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MS-DOS (short for Microsoft Disk Operating System) is an operating
system commercialised by Microsoft. It was the most commonly used member of
the DOS family of operating systems and was the dominant operating system for
the PC compatible platform during the 1980s. It has gradually been replaced
on consumer desktop computers by various generations of the Windows operating
system.
MS-DOS was originally released in 1981 and had eight major versions
released before Microsoft stopped development in 2000. 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 also provided the platform on which early versions of
Windows ran.
Contents
1) History
1.1) Versions and release dates
2) Features
2.1) User interface
2.2) Multitasking
3) Competition
4) End of MS-DOS
5) Legal issues
6) Legacy compatibility
7f) Related systems
1) History
MS-DOS began as QDOS (for Quick and Dirty Operating System), written by
Tim Paterson for computer manufacturer Seattle Computer Products (SCP) in
1980. It was marketed by SCP as 86-DOS because it was designed to run on the
Intel 8086 processor. 86-DOS function calls were based on the dominant
CP/M-80 operating system, written by Digital Research, but it used a
different file system. Paterson allegedly wrote it because he liked CP/M, but
a version of CP/M didn't yet exist for the 8086. In a sequence of events that
would later inspire much folklore, Microsoft negotiated a license for 86-DOS
from SCP in December 1980 for $25,000, then re-licensed 86-DOS to IBM.
Microsoft then acquired all rights to 86-DOS for only $50,000 from SCP in
July, 1981, shortly before the PC's release.
IBM both released versions of DOS; the IBM version was supplied with
the IBM PC and known as PC-DOS. Originally, IBM only validated and packaged
Microsoft developments, and thus IBM's versions tended to be released shortly
after Microsoft's. However, MS-DOS 4.0 was actually based on IBM PC-DOS 4.0,
as Microsoft was by then concentrating on OS/2. Microsoft released its versions
under the name "MS-DOS", while IBM released its versions under the name
"PC-DOS". Initially, when Microsoft would license their OEM version of
MS-DOS, the computer manufacturer would customize its name, Compaq DOS, etc).
Most of these versions were identical to the official MS-DOS; however,
Microsoft began to insist that OEMs start calling the product MS-DOS.
Eventually, only IBM resisted this move.
Computer advertisements of this period often claimed that computers
were "IBM-Compatible" or very rarely "MS-DOS compatible". The two terms were
not synonyms. There were computers that used MS-DOS but couldn't run all the
software that an IBM-Compatible machine could. An example is the Morrow Pivot,
which used MS-DOS but was not IBM-Compatible.
1.1) Versions and release dates
* MS-DOS 1.14 - July 1981 - Microsoft rebranded 86-DOS as MS-DOS in July 1981,
having bought the rights from SCP.
* PC DOS 1.0 - August 1981 - initial release with the first IBM-PC,
essentially MS-DOS 1.14 with a CP/M style prompt (COMMAND.COM is 4959 bytes)
* PC DOS 1.1 - May 1982 - support for 320 kB double-sided floppy disk.
* Developed internally at Microsoft as MS-DOS 1.24.
* MS-DOS 1.25 - May 1982 - first release for IBM PC compatibles marketed
under different brands (COMMAND.COM is 4986 bytes)
* MS-DOS 2.0 - March 1983 - support for PC XT : introduced subdirectories,
handle-based file operations, command input/output redirection, and pipes.
Microsoft decided to use backslashes (\) as pathname separators rather than
slashes as on Unix, apparently due to the latter character being used as
the switch (/) character in most DOS and CP/M programs. Adds support for
hard drives and 360KB floppy disks
This new version of DOS had unexpected consequences: Occasionally a user
would learn the hard way that the command "FORMAT [no options]" formats the
hard disk ( DRIVE C: ) by default. This could be disconcerting to a user
that has just inserted a floppy, listed its directory (DIR), and been
informed that no directory existed. The default had been the first floppy
drive in earlier versions of MS-DOS, but the designers of MS_DOS had found
it convenient to change the default to the most-used drive when hard drives
were supported. For the developers, deleting the operating system wouldn't
have been a major problem, because they could easily replace it; for a
customer, losing the operating system-and several months' work- could be
catastrophic.
* PC DOS 2.1 - October 1983 - support for IBM PCjr.
* MS-DOS 2.11 - March 1984 - non-English language and date format support
(COMMAND.COM is 16229 bytes).
* MS-DOS 2.25 - October 1985 - better support for Japanese Kanji and Korean
character sets, shipped to western Pacific countries only.
