MS-DOS versions 1.x-7.0 unsupported as of December 31, 2001[4] MS-DOS versions 7.10 and 8.0 unsupported as of July 11, 2006.
MS-DOS (/ˌɛmˌɛsˈdɒs/em-es-DOSS; acronym forMicrosoft Disk Operating System, also known asMicrosoft DOS) is anoperating system forx86-basedpersonal computers mostly developed byMicrosoft. Collectively, MS-DOS, its rebranding asIBM PC DOS, and a few operating systems attempting to be compatible with MS-DOS, are sometimes referred to as "DOS" (which is also the generic acronym fordisk operating system). MS-DOS was the main operating system forIBM PC compatibles during the 1980s, from which point it was gradually superseded by operating systems offering agraphical user interface (GUI), in various generations of the graphicalMicrosoft Windows operating system.[5]
IBM licensed and re-released it in 1981 asPC DOS 1.0 for use in its PCs. Although MS-DOS and PC DOS were initially developed in parallel by Microsoft and IBM, the two products diverged after twelve years, in 1993, with recognizable differences in compatibility, syntax and capabilities.[5] Beginning in 1988 withDR-DOS,several competing products were released for the x86 platform.[6]
Initially, MS-DOS was targeted atIntel 8086 processors running on computer hardware usingfloppy 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 development from aprogramming 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 ran as a GUI. MS-DOS went through eight versions, until development ceased in 2000; version 6.22 from 1994 was the final standalone version, with versions 7 and 8 serving mostly in the background for loadingWindows 9x.[7]
MS-DOS was a renamed form of86-DOS[8] – owned bySeattle Computer Products, written byTim Paterson. Development of 86-DOS took only six weeks, as it was basically a clone ofDigital Research'sCP/M (for 8080/Z80 processors), ported to run on8086 processors and with two notable differences compared to CP/M: an improved disk sector buffering logic, and the introduction ofFAT12 instead of theCP/M filesystem. This first version was shipped in August 1980.[2] Microsoft, which needed an operating system for theIBM Personal Computer,[9][10] hired Tim Paterson in May 1981 and bought 86-DOS 1.10 forUS$25,000 in July of the same year.[11] Microsoft kept the version number, but renamed it MS-DOS. They also licensed MS-DOS 1.10/1.14 to IBM, which, in August 1981, offered it asPC DOS 1.0 as one of three operating systems[12] for the IBM 5150 or theIBM PC.[2]
Within a year, Microsoft licensed MS-DOS to over 70 other companies.[13] 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 forCP/M, and with MS-DOS emulating thesame 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 (theDOS BIOS), 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. TheOEM 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 theTandy 2000, were MS-DOS compatible but not IBM-compatible, so they could 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. Indeed, the same design philosophy is embodied in Windows NT (seeHardware Abstraction Layer). However, in MS-DOS' 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 computersclosely 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 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 1.x as 2.0 or vice versa)—with a few notable exceptions.
Microsoft omittedmulti-user support from MS-DOS because Microsoft'sUnix-based operating system,Xenix, was fully multi-user.[14] The company planned, over time, to improve MS-DOS so it would be almost indistinguishable from single-user Xenix, orXEDOS, which would also run on theMotorola 68000,Zilog Z8000, and theLSI-11; they would beupwardly compatible with Xenix, whichByte in 1983 described as "the multi-user MS-DOS of the future".[15][16] Microsoft advertised MS-DOS and Xenix together, listing the shared features of its "single-user OS" and "the multi-user,multi-tasking,UNIX-derived operating system", and promising easy porting between them.[17] After thebreakup of the Bell System, however,AT&T Computer Systems started sellingUNIX System V. Believing that it could not compete with AT&T in the Unix market, Microsoft abandoned Xenix, and in 1987 transferred ownership of Xenix to theSanta Cruz Operation (SCO).
Microsoft licensed or released versions of MS-DOS under different names likeLifeboat Associates "Software Bus 86"[25][26] a.k.a.SB-DOS,[6]COMPAQ-DOS,[25][26]NCR-DOS orZ-DOS[25][6] before it eventually enforced the MS-DOS name for all versions but the IBM one, which was originally called "IBM Personal Computer DOS", later shortened toIBM PC DOS. (Competitors released compatible DOS systems such asDR-DOS andPTS-DOS that could also run MS-DOS applications.)
