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MS- DOS
DOS
(/ˌɛmɛsˈdɒs/ EM-es-DOSS ; acronym for MICROSOFT DISK OPERATING SYSTEM) is a discontinued operating system for x86 -based personal computers mostly developed by Microsoft
Microsoft
. Collectively, MS-DOS, its rebranding as IBM PC
IBM PC
DOS, and some operating systems attempting to be compatible with MS-DOS, are sometimes referred to as "DOS" (which is also the generic acronym for disk operating system ). MS- DOS
DOS
was the main operating system for IBM PC compatible
IBM PC compatible
personal computers during the 1980s and the early 1990s, when it was gradually superseded by operating systems offering a graphical user interface (GUI), in various generations of the graphical Microsoft
Microsoft
Windows operating system.

MS- DOS
DOS
resulted from a request in 1981 by IBM for an operating system to use in its IBM PC
IBM PC
range of personal computers. Microsoft
Microsoft
quickly bought the rights to 86- DOS
DOS
from Seattle Computer Products , and began work on modifying it to meet IBM's specification. IBM licensed and released it on August 12, 1981 as PC DOS
DOS
1.0 for use in their PCs. Although MS- DOS
DOS
and PC DOS
DOS
were initially developed in parallel by Microsoft
Microsoft
and IBM, the two products diverged after twelve years, in 1993, with recognizable differences in compatibility, syntax, and capabilities.

During its lifetime, several competing products were released for the x86 platform, and MS- DOS
DOS
went through eight versions, until development ceased in 2000. Initially MS- DOS
DOS
was targeted at Intel 8086 processors running on computer hardware using floppy disks to store and access not only the operating system, but application software and user data as well. Progressive version releases delivered support for other mass storage media in ever greater sizes and formats, along with added feature support for newer processors and rapidly evolving computer architectures. Ultimately it was the key product in Microsoft's growth from a programming language company to a diverse software development firm, providing the company with essential revenue and marketing resources. It was also the underlying basic operating system on which early versions of Windows
Windows
ran as a GUI. It is a flexible operating system, and consumes negligible installation space.

CONTENTS

* 1 History * 2 Versions * 3 Competition * 4 Legal issues * 5 Use of undocumented APIs * 6 End of MS- DOS
DOS
* 7 Windows
Windows
command-line interface * 8 Legacy compatibility * 9 Related systems * 10 See also * 11 Notes * 12 References * 13 External links

HISTORY

Further information: DOS
DOS
and Timeline of DOS
DOS
operating systems

MS- DOS
DOS
was a renamed form of 86- DOS
DOS
– owned by Seattle Computer Products , written by Tim Paterson . Development of 86- DOS
DOS
took only six weeks, as it was basically a clone of Digital Research 's CP/M (for 8080/Z80 processors), ported to run on 8086 processors and with two notable differences compared to CP/M; an improved disk sector buffering logic and the introduction of FAT12 instead of the CP/M filesystem. This first version was shipped in August 1980. Microsoft, which needed an operating system for the IBM Personal Computer hired Tim Paterson in May 1981 and bought 86- DOS
DOS
1.10 for $75,000 in July of the same year. Microsoft
Microsoft
kept the version number, but renamed it MS-DOS. They also licensed MS- DOS
DOS
1.10/1.14 to IBM, who, in August 1981, offered it as PC DOS
DOS
1.0 as one of three operating systems for the IBM 5150 , or the IBM PC
IBM PC
.

Within a year Microsoft
Microsoft
licensed MS- DOS
DOS
to over 70 other companies. It was designed to be an OS that could run on any 8086-family computer. Each computer would have its own distinct hardware and its own version of MS-DOS, similar to the situation that existed for CP/M , and with MS- DOS
DOS
emulating the same solution as CP/M
CP/M
to adapt for different hardware platforms. To this end, MS- DOS
DOS
was designed with a modular structure with internal device drivers, minimally for primary disk drives and the console, integrated with the kernel and loaded by the boot loader, and installable device drivers for other devices loaded and integrated at boot time. The OEM would use a development kit provided by Microsoft
Microsoft
to build a version of MS- DOS
DOS
with their basic I/O drivers and a standard Microsoft
Microsoft
kernel, which they would typically supply on disk to end users along with the hardware. Thus, there were many different versions of "MS-DOS" for different hardware, and there is a major distinction between an IBM-compatible (or ISA) machine and an MS- DOS
DOS
machine. Some machines, like the Tandy 2000 , were MS- DOS
DOS
compatible but not IBM-compatible, so they could run software written exclusively for MS- DOS
DOS
without dependence on the peripheral hardware of the IBM PC
IBM PC
architecture.

