Home      Discussion      Topics      Dictionary      Almanac
Signup       Login
MS-DOS

MS-DOS

Overview
MS-DOS is an operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

 for x86-based personal computers. It was the most commonly used member of the DOS
DOS
DOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...

 family of operating systems, and was the main operating system for IBM PC compatible
IBM PC compatible
IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC architecture, facilitated by various manufacturers' ability to...

 personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating systems offering a graphical user interface
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...

 (GUI), in particular by various generations of the Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

 operating system.

MS-DOS grew from a 1981 request by IBM for an operating system for its IBM PC
IBM PC
The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...

 range of personal computers.
Discussion
Ask a question about 'MS-DOS'
Start a new discussion about 'MS-DOS'
Answer questions from other users
Full Discussion Forum
 
Unanswered Questions
Recent Discussions
Encyclopedia
MS-DOS is an operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

 for x86-based personal computers. It was the most commonly used member of the DOS
DOS
DOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...

 family of operating systems, and was the main operating system for IBM PC compatible
IBM PC compatible
IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC architecture, facilitated by various manufacturers' ability to...

 personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating systems offering a graphical user interface
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...

 (GUI), in particular by various generations of the Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

 operating system.

MS-DOS grew from a 1981 request by IBM for an operating system for its IBM PC
IBM PC
The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...

 range of personal computers. Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...

 quickly bought the rights to QDOS (Quick and Dirty Operating System), also known as 86-DOS, from Seattle Computer Products
Seattle Computer Products
Seattle Computer Products was a Seattle, Washington microcomputer hardware company which was one of the first manufacturers of computer systems based on the 16-bit Intel 8086 processor...

, and began work on modifying it to meet IBM's specification. The first edition, MS-DOS 1.0, was launched in 1982. The version shipped with IBM's PCs was called PC DOS. Although MS-DOS and PC-DOS were initially developed in parallel by Microsoft and IBM, the two products eventually went their separate ways.

During its life, several competing products
Comparison of x86 DOS operating systems
- Historical and licensing information :Originally MS-DOS was designed to be an operating system that could run on any computer with a 8086-family microprocessor. It competed with other Operating Systems written for such computers, such as CP/M-86 and UCSD Pascal. Each computer would have its own...

 were released for the x86 platform, and MS-DOS itself would go through eight versions, until development ceased in 2000. Ultimately it was the key product in Microsoft's growth from a programming language
Programming language
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....

s 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 ran as a GUI.

History


MS-DOS was a renamed form of 86-DOS – informally known as the Quick-and-Dirty Operating System or Q-DOS – owned by Seattle Computer Products
Seattle Computer Products
Seattle Computer Products was a Seattle, Washington microcomputer hardware company which was one of the first manufacturers of computer systems based on the 16-bit Intel 8086 processor...

, written by Tim Paterson
Tim Paterson
Tim Paterson is an American computer programmer, best known as the original author of MS-DOS, the most widely used personal computer operating system in the 1980s....

. Microsoft needed an operating system for the then-new Intel 8086
Intel 8086
The 8086 is a 16-bit microprocessor chip designed by Intel between early 1976 and mid-1978, when it was released. The 8086 gave rise to the x86 architecture of Intel's future processors...

 but it had none available, so it bought 86-DOS for $75,000 and licensed it as its own then released a version of it as MS-DOS 1.0. Development started in 1981, and MS-DOS 1.0 was released with the IBM PC in 1982 (86-DOS, in turn, was written as a clone of CP/M, with the exception of how drives internal to the system were referenced. In CP/M the hard drive was referenced with A:, where as 86-DOS referred to the hard drive with C:/.Tim Paterson is considered the original author of DOS and he is called "The Father of DOS".Notice that he is called the author of Dos and not the author of MS-DOS

Originally MS-DOS was designed to be an operating system 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
CP/M
CP/M was a mass-market operating system created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc...

, and with MS-DOS emulating the same solution as CP/M to adapt for different hardware platforms. To this end, MS-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
OEM
OEM means the original manufacturer of a component for a product, which may be resold by another company.OEM may also refer to:-Computing:* OEM font, or OEM-US, the original character set of the IBM PC, circa 1981...

 would use a development kit provided by Microsoft to build a version of MS-DOS with their basic I/O drivers and a standard 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 [compatible] machine. Some machines, like the Tandy 2000
Tandy 2000
The Tandy 2000 was a personal computer introduced by Radio Shack in late 1983 which used the 8 MHz Intel 80186 microprocessor. By comparison, the IBM PC XT used the older 4.7 MHz 8088 processor, and the IBM PC AT would later use the newer 6 MHz Intel 80286...