Support for IBM's XT 10 MB hard disk drives, support up to 16 MB or 32 MBFAT12-formatted hard disk drives depending on the formatting tool shipped by OEMs,[38] user-installable device drivers, tree-structure filing system,[39] Unix-like[40] inheritable redirectable file handles,[41][42] non-multitasking child processes[43] an improved Terminate and Stay Resident (TSR) API,[44] environment variables, device driver support, FOR and GOTO loops in batch files,ANSI.SYS.[45]
Version 2.0 (OEM), First version to support double-sided 360 KB 5.25-inch floppy disks;[46][47] Release date: October 1983[48]
Version 2.02 (OEM, Compaq); Release date: November 1983[49]
Version 2.05 (OEM, international support);[25] Release date: October 1983[50]
Version 3.0 (OEM) – First version to support 5.25-inch 1.2 MB floppy drives and diskettes,FAT16 partitions up to 32 MB;[55][56] Release date: April 1985[57]
Version 3.1 (OEM) – Support for Microsoft Networks through anIFS layer,[55] remote file and printer API[58][59]
Version 3.2 (OEM) – First version to support 3.5-inch 720 KB floppy drives and diskettes andXCOPY.[46]
Version 3.10 (OEM,Multitech); Release date: May 1986[60]
Version 3.20 – First retail release (non-OEM); Release date: July 1986[61]
Version 3.21 (OEM / non-OEM); Release date: May 1987[62]
Version 3.3 (OEM) – First version to support 3.5-inch 1.44 MB floppy drives and diskettes, extended and logical partitions, directory tree copying with XCOPY, improved support for internationalization (COUNTRY.SYS),[63] networked file flush operations[64]
MS-DOS 4.0 (multitasking) and MS-DOS 4.1 – A separate branch of development with additional multitasking features, released between 3.2 and 3.3, and later abandoned. It is unrelated to any later versions, including versions 4.00 and 4.01 listed below
MS-DOS 4.x (IBM-developed) – Includes a graphical/mouse interface. It had many bugs and compatibility issues that plagued all versions of MS-DOS 4.x.[69][23]
Version 4.00 (OEM) – First version with built-in IBM/Microsoft support for hard disk partitions larger than 32 MB and up to a maximum size of 2 GB,[70]FASTOPEN/FASTSEEK,DOSSHELL, could useEMS for the disk buffers and provided EMS drivers and emulation for386-compatible processors;[71] Release date: October 1988[72]
Version 4.01 (OEM) – Microsoft-rewritten Version 4.00 released under MS-DOS label but not IBM PC DOS. First version to introduce volume serial number when formatting hard disks and floppy disks (Disk duplication also[nb 3] and when usingSYS to make a floppy disk or a hard drive partition bootable);[73] Release date: April 1989[74]
Version 5.0 (Retail) – includes afull-screen text editor. Many of the bugs and compatibility issues from MS-DOS 4.x are resolved. First version to support 3.5-inch 2.88 MB floppy drives and diskettes. TheSHARE command was not needed anymore for old DOS 1.x styleFCB fileAPI to partitions over 32 MB.[71][70] First version to get theHIMEM.SYS driver and load portions of the operating system into theupper memory area andhigh memory area. Supports up to four DOSprimary partitions, howeverFDISK cannot create more than one primary partition. Third-party tools allowed for the creation of up to four primary partitions.
AST Premium Exec DOS 5.0 (OEM) – a version for theAST Premium Exec series of notebooks with various extensions, including improved load-high and extendedcodepage support[75][76]
Version 5.0a (Retail) – With this release, IBM and Microsoft versions diverge.
MS-DOS 7.0 was included inWindows 95's first retail release. It contains support forVFAT long file names when run in a WindowsVirtual 8086 box or with anLFN driver such as DOSLFN. JO.SYS is an alternative filename of theIO.SYS kernel file and used as such for "special purposes". JO.SYS allows booting from either CD-ROM drive or hard disk. Last version to recognize only the first 8.4 GB of a hard disk. TheVER internal command reports the Windows version 4.00.950, applications through theMS-DOS API would be reported a version number of 7.00.
MS-DOS 7.1 was included inWindows 95's OEM Service Release 2 throughWindows 98 Second Edition. It added support for theFAT32 file system andlogical block addressing (LBA), and was the last version that could boot to the command line from a hard disk. The VER internal command reports the Windows version 4.00.1111, 4.10.1998, or 4.10.2222 depending on the version of Windows, while applications through the API would report version 7.10.