This design would have worked well for compatibility, if application programs had only used MS- DOS
DOS
services to perform device I/O, and indeed the same design philosophy is embodied in Windows NT
Windows NT
(see Hardware Abstraction Layer ). However, in MS-DOS's early days, the greater speed attainable by programs through direct control of hardware was of particular importance, especially for games, which often pushed the limits of their contemporary hardware. Very soon an IBM-compatible architecture became the goal, and before long all 8086-family computers closely emulated IBM\'s hardware , and only a single version of MS- DOS
DOS
for a fixed hardware platform was needed for the market. This version is the version of MS- DOS
DOS
that is discussed here, as the dozens of other OEM versions of "MS-DOS" were only relevant to the systems they were designed for, and in any case were very similar in function and capability to some standard version for the IBM PC—often the same-numbered version, but not always, since some OEMs used their own proprietary version numbering schemes (e.g. labeling later releases of MS- DOS
DOS
1.x as 2.0 or vice versa)—with a few notable exceptions.

Microsoft
Microsoft
omitted multi-user support from MS- DOS
DOS
because Microsoft's Unix
Unix
-based operating system, Xenix
Xenix
, was fully multi-user. The company planned to over time improve MS- DOS
DOS
so it would be almost indistinguishable from single-user Xenix, or XEDOS, which would also run on the Motorola 68000
Motorola 68000
, Zilog Z8000 , and the LSI-11 ; they would be upwardly compatible with Xenix, which Byte in 1983 described as "the multi-user MS- DOS
DOS
of the future". Microsoft
Microsoft
advertised MS-DOS and Xenix
Xenix
together, listing the shared features of its "single-user OS" and "the multi-user, multi-tasking , UNIX
UNIX
-derived operating system", and promising easy porting between them. After the breakup of the Bell System , however, AT&T Computer Systems
AT&T Computer Systems
started selling UNIX
UNIX
System V . Believing that it could not compete with AT"> The original MS- DOS
DOS
advertisement in 1981.

On microcomputers based on the Intel 8086 and 8088 processors, including the IBM PC
IBM PC
and clones, the initial competition to the PC DOS/MS- DOS
DOS
line came from Digital Research , whose CP/M
CP/M
operating system had inspired MS-DOS. In fact, there remains controversy as to whether Q DOS
DOS
was more or less plagiarised from early versions of CP/M code. Digital Research released CP/M-86 a few months after MS-DOS, and it was offered as an alternative to MS- DOS
DOS
and Microsoft's licensing requirements, but at a higher price. Executable programs for CP/M-86 and MS- DOS
DOS
were not interchangeable with each other; many applications were sold in both MS- DOS
DOS
and CP/M-86 versions until MS- DOS
DOS
became preponderant (later Digital Research operating systems could run both MS- DOS
DOS
and CP/M-86 software). MS- DOS
DOS
originally supported the simple .COM , which was modelled after a similar but binary incompatible format known from CP/M-80
CP/M-80
. CP/M-86 instead supported a relocatable format using the file extension .CMD to avoid name conflicts with CP/M-80
CP/M-80
and MS- DOS
DOS
.COM files. MS- DOS
DOS
version 1.0 added a more advanced relocatable . EXE executable file format.

Most of the machines in the early days of MS- DOS
DOS
had differing system architectures and there was a certain degree of incompatibility, and subsequently vendor lock-in . Users who began using MS- DOS
DOS
with their machines were compelled to continue using the version customized for their hardware, or face trying to get all of their proprietary hardware and software to work with the new system.

