View source for IBM PC DOS

{{Short description|Computer operating system}}
{{Use dmy dates|date=May 2019|cs1-dates=y}}
{{Infobox OS
| name = IBM PC DOS
| logo = IBM PC DOS 7.0 logo.svg
| logo_size = 96px
| screenshot = PC DOS 1.10 screenshot.png
| caption = Version 1.10 (1982) command line
| developer = [[Microsoft]]<br>[[IBM]]
| family = [[DOS]]
| source_model = [[Closed source]]
| released = {{Start date and age|1981|08|df=yes}} 
| latest_release_version = [[#PC DOS 2000|PC DOS 2000]]
| latest_release_date = {{Start date and age|1998|04|df=yes}} 
| latest preview version = [[#PC DOS 7.10|PC DOS 7.1]] 
| latest preview date = {{Start date and age|2003|df=yes}} 
| kernel_type = [[Monolithic kernel]]
| ui = [[Command-line interface]] ([[COMMAND.COM]])
| programmed_in = [[Assembly language]], [[C (programming language)|C]]
| supported_platforms = [[x86]]
| license = [[Commercial software|Commercial]] [[proprietary software]]
| language=English (US), English (UK), Danish, Dutch, Finnish, French, German, Italian, Norwegian, Portuguese, Russian, Spanish, Swedish<!-- based on PC DOS 7.0, was available for these locales specifically, but not sure if messages translated into all of these languages -->
| working_state = No longer supported
| website =
}}

'''IBM PC DOS''' (an [[acronym]] for '''IBM Personal Computer Disk Operating System'''),<ref name=ver group=nb>Formally known as "The IBM Personal Computer DOS" from versions 1.0 through 3.30, as reported in those versions' respective [[COMMAND.COM]] outputs</ref> also known as '''PC DOS''' or '''IBM DOS''', is a discontinued [[disk operating system]] for the [[IBM Personal Computer]], its successors, and [[IBM PC compatible]]s. It was sold by [[IBM]] from the early 1980s into the 2000s. Developed by [[Microsoft]], it was also sold by that company to the open market as [[MS-DOS]]. Both operating systems were identical or almost identical until 1993, when IBM began selling PC DOS 6.1 with its own new features. The collective shorthand for PC DOS and MS-DOS was [[DOS]], which is also the generic term for disk operating system, and is shared with dozens of [[List of disk operating systems called DOS|disk operating systems called DOS]].

==History==
The IBM task force assembled to develop the IBM PC decided that critical components of the machine, including the operating system, would come from outside vendors. This radical break from company tradition of in-house development was one of the key decisions that made the IBM PC an industry standard. [[Microsoft]], founded five years earlier by [[Bill Gates]], was eventually selected for the operating system.

IBM wanted Microsoft to retain ownership of whatever software it developed, and wanted nothing to do with helping Microsoft, other than making suggestions from afar. According to task force member Jack Sams: 
<blockquote>The reasons were internal. We had a terrible problem being sued by people claiming we had stolen their stuff. It could be horribly expensive for us to have our programmers look at code that belonged to someone else because they would then come back and say we stole it and made all this money. We had lost a series of suits on this, and so we didn't want to have a product which was clearly someone else's product worked on by IBM people. We went to Microsoft on the proposition that we wanted this to be their product.<ref name="Jakobsen"/>{{Citation needed|date=July 2016|reason=Parts of this source can be found in at least two books published in 2015 ([https://books.google.com/books?id=B1SNBQAAQBAJ&pg=PT269&lpg=PT269] [https://books.google.com/books?id=a2l9DwAAQBAJ&pg=PA34&lpg=PA34]), but they don't cite the origin of their source, so it's possible that they sourced Jack Sams's citation from Wikipedia.}}</blockquote>

IBM first contacted Microsoft to look the company over in July 1980. Negotiations continued over the months that followed, and the paperwork was officially signed in early November.<ref name="Wallace_1992"/>

Although IBM expected that most customers would use PC&nbsp;DOS,<ref name="Bunnell_1982"/> the IBM PC also supported [[CP/M-86]], which became available six months after PC&nbsp;DOS,<ref name="Edlin_1982"/> and [[UCSD p-System]] operating systems.<ref name="Lemmons_1981"/> IBM's expectation proved correct: one survey found that 96.3% of PCs were ordered with the $40 PC&nbsp;DOS compared to 3.4% with the $240 CP/M-86.<ref name="Pcommuniques_1983"/>

Over the history of IBM PC&nbsp;DOS, various versions were developed by IBM and Microsoft. By the time PC&nbsp;DOS 3.0 was completed, IBM had a team of developers covering the full OS. At that point in time, either IBM or Microsoft completely developed versions of IBM PC&nbsp;DOS going forward. By 1985, the joint development agreement (JDA) between IBM and Microsoft for the development of PC&nbsp;DOS had each company giving the other company a completely developed version. Most of the time branded versions were identical, but there were some cases in which each of the companies made minor modifications to their version of DOS. In the fall of 1984, IBM gave all the source code and documentation of the internally developed [[IBM TopView]] for DOS to Microsoft so that Microsoft could more fully understand how to develop an [[Object-oriented programming|object-oriented]] [[operating environment]], overlapping windows (for its development of [[Windows 2.0]]) and [[Computer multitasking|multitasking]].

