Intro to Operating System

Operating System Introduction

A computer is an electronic machine, which can store, process and retrieve information trough software, which are divided into two kinds

           I.      System software

           II.      Application software

The system software is used to control and manage the operation of the computer. While the application software’s are used to control or solve the particular problems of the users.

The systems software is further divided into different categories. The most important is operating system. It controls all the computer resources, application programs and provides the services to the systems users; it also provides the platform through which the computer programs are developed.

A usual computer system consists of five major elements.

Hardware: it includes the CPU, memory and input/output deceives and provides the basic computing resources for the system.

Operating System: it manages hardware and provides the services to the application programs and system users.

System Program: these programs are set of programs that use to provide the basic services for hardware and software such as disk scanner program, backup utility program and Antivirus.

Application Programs: the programs are used to solve the problems of user. Like word processor, and web browser.

Users: the user interact with the operating system indirectly though the application programs.

Components of operating systems

The operating system is divided into various components or parts and each component performs its own role in computer operation. The components of a typical operation system are:

    * Process management
    * Memory management
    * Secondary storage management
    * I/O system
    * File system
    * Protection system
    * Command interpreter system

Process management

The most important task of operating system is to manage and monitor different processes executing in the computer (The program in execution is called a process). A system consists of a collection of processes, some of which are operating systems processes and the rest of which are user processes. The process management component of the operating system schedules the processes for execution.

The operating system also performs following major activities for process management.

v     Creates and deletes both user and system processes.

v     Suspends and resumes process

v     Provides mechanisms for process synchronization

v     Provides mechanism for processes communication between them.

Memory management

The memory unit has very important role for data processing. The processor takes data and program instruction from memory, executes them, and store results in the main memory. In some advanced computer systems, memory can share by multiple processes. The operating systems must manage the allocation memory to these processes.

The operating system performs the following major memory management tasks.

v     Manages the memory space used by different processes or user programs

v     Loads new process into memory and allocates memory space for them

v     De-allocate memory space allocated to a process when it is terminated.

v     Swaps out and swaps in process if required.

Secondary storage management

The information and programs are permanently stored on the secondary devices such as hard disk, floppy disk, tape drive etc. the programs are loaded by operating system from secondary storage in main memory before to execute.

The operating system performs the following major secondary management tasks.

v     Manages free space

v     Allocates storage area for storing information and programs

v     Manages the disk scheduling

File system management

The processed data must be stored in the form of files on storage medium and can be retrieved when required for use (a file is a storage unit and it is a collection of information or it may be a set of programs instruction). The files are stored permanently on the storage device and are organized in folders or directories so that a particular file can be easily accessed.

File management is the most visible components of an operating system. It performs the following major file management tasks.

v     File operations such as creating, deleting, closing a file.

v     Directory operation such as creating new directory or removing directory

v     File organization such as arrangement of records into files and the ways for accessing these records

v     File protection to control access the files etc

I/O system

A computer communicates information through its input and output devices. The application programs access these devices through operating system supervisor calls provided for this purpose.

The OS perform these I/O related task

v     Issues commands to various I/O devices

v     Handles I/O interrupts

v     Handles I/O errors that occur to reading and writing operation.

Protection system

The operating system provides protection to various resources of the computer against unauthorized users so that only authorized users can access the system. The operating systems use various mechanisms for the protection of the computer system.

Command interpreter system

It is the basic interface between the computer and user the user interacts with the computer by giving command to the operating system. The command interpreter is also known as command line interpreter or the shell. It gets the commend from user and executes them