DOS API

The DOS API is an API which originated with 86-DOS and is used in MS-DOS/PC DOS and other DOS-compatible operating systems. Most calls to the DOS API are invoked using software interrupt 21h (INT 21h). By calling INT 21h with a subfunction number in the AH processor register and other parameters in other registers, various DOS services can be invoked. These include handling keyboard input, video output, disk file access, program execution, memory allocation, and various other activities. In the late 1980s, DOS extenders along with the DOS Protected Mode Interface (DPMI) allow the programs to run in either 16-bit or 32-bit protected mode and still have access to the DOS API.

21h Main DOS API 1.0+ Implemented in DOS kernel 24h Critical error handler address 1.0+ Default handler is in the command shell (usually COMMAND.COM) 27h Terminate and stay resident 1.0+ Implemented in COMMAND.COM in DOS 1.0, DOS kernel in DOS 2.0+ 2Ah Networking and critical section 3.0+ Called by DOS kernel to interface with networking software 2Dh Unused AH Description Version 02h Character output 1.0+ 05h Printer output 1.0+ 08h Console input without echo 1.0+ 0Bh Get input status 1.0+ 0Eh Set default drive 1.0+ 11h Find first file 1.0+ 14h Sequential read 1.0+ 17h Rename file 1.0+ 1Ah Set disk transfer address 1.0+ 1Dh Reserved 1.0+ 20h Reserved 1.0+ 23h Get file size in records 1.0+ 26h Create PSP 1.0+ 29h Parse filename 1.0+ 2Ch Get time 1.0+ 2Fh Get disk transfer address 2.0+ 32h Get disk parameter block for specified drive 2.0+ 35h Get interrupt vector 2.0+ 38h Get or set country info 2.0+ 3Bh Change current directory 2.0+ 3Eh Close file 2.0+ 41h Delete file 2.0+ 44h I/O control for devices 2.0+ 47h Get current directory 2.0+ 4Ah Reallocate memory 2.0+ 4Dh Get program return code 2.0+ 50h Set current PSP 2.0+ 53h Create disk parameter block 2.0+ 56h Rename file 2.0+ 59h Get extended error info 3.0+ 5Ch Lock or unlock file 3.0+ 5Fh Network redirection functions 3.0+ 62h Get current PSP 3.0+ 65h Get extended country info 3.3+ 68h Commit file 3.3+ 6Bh Reserved 4.0+ Allen, Paul; Gates, Bill; King, Adrian; Larson, Chris; Letwin, Gordon; O'Rear, Bob; Paterson, Tim; Peters, Chris; Phillips, Bruce; Reynolds, Aaron; Stillmaker, Betty; Zbikowski, Mark (1986). "Technical advisors". MS-DOS (Versions 1.0-3.2) Technical Reference Encyclopedia. By Bornstein, Howard; Bredehoeft, Lawrence; Duncan, Ray; Morris, Carol; Rose, David; Socha, John; Tomlin, Jim; Vian, Kathleen; Wolverton, Van. Beley, Jim; Preppernau, Barry; Beason, Pam; Lewis, Andrea; Rygmyr, David (eds.). Microsoft Reference Library. Vol. 1 (Original withdrawn ed.). Redmond, Washington, USA: Microsoft Press. ISBN 0-914845-69-1. LCCN 86-8640. OCLC 635600205. (xvii+1053 pages; 29 cm) (NB. This original edition contains flowcharts of the internal workings of the system. It was withdrawn by Microsoft before mass-distribution in 1986 because it contained many factual errors as well as some classified information which should not have been published. Few printed copies survived. It was replaced by a completely reworked edition in 1988. )