===Version history===
{| class="wikitable"
|-
! Version !! Release date !! References
|-
| 1.0 || August 12, 1981 || <ref>{{cite press release |url=https://minuszerodegrees.net/5150/doco/IBM%20Product%20Announcement%20-%20IBM%20PC%205150.pdf |title=Product Announcement: The IBM Personal Computer |publisher=[[IBM]] |location=White Plains, New York |date=August 12, 1981 |access-date=February 8, 2023}}</ref>
|-
| 1.1 (1.10) || May 7, 1982 || <ref>{{cite web |url=https://thestarman.pcministry.com/DOS/ibm110 |title=IBM Personal Computer DOS Version 1.1.0 (1982) |first=Daniel |last=Sedory |publisher=The Starman's Realm |date=August 13, 2008 |access-date=February 8, 2023}}</ref>
|-
| 2.0 || March 8, 1983 || <ref>{{cite web |url=https://www.ibm.com/docs/en/announcements/archive/ENUS283-034 |type=Announcement letter |id=283-034 |title=IBM Personal Computer DOS Version 2 And IBM Personal Computer BASIC Language Extensions Version 2 Are Now Available 6024061 |publisher=[[IBM]] |date=March 8, 1983 |access-date=January 19, 2025}}</ref>
|-
| 2.1 (2.10) || November 1, 1983 || <ref>{{cite web |url=https://www.ibm.com/docs/en/announcements/archive/ENUS283-389 |type=Announcement letter |id=283-389 |title=IBM Personal Computer DOS Version 2.1 Announced And Available |publisher=[[IBM]] |date=November 1, 1983 |access-date=January 19, 2025}}</ref>
|-
| 3.0 || September 14, 1984 || <ref>{{cite web |url=https://www.ibm.com/docs/en/announcements/archive/ENUS284-283 |type=Announcement letter |id=284-283 |title=IBM Personal Computer DOS Version 3.0 |publisher=[[IBM]] |date=August 14, 1984 |access-date=January 19, 2025}}</ref>
|-
| 3.1 (3.10) || April 2, 1985 || <ref>{{cite web |url=https://www.pcjs.org/software/pcx86/sys/dos/ibm/3.10 |title=IBM PC DOS 3.10 |publisher=PCjs Machines |access-date=February 8, 2023}}</ref>
|-
| 3.2 (3.20) || April 2, 1986 || <ref>{{cite web |url=https://www.ibm.com/docs/en/announcements/archive/ENUS286-129 |type=Announcement letter |id=286-129 |title=IBM Personal Computer Disk Operating System Version 3.2 On 3.5-Inch Diskette And IBM Personal Computer BASIC Reference Version 3.2 Available |publisher=[[IBM]] |date=April 2, 1986 |access-date=January 19, 2025}}</ref>
|-
| 3.3 (3.30) || April 2, 1987 || <ref>{{cite web |url=https://www.ibm.com/docs/en/announcements/archive/ENUS287-098 |type=Announcement letter |id=287-098 |title=IBM Disk Operating System (DOS) Version 3.30 |publisher=[[IBM]] |date=April 2, 1987 |access-date=January 19, 2025}}</ref>
|-
| 4.0 || July 19, 1988 || <ref>{{cite web |url=https://www.ibm.com/docs/en/announcements/archive/ENUS288-380 |type=Announcement letter |id=288-380 |title=IBM Disk Operating System (DOS) Version 4.00 |publisher=[[IBM]] |date=July 19, 1988 |access-date=January 19, 2025}}</ref>
|-
| 5.0 || June 11, 1991 || <ref>{{cite web |url=https://www.ibm.com/docs/en/announcements/archive/ENUSZP91-0432 |type=Announcement letter |id=ZP91-0432 |title=IBM DOS Version 5.00 and Upgrade |publisher=[[IBM]] |date=June 11, 1991 |access-date=January 19, 2025}}</ref>
|-
| 6.1 || July 26, 1993 || <ref name="version-6.1">{{cite web |url=https://www.ibm.com/docs/en/announcements/archive/ENUS293-347 |type=Announcement letter |id=293-347 |title=IBM PC DOS Version 6.1 |publisher=[[IBM]] |date=June 29, 1993 |access-date=January 19, 2025}}</ref>
|-
| 6.3 || April 27, 1994 || <ref>{{cite web |url=https://www.ibm.com/docs/en/announcements/archive/ENUS294-263 |type=Announcement letter |id=294-263 |title=IBM PC DOS Version 6.3 |publisher=[[IBM]] |date=April 27, 1994 |access-date=January 19, 2025}}</ref>
|-
| 7.0 || February 28, 1995 || <ref name="version-7">{{cite web |url=https://www.ibm.com/docs/en/announcements/archive/ENUSZP95-0102 |type=Announcement letter |id=ZP95-0102 |title=IBM PC DOS Version 7 |date=February 28, 1995 |access-date=January 19, 2025}}</ref>
|-
| 2000 || May 29, 1998 || <ref>{{cite web |url=https://www.ibm.com/docs/en/announcements/archive/ENUS298-169 |type=Announcement letter |id=298-169 |publisher=[[IBM]] |title=IBM PC DOS 2000 Can Ease Your Transition to the Year 2000 |date=May 26, 1998 |access-date=January 19, 2025}}</ref>
|}

