DOS API: Difference between revisions

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Revision as of 09:10, 10 February 2009

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The '''MS-DOS API''' is an [[API]] used originally in [[MS-DOS]]/[[PC-DOS]], and later by other [[DOS]] systems. Most calls to the DOS API invoke [[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 areA variousmajor implementationsrevamp of the DOS API, includingwas undertaken for the release of MS-DOS, PC-DOS,2.0 DR-DOS,in FreeDOS1983, PTS-DOS,adding numerous new subfunctions to deal with file I/O using abstract "handles" and otherssupport subdirectories. The DOSIn APIthese isnew basedsubfunctions, onstrings theare usually terminated by a NUL byte ([[BIOSASCIIZ]],). and In MS-DOS routinesverion often3.1 internally(released accessin [[BIOS1985), interruptseveral call]]ssubfunctions were added for dealing with networks.

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 call]]s.

The [[DOS Protected Mode Interface]] extends the DOS API to 32-bits. The MS-DOS API is partially dependent on x86 code hence DOS cannot be ported to other architectures.

The [[DOS Protected Mode Interface]] extends the DOS API to 32-bits. The MS-DOS API is partially dependent on x86 code, hence DOS cannot be ported to other chip architectures.

==The MS-DOS API and Windows==

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==References==

*[http://www.arl.wustl.edu/~lockwood/class/cs306/books/artofasm/toc.html Description of MS-DOS services]

*''The New Peter Norton Programmaer's Guide to the IBM PC & PS/2'' by Peter Norton and Richard Wilton, Microsoft Press, 1987 ISBN 1-55615-131-4.

[[Category:DOS on IBM PC compatibles]]