In the business world the 808x-based machines that MS- DOS
DOS
was tied to faced competition from the Unix
Unix
operating system which ran on many different hardware architectures. Microsoft
Microsoft
itself sold a version of Unix
Unix
for the PC called Xenix
Xenix
.

In the emerging world of home users, a variety of other computers based on various other processors were in serious competition with the IBM PC: the Apple II
Apple II
, early Apple Macintosh
Apple Macintosh
, the Commodore 64 and others did not use the 808x processor; many 808x machines of different architectures used custom versions of MS-DOS. At first all these machines were in competition. In time the IBM PC
IBM PC
hardware configuration became dominant in the 808x market as software written to communicate directly with the PC hardware without using standard operating system calls ran much faster, but on true PC-compatibles only. Non-PC-compatible 808x machines were too small a market to have fast software written for them alone, and the market remained open only for IBM PCs and machines that closely imitated their architecture, all running either a single version of MS- DOS
DOS
compatible only with PCs, or the equivalent IBM PC
IBM PC
DOS. Most clones cost much less than IBM-branded machines of similar performance, and became widely used by home users, while IBM PCs had a large share of the business computer market.

Microsoft
Microsoft
and IBM together began what was intended as the follow-on to MS-DOS/PC DOS, called OS/2 . When OS/2 was released in 1987, Microsoft
Microsoft
began an advertising campaign announcing that " DOS
DOS
is Dead" and stating that version 4 was the last full release. OS/2 was designed for efficient multi-tasking (as was standard in operating systems since 1963) and offered a number of advanced features that had been designed together with similar look and feel ; it was seen as the legitimate heir to the "kludgy" DOS
DOS
platform.

MS- DOS
DOS
had grown in spurts, with many significant features being taken or duplicated from Microsoft's other products and operating systems. MS- DOS
DOS
also grew by incorporating, by direct licensing or feature duplicating, the functionality of tools and utilities developed by independent companies, such as Norton Utilities , PC Tools ( Microsoft
Microsoft
Anti-Virus ), QEMM expanded memory manager, Stacker disk compression , and others.

During the period when Digital Research was competing in the operating system market some computers, like Amstrad PC1512
Amstrad PC1512
, were sold with floppy disks for two operating systems (only one of which could be used at a time), MS- DOS
DOS
and CP/M-86 or a derivative of it. Digital Research produced DOS
DOS
Plus , which was compatible with MS-DOS 2.11, supported CP/M-86 programs, had additional features including multi-tasking, and could read and write disks in CP/M
CP/M
and MS-DOS format.

While OS/2 was under protracted development, Digital Research released the MS- DOS
DOS
compatible DR DOS
DOS
5.0, which included features only available as third-party add-ons for MS-DOS. Unwilling to lose any portion of the market, Microsoft
Microsoft
responded by announcing the "pending" release of MS- DOS
DOS
5.0 in May 1990. This effectively killed most DR DOS
DOS
sales until the actual release of MS- DOS
DOS
5.0 in June 1991. Digital Research brought out DR DOS
DOS
6.0, which sold well until the "pre-announcement" of MS- DOS
DOS
6.0 again stifled the sales of DR DOS.

Microsoft
Microsoft
had been accused of carefully orchestrating leaks about future versions of MS- DOS
DOS
in an attempt to create what in the industry is called FUD (fear, uncertainty, and doubt ) regarding DR DOS. For example, in October 1990, shortly after the release of DR DOS
DOS
5.0, and long before the eventual June 1991 release of MS- DOS
DOS
5.0, stories on feature enhancements in MS- DOS
DOS
started to appear in InfoWorld and PC Week. Brad Silverberg , then Vice President of Systems Software at Microsoft
Microsoft
and general manager of its Windows
Windows
and MS- DOS
DOS
Business Unit, wrote a forceful letter to PC Week (5 November 1990), denying that Microsoft
Microsoft
was engaged in FUD tactics ("to serve our customers better, we decided to be more forthcoming about version 5.0") and denying that Microsoft
Microsoft
copied features from DR DOS:

"The feature enhancements of MS- DOS
DOS
version 5.0 were decided and development was begun long before we heard about DR DOS
DOS
5.0. There will be some similar features. With 50 million MS- DOS
DOS
users, it shouldn't be surprising that DRI has heard some of the same requests from customers that we have." – (Schulman et al. 1994).