== Versions ==

=== {{anchor|1.00|1.10}}PC DOS 1.x ===
<!-- What about PC DOS 1.05 and 1.85? Did they really exist? -->
[[File:IBM DOS 1.1 Manual and Disk.jpg|thumb|upright | User manual and diskette for IBM PC&nbsp;DOS 1.1]]
Microsoft first licensed,<ref name="86-DOS_License"/> then purchased<ref name="86-DOS_Sale"/> [[86-DOS]] from [[Seattle Computer Products]] (SCP), which was modified for the IBM PC by Microsoft employee [[Bob O'Rear]] with assistance from SCP (later Microsoft) employee [[Tim Paterson]].<ref name="Paterson_2007"/> O'Rear got 86-DOS to run on the prototype PC in February 1981. 86-DOS had to be converted from 8-inch to 5.25-inch [[floppy disks]] and integrated with the [[BIOS]], which Microsoft was helping IBM to write.<ref name="Beley_1986"/><ref name="Duncan_1988"/> IBM had more people writing requirements for the computer than Microsoft had writing code. O'Rear often felt overwhelmed by the number of people he had to deal with at the ESD (Entry Systems Division) facility in [[Boca Raton, Florida]].

Perhaps the first public mention of the operating system was in July 1981, when ''[[Byte (magazine)|Byte]]'' discussed rumors of a forthcoming personal computer with "a CP/M-like DOS ... to be called, simply, 'IBM Personal Computer DOS{{'"}}.<ref name="Morgan_1981"/> 86-DOS was [[rebranded]] IBM PC&nbsp;DOS 1.0 for its August 1981 release with the IBM PC. The initial version of DOS was largely based on [[CP/M-80]] 1.x and most of its architecture, function calls and file-naming conventions were copied directly from the older OS. The most significant difference was the fact that it introduced a different file system, [[FAT12]]. Unlike all later DOS versions, the {{mono|[[DATE (DOS command)|DATE]]}} and {{mono|[[TIME (DOS command)|TIME]]}} commands were separate executables rather than part of {{mono|[[COMMAND.COM]]}}. Single-sided 160 [[kilobyte]] (KB) 5.25-inch floppies were the only disk format supported.

In late 1981, Paterson, now at Microsoft, began writing PC&nbsp;DOS 1.10. It debuted in May 1982 along with the Revision&nbsp;B IBM PC. Support for the new double-sided drives was added, allowing 320&nbsp;KB per disk. A number of bugs were fixed, and error messages and prompts were made less cryptic. The {{mono|[[DEBUG (DOS command)|DEBUG.EXE]]}} was now able to load files greater than 64&nbsp;KB in size.

=== {{anchor|2.00|2.10|2.11}}PC DOS 2.x ===

Later, a group of Microsoft programmers (primarily [[Paul Allen]], [[Mark Zbikowski]] and [[Aaron R. Reynolds|Aaron Reynolds]])<ref name="Duncan_1988"/> began work on PC&nbsp;DOS 2.0. Completely rewritten, DOS 2.0 added subdirectories and hard disk support for the new [[IBM Personal Computer XT|IBM XT]], which debuted in March 1983. A new 9-sector format bumped the capacity of floppy disks to 360&nbsp;KB. The [[Unix]]-inspired kernel featured [[file handle]]s in place of the CP/M-derivative file control blocks and loadable device drivers could now be used for adding hardware beyond that which the IBM PC BIOS supported. BASIC and most of the utilities provided with DOS were substantially upgraded as well. A major undertaking that took almost 10 months of work, DOS 2.0 was more than twice as big as DOS 1.x, occupying around 28&nbsp;KB of RAM compared to the 12&nbsp;KB of its predecessor. It would form the basis for all Microsoft consumer-oriented OSes until 2001, when [[Windows XP]] (based on [[Windows NT]]) was released.<ref name="Duncan_1988"/>

In October 1983 (officially 1 November 1983)<ref name="DOS21"/> DOS 2.1 debuted. It fixed some bugs and added support for half-height floppy drives and the new [[IBM PCjr]].

In 1983, [[Compaq]] released the [[Compaq Portable]], the first 100% [[IBM PC compatible]]. It shipped with [[COMPAQ-DOS]],<ref name="edwards20250616">{{Cite web |last=Edwards |first=Gareth |date=2025-06-16 |title=The Man Who Beat IBM |url=https://every.to/the-crazy-ones/the-man-who-beat-ibm |access-date=2025-08-07 |website=Every}}</ref> its own OEM version of MS-DOS 1.10 (quickly replaced by DOS 2.00) from Microsoft. Other PC compatibles followed suit, most of which included hardware-specific DOS features, although some were generic.

=== {{anchor|3.00|3.10|3.20|3.21|3.30}}PC DOS 3.x ===
[[File:IBM DOS 3.30 Retail Box.jpg|thumb|Retail box of IBM PC DOS 3.30]]
In August 1984, IBM introduced the [[Intel 80286]]-derived [[IBM PC/AT]], its next-generation machine. Along with this was DOS 3.00. Despite jumping a whole version number, it again proved little more than an incremental upgrade, adding nothing more substantial than support for the AT's new 1.2 [[megabyte]] (MB) floppy disks. Planned networking capabilities in DOS 3.00 were judged too buggy to be usable and Microsoft disabled them prior to the OS's release. In any case, IBM's original plans for the AT had been to equip it with a proper next-generation OS that would use its extended features, but this never materialized.<ref name="Wallace_1992"/> PC&nbsp;DOS 3.1 (released March 1985) fixed the bugs in DOS 3.00 and supported IBM's Network Adapter card on the [[IBM PC Network]]. PC&nbsp;DOS 3.2 added support for {{frac|3|1|2}}-inch double-density 720&nbsp;KB floppy disk drives, supporting the [[IBM PC Convertible]], IBM's first computer to use {{frac|3|1|2}}-inch floppy disks, released April 1986, and later the [[IBM Personal System/2]] in 1987.