* MS-DOS 3.0 - August 1984 - added support for PC AT: 1.2 MB floppy disks and
hard disk partitions of up to 32MB, one primary and one "logical drive" in
an "extended partition"
* MS-DOS 3.1 - November 1984 - support for Microsoft networking.
* MS-DOS 3.2 - January 1986 - support for 3.5 inch, 720 kB floppy disk drives
(v 3.21 COMMAND.COM is 23612 bytes).
* PC DOS 3.3 - April 1987 - support for IBM PS/2: 1.44 MB floppy disk drives,
added codepage support (international character sets) (COMMAND.COM is 25307
bytes).
* MS-DOS 3.3 - August 1987 - supported multiple logical drives (COMMAND.COM
is 25273 bytes).
* MS-DOS 4.0 - June 1988 - derived from IBM's codebase rather than Microsoft's
* PC DOS 4.0 - July 1988 - added DOS Shell & support for hard disks of >32MB
using the format from Compaq DOS 3.31. But it had many bugs and less free
conventional memory than before. Generally regarded as an unpopular release.
* MS-DOS 4.01 - December 1988 - bug-fix release (COMMAND.COM is 37557 bytes)
* MS-DOS 5.0 - June 1991 - memory management, full-screen editor, QBasic
programming language, online help, DOS Shell task switcher, and FastLynx
file transfer utility licensed from Rupp Technology. Also used as the basis
for Virtual DOS Machine for Windows NT4 through Vista. (COMMAND.COM is
47845 bytes)
* MS-DOS 6.0 - March 1993 - added DoubleSpace disk compression, disk
defragmentation, and other features (COMMAND.COM is 52925 bytes)
* MS-DOS 6.2 - November 1993 - bug fix release (COMMAND.COM is 54619 bytes)
* MS-DOS 6.21 - February, 1994 - following Stac Electronics lawsuit, removed
DoubleSpace disk compression (COMMAND.COM is 54619 bytes)
* PC DOS 6.3 - April 1994
* MS-DOS 6.22 - June 1994 - last official stand-alone version. DoubleSpace
replaced with non-infringing but compatible DriveSpace tool (COMMAND.COM is
54645 bytes)
* PC DOS 7.0 - April, 1995 - bundles Stacker in place of DriveSpace
* MS-DOS 7.0 - August 1995 - shipped embedded in Windows 95. Included Logical
block addressing and Long File Name (LFN) support (COMMAND.COM is 92870
bytes)
* MS-DOS 7.1 - August 1996 - shipped embedded in Windows 95B (OSR2) (and
Windows 98 first and second editions in June 1998 and May 1999). Added
support for FAT32 (File Allocation Table) file system (COMMAND.COM is
93812, 93880 or 93890 bytes in 95B, 98 or 98SE respectively)
* MS-DOS 8.0 - September 2000 <//2000> - shipped embedded in Windows Me. A
subset is included with 32-bit versions of Windows XP and Windows Vista.
Last version of MS-DOS. Removes SYS command, ability to boot to command
line and other features (COMMAND.COM is 93040 bytes)
* PC DOS 2000 - year 2000 -compliant version with minor additional features.
Final member of the MS-DOS family
(Adapted from original source: PC Museum)
2) Features
2.1) User interface
MS-DOS employs a command line interface and a batch scripting facility
via its command interpreter, COMMAND.COM. MS-DOS was designed so users could
easily substitute a different command line interpreter, for example 4DOS.
Beginning with version 4.0, MS-DOS included DOS Shell, a file manager
program with a quasi-graphical text user interface (TUI) that featured menus,
split windows, color themes, mouse support and program shortcuts using
character mode graphics.
2.2) Multitasking
MS-DOS wasn't designed to be a multi-user or multitasking operating
system, but many attempts were made to add these capabilities. Terminate and
Stay Resident (TSR) system calls were originally designed for device drivers
and extensible plugins that enhanced or added features. Companies such as
Borland began to tap into the TSR design with products like SideKick. Add-on
environments like TopView and especially DESQview attempted to provide
multitasking, and achieved some success when later combined with the virtual
8086 mode and virtual memory features of the Intel 80386 and later processors.
3) Competition
On the IBM PC (and clones) platform, the initial competition to the
PC-DOS/MS-DOS line came from Digital Research, whose CP/M operating system
had inspired MS-DOS. Digital Research developed CP/M-86 and offered it to
computer manufacturers as an alternate to MS-DOS and Microsoft's licensing
requirements.
