange of data with one another via electronic mail.
If one site fails in a distributed system, the remaining sites can potentially continue operating.
Better service to the customers.
Reduction of the load on the host computer.
Reduction of delays in data processing.

14. Network operating System
Network Operating System runs on a server and provides server the capability to manage data, users, groups, security, applications, and other networking functions.
The primary purpose of the network operating system is to allow shared file and printer access among multiple computers in a network, typically a local area network LAN, a private network or to other networks.
Examples of network operating systems are Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX, Linux, Mac OS X, Novell NetWare, and BSD.

15. Advantages of network operating systems
Centralized servers are highly stable.
Security is server managed.
Upgrades to new technologies and hardwares can be easily integrated into the system.
Remote access to servers is possible from different locations and types of systems.

16. Disadvantages of network operating systems
The disadvantages of network operating systems are following.
High cost of buying and running a server.
Dependency on a central location for most operations.
Regular maintenance and updates are required.

17. Special Features of OS multi-tasking multi-programming
parallel processing
buffering
spooling

18. Multi-tasking
to handle 2 or more programs at the same time from a single user ‘s perception
CPU can only perform one task at a time, however, it runs so fast that 2 or more jobs seem to execute at the same time

19. Multi-programming
2 or more programs store in the main memory at the same time
when one job reeds to wait (e.g. I/O operation), CPU switch to another job to execute
when the first job finishes waiting, CPU will get back the first job to execute

20. Illustration of the multiprogramming concept

21. Parallel Processing use 2 or more CPUs to handle jobs
computer networking
without multiprocessing
with multiprocessing
Job 4
Job 3
Job 4
Job 2
time
Job 3
time
Job 1
Job 1
Job 2
CPU 1
CPU 2
CPU 1

22. Buffering
a temporary storage area (buffers) to read data from input device or send data to the output device
keep CPU busy
because I/O operation is slow

23. Spooling a larger buffer from hard disk
buffer store the data through I/O operation
because I/O operation is slow and CPU operation is fast