In June 1985, IBM and Microsoft signed a long-term Joint Development Agreement to share specified DOS code and create a new operating system from scratch, known at the time as Advanced DOS. On 2 April 1987 [[OS/2]] was announced as the first product produced under the agreement.<ref name="Necasek_2004"/> At the same time, IBM released its next generation of personal computers, the [[IBM Personal System/2]] (PS/2).<ref name="Wallace_1992"/> PC&nbsp;DOS 3.3, released with the PS/2 line, added support for high density {{frac|3|1|2}}-inch 1.44&nbsp;MB floppy disk drives, which IBM introduced in its 80286-based and higher PS/2 models. The upgrade from DOS 3.2 to 3.3 was completely written by IBM, with no development effort on the part of Microsoft, who were working on "Advanced DOS 1.0". DOS 3.30 was the last version designed with the IBM XT and floppy-only systems in mind; it became one of the most popular versions and many users preferred it to its buggy successor.

=== {{anchor|3.40|4.00|4.01|4.02|Lifeboat|Captain|Jetski}}PC DOS 4.x ===

PC&nbsp;DOS 4.0 (internally known as DOS 3.4 originally) shipped July 1988. DOS 4.0 had some compatibility issues with low-level disk utilities due to some internal data structure changes. DOS 4.0 used more memory than DOS 3.30 and it also had a few glitches. Newly added EMS drivers were only compatible with IBM's EMS boards and not the more common{{Citation needed|date=April 2012}} Intel and AST ones. DOS 4.0 is also notable for including the first version of the [[DOS Shell]], a full-screen utility designed to make the command-line OS more user-friendly. Microsoft took back control of development and released a bug-fixed DOS 4.01.<ref name="TackTech"/>

=== {{anchor|5.00|5.01|5.02}}PC DOS 5 ===

DOS 5 debuted in June 1991. DOS 5 supported the use of the [[High Memory Area]] (HMA) and [[Upper Memory Blocks]] (UMBs) on 80286 and later systems to reduce its [[conventional memory]] usage. Also all DOS commands now supported the {{mono|/?}} option to display command syntax. Aside from IBM's PC&nbsp;DOS, MS-DOS was the only other version available as OEM editions vanished since by this time PCs were 100% compatible so customizations for hardware differences were no longer necessary.

The POWER.EXE was introduced that has the [[Advanced Power Management|APM]] standard in version 5.02.<ref>Intel Corporation, "NewsBit: Microsoft, Intel Develop Power Standard", Microcomputer Solutions, March/April 1992, page 1</ref><ref>[https://www.pcjs.org/software/pcx86/sys/dos/ibm/5.02/ IBM PC DOS 5.02]</ref>

This was the last version of DOS that IBM and Microsoft shared the full code for, and the DOS that was integrated into OS/2 2.0's, and later Windows NT's, [[virtual DOS machine]].

=== {{anchor|6.10}}PC DOS 6.1 ===

PC&nbsp;DOS remained a rebranded version of MS-DOS until 1993. IBM and Microsoft parted ways&mdash;MS-DOS 6 was released in March, and PC&nbsp;DOS 6.1 (separately developed) followed in June. Most of the new features from MS-DOS 6.0 appeared in PC&nbsp;DOS 6.1 including the new boot menu support and the new commands {{mono|[[CHOICE (DOS command)|CHOICE]]}}, {{mono|[[DELTREE]]}}, and {{mono|[[MOVE (DOS command)|MOVE]]}}. [[QBasic]] was dropped and the [[MS-DOS Editor]] was replaced with the IBM [[E (PC DOS)|E Editor]]. It also licensed components of [[Central Point Software|Central Point's]] [[PC Tools (software)|PC Tools]], such as Central Point Backup Utility (CPBACKUP).<ref name="version-6.1" /><ref name="version-7" /> PC&nbsp;DOS 6.1 reports itself as DOS 6.00.

=== {{anchor|6.30}}PC DOS 6.3 ===

PC&nbsp;DOS 6.3 followed in December. PC&nbsp;DOS 6.3 was also used in OS/2 for the [[PowerPC]]. PC&nbsp;DOS 6.3 also featured [[SuperStor]] disk compression technology from [[Addstor, Inc.|Addstor]].

