4.2 Disk Operating System (DOS)
4.2.1 What is DOS, and why learn about it?
Microsoft developed the Disk Operating System (DOS), also called MS-DOS, in 1981. DOS was designed for the IBM Personal Computer. Windows 98 and Windows 2000 both support DOS commands in order to address compatibility issues related with older applications. Simply put, DOS is a collection of programs and commands used to control the overall computer operation in a disk-based system. There are three distinct sections that make up the disk operating system. These include the following:
  • Boot files – Used during the boot process (that is, start-up).
  • File management files – Enables the system to manage the data that it holds.
  • Utility files – Enables the user to manage system resources, troubleshoot the system, and configure the system settings.

DOS programs usually work in the background, permitting the computer user to input characters from the keyboard, to define a file structure for storing records on the disk, and to output data to a printer or monitor. Basically, the disk operating system is responsible for finding and organizing data and applications on the disk.

The introduction of operating systems having a Graphical User Interface (GUI), such as Microsoft Windows, has made DOS mostly obsolete. DOS, however, continues to play a significant role in many areas, including programming, running older applications, and installing the Windows OS, especially on older computers. All generations of Windows to date support DOS commands for backward compatibility with older applications. It is important to understand the basics of DOS before proceeding with a Windows OS installation (see Chapter 5).

Basic Elements of DOS
The following are some of the basic things to remember when working with DOS:

  • DOS is a command line operating system, it is not user-friendly. The best way to learn DOS is to use it.
  • DOS can only run one program at a time. It is not multitasking.
  • DOS can only run small programs and has memory limitations.
  • DOS is an essential tool for IT professionals and is used extensively for troubleshooting.