Note: This API call is for DOS personality only. Use Family API for portability.
INT 21H
| AH | Description | Version |
|---|---|---|
| 00H | Program terminate | 1.0+ |
| 01H | Character input | 1.0+ |
| 02H | Character output | 1.0+ |
| 03H | Auxiliary input | 1.0+ |
| 04H | Auxiliary output | 1.0+ |
| 05H | Printer output | 1.0+ |
| 06H | Direct console I/O | 1.0+ |
| 07H | Direct console input without echo | 1.0+ |
| 08H | Console input without echo | 1.0+ |
| 09H | Display string | 1.0+ |
| 0AH | Buffered keyboard input | 1.0+ |
| 0BH | Get input status | 1.0+ |
| 0CH | Flush input buffer and input | 1.0+ |
| 0DH | Disk reset | 1.0+ |
| 0EH | Set default drive | 1.0+ |
| 0FH | Open file | 1.0+ |
| 10H | Close file | 1.0+ |
| 11H | Find first file | 1.0+ |
| 12H | Find next file | 1.0+ |
| 13H | Delete file | 1.0+ |
| 14H | Sequential read | 1.0+ |
| 15H | Sequential write | 1.0+ |
| 16H | Create or truncate file | 1.0+ |
| 17H | Rename file | 1.0+ |
| 19H | Get default drive | 1.0+ |
| 1AH | Set disk transfer address | 1.0+ |
| 1BH | Get allocation info for default drive | 1.0+ |
| 1CH | Get allocation info for specified drive | 1.0+ |
| 1FH | Get disk parameter block for default drive | 1.0+ |
| 21H | Random read | 1.0+ |
| 22H | Random write | 1.0+ |
| 23H | Get file size in records | 1.0+ |
| 24H | Set random record number | 1.0+ |
| 25H | Set interrupt vector | 1.0+ |
| 26H | Create PSP | 1.0+ |
| 27H | Random block read | 1.0+ |
| 28H | Random block write | 1.0+ |
| 29H | Parse filename | 1.0+ |
| 2AH | Get date | 1.0+ |
| 2BH | Set date | 1.0+ |
| 2CH | Get time | 1.0+ |
| 2DH | Set time | 1.0+ |
| 2EH | Set verify flag | 1.0+ |
| 2FH | Get disk transfer address | 2.0+ |
| 30H | Get DOS version | 2.0+ |
| 31H | Terminate and stay resident | 2.0+ |
| 32H | Get disk parameter block for specified drive | 2.0+ |
| 33H | Extended functions | 2.0+ |
| 34H | Get InDOS flag pointer | 2.0+ |
| 35H | Get interrupt vector | 2.0+ |
| 36H | Get free disk space | 2.0+ |
| 37H | Extended functions | 2.0+ |
| 38H | Get or set country info | 2.0+ |
| 39H | Create subdirectory | 2.0+ |
| 3AH | Remove subdirectory | 2.0+ |
| 3BH | Change current directory | 2.0+ |
| 3CH | Create or truncate file | 2.0+ |
| 3DH | Open file | 2.0+ |
| 3EH | Close file | 2.0+ |
| 3FH | Read file or device | 2.0+ |
| 40H | Write file or device | 2.0+ |
| 41H | Delete file | 2.0+ |
| 42H | Move file pointer | 2.0+ |
| 43H | Get or set file attributes | 2.0+ |
| 44H | I/O control for devices | 2.0+ |
| 45H | Duplicate handle | 2.0+ |
| 46H | Redirect handle | 2.0+ |
| 47H | Get current directory | 2.0+ |
| 48H | Allocate memory | 2.0+ |
| 49H | Release memory | 2.0+ |
| 4AH | Reallocate memory | 2.0+ |
| 4BH | Execute program | 2.0+ |
| 4CH | Terminate with return code | 2.0+ |
| 4DH | Get program return code | 2.0+ |
| 4EH | Find first file | 2.0+ |
| 4FH | Find next file | 2.0+ |
| 50H | Set current PSP | 2.0+ |
| 51H | Get current PSP | 2.0+ |
| 52H | Get DOS internal pointers (SYSVARS) | 2.0+ |
| 53H | Create disk parameter block | 2.0+ |
| 54H | Get verify flag | 2.0+ |
| 55H | Create program PSP | 2.0+ |
| 56H | Rename file | 2.0+ |
| 57H | Get or set file date and time | 2.0+ |
| 58H | Get or set allocation strategy | 2.11+ |
| 59H | Get extended error info | 3.0+ |
| 5AH | Create unique file | 3.0+ |
| 5BH | Create new file | 3.0+ |
| 5CH | Lock or unlock file | 3.0+ |
| 5DH | File sharing functions | 3.0+ |
| 5EH | Network functions | 3.0+ |
| 5FH | Network redirection functions | 3.0+ |
| 60H | Qualify filename | 3.0+ |
| 61H | Reserved | 3.0+ |
| 62H | Get current PSP | 3.0+ |
| 63H | Get DBCS lead byte table pointer | 3.0+ |
| 64H | Set wait for external event flag | 3.2+ |
| 65H | Get extended country info | 3.3+ |
| 66H | Get or set code page | 3.3+ |
| 67H | Set handle count | 3.3+ |
| 68H | Commit file | 3.3+ |
| 69H | Get or set media id | 4.0+ |
| 6AH | Commit file | 4.0+ |
| 6BH | Reserved | 4.0+ |
| 6CH | Extended open/create file | 4.0+ |
| DOS API | |
|---|---|
| Process manager | INT 20H, INT 21H: 00H, 25H, 26H, 31H, 34H, 35H, 4CH, INT 22H, INT 27H, INT 28H |
| File manager | INT 25H, INT 26H, INT 21H: 0DH, 0EH, 0FH, 10H, 11H, 12H, 13H, 14H, 15H, 16H, 17H, 19H, 1AH, 1BH, 1CH, 21H, 22H, 23H, 24H, 27H, 28H, 29H, 2EH, 2FH, 32H, 3305H, 36H |
| Character Device I/O | INT 29H, INT 21H: 01H, 02H, 03H, 04H, 05H, 06H, 07H, 08H, 09H, 0AH, 0BH, 0AH, 0CH |
| Signals | INT 23H, INT 24H, INT 21H: 3300H, 3301H, 3302H |
| Memory manager | |
| Date and Time | INT 21H: 2AH, 2BH, 2CH, 2DH |
| Misc | INT 21H: 30H, 3306H, 3700H, 3701H, 3702H, 3703H |
| NLS | INT 21H: 3303H, 3304H |