=== {{anchor|7.00}}PC DOS 7 ===

PC&nbsp;DOS 7 was released in April 1995 and was the last release of DOS before IBM software development (other than the development [[IBM ViaVoice]]) moved to Austin. The [[REXX]] programming language was added, as well as support for a new floppy disk format, [[IBM Extended Density Format|XDF]], which extended a standard 1.44&nbsp;MB floppy disk to 1.86&nbsp;MB. SuperStor disk compression technology was replaced with [[Stac Electronics]]' [[STACKER]]. An algebraic command line calculator and a utility program to load device drivers from the command line were added. PC&nbsp;DOS 7 also included many optimizations to increase performance and reduce memory usage.<ref name="retro"/>

=== {{anchor|2000}}PC DOS 2000 ===

The most recent retail release was PC&nbsp;DOS 2000 &ndash; released from Austin in 1998 &ndash; which found its niche in the [[embedded software]] market and elsewhere. PC&nbsp;DOS 2000 is a [[Slipstream (computing)|slipstream]] of 7.0 with [[Year 2000 problem|Y2K]] and other fixes applied. To applications, PC&nbsp;DOS 2000 reports itself as "IBM PC&nbsp;DOS 7.00, revision 1", in contrast to the original PC&nbsp;DOS 7, which reported itself as "IBM PC&nbsp;DOS 7.00, revision 0".<ref group="nb" name="NB_OEM"/>

PC-DOS 2000 was the last version of IBM PC-DOS that was sold at retail. IBM advertised it as a Y2K compliant DOS. As it reports itself as "IBM PC-DOS 7 Revision 1", it is often referred to as "IBM PC-DOS7R1" or just "PC-DOS7R1".

[[Hitachi]] used PC&nbsp;DOS 2000 in their legacy ''Drive Fitness Test'' (4.15) and ''Hitachi Feature Tool'' (2.15) until 2009.<ref name="HGST_2009"/> [[ThinkPad]] products had a copy of the latest version of PC&nbsp;DOS in their Rescue and Recovery partition.<ref name="Lenovo"/>

=== {{anchor|7.10|PC DOS 7.10}}PC DOS 7.1 ===

PC&nbsp;DOS 7.1 added support for [[Logical Block Addressing]] (LBA) and [[FAT32]] partitions.<ref group="nb" name="NB_OEM"/> Various builds [[Timeline of DOS operating systems|from 1999 up to 2003]] were not released in retail, but used in products such as the IBM ServerGuide Scripting Toolkit.<ref name="IBM_ServerGuide"/> A build of this version of DOS appeared in [[Norton Ghost]] from [[NortonLifeLock|Symantec]].<ref name="Symantec_Ghost"/> Version 7.1 indicates support for FAT32 also in [[MS-DOS]].<ref name="retro"/>

Most builds of this version of DOS are limited to the kernel files {{mono|[[IBMBIO.COM]]}}, {{mono|[[IBMDOS.COM]]}}, and {{mono|[[COMMAND.COM]]}}. The updated programs {{mono|FDISK32}} and {{mono|FORMAT32}} allow one to prepare FAT32 disks. Additional utilities are taken from PC&nbsp;DOS 2000, where needed.

== PC DOS as a distributed file client ==

In 1986, IBM announced PC&nbsp;DOS support for client access to the file services defined by [[Distributed Data Management Architecture]] (DDM). This enabled programs on PCs to create, manage, and access [[record-oriented file (DDM)|record-oriented file]]s available on IBM System/36, IBM System/38 and IBM mainframe computers running [[CICS]]. In 1988, client support for [[stream-oriented file (DDM)|stream-oriented file]]s and [[hierarchical directory (DDM)|hierarchical directories]] was added to PC&nbsp;DOS when they became available on the DDM server systems.

== See also ==
* [[Timeline of DOS operating systems]]
* [[Comparison of DOS operating systems]]
* [[List of DOS commands]]

== Notes ==
{{Reflist|group="nb"|refs=
<ref group="nb" name="NB_OEM">For PC&nbsp;DOS the [[DOS API|DOS INT <code>21h</code>]] function <code>30h</code> ''Get DOS version'' returns [[Original equipment manufacturer|OEM]] code <code>00h</code> for [[IBM]] instead of <code>FFh</code> for [[Microsoft]]. This is particularly important for DOS 7, because various features introduced in MS-DOS 7.0 and 7.1 are not supported in PC&nbsp;DOS 7.x, and vice versa, e.g., MS-DOS does not support [[REXX]], and PC&nbsp;DOS 7 and 2000 do not support LBA access.</ref>
}}

