MS-DOS: Meaning (information, definition, explanation, facts)

Microsoft's original disk operating system, MS-DOS, was the first popular operating system for the IBM PC. It employs a command line interface and a batch scripting facility 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 identical to begin with but would eventually diverge. (See PC-DOS.)

In Microsoft's development from 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. Incidentally, 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 including Borland's popular Sidekick product. Add-on environments like DESQView attempted to provide multitasking, and achieved some 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 NT. Digital Research created the GEM environment which 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.

Early versions of Microsoft Windows were a program which ran under MS-DOS and its clones. Later versions were launched under DOS but "extended" it by going into protected mode. Still later versions of MS Windows ran independently of DOS but included much of the old code such that it could run in virtual machines under the new OS and the latest versions of MS Windows are continually dropping ever more of the old DOS.

Under Linux it is possible to run copies of DOS and many of its clones under dosemu, a Linux-native virtual machine for running real mode programs. There are a number of other emulators for running DOS under various versions of UNIX, even on non-x86 platforms.

Main commands

DIR List directory content TYPE Type file content to screen COPY Copy a file REN Rename a file DEL Delete a file MD Make a new directory CD Change current directory RD Remove a directory

C:\>dir
 Volume in drive C has no label
 Volume Serial Number is 1234-5678
 Directory of C:\

AUTOEXEC TTZ         1,120  07-26-03  1:03a
MSDOSS~1 BAK         1,779  01-21-96  7:12p
SETUP          <DIR>        01-21-96  9:06p
HIDDEN   TX1        19,296  01-21-96  7:27p
CONFIG   BAK           122  01-21-96  2:25p
GAMES          <DIR>        01-21-96  9:06p
WS_FTP   LOG           128  01-21-96 12:36p
CONFIG   DOS            50  01-21-96  2:25p
AUTOEX~2 BAK         1,150  01-22-03  2:13p
CYGNUS         <DIR>        01-21-96  9:38a
JAVA           <DIR>        01-21-96  9:40a
TMP            <DIR>        01-21-96  4:01p
E              <DIR>        01-21-96  4:23p
COMMAND  COM        93,890  01-21-96 10:22p
WINDOWS        <DIR>        01-21-96  8:42p
MOUSE          <DIR>        01-21-96  8:45p
BASIC          <DIR>        01-21-96  5:09p
MASM           <DIR>        01-21-96  5:09p
CONFIG   SYS           122  01-31-03 11:50p
PROGRA~1       <DIR>        01-21-96  6:26p
MYDOCU~1       <DIR>        01-21-96  9:00p
AUTOEXEC BAT         1,150  07-26-03  1:03a
        10 file(s)     12,056,573 bytes
        12 dir(s)        1,214.84 MB free

Several similar products were produced by other companies. 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
• PTS-DOS