1. Introduction To MS-DOS
An operating system is an interface between the hardware and the software and the user to communicate with each other. MS-DOS stands for Microsoft Disk Operating System, is one of the powerful operating systems. DOS basically works as an interpreter to provide an interface between hardware and programs/software. It also controls the overall operations of the computer system and the flow of data etc. as other operating systems do. MS DOS is a single user operating system. It uses a command line interface i.e. to perform specific tasks, you need to type command. Basically command line interface Is a mechanism for interfacing with the computer operating system by typing commands only.
Introduction To MS-DOS

2. The DOS operating system is a program which is loaded in the computer memory normally called as floppy disk. The architecture of MS-DOS consists of three main files. The files are also known as system files. These files are (a) IO.SYS (b) MS-DOS © COMMAND.COM
Structure Of MS-DOS

3. IO.SYS (Input Output System) :-
This is the system file which manages the input output attached to the computer. Basically this system file is divided into two portions , first portion of IO.SYS controls the operations of input output devices and second portion which is also known as SYS.INI loads the MSDOS.SYS from the hard disk to main memory and stays in the memory till the power is switched on.

4. b) MSDOS. :- MS-DOS is also known as DOS Kernel
b) MSDOS. :- MS-DOS is also known as DOS Kernel. It acts like a policeman who controls the various activities of the system. Basically it acts as a link between the BIOS (Basic Input- Output Services) and the application programs being run by the computer user. It contains all the modules for process management which are written in machine language so that they could be easily ported. It performs four basic functions. (1) Process Control :- MS-DOS is responsible for loading the program from the disk into memory requested by the user and also recovers system files when unwanted termination occurs. (2) Memory Management :- It allocates the memory to different application programs and also does file allocation if demanded.

5. (3) File Management :- File management like reading, writing, renaming, copying and removing the files is done by this command. (4) Application Program Interface :- It provides an interface between the user and the hardware. Using this, if programmer has knowledge of hardware, he/she can directly write programs.

6. c ) Command. Com :- The command
c ) Command.Com :- The command.com is the main operating system program that acts as an interface between the user and the system. The commands we give to the system are received by command.com and the translated into the language understandable by the system. The MS-DOS shell is known as command.com which provides a command line interface. Command.com has two portions as :- (a) Resident Portion :- DOS is first loaded into the Resident Portion of memory and stays there all the time from the switching on till switch off the computer. It can only be interrupted by Ctrl+C. It contains code required to reload the transient portion of Command.com.

7. (b). Transient Portion :- It is the temporary portion of the command
(b) Transient Portion :- It is the temporary portion of the command.com can be erased if memory is required by application program due to less or shortage of memory. The Transient portion displays the DOS prompt like A:\> , B:\> and C:\> and it reads commands from keyboard and executes those commands.

8. 1. BOOTSTRAP:-The term boot is short for bootstrap
1. BOOTSTRAP:-The term boot is short for bootstrap. With the power off , a computer is a dead hunk of silicon, steel, and wires. During the boot process , it has to wake up, find all of its peripherals , and configure itself to run software . It takes some doing to make all of this happen .
SOME DOS RELATED TERMS

9. 2. THE DOS BOOT PROCESS:- When DOS was first used by IBM for its personal computers , the OS system was called PC-DOS , and IBM gave certain names to the files that made them sound like IBM-specific files. But as soon as clone makers (e.g. Compaq, Dell) starting making IBM compatible clone computers, Microsoft released a clone Version called MS-DOS, and renamed some of those files. Now MS-DOS is much more widely used than PC-DOS and MS-DOS names are more common.

10. Booting When we start our Computer then there is an operation which is performed automatically by the Computer which is also called as Booting. In the Booting, System will check all the hardware’s and Software’s those are installed or Attached with the System and this will also load all the Files those are needed for running a system. In the Booting Process all the Files those are Stored into the ROM Chip will also be Loaded for Running the System.