== References ==
{{Reflist|refs=
<ref name="Jakobsen">{{cite web |title=The History of DOS |author-first=Remi |author-last=Jakobsen |work=Remi's Classic Computers - My collection of vintage computers, game consoles, history, specs and repairs. |url=https://rclassiccomputers.com/dos/ |access-date=2017-11-10 |url-status=live |archive-url=https://web.archive.org/web/20190804152929/https://rclassiccomputers.com/dos/ |archive-date=2019-08-04}}</ref>
<ref name="Wallace_1992">{{cite book |title=Hard Drive: Bill Gates and the Making of the Microsoft Empire |author-last1=Wallace |author-first1=James |author-last2=Erickson |author-first2=Jim |date=1992 |publisher=[[John Wiley & Sons]] |isbn=0-471-56886-4 |pages=[https://archive.org/details/harddrivebillgat00wall_0/page/190 190] |url=https://archive.org/details/harddrivebillgat00wall_0/page/190 |url-access=registration}}</ref>
<ref name="Bunnell_1982">{{cite magazine |title=The Man Behind The Machine? A PC Exclusive Interview With Software Guru Bill Gates |magazine=[[PC Magazine]] |date=February–March 1982 |page=16 |author-last=Bunnell |author-first=David Hugh |author-link=David Hugh Bunnell |url=https://books.google.com/books?id=w_OhaFDePS4C&pg=PA16 |access-date=2016-07-12}}</ref>
<ref name="Edlin_1982">{{cite magazine |title=CP/M Arrives |magazine=[[PC Magazine]] |date=June–July 1982 |author-last=Edlin |author-first=Jim |page=43 |url=https://books.google.com/books?id=w_OhaFDePS4C&pg=RA2-PA43 |access-date=2016-07-12}}</ref>
<ref name="Lemmons_1981">{{cite magazine |title=The IBM Personal Computer: First Impressions |magazine=[[Byte (magazine)|Byte]] |date=October 1981 |author-last=Lemmons |author-first=Phil |page=36 |url=https://archive.org/stream/byte-magazine-1981-10/1981_10_BYTE_06-10_Local_Networks#page/n27/mode/2up |access-date=2016-07-12}}</ref>
<ref name="Pcommuniques_1983">{{cite magazine |title=CP/M-86 Price Plunges to $60 |magazine=[[PC Magazine]] |date=February 1983 |page=56 |url=https://books.google.com/books?id=7wCiNAUEuAMC&pg=PA56 |access-date=2017-10-11}}</ref>
<ref name="86-DOS_License">{{cite web |title=86-DOS version 0.3 (1980-11-15) License Agreement between Seattle Computer Products and Microsoft |date=1981-01-06<!-- signed date --> |url=http://antitrust.slated.org/www.iowaconsumercase.org/011607/0000/PX00001.pdf |access-date=2013-04-01 |url-status=live |archive-url=https://web.archive.org/web/20200218165128/http://antitrust.slated.org/www.iowaconsumercase.org/011607/0000/PX00001.pdf |archive-date=2020-02-18}} (NB. Published as part of the [[Comes v. Microsoft]] case as exhibit #1.)</ref>
<ref name="86-DOS_Sale">{{cite web |title=86-DOS Sales Agreement between Seattle Computer Products and Microsoft |date=1981-07-27 |url=http://antitrust.slated.org/www.iowaconsumercase.org/011607/0000/PX00002.pdf |access-date=2013-04-01 |archive-date=2014-09-05  |archive-url=https://web.archive.org/web/20140905220128/http://antitrust.slated.org/www.iowaconsumercase.org/011607/0000/PX00002.pdf |url-status=dead }} (NB. Published as part of the [[Comes v. Microsoft]] case as exhibit #2/#3. The document also carries a typed date stamp as of 1981-07-22.)</ref>
<ref name="Paterson_2007">{{cite web |title=Is DOS a Rip-Off of CP/M? |author-first=Tim |author-last=Paterson |author-link=Tim Paterson |work=DosMan Drivel |date=2007-08-08 |url=http://dosmandrivel.blogspot.de/2007/08/is-dos-rip-off-of-cpm.html |access-date=2014-02-13}}</ref>
<ref name="Morgan_1981">{{cite news |title=IBM's Personal Computer |work=BYTE |date=July 1981 |author-last=Morgan |author-first=Chris |page=6 |url=https://archive.org/stream/byte-magazine-1981-07/1981_07_BYTE_06-07_Energy_Conservation#page/n7/mode/2up |access-date=2013-10-18}}</ref>
<ref name="Necasek_2004">{{cite web |title=Microsoft Operating System/2 With Windows Presentation Manager Provides Foundation for Next Generation of Personal Computer Industry |author-first=Michal |author-last=Necasek |work=The History of OS/2 |date=2004-06-24 |url=http://pages.prodigy.net/michaln/history/pr/87apr_m3592.html |url-status=dead |archive-url=https://web.archive.org/web/20100410013835/http://pages.prodigy.net/michaln/history/pr/87apr_m3592.html |archive-date=2010-04-10}} (NB. A copy of Microsoft's 1987-04-02 press release announcing OS/2.)</ref>
<ref name="DOS21">{{Cite web|url=http://www.os2museum.com/wp/?page_id=630|title = DOS 2.0 and 2.1 &#124; OS/2 Museum}}</ref>
<ref name="TackTech">[http://www.tacktech.com/display.cfm?ttid=30 History of Microsoft Windows and MS-DOS (Miscellaneous)] TACKtech Corp.</ref>
<ref name="retro">{{cite web |title=Information and history about PC&nbsp;DOS and MS-DOS |author-first=Vernon C. |author-last=Brooks |work=PC&nbsp;DOS Retro |url=https://pcdosretro.github.io/ |access-date=2014-01-10 |url-status=live |archive-url=https://web.archive.org/web/20200221141654/https://sites.google.com/site/pcdosretro/ |archive-date=2020-02-21}}</ref>
<ref name="HGST_2009">{{cite web |title=Drivers and Software for Legacy (Discontinued) Products |publisher=[[HGST]] |date=2009 |url=http://www.hgst.com/support/downloads/legacy-downloads |access-date=2014-02-13 |url-status=dead |archive-url=https://web.archive.org/web/20140304052713/http://www.hgst.com/support/downloads/legacy-downloads |archive-date=2014-03-04}}</ref>
<ref name="Lenovo">{{cite web |title=How to use the pre-boot service partition to recover your software |publisher=[[Lenovo]] |url=http://support.lenovo.com/en_US/detail.page?LegacyDocID=MIGR-4UFUYK |access-date=2014-02-11 |quote=An additional undocumented feature added to the User Interface is the ability to drop directly out to a DOS prompt. Pressing F3 (there is no prompt for this) will exit the recovery utility and go to a DOS prompt}}</ref>
<ref name="IBM_ServerGuide">{{cite web |title=IBM ServerGuide Scripting Toolkit, DOS Edition |version=1.3.07 |date=2008-01-24 |publisher=[[IBM]] |id=MIGR-53564 |url=http://www-947.ibm.com/support/entry/portal/docdisplay?lndocid=MIGR-53564 |access-date=2014-02-13 |url-status=dead |archive-url=https://web.archive.org/web/20160311025324/https://www-947.ibm.com/support/entry/portal/docdisplay?lndocid=MIGR-53564 |archive-date=2016-03-11}}</ref>
<ref name="Symantec_Ghost">{{cite web |title=Create a Standard Ghost Boot Disk |publisher=[[NortonLifeLock|Symantec]] |date=2004-01-03 |id=TECH108761 |url=http://www.symantec.com/docs/TECH108761 |archive-url=https://archive.today/20140213155128/http://www.symantec.com/docs/TECH108761 |url-status=dead |archive-date=13 February 2014 |access-date=2014-02-13}}</ref>