MS-DOS 8.0 was included inWindows Me, the last version based on MS-DOS. DOS mode was significantly altered in this release. Booting from the hard disk to a command line only was no longer permitted, AUTOEXEC.BAT and CONFIG.SYS files were no longer loaded or parsed before loading the Windows GUI; booting from floppy disk was still permitted to allow for emergency recovery. This version was included (in modified form) inWindows XP up toWindows 8.1 for creating MS-DOS startup disks. The VER internal command reports the Windows version 4.90.3000 or 5.1 when created from newer versions of Windows. Applications requesting the version through the API would report version 8.00.
Microsoft DOS was released through the OEM channel, until Digital Research releasedDR-DOS 5.0 as a retail upgrade. WithPC DOS 5.00.1, the IBM–Microsoft agreement started to end, and IBM entered the retail DOS market with IBM DOS 5.00.1, 5.02, 6.00 and PC DOS 6.1, 6.3, 7, 2000 and 7.1.
Localized versions of MS-DOS existed for different markets.[78] While Western issues of MS-DOS evolved around the same set of tools and drivers just with localized message languages and differing sets of supported codepages and keyboard layouts, some language versions were considerably different from Western issues and were adapted to run on localized PC hardware with additional BIOS services not available in Western PCs, support multiple hardware codepages for displays and printers, support DBCS, alternative input methods and graphics output. Affected issues include Japanese (DOS/V), Korean, Arabic (ADOS 3.3/5.0), Hebrew (HDOS 3.3/5.0), Russian (RDOS 4.01/5.0) as well as some other Eastern European versions of DOS.
On microcomputers based on theIntel 8086 and8088 processors, including the IBM PC and clones, the initial competition to the PC DOS/MS-DOS line came fromDigital Research, whoseCP/M operating system had inspired MS-DOS. In fact, there remains controversy as to whether QDOS was more or less plagiarized from early versions of CP/M code. Digital Research releasedCP/M-86 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; manyapplications were 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 originally supported the simple.COM, which was modeled after a similar but binary-incompatible format known fromCP/M-80. CP/M-86 instead supported arelocatable format using thefilename extension.CMD to avoid name conflicts with CP/M-80 and MS-DOS .COM files. MS-DOS version 1.0 added a more advanced relocatable .EXE executable file 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 subsequentlyvendor lock-in. 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 theUnix operating system; the latter ran on many different hardware architectures. Microsoft itself sold a version of Unix for the PC calledXenix.
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: theApple II,Mac,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 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-DOS/PC DOS, calledOS/2. 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 and offered a number of advanced features that had been designed together with similarlook and feel; 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 asNorton Utilities,PC Tools (Microsoft Anti-Virus),QEMM expanded memory manager,Stackerdisk compression, and others.
During the period when Digital Research was competing in the operating system market some computers, like theAmstrad PC1512, 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 producedDOS 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 and MS-DOS format.
While OS/2 was under protracted development, Digital Research released the MS-DOS compatibleDR-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 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 6.0, 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 inInfoWorld andPC Week.Brad Silverberg, then Vice President of Systems Software at Microsoft and general manager of its Windows and MS-DOS Business Unit, wrote a forceful letter toPC 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).[79]
The pact between Microsoft and IBM to promote OS/2 began to fall apart in 1990 whenWindows 3.0 became a marketplace success. Many of Microsoft's further contributions to OS/2 also went into creating a thirdGUI replacement for DOS,Windows NT.
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.
As a response toDigital Research'sDR DOS 6.0, which bundled SuperStor disk compression, Microsoft opened negotiations withStac Electronics, vendor of the most popular DOS disk compression tool, Stacker. In thedue diligence 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.[80]
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 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. governmentFederal Trade Commission 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, sued Microsoft for damages in theCaldera v. 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.[81]
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'sProgram Segment Prefix 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 MicrosoftQuickC v2.5, Programmer's Workbench and Microsoft C v6.0.[79]
TheAARD code, a block of code in the Windows launcher (WIN.COM) and a few other system files of Windows 3.1. It was XOR encrypted,self-modifying, and deliberately obfuscated, using various undocumented DOS structures and functions to determine whether or not Windows really was running on MS-DOS.[79] In the beta versions, it displayed an "error" message if the test for genuine MS-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.
Windows 3.0 beta release only gave a warning that Windows would not operate properly on a "foreign" OS and actually ran well 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.[79]
All versions ofMicrosoft Windows have had an MS-DOS or MS-DOS-likecommand-line interface calledMS-DOS Prompt which redirected input to MS-DOS and output from MS-DOS to the MS-DOS Prompt, or, in later versions,Command Prompt. This could run many DOS and variously Win32, OS/2 1.x andPOSIX 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. The Command Prompt introduced with Windows NT is not actually MS-DOS, but shares some commands with MS-DOS.