11. In the Booting Process the System will read all the information from the Files those are Stored into the ROM Chip and the ROM chip will read all the instructions those are Stored into these Files. After the Booting of the System this will automatically display all the information on the System. The Instructions those are necessary to Start the System will be read at the Time of Booting.

12. There are mainly two types of Booting: (1) Cold Booting (Switch Booting) (2) Hot Booting (Warm booting)(Resetting) 1. Cold Booting: When the PC is switched on, it loads the Bootable DOS program from the disk to the memory. This type of Booting of the computer is a slow process. It can be done only from the ON/OFF switch button on the cabinet and so called as Switch Booting.

13. 2. Hot Booting (warm booting) This is also called Warm Booting
2. Hot Booting (warm booting) This is also called Warm Booting. It is faster than cold booting. If computer “Hangs” or halts or crashes due to some reason, it may be necessary to reset it either by pressing Reset Button from the cabinet or by pressing Ctrl+Alt+Del keys from the keyboard simultaneously. The computer restarts and the booting of this type from Keyboard keys or Reset button is called Hot Booting. It is also called Resetting or Reinitialization.

14. Pipes and Redirection A number of Dos commands send output to the screen and/or require input from the user. Redirection is a mechanism whereby the output of a command can be fed either to some other device (e.g. a printer or file) or to another program or command. There are four redirection functions: (1) > Redirect output (2) >> Append (3) < Redirect input (4) | Pipe

15. (1) > (Redirect output) Redirects a command's output from the "standard output device" (usually the monitor) to another device (e.g. printer) or a file. Syntax: To redirect output to a device: Command > Device To redirect output to a file: Command > Filename

16. (2) >> (Append) Appends the output from a command to the specified file. Syntax: Command >> Filename (3) < (Redirect input) Directs input to a command from a source other than the default (the default source usually being the keyboard). Command < Datasource

17. | (Pipe)
The "pipe" redirects the output of a program or command to a second program or command.
Syntax:
Command1 | Command2

18. What is Batch File
A batch file is a file containing a series of commands that the operating system will carry out for you, one at a time. A batch file is a collection of DOS commands. MS-DOS batch files consist of the normal operating system commands (e.g. DIR, DEL, COPY and MKDIR) together with some extra commands such as IF, FOR, GOTO, SHIFT and PAUSE that provide conditional control of execution and enable PARAMETERS to be passed so that the same batch file can be used in many different contexts.

19. A batch file, such as WP. BAT, ends with the letters. BAT
A batch file, such as WP.BAT, ends with the letters .BAT. When the user types in the name of a batch file and presses Enter at the DOS prompt, the commands in that batch file are performed one at a time-with no additional instructions from the user. For example, if the user typed WP and pressed Enter, WordPerfect (a popular word processing program) would start. A user can create a batch file to perform any routine task. For example, a batch file could be created to prepare a disk for use (a process called formatting). Because the commands are in a batch file, the user doesn't have to type them herself, or even remember what they are-all the user would have to do is type the name of this batch file to format a disk.

20. The most important batch file is the AUTOEXEC. BAT
The most important batch file is the AUTOEXEC.BAT. This file contains commands that are performed automatically each time the PC is turned on or restarted. Typical AUTOEXEC BAT commands include those which change the system prompt, display the current date and time, and set the directories in which DOS looks for files. Other than the internal and external DOS commands the batch file has their own commands. Some commonly used batch file commands are: 1. REM (Remark)- used for comments 2. PAUSE- to pause the execution of batch file and waits until user press a key

21. 3. ECHO- to on/off the text display on the screen 4
3. ECHO- to on/off the text display on the screen 4. CALL- calls specified batch file, execute it and returns to the main file. Example of Batch File: C:\>EDIT SAT.BAT type the following in DOS editor: CLS DATE TIME VER VOL LABEL D: Press ctrl+z to save the file