UNIT: - 01


01.01 Evaluation of Operating Systems
01.02 Types of Operating Systems
01.03 Different views of the Operating Systems

Q. What is operating system?
·     An operating system is software (it is a type of software) that supports a computer’s functions, such as controlling hardware and system applications. It also provides common services for computer programs and acts as an intermediary between a user of a computer and the computer hardware.
·     The operating system is essential component of system software.
·     These are the four components in which a computer system can be divided roughly :
1.   The hardware
2.   The operating system
3.   The application programs, and
4.   The users
·      An operating system works as a manager which provides an environment within which other programs can do useful work.
·     The hardware functions such as the CPU (Central Processing Unit), the memory, and the Input Output devices-provides the basic computing resources.
·     Here, are some examples of operating system: - UNIX-OS, MS-DOS (Micro-Soft Disk Operating System), MS-Windows - 98/XP/Vista/8.1/10 (Versions of Windows OS), Windows-NT/2000, OS/2 and Mac OS(IOS).
·      Purpose of an operating system:-
1.   Providing Execution Environment.
2.   Proper utilization of resources.
3.   Controlling programs.

Q. Objectives/goals of Operating System: -

      i.       The primary goal of some operating system is convenience for the users in an efficient manner.
     ii.       It allows hiding the details of the hardware resources from the users.
    iii.       It would act as an intermediary between its hardware &  users to making it easier for the users who uses it and to access and use other resources.
    iv.       It allows managing the resources of a computer system.
  v.   Among users and programs, to provide efficient and fair sharing of resources.

Q. Features of an operating system program: -
·      It acts as an interface between the software and the computer hardware.
·      Due to the set of integrated specialized programs it used to manage overall resources and operations of the computer.

Q.  Functions of Operating System: -

·       Process management: -

a.   Control execution of applications.
b.   Create, execute and delete a process.
c.    Cancel or resume a process.

·       Main-Memory management: -
a.   Allocate memory.
b.   Keep track of free memory
c.    Keep track of memory usage.

·       File management: -
a.   Create and delete both files and directories.
b.   Provide access to files.
c.    Keep backup of files.
d.   Secure files.

·       System management: -
a.   Open, close and write device drivers.
b.   Communicate, control and monitor the device driver. 

·       Secondary Storage management: -
a.   Free-space management
b.   Storage allocation
c.    Disk scheduling 

·       Protection system: -
a.   Protects the resources of system.
b.   It provide basic protection to OS i.e. authentication, read & write encryption.

·       Program execution and I/O Operations: -
a.   It loads the content of the file into memory.

·       Communication and error detection: -
a.   Deals with network devices for message passing
b.   Also perform error detection.

01.01  Evaluation of Operating Systems: -

The evolution of operating systems is dependent on the development of computer systems and there uses, depend on users.
Some important development: -
             i.        In 1945 ENIAC Developed by Moore School of Engineering, University of Pennsylvania.
           ii.        In 1949 EDSAC and EDVAC were developed.
      iii.        In !949 BINAC which was a successor to the ENIAC (also say that advance version of ENIAC)
          iv.        In 1951 UNIVAC developed by Remington
           v.        In 1952 IBM 701 launch into the computer industries.
          vi.        Between the years of 1954-1957  FORTRAN was developed
         vii.        In 1966 Minicomputers got cheaper, more powerful, and really useful.
        viii.    Between the years of 1967-1968 Mouse was invented which made our work very easy.
    ix. In 1969 The UNIX Time-Sharing System from Bell Telephone Laboratories which was command based operating system also say that DOS.
           x.        August 12, 1981 IBM introduces the IBM Personal Computer commonly known as IBM PC.
          xi.        In the year of 1983 Microsoft begins work on MS-Windows which we are using now-a-days.(We use the upgrade version of windows)
    xii.        In 1984 Apple Macintosh which is a family of personal computers designed, manufactured and sold by Apple Inc. comes out.
        xiii.        In 1990 Microsoft Windows 3.0
        xiv.        In 1991 GNU/Linux
         xv.        In 1993 Windows NT (which was 32-bit operating system that supports preemptive multitasking.)
        xvi.        In 2007 iOS is mobile operating system created and developed by Apple Inc.
      xvii.        In 2008  Android OS is a mobile operating system based on a modified version of the Linux kernel and other open source software

01.02 Types of Operating Systems: -

Operating system is there form the very first computer generation. Operating systems keep evolving over the period of time. Following are few of the important types of operating system.

