DOS API: Difference between revisions

Revision as of 17:26, 11 September 2009

Revision as of 18:33, 11 September 2009

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{|class="wikitable"

!Subfunction <br />(hex)

!Service

!Parameters

!Returns

!Service

|-

|AH =0h 00

| Terminate program

|

| Never

|never

|TERMINATE PROGRAM

|-

| AH =1h 01

| Read character from [[Standard streams#Standard input (stdin)|STDIN]]

|

| AL=character read

|READ CHARACTER FROM STDIN

|-

| AH =2h 02

| Write to character to [[Standard streams#Standard input (stdout)|STDOUT]]

| DL=character

|

|WRITE CHARACTER TO STDOUT

|-

| AH =9h 09

| Write string
| DS:DX=pointer to '$' terminated string

|

|-

|WRITE STRING

| AH = 3C

| DOS 2+<br />Create or truncate file

| CX = file attributes, DS:DX -> [[C string|ASCIZ]] filename

| [[Carry flag|CF]] clear if successful ; AX = [[File descriptor|file handle]] ; CF set on error ; AX = error code<ref name="ctyme_com-rb-2778">{{cite web|title=Int 21/AH=3Ch|url=http://www.ctyme.com/intr/rb-2778.htm}} 090911 ctyme.com</ref>

|-

| AH = 3D

| DOS 2+<br />Open existing file

| AL = access and sharing modes ; DS:DX -> ASCIZ filename ; CL = attribute mask

| CF clear if successful ; AX = file handle ; CF set on error ; AX = error code<ref name="ctyme_com-rb-2779">{{cite web|title=Int 21/AH=3Dh|url=http://www.ctyme.com/intr/rb-2779.htm}} 090911 ctyme.com</ref>

|-

| AH = 3F

| DOS 2+<br />Read from file or device

| BX = [[File descriptor|file handle]] ; CX = bytes to read ;DS:DX -> buffer for data

| CF clear if successful ; AX = bytes read ; CF set on error ; AX = error code<ref name="ctyme_com-rb-2783">{{cite web|title=Int 21/AH=3Fh|url=http://www.ctyme.com/intr/rb-2783.htm}} 090911 ctyme.com</ref>

|-

| AH = 40

| DOS 2+<br />Write to file or device

| BX = file handle ; CX = bytes to write ; DS:DX -> data

| CF clear if successful ; AX = bytes written ; CF set on error ; AX = error code<ref name="ctyme_com-rb-2791">{{cite web|title=Int 21/AH=40h|url=http://www.ctyme.com/intr/rb-2791.htm}} 090911 ctyme.com</ref>

|-

| AH = 3E

| DOS 2+<br />Close file

| BX = file handle

| CF clear if successful ; AX destroyed ; CF set on error ; AX = error code<ref name="ctyme_com-rb-2782">{{cite web|title=Int 21/AH=3Eh|url=http://www.ctyme.com/intr/rb-2782.htm}} 090911 ctyme.com</ref>

|-

| AH = 42

| DOS 2+<br />Lseek - Set fileposition

| AL = origin of move, 0-start, 1-current, 2-end ; BX = file handle ; CX:DX = (signed) offset

| CF clear if successful ; DX:AX = new position in bytes from start of file ; CF set on error ; AX = error code<ref name="ctyme_com-rb-2799">{{cite web|title=Int 21/AH=42h|url=http://www.ctyme.com/intr/rb-2799.htm}} 090911 ctyme.com</ref>

|}