The pact between Microsoft
Microsoft
and IBM to promote OS/2 began to fall apart in 1990 when Windows 3.0 became a marketplace success. Much of Microsoft's further contributions to OS/2 also went into creating a third GUI
GUI
replacement for DOS, Windows NT
Windows NT
.

IBM, which had already been developing the next version of OS/2, carried on development of the platform without Microsoft
Microsoft
and sold it as the alternative to DOS
DOS
and Windows.

LEGAL ISSUES

As a response to Digital Research 's DR DOS
DOS
6.0 , which bundled SuperStor disk compression, Microsoft
Microsoft
opened negotiations with Stac Electronics , vendor of the most popular DOS
DOS
disk compression tool, Stacker. In the due diligence process, Stac engineers had shown Microsoft
Microsoft
part of the Stacker source code. Stac was unwilling to meet Microsoft's terms for licensing Stacker and withdrew from the negotiations. Microsoft
Microsoft
chose to license Vertisoft's DoubleDisk, using it as the core for its DoubleSpace disk compression.

MS- DOS
DOS
6.0 and 6.20 were released in 1993, both including the Microsoft
Microsoft
DoubleSpace disk compression utility program. Stac successfully sued Microsoft
Microsoft
for patent infringement regarding the compression algorithm used in DoubleSpace. This resulted in the 1994 release of MS- DOS
DOS
6.21, which had disk compression removed. Shortly afterwards came version 6.22, with a new version of the disk compression system, DriveSpace, which had a different compression algorithm to avoid the infringing code.

Prior to 1995, Microsoft
Microsoft
licensed MS- DOS
DOS
(and Windows) to computer manufacturers under three types of agreement: per-processor (a fee for each system the company sold), per-system (a fee for each system of a particular model), or per-copy (a fee for each copy of MS-DOS installed). The largest manufacturers used the per-processor arrangement, which had the lowest fee. This arrangement made it expensive for the large manufacturers to migrate to any other operating system, such as DR DOS. In 1991, the U.S. government Federal Trade Commission began investigating Microsoft's licensing procedures, resulting in a 1994 settlement agreement limiting Microsoft
Microsoft
to per-copy licensing. Digital Research did not gain by this settlement, and years later its successor in interest, Caldera , sued Microsoft for damages in the Caldera v. Microsoft
Microsoft
lawsuit. It was believed that the settlement ran in the order of $150 million, but was revealed in November 2009 with the release of the Settlement Agreement to be $280 million.

USE OF UNDOCUMENTED APIS

Microsoft
Microsoft
also used a variety of tactics in MS- DOS
DOS
and several of their applications and development tools that, while operating perfectly when running on genuine MS- DOS
DOS
(and PC DOS), would break when run on another vendor's implementation of DOS. Notable examples of this practice included:

* Microsoft's QuickPascal released in early 1989 was the first MS product that checked for MS- DOS
DOS
by modifying the program's Program Segment Prefix using undocumented DOS
DOS
functions, and then checked whether or not the associated value changed in a fixed position within the DOS
DOS
data segment (also undocumented). This check also made it into later MS products, including Microsoft
Microsoft
QuickC v2.5, Programmer's Workbench and Microsoft
Microsoft
C v6.0.

* The AARD code , a block of code in the windows launcher (WIN.COM) and a few other system files of Windows
Windows
3.1. It was XOR encrypted, self-modifying , and deliberately obfuscated, using various undocumented DOS
DOS
structures and functions to determine whether or not Windows
Windows
really was running on MS-DOS. In the beta versions, it displayed an "error" message if the test for genuine MS- DOS
DOS
failed, prompting the user to abort or continue, with abort the default. In the final release version, the code still ran, but the message and prompt were disabled by an added flag byte, rendering it (probably) ineffectual.

* Note that the Windows 3.0 beta code only gave a warning that Windows
Windows
would not operate properly on a "foreign" OS. It did, in fact, run just fine on DR DOS
DOS
6.0.

