Operating System PPT

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Operating System


DEFINITION OF OS An operating system is a program that acts as an interface between the user and the computer hardware and controls and manages the overall resources of computer system. Goals of an OS:- Making computer system convenient to use in effective manner. Manages resources of a computer system. Example of os:- Ms-dos Windows Solaris

Computer System Components:

Computer System Components 1 . Hardware – provides basic computing resources (CPU, memory, I/O devices). 2. Operating system – controls and coordinates the use of the hardware among the various application programs for the various users. 3. Applications programs – define the ways in which the system resources are used to solve the computing problems of the users (compilers, database systems, video games, business programs). 4. Users (people, machines, other computers).

Structure of Operating System::

Structure of Operating System: USERS Application Software Operating System HARDWARE


5 Program Interface Humans User Programs O.S. Interface O.S. Hardware Interface/ Privileged Instructions Disk/Tape/Memory View of System Components

Evolution of OS:

Evolution of OS Major Phases Technical Innovations Operating Systems Open Shop The idea of OS IBM 701 open shop (1954) Batch Processing Tape batching, First-in, first-out scheduling. BKS system (1961) Multi- programming Processor multiplexing, Indivisible operations, Demand paging, Input/output spooling, Priority scheduling, Remote job entry Atlas supervisor (1961), Exec II system (1966)

Evolution of OS :

Evolution of OS Timesharing Simultaneous user interaction, On-line file systems Multics file system (1965), Unix (1974) Concurrent Programming Hierarchical systems, Extensible kernels, Parallel programming concepts, Secure parallel languages RC 4000 system (1969), 13 Venus system (1972), 14 Boss 2 system (1975). Personal Computing Graphic user interfaces OS 6 (1972) Pilot system (1980) Distributed Systems Remote servers WFS file server (1979) Unix United RPC (1982) 24 Amoeba system (1990)

Basic functions of the operating system:

Operating System Device configuration Controls peripheral devices connected to the computer File management Transfers files between main memory and secondary storage, manages file folders, allocates the secondary storage space, and provides file protection and recovery Memory management Allocates the use of random access memory (RAM) to requesting processes Interface platform Allows the computer to run other applications Basic functions of the operating system

Features of operating system :

Features of operating system 1. Program execution Interrupts Protected mode and supervisor mode Memory management Virtual Memory Multitasking Disk access and file systems Device drivers Networking Security

Need of operating system :

Need of operating system Operating System provides a stable and consistent way to deal with hardware without having to know all the details of the hardware. 2. To manage the hardware and software resources. 3. It plays the role of good parent, making sure that each application gets the necessary resources while playing nicely with other applications.


TYPES OF OS Early os or serial processing Single Program os Multiprogram os Multitasking os Time sharing os Multiprocessing os Real time os Distributed os


EARLY O.S OR PROCESSING O.S In serial operating system only one job resides in computer memory and it remains there till it is executed. After completion of job, next ob is entered. Disadvantages:- cpu remains idle for most of time. Very slow Waiting time of jobs are more Advantages:- Resource management is very easy. allocation is very easy. O.S User Program Area

Single Program os: :

Single Program os : Provides a platform for only one user at a time. They are popularly associated with Desk Top operating system which run on standalone systems where no user accounts are required. Example: DOS


MULTIPROGRAMMING O.S It refers to holding more than one process in memory and executing them concurrently. It increase cpu utilisation such that cpu always has one to execute. Example of multiprogramming is given below:- SUPERVISOR PROGRAM A PROGRAM B PROGRAM C (waiting for CPU) CPU Writing o/p data Execution in progress Main memory Secondary disk storage


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

Multi user/Multi tasking OS:

Multi user/Multi tasking OS


Processor’s time is shared among multiple users Multiple users simultaneously access the system through terminals. Advantages:- Reduce CPU idle time. Provides advantage of quick response. Disadvantages:- Problem of data communication. Question of security and integrity of user program and data 17 Time Sharing O.S.


Terminal 1 Terminal 2 Terminal n time sharing supervisor User 1 User 2 User n User n User 1 Main memory Online storage User 2 CPU User 1 User 2 User n Time Sharing Process

Multi processing or parallel processing O.S:

Multi processing or parallel processing O.S This technique consist of two or more CPUs, perform more than one job at a time. Fig:- I/O processor CPU 1 I/O units I/O units I/O processor CPU 2 Main memory

Advantages of Multi processing or parallel processing O.S:

Advantages of Multi processing or parallel processing O.S Better throughput Better reliability Saving cost

Disadvantages of Multi processing or parallel processing O.S:

Large main memory is required Such system are expensive. Disadvantages of Multi processing or parallel processing O.S

Parallel Computing Systems:

Parallel Computing Systems Climate modeling, earthquake simulations, genome analysis, protein folding, nuclear fusion research, ….. ILLIAC 2 ( UIllinois ) Connection Machine (MIT) IBM Blue Gene Tianhe-1(China) K-computer(Japan)

Real time O.S:

Real time O.S It is a multiprogramming system that aims at executing real time applications. Its main objective is their quick and predictable response to events. Examples are:- ATM machine Flight control etc. Advantages:- Better throughput Response time is very less Disadvantages:- Very costly Large memory required

Distributed O.S:

Distributed O.S A distributed system uses multiple central processors to serve multiple real time applications. With distributed processing, related data at all terminals is synchronized, updated simultaneously. It allows the user to access remote resources in the same manner as local resources as they do. It is a collection of processors that do not share memory. Each processor has its own local memory. The use of multiple processors is invisible to the user i.e. the users are not aware of where these file are residing. These are handled automatically and efficiently by the os .


Operating system Platform Developer AIX/AIXL Various IBM AmigaOS Amiga Commodore BSD Various BSD Caldera Linux Various SCO Corel Linux Various Corel Debian Linux Various GNU DUnix Various Digital DYNIX/ ptx Various IBM HP-UX Various Hewlett Packard IRIX Various SGI Kondara Linux Various Kondara Various operating systems developed by various companies


Operating system Platform Developer Linux Various Linus Torvalds MAC OS 8 Apple Macintosh Apple MAC OS 9 Apple Macintosh Apple MAC OS 10 Apple Macintosh Apple MAC OS X Apple Macintosh Apple Mandrake Linux Various Mandrake MINIX Various MINIX MS-DOS 1.x IBM / PC Microsoft MS-DOS 2.x IBM / PC Microsoft MS-DOS 3.x IBM / PC Microsoft MS-DOS 4.x IBM / PC Microsoft


Akshit Kumar Chandora XI Science Made BY-

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