What is DOS? Everything You Need To Know

Just mentioning DOS brings back memories of early 1980’s computing. 

Folks born more recently have most likely never seen this tech in action. While it may look obscure now, it was for its time groundbreaking technology and has played a critical role in developing today’s operating systems.

But what exactly is DOS? How does it work? And is it still used?

We’ll answer all this and more as we dig into this tech. 

What Is DOS?

Put simply, a DOS or Disk Operating System is an OS that runs from a disk drive. This tech made it possible for users to run their personal computers from floppy disks and hard drives.

The earliest home computers, including Commodore 64, Atari 800, and Apple II - all relied on this operating system.

Before them, computers didn’t have any disk drives. Instead, they were hard-wired to complete specific tasks. Then, early storage devices such as punch cards and magnetic tapes emerged. But, this tech was quickly replaced by floppy disks and hard disks with their many improvements.

And by the early 1980s, these storage devices became more available and with greater capacity. Seizing on this medium’s popularity, tech firms began developing and introducing DOS operating system products.

Who invented DOS?

Tim Paterson, an American computer programmer, is often considered the father of this pioneering technology. He earned this moniker for developing the 86-DOS while working for Seattle Computer Products.

Paterson developed 86-DOS to be compatible with the Intel 8086 16-bit processor. Bill Gates’ Microsoft soon after purchased it. After leaving Seattle Computer Products, Paterson had a brief stint with Microsoft, and that’s when the latter developed its very own PC-DOS version - MS-DOS.

Microsoft initially released version 1.0 of PC-DOS in 1981. It was followed by version 1.1. in 1982, which advanced the use of double-sided floppy disks.

What other operating systems were available back then?

During the 1980s, it was the most common OS in most household computers. MS-DOS computers dominated the IBM PC-DOS compatible market until 1995. This is when Windows 95 was released, which merged the formerly separate MS-DOS and Microsoft Windows products. 

Other popular disk operating systems during the 1980s were specific iterations for Commodore DOS, Atari DOS, Amiga DOS, and Apple DOS.

Newer operating systems like Windows NT (New Technology) and OS/2 relied less on this operating system but could still execute DOS-based programs. 

Now that we better understand what DOS is, let's take a closer look at how it works, whether or not people still use it today, and what the future holds for it.

How Does DOS Work?

Because modern operating systems are the daily norm, many contemporary computer users may not know about this OS, let alone know how it works. If this is you, then it’s time to change that.

At its core, the DOS computer system interfaces between software programs and a computer’s hardware.

When you turn on the computer, the read-only memory (ROM) bootstrap reads the information from the first sector of the hard disk or diskette. Then, it passes control over to it.

With the Master Boot Record operating the machine, the computer transfers data from the disk to its read-only memory. Additionally, peripheral devices like monitors and printers also receive information. 

Then, the computer provides application programming interfaces for programs designed for different operations. They can provide input and output, memory management, program loading, and more. 

A mere miracle in its heyday. 

Since DOS only supports a character user interface (CUI), you must input DOS commands manually through a keyboard. The typing of commands may seem ridiculous in today’s computing world, as we primarily rely on a graphical user interface (GUI). This allows us to switch between numerous tasks with simple clicks of a button.

Advantages and Disadvantages

Using this tech has numerous pros and cons. Let’s drill down on some of the most important ones.

Advantage: Direct access to BIOS

One of the best things about this operating system is that it provides direct control over the computer’s Basic Input/Output System (BIOS). This allows you to operate any underlying hardware.

Advantage: Boots faster

This OS is exceptionally lightweight. As such, it boots faster than any other operating system. It expectantly runs on a smaller system, though.

Advantage: Managing/Administering MS

DOS is a capable operating system for implementing workarounds when managing or administering a Microsoft operating system. This is largely due to its ability to more directly control over computer processes than a GUI-based system.

While that all sounds good, there is little doubt that modern day computing requires something more.  

Disadvantage: Single task limitation

A crucial difference from present-day operating systems is that it doesn’t support multitasking on your computer. If you’re accustomed to working on several open windows or tabs, you won’t have a similar experience with DOS. Instead, you are limited to one task at a time.  

