Category : SSC
Operating System
An operating system consists of a set of programs, which controls, coordinates and supervises the activities of the various components of a computer system. It is a program which acts as an interface between the user and the hardware. The interface enables a user to utilise hardware resources very efficiently. Operating system (OS) is an organised collection or intergrated set of specialised programs that controls the overall operations of a computer. It is a program that must be on any computer for proper booting.
Functions of Operating System
Operating system is a large and complex software consisting of several components. It is responsible for managing all the resources attached to a computer system.
Following functions are provided by an operating system to the convenience of users
Process Management
‘A Process is a program under execution'. It is the task which is currently being executed by the processor (CPU). The operating system handles the creation and deletion of processes and also manages the scheduling and synchronisation of process. Process management is the important part of an operating system which enables the activities of planning, monitoring and performance of a process.
Memory Management
Memory management of an operating system takes care of allocation and de-allocation of main memory to various processes. Managing the primary memory, sharing and minimising memory access time are the basic goals of the memory management. It also keeps track of memory usage. The performance of memory management is crucial for the performance of entire system.
File Management
File management module of operating system manages files held on various storage devices as well as transfers file from one storage device to another. The file management includes creating and deleting both files and directories, allocating space for files, keeping back-up, securing, easy access to files.
Input/Output Management
The Input/Output management module of the OS coordinates and assigns different input and output devices, namely terminals, printers, disk drives, tape drives, etc. Input/Output Management controls all I/O devices, keeps track of I/O requests, issues commands to these devices and takes measures which would ensure that data is transmitted efficiently and correctly to and from I/O devices.
Types of Operating System
The operating systems are classified as
Batch Processing Operating System
In batch processing operating system, a number of jobs are put together and executed as a group. This operating system is responsible for scheduling the jobs according to priority and the resource required. It is the type of OS which does not interact with the computer directly, e.g. Unix.
Single User Operating System
It is a type of operating system which allows only one user at a time. Operating system for personal computer (PC) is single user OS. They are designed to manage one task at a time. e.g. MS-DOS, Windows 9X.
Multi User Operating System
This OS allows multiple users to access a computer system concurrently. It is used in computer networks that allows same data and applications to be accessed by multiple users at the same time. e.g. VMS, etc.
Multi-Tasking Operating System
In multi-tasking operating system, more than one processes can be executed concurrently. It also allows the user to switch between the running applications. e.g. Linux, Unix, Windows 95.
Multi-tasking OS can be classified as follow
(a) Preemptive Multi-tasking OS It is a type of multi-tasking that allows computer programs to share operating system and underlying harware resources. It divides its overall operating, computing time between processes, and the switching of resources between different processes occurs through predefined criteria, e.g. OS/2, Window 95/NT, etc.
(b) Cooperative Multi-Tasking OS It is the simplest form of multi-tasking. In it, each program can control the CPU for as long as it need it. If a program is not using the CPU, however it can allow another program to use it temporarily, e.g. Mac OS, MS-Windows 3-X, etc
Time Sharing Operating System
In time sharing OS, a small amount of time is allocated for the processing simultanously. The time sharing operating system allows multiple programs to simultaneously share the computer resources. It provides to each process to be run on. e.g. Mac OS,
Real Time Operating Sytem (RTOS)
The main objective of real time operating systems is their quick and predictable response to events than any other operating system. Real time operating systems are designed to respond to an event within a predetermined time. It must have preemptive kernels to execute a program. They are often used in applications such as flight reservation system, military applications, etc. These types of operating system increase the availability and reliability of the system, e.g. Lynx OS, etc.
There are two types of real time operating system
(a) Hard Real Time OS It is referred to as an operating system that can absolutely guarantee a maximum time for the operations, it performs.
(b) Soft Real Time OS It is referred to as an operating system that cannot absolutely guarantee a maximum time for the operations, it performs.
User Interface
An operating system provides an interface between the computer user and the hardware. The user interface is one of the most important parts of any operating system because it allows users to easily access and communicate with the applications and the hardware.
The user can interact with the computer by using mainly two kinds of interfaces
Graphical User Interface (GUI)
It is a computer program that enables a person to communicate with a computer through the use of symbols, visual metaphors and pointing devices. It is best known for its implementation in Apple products.
The first graphical user interface was designed by Xerox Corporation in 1970s. GUIs can be found in hand held devices such as MP3 players, portable media players, gaming devices, etc.
Character User Interface (CUD
It is also known as Command Line Interface (CLI). CUI is a mechanism of interacting with a computer system or software by typing commands to perform specific tasks. Programs with character user interface are generally easier to automate via scripting. CUI only uses text types one after another just as commands used in MS-DOS.
