Popular operating systems


In this article we will discuss about some popular operating systems. except from this in this section, we shall discuss in brief, some salient features of two commonly used operating systems, namely MSDOS and Unix. MSDOS is an operating system available on personal computer series of IBM with microprocessors Intel 8086, Intel 80286, Intel 80386 and Intel 80486 (for various families of microprocessors, see Appendix-A). Unix is a trademark of an operating system created by AT&T Bell laboratories. This operating system is available on variety of the computer systems ranging from personal computers to main- frame and supercomputers. Normally, Unix operating system is used on microcomputers, micro/mini and some minicomputers where a moderate number of terminals are connected.


MSDOS stands for Microsoft Disk Operating System and PCDOS is abbreviation of Personal Computer Disk Operating System. These two are closely related in their features This operating system is compact and can be stored on a floppy disk. MSDOS is supported by a large number of utilities, associated with the core operating system.

Following are main features of MSDOS:

  • (a) It is a single user, single process operating system,
  • (b) It supports batch processing mode of operation,
  • (c) It provides the file system in a hierarchical organization, i.e. there is a root directory, and sub-directories at various intermediate levels and the files at the lowest level,
  • (d) It supports a wide range of system software tools like language compilers, editors, interpreters, linkers and software maintenance tools. It also supports application packages like word-processors, spreadsheets, database management systems. CAD/CAM packages and expert system shell etc.
  • (e) It has become a very popular and versatile operating system. A text file in MSDOS format can be read by other operating system.

There are numerous commands and utilities associated with MSDOS. A command is intrinsic to the kernel (core) of the operating system i.e. it is integral part of the kernel. A utility is a separate routine out side the kernel but it is executed by the operating system. We illustrate a few frequently used commands and utilities of MSDOS for some basic system operations.


It is a command to enlist the names of the files stored in the file table (directory).


It is a command to create a new directory which will be sub-directory of the working directory.


It is a command to remove a sub-directory if it does not contain any files or other sub-directory.


It is abbreviation of Change Directory which allows to change the working directory.


It is a command to delete a file from the file system.


It is a command to rename a file in the file system.


It is a command to copy contents of some specified file into another specified


It is a utility to initialize a disk for usage. file.


It is a utility to check the status of the disk and display it to the user.


It is a utility to copy track-by-track a complete disk to other disk.


It is a utility to store a backup of the contents of disk.


It is a utility to restore the files stored by backup utility.


It is a utility to recover the damaged or lost files.


Unix is a very popular multi-user, multi-tasking operating system with time-shared mode. The main objective of this operating system is to provide a platform for program development, networking and documentation. Unix operating system is so versatile that it is available on various types of computer systems. It is available on personal, micro, mini, and mainframe computers. Some super-computers are also provided with Unix. Major salient features of Unix operating system are:

  • (a) It is portable on various types of machines,
  • (b) It allows the usage in multi-user mode through interactive terminals,
  • (c) Its file system is tree structured (hierarchical),
  • (d) It provides tools and utilities for developing more tools and utilities and the application packages,
  • (e)  It is associated with the library of scientific and statistical functions and routine to support compilers.
  • (f) It provides a large number of software calls to help in development of software tools like compilers and interpreters,
  • (g) It has facility of networking through modem circuits for electronic mail,
  • (h) It supports text-formatting software tools.

There are numerous commands and utilities available on Unix operating system. We present here a few frequently used commands and utilities for some basic system operations.


It is a command to enlist the files of the working directory.


This commands creates a new sub-directory in the working directory.


It removes a sub-directory, if it does not contain any files sub-directory.


This command changes the working directory.


It removes one or more files.


It moves a file by name.


It copies a file to other file.


It concatenates (join in sequences) one or more files


This command mounts a device for usage.. .


It performs backup of the whole disk or files specified in the disk.


It restores the dumped information.


Windows’ is a concept of GUI based operating systems that provide a very easy to use interface to the users of the computers. Microsoft evolved this concept in 1985 with a view that the contemporary powerful operating systems such as MSDOS and Unix are limited to text commands for computer operations. Windows came out with a philosophy of providing the graphical ways of commanding the computer resources. Windows OS combines the salient features of MSDOS and Unix for memory management, I/O management, process management and file management.

Following are the main elements of a Windows operating system:


It is an area on the computer screen with a number of Icons.


It is a graphical symbol to indicate a program, a folder, an activity or an file.


It is used to point and click using a mouse.


It is blinking character for inserting a character.

Desktop Interface:

A desktop interface provides a set of click operations.

  • Left-click: It is used to select or open.
  • Right click: It is used provide a menu of quick options.
  • Single-click: It is used to select an item
  • Double-click: It is used to open or launch program


This option provides details about the size of drives, disks, folders and files. This is also used to change the appearances and preferences of windows, drives, disks, folders and files.

New folder:

It can be created by right-click on desktop or select icon for new folder.

Drag and Drop:

This facility allows a user to move files by single left-click on item, hold down on mouse button and drag to desired area. Sometimes it can be used to copy files to new location.


It is an option to provide a Pull down menu in most windows. Start Button> Help. Press F1 at any point that you have a question. Type your question in box and left- click Select. (This is the Office Assistant.) Help will often provide definition of terms that pop-up when you click on the underlined term.

Moving Taskbar:

A task bar can be moved by a click and hold down on the Taskbar, drag to right, top or left.

Start Button:

It is used to start programs, change settings, access Help, Run programs or setups, and Find files or programs and access recently used documents.


It is an opened box appearing on screen. It can be resized. Most windows have the same features: title bar, pull-down menus, standard toolbar, status bar and scroll bars.

Active window:

It is the window on top and it is also seen in an indented button on the Taskbar


It keeps program running and sends to Taskbar


It opens window in full screen Close: It closes is used to close a file or program.


They take you step-by-step to perform certain tasks. The wizard are very helpful because they have default settings based on most common usage of programs and files.


This helps to find files, programs, folders, downloads that you want to open and can’t remember where they were saved. Can be done by name, date, extension, etc.

Windows Explorer:

It is one more way to find and access files, programs. This shows the paths and directories of the drives, folders and files. You can move, copy and delete folders, files using Explorer.

Copy/Cut and Paste:

It is a facility to select (with copy or cut option) a file or a folder or a program on a desktop and paste the same on other desktop. There are various versions of Windows OS in the last two decades:
  • 1. Windows 3.11- it was an interface over MSDOS.
  • 2. Windows 95- it was the first independent Windows OS.
  • 3. Windows 98- it was an enhanced and improved version of Windows 95.
  • 4. Windows 2000-it is still better version of Windows with advanced facilities to support applications directly. The Internet protocols were built in this OS.
  • 5. Windows NT- it is a network operating system to work on LAN and get connected to other LANs. It is based on Networking Technologies at Hardware and Software level both.
Windows XP and Windows ME are some more versions of Windows that have come up for meeting the requirements of different applications. A sample look of Desktop of a Windows

OS is shown in Figure below.

Popular operating system
A Sample Desktop


Lastly, we mention some other operating systems that have been available on various machines:
  • VAX/VMS operating system on VAX computers,
  • VM/370 operating system,
  • UCSD pascal system,
  • CP/M operating system,
  • ECORN: On BBC machines,
  • OS/2 operating system.

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