<ref name="Beley_1986">{{Cite book |editor-first1=Jim |editor-last1=Beley |editor-first2=Barry |editor-last2=Preppernau |editor-first3=Pam |editor-last3=Beason |editor-first4=Andrea |editor-last4=Lewis |editor-first5=David |editor-last5=Rygmyr |author-first1=Howard |author-last1=Bornstein |author-first2=Lawrence |author-last2=Bredehoeft |author-first3=Ray |author-last3=Duncan |author-first4=Carol |author-last4=Morris |author-first5=David |author-last5=Rose <!-- |author-link5=David Rose --> |author-first6=John |author-last6=Socha |author-link6=John Socha |author-first7=Jim |author-last7=Tomlin |author-first8=Kathleen |author-last8=Vian |author-first9=Van |author-last9=Wolverton |title=MS-DOS (Versions 1.0-3.2) Technical Reference Encyclopedia |contribution=Technical advisors |contributor-first1=Paul |contributor-last1=Allen |contributor-link1=Paul Allen |contributor-first2=Bill |contributor-last2=Gates |contributor-link2=Bill Gates |contributor-first3=Adrian |contributor-last3=King |contributor-first4=Chris |contributor-last4=Larson |contributor-first5=Gordon |contributor-last5=Letwin |contributor-link5=Gordon Letwin |contributor-first6=Bob |contributor-last6=O'Rear |contributor-link6=Bob O'Rear |contributor-first7=Tim |contributor-last7=Paterson |contributor-link7=Tim Paterson |contributor-first8=Chris |contributor-last8=Peters |contributor-first9=Bruce |contributor-last9=Phillips |contributor-first10=Aaron |contributor-last10=Reynolds |contributor-link10=Aaron R. Reynolds |contributor-first11=Betty |contributor-last11=Stillmaker |contributor-first12=Mark |contributor-last12=Zbikowski |contributor-link12=Mark Zbikowski |date=1986 |edition=Original withdrawn |publisher=[[Microsoft Press]] |series=Microsoft Reference Library |volume=1 |location=Redmond, Washington, USA |isbn=0-914845-69-1 |lccn=86-8640 |oclc=635600205}} (xvii+1053 pages; 29&nbsp;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. [https://blogs.msdn.microsoft.com/larryosterman/2004/06/14/does-anyone-remember-the-original-ms-dos-encyclopedia/])</ref>
<ref name="Duncan_1988">{{cite book |title=The MS-DOS Encyclopedia: versions 1.0 through 3.2 |author-first1=Ray |author-last1=Duncan |author-first2=Steve |author-last2=Bostwick |author-first3=Keith |author-last3=Burgoyne |author-first4=Robert A. |author-last4=Byers |author-first5=Thom |author-last5=Hogan |author-first6=Jim |author-last6=Kyle |author-first7=Gordon |author-last7=Letwin |author-link7=Gordon Letwin |author-first8=Charles |author-last8=Petzold |author-link8=Charles Petzold |author-first9=Chip |author-last9=Rabinowitz |author-first10=Jim |author-last10=Tomlin |author-first11=Richard |author-last11=Wilton |author-first12=Van |author-last12=Wolverton |author-first13=William |author-last13=Wong |author-first14=JoAnne |author-last14=Woodcock |contribution=Technical advisors |contributor-first1=Mark |contributor-last1=Zbikowski |contributor-link1=Mark Zbikowski |contributor-first2=Paul |contributor-last2=Allen |contributor-link2=Paul Allen |contributor-first3=Steve |contributor-last3=Ballmer |contributor-link3=Steve Ballmer |contributor-first4=Reuben |contributor-last4=Borman |contributor-first5=Rob |contributor-last5=Borman |contributor-first6=John |contributor-last6=Butler |contributor-first7=Chuck |contributor-last7=Carroll |contributor-first8=Mark |contributor-last8=Chamberlain |contributor-first9=David |contributor-last9=Chell |contributor-first10=Mike |contributor-last10=Colee |contributor-first11=Mike |contributor-last11=Courtney |contributor-first12=Mike |contributor-last12=Dryfoos |contributor-first13=Rachel |contributor-last13=Duncan |contributor-first14=Kurt |contributor-last14=Eckhardt |contributor-first15=Eric |contributor-last15=Evans |contributor-first16=Rick |contributor-last16=Farmer |contributor-first17=Bill |contributor-last17=Gates |contributor-link17=Bill Gates |contributor-first18=Michael |contributor-last18=Geary |contributor-first19=Bob |contributor-last19=Griffin |contributor-first20=Doug |contributor-last20=Hogarth |contributor-first21=James W. |contributor-last21=Johnson |contributor-first22=Kaamel |contributor-last22=Kermaani |contributor-first23=Adrian |contributor-last23=King |contributor-first24=Reed |contributor-last24=Koch |contributor-first25=James |contributor-last25=Landowski |contributor-first26=Chris |contributor-last26=Larson |contributor-first27=Thomas |contributor-last27=Lennon |contributor-first28=Dan |contributor-last28=Lipkie |contributor-first29=Marc |contributor-last29=McDonald |contributor-link29=Marc McDonald |contributor-first30=Bruce |contributor-last30=McKinney |contributor-first31=Pascal |contributor-last31=Martin |contributor-first32=Estelle |contributor-last32=Mathers |contributor-first33=Bob |contributor-last33=Matthews <!-- |contributor-link33=Robert Matthews (scientist)??? --> |contributor-first34=David |contributor-last34=Melin |contributor-first35=Charles |contributor-last35=Mergentime |contributor-first36=Randy |contributor-last36=Nevin |contributor-first37=Dan |contributor-last37=Newell |contributor-first38=Tani |contributor-last38=Newell |contributor-first39=David |contributor-last39=Norris |contributor-first40=Mike |contributor-last40=O'Leary |contributor-first41=Bob |contributor-last41=O'Rear |contributor-link41=Bob O'Rear |contributor-first42=Mike |contributor-last42=Olsson |contributor-first43=Larry |contributor-last43=Osterman |contributor-first44=Ridge |contributor-last44=Ostling |contributor-first45=Sunil |contributor-last45=Pai |contributor-first46=Tim |contributor-last46=Paterson |contributor-link46=Tim Paterson |contributor-first47=Gary |contributor-last47=Perez |contributor-first48=Chris |contributor-last48=Peters |contributor-first49=Charles |contributor-last49=Petzold |contributor-link49=Charles Petzold |contributor-first50=John |contributor-last50=Pollock |contributor-first51=Aaron |contributor-last51=Reynolds |contributor-link51=Aaron R. Reynolds |contributor-first52=Darryl |contributor-last52=Rubin |contributor-first53=Ralph |contributor-last53=Ryan |contributor-first54=Karl |contributor-last54=Schulmeisters |contributor-first55=Rajen |contributor-last55=Shah |contributor-first56=Barry |contributor-last56=Shaw |contributor-first57=Anthony |contributor-last57=Short |contributor-first58=Ben |contributor-last58=Slivka |contributor-first59=Jon |contributor-last59=Smirl |contributor-first60=Betty |contributor-last60=Stillmaker |contributor-first61=John |contributor-last61=Stoddard |contributor-first62=Dennis |contributor-last62=Tillman |contributor-first63=Greg |contributor-last63=Whitten |contributor-first64=Natalie |contributor-last64=Yount |contributor-first65=Steve |contributor-last65=Zeck |date=1988 |edition=Completely reworked |publisher=[[Microsoft Press]] |location=Redmond, Washington, USA |isbn=1-55615-049-0 |lccn=87-21452 |oclc=16581341}} (xix+1570 pages; 26&nbsp;cm) (NB. This edition was published in 1988 after extensive rework of the withdrawn 1986 first edition by a different team of authors. [https://www.pcjs.org/pubs/pc/reference/microsoft/mspl13/msdos/encyclopedia/])</ref>
}}

