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The FreeDOS startup sequence.

DOS, short for "Disk Operating System",[1] is a shorthand term for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millenium Edition.

Related systems include MS-DOS, PC DOS, DR-DOS, FreeDOS, PTS-DOS, ROM-DOS, JM-OS, and several others.

In spite of the common usage, none of these systems were named simply "DOS" (a name given only to an unrelated IBM mainframe operating system in the 1960s). A number of unrelated, non-x86 microcomputer disk operating systems had "DOS" in their name, and are often referred to simply as "DOS" when discussing machines that use them (e.g. AmigaDOS, AMSDOS, ANDOS, Apple DOS, Atari DOS, Commodore DOS, CSI-DOS, ProDOS, and TRS-DOS). While providing many of the same operating system functions for their respective computer systems, programs running under any one of these operating systems would not run under others.

Contents

Design

All DOS-type operating systems run on machines with the Intel x86 or compatible CPUs, mainly the IBM PC and compatibles. Initially, DOS was not restricted to these, and machine-dependent versions of DOS and similar operating systems were produced for many non-IBM-compatible x86-based machines.[2] In particular, DOS-C's predecessor DOS/NT ran on Motorola 68000 CPU's.

DOS is a single-user, single-task operating system with basic kernel functions that are non-reentrant: only one program at a time can use them. There is an exception with Terminate and Stay Resident (TSR) programs, and some TSRs can allow multitasking. However, there is still a problem with the non-reentrant kernel: once a process calls a service inside of operating system kernel (system call), it must not be interrupted with another process calling system call, until the first call is finished.[3]

The DOS kernel provides various functions for programs, like displaying characters on-screen, reading a character from the keyboard, accessing disk files and more.

API

Scripting

DOS by default provides a primitive ability for shell scripting, via batch files (with the filename extension .BAT). These are text files that can be created in any DOS text editor, such as the MS-DOS Editor. They are executed in the same fashion as compiled programs, and run each line of the batch file as a command. Batch files can also make use of several internal commands, such as goto and conditional statements.[4] gosub and simple arithmetic is supported in some third-party shells but can also be faked via strange workarounds; however, no real form of programming is usually enabled.

The operating system offers a hardware abstraction layer that allows development of character-based applications, but not for accessing most of the hardware, such as graphics cards, printers, or mice. This required programmers to access the hardware directly, usually resulting in each application having its own set of device drivers for each hardware peripheral. Hardware manufacturers would release specifications to ensure device drivers for popular applications were available.[5]

Reserved device names

There are reserved device names in DOS that cannot be used as filenames regardless of extension; these are used to send application output to hardware peripherals. These restrictions also affect several Windows versions, in some cases causing crashes and security vulnerabilities.[6]

A partial list of these reserved names is: NUL:, COM1: or AUX:, COM2:, COM3:, COM4:, CON:, LPT1: or PRN:, LPT2:, LPT3:, and CLOCK$.[7]

Drive naming scheme

In DOS, drives are referred to by identifying letters. Standard practice is to reserve "A" and "B" for floppy drives. On systems with only one floppy drive DOS assigns both letters to the drive, prompting the user to swap disks as programs alternate access between them. This facilitates copying from floppy to floppy or having a program run from one floppy while accessing its data on another. Hard drives were originally assigned the letters "C" and "D". DOS could only support one active partition per drive. As support for more hard drives became available, this developed into first assigning a drive letter to each drive's active primary partition, then making a second pass over the drives to allocate letters to logical drives in the extended partition, then a third pass to give any other non-active primary partitions their names (where such additional partitions existed and contained a DOS-supported file system.) Lastly, DOS allocates letters for optical disc drives, RAM disks, and other hardware. Letter assignments usually occur in the order the drivers are loaded, but the drivers can instruct DOS to assign a different letter; drivers for network drives, for example, typically assign letters nearer the end of the alphabet.[8]

Because DOS applications use these drive letters directly (unlike the /dev directory in Unix-like systems), they can be disrupted by adding new hardware that needs a drive letter. An example is the addition of a new hard drive having a primary partition where a pre-existing hard drive contains logical drives in extended partitions; the new drive will be assigned a letter that was previously assigned to one of the extended partition logical drives. Moreover, even adding a new hard drive having only logical drives in an extended partition would still disrupt the letters of RAM disks and optical drives. This problem persisted through the 9x versions of Windows until NT, which preserves the letters of existing drives until the user changes them.[8]

Boot sequence

  • The boot sector on PC-compatible computers (MBR) is located at track zero. The boot sector on all disc devices are then in turn loaded into memory segment 0000:7C00, and if the sector contains the values "0x55 0xAA" at position 0x1FE, it's considered to be valid and is executed. On harddiscs each of the four partitions are searched for an active partition (bit-7=1 at pos 0x1BE+0x10*n).
  • The boot sector code loads the DOS-BIOS into segment 0000:0600; which is located in the file IO.SYS on MS-DOS systems.[9] In some cases the boot sector instead relocates itself into 0000:0600 and loads the partition boot code into 0000:7C00 and executes it.[10]
  • The DOS-BIOS will then load the DOS kernel, located in MSDOS.SYS on MS-DOS systems. In the DOS-kernel Windows 9x, the DOS-BIOS and kernel are combined in IO.SYS, and MSDOS.SYS is used as a text configuration file.
  • The kernel then loads the \CONFIG.SYS file to parse configuration parameters. The SHELL variable specifies the location of the shell which defaults to \COMMAND.COM.
  • The shell is loaded and executed.
  • The startup batch file AUTOEXEC.BAT is then run by the shell.[11][12] DR-DOS allows specification of the startup batch file through a parameter in the SHELL statement.[13][14]:392

The BIOS and kernel files loaded by the boot sector must be contiguous and be the first two directory entries.[15] As such, removing and adding this file is likely to render the media unbootable. It is, however, possible to replace the shell at will, a method that can be used to start the execution of dedicated applications faster.

In DR-DOS and PC-DOS IBMBIO.COM is used in place of IO.SYS and IBMDOS.COM in place of MSDOS.SYS.

On systems designed for PC-DOS v1.10 the signature 0x55 0xAA at position 0x1FE is not checked.[16]

Origins

IBM PC-DOS (and the separately sold MS-DOS, which was licensed therefrom), and its predecessor, 86-DOS, were loosely inspired by CP/M (Control Program / [for] Microcomputers) from Digital Research, which was the dominant disk operating system for 8-bit Intel 8080 and Zilog Z80 based microcomputers. However, PC-DOS never ran on less than an 8088 (16-bit).

