1. Introduction to Operating Systems Prepared by: Dhason Operating Systems

2. Operating Systems Introduction to Operating Systems Slide 2 of 23 Topic & Structure of the lesson Basic functions of operating systems

3. Operating Systems Introduction to Operating Systems Slide 3 of 23 Learning Outcomes At the end of this lecture YOU should be able to: - Discuss the functions of operating systems

4. Operating Systems Introduction to Operating Systems Slide 4 of 23 Introduction A computer system consists of : - users, application programs, operating systems and hardware An operating system is the layer of software that manages all parts of the hardware and presents an interface that is easier to understand An operating system shields programmers from hardware complexity

5. Operating Systems Introduction to Operating Systems Slide 5 of 23 Introduction (cont.) An operating system can be defined as : - a program that acts as an intermediary between a computer user and the computer hardware - a resource allocator - a resource manager - a control program

6. Operating Systems Introduction to Operating Systems Slide 6 of 23 Basic Functions of an Operating System Accepts commands from the user Provides desired services to the user and user programs Act as a system manager / resource manager - controls hardware and software - act as an interface between user and system Manages resources of the computer effectively

7. Operating Systems Introduction to Operating Systems Slide 7 of 23 Services of an Operating System A.Services provided to users and programs: Program Execution – loads a program in memory, runs and terminates the execution either normally or abnormally Input-Output Operations – control input-output devices File System Manipulation – allow reading, writing, deletion, creating of files

8. Operating Systems Introduction to Operating Systems Slide 8 of 23 Services of an Operating System (cont.) Communication – manage shared memory or message passing for the exchange of information between processes Error Detection – take measures to correct errors to ensure a consistent state

9. Operating Systems Introduction to Operating Systems Slide 9 of 23 Services of an Operating System (cont.) B. Services to ensure efficient operation of the operating system: Resource allocation – CPU scheduling routines for memory, input output devices, file storage to decide the best method to utilize the CPU Accounting – which users are using what kind and how much resources. Usage statistics for performance improvement Protection – user, process and data protection

10. Operating Systems Introduction to Operating Systems Slide 10 of 23 Quick Review Questions 1) State and explain one function of operating systems

11. Operating Systems Introduction to Operating Systems Slide 11 of 23 Q & A Question and Answer Session