In the business world, the PC platform that MS-DOS was tied to faced
competition from the Unix operating system which ran on many different
hardware architectures. Microsoft even sold a version of Unix called Xenix.
In the emerging world of home users, a variety of other hardware
platforms were in serious competition with the IBM PC: the Apple II, early
Apple Macintosh, the Commodore 64 and others. At first, the competition for
these other platforms was with IBM PC computers running MS-DOS. With the
advent of IBM PC clones all running on Intel processors, the name IBM became
less important to home users. What was important was keeping up with Intel's
steadily increasing clock speeds and the ability to run MS-DOS.
Microsoft and IBM together began what was intended as the follow-on to
DOS, called OS/2. When OS/2 was released in 1987, Microsoft began an ad
campaign announcing that "DOS is Dead", boldly proclaiming version 4 was the
last full release.
MS-DOS had grown in spurts, with many significant features being taken
(or duplicated) from other products and operating systems, as well as
reverse-engineering tools and utilities including Norton Utilities, PC Tools
(Microsoft Anti-Virus), QEMM expanded memory manager, DOS/4GW (a 32-bit DOS
extender), Stacker disk compression, and so on. The advent of OS/2, which
offered a number of advanced features which had been written together, was
seen as the legitimate heir to the "kludgy" DOS platform.
Digital Research, recognizing the need to continue the lower-level
platform represented by DOS, then developed DR DOS 5, which mirrored the OS/2
"platform integration" model by adding features which were available only 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
of 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 has 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 cops 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" .
The pact between Microsoft and IBM to promote OS/2 began to fall apart
in 1990 when Windows 3.0 became a marketplace success. Much of Microsoft's
further contributions to OS/2 also went in to creating a third GUI 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.
4) End of MS-DOS
MS-DOS has effectively ceased to exist as a platform for desktop
computing. Since the releases of Windows 9x, it was integrated as a full
product mostly used for bootstrapping, and no longer officially released as
a standalone DOS. It was still available, but became increasingly irrelevant
as development shifted to the Windows API.
Windows XP contains a copy of the core MS-DOS 8 files from Windows
Millennium, accessible only by formatting a floppy as an "MS-DOS startup
disk". Attempting to run COMMAND.COM from such a disk under the NTVDM results
in the message "Incorrect MS-DOS version".
With Windows Vista the files on the startup disk are dated 18th April
2005 but are otherwise unchanged, including the string "MS-DOS Version 8 (C)
Copyright 1981-1999 Microsoft Corp" inside COMMAND.COM.
Today, DOS is still used in embedded x86 systems due to its simple
architecture, and minimal memory and processor requirements. The command line
interpreter of Windows NT, cmd.exe maintains most of the same commands and
some compatibility with DOS batch files.
5) Legal issues
As a response to Digital Research's DR-DOS 6.0, which bundled SuperStor
disk compression, Microsoft opened negotiations with Stac Electronics, vendor
of the most popular DOS disk compression tool, Stacker. In the due diligence
process, Stac engineers had shown Microsoft some 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 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 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 US government Federal Trade Commission
began investigating Microsoft's licensing procedures resulting in a 1994
settlement agreement limiting Microsoft to per-copy licensing. Digital
Research didn't gain by this settlement, and years later its successor in
interest Caldera sued Microsoft for damages. This lawsuit was settled with a
monetary payment of 150 million dollars.
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 QuickC v2.5, a.k.a. Programmer's Workbench and Microsoft C
v6.0, modified the program's Program 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).
The (once infamous) AARD code, a block of code in Windows 3.1's WIN.COM
that was XOR encrypted, self-modifying, and deliberately obfuscated,
that used various undocumented DOS structures and functions to
determine whether or not Windows really was running on MS-DOS.
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.
6) Legacy compatibility
From 1983 onwards, various companies have worked on graphical user
interfaces (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, and the Norton Shell. However, this required
duplication of effort and didn't provide much consistency in interface
design (even between products from the same company).
Later, in 1985, Microsoft Windows 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. After version 3.0 (1990),
Windows gained marked 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 ran independently of DOS but
included a DOS subsystem so applications could run in a virtual machine 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.
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º Compilled from Wikipedia.com . Translatted to ASCII by LW1DSE Osvaldo º
º F. Zappacosta. Barrio Garay, Almirante Brown, Buenos Aires, Argentina. º
º Made with MSDOS 7.10's Text Editor (edit.com) in my AMD's 80486. º
º November 24, 2007 º
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