When IBM introduced their first microcomputer in 1980, built with the Intel 8088 microprocessor, they needed an operating system. Seeking an 8088-compatible build of CP/M, IBM initially approached Microsoft CEO Bill Gates (possibly believing that Microsoft owned CP/M due to the Microsoft Z-80 SoftCard, which allowed CP/M to run on an Apple II[17]). IBM was sent to Digital Research, and a meeting was set up. However, the initial negotiations for the use of CP/M broke down—Digital Research wished to sell CP/M on a royalty basis, while IBM sought a single license, and to change the name to "PC DOS". DR founder Gary Kildall refused, and IBM withdrew.[17][18]

IBM again approached Bill Gates. Gates in turn approached Seattle Computer Products. There, programmer Tim Paterson had developed a variant of CP/M-80, intended as an internal product for testing SCP's new 16-bit Intel 8086 CPU card for the S-100 bus. The system was initially named "QDOS" (Quick and Dirty Operating System), before being made commercially available as 86-DOS. Microsoft purchased 86-DOS, allegedly for $50,000. This became Microsoft Disk Operating System, MS-DOS, introduced in 1981.[19]

Microsoft also licensed their system to multiple computer companies, who supplied MS-DOS for their own hardware, sometimes under their own names. Microsoft later required the use of the MS-DOS name, with the exception of the IBM variant. IBM continued to develop their version, PC DOS, for the IBM PC.[19] Digital Research became aware that an operating system similar to CP/M was being sold by IBM (under the same name that IBM insisted upon for CP/M), and threatened legal action. IBM responded by offering an agreement: they would give PC consumers a choice of PC DOS or CP/M-86, Kildall's 8086 version. Side-by-side, CP/M cost almost $200 more than PC DOS, and sales were low. CP/M faded, with MS-DOS and PC DOS becoming the marketed operating system for PCs and PC compatibles.[17]

Digital Research attempted to regain the market lost from CP/M-86; initially with DOS Plus, and later with DR-DOS (both compatible with both MS-DOS and CP/M-86 software). Digital Research was bought by Novell, and DR DOS became Novell DOS 7; later, it was part of Caldera Systems (under the names OpenDOS and DR DOS 7), Lineo, and DeviceLogics.

Microsoft and IBM later had a series of disagreements over two successor operating systems to DOS - Microsoft's Windows and IBM's OS/2.[20] They split development of their DOS systems as a result.[21] MS-DOS was partially transformed into Windows; the last version of PC DOS was PC DOS 2000, released in 1998.

The FreeDOS project began June 26, 1994, when Microsoft announced it would no longer sell or support MS-DOS. Jim Hall then posted a manifesto proposing the development of an open-source replacement. Within a few weeks, other programmers including Pat Villani and Tim Norman joined the project. A kernel, the command.com command line interpreter (shell) and core utilities were created by pooling code they had written or found available. There were several official pre-release distributions of FreeDOS before the FreeDOS 1.0 distribution was released on September 3, 2006. Made available under the GNU General Public License (GPL), FreeDOS does not require license fees or royalties.[22][23]

Decline

Early versions of Microsoft Windows were an application that ran on top of a separate version of DOS.[24] By the early 1990s, Windows saw heavy use on new DOS systems. With MS-Windows for Workgroups 3.11, DOS was almost reduced to the role of a boot loader for the Windows kernel; in 1995, MS-Windows 95 was bundled as a standalone operating system that did not require a separate DOS license. With Windows 95 (and Windows 98 and Me, that followed it), the MS-DOS kernel remains, but with Windows as the system's graphical shell. With Windows 95 and 98, but not ME, the MS-DOS component could be run without starting Windows.[25] With DOS no longer required to use Windows, the majority of PC users abandoned DOS in favor of Windows.

Continued use

Currently available DOS systems are FreeDOS, DR-DOS (and Enhanced DR-DOS), ROM-DOS, the Russian PTS-DOS, NX-DOS, Multiuser DOS (based on Digital Research's Concurrent DOS)[26], and others. Some computer manufacturers, including Dell and HP, sell computers with FreeDOS as the OEM operating system.[27][28] NX-DOS, is currently under development. It is 16-bit, real-time, networkable, bootable from a floppy, and has an incomplete USB driver. It dates back to 1992 as a personal project, and was released as GPL in 2005.[29]

Embedding

DOS' structure of accessing hardware directly makes it ideal for use in embedded devices. The final versions of DR-DOS are still aimed at this market.[30] ROM-DOS was used as the embedded system on the Canon PowerShot Pro 70.[31]

Emulation

DOSBox running on Windows Vista

Under Linux it is also possible to run copies of DOS and many of its clones under DOSEMU, a Linux-native virtual machine for running DOS programs at near native speed. There are a number of other emulators for running DOS under various versions of UNIX, even on non-x86 platforms, such as DOSBox.[32][33]

DOS emulators are gaining popularity among MS-Windows XP and MS-Windows Vista users, due to these systems being very incompatible with pure DOS. They can be used to run games or other DOS software. One of the most well-known is DOSBox, designed for legacy gaming (e.g. King's Quest, Doom) on modern operating systems.[24][32]

It is possible to run DOS applications under Microsoft Virtual PC, allowing better compatibility than DOS emulators. A legitimate version of MS-DOS can be installed which should allow all but the most stubborn applications to run.[34]

With Microsoft Windows

cmd.exe, the DOS-styled command prompt used in Microsoft-NT-based Windows.

True 32-bit versions of Windows, starting with NT and including 2000, XP, and Vista, are not based upon DOS. These include the NT Virtual DOS Machine (NTVDM), which runs a modified version of MS-DOS 5 in a virtual machine. While DOS-based versions used the traditional COMMAND.COM for a command line interface, MS-Windows NT and its derivatives use cmd.exe, a descendant of OS/2's command interpreter which recognizes many DOS commands (although COMMAND.COM is still called and used when DOS .EXE files are run).

Versions

See Comparison of x86 DOS operating systems and Timeline of x86 DOS operating systems.

Software

Arachne web browser
See also:DOS software, CUA (an aim to harmonise DOS applications user interfaces)

DOS was the dominant PC-Compatible platform and many notable programs were written for it. These included:

Ease of use

User interface

Screenshot of a Windows command shell listing the files in a directory

DOS systems utilize a command line interface. Programs are started by entering their filename at the command prompt. DOS systems include several programs as system utilities, and provides additional commands that don't correspond to programs (internal commands).[36]

In an attempt to provide a more user-friendly environment, numerous software manufacturers wrote file management programs that provided users with menu- and/or icon-based interfaces. Microsoft Windows is a notable example, eventually resulting in Microsoft Windows 9x becoming a self-contained program loader, and replacing DOS as the most-used PC-compatible program loader. Text user interface programs included Norton Commander, Dos Navigator, Volkov Commander, Quarterdesk DESQview, and SideKick. Graphical user interface programs included Digital Research's Graphical Environment Manager (originally written for CP/M) and GEOS.

