AH=3DH - 8086 INT 21H

AH = 3Dh - "OPEN" - OPEN EXISTING FILE
Entry:
AL = access and sharing modes
DS:DX -> ASCIZ filename
Return:
CF clear if successful, AX = file handle
CF set on error AX = error code (01h,02h,03h,04h,05h,0Ch,56h)
Notes:
file pointer is set to start of file
file handles which are inherited from a parent also inherit sharing and access restrictions
files may be opened even if given the hidden or system attributes

Syntax

MOV AH,3DH
INT 21H

Example

MOV AH,3DH
INT 21H

Output / Return Value

Return:
    CF clear if successful, AX = file handle
    CF set on error AX = error code (01h,02h,03h,04h,05h,0Ch,56h)

Limitations

Alternatives / See Also

• Close a File
• Read from File
• Write to File

Reference