* Interrupt routines called by Windows
Windows
to inform MS- DOS
DOS
that Windows
Windows
is starting/exiting, information that MS- DOS
DOS
retained in an IN_WINDOWS flag, in spite of the fact that MS- DOS
DOS
and Windows
Windows
were supposed to be two separate products.

END OF MS-DOS

As of 2011 , MS- DOS
DOS
is still used in some enterprises to run legacy applications, such as this US Navy food service management system.

With the introduction of Windows 3.0 in 1990, the easy usability of graphical user interface severely diminished the usage of MS- DOS
DOS
which is based on the command line. With the release of Windows 95 (and continuing in the Windows 9x product line through to Windows ME ), an integrated version of MS- DOS
DOS
was used for bootstrapping , troubleshooting, and backwards-compatibility with old DOS
DOS
software, particularly games, and no longer released as a standalone product. In Windows
Windows
95, the DOS, called MS- DOS
DOS
7, can be booted separately, without the Windows
Windows
GUI; this capability was retained through Windows 98 Second Edition. Windows ME removed the capability to boot its underlying MS- DOS
DOS
8.0 alone from a hard disk, but retained the ability to make a DOS
DOS
boot floppy disk (called an "Emergency Boot Disk") and can be hacked to restore full access to the underlying DOS.

In contrast to the Windows 9x series, the Windows NT
Windows NT
-derived 32-bit operating systems developed alongside the 9x series ( Windows NT
Windows NT
, 2000 , XP and newer) do not contain MS- DOS
DOS
as part of the operating system, but provide a subset of DOS
DOS
emulation to run DOS
DOS
applications and provide DOS-like command prompt windows. 64-bit versions of Windows
Windows
NT line do not provide DOS
DOS
emulation and cannot run DOS
DOS
applications natively. Windows XP
Windows XP
contains a copy of the Windows ME boot disk, stripped down to bootstrap only. This is accessible only by formatting a floppy as an "MS- DOS
DOS
startup disk". Files like the driver for the CD-ROM support were deleted from the Windows ME bootdisk and the startup files ( AUTOEXEC.BAT and CONFIG.SYS ) no longer had content. This modified disk was the base for creating the MS- DOS
DOS
image for Windows
Windows
XP. Some of the deleted files can be recovered with an undelete tool. With Windows Vista
Windows Vista
the files on the startup disk are dated 18 April 2005 but are otherwise unchanged, including the string "MS- DOS
DOS
Version 8 Copyright 1981–1999 Microsoft
Microsoft
Corp" inside COMMAND.COM . Starting with Windows
Windows
10, the ability to create a DOS startup disk has been removed.

MS- DOS
DOS
6.22 was the last standalone version produced by Microsoft
Microsoft
for Intel 8088
Intel 8088
, Intel 8086 , and Intel 80286 processors, which remain available for download via their MSDN , volume license, and OEM license partner websites, for customers with valid login credentials. MS- DOS
DOS
is still used in embedded x86 systems due to its simple architecture and minimal memory and processor requirements, though some current products have switched to the still-maintained open-source alternative Free DOS
DOS
.

WINDOWS COMMAND-LINE INTERFACE

All versions of Microsoft
Microsoft
Windows
Windows
have had an MS-DOS-like command-line interface (CLI) called Command Prompt . This could run many DOS
DOS
and variously Win32, OS/2 1.x and POSIX command line utilities in the same command-line session, allowing piping between commands. The user interface, and the icon up to Windows
Windows
2000, followed the native MS- DOS
DOS
interface.

The 16-bit versions of Windows
Windows
(up to 3.11) ran as a Graphical User Interface (GUI) on top of MS-DOS. With Windows 95 , 98, 98 SE and ME, the MS- DOS
DOS
part was (superficially) integrated, treating both operating systems as a complete package, though the DOS
DOS
component could actually stand alone. The command line accessed the DOS
DOS
command line (usually COMMAND.COM) through a Windows
Windows
module (WINOLDAP.MOD).