Disadvantage: Character User Interface

Because it relies on CUI commands, it cannot open pictures, videos, games, and most other things that modern OSs can. This also means mouse inputs are not supported. The only way to control this computer system is by typing DOS operating system commands. 

Disadvantage: Single-user

Only one user can operate this operating system. In other words, whoever uses the machine has access to the data stored in it.

Funny enough, older computers often had physical padlocks to prevent others from accessing them.

Disadvantage: Can’t address more than 640 MB of RAM

Considering when DOS was initially released, it’s understandable that it doesn’t have the capacity of modern-day operating systems. As such, expect issues if addressing more than 640 MB of RAM. 

With such limitations, it's a godsend that operating systems have evolved. 

How To Use DOS?

As mentioned above, you can only operate this OS by inputting text. This may seem complicated, but the process isn’t so daunting once you get the hang of it. All it takes is learning some of the basic DOS commands.

Before we move on, it’s important to mention that most disk operating systems aren’t case-sensitive. The commands will work whether you type them in uppercase or lowercase. However, the DOS Linux version is case-sensitive.

Now let’s dive deeper into the process.

When the computer has successfully booted the operating system, it opens the command line interpreted COMMAND.COM.

That’s where the user can enter commands through the keyboard.

But you may be wondering, what is a DOS command?

Basically, it’s what you use to interact with the operating system. Unlike in Windows, in DOS, these commands are the primary way you communicate with the computer.

DOS Command examples

We’ll start with an obvious one.

If you want to change file directories in this operating system, the command you should input is “cd”. So, you have to type “cd:\testdirectory” to switch your working directory to “testdirectory”.

And what if you want to delete a file from this directory?

The command used in this scenario is “del”. As you can assume, it deletes one or more files.

In practice, you’d have to type “del c:\testdirectory\testfile.txt”.

Keep in mind, Microsoft DOS commands are commonly called just DOS commands.  More or less synonymous.  

If you look at basic commands for MS-DOS and Linux, you’ll notice that not all of them are the same.

For example, if you want to display differences between two files in both systems, you must use two different commands.

In MS-DOS, you do this by inputting “fc c:\testdirectory\testfile1.txt c:\testdirectory\testfile2.txt”.

The Linux command counterpart is “$ diff testfile1.txt testfile2.txt”.

Consider also that not all versions of MS-DOS have every command available. Microsoft regularly added new directives with the release of its new OS iterations. 

For example, the expand command introduced in 1990 with MS-DOS v.5 serves to extract one or more files from a compressed file. Such an instruction never previously existed. 

Some present-day users are aware of Windows Command Prompts or CMD commands. It’s necessary to differentiate the two as they’re not the same commands available with DOS.

DOS Today

With the introduction of Windows XP in 2001, this disk operating system is seldom ever used. 

If, for example, you want to access retro games or other types of  DOS software, you will need to reboot this rarely used operating system. 

George R.R. Martin, the author of the popular A Song of Ice and Fire series, recently explained that he uses a DOS word processor. This is because he takes a more traditional writing approach without spell-check and similar features.

Beyond supporting niche users of retro software, how else is this by-gone OS relevant today?  

Currently, a few dozen core developers continue to further the FreeDOS project. Eric Auer, a long-time core contributor to the project, explained that it is still relevant because “it is small enough to get an idea of the inner workings.”

The system does very little, but what it does do, it does very well. For example, it gives developers a chance to get closer to the hardware, which, for security and stability reasons, isn’t the case with modern operating systems.

Auer also compared the DOS-based system to model trains as “you can learn to know a lot about it, and you can do a lot with it yourself, but you would not use it for your daily commute.”

Wrap Up

There’s no doubt that the disk operating system, better known as DOS, has played a significant role in the development of personal computing. And while used only occasionally these days, it hasn’t been completely forgotten. 

It’s a perfect example of how much operating systems have evolved during these past decades.  We can only wait and see what the future holds for Windows and other popular OS options.