, were MS-DOS compatible but not IBM-compatible, so they could only run software written exclusively for MS-DOS without dependence on the peripheral hardware of the IBM PC architecture.

This design would have worked well for compatibility, if application programs had only used MS-DOS services to perform device I/O, and indeed the same design philosophy is embodied in 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 for a fixed hardware platform was needed for the market. This version is the version of MS-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 the same-numbered standard version for the IBM PC, with a few notable exceptions.

While MS-DOS appeared on PC clones
IBM PC compatible
IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC architecture, facilitated by various manufacturers' ability to...

, true IBM computers used PC DOS, a rebranded form of MS-DOS. Ironically, the dependence on IBM-compatible hardware caused major problems for the computer industry when the original design had to be changed. For example, the original design could support no more than 640 kilobyte
Kilobyte
The kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...

s of memory (the 640 kB barrier), because IBM's hardware design reserved the address space above this limit for peripheral devices and ROM. Manufacturers had to develop complicated schemes (EMS
Expanded memory
In DOS memory management, expanded memory is a system of bank switching introduced April 24, 1985 that provided additional memory to DOS programs beyond the limit of conventional memory. Expanded memory uses parts of the address space normally dedicated to communication with peripherals for program...

 and XMS, and other minor proprietary ones) to access additional memory. This limitation would not have been a problem if the original idea of interfacing with hardware through MS-DOS had endured. (However, MS-DOS was also a real-mode operating system, and the Intel x86 architecture only supports up to 1 MB of memory address space in Real Mode, even on Pentium 4 and later x86 CPUs, so for simple access to megabytes of memory, MS-DOS would have had to be rewritten to run in 80286 or 80386 Protected Mode.) Also, Microsoft originally described MS-DOS as "an operating system for Intel 8086-based microcomputers", and the 8086 CPU (and its cousin the 8088) itself has only 1 MiB of total memory address space.

Versions



Microsoft licensed or released versions of MS-DOS under different names like SB-DOS or Z-DOS
Z-DOS
Z-DOS was a version of Microsofts generic MS-DOS specifically written to run on the hardware of the Zenith Z-100 personal computer.The Z-100 used a 8086-family microprocessor, but otherwise had a completely different internal architecture than the IBM PC.At the time Microsofts MS-DOS wasn't...

. Competitors released DOS systems such as DR-DOS
DR-DOS
DR-DOS is an MS-DOS-compatible operating system for IBM PC-compatible personal computers, originally developed by Gary Kildall's Digital Research and derived from Concurrent PC DOS 6.0, which was an advanced successor of CP/M-86...

 and PTS-DOS
PTS-DOS
PTS-DOS is a disk operating system, a DOS clone, developed in Russia by PhysTechSoft.- History and versions :PhysTechSoft was formed in 1991 in Moscow, Russia by graduates and members of MIPT, informally known as PhysTech. At the end of 1993, PhysTechSoft released the first commercially available...

 that could also run DOS applications.
The following versions of MS-DOS were released to the public:
  • MS-DOS 1.x
    • Version 1.12 (OEM) - Compaq release of PC-DOS 1.10
    • Version 1.19 (OEM) - Zenith OEM
    • Version 1.25 (OEM) - Microsoft repackaging of PC-DOS 1.10
  • MS-DOS 2.x - Support for 10 MB hard disk drives and tree-structure filing system
    • Version 2.0 (OEM)
    • Version 2.1 (OEM)
    • Version 2.11 (OEM)
    • Version 2.2 (OEM)
    • Version 2.21 (OEM)
  • MS-DOS 3.x
    • Version 3.0 (OEM) - Support for larger hard disk drives
    • Version 3.1 (OEM) - Support for Microsoft Networks
    • Version 3.2 (OEM)
    • Version 3.21 (OEM)
    • Version 3.25 (OEM)
    • Version 3.3 (OEM)
    • Version 3.3a (OEM)
    • Version 3.3r (OEM)
    • Version 3.31 (OEM) - Compaq PC DOS 3.31 supports FAT16 and larger drives.
    • Version 3.35 (OEM)
  • MS-DOS 4.x - includes a graphical/mouse interface.
    • Version 4.00 (OEM)
    • Version 4.01 (OEM) - IBM patched Version 4.00 before Microsoft released it. First version to introduce volume serial number when formatting hard disks and floppy disks (Disk duplication also).
    • Version 4.01a (OEM)
  • MS-DOS 5.x
    • Version 5.0 (Retail) - includes a full-screen editor. A number of bugs required reissue.
    • Version 5.0a (Retail) - With this release, IBM and Microsoft versions diverge.
    • Version 5.0.500 (WinNT) - All Windows NT 32-bit versions ship with files from DOS 5.0
  • MS-DOS 6.x
    • Version 6.0 (Retail) - Online help through QBASIC. Disk compression and antivirus included.
    • Version 6.1 (none) - IBM and Microsoft alternate DOS 6 versions. IBM released 6.3 also.
    • Version 6.2 (Retail) - Scandisk as replacement for CHKDSK. Fix serious bugs in DBLSPACE.
    • Version 6.21 (Retail) - Stacker-infringing DBLSPACE removed.
    • Version 6.22 (Retail) - New DRVSPACE compression.
  • MS-DOS 7.x
    • Version 7.0 (Win95,95A) - Support for long file names. New editor. JO.SYS allows booting from CD-ROM to hard disk.
    • Version 7.1 (Win95B-Win98SE) - Support for FAT32 file system. Last general purpose DOS to load Windows.
  • MS-DOS 8.0
    • Version 8.0 (WinME) - Integrated drivers for faster Windows loading. Four different kernels (IO.SYS) observed.
    • Version 8.0 (WinXP) - DOS boot disks created by XP and later contain files from WinME. The internal command prompt still reports version 5.0