A new line of Windows, ( Windows
Windows
NT), boot through a kernel whose sole purpose is to load Windows. One cannot run Win32 applications in the loader system in the manner that OS/2, UNIX
UNIX
or Consumer Windows
Windows
can launch character-mode sessions.

The command session permits running of various supported command line utilities from Win32, MS-DOS, OS/2 1.x and POSIX. The emulators for MS-DOS, OS/2 and POSIX use the host's window in the same way that Win16 applications use the Win32 explorer. Using the host's window allows one to pipe output between emulations.

The MS- DOS
DOS
emulation is done through the NTVDM (NT Virtual DOS Machine). This is a modified SoftPC (a former product similar to VirtualPC), running a modified MS- DOS
DOS
5 (NTIO.SYS and NTDOS.SYS). The output is handled by the console DLLs, so that the program at the prompt (CMD.EXE, 4NT.EXE, TCC.EXE), can see the output. 64-bit Windows does not have either the DOS
DOS
emulation, or the DOS
DOS
commands (EDIT, DEBUG, EDLIN ), that come with 32-bit Windows.

The DOS
DOS
version returns 5.00 or 5.50, depending on which API function is used to determine it. Utilities from MS- DOS
DOS
5.00 run in this emulation without modification. The very early beta programs of NT show MS- DOS
DOS
30.00, but programs running in MS- DOS
DOS
30.00 would assume that OS/2 was in control.

The OS/2 emulation is handled through OS2SS. EXE and OS2.EXE, and DOSCALLS.DLL. OS2. EXE is a version of the OS/2 shell (CMD.EXE), which passes commands down to the OS2SS.EXE, and input-output to the Windows NT shell. Windows 2000 was the last version of NT to support OS/2. The emulation is OS/2 1.30.

POSIX is emulated through the POSIX shell, but no emulated shell; the commands are handled directly in CMD.EXE.

The Command Prompt is often called the MS- DOS
DOS
prompt. In part, this was the official name for it in Windows 9x and early versions of Windows NT
Windows NT
(NT 3.5 and earlier), and in part because the SoftPC emulation of DOS
DOS
redirects output into it. Actually only COMMAND.COM and other 16-bit commands run in an NTVDM with AUTOEXEC.NT and CONFIG.NT initialisation determined by _default.pif , optionally permitting the use of Win32 console applications and internal commands with an NTCMDPROMPT directive.

Win32 console applications use CMD. EXE as their command prompt shell. This confusion does not exist under OS/2 because there are separate DOS
DOS
and OS/2 prompts, and running a DOS
DOS
program under OS/2 will launch a separate DOS
DOS
window to run the application.

All versions of Windows
Windows
for Itanium (no longer sold by Microsoft) and x86-64 architectures no longer include the NTVDM and can therefore no longer natively run MS- DOS
DOS
or 16-bit Windows
Windows
applications. There are alternatives in the form of virtual machine emulators such as Microsoft's own Virtual PC , as well as VMware
VMware
, DOSBox , and others.

LEGACY COMPATIBILITY

From 1983 onwards, various companies worked on graphical user interfaces (GUIs) capable of running on PC hardware. However, this required duplicated effort and did not provide much consistency in interface design (even between products from the same company).

Later, in 1985, Microsoft
Microsoft
Windows
Windows
was released as Microsoft's first attempt at providing a consistent user interface (for applications). The early versions of Windows
Windows
ran on top of MS-DOS. At first Windows met with little success, but this was also true for most other companies' efforts as well, for example GEM . After version 3.0, Windows
Windows
gained market acceptance.

Windows 9x used the DOS
DOS
boot process to launch into protected mode. Basic features related to the file system, such as long file names, were only available to DOS
DOS
when running as a subsystem of Windows. Windows NT
Windows NT
runs independently of DOS
DOS
but includes NTVDM , a component for simulating a DOS
DOS
environment for legacy applications.

RELATED SYSTEMS

Main article: DOS
DOS

MS- DOS
DOS
compatible systems include:

* IBM PC
IBM PC
DOS
DOS
* DR DOS
DOS
, Novell DOS
DOS
, Open DOS
DOS
* Free DOS
DOS
* PTS- DOS
DOS
* ROM- DOS
DOS

Microsoft
Microsoft
manufactured IBM PC
IBM PC
DOS
DOS
for IBM. It and MS- DOS
DOS
were identical products that eventually diverged starting with PC DOS version 6.1.

