Architecture, Goals & Structures of O.S, Basic functions, Interaction of O. S. & hardware architecture, System calls,

Operating Systems 


Q.        What is an operating systems ?       ---- 4 marks.

Definition of an OS
An operating system is an interface between users and hardware of a compute system. An operating system manages resources of a computer .

            These resources include :

a) Memory    b) Processor    c) Input / Output devices      d) File system

OS keeps track of each resource and decides who will get control over resources, for how long.

Architecture of an OS

                                                                                                      Fig . Architecture of an OS

Operating system makes computer more convenient to use. All resource are used in very efficient way.

Functions of an OS


Q.        Explain functions of an operating system.   ---- 4 marks

Ans:-   Operating system works as an interface between user and the computer.

Functions of Operating System :-

1) Program Development :- Operating system provide a set of utility program which are necessary to program development. (e.g . Editor, linker, etc )

2) Program Execution :- Operating system handles loading of programs from secondary memory to primary memory. It makes program available for execution.

3) I/O Operations :- A running program may require I/O. I/O operations are handled by operating system.

4) File System Manipulations :- An operating system provides various system calls for manipulation of files.

5)  Communication :- Under many situations a process has to communicate with other process. Communication is required for exchange of information. Communication done through message pipes, mailbox, etc.

6) Resource Sharing and Protection :- Resources are shared properly with all processes as well as protection is also provided.

7) Error Detection :- Different types of errors may occur while a computer system is running.

8) Accounting :- Operating system keeps track of every action. For how much duration user has a log, what modifications he did , etc.

System Calls


Q. Explain system calls and its different types ? ------ 4 marks

Ans:- System calls :-System calls provide interface between user program or application program and the operating system.

Types of System Calls :-

a) File management :- These system calls are used to create file, open file, close file, read as well as write files, etc.

b) Process Management :- System calls for process management are create, terminate, load as well as execute process.

c) Inter process communication :- For sharing information some system calls are used. It uses pipes, semaphore, mail box, message queue, etc for inter process communication.

d) I/O device management :- System calls for device management are request ( ) device, release  ( ) device.

e) Information processing and maintenance :- System calls for this category is set time, set date , get time, get date.


  • Notes by Prof. D. B. Pawar, Team WikiNote, Pune
  • WikiNote Foundation

Last modified: Friday, 20 September 2019, 1:03 AM