MS-DOS

Microsoft's original disk operating system, MS-DOS, was the first popular operating system for the IBM PC. It employed a command line interface via its command interpreter, command.com.

The progenitor of MS-DOS was created by a company called Seattle Computer Systems. The original name was QDOS, for Quick and Dirty Operating System. It was designed as a short-term clone of the market-leading CP/M operating system, to provide compatibility with the existing installed base of business applications such as WordStar and dBase[?]. Microsoft bought the product for re-sale to IBM and it was renamed PC-DOS (the IBM-badged version) and MS-DOS (the version badged by Microsoft themselves). The two products were all but identical to begin with but would eventually diverge. (See PC-DOS.)

For Microsoft's development from its origin as a specialist programming language supplier in the 1970s to its eventual status as the dominant firm in the computer industry, DOS was the key product. It was revenue from MS-DOS sales (particularly from exclusive OEM per-unit contracts - which were not finally ruled illegal in the USA until considerably later), that made the explosive growth of the company possible, and MS-DOS continued to be the largest single contributor to Microsoft's earnings well after the company had become more famous for Windows. (As a matter of detail, it was not until well after the release of Windows 95 that aggregate Windows revenue surpassed aggregate DOS revenue.)

MS-DOS grew to include more features from other operating systems. MS-DOS 2.0 introduced features from Unix such as subdirectories, command input/output redirection, and pipes.

MS-DOS was not designed to be a multi-user or multitasking operating system, but many attempts were made to retrofit these capabilities. Many programs were developed using the Terminate and Stay Resident (TSR) technique and other mostly-undocumented functions to provide pop-up applications. Add-on environments like DesqView[?] attempted to provide multitasking, and achieved a fair degree of success when later combined with the memory-management hardware of the Intel 80386 processor.

After the release of the Apple Macintosh in 1984, people became interested in a graphical user interface. Many programs created their own graphical interface, such as Microsoft Word for DOS, XTree, and the Norton Shell. However, that required duplication of effort and did not provide much consistency, so complete GUI environments were created.

IBM and Microsoft began work on a joint project called OS/2, originally a protected-mode version of MS-DOS with a GUI, but Microsoft soon abandoned the project to devote full resources to Windows. Digital Research created the GEM environment that reached minimal popularity, but both were soon eclipsed by Microsoft's Windows GUI package, reportedly due to Microsoft's exclusive agreements with computer hardware vendors. Prior to Windows '95, Windows was not a full operating system, but rather a shell that still required DOS to run. Main Commands

 DIR      List directory content
 TYPE     List file content
 COPY     Copy a file
 REN      Rename a file
 DEL      Delete a file
 MD       Create a directory Make Directory
 CD       Change current directory Change Directory
 RD       Delete a directory Delete Directory

Sample Output

 D:\luxor>dir
 Volume in drive D is Data
 Volume Serial Number is C0A2-A003

 Directory of D:\luxor

 12/31/2002  02:53 PM    <DIR>          .
 12/31/2002  02:53 PM    <DIR>          ..
 12/31/2002  01:15 AM               549 2c.L
 12/30/2002  11:33 PM               360 lang.L
 12/31/2002  02:10 AM            22,538 luxor.rb
 11/30/2002  05:39 PM                63 makefile
 11/30/2002  08:21 PM            67,800 memwatch.log
 12/31/2002  02:53 PM                94 test.L
 12/29/2002  01:01 AM                60 test.pl
                7 File(s)         91,464 bytes
                2 Dir(s)  20,028,874,752 bytes free

Several similar products were produced by other companies. Certainly in the case of PC-DOS and DR-DOS, it is common but incorrect to call these "clones". PC-DOS and MS-DOS were (to continue the genetic analogy) "identical twins" that diverged only in adulthood and eventually became quite different products; DR-DOS was a clone of itself once removed: see DR-DOS for details.

• PC-DOS
• DR-DOS
• FreeDOS
• OpenDOS[?]

See also: Microsoft Windows, History of Microsoft Windows