MS-DOS, Windows and UNIX

The operating system is a system software used for management of computer hardware and application software. It is a interactive interface of computer.

MS-DOS is a very popular operating system for PC, and it is replaced by its extension Windows operating system. In the Windows environment, DOS is also Boss because many utilities programs of MS-DOS are used in trouble shooting of Windows Operating system.



MS-DOS stands for Microsoft Disk Operating System. Tim Paterson developed this operating system in 1980. The IBM (International Business Machine) released first PC (Personal Computer) in 1981. MS-DOS version 1.0 was used as operating system in IBM-PC and become talk of town in overnight.

The father of PC Operating System is Gary Kildall of Digital Research. He had his Ph.D in computer and designed more successful operating System called CP/ M. The selling of CP / M is more than 600,000 copies proves its popularity. The Microsoft Disk Operating System or MS-DOS was based on QDOS, the Quick and Dirty Operating System written by Tim Peterson of Seattle Computer Products, for their prototype Intel 8086 based computer. QDOS was based on Gray Kildall’s CF/M,. Paterson had bought a CP/ M manual and used it as the basis to write his operating system six weeks, QBOS was different enough from CP / M. MS-DOS version 7.0 is lunched in 1997 which is a hidden with Window 95/98 OS.

It has three essential files and many command files. These essential files are: IO.SYS, MSDOS.SYS, and COMMAND.COM. These files are called system files of MS-DOS. The DOS is Boss in real sense, because in the age of Windows operating system, hardware utilities are dependent on the DOS.

The heart of MS-DOS:

  • IO.SYS: This let DOS communicate with the hardware through the BIOS (Basic Input / Output System).
  • MSDOS.SYS: This is a DOS kernel.
  • COMMAND.COM: This is where all the DOS commands are stored and interpreted.
  • COFIG.SYS: Hardware configuration information is stored here.
  • AUTOEXEC.BAT: All the programs that are supposed to run at startup are called here.


(a) Booting: The booting is a process of loading system files into main memory (RAM). There are two types of booting: cold booting and warm booting.

Algorithm of booting:

Step-1: Turn on computer

Step-2: ROM is activated and BIOS (Basic Input Output System) is loaded.

Step-3: POST (Power On Self-Test)

Step-4: Boot records load the initial system files (lO.SYS) into RAM from disk.


MBR (Master Boot Record) is the information in the first sector of any disk that identifies how and where an operating system is loaded into RAM. MBR is also called Partition sector or Master Partion table.

There are two types of booting:

  • Cool Booting: Booting by turn on computer.
  • Warm Booting: Booting of turn on computer when it is hanged using Alt+ Ctrl+ Del or reset button.

DOS gives drive letters to each disk drive ’C:’ is displayed for hard disk drive, A: for floppy and so on.


(b) File and Directory: The collection of data is called file. It has specific memory location represented by name which is called file name. The file name has two parts: main part (maximum 8 characters) and extension (maximum 3 characters). We cannot use exe, com as file extensions and commands are also not used as file name.

Example: student.txt, exam.doc

These two names are separated by point (.). The files are collected in directory or folder.


(c) Internal and External DOS Commands:


Internal Command

External Command


The internal command of DOS are packed in command interpreter ( file. These commands became active at MS-DOS prompt. These commands are limited in numbers.

The external commands are not present in command interpreter. It is called from data stores of any other folders. These commands have exe or com extension.

Example: xcopy.exe, msd.exe. move.exe, mem.exe, etc


Example: Copy con, cls, copy, date, del, netch, tracert, ipconfig

Example: chkdsk, diskcopy, format, edit, tree, xcopy, deltree


The switch is used to enhance productivity of any MS-DOS commands. If you want to know about switches of xcopy, type, type xcopy /? At DOS prompt and press enter key.


C:\> Xcopy/? <enter>


Some very common dos command:




To display current time:


TO display current date:


To display volume:


To display version


To create file:

COPY CON <Filename>


C:\> COPY CON student.txt <enter>


To save file:

Z^ or F6

To edit file:

EDIT <Filename>


C:\> EDIT student.txt <enter>

To clean monitor


To retrieve Contents of file

TYOE <Filename specification>


C:\> TYPE student.txt

To delete file:

DEL <file specification>


C:\> student.txt<enter>


Some Standard Commands:


i. To display files and sub directories: DIR [drive:][path][filename]

  • /P: Pause after each screen full of information


  • /W: Uses wide list format


  • /A : Display files with specified attributes

D for Directories, R for Read only files,

H for hidden files, S for system files etc.

