Operating System

Operating System

1. Operating System Definition

   • It is a software that works as an interface between a user and the computer hardware.
   • primary objective
     • of an operating system is to make computer system convenient to use and to utilize computer hardware in an efficient manner
   • performs the basic tasks
     • receiving input from the keyboard
     • processing instructions
     • sending output to the screen

2. Examples of operating system

   • UNIX
   • MS-DOS
   • MS-Windows
   • 98/XP/Vista
   • Windows-NT/2000
   • OS/2
   • Mac OS
   • LINUX

3. Functions of operating system

   • Process management
   • Memory management
   • File management
   • Device Management
   • I/O System Management
   • Secondary-Storage Management
   • Security
   • Command interpretation
   • Networking
   • Job accounting
   • Communication management

4. Features of Operating System (OS)

   • Protected and supervisor mode
   • Allows disk access and file systems Device drivers Networking Security
   • Program Execution
   • Memory management Virtual Memory Multitasking
   • Handling I/O operations
   • Manipulation of the file system
   • Error Detection and handling
   • Resource allocation
   • Information and Resource Protection

5. Types of Operating System (OS)

   • Batch Operating System
   • Multitasking/Time Sharing OS
   • Multiprocessing OS
   • Real Time OS
   • Distributed OS
   • Network OS
   • Mobile OS

6. Advantages and Disadvantages

   • Advantage of using Operating System
     • hide hardware details
       • mediante la creación de una abstracción
     • Easy to use with a GUI
     • Offers an environment in which a user may execute programs/applications
     • The operating system must make sure that the computer system convenient to use
     • Operating System acts as an intermediary
       • among applications and the hardware components
     • It provides the computer system resources with easy to use format
     • Acts as an intermediator
       • Between all hardware's and software's of the system
   • Disadvantages of using Operating System
     • If any issue occurs in OS
       • You may lose all the contents which have been stored in your system
     • Operating system's software is quite expensive for small size organization
       • Which adds burden on them
         • Example Windows
     • It is never entirely secure
       • As a threat can occur at any time

7. Structure of an Operating System

   • It is composed of a KERNEL
     • some servers
       • posssibly some user-level libraries
     • The kernel provides operating system services
       • through a set of procedures
         • through SYSTEM CALLS
           • transfer control to the kernel when they are invoked at run time
   • servers
     • are user processes that offer operating system services to other processes
   • Simple Structure
     • A common example of this is MS-DOS
   • Layered Structure
     • the bottom layer is the hardware
     • the topmost layer is the user interface