The16-bit versions of Windows (up to 3.11) ran as a graphical user interface (GUI) on top of MS-DOS. WithWindows 95,98, andMe, the role of MS-DOS was reduced to a boot loader according to Microsoft, with MS-DOS programs running in a virtual DOS machine within 32-bit Windows, with ability to boot directly into MS-DOS retained as a backward compatibility option for applications that required real mode access to the hardware, which was generally not possible within Windows.[82] The command line accessed the DOS command line (usuallyCOMMAND.COM) through a Windows module (WINOLDAP.MOD).[clarification needed]
Windows NT-based operating systems boot to a kernel whose purpose is to load Windows and run the system. One cannot run Win32 applications in the loader system in the manner that OS/2, UNIX or consumer versions of Windows can launch character-mode sessions.
The command session permits running 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 emulation takes place through theNTVDM (NT Virtual DOS Machine). This is a modifiedSoftPC (a former product similar toVirtualPC), running a modified MS-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 has neither the DOS emulation, nor the DOS commands EDIT,DEBUG andEDLIN that come with 32-bit Windows.
The DOS version returns 5.00 or 5.50, depending on which API function is used to determine it. Utilities from MS-DOS 5.00 run in this emulation without modification. The very early beta programs of NT show MS-DOS 30.00, but programs running in MS-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 Prompt. In part, this was the official name for it in Windows 9x and early versions of Windows NT (NT 3.5 and earlier), and in part because the SoftPC emulation of DOS redirects output into it. Actually onlyCOMMAND.COM and other 16-bit commands run in an NTVDM withAUTOEXEC.NT andCONFIG.NT initialization determined by_DEFAULT.PIF, optionally permitting the use ofWin32 console applications and internal commands with anNTCMDPROMPT directive.
Win32 console applications useCMD.EXE as their command prompt shell. This confusion does not exist under OS/2 because there are separate DOS and OS/2 prompts, and running a DOS program under OS/2 will launch a separate DOS window to run the application.
All versions of Windows forItanium (no longer sold by Microsoft) andx86-64 architectures no longer include the NTVDM and can therefore no longer natively run DOS or 16-bit Windows applications. There are alternatives such asvirtual machine emulators such as Microsoft's ownVirtual PC, as well asVMware,DOSBox etc., unofficial compatibility layers such as NTVDMx64, OTVDM (WineVDM), Win3mu and others.
As of 2011[update], MS-DOS was still used in some enterprises to runlegacy applications, such as thisUS Navy food service management system.
The introduction ofWindows 3.0 in 1990, with an easy-to-usegraphical user interface, marked the beginning of the end for the command-line driven MS-DOS. With the release ofWindows 95 (and continuing in theWindows 9x product line through toWindows Me), an integrated version of MS-DOS was used forbootstrapping, troubleshooting, and backwards-compatibility with old DOS software, particularly games, and no longer released as a standalone product.[83] In Windows 95, the DOS, called MS-DOS 7, can be booted separately, without the Windows GUI; this capability was retained through Windows 98 Second Edition. Windows Me removed the capability to boot its underlying MS-DOS 8.0 alone from a hard disk, but retained the ability to make a DOS boot floppy disk (called an "Emergency Boot Disk") and can be hacked to restore full access to the underlying DOS. On December 31, 2001, Microsoft declared all versions of MS-DOS 6.22 and older obsolete and stopped providing support and updates for the system.[4] As MS-DOS 7.0 was a part of Windows 95, support for it also ended when Windows 95 extended support ended on December 31, 2001.[84] As MS-DOS 7.10 and MS-DOS 8.0 were part of Windows 98 and Windows ME, respectively, support ended when Windows 98 and ME extended support ended on July 11, 2006, thus ending support and updates of MS-DOS from Microsoft.[85]
In contrast to the Windows 9x series, theWindows NT-derived 32-bit operating systems (Windows NT,2000,XP and newer), developed alongside the 9x series, do not contain MS-DOS compatibility as a core component of the operating system nor do they rely on it for bootstrapping, as NT was not with the level of support for legacy MS-DOS and Win16 apps that Windows 9x was,[83] but does provide limited DOS emulation calledNTVDM (NT Virtual DOS Machine) to run DOS applications and provide DOS-like command prompt windows.64-bit versions of Windows NT prior toWindows 11 (andWindows Server 2008 R2 by extension) do not provide DOS emulation and cannot run DOS applications natively.[86]Windows XP onwards contains a copy of theWindows Me 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 andCONFIG.SYS) no longer had 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.[87] When booting up an MS-DOS startup disk made with the format tool from Windows XP onwards, the version number and the VER internal command reports as "Windows Millennium" and "5.1", respectively, and not as "MS-DOS 8.0" (which was used as the base for Windows Me but never released as a stand-alone product), though the API still says Version 8.0.