"},"contributor-first34":{"wt":"David"},"contributor-last34":{"wt":"Melin"},"contributor-first35":{"wt":"Charles"},"contributor-last35":{"wt":"Mergentime"},"contributor-first36":{"wt":"Randy"},"contributor-last36":{"wt":"Nevin"},"contributor-first37":{"wt":"Dan"},"contributor-last37":{"wt":"Newell"},"contributor-first38":{"wt":"Tani"},"contributor-last38":{"wt":"Newell"},"contributor-first39":{"wt":"David"},"contributor-last39":{"wt":"Norris"},"contributor-first40":{"wt":"Mike"},"contributor-last40":{"wt":"O'Leary"},"contributor-first41":{"wt":"Bob"},"contributor-last41":{"wt":"O'Rear"},"contributor-link41":{"wt":"Bob O'Rear"},"contributor-first42":{"wt":"Mike"},"contributor-last42":{"wt":"Olsson"},"contributor-first43":{"wt":"Larry"},"contributor-last43":{"wt":"Osterman"},"contributor-first44":{"wt":"Ridge"},"contributor-last44":{"wt":"Ostling"},"contributor-first45":{"wt":"Sunil"},"contributor-last45":{"wt":"Pai"},"contributor-first46":{"wt":"Tim"},"contributor-last46":{"wt":"Paterson"},"contributor-link46":{"wt":"Tim Paterson"},"contributor-first47":{"wt":"Gary"},"contributor-last47":{"wt":"Perez"},"contributor-first48":{"wt":"Chris"},"contributor-last48":{"wt":"Peters"},"contributor-first49":{"wt":"Charles"},"contributor-last49":{"wt":"Petzold"},"contributor-link49":{"wt":"Charles Petzold"},"contributor-first50":{"wt":"John"},"contributor-last50":{"wt":"Pollock"},"contributor-first51":{"wt":"Aaron"},"contributor-last51":{"wt":"Reynolds"},"contributor-link51":{"wt":"Aaron R. Reynolds"},"contributor-first52":{"wt":"Darryl"},"contributor-last52":{"wt":"Rubin"},"contributor-first53":{"wt":"Ralph"},"contributor-last53":{"wt":"Ryan"},"contributor-first54":{"wt":"Karl"},"contributor-last54":{"wt":"Schulmeisters"},"contributor-first55":{"wt":"Rajen"},"contributor-last55":{"wt":"Shah"},"contributor-first56":{"wt":"Barry"},"contributor-last56":{"wt":"Shaw"},"contributor-first57":{"wt":"Anthony"},"contributor-last57":{"wt":"Short"},"contributor-first58":{"wt":"Ben"},"contributor-last58":{"wt":"Slivka"},"contributor-first59":{"wt":"Jon"},"contributor-last59":{"wt":"Smirl"},"contributor-first60":{"wt":"Betty"},"contributor-last60":{"wt":"Stillmaker"},"contributor-first61":{"wt":"John"},"contributor-last61":{"wt":"Stoddard"},"contributor-first62":{"wt":"Dennis"},"contributor-last62":{"wt":"Tillman"},"contributor-first63":{"wt":"Greg"},"contributor-last63":{"wt":"Whitten"},"contributor-first64":{"wt":"Natalie"},"contributor-last64":{"wt":"Yount"},"contributor-first65":{"wt":"Steve"},"contributor-last65":{"wt":"Zeck"},"date":{"wt":"1988"},"edition":{"wt":"Completely reworked"},"publisher":{"wt":"[[Microsoft Press]]"},"location":{"wt":"Redmond, Washington, USA"},"isbn":{"wt":"1-55615-049-0"},"lccn":{"wt":"87-21452"},"oclc":{"wt":"16581341"}},"i":0}}]}'/>Zbikowski, Mark; Allen, Paul; Ballmer, Steve; Borman, Reuben; Borman, Rob; Butler, John; Carroll, Chuck; Chamberlain, Mark; Chell, David; Colee, Mike; Courtney, Mike; Dryfoos, Mike; Duncan, Rachel; Eckhardt, Kurt; Evans, Eric; Farmer, Rick; Gates, Bill; Geary, Michael; Griffin, Bob; Hogarth, Doug; Johnson, James W.; Kermaani, Kaamel; King, Adrian; Koch, Reed; Landowski, James; Larson, Chris; Lennon, Thomas; Lipkie, Dan; McDonald, Marc; McKinney, Bruce; Martin, Pascal; Mathers, Estelle; Matthews, Bob; Melin, David; Mergentime, Charles; Nevin, Randy; Newell, Dan; Newell, Tani; Norris, David; O'Leary, Mike; O'Rear, Bob; Olsson, Mike; Osterman, Larry; Ostling, Ridge; Pai, Sunil; Paterson, Tim; Perez, Gary; Peters, Chris; Petzold, Charles; Pollock, John; Reynolds, Aaron; Rubin, Darryl; Ryan, Ralph; Schulmeisters, Karl; Shah, Rajen; Shaw, Barry; Short, Anthony; Slivka, Ben; Smirl, Jon; Stillmaker, Betty; Stoddard, John; Tillman, Dennis; Whitten, Greg; Yount, Natalie; Zeck, Steve (1988). "Technical advisors". The MS-DOS Encyclopedia: versions 1.0 through 3.2. By Duncan, Ray; Bostwick, Steve; Burgoyne, Keith; Byers, Robert A.; Hogan, Thom; Kyle, Jim; Letwin, Gordon; Petzold, Charles; Rabinowitz, Chip; Tomlin, Jim; Wilton, Richard; Wolverton, Van; Wong, William; Woodcock, JoAnne (Completely reworked ed.). Redmond, Washington, USA: Microsoft Press. ISBN 1-55615-049-0. LCCN 87-21452. OCLC 16581341. (xix+1570 pages; 26 cm) (NB. This edition was published in 1988 after extensive rework of the withdrawn 1986 first edition by a different team of authors. )

Hogan, Thom (1991). The Programmer's PC Sourcebook. Microsoft Press. ISBN 155615321X.