  • /O: Displays in sorted order

N by name, S by size, E by extension, D by date etc

Example: C:\> DIR /AD<enter>


ii. To copy file: COPY<source><destination>


C:\>COPY student.txt a:\AVN<enter>

To set attributes: ATTRIB [switches]



+R :  Set Read Only attribute

-R: Clear Read Only attribute

+A: set the file as a system file

-A: clear archive file attribute

+S: set the file as a system file

-S: clear the system file attributes

+H: set the file as hidden file

-H: clear the hidden file attribute


C:\> ATTRIB +R +A A:\student.avn<enter>


iii. To copy all files (except hidden ) and directories, sub directories:

XCOPY source specification destination specification [switches]


  • /S: Copies all files and subdirectories except empty one.
  • /E: copies any subdirectories, even if they are empty.
  • /Q: Quite mode. Doesn’t display files while copying
  • /H: copies hidden files.
  • /R: Over-writes read-only files, too.
  • /V: Verifies each new as it is written to the destination file to make sure that the destination files are identical and wait for response.

Example: C:\> XCOPY A:C:\avn /S /H<enter>


iv. To know about more and more about all internal and external MS-DOS command:


Example: C:\>HELP<enter>


v. Some sub directory related commands:

  • To create sub directory : MD <directory>

Example: C:\> MD AVN<enter>

  • To change directory: CD<directory>

Example: C:\>CD AVN<enter>


  • To exit form directory: CD\ or CD..

Example: C:\AVN>cd\<enter>


  • To remove empty directory: rd<directory>

Example: C:\> RD avn <enter>

  • To delete all directories: DELTREE

Example: C:\>AVN>DELTREE student \*.*<enter>


vi. Some other commands:



To check directory and FAT ( File Allocation Table):


To check status of drive:


To create or change volume label:


To transfer DOS system


To display directory structure:


To make backup



vii. To format disk : FORMAT [drive:][switch]


  • /Q: perform quick formatting. It is suitable for formatted floppy or disk.
  • /F: SIZE: Size as 160, 180,320,729,1.2,
  • /B: Allocate spaces for system files
  • /S: Copies system files
  • /T: Tracks: Specifies the number of tracks per disk side
  • /N: SECTOR: specifies the number of sectors per track
  • /1: Single Side

Example: C:\>FORMAT A:/Q<enter>


viii. To copy contents of one disk into other disk:

DISKCOPY [drive1:[drive2:]][/1][/V][/M]


  • /1: Copies only the first side of a disk
  • /V: verifies that the information is copied correctly.
  • /M: Forces diskcopy to use only conventional memory for interim storage. By default, diskcopy uses hard disk as an interim storage area so you don’t have to swap floppy disks.

Example: C:\>DISKCOPY A:A: /V <enter>


ix. To complete diskettes: DiskCOMP [drive1: [drive2:]][/1][/8]


  • /1 : Compares only the first side of the disk, even if the disks are double-sided and the drives can read double-sided disks.
  • /8: Compares only the first 8 sectors per track, even if the disks contain 9 or 15 sectors.

Example: C:\> DISKCOMP A:A:<enter>

x. Stop Execution (ctrl-break): If you wish to stop the computer in the midst of executing the current command, you may use the key sequence CTRL-BREAK. Ctrl-Break not always works with non-DOS commands. Some software package block its action in certain situation, but it is worth trying before you re-bool.


Dos Version


The following table shows gradual incensement in commands of MS-DOS. External commands are added in each versions but there is no fantastic changes are shown in internal commands in each version. All the internal commands are packed in interpreter of DOS.

Dos Version

Dos Version



It is an operating system, extension of MS-DOS with user friendly GUL and several facilities to control memory, hardware, text, graphics, audio, video, internet connection etc.



Windows 1.0

This operating system with user interface is a notification of MS-DOS. The nifty mouse is used to click on desired program to open. It was first called interface manager, but then changed in to the more appealing Windows. Windows 1.0 lunched in November 1985.

Windows 2.0

It was released in 1987 to take advantage of the awesome processing power of the Intel 286 processor. The first version of Microsoft Word and Excel are introduced in this version.

Windows 3.0

It was released in May 1990. It came with a prettier 16-color interface, and new technological bells and whistles that let it make better use of the memory. In 1991, Microsoft brought multimedia support for Windows 3.0, called Multimedia Extensions 1.0. It gave Windows support for CD-ROM drives and sound cards. It also contained a basic CD player application for Windows.

Windows 3.1

It was released in April 1992. It was equipped with big, comprehensive API (Application Program Interface), which simplified the task of creating user interface and let them focus more time on developing the core functionality of software.

In 1993, windows for Workgroup 3.1 were released, which added support for networking, file and printer sharing. It also added Microsoft Mail Program to send and receive over the network.

Windows NT

In 1988, Microsoft had been developing, Windows NT; the NT stands for new technology. This was a whole new kernel, built for data and application security.

It is a robust, pre-emptive, multi-threaded, multi-tasking, 32-bits operating system with symmetric multiprocessing support.

Windows 98

It released in 1995. It is equipped with advance technology like AGP (Accelerated Graphics Port), MMX (multimedia Extension), USB (Universal serial Bus), DVD (Digital Video Disk) etc. Its most visible feature, through, is the active desktop, which integrates the web browser (internet Explorer), with operating system.

