DOS (Disk Operating System)

MS-DOS was the widely used operating system before the introduction of the Windows
operating system. Even now the MS-DOS commands are used for carrying out many jobs like
copying the files, deleting the files etc. The DOS is a set of computer programs. The main
functions of DOS are to manage files, allocate system resources according to the requirement. It
provides essential features to control hardware devices such a keyboard, screen, disk drives,
printers, modems etc. Thus, DOS is a medium through which the user and external devices
attached to the system communicate the command with the system. DOS translate
communication issued by the computer in the format that is understandable by the computer and
instruct computer to work accordingly. It is also translates the result and any error message in the
format for the user to understand.

DOS Commands

We can type all DOS commands in either upper or lower case letters. There are two basic
types of DOS commands:

Internal commands

These commands, like COPY, DEL, and TYPE, are stored in computers memory. Many
DOS commands fall into this category.

External commands

This group of commands is stored on the disk. To use them, either insert the DOS floppy
disk, or change to the directory on hard disk which contains DOS external commands. Examples
of external commands include FORMAT, DISKCOPY, and CHKDSK.
Some commands can take several forms. These separate forms are used by including
various parameters with the command. Parameters, which will be discussed with each command,
are indicate by a / mark. Here is an example of command with an attached parameter:
C:\>DIR/W
[DOS command DIR is attached with parameter W]
All DOS commands must be activated by pressing the <Enter> key after typing the
command.

Features of DOS

• Single user system
• Machine independence
• Program control
• Peripheral management
• Operating with Directories
• Managing files
• Processing commands
• Managing input and output
• Data securing
• Using Batch files
• Managing memory
• Setting up environment
• Command processing - DOS shell(a set of commands which is used to create the programs)
• Operating with Assembler.

Advantages of DOS

The DOS provides the following advantages:

• Machine independence
• More security
• User friendly environment
• More useful in commercial applications.
• Error finding and recovery is more efficient
• Facilities more graphical user interfaces.
• Easy debugging