What Is DOS? Disk Operating System Explained (All You Need to Know)

Daisy updated on Jan 11, 2024 | Home > Knowledge Center

If you've ever wondered about DOS, then this article will help you understand what it is.

Operating systems are the key to any computer. Without these operating systems, computers are just machines that take up electricity. In order to do anything with computers, an operating system is needed as a conjunction for hardware, software, and human interaction.

One such operating system used to be DOS, commonly known as MS-DOS. It was all the buzz back in the 80s and early 90s when UI wasn't a thing. But, more than 40 years later, DOS is rarely heard of. So, what exactly was or is it? And, how was it different from the operating systems we use today? Let's find out.

What Is DOS?

DOS or MS-DOS is the shortened name for Microsoft Disk Operating System. Usually seen as words on a black screen, MS-DOS looked a lot like your common command prompt on the computer today. As you can guess, the operating system requires written commands to operate.

However, DOS wasn't always "MS-DOS," as it started out in the IBM computers of the early days. Later, the rebranded Microsoft version became the primary DOS we know today. However, earlier on, it was licensed as PC DOS 1.0, owned and patented by Microsoft.

Later on, it went to Microsoft and became the primary operating system offered by the software giant after 1988—particularly after the release of the x86 framework. However, all MS-DOS production stopped in 2000, marketing the end of a remarkable 29-year run.

However, this was the very operating system that catapulted Microsoft into becoming the software-development giant we know today. But, before the introduction of GUI, DOS went through many upgrades, such as:

  • MS-DOS 1, 2, 3
  • MS-DOS 4.0, 6, and 7 – the secondary upgrades
  • MS-DOS 7, 8 as a part of Windows 95, 98, etc.

But by Windows 2000, Microsoft had ceased working on all the upgrades as command-based operating systems were running out of fuel. Besides that, Microsoft's own GUI operating system (Windows) had seen immense success. This marked the end of DOS' continued reign and development of over 30-32 years.

How Does DOS Work?

The basics of DOS are as simple as it was to use it. Granted, modern OS users may not have a clue about it, but it requires only a specific and exclusive set of things to work correctly. But how exactly did it work?

It used ROM (Read-Only Memory) to read the MBR (Master Boot Record). Then it passed the control through bootstrap leader to MBR>. However, the boot record laded the DOS into memory, allowing it to control it entirely. Then, an array of operations happen, such as:

  • The computer transferred data stored on disks, such as hard disk drives (known as magnetic drives at the time)
  • Transferring data as output to external devices, such as printers, screens, secondary screens, etc.
  • DOS' in-built file management, much akin to today's much advanced Windows explorer, reads and writes files and commands on storage devices
  • The computer works through various APIS such as IO (input/output), memory management, and opening a program or closing it
  • It also handles the input provided by the user, as it's the primary function of human-computer interaction

These are some of the main ways DOS works. However, it works through two main features: CLI (command-line interface) and management. The former handles keyboard input, as DOS didn't have GUI to take mouse input. Whereas the latter handles managing files, OS, system memory, etc.

Advantages and Disadvantages of DOS

The question of advantages or disadvantages is asked of something relevant and used frequently. DOS is an outdated technology employed only in a few cases today. So, it does make it relevant to various disadvantages and advantages, which are as follows:


  • Direct contact with hardware because of its BIOS-like access to hardware installed in a PC
  • Very light in size makes it very quick to launch, more than most present-day operating systems
  • A quick alternative to work around common operations without the confines of modern operating systems, such as formatting a disk
  • Requires a lot less storage space


  • Severely outdated in 2022
  • They struggle with using ram, as the limitations are around 640MB
  • Not easy to operate, as each command requires a typed-in directive

While you can still find DOS in computers in some capacity, it's still outdated a little bit. And, there are seldom any uses for it besides troubleshooting, formatting, etc.


If you got any more questions, then here are some frequently asked ones:

1. What was DOS used for?

The DOS was used for transferring data to the disk using typed-in command lines in a computer. It allowed the user to operate various devices connected to the computer, such as printers, video screens, and other external devices.

2. Are DOS commands still used?

While DOS is severely outdated, it's still used in some capacity. In every Windows-based computer, there's a PowerShell or command prompt today. It allows them to use the same commands as DOS to work around troubles or solve issues with hardware.

3. Are the Command Prompt and MS-DOS the same thing?

While they do share the same attributes, they are a bit different. As opposed to MS-DOS, a command prompt is GUI-based, so it accepts mouse input.

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Updated by Daisy

Daisy is the Senior editor of the writing team for EaseUS. She has been working at EaseUS for over ten years, starting as a technical writer and moving on to being a team leader of the content group. As a professional author for over ten years, she writes a lot to help people overcome their tech troubles.

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