MS-DOS Operating System

IBM was looking for an operating system for their new line of personal computers. Bill Gates's mother Marry M Gates served on the national board of United Way alongside the CEO of IBM. IBM got in touch with Bill Gates through his mother when he convinced IBM that his company Microsoft could deliver the new software for IBM's personal computer. Bill Gates then bought an existing OS called 86-DOS also known as QDOS for Quick and Dirty Operating System. He then adapted QDOS to run on the new IBM computers and called the particular product as "Microsoft Disk Operating System".

What is MS-DOS Operating System?

MS-DOS Operating System also called the Disk Operating system was Developed by Microsoft for x86 personal computers. It works on the phenomenon of doing less and getting more. It is a 16-bit operating system. A closed-source model was initially released on August 12, 1981, and the final release on September 14, 2000.

Why is MS-DOS Operating System Used? 

It is used for many purposes:

• Education and research: It is used in the Education and research field to know how simple MS-DOS is and how it works. The source code is available from Microsoft in two versions. 
• Legacy systems: Some organizations prefer using MS-DOS because it has been used reliably over decades whereas others don't have the budget to upgrade the application since this process is costly.
• Embedded systems: Embedded systems are dependent on MS-DOS especially new devices with x86 processor architecture. It is also used on legacy Embedded systems which have been used for decades.
• Classic Computer Games: There are still some games that were developed on MS-DOS and still support only MS-DOS.

Features of MS-DOS Operating System

• It is a minimalist OS which means it can boot a computer and run programs.
• Still usable for simple tasks like word processing and playing games.
• The mouse cannot be used to give inputs instead it uses basic system commands to perform the task.
• It is a 16-bit, free operating system.
• It is a single-user operating system.
• It is very lightweight due to fewer features available and no multitasking.

Working of MS-DOS

MS-DOS input and output occur at the command line in the form of issued commands and system results of those commands. When booted, MS-DOS systems display a command prompt. MS-DOS commands are then entered using a keyboard. Commands are either one of the standard DOS commands, implemented as part of the OS, or they are the file name of an executable program.

Although it does not natively support a GUI, MS-DOS can run graphical programs if they are installed on a system disk or diskette. Users enter the command for a graphical program, and the program takes control of the input and output devices. When the program terminates, the control reverts to MS-DOS and the command prompt reappears.

Limitations of MS DOS Operating System

• It is not a multitasking operating system that is we cannot run too many applications in the background.
• Files on the system can be easily deleted or the system can also be easily destroyed.
• It does not provide any warning message before you delete or perform any unwanted task like in windows or Linux. 
• It is text-based and it does not have any graphical user interface.
• Not secure to be used in any kind of public network.
• Encryption is not supported.
• Difficulty in memory access. 
• Mouse cannot be used to give inputs. 

Types of MS-DOS Commands

There are mainly two types of MS-DOS commands:

1. Internal Commands

Internal commands are those commands that are loaded automatically in the memory when DOS is loaded into memory during the booting process. These commands are easier to learn and use. They require no external files for their storage as in the case of external commands. These are for performing a basic operation on files and in directories. They do not need any external file support. These commands are used for common jobs such as copying and erasing files.

2. External Commands

These external commands are for performing advanced tasks and they do not need some external file support as they are not stored in COMMAND.com. The external commands are used less frequently and are stored in some external files which are stored in some secondary storage devices. Whenever an external command is to be executed then the external file in which that particular command is stored is transferred from the secondary storage disk to the main memory(RAM).

How to open MS-DOS in windows?

• Step 1: Click on Windows.
• Step 2: Search for 'Run' or directly use (Windows key+R) to open.
• Step 3: Type 'cmd' in run and press 'Enter'.
• Step 4: MS-DOS will open in many cases with default command prompt i.e. c:\>

Basic MS-DOS Commands

MS-DOS File and Filetypes

A computer file created by an application running under the DOS operating system. is called an MS-DOS file. There are three main files of DOS. During the Booting process, the computer loads the operating system into its memory. DOS booting involves reading the following files into memory namely

• IO. SYS: A hidden executable binary file that processes instructions that tell the operating system (OS) how the computer is set up when it is booted or started.  It contains the default MS-DOS device drivers (hardware interfacing routines) and the DOS initialization program.
• MSDOS. SYS: The MSDOS.SYS file is a hidden, system, read-only file created on the root of the boot drive. There are several configurations that can be changed using this file. Most values in the MSDOS.SYS are either 0 or 1, which is off or on.
• COMMAND.COM: COMMAND.COM is the default command-line interpreter for MS-DOS. It is the default user interface as well.COMMAND.COM is the command shell on MS-DOS and PC-DOS, as well as versions of Windows that depend on DOS. Gives users a command line interface to DOS as well as a way to run scripts called “batch files” with the .BAT file extension.

Conclusion

MS-DOS allows the user to navigate, open, and otherwise manipulate files on their computer from a command line instead of a GUI like Windows. Although it is not widely used nowadays, however, the command shell, also known as the Windows command line, is still used by many users. Legacy systems, specifically older IBM PC-compatible computers, are still in use. Many are still running some versions of MS-DOS. Compatible OSes have been published over the years, including at least two open-source implementations of MS-DOS that are still actively maintained. It’s still around supporting legacy usually standalone applications, generally because they work well and the applications would be expensive and risky to “modernize”.