DOS
DOS ( (1998). MS-DOS dominated the IBM PC compatible market between 1981 and 1995.
Although the name has come to be identified specifically with this particular family of operating systems, DOS is a platform-independent acronym for disk operating system,[2] whose use predates the IBM PC. Dozens of other operating systems also use the acronym, beginning with the mainframe DOS/360 from 1966. Others include Apple DOS, Apple ProDOS, Atari DOS, Commodore DOS, TRSDOS, and AmigaDOS.
History
Origins
When IBM introduced the
IBM again approached Bill Gates. Gates in turn approached
Microsoft originally sold MS-DOS only to original equipment manufacturers (OEMs). One major reason for this was that not all early PCs were 100% IBM PC compatible. DOS was structured such that there was a separation between the system specific device driver code (IO.SYS) and the DOS kernel (MSDOS.SYS). Microsoft provided an OEM Adaptation Kit (OAK) which allowed OEMs to customize the device driver code to their particular system. By the early 1990s, most PCs adhered to IBM PC standards so Microsoft began selling a retail version of MS-DOS, starting with MS-DOS 5.0.
In the mid-1980s, Microsoft developed a
Digital Research attempted to regain the market lost from CP/M-86, initially with
IBM, however, did not want to replace DOS.[13] After AT&T began selling Unix, Microsoft and IBM began developing OS/2 as an alternative.[10] The two companies later had a series of disagreements over two successor operating systems to DOS, OS/2 and Windows.[14] They split development of their DOS systems as a result.[15] The last retail version of MS-DOS was MS-DOS 6.22; after this, MS-DOS became part of Windows 95, 98 and Me. The last retail version of PC DOS was PC DOS 2000 (also called PC DOS 7 revision 1), though IBM did later develop PC DOS 7.10 for OEMs and internal use.
The
Decline
Early versions of
Continued use
As of 2023[update], available compatible systems are
Embedded systems
DOS's structure of accessing hardware directly allows it to be used in
Emulation
On Linux, it is possible to run DOSEMU, a Linux-native virtual machine for running DOS programs at near native speed. There are a number of other emulators for running DOS on various versions of Unix and Microsoft Windows such as DOSBox.[27][28] DOSBox is designed for legacy gaming (e.g. King's Quest, Doom) on modern operating systems.[18][27]
Design
MS-DOS and IBM PC DOS related operating systems are commonly associated with machines using the
DOS is a single-user, single-tasking operating system with basic
DOS provides the ability for
The operating system offers an application programming interface that allows development of character-based applications, but not for accessing most of the
Boot sequence
- The bootstrap loader on PC-compatible computers, the master boot record, is located beginning at the boot sector, the first sector on the first track (track zero), of the boot disk. The ROM BIOSwill load this sector into memory at address 0000h:7C00h, and typically check for a signature "55h AAh" at offset +1FEh. If the sector is not considered to be valid, the ROM BIOS will try the next physical disk in the row, otherwise it will jump to the load address with certain registers set up.
- If the loaded boot sector happens to be a Volume Boot Record(VBR) of that volume, into memory at 0000h:7C00h in the similar fashion as if it had been loaded by the ROM BIOS itself. The MBR will then pass execution to the loaded portion with certain registers set up.
- The sector content loaded at 0000h:7C00h constitutes a VBR now. VBRs are operating system specific and cannot be exchanged between different DOS versions in general, as the exact behaviour differs between different DOS versions. In very old versions of DOS such as DOS 1.x, the VBR would load the whole IO.SYS/IBMBIO.COM file into memory at 0000h:0600h.[32] For this to work, these sectors had to be stored in consecutive order on disk by SYS. In later issues, it would locate and store the contents of the first two entries in the root directory at 0000h:0500h and if they happen to reflect the correct boot files as recorded in the VBR, the VBR would load the first 3 consecutive sectors of the IO.SYS/IBMBIO.COM file into memory at 0070h:0000h. The VBR also has to take care to preserve the contents of the Disk Parameter Table (DPT). Finally, it passes control to the loaded portion by jumping to its entry point with certain registers set up (with considerable differences between different DOS versions).
- In later[clarification needed] DOS versions, where the VBR has loaded only the first 3 sectors of the IO.SYS/IBMBIO.COM file into memory, the loaded portion contains another boot loader, which will then load the remainder of itself into memory, using the root directory information stored at 0000h:0500h. For most versions, the file contents still need to be stored in consecutive order on disk. In older versions of DOS, which were still loaded as a whole, this step is skipped.