The creation of the MS-DOS startup disk was then carried over to later versions of Windows, with the majority of its contents remaining unchanged from its introduction in Windows XP. When creating a DOS startup disk onWindows Vista, the files on the startup disk are dated April 18, 2005, but are otherwise unchanged from XP, including the string "MS-DOS Version 8 Copyright 1981–1999 Microsoft Corp" insideCOMMAND.COM. Windows 7, 8, and 8.1 can also create a MS-DOS startup disk, which are otherwise unchanged from XP and Vista. Starting withWindows 10, the ability to create a MS-DOS startup disk has been removed, and so either avirtual machine running MS-DOS or an older version (in a virtual machine or dual boot) must be used to format a floppy disk, or an image must be obtained from an external source. Other solutions include using DOS compatible alternatives, such asFreeDOS or even copying the required files and boot sector themselves. The last remaining components related to MS-DOS was the NTVDM component, which was removed entirely in Windows starting withWindows 11 as the operating system dropped support for 32-bit processors in favor of being solely offered in 64-bit versions only. This effectively ended any association of MS-DOS within Microsoft Windows after 36 years.
MS-DOS 6.22 was the last standalone version produced by Microsoft forIntel 8088,Intel 8086, andIntel 80286 processors, which remains available for download via theirMSDN,[88] 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, though some current products have switched to the still-maintained open-source alternativeFreeDOS.
In 2018, Microsoft released thesource code for MS-DOS 1.25 and 2.0 onGitHub, with the source code for MS-DOS 4.00 being released in the same repository six years later.[3][23] The purpose of this, according to Microsoft, is mainly for education and experimentation with historic operating systems and for new programmers to gain an understanding of how low-level software works, both historic and current. According to program manager Rich Turner, the other versions could not be open-sourced due to third-party licensing restrictions.[89]
Due to the historical nature of the software, Microsoft will not accept anypull requests to the code. Users, however, are allowed and fully encouraged tofork the repository containing the MS-DOS source code and make their own modifications, and do whatever they like with it.
From 1983 onwards, various companies worked ongraphical 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 Windows 1.0 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. At first Windows met with little success, but this was also true for most other companies' efforts as well, for exampleGEM. After version 3.0, Windows gained market acceptance.
Windows 9x used MS-DOS to boot the Windows kernel in protected mode. Basic features related to the file system, such as long file names, were only available to DOS applications when running through Windows.Windows NT runs independently of DOS but includesNTVDM, a component for simulating a DOS environment forlegacy applications. It was not included withWindows 11 as the operating system is exclusively offered in 64-bit architectures such as x86-64.
Microsoft madeIBM PC DOS for IBM. It and MS-DOS were identical products that eventually diverged starting with MS-DOS version 6.0.Digital Research did not follow Microsoft's version numbering scheme. For example, MS-DOS 4, released in July 1988, was followed by DR DOS 5.0 in May 1990. MS-DOS 5.0 came in April 1991, and DR DOS 6.0 was released the following June.[90]
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 on IBM PC compatible computers.
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, crippled the ability of other DOS makers to continue to compete with MS-DOS.[79] Digital Research had to release interim releases to circumvent Windows limitations inserted artificially,[79] designed specifically to provide Microsoft with a competitive advantage.[79]
^abcHanselman, Scott; Wilcox, Jeff (April 25, 2024)."Open sourcing MS-DOS 4.0".Microsoft Open Source Blog.Archived from the original on April 25, 2024. RetrievedApril 26, 2024.Today, in partnership with IBM and in the spirit of open innovation, we're releasing the source code to MS-DOS 4.00 under the MIT license.
^Turner, Rich (September 28, 2018)."Re-Open-Sourcing MS-DOS 1.25 and 2.0".Windows Command Line Tools For Developers.Archived from the original on September 29, 2018. RetrievedSeptember 29, 2018.