== Further reading ==
* IBM Corporation and Microsoft, Inc. ''DOS 3.30: User's Guide''. IBM Corporation, 1987. Part number 80X0933.
* IBM Corporation and Microsoft, Inc. ''DOS 3.30: Reference (Abridged)''. IBM Corporation, 1987. Part number 94X9575.
* IBM Corporation. ''Getting Started with Disk Operating System Version 4.00''. IBM Corporation, 1988. Part number 15F1370.
* IBM Corporation. ''Using Disk Operating System Version 4.00''. IBM Corporation, 1988. Part number 15F1371.
* IBM Corporation. ''IBM Disk Operating System Version 5.0. User Guide and Reference''. IBM Corporation, 1991. Part number 07G4584.
* Que Corporation. ''IBM PC&nbsp;DOS and Microsoft Windows User's Guide''. Suzanne Weixel, 2nd ed., Indianapolis, 1995. {{ISBN|0-7897-0276-2}}.
* IBM Corporation. ''PC&nbsp;DOS 7 User's Guide''. Margaret Averett, 1995. Part number 83G9260 (S83G-9260-00). 
* IBM Corporation. [https://web.archive.org/web/20120205202422/http://www.redbooks.ibm.com/abstracts/gg244459.html PC&nbsp;DOS 7 Technical Update]. [[IBM Redbooks]], 1995. {{ISBN|0-7384-0677-5}}.

{{IBM operating systems}}
{{Disk operating systems}}
{{Authority control}}

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