[[Category:Operating Systems]] '''DOS''' ('''D'''isk '''O'''perating '''S'''ystem) is a generic name for a variety of 16-bit text-mode [[:Category:Operating Systems|operating systems]]. (Note that "DOS" is pronounced ''dahss'' or ''doss'' but not ''dose''.) The archetypal example is '''[[wp:MS-DOS|MS-DOS]]''', [[Microsoft|Microsoft's]] long-running OS that was also sold by IBM as [[wp:PC-DOS|PC-DOS]]. MS-DOS (and PC-DOS) originated as [[wp:86-DOS|86-DOS]] (eventually renamed QDOS) from Seattle Computer Products, which was intended to be a [[wp:CP/M|CP/M]] clone. Other (modern) examples include [[wp:DR-DOS|DR-DOS]] and [[wp:FreeDOS|FreeDOS]].

DOS by itself had no graphical interface; instead, if one was desired, users had to buy one seperately. Several GUIs were available for DOS, but [[Windows]] displaced them all with [[wp:Windows 3.0|version 3]]. DOS was still present in Windows 95, 98, and Me, but is totally absent from all NT-based versions (including NT, 2000, XP, Vista, and Windows 7), instead being emulated (via [[wp:Virtual DOS machine|NTVDM]] and [[wp:cmd.exe|cmd.exe]]).

Early versions of MS-DOS and PC-DOS included a [[BASIC]] interpreter (basic.exe), followed by [[BASICA]], [[GW-BASIC]], and finally [[QuickBASIC#QBasic|QBasic]]. (QBasic wasn't installed by default under Windows 9x; it had to be copied from the install media.) There are compilers and/or interpreters for pretty much every programming language available for DOS.

Before the rise of MS-DOS, the term DOS was used for a specific case of '''OS''', one that was able to use a disk drive (as opposed to things like tapes and punch cards), thus "'''disk''' operating system". There have been a number of operating systems called "DOS", besides the ones discussed here, many of which are completely different systems. (For a fairly complete list, see [[wp:List of disk operating systems|Wikipedia's list of disk operating systems]].)