^abcCunningham, Andrew (April 26, 2024)."Microsoft open-sources infamously weird, RAM-hungry MS-DOS 4.00 release".Ars Technica.Microsoft has open-sourced another bit of computing history this week: The company teamed up with IBM to release the source code of 1988's MS-DOS 4.00, a version better known for its unpopularity, bugginess, and convoluted development history than its utility as a computer operating system.
^abcdefghAllen, Paul;Gates, Bill; King, Adrian; Larson, Chris;Letwin, Gordon;O'Rear, Bob;Paterson, Tim; Peters, Chris; Phillips, Bruce;Reynolds, Aaron; Stillmaker, Betty;Zbikowski, Mark (1986). "Technical advisors".MS-DOS (Versions 1.0-3.2) Technical Reference Encyclopedia. By Bornstein, Howard; Bredehoeft, Lawrence; Duncan, Ray; Morris, Carol; Rose, David;Socha, John; Tomlin, Jim; Vian, Kathleen; Wolverton, Van. Beley, Jim; Preppernau, Barry; Beason, Pam; Lewis, Andrea; Rygmyr, David (eds.). Microsoft Reference Library. Vol. 1 (Original withdrawn ed.). Redmond, Washington, USA:Microsoft Press.ISBN0-914845-69-1.LCCN86-8640.OCLC635600205. (xvii+1053 pages; 29 cm) (NB. This original edition contains flowcharts of the internal workings of the system. It was withdrawn by Microsoft before mass-distribution in 1986 because it contained many factual errors as well as some classified information which should not have been published. Few printed copies survived. It was replaced by a completely reworked edition in 1988.[2]Archived July 15, 2019, at theWayback Machine)
^abZbikowski, Mark;Allen, Paul;Ballmer, Steve; Borman, Reuben; Borman, Rob; Butler, John; Carroll, Chuck; Chamberlain, Mark; Chell, David; Colee, Mike; Courtney, Mike; Dryfoos, Mike; Duncan, Rachel; Eckhardt, Kurt; Evans, Eric; Farmer, Rick;Gates, Bill; Geary, Michael; Griffin, Bob; Hogarth, Doug; Johnson, James W.; Kermaani, Kaamel; King, Adrian; Koch, Reed; Landowski, James; Larson, Chris; Lennon, Thomas; Lipkie, Dan;McDonald, Marc; McKinney, Bruce; Martin, Pascal; Mathers, Estelle; Matthews, Bob; Melin, David; Mergentime, Charles; Nevin, Randy; Newell, Dan; Newell, Tani; Norris, David; O'Leary, Mike;O'Rear, Bob; Olsson, Mike; Osterman, Larry; Ostling, Ridge; Pai, Sunil;Paterson, Tim; Perez, Gary; Peters, Chris;Petzold, Charles; Pollock, John;Reynolds, Aaron; Rubin, Darryl; Ryan, Ralph; Schulmeisters, Karl; Shah, Rajen; Shaw, Barry; Short, Anthony; Slivka, Ben; Smirl, Jon; Stillmaker, Betty; Stoddard, John; Tillman, Dennis; Whitten, Greg; Yount, Natalie; Zeck, Steve (1988). "Technical advisors".The MS-DOS Encyclopedia: versions 1.0 through 3.2. By Duncan, Ray; Bostwick, Steve; Burgoyne, Keith; Byers, Robert A.; Hogan, Thom; Kyle, Jim;Letwin, Gordon;Petzold, Charles; Rabinowitz, Chip; Tomlin, Jim; Wilton, Richard; Wolverton, Van; Wong, William; Woodcock, JoAnne (Completely reworked ed.). Redmond, Washington, USA:Microsoft Press.ISBN1-55615-049-0.LCCN87-21452.OCLC16581341. (xix+1570 pages; 26 cm) (NB. This edition was published in 1988 after extensive rework of the withdrawn 1986 first edition by a different team of authors.[3]Archived October 14, 2018, at theWayback Machine)
^Kurth, Rüdiger; Groß, Martin; Hunger, Henry (November 29, 2016) [2007]."Betriebssystem DCP".www.robotrontechnik.de (in German).Archived from the original on April 3, 2019. RetrievedApril 28, 2019.
^Mueller, Scott (1995).Upgrading and Repairing PCs (5th ed.).Que Corporation. p. 784.ISBN0-7897-0321-1.The limit of 16 MB did not come from the FAT, but from the high-level DOS FORMAT command... Most vendors supplied modified high-level format programs that permitted partitions of up to 32 MB to be formatted properly.
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