Microsoft DOS was released through the OEM channel, until DRI released DR-DOS 5.0 as a retail upgrade. With PC-DOS 5.00.1, the IBM-Microsoft agreement started to end, and IBM entered the retail DOS market with IBMDOS 5.00.1, 5.02, 6.00 and PC-DOS 6.10, 6.30, 7.00 and 2000.

A number of beta versions have surfaced on the Internet, such as 5.0 (a ten-diskette version in the same vein as 4.0), 7.00 beta 1 (based on 6.00), 7.00 beta 2 (based on 6.22). An OEM source package for 6.00, and a late release of 6.2(b) have also been seen. These are not retail versions.

Competition



On microcomputers based on the Intel 8086
Intel 8086
The 8086 is a 16-bit microprocessor chip designed by Intel between early 1976 and mid-1978, when it was released. The 8086 gave rise to the x86 architecture of Intel's future processors...

 and 8088
Intel 8088
The Intel 8088 microprocessor was a variant of the Intel 8086 and was introduced on July 1, 1979. It had an 8-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and the one megabyte address range were unchanged, however...

 processors, including the IBM PC and clones, the initial competition to the PC DOS/MS-DOS line came from Digital Research
Digital Research
Digital Research, Inc. was the company created by Dr. Gary Kildall to market and develop his CP/M operating system and related products. It was the first large software company in the microcomputer world...

, whose CP/M
CP/M
CP/M was a mass-market operating system created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc...

 operating system had inspired MS-DOS. In fact, there remains controversy as to whether Q-DOS was more or less plagiarised from early versions of CP/M code. Digital Research released CP/M-86
CP/M-86
CP/M-86 was a version of the CP/M operating system that Digital Research made for the Intel 8086 and Intel 8088. The commands are those of CP/M-80. Executable files used the relocatable .CMD file format...

 a few months after MS-DOS, and it was offered as an alternative to MS-DOS and Microsoft's licensing requirements, but at a higher price. Executable programs for CP/M-86 and MS-DOS were not interchangeable with each other; much applications software was sold in both MS-DOS and CP/M-86 versions until MS-DOS became preponderant (later Digital Research operating systems could run both MS-DOS and CP/M-86 software). MS-DOS supported the simple .COM
COM file
In many computer operating systems, a COM file is a type of executable file; the name is derived from the file name extension .COM. Originally, the term stood for "Command file", a text file containing commands to be issued to the operating system , on many of the Digital Equipment Corporation mini...

 and the more advanced relocatable .EXE
EXE
EXE is the common filename extension denoting an executable file in the DOS, OpenVMS, Microsoft Windows, Symbian, and OS/2 operating systems....

 executable file formats; CP/M-86 a relocatable format using the file extension .CMD
CMD file (CP/M)
In CP/M-86, CMD is the filename extension used by executable programs. It corresponds to COM in CP/M-80 and EXE in DOS. The same extension is used by Microsoft Windows for unrelated batch files.-Binary format:...

.

Most of the machines in the early days of MS-DOS had differing system architectures and there was a certain degree of incompatibility, and subsequently vendor lock-in
Vendor lock-in
In economics, vendor lock-in, also known as proprietary lock-in or customer lock-in, makes a customer dependent on a vendor for products and services, unable to use another vendor without substantial switching costs...

