WHAT IS BOOTING

3. What is BOOTing ?
When the computer is switched on, the firmware program in Read Only Memory(ROM) also called Basic Input-Output System(BIOS) reads programs and data i.e. Operating System and loads it into memory (RAM). This process is known Bootstrapping(Booting). The OS once loaded takes control of the computer, handles user interaction and executes application programs.

4. Booting Sequence
During Booting process, computer loads the operating system into its memory. DOS booting involves reading following files into memory namely IO.SYS, MSDOS.SYS, and COMMAND COM. The Basic Input/Output Program (IO.SYS): This program provides interface between the hardware devices and software of the system. It takes care of the keyboard input, character output to monitor, output to printer and time of the day. The File and Disk Manager Program (MSDOS.SYS) : It contains the file management and thedisk buffering management capabilities. It keeps track of all the disk access of an application program and remains permanently in memory. The Command Processor (COMMAND.COM) : It is also called command interpreter. It is the program that displays the system prompt and handles user interface by executing the command typed in by the user using keyboard.

5. The CONFIG.SYS file :
This file contains reference to device drivers which are loaded when OS takes control of the computer. This device drivers are required for configuring operating system for running special devices.

6. The AUTOEXEC.BAT file :
This is a special batch program that is automatically executed when the system is started. It can be used to define keys, define the path that MS-DOS uses to find files, display messages on the screen etc. It will be executed only if it exists in the root directory or the diskette from which the system is loaded. Each time the system is started, MS-DOS executes the commands stored in AUTOEXEC.BAT file. One can run it without restarting the system by typing AUTOEXEC at the command prompt.

7. Disk/Drives :
The user can store data or programs on secondary storage devices called Hard disk or Floppy disk. Physically disks store data by recording any pattern of magnetic changes on using a tiny read-write head that moves over the surface. Disk is divided into sectors and tracks. The first two characters of alphabet (a: or b:) are reserved for Floppy disks, Hard disks are identified by characters (c:) or (d:), the next character inthe sequence is assigned to Compact Disk (CD-ROM) drive further the network drives connected to the system are assigned the remaining characters.

8. Directory :
It is a special type of file that contains other files. The relation between files, directories and disk is very similar to the relation between papers, filing folders and filing cabinets. The hierarchy in which directories are kept is called a tree structure.

9. Definition of a file :
File Names Information or data is stored is stored on a disk in the form of a file. When storing any file, it must be given a unique name, which can be used for subsequent identification/reference. Filenames should not be longer than 8 characters, can have an extension which should not be longer than 3 characters. Following characters are valid in a filename : A to Z , a to z, 0 to 9,!,@#$%&(){}_-\’. Different files are identified by their extensions. File which have extension EXE, COM, BAT are executable files. They can be executed by just typing their name at the command prompt. Extensions TXT, DOC, BAK, BAS, C represent text file, Documentation (MS-Word) file, Backup file, basic program file, C program file respectively.

10. Wildcards
DefinitionTo retrieve and identify file, we can use its specific name or may refer to it with the help of wildcards which can even refer to entire group of files. There are two wild card symbols : asterisk (*) indicates that any or a one valid character can occupy that position or of the remaining positions in the filename or extension, Question mark (?) means that any one valid character can occupy that position.

11. Warm and COLD Reboot
Switching on of the computer from Power off and loading the operating system is called "Cold Boot". This generally starts with memory test and chips initialization.
There may be case when the computer is already on or has hanged up and we want to reboot the system. This is known as "Warm Boot" and is done by pressing ctrl+alt+del keys simultaneously or just by pressing"Reset" button on the system.

12. Types of DOS commands
Any instruction given to the computer to perform a specific task is called command. The DOS has several commands, each for a particular task and these are stored in DOS directory on the disk. The commands areof two types : (a)Internal Commands : These are in builtcommands of MS-DOS i.e. these are stored in Command interpreter file (COMMAND.COM). These commands reside in the memory as long as the machine is at he system prompt(C:\>) level. To use these commands no extra /external file is required. E.g.DATE, TIME, DIR, VER etc. (b) External commands : These are separate program (.com) files that reside in DOS directory and when executed behave like commands. An external command has predefined syntax. for e.g. HELP, DOSKEY, BACKUP, RESTORE, FORMAT etc.

13. BASIC DOS COMMANDS :
a) Directory Commands :
DIR : To list all or specific files of any directory on a specified disk.
MD : To make directory or subdirectory on a specified disk/drive.

CD or CHDIR : Change DOS current working directory tospecified directory on specified disk or to check for the current directory on the specified or default drive.

RMDIR or RD : Removes a specified sub-directory only when it is empty. This command cannot remove root directory (C:\) or current working directory.

TREE : Displays all of the directory paths found on the specified drive.

PATH : Sets a sequential search path for the executables files, if the same are not available in the current directory.

SUBST : Substitutes a string alias for the pathname and creates a virtual drive.

b) File Management Commands :
COPY : Copies one or more files from source disk/driveto the specified disk/drive.XCOPY : Copies files and directories, including lower-level directories if they exists.

DEL : Removes specified files from specified disk/drive.

REN : Changes the name of a file(Renaming).
ATTRIB : Sets or shows file attributes (read, write, hidden, Archive).

BACKUP : Stores or back up one or more files/directories from source disk/drive to other destination disk/drive.

RESTORE : Restores files that were backed up using BACKUP command.

EDIT : Provides a full screen editor to create or edit a text file.

FORMAT : Formats a disk/drive for data storage and use

c) General Commands :
TIME : sets or displays the system time.
DATE : Sets or displays system date.
TYPE : Displays the contents of at the specified file.
PROMPT : Customizes the DOS command prompt.
If a users requires help on any DOS commands he/she may type help and command name at the command prompt.