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+
18h	Reserved	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+
1Dh	Reserved	1.0+
1Eh	Reserved	1.0+
1Fh	Get disk parameter block for default drive	1.0+
20h	Reserved	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	Get or set Ctrl-Break	2.0+
34h	Get InDOS flag pointer	2.0+
35h	Get interrupt vector	2.0+
36h	Get free disk space	2.0+
37h	Get or set switch character	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+