Windows 2000

Its interface is similar to interface for windows 98. It has new security protocol with an encryption facility to authenticate users logging in to the network. It supports 32 FAT file system along with NTFC (New Technology File System), making it easier for users to upgrade for Windows 98. It has quite robust hybrid kernel architecture, make it more stable version.

Windows Me

Later in 2000, Windows Millennium (windows Me) Edition was released for the home user. This was the last version of Windows to be based on Windows 98. Windows Me had always been regarded as Microsoft’s way of keeping users busy while they waited for Windows XP.

Windows XP

Here, XP Stands For eXPerience. It bought together the robust Kernel of windows 2000 and all the friendless and multimedia support of windows Me, and painted on a new face for it.

Apart from the merger of Windows 2000 and me, Windows Xp also added new features to enhance its performance. The first of These was its ability to work even in low-memory conditions without crashing, using a technique called Memory Throttling, Usually,  Windows likes to do many things at once, but when memory falls short, it will throttle its memory access, doing fewer at a time. This shows the system down considerably, but prevents it form crashing.


GUI Operating System


There are many operating system available with GUI (pronounced as goo-ye). The concept of GUI is invented by computer scientists of PARC (Palo Alto Research Center) of Xerox Corporation in early 1970, but it is used in business sectors by Apple Corporation first time in 1983 and Macintosh Computer introduced its updated form in 1984. In beginning, the apple has introduced GUI operating system in market. The Microsoft has lunched operating system with GUI, after apple. The Microsoft Windows operating system is an excellent example of GUI.

The pointer, pointing devices, program icons, desktop, windows, menu etc are main GUI components of operating system.

Some features of GUI operating systems are given below:

  • The interface: is a common boundary between the user and the computer system. The GUI interface is equipped with clickable program icons.
  • Program icon: The GUI operating system contains program icons which are linked with main program. Icon is bitmapped graphics used to represent program, file, and windows. When program icon is double clicked, program is executed.
  • Desktop: The desktop is a container in which program icons and other interface components are arranged in attractive ways. It has users compiling background, animation, system tray etc.
  • System tray: It contains date, time, explorer, printer, anti-virus and other icons on the try.
  • Excellent desktop: The on screen work area is called desktop. The facility to change color, fonts, wall papers and others.
  • Menu: The program menu is also available with all the available facilities. We can open program by clicking the program icons displayed on desk top or by opening pop up menu.

A Graphical User Interface (GUI) allows one to enter commands by pointing and clicking objects appearing on the screen. Thus, the operating system hides the innermost details of the working of computer hardware components and presents a simple, usable and effective model of the computer to the user.

  • Control Panel: The Windows control panel is a real hardware and software engineer because all the problems can be removed from here. So, it is names as Control Panel.
  • System Tools: The Windows Operating system is equipped with several tools to control several activities. These tools are utilities program like as Disk Cleanup, Disk Defragmenter, Drive Converter (FAT32), Maintenance Wizard, ScanDisk, Sheduled Tasks etc.


  • Recycle Bin: Deleted files of folders are stored in it. If any important files are deleted, you can restore these files again from Recycle Bin. It is based on concept of dust bins in which litters, dusts, and unwanted thins are collected for final disposal. The Recycle bin is similar to Trash icon of Macintosh.


UNIX Operating System


The UNIX (pronounced as YEW-nihks) is a powerful, flexible, multi-user Operating system with GUI and several utilities. Ken Thompson and Dennis Ritchie wrote C compiler under UNIX in 1969 at Bell Labs. In 1973, Thompson and Ritchie rewrote the UNIX kernel using C language. It is based on MULTICS operating system. Its first user was Bell patent department. XENIX, VENIX, MICRONIX, LINUX, UNIXWARE-7 etc are version of UNIX operating system.

The UNIX operating system is made up from three parts:

(a) Kernel: It is a hub of operating system dedicated for memory management, file management and communication within system.

(b) Shell: It is an interface between kernel and users. When a user logs in, the login program matches the username and password, and then starts shell. The shell is a command line interpreter (CLI) of UNIX.

(c)Program or command is used to accomplish specific tasks. When one command is terminated, the shell displays prompt % to accept next command for execution.


Some UNIX Commands:

  • To display files of current directory: Ls

Example: %Ls

  • To make directory: Mkdir<destination>

Example: %Mkdir unixst

  • To change directory: cd

Example: %cd

  • To copy file: cp<source><destination>

Example: 5cp /student /example /bio.txt

In UNIX, the dot means the current directory.

  • To move file: mv<file1><file2>

Example: 5mv bio.txt hello/

  • To remove or delete directory: rm or rmdir<directory>

Example: %rm unixstd

  • To display contents of file: Cat<file1>

Example: %cat bio.txt

  • To clean monitor: clear

Example: %clear

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