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An example of MS-DOS's command-line interface, this one showing that the current directory is the root of drive C.
Developer Microsoft
Written in Assembly[1]
OS family DOS
Working state Discontinued
Source model Closed source;source-available for select versions since 2014[2][3][4]
Initial release August 1981; 33 years ago[5]
Final release 8.0 / September 15, 2000; 14 years ago
Update method None
Package manager None
Platforms x86
Kernel type Monolithic
Default user interface Command-linetext
License Proprietary
Succeeded by Microsoft Windows
Official website MS-DOS overview
Support status
Unsupported, starting from 31 December 2001[6]

MS-DOS (/ˌɛmɛsˈdɒs/ em-es-doss; short for Microsoft Disk Operating System) was an operating system for x86-based personal computersmostly developed by Microsoft. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid-1990s, when it was gradually superseded by operating systems offering a graphical user interface (GUI), in various generations of the Microsoft Windows operating system.

MS-DOS resulted from a request in 1981 by IBM for an operating system to use in its IBM PC range of personal computers.[7][8] Microsoft quickly bought the rights to 86-DOS from Seattle Computer Products,[9] and began work on modifying it to meet IBM's specification. IBM licensed and released it in August 1981 as PC DOS 1.0 for use in their PCs. Although MS-DOS and PC DOS were initially developed in parallel by Microsoft and IBM, in subsequent years the two products went their separate ways.

During its life, several competing products were released for the x86 platform,[10] and MS-DOS went through eight versions, until development ceased in 2000. Initially MS-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 languages 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. It is a flexible operating system, and consumes negligible installation space. 


Further information: DOS and Timeline of DOS operating systems

MS-DOS was a renamed form of 86-DOS [11] – owned by Seattle Computer Products, written by Tim Paterson. Development of 86-DOS took only six weeks, as it was basically a clone ofDigital 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.[5] Microsoft, which needed an operating system for the IBM Personal Computer[7][8] hired Tim Paterson in May 1981 and bought 86-DOS 1.10 for $75,000 in July of the same year. Microsoft kept the version number, but renamed it MS-DOS. They also licensed MS-DOS 1.10/1.14 to IBM, who, in August 1981, offered it as PC DOS 1.0 as one of three operating systems[12] for the IBM 5150, or the IBM PC.[5]

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 for CP/M, 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 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, 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, 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 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 the same-numbered standard version for the IBM PC, with a few notable exceptions.

On 25 March 2014, Microsoft made the code to SCP MS-DOS 1.25 and a mixture of Altos MS-DOS 2.11 and TeleVideo PC DOS 2.11 available to the public under the Microsoft Research License Agreement, which makes the code source-available, but not open source as defined by Open Source Initiative or Free Software Foundation standards.[2][3][4][14]

As an April Fools joke in 2015, Microsoft Mobile launched a Windows Phone application called MS-DOS Mobile which was presented as a new mobile operating system and worked similar to MS-DOS.[15]



Microsoft licensed or released versions of MS-DOS under different names like Lifeboat Associates "Software Bus 86"[16] aka SB-DOS,[10] COMPAQ-DOS,[16] NCR-DOS or Z-DOS[10] 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 to IBM PC DOS. (Competitors released compatible DOS systems such as DR DOS and PTS-DOS that could also run DOS applications.)

The following versions of MS-DOS were released to the public:[17][18]

  • MS-DOS 1.x
    • Version 1.10 (OEM) – possible basis for IBM's Personal Computer DOS 1.0
    • Version 1.11 (OEM) – possible basis for IBM's Personal Computer DOS 1.0
    • Version 1.14 (OEM) – possible basis for IBM's Personal Computer DOS 1.0
    • Version 1.24 (OEM) – basis for IBM's Personal Computer DOS 1.1
    • Version 1.25 (OEM) – basis for non-IBM OEM versions of MS-DOS, including SCP MS-DOS 1.25
  • Compaq-DOS 1.12, a Compaq OEM version of MS-DOS (1.25 or higher)
  • Zenith Z-DOS 1.19, a Zenith OEM version of MS-DOS (1.25 or higher)[19]
  • 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)
      • Altos MS-DOS 2.11, an Altos OEM version of MS-DOS 2.11 for the ACT-86C
      • TeleVideo PC DOS 2.11, an TeleVideo OEM version of MS-DOS 2.11
  • MS-DOS 3.x
    • Version 3.0 (OEM) – Support for FAT16. First version to support 5.25 inch, 1.2 MB floppy drives and diskettes.
    • Version 3.1 (OEM) – Support for Microsoft Networks
    • Version 3.11 (OEM) - First version to support 3.5 inch, 720 kB floppy drives and diskettes.
    • Version 3.2 (OEM) - First version to support 3.5 inch, 720 kB floppy drives and diskettes.
    • Version 3.21 (OEM)
    • Version 3.22 (OEM) - (HP 95LX)
    • Version 3.25 (OEM)
    • Version 3.3 (OEM) - First version to support 3.5 inch, 1.44 MB floppy drives and diskettes.
    • Version 3.3a (OEM)
    • Version 3.31 (OEM) – Compaq MS-DOS 3.31 supports FAT16B and larger drives.[20]
  • 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.[21]
    • Version 4.00 (OEM) - First version to support a single hard disk partition that is greater than 32 MiB and up to a maximum size of 2 GiB (SHARE.EXE was required to be loaded to access these partitions).[22]
    • 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[23] and when using SYS to make a floppy disk or a partition of a hard drive bootable).[24]
    • Version 4.01a (OEM)
  • MS-DOS 5.x
    • Version 5.0 (Retail) – includes a full-screen editor. A number of bugs required re issue. First version to support 3.5 inch, 2.88 MB floppy drives and diskettes. Hard disk partitions greater than 32 MiB and up to a maximum size of 2 GiB no longer required SHARE.EXE to be loaded in order to access them. Support was now provided by the MS-DOS kernel.[25]
    • 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, upper memory optimization and antivirus included.
    • Version 6.2 – 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.[26]
  • MS-DOS 7.x
    • Version 7.0 (Windows 95, Windows 95A) – Support for VFAT long file names and 32-bits signed integer errorlevel. New editor. JO.SYS is an alternative filename of the IO.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.
    • Version 7.1 (Windows 95B – Windows 98SE) – Support for FAT32 file system. Last general purpose DOS to load Windows.
  • MS-DOS 8.0
    • Version 8.0 (Windows ME) – Integrated drivers for faster Windows loading. Four different kernels (IO.SYS) observed.[27]
    • Version 8.0 (Windows XP) – DOS boot disks created by XP and later contain files from Windows ME. The internal command prompt still reports version 5.0[citation needed]

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 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.[28] 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.

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Article details
Article ID: 28
Category: computers
Date added: 2015-07-03 17:06:50
Views: 184
Rating (Votes): Article rated 3.2/5.0 (9)

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