DOS - Class 9 PDF Download

DOS

DOS stands for "Disk Operating System". It is a program, which acts as an interface between the user and the computer hardware. DOS allows manipulation of files and programs by interpreting and processing the commands typed by the user.

The DOS software is automatically copied from a floppy disk or the hard drive into the computer's memory whenever the computer is turned on or booted (made a computer ready to be used by putting in its instructions). DOS is not an application package that you start and then exit when done. This is an operating system runs from the moment you turn the computer on until you turn the machine off. The major tasks the DOS must carry out are:

1. To control input and output devices.

2. To enable user to load and execute program.

3. To maintain an orderly system of data in the disk.

Types of DOS Commands

There are two types of DOS Commands:

1. Internal Commands

2. External Commands

Internal Commands

Internal commands are a part of the DOS program COMMAND.COM and are loaded into memory when you boot your computer. These commands are needed to be used most often, although they are not seen when we display the disk directory of filenames on our screen. Some internal DOS commands are:

CLS

This command is used to clear the screen of a monitor.

Syntax: CLS

DIR

This command is used to display a list of current directly files and subdirectories.

Syntax: DIR[drive:][path][filename][/p][1w]

CHDIR (CD)

This command is used to display the current directory or changes in the current (default) directory.

Syntax: CD[drive:][path]

DEL

This command is used to deletes one or more specified files from the disk.

Syntax: DEL[drive][path]file name[/p]

e.g. DEL Aslam.Doc

External Commands

External Commands are programs, which exist on the DOS disk or the hard disk. They are run when you type their name on the command line. For example, typing FORMAT at the DOS prompt results in a program called FORMAT.COM being executed.

External Commands are not frequently used and DOS saves valuable memory space by loading them only when required. Some the external commands are:

CHKDSK

This command is used to checks the validity of a disk and reports the total space, used and free space on the selected disk.

Syntax: CHKDSK [drive][path][/f][/v]

SYS

This command is used to create a bootable drive and installs the main DOS files.

Syntax: SYS[drive:][path]drive2:

e.g. SYS A:

TREE

This command is used to display directory structure.

Syntax: TREE[drive:][path][/f][/a]

XCOPY

This commands is used to copy files (except hidden and system files) and directories, including sub directories.

Syntax: XCOPY source [destination][/a|/m][/d:date][/p][/s][/e][/v][/w]

e.g. XCOPY *.*A:

DELTREE

This command is used to delete all files and sub directories in a directory.

Syntax: DELTREE[/Y][pathname]