Eventually, the manufacturers of major DOS systems began to include their own environment managers. MS-DOS/IBM DOS 4 included DOS Shell;[37] DR-DOS 5, released the next year, included ViewMAX, based upon GEM.[38]

Multitasking

By its original design, DOS was a single task operating system. MS and PC DOS would introduce task switching with DOSShell,[39] and DR-DOS would include it with DR-DOS 6, via the TaskMAX command.[14]:320–324 MS and PC DOS never had a multitasking capability;[40] DR-DOS had the capability with DR-DOS 7 (assuming DR-DOS was running with DPMI enabled).[41] Programs such as VMIX (shareware) or DesqView (commercial) could multitask even on an 8088, which did not have hardware support for multitasking due to its lack of protected mode.

Limitations

Several limitations plague the DOS architecture. The original 8088 microprocessor could only address 1 megabyte of physical RAM. With additional hardware devices being mapped into this range, the highest amount of available memory was 640 kilobytes, known as conventional memory. Due to DOS' structure, this was assumed to be the maximum, and DOS could not address more than this. An early workaround was expanded memory; later, extended memory was developed with the 80286. While these provided usable memory to applications, they still had to start in conventional memory, thereby using part of the existing 640 KB. With the 80386 microprocessor's redesigned protected mode, DOS extenders and the DOS Protected Mode Interface were able to provide additional memory to applications, as well as multitasking. [42][43]

DOS also has an upper limit to the size of hard disk partitions. This has two causes. First, many DOS-type systems never had support for any file system newer than FAT16, which, by design, does not allow partitions larger than 2.1 gigabytes.[44] Additionally, DOS accesses the hard disk by calling Interrupt 13, which utilizes the cylinder-head-sector system of mapping the disk. Under this system, only 8 gigabytes are visible to the operating system.[45] Newer operating systems accomplished disk access via software means, e.g. 32-bit disk access.

Using FAT16 (and FAT12 for floppy disks) required use of the 8.3 filename. Filenames in DOS can not be longer than eight characters, and the filename extension cannot be longer than three. Win95's patented VFAT hack worked around this in a unique way.

See also

References

  1. ^ Murdock, Everett (1988). DOS the Easy Way. EasyWay Downloadable Books. ISBN 0923178007. 
  2. ^ See MS-DOS
  3. ^ Hyde, Randall (1996-09-30). "CHAPTER EIGHTEEN: RESIDENT PROGRAMS (Part 3)". The Art of Assembly Language Programming. http://oopweb.com/Assembly/Documents/ArtOfAssembly/Volume/Chapter_18/CH18-3.html. Retrieved 2008-09-02. 
  4. ^ "Batch File Help". computerhope.com. http://www.computerhope.com/batch.htm. Retrieved 2008-09-10. 
  5. ^ Matczynski, Michael. "ZINGTECH - Guide to the New Game Programmer". http://www.zingtech.com/features/gamedev/gnewprog.htm. Retrieved 2008-09-02. 
  6. ^ "Microsoft Windows MS DOS Device Name DoS Vulnerability". http://www.juniper.net/security/auto/vulnerabilities/vuln1043.html. Retrieved 2008-09-02. 
  7. ^ "DOS device names definition". PC Magazine. http://www.pcmag.com/encyclopedia_term/0,2542,t=DOS+device+names&i=41766,00.asp. Retrieved 2008-09-02. 
  8. ^ a b "Drive Letter Assignment and Choosing Primary vs. Logical Partitions". The PC Guide. 2007-05-17. http://www.storagereview.com/guide/partLetter.html. Retrieved 2008-09-02. 
  9. ^ "Reverse-Engineering DOS 1.0 – Part 1: The Boot Sector « pagetable.com". http://www.pagetable.com/?p=165.  090912 pagetable.com
  10. ^ "The Master Boot Record (MBR) and What it Does". http://www.dewassoc.com/kbase/hard_drives/master_boot_record.htm.  090912 dewassoc.com
  11. ^ "CONFIG.SYS Commands". http://academic.evergreen.edu/projects/biophysics/technotes/program/config-sys.txt.  090913 academic.evergreen.edu
  12. ^ Kozierok, Charles (2001). "The DOS Boot Process". The PC Guide. http://www.pcguide.com/ref/hdd/file/structBoot-c.html. Retrieved 2008-09-02. 
  13. ^ "DR-DOS 7.02 User Guide chapter 9". Caldera Systems. 1998. http://www.drdos.net/documentation/usergeng/09ugch9.htm. Retrieved 2009-09-15. 
  14. ^ a b DR DOS 6.0 User Guide. Digital Research. 1991. pp. 320–324. 
  15. ^ "misc.txt". http://www.arl.wustl.edu/~lockwood/class/cse306-s04/resources/helppc/misc.txt.html.  090912 arl.wustl.edu
  16. ^ The 55 AA signature is not present at 0x01FE in PC-DOS v1.10 boot image.
  17. ^ a b c Rolander, Tom. Interview. The rest of the story: How Bill Gates beat Gary Kildall in OS war, Part 1.
  18. ^ Bove, Tony (2005). Just Say No to Microsoft. No Starch Press. p. 9–11. ISBN 159327064X. http://books.google.co.uk/books?id=I0RB1Xxp-KAC&pg=PA11&lpg=PA11&dq=ibm+cp/m+licensing&source=web&ots=dryptL9LAW&sig=KJqNIT1r_-yVcpe0fa0p9RI1BW4&hl=en&sa=X&oi=book_result&resnum=10&ct=result#PPA9,M1. 
  19. ^ a b Bellis, Mary. "The Unusual History of MS-DOS The Microsoft Operating System". http://inventors.about.com/library/weekly/aa033099.htm. Retrieved 2008-09-02. 
  20. ^ Pollack, Andrew (1991-07-27). "Microsoft Widens Its Split With I.B.M. Over Software". New York Times. http://query.nytimes.com/gst/fullpage.html?res=9D0CE0D81339F934A15754C0A967958260. Retrieved 2008-09-02. 
  21. ^ Brinkley, Joel (1999-05-28). "I.B.M. Executive Describes Price Pressure by Microsoft". New York Times. http://query.nytimes.com/gst/fullpage.html?res=990DEEDD1630F93BA15756C0A96F958260. Retrieved 2008-09-02. 
  22. ^ Jim Hall (2002-03-25). "The past, present, and future of the FreeDOS Project". http://www.linuxdevices.com/articles/AT3952799051.html. Retrieved 2008-06-14. 
  23. ^ Hall, Jim (September 23, 2006). "History of FreeDOS". freedos.org. http://www.freedos.org/freedos/about/. Retrieved 2007-05-28. 
  24. ^ a b James Bannan (2006-10-13). "HOW TO: Coax retro DOS games to play on Vista". http://apcmag.com/how_to_coax_retro_dos_games_to_play_on_vista.htm. Retrieved 2008-07-03. 
  25. ^ "Finding The DOS In Windows 95". Smart Computing. March 1996. http://www.smartcomputing.com/Editorial/article.asp?article=articles/archive/95win/95win21/95win21.asp&guid=. Retrieved 2008-07-12. 
  26. ^ http://www.conctrls.com/CCInews.html
  27. ^ Hall, Jim (2007-07-13). "Jim Hall". http://www.freedos.org/jhall/. Retrieved 2008-06-12. 
  28. ^ "Dell PCs Featuring FreeDOS". http://www.dell.com/content/topics/segtopic.aspx/e510_nseries?c=us&cs=19&l=en&s=dhs. Retrieved 2008-06-14. 
  29. ^ "GPL'd DOS workalike adds features". 2007-04-01. http://www.linuxdevices.com/news/NS9509696845.html. Retrieved 2008-06-01. 
  30. ^ "DR DOS Embedded DOS". http://www.drdos.com/products/drdos703.htm. Retrieved 2008-09-26. 
  31. ^ "Datalight DOS Selected for Canon's New Line of Digital Still Cameras". Business Wire. 1999-08-24. http://findarticles.com/p/articles/mi_m0EIN/is_1999_Feb_23/ai_53930374. Retrieved 2008-09-26. 
  32. ^ a b "DOSBox Information". http://www.dosbox.com/information.php. Retrieved 2008-05-18. 
  33. ^ "DOSEMU Home". 2007-05-05. http://www.dosemu.org/. Retrieved 2008-07-03. 
  34. ^ "DOS Games on Vista". 2008-03-11. http://www.winvistatips.com/dos-games-on-vista-a102.php. Retrieved 2008-09-02. 
  35. ^ Darrow, Barbara (1 February, 2002). "Whatever Happened To Lotus 1-2-3?". http://www.crn.com/it-channel/18818026. Retrieved 2008-07-12. 
  36. ^ Murdock, Everett. DOS the Easy Way. EasyWay Downloadable Books. pp. 7–12. ISBN 0923178023. 
  37. ^ Murdock, Everett. DOS the Easy Way. EasyWay Downloadable Books. pp. 71. ISBN 0923178023. http://books.google.com/books?id=vrsSflB2o5sC. 
  38. ^ Dvorak, John; Nick Anis (1991). Dvorak's Guide to DOS and PC Performance. Osborne McGraw-Hill. pp. 442–444. 
  39. ^ Murdock, Everett. DOS the Easy Way. EasyWay Downloadable Books. pp. 83. ISBN 0923178023. 
  40. ^ Perry, Greg; Jill Freeze (2003). Sams Teach Yourself Windows XP Computer Basics All in One. Sams Publishing. pp. 445. ISBN 0672325357. http://books.google.co.uk/books?id=FptQSQs0skEC&pg=PA445&dq=ms-dos+multitasking&sig=ACfU3U1yCLlNTSiGByW9TJOZJqmPENSdkQ. 
  41. ^ "Chapter 13 Multitasking and Task Switching". Caldera DR-DOS 7.02 User Guide. Caldera Systems. 1998. http://www.drdos.net/documentation/usergeng/13ugch13.htm. Retrieved 2008-09-12. 
  42. ^ "DOS: still thriving after all these years". Software Magazine. Findarticles.com. May 1990. http://findarticles.com/p/articles/mi_m0SMG/is_n6_v10/ai_8528224. Retrieved 2008-07-10. 
  43. ^ Duncan, Ray (1991). Extending DOS: A Programmer's Guide to Protected-Mode DOS (2 ed.). Addison-Wesley. ISBN 0201567989. 
  44. ^ Mueller, Scott (2003). Upgrading and Repairing PCs. Que Publishing. p. 812. ISBN 0789729741. 
  45. ^ "The Int 13 Interface". The PC Guide. storagereview.com. http://www.storagereview.com/guide2000/ref/hdd/bios/sizeGB8.html. Retrieved 2008-07-10. 
  • IBM Corp., IBM, (January 1984). “IBM DOS Release 2.10 Cloth bound retail hard board box”. 1st edition. IBM Corp. Item Number. 6183946
  • IBM Corp., IBM, (January 1984). “Disk Operating System User's guide (DOS Release 2.10)”. 1st edition. Microsoft Corp. (100 pages including colour illustrations) Item Number. 6183947
  • IBM Corp., IBM, (January 1984). “Disk Operating System Manual (DOS Release 2.10)”. 1st edition. Microsoft Corp. (574 looseleaf pages in 3 ring folder) Item No. 6183940
  • IBM Corp., IBM, (May 1984). “BASIC HANDBOOK General Programming Information (BASIC Release 3.0)”. 3rd edition. IBM Corp. (127 pages) Item Number 6361129
  • IBM Corp., IBM, (May 1984). “BASIC Reference (BASIC Release 3.0)”. 3rd edition. IBM Corp. Item Number 6361134

External links


startup sequence.]]

DOS, short for "Disk Operating System",[1] is a shorthand term for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.

Related systems include MS-DOS, PC-DOS, DR-DOS, FreeDOS, PTS-DOS, ROM-DOS, JM-OS, and several others.

In spite of the common usage, none of these systems were simply named "DOS" (a name given only to an unrelated IBM mainframe operating system in the 1960s). A number of unrelated, non-x86 microcomputer disk operating systems had "DOS" in their name, and are often referred to simply as "DOS" when discussing machines that use them (e.g. AmigaDOS, AMSDOS, ANDOS, Apple DOS, Atari DOS, Commodore DOS, CSI-DOS, ProDOS, and TRS-DOS). While providing many of the same operating system functions for their respective computer systems, programs running under any one of these operating systems would not run under others.

Contents

Design

All MS-DOS-type operating systems run on machines with the Intel x86 or compatible CPUs, mainly the IBM PC and compatibles. Machine-dependent versions of MS-DOS were produced for many non-IBM-compatible x86-based machines, with variations from relabelling of the Microsoft distribution under the manufacturer's name, to versions specifically designed to work with non-IBM-PC-compatible hardware. DOS-C's predecessor DOS/NT ran on Motorola 68000 CPU's.[citation needed]

DOS is a single-user, single-task operating system with basic kernel functions that are non-reentrant: only one program at a time can use them. There is an exception with Terminate and Stay Resident (TSR) programs, and some TSRs can allow multitasking. However, there is still a problem with the non-reentrant kernel: once a process calls a service inside of operating system kernel (system call), it must not be interrupted with another process calling system call, until the first call is finished.[2]

The DOS kernel provides various functions for programs (an application program interface), like displaying characters on-screen, reading a character from the keyboard, accessing disk files and more.

DOS by default provides a primitive ability for shell scripting, via batch files (with the filename extension .BAT). These are text files that can be created in any DOS text editor, such as the MS-DOS Editor. They are executed in the same fashion as compiled programs, and run each line of the batch file as a command. Batch files can also make use of several internal commands, such as goto and conditional statements.[3] gosub and simple arithmetic is supported in some third-party shells but can also be faked via strange workarounds; however, no real form of programming is usually enabled.

The operating system offers a hardware abstraction layer that allows development of character-based applications, but not for accessing most of the hardware, such as graphics cards, printers, or mice. This required programmers to access the hardware directly, usually resulting in each application having its own set of device drivers for each hardware peripheral. Hardware manufacturers would release specifications to ensure device drivers for popular applications were available.[4]

Drive naming scheme

In DOS, drives are referred to by identifying letters. Standard practice is to reserve "A" and "B" for floppy drives. On systems with only one floppy drive DOS assigns both letters to the drive, prompting the user to swap disks as programs alternate access between them. This facilitates copying from floppy to floppy or having a program run from one floppy while accessing its data on another. Hard drives were originally assigned the letters "C" and "D". DOS could only support one active partition per drive. As support for more hard drives became available, this developed into first assigning a drive letter to each drive's active primary partition, then making a second pass over the drives to allocate letters to logical drives in the extended partition, then a third pass to give any other non-active primary partitions their names (where such additional partitions existed and contained a DOS-supported file system.) Lastly, DOS allocates letters for optical disc drives, RAM disks, and other hardware. Letter assignments usually occur in the order the drivers are loaded, but the drivers can instruct DOS to assign a different letter; drivers for network drives, for example, typically assign letters nearer the end of the alphabet.[5]

Because DOS applications use these drive letters directly (unlike the /dev directory in Unix-like systems), they can be disrupted by adding new hardware that needs a drive letter. An example is the addition of a new hard drive having a primary partition where a pre-existing hard drive contains logical drives in extended partitions; the new drive will be assigned a letter that was previously assigned to one of the extended partition logical drives. Moreover, even adding a new hard drive having only logical drives in an extended partition would still disrupt the letters of RAM disks and optical drives. This problem persisted through the 9x versions of Windows until NT, which preserves the letters of existing drives until the user changes them.[5]

Reserved device names

There are reserved device names in DOS that cannot be used as filenames regardless of extension; these are used to send application output to hardware peripherals. These restrictions also affect several Windows versions, in some cases causing crashes and security vulnerabilities.[6]

A partial list of these reserved names is: NUL:, COM1: or AUX:, COM2:, COM3:, COM4:, CON:, LPT1: or PRN:, LPT2:, LPT3:, and CLOCK$.[7]

Boot sequence

  • The boot sector on PC-compatible computers (MBR) is located at track zero. The boot sector on all disc devices are then in turn loaded into memory segment 0000:7C00, and if the sector contains the values "0x55 0xAA" at position 0x1FE, it's considered to be valid and is executed. On harddiscs each of the four partitions are searched for an active partition (bit-7=1 at pos 0x1BE+0x10*n).
  • The boot sector code loads the DOS-BIOS into segment 0000:0600; which is located in the file IO.SYS on MS-DOS systems.[8] In some cases the boot sector instead relocates itself into 0000:0600 and loads the partition boot code into 0000:7C00 and executes it.[9]
  • The DOS-BIOS will then load the DOS kernel, located in MSDOS.SYS on MS-DOS systems. In the DOS-kernel Windows 9x, the DOS-BIOS and kernel are combined in IO.SYS, and MSDOS.SYS is used as a text configuration file.
  • The kernel then loads the \CONFIG.SYS file to parse configuration parameters. The SHELL variable specifies the location of the shell which defaults to \COMMAND.COM.
  • The shell is loaded and executed.
  • The startup batch file AUTOEXEC.BAT is then run by the shell.[10][11] DR-DOS allows specification of the startup batch file through a parameter in the SHELL statement.[12][13]:392

The BIOS and kernel files loaded by the boot sector must be contiguous and be the first two directory entries.[14] As such, removing and adding this file is likely to render the media unbootable. It is, however, possible to replace the shell at will, a method that can be used to start the execution of dedicated applications faster.

Variations from MS DOS re-name the BIOS and kernel files, for example, in DR-DOS and PC-DOS IBMBIO.COM is used in place of IO.SYS and IBMDOS.COM in place of MSDOS.SYS. On systems designed for PC-DOS v1.10 the signature 0x55 0xAA at position 0x1FE is not checked.[citation needed]

Origins

IBM PC-DOS (and the separately sold MS-DOS, which was licensed therefrom) and its predecessor, 86-DOS, were loosely inspired by Digital Research's CP/M (Control Program / [for] Microcomputers), which was the dominant disk operating system for 8-bit Intel 8080 and Zilog Z80 based microcomputers. PC-DOS ran on 8088 (16-bit) and above.

When IBM introduced their first microcomputer in 1980, built with the Intel 8088 microprocessor, they needed an operating system. Seeking an 8088-compatible build of CP/M, IBM initially approached Microsoft CEO Bill Gates (possibly believing that Microsoft owned CP/M due to the Microsoft Z-80 SoftCard, which allowed CP/M to run on an Apple II[15]). IBM was sent to Digital Research, and a meeting was set up. However, the initial negotiations for the use of CP/M broke down—Digital Research wished to sell CP/M on a royalty basis, while IBM sought a single license, and to change the name to "PC DOS". DR founder Gary Kildall refused, and IBM withdrew.[15][16]

IBM again approached Bill Gates. Gates in turn approached Seattle Computer Products. There, programmer Tim Paterson had developed a variant of CP/M-80, intended as an internal product for testing SCP's new 16-bit Intel 8086 CPU card for the S-100 bus. The system was initially named "QDOS" (Quick and Dirty Operating System), before being made commercially available as 86-DOS. Microsoft purchased 86-DOS, allegedly for $50,000. This became Microsoft Disk Operating System, MS-DOS, introduced in 1981.[17]

Microsoft also licensed their system to multiple computer companies, who supplied MS-DOS for their own hardware, sometimes under their own names. Microsoft later required the use of the MS-DOS name, with the exception of the IBM variant. IBM continued to develop their version, PC DOS, for the IBM PC.[17] Digital Research became aware that an operating system similar to CP/M was being sold by IBM (under the same name that IBM insisted upon for CP/M), and threatened legal action. IBM responded by offering an agreement: they would give PC consumers a choice of PC DOS or CP/M-86, Kildall's 8086 version. Side-by-side, CP/M cost almost $200 more than PC DOS, and sales were low. CP/M faded, with MS-DOS and PC DOS becoming the marketed operating system for PCs and PC compatibles.[15]

Digital Research attempted to regain the market lost from CP/M-86; initially with DOS Plus, and later with DR-DOS (both compatible with both MS-DOS and CP/M-86 software). Digital Research was bought by Novell, and DR DOS became Novell DOS 7; later, it was part of Caldera Systems (under the names OpenDOS and DR DOS 7), Lineo, and DeviceLogics.

Microsoft and IBM later had a series of disagreements over two successor operating systems to DOS - Microsoft's Windows and IBM's OS/2.[18] They split development of their DOS systems as a result.[19] MS-DOS was partially transformed into Windows; the last version of PC DOS was PC DOS 2000, released in 1998.

The FreeDOS project began June 26, 1994, when Microsoft announced it would no longer sell or support MS-DOS. Jim Hall then posted a manifesto proposing the development of an open-source replacement. Within a few weeks, other programmers including Pat Villani and Tim Norman joined the project. A kernel, the command.com command line interpreter (shell) and core utilities were created by pooling code they had written or found available. There were several official pre-release distributions of FreeDOS before the FreeDOS 1.0 distribution was released on September 3, 2006. Made available under the GNU General Public License (GPL), FreeDOS does not require license fees or royalties.[20][21]

Decline

Early versions of Microsoft Windows were an application that ran on top of a separate version of DOS.[22] By the early 1990s, Windows saw heavy use on new DOS systems. With MS-Windows for Workgroups 3.11, DOS was almost reduced to the role of a boot loader for the Windows kernel; in 1995, MS-Windows 95 was bundled as a standalone operating system that did not require a separate DOS license. With Windows 95 (and Windows 98 and Me, that followed it), the MS-DOS kernel remains, but with Windows as the system's graphical shell. With Windows 95 and 98, but not ME, the MS-DOS component could be run without starting Windows.[23] With DOS no longer required to use Windows, the majority of PC users abandoned DOS in favor of Windows.

Continued use

Currently available DOS systems are FreeDOS, DR-DOS (and Enhanced DR-DOS), ROM-DOS, the Russian PTS-DOS, NX-DOS, Multiuser DOS (based on Digital Research's Concurrent DOS)[24], and others. Some computer manufacturers, including Dell and HP, sell computers with FreeDOS as the OEM operating system.[25][26] NX-DOS is currently under development. It is 16-bit, real-time, networkable, bootable from a floppy, and has an incomplete USB driver. It dates back to 1992 as a personal project, and was released as GPL in 2005.[27]

Embedding

DOS' structure of accessing hardware directly makes it ideal for use in embedded devices. The final versions of DR-DOS are still aimed at this market.[28] ROM-DOS was used as the embedded system on the Canon PowerShot Pro 70.[29]

Emulation

Under Linux it is also possible to run copies of DOS and many of its clones under DOSEMU, a Linux-native virtual machine for running DOS programs at near native speed. There are a number of other emulators for running DOS under various versions of UNIX, even on non-x86 platforms, such as DOSBox.[30][31]

DOS emulators are gaining popularity among MS-Windows XP and MS-Windows Vista users, due to these systems being very incompatible with pure DOS. They can be used to run games or other DOS software. One of the most well-known is DOSBox, designed for legacy gaming (e.g. King's Quest, Doom) on modern operating systems.[22][30]

It is possible to run DOS applications under Microsoft Virtual PC, allowing better compatibility than DOS emulators. A legitimate version of MS-DOS can be installed which should allow all but the most stubborn applications to run.[32]

With Microsoft Windows

, the DOS-styled command prompt used in Microsoft-NT-based Windows.]] True 32-bit versions of Windows, starting with NT and including 2000, XP, and Vista, are not based upon DOS. These include the NT Virtual DOS Machine (NTVDM), which runs a modified version of MS-DOS 5 in a virtual machine. While DOS-based versions used the traditional COMMAND.COM for a command line interface, MS-Windows NT and its derivatives use cmd.exe, a descendant of OS/2's command interpreter which recognizes many DOS commands (although COMMAND.COM is still called and used when DOS .EXE files are run).

Versions

See Comparison of x86 DOS operating systems and Timeline of x86 DOS operating systems.

Software


DOS was the dominant PC-Compatible platform and many notable programs were written for it. These included:

Ease of use

User interface

[[File:|300px|thumb|right|Screenshot of a Windows command shell listing the files in a directory]] DOS systems utilize a command line interface. Programs are started by entering their filename at the command prompt. DOS systems include several programs as system utilities, and provides additional commands that don't correspond to programs (internal commands).[34]

In an attempt to provide a more user-friendly environment, numerous software manufacturers wrote file management programs that provided users with menu- and/or icon-based interfaces. Microsoft Windows is a notable example, eventually resulting in Microsoft Windows 9x becoming a self-contained program loader, and replacing DOS as the most-used PC-compatible program loader. Text user interface programs included Norton Commander, Dos Navigator, Volkov Commander, Quarterdesk DESQview, and SideKick. Graphical user interface programs included Digital Research's Graphical Environment Manager (originally written for CP/M) and GEOS.

Eventually, the manufacturers of major DOS systems began to include their own environment managers. MS-DOS/IBM DOS 4 included DOS Shell;[35] DR-DOS 5, released the next year, included ViewMAX, based upon GEM.[36]

Multitasking

By its original design, DOS was a single task operating system. MS and PC DOS would introduce task switching with DOSShell,[37] and DR-DOS would include it with DR-DOS 6, via the TaskMAX command.[13]:320–324 MS and PC DOS never had a multitasking capability;[38] DR-DOS had the capability with DR-DOS 7 (assuming DR-DOS was running with DPMI enabled).[39] Programs such as VMIX (shareware) or DesqView (commercial) could multitask even on an 8088, which did not have hardware support for multitasking due to its lack of protected mode.

Limitations

Several limitations plague the DOS architecture. The original 8088 microprocessor could only address 1 megabyte of physical RAM. With additional hardware devices being mapped into this range, the highest amount of available memory was 640 kilobytes, known as conventional memory. Due to DOS' structure, this was assumed to be the maximum, and DOS could not address more than this. An early workaround was expanded memory; later, extended memory was developed with the 80286. While these provided usable memory to applications, they still had to start in conventional memory, thereby using part of the existing 640 KB. With the 80386 microprocessor's redesigned protected mode, DOS extenders and the DOS Protected Mode Interface were able to provide additional memory to applications, as well as multitasking.[40][41]

DOS also has an upper limit to the size of hard disk partitions. This has two causes. First, many DOS-type systems never had support for any file system newer than FAT16, which, by design, does not allow partitions larger than 2.1 gigabytes.[42] Additionally, DOS accesses the hard disk by calling Interrupt 13, which utilizes the cylinder-head-sector system of mapping the disk. Under this system, only 8 gigabytes are visible to the operating system.[43] Newer operating systems accomplished disk access via software means, e.g. 32-bit disk access.

Using FAT16 (and FAT12 for floppy disks) required use of the 8.3 filename. Filenames in DOS can not be longer than eight characters, and the filename extension cannot be longer than three. Win95's patented VFAT hack worked around this in a unique way.

See also

References

  1. ^ Murdock, Everett (1988). DOS the Easy Way. EasyWay Downloadable Books. ISBN 0923178007. 
  2. ^ Hyde, Randall (1996-09-30). "CHAPTER EIGHTEEN: RESIDENT PROGRAMS (Part 3)". The Art of Assembly Language Programming. http://oopweb.com/Assembly/Documents/ArtOfAssembly/Volume/Chapter_18/CH18-3.html. Retrieved 2008-09-02. 
  3. ^ "Batch File Help". computerhope.com. http://www.computerhope.com/batch.htm. Retrieved 2008-09-10. 
  4. ^ Matczynski, Michael. "ZINGTECH - Guide to the New Game Programmer". http://www.zingtech.com/features/gamedev/gnewprog.htm. Retrieved 2008-09-02. 
  5. ^ a b "Drive Letter Assignment and Choosing Primary vs. Logical Partitions". The PC Guide. 2007-05-17. http://www.storagereview.com/guide/partLetter.html. Retrieved 2008-09-02. 
  6. ^ "Microsoft Windows MS DOS Device Name DoS Vulnerability". http://www.juniper.net/security/auto/vulnerabilities/vuln1043.html. Retrieved 2008-09-02. 
  7. ^ "DOS device names definition". PC Magazine. http://www.pcmag.com/encyclopedia_term/0,2542,t=DOS+device+names&i=41766,00.asp. Retrieved 2008-09-02. 
  8. ^ "Reverse-Engineering DOS 1.0 – Part 1: The Boot Sector « pagetable.com". http://www.pagetable.com/?p=165.  090912 pagetable.com
  9. ^ "The Master Boot Record (MBR) and What it Does". http://www.dewassoc.com/kbase/hard_drives/master_boot_record.htm.  090912 dewassoc.com
  10. ^ "CONFIG.SYS Commands". http://academic.evergreen.edu/projects/biophysics/technotes/program/config-sys.txt.  090913 academic.evergreen.edu
  11. ^ Kozierok, Charles (2001). "The DOS Boot Process". The PC Guide. http://www.pcguide.com/ref/hdd/file/structBoot-c.html. Retrieved 2008-09-02. 
  12. ^ "DR-DOS 7.02 User Guide chapter 9". Caldera Systems. 1998. http://www.drdos.net/documentation/usergeng/09ugch9.htm. Retrieved 2009-09-15. 
  13. ^ a b DR DOS 6.0 User Guide. Digital Research. 1991. pp. 320–324. 
  14. ^ "misc.txt". http://www.arl.wustl.edu/~lockwood/class/cse306-s04/resources/helppc/misc.txt.html.  090912 arl.wustl.edu
  15. ^ a b c Rolander, Tom. Interview. The rest of the story: How Bill Gates beat Gary Kildall in OS war, Part 1.
  16. ^ Bove, Tony (2005). Just Say No to Microsoft. No Starch Press. pp. 9–11. ISBN 159327064X. http://books.google.co.uk/books?id=I0RB1Xxp-KAC&pg=PA11&lpg=PA11&dq=ibm+cp/m+licensing&source=web&ots=dryptL9LAW&sig=KJqNIT1r_-yVcpe0fa0p9RI1BW4&hl=en&sa=X&oi=book_result&resnum=10&ct=result#PPA9,M1. 
  17. ^ a b Bellis, Mary. "The Unusual History of MS-DOS The Microsoft Operating System". http://inventors.about.com/library/weekly/aa033099.htm. Retrieved 2008-09-02. 
  18. ^ Pollack, Andrew (1991-07-27). "Microsoft Widens Its Split With I.B.M. Over Software". New York Times. http://query.nytimes.com/gst/fullpage.html?res=9D0CE0D81339F934A15754C0A967958260. Retrieved 2008-09-02. 
  19. ^ Brinkley, Joel (1999-05-28). "I.B.M. Executive Describes Price Pressure by Microsoft". New York Times. http://query.nytimes.com/gst/fullpage.html?res=990DEEDD1630F93BA15756C0A96F958260. Retrieved 2008-09-02. 
  20. ^ Jim Hall (2002-03-25). "The past, present, and future of the FreeDOS Project". http://www.linuxdevices.com/articles/AT3952799051.html. Retrieved 2008-06-14. 
  21. ^ Hall, Jim (September 23, 2006). "History of FreeDOS". freedos.org. http://www.freedos.org/freedos/about/. Retrieved 2007-05-28. 
  22. ^ a b James Bannan (2006-10-13). "HOW TO: Coax retro DOS games to play on Vista". http://apcmag.com/how_to_coax_retro_dos_games_to_play_on_vista.htm. Retrieved 2008-07-03. 
  23. ^ "Finding The DOS In Windows 95". Smart Computing. March 1996. http://www.smartcomputing.com/Editorial/article.asp?article=articles/archive/95win/95win21/95win21.asp&guid=. Retrieved 2008-07-12. 
  24. ^ http://www.conctrls.com/CCInews.html
  25. ^ Hall, Jim (2007-07-13). "Jim Hall". http://www.freedos.org/jhall/. Retrieved 2008-06-12. 
  26. ^ "Dell PCs Featuring FreeDOS". http://www.dell.com/content/topics/segtopic.aspx/e510_nseries?c=us&cs=19&l=en&s=dhs. Retrieved 2008-06-14. 
  27. ^ "GPL'd DOS workalike adds features". 2007-04-01. http://www.linuxdevices.com/news/NS9509696845.html. Retrieved 2008-06-01. 
  28. ^ "DR DOS Embedded DOS". http://www.drdos.com/products/drdos703.htm. Retrieved 2008-09-26. 
  29. ^ "Datalight DOS Selected for Canon's New Line of Digital Still Cameras". Business Wire. 1999-08-24. http://findarticles.com/p/articles/mi_m0EIN/is_1999_Feb_23/ai_53930374. Retrieved 2008-09-26. 
  30. ^ a b "DOSBox Information". http://www.dosbox.com/information.php. Retrieved 2008-05-18. 
  31. ^ "DOSEMU Home". 2007-05-05. http://www.dosemu.org/. Retrieved 2008-07-03. 
  32. ^ "DOS Games on Vista". 2008-03-11. http://www.winvistatips.com/dos-games-on-vista-a102.php. Retrieved 2008-09-02. 
  33. ^ Darrow, Barbara (1 February 2002). "Whatever Happened To Lotus 1-2-3?". http://www.crn.com/it-channel/18818026. Retrieved 2008-07-12. 
  34. ^ Murdock, Everett. DOS the Easy Way. EasyWay Downloadable Books. pp. 7–12. ISBN 0923178023. 
  35. ^ Murdock, Everett. DOS the Easy Way. EasyWay Downloadable Books. pp. 71. ISBN 0923178023. http://books.google.com/books?id=vrsSflB2o5sC. 
  36. ^ Dvorak, John; Nick Anis (1991). Dvorak's Guide to DOS and PC Performance. Osborne McGraw-Hill. pp. 442–444. 
  37. ^ Murdock, Everett. DOS the Easy Way. EasyWay Downloadable Books. pp. 83. ISBN 0923178023. 
  38. ^ Perry, Greg; Jill Freeze (2003). Sams Teach Yourself Windows XP Computer Basics All in One. Sams Publishing. pp. 445. ISBN 0672325357. http://books.google.co.uk/books?id=FptQSQs0skEC&pg=PA445&dq=ms-dos+multitasking&sig=ACfU3U1yCLlNTSiGByW9TJOZJqmPENSdkQ. 
  39. ^ "Chapter 13 Multitasking and Task Switching". Caldera DR-DOS 7.02 User Guide. Caldera Systems. 1998. http://www.drdos.net/documentation/usergeng/13ugch13.htm. Retrieved 2008-09-12. 
  40. ^ Korzeniowski, Paul (May 1990). "DOS: still thriving after all these years". Software Magazine (Findarticles.com). http://findarticles.com/p/articles/mi_m0SMG/is_n6_v10/ai_8528224. Retrieved 2008-07-10. 
  41. ^ Duncan, Ray (1991). Extending DOS: A Programmer's Guide to Protected-Mode DOS (2 ed.). Addison-Wesley. ISBN 0201567989. 
  42. ^ Mueller, Scott (2003). Upgrading and Repairing PCs. Que Publishing. p. 812. ISBN 0789729741. 
  43. ^ "The Int 13 Interface". The PC Guide. storagereview.com. http://www.storagereview.com/guide2000/ref/hdd/bios/sizeGB8.html. Retrieved 2008-07-10. 
Notes
  • IBM Corp., IBM, (January 1984). “IBM DOS Release 2.10 Cloth bound retail hard board box”. 1st edition. IBM Corp. Item Number. 6183946
  • IBM Corp., IBM, (January 1984). “Disk Operating System User's guide (DOS Release 2.10)”. 1st edition. Microsoft Corp. (100 pages including colour illustrations) Item Number. 6183947
  • IBM Corp., IBM, (January 1984). “Disk Operating System Manual (DOS Release 2.10)”. 1st edition. Microsoft Corp. (574 looseleaf pages in 3 ring folder) Item No. 6183940
  • IBM Corp., IBM, (May 1984). “BASIC HANDBOOK General Programming Information (BASIC Release 3.0)”. 3rd edition. IBM Corp. (127 pages) Item Number 6361129
  • IBM Corp., IBM, (May 1984). “BASIC Reference (BASIC Release 3.0)”. 3rd edition. IBM Corp. Item Number 6361134

External links


Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

See also DoS

Contents

English

Acronym

DOS

  1. (computing) Disk Operating System, sometimes MS-DOS for Microsoft-DOS, DR-DOS, etc.

Translations

  • Icelandic: diskstýrikerfi is(is) n.

Initialism

DOS

  1. (military) Date[s] of Service
  2. (military) Date of Separation
  3. (US) Department of State
  4. (sciences) Density of states

See also

Anagrams


Strategy wiki

Up to date as of January 23, 2010
(Redirected to Category:MS-DOS article)

From StrategyWiki, the free strategy guide and walkthrough wiki

MS-DOS
The console image for MS-DOS.
Manufacturer Microsoft
Active 19812000
Total Games 2 (226 present)
← (none) Windows →
For help running MS-DOS games on modern operating systems, see the DOSBox guide.

MS-DOS is an operating system marketed by Microsoft. As a result of being distributed on IBM systems (under the name PC-DOS) it soon became immensely successful, and the platform of choice for computer games. Even after the release of Windows 95 many games were still produced primarily for MS-DOS, albeit including some additional features when run under Windows. Once DirectX gained widespread support, MS-DOS was quickly abandoned by developers.

On more modern versions of Windows many MS-DOS games will not run correctly, and, just as often, many will not run at all. One popular solution for running these games correctly is the open-source emulator DOSBox.


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Pages in category "MS-DOS"

The following 200 pages are in this category, out of 226 total.

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  • 007: Licence to Kill

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B

C

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G cont.

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  • Karateka
  • King's Quest II: Romancing the Throne
  • King's Quest IV: The Perils of Rosella
  • King's Quest V: Absence Makes the Heart Go Yonder!
  • King's Quest VI: Heir Today, Gone Tomorrow
  • King's Quest: Quest for the Crown

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M

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N cont.

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  • Qix
  • Quake
  • Quest for Glory I: So You Want To Be A Hero
  • Quest for Glory II: Trial by Fire
  • Quest for Glory III: Wages of War
  • Quest for Glory IV: Shadows of Darkness

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Gaming

Up to date as of February 01, 2010

From Wikia Gaming, your source for walkthroughs, games, guides, and more!

Contents

System information

DOS, short for Disk Operating System, was at one time the primary operating systems of IBM PCs.

List of major DOS types
Type Maker Supported?
MS-DOS Microsoft No
PC-DOS IBM No
DR-DOS DRDOS, Inc. Yes
FreeDOS FreeDOS Project Yes

MS-DOS information

MS-DOS logo

The Microsoft Disk Operating System. In simplest terms as per games, the text-based Operating System immediately preceding Windows.

In 1980, Microsoft head Bill Gates (then known for his creation of the BASIC computer language) was approached by IBM about an operating system for their boxes. Paul Allen contacted Tim Patterson of Seattle Computer Products, and acquired the rights to sell his QDOS (Quick and Dirty Operating System) to an unnamed client - IBM - for under $100,000. Deals continued as the product was still under development at Seattle Computer, and in 1981 Microsoft bought the full rights to the operating system.

Legions of games were developed for MS-DOS, and thus the platform is still fairly important, if somewhat ancient. Many of these games now run on FreeDos.

List of games

See also


This article uses material from the "DOS" article on the Gaming wiki at Wikia and is licensed under the Creative Commons Attribution-Share Alike License.

Simple English

A disk operating system (DOS) will load from a floppy disk each time a computer starts, and will access that disk for software to complete operations. MS-DOS is probably the most well-known DOS, and was purchased by Microsoft Corporation from a system known as QDOS. As operating systems became more complicated and took up more space, they began to be permanently installed on hard drives, which are faster and more reliable than floppy disks, and can store more data. This was encouraged by a steady drop in hard drive prices.

DOSes are usually text-based and without graphics to save space on a floppy disk. Although DOSes have mostly been replaced by Windows, Macintosh, and Linux systems, among others (sporting a GUI, or Graphical User Interface), they are still in use in some places, mostly on older computers. This may be because of a lack of money, the need to use software which still runs on a DOS system, nostalgia for an older operating system, or the belief that text-based systems are more efficient.

Although GUIs are more popular, in times of emergency or when one needs to install special software, a boot disk allows a user to start his computer into a DOS.









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