. Users who began using MS-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 was tied to faced competition from the Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...

 operating system which ran on many different hardware architectures. Microsoft itself sold a version of Unix for the PC called Xenix
Xenix
Xenix is a version of the Unix operating system, licensed to Microsoft from AT&T in the late 1970s. The Santa Cruz Operation later acquired exclusive rights to the software, and eventually superseded it with SCO UNIX ....

.

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
The Apple II is an 8-bit home computer, one of the first highly successful mass-produced microcomputer products, designed primarily by Steve Wozniak, manufactured by Apple Computer and introduced in 1977...

, early Apple Macintosh, the Commodore 64
Commodore 64
The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595...

 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 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 compatible only with PCs, or the equivalent 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 and IBM together began what was intended as the follow-on to MS/PC DOS, called OS/2
OS/2
OS/2 is a computer operating system, initially created by Microsoft and IBM, then later developed by IBM exclusively. The name stands for "Operating System/2," because it was introduced as part of the same generation change release as IBM's "Personal System/2 " line of second-generation personal...

. When OS/2 was released in 1987, Microsoft began an advertising campaign announcing that "DOS is Dead" and stating that version 4 was the last full release. OS/2 was designed for efficient multi-tasking — an IBM speciality derived from deep experience with mainframe operating systems — and offered a number of advanced features that had been designed together with similar look and feel
Look and feel
In software design, look and feel is a term used in respect of a graphical user interface and comprises aspects of its design, including elements such as colors, shapes, layout, and typefaces , as well as the behavior of dynamic elements such as buttons, boxes, and menus...

; it was seen as the legitimate heir to the "kludgy" DOS platform.

MS-DOS had grown in spurts, with many significant features being taken or duplicated from Microsoft's other products and operating systems. MS-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
Norton Utilities
Norton Utilities is a utility software suite designed to help analyze, configure, optimize and maintain the computer. The current version 15 of Norton Utilities Premier Edition for Windows XP/Vista/7 was released December 27, 2010....

, PC Tools (Microsoft Anti-Virus
Microsoft Anti-Virus
Microsoft Anti-Virus was an antivirus program introduced by Microsoft for its MS-DOS operating system. The program first appeared in MS-DOS version 6.0...

), QEMM
QEMM
Quarterdeck Expanded Memory Manager , was a memory manager produced by Quarterdeck Office Systems in the late 1980s through late 1990s. It was the most popular memory manager for the MS-DOS and other DOS operating systems.-QEMM product ranges:QRAM: A memory manager for 286 or higher CPU. It...

 expanded memory manager, Stac
Lempel–Ziv–Stac
Lempel-Ziv-Stac is a lossless data compression algorithm that uses a combination of the LZ77 sliding-window compression algorithm and fixed Huffman coding. It was originally developed by Stac Electronics for hard disk compression, and sold as the Stacker disk compression software. It was later...

ker disk compression
Disk compression
A disk compression software utility increases the amount of information that can be stored on a hard disk drive of given size. Unlike a file compression utility which compresses only specified files - and which requires the user designate the files to be compressed - a disk compression utility...

, and others.

During the period when Digital Research was competing in the operating system market some computers, like Amstrad PC-1512
PC-1512
The Amstrad PC1512 was Amstrad's mostly IBM PC-compatible computer system, first manufactured in 1986. It was later succeeded by the PC1640.It launched for £499 and sold very well, as it was one of the first cheap PCs in Europe...

, were sold with floppy disks for two operating systems (only one of which could be used at a time), MS-DOS and CP/M-86 or a derivative of it. Digital Research produced DOS Plus
DOS Plus
DOS Plus is an operating system written by Digital Research, first released in 1985. It can be seen as an intermediate step between CP/M-86 and DR-DOS....

, 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 and MS-DOS format.

While OS/2 was under protracted development, Digital Research released the MS-DOS compatible DR-DOS
DR-DOS
DR-DOS is an MS-DOS-compatible operating system for IBM PC-compatible personal computers, originally developed by Gary Kildall's Digital Research and derived from Concurrent PC DOS 6.0, which was an advanced successor of CP/M-86...

 5, which included features only available as third-party add-ons for MS-DOS (and still maintained considerable internal CP/M-86 compatibility). Unwilling to lose any portion of the market, Microsoft responded by announcing the "pending" release of MS-DOS 5.0 in May 1990. This effectively killed most DR-DOS sales until the actual release of MS-DOS 5.0 in June 1991. Digital Research brought out DR-DOS 6, which sold well until the "pre-announcement" of MS-DOS 6.0 again stifled the sales of DR-DOS.

