Disk operating system, usually used as a short form for MS-DOS was developed by Microsoft for IBM. It is compatible with every personal computer. DOS is a family of disk operating systems and consists of MS-DOS and a new version of PTS-DOS, ROM-DOS, IBM PC DOS, Dr-DOS, Free-DOS, etc. There are over a dozen operating systems under the name of ‘DOS – the others include AmigaDOS, TRSDOS, Commodore DOS, AtariDOS, Apple ProDOS, and Apple DOS, among others.

The initial version of MS Windows was operated on DOS. In the 1990s, one saw it being used for Windows Graphical Shell. When Windows 95 was developed in 1995, it was created as a separate operating system which did not need a DOS license.

DOS accessed hardware directly, making it perfect to be used in embedded devices. The concluding versions of DR-DOS still target this section of the market. ROM-DOS was employed by Canon Powershot Pro 70 as an embedded system.

The first version of DOS was very simple and looked like an operating system called CP/M. The later versions were more sophisticated as they had features of a minicomputer operating system. DOS was and is still a 16-bit operating system and does not support multi-tasking, something that operating systems today are adept at.

However, Windows helped solve many problems but it relied on DOS for many things – even Windows 95 used DOS. The Windows NT does not use DOS, although it does execute DOS based programs. DOS is expected to disappear soon. Caldera, Inc. markets a version of DOS called DR-Open DOS which is an extension of MS-DOS in many ways.

Internet applications on disk operating systems are hard as it not network-oriented nor is it a multi-tasker or a multi-user, friendly operating system. DOS is used to run browsers or office software. DOS is important for those who have worked with it; it allows them to keep their old custom-made software. The core audience is huge and there are still a number of companies which continue to develop systems that run on DOS. Microsoft still offers a version of MS-DOS for embedded systems to devise manufacturers

DOS commands are commands which are available in MS-DOS which is used to interact with the operating system and other line-based software. DOS commands are the primary method to use the DOS operating system.

DOS commands are classified into two types. DOS commands with specifications in the shell (command.com) are called as Internal Command. Frequently used commands are called Resident commands. DOS uses command text and line-based interface, which allows users to simply type commands. With the help of the commands like cd (change directory) and pwd (print working directory), the user can browse files on running programs, open files, and the hard drive. However, even if the commands are simple, the user must know the commands to use DOS. This is what made DOS difficult for new users and hence Microsoft bunched DOS together with graphic-based Windows operating system.

The first version of Windows right up to Windows 95 ran on DOS operating systems. Hence, it had numerous DOS-related files like .com, .dll, and .ini files which are still in use. The Windows operating system was reworded with Windows NT (New Technology), which allowed Windows to operate without using DOS.

DOS is still a part of Windows, but it runs from the Windows operating system rather than the other way around. The DOS prompt is opened in Windows when you select the ‘Run’ option on the Start Menu after punching in ‘cmd’.

If you are using a Windows computer, you will have to start the command prompt manually. The command prompt shows which directory you are working in. The DIR command lists the contents on the hard disk which depends on the person and the location.