The document discusses the history and features of the MS-DOS operating system. It describes MS-DOS as a single-user single-tasking operating system that provided a command line interface. It details the various versions released from MS-DOS 1 to 7 and the competition it faced from systems like CP/M and DR-DOS. The document also outlines how MS-DOS was eventually replaced by Windows 95 but retained some legacy compatibility and discusses related single-user systems.

1. COMPUTER AND COMPUTATION
MS DOS
Assignment
IBRAR KHALID
2011-CH-55
2012
DEPARTMENT OF CHEMICAL ENGINEERING

2. CONTENTS
 Dos
 History
 Versions
 Competition
 Legal Issues
 Use Of Undocumented APIs
 End Of MS DOS
 Legacy Compatibility
 Related Systems
 References
 External links
DEPATMENT OF CHEMICAL ENGINEERING Page 1

3. Operating system is a set of programs that controls the working of your computer system.
There are following main types of O.S, which are given below.
 SINGLE USER SINGLE TASKING
 SINGLE USER MULTI TASKING
 MULTI USER MULTI ASKING
 RTOs
MS Dos is a type of operating system which is under the heading of “Single User Single Tasking
Operating System”
Dos
It stands for Disc Operating system.
It is an old version of operating system which is not very common in now a days. It gives us a
command line user interface.
History
MS-DOS was a renamed form of 86-DOS – informally known as the Quick-and-Dirty Operating
System or Q-DOS[3] – owned by Seattle Computer Products, written by Tim Paterson.
Microsoft needed an operating system for the then-new Intel 8086 but it had none available,
so it bought 86-DOS and licensed it as its own then released a version of it as MS-DOS 1
Development started in 1981.
Originally MS-DOS was designed to be an operating system that could run on any 8086-family
computer.
Versions
The following versions of MS-DOS were released to the public.
MS-DOS 1.x
MS-DOS 2.x
Support for 10 MB hard disk drives and tree-structure filing system
MS-DOS 3.x
DEPATMENT OF CHEMICAL ENGINEERING Page 2

4. MS-DOS 4.x
MS-DOS 5.x
MS-DOS 6.x
MS-DOS 7.x
Competition
On microcomputers based on the Intel 8086 and 8088 processors, including the IBM PC and
clones, the initial competition to the PC DOS/MS-DOS line came from Digital Research, whose
CP/M operating system had inspired MS-DOS
The pact between Microsoft and IBM to promote OS/2 began to fall apart in 1990 when
Windows 3.0 became a marketplace success.
IBM, which had already been developing the next version of OS/2, carried on development of
the platform without Microsoft and sold it as the alternative to DOS and Windows.
Legal issues
As a response to Digital Research's DR DOS 6.0, which bundled SuperStore disk compression,
Microsoft opened negotiations with Stack Electronics, vendor of the most popular DOS disk
compression tool, Stacker.
In the due diligence process, Stack engineers had shown Microsoft part of the Stacker source
code.
USE OF UNDOCUMENTED APIs
Microsoft also used a variety of tactics in MS-DOS and several of their applications and
development tools.
Notable examples of this practice include,
Microsoft's Quick Pascal
The (once infamous) code AARD code, a block of code in the Windows 3.1 beta installer.End of
MS DOS
DEPATMENT OF CHEMICAL ENGINEERING Page 3

5. Today, MS-DOS is rarely used for desktop computing. Since the release of Windows 95, it was
integrated as a full product used for bootstrapping and troubleshooting, and no longer released
as a standalone product.
However the only versions of DOS currently recognized as stand-alone OSs, and supported as
such by the Microsoft Corporation are DOS 6.0 and 6.22, both of which remain available for
download via their MSDN.
Legacy compatibility
From 1983 onwards, various companies worked on graphical user interfaces (GUIs) capable of
running on PC hardware.
With DOS being the dominant operating system several companies released alternate shells,
e.g. Microsoft Word for DOS, and the Norton Commander.
Later versions (Windows 95, Windows 98 and Windows Me) used the DOS boot process to
launch itself into protected mode. With the latest Windows releases, even dual-booting MS-
DOS is problematic as DOS may not be able to read the basic file system.
Related systems
Single-user
Several similar products were produced by other companies. In the case of PC DOS and DR-
DOS, it is common but incorrect to call these "clones". Given that Microsoft manufactured PC
DOS for IBM, PC DOS and MS-DOS were (to continue the genetic analogy) "identical twins" that
diverged only in adulthood and eventually became quite different products. Some types are
given below.
DR-DOS
DR-DOS
GNU/DOS
PTS-DOS.
These products are collectively referred to as DOS. However, MS-DOS can be a generic
reference to DOS on IBM-PC compatible computers.
DEPATMENT OF CHEMICAL ENGINEERING Page 4

6. References
Microsoft.MS-DOS 6 Technical Reference
Search through Net
External links
DOS version timeline
Ralf Brown's Interrupt List
DOS command overview
DOSBox, a multiplatform DOS emulator
GARBO - An MS-DOS program distribution library at the University of Vaasa, Finland
MS-DOS Resources
Information on various aspects of MS-DOS including download
THANK YOU
DEPATMENT OF CHEMICAL ENGINEERING Page 5