Digital Research 's DR- DOS
DOS
is sometimes regarded as a clone of MS-DOS, but it did not follow Microsoft's version numbering scheme. For example, MS- DOS
DOS
4, released in July 1988, was followed by DR DOS 5.0 in May 1990. MS- DOS
DOS
5.0 came in April 1991, with DR DOS
DOS
6.0 being released the following June.

These products are collectively referred to as "DOS," even though "Disk Operating System" is a generic term used on other systems unrelated to the x86 and IBM PC. "MS-DOS" can also be a generic reference to DOS
DOS
on IBM PC compatible
IBM PC compatible
computers.

What made the difference in the end was Microsoft's control of the Windows
Windows
platform and their programming practices which intentionally made Windows
Windows
appear as if it ran poorly on competing versions of DOS. Digital Research had to release interim releases to circumvent Windows limitations inserted artificially, designed specifically to provide Microsoft
Microsoft
with an unfair competitive advantage.

SEE ALSO

* 4 DOS
DOS
– designed to replace the default command interpreter COMMAND.COM * Bad command or file name * DOSBox * History of Microsoft
Microsoft
Windows
Windows
* List of DOS
DOS
commands * MS- DOS
DOS
API * Towns OS
Towns OS
– an MS- DOS
DOS
adaptation by Fujitsu
Fujitsu
for FM Towns * Tao Ex DOS
DOS
– commercial solution for DOS
DOS
software on new Windows systems. * Timeline of DOS
DOS
operating systems * Win32 console – an environment provided by Windows
Windows
operating systems to support character-mode applications

NOTES

* ^ Confirmed that there was Compaq Personal Computer DOS
DOS
3.31 aside from MS- DOS
DOS
3.31. * ^ Up to 512 MiB only. * ^ Only if boot record of source floppy disk contains volume serial number also. * ^ One for the floppy disk, one for a bootable partition of a hard disk, the other two are not known.

REFERENCES

* ^ Paterson, Tim (June 1983). "An Inside Look at MS-DOS". Seattle Computer Products . Seattle. Archived from the original on 2017-05-06.

* ^ A B Paterson, Tim (2013-12-19) . " Microsoft
Microsoft
DOS
DOS
V1.1 and V2.0: /msdos/v11source/MSDOS.ASM". Computer History Museum
Computer History Museum
, Microsoft
Microsoft
. Retrieved 2014-03-25. (NB. While the publishers claim this would be MS- DOS
DOS
1.1 and 2.0, it actually is SCP MS- DOS
DOS
1.25 and a mixture of Altos MS- DOS
DOS
2.11 and TeleVideo PC DOS
DOS
2.11 .) * ^ A B Shustek, Len (24 March 2014). " Microsoft
Microsoft
MS- DOS
DOS
early source code". Software Gems: The Computer History Museum
Computer History Museum
Historical Source Code Series. Retrieved 2014-03-29. (NB. While the author claims this would be MS- DOS
DOS
1.1 and 2.0, it actually is SCP MS-DOS 1.25 and a mixture of Altos MS- DOS
DOS
2.11 and TeleVideo PC DOS
DOS
2.11 .) * ^ A B Levin, Roy (25 March 2014). " Microsoft
Microsoft
makes source code for MS- DOS
DOS
and Word for Windows
Windows
available to public". Official Microsoft
Microsoft
Blog. Retrieved 2014-03-29. (NB. While the author claims this would be MS- DOS
DOS
1.1 and 2.0, it actually is SCP MS- DOS
DOS
1.25 and a mixture of Altos MS- DOS
DOS
2.11 and TeleVideo PC DOS
DOS
2.11 .) * ^ A B C "MS-DOS: A Brief Introduction". The Linux
Linux
Information Project. Archived from the original on 2017-12-14. Retrieved 2017-12-14. * ^ "Obsolete Products Life-Cycle Policy". Support. Microsoft
Microsoft
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