Microsoft had been accused of carefully orchestrating leaks about future versions of MS-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 5.0, and long before the eventual June 1991 release of MS-DOS 5.0, stories on feature enhancements in MS-DOS started to appear in InfoWorld and PC Week. Brad Silverberg, Vice President of Systems Software at Microsoft and General Manager of its Windows and MS-DOS Business Unit, wrote a forceful letter to PC Week (November 5, 1990), denying that 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 copied features from DR-DOS:

"The feature enhancements of MS-DOS version 5.0 were decided and development was begun long before we heard about DR-DOS 5.0. There will be some similar features. With 50 million MS-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 and IBM to promote OS/2 began to fall apart in 1990 when Windows 3.0
Windows 3.0
Windows 3.0, a graphical environment, is the third major release of Microsoft Windows, and was released on 22 May 1990. It became the first widely successful version of Windows and a rival to Apple Macintosh and the Commodore Amiga on the GUI front...

 became a marketplace success. Much of Microsoft's further contributions to OS/2 also went in to creating a third GUI
Gui
Gui or guee is a generic term to refer to grilled dishes in Korean cuisine. These most commonly have meat or fish as their primary ingredient, but may in some cases also comprise grilled vegetables or other vegetarian ingredients. The term derives from the verb, "gupda" in Korean, which literally...

 replacement for DOS, Windows NT
Windows NT
Windows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. It was a powerful high-level-language-based, processor-independent, multiprocessing, multiuser operating system with features comparable to Unix. It was intended to complement...

.

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
Digital Research
Digital Research, Inc. was the company created by Dr. Gary Kildall to market and develop his CP/M operating system and related products. It was the first large software company in the microcomputer world...

's DR DOS 6.0, which bundled SuperStor disk compression, Microsoft opened negotiations with Stac Electronics
Stac Electronics
Stac Electronics, originally incorporated as State of the Art Consulting and later shortened to Stac, Inc, was a technology company founded in 1983...

, vendor of the most popular DOS disk compression tool, Stacker. In the due diligence
Due diligence
"Due diligence" is a term used for a number of concepts involving either an investigation of a business or person prior to signing a contract, or an act with a certain standard of care. It can be a legal obligation, but the term will more commonly apply to voluntary investigations...

 process, Stac engineers had shown Microsoft part of the Stacker source code. Stac was unwilling to meet Microsoft's terms for licensing Stacker and withdrew from the negotiations. Microsoft chose to license Vertisoft's DoubleDisk, using it as the core for its DoubleSpace disk compression.

MS-DOS 6.0 and 6.20 were released in 1993, both including the Microsoft DoubleSpace disk compression utility program. Stac successfully sued Microsoft for patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

 infringement regarding the compression algorithm used in DoubleSpace. This resulted in the 1994 release of MS-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 licensed MS-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
Federal Trade Commission
The Federal Trade Commission is an independent agency of the United States government, established in 1914 by the Federal Trade Commission Act...

 began investigating Microsoft's licensing procedures, resulting in a 1994 settlement agreement limiting Microsoft to per-copy licensing. Digital Research did not gain by this settlement, and years later its successor in interest, Caldera
Caldera (company)
Caldera was a US-based software company founded in 1994 to develop Linux- and DOS-based operating system products.- Caldera :Caldera, Inc...

, sued Microsoft for damages. It was believed that the settlement ran in the order of $150m, but was revealed in November 2009 with the release of the Settlement Agreement to be $280m.

Use of undocumented APIs


Microsoft also used a variety of tactics in MS-DOS and several of their applications and development tools that, while operating perfectly when running on genuine MS-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 by modifying the program's Program Segment Prefix
    Program Segment Prefix
    The Program Segment Prefix is a data structure used in DOS systems to store the state of a program. It resembles the Zero Page in the CP/M operating system...

     using undocumented DOS functions, and then checked whether or not the associated value changed in a fixed position within the DOS data segment (also undocumented). This check also made it into later MS products, including Microsoft QuickC
    QuickC
    Microsoft QuickC was a commercial integrated development environment product engineered by Microsoft for the C programming language, superseded by Visual C++ Standard Edition. Its main competitor was Turbo C.-Version history:...

     v2.5, Programmer's Workbench and Microsoft C v6.0.
  • The (once infamous) AARD code
    AARD code
    The AARD code was a segment of obfuscated machine code that is included in several executables, including the installer and WIN.COM, in a beta release of Microsoft Windows 3.1. It was a block of code which was XOR encrypted, self-modifying, and deliberately obfuscated, using various undocumented...

