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Table of contents
What is MS DOS Operating System?
How does a Disk Operating System Work?
Features of DOS Operating System
Command Line Interface
File Management
Memory Management
Batch Files
Boot Process
Types of MS-DOS Commands
1. External commands
2. Internal commands 
Benefits of a MS DOS Operating System
Limitations of MS DOS
How to open MS-DOS in windows?
MS-DOS file and file types:
DOS vs. Unix
History of DOS
Impact of DOS on modern systems
Frequently Asked Questions
What are the Different Versions of MS-DOS?
How did DOS manage memory on early personal computers?
What was the role of command prompt in DOS, and how did it differ from GUI?
What is the purpose of the DOS operating system?
Last Updated: Mar 27, 2024

MS-DOS Operating System

Author Abhay Rathi
0 upvote
Create a resume that lands you SDE interviews at MAANG
Anubhav Sinha
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12 Jun, 2024 @ 01:30 PM


Hey Ninjas! You must have wondered what the initial phase of the operating system must have looked and worked like. 

MS-DOS was used in the past because it was one of the earliest operating systems for personal computers. It helped people install and run programs from a hard disk, manage files, and control their computers. It has mostly become outdated now, but still has some uses for specific tasks on older machines and in certain situations.

In this article, we will explore the DOS OS in depth. We will look at DOS operating system limitations, commands and architecture.

dos operating system

What is MS DOS Operating System?

MS-DOS, short for Microsoft Disk Operating System, was a foundational operating system developed by Microsoft. It gained prominence in the 1980s and early 1990s, serving as the primary operating system for IBM PC-compatible computers. MS-DOS operated through a command-line interface, where users entered text commands to perform tasks. 

It played a crucial role in the early personal computer era, providing essential functions for running software and managing files on early PCs. Over time, graphical user interfaces like Windows gradually replaced MS-DOS, but its historical significance remains in the evolution of operating systems.

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How does a Disk Operating System Work?

MS-DOS works like a command interpreter. Let us understand the working of the DOS operating system in detail.

  • Booting: When you start your computer, MS-DOS is one of the first things that gets loaded into the computer's memory when we start the computer. It co-ordinates between the following steps.
  • Command Line Interface: MS-DOS doesn't have a graphical user interface like modern computer systems that we have now. Instead, it has a command line where we type in the commands using the keyboard. These commands are like instructions given to the computer to perform a particular task.
  • Execution of Command: When the user presses the ‘Enter’ key after typing the command. MS-DOS reads the command and understand the task to be done that might include copying files, deleting folders, or running programs.
  • Interacting with Hardware: MS-DOS interacts with the hardware parts and tells them what to do based on the commands given.
  • Memory Management: MS-DOS also plays a key role in managing the memory of the computer.
  • File Management: MS-DOS helps users to create, delete, copy, and move files and folders on the computer's storage.
  • Task Switching: MS-DOS is used  to switch between different programs running on the computer thus allowing the user to do multitasking.
  • Shutting Down: MS-DOS ensures that all necessary processes are closed properly before turning off the computer.

Also see, Difference Between Bit and Byte

Features of DOS Operating System

Below are the features of the MS-DOS

Command Line Interface

MS-DOS' command-line interface lets users interact with the OS. The user executes commands by typing them into a text-based interface. 

For example, to list the contents of a directory, a user could type "DIR" and press enter. Other common commands include "COPY", "DEL", and "FORMAT".

File Management

MS-DOS included a simple yet effective file management system based on the FAT file system. Users could use commands like "COPY" and "RENAME" to create, delete, copy, move, and rename files. Subdirectories were also supported by MS-DOS, allowing users to organize their files into folders.

Also read - File management in operating system

Memory Management

MS-DOS had limited memory management capabilities. It did allow users to manage conventional memory or memory less than 640 KB. 

Users could use the "MEM" command to see how much free and used memory they had. Users could use various memory managers to optimize memory usage.

Batch Files

Batch files were scripts that enabled users to automate repetitive tasks or run commands sequentially. Batch files were created with simple text editors and executed the same way as any other command. 

For example, a batch file is used to back up critical files and copy files to a remote location.

Boot Process

MS-DOS had a straightforward boot process. It involved reading the OS files from the disk and executing the command interpreter. Thus, allowing users to interact with the system. The boot process was initiated by turning on the computer or pressing the reset button.

Also read - features of operating system

Types of MS-DOS Commands

There are the two types of commands in MS-DOS.

  1. External Commands
  2. Internal Commands

1. External commands

  • External commands are executable files that run independently and are stored on a disc. 
  • These commands are not included in the command interpreter and must be loaded from the disk each time they are run.
  • They take longer to execute than internal commands because they need to be in memory. 
  • FORMAT, CHKDSK, and EDIT are some examples of external commands.
External Commands Use of the Command
FORMAT Format a disk or drive
CHKDSK Check a disk for errors and fix them
TREE Display the structure of a directory tree
XCOPY Copy files and directories, with more options
DISKPART Disk partitioning utility

2. Internal commands 

  • Internal commands are built into and executed directly by the command interpreter (COMMAND.COM). 
  • When the system boots up, these commands and the command interpreter are loaded into memory. 
  • They execute faster than external commands because they are already in memory. 
  • DIR, CD, MD, RD, COPY, DEL, TYPE, and VER are examples of internal commands.

There are three types of Internal commands: directory, file, and system.