1.   Mainframe system: -

Mainframe computer systems were the first computers used to tackle many commercial and scientific applications

A.  Batch System: - The users of batch operating system do not interact with the computer directly.

B.  Multi-programmed system: - In multi programming system, when one program is waiting for I/O transfer, there is another program ready to utilize the CUP. So it is possible for several jobs to share for several jobs to share the time of the CPU.
C.   Interactive system: - It provides direct communication between the user and the system.
D.  Time-sharing System (Multi-tasking): - Operating system uses CPU scheduling and multi programming to provide each user with a small portion of a time.

1.   Desktop System: -

A.  Nowadays, the desktop systems are becoming more users convenient.

B.  These systems can adopt technology for larger operating systems.
C.   It can run different operating systems (Windows, MacOS, UNIX, Linux) as per use.

2.   Multi-processor System: -
In Multiprocessor systems communication takes place through shared communication takes place through shared memory parallel systems.
It has three main advantages: -
a.   Increased throughput
b.   Economy of scale
c.    Increased reliability

3.   Distributed System: -
A.  Distributed systems use multiple central processors to swerve multiple real time application.
B.  Data processing jobs are distributed among the processor accordingly to which one can perform each job most efficiently.

4.   Clustered System: -
A.  Clustered systems are made by combining multiple computers into a single system.
B.  The clustered computers share storage and are closely linked via LAN networking.
C.   Clustering is usually used to provide high availability.

5.   Real Time System: -
A.  A real time operating system is a multitasking operating system designed for real time applications i.e. embedded system, industrial robots, and scientific research.
B.  Real-time operating systems use specialized scheduling algorithms in order to provide the real time applications.
C.   Real-time systems come in two ways: -
1.   Hard real time system
2.   Soft real time system

6.   Handheld System: -
A.  Handheld system is nothing but a small computer system performs simple tasks such as calendars, email, & web browsing.
B.  A mobile device is handheld operating system which run small applications.

01.03 Different views of the Operating Systems: -

1.    User’s View: -

                   I.        The user view of computer depends on the interface which is user friendly. Every computer that is to be operated by an individual requires a user interface.

                 II.        The user interface views the directory structure and requests services from the operating system that will acquire data from input hardware devices, such a keyboard, mouse and such on output hardware devices, such as video monitor and printer.

              III.        Some computers have little or no user view. For example, embedded computers in home devices and automobiles may have numeric, keypads but they and their operating systems are designed primarily to run without user intervention.

2.  System View:  - The  operating system manages the hardware resources of computer system.

            I.        Resources include processors, memory, disks, network interfaces, I/O devices etc..
     II.        The operating system allocates resources among running programs. It controls the sharing of resources within multiple programs.
             III.        The operating system itself uses resources, which it must share with application programs.
3.  Programming  View: -

I.           The programmers view involves application programming environment which work as an interface between the user and operating systems.
II.         These applications provide writing a particular program executing, compiling and working with a developing framework with input of a skilled programmer.
III.       In short, the operating system provides an environment for developing programs which are used by other users at user view.



  1. Tsm sir,it will help me definitely in my 3rd sem xam.....you are doing a good work for the student who feel hesitation during xamination tym

  2. Sir,notes can be available in pdf form.plz reply

    1. sorry dear its not possible yet. Thnx for reading from this link keep studying and all the best...


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