Booting It is a boot strapping process which starts the operating system when a computer is switched ON and the operating system gets loaded from hard disk to main memory. There are two types of booting · Cold Booting When a computer is turned ON after it has been completely shut down. · Warm Booting When a computer is restarted by pressing the combination of Ctrl + Alt + Del Keys or by restarted button, |
Some Important Operating System
Some popular operating systems are as follows
developed by Sun Microsystems. The first version of Sun Microsystems was published in 1992 and coined as SunOS.
Mobile Operating System
This OS operates on Smartphones, Tablets and Digital Mobile devices. It controls mobile devices and its design supports wireless communication and different types of mobile applications. It has built-in support for mobile multimedia formats
Some popular mobile operating systems are as follows
(i) Android It is a mobile OS developed by Google, which is based on Linux Kernel. It is basically designed for touch screen mobile devices like Tablets, Smartphones, etc. Now-a-days, it is most common as used in mobile phones. The latest version of Android is Nougat which was released on 22 August, 2016.
(ii) Symbian It is the OS developed and sold by Symbian Ltd. It is an open source mobile OS designed for Smartphones. It has been used by many major handset manufacturers including Motorola, Nokia, Samsung, Sony, etc. The latest version of Symbian is Nokia Belle which was released in October 2012.
(iii) IOS It is the popular mobile operating system developed by Apple Incorporation. This operating system is commonly used in Apple iPhone, iPod Touch, iPad, etc. The latest version of iOS is iOS 10.0.2 which was released on 23th September 2016
(iv) BlackBerry it is the most secure operating system used in leading Smartphones developed by BlackBerry Company. It also supports WAP 1.2. The latest version of Blackberry is BlackBerry OS 10.3.3 which was released in 2016.
MS-DOS (Microsoft - Disk Operating System)
The DOS OS was developed by Microsoft in 1980 for microcomputers. MS-DOS was the first operating system that run on PC developed by IBM Corporation in 1981. DOS is a single user Operating system. It is only operating system, which can be loaded in the main memory of the computer using a single disk.
Structure of DOS
There are four essential programs associated with the control of computer and the way it interacts with them.
(a) The Boot Record It includes loading the operating system into main memory. It is the main program of MS-DOS.
(b) The Basic Input/Output System (BIOS. sys) it provides an interface between the hardware and programs.
(c) The MSDOS. Sys Program It is a collection of program routines and data tables that provides high level programs such as application programs.
(d) The Command.com Program it provides a standard set of commands that gives users access to file management, configuration and miscellaneous functions.
Configuration of DOS
Config. Sys, Autoexec, bat provide the environment to computer to set commands.
(a) CONFIG.sys It adjusts the system according to commands.
(b) Auto Exec.bat when the system is powered on, this file executes in automatically command line.
Important Extensions and their Meaning
Extensions |
Meaning |
.exe |
Executable files |
.corn |
Command files |
.bat |
Batch files |
.doc |
Document files |
.txt |
Text files |
.prg |
Program files |
.ovr |
Over lays |
.sys |
System files |
Types of DOS Commands
There are two kinds of DOS command, Internal and External.
(a) Internal Commands These commands are automatically loaded into main memory when the booting process gets completed, e.g. DATE, TIME, VER, VOL, DIR, COPY, etc.
(b) External Commands These commands require external files to be loaded in the computer to run. e.g. Checking disk, comparing disk, formatting, etc.
Important Commands and their Uses
Commands |
Description |
CALL |
Call one batch program from another |
CD |
Change Directory-move to a specific folder |
CLS |
Clear the screen |
CHKDSk |
Check the hard drive running position |
COPY |
Copy one or more files to another location |
DATE |
Display or set the date |
DEL |
Delete one or more files |
DIR |
Display a list of files and folders |
ERASE |
Delete one or more files |
EDIT |
View and edit files |
EXIT |
Quit the current script/routine and set an error level |
FORMAT |
To erase and prepare and disk drive |
IF |
Conditionally perform a command |
MD |
Create new folders |
MOVE |
Move files from one folder to another |
PATH |
Display or set a search path for executable files |
|
Prints data to a printer port |
PROMPT |
Change the command prompt |
REN |
Rename a file or directory |
RD |
Remove an empty directory |
SORT |
Sort the input and displays the output to the screen |
START |
Start a program, command or batch file |
TIME |
Display or set the system time |
TYPE |
Display the contents of a text file |
VER |
Display version information f |
XCOPY |
Copy multiple files, directories, or drives ; from one location to another |
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