- The DOS system initialization code will initialize its built-in device drivers and then load the DOS kernel, located in MSDOS.SYS on MS-DOS systems, into memory as well. In Windows 9x, the DOS system initialization code and built-in device drivers and the DOS kernel are combined into a single IO.SYS file while MSDOS.SYS is used as a text configuration file.
- The CONFIG.SYS file is then read 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.[33][34]
The DOS system files loaded by the boot sector must be
In PC DOS and DR DOS 5.0 and above, the DOS system files are named IBMBIO.COM instead of IO.SYS and IBMDOS.COM instead of MSDOS.SYS. Older versions of DR DOS used DRBIOS.SYS and DRBDOS.SYS instead.
Starting with
0
, the boot process will stop with the command processor (typically COMMAND.COM) loaded, instead of executing WIN.COM automatically.
File system
DOS uses a filesystem which supports 8.3 filenames: 8 characters for the filename and 3 characters for the extension. Starting with DOS 2 hierarchical directories are supported. Each directory name is also 8.3 format but the maximum directory path length is 64 characters due to the internal current directory structure (CDS) tables that DOS maintains. Including the drive name, the maximum length of a fully qualified filename that DOS supports is 80 characters using the format drive:\path\filename.ext followed by a null byte.
DOS uses the
Starting with DOS 3.1, file redirector support was added to DOS. This was initially used to support networking but was later used to support CD-ROM drives with MSCDEX. IBM PC DOS 4.0 also had preliminary installable file system (IFS) support but this was unused and removed in DOS 5.0. DOS also supported Block Devices ("Disk Drive" devices) loaded from CONFIG.SYS that could be used under the DOS file system to support network devices.
Drive naming scheme
In DOS, drives are referred to by identifying letters. Standard practice is to reserve "A" and "B" for
Because DOS applications use these drive letters directly (unlike the /dev directory in
Reserved device names
There are reserved device names in DOS that cannot be used as filenames regardless of extension as they are occupied by built-in character devices. These restrictions also affect several Windows versions, in some cases causing crashes and security vulnerabilities.[37]
The reserved names are:
COM1
,COM2
,COM3
,COM4
,COM5
,COM6
,COM7
,COM8
,COM9
(serial communication ports)CON
, for consoleLPT1
,LPT2
,LPT3
,LPT4
,LPT5
,LPT6
,LPT7
,LPT8
,LPT9
(line printers)AUX
, for auxiliaryPRN
, for printer[38]NUL
, for null devices; added in 86-DOS 1.10 and PC DOS 1.0.
In Windows 95 and Windows 98, typing in the location of the reserved name (such as CON/CON, AUX/AUX, or PRN/PRN) crashes the operating system, of which Microsoft has provided a security fix for the issue. In Windows XP, the name of the file or folder using a reserved name silently reverts to its previous name, with no notification or error message. In Windows Vista and later, attempting to use a reserved name for a file or folder brings up an error message saying "The specified device name is invalid."
These names (except for NUL) have continued to be supported in all versions of MS-DOS, PC DOS and DR-DOS ever since. manager in MS-DOS 7.0–8.0.
AUX
typically defaults to COM1
, and PRN
to LPT1
(LST
),[39] but these defaults can be changed in some versions of DOS to point to other serial or parallel devices.[40][41][43] The PLT
device (present only in some HP OEM versions of MS-DOS) was reconfigurable as well.[40][41]
Filenames ended with a colon (:) such as NUL:
conventionally indicate device names, but the colon is not actually a part of the name of the built-in device drivers. Colons are not necessary to be typed in some cases, for example:
ECHO This achieves nothing > NUL
It is still possible to create files or directories using these reserved device names, such as through direct editing of directory data structures in disk sectors. Such naming, such as starting a file name with a space, has sometimes been used by viruses or hacking programs to obscure files from users who do not know how to access these locations.
Memory management
DOS was designed for the Intel 8088 processor, which can only directly access a maximum of 1 MiB of RAM.