    , a block of code in the Windows 3.1 beta installer. It was XOR encrypted, self-modifying
    Self-modifying code
    In computer science, self-modifying code is code that alters its own instructions while it is executing - usually to reduce the instruction path length and improve performance or simply to reduce otherwise repetitively similar code, thus simplifying maintenance...

    , and deliberately obfuscated, using various undocumented DOS structures and functions to determine whether or not Windows really was running on MS-DOS.
    • Note that the Windows 3.0 beta code only gave a warning that Windows would not operate properly on a "foreign" OS. It did in fact run just fine on DR-DOS 6.0.
  • Interrupt routines called by Windows to inform MS-DOS that Windows is starting/exiting, information that MS-DOS retained in an IN_WINDOWS flag, in spite of the fact that MS-DOS and Windows were supposed to be two separate products.

End of MS-DOS


Today, MS-DOS is rarely used for desktop computing. Since the release of Windows 95
Windows 95
Windows 95 is a consumer-oriented graphical user interface-based operating system. It was released on August 24, 1995 by Microsoft, and was a significant progression from the company's previous Windows products...

, it was integrated as a full product used for bootstrapping and troubleshooting, and no longer released as a standalone product.

Windows XP
Windows XP
Windows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops and media centers. First released to computer manufacturers on August 24, 2001, it is the second most popular version of Windows, based on installed user base...

 contains a copy of the Windows Me
Windows Me
Windows Millennium Edition, or Windows Me , is a graphical operating system released on September 14, 2000 by Microsoft, and was the last operating system released in the Windows 9x series. Support for Windows Me ended on July 11, 2006....

 boot disk, stripped down to bootstrap only. This is accessible only by formatting a floppy as an "MS-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
AUTOEXEC.BAT
AUTOEXEC.BAT is a system file found originally on DOS-type operating systems. It is a plain-text batch file that is located in the root directory of the boot device...

 and CONFIG.SYS
CONFIG.SYS
CONFIG.SYS is the primary configuration file for the DOS, OS/2 as well as similar operating systems. It is a special file that contains setup or configuration instructions for the computer system.- Usage :...

) no longer had a content. This modified disk was the base for creating the MS-DOS image for Windows XP. Some of the deleted files can be recovered with an undelete tool. With Windows Vista
Windows Vista
Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...

 the files on the startup disk are dated 18 April 2005 but are otherwise unchanged, including the string "MS-DOS Version 8 © Copyright 1981-1999 Microsoft Corp" inside COMMAND.COM
COMMAND.COM
COMMAND.COM is the filename of the default operating system shell for DOS operating systems and the default command line interpreter on Windows 95, Windows 98 and Windows Me...

.

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, volume license, and OEM license partner websites, for customers with valid login credentials.

MS-DOS is still used in embedded x86 systems due to its simple architecture, and minimal memory and processor requirements. The command line interpreter of NT
Windows NT
Windows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. It was a powerful high-level-language-based, processor-independent, multiprocessing, multiuser operating system with features comparable to Unix. It was intended to complement...

-based versions of Windows, cmd.exe
Cmd.exe
Command Prompt is the Microsoft-supplied command-line interpreter on OS/2, Windows CE and on Windows NT-based operating systems...

, maintains most of the same commands and some compatibility with DOS batch files.

The Windows command-line interface


All versions of Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

 have had an MS-DOS like command-line interface
Command-line interface
A command-line interface is a mechanism for interacting with a computer operating system or software by typing commands to perform specific tasks...

 (CLI). This could run many 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 2000, followed the native MS-DOS interface.

Consumer Windows (up to 3.11, Win9x, WinME) ran as a Graphical User Interface (GUI) running on top of MS-DOS. With Windows 95
Windows 95
Windows 95 is a consumer-oriented graphical user interface-based operating system. It was released on August 24, 1995 by Microsoft, and was a significant progression from the company's previous Windows products...

, 98, and ME the MS-DOS part was integrated to give the illusion of a new operating system (this is completely false. DOS is a 16-bit operating system that runs i86 in real mode and in no way can it support a 32-bit, protected mode OS like windows 95/98 running "on top" of it). The command line accessed the DOS command line (usually command.com), through a Windows module (winoldap.mod).

A new line of Windows, (Windows NT), boot through a kernel whose sole purpose is to load Windows: there is no character-mode boot similar to Consumer Windows, OS/2 or UNIX). The console runs as a Win32 session, with the default processor cmd.exe being a feature-reduced version of OS/2's version. The command session permits running of various supported command line utilities from Win32, MS-DOS, OS/2 1.x and POSIX.

