DOS API: Difference between revisions

Revision as of 00:35, 19 April 2008

Revision as of 00:37, 19 April 2008

Line 1:

{{Unreferenced|date=April 2008}}

The '''MS-DOS API''' is an [[API]] used in [[MS-DOS]], [[PC-DOS]] and other compatible operating systems. The DOS API is based on software interrupt 21h (int 21h). By calling int 21h with the subfunction in ah and the other parameters in other registers, one invokes various DOS services. DOS services include keyboard input, video output, disk file access, executing programs, memory allocation, and various other things. There are various implementations of the DOS API, including MS-DOS, PC-DOS, DR-DOS, FreeDOS, PTS-DOS, and others. The DOS API is based on the [[BIOS]], and [[DOS]] routines often internally access [[BIOS interrupt calls]].

[[Microsoft Windows]] versions 1.0 through 3.1 were graphical shells that ran on MS-DOS and relied on the MS-DOS API. [[Windows 9x]] was also DOS based, but used a custom version of MS-DOS mainly as a bootloader and did not use the MS-DOS API much after booting. [[Windows NT]] is not based on MS-DOS, but features a DOS emulator called [[NTVDM]]. NTVDM works by running a DOS program in [[virtual 8086 mode]] (an emulation of [[real mode]] available on [[80386]] and higher processors). [[DOSEMU]] for [[linux]] uses a similar approach.

[[DPMI]] extends the DOS API to 32-bits.

==Common DOS services==

Line 49 ⟶ 50:

==See also==

*[[BIOS interrupt call]]

*[[Comparison of x86 DOS operating systems]]

*[[DOS/4GW]]