  1. Directory commands (MD, RD) are used to manipulate directories. 
  2. File commands (COPY, DEL, REN, TYPE, XCOPY, ATTRIB) are used to manage the system.
  3. System commands (CHKDSK, FORMAT, LABEL, MEM) are used to manage the system.
Internal Commands Use of the Command
CLS Clear the screen
DIR Display a list of files and directories
CD or CHDIR Change the current directory
COPY Copy one or more files to another location
DEL or ERASE Delete one or more files

Benefits of a MS DOS Operating System

MS-DOS had several benefits during its prime, especially in the earlier days of personal computing. Some of its notable benefits include:

  • Simplicity and Lightweight: MS-DOS was a simple and lightweight operating system, making it well-suited for the limited computing resources of early personal computers. Its minimalistic design allowed it to run on machines with relatively low processing power and memory.
  • Compatibility: MS-DOS provided a standardized platform for software developers. Applications developed for MS-DOS could run on a wide range of compatible hardware, fostering a more consistent user experience across different computer systems.
  • Command-Line Interface (CLI): The command-line interface of MS-DOS allowed users to interact with the system through text commands. While this might seem less user-friendly compared to modern graphical interfaces, it provided experienced users with powerful control over the system.
  • Bootable from Floppy Disks: MS-DOS could be booted directly from a floppy disk, allowing users to run the operating system without installing it on a hard drive. This was particularly useful for troubleshooting, recovery, or running the system on computers with limited storage.
  • Basis for Windows OS: MS-DOS served as the foundation for Microsoft Windows operating systems. Versions of Windows up to Windows ME (Millennium Edition) retained a significant reliance on MS-DOS for various functions. Windows 95, 98, and ME operated as graphical shells running on top of MS-DOS.

Limitations of MS DOS

Some limitations of DOS operating System are:

  1. MS-DOS is a 16-bit operating system designed to run on computers with limited memory. As a result, its maximum memory limit is 640 KB. Thus, limiting the number of programs and data that can be stored and executed at any given time.
  2. It has a limited graphical user interface and is primarily command-line based. This makes it difficult for inexperienced users to use and navigate.
  3. It is not designed to be a network OS because it has limited network capabilities. This limits its applicability in a modern networked environment.
  4. It lacks security features such as user accounts. As a result, it is vulnerable to security threats like viruses.
  5. It allows only a limited number of characters in file names. Which is limited to eight characters, followed by a three-character file extension. This can cause confusion and make managing large numbers of files difficult.
  6. It was created to work with older hardware. So it had limited support for modern hardware such as USB drives and wireless networks.

How to open MS-DOS in windows?

To open MS-DOS in a windows, follow the steps as given below:

  • Go to the Windows start button in the desktop and click on it. You can also press the windows key on your keyboard.
  • Next type ‘cmd’ and press ‘Enter’. This will open the MS-DOS command line interface. 

MS-DOS file and file types:

MS-DOS operating system uses many types of files:

  1. Executable files: These files have a .exe extension and are program files that can be run directly from the command prompt.
  2. Configuration files: These files have a .cfg extension and used to configure settings for MS-DOS applications.
  3. Text files: These files have a .txt extension and contain plain text data.
  4. Batch Files: These files have a .bat extension and are text files containing a series of commands to be executed sequentially.

DOS vs. Unix

Aspect DOS Unix
Operating System Type Single-user operating system. Multi-user operating system.
User Interface Command-line interface (CLI). Command-line interface (CLI) and graphical user interface (GUI).
File System Limited file system support. Hierarchical file system with rich features.
Security Minimal security features. Robust security measures, user permissions, and access controls.
Multitasking Limited multitasking support. Advanced multitasking capabilities.
Network Functionality Basic networking capabilities. Built-in networking capabilities and protocols.

History of DOS

MS-DOS, or Microsoft Disk Operating System, emerged in 1981 as a command-line operating system developed by Microsoft for IBM's personal computers. It became a standard for IBM-compatible PCs and marked a crucial phase in the evolution of personal computing. Originally designed for simplicity, it lacked multitasking and advanced features but became the foundation for subsequent Windows operating systems.

Impact of DOS on modern systems

The legacy of MS-DOS is profound, as it laid the groundwork for modern operating systems. Its command-line interface inspired subsequent command shells, while its file system conventions influenced file organization. MS-DOS paved the way for the graphical user interfaces (GUIs) of Windows and contributed to the establishment of Microsoft as a dominant force in the software industry. Although obsolete, MS-DOS remains a crucial chapter in the history of computing, showcasing the evolution from text-based interfaces to the intuitive systems we use today.

Frequently Asked Questions

What are the Different Versions of MS-DOS?

There are various versions of MS-DOS include MS-DOS 1.0 (1981), MS-DOS 2.0, MS-DOS 3.0, MS-DOS 4.0, MS-DOS 5.0, MS-DOS 6.0, MS-DOS 6.22, and MS-DOS 7.0 (Windows 95 DOS). Each version introduced new features and improvements to the operating system.

How did DOS manage memory on early personal computers?

DOS partitioned available memory on early PC into normal memory, extended memory. Expanded memory (made with special hardware or software) and high memory.

What was the role of command prompt in DOS, and how did it differ from GUI?

In DOS, the command prompt was the primary means of interacting with the OS. Unlike GUI, which uses a graphical interface with icons and windows. Users used the prompt to conduct file management and system configuration operations. The command prompt uses a text-based interface.

What is the purpose of the DOS operating system?

The DOS Operating System manages the hardware and software of the computer. It allows users to run programs, manage files and interact with the computer with the help of a command line interface.


MS-DOS (Microsoft Disk Operating System) played a pivotal role in the history of personal computing. Its simplicity, compatibility, and command-line interface made it a foundational operating system during the formative years of the computer industry. MS-DOS not only provided a standardized platform for software development but also served as the precursor to the graphical user interfaces we use today.

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