The 32-bit Windows can run MS-DOS programs through the use of the NTVDM (NT Virtual DOS Machine). This launches a stubbed version of MS-DOS 5.0. Launching any DOS application such as the DOS command processor command.com creates a 16-bit sub-system providing most of the higher level DOS APIs for DOS programs to run and even communicate with each other.

The 32-bit CLI is usually referred to as the MS-DOS prompt. Although the binary interface is no longer that found in PC-DOS etc., it is an 'interface', and not an API. The commands typed here, the batches etc., all resemble those of MS/PC-DOS in much the same way that the Linux/UNIX commands resemble each other without underlying binary compatibility.

All versions of Windows for x86-64
X86-64
x86-64 is an extension of the x86 instruction set. It supports vastly larger virtual and physical address spaces than are possible on x86, thereby allowing programmers to conveniently work with much larger data sets. x86-64 also provides 64-bit general purpose registers and numerous other...

 and Itanium
Itanium
Itanium is a family of 64-bit Intel microprocessors that implement the Intel Itanium architecture . Intel markets the processors for enterprise servers and high-performance computing systems...

 architectures no longer include the NTVDM and can therefore no longer natively run MS-DOS or 16-bit Windows applications. There are alternatives in the form of Virtual machine
Virtual machine
A virtual machine is a "completely isolated guest operating system installation within a normal host operating system". Modern virtual machines are implemented with either software emulation or hardware virtualization or both together.-VM Definitions:A virtual machine is a software...

 emulators such as Microsoft's own Virtual PC
Microsoft Virtual PC
Windows Virtual PC is a virtualization program for Microsoft Windows. In July 2006 Microsoft released the Windows-hosted version as a free product...

, as well as VMware
VMware
VMware, Inc. is a company providing virtualization software founded in 1998 and based in Palo Alto, California, USA. The company was acquired by EMC Corporation in 2004, and operates as a separate software subsidiary ....

, DOSBox
DOSBox
DOSBox is emulator software that emulates an IBM PC compatible computer running MS-DOS. It is intended especially for use with old PC games. DOSBox is free software....

, and others.

Legacy compatibility



From 1983 onwards, various companies worked on graphical user interface
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...

s (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, XTree
XTree
XTree is a file manager software originally designed for use under DOS. It was published by Executive Systems and first released on 1 April 1985, and became highly popular...

, and the Norton Shell
Norton Commander
Norton Commander was a prototypical orthodox file manager , written by John Socha and released by Peter Norton Computing . NC is a file manager which provides a text user interface on top of DOS. It was officially produced by Symantec between 1986 and 1998...

. However, this required duplication of effort and did not provide much consistency in interface design (even between products from the same company).

Later, in 1985, Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

 was released as Microsoft's first attempt at providing a consistent user interface (for applications). The early versions of Windows ran on top of MS-DOS and its clones. At first Windows met with little success, but this was also true for most other companies' efforts as well, for example GEM
Graphical Environment Manager
GEM was a windowing system created by Digital Research, Inc. for use with the CP/M operating system on the Intel 8088 and Motorola 68000 microprocessors...

. After version 3.0 (1990), Windows gained market acceptance.

Later versions (Windows 95, Windows 98 and Windows Me) used the DOS boot process to launch itself into protected mode. Basic features related to the file system, such as long file names, were only available to DOS when running as a subsystem of Windows. Windows NT
Windows NT
Windows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. It was a powerful high-level-language-based, processor-independent, multiprocessing, multiuser operating system with features comparable to Unix. It was intended to complement...

 ran independently of DOS but included a DOS subsystem so applications could run in a virtual machine
Virtual machine
A virtual machine is a "completely isolated guest operating system installation within a normal host operating system". Modern virtual machines are implemented with either software emulation or hardware virtualization or both together.-VM Definitions:A virtual machine is a software...

 under the new OS. With the latest Windows releases, even dual-booting MS-DOS is problematic as DOS may not be able to read the basic file system.

Single-user


Several similar products were produced by other companies. In the case of PC DOS and DR-DOS
DR-DOS
DR-DOS is an MS-DOS-compatible operating system for IBM PC-compatible personal computers, originally developed by Gary Kildall's Digital Research and derived from Concurrent PC DOS 6.0, which was an advanced successor of CP/M-86...

