操作系统 DOS系统调用的扩充

code segment
org 100h
words db 0ah,0dh,'I am huangxiangchong. How do you do ?$'
assume cs:code

init proc far
mov ax,cs
mov ds,ax
lea dx,words
mov ah,9
int 21h
iret
init endp

begin:
mov ax,code
mov ds,ax

mov ax,seg init
mov ds,ax
mov dx,offset init
mov bx,offset init
mov al,70h
mov ah,25h ;设中断向量
int 21h


mov dx,offset begin
mov ah,31h
mov al,70h
int 21h
code ends
end begin

测试程序：（两个分开执行）
code segment
assume cs:code,ds:code
begin:
mov ax,code
mov ds,ax


int 70h

mov ah,4ch
int 21h

code ends
end begin