DOS Introduction -1

What is MS-DOS Operating System

MS-DOS stands for Microsoft Disk Operating System & it is developed by Microsoft Corporation. It provides a interface b/w computer hardware & software programs. 

DOS is a 16 bit operating system that means it can save & process 16 bit of data at a single time. It is a single user & single tasking operating system. It is command line operating system which means you have to use commands in command line interface to obtain desired result.

History of DOS:-

There are available in 2 version.

1. MS-DOS                                         2. PC-DOS 

In 1979 a small company owned by Seattle Computer Products written by Tim Partson and its OS name was ODOS. IBM purchased ODOS and then took the help of Microsoft to develop a new product. This product was announced with IBM-PC in 1981 with name as MS – DOS version 1.0.

 In 1983 MS-DOS version 2.0 appeared with many advances in design. It was made for PC announced by IBM. It introduced fixed formatting, backup utilities and filter commands for redirection of input/output operations.

                           MS-DOS operating system is a non-graphical command line O.S. derived from 86-DOS that was created for IBM compatible computers.

Version of DOS with Their features :

• 1981 : DOS 1.1 : Renamed version of QDOS(quick and Dirty Operating System). Which was purchased by Microsoft from Seattle Computer Products. 

• 1982 : DOS 1.25 : Supported use of double sided Disks.

• 1983 : DOS 2.0 : Supported IBM’s 10 MB hard disk and some other additional features.

• 1984 : DOS 3.0 : Supported for high density floppy disk(5.25”).

• 1987 : DOS 3.3 : Supported for high density 3.5” floppy disk. Allowed partition on hard disk.

• 1991 : DOS 5.0 : Much upgraded version. Included text editor and Improved BASIC interpreter etc.

• 1993 : DOS 6.0 : Added a disk compression utility, antivirus program and disk derangement.

• 1995 : DOS 7.0 : This version is part of MS Windows 95. Supports long file names but remove a large number of utilities.

• 1997 : DOS 7.1 : Support for FAT 32 hard disks and is part of later of MS Windows 95.

• 2000 : DOS 8.0 : It is included in windows ME. It is the last version of MS-DOS.

MS-DOS Parts :

The DOS Operating system is a set of programs which are stored on some secondary storage device normally floppy disk. It is then loaded into RAM when required. The DOS software is divided into three parts stored in three different files on a disk. The disk which contains these three files is called a bootable Disk.

The three files loaded on this disk are :-

1. IO.SYS

2. MS-DOS.SYS

3. COMMAND.COM

Ø The IO.SYS file contains the device drivers for the standard devices such as keyboard disk, floppy, printer and monitor are present. All these devices drivers are often called BIOS (Basic Input Output System).

Ø The MS-DOS.SYS file is also called DOS Kernel. It contains all the modules for process management. These Modules are written in machine independent manner so that they could be easily ported.

                                               The DOS Kernel provides the link between the BIOS and User’s application program.

    The DOS Kernel performs 4 basic important functions:

Memory Management, Process Management, File Management, Provides an Interface.

Ø MS-DOS provides a command line interface (CLI). The MS-DOS shell is known as COMMAND.COM.

File in DOS:

A file is a organized collection of data stored on storage device such as magnetic tape disk. The file is used to store only one kind of information.

                              Different types of files are used in computer such as text file, batch file, data base file etc.

Some file Extensions and their meanings:-

·        .C – C source program file.

·        .ftn – Fortran source program file.

·        .pas – Pascal source program file.

·        .obj – Object file.

·        .exe – Executable file.

·        .bat – Batch file.

·        .bak – Backup file.

·        .dat – Data file

·        .wav -  Microsoft windows sound file.

•     .txt - Notepad file
•      .docx - Word file

Difference b/w DOS & Windows

DOS	Windows
It is Command line.	It is GUI (Graphics User Interface).
It is difficult to learn.	It is easy to learn.
It supports single user.	It support multiple user.
It supports single tasking.	It supports multitasking.
It only supports keyboard.	It supports keyboard & mouse.
It does not provide networking.	It provides networking.

 

File Management

·        Managing file system to enable user to keep their data safely & correctly is an important function of operating system.

·        Managing file system by operating system is called file management.

·        File management provides tools for these related activities.

§  Creating new file for storing data.

§  Updating

§  Sharing

§  Securing data through password & encryption.

§  Recovery in case of system file.

   What is Command?

             A command is a set of instructions used to perform a specific work.

       e.g. -  <md Ram> , <cd Ram> etc.

PROMPT:-  This command is used to change the MS-DOS command prompt. The user can on/off the prompt by using this command.

DIR :-  DIR stands for Directory listing. It is used to display all the files & sub directory stored in the directory (Folder) along with their size in bytes. 

                 Directory is further classified in to three parts :

·        Current Directory

·        Sub Directory

·        Root Directory               

                      

Like as :  

              C:\dir D: (Enter) [It will display list of directories & files in drive D]