, 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. Although DR-DOS is regarded as a clone of MS-DOS, the DR-DOS versions appeared months and years before Microsoft's products. (For example, MS-DOS 4, released in July 1988, was followed by DR-DOS 5 in May 1990. MS-DOS 5 came in April 1991, with DR-DOS 6 being released the following June. MS-DOS 6 did not arrive until April 1993, with Novell DOS 7, DR-DOS' successor, following the next month.) What made the difference in the end was Microsoft's control of the Windows platform and their programming practices which intentionally made Windows appear as if it ran poorly on competing versions of DOS. Both IBM (DOS 5.02) and DRI (DOS 6 update) had to release interim releases to circumvent Windows limitations inserted artificially, designed specifically to provide Microsoft with an unfair competitive advantage.
  • PC DOS
    PC-DOS
    IBM PC DOS is a DOS system for the IBM Personal Computer and compatibles, manufactured and sold by IBM from the 1980s to the 2000s....

    ,
  • DR-DOS
    DR-DOS
    DR-DOS is an MS-DOS-compatible operating system for IBM PC-compatible personal computers, originally developed by Gary Kildall's Digital Research and derived from Concurrent PC DOS 6.0, which was an advanced successor of CP/M-86...

     / Novell DOS / OpenDOS,
  • GNU/DOS / FreeDOS
    FreeDOS
    FreeDOS is an operating system for IBM PC compatible computers. FreeDOS is made up of many different, separate programs that act as "packages" to the overall FreeDOS Project...

     / FreeDOS 32,
  • PTS-DOS
    PTS-DOS
    PTS-DOS is a disk operating system, a DOS clone, developed in Russia by PhysTechSoft.- History and versions :PhysTechSoft was formed in 1991 in Moscow, Russia by graduates and members of MIPT, informally known as PhysTech. At the end of 1993, PhysTechSoft released the first commercially available...

    .


These products are collectively referred to as DOS. However, MS-DOS can be a generic reference to DOS on IBM-PC compatible computers.

See also

  • Bad command or file name
    Bad command or file name
    "Bad command or file name" is a common error message in Microsoft's MS-DOS and some other operating systems.In command.com, the message Bad command or file name is produced if the user mistyped the first word of a command line. This first word must be either the name of built-in "command", or of an...

  • Comparison of x86 DOS operating systems
    Comparison of x86 DOS operating systems
    - Historical and licensing information :Originally MS-DOS was designed to be an operating system that could run on any computer with a 8086-family microprocessor. It competed with other Operating Systems written for such computers, such as CP/M-86 and UCSD Pascal. Each computer would have its own...

  • DOSKey
    DOSKey
    DOSKey is a utility for MS-DOS and Microsoft Windows that adds command history, macro functionality, and improved editing features to the command line interpreters COMMAND.COM and cmd.exe...

    , MS-DOS utility
  • History of Microsoft Windows
    History of Microsoft Windows
    In 1983, Microsoft announced the development of Windows, a graphical user interface for its own operating system , which had shipped for IBM PC and compatible computers since 1981...

  • List of DOS commands
  • List of Microsoft Windows versions
  • Microsoft Windows
    Microsoft Windows
    Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

  • MS-DOS API
    MS-DOS API
    The MS-DOS API is an API used originally in MS-DOS/PC-DOS, and later by other DOS systems. Most calls to the DOS API invoke software interrupt 21h . By calling INT 21h with a subfunction number in the AH processor register and other parameters in other registers, one invokes various DOS services...

  • Timeline of x86 DOS operating systems
    Timeline of x86 DOS operating systems
    This article presents a timeline of events in the history of x86 DOS operating systems from 1973 to 2006.-Important Events in DOS History:-See also:*Comparison of x86 DOS operating systems*Timeline of Microsoft Windows*Timeline of OpenBSD...

  • Win32 console
    Win32 console
    Win32 console is a text user interface implementation within the system of Windows API, which runs console applications. A Win32 console has a screen buffer and an input buffer, and is available both as a window or in text mode screen, with switching back and forth available via Alt-Enter...

     - a text-rendering system akin to MS-DOS
  • 4DOS
    4DOS
    4DOS is a command line interpreter by JP Software, designed to replace the default command interpreter COMMAND.COM in DOS and Windows 95/98/Me. The 4DOS family of programs are meant to replace the default command processor. 4OS2 and 4NT replace CMD.EXE in OS/2 and Windows NT respectively...

     - designed to replace the default command interpreter COMMAND.COM
    COMMAND.COM
    COMMAND.COM is the filename of the default operating system shell for DOS operating systems and the default command line interpreter on Windows 95, Windows 98 and Windows Me...

  • DOSBox
    DOSBox
    DOSBox is emulator software that emulates an IBM PC compatible computer running MS-DOS. It is intended especially for use with old PC games. DOSBox is free software....


External links