Specifications were developed to allow access to additional memory. The first was the
Starting with DOS 5,[50] DOS could directly take advantage of the HMA by loading its kernel code and disk buffers there via the DOS=HIGH
statement in CONFIG.SYS. DOS 5+ also allowed the use of available upper memory blocks via the DOS=UMB
statement in CONFIG.SYS.[51]
DOS under OS/2 and Windows
The DOS emulation in OS/2 and Windows runs in much the same way as native applications do. They can access all of the drives and services, and can even use the host's clipboard services. Because the drivers for file systems and such forth reside in the host system, the DOS emulation needs only provide a DOS API translation layer which converts DOS calls to OS/2 or Windows system calls. The translation layer generally also converts BIOS calls and virtualizes common I/O port accesses which many DOS programs commonly use.
In Windows 3.1 and 9x, the DOS virtual machine is provided by WINOLDAP. WinOldAp creates a virtual machine based on the program's PIF file, and the system state when Windows was loaded. The DOS graphics mode, both character and graphic, can be captured and run in the window. DOS applications can use the Windows clipboard by accessing extra published calls in WinOldAp, and one can paste text through the WinOldAp graphics.
The emulated DOS in OS/2 and Windows NT is based upon DOS 5. Although there is a default configuration (config.sys and autoexec.bat), one can use alternate files on a session-by-session basis. It is possible to load drivers in these files to access the host system, although these are typically third-party.
Under OS/2 2.x and later, the DOS emulation is provided by DOSKRNL. This is a file that represents the combined IBMBIO.COM and IBMDOS.COM, the system calls are passed through to the OS/2 windowing services. DOS programs run in their own environment, the bulk of the DOS utilities are provided by bound DOS / OS2 applications in the \OS2 directory. OS/2 can run Windows 3.1 applications by using a modified copy of Windows (Win-OS/2). The modifications allow Windows 3.1 programs to run seamlessly on the OS/2 desktop, or one can start a WinOS/2 desktop, similar to starting Windows from DOS.
OS/2 allows for 'DOS from Drive A:', (VMDISK). This is a real DOS, like MS-DOS 6.22 or PC DOS 5.00. One makes a bootable floppy disk of the DOS, adds a number of drivers from OS/2, and then creates a special image. The DOS booted this way has full access to the system, but provides its own drivers for hardware. One can use such a disk to access cdrom drives for which there is no OS/2 driver.
In all 32-bit (IA-32) editions of the Windows NT family since 1993, DOS emulation is provided by way of a virtual DOS machine (NTVDM). 64-bit (IA-64 and x86-64) versions of Windows do not support NTVDM and cannot run 16-bit DOS applications directly; third-party emulators such as DOSbox can be used to run DOS programs on those machines.
User interface
DOS systems use a command-line interface. A program is started by entering its filename at the command prompt. DOS systems include utility programs and provide internal commands that do not correspond to programs.[52]
In an attempt to provide a more user-friendly environment, numerous software manufacturers wrote
Eventually, the manufacturers of major DOS systems began to include their own environment managers. MS-DOS/IBM DOS 4 included DOS Shell;[53] DR DOS 5.0, released the following year, included ViewMAX, based upon GEM.[54]
Terminate and stay resident
Although DOS is not a multitasking operating system, it does provide a terminate-and-stay-resident (TSR) function which allows programs to remain resident in memory. These programs can hook the system timer or keyboard interrupts to allow themselves to run tasks in the background or to be invoked at any time, preempting the current running program and effectively implementing a simple form of multitasking on a program-specific basis. The DOS PRINT command does this to implement background print spooling. Borland Sidekick, a popup personal information manager (PIM), also uses this technique.
Terminate-and-stay-resident programs are also used to provide additional features not available by default. Programs like CED and DOSKEY provide command-line editing facilities beyond what is available in COMMAND.COM. Programs like the Microsoft CD-ROM Extensions (MSCDEX) provide access to files on CD-ROM disks.
Some TSRs can even perform a rudimentary form of task switching. For example, the
Software
- Arachne, a 16-bit graphical web browser
- dBase, database program
- Harvard Graphics, a presentation graphics design program
- Lotus 1-2-3, a spreadsheet which has been credited with the success of the IBM PC[56]
- Norton Commander and XTree, file management utilities
- PKZIP, the utility that quickly became the standard in file compression
- communication programs
- Sidekick, personal information manager that could be used from within other programs
- WordPerfect, a word processor that was dominant in the 1980s
- WordStar, word processor originally for CP/M that became popular on the IBM PC
Development tools
- BASICA and GW-BASIC
- DJGPP, the 32-bit DPMI DOS port of gcc
- Microsoft C, and CodeViewfrom Microsoft
- Watcom C/C++ from Watcom
- Turbo Prolog, and Turbo Assembler from Borland
See also
- COMMAND.COM (the command line interpreter for DOS and Windows 9x)
- CP/M (Digital Research early operating system similar to DOS)
- Disk Control ProgramVEB Robotron) (DCP, an MS-DOS derivative by the former East-German
- DOS API
- DOS/V
- Index of DOS games
- List of DOS operating systems
- PC-MOS/386 (a DOS-compatible multiuser operating system)
- VGA-compatible text mode, the base of DOS's TUI on IBM PC compatibles
References
- ISBN 0-923178-00-7.
- ^ Dictionary.com Archived 2017-11-12 at the Wayback Machine
- ^ "Mary Gates, 64; Helped Her Son Start Microsoft". New York Times. 1994-06-11. Retrieved 2023-04-11.
- ^ a b Rolander, Tom. "The rest of the story: How Bill Gates beat Gary Kildall in OS war, Part 1". The Scoble Show (Interview). Interviewed by Scoble, Robert. Archived from the original on 2007-11-04.
- ISBN 1-59327-064-X.
- ^ a b Bellis, Mary. "The Unusual History of MS-DOS The Microsoft Operating System". Archived from the original on 2012-04-27. Retrieved 2008-09-02.
- Freiberger, Paul (1982-08-23). "Bill Gates, Microsoft and the IBM Personal Computer". InfoWorld: 22. Archivedfrom the original on 2015-03-18. Retrieved 2015-01-29.
- ^ "Did you know that OS/2 wasn't Microsoft's first non Unix multi-tasking operating system?". Archived from the original on 2012-11-04.
- ^ "Larry Osterman's Biography". Archived from the original on 2013-06-02.
- ^ Usenet: [email protected]. Retrieved 2013-11-06.
- BYTE: 6. Retrieved 2013-10-19.
- BYTE: 132. Retrieved 2015-01-30.
- ^ Howitt, Doran (1984-12-10). "Unix and the Single User". InfoWorld: 28. Archived from the original on 2018-01-29. Retrieved 2015-02-07.
- ^ Pollack, Andrew (1991-07-27). "Microsoft Widens Its Split With I.B.M. Over Software". The New York Times. Archived from the original on 2010-11-02. Retrieved 2008-09-02.
- ^ Brinkley, Joel (1999-05-28). "I.B.M. Executive Describes Price Pressure by Microsoft". New York Times. Archived from the original on 2008-12-11. Retrieved 2008-09-02.
- Hall, Jim (2002-03-25). "The past, present, and future of the FreeDOS Project". Archived from the originalon 2012-05-29. Retrieved 2008-06-14.
- Hall, Jim (2006-09-23). "History of FreeDOS". freedos.org. Archived from the originalon 2007-05-27. Retrieved 2007-05-28.
- ^ a b Bannan, James (2006-10-13). "HOW TO: Coax retro DOS games to play on Vista". Archived from the original on 2008-08-01. Retrieved 2008-07-03.
- ^ "Finding The DOS In Windows 95". Smart Computing. March 1996. Archived from the original on 2004-07-07. Retrieved 2008-07-12.
- Chen, Raymond (2007-12-24). "What was the role of MS-DOS in Windows 95?". The Old New Thing - Site Home - MSDN Blogs. Archivedfrom the original on 2014-02-05. Retrieved 2014-02-05.
- ^ "Description of Restarting Computer in MS-DOS Mode". support.microsoft.com. 2007-01-19. Archived from the original on 2014-02-05. Retrieved 2014-02-05.
- ^ "Home". rxdos.sourceforge.net.
- Hall, Jim (2007-07-13). "Jim Hall's blog - 2007". Archived from the originalon 2012-10-25. Retrieved 2008-06-12.
- ^ "Dell PCs Featuring FreeDOS". Archived from the original on 2008-03-19. Retrieved 2008-06-14.
- ^ "DR-DOS Embedded DOS". Archived from the original on 2008-12-21. Retrieved 2008-09-26.
- ^ "Datalight DOS Selected for Canon's New Line of Digital Still Cameras". Business Wire. 1999-08-24. Archived from the original on 2012-07-09. Retrieved 2008-09-26.
- ^ a b "DOSBox Information". Archived from the original on 2008-05-25. Retrieved 2008-05-18.
- ^ "DOSEMU Home". 2007-05-05. Archived from the original on 2008-07-23. Retrieved 2008-07-03.
- ^ "Batch File Help". computerhope.com. Archived from the original on 2008-09-07. Retrieved 2008-09-10.
- ^ Matczynski, Michael. "ZINGTECH - Guide to the New Game Programmer". Archived from the original on 2008-12-19. Retrieved 2008-09-02.
- ^ "The Master Boot Record (MBR) and What it Does". Archived from the original on 2013-05-27. 090912 dewassoc.com
- ^ "Reverse-Engineering DOS 1.0 – Part 1: The Boot Sector « pagetable.com". Archived from the original on 2009-05-11. 090912 pagetable.com
- ^ "CONFIG.SYS Commands". Archived from the original on 2009-05-02. 090913 academic.evergreen.edu
- ^ Kozierok, Charles (2001). "The DOS Boot Process". The PC Guide. Archived from the original on 2008-07-19. Retrieved 2008-09-02.
- ^ "misc.txt". Archived from the original on 2010-06-29. 090912 arl.wustl.edu
- ^ a b "Drive Letter Assignment and Choosing Primary vs. Logical Partitions". The PC Guide. 2001-04-17. Archived from the original on 2012-04-17. Retrieved 2012-04-04.
- ^ "Microsoft Windows MS-DOS Device Name DoS Vulnerability". Archived from the original on 2011-07-25. Retrieved 2008-09-02.
- PC Magazine. Archivedfrom the original on 2008-09-29. Retrieved 2008-09-02.
- ^ a b c "MS-DOS Device Driver Names Cannot be Used As File Names". Revision 2.0. Microsoft. 2003-05-12. KB74496, Q74496. Archived from the original on 2012-07-21.
- ^ Hewlett-Packard Company, Portable Computer Division. August 1985. 45559-90001. Retrieved 2016-11-27.
- ^ Hewlett-Packard Company. December 1986 [August 1985]. 45559-90006. Archived(PDF) from the original on 2016-11-28. Retrieved 2016-11-27.
- TeleVideo PC DOS 2.11.)
- ^ Paul, Matthias R. (1997-10-02). "Caldera OpenDOS 7.01/7.02 Update Alpha 3 IBMBIO.COM README.TXT". Archived from the original on 2003-10-04. Retrieved 2009-03-29. [1]
- ^ Bailes & Mueller 1992, p. 5.
- ^ Bailes & Mueller 1992, pp. 42–44.
- ^ Bailes & Mueller 1992, pp. 67–68.
- ^ Mueller 1998, pp. 169.
- ^ Mueller 1998, pp. 243–244.
- ^ Bailes & Mueller 1992, p. 79–80.
- ^ Mueller 1998, p. 243.
- ^ Bailes & Mueller 1992, pp. 150–151.
- ISBN 978-0-923178-02-4.
- ISBN 978-0-923178-02-4. Archivedfrom the original on 2015-03-18.
- Osborne McGraw-Hill. pp. 442–444.
- ^ Version 1.47 is archived at "Back and Forth 1.47". Archived from the original on 2013-11-05. Retrieved 2013-08-05. and says "(C) 1990 by Progressive Solutions, Inc."
- ^ Darrow, Barbara (2002-02-01). "Whatever Happened To Lotus 1-2-3?". Archived from the original on 2009-01-09. Retrieved 2008-07-12.
Further reading
- 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
- Mueller, Scott (1998). Upgrading and Repairing PCs (Eighth ed.). ISBN 0-7897-1295-4. Retrieved 2021-11-02.
- Bailes, Lenny; Mueller, John (1992). Memory Management and Multitasking Beyond 640K. ISBN 0-8306-3476-2. Retrieved 2021-11-02.
External links
- Origins of DOS, articles and manuals by Tim Paterson.
- Timeline of DOS and Windows versions at the Wayback Machine (archived 2007-10-28)
- "DOS - where hardware is the only limit". Archived from the original on 2010-08-15. Retrieved 2010-08-29.
- Batfiles: The DOS batch file programming handbook
- "The Rise of DOS: How Microsoft Got the IBM PC OS Contract". pcmag.com. Retrieved 2022-12-24.
- "Application Software - DOS Short File Name Family". www.jumpjet.info. Archived from the original on 2020-02-17. Retrieved 2020-02-07. "(...) An archive of carefully hand selected FREE [and abandoned] software for DOS."
- Online Windows XP Simulator