• Developed by Microsoft in 1980 and first operating system for IBM computers in 1981.
• It is a non-graphical command line operating system.
• It is a single user operating system.
• DOS can be loaded in main memory of the computer using a single disk.
• It is based on character user interface. Communication done by using character between a computer and a user.
• Here one has to key in the commands on the prompt. Prompt is a place where commands are issued, like C:\ or C:\windows\>

Types of MS-DOS Commands

• Internal Commands – are those commands which are automatically loaded into main memory when the booting process gets completed, e.g., DATA, TIME, VER, VOL, DIR, COPY, CLS etc.
• External Commands – are those commands requires external files to be loaded in the computer to run, e.g., Checking Disk, Comparing Disk, Formatting etc.

Programs that controls and interact with Computers

• Boot record – It is the main program of MS-DOS which includes loading the operating system into main memory.
• Basic Input/Output System (BIOS.sys) – Provides an interface between the hardware and programs.
• The MS-DOS.sys program – It is a collection of program routines and data tables that provides high level programs such as application programs.
• The Command.com program – Provides a standard set of commands that gives users access to file management, configuration and miscellaneous functions.
• Config.sys – Adjust the system according to commands.
• Autoexec